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  • 1.
    Aakumiah, Prince Osei
    Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    Water Management and Health in Ghana: Caes Study - Kumasi2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There have been multiple cases of drinking water related diseases in Ghana, particularly the cities. Kumasi, the second largest city is recording high figures of drinking water related diseases. The Ghana water and sewage company is supposed to provide adequate safe drinking water to the people. However, the company has failed to provide this service effectively. Various reasons have been given by the company on its inability to perform efficiently. Meanwhile the government decided lately to privatise water in the cities to facilitate access to quality water through what is called “FULL COST RECOVERY”. This attracted a lot of international companies to Ghana but this has also generated protest and demonstrations. The argument is that these foreign companies are basically profit oriented and considering the fact that most of the affected people are very poor, suggesting they cannot afford it.

    The study is aimed at finding out the relationship between water management and health in the study area and how effective water management through full community participation could help provide adequate safe drinking water. The study was a non-interventional descriptive type using both qualitative and quantitative methods. It was conducted in Kumasi, the second largest city in Ghana. A total of 100 residents from the communities was selected through systematic sampling and interviewed. This includes 86 local residents and 14 key informer interviews. The study also relied on observation as well as some selected literature.

    The results confirmed that drinking water related diseases is on the increase with the most affected people being the poor living in shanty and informal areas of the city. It was also found that most people in the city are willing to render any services to provide safe drinking water. But in relative terms, most of these people are very poor with high percentage of illiterates and may only contribute if there is a good relation and trust among all. It however appears that community participation is a good option for the city provided that stakeholders are made to play effective roles.

  • 2.
    Aalberg, Laura
    et al.
    National Bureau of Investigation, P.O. Box 285, FIN-01301 Vantaa, Finland.
    Andersson, Kjell
    Swedish National Laboratory of Forensic Science, SKL, SE-581 94 Linköping, Sweden.
    Bertler, Christina
    Swedish National Laboratory of Forensic Science, SKL, SE-581 94 Linköping, Sweden.
    Borén, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Analytical Chemistry .
    Cole, Michael D.
    Forensic Science Unit, University of Strathclyde, 204 George Street, Glasgow, UK.
    Dahlén, Johan
    Swedish National Laboratory of Forensic Science, SKL, SE-581 94 Linköping, Sweden.
    Finnon, Yvonne
    Forensic Science Unit, University of Strathclyde, 204 George Street, Glasgow, UK.
    Huizer, Henk
    Netherlands Forensic Institute, Volmerlaan 17, 2288 GD Rijswijk, The Netherlands.
    Jalava, Kajsa
    National Bureau of Investigation, P.O. Box 285, FIN-01301 Vantaa, Finland.
    Kaa, Elisabet
    Department of Forensic Medicine, University of Aarhus, Skovagervej 2, DK-8240 Risskov, Denmark.
    Lock, Eric
    Netherlands Forensic Institute, Volmerlaan 17, 2288 GD Rijswijk, The Netherlands/Institut de Police Scientifique, University of Lausanne, Batiment de Chimie, CH-1015 Lausanne-Dorigny, Switzerland.
    Lopes, Alvaro
    Laboratorio de Policia Cientifica, Policia Judiciaria, Rua Gomes Freire 174, 1169-007 Lisbon, Portugal.
    Poortman-van-der Meer, Anneke
    Department of Forensic Medicine, University of Aarhus, Skovagervej 2, DK-8240 Risskov, Denmark.
    Sippola, Erkki
    National Bureau of Investigation, P.O. Box 285, FIN-01301 Vantaa, Finland.
    Development of a harmonised method for the profiling of amphetamines: I. Synthesis of standards and compilation of analytical data2005In: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 149, no 2-3, 219-229 p.Article in journal (Refereed)
    Abstract [en]

    Reference material was synthesised for 21 substances that are frequently present as synthetic impurities, i.e. by-products, in illicitly produced amphetamine. Each of these substances is a typical by-product for at least one of the three approaches most often used to synthesise amphetamine, namely, the Leuckart, the reductive amination of benzyl methyl ketone, and the nitrostyrene routes. A large body of data on the substances was recorded, including the following: mass spectra, ultraviolet spectra, Fourier transform infrared spectra, infrared spectra in gas phase, and 1H NMR and 13C NMR spectra. © 2004 Elsevier Ireland Ltd. All rights reserved.

  • 3. Aavikko, R.
    et al.
    Saarinen, K.
    Magnusson, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Clustering of Vacancies in Semi-Insulating SiC Observed with Positron Spectroscopy2006In: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, 575-578 p.Conference paper (Refereed)
  • 4. Aavikko, R.
    et al.
    Saarinen, K.
    Tuomisto, F.
    Magnusson, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nguyen, Son Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Clustering of vacancy defects in high-purity semi-insulating SiC2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 8, 085208- p.Article in journal (Refereed)
    Abstract [en]

    Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity in both as-grown and annealed materials. Our results suggest that Si-vacancy-related complexes electrically compensate the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity. © 2007 The American Physical Society.

  • 5.
    Abadias, Gregory
    et al.
    University of Poitiers, France.
    Sarakinos, Kostas
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Fenker, Martin
    FEM, Germany.
    Kassavetis, Spiros
    Aristotle University of Thessaloniki, Greece.
    Editorial Material: Preface in SURFACE and COATINGS TECHNOLOGY, vol 255, issue , pp2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 255Article in journal (Other academic)
    Abstract [en]

    n/a

  • 6.
    Abadir Guirgis, Georg
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Mindre energi och rätt tid: Utvärdering av utbildning och träning för lokförare i energieffektiv körning – en simulatorstudie2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the 80’s, the first train simulator was introduced in Swedish train driver education and is still the only full scale simulator being used to educate train drivers in Sweden. The reason for this seems to be a lack of educational and economic motives for an expanded usage of simulators within education and training. Energy savings within the railway domain, i.e. energy-efficient driving, is currently a topic for all train operators in Sweden. Some operators already educate their drivers in energy efficient driving and tests of energy efficiency in real traffic has shown a potential energy saving of 16 %, after drivers have completed a theoretical education in energy-efficient driving. Because there were some uncertainties in the data from the tests carried out in real traffic, where conditions and experimental procedures varied between the drivers and it also turned out that education and access to a support system while driving resulted in a small saving in energy (13 %) there was a need to examine the potential savings under controlled conditions. Therefore, a study was conducted using a train simulator. In the simulator, the researcher has full control over the data and conditions are the same for all drivers. The simulator used in the study was developed by VTI (Swedish National Road and Transport Research Institute) and modeled after an X50 Regina. The purpose of this study was to investigate whether the same theoretical education in energy-efficient driving, in combination with simulator training under ideal conditions, could contribute to the same, or better energy saving compared to the results of the tests from real traffic. Furthermore, the effect of feedback during training with regard to energy savings was also investigated. 24 train driver students were divided into three groups with 8 students in each. Two of these groups completed two sessions (reference and test session) with theoretical education and simulator training between the sessions. The last group (control group) completed two sessions (reference and test session) without education and training between the sessions. The two groups that were given theoretical education conducted their simulator training under two different conditions, where one group trained with feedback (energy consumption and rail gradient) and the other group trained without feedback. It turns out that a theoretical education in energy efficient driving, combined with 30 minutes of simulator training, resulted in a total saving of about 24 % energy for both groups. Also, considering that the control group improved their energy consumption by simply driving the simulator two times (8 % total energy saving), the energy saving was almost equal to the result of the tests in real traffic. Since the results were equal even though the conditions differed, there is reason to investigate how different driving conditions affect the outcome. There is also a need to better understand why education in combination with a support system resulted in a lower energy saving than for those who were only given education during the tests in real traffic, and also why feedback during training in the simulator did not give a detectable effect. Basically, there are many reasons to further investigate how to design simulator training and support systems for train drivers. In addition to the energy savings, the results showed that drivers improved their arrival times i.e. arrive more accurate in relation to the time table. The results suggest that there is great potential for train simulators in the Swedish train driver education, both for training and for evaluating the effects of the training.

  • 7.
    Abadir Guirgis, Georg
    Linköping University, Department of Computer and Information Science.
    Lärarperspektiv på riskutbildningen för motorcyklister2011Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [sv]

    Under det senaste decenniet har det i Sverige blivit allt populärare att åka motorcykel. Enobligatorisk riskutbildning för behörighet A och A1 infördes från och med den 1 november2009. Då riskutbildningen är ny har få utvärderingar gjorts.Denna studie utvärderar riskutbildningen för motorcyklister utifrån trafikskolläraresperspektiv. Målet har varit att sammanställa synpunkter och erfarenheter från lärarna påutbildningen. Ett ytterligare mål har varit att undersöka trafikskollärarnas upplevda effekter avutbildningen på elevers trafikbeteende. Sex semistrukturerade intervjuer med trafikskolläraresamt en observationsstudie på olika trafikskolor genomfördes. Utöver detta genomfördesdeltagande observation av en fortbildning där 15 trafikskollärare deltog. Resultatet frånstudien visar att lärarna anser att behovet av riskutbildningen är stort och attimplementationen av den nya riskutbildningen gått bra. Förutom att elever efter utbildningenrefererar till den, vilket enligt lärarna indikerar att de tagit till sig vad som sagts, märks det nui större utsträckning än tidigare att elever kör lugnare och tänker sig mer för i vissasituationer. Detta påtalades vara ett klart önskvärt resultat.

  • 8.
    Abbas, Muhammad Hassan
    et al.
    Linköping University, Department of Computer and Information Science.
    Khan, Mati-ur-Rehman
    Linköping University, Department of Computer and Information Science.
    Correlational Analysis of Drivers Personality Traits and Styles in a Distributed Simulated Driving Environment2007Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis report we conducted research study on driver's behavior in T-Intersections using simulated environment. This report describes and discusses correlation analysis of driver's personality traits and style while driving at T-Intersections.

    The experiments were performed on multi user driving simulator under controlled settings, at Linköping University. A total of forty-eight people participated in the study and were divided into groups of four, all driving in the same simulated world.

    During the experiments participants were asked to fill a series of well-known self-report questionnaires. We evaluated questionnaires to get the insight in driver's personality traits and driving style. The self-report questionnaires consist of Schwartz's configural model of 10 values types and NEO-five factor inventory. Also driver's behavior was studied with the help of questionnaires based on driver's behavior, style, conflict avoidance, time horizon and tolerance of uncertainty. Then these 10 Schwartz's values are correlated with the other questionnaires to give the detail insight of the driving habits and personality traits of the drivers.

  • 9.
    Abbas, Qaisar
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Weak Boundary and Interface Procedures for Wave and Flow Problems2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems.

    The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case.

    The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach.

    Using the SBP technique and WBCs, we have worked out how to construct conservative and energy stable hybrid schemes for shocks using two different approaches. In the first method, we combine a high order finite difference scheme with a second order MUSCL scheme. In the second method, a procedure to locally change the order of accuracy of the finite difference schemes is developed. The main purpose is to obtain a higher order accurate scheme in smooth regions and a low order non-oscillatory scheme in the vicinity of shocks.

    Furthermore, we have analyzed the energy stability of the MUSCL scheme, by reformulating the scheme in the framework of SBP and artificial dissipation operators. It was found that many of the standard slope limiters in the MUSCL scheme do not lead to a negative semi-definite dissipation matrix, as required to get pointwise stability.

    Finally, high order simulations of shock diffracting over a convex wall with two facets were performed. The numerical study is done for a range of Reynolds numbers. By monitoring the velocities at the solid wall, it was shown that the computations were resolved in the boundary layer. Schlieren images from the computational results were obtained which displayed new interesting flow features.

  • 10.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Weak versus strong no-slip boundary conditions for the Navier-Stokes equations2010In: Engineering Applications of Computational Fluid Mechanics, ISSN 1994-2060, Vol. 4, 29-38 p.Article in journal (Refereed)
  • 11.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Weak versus Strong No-Slip Boundary Conditions for the Navier-Stokes Equations2008In: Proc. 6th South African Conference on Computational and Applied Mechanics, South African Association for Theoretical and Applied Mechanics , 2008, 52-62 p.Conference paper (Other academic)
  • 12.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    van der Weide, Edwin
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Accurate and stable calculations involving shocks using a new hybrid scheme2009In: Proc. 19th AIAA CFD Conference, AIAA , 2009Conference paper (Refereed)
  • 13.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    van der Weide, Edwin
    Faculty of Engineering Technology, University of Twente, AE Enschede, The Netherlands.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Energy Stability of the MUSCL Scheme2010In: Proc. 7th South African Conference on Computational and Applied Mechanics, South African Association for Theoretical and Applied Mechanics , 2010, 65:1-8 p.Conference paper (Other academic)
  • 14.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    van der Weide, Edwin
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Energy stability of the MUSCL scheme2010In: Numerical Mathematics and Advanced Applications: 2009, Berlin: Springer-Verlag , 2010, 61-68 p.Conference paper (Refereed)
  • 15.
    Abbasi, Mazhar Ali
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The synthesis, characterization and device fabrication of ZnO, NiO and their composite nanostructures2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electronics industry has been revolutionized since last few decades because of the fabrication of electronic devices by using nanoscale based materials. But the more innovative feature in the electronic devices is the use of transparent materials, which makes the transparent electronic devices as one of the most interesting research field in nanoscience and nano-technology now a days. In order to have high performance electronic devices based on the wide band gap compound semiconductors, a selection of right transparent material is crucial step. Among all the transparent metal oxides, ZnO is one of the potential candidates due to the ease in the synthesis process, wide bandgap of 3.37 eV, a high exciton binding energy of 60 meV and diverse morphologies. Since p-type ZnO based nanodevices are still difficult to fabricate due to the instability and unreliability of p-type ZnO nanomaterial, therefore several p-type semiconductors are used for the development of p-n junctions. Among those NiO is suitable p-type compound semiconductor to make p-n junction with ZnO because of its wide band gap of 3.7 eV and environment friendly conditions for its synthesis. Keeping these attractive properties of n-type ZnO and p-type NiO, the synthesis of composite nanostructures of these two transparent oxides and fabrication of their electronic devices is presented in this dissertation work.

    I started my work with the synthesis of ZnO nanostructures focusing on the effect of different anions of zinc salts on the morphology and crystallinity of ZnO nanostructures. Then I grow honey-comb like NiO nanostructures on 3D nickel foam and used these nanostructures for the detection of Zinc ion. After that synthesized NiO and ZnO based composite nanostructures and characterized them, having main focus on the luminescence properties of ZnO when decorated with NiO nanostructures. The composite nanostructures of p-type NiO and n-type ZnO showed enhancement in the luminescence properties. Since pn junction is the back bone of electronic devices so working on the designing of band alignment along with the current transport properties of p-type NiO/n-type ZnO composite structures, an attempt was put forwarded to explain the phenomenon of these compound semiconducting materials. Different devices based on these two compound semiconducting materials are fabricated and designed in the present dissertation work, however still more work is required to improve the efficiency of devices like LEDs and UV detectors.

    List of papers
    1. Anions effect on the low temperature growth of ZnO nanostructures
    Open this publication in new window or tab >>Anions effect on the low temperature growth of ZnO nanostructures
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    2012 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 12, 1998-2001 p.Article in journal (Refereed) Published
    Abstract [en]

    Seed mediated aqueous chemical growth (ACG) route was used for the growth of ZnO nanostructures on Si substrate in four different growth mediums. The growth medium has shown to affect the morphology and the size of the different nanostructures. We observed that the medium containing zinc nitrate anions yields the nanorods, in a medium containing zinc acetate anions nano-candles are obtained. While in a medium containing zinc chloride anions ZnO nano-discs were obtained and in a medium containing zinc sulfate anions nano-flakes are achieved. Growth in these different mediums has also shown effect on the optical emission characteristics of the different ZnO nanostructures.

    Place, publisher, year, edition, pages
    Elsevier, 2012
    Keyword
    ZnO, Chemical growth, Nanostructures, Optical properties
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-84909 (URN)10.1016/j.vacuum.2012.05.020 (DOI)000308672000041 ()
    Available from: 2012-10-26 Created: 2012-10-26 Last updated: 2014-01-17
    2. Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures
    Open this publication in new window or tab >>Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures
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    2012 (English)In: Sensors, ISSN 1424-8220, Vol. 12, no 11, 15424-15437 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples.

    Place, publisher, year, edition, pages
    MDPI, 2012
    Keyword
    honeycomb NiO nanostructures, potentiometric response, ion selective electrode, selectivity, selective ionophore
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-86653 (URN)10.3390/s121115424 (DOI)000311429500060 ()
    Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2014-01-17
    3. Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study
    Open this publication in new window or tab >>Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study
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    2014 (English)In: Materials, ISSN 1996-1944, Vol. 7, no 1, 430-440 p.Article in journal (Refereed) Published
    Abstract [en]

    Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy,  high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.

    Place, publisher, year, edition, pages
    MDPI, 2014
    Keyword
    ZnO nanorods; NiO nanostructure; composite nanostructures; defect states; cathodoluminescent
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-103339 (URN)10.3390/ma7010430 (DOI)000336088500030 ()
    Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2016-08-31Bibliographically approved
    4. The determination of valence band offset and the current transport properties of the p-NiO/n-ZnO heterojunction
    Open this publication in new window or tab >>The determination of valence band offset and the current transport properties of the p-NiO/n-ZnO heterojunction
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    2013 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The electron transport in the electronic devices has significant influence on the device performance, thus current transport properties determination is highly demanded for a particular device. Herein, we report the facile hydrothermal growth method based fabrication of p-NiO/n-ZnO heterojunction. The material characterization was performed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy. These techniques provided the good crystal quality, pure phase of p-NiO and n-ZnO nanostructures respectively. The measured valance band offset of composite nanostructure is 2.25 eV and conduction band offset was found to be 2.58 eV. The current transport properties of the fabricated p-n junction are governed by three different I-V regions. The impedance spectroscopy was used for the determination of the role of grain boundaries at the interface.

    Keyword
    Zinc oxide, nickel oxide, heterojunction, diode, current transport properties
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-103340 (URN)
    Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2014-03-27Bibliographically approved
    5. Fabrication of UV photo-detector based on coral reef like p-NiO/n-ZnO nanocomposite structures
    Open this publication in new window or tab >>Fabrication of UV photo-detector based on coral reef like p-NiO/n-ZnO nanocomposite structures
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    2013 (English)In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 108, 149-152 p.Article in journal (Refereed) Published
    Abstract [en]

    In this research work, a UV photo-detector is fabricated on fluorine doped tin oxide (FTO) glass substrate by exploiting the advantageous features of p-n heterojunctions based on p-NiO and n-ZnO composite nanostructures forming a coral-reef like structures. Scanning electron microscopy (SEM) and X-ray diffraction results showed uniform morphology and good crystal quality of the synthesised nanostructures respectively. I-V measurements have shown nonlinear and rectifying response of the p-NiO/n-ZnO heterojunction. The proposed photodiode exhibited excellent UV response with acceptable photocurrent generation of about 3.4 mA and the responsivity of 2.27 A/W at -3 biasing voltage.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keyword
    p-NiO/n-ZnO composite nanostructures, Photodiode, UV-visible spectrophotometry
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-99403 (URN)10.1016/j.matlet.2013.06.083 (DOI)000324562900038 ()
    Available from: 2013-10-17 Created: 2013-10-17 Last updated: 2014-04-04
    6. The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence
    Open this publication in new window or tab >>The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence
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    2013 (English)In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 8, no 320Article in journal (Refereed) Published
    Abstract [en]

    Cheap and efficient white light-emitting diodes (LEDs) are of great interest due to the energy crisis all over the world. Herein, we have developed heterojunction LEDs based on the well-aligned ZnO nanorods and nanotubes on the p-type GaN with the insertion of the NiO buffer layer that showed enhancement in the light emission. Scanning electron microscopy have well demonstrated the arrays of the ZnO nanorods and the proper etching into the nanotubes. X-ray diffraction study describes the wurtzite crystal structure array of ZnO nanorods with the involvement of GaN at the (002) peak. The cathodoluminescence spectra represent strong and broad visible emission peaks compared to the UV emission and a weak peak at 425 nm which is originated from GaN. Electroluminescence study has shown highly improved luminescence response for the LEDs fabricated with NiO buffer layer compared to that without NiO layer. Introducing a sandwich-thin layer of NiO between the n-type ZnO and the p-type GaN will possibly block the injection of electrons from the ZnO to the GaN. Moreover, the presence of NiO buffer layer might create the confinement effect.

    Keyword
    White light-emitting diode; ZnO nanorods; Nanotubes; NiO buffer layer
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-103341 (URN)10.1186/1556-276X-8-320 (DOI)000331642900001 ()
    Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2014-03-18Bibliographically approved
  • 16.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, Mushtaque
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence2013In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 8, no 320Article in journal (Refereed)
    Abstract [en]

    Cheap and efficient white light-emitting diodes (LEDs) are of great interest due to the energy crisis all over the world. Herein, we have developed heterojunction LEDs based on the well-aligned ZnO nanorods and nanotubes on the p-type GaN with the insertion of the NiO buffer layer that showed enhancement in the light emission. Scanning electron microscopy have well demonstrated the arrays of the ZnO nanorods and the proper etching into the nanotubes. X-ray diffraction study describes the wurtzite crystal structure array of ZnO nanorods with the involvement of GaN at the (002) peak. The cathodoluminescence spectra represent strong and broad visible emission peaks compared to the UV emission and a weak peak at 425 nm which is originated from GaN. Electroluminescence study has shown highly improved luminescence response for the LEDs fabricated with NiO buffer layer compared to that without NiO layer. Introducing a sandwich-thin layer of NiO between the n-type ZnO and the p-type GaN will possibly block the injection of electrons from the ZnO to the GaN. Moreover, the presence of NiO buffer layer might create the confinement effect.

  • 17.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, Mushtaque
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study2014In: Materials, ISSN 1996-1944, Vol. 7, no 1, 430-440 p.Article in journal (Refereed)
    Abstract [en]

    Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy,  high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.

  • 18.
    Abdalla, Hassan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Investigation of the dimensionality of charge transport in organic field effect transistors2017In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, no 8, 85301Article in journal (Refereed)
    Abstract [en]

    Ever since the first experimental investigations of organic field effect transistors (OFETs) the dimensionality of charge transport has alternately been described as two dimensional (2D) and three dimensional (3D). More recently, researchers have turned to an analytical analysis of the temperature-dependent transfer characteristics to classify the dimensionality as either 2D or 3D as well as to determine the disorder of the system, thereby greatly simplifying dimensionality investigations. We applied said analytical analysis to the experimental results of our OFETs comprising molecularly well-defined polymeric layers as the active material as well as to results obtained from kinetic Monte Carlo simulations and found that it was not able to correctly distinguish between 2D and 3D transports or give meaningful values for the disorder and should only be used for quasiquantitative and comparative analysis. We conclude to show that the dimensionality of charge transport in OFETs is a function of the interplay between transistor physics and morphology of the organic material.

  • 19.
    Abdalla, Hassan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    van de Ruit, Kevin
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering. Eindhoven University of Technology, Netherlands.
    Effective Temperature and Universal Conductivity Scaling in Organic Semiconductors2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, 16870Article in journal (Refereed)
    Abstract [en]

    We investigate the scalability of the temperature-and electric field-dependence of the conductivity of disordered organic semiconductors to universal curves by two different but commonly employed methods; by so-called universal scaling and by using the effective temperature concept. Experimentally both scaling methods were found to be equally applicable to the out-of-plane charge transport in PEDOT: PSS thin films of various compositions. Both methods are shown to be equivalent in terms of functional dependence and to have identical limiting behavior. The experimentally observed scaling behavior can be reproduced by a numerical nearest-neighbor hopping model, accounting for the Coulomb interaction, the high charge carrier concentration and the energetic disorder. The underlying physics can be captured in a simple empirical model, describing the effective temperature of the charge carrier distribution as the outcome of a heat balance between Joule heating and (effective) temperature-dependent energy loss to the lattice.

  • 20.
    Abdollahi Sani, Negar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Robertsson, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Cooper, Philip
    De La Rue Plc, Overton, Hampshire, UK .
    Wang, Xin
    Acreo AB, Norrköping, Sweden.
    Svensson, Magnus
    Acreo AB, Norrköping, Sweden.
    Andersson Ersman, Peter
    Acreo AB, Norrköping, Sweden.
    Norberg, Petronella
    Acreo AB, Norrköping, Sweden.
    Nilsson, Marie
    Acreo AB, Norrköping, Sweden.
    Nilsson, David
    Acreo AB, Norrköping, Sweden.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Hesselbom, Hjalmar
    Hesselbom Innovation and Development HB, Huddinge, Sweden .
    Akesso, Laurent
    De La Rue Plc, Overton, Hampshire, UK .
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Engquist, Isak
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Acreo AB, Norrköping, Sweden.
    Gustafsson, Goran
    Acreo AB, Norrköping, Sweden.
    All-printed diode operating at 1.6 GHz2014In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, no 33, 11943-11948 p.Article in journal (Refereed)
    Abstract [en]

    Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.

  • 21.
    Abdolmajid Ahmad, Bookan
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Programmering av generativ konst i C# .Net2014Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes på IDA (Institutionen för datavetenskap) vid Linköpings universitet. 

    Syftet med det här examensarbetet var att utveckla ett program som skulle skapa förutsättningar för generativ konst med hjälp av MyPaint som är ett digitalt rit/målarverktyg. Metoden gick ut på att registrera vad användaren skapat för komponenter, dvs. musinteraktioner och kortkommandon, och därefter använda dem algoritmiskt.

    Examensarbetet resulterades i ett program (SharpArt), som fångar musinteraktioner samt simulerar tangentbordstryckningar (kortkommandon) från och till Mypaint, vilket i sin tur skapar komponenter som används algoritmiskt. Programmet kan även positionera objektet på canvasen enligt det önskade koordinatvärdet.

  • 22.
    Abdulahad, Bassam
    et al.
    Linköping University, Department of Computer and Information Science.
    Lounis, Georgios
    Linköping University, Department of Computer and Information Science.
    A user interface for the ontology merging tool SAMBO2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Ontologies have become an important tool for representing data in a structured manner. Merging ontologies allows for the creation of ontologies that later can be composed into larger ontologies as well as for recognizing patterns and similarities between ontologies. Ontologies are being used nowadays in many areas, including bioinformatics. In this thesis, we present a desktop version of SAMBO, a system for merging ontologies that are represented in the languages OWL and DAML+OIL. The system has been developed in the programming language JAVA with JDK (Java Development Kit) 1.4.2. The user can open a file locally or from the network and can merge ontologies using suggestions generated by the SAMBO algorithm. SAMBO provides a user-friendly graphical interface, which guides the user through the merging process.

  • 23.
    Abdulla, Parosh Aziz
    et al.
    Department of Information Technology, Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Department of Information Technology, Uppsala University, Sweden.
    Chen, Yu-Fang
    Institute of Information Science, Academia Sinica, Taiwan.
    Holik, Lukas
    Faculty of Information Technology, Brno University of Technology, Czech Republic.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Rümmer, Philipp
    Department of Information Technology, Uppsala University, Sweden.
    Stenman, Jari
    Department of Information Technology, Uppsala University, Sweden.
    String Constraints for Verification2014In: 26th International Conference on Computer Aided Verification (CAV 2014), Vienna, Austria, Jul. 9-12, 2014., Springer, 2014, 150-166 p.Conference paper (Refereed)
    Abstract [en]

    We present a decision procedure for a logic that combines (i) word equations over string variables denoting words of arbitrary lengths, together with (ii) constraints on the length of words, and on (iii) the regular languages to which words belong. Decidability of this general logic is still open. Our procedure is sound for the general logic, and a decision procedure for a particularly rich fragment that restricts the form in which word equations are written. In contrast to many existing procedures, our method does not make assumptions about the maximum length of words. We have developed a prototypical implementation of our decision procedure, and integrated it into a CEGAR-based model checker for the analysis of programs encoded as Horn clauses. Our tool is able to automatically establish the correctness of several programs that are beyond the reach of existing methods.

  • 24.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Memorax, a Precise and Sound Tool for Automatic Fence Insertion under TSO2013In: Tools and Algorithms for the Construction and Analysis of Systems: 19th International Conference, TACAS 2013, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2013, Rome, Italy, March 16-24, 2013. Proceedings, Springer Berlin/Heidelberg, 2013, 530-536 p.Conference paper (Refereed)
    Abstract [en]

    We introduce MEMORAX, a tool for the verification of control state reachability (i.e., safety properties) of concurrent programs manipulating finite range and integer variables and running on top of weak memory models. The verification task is non-trivial as it involves exploring state spaces of arbitrary or even infinite sizes. Even for programs that only manipulate finite range variables, the sizes of the store buffers could grow unboundedly, and hence the state spaces that need to be explored could be of infinite size. In addition, MEMORAX in- corporates an interpolation based CEGAR loop to make possible the verification of control state reachability for concurrent programs involving integer variables. The reachability procedure is used to automatically compute possible memory fence placements that guarantee the unreachability of bad control states under TSO. In fact, for programs only involving finite range variables and running on TSO, the fence insertion functionality is complete, i.e., it will find all minimal sets of memory fence placements (minimal in the sense that removing any fence would result in the reachability of the bad control states). This makes MEMORAX the first freely available, open source, push-button verification and fence insertion tool for programs running under TSO with integer variables.

  • 25.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Automatic fence insertion in integer programs via predicate abstraction2012In: Static Analysis: 19th International Symposium, SAS 2012, Deauville, France, September 11-13, 2012. Proceedings / [ed] Antoine Miné, David Schmidt, Springer Berlin/Heidelberg, 2012, 164-180 p.Conference paper (Refereed)
    Abstract [en]

    We propose an automatic fence insertion and verification framework for concurrent programs running under relaxed memory. Unlike previous approaches to this problem, which allow only variables of finite domain, we target programs with (unbounded) integer variables. The problem is difficult because it has two different sources of infiniteness: unbounded store buffers and unbounded integer variables. Our framework consists of three main components: (1) a finite abstraction technique for the store buffers, (2) a finite abstraction technique for the integer variables, and (3) a counterexample guided abstraction refinement loop of the model obtained from the combination of the two abstraction techniques. We have implemented a prototype based on the framework and run it successfully on all standard benchmarks together with several challenging examples that are beyond the applicability of existing methods.

  • 26.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Counter-Example Guided Fence Insertion under TSO2012In: TACAS 2012, 2012Conference paper (Refereed)
    Abstract [en]

    We give a sound and complete fence insertion procedure for concurrentfinite-state programs running under the classical TSO memory model. Thismodel allows “write to read” relaxation corresponding to the addition of an unboundedstore buffer between each processor and the main memory. We introducea novel machine model, called the Single-Buffer (SB) semantics, and show thatthe reachability problem for a program under TSO can be reduced to the reachabilityproblem under SB. We present a simple and effective backward reachabilityanalysis algorithm for the latter, and propose a counter-example guided fence insertionprocedure. The procedure is augmented by a placement constraint thatallows the user to choose places inside the program where fences may be inserted.For a given placement constraint, we automatically infer all minimal setsof fences that ensure correctness. We have implemented a prototype and run itsuccessfully on all standard benchmarks together with several challenging examplesthat are beyond the applicability of existing methods.

  • 27.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University.
    Atig, Mohammed Faouzi
    Uppsala University.
    Ganjei, Zeinab
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Zhu, Yunyun
    Uppsala University.
    Verification of Cache Coherence Protocols wrt. Trace Filters2015Conference paper (Refereed)
    Abstract [en]

    We address the problem of parameterized verification of cache coherence protocols for hardware accelerated transactional memories. In this setting, transactional memories leverage on the versioning capabilities of the underlying cache coherence protocol. The length of the transactions, their number, and the number of manipulated variables (i.e., cache lines) are parameters of the verification problem. Caches in such systems are finite-state automata communicating via broadcasts and shared variables. We augment our system with filters that restrict the set of possible executable traces according to existing conflict resolution policies. We show that the verification of coherence for parameterized cache protocols with filters can be reduced to systems with only a finite number of cache lines. For verification, we show how to account for the effect of the adopted filters in a symbolic backward reachability algorithm based on the framework of constrained monotonic abstraction. We have implemented our method and used it to verify transactional memory coherence protocols with respect to different conflict resolution policies.

  • 28.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Dwarkadas, Sandhya
    University of Rochester, U.S.A..
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Shriraman, Arrvindh
    Simon Fraser University, Canada.
    Zhu, Yunyun
    Uppsala University, Sweden.
    Verifying Safety and Liveness for the FlexTM Hybrid Transactional Memory2013In: Design, Automation & Test in Europe (DATE 2013), Grenoble, France, March 18-22, 2013., IEEE , 2013, 785-790 p.Conference paper (Refereed)
    Abstract [en]

    We consider the verification of safety (strict se- rializability and abort consistency) and liveness (obstruction and livelock freedom) for the hybrid transactional memory framework FLEXTM. This framework allows for flexible imple- mentations of transactional memories based on an adaptation of the MESI coherence protocol. FLEXTM allows for both eager and lazy conflict resolution strategies. Like in the case of Software Transactional Memories, the verification problem is not trivial as the number of concurrent transactions, their size, and the number of accessed shared variables cannot be a priori bounded. This complexity is exacerbated by aspects that are specific to hardware and hybrid transactional memories. Our work takes into account intricate behaviours such as cache line based conflict detection, false sharing, invisible reads or non-transactional instructions. We carry out the first automatic verification of a hybrid transactional memory and establish, by adopting a small model approach, challenging properties such as strict serializability, abort consistency, and obstruction freedom for both an eager and a lazy conflict resolution strategies. We also detect an example that refutes livelock freedom. To achieve this, our prototype tool makes use the latest antichain based techniques to handle systems with tens of thousands of states.

  • 29.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University.
    Haziza, Frédéric
    Uppsala University.
    Holik, Lukas
    Brno University of Technology, Czech Republic.
    Jonsson, Bengt
    Uppsala University.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    An Integrated Specification and Verification Technique for Highly Concurrent Data Structures2013In: The 19th International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS 2013), Rome, Italy, March 16-24, 2013., 2013Conference paper (Refereed)
    Abstract [en]

    We present a technique for automatically verifying safety properties of concurrent programs, in particular programs which rely on subtle dependencies of local states of different threads, such as lock-free implementations of stacks and queues in an environment without garbage collection. Our technique addresses the joint challenges of infinite-state specifications, an unbounded number of threads, and an unbounded heap managed by explicit memory allocation. Our technique builds on the automata-theoretic approach to model checking, in which a specification is given by an automaton that observes the execution of a program and accepts executions that violate the intended specification.We extend this approach by allowing specifications to be given by a class of infinite-state automata. We show how such automata can be used to specify queues, stacks, and other data structures, by extending a data-independence argument. For verification, we develop a shape analysis, which tracks correlations between pairs of threads, and a novel abstraction to make the analysis practical. We have implemented our method and used it to verify programs, some of which have not been verified by any other automatic method before.

  • 30.
    Abdullah Jan, Mirza
    et al.
    Linköping University, Department of Electrical Engineering.
    Ahsan, Mahmododfateh
    Linköping University, Department of Electrical Engineering.
    Multi-View Video Transmission over the Internet2010Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    3D television using multiple views rendering is receiving increasing interest. In this technology a number of video sequences are transmitted simultaneously and provides a larger view of the scene or stereoscopic viewing experience. With two views stereoscopic rendition is possible. Nowadays 3D displays are available that are capable of displaying several views simultaneously and the user is able to see different views by moving his head.

    The thesis work aims at implementing a demonstration system with a number of simultaneous views. The system will include two cameras, computers at both the transmitting and receiving end and a multi-view display. Besides setting up the hardware, the main task is to implement software so that the transmission can be done over an IP-network.

    This thesis report includes an overview and experiences of similar published systems, the implementation of real time video, its compression, encoding, and transmission over the internet with the help of socket programming and finally the multi-view display in 3D format.  This report also describes the design considerations more precisely regarding the video coding and network protocols.

  • 31.
    Abidin, Aysajan
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Weaknesses of Authentication in Quantum Cryptography and Strongly Universal Hash Functions2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Authentication is an indispensable part of Quantum Cryptography, which is an unconditionally secure key distribution technique based on the laws of nature. Without proper authentication, Quantum Cryptography is vulnerable to “man-in-the-middle” attacks. Therefore, to guarantee unconditional security of any Quantum Cryptographic protocols, the authentication used must also be unconditionally secure. The standard in Quantum Cryptography is to use theWegman-Carter authentication, which is unconditionally secure and is based on the idea of universal hashing.

    In this thesis, we first investigate properties of a Strongly Universal hash function family to facilitate understanding the properties of (classical) authentication used in Quantum Cryptography. Then, we study vulnerabilities of a recently proposed authentication protocol intended to rule out a "man-in-the-middle" attack on Quantum Cryptography. Here, we point out that the proposed authentication primitive is not secure when used in a generic Quantum Cryptographic protocol. Lastly, we estimate the lifetime of authentication using encrypted tags when the encryption key is partially known. Under simplifying assumptions, we derive that the lifetime is linearly dependent on the length of the authentication key. Experimental results that support the theoretical results are also presented.

    List of papers
    1. Special Properties of Strongly Universal2 Hash Functions Important in Quantum Cryptography
    Open this publication in new window or tab >>Special Properties of Strongly Universal2 Hash Functions Important in Quantum Cryptography
    2009 (English)In: AIP Conference Proceedings, ISSN 0094-243X, Foundations of Probability and Physics—5, Växjö, augusti 2008, New York: American Institute of Physics , 2009, Vol. 1101, 289-293 p.Conference paper, (Refereed)
    Abstract [en]

    Secure message authentication is an important part of Quantum Key Distribution. In this paper we analyze special properties of a Strongly Universal2 hash function family, an understanding of which is important in the security analysis of the authentication used in Quantum Cryptography. We answer the following question: How much of Alices message does Eve need to influence so that the message along with its tag will give her enough information to create the correct tag for her message?

    Place, publisher, year, edition, pages
    New York: American Institute of Physics, 2009
    Keyword
    Quantum cryptography, Quantum theory, Probability
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-18738 (URN)10.1063/1.3109951 (DOI)
    Conference
    Foundations of Probability and Physics—5, Växjö, augusti 2008
    Projects
    ICG QC
    Available from: 2009-06-03 Created: 2009-06-03 Last updated: 2016-08-31
    2. Vulnerability of "A Novel Protocol-Authentication Algorithm Ruling out a Man-in-the-Middle Attack in Quantum Cryptography"
    Open this publication in new window or tab >>Vulnerability of "A Novel Protocol-Authentication Algorithm Ruling out a Man-in-the-Middle Attack in Quantum Cryptography"
    2009 (English)In: International Journal of Quantum Information, ISSN 0219-7499, Vol. 7, no 5, 1047-1052 p.Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography" [M. Peev et al., Int. J. Quant. Inf. 3 (2005) 225]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.

    Keyword
    Quantum cryptography, quantum key distribution, authentication
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20405 (URN)10.1142/S0219749909005754 (DOI)
    Projects
    ICG QC
    Available from: 2009-09-08 Created: 2009-09-07 Last updated: 2016-08-31Bibliographically approved
    3. Lifetime of Authentication Using Encrypted Tags When the Encryption Key is Partially Known
    Open this publication in new window or tab >>Lifetime of Authentication Using Encrypted Tags When the Encryption Key is Partially Known
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Quantum cryptography is an unconditionally secure key growing technique provided that an unconditionally secure authentication protocol is combined with it. This paper is about the study of the lifetime of a message authentication scheme, where a message to be authenticated is first hashed by a secret–but fixed–Strongly Universal hash function then the output is encrypted with a one-time-pad key to generate a tag for the message. If the onetime-pad is completely secret, then the lifetime is exponential in the tag length. If, however, the one-time-pad key is partially known in each authentication round, as is the case in practical quantum key distribution protocols, then the picture is different; because the adversary’s partial knowledge of the one-time-pad key in each authentication round contributes to his/her ability to identify the secret hash function. We estimate the lifetime of this type of authentication. Here the parameters are the length of the key identifying the secret hash function and the amount of knowledge that Eve has on the one-time-pad. A theoretical estimate is presented, along with experimental results that support it.

    Keyword
    Quantum cryptography, quantum key distribution, authentication, strongly universal hash functions, lifetime
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-57289 (URN)
    Projects
    ICG QC
    Available from: 2010-06-16 Created: 2010-06-16 Last updated: 2016-08-31
  • 32.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Larsson, Jan-Åke
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Vulnerability of "A Novel Protocol-Authentication Algorithm Ruling out a Man-in-the-Middle Attack in Quantum Cryptography"2009In: International Journal of Quantum Information, ISSN 0219-7499, Vol. 7, no 5, 1047-1052 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography" [M. Peev et al., Int. J. Quant. Inf. 3 (2005) 225]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.

  • 33.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Larsson, Jan-Åke
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Lifetime of Authentication Using Encrypted Tags When the Encryption Key is Partially KnownManuscript (preprint) (Other academic)
    Abstract [en]

    Quantum cryptography is an unconditionally secure key growing technique provided that an unconditionally secure authentication protocol is combined with it. This paper is about the study of the lifetime of a message authentication scheme, where a message to be authenticated is first hashed by a secret–but fixed–Strongly Universal hash function then the output is encrypted with a one-time-pad key to generate a tag for the message. If the onetime-pad is completely secret, then the lifetime is exponential in the tag length. If, however, the one-time-pad key is partially known in each authentication round, as is the case in practical quantum key distribution protocols, then the picture is different; because the adversary’s partial knowledge of the one-time-pad key in each authentication round contributes to his/her ability to identify the secret hash function. We estimate the lifetime of this type of authentication. Here the parameters are the length of the key identifying the secret hash function and the amount of knowledge that Eve has on the one-time-pad. A theoretical estimate is presented, along with experimental results that support it.

  • 34.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Larsson, Jan-Åke
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Special Properties of Strongly Universal2 Hash Functions Important in Quantum Cryptography2009In: AIP Conference Proceedings, ISSN 0094-243X, Foundations of Probability and Physics—5, Växjö, augusti 2008, New York: American Institute of Physics , 2009, Vol. 1101, 289-293 p.Conference paper (Refereed)
    Abstract [en]

    Secure message authentication is an important part of Quantum Key Distribution. In this paper we analyze special properties of a Strongly Universal2 hash function family, an understanding of which is important in the security analysis of the authentication used in Quantum Cryptography. We answer the following question: How much of Alices message does Eve need to influence so that the message along with its tag will give her enough information to create the correct tag for her message?

  • 35.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Pacher, Christoph
    Austrian Institute of Technology, Austria.
    Lorünser, Thomas
    Austrian Institute of Technology, Austria.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Peev, Momtchil
    Austrian Institute of Technology, Austria.
    Quantum cryptography and authentication with low key-consumption2011In: Proceedings of SPIE - The International Society for Optical Engineering, 2011, 818916- p.Conference paper (Refereed)
    Abstract [en]

    Quantum Key Distribution (QKD - also referred to as Quantum Cryptography) is a technique for secret key agreement. It has been shown that QKD rigged with Information-Theoretic Secure (ITS) authentication (using secret key) of the classical messages transmitted during the key distribution protocol is also ITS. Note, QKD without any authentication can trivially be broken by man-in-the-middle attacks. Here, we study an authentication method that was originally proposed because of its low key consumption; a two-step authentication that uses a publicly known hash function, followed by a secret strongly universal2 hash function, which is exchanged each round. This two-step authentication is not information-theoretically secure but it was argued that nevertheless it does not compromise the security of QKD. In the current contribution we study intrinsic weaknesses of this approach under the common assumption that the QKD adversary has access to unlimited resources including quantum memories. We consider one implementation of Quantum Cryptographic protocols that use such authentication and demonstrate an attack that fully extract the secret key. Even including the final key from the protocol in the authentication does not rule out the possibility of these attacks. To rectify the situation, we propose a countermeasure that, while not informationtheoretically secure, restores the need for very large computing power for the attack to work. Finally, we specify conditions that must be satisfied by the two-step authentication in order to restore informationtheoretic security.

  • 36.
    Abongo, D. A.
    et al.
    University of Nairobi, Kenya.
    Wandiga, S. O.
    University of Nairobi, Kenya.
    Jumba, I. O.
    University of Nairobi, Kenya.
    Van den Brink, P. J.
    University of Wageningen and Research Centre, Netherlands.
    Naziriwo, B. B.
    Makerere University, Uganda.
    Madadi, V. O.
    University of Nairobi, Kenya.
    Wafula, G. A.
    University of Nairobi, Kenya.
    Nkedi-Kizza, P.
    University of Florida, FL USA.
    Kylin, Henrik
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. North West University, South Africa.
    Occurrence, abundance and distribution of benthic macroinvertebrates in the Nyando River catchment, Kenya2015In: African Journal of Aquatic Science, ISSN 1608-5914, E-ISSN 1727-9364, Vol. 40, no 4, 373-392 p.Article in journal (Refereed)
    Abstract [en]

    A baseline study was conducted of the occurrence of macroinvertebrates at 26 sites in the Nyando River catchment in 2005-2006. A total of 13 orders and 16 families of Arthropoda, Mollusca, Platyhelminthes and Annelida were collected, with the order Ephemeroptera being most abundant in the up- and mid-stream reaches, followed by Hemiptera and Plecoptera respectively. The downstream sections of the river were dominated by Hirudinea and tubificids, as the water quality deteriorated mainly due to local land use, raw sewage effluent discharge and annual floods. Insects and annelids were the main invertebrates found and the extent of pollution increased from mid-section (Site 15) downwards as the river flowed into the Winam Gulf. Stringent management measures are required to safeguard the environment and ecosystems of Lake Victoria.

  • 37.
    Abong'o, Deborah
    et al.
    University of Nairobi, Kenya.
    Wandiga, Shem
    University of Nairobi, Kenya.
    Jumba, Isaac
    University of Nairobi, Kenya.
    Madadi, Vincent
    University of Nairobi, Kenya.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Impacts of pesticides on human health and environment in the River Nyando catchment, Kenya2014In: International Journal of Humanities, Arts, Medicine and Sciences, ISSN 2348-0521, Vol. 2, no 3, 1-14 p.Article in journal (Other academic)
    Abstract [en]

    The population of the River Nyando catchment largely relies on rain fed agriculture for their subsistence.

    Important crops grown include cereals, cash crops fruits and vegetables. Farming is one of the contributors of pollution to Lake Victoria. Organophosphates and other banned organochlorine pesticides such as lindane, aldrin and dieldrin were used by farmers. The pesticides transport was by storm water run-off and air drift into the lake. Environmental risk assessment background information was collected through questionnaire and interviews of farmers to determine knowledge and safe use of pesticides. Fourteen pesticides were identified as commonly used of which four are toxic to bees and five to birds. The farmers identified declines in the number of pollinating insects, the disappearance of Red-billed Oxpecker (Buphagus erythrorthynchus) and wild bird’s fatalities. The general knowledge among farmers about chemicals risks, safety, and chronic illnesses was low. Activities that increases environmental awareness and safety of pesticides should be initiated by the agrochemical firms and government.

  • 38.
    Abong'o, Deborah
    et al.
    University of Nairobi, Kenya.
    Wandiga, Shem
    University of Nairobi. Kenya.
    Jumba, Isac
    University of Nairobi, Kenya.
    van den Brink, Paul
    Wageningen University, the Netherlands.
    Nazariwo, Betty
    Makerere University, Uganda.
    Madadi, Vincent
    University of Nairobi, Kenya.
    Wafula, Godfrey
    University of Nairobi, Kenya.
    Kylin, Henrik
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Nkedi-Kizza, Peter
    University of Florida, USA.
    Organochlorine pesticide residue levels in soil from the Nyando River catchment, Kenya2015In: Africa Journal of Physical Sciences, ISSN 2313-3317, Vol. 2, no 1, 18-32 p.Article in journal (Refereed)
    Abstract [en]

    Soil samples were collected from six locations representative of the Nyando River catchment area of the Lake Victoria over a period of two years. Sampling was done four times in the year in February, May, September and December 2005 and 2006 in farms where maize, tea, sugar cane, coffee, rice and vegetables have been grown over the years. This coincided with the effects of different seasons and farming activities on residue levels of the pesticides in use. The objective was to investigate levels and distribution of organochlorine pesticides that have either been banned or are restricted for use in Kenya. Organochlorine pesticides investigated were DDT, lindane, aldrin, dieldrin, heptachlor, endrin, endosulfan (both α- and β- isomers and endosulfan sulphate), the sum is called “total” or Σendosulfan and methoxychlor. Prior to the ban or restriction in use, these pesticides had found wide applications in public health for control of disease vectors and in agriculture for control of crop pests. The analysis revealed presence of all the targeted pesticides with the highest mean concentrations for methoxychlor 140 ± 1.5 μg/kg, Σendosulfan (30 ± 2.1 μg/kg), aldrin (18 ± 0.28 μg/kg), respectively. The results show the presence of these pesticides in soils in the basin and this could be impacting negatively on the ecosystem health of the area.

  • 39.
    Abraham-Nordling, Mirna
    et al.
    Karolinska institutet.
    Persson, Bengt
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics. Linköping University, The Institute of Technology.
    Nordling, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics. Linköping University, The Institute of Technology.
    Model of the complex of Parathyroid hormone-2receptor and Tuberoinfundibular peptide of39 residues2010In: BMC Reseach Notes, ISSN 1756-0500, Vol. 3, no 270Article in journal (Refereed)
    Abstract [en]

    Background

    We aim to propose interactions between the parathyroid hormone-2 receptor (PTH2R) and its ligand the tuberoinfundibular peptide of 39 residues (TIP39) by constructing a homology model of their complex. The two related peptides parathyroid hormone (PTH) and parathyroid hormone related protein (PTHrP) are compared with the complex to examine their interactions.

    Findings

    In the model, the hydrophobic N-terminus of TIP39 is buried in a hydrophobic part of the central cavity between helices 3 and 7. Comparison of the peptide sequences indicates that the main discriminator between the agonistic peptides TIP39 and PTH and the inactive PTHrP is a tryptophan-phenylalanine replacement. The model indicates that the smaller phenylalanine in PTHrP does not completely occupy the binding site of the larger tryptophan residue in the other peptides. As only TIP39 causes internalisation of the receptor and the primary difference being an aspartic acid in position 7 of TIP39 that interacts with histidine 396 in the receptor, versus isoleucine/histidine residues in the related hormones, this might be a trigger interaction for the events that cause internalisation.

    Conclusions

    A model is constructed for the complex and a trigger interaction for full agonistic activation between aspartic acid 7 of TIP39 and histidine 396 in the receptor is proposed.

  • 40.
    Abrahamsson, Björn
    Linköping University, Department of Electrical Engineering.
    Architectures for Multiplication in Galois Rings2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis investigates architectures for multiplying elements in Galois rings of the size 4^m, where m is an integer.

    The main question is whether known architectures for multiplying in Galois fields can be used for Galois rings also, with small modifications, and the answer to that question is that they can.

    Different representations for elements in Galois rings are also explored, and the performance of multipliers for the different representations is investigated.

  • 41.
    Abrahamsson, David
    Linköping University, Department of Computer and Information Science.
    Security Enhanced Firmware Update Procedures in Embedded Systems2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many embedded systems are complex, and it is often required that the firmware in these systems are updatable by the end-user. For economical and confidentiality reasons, it is important that these systems only accept firmware approved by the firmware producer.

    This thesis work focuses on creating a security enhanced firmware update procedure that is suitable for use in embedded systems. The common elements of embedded systems are described and various candidate algorithms are compared as candidates for firmware verification. Patents are used as a base for the proposal of a security enhanced update procedure. We also use attack trees to perform a threat analysis on an update procedure.

    The results are a threat analysis of a home office router and the proposal of an update procedure. The update procedure will only accept approved firmware and prevents reversion to old, vulnerable, firmware versions. The firmware verification is performed using the hash function SHA-224 and the digital signature algorithm RSA with a key length of 2048. The selection of algorithms and key lengths mitigates the threat of brute-force and cryptanalysis attacks on the verification algorithms and is believed to be secure through 2030.

  • 42.
    Abrahamsson, Lars
    Linköping University, Department of Electrical Engineering.
    A portal based system for indoor environs2006Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    The purpose of this thesis is to document the development of the graphics part of an extremely pluggable game engine/lab environment for a course in advanced game programming. This thesis is one out of five, and concerns indoor, realtime computer 3D graphics. It covers state-of-the-art techniques such as GLSL - the OpenGL Shading Language - and more well known techniques such as portal based rendering.

  • 43.
    Abrahamsson, Marcus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    A platform for third-party applications on the web2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    A trend seen on the web today is to create a platform where externally developed applications can run inside some kind of main application. This is often done by providing an API to access data and business logic of your service and a sandbox environment in which third-party applications can run. By providing this, it is made possible for external developers to come up with new ideas based on your service. Some good examples on this are Spotify Apps, Apps on Facebook and SalesForce.com.

    Ipendo Systems AB is a company that develops a web platform for intellectual properties. Currently most things on this platform are developed by developers at Ipendo Systems AB. Some interest has though risen to enable external developers to create applications that will in some way run inside the main platform.

    In this thesis an analysis of already existing solutions has been done. These solutions were Spotify Apps and Apps on Facebook. The two have different approaches on how to enable third-party applications to run inside their own service. Facebook’s solution builds mainly on iframe embedded web pages where data access is provided through a web API. Spotify on the other hand hosts the third-party applications themselves but the applications may only consist of HTML5, CSS3 and JavaScript.

    In addition to the analysis a prototype was developed. The purpose of the prototype was to show possible ways to enable third-party applications to run inside your own service. Two solutions showing this were developed. The first one was based on Facebook’s approach with iframing of external web pages. The second was a slightly modified version of Spotify’s solution with only client-side code hosted by the main application. To safely embed the client side code in the main application a sandboxing tool for JavaScript called Caja was used.

    Of the two versions implemented in the prototype was the Iframe solution considered more ready to be utilized in a production environment than Caja. Caja could be seen as an interesting technique for the future but might not be ready to use today. The reason behind this conclusion was that Caja decreased the performance of the written JavaScript as well as adding complexity while developing the third-party applications.

  • 44.
    Abrahamsson, Olle
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    A Gröbner basis algorithm for fast encoding of Reed-Müller codes2016Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    In this thesis the relationship between Gröbner bases and algebraic coding theory is investigated, and especially applications towards linear codes, with Reed-Müller codes as an illustrative example. We prove that each linear code can be described as a binomial ideal of a polynomial ring, and that a systematic encoding algorithm for such codes is given by the remainder of the information word computed with respect to the reduced Gröbner basis. Finally we show how to apply the representation of a code by its corresponding polynomial ring ideal to construct a class of codes containing the so called primitive Reed-Müller codes, with a few examples of this result.

  • 45.
    Abrahamsson, Olle
    Linköping University, Department of Electrical Engineering, Communication Systems.
    Hide and Seek in a Social Network2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis a known heuristic for decreasing a node's centrality scores while maintaining influence, called ROAM, is compared to a modified version specifically designed to decrease eigenvector centrality. The performances of these heuristics are also tested against the Shapley values of a cooperative game played over the considered network, where the game is such that influential nodes receive higher Shapley values. The modified heuristic performed at least as good as the original ROAM, and in some instances even better (especially when the terrorist network behind the World Trade Center attacks was considered). Both heuristics increased the influence score for a given targeted node when applied consecutively on the WTC network, and consequently the Shapley values increased as well. Therefore the Shapley value of the game considered in this thesis seems to be well suited for discovering individuals that are assumed to actively trying to evade social network analysis.

  • 46.
    Abrahamsson, Peder
    Linköping University, Department of Computer and Information Science.
    Mer lättläst: Påbyggnad av ett automatiskt omskrivningsverktyg till lätt svenska2011Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [sv]

    Det svenska språket ska finnas tillgängligt för alla som bor och verkar i Sverige. Därförär det viktigt att det finns lättlästa alternativ för dem som har svårighet att läsa svensktext. Detta arbete bygger vidare på att visa att det är möjligt att skapa ett automatisktomskrivningsprogram som gör texter mer lättlästa. Till grund för arbetet liggerCogFLUX som är ett verktyg för automatisk omskrivning till lätt svenska. CogFLUXinnehåller funktioner för att syntaktiskt skriva om texter till mer lättläst svenska.Omskrivningarna görs med hjälp av omskrivningsregler framtagna i ett tidigare projekt.I detta arbete implementeras ytterligare omskrivningsregler och även en ny modul förhantering av synonymer. Med dessa nya regler och modulen ska arbetet undersöka omdet är det är möjligt att skapa system som ger en mer lättläst text enligt etableradeläsbarhetsmått som LIX, OVIX och Nominalkvot. Omskrivningsreglerna ochsynonymhanteraren testas på tre olika texter med en total lägnd på ungefär hundra tusenord. Arbetet visar att det går att sänka både LIX-värdet och Nominalkvoten signifikantmed hjälp av omskrivningsregler och synonymhanterare. Arbetet visar även att det finnsfler saker kvar att göra för att framställa ett riktigt bra program för automatiskomskrivning till lätt svenska.

  • 47.
    Abrahamsson, Robin
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Berntsen, David
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Comparing modifiability of React Native and two native codebases2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Creating native mobile application on multiple platforms generate a lot of duplicate code. This thesis has evaluated if the code quality attribute modifiability improves when migrating to React Native. One Android and one iOS codebase existed for an application and a third codebase was developed with React Native. The measurements of the codebases were based on the SQMMA-model. The metrics for the model were collected with static analyzers created specifically for this project. The results created consists of graphs that show the modifiability for some specific components over time and graphs that show the stability of the platforms. These graphs show that when measuring code metrics on applications over time it is better to do this on a large codebase that has been developed for some time. When calculating a modifiability value the sum of the metrics and the average value of the metrics between files should be used and it is shown that the React Native platform seems to be more stable than native.

  • 48.
    Abrahamsson, S.
    et al.
    SLU, Umeå, Sweden .
    Ahlinder, J.
    FOI, Umeå, Sweden .
    Waldmann, Patrik
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, The Institute of Technology.
    García-Gil, M. R.
    SLU, Umeå, Sweden .
    Maternal heterozygosity and progeny fitness association in an inbred Scots pine population2013In: Genetica, ISSN 0016-6707, E-ISSN 1573-6857, Vol. 141, no 1-3, 41-50 p.Article in journal (Refereed)
    Abstract [en]

    Associations between heterozygosity and fitness traits have typically been investigated in populations characterized by low levels of inbreeding. We investigated the associations between standardized multilocus heterozygosity (stMLH) in mother trees (obtained from12 nuclear microsatellite markers) and five fitness traits measured in progenies from an inbred Scots pine population. The traits studied were proportion of sound seed, mean seed weight, germination rate, mean family height of one-year old seedlings under greenhouse conditions (GH) and mean family height of three-year old seedlings under field conditions (FH). The relatively high average inbreeding coefficient (F) in the population under study corresponds to a mixture of trees with different levels of co-ancestry, potentially resulting from a recent bottleneck. We used both frequentist and Bayesian methods of polynomial regression to investigate the presence of linear and non-linear relations between stMLH and each of the fitness traits. No significant associations were found for any of the traits except for GH, which displayed negative linear effect with stMLH. Negative HFC for GH could potentially be explained by the effect of heterosis caused by mating of two inbred mother trees (Lippman and Zamir 2006), or outbreeding depression at the most heterozygote trees and its negative impact on the fitness of the progeny, while their simultaneous action is also possible (Lynch. 1991). However,since this effect wasn’t detected for FH, we cannot either rule out that the greenhouse conditions introduce artificial effects that disappear under more realistic field conditions.

  • 49.
    Abramavicius, V.
    et al.
    Vilnius University, Lithuania; Centre Phys Science and Technology, Lithuania.
    Pranculis, V.
    Centre Phys Science and Technology, Lithuania.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gulbinas, V.
    Centre Phys Science and Technology, Lithuania.
    Abramavicius, D.
    Vilnius University, Lithuania.
    Role of coherence and delocalization in photo-induced electron transfer at organic interfaces2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 32914Article in journal (Refereed)
    Abstract [en]

    Photo-induced charge transfer at molecular heterojunctions has gained particular interest due to the development of organic solar cells (OSC) based on blends of electron donating and accepting materials. While charge transfer between donor and acceptor molecules can be described by Marcus theory, additional carrier delocalization and coherent propagation might play the dominant role. Here, we describe ultrafast charge separation at the interface of a conjugated polymer and an aggregate of the fullerene derivative PCBM using the stochastic Schrodinger equation (SSE) and reveal the complex time evolution of electron transfer, mediated by electronic coherence and delocalization. By fitting the model to ultrafast charge separation experiments, we estimate the extent of electron delocalization and establish the transition from coherent electron propagation to incoherent hopping. Our results indicate that even a relatively weak coupling between PCBM molecules is sufficient to facilitate electron delocalization and efficient charge separation at organic interfaces.

  • 50.
    Abramsson, Mia
    et al.
    Swedish Energy Agency, Sweden.
    Jidesjö, Anders
    Swedish Energy Agency, Sweden.
    Research and development projects aiming to increase young adults’ knowledge of energy and energy efficiency2015In: eceee Summer Study proceedings / [ed] Therese Laitinen Lindström, Borg & Co, Stockholm, Sweden, European Council for an Energy Efficient Economy (ECEEE), 2015, 509-514 p.Conference paper (Refereed)
    Abstract [en]

    Children and young adults are important target groups in order to decrease the climate change effects and increase an energy-efficient end use. With increased knowledge and awareness these target groups could play a constructive role in the current and future transition of the energy system. The correlation between knowledge, awareness and behavioral change is central for improved energy efficiency in the society. Children and young adults and their interest in the natural and technical science are central to ensure the long-term capability needed to transform the energy system.

    To support this development the Swedish Energy Agency started with young adults as a target group in research and development projects in 2008. Since then approximately 5 million EUR has been allocated for projects aiming to increase knowledge in these areas among young adults by developing practical methods and tools, educational material or in-service training for teachers. Around thirty projects have been supported and three of them, KNUT school development project, KNUT evaluation research project and The Energy Fall, will be discussed in this paper.

     

    The KNUT school development project is a national school project aiming at increasing students’ knowledge and interest in energy and energy efficiency. KNUT also stimulates learning and career choices related to energy, climate and resources and therefor strengthen Sweden's capacities and competitiveness future in these areas. To ensure the scientific base a research group from Linköping University (KNUT evaluation research project) has followed the project’s activities. Best practices of methods and tools have been tested and disseminated within the project at both regional and national level.

     

    The KNUT evaluation research project has identified and analyzed five success factors regarding energy, climate change and energy efficiency of importance for education: 

    • The relationships between the national, regional and local level

    • The function of education vary in time due to the development of society

    • Get to know the education content inside and outside of school

    • Successful meetings between different actors

    • The educational systems capacity to educate all and at the same time recruit some for specialization

    This paper will present an overview of the Swedish Energy Agency’s work on research and development projects aiming to increase young adults’ knowledge of energy and energy efficiency and the KNUT evaluation research project results, analysis and success factors.

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