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  • 101.
    Arana Escobedo, André
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Gunnarsson, Oskar
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Hydraulic Energy Efficiency of Concepts on an Articulated Hauler: Design and evaluation of different hydraulic concepts with focus on energy efficiency2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This master's thesis has evaluated dierent system designs for the hydraulic system on an articulated hauler at Volvo Construction Equipment (CE). The current system suers from great losses when running on low pump displacement settings. This is due to large installed displacements as a result of regulations and market demands. New system concepts have been generated and simulations in Matlab and Amesim show that some of the concepts can be implemented in order to increase energy eciency up to 65%. However, increasing eciency does in most cases also increase cost, making some of the concepts unrealistic to implement. The suggested solution for Volvo CE is to remove one pump and allow for the fan pumps to supply oil to the steering and dumping, as described in the Displacement reduction concept. They should also examine the possibility to implement clutches further.

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  • 102.
    Arfwidsson, Oskar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Andersson, Elias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Benchmarking av industriella små och medelstora företags energiprestanda: Presentation av en metod för beräkning av energieffektiviseringsindex2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Industrisektorn står idag cirka 30 % av slutenergianvändningen i västvärlden. En betydande energibesparingspotential genom energieffektivisering av energianvändande processer har identifierats inom sektorn. Forskning har visat att det finns en särskilt stor potential för energieffektivisering hos små och medelstora företag, men att det samtidigt finns hinder som leder till att ekonomiskt rationella energieffektiviseringsåtgärder inte genomförs. Dessa hinder är bland annat kopplade till bristande kunskap om den egna energianvändningen.

    Ett verktyg för att öka medvetenheten om detta hos företagen är benchmarking av energianvändande processer, som ger dem möjlighet att jämföra sin egen energianvändning mot andra företag. Utifrån tidigare forskning och erfarenheter på området har en ny metod föreslagits för beräkning av ett energieffektiviseringsindex, vars syfte är att visa på varje företags energiprestanda i förhållande till andra företag.

    I examensarbetet genomfördes en litteraturstudie där vetenskapliga artiklar och rapporter som behandlade benchmarking av energianvändning studerades. Vidare genomfördes en intervjustudie med aktörer som har erfarenhet och inblick i företagens energiarbete, vilket inkluderade myndigheter, operativa tillsynsmyndigheter och energikartläggare. Litteratur- och intervjustudien visade att det finns en efterfrågan att kunna jämföra energianvändningen mellan industrier genom benchmarking. Benchmarking av energianvändande processer bedömdes ha särskilt god potential för att uppnå energibesparingspotentialer genom identifiering av energieffektiviseringsåtgärder.

    Den föreslagna metoden möjliggör beräkning av ett energieffektiviseringsindex som är baserat på enskilda energianvändande processer inom en industrianläggning. Detta möjliggör benchmarking av energianvändande processer såväl som hela industriella anläggningar. Metoden testades och validerades på svenska små och medelstora sågverk med underlag från energikartläggningsrapporter och Energimyndighetens databas som sammanställts i samband med det svenska stödet för energikartläggningar.

    Validering av den framtagna metoden visade att potential för energieffektiviseringar kan identifieras genom beräknande av ett energieffektiviseringsindex. Metoden förutsätter dock att jämförelser görs inom en bransch, särskilt när det gäller industriers produktionsprocesser. Vidare krävs att metoden appliceras på ytterligare branscher för att stärka metodens tillförlitlighet. Om den till Energimyndigheten inrapporterade energidatan i samband med stödet för energikartläggning i små och medelstora företag ska användas krävs ytterligare kvalitetssäkring av underlaget.

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  • 103.
    Arjoni, D. H.
    et al.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Rocha, G. C.
    Konatus, São José dos Campo, Brazil.
    Moreira, A. H.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Nicola, R. M.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Oliveira, W. R.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Silva, A. V. S.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Natal, G. S.
    TA Instituto Tecnológico de Aeronáutica, São José dos Campo, Brazil.
    Silveira, L.
    NAC, São José dos Campo, Brazil.
    Thomas, E.
    Embraer, São José dos Campo, Brazil.
    Villani, E.
    TA Instituto Tecnológico de Aeronáutica, São José dos Camp, Brazil.
    Trabasso, Luís Gonzaga
    TA Instituto Tecnológico de Aeronáutica, São José dos Camp, Brazil.
    Experimental Evaluation of the Human Performance on a RoboticFlight Simulator based on FOQA Parameters2016Ingår i: Proceedings of the Aerospace Technology Congress / [ed] Kaj Lundahl, Roland Karlsson, Björn Jonsson and Knut Övrebö, Stockholm, 2016, Vol. 1, s. 1-11Konferensbidrag (Refereegranskat)
    Abstract [en]

    The SIVOR project, currently being developed by ITA and Embraer, consists of designing andimplementing a high fidelity flight simulator based on the use of COTS industrial robots. The aim of theproject is to provide a cost-efficient and flexible platform that can be used along the design phases of theaircraft. One of the advantages of an industrial robot over the traditional Stewart platform is theavailability of a large workspace, which provides more flexibility for defining the washout filter. Thisfilter converts the aircraft dynamics into robot movements, which has a limited workspace. The mainpurpose of the flight simulator is to provide a motion feeling similar to the one imposed by the aircraftmovements in a real flight. The representativeness of the motion cue is usually evaluated in a qualitativeway by the pilots that fly the simulator. Quantitative methods to evaluate the entire range of actuation of asimulator are complex, inducing tests in fractions of the flight to increase performance. In this work, wediscuss the use of FOQA (Flight Operational Quality Assurance) as an additional quantitative tool for theevaluation of the motion cue in the SIVOR flight simulator. FOQA is a voluntary safety program fromFAA, detailed in AC-120-82. It proposes a set of parameters that can be used by airliners to analyse flightsafety and increase operational efficiency. The verification of FOQA parameters checks whether or notthe pilot complies with the standard operational procedures defined by the airliners and aircraftmanufacturers. The purpose of this work is to analyse whether or not, and to what extent, the FOQAparameters can be used to evaluate the quality of the motion cue of flight simulators. For this purpose, wedefine an experimental procedure that compares flights performed by pilots under different motionmodes. It then calculates a set of behavioural parameters that has been proposed in order to quantify howthe motion affects the inputs of the pilot. The results are submitted to ANOVA statistical analysis thatverifies the relevance of the motion factor. Finally, we discuss the capability of a FOQA basedexperiment to estimate the contribution of the motion to the realism of the flight simulation.

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    Experimental Evaluation of the Human Performance on a RoboticFlight Simulator based on FOQA Parameters
  • 104.
    Arkman, Jonas
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Boo, Christofer
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Design och dimensionering av momentskärmsstativ för provflygning av JAS39 Gripen: Konceptverifiering med hjälp av handberäkningar och FEM2013Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det här projektet har genomförts på uppdrag av Saab, med syftet att designa och dimensionera ett stativ för infästning av en momentskärm. Denna momentskärm används vid provflygning av JAS39 Gripen för att vid behov upphäva ett okontrollerat tillstånd som kan inträffa vid tester av spinnfall och högalfaflygningar.

    Det arbete som presenteras i den här rapporten är en del av ett större projekt där målet har varit att ta fram ett stativ. I den här rapporten presenteras analyser som har gjorts dels med handbokslösningar och klassisk hållfasthetslära, dels med FE-programmet Ansys för att kontrollera att det slutgiltiga konceptet uppfyller samtliga givna krav.

    Vid dimensioneringen har ett iterativt arbetssätt använts, det har byggt på att först ta fram ett grundläggande koncept och sedan förbättra detta under projektets gång. Efter varje iteration har analyser gjorts av resultatet för att verifiera stativets funktion. För att inte påverka flygegenskaperna mer än nödvändigt har det även varit viktigt att minimera stativets vikt. Projektet har resulterat i ett koncept av titanlegeringen Ti-6Al-4V med en vikt på 67,7 kg.

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  • 105.
    Arnoldsson, Joel
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Adsorption Chillers: uptake of Ethanol on Type RD Silica gel2012Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The adsorption cooling technology has the potential to replace all vapor compression based chillers in the future. So, in all over the world immense researches are going on in this field. The purpose of this report is to experimentally investigate whether ethanol could serve as a refrigerant in the technology. Compared to water it has freezing point below 0 °C (-114.1 °C) and can therefore in theory be used in refrigeration applications. The report begins with the theory regarding the adsorption cooling process, describing the cycle and parameters that affect the Coefficient of Performance (COP).In the actual experiment, adsorption between the silica gel and the ethanol vapor is studied at various pressures by maintaining isothermal conditions. An experimental apparatus (Constant Volume Variable Pressure apparatus - CVVP) was fabricated, assembled and tested for this project. After the assembly and testing, volume calibration for the apparatus was carried out as it is essential to know in further experimental calculation. All the data related with the fabrication, assembly and testing of the apparatus and the volume calibrations are presented later in this report in detail.Adsorption experiments are conducted at 301.15K, 311.15K, 321.15K and 331.15K with varying inlet pressure condition to the system and then the uptake data is calculated for each and every experiments using ideal gas equation. Subsequently, the validations of the experimental data with the standard adsorption isotherms are done. Dubinin-Astakhov is found to be the most ideal isotherm to simulate the theoretical data. Its RMSE (Root Mean Square Error) value is found to be 0.506%. It is concluded that ethanol valid option for refrigeration, but further research is needed and recommended.

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    Adsorption chillers - uptake of ethanol on type RD silica gel
  • 106.
    Arnstedt, Johanna
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik.
    Tullsson, Frida
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik.
    Förbudet mot utsläpp av toalettavfall från fritidsbåtar på svenskt vatten och dess potentiella bidrag till hållbar utveckling i Östersjön: En kvalitativ undersökning av fritidsbåtsägares syn på förbudet och förslag för ökad efterlevnad2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En av de största utmaningarna i dagens samhälle är att säkerställa hållbar utveckling, vilket ingick i FN:s sjunde milleniemål med måldatum 2015. Östersjön är ett särskilt känsligt innanhav med en hotad biologisk mångfald och en utbredd övergödningsproblematik. År 2001 gav Helcom, en samarbetsorganisation för alla Östersjöländer, rekommendationen att införa ett förbud mot utsläpp av toalettavfall från fritidsbåtar som ett steg i att begränsa tillförseln av näringsämnen till Östersjön. Den 1 april år 2015 infördes förbudet i Sverige. Under de följande månaderna blev förbudet mycket uppmärksammat i media och det har sedan dess förekommit en stor kvantitet synpunkter på förbudet. Från april till oktober 2015 inkom 182 anmälningar gällande brister i hamnars mottagande av toalettavfall till Transportstyrelsen.

    Studien syftar till att utvärdera förbudets potentiella bidrag till hållbar utveckling, att undersöka fritidsbåtsägares syn på utsläppsförbudet samt att ge förslag till förbättringar för att förbudet enklare ska kunna efterlevas för fritidsbåtsägare. Studien genomfördes med en kombination av olika metoder. Huvudmomentet utgjordes av kvalitativa intervjuer med fritidsbåtsägare. Som komplement skickades en webbenkät till 109 personer. Svarsfrekvensen beräknades till 92 procent, vilket belyser det stora engagemang som funnits i att delta i studien. Därutöver sammanställdes de brister och synpunkter som rapporterats in till Transportstyrelsen. Författarna har även deltagit i seminarier.

    Resultaten visar att majoriteten av fritidsbåtsägarna anser att förbudet är korrekt och att principen att inte släppa ut toalettavfall i Östersjön är riktig. Enligt webbenkäten skulle 64 av 99 personer tömma båtens septiktank i havet om det inte fanns någon fungerande mottagningsanordning inom deras färdväg. Situationen speglas även i förbättringsförslagen då det mest frekvent förekommande förslaget är att bygga ut nätet med mottagningsanordningar och att säkerställa att befintliga anordningar är i drift och fungerar. Fritidsbåtsägarna gav flera argument både för och emot förbudet och hade även synpunkter på förbudets utformning. Två vanligt förekommande argument för förbudet var vikten av att ta ansvar för sina egna utsläpp och den sanitära olägenheten att bada i samma vatten som någon släpper ut toalettavfall i. Tre vanliga motargument var att regleringar för andra aktörer som jordbruk, industrier och kommunala bräddavlopp bör införas innan regleringar för fritidsbåtsägare, att toalettavfallet sprids ut i en så stor volym vatten och att båtliv ska innebära frihet.

    Förbudet kan bidra till hållbar utveckling ur såväl det sociala, ekonomiska och ekologiska perspektivet trots att utsläpp av näringsämnen från fritidsbåtar utgör en mindre andel av de totala utsläppskvantiteterna. Flera av Östersjöns ekosystemtjänster hotas av övergödning, exempelvis livsmedelsproduktion, biologisk mångfald och estetiska värden. Författarna till denna rapport anser därmed att alla ekonomiskt rimliga åtgärder kan motiveras ur ett ekosystemtjänstperspektiv för att inte riskera kommande generationers möjlighet att uppfylla sina behov. Förbudet bidrar ytterligare till den sociala dimensionen av hållbarhet genom att det medför en ökad medvetenhet kring problematiken relaterad till Östersjöns miljötillstånd. Författarna rekommenderar i första hand att det byggs flera landtoaletter och sugtömningsanordningar. Placeringen av dessa bör ses över av en aktör med ett övergripande ansvar. Spridning av information kring var det finns utplacerade mottagningsanordningar rekommenderas, exempelvis via en applikation i mobiltelefonen och utmärkning på sjökort. Därutöver bör information om vilka regler som gäller för fritidsbåtsägare och hamnansvariga spridas, samt tydliga användarinstruktioner på mottagningsanordningarna vara mer frekvent förekommande.

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  • 107.
    Arrell, Douglas
    et al.
    Siemens Industrial Turbomachinery AB, Finspång.
    Hasselqvist, Magnus
    Siemens Industrial Turbomachinery AB, Finspång.
    Sommer, C
    ABB Technology Ldt, Heidelberg, Germany.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    On TMF damage, degradation effects, and the associated TMin influence on TMF test results in γ/γ′ alloys2004Ingår i: Proceedings of the International Symposium on Superalloys / [ed] Green K.A., Pollock T.M., Harada H., Howson T.E., Reed R.C., Schirra J.J., Walston S., Warrendale, PA, USA: The Minerals, Metals and Materials Society, TMS , 2004, s. 291-294Konferensbidrag (Övrigt vetenskapligt)
  • 108.
    Arustei, Adrian
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system.
    Development of a System Identification Tool for Subscale Flight Testing2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Aircraft system identification has been widely used to this day in applications like control law design, building simulators or extending flight envelopes. It can also be utilized for determining flight-mechanical characteristics in the preliminary design phase of a flight vehicle. In this thesis, three common time-domain methods were implemented in MATLAB for determining the aerodynamic derivatives of a subscale aircraft. For parameter estimation, the equation-error method is quick, robust and can provide good parameter estimates on its own. The output-error method is computationally intensive but keeps account of the aircraft's evolution in time, being more suitable for fine-tuning predictive models. A new model structure is identified using multivariate orthogonal functions with a predicted squared error stopping criteria. This method is based on linear regression (equation-error).

    The code written is flexible and can also be used for other aircraft and with other aerodynamic models. Simulations are compared with experimental data from a previous flight test campaign for validation. In the future, this tool may help taking decisions in conceptual design after a prototype is tested.

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  • 109.
    Arvola, Mattias
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Filosofiska fakulteten.
    Blomkvist, Johan
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten.
    Wahlman, Fredrik
    Linköpings universitet.
    Lifelogging in User Experience Research: Supporting Recall and Improving Data Richness2017Ingår i: The Design Journal, ISSN 1460-6925, E-ISSN 1756-3062, Vol. 20, s. S3954-S3965Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of lifelogging is to help users collect data for self-monitoring and reflection. We have in this study explored how lifelogging technology (a camera and a heart rate monitor) can change user experience (UX) research, and we describe a novel approach. Data was collected for three days with four participants, and a 4-6-hours co-creation workshop with stimulated recall interview was held with each of them to create an experience timeline. The timeline includes selfreported key experiences, lifelog stimulated experiences, heart rate, decisions, and valence. The results show that the number of experiences in the timeline that come from data points stimulated by the lifelogging, are as many as the self-reported data points. Lessons learned include that the use of lifelogging produces highly detailed UX research, but it is very time consuming, due to the sheer amount of data.

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  • 110.
    Asghar, Raja Babar
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik.
    Optimization as a Thermodynamic System2010Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    As we know that nature made the things optimized in all point of views, also it is supposed that nature works under some evolutionary process.

    Since there was no such Evolutionary Structural Optimization (ESO) method having strong mathematical background, that’s why these are not much reliable. The purpose of this thesis work is a little effort to introduce such an ESO method having a strong mathematical background.

    In this thesis work Optimization as a thermodynamic system, we are introducing a new method for topology optimization by using concept of Free Energy and Dissipation Potential from non-smooth thermodynamics system. For better understanding we may call it as Evolutionary Structural Topology Optimization (ESTO), and this project work is done in the following steps.

    An evolution problem is formulated in terms of free energy and dissipation potential for a non-smooth thermodynamical system. Free energy is taken as an objective function for a general structural optimization problem. Derivation of a well posed evolution problem for which evolution is such that objective function always decreases. An optimality criteria method is derived for given evolution problem and it is implemented in a FEM program TRINITAS. And the behaviour of the so called evolutionary parameters such as Forward and Backward plastic constants is analyzed.

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    FULLTEXT01
  • 111.
    Ask, Per
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Enberg, Anders
    Öberg, Åke
    Spånberg, Anders
    A SHORT-TIME-DELAY URINARY FLOWMETER1985Ingår i: Neurourology and Urodynamics, ISSN 0733-2467, E-ISSN 1520-6777, Vol. 4, nr 3, s. 247-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A urinary flowmeter has been designed, using a quickly rotating disc and a balance principle. The flowmeter has a fast and accurate response to changing flows. The time delay of the flowmeter is less than about 0.25 s. The improved accuracy in recording urinary flow using the presented flowmeter should make it possible to extract more information from the detrusor pressure and urinary flow relations, relevant for assessing lower urinary tract function.

  • 112.
    Ask, Per
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    ENGVALL, J
    Loyd, Dan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Wranne, Bengt
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    THEORETICAL AND EXPERIMENTAL-ANALYSIS OF AORTIC COARCTATION1989Ingår i: IMAGES OF THE TWENTY-FIRST CENTURY, PTS 1-6, 1989, Vol. 11, s. 103-103Konferensbidrag (Refereegranskat)
    Abstract [en]

    Aortic coarctation, which could severely influence the haemodynamic conditions of the body, is discussed. A theory has been developed which relates the pressure drop over the coarctation to the flow. This theory indicates that the pressure drop across the actual coarctation is related to the flow squared. For the collateral flow the expected pressure drop is either linearly or quadratically related to the flow. Model experiments and patient data support the present theoretical model

  • 113.
    Ask, Per
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Hök, B
    Loyd, Dan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Teriö, H
    Bio-acoustic signals from stenotic tube flow: state of the art and perspectives for future methodological development.1995Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 33, nr 5, s. 669-675Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To study the degree of stenosis from the acoustic signal generated by the turbulent flow in a stenotic vessel, so-called phonoangiography was first suggested over 20 years ago. A reason for the limited use of the technique today may be that, in the early work, the theory of how to relate the spectrum of the acoustic signal to the degree of the stenosis was not clear. However, during the last decade, the theoretical basis for this and other biological tube flow applications has been clarified. Now there is also easy access to computers for frequency analysis. A further explanation for the limited diagnostic use of bio-acoustic techniques for tube flow is the strong competition from ultrasound Doppler techniques. In the future, however, applications may be expected in biological tube flow where the non-invasive, simple and inexpensive bio-acoustic techniques will have a definite role as a diagnostic method.

  • 114.
    Ask, Per
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Hök, Bertil
    PRESSURE MEASUREMENT TECHNIQUES IN URODYNAMIC INVESTIGATIONS1990Ingår i: Neurourology and Urodynamics, ISSN 0733-2467, E-ISSN 1520-6777, Vol. 9, nr 1, s. 1-15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is apparent that the use of accurate pressure measurement techniques is essential for the outcome of urodynamic investigations. The aim of this paper is to estimate the demands on urodynamic pressure measurements and to review the properties of various techniques used. For the infused catheter technique, the dynamic properties are very much dependent on the complicance of the infusion system. With optimal infusion, the bandwidth and the pressure rise rate seem to be sufficient for most applications. Intraluminal microtransducers have a high bandwidth, but a certain fiber optic transducer cannot accurately measure mechanical pressure in the collapsed urethra. The principal differences in measuring hydrostatic pressure between the infused catheter technique and microtransducers should be observed. Flexion artefacts are a problem when measuring urethral pressure profiles. Newly developed transducers may offer a solution to this problem.

  • 115.
    Ask, Per
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Tibbling, Lita
    Evaluation of a new method for abdominal compression for use in oesophageal investigation.1982Ingår i: Scandinavian Journal of Gastroenterology, ISSN 0036-5521, E-ISSN 1502-7708, Vol. 17, nr 2, s. 269-272Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of conventional extra-abdominal compression with a constant cuff pressure was shown to give various pressures intra-abdominally in different subjects. A feedback system was therefore used, in which the extra-abdominal pressure is controlled by the intra-abdominal pressure. For an intra-abdominal pressure increase of 15 mm Hg the external cuff pressure in 20 subjects varied from 21 to 98 mm Hg. There was, however, an almost linear relationship between increased intra-abdominal pressure and cuff pressure. The extra-abdominal pressure required to obtain a certain intra-abdominal pressure also varied with the size of the cuff. To obtain relevant and comparable results in studies of hiatal incompetence and gastro-oesophageal reflux, the feedback system is recommended and the size of the intra-abdominal cuff should be stated.

  • 116.
    Asp, Erik
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion.
    Järlstig, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion.
    Planning interior lighting in a truck cab: A thesis in visual ergonomics2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A long-haulage truck cab from Scania is an environment that involves various activities and combines a working place with compact living which sets different requirements on the lighting environment depending on the activity. Truck drivers have different requirements in means of visual ergonomics and preference on the lighting design. A conclusion in this thesis is that different user in various activities sets different requirements on lighting design in a truck cab. 

    Lighting planning in a truck cab with new lighting technologies such as LED (Light Emitting Diode) and OLED (Organic Light Emitting Diode) stands for a paradigm shift in lighting planning and lighting design. The new technologies enables more integration in the interior, more diverse lighting which means more effort is needed to succeed in good visual ergonomics, light distribution, aesthetic expression and branding. 

    Studies have shown that by blue enriched light can be used as a tool to affect the humans’ sleep-awake rhythm. With the new paradigm shift with LED and OLED comes an opportunity to change the colour temperature of the lighting and use blue-enriched light as a tool to possibly create a better working environment for shift working truck drivers using warmer light at night and colder light in the morning. 

    In this thesis two main studies has been conducted, the first was regarding product and user knowledge and the second was a lighting study. From these studies we have concluded three analyses and suggested a lighting planning guide for Scania that takes into account future lighting planning with new technology for a better working environment for long-haulage truck drivers.

    Ladda ner fulltext (pdf)
    Planning interior lighting in a truck cab
  • 117.
    Assis Lana e Cruz, Igor
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Energy and material balances of wastewater treatment, including biogas production, at a recycled board mill2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Challenges surrounding energy have gained increased attention, which is not least reflected in the 2030 Agenda for Sustainable Development and the Sustainable Development Goals (SDGs). Energy issues have also become a pressing matter for most countries in the last decades. The reasons for this are not only related to the effects of the emission of greenhouse gases (GHG) from fossil fuels and their impact in climate change, but also span through other issues such as security of energy supply with geopolitical considerations and competitiveness of industry. To address these issues, a collection of public policies ranging from the international to local levels have been implemented.

    Sweden has historically had lower energy prices than its European counterparts, which has resulted in its industry having a relatively higher share of electricity in the total energy use by industry. The share of electricity accounts for 35% of total energy use in Swedish industry. This has led to efficiency measures being overlooked by industry, and the pulp and paper industry is by far the biggest energy user, with a share of 51% of the total energy use by industry. The variation of energy prices, and particularly electricity prices have obvious implications on the competitiveness of this sector.

    Production of biogas in pulp and paper mills has been gaining attention, and is now the target of an increasing number of scientific studies. The interest for this industry is not only related to security of energy supply and the environmental performance of the biogas itself, but there are also considerations regarding the biogas plant as an alternative to treat the large flows of wastewaters and other waste stream in this sector. There is an estimated biogas production potential of 1 TWh within this industry in Sweden, which accounts for 60% of the current biogas production in the country.

    Pulp and paper mills commonly rely on aerated biological treatment to deal with waste streams with high organic content This biological process has a high energy demand, and the integration of an anaerobic treatment, along with the use of the biogas for heat and electricity can yield a net positive energy recovery for the combined plant.

    This project analyses the current energy and material performance of an anaerobic biological treatment combined with an aerobic biological treatment in a recycled board mill. The anaerobic treatment is performed upstream of the aerobic one and removes most of the chemical oxygen demand of the wastewater.

    Energy and material balances for the plant are presented, and a comparison of the wastewater treatment plant running before and after the start-up of the biogas plant is made. The plant operation with the anaerobic digestion has shown an increased energy use of 9.4% coupled to an increased flow of wastewater of 7.7%. The average biogas production is 72 Nm³/h, which accounts for 440 kWh and is currently being flared. The introduction of AD has largely decrease the organic load in the aerobic treatment, by nearly 50%. This project ends with an optimisation model implemented with the optimisation tool reMIND to investigate potential optimisation strategies for the operation of the combined plant. The model has shown to be adequate to describe electricity use with mean error below 10%. For the biogas production, the mean error was of 16%.

    Ladda ner fulltext (pdf)
    Thesis report Igor Cruz
  • 118.
    Athanasiou, Vasileios
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Estimation and modelling of fMRI BOLD response2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    One of the current topics of research in neuroimaging techniques is related to explaining and modelling the Blood Oxygen Level Dependent (BOLD) responses. BOLD responses are estimated by processing functional Magnetic Resonance Imaging (fMRI) data. BOLD responses are caused by hemodynamic responses to neural activity which alter the levels of blood oxygenation at local brain regions. The main aims of the current thesis were to i) develop and examine methods regarding BOLD response estimation from the visual cortex and the frontal cortex of human brain and to ii) develop a model in order to explain the physiological mechanisms which cause the estimated BOLD responses.

    In order to satisfy the main aims, fMRI data were provided by the Center of Medical Imaging and Visualization (CMIV). The provided fMRI data consist of fMRI brain measurements of twelve healthy human subjects who were subjected to visual stimulation. By processing the fMRI data, Regions Of Interest (ROIs) were extracted at the anatomical sites of the visual cortex and the frontal cortex. Afterwards, the fMRI data were manipulated in order to extract BOLD responses from the visual cortex and the frontal cortex. Various methods were developed and compared in terms of which technique provided well representative BOLD responses.       

    Subsequently, a model was developed by using software Wolfram Mathematica 9 in order to explain the physiological mechanisms of the estimated BOLD responses at the visual and the frontal cortex. The model aimed to solve for oxygen concentration in blood plasma as blood flows from the arterial part to the venous part of the blood circulation system through a capillary. Oxygen outward diffusion through the capillary wall and oxygen concentration at the extravascular environment were modelled as well. Blood plasma oxygen concentration was turned into hemoglobin oxygen saturation (Sa ) through hemoglobin oxygen dissociation curve and Henry’s law for gases. As a result, the Sa  was estimated through modelling for oxygen concentration in blood plasma. Finally, the developed model ended to a system with input the fractional change of Cerebral Blood Flow (CBF) velocity and Cerebral Metabolic Rate of Oxygen (CMR ) and as output a proportional signal to the BOLD response. By simulating for different scenarios of fractional changes of CBF velocity and CMR  and by comparing the resulted BOLD responses to the estimated ones, it was attempted to explain for the physiological mechanisms which caused the BOLD responses at the anatomical sites of the visual and frontal cortex.

    Ladda ner (pdf)
    BOLD response
  • 119.
    Attervall, Sebastian
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    Gustafsson, Nichlas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    Styrning och nödbroms av ModuLith2008Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [sv]

    Syftet med detta projekt är att få ett fungerande automatiskt styrsystem och en variabel broms med nödbromsfunktion till en fyrhjuling som ska bli ett hjälpmedel i militära situationer. En projektgrupp bestående av Sebastian Attervall och Nichlas Gustafsson fick i uppgift av beställare Jonas Nygårds att ta fram ett system som ska kunna manövrera en fyrhjuling utan att en människa är inblandad. På detta vis ska den fungera helt automatiskt med hjälp av sensorer, kameror och datorer. Projektgruppen fick även i uppgift att ta fram en broms som ska kunna fungera utan inblandning av en människa. Den ska även kunna fungera som en nödbroms om systemet skulle strejka. Projektgruppen har löst de uppgifter som de har blivit tilldelade med hjälp av David G. Ullmans konstruktionsmetodik. Det system som tillslut valdes åt styrenheten blev ett system där momentet som vrider styrstången skapas med hjälp av en DC motor på 48 V och 250 W. Efter motorn sätts en planetväxel för att öka momentet. Som överföring av momentet från planetväxeln till styrstången används kedjedrift, detta på grund av att kedjan klarar av att ta upp de krafter som uppstår. En slirkoppling finns även med mellan planetväxeln och kedjedriften för att inte motorn och planetväxeln ska ta stryk vid överbelastning. Hela detta system övervakas med rotationsgivare vid motorn och styrstången så att inget fel uppstår. Konstruktionen för bromsen blev tillslut en lösning där de befintliga trumbromsarna på framhjulen används. För att bromsen ska kunna fungera utan inblandning av en människa har projektgruppen valt ett system bestående av ett linjärt ställdon, en elektromagnet och en fjäder. Systemet fungerar på så sätt att fjädern trycks ihop och en kraft uppstår. Denna kraft kommer att spänna bromsvajern så trumbromsen låser sig. Men för att inte trumbromsen ska ligga i hela tiden valde projektgruppen att använda sig av ett ställdon för att trycka ihop fjädern ytterligare så att vajern slaknar och bromskraften försvinner. För att nödbromsfunktionen ska fungera sattes en elektromagnet mellan ställdonet och fjädern. Om fyrhjulingen skulle bli strömlös släpper elektromagneten och fjädern drar åt bromsvajern. Även detta system kommer att övervakas av givare och i detta fall av en linjärgivare.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 120.
    Axelsson, Anders
    Linköpings universitet, Institutionen för konstruktions- och produktionsteknik.
    Validering av BME - ett verktyg för kartläggning av belastningsergonomi2006Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [sv]

    I Volvo Personvagnars tillverkningsanläggning i Torslanda utanför Göteborg tillverkas personbilar av flera modeller och en mängd olika varianter av varje modell. I dagsläget är produktivitetskraven höga vilket medför risker för belastningsbesvär eller skador för

    operatörerna som monterar ihop bilen. Således blir belastningsergonomi en viktig del i arbetsmiljöarbetet.

    Man har på Volvo Personvagnars slutmonteringsanläggning i Torslanda utvecklat en beräkningsmodell för att beskriva belastningsergonomin i tillverkningen som man kallar BME (Beräknings Modell Ergonomi). Problemet består i att utvärdera validiteten hos BME utifrån ett

    personalekonomiskt perspektiv, det vill säga huruvida kostnader relaterade till sjukfrånvaro,sjukskrivningar, rehabilitering, personalomsättning och omplaceringar kan knytas till belastningsergonomi med hjälp av BME. Genom litteraturstudier, undersökningar om hur den belastningsergonomiska situationen förändrats sedan BME infördes samt genom studier av hur sjukdomsbilden ser ut kunde samband ställas upp mellan belastningsergonomisk tyngd och

    förekomst av skador.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 121.
    Axelsson, Daniel
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    Design and Development of a Spray Booth2008Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    As a part of a more extensive project of developing a new finishing line at the Bolivian door manufacturer Tecno Carpinteria San Pedro this thesis presents the development process for a special designed spray booth. The thesis covers every phase from a product idea to a final concept design.

    Working with finishing of furniture and other wooden products can effect the workers health in a negative way and damage the environment. The final result of the manufactured door is also depending on the how well the ventilation system in the working area is. Because of these reasons it is important to use safety equipment and a good ventilation system in the working area. As a part of this new finishing line San Pedro is in need of a special designed spray booth to control the spread of paint particles and other hazard substances that is a result of the finishing process.

    Together with the consultant firm CADEFOR a spray booth is designed and a proposal design is presented in this thesis. The result is a design built up with a dry filter solution together with an extractor that creates a cross draft airflow towards the rear part of the spray booth. The result of the project together with some recommendations of increasing the capacity in the finishing line are also presented.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 122.
    Axin, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Arbetshydraulik i mobila maskiner2015Konferensbidrag (Refereegranskat)
    Abstract [sv]

    I mobila maskiner finns en mängd olika systemtyper för arbetshydrauliken. Det vanligaste är fortfarande det kostnadseffektivaoch robusta öppet-centrum systemet med fast pump. Det ger operatören en mjuk styrning med hög dämpning. Ennackdel är dock den låga energieffektiviteten. Under de senaste decennierna har det lastkännande systemet blivit mer ochmer populärt. Energieffektiviteten i detta system är högre även om tryck och flöde varierar stort över tid och mellan olikafunktioner. En nackdel är dock att systemets dämpning är låg. Det finns ett antal olika systemtyper som kombinerar en mjukstyrning med relativt hög energieffektivitet. Nyckeln är att begränsa flödet genom det öppna centrumet i riktningsventilen.Detta kan göras med en variabel tryckstyrd pump som regleras så att öppet-centrum flödet hålls på en konstant nivå. Alternativetär en flödesstyrd pump som styrs direkt från operatörens joystickkommandon eller via flödet i det öppna centrumet. Iden här artikeln görs en jämförande analys av olika systemtyper för arbetshydrauliken i mobila maskiner. Fokus ligger påenergieffektivitet, dynamiska egenskaper och pumpreglering. En genomgång av mer avancerade systemtyper såsom individuellastrypställen och pumpstyrda aktuatorer har också gjorts.

    Ladda ner fulltext (pdf)
    fulltext
  • 123. Beställ onlineKöp publikationen >>
    Axin, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Fluid Power Systems for Mobile Applications: with a Focus on Energy Efficiency and Dynamic Characteristics2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis studies an innovative working hydraulic system design for mobile applications. The purpose is to improve the energy efficiency and the dynamic characteristics compared to load sensing systems without increasing the complexity or adding additional components.

    The system analysed in this thesis is referred to as flow control. The fundamental difference compared to load sensing systems is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency since the pressure difference between pump and load is given by the system resistance rather than a prescribed pump pressure margin. High power savings are possible especially at medium flow rates.

    Furthermore, load sensing systems suffer from poor dynamic characteristics since the pump is operated in a closed loop control mode. This might result in an oscillatory behaviour. Flow control systems have no stability issues attached to the load pressure feedback since there is none.

    Pressure compensators are key components in flow control systems. This thesis addresses the flow matching problem which occurs when using conventional compensators in combination with a flow controlled pump. Flow sharing pressure compensators solve this problem since the pump flow will be distributed between all active functions. A novel control approach where the directional valve is controlled without affecting the cylinder velocity with the objective of optimizing the damping is proposed.

    In this research, both theoretical studies and practical implementations demonstrate the capability of flow control systems. Experiments show a reduced pump pressure margin and energy saving possibilities in a short loading cycle for a wheel loader application.

    Delarbeten
    1. Energy Efficient Load Adapting System Without Load Sensing: Design and Evaluation
    Öppna denna publikation i ny flik eller fönster >>Energy Efficient Load Adapting System Without Load Sensing: Design and Evaluation
    2009 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    In load sensing systems, the pump pressure is controlled in a closed loop control mode. In this paper, a system solution where the displacement of the pump is controlled directly from the operator's demand is studied. Both the stability and the response is thereby improved. It also implies a better energy efficiency since the pump pressure will be adapted according to the point of operation with no additional pressure margin needed. In some mobile applications, pressure compensation is required to avoid load interference. When using common pre compensators in a displacement controlled system, the pump and the valve will both control the flow. A better solution would be to control the flow by the pump and utilize the valve as a flow divider. This can be achieved by using flow sharing compensators. It also allows further energy savings since the maximum restriction area of the main spool at one of the loads can be utilized independent of the flow delivered by the pump. This paper addresses the problem with using common pre compensators in displacement controlled systems and analyses and compares both a traditional load sensing system and an open controlled pump solution with flow sharing compensators. Measurements on a wheel loader application equipped with the system presented in this paper shows a decreased energy consumption of 14 % for the working hydraulics compared to a load sensing system during a short loading cycle, provided that the pump is not saturated.

    Ort, förlag, år, upplaga, sidor
    Linköping: , 2009
    Nyckelord
    fluid power, mobile systems, LS systems, pre compensation, energy efficiency, flow sharing
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-52691 (URN)
    Konferens
    11th Scandinavian International Conference on Fluid Power, SICFP'09, June 2-4, Linköping, Sweden
    Tillgänglig från: 2010-01-08 Skapad: 2010-01-08 Senast uppdaterad: 2015-08-31Bibliografiskt granskad
    2. Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems
    Öppna denna publikation i ny flik eller fönster >>Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems
    2011 (Engelska)Ingår i: The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11: Volume 2 / [ed] Harri Sairiala & Kari T. Koskinen, 2011, s. 223-238Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Interest has increased in flow controlled systems in the field of mobile fluid power. The capital distinction between traditional load-sensing (LS) systems and flow controlled systems is that the pump is controlled based on the operator’s total flow demand rather than maintaining a certain pressure margin over the maximum load pressure. One of the main advantages of flow controlled systems is the absence of the feedback of the highest load pressure to the pump controller. In this paper, a dynamic analysis is performed where flow controlled and LS systems are compared. It is shown how instability can occur in LS systems due to the pump controller and proven that no such instability properties are present in flow controlled systems. A drawback with one type of flow controlled system is that the highest load dynamically will disturb the lighter loads. This paper shows a novel way to optimize the damping in such systems by controlling the opening position of the directional valve independently of the flow. The mentioned disturbance between the highest load to the others can thereby be reduced.

    Nyckelord
    Flow control, load sensing, dynamic analysis, stability, damping
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-68636 (URN)978-952-15-2519-3 (ISBN)
    Konferens
    The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11, May 18-20, 2011 Tampere, Finland
    Tillgänglig från: 2011-05-25 Skapad: 2011-05-25 Senast uppdaterad: 2015-09-07
    3. Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification
    Öppna denna publikation i ny flik eller fönster >>Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification
    2012 (Engelska)Ingår i: 8th International Fluid Power Conference Dresden: "Fluid Power Drives!", 2012, Vol. 1, s. 579-591Konferensbidrag, Enbart muntlig presentation (Övrigt vetenskapligt)
    Abstract [en]

    This paper analyses the damping of a flow controlled cylinder with a mass load and an outlet orifice. By using linear models, a mathematical expression for the damping is derived. It is shown that the volumes on each side of the piston have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension; both smaller and larger orifice areas give low damping independently of the size of the volumes. In this paper a design is proposed of the outlet orifice area that optimizes the damping of the system. Experimental results which confirm the theoretical expectations are also presented. The conclusions are that without an outlet orifice, the hydraulic system will not contribute with any damping at all. Furthermore, large dead volumes in the cylinder will increase the damping, but at the expense of the system’s efficiency.

    Nyckelord
    Damping, compensator, outlet orifice, efficiency
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-76878 (URN)
    Konferens
    8th International Fluid Power Conference, March 26 - 28, 2012, Dresden
    Tillgänglig från: 2012-04-23 Skapad: 2012-04-23 Senast uppdaterad: 2015-09-07
    Ladda ner fulltext (pdf)
    Fluid Power Systems for Mobile Applications: with a Focus on Energy Efficiency and Dynamic Characteristic
    Ladda ner (pdf)
    omslag
  • 124. Beställ onlineKöp publikationen >>
    Axin, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Mobile Working Hydraulic System Dynamics2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with innovative working hydraulic systems for mobile machines. Flow control systems are studied as an alternative to load sensing. The fundamental difference is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency and there is no load pressure feedback causing stability issues. Experimental results show a reduced pump pressure margin and energy saving potential for a wheel loader application.

    The damping contribution from the inlet and outlet orifice in directional valves is studied. Design rules are developed and verified by experiments.

    A novel system architecture is proposed where flow control, load sensing and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. Experiments show that it is possible to avoid unnecessary energy losses while improving system response and increasing stability margins compared to load sensing. Static and dynamic differences between different control modes are also demonstrated experimentally.

    Delarbeten
    1. Flow versus pressure control of pumps in mobile hydraulic systems
    Öppna denna publikation i ny flik eller fönster >>Flow versus pressure control of pumps in mobile hydraulic systems
    2014 (Engelska)Ingår i: Proceedings of the Institution of mechanical engineers. Part I, journal of systems and control engineering, ISSN 0959-6518, E-ISSN 2041-3041, Vol. 228, nr 4, s. 245-256Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    This work studies an innovative working hydraulic system design for mobile applications, referred to as flow control. The fundamental difference compared to load-sensing systems is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency since the pressure difference between pump and load is given by the system resistance rather than a prescribed pump pressure margin. Furthermore, load-sensing systems suffer from poor dynamic characteristics since the pump is operated in a closed-loop control mode. This might result in an oscillatory behaviour. Flow control systems have no stability issues attached to the load pressure feedback since there is none. This allows the pump to be designed to meet the response requirements without considering system stability. Pressure compensators are key components in flow control systems. This study addresses the flow matching problem which occurs when using traditional compensators in combination with a flow-controlled pump. Flow sharing pressure compensators solve this problem since the pump flow will be distributed between all active functions. Simulation results and measurements on a wheel loader application demonstrate the energy-saving potentials and the dynamic improvements for the flow control system.

    Ort, förlag, år, upplaga, sidor
    Sage Publications, 2014
    Nyckelord
    Hydraulics, flow control, load-sensing, mobile systems, energy efficiency, dynamic characteristics, compensators
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-105796 (URN)10.1177/0959651813512820 (DOI)000333799100005 ()
    Tillgänglig från: 2014-04-07 Skapad: 2014-04-07 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
    2. Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems
    Öppna denna publikation i ny flik eller fönster >>Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems
    2011 (Engelska)Ingår i: The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11: Volume 2 / [ed] Harri Sairiala & Kari T. Koskinen, 2011, s. 223-238Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Interest has increased in flow controlled systems in the field of mobile fluid power. The capital distinction between traditional load-sensing (LS) systems and flow controlled systems is that the pump is controlled based on the operator’s total flow demand rather than maintaining a certain pressure margin over the maximum load pressure. One of the main advantages of flow controlled systems is the absence of the feedback of the highest load pressure to the pump controller. In this paper, a dynamic analysis is performed where flow controlled and LS systems are compared. It is shown how instability can occur in LS systems due to the pump controller and proven that no such instability properties are present in flow controlled systems. A drawback with one type of flow controlled system is that the highest load dynamically will disturb the lighter loads. This paper shows a novel way to optimize the damping in such systems by controlling the opening position of the directional valve independently of the flow. The mentioned disturbance between the highest load to the others can thereby be reduced.

    Nyckelord
    Flow control, load sensing, dynamic analysis, stability, damping
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-68636 (URN)978-952-15-2519-3 (ISBN)
    Konferens
    The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11, May 18-20, 2011 Tampere, Finland
    Tillgänglig från: 2011-05-25 Skapad: 2011-05-25 Senast uppdaterad: 2015-09-07
    3. Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification
    Öppna denna publikation i ny flik eller fönster >>Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification
    2012 (Engelska)Ingår i: 8th International Fluid Power Conference Dresden: "Fluid Power Drives!", 2012, Vol. 1, s. 579-591Konferensbidrag, Enbart muntlig presentation (Övrigt vetenskapligt)
    Abstract [en]

    This paper analyses the damping of a flow controlled cylinder with a mass load and an outlet orifice. By using linear models, a mathematical expression for the damping is derived. It is shown that the volumes on each side of the piston have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension; both smaller and larger orifice areas give low damping independently of the size of the volumes. In this paper a design is proposed of the outlet orifice area that optimizes the damping of the system. Experimental results which confirm the theoretical expectations are also presented. The conclusions are that without an outlet orifice, the hydraulic system will not contribute with any damping at all. Furthermore, large dead volumes in the cylinder will increase the damping, but at the expense of the system’s efficiency.

    Nyckelord
    Damping, compensator, outlet orifice, efficiency
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-76878 (URN)
    Konferens
    8th International Fluid Power Conference, March 26 - 28, 2012, Dresden
    Tillgänglig från: 2012-04-23 Skapad: 2012-04-23 Senast uppdaterad: 2015-09-07
    4. A Hybrid of Pressure and Flow Control in Mobile Hydraulic Systems
    Öppna denna publikation i ny flik eller fönster >>A Hybrid of Pressure and Flow Control in Mobile Hydraulic Systems
    2014 (Engelska)Ingår i: 9th InternationalFluid Power Conference (IFK). Vol. 1. Aachen, Germany, 24-26 March 2014 / [ed] Hubertus Murrenhoff, 2014, s. 190-201Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper presents a hybrid pump controller approach for mobile hydraulic systems, influenced by both pressure and flow. The controller is tuneable to be able to set the order of importance of the pressure and flow controller, respectively. It is thus possible to realize a load sensing system, a flow control system or a mix of the two. Using a low load pressure feedback gain and a high flow control gain, a system emerges with high energy efficiency, fast system response, high stability margins and no flow matching issues. In this paper, both theoretical studies and practical implementations demonstrate the capability of a hybrid pump control approach.

    Nyckelord
    Mobile hydraulics, pressure control, flow control, energy efficiency, dynamics
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-105794 (URN)978-3-9816480-0-3 (ISBN)
    Konferens
    9th International Fluid Power Conference (IFK), 24-26 March 2014, Aachen, Germany
    Tillgänglig från: 2014-04-07 Skapad: 2014-04-07 Senast uppdaterad: 2015-09-07Bibliografiskt granskad
    5. Energy Efficient Fluid Power System for Mobile Machines with Open-centre Characteristics
    Öppna denna publikation i ny flik eller fönster >>Energy Efficient Fluid Power System for Mobile Machines with Open-centre Characteristics
    2014 (Engelska)Ingår i: 9th JFPS International Symposium on Fluid Power. Matsue, Japan, 28-31 October 2014, The Japan Fluid Power System Society , 2014, s. 452-459Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
    Abstract [en]

    This paper presents a flexible and energy efficient system solution which mimics the behaviour of an open-centre system. An electro-hydraulic variable displacement pump and closed-centre valves are used. Instead of having a flow in the open-centre gallery, that flow is calculated using a pressure sensor and a valve model. The variable pump is then controlled in order to only deliver the flow that would go to the actual loads. It is also possible for the operator to decide how much load dependency there should be. The extreme case is not having any load dependency at all, resulting in a system where the pump displacement setting is controlled according to the sum of all requested load flows. It is thus possible to realize a system design with open-centre characteristics, a flow control system or something in between. Each operator can thereby get their optimal control characteristic while having high energy efficiency.

    Ort, förlag, år, upplaga, sidor
    The Japan Fluid Power System Society, 2014
    Nyckelord
    Mobile hydraulics, energy efficiency, dynamics, damping
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-111819 (URN)4-931070-10-8 (ISBN)
    Konferens
    9th JFPS International Symposium on Fluid Power, Shimane, Japan, 28-31 October 2014
    Tillgänglig från: 2014-11-04 Skapad: 2014-11-04 Senast uppdaterad: 2016-05-17Bibliografiskt granskad
    6. A Flexible Working Hydraulic System for Mobile Machines
    Öppna denna publikation i ny flik eller fönster >>A Flexible Working Hydraulic System for Mobile Machines
    2016 (Engelska)Ingår i: International Journal of Fluid Power, ISSN 1439-9776, Vol. 17, nr 2, s. 79-89Artikel i tidskrift (Övrigt vetenskapligt) Published
    Abstract [en]

    This paper proposes a novel working hydraulic system architecture for mobile machines. Load sensing, flow control and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. One electrically controlled variable displacement pump supplies the system and conventional closed-centre spool valves are used. The pump control strategies are explained in detail. Experimental results demonstrate one solution to the flow matching problem and the static and dynamic differences between different control modes.

    Ort, förlag, år, upplaga, sidor
    Taylor & Francis, 2016
    Nyckelord
    Mobile hydraulics, dynamics, energy efficiency, pump controller
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-121068 (URN)10.1080/14399776.2016.1141635 (DOI)
    Tillgänglig från: 2015-09-04 Skapad: 2015-09-04 Senast uppdaterad: 2017-12-04Bibliografiskt granskad
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  • 125.
    Axin, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Ökad dämpning genom rätt design av utloppsstrypningen2012Ingår i: Hydraulikdagarna 2012, Linköping, 2012Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Svängningar är ett vanligt förekommande problem i hydrauliska system. Den här artikeln analyserar dämpningen i ett system bestående av en tryckkompenserad ventil, en cylinder samt en last. Genom att designa utloppsstrypningen i ventilen på ett bra sätt kan en hög dämpning erhållas. Resultaten som presenteras i den här artikeln kan ligga till grund vid systemdimensionering för att erhålla önskad dämpning i tryckkompenserade hydraulsystem. Volymerna på respektive sida av cylinderkolven har stor inverkan på dämpningen. Om inloppsvolymen är liten blir dämpningen låg. Det absolut viktigaste är dock att designa utloppsstrypningen på ett bra sätt. En optimal öppningsarea existerar; både mindre och större area ger lägre dämpning. I den här artikeln föreslås en design av utloppsstrypningen som optimerar dämpningen i det mest ogynnsamma fallet samtidigt som förlusterna över strypningen hålls relativt små. Experimentella resultat som bekräftar de teoretiska förväntningarna presenteras också.

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  • 126.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Braun, Robert
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Dell'Amico, Alessandro
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Björn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Nordin, Peter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Pettersson, Karl
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Staack, Ingo
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Next Generation Simulation Software using Transmission Line Elements2010Ingår i: Fluid Power and Motion Control / [ed] Dr D N Johnston and Professor A R Plummer, Centre for Power Transmission and Motion Control , 2010, s. 265-276Konferensbidrag (Refereegranskat)
    Abstract [en]

    A suitable method for simulating large complex dynamic systems is represented by distributed modelling using transmission line elements. The method is applicable to all physical systems, such as mechanical, electrical and pneumatics, but is particularly well suited to simulate systems where wave propagation is an important issue, for instance hydraulic systems. By using this method, components can be numerically isolated from each other, which provide highly robust numerical properties. It also enables the use of multi-core architecture since a system model can be composed by distributed simulations of subsystems on different processor cores.

    Technologies based on transmission lines has successfully been implemented in the HOPSAN simulation package, develop at Linköping University. Currently, the next generation of HOPSAN is developed using an object-oriented approach. The work is focused on compatibility, execution speed and real-time simulation in order to facilitate hardware-in-the-loop applications. This paper presents the work progress and some possible features in the new version of the HOPSAN simulation package.

  • 127.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Eriksson, Björn
    Parker Hannifin, Borås, Sweden.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    A Flexible Working Hydraulic System for Mobile Machines2016Ingår i: International Journal of Fluid Power, ISSN 1439-9776, Vol. 17, nr 2, s. 79-89Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This paper proposes a novel working hydraulic system architecture for mobile machines. Load sensing, flow control and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. One electrically controlled variable displacement pump supplies the system and conventional closed-centre spool valves are used. The pump control strategies are explained in detail. Experimental results demonstrate one solution to the flow matching problem and the static and dynamic differences between different control modes.

  • 128.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Eriksson, Björn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    A Hybrid of Pressure and Flow Control in Mobile Hydraulic Systems2014Ingår i: 9th InternationalFluid Power Conference (IFK). Vol. 1. Aachen, Germany, 24-26 March 2014 / [ed] Hubertus Murrenhoff, 2014, s. 190-201Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a hybrid pump controller approach for mobile hydraulic systems, influenced by both pressure and flow. The controller is tuneable to be able to set the order of importance of the pressure and flow controller, respectively. It is thus possible to realize a load sensing system, a flow control system or a mix of the two. Using a low load pressure feedback gain and a high flow control gain, a system emerges with high energy efficiency, fast system response, high stability margins and no flow matching issues. In this paper, both theoretical studies and practical implementations demonstrate the capability of a hybrid pump control approach.

  • 129.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Eriksson, Björn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Energy Efficient Fluid Power System for Mobile Machines with Open-centre Characteristics2014Ingår i: 9th JFPS International Symposium on Fluid Power. Matsue, Japan, 28-31 October 2014, The Japan Fluid Power System Society , 2014, s. 452-459Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper presents a flexible and energy efficient system solution which mimics the behaviour of an open-centre system. An electro-hydraulic variable displacement pump and closed-centre valves are used. Instead of having a flow in the open-centre gallery, that flow is calculated using a pressure sensor and a valve model. The variable pump is then controlled in order to only deliver the flow that would go to the actual loads. It is also possible for the operator to decide how much load dependency there should be. The extreme case is not having any load dependency at all, resulting in a system where the pump displacement setting is controlled according to the sum of all requested load flows. It is thus possible to realize a system design with open-centre characteristics, a flow control system or something in between. Each operator can thereby get their optimal control characteristic while having high energy efficiency.

  • 130.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Eriksson, Björn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Flow versus pressure control of pumps in mobile hydraulic systems2014Ingår i: Proceedings of the Institution of mechanical engineers. Part I, journal of systems and control engineering, ISSN 0959-6518, E-ISSN 2041-3041, Vol. 228, nr 4, s. 245-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work studies an innovative working hydraulic system design for mobile applications, referred to as flow control. The fundamental difference compared to load-sensing systems is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency since the pressure difference between pump and load is given by the system resistance rather than a prescribed pump pressure margin. Furthermore, load-sensing systems suffer from poor dynamic characteristics since the pump is operated in a closed-loop control mode. This might result in an oscillatory behaviour. Flow control systems have no stability issues attached to the load pressure feedback since there is none. This allows the pump to be designed to meet the response requirements without considering system stability. Pressure compensators are key components in flow control systems. This study addresses the flow matching problem which occurs when using traditional compensators in combination with a flow-controlled pump. Flow sharing pressure compensators solve this problem since the pump flow will be distributed between all active functions. Simulation results and measurements on a wheel loader application demonstrate the energy-saving potentials and the dynamic improvements for the flow control system.

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  • 131.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Design Rules for High Damping in Mobile Hydraulic Systems2013Ingår i: 13th Scandinavian International Conference on Fluid Power, Linköping University Electronic Press, 2013, s. 13-20Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper analyses the damping in pressure compensated closed centre mobile working hydraulic systems. Both rotational and linear loads are covered and the analysis applies to any type of pump controller. Only the outlet orifice in the directional valve will provide damping to a pressure compensated system. Design rules are proposed for how the system should be dimensioned in order to obtain a high damping. The volumes on each side of the load have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension for maximized damping; both smaller and larger orifice areas give lower damping independently of the volumes. This paper presents a method to dimension the outlet orifice area and the load volumes in order to obtain a desired system damping. Experimental results, which confirm the theoretical expectations, are also presented. The conclusions are that it is possible to obtain a high damping contribution from the outlet orifice if the system is dimensioned correctly. However, the energy efficiency needs to be considered while improving the damping

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    Design Rules for High Damping in Mobile Hydraulic Systems
  • 132.
    Axin, Mikael
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Palmberg, Jan-Ove
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification2012Ingår i: 8th International Fluid Power Conference Dresden: "Fluid Power Drives!", 2012, Vol. 1, s. 579-591Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper analyses the damping of a flow controlled cylinder with a mass load and an outlet orifice. By using linear models, a mathematical expression for the damping is derived. It is shown that the volumes on each side of the piston have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension; both smaller and larger orifice areas give low damping independently of the size of the volumes. In this paper a design is proposed of the outlet orifice area that optimizes the damping of the system. Experimental results which confirm the theoretical expectations are also presented. The conclusions are that without an outlet orifice, the hydraulic system will not contribute with any damping at all. Furthermore, large dead volumes in the cylinder will increase the damping, but at the expense of the system’s efficiency.

  • 133.
    Azeez, Ahmed
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära.
    Effect of dwell time on stress intensity factor of ferritic steel for steam turbine applications2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the transition from conventional to green energy production resources, steam turbines are used to satisfy the lack of energy during peaks in the demand times and the limited access of renewable resources. This type of usage for steam turbines makes them operate on a flexible schedule, which leads to unpredictable issues related to shorter component life and faster crack propagation. Thus, the steam turbine components must be examined to determine their specific life period. This will help set proper maintenance intervals and prevent unexpected failures. For that, thermo-mechanical fatigue (TMF) testing is used, where a specimen made of the same material as the turbine component is subjected to both temperature and load variation. The specimen is pre-cracked to investigate the crack propagation behavior, which is the focus of this study.

    This thesis work concentrates on simulating the TMF cycle for the steam turbine casing component. The material is 9%-10%Cr ferritic steel. The aim is to understand the material behavior during crack propagation and to predict a useful testing parameter. The method provided in this work discusses two cases, both are out-of-phase (OP) TMF tests with strain control. The maximum and minimum temperatures for the cycle are 600 ˚C and 400 ˚C respectively, while the maximum and minimum strain levels are 0 and  respectively. The study will investigate different , which is the maximum compressive strain level. Case 1 has a dwell time at the maximum temperature only, while case 2 has dwell times at both maximum and minimum temperatures. The method utilizes the stress intensity factor (SIF) to characterize the crack tip conditions. Also, it uses Paris' law to estimate the duration of the tests. For simplification, only the elastic behavior of the material is considered.

    The results obtained show no effect of using different pre-crack lengths due to the strain control condition. Minor effects can be observed by using different dwell times, however very short dwell times must be avoided to produce reliable results. A recommended dwell time of 5 minutes could be used, since longer dwell times will make the test prohibitively time-consuming. The compressive strain levels used in the work shows large effects on the results. Using low compressive strain values will produce a very long time for the tests, while very high compressive strains produce large plasticity. Thus, high compressive strains must be avoided since the SIF describes cracks for only elastic or near elastic cases. Also, small compressive strain levels in case 2 should not be used since it will lead to results like case 1. This is due to the small creep effect at the minimum temperature. Finally, compressive strain levels of 0.6 %, 0.5 % and 0.4 % are recommended for case 1, while only 0.6 % compressive strain level is recommended for case 2.

    This thesis contributes to the fields of solid mechanics, fracture mechanics and the use of TMF testing, where a recommended set of testing parameters are provided.

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  • 134.
    Azeez, Ahmed
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Robert
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Tekniska fakulteten.
    Calmunger, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Characterisation of Deformation and Damage in a Steam Turbine Steel Subjected to Low Cycle Fatigue2019Ingår i: Structural Integrity Procedia / [ed] Elsevier, 2019, Vol. 23, s. 155-160Konferensbidrag (Refereegranskat)
    Abstract [en]

    The increased use of renewable energy pushes steam turbines toward a more frequent operation schedule. Consequently, components must endure more severe fatigue loads which, in turn, requires an understanding of the deformation and damage mechanisms under high-temperature cyclic loading. Based on this, low cycle fatigue tests were performed on a creep resistant steel, FB2, used in ultra-supercritical steam turbines. The fatigue tests were performed in strain control with 0.8-1.2 % strain range and at temperatures of 400 °C and 600 °C. The tests at 600 °C were run with and without dwell time. The deformation mechanisms at different temperatures and strain ranges were characterised by scanning electron microscopy and by quantifying the amount of low angle grain boundaries. The quantification of low angle grain boundaries was done by electron backscatter diffraction. Microscopy revealed that specimens subjected to 600 °C showed signs of creep damage, in the form of voids close to fracture surface, regardless of whether the specimen had been exposed to dwell time or been purely cycled. In addition, the amount of low angle grain boundaries was lower at 600 °C than at 400 °C. The study indicates that a significant amount of the inelastic strain comes from creep strain as opposed to being all plastic strain.

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  • 135.
    Azeez, Ahmed
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Robert
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära.
    Leidermark, Daniel
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Calmunger, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Low cycle fatigue life modelling using finite element strain range partitioning for a steam turbine rotor steel2020Ingår i: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638, Vol. 107, artikel-id 102510Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Materials made for modern steam power plants are required to withstand high temperatures and flexible operational schedule. Mainly to achieve high efficiency and longer components life. Nevertheless, materials under such conditions experience crack initiations and propagations. Thus, life prediction must be made using accurate fatigue models to allow flexible operation. In this study, fully reversed isothermal low cycle fatigue tests were performed on a turbine rotor steel called FB2. The tests were done under strain control with different total strain ranges and temperatures (20 °C to 625 °C). Some tests included dwell time to calibrate the short-time creep behaviour of the material. Different fatigue life models were evaluated based on total life approach. The stress-based fatigue life model was found unusable at 600 °C, while the strain-based models in terms of total strain or inelastic strain amplitudes displayed inconsistent behaviour at 500 °C. To construct better life prediction, the inelastic strain amplitudes were separated into plastic and creep components by modelling the deformation behaviour of the material, including creep. Based on strain range partitioning approach, the fatigue life depends on different damage mechanisms at different strain ranges at 500 °C. This allows for the formulation of life curves based on either plasticity-dominated damage or creep-dominated damage. At 600 °C, creep dominated while at 500 °C creep only dominates for higher strain ranges. The deformation mechanisms at different temperatures and total strain ranges were characterised by scanning electron microscopy and by quantifying the amount of low angle grain boundaries. The quantification of low angle grain boundaries was done by electron backscatter diffraction. Microscopy revealed that specimens subjected to 600 °C showed signs of creep damage in the form of voids close to the fracture surface. In addition, the amount of low angle grain boundaries seems to decrease with the increase in temperature even though the inelastic strain amplitude was increased. The study indicates that a significant amount of the inelastic strain comes from creep strain as opposed of being all plastic strain, which need to be taken into consideration when constructing a life prediction model.

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    fulltext
  • 136.
    Aziz, Imran
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion.
    Design of a High Altitude Wind Power Generation System2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    One of the key points to reduce the world dependence on fossil fuels and the emissions of greenhouse gases is the use of renewable energy sources. Recent studies showed that wind energy is a significant source of renewable energy which is capable to meet the global energy demands. However, such energy cannot be harvested by today’s technology, based on wind towers, which has nearly reached its economical and technological limits. The major part of the atmospheric wind is inaccessible to the conventional wind turbines and wind at higher altitude is the major source of potential energy which has not been fully exploited yet. The thesis paper has presented a study aimed to devise a new class of wind generator based on extracting energy from high altitude wind.A brief theoretical study is presented to evaluate the potential of an innovative high altitude wind power technology which exploits a tethered airfoil to extract energy from wind at higher altitude. Among the various concepts proposed over last few decades, a kite power system with a single kite is selected for the design purpose.The designed ground station is an improvisation over existing prototypes with an energy reservoir for having a continuous power output. A flywheel is used as the energy storage system which stores the extra energy during traction phases and supplies it during recovery phases and thus giving a continuous power generation regardless of the kite’s motion and keeping the rotor speed in a permissible range defined by the design constraints. Manufacturability of the structure, availability of the components, safety and maintenance criteria have been taken into account while building the ground station CAD model.A dynamic simulation model is developed to investigate the power transmission system of the kite power unit which reflects the torque, speed and power behaviour of the modelled ground station driveline. The functionality of the designed model for the selected concept is tested with several numerical and graphical examples.

    Ladda ner fulltext (pdf)
    Design of a High Altitude Wind Power Generation System - Imran Aziz
  • 137.
    B M, Shiva Kumar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system.
    Ramanujam, kathiravan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system.
    Thermal Simulation of Hybrid Drive System2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Safety, performance and driving comforts are given high importance while developing modern day cars. All-Wheel Drive vehicles are exactly designed to fulfill such requirements. In modern times, human concern towards depleting fossil fuels and cognizance of ecological issues have led to new innovations in the field of Automotive engineering. One such outcome of the above process is the birth of electrical hybrid vehicles. The product under investigation is a combination of all wheel drive and hybrid system. A superior fuel economy can be achieved using hybrid system and optimized vehicle dynamic forces are accomplished by torque vectoring action which in turn provides All-Wheel Drive capabilities.

    Heat generation is inevitable whenever there is a conversion of energy from one form into another. In this master thesis investigation, a thermal simulation model for the product is built using 1D simulation tool AMESim and validation is done against the vehicle driving test data. AMESim tool was chosen for its proven track record related to vehicle thermal management. The vehicle CAN data are handled in MATLAB. In a nutshell, Simulation model accounts for heat generation sources, oil flow paths, power loss modeling and heat transfer phenomena.

    The final simulation model should be able to predict the transient temperature evolution in the rear drive when the speed and torque of motor is supplied as input. This simulation model can efficiently predict temperature patterns at various locations such as casing, motor inner parts as well as coolant at different places. Various driving cases were tried as input including harsh (high torque, low speed) ones. Simulation models like this helps Engineers in trying out new cooling strategies. Flow path optimization, flow rate, convection area, coolant pump controlling etc are the few variables worth mentioning in this regard.

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    Master_Thesis
  • 138.
    Backman, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    Åkerfeldt, Jonas
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    Bridging the gap: finding the processes to adapt a repository-based knowledge management system to the knowledge intense sales organization at IBM Nordic2007Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    For knowledge intense companies the knowledge and skills of its employees are much more valuable than any physical assets. To share knowledge between its employees, some companies launch knowledge sharing initiatives which aims to spread best practices and increase the expertise of the employees. These initiatives are often supported by technical systems, repositories, which store the information that is to be shared. This report discusses how the value of such a repository, a Wiki containing reference cases of SOA projects at IBM Nordic, can be increased by using processes that aims to better connect it to the organization.

    To do this, seven employees at IBM Nordic were interviewed. Four of them were sales people, the main user group of the Wiki. Two were employees at the SOA Acceleration Team, the group responsible for the Wiki. The last interviewee works at Learning and Knowledge, IBM’s internal department for organization-wide knowledge management and education. The answers were analyzed using a framework created using academic theory. This framework consists of four different areas of requirements for the processes connecting the Wiki to the organization. The analysis showed that for IBM the most important area to manage is enablement followed by governance, motivation and finally content.

    The report is concluded with recommendations for five processes to connect the Wiki to the organization. The process Internal selling aims to inform the sales people about the existence of the Wiki and how they are to use it. Ensure search engine compatibility makes sure that the sales people are able to find the contents of the Wiki via the intranet based search engines. The process for adding a new case description ensures that new case descriptions which are added to the Wiki is consistent and contains the right kind of information. By validating the case information that is added to the Wiki the acceleration team verifies that the information is correct, increasing its credibility. In the last process, ensure information congruence, the members of the acceleration team updates the guidelines on what information to collect and the information in the Wiki as the information need of the sales people changes. This is done on a regular basis and ensures that the information that is collected and stored is actually useful.

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    FULLTEXT01
  • 139. Beställ onlineKöp publikationen >>
    Baer, Katharina
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Simulation-Based Optimization of a Series Hydraulic Hybrid Vehicle2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Hybrid transmissions are characterized by their utilization of more than one form of energy storage. They have the potential to help reduce overall fuel consumption and vehicle emissions by providing the possibility of brake energy recuperation and prime mover operation management. Electric hybrids and electric vehicle drives are nowadays ubiquitous, and mechanical energy storage in flywheel has been investigated in the past. The use of fluid power technology with a combustion engine has also been investigated since the late 1970s, and is frequently revisited.

    Hydraulic hybridization is especially attractive for heavy vehicles with frequent braking and acceleration which benefit most from fluid power components’ high power density, typically busses, delivery or refuse vehicles, and vehicles with existing hydraulic circuits and transmissions, such as forest and construction machinery, but have been considered for smaller vehicles as well.

    Due to the characteristic discharge profile of hydraulic energy storage, special attention needs to be paid to control aspects in the design process to guarantee drivability of the vehicle. In this respect, simulation models can be of use in early design process stages for cheaper and faster evaluation of concepts and designs than physical experiments and prototyping, and to generate better understanding of the system studied. Engineering optimization aids in the systematic exploration of a given design space, to determine limits and potentials, evaluate trade-offs and potentially find unexpected solutions. In the optimization of a hydraulic hybrid transmission, the integration of component and controller design is of importance, and different strategies (sequential, iterative, bi-level and simultaneous approaches) are conceivable, with varying consequences for the implementation.

    This thesis establishes a simulation-based optimization framework for a hydraulic hybrid transmission with series architecture. Component and control parameter optimization are addressed simultaneously, using a rule-based supervisory control strategy. The forward-facing dynamic simulation model at the centre of the framework is built in Hopsan, a multi-disciplinary open-source tool developed at Linköping University. The optimization is set up and conducted for an example application of an on-road light-duty truck over standard drive cycles. Both results from these experiments as well as the framework itself are studied and evaluated. Relevant design aspects, such as explicit design relations to be considered and performance requirements for more robust design, are identified and addressed, and the optimization problem is analysed with regard to algorithm performance and problem formulation. The final result is an optimization framework that can be adjusted for further in-depth studies, for example through the inclusion of additional components or optimization objectives, and extendable for comparative analysis of different topologies, applications and problem formulations.  

    Delarbeten
    1. System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle
    Öppna denna publikation i ny flik eller fönster >>System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle
    2014 (Engelska)Ingår i: PROCEEDINGS OF THE 8TH FPNI PH.D SYMPOSIUM ON FLUID POWER, 2014, ASME Press, 2014, s. V001T03A004-Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Amongst the hybrid vehicle propulsion solutions aiming to improve fuel efficiency, hybrid electric solutions currently receive most attention, especially on the market. However, hydraulic hybrids are an interesting alternative, especially for heavier vehicles due to higher power density which is beneficial if higher masses are moved. As a step towards a comprehensive design framework to compare several possible hydraulic hybrid architectures for a specified application and usage profile, the model of a series hydraulic hybrid vehicle was previously introduced and initially studied concerning component sizing for an exemplary light-duty vehicle in urban traffic. The vehicle is modeled in the Hopsan simulation tool. A comparably straight-forward engine management is used for the vehicle control; both pump and engine controls are based on the hydraulic accumulator’s state-of-charge. The model is developed further with respect to the accumulator component model. Based on that, the influence of several system and component parameters, such as maximum system pressure and engine characteristics, as well as controller parameters on the vehicle’s performance is analyzed. The goal is to allow for more understanding of the system’s characteristics to facilitate future optimization of the system.

    Ort, förlag, år, upplaga, sidor
    ASME Press, 2014
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-114212 (URN)10.1115/FPNI2014-7840 (DOI)000359389400029 ()978-0-7918-4582-0 (ISBN)
    Konferens
    8th FPNI Ph.D Symposium on Fluid Power, Lappeenranta, Finland, June 11–13, 2014
    Tillgänglig från: 2015-02-13 Skapad: 2015-02-13 Senast uppdaterad: 2018-03-09
    2. Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle
    Öppna denna publikation i ny flik eller fönster >>Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle
    2015 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.

    Serie
    Scandinavian International Conference on Fluid Power (SICFP), ISSN 2342-2726
    Nationell ämneskategori
    Farkostteknik
    Identifikatorer
    urn:nbn:se:liu:diva-122004 (URN)
    Konferens
    14th Scandinavian International Conference on Fluid Power (SICFP'15), Tampere, Finland
    Tillgänglig från: 2015-10-14 Skapad: 2015-10-14 Senast uppdaterad: 2018-03-09
    3. Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design
    Öppna denna publikation i ny flik eller fönster >>Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design
    2016 (Engelska)Ingår i: Proceedings of the 9th FPNI Ph.D. Symposium on Fluid Power (FPNI2016), American Society of Mechanical Engineers , 2016, artikel-id V001T01A041Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Hybridization of a vehicle’s drivetrain can in principle help to improve its energy efficiency by allowing for recuperation of kinetic energy and modulating the engine’s load. How well this can be realized depends on appropriate sizing and control of the additional components. The system is typically designed sequentially, with the hardware setup preceding the development and tuning of advanced controller architectures. Taking an alternative approach, component sizing and controller tuning can be addressed simultaneously through simulation-based optimization.

    The results of such optimizations, especially with standard algorithms with continuous design variable ranges, can however be difficult to realize, considering for example limitations in available components. Furthermore, drive-cycle based optimizations are prone to cycle-beating. This paper examines the results of such simulation-based optimization for a series hydraulic hybrid vehicle in terms of sensitivity to variations in design parameters, system parameters and drive cycle variations. Additional relevant aspects concerning the definition of the optimization problem are pointed out.

    Ort, förlag, år, upplaga, sidor
    American Society of Mechanical Engineers, 2016
    Nyckelord
    Weight (Mass), Automotive design, Cycles, Optimization, Control equipment, Simulation, Design, Hybrid electric vehicles, Hardware, Stress
    Nationell ämneskategori
    Maskinteknik
    Identifikatorer
    urn:nbn:se:liu:diva-135737 (URN)10.1115/FPNI2016-1567 (DOI)978-0-7918-5047-3 (ISBN)
    Konferens
    9th FPNI Ph.D. Symposium on Fluid Power, Florianópolis, SC, Brazil, October 26–28, 2016
    Tillgänglig från: 2017-03-17 Skapad: 2017-03-17 Senast uppdaterad: 2018-03-09
    4. Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle
    Öppna denna publikation i ny flik eller fönster >>Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle
    2018 (Engelska)Ingår i: International Journal of Fluid Power, ISSN 1439-9776Artikel i tidskrift (Refereegranskat) Epub ahead of print
    Abstract [en]

    Hybridisation of hydraulic drivetrains offers the potential of efficiency improvement for on – and off-road applications. To realise the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process. Addressing component selection and control parameterisation simultaneously through simulation-based optimisation allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimisation framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance. A number of optimisation experiments for an on-road light-duty vehicle, focused on standard-drive-cycle-performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.

    Ort, förlag, år, upplaga, sidor
    Taylor & Francis, 2018
    Nyckelord
    Simulation-based optimization, hydraulic hybrid vehicle, series hybrid, simultaneous design and control optimization, Hopsan
    Nationell ämneskategori
    Datorsystem
    Identifikatorer
    urn:nbn:se:liu:diva-152353 (URN)10.1080/14399776.2018.1527122 (DOI)2-s2.0-85055674140 (Scopus ID)
    Tillgänglig från: 2018-10-29 Skapad: 2018-10-29 Senast uppdaterad: 2018-11-23Bibliografiskt granskad
    5. Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
    Öppna denna publikation i ny flik eller fönster >>Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
    2020 (Engelska)Ingår i: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 52, nr 3, s. 446-464Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.

    Ort, förlag, år, upplaga, sidor
    Taylor & Francis, 2020
    Nyckelord
    Simulation-based optimization, information entropy-rate-based performance index, robustness analysis, direct search optimization, hydraulic hybrid vehicle
    Nationell ämneskategori
    Farkostteknik
    Identifikatorer
    urn:nbn:se:liu:diva-156185 (URN)10.1080/0305215X.2019.1590566 (DOI)000510053200005 ()
    Tillgänglig från: 2019-04-08 Skapad: 2019-04-08 Senast uppdaterad: 2020-02-17Bibliografiskt granskad
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    Simulation-Based Optimization of a Series Hydraulic Hybrid Vehicle
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  • 140.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design2016Ingår i: Proceedings of the 9th FPNI Ph.D. Symposium on Fluid Power (FPNI2016), American Society of Mechanical Engineers , 2016, artikel-id V001T01A041Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hybridization of a vehicle’s drivetrain can in principle help to improve its energy efficiency by allowing for recuperation of kinetic energy and modulating the engine’s load. How well this can be realized depends on appropriate sizing and control of the additional components. The system is typically designed sequentially, with the hardware setup preceding the development and tuning of advanced controller architectures. Taking an alternative approach, component sizing and controller tuning can be addressed simultaneously through simulation-based optimization.

    The results of such optimizations, especially with standard algorithms with continuous design variable ranges, can however be difficult to realize, considering for example limitations in available components. Furthermore, drive-cycle based optimizations are prone to cycle-beating. This paper examines the results of such simulation-based optimization for a series hydraulic hybrid vehicle in terms of sensitivity to variations in design parameters, system parameters and drive cycle variations. Additional relevant aspects concerning the definition of the optimization problem are pointed out.

  • 141.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Component Sizing Study for a Light-Duty Series Hydraulic Hybrid Vehicle in Urban Drive Cycles2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the focus on energy efficiency for many different kinds of vehicle applications,hybridization is considered a possible solution to reduce fuel consumption. While hybrid electric concepts are already available for passenger vehicles, and also considered for heavier applications, hybrid hydraulic alternatives have been mainly limited to the latter, which benefit most from the higher power density available. To study the different hybrid architectures and applications, a modeling framework for the system design is developed using the simulation tool Hopsan from Linköping University.  Previously,  the  model  of  a  series  hydraulic  hybrid  vehicle  was introduced, a light-duty vehicle simulated over two standard urban drive cycles, and its potential for further work established. In this paper, the model is extended by including a simple combustion engine power management to provide for more realistic propulsion of the hydraulic drivetrain, showing the potential to operate a series hydraulic hybrid vehicle’s engine in more efficient regions. Additionally, the design is studied concerning the effects of a variation of key component sizes on the accuracy and energy efficiency objectives. Instead of subjecting the system to (multi- objective) optimization, at this stage the individual component’s influence is studied, and the objectives are dealt with separately from each other to eliminate the need for compromise   between   them,   both   to   gain a better understanding of the interdependencies.

  • 142.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.

  • 143.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Framework for Simulation-Based Simultaneous System Optimization for a Series Hydraulic Hybrid Vehicle2019Ingår i: International Journal of Fluid Power, ISSN 1439-9776, Vol. 20, nr 1, s. 27-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hybridization of hydraulic drivetrains offers the potential of efficiency improvement for on- and off-road applications. To realize the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process. Addressing component selection and control parameterization simultaneously through simulation-based optimization allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimization framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the systems performance. Anumber of optimization experiments for an on-road light-duty vehicle, focused on standard-drive-cycle-performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.

  • 144.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Modeling of a Series Hybrid Hydraulic Drivetrain for a Light-Duty Vehicle in Hopsan2013Ingår i: Conference proceedings: 13th Scandinavian International Conference on Fluid Power / [ed] Petter Krus, Magnus Sethson, Liselott Ericson, Linköping, Sweden: Linköping University Electronic Press, 2013, s. 107-112Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hydraulic hybrids continue to receive attention as a possible solution in the search for improved fuel economy for different vehicle types. This paper presents a model for a series hydraulic hybrid light-duty vehicle, developed in the Hopsan simulation tool of Linköping University’s Division of Fluid and Mechatronic Systems (Flumes). Focusing on the hydraulic transmission which employs a pump control based on the hydraulic accumulator’s state-of-charge (SoC), several simplifications were made, especially concerning mechanical components. Simulation over two urban standard cycles shows promising results concerning dynamic performance and energy recuperation potential, provided sufficient component sizing to compensate for the mechanical limitations. This paper lays the foundation for both a further refined model - suitable for optimizing the full drivetrain, including component sizing and controller parameterization - and the development of comparable models for parallel and power-split hybrid architectures.

  • 145.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle2020Ingår i: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 52, nr 3, s. 446-464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.

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    fulltext
  • 146.
    Baer, Katharina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Ericson, Liselott
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle2014Ingår i: PROCEEDINGS OF THE 8TH FPNI PH.D SYMPOSIUM ON FLUID POWER, 2014, ASME Press, 2014, s. V001T03A004-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Amongst the hybrid vehicle propulsion solutions aiming to improve fuel efficiency, hybrid electric solutions currently receive most attention, especially on the market. However, hydraulic hybrids are an interesting alternative, especially for heavier vehicles due to higher power density which is beneficial if higher masses are moved. As a step towards a comprehensive design framework to compare several possible hydraulic hybrid architectures for a specified application and usage profile, the model of a series hydraulic hybrid vehicle was previously introduced and initially studied concerning component sizing for an exemplary light-duty vehicle in urban traffic. The vehicle is modeled in the Hopsan simulation tool. A comparably straight-forward engine management is used for the vehicle control; both pump and engine controls are based on the hydraulic accumulator’s state-of-charge. The model is developed further with respect to the accumulator component model. Based on that, the influence of several system and component parameters, such as maximum system pressure and engine characteristics, as well as controller parameters on the vehicle’s performance is analyzed. The goal is to allow for more understanding of the system’s characteristics to facilitate future optimization of the system.

  • 147.
    Bahmai, Masoud
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Kvalitetsteknik. Linköpings universitet, Tekniska högskolan.
    Lean Implementation in Rosti AB: Improvement Opportunities and Challenges2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Lean production has become a widespread production system to address the need of being more productive. Since three decades ago that some big automotive manufacturers started to adopt lean, many SME’s has adopt it and enjoy the outcomes. Literature have investigated the successful implementation of lean in these organizations, yet, very few papers have addressed the challenges toward adopting lean.

    In this thesis research a plastic package manufacturer is chosen as the case of study to implement some initiatives of lean production and study the challenges and outcomes of lean adoption. The efforts during the making the changes were focused on adopting the SMED and Root-Cause Analysis techniques, and also to reduce defect rate in one of the products.

    The findings indicate before any effort to implement lean production techniques, some social issues must be considered to reduce the risk of failure. The Rosti AB case indicated that promoting motivation among operators and resolving mistrust between managers and operators is essential to encourage them to participate in improvement changes.

    In order to promote motivation and eliminate mistrust to encourage operators to participate in improvement changes it is necessary to empower them in decision makings in improvement implementations.

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    Thesis Report
  • 148.
    Bajuri, M. N.
    et al.
    University of Oxford, England; University of Teknol Malaysia, Malaysia.
    Isaksson, Hanna
    Lund University, Sweden.
    Eliasson, Pernilla T.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Thompson, Mark S.
    University of Oxford, England.
    A hyperelastic fibre-reinforced continuum model of healing tendons with distributed collagen fibre orientations2016Ingår i: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 15, nr 6, s. 1457-1466Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The healing process of ruptured tendons is problematic due to scar tissue formation and deteriorated material properties, and in some cases, it may take nearly a year to complete. Mechanical loading has been shown to positively influence tendon healing; however, the mechanisms remain unclear. Computational mechanobiology methods employed extensively to model bone healing have achieved high fidelity. This study aimed to investigate whether an established hyperelastic fibre-reinforced continuum model introduced by Gasser, Ogden and Holzapfel (GOH) can be used to capture the mechanical behaviour of the Achilles tendon under loading during discrete timepoints of the healing process and to assess the models sensitivity to its microstructural parameters. Curve fitting of the GOH model against experimental tensile testing data of rat Achilles tendons at four timepoints during the tendon repair was used and achieved excellent fits (0.9903 amp;lt; R-2 amp;lt; 0.9986). A parametric sensitivity study using a three-level central composite design, which is a fractional factorial design method, showed that the collagen-fibre-related parameters in the GOH model-kappa, k(1) and k(2)-had almost equal influence on the fitting. This study demonstrates that the GOH hyperelastic fibre-reinforced model is capable of describing the mechanical behaviour of healing tendons and that further experiments should focus on establishing the structural and material parameters of collagen fibres in the healing tissue.

  • 149.
    Bakoglidis, Konstantinos
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Glenat, Herve
    Technosud, France.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schmidt, Susann
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Grillo, Stefano
    Technosud, France; University of Perpignan, France.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Comparative study of macro- and microtribological properties of carbon nitride thin films deposited by HiPIMS2017Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 370Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The macro- and microtribological properties of carbon nitride thin films deposited by high power impulse magnetron sputtering at different substrate bias voltages (V-b) were investigated. V-b of -100, -150, -200, and-300 V were used. A Hysitron Triboindenter TI950 and a reciprocating Tribotechnic tribometer with diamond counterparts were used in order to assess the tribological performance of the films at the micro- and macroscale, respectively. Initial Hertzian contact pressures of 2.5 GPa, 3.3 GPa and 3.9 GPa were chosen for the comparative measurements at both scales. At the macroscale, films with higher initial roughness present an increased wear. Debris creation and asperity deformation takes place causing abrasive wear. At the microscale, compression of the surface material occurs. The run-in friction shows similar trends at both scales; an initial decrease and an increase thereafter. Steady-state friction is not reached at the microscale, attributed to the absence of a graphitic tribolayer in the contact. At the macroscale, all films show abrasive wear and debris creation. Here, the changes in friction coefficients are attributed to the debris loss from the contact during the tribotests. The CN film tested at 2.5 GPa shows a continuous increase of friction, due to the continuous loss of debris from the contact. The other films reach a steady-state friction coefficient, since most of the debris is lost before the end of the tribotests. (C) 2016 Elsevier B.V. All rights reserved.

  • 150.
    Bakoglidis, Konstantinos
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. SKF Engineering and Research Centre, Tribology and Lubrication Department, Nieuwegein, The Netherlands.
    Nedelcu, Ileana
    SKF Engineering and Research Centre, Tribology and Lubrication Department, Nieuwegein, The Netherlands.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Meeuwenoord, Ralph
    SKF Engineering and Research Centre, Tribology and Lubrication Department, Nieuwegein, The Netherlands.
    Schmidt, Susann
    IHI Ionbond AG, Olten, Switzerland.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ehret, Pascal
    SKF Engineering and Research Centre, Tribology and Lubrication Department, Nieuwegein, The Netherlands.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rolling performance of carbon nitride-coated bearing components in different lubrication regimes2017Ingår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 114, s. 141-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of carbon nitride (CN) coated roller bearings is investigated, using a micropitting rig. The rolling performance is evaluated using Stribeck test, with a continuously varying rolling speed (0.2 - 2 m/s). Rolling contact fatigue tests with constant speeds (0.5, 1, 2, and 3.5 m/s) are also conducted in order to study the high-cycle performance of the rollers. The obtained Stribeck curve shows that the presence of coatings eliminates run-in, resulting in low friction coefficients (similar to 0.08). Raman spectroscopy, performed at the wear tracks, reveals that CNx maintain stable chemical state. Coatings show abrasion although the wear rate is not detrimental for the performance of the rollers, since a CNx to-steel contact is retained during the entire rolling contact fatigue test.

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