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  • 301. Beställ onlineKöp publikationen >>
    Chen, Zhe
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Surface Integrity and Fatigue Performance of Nickel-based Superalloys2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Due to global warming, the demand for more efficient gas turbines has increased. A way to achieve this, is by increasing the operating temperature of the gas turbine. Therefore, nickel-based superalloys have been developed to withstand these extreme temperatures and loads, especially in the hot sections. Today, the way of operating land-based gas turbines is changing. Instead of running for long periods of time, the operation is becoming more flexible, with ever-increasing cyclic loads and number of start and stop cycles. To handle the increased stress and cycles, component resistance to fatigue failures need to be improved.

    Surface integrity is critical to fatigue performance, since fatigue cracks normally initiate at a surface. Machining changes the surface integrity which can result in worse fatigue resistance. The work presented in this Ph.D. thesis was conducted in collaboration with Siemens Industrial Turbomachinery AB in Finspång, Sweden. Surface integrity changes which are induced during machining and their effects on fatigue performance have been studied on the alloy Inconel 718. Inconel 718 is a widely-used nickel-based superalloy for high temperature applications in modern gas turbines.

    Broaching, milling, and wire electrical discharge machining, related to component manufacturing in turbo machinery industries, were included in this study. Machining induced surface defects provide preferential sites for fatigue crack initiation which influence the fatigue performance of the alloy. If compressive residual stresses are induced during machining, they benefit the fatigue life by retarding fatigue crack initiation away from surface regions. Shot peening was performed on machined Inconel 718, by which high compressive residual stresses are deliberately induced. It results in enhanced fatigue performance.

    The high temperatures in gas turbines generally deteriorate the surface integrity. Recrystallization often occurs in the highly deformed surface layer. Microstructural degradation, in the form of α-Cr precipitates, have also been frequently observed in the deformed surface and sub-surface microstructure. Oxidation at elevated temperatures degrades the surface integrity and thereby also the fatigue performance. Fatigue cracks are preferably initiated at oxidized surface carbides, if thermal exposure has been made prior to the test. It is even worse when high temperatures relax the beneficial surface compression induced by shot-peening and thereby lowering the fatigue resistance.

    Machinability of a newly developed nickel-based superalloy, AD 730TM, and the surface integrity induced during turning have also been studied in this thesis project. AD 730TM is a candidate for turbine disc applications with an operating temperature above 650 °C. At such high temperatures, Inconel 718 is no longer stable and its mechanical properties start to degrade.

    To summarize, the results from this thesis work show the importance of understanding surface integrity effects for fatigue applications, especially in harsh environments. Moreover, the knowledge gained through this work could be used for surface enhancement of turbine components which are subjected to a high risk of fatigue failure. These will contribute to more efficient and flexible power generation by gas turbines.

    Delarbeten
    1. Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures
    Öppna denna publikation i ny flik eller fönster >>Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures
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    2016 (Engelska)Ingår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 47A, nr 7, s. 3664-3676Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The current study focused on the surface integrity issues associated with broaching of Inconel 718 and the structural stability of the broached specimen at high temperatures, mainly involving the microstructural changes and residual stress relaxation. The broaching operation was performed using similar cutting conditions as that used in turbo machinery industries for machining fir-tree root fixings on turbine disks. Thermal exposure was conducted at 723 K, 823 K, and 923 K (450 A degrees C, 550 A degrees C, and 650 A degrees C) for 30, 300, and 3000 hours, respectively. Surface cavities and debris dragging, sub-surface cracks, high intensity of plastic deformation, as well as the generation of tensile residual stresses were identified to be the main issues in surface integrity for the broached Inconel 718. When a subsequent heating was applied, surface recrystallization and alpha-Cr precipitation occurred beneath the broached surface depending on the applied temperature and exposure time. The plastic deformation induced by the broaching is responsible for these microstructural changes. The surface tension was completely relaxed in a short time at the temperature where surface recrystallization occurred. The tensile layer on the sub-surface, however, exhibited a much higher resistance to the stress relief annealing. Oxidation is inevitable at high temperatures. The study found that the surface recrystallization could promote the local Cr diffusion on the broached surface.

    Ort, förlag, år, upplaga, sidor
    Springer, 2016
    Nyckelord
    Structural integrity, Broaching, Inconel 718, Plastic deformation, Residual stresses, Thermal exposure, Superalloy
    Nationell ämneskategori
    Materialteknik Annan materialteknik
    Identifikatorer
    urn:nbn:se:liu:diva-111056 (URN)10.1007/s11661-016-3515-6 (DOI)000377434700041 ()
    Forskningsfinansiär
    Linköpings universitet, 2009-00971
    Anmärkning

    The original title of this article when published in manuscript form was Structural integrity of broached Inconel 718 subjected to thermal exposure.

    Tillgänglig från: 2014-10-06 Skapad: 2014-10-06 Senast uppdaterad: 2018-02-27Bibliografiskt granskad
    2. On the Conjoint Influence of Broaching and Heat Treatment on Bending Fatigue Behavior of Inconel 718
    Öppna denna publikation i ny flik eller fönster >>On the Conjoint Influence of Broaching and Heat Treatment on Bending Fatigue Behavior of Inconel 718
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    2016 (Engelska)Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 671, s. 158-169Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this study, the conjoint effect of a broaching operation, similar to that used for machining fir-tree slots on turbine discs, and subsequent heat treatments at 550 °C and 650 °C on the fatigue performance and corresponding crack initiation behavior of forged Inconel 718 has been investigated. Four-point bending fatigue tests were conducted under load control on specimens of two groups, i.e. a polished group and a broached group, with totally six different surface conditions. Compared to the as-polished specimens, a beneficial effect of the broaching operation was found on the fatigue life due to the high compressive residual stresses on the broached surface which transfer the fatigue crack initiation from surface to sub-surface regions. Introducing a heat treatment generally deteriorated the fatigue performance of the alloy because of the oxidation assisted crack initiation, while the reduction in fatigue life was found to be more remarkable for the broached specimens, in particular when heat treated at 650 °C, as the thermal impact also led to a great relaxation of the compressive residual stresses; the combined effect, together with the substantial anomalies created by broaching on the surface, such as cracked carbides and machining grooves, caused an increased propensity to surface cracking in fatigue and consequently a loss of the lifetime. Furthermore, it was found that the occurrence of surface recrystallization at elevated temperatures in machined Inconel 718 could lead to intergranular oxidation, creating micro-notches as preferable sites for the fatigue crack initiation.

    Nyckelord
    Broaching, Inconel 718, Surface integrity, thermal impact, Fatigue, Crack initiation
    Nationell ämneskategori
    Annan materialteknik
    Identifikatorer
    urn:nbn:se:liu:diva-129843 (URN)10.1016/j.msea.2016.06.030 (DOI)000381165400016 ()
    Anmärkning

    Funding agencies: Faculty grant SFO-MAT-LiU at Linkoping University [2009-00971]; Siemens Industrial Turbomachinery AB

    Tillgänglig från: 2016-06-29 Skapad: 2016-06-29 Senast uppdaterad: 2017-11-28
    3. Nano-scale characterization of white layer in broached Inconel 718
    Öppna denna publikation i ny flik eller fönster >>Nano-scale characterization of white layer in broached Inconel 718
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    2017 (Engelska)Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 684, s. 373-384Artikel i tidskrift (Refereegranskat) Published
    Abstract [sv]

    The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.

    TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.

    Ort, förlag, år, upplaga, sidor
    Amsterdam: Elsevier, 2017
    Nyckelord
    Surface integrity; White layer; Broaching; Inconel 718; Adiabatic shear band; Mechanically-based subgrain rotation
    Nationell ämneskategori
    Materialkemi Oorganisk kemi Annan materialteknik Pappers-, massa- och fiberteknik Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-134123 (URN)10.1016/j.msea.2016.12.045 (DOI)000393938300045 ()
    Anmärkning

    Funding agencies: AForsk Foundation [15-334];  [2009-00971]

    Tillgänglig från: 2017-01-24 Skapad: 2017-01-24 Senast uppdaterad: 2017-11-29Bibliografiskt granskad
    4. Surface Integrity and Fatigue Performance of Inconel 718 in Wire Electrical Discharge Machining
    Öppna denna publikation i ny flik eller fönster >>Surface Integrity and Fatigue Performance of Inconel 718 in Wire Electrical Discharge Machining
    2016 (Engelska)Ingår i: 3RD CIRP CONFERENCE ON SURFACE INTEGRITY, 2016, Vol. 45, s. 307-310Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper presents a study to characterize the surface integrity in wire electrical discharge machining (EDM) of Inconel 718 and investigate its effect on the fatigue performance of the alloy in a four-point bending fatigue mode at room temperature. The EDM process generates a rough recast surface with multi-types of defects. Surface craters, micro-cracks and micro-voids within the recast layer have been found to be most detrimental from the point of view of fatigue as they could provide many preferential initiation sites for fatigue cracks. As a consequence, the specimens with an EDM cut surface show an approximately 30% decrease in fatigue life compared to those with a polished surface, and multiple crack origins were observed on the fracture surface. The high tensile residual stresses generated on the EDM cut surface, on the other hand, are also believed to be partly responsible for the loss in fatigue life of the alloy machined by EDM.

    Serie
    Procedia CIRP, ISSN 2212-8271
    Nyckelord
    wire electrical discharge machining (wire EDM), surface integrity, fatigue, crack initiation, Inconel 718
    Nationell ämneskategori
    Materialteknik Annan materialteknik
    Identifikatorer
    urn:nbn:se:liu:diva-130582 (URN)10.1016/j.procir.2016.02.053 (DOI)000417326500077 ()
    Konferens
    3rd CIRP Conference on Surface Integrity (CIRP CSI)8-10 June, 2016, Charlotte, USA
    Anmärkning

    Funding agencies: Siemens Industrial Turbomachinery AB; Strategic Faculty Grant AFM at Linkoping University

    Tillgänglig från: 2016-08-17 Skapad: 2016-08-17 Senast uppdaterad: 2018-03-28
    5. Effect of Cooling and Shot Peening on Residual Stresses and Fatigue Performance of Milled Inconel 718
    Öppna denna publikation i ny flik eller fönster >>Effect of Cooling and Shot Peening on Residual Stresses and Fatigue Performance of Milled Inconel 718
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    2017 (Engelska)Ingår i: Residual Stresses 2016 ICRS 10 / [ed] T.M. Holden, O. Muránsky, and L. Edwards, 2017, Vol. 2, s. 13-18Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    The present study highlights the effect of cooling and post-machining surface treatment of shot peening on the residual stresses and corresponding fatigue life of milled superalloy Inconel 718. It was found that tensile residual stresses were created on the milled surface, regardless of the use of coolant, however, the wet milling operation led to a lower surface tension and a reduced thickness of the tensile layer. The shot peening performed on the dry-milled specimens completely annihilated the surface tensile residual tresses and introduced a high level of surface compression. A comparable fatigue life for the wet-milled specimens was obtained as compared with the specimens prepared by dry milling. This is very likely attributed to that the milling-induced surface damage with respect to cracked non-metallic inclusions is the predominant cause of the fatigue failure. The presence of the compressive layer induced by shot peening resulted in a significant increase of the fatigue life and strength, while the extent to which the lifetime was prolonged was decreased as the applied load was increased.

    Serie
    Materials Research Proceedings, ISSN 2474-395X
    Nyckelord
    Residual stresses, surface integrity, milling, shot peening, superalloys, fatigue
    Nationell ämneskategori
    Materialteknik
    Identifikatorer
    urn:nbn:se:liu:diva-132001 (URN)10.21741/9781945291173-3 (DOI)000401041500003 ()978-1-9452-9116-6 (ISBN)
    Konferens
    10th International Conference on Residual Stresses ICRS-10, Sydney, Australia, 3-8 July 2016
    Anmärkning

    Funding agencies: Linkoping University [2009-00971]; Ytstruktur Arboga AB; Siemens Industrial Turbomachinery AB

    Tillgänglig från: 2016-10-13 Skapad: 2016-10-13 Senast uppdaterad: 2017-06-13Bibliografiskt granskad
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  • 302.
    Chen, Zhe
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Zhou, Jinming
    Division of Production and Materials Engineering, Lund university.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Bushlya, Volodymyr
    Division of Production and Materials Engineering, Lund university.
    Johansson, Sten
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    ECCI and EBSD Study of Surbsurface Damages in High Speed Turning of Inconel 718 under Different Tools and Machining Parameters2013Konferensbidrag (Refereegranskat)
  • 303. Chew, Michelle S
    et al.
    Brandberg, Joakim
    Canard, P
    Sloth, E
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Hasenkam, J Michael
    Doppler flow measurement using surface integration of velocity vectors (SIVV): in vitro validation.2000Ingår i: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 26, nr 2, s. 255-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Blood flow measurement using an improved surface integration of velocity vectors (SIVV) technique was tested in in vitro phantoms. SIVV was compared with true flow (12-116 mL/s) in a steady-state model using two angles of insonation (45 degrees and 60 degrees ) and two vessel sizes (internal diameter = 11 and 19 mm). Repeatability of the method was tested at various flow rates for each angle of insonation and vessel. In a univentricular pulsatile model, SIVV flow measured at the mitral inlet was compared to true flow (29-61 mL/s). Correlation was excellent for the 19-mm vessel (r(2)= 0.99). There was a systematic bias but close limits of agreement (mean +/- 2 SD = -24.1% +/- 7.6% at 45 degrees; +16.4% +/- 11.0% at 60 degrees ). Using the 11-mm vessel, a quadratic relationship was demonstrated between between SIVV and true flow (r(2) = 0.98-0.99), regardless of the angle of insonation. In the pulsatile system, good agreement and correlation were shown (r(2) = 0.94, mean +/- 2 SD = -4.7 +/- 10.1%). The coefficients of variation for repeated SIVV measurements ranged from 0.9% to 10.3%. This method demonstrates precision and repeatability, and is potentially useful for clinical measurements.

  • 304.
    Chicksand, Daniel
    et al.
    Warwick Business School.
    Kumar, Naveen
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Logistik. Linköpings universitet, Tekniska högskolan.
    Rehme, Jakob
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell marknadsföring och industriell ekonomi. Linköpings universitet, Tekniska högskolan.
    Walker, Helen
    Cardiff Business School.
    Global Purchasing – Implications for Purchasing and Logistics: A research synthesis2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Globalisation and the dynamics of the new economic geography is increasingly influencing supply chain management across different industries. Although the literature combining purchasing and logistics in the global supply chain is crucial, it has scarcely been reviewed in this combined approach. With companies like DELL, Walmart, and Li & Fung who are orchestrators in supply chains capitalising upon globalisation, the future trend is for a greater need to understand the purchasing and logistics aspects of global supply chains. In this study a review, analysis and synthesis of the literature in purchasing and logistics in global purchasing is conducted to. The research synthesis will aid both practitioners and researchers in a broader and better understanding of purchasing and logistics issues in the context of global supply chain design.

  • 305.
    Christensen, Peter
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Klarbring, Anders
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    An introduction to structural optimization2009 (uppl. 1)Bok (Övrigt vetenskapligt)
    Abstract [en]

    Mechanical and structural engineers have always strived to make as efficient use of material as possible, e.g. by making structures as light as possible yet able to carry the loads subjected to them. In the past, the search for more efficient structures was a trial-and-error process. However, in the last two decades computational tools based on optimization theory have been developed that make it possible to find optimal structures more or less automatically. Due to the high cost savings and performance gains that may be achieved, such tools are finding increasing industrial use.This textbook gives an introduction to all three classes of geometry optimization problems of mechanical structures: sizing, shape and topology optimization. The style is explicit and concrete, focusing on problem formulations and numerical solution methods. The treatment is detailed enough to enable readers to write their own implementations. On the book's homepage, programs may be downloaded that further facilitate the learning of the material covered.The mathematical prerequisites are kept to a bare minimum, making the book suitable for undergraduate, or beginning graduate, students of mechanical or structural engineering. Practicing engineers working with structural optimization software would also benefit from reading this book."--Publisher's website.

  • 306.
    Clipii, Tudor
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling.
    On mathematical modeling of shaped charge penetration2008Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Shaped charges are a well established type of projectile, subjected to a lot of research ever since emerging as a viable technology in the 1940s. The penetration achieved by shaped charges decreases with increased standoff distance. This is often attributed to the shaped charge jet losing its coherence. The Swedish Defence Research Agency however, noted no such loss of coherence in its experiments. An alternative explanation to the decrease of penetration was instead proposed. The object of this thesis was to investigate this proposed theory. To this end, the hydrocode Autodyn was used, modelling the impact of a high-velocity projectile into a generic target and analysing the resulting behaviour of the target. Several setups were used and several parameters were considered when evaluating the results. The conclusion of this thesis is that the alternative explanation offered is not supported by the observed behaviour of the target in the computer model.

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  • 307.
    Colombi, Raffaele
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära.
    CFD Investigation of Aerodynamic Drag Reduction for an Unloaded Timber Truck2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The road transport industry is facing a strong need for fuel consumption reduction, driven by the necessity of decreasing polluting emissions, such as CO2 and NOX, as well as coping with strict regulations and increasing fuel costs. For road vehicles the aerodynamic drag constitutes a major source of energy consumption, and for this reason improving the aerodynamic performance of the vehicle is an established approach for reducing fuel consumption and greenhouse gases emissions.

    In this Thesis work, Computational Fluid Dynamics (CFD) investigations have been carried out in order to investigate and improve the aerodynamic performance of an unloaded timber truck. The work has been divided in two parts. In a first phase, a preliminary study was carried out on a simplified tractor-trailer model in order to establish a suitable computational grid and turbulence model. The hexcore-mesh showed a better performance over the tet- and poly-mesh types. Among the selected RANS turbulence models, the Realizable kε with Enhanced Wall Treatment (EWT) and y+ > 30 showed the highest reliability of results in

    comparison with experimental data and existing CFD investigations.

    In a second phase, the flow field around the baseline unloaded timber truck was analysed in order to highlight potential regions for drag reduction. The truck cabin-bulkhead gap, bunks, the exposed wheels and the stakes were found make key contribution to the drag build-up. The analysis confirmed the 5-yaw case to be the most representative for the wind-averaged drag coefficient.

    Geometry modifications were implemented in order to improve the aerodynamic performance in the selected areas, and subsequently combined into aero-kits in order to enhance the performance, analysed for the 5-yaw case. The combination of extended side skirts, bulkhead shield and collapsed stakes yielded a remarkable result of more than 30% decrease in the wind-averaged drag coefficient, achieved by reducing the flow separation on the cabin leeward A-pillar, and by shielding areas of high stagnation pressure from the side wind.

    Furthermore, a parallel study was conducted on the development of a procedure for the automatic post-processing of results. The outcome was a set of Python scripts to be used with Kitaware Paraview in order to automatically obtain figures of surface variables distributions, iso-surfaces, velocity profiles, drag build-up and total pressure contours. The procedure was finally extended to include the case comparison.

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  • 308.
    Cramér, Martin
    et al.
    Linköpings universitet, Ekonomiska institutionen.
    Matsson, Anders
    Linköpings universitet, Ekonomiska institutionen.
    Customization Through Standardization: a study on Atlas Copco Tools & Assembly Systems’ market offer of fixtured tools to the motor vehicle industry2004Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Atlas Copco Tools & Assembly Systems (ACTA) is world leader in industrial tools and assembly systems for safety-critical joints. One of the products the company sells is fixtured nutrunners, mainly to the motor vehicle industry. The margins on these highly customized products have been decreasing – much depending on changes in the purchasing behavior of the automotive industry.

    Traditionally, the marketing of the fixtured nutrunners has been concentrated to the parts of the product instead of the final product. Today, there is a belief within the organization that many of the sold customized products could be replaced by more standardized applications. There is also a wish to turn the focus of the market offer from the parts towards the final application. These beliefs and wishes resulted in this thesis, with the purpose to propose a new market offer to increase profitability and give more customer benefits.

    To reach this purpose we started out with theoretical studies of several different areas. Among those was mass customization, a strategy that combines the benefits of mass production with those of customization. We also performed a prestudy at the headquarters of ACTA in Sickla and visited major customers in Sweden. Using our collected knowledge from the theoretical studies and the prestudy, we conducted an in-depth case study by interviewing customers and people working at ACTA, both in Sweden and in the USA, in order to analyze today’s situation. In the analysis, we found several problems with today’s offer. For instance, we found that similar products are solved with unique solutions, which has lead to poor cost control and has made it difficult for ACTA to assure the quality of the ordered products. A further problem is the poor sales support and the lack of traceability of sold systems, which reduces sales and leads to unnecessary special solutions. A problem linked to that is the difficulties in getting accurate and sufficient information from the customer, which leads to extra errors and a lot of extra work.

    To solve these problems, we recommend ACTA to implement a mass customization strategy. Of course, not all of ACTA’s products can be mass customized, but to a large extent it should be possible. To implement a mass customization strategy, we argue that ACTA should take three measures, namely design standard products, modularize the products, and implement a computerized configuration tool. We also suggest that the implementation of the new market offer should be done stepwise. With the proposed new market offer, we believe that ACTA can increase profitability in the area of fixtured nutrunners without losing the flexibility of the products.

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  • 309.
    Criscuolo, Ivan
    et al.
    Department of Mechanical Engineering, University of Salerno, Fisciano, Italy.
    Leufvén, Oskar
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Thomasson, Andreas
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Model-Based Boost Pressure Control with System Voltage Disturbance Rejection2011Ingår i: Proceedings of the 18th IFAC World Congress, 2011 / [ed] Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro, International Federation of Automatic Control (IFAC) , 2011, s. 5058-5063Konferensbidrag (Refereegranskat)
    Abstract [en]

    Actuation systems for automotive boost control incorporate a vacuum tank and PWM controlled vacuum valves to increase the boosting system flexibility. Physical models for the actuator system are constructed using measurement data from a dynamometer with an engine having a two stage turbo system. The actuator model is integrated in a complete Mean Value Engine Model and a boost pressure controller is constructed. The developed model is used as basis for a nonlinear compensator, that is capable of rejecting disturbances from system voltage. An IMC based boost pressure controller is developed for the vacuum actuator and engine by using the engine model and then tested on the test cell. The controller performance is quantified and system voltage disturbance rejection is demonstrated.

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    fulltext
  • 310. Beställ onlineKöp publikationen >>
    Cronemyr, Peter
    Linköpings universitet, Institutionen för konstruktions- och produktionsteknik. Linköpings universitet, Tekniska högskolan.
    Towards a learning organization for product development2000Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [sv]

    Kostnaderna för ändringar sent i produktutvecklingsprojekt på grund av missförstånd tidigare i projektet är mycket höga, även om inget företag vill erkänna hur höga de verkligen är. Baserat på erfarenheter från svensk industri och på resultat från tidigare forskning inom området drasslutsatsen att människor måste tala med varandra för att kunna förstå varandra och därmed undvika missförstånd. Informationsteknik kan användas för att öka frekvensen och mängden information som kommuniseras inom en produktutvecklingsorganisation men den kan inte ersätta samtal mellan människor. Detta forskningsprojekt har som mål att presentera metoder som ska kunna användas för att förbättra måluppfyllelsen vid utveckling av nya produkter, det vill säga färre missförstånd ska ge en förbättrad produkt- och processkvalitet, vilket i sin tur medför sänkta kostnader och förkortade ledtider. Ytterligare ett mål är att presentera en metod för att öka det organisatoriska lärandet, vilket skulle förbättra en organisations förmåga att anpassa sig till förändringar i dess omvärld. Det övergripande målet är mer konkurrenskraftiga företag.

    Följande bidrag till forskningsområdet Metoder och organisation för ledning av ingenjörsarbete (Engineering Management på engelska) lämnas i denna avhandling: (i) En modell för ledning av ingenjörsarbete är en teoretisk modell av hur tre olika ledningsfilosofier kan användas tillsammans för att förbättra det organisatoriska lärandet inom en produktutvecklingsorganisation baserat på Senges ramverk ‘De fem disciplinerna’. (ii) Fantomturbinutveckling är en presentation av hur ingenjörer som arbetar med utveckling av teknik och process för produktutveckling kan dela mål och visioner baserade på framtida kundbehov. (iii) Simulering av processförbättringar är en metod för att simulera och jämföra förbättringar av en utvecklingsprocess innan de införs. (iv) Kunskapsöverlappningsseminarium (KOS) är en kommunikationsmetod som ingenjörer i ett produktutvecklingsteam kan använda för att eliminera missförstånd. Hinder som uppträder i vanliga möten undviks i KOS.

    Aktionsforskning har använts som forskningsmetod. Forskningen har utförts på ABB STAL, ett företag som tillverkar gasturbiner och ångturbiner, där författaren till denna avhandling är anställd. Det använda angreppssättet, samverkande aktionsforskning, karaktäriseras av att forskaren i stort sett totalt identifierar sig med företagets aktiviteter och förändringsriktning, vilket väl överensstämmer med forskningen inom detta projekt som till stor del är baserat på författarens egna erfarenheter.

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    Towards a learning organization for product development
  • 311.
    Cronemyr, Peter
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Kvalitetsteknik. Linköpings universitet, Tekniska högskolan.
    Poksinska, Bozena
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Kvalitetsteknik. Linköpings universitet, Tekniska högskolan.
    Assessing the Quality of Elderly Care – Can Survey Incomparability be Solved by Vignettes?2014Ingår i: Proceedings of the 21st EurOMA conference, Palermo, Italy, Palermo, Italy., 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    User and customer surveys are the most commonly used instruments to evaluate the efficiency and quality of public services, but an important question is whether the data collected by the surveys are of sufficient quality to support decision making and improvements of public services. One of the mentioned problems is the interpersonal incomparability of survey responses, which may be biased if individuals interpret the questions in different ways and use response scales in systematically different ways. The purpose of the present study is therefore to investigate how the use of anchoring vignettes could improve the quality of survey results. Our results show that anchoring vignettes remove some noise from survey results and allow the correction of otherwise interpersonally incomparable survey responses. The suggested methodology has the potential to contribute to better evaluations of the quality of elderly care and, thereby, to better decisions on how to improve elderly care services.

  • 312.
    Dadfar, Hossein
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell ekonomi. Linköpings universitet, Tekniska fakulteten.
    Dahlgaard, Jens Jörn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell ekonomi. Linköpings universitet, Tekniska fakulteten.
    Afazeli, Siamack
    MBA ProMA Program.
    Brege, Staffan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell ekonomi. Linköpings universitet, Tekniska fakulteten.
    Quality, export and domestic market performance: the case of pharmaceutical firms in Iran2015Ingår i: Total quality management and business excellence (Online), ISSN 1478-3363, E-ISSN 1478-3371, Vol. 26, nr 9-10, s. 938-957Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study examines the relationship between export involvement/performance and domestic market performance of pharmaceutical enterprises in Iran, an area which has remained largely unresearched. The study seeks to address the following three research objectives: first, to assess the export performance of Iranian pharmaceutical companies; second, to assess the performance of Iranian pharmaceutical companies in the domestic market; and third, to examine the relationship between export involvement/performance and domestic market performance. Although existing literature claims that local performance (rivalry) leads to export performance, this study reveals that in the Iranian pharmaceutical industry, export involvement and performance enhance local market performance. The study provides empirical evidence on the relationship between export performance and domestic market performance, and adds depth to the understanding of the reasons why the traditional views did not explain the situation. A comprehensive literature review was used to build our conceptual and analytical framework upon the Export Performance (EXPERF) model for export performance evaluation. The European Foundation for Quality Management (EFQM) Excellence Model and assessment indicators of Innovativeness, Learning and Lean indices were used for measuring domestic performance. By using clustering, six clusters of similar companies were identified and the centroids of the six clusters chosen to verify the relationship between export performance and domestic performance. Correlation analyses confirmed that there was a significant positive relation between export performance and domestic performance. This means that export performance results in better domestic performance, and vice versa.

  • 313.
    Dahl, Elin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska högskolan.
    Energy companies becoming energy service providers: A comparative study between Denmark and Sweden2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Energy efficiency is important – but an energy saving potential has yet to reach its full range. Energy services are means to reach that potential and energy companies are stressed as important actors into creating an established market for energy services. Energy services are tools that include providing in-direct services such as energy statistics, audits, declarations, consultations and analysis. It also includes a number of more complex and direct services, for example energy efficiency measurements or service contracts.

    This report is a result of a study on Danish and Swedish energy companies offering energy services, based on the market they act upon. It aims to find their driving forces for providing energy services. It also looks closer into whether publically and privately owned energy companies differ and if there exist contradictions to both supply energy and energy services at the same time. It also looks into how energy companies are affected and feel about national regulatory instruments.

    Energy companies in both countries offering energy services are reaching a wide spectrum of client segments and energy services. They often have the possibility to combine and package energy supply with energy services and they can reduce many of the theoretical barriers to energy efficiency by offering energy services. They are driven by a client demand and a closer client relationship, both leading to a decreased supply client fluctuation. A new business opportunity and a green profile strategy are also driving factors. Energy services also help energy companies to decrease heavy investment on existing equipment by having more control over their clients’ energy use and reducing energy utilization tops.

    Danish energy companies are tied to an energy saving obligation scheme, providing them with conditions, which their market is based, whilst Swedish energy companies offering energy services act on a market that is created by them and their competitors derive from different business backgrounds. There exist an assertive regulatory instrument in Denmark affecting driving factors for public and private energy companies and clients. In Sweden regulatory instruments, such as energy efficiency programmes, subsidises for energy audits and voluntary agreements for industries affect energy companies in a less way than in Denmark, mostly increasing a client demand for energy services. The regulatory instruments in Denmark increase a trust for energy companies as energy service providers as in Sweden they are trusted upon their existing substantial role on the energy market, a reputation of knowledge and experience and a strategy aiming towards visualisation, motivation and education for the clients.

    Public energy companies feel a responsibility towards their public owners to offer an efficient energy supply and by having a local connection to the municipality they are able to increase competiveness in the region by offering energy services. Private companies are substantially larger than public companies and have a great potential to reach out to a larger number of clients through their existing supply client stock. This is of substantial higher relevance in Sweden than Denmark. 

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    Energy companies becoming energy service providers - Master thesis, 2012 - Elin Dahl
  • 314.
    Dahlberg, Joen
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Andersson Granberg, Tobias
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Polishchuk, Tatiana
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Schmidt, Christiane
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Sedov, Leonid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Capacity-Driven Automatic Design of Dynamic Aircraft Arrival Routes2018Ingår i: 2018 IEEE/AIAA 37TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC), IEEE , 2018, s. 1194-1202Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a Mixed-Integer Programming framework for the design of aircraft arrival routes in a Terminal Maneuvering Area (TMA) that guarantee temporal separation of aircraft. The output routes constitute operationally feasible merge trees, and guarantee that the overall traffic pattern in the TMA can be monitored by air traffic controllers; in particular, we ensure that all aircraft on the arrival routes are separated in time and all merge points are spatially separated. We present a proof of concept of our approach, and demonstrate its feasibility by experiments for arrival routes during one hour at Stockholm TMA.

  • 315.
    Dahlberg, Tore
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    On the Use of Under-Sleeper Pads in Tracks with Varying Track Stiffness2009Ingår i: Proc 9th International Heavy Haul Conference, June 2009, Shanghai, P R China: Heavy Haul and Innovation Development, Beijing, China: China Railway Publishing House , 2009, s. 293-299Konferensbidrag (Refereegranskat)
    Abstract [en]

    The track stiffness experienced by a train will vary along the track. Sometimes the stiffness variation may be very large within a short distance. One example is when an unsupported sleeper is hanging in the rail. Track stiffness is then, locally at that sleeper, very low. At insulation joints the bending stiffness of the rail has a discontinuity. A third example of an abrupt change of track stiffness is the transition from an embankment to a bridge.

    The variations of track stiffness will induce variations in the wheel/rail contact force. This will intensify track degradation such as increased wear, fatigue, track settlement due to permanent deformation of the ballast and the substructure, and so on. In the work reported here the possibility to smooth out track stiffness variations by use of under-sleeper pads is discussed. It is demonstrated that the wheel/rail contact force variations can be made small by modifying the stiffness variations along the track.

  • 316.
    Dahlberg, Tore
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Railway track stiffness variations - consequences and countermeasures2009Ingår i: Proc of the 2nd International Conference on Recent Advances in Railway Engineering, Teheran: Iran University of Science and Technology , 2009, s. 38-46Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The track stiffness experienced by a train will vary along the track. Sometimes the stiffness variation may be very large within a short distance. One example is when an unsupported sleeper is hanging in the rail. Track stiffness is then, locally at that sleeper, very low. At insulated joints the bending stiffness of the rail has a discontinuity implying a discontinuity also of the track stiffness. A third example of an abrupt change of track stiffness is the transition from an embankment to a bridge. At switches both mass and stiffness change rapidly.

     

    The variations of track stiffness will induce variations in the wheel/rail contact force. This will intensify track degradation such as increased wear, fatigue, track settlement due to permanent deformation of the ballast and the substructure, and so on. As soon as the track geometry starts to deteriorate, the variations of the wheel/rail interaction forces will increase, and the track deterioration rate increases. In the work reported here the possibility to smooth out track stiffness variations is discussed. It is demonstrated that by modifying the stiffness variations along the track, for example by use of grouting or under-sleeper pads, the variations of the wheel/rail contact force may be considerably reduced.

  • 317.
    Dahlberg, Tore
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Vågutbredning i kontaktledningar (Wave propagations in contact wires, in Swedish).2009Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Teoretisk analys av vågutbredning i kontaktledning modellerad som en spänd sträng med böjstyvhet (eller axialbelastad balk) belastad med rörlig kraft.

  • 318.
    Dahlgaard, Jens Jörn
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Kvalitetsteknik. Linköpings universitet, Tekniska högskolan.
    Dahlgaard-Park, Su Mi
    Lund University, Sweden.
    Chen, Chi-Kuang
    Yuan Ze University, Taiwan.
    Editorial Material: Quality excellence in Taiwan: theories and practices in TOTAL QUALITY MANAGEMENT and BUSINESS EXCELLENCE, vol 26, issue 1-2, pp2015Ingår i: TOTAL QUALITY MANAGEMENT and BUSINESS EXCELLENCE, ISSN 1478-3363, Vol. 26, nr 1-2Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 319.
    Dahlgaard, Jens Jörn
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Logistik- och kvalitetsutveckling. Linköpings universitet, Tekniska fakulteten.
    Pugna, Adrian
    Politehn University of Timisoara, Romania.
    Potra, Sabina
    Politehn University of Timisoara, Romania.
    Negrea, Romeo
    Politehn University of Timisoara, Romania.
    Mocan, Marian
    Politehn University of Timisoara, Romania.
    A greenhouse approach for value cultivation2016Ingår i: Total quality management and business excellence (Online), ISSN 1478-3363, E-ISSN 1478-3371, Vol. 27, nr 7-8, s. 836-852Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present paper explores design requirements to take into consideration when designing and developing new products or services. The purpose of this article is to develop a strategic approach for analysing variations between potential customer needs in order better to understand what qualities should be further cultivated before product launch. This new approach is called A Greenhouse Approach for Value Cultivation. Case study data of a new web-based customisation service for a Romanian shoe manufacturing company has been re-analysed by using questionnaire data on 166 respondents perceptions on 14 attributes importance and value. A nonlinear regression model was developed and used to understand relations between importance and value. Such relations were used together with the Greenhouse Model to better understand the service attributes potential life cycles if selected for further cultivation. The Greenhouse Model envisages new perspectives of the evaluation of customer needs to support strategic decision-making regarding further value cultivation for profound affection (= customer delight). Even if there is a need for further tests the suggested Greenhouse Approach for Value Cultivation is regarded as a new and original contribution to the theory of attractive quality creation which deepens its position in the theory of attractive quality and transforms it into a practical management tool to support new product and service design.

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    fulltext
  • 320.
    Dahlgaard-Park, Su Mi
    et al.
    Lund University, Sweden.
    Dahlgaard, Jens Jörn
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Logistik- och kvalitetsutveckling. Linköpings universitet, Tekniska fakulteten.
    Editorial Material: Untitled in TOTAL QUALITY MANAGEMENT and BUSINESS EXCELLENCE, vol 26, issue 9-10, pp 933-9372015Ingår i: Total quality management and business excellence (Online), ISSN 1478-3363, E-ISSN 1478-3371, Vol. 26, nr 9-10, s. 933-937Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 321.
    Dahlström, Nicklas
    et al.
    Lund University School of Aviation, Ljungbyhed, Sweden/Swedish Defence Research Agency, Linköping, Sweden.
    Magnusson Nählinder, Staffan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan.
    A Comparison of Two Recorders for Obtaining In-flight Heart Rate Data2006Ingår i: Applied Psychophysiology and Biofeedback, ISSN 1090-0586, E-ISSN 1573-3270, Vol. 31, nr 3, s. 273-279Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measurement of mental workload has been widely used for evaluation of aircraft design, mission analysis and assessment of pilot performance during flight operations. Heart rate is the psychophysiological measure that has been most frequently used for this purpose. The risk of interference with flight safety and pilot performance, as well as the generally constrained access to flights, make it difficult for researchers to collect in-flight heart rate data. Thus, this study was carried out to investigate whether small, non-intrusive sports recorders can be used for in-flight data collection for research purposes. Data was collected from real and simulated flights with student pilots using the Polar Team System sports recorder and the Vitaport II, a clinical and research recording device. Comparison of the data shows that in-flight heart rate data from the smaller and less intrusive sports recorder have a correlation of.981 with that from the clinical recorder, thus indicating that the sports recorder is reliable and cost-effective for obtaining heart rate data for many research situations.

  • 322.
    Dahlström, Nicklas
    et al.
    Lund University School of Aviation, Ljungbyhed, Sweden.
    Magnusson Nählinder, Staffan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan. Swedish Defence Research Agency , Linköping, Sweden.
    Mental Workload in Aircraft and Simulator during Basic Civil Aviation Training2009Ingår i: The International journal of aviation psychology, ISSN 1050-8414, E-ISSN 1532-7108, Vol. 19, nr 4, s. 309-325Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This study investigated mental workload in basic civil aviation training. Heart rate, eye movement and subjective ratings from eleven students were collected during simulator and aircraft sessions. Results show high correspondence in psychophysiological reactions between the sessions. For some flight segments heart rate was consistently lower in the simulator, suggesting higher mental workload in the aircraft. Differences in heart rate during rejected take-off and engine failure indicate that the increase of workload starts in advance of an “unexpected“ event in the simulator and seem to be of preparatory nature, while more connected to management of the situation in the aircraft. Descriptors: psychophysiology, mental workload, aviation training, flight simulation, learning transfer

  • 323.
    Dahlström, Nicklas
    et al.
    Lund University School of Aviation, Ljungbyhed, Sweden.
    Magnusson Nählinder, Staffan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska högskolan. Swedish Defence Research Agency , Stockholm, Sweden.
    Wilson, Glenn F.
    Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio, USA.
    Svensson, Erland
    Swedish Defence Research Agency , Stockholm, Sweden.
    Recording of Psychophysiological Data during Aerobatic Training2011Ingår i: The International journal of aviation psychology, ISSN 1050-8414, E-ISSN 1532-7108, Vol. 21, nr 2, s. 105-122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measuring pilot mental workload can be important for understanding cognitive demands during flight involving unusual movements and attitudes. Heart rate, eye movements, EEG and subjective ratings from seven flight instructors was collected for a flight including a repeated aerobatics sequence. Heart rate data and subjective ratings showed that aerobatic sequences produced the highest levels of mental workload and that heart rate can identify low-G flight segments with high mental workload. Blink rate and eye movement data did not support previous research regarding their relation to mental workload. EEG data was difficult to analyze due to muscle artifacts.

  • 324.
    Dalibon, Eugenia. L.
    et al.
    UTN, Argentina.
    Czerwiec, Thierry
    Univ Lorraine, France.
    Trava-Airoldi, Vladimir J.
    INPE, Brazil.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Bruhl, Sonia P.
    UTN, Argentina.
    Characterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles2019Ingår i: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMRandT, ISSN 2238-7854, Vol. 8, nr 2, s. 1653-1662Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel.Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp(3)/sp(2) bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer. Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 degrees C in several steps. After each cycle, Raman spectra and surface topography measurements were performed and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance. The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.

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    fulltext
  • 325.
    Danielsson, Per-Erik
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Implementations of the Convolution Operation1982Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The first part of this article surveys a large number of implementations of the convolution operation (which is also known as the sum-of-products, the inner product) based on a systematic exploration of index permutations. First we assume a limited amount of parallelism in the form of an adder. Next, multipliers and RAM:s are utilized. The so called distributed arithmetic follows naturally from this approach.

    The second part brings in the concept of pipelining on the bitlevel to obtain high throughput convolvers adapted for VLSI-design (systolic arrays). The serial/parallel multiplier is analyzed in a way that unravels a vast amount new variations. Even more interesting, all these new variations can be carried over to serial/parallel convolvers. These novel devices can be implemented as linear structures of identical cells where the multipliers are embedded at equidistant intervals.

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    Implementations of the Convolution Operation
  • 326.
    Dannapfel, Petra
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för samhällsmedicin. Linköpings universitet, Hälsouniversitetet.
    Poksinska, Bozena
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Kvalitetsteknik. Linköpings universitet, Tekniska högskolan.
    Thomas, Kristin
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för samhällsmedicin. Linköpings universitet, Hälsouniversitetet.
    Dissemination strategy for Lean thinking in health care2014Ingår i: International Journal of Health Care Quality Assurance, ISSN 0952-6862, E-ISSN 1758-6542, Vol. 27, nr 5, s. 391-404Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose – The purpose of this paper is to contribute to knowledge about dissemination strategies for Lean thinking throughout multiple healthcare organisations.

    Design/methodology/approach – The Östergötland county council, Sweden (CCÖ ) was chosenas a case study for an healthcare Lean-thinking dissemination strategies. Document analysis and interviews were used and results were compared with similar strategies employed by staff at the National Health Service Institute for Innovation (NHSI) and improvement in Great Britain and the Odense University Hospital in Denmark.

    Findings – The Lean improvement programme was introduced to tackle challenges such as anageing society, rising care expectations and budgetary and economic constraints. It was designedas a long-term programme to create added value for patients and employee involvement. The dissemination strategy was: forming clear visions and objectives; piloting; training potential adopters; and formal dissemination. The CCÖ strategy was focused primarily on managers and was not meant to involve all staff until the implementation stage. Staff at the NHS attempted to address nurses’ needs during dissemination, which questioned whether the CCÖ managers’ dissemination strategy is sustainable.

    Practical implications – This paper inspires healthcare managers and decision makers who aim to disseminate Lean production in their organisations.

    Originality/value – There are many case studies describing Lean implementation in single healthcare organisations, but little is known about effective dissemination and implementation strategies in large healthcare systems. The authors, therefore, suggest activities for developing and implementing dissemination strategies in multiple healthcare organisations.

  • 327.
    Davidsson, Nina
    et al.
    Service Research Center, Karlstad University.
    Edvardsson, Bo
    Service Research Center, Karlstad University.
    Gustafsson, Anders
    Service Research Center, Karlstad University.
    Witell, Lars
    Service Research Center, Karlstad University.
    Degree of service-orientation in the pulp and paper industry2009Ingår i: International Journal of Services Technology and Management, ISSN 1460-6720, E-ISSN 1741-525X, Vol. 11, nr 1, s. 24-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many companies in the process industries are seeing the advantages of services but are struggling with the changes these require as regards the offering and the organisation. This paper presents an empirical investigation within the pulp and paper industry based on a survey of Swedish manufacturing firms and a multiple case study of three case companies and their customers. To investigate whether the manufacturers active in this industry are product-oriented or are becoming more service-oriented, five themes important to the companies under study are presented and discussed: that is, finding the right mix of physical products and services, the concept of service, business models, technology-based services and organising service delivery.

  • 328.
    de Brun Mangs, Jonathan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system.
    Tillquist, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system.
    Evaluation of a Programmable Hydraulic Valve for Drill Rig Applications2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The increase of intelligent systems can be seen in every industry. Integrated sensors and processors are used with internal control systems to create better performance for mobile hydraulic applications.

    The report describes how an evaluation was made to see if the productivity of a drill rig could be increased. This was done by implementing a programmable hydraulic valve to control the hydraulic drilling functions. The productivity would be increased by reducing the downtime due to jamming in the drill hole. Jamming occur when the system does not compensate for changes in rock conditions. By conducting a series of tests in a controlled environment with simulated loads, the response time of the CMA system and original system could be determined and compared. The CMA system had a response time that was 60-64% faster than the original system.

    Two different implementations of a controller was tested. Ziegler-Nichols method was used to get the initial value of the PI parameters. The controller that was implemented onboard the valve’s CPU was considered more successfull to reduce jamming.

    A drill test was conducted to ensure that the programmable valve could handle a drilling procedure with the controller that was implemented onboard the valve’s CPU. The valve handled the drilling procedure well.

    Ladda ner fulltext (pdf)
    Evaluation of a Programmable Hydraulic Valve for Drill Rig Applications
  • 329. Beställ onlineKöp publikationen >>
    de Paula, Andes
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell marknadsföring och industriell ekonomi. Linköpings universitet, Tekniska högskolan.
    Dynamics of corporate strategy from a value chain perspective: A study of the Swedish telecom and construction industries during the 90’s2006Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Changes in sectors and industries have brought new challenges to corporations as well as been important driving forces for the dynamics in strategy at the corporate level. With the dramatic developments of the 1990’s in mind, such as multilateral free-trade agreements, liberalization, privatization, sharp industry growth/decline, increased competition and globalization, in particular within the telecom and the construction industry, this study contributes to describing and understanding strategic change at the corporate level as well as changes in the division of work within value chains. Strategy is defined as intentions, decisions and actions that relate to bundling and unbundling at different strategic levels, aiming to establish and reestablish a value chain position. Thus, outsourcing, M&As, modularization and systems development and sales are important strategic components which are examined from a value chain perspective. From a value chain perspective, the purpose of this study is to describe and understand strategic change at the corporate level in the telecom and construction industries during the 1990’s. More specifically this study shall contribute to describing and understanding (i) the dynamics of and between M&As, outsourcing, modularization and systemization, as well as (ii) industrial and financial drivers to strategic change.

    The conclusions describe strategic change from a value chain perspective using three descriptive patterns, including an increasing degree of specialization and need for interorganizational coordination across the value chain. In addition, outsourcing and modularization of systems and an increased scope of offering through systemization and BOT-projects, result in the fact that due to M&As the horizontal boundary of the firm sometimes goes beyond the industry scope while the vertical scope is often narrowed through outsourcing. The conclusions also focus on understanding the content of strategic change, that is to say the dynamics of and between mergers and acquisitions, outsourcing, modularization and system sales. These findings are summarized in nine explanatory patterns. These patterns show that the strategic decisions of bundling and unbundling at the corporate and functional level through mergers and acquisitions, outsourcing, systemization and modularization are guided by an industrial as well as a financial logic. By considering the descriptive and explanatory patterns found this study, the conclusions also include what to expect during the next decade with regard to corporate strategy from a value chain perspective in five predictive patterns.

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  • 330.
    de Vries, Frank
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära.
    Inverkan av värme på lagerlägets cylindricitet i ett lagerhus2010Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det här examensarbetet har utförts hos och med stöd av SKF Mekan i Katrineholm. Grundfrågeställningen som innebar upphovet till examensarbetet är om värme påverkar lagerlägets cylindricitet hos ett lagerhus. Detta avgränsas senare till att gälla enbart värmepåverkan under produktion för en typ av lagerhus i en storlek men tre olika materialval. Därmed koncentreras arbetet på gjuterilinan för de mindre lagerhusen samt den bearbetningslina som kallas ”Robot line”.

    Inledningsvis ges en presentation vad lager och lagerhus är samt vilken funktion de fyller. Därefter ges en överblick av gjuteriet samt bearbetningen. Berörda linor betraktas mer ingående men även övriga linor ges en övergripande bild av. Övriga resurser såsom mätrum samt testlabb presenteras också.

    De tre olika materialen granskas för att se vilka avgörande skillnader som finns dem emellan. Detta med hjälp av litteratur samt intervjuer med medarbetare hos SKF Mekan, personal vid Linköpings universitet samt SWEREA.

    Två test som genomförts under arbetets gång beskrivs, varav det ena lyckat men det andra misslyckat. Dock fick det andra testet ett överraskande resultat.

    Befintliga kontroller längs med produktionskedjan omtalas.

    Slutligen sammanfattas vilka moment inom gjuteri- samt bearbetningsprocessen där toleransen för cylindriciteten hos lagerläget riskerar att under-/överskridas samt vad som då är orsaken.

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  • 331.
    Dell' Amico, Alessandro
    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.
    Henriksen, Fredrik
    Skogforsk, the Swedish Forestry Research Institute of Sweden.
    Krus, Petter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Modelling and experimental verification of a secondary controlled six-wheel pendulum arm forwarder2015Ingår i: the 13th European Conference of ISTVS / [ed] Roberto Paoluzzi, 2015, s. 1-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines duringharvesting, where damages can have a negative impact on e.g. further growth. One of the main reasons is wheel slip.Another concern is the working environment of the operator due to the harsh ground in the forest. Both these issueshave a negative impact on productivity. An attempt to overcome these challenges is made within a collaborative researchproject, which among others also includes Linköping University, where a new six-wheel pendulum arm forwarder isbeing developed. The new forwarder aims at reducing the soil damage by an even pressure distribution and smooth torquecontrol, as well as increased damping of the complete chassis, and thereby improving the working environment. This ispossible since each wheel, driven by its own hydraulic motor, is attached to a pendulum arm allowing to control the heightof each wheel independently of each other. The forwarder has a total maximum weight of 31 tonnes, including 14 tonnesmaximum load. It consists of two steerable joints and is driven by a 360 bhp diesel engine. The transmission consists oftwo hydraulic pumps and six hydraulic motors.This paper deals with the development of the driveline and presents the first experimental tests of the implementedcontrol strategies, where a secondary control approach is chosen for its ability to individually control the torque on eachwheel. The control strategies, presented in the paper, include pressure control, velocity control of the vehicle and ananti-slip controller. To support the development of the control strategies, models of the vehicle and hydraulic subsystemsare derived. The aim with this paper is to verify the concepts on the actual vehicle. The initial results are promising,indicating that the suggested concept is feasible.

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    fulltext
  • 332.
    Dell'Amico, Alessandro
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Hardware-in-the-loop simulering av elektrohydraulisk servostyrning för tunga fordon2012Ingår i: Hydraulikdagarna 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Ökade krav på säkrare fordon i trafiken har lett till att forskningen har inriktat sig mot mer styrningsrelaterade säkerhets-funktioner. I ett komplett scenario används ett flertal sensorer för att detektera bl.a. hinder och fordonets placering på vägen.Denna information nyttjas sedan för att skapa en hotbild och beslut måste tas för att undvika en kommande olycka. I grundenmåste det finnas en aktuator som tillåter att ändra hjulvinkeln eller det moment som krävs för att vrida hjulen. Samtidigt ökar ständigt kraven på lägre utsläpp för fordon, där även styrservot är en bidragane faktor. I personbilsindustrin har man löst detta genom att införa ett rent elektriskt styrservo. Till skillnad mot det traditionella styrservot som är rent hydraulmekaniskt, kan man i ett elektriskt styrservo manipulera den assistans som servot ger samtidigt som energiförbrukning minskar dramatiskt. För tunga fordon är det idag inte möjligt att införa rent elektrisk styrservo, framförallt p.g.a. de stora laster som förekommer. Detta projekt syftar till att undersöka möjligheterna att implementera aktiv styrning i tunga fordon samtidigt som energiförbrukning kan minskas. Detta görs med hjälp av en konceptstudie där hardware-in-the-loop simulering är en viktig del för att untvärdera olika koncept. Testriggen som har tagits fram består till hårdvaran av ett styrservo och till mjukvaran av en fordonsmodell. Testriggen är generisk vilket innebär att vilket koncept som helst inom samma kategori kan implementeras och utvärderas. Därav kan testriggen vara en del i designprocessen.

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    Hydraulikdagarna 2012
  • 333. Beställ onlineKöp publikationen >>
    Dell'Amico, Alessandro
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    On Electrohydraulic Pressure Control for Power Steering Applications: Active Steering for Road Vehicles2016Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with the Electrohydraulic Power Steering system for road vehicles, using electronic pressure control valves. With an ever increasing demand for safer vehicles and fewer traffic accidents, steering-related active safety functions are becoming more common in modern vehicles. Future road vehicles will also evolve towards autonomous vehicles, with several safety, environmental and financial benefits. A key component in realising such solutions is active steering.

    The power steering system was initially developed to ease the driver's workload by assisting in turning the wheels. This is traditionally done through a passive open-centre hydraulic system and heavy trucks must still rely on fluid power, due to the heavy work forces. Since the purpose of the original system is to control the assistive pressure, one way would be to use proportional pressure control valves. Since these are electronically controlled, active steering is possible and with closed-centre, energy efficiency can be significantly improved on.

    In this work, such a system is analysed in detail with the purpose of investigating the possible use of the system for Boost curve control and position control for autonomous driving. Commercially available valves are investigated since they provide an attractive solution. A model-based approach is adopted, where simulation of the system is an important tool. Another important tool is hardware-in-the-loop simulation. A test rig of an electrohydraulic power steering system, is developed.

    This work has shown how proportional pressure control valves can be used for Boost curve control and position control and what implications this has on a system level. As it turns out, the valves add a great deal of time lag and with the high gain from the Boost curve, this creates a control challenge. The problem can be handled by tuning the Boost gain, pressure response and damping and has been effectively shown through simulation and experiments. For position control, there is greater freedom to design the controller to fit the system. The pressure response can be made fast enough for this case and the time lag is much less critical.

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  • 334.
    Dell'Amico, Alessandro
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Carlsson, Marcus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Norlin, Erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Sethson, Magnus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Investigation of a Digital Hydraulic Actuation System on an Excavator Arm2013Ingår i: 13th Scandinavian International Conference on Fluid Power, Linköping University Electronic Press, 2013, s. 505-511Konferensbidrag (Refereegranskat)
    Abstract [en]

    Digital hydraulics is an ongoing trend that offers many interesting advantages and possibilities. Digital refers to that the system output is discrete, e.g. using an on/off valve with only discrete values or a finite amount of flow steps available. The advantages mentioned when compared to analogue systems are better performance, robust and fault tolerant, and amplitude independent bandwidth. On the other side noise and pressure pulsations must be handled, the physical size can be a problem, and the system requires complicated control. When considering control of linear motion, there are mainly two branches, controlling the flow with several parallel connected on/off valves, which generates discrete output flow values, or switching valves, which in theory can generate any mean output flow. The latter only requires one valve for each flow path but the demand for fast valves is very high, while the former requires many valves but avoids high frequent switching. With the introduction of a multi-chamber cylinder, secondary control is now also possible for linear motion. This paper is a first step in the investigation of the system applied to an excavator arm. The cylinder has four chambers, each with different area. Three pressure lines are used and a valve-pack of 27 on/off valves. The valve-pack connects the three pressure lines with each chamber generating 81 available force steps. The scope has been to start out with relative simple control of the velocity of the cylinder. To handle unnecessary switching of valves, different penalty strategies were tested. The results are promising where relatively smooth control could be achieved at the same time challenges with the system were identified. Next step is to investigate the force transients due to different capacitance in all four chambers as well as mode control for better accuracy. Energy potential compared to original system remains to investigate as well.

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    fulltext
  • 335.
    Dell'Amico, Alessandro
    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.
    A Test Rig for Hydraulic Power Steering System Concept Evaluation using Hardware-in-the-Loop Simulation2013Ingår i: ICFP 2013, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper derives a test rig of a power steering system with purpose to investigate the performance of closed-centre valves as actuators in the steering system loop using hardware-in-the-loop simulation. Servo valves are used for independent control of each chamber pressure. The approach is to use a static model of the reference actuator and control the pressures with the servo valves accordingly. A simulation model of the system is used to verify the approach. Results from the test rig are presented from on-centre driving which show how the pressure is controlled satisfyingly.

  • 336.
    Dell'Amico, Alessandro
    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.
    Closed-Centre Hydraulic Power Steering by Direct Pressure Control2014Ingår i: The 9th JFPS International Symposium on Fluid Power : Matsue 2014 : Oct. 28-31, 2014, The Japan Fluid Power System Society , 2014, s. 332-339Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    An ongoing trend in the vehicle industry is the development of steering related active safety functions for increased road safety. For this to be a reality there must exist a steering system that allows to either change the road wheel angle or torque by means of an external signal, called active steering. Due to heavy vehicles’ high axle load, hydraulic power is needed to assist the driver in turning the wheels. This paper looks into a solution where self-regulated pressure control valves are used for electronic control of the assistance pressure in order to realise active steering. The valve has closed-centre for a high potential to reduce the energy consumption. A model based approach is used to analyse the system. A non-linear simulation environment is developed to compare the closed-centre system with the original system. A linear analysis is also performed to discover the influence of valve properties on steering system performance. Results have shown that a feasible solution exists and that there exists a relation between valve dynamics, boost gain and steering system loop stability.

  • 337.
    Dell'Amico, Alessandro
    et al.
    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.
    Modelling and experimental validation of a nonlinear proportional solenoid pressure control valve2016Ingår i: International Journal of Fluid Power, ISSN 1439-9776, Vol. 17, nr 2, s. 90-101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates the static and dynamic behaviour of a pressure control valve with nonlinear negative characteristics. The pressure control valve has both reducing and relieving capability and is actuated by a solenoid. The static characteristics have been measured over the entire working range, covering the dynamic response of the solenoid, as well as the complete valve. A model is proposed that considers the flow as a mix of laminar and turbulent flow and flow forces with a flow angle that varies with the stroke of the spool. The model shows good agreement with measurements. The investigations show that the flow forces decrease with higher flow rates as a result of a flow angle that tends to go towards a vertical angle. This results in an increase in pressure with flow during pressure reducing mode. A linear analysis is also presented, explaining this as a negative spring constant in the low frequency range. Stability is, however, maintained.

  • 338.
    Dell'Amico, Alessandro
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Pohl, Jochen
    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.
    Conceptual Evaluation of Closed-Centre Steering Gears in Road Vehicles2012Ingår i: Proceedings of the 7th FPNI PhD Symposium on Fluid Power, 2012 / [ed] Massimo Milani, Luca Montorsi, Fabrizio Paltrinieri, 2012, s. 433-452Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper is a study into the possibility to use a self-regulated pressure control valve as a way of realizing active steering into road vehicles by hydraulic means. From an actuator point of view, active steering refers to the possibility to control the assistance pressure via an external signal. From the steering system control loop, it is seen that the task of the steering system is to control the assistance pressure in each chamber of the assistance cylinder. A methodology is also derived for investigating the concept and finding a set of design parameters based on system requirements. This is based on a linear approach and later a simulation of the complete steering system with vehicle and driver. In order to assure good control accuracy during fast actuation of the valve a high gain is required. This would require an over damped valve with large proportions. This design was tested to verify the design methodology. A feasible design based on maximum available spool force was also tested. This design showed to large deviation in steering wheel torque compared to the original system.

  • 339.
    Dell'Amico, Alessandro
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluid och mekanisk systemteknik. Linköpings universitet, Tekniska högskolan.
    Pohl, Jochen
    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.
    Modeling and Simulation for Requirement Generation of Heavy Vehicles Steering Gears2010Ingår i: Fluid Power and Motion Control (FPMC 2010) / [ed] D N Johnston and A R Plummer, Centre for Power Transmission and Motion Control , 2010, s. 475-490Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today’s passenger vehicles are becoming more and more safe as more steering related active safety functions are being introduced. As an example, lane keeping assist functions or even electronic vehicle stability with steering intervention can be mentioned. However, the same trend can yet not be witnessed for heavy vehicles, which is, among others, due to a lesser degree of controllability of the steering system. While electric power assisted steering has been introduced in passenger cars in recent years on a broader basis, electric power assisted steering is yet not suitable for heavy vehicles due to heavier loads on the steering rack. Heavy vehicles thus lack a freely programmable steering system.The purpose of this paper is to generate and evaluate the requirements of future hydraulic actuation concepts for heavy vehicles, where emphasis is put on the required steering actuator linearity and bandwidth. Both actuator response and linearity are decisive for transmitting a proper steering feel to the driver. In this study we provide a structured approach to derive the required bandwidth as a function of the system sizing and provide a simulation supported method for deriving the requirements of linearity and accuracy.

  • 340.
    Dell'Amico, Alessandro
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska högskolan.
    Sethson, Magnus
    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.
    Modeling, Simulation and Experimental Verification of a Solenoid Pressure Control Valve2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Simulation is a great tool to help the development of products. For simulation to be a validtool there are high demands on the models, where they need to be accurate and fast, regardingcomputational time.  This work is a first step to model and implement a 4 wheel drive system.The system is electronically controlled and the torque transferred by the system is dependenton the pressure built up by the hydraulic system. This work focuses primary on the develop-ment of the solenoid pressure control valve model. In order to perform simulations, the valvemodel needs to be connected to the rest of the system. The supply pressure is provided froma piston accumulator, that is implemented only to provide the right functionality at this stage.The load in this system is composed of a wet multiplate clutch, that is implemented only as astatic model based on measurements. The modeling of the valve was divided into studying theelectromagnetical part and hydromechanical part separately. The electromagnetical part, i.e.the solenoid, is modeled as a resistor in series with a nonlinear inductor. The electromagneticcharacteristics is modeled with the help of a curve fitting technique. A testbench was developedfor this purpose. The simulation results of the solenoid agrees well with measured results. Alinearized analysis of the hydromechanical part was performed in order to better understand thedynamics of the valve and see the most dominant effects. Two valve configurations resultedfrom this work. One includes more dynamics and has the possibility to change more param-eters in order to study different effects. The other configuration was based on the linearizedanalysis and therefore includes only the most dominant dynamics. This model is much fasterto simulate. Both configuration shows accurate results when compared to measurements of thesystem.

  • 341.
    Deng, Dunyong
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Robert
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    On the Dwell-Fatigue Crack Propagation Behavior of a High-Strength Ni-Base Superalloy Manufactured by Selective Laser Melting2019Ingår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study focuses on the dwell-fatigue crack propagation behavior of IN718 manufactured via selective laser melting (SLM). The dwell-fatigue test condition is 823 K (550 with a long 2160-s dwell-holding period. Effects of heat treatment and loading direction on dwell-fatigue crack propagation rates are studied. A grain boundary delta precipitate seems to be slightly beneficial to the dwell-fatigue cracking resistance of SLM IN718. A comparison has been made between SLM IN718 and forged counterparts at different temperatures, indicating that a creep damage mechanism is likely dominant for SLM IN718 under the present test condition. A general discussion of the inferior creep resistance of SLM IN718 is also included. The anisotropic dwell-fatigue cracking resistance has also been studied and rationalized with the effective stress intensity factor calculated from finite element modeling.

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    fulltext
  • 342.
    Dermentzis, Georgios
    et al.
    Unit for Energy Efficient Building, University of Innsbruck, Innsbruck, Austria.
    Ochs, Fabian
    Unit for Energy Efficient Building, University of Innsbruck, Innsbruck, Austria.
    Gustafsson, Marcus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska fakulteten.
    Calabrese, Toni
    Unit for Energy Efficient Building, University of Innsbruck, Innsbruck, Austria.
    Siegele, Dietmar
    Unit for Energy Efficient Building, University of Innsbruck, Innsbruck, Austria.
    Feist, Wolfgang
    Unit for Energy Efficient Building, University of Innsbruck, Innsbruck, Austria; Passive House Institute, Darmstadt, Germany.
    Dipasquale, Chiara
    EURAC Research, Bolzano, Italy.
    Fedrizzi, Roberto
    EURAC Research, Bolzano, Italy.
    Bales, Chris
    Energy Technology, Dalarna University, Falun, Sweden.
    A comprehensive evaluation of a monthly-based energy auditing tool through dynamic simulations, and monitoring in a renovation case study2019Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 183, s. 713-726Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An energy auditing tool (PHPP) was evaluated against a dynamic simulation tool (TRNSYS) and used for the assessment of energy conservation measures in a demo case study. The comprehensive comparison of heating and cooling useful demands and loads included three building types (single-, multi-family house, and office), three building energy levels (before renovation and after renovation with a heating demand of 45 and 25 kWh/(m²·a)) and seven European climates.

    Dynamic simulation results proved PHPP (monthly energy balance) to be able to calculate heating demand and energy savings with good precision and cooling demand with acceptable precision compared to detailed numerical models (TRNSYS). The average deviation between the tools was 8% for heating and 15% for cooling (considering climates with a relevant cooling load only). The higher the thermal envelope quality was, i.e. in case of good energy standards and in cold climates, the better was the agreement. Furthermore, it was confirmed that PHPP slightly overestimates the heating and cooling loads by intention for system design.

    The renovation design of a real multi-family house was executed using PHPP as energy auditing tool. Several calculation stages were performed for (a) baseline, (b) design phase, and (c) verification with monitoring in order to calculate the corresponding heating demand. The PHPP model was calibrated twice, before and after the renovation. The necessity for tool calibration, especially for the baseline, was highlighted increasing the confidence with respect to a number of boundary conditions.

    In this study, PHPP was tested as an energy auditing tool aiming to be a versatile and less error-prone alternative to more complex simulation tools, which require much more expert knowledge and training.

  • 343.
    Dervisic, Admir
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik.
    Kraftberäkning på transportsystemet Gripper TGG 32002011Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Schur AB är ett företag i Eksjö som erbjuder sina kunder lösningar inom post- och tidningshantering. Bland dessa lösningar ingår ett transportsystem kallat Gripper TGG 3200 vilket transporterar tidningar från exempelvis pressen till olika enheter i packsalen. Transportsystemet drivs av ett antal asynkronmotorer, antalet motorer variera med avseende på hur lång transportsträckan är. Då drivstationer och motorer är de dyraste komponenterna i transportsystemet vill man minimera antalet av dessa

    Systemet är uppbyggt av aluminiumprofiler som gör att det kan skräddarsys efter kundens behov. I profilerna rullar enheterna som transporterar tidningen i en sammanlänkad kedja. För att kunna placera ut motorer med en given effekt krävs det att ett effektbehov beräknas för varje enskild profil. Detta för att övervinna diverse krafter som uppstår under drift. Med hjälp av detta kan precis så många motorer som krävs för att driva systemet placeras ut.

    I detta examensarbete har effektbehovet beräknats på de vanligaste profilerna i systemet. För att sedan simplifiera beräkningarna har en beräkningsmall utformats, där kan varje enskild profil beräknas. I mallen kan även hela transportsystemets effektbehov och längd överskådas. Med detta verktyg ser användaren snabbt när effektbehovet kommit till en gräns då en motor måste införas.

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    Kraftberäkning på transportsystemet Gripper TGG 3200
  • 344.
    Detterfelt, Jonas
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Henriksson, Fredrik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Production – as seen in product development: A theoretical review of how established product development process models address the production system2018Ingår i: DS 91: Proceedings of NordDesign 2018: DESIGN IN THE ERA OF DIGITALIZATION / [ed] Ekströmer, Philip; Schütte, Simon and Ölvander, Johan, Scotland: The Design Society, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    It is a well-known fact that collaboration between design and production during product development is a critical success factor. Literature on product development have described many different product development processes (PDP), but engineering students are in general only taught one or a few of the existing models. Given this, it is interesting to investigate how established (and often used) PDP models address production and the development of the production system, since this could influence the presumptions of engineers in industry as well as academic researchers (who in general have been engineering students before pursuing an academic career). In this paper, the authors have reviewed seven established and commonly used (in mechanical engineering education and/or research) PDP models, with respect to how the models address the production system and its development. The models are reviewed with respect to what the PDP model describe as the content of the PDP, inclusion of the development of the production system in the model, the presentation of support tools for production related activities, the level of references or mentioning of production system development theories, the visibility of data transfer needs between product and production system development and the strategic role of production in product development. This analysis shows that production system development is mentioned less in more recent literature but is generally scarcely described. Design for manufacturing and design for assembly tools have been added to more recent literature, which might be a way of managing the decreased inclusion of production system development. Finally, an outline for future research efforts on the topic is presented.

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  • 345.
    Devadurgam, Hemanth
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Rajagopal, Soorya
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Munjulury, Raghu Chaitanya
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Modeling and Sizing of Conventional and Electrical Environmental Control Systems2019Rapport (Refereegranskat)
    Abstract [en]

    Environmental control system holds vital importance as it is responsible for passenger’s ventilation and comfort. This paper presents modelling and sizing of the parameterized model of environmental control systems. Knowledge based engineering application serves as the base for designing and methodology for the environmental control systems. Flexibility in the model enables user to control the size and positioning of the system and also sub-systems  associated with it. Number of passengers serves as the driving input for the environmental control system. A 3-d model gives the exact representation with respect to volume occupied and dependencies on the number of passengers. It also provides a faster method to alter the system to user needs with respect to number of air supply pipes, number of ducts and pipe length. Knowledge based engineering gives the freedom to visualize various options in the conceptual design process.

  • 346.
    Diaz Puebla, Alejandro
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Munjulury, Raghu Chaitanya
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Fluida och mekatroniska system. Linköpings universitet, Tekniska fakulteten.
    Sizing of actuators for flight control systems and flaps integration in RAPID2015Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The architecture of the flight control system, essentialfor all flight operations, has significantlychanged throughout the years. The first part ofthe work consists of a preliminary sizing modelof an EHA and an EMA. The second part of thework consists of the development of parametricCAD models of different types of flaps and theirintegration in RAPID. This thesis addresses theactuation system architecture of what it is namedas more electric aircraft with electrically poweredactuators. This consists of the development offlexible parametric models of flight control surfaces,being able to adapt to any wing geometryand their automatic integration in RAPID. Furthermore,it represents a first step in the developmentof an automatic tool that allows the user tochoose any possible wing control surface configuration.

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  • 347.
    Diffner, Björn
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Monteringsteknik.
    Edlund, Erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Monteringsteknik.
    Utvärdering av 3dvia Composer: -För arbetsinstruktioner och beredning2009Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats
    Abstract [sv]

    I takt med den tekniska utvecklingen har datorstödd konstruktion och produktion blivit en alltviktigare del i produktlivscykeln. Nya affärsområden såsom funktionsförsäljning ochåtertillverkning där tillverkande företag har tagit på sig ett allt större ansvar för helaproduktlivscykeln har växt fram på senare tid. Detta ställer allt högre krav på att ha kontrollöver produktdata under hela produktlivscykeln. Datorstödd konstruktion är sedan länge utbrettoch etablerat inom industrin och på senare år har även digital manufacturing , med i vilketPapperslös produktion är en del fått en allt större betydelse. Papperslös produktion innebär attalla order och arbetsinstruktioner visas t.ex. på en skärm istället för i pappersform. För atthjälpa företag att bereda bättre arbetsinstruktioner har Dassault Systémes lanserat produkten3Dvia Composer.Företaget DELFOi arbetar med digital manufacturing på den nordiska marknaden och äråterförsäljare av Dassault Systémes produkter. DELFOi önskar veta om 3Dvia Composer ären produkt som tillför produktportföljen något och vilka vinster den kan ge deras kunder. Detär även viktigt att företaget har en modell som kan användas för att marknadsföra ochimplementera Composer framgångsrikt hos kund.För att utreda detta intervjuades fem företag som bereder instruktioner för olika delar avproduktlivscykeln. Deras arbetssätt kring arbetsinstruktioner kartlades, samt behov och bristeri arbetssätt identifierades. Teorier för människa/maskin-gränssnitt och elektroniskaarbetsinstruktioner studerades. Utifrån dessa teorier och resultatet från intervjuernautvärderades sedan 3Dvia Composers kompetens för framtagning av arbetsinstruktioner.Programvaran jämfördes också med konkurrerande program i en benchmarking. Slutligenarbetades metodik och dokument fram för hur DELFOi kan implementera 3Dvia Composerhos kund.Detta arbete visar att interaktiva arbetsinstruktioner har många fördelar och kan lösa många avde problem som företag idag identifierar relaterat till beredning av arbetsinstruktioner och3Dvia Composer är en kompetent programvara för att uppnå detta. Det kommer dock attkrävas stora arbetsresurser för att sälja 3Dvia Composer, eftersom de flesta företag, trots enrad uttalade problem, är nöjda med dagens arbetsmetodik och därför har svårt att söka nyalösningar på problemen.

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    FULLTEXT01
  • 348.
    Ding, Huiping
    et al.
    Beijing Jiaotong University, Peoples R China.
    Zhao, Qilan
    Beijing Jiaotong University, Peoples R China.
    An, Zhirong
    Beijing Jiaotong University, Peoples R China.
    Tang, Ou
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Produktionsekonomi. Linköpings universitet, Tekniska fakulteten.
    Collaborative mechanism of a sustainable supply chain with environmental constraints and carbon caps2016Ingår i: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 181, s. 191-207Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Negative impacts on environment such as carbon emissions and pollution resulting from the business activities of firms in a supply chain have attracted great attention worldwide. Hence, one of the crucial issues for supply chain management is the trade-off between economic objectives and environmental sustainability. This paper focuses on investigating the government policy incentive mechanism, with which supply chain members are motivated to work collaboratively to reduce carbon and pollutant emissions by investing in producing environmental-friendly products (EFP). Such a mechanism affects the transfer price through negotiation between the supply chain firms, and consequently it has an impact on the supply chains value transition and profit allocation. A collaborative supply chain decision-making framework is formulated with environmental constraints and carbon caps; its objective is to maximize the net present value of an integrated supply chain as well as satisfy the interests of its individual members. Our key contribution lies in exploring a decision-making mechanism for an environmentally sustainable supply chain that is jointly constrained by environmental carrying capacities and carbon caps, and also takes into account government policy incentives. The results show that collaboration between supply chain members plays a crucial role in improving their environmental performance, as the transfer price is determined through negotiations to share government subsidies to satisfy the individual interests of supply chain members while the level of pollutants and carbon emissions are in compliance with environmental standards.(C) 2016 Elsevier B.V. All rights reserved.

  • 349.
    Dipasquale, Chiara
    et al.
    EURAC.
    Fedrizzi, Roberto
    EURAC.
    Bellini, Alessandro
    EURAC.
    Gustafsson, Marcus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska fakulteten.
    Ochs, Fabian
    University of Innsbruck.
    Bales, Chris
    Högskolan Dalarna.
    Database of energy, environmental and economic indicators of renovation packages for European residential buildings2019Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 203, artikel-id 109427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing the energy efficiency with a vast impact in the residential building stock requires retrofit so- lutions that can be exploited with respect to a wide range of different building typologies and climates. Several tools and methodologies are nowadays available both for the assessment of building demands and for the individuation of optimum retrofit solutions. However, they are usually either too complex to be adopted by professionals or, on the contrary, oversimplified to account for the full complexity of a deep envelope and HVAC system retrofit. In this context, this paper describes a methodology developed to generate reliable information on retrofit solutions for typical buildings in different climatic conditions. Detailed numerical models are used to simulate a number of combinations of envelope and HVAC systems retrofit measures and renewable energy integration. Energy performance results are gathered in a database that allows comparing solu- tions, spanning over a range of more than 250,0 0 0 combinations of building types, age of construction, climates, envelope performance levels and HVAC systems configurations. Economic feasibility is also de- rived for each of the combinations. In this way, the accurateness of a detailed and validated calculation is made available to assist during the decision making process, with minimum computational effort being required by professionals: the variety and density of evaluated combinations allows to easily assess the performance of a specific case by interpolating among instances previously assessed. The applicability of the results to different climates and similar building typologies is verified by a comparison of the database results with a specific case dynamic simulation.

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  • 350.
    Djordjevic, Miroljub
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem.
    Häggqvist, Johan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem.
    Simuleringsbaserad material och produktionsstyrning2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Gruppen Kvantitativ Logistik (KL) vid Linköpings Universitet har under en längre tid efterfrågat en simuleringsbaserad utbildningsmiljö där produktionsplanering kan upplevas i form av planering, omplanering och kapacitetsberäkningar. 

    Denna utbildningsmiljö ska framförallt användas för att utbilda andra studenter inom produktionsplanering. Miljön ska bestå av ett användarinterface där all data om produktionen framgår, en simuleringsmodell som utgör själva fabriken samt en sammanhållande struktur som möjliggör styrning av de båda komponenterna. Dessutom skall ett antal scenarion skapas som skall ligga till grund för de lärandemoment som MPCW hanterar.

    Fyra fiktiva produktstruktur skapades, på så sätt att deras komplexitet och djup var tillfredsställande. Dessa strukturer ligger till grund för de MRP- och sedermera CRP-beräkningar som används för att styra de ursprungliga aktiviteterna.

    Resultatet av examensarbetet är ett verktyg som kan användas för att simulera produktionsplaneringsarbete. Verktyget består av två huvuddelar, den ena är ett GUI (Graphical User Interface) i Excel som kallas för MPCW (Material Planning and Control Workbench) och en simuleringsmodell. Dessa delar jobbar tillsammans via Excel och VBA. Allt kontrolleras genom MPCW:s GUI och det är i MPCW som användaren sitter och styr produktionsplaneringen genom att analysera och bearbeta tillgänglig information. Användaren har möjlighet att erhålla information i MPCW i form av MRP tablåer som bygger på en huvudplan, information om produktionskapacitet och beläggning på maskinerna i fabriken.

    Vad gäller vidare arbete med modellen, så kommer det alltid finnas utrymme för förbättring, framförallt vad gäller fabriken. Detta då en simulerad fabrik naturligtvis aldrig kan avbilda en riktig fabrik helt och hållet, särskilt då den modellerade fabriken inte bygger på en verklig fabrik.

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