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  • 4801.
    Verenzuela, Daniel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Miao, Guowang
    KTH Royal Institute Technology, Sweden; Freelinguist Com, Sweden.
    Scalable D2D Communications for Frequency Reuse 1 in 5G2017Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, nr 6, 3435-3447 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Proximity-based applications are becoming fast growing markets suggesting that device-to-device (D2D) communications is becoming an essential part of the future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. In practice, as D2D communications will generate a new layer of interference, it is essential to take D2D interference into account in inter-cell interference coordination for multi-cell communications. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse in a practical 5G multi-cell environment. Different schemes are designed for applications that have different levels of complexity and availability of channel state information. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provide QoS for all users.

  • 4802.
    Vergara Alonso, Ekhiotz Jon
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Energy Modelling and Fairness for Efficient Mobile Communication2016Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Energy consumption and its management have been clearly identified as a challenge in computing and communication system design, where energy economy is obviously of paramount importance for battery powered devices. This thesis addresses the energy efficiency of mobile communication at the user end in the context of cellular networks.

    We argue that energy efficiency starts by energy awareness and propose EnergyBox, a parametrised tool that enables accurate and repeatable energy quantification at the user end using real data traffic traces as input. EnergyBox offers an abstraction of the underlying states for operation of the wireless interfaces and allows to estimate the energy consumption for different operator settings and device characteristics. The tool is used throughout the thesis to quantify and reveal inefficient data communication patterns of widely used mobile applications.

    We consider two different perspectives in the search of energy-efficient solutions. From the application perspective, we show that systematically quantifying the energy consumption of design choices (e.g., communication patterns, protocols, and data formats) contributes to a significantly smaller energy footprint. From the system perspective, we devise a cross-layer solution that schedules packet transmissions based on the knowledge of the network parameters that impact the energy consumption of the handset. These attempts show that application level decisions require a better understanding of possible energy apportionment policies at system level.

    Finally, we study the generic problem of determining the contribution of an entity (e.g., application) to the total energy consumption of a given system (e.g., mobile device). We compare the state-of-the-art policies in terms of fairness leveraging cooperative game theory and analyse their required information and computational complexity. We show that providing incentives to reduce the total energy consumption of the system (as part of fairness) is tightly coupled to the policy selection. Our study provides guidelines to select an appropriate policy depending on the characteristics of the system. 

  • 4803.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Fairness and Incentive Considerations in Energy Apportionment Policies2016Ingår i: ACM Transactions on Modeling and Performance Evaluation of Computing Systems, ISSN 2376-3639, Vol. 2, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The energy consumption of a system is determined by the system component usage patterns and interactions between the coexisting entities and resources. Energy accounting plays an essential role to reveal the contribution of each entity to the total consumption and for energy management. Unfortunately, energy accounting inherits the apportionment problem of accounting in general, which does not have a general single best solution. In this paper we leverage cooperative game theory commonly used in cost allocation problems to study the energy apportionment problem, i.e., the problem of prescribing the actual energy consumption of a system to the consuming entities (e.g., applications, processes or users of the system).

    We identify five relevant fairness properties for energy apportionment and present a detailed categorisation and analysis of eight previously proposed energy apportionment policies from different fields in computer and communication systems. In addition, we propose two novel energy apportionment policies based on cooperative game theory which provide strong fairness notion and a rich incentive structure. Our comparative analysis in terms of the identified five fairness properties as well as information requirement and computational complexity shows that there is a trade-off between fairness and the other evaluation criteria. We provide guidelines to select an energy apportionment policy depending on the purpose of the apportionment and the characteristics of the system.

  • 4804.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Sharing the Cost of Lunch: Energy Apportionment Policies2015Ingår i: Proceedings of the 11th ACM Symposium on QoS and Security for Wireless and Mobile Networks, ACM Digital Library, 2015, 91-97 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Energy consumption has become a hot topic in computer and communication technologies pinpointing the need to carefully analyse system efficiency. The energy consumption of a system is determined by the usage patterns of system components and complex interactions between the coexisting entities and resources. Providing transparency of a system’s consumption by breaking down the total consumption is vital to evaluate and provide energy-efficient design and operation.

    In this paper we survey the apportionment problem in different fields such as computer systems, wireless sensor networks, mobile devices and energy-efficient buildings. The challenge lies in how to attribute a share of the total energy consumption to the responsible entities (e.g., applications, processes or users of the system). Our analysis identifies that energy apportionment is a common problem in different fields and reviews five previously applied energy apportionment policies. Also, the work identifies relevant further research.

  • 4805.
    Verhaegen, Michel
    et al.
    Delft University of Technology, Netherlands.
    Hansson, Anders
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    N2SID: Nuclear norm subspace identification of innovation models2016Ingår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 72, 57-63 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The identification of multivariable state space models in innovation form is solved in a subspace identification framework using convex nuclear norm optimization. The convex optimization approach allows to include constraints on the unknown matrices in the data-equation characterizing subspace identification methods, such as the lower triangular block-Toeplitz of weighting matrices constructed from the Markov parameters of the unknown observer. The classical use of instrumental variables to remove the influence of the innovation term on the data equation in subspace identification is avoided. The avoidance of the instrumental variable projection step has the potential to improve the accuracy of the estimated model predictions, especially for short data length sequences. (C) 2016 Elsevier Ltd. All rights reserved.

  • 4806.
    Verhaegen, Michel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Hansson, Anders
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Nuclear norm subspace identification (N2SID) for short data batches2014Ingår i: Proceedings of IFAC 2014 World Congress, Cape Town, 2014, 9528-9533 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Subspace identification is revisited in the scope of nuclear norm minimization methods. It is shown that essential structural knowledge about the unknown data matrices in the data equation that relates Hankel matrices constructed from input and output data can be used in the first step of the numerical solution presented. The structural knowledge comprises the low rank property of a matrix that is the product of the extended observability matrix and the state sequence and the Toeplitz structure of the matrix of Markov parameters (of the system in innovation form). The new subspace identification method is referred to as the N2SID (twice the N of Nuclear Norm and SID for Subspace IDentification) method. In addition to include key structural knowledge in the solution it integrates the subspace calculation with minimization of a classical prediction error cost function. The nuclear norm relaxation enables us to perform such integration while preserving convexity. The advantages of N2SID are demonstrated in a numerical open- and closed-loop simulation study. Here a comparison is made with another widely used SID method, i.e. N4SID. The comparison focusses on the identification with short data batches, i.e. where the number of measurements is a small multiple of the system order.

  • 4807.
    Vermang, Bart
    et al.
    Uppsala University, Sweden; University of Leuven, Belgium.
    Timo Watjen, Jorn
    Uppsala University, Sweden.
    Fjallstrom, Viktor
    Uppsala University, Sweden.
    Rostvall, Fredrik
    Uppsala University, Sweden.
    Edoff, Marika
    Uppsala University, Sweden.
    Gunnarsson, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
    Pilch, Iris
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Helmersson, Ulf
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
    Kotipalli, Ratan
    Catholic University of Louvain, Belgium.
    Henry, Frederic
    Catholic University of Louvain, Belgium.
    Flandre, Denis
    Catholic University of Louvain, Belgium.
    Highly reflective rear surface passivation design for ultra-thin Cu(In,Ga) Se-2 solar cells2015Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 582, 300-303 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Al2O3 rear surface passivated ultra-thin Cu(In,Ga)Se-2 (CIGS) solar cells with Mo nano-particles (NPs) as local rear contacts are developed to demonstrate their potential to improve optical confinement in ultra-thin CIGS solar cells. The CIGS absorber layer is 380 nm thick and the Mo NPs are deposited uniformly by an up-scalable technique and have typical diameters of 150 to 200 nm. The Al2O3 layer passivates the CIGS rear surface between the Mo NPs, while the rear CIGS interface in contact with the Mo NP is passivated by [Ga]/([Ga] + [In]) (GGI) grading. It is shown that photon scattering due to the Mo NP contributes to an absolute increase in short circuit current density of 3.4 mA/cm(2); as compared to equivalent CIGS solar cells with a standard back contact.

  • 4808.
    Vernon, David
    et al.
    University of Skövde, School of Informatics.
    Billing, Erik
    University of Skövde, School of Informatics.
    Thill, Serge
    University of Skövde, School of Informatics.
    Hemeren, Paul
    University of Skövde, School of Informatics.
    Ziemke, Tom
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten. University of Skövde.
    An Architecture-oriented Approach to System Integration in Collaborative Robotics Research Projects: An Experience Report2015Ingår i: Journal of Software Engineering for Robotics, ISSN 2035-3928, E-ISSN 2035-3928, Vol. 6, nr 1, 15-32 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Effective system integration requires strict adherence to strong software engineering standards, a practice not much favoured in many collaborative research projects. We argue that component-based software engineering (CBSE) provides a way to overcome this problem because it provides flexibility for developers while requiring the adoption of only a modest number of software engineering practices. This focus on integration complements software re-use, the more usual motivation for adopting CBSE. We illustrate our argument by showing how a large-scale system architecture for an application in the domain of robot-enhanced therapy for children with autism spectrum disorder (ASD) has been implemented. We highlight the manner in which the integration process is facilitated by the architecture implementation of a set of placeholder components that comprise stubs for all functional primitives, as well as the complete implementation of all inter-component communications. We focus on the component-port-connector meta-model and show that the YARP robot platform is a well-matched middleware framework for the implementation of this model. To facilitate the validation of port-connector communication, we configure the initial placeholder implementation of the system architecture as a discrete event simulation and control the invocation of each component’s stub primitives probabilistically. This allows the system integrator to adjust the rate of inter-component communication while respecting its asynchronous and concurrent character. Also, individual ports and connectors can be periodically selected as the simulator cycles through each primitive in each sub-system component. This ability to control the rate of connector communication considerably eases the task of validating component-port-connector behaviour in a large system. Ultimately, over and above its well-accepted benefits for software re-use in robotics, CBSE strikes a good balance between software engineering best practice and the socio-technical problem of managing effective integration in collaborative robotics research projects.

  • 4809.
    Vernon, David
    et al.
    University of Skovde, Sweden.
    Lowe, Robert
    University of Skovde, Sweden; University of Gothenburg, Sweden.
    Thill, Serge
    University of Skovde, Sweden.
    Ziemke, Tom
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten. University of Skovde, Sweden.
    Embodied cognition and circular causality: on the role of constitutive autonomy in the reciprocal coupling of perception and action2015Ingår i: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 6, nr 1660Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reciprocal coupling of perception and action in cognitive agents has been firmly established: perceptions guide action but so too do actions influence what is perceived. While much has been said on the implications of this for the agents external behavior, less attention has been paid to what it means for the internal bodily mechanisms which underpin cognitive behavior. In this article, we wish to redress this by reasserting that the relationship between cognition, perception, and action involves a constitutive element as well as a behavioral element, emphasizing that the reciprocal link between perception and action in cognition merits a renewed focus on the system dynamics inherent in constitutive biological autonomy. Our argument centers on the idea that cognition, perception, and action are all dependent on processes focussed primarily on the maintenance of the agents autonomy. These processes have an inherently circular nature self-organizing, self producing, and self-maintaining and our goal is to explore these processes and suggest how they can explain the reciprocity of perception and action. Specifically, we argue that the reciprocal coupling is founded primarily on their endogenous roles in the constitutive autonomy of the agent and an associated circular causality of global and local processes of self regulation, rather than being a mutual sensory-motor contingency that derives from exogenous behavior. Furthermore, the coupling occurs first and foremost via the internal milieu realized by the agents organismic embodiment. Finally, we consider how homeostasis and the related concept of allostasis contribute to this circular self regulation.

  • 4810.
    Vernon, David
    et al.
    University of Skövde, School of Informatics.
    Thill, Serge
    University of Skövde, School of Informatics.
    Ziemke, Tom
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten. University of Skövde.
    The role of intention in cognitive robotics2016Ingår i: Toward Robotic Socially Believable Behaving Systems: Modeling Emotions / [ed] Esposito, Anna; Jain, Lakhmi C., Springer, 2016, 15-27 s.Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    We argue that the development of robots that can interact effectively with people requires a special focus on building systems that can perceive and comprehend intentions in other agents. Such a capability is a prerequisite for all pro-social behaviour and in particular underpins the ability to engage in instrumental helping and mutual collaboration. We explore the prospective and intentional nature ofaction, highlighting the importance of joint action, shared goals, shared intentions,and joint attention in facilitating social interaction between two or more cognitive agents. We discuss the link between reading intentions and theory of mind, notingthe role played by internal simulation, especially when inferring higher-level action focussed intentions. Finally, we highlight that pro-social behaviour in humans is the result of a developmental process and we note the implications of this for the challenge of creating cognitive robots that can read intentions.

  • 4811.
    Vibeck, Alexander
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Synchronization of a Multi Camera System2015Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In a synchronized multi camera system it is imperative that the synchronization error between the different cameras is as close to zero as possible and the jitter of the presumed frame rate is as small as possible. It is even more important when these systems are used in an autonomous vehicle trying to sense its surroundings. We would never hand over the control to a autonomous vehicle if we couldn't trust the data it is using for moving around.

    The purpose of this thesis was to build a synchronization setup for a multi camera system using state of the art RayTrix digital cameras that will be used in the iQMatic project involving autonomous heavy duty vehicles. The iQMatic project is a collaboration between several Swedish industrial partners and universities. There was also software development for the multi camera system involved. Different synchronization techniques were implemented and then analysed against the system requirements. The two techniques were hardware trigger i.e. external trigger using a microcontroller, and software trigger using the API from the digital cameras.

    Experiments were conducted by testing the different trigger modes with the developed multi camera software. The conclusions show that the hardware trigger is preferable in this particular system by showing more stability and better statistics against the system requirements than the software trigger. But the thesis also show that additional experiments are needed for a more accurate analysis.

  • 4812.
    Vicente, Antonio T.
    et al.
    University of Nova Lisboa, Portugal; CEMOP UNINOVA, Portugal.
    Wojcik, Pawel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. University of Nova Lisboa, Portugal; CEMOP UNINOVA, Portugal.
    Mendes, Manuel J.
    University of Nova Lisboa, Portugal; CEMOP UNINOVA, Portugal.
    Aguas, Hugo
    University of Nova Lisboa, Portugal; CEMOP UNINOVA, Portugal.
    Fortunato, Elvira
    University of Nova Lisboa, Portugal; CEMOP UNINOVA, Portugal.
    Martins, Rodrigo
    University of Nova Lisboa, Portugal; CEMOP UNINOVA, Portugal.
    A statistics modeling approach for the optimization of thin film photovoltaic devices2017Ingår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 144, 232-243 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growing interest in exploring thin film technologies to produce low cost devices such as n-i-p silicon solar cells, with outstanding performances and capability to address the highly relevant energy market, turns the optimization of their fabrication process a key area of development. The usual one-dimensional analysis of the involved parameters makes it difficult and time consuming to find the optimal set of conditions. To overcome these difficulties, the combination of experimental design and statistical analysis provides the tools to explore in a multidimensional fashion the interactions between fabrication parameters and expected experimental outputs. Design of Experiment and Multivariate Analysis are demonstrated here for the optimization of: (1) the low temperature deposition (150 degrees C) of high quality intrinsic amorphous silicon (i-a-Si:H); and (2) the matching of the n-, i-, and p-silicon layers thickness to maximize the efficiency of thin film solar cells. The multiple regression method applied, validated through analysis of variance and evaluated against exact numerical simulations, is shown to predict the overall intrinsic layer properties and the devices performance. The results confirm that experimental design and statistical data analysis are effective approaches to improve, within a minimum time frame and high certainty, the properties of silicon thin films, and subsequently the layer structure of solar cells.(C) 2017 Published by Elsevier Ltd.

  • 4813.
    Videvall, Elin
    et al.
    Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Lund, Sweden.
    Sletvold, Nina
    Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Hagenblad, Jenny
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten. Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University.
    Ågren, Jon
    Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Hansson, Bengt
    Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Lund, Sweden.
    Strong Maternal Effects on Gene Expression inArabidopsis lyrata Hybrids2016Ingår i: Molecular Biology and Evolution, ISSN 0737-4038, Vol. 33, nr 4, 984-994 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hybridization between populations or species can have pronounced fitness consequences. Yet little is known about howhybridization affects gene regulation. Three main models have been put forward to explain gene expression patterns inhybrids: additive, dominance, or parental effects. Here, we use high throughput RNA-sequencing to examine the extent towhich hybrid gene expression follows predictions by each of the three models. We performed a reciprocal crossingexperiment between two differentiated populations of the perennial herb Arabidopsis lyrata and sequenced RNA inrosette leaves of 12-week-old plants grown in greenhouse conditions. The two parental populations had highly differentiatedgene expression patterns. In hybrids, a majority of genes showed intermediate expression relative to that of theirparental populations (i.e., additive effects), but expression was frequently more similar to the maternal than to theirpaternal population (i.e., maternal effects). Allele-specific expression analyses showed that in the vast majority of cases,genes with pronounced maternal effect expressed both the maternal and the paternal allele. Maternal effects on hybridgene expression have rarely been documented previously and our study suggests it could be more common thanpreviously assumed. Whether the maternal effect on gene expression persists to later life-stages, and whether thevariation in gene expression is manifested in other aspects of the phenotype, remain to be elucidated. Our findingsare relevant for understanding the consequences of outbreeding and hybridization and open up several questions forfuture studies.

  • 4814.
    Vidlid, Marija
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Konstruktion av strömförsörjningsmodul till testsystem2015Självständigt arbete på grundnivå (högskoleexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete är utfört vid den tekniska högskolan vid Linköping Universitet på programmet högskoleingenjör elektronik. Uppdragsgivaren, Flextronics, är ett företag som utvecklar generell testutrustning inom elektronikproduktion. Den testutrustning som finns behöver uppdateras och examensarbetet går ut på att bygga en ny strömförsörjningsmodul till denna. Den största skillnaden mot tidigare system är att den nya strömförsörjningsmodulen ska klara av högre uteffekt. Eftersom den nya testutrustningen redan är påbörjad finns några krav att ta hänsyn till och ett av dem är att det ska finnas en mikrokontroller i strömförsörjningsmodulen. Mikrokontrollern kan ha funktioner som är användbara såsom inbyggda DAC:ar och ADC:er och designen har gjorts om så att dessa kan utnyttjas och till och med sköta regleringen. Efter en del databladsläsande och simulerande utvecklades en lösning som har med två regulatorer vilka styrs av mikrokontrollern. Denna lösning har också konstruerats och utvärderats.

  • 4815.
    Vikingsson, Svante
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten.
    Gréen, Henrik
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping Sweden.
    Brinkhagen, Linda
    Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping Sweden.
    Mukhtar, Shahzabe
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten.
    Josefsson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten. Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping Sweden.
    Identification of AB-FUBINACA metabolites in authentic urine samples suitable as urinary markers of drug intake using liquid chromatography quadrupole tandem time of flight mass spectrometry.2016Ingår i: Drug Testing and Analysis, ISSN 1942-7603, E-ISSN 1942-7611, Vol. 8, nr 9, 950-956 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Synthetic cannabinoids are a group of psychoactive drugs presently widespread among drug users in Europe. Analytical methods to measure these compounds in urine are in demand as urine is a preferred matrix for drug testing. For most synthetic cannabinoids, the parent compounds are rarely detected in urine. Therefore urinary metabolites are needed as markers of drug intake. AB-FUBINACA was one of the top three synthetic cannabinoids most frequently found in seizures and toxicological drug screening in Sweden (2013-2014). Drug abuse is also reported from several other countries such as the USA and Japan. In this study, 28 authentic case samples were used to identify urinary markers of AB-FUBINACA intake using liquid chromatography quadrupole tandem time of flight mass spectrometry and human liver microsomes. Three metabolites suitable as markers of drug intake were identified and at least two of them were detected in all but one case. In total, 15 urinary metabolites of AB-FUBINACA were reported, including hydrolxylations on the indazole ring and the amino-oxobutane moiety, dealkylations and hydrolysis of the primary amide. No modifications on the fluorobenzyl side-chain were observed. The parent compound was detected in 54% of the case samples. Also, after three hours of incubation with human liver microsomes, 77% of the signal from the parent compound remained. Copyright © 2015 John Wiley & Sons, Ltd.

  • 4816.
    Vikingsson, Svante
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten.
    Josefsson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Green, Henrik
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Identification of AKB-48 and 5F-AKB-48 Metabolites in Authentic Human Urine Samples Using Human Liver Microsomes and Time of Flight Mass Spectrometry2015Ingår i: Journal of Analytical Toxicology, ISSN 0146-4760, E-ISSN 1945-2403, Vol. 39, nr 6, 426-435 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The occurrence of structurally related synthetic cannabinoids makes the identification of unique markers of drug intake particularly challenging. The aim of this study was to identify unique and abundant metabolites of AKB-48 and 5F-AKB-48 for toxicological screening in urine. Investigations of authentic urine samples from forensic cases in combination with human liver microsome (HLM) experiments were used for identification of metabolites. HLM incubations of AKB-48 and 5F-AKB-48 along with 35 urine samples from authentic cases were analyzed with liquid chromatography quadrupole tandem time of flight mass spectrometry. Using HLMs 41 metabolites of AKB-48 and 37 metabolites of 5F-AKB-48 were identified, principally represented by hydroxylation but also ketone formation and dealkylation. Monohydroxylated metabolites were replaced by di- and trihydroxylated metabolites within 30 min. The metabolites from the HLM incubations accounted for on average 84% (range, 67-100) and 91% (range, 71-100) of the combined area in the case samples for AKB-48 and 5F-AKB-48, respectively. While defluorinated metabolites accounted for on average 74% of the combined area after a 5F-AKB-48 intake only a few identified metabolites were shared between AKB-48 and 5F-AKB-48, illustrating the need for a systematic approach to identify unique metabolites. HLMs in combination with case samples seem suitable for this purpose.

  • 4817.
    Vikingsson, Svante
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Wohlfarth, Ariane
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Andersson, Mikael
    National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Green, Henrik
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Roman, Markus
    National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Josefsson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Kugelberg, Fredrik
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Kronstrand, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Identifying Metabolites of Meclonazepam by High-Resolution Mass Spectrometry Using Human Liver Microsomes, Hepatocytes, a Mouse Model, and Authentic Urine Samples2017Ingår i: AAPS Journal, ISSN 1550-7416, E-ISSN 1550-7416, Vol. 19, nr 3, 736-742 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Meclonazepam is a benzodiazepine patented in 1977 to treat parasitic worms, which recently appeared as a designer benzodiazepine and drug of abuse. The aim of this study was to identify metabolites suitable as biomarkers of drug intake in urine using high-resolution mass spectrometry, authentic urine samples, and different model systems including human liver microsomes, cryopreserved hepatocytes, and a mice model. The main metabolites of meclonazepam found in human urine were amino-meclonazepam and acetamido-meclonazepam; also, minor peaks for meclonazepam were observed in three of four urine samples. These observations are consistent with meclonazepam having a metabolism similar to that of other nitro containing benzodiazepines such as clonazepam, flunitrazepam, and nitrazepam. Both metabolites were produced by the hepatocytes and in the mice model, but the human liver microsomes were only capable of producing minor amounts of the amino metabolite. However, under nitrogen, the amount of amino-meclonazepam produced increased 140 times. This study comprehensively elucidated meclonazepam metabolism and also illustrates that careful selection of in vitro model systems for drug metabolism is needed, always taking into account the expected metabolism of the tested drug.

  • 4818.
    Vikström, Elena
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Medicinsk mikrobiologi. Linköpings universitet, Hälsouniversitetet.
    Bui, Lan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Konradsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Organisk Kemi. Linköpings universitet, Tekniska högskolan.
    Magnusson, Karl-Eric
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Medicinsk mikrobiologi. Linköpings universitet, Hälsouniversitetet.
    Role of calcium signalling and phosphorylations in disruption of the epithelial junctions by Pseudomonas aeruginosa quorum sensing molecule2010Ingår i: European Journal of Cell Biology, ISSN 0171-9335, E-ISSN 1618-1298, Vol. 89, nr 8, 584-597 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Pseudomonas aeruginosa. cell-cell communication based on acyl-homoserine lactone (HSL) quorum sensing molecules is known to coordinate the production of virulence factors and biofilms by the bacterium. Incidentally, these bacterial signals can also modulate mammalian cell behaviour. We demonstrate here that 3O-C-12-HSL can induce changes in calcium signalling through influx and release of calcium from thapsigargin-sensitive stores and delocalization of inositol 1,4,5-trisphosphate receptors (IP3R), but not of ryanodine receptors (RyR). In parallel, P. aeruginosa 3O-C-12-HSL disrupts junctions in human Caco-2 cells as evidenced by a reduction of the expression and distribution of ZO-3 and JAM-A. Using co-immunoprecipitation we also found an alteration in the binding of ZO-3 to JAM-A in protein complexes. Moreover, 3O-C-12-HSL-treatment resulted in tyrosine hyperphosphorylation of ZO-3 and JAM-A. On the contrary, serine and threonine residues of ZO-1 and JAM-A became less phosphorylated after exposition of 3O-C-12-HSL. The 3O-C-12-HSL-induced intracellular calcium signalling and alteration in the phosphorylation status of junction proteins furthermore correlated with changes in the association between JAM-A-ZO-3. The calcium inhibitors thapsigargin, xestospongin C. and dantrolene partly prevented the 3O-C-12-HSL-induced decreases in TER and increases in the paracellular flux of 10 kDa dextran. These findings clearly suggest that P. aeruginosa 3O-C-12-HSL can cause the loss of epithelial barrier function via calcium signalling and further alteration in the phosphorylation status of junction proteins; and that bacterial quorum sensing signals represent inter-kingdom signalling.

  • 4819.
    Vikström, Elena
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Medicinsk mikrobiologi. Linköpings universitet, Hälsouniversitetet.
    Bui, Lan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Konradsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Magnusson, Karl-Eric
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Medicinsk mikrobiologi. Linköpings universitet, Hälsouniversitetet.
    The junctional integrity of epithelial cells is modulated by Pseudomonas aeruginosa quorum sensing molecule through phosphorylation-dependent mechanisms2009Ingår i: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 315, nr 2, 313-326 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Pseudomonas aeruginosa, cell-cell Communication based on acyl-homoserine lactone (HSL) quorum sensing molecules is known to coordinate the production of virulence factors and biofilms by the bacterium. Incidentally, these bacterial signals can also modulate mammalian cell behaviour. We report that 3O-C-12-HSL can disrupt adherens junctions in human epithelial Caco-2 cells as evidenced by a reduction of the expression and distribution of E-cadherin and beta-catenin. Using co-immunoprecipitation we also found that P. aeruginosa 3O-C-12-HSL-treatment resulted in tyrosine hyperphosphorylation of E-cadherin, beta-catenin, occludin and ZO-1. Similarly, serine and threonine residues of E-cadherin and ZO-1 became more phosphorylated after 3O-C-12-HSL treatment. On the contrary, occludin and beta-catenin underwent dephosphorylation on serine and threonine residues after exposition of 3O-C-12-HSL. These changes in the phosphorylation state were paralleled by alteration in the Structure of junction complexes and increased paracellular permeability. Moreover, pre-treatment of the Caco-2 cells with protein phosphatase and kinase inhibitors prevented 3O-C-12-HSL-induced changes in paracellular permeability and interactions between occludin-ZO-1 and the E-cadherin-beta-catenin. These findings clearly suggest that an alteration in the phosphorylation status of junction proteins are involved in the changes in cell junction associations and enhanced paracellular permeability, and that bacterial signals are indeed sensed by the host cells.

  • 4820.
    Vikström, Simon
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Thuresson, Robin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Finite element analysis of winding sequence for cable drums2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This project concerns large cable drums made of steel. Cable drums are cylindrical structures used to transport different kinds of cables or wires. The ones in focus in this work are used to transport very stiff and heavy cables to offshore sites in the oil industry. To reduce weight in structures is always of great interest, and for cable drums, that are designed according to standards, there is much that can be improved.

    The aim of this project is to predict the loads acting on a drum during the winding of cables. This was accomplished by performing explicit finite element simulations of the winding sequence. Modeling and meshing were done using LS-PrePost and ANSA, and the winding was simulated using LS-DYNA. LS-PrePost was also used to analyze the results, together with mETApost.

    A number of simplifications and delimitations have been made in order to make the simulation possible within the time frame of the project. Simplified models of both the cable and the drum have been used. Winding velocities in real life are really slow, so in order to reduce simulation times, the winding velocity had to be increased while still avoiding dynamic effects. From this, contact forces between the drum and the cable could be obtained. The contact forces were investigated with respect to different friction values between the cable and the drum, for the cable itself and also for different cable stiffnesses.

    The results obtained from the simulations provide contact force distributions for different parts of the drum. Much fewer rows and layers of cable were winched than in real life, and it is therefore hard to see any clear trends in the obtained forces. However, one important result of the contact forces, is that a previously used assumption, namely that the pretension of the cable only applies loads to a small fraction of the drum, was a bit too conservative. According to the simulations it actually gets distributed over the whole drum.

    It is hard to draw any conclusions from the obtained contact forces, due to the small size of the simulations. The conclusion one can draw from this report, is that it is fully possible to use finite element tools to simulate the winding sequence of cable drums and this report presents a methodology on how to achieve this. LS-DYNA handles the contact definitions in an adequate way and is, according to the authors, a strong candidate for future work in this area. 

  • 4821.
    Villamil Giraldo, Ana Maria
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för cellbiologi. Linköpings universitet, Medicinska fakulteten.
    Fyrner, Timmy
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Wennmalm, Stefan
    Royal Institute Technology, Sweden.
    Parikh, Atul N.
    University of Calif Davis, CA 95616 USA; University of Calif Davis, CA 95616 USA.
    Öllinger, Karin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för cellbiologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Klinisk patologi och klinisk genetik.
    Ederth, Thomas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Spontaneous Vesiculation and pH-Induced Disassembly of a Lysosomotropic Detergent: Impacts on Lysosomotropism and Lysosomal Delivery2016Ingår i: LANGMUIR, ISSN 0743-7463, Vol. 32, nr 50, 13566-13575 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lysosomotropic detergents (LDs) selectively rupture lysosomal membranes through mechanisms that have yet to be characterized. A consensus view, currently, holds that LDs, which are weakly basic, diffuse across cellular membranes as monomers in an uncharged state, and via protonation in the acidic lysosomal compartment, they become trapped, accumulate, and subsequently solubilize the membrane and induce lysosomal membrane permeabilization. Here we demonstrate that the lysosomotropic detergent O-methyl-serine dodecylamide hydrochloride (MSDH) spontaneously assembles into vesicles at, and above, cytosolic pH, and that the vesicles disassemble as the pH reaches 6.4 or lower. The aggregation commences at concentrations below the range of those used in cell studies. Assembly and disassembly of the vesicles was studied via dynamic light scattering, zeta potential measurements, cryo-TEM, and fluorescence correlation spectroscopy and was found to be reversible via control of the pH. Aggregation of MSDH into closed vesicles under cytosolic conditions is at variance with the commonly held view of LD behavior, and we propose that endocytotic pathways should be considered as possible routes of LD entry into lysosomes. We further demonstrate that MSDH vesicles can be loaded with fluorophores via a solution transition from low to high pH, for subsequent release when the pH is lowered again. The ability to encapsulate molecular cargo into MSDH vesicles together with its ability to disaggregate at low pH and to permeabilize the lysosomal membrane presents an intriguing possibility to use MSDH as a delivery system.

  • 4822.
    Villani, Mattias
    Linköpings universitet, Institutionen för datavetenskap, Statistik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Tekniska fakulteten.
    Fractional Bayesian lag length inference in multivariate autoregressive processes2001Ingår i: Journal of Time Series Analysis, ISSN 0143-9782, E-ISSN 1467-9892, Vol. 22, nr 1, 67-86 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The posterior distribution of the number of lags in a multivariate autoregression is derived under an improper prior for the model parameters. The fractional Bayes approach is used to handle the indeterminacy in the model selection caused by the improper prior. An asymptotic equivalence between the fractional approach and the Schwarz Bayesian Criterion (SBC) is proved. Several priors and three loss functions are entertained in a simulation study which focuses on the choice of lag length. The fractional Bayes approach performs very well compared to the three most widely used information criteria, and it seems to be reasonably robust to changes in the prior distribution for the lag length, especially under the zero-one loss.

  • 4823.
    Villani, Mattias
    Linköpings universitet, Institutionen för datavetenskap, Statistik och maskininlärning. Linköpings universitet, Tekniska fakulteten. Linköping University.
    Sparse Partially Collapsed MCMC for Parallel Inference in Topic Models2017Ingår i: Journal of Computational And Graphical Statistics, ISSN 1061-8600, E-ISSN 1537-2715Artikel i tidskrift (Refereegranskat)
  • 4824.
    Vincelette, Erik
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Forecast: Beräkningar på affärs data2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    RemoteX Technologies AB är ett mjukvaruföretag i Stockholm. De utvecklar branschlösningar för ärendehantering och administration inom och mellan företrädandevis serviceföretag, ex. fastighetsförvaltning, VVS och byggbolag. Deras produkt heter RemoteX Applications och har sedan ett par månader tillbaka en möjlighet att kunna generera jobb utifrån fördefinierade scheman, vilket säkerställer att man kan hantera sina åtaganden i form av ronderingar och planerat underhåll. Deras kunder saknar dock en möjlighet att se vad den samlade mängden scheman kommer att generera framåt i tiden.Detta examensarbete syftar till att bygga en simulator för att beräkna hur mycket jobb som genereras och visa upp detta i ett webbgränssnitt. Simulatorn kommer skrivas i C# och hämta data från bakomliggande databas med LINQ to SQL och fokus ligger på att göra simuleringen så effektiv som möjligt med de tekniker som används. Webbgränssnittet skrivs i HTML5 och JavaScript och använder sig av färdiga JavaScript bibliotek för att visualisera prognosen som skapas av simulatorn.En slutpunkt har byggts i RemoteX REST API som tillhandahåller prognoser 6 månader framåt i tiden. Det går att ge parametrar till slutpunkten för att filtrera sin prognos ytterligare. En front-end som är en ny vy inom planning modulen har skapats och denna kommunicerar med slutpunkten. Denna front-end visualiserar prognosen i form av en agenda.

  • 4825.
    Vink, Josina
    et al.
    Service Research Center, Karlstad University, Sweden.
    Wetter-Edman, Katerina
    Örebro University.
    Rodrigues, Vanessa
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten.
    Designing Good(s)? Exploring the Politics of Social Design Processes2017Ingår i: Conference Proceedings of the Design Management Academy / [ed] Erik Bohemia, Cees de Bont and Lisbeth Svengren Holm, United Kingdom, 2017, Vol. 3, 961-977 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    As design shifts from designing objects to designing for social transformation, there is an increasing need to address political dimensions within the design process. This paper explores those dimensions by drawing insights from the field of Science and Technology Studies. In doing so, we bring forward issues of ontological politics within social design processes, including: the recognition of situated knowledges, the multiplicity of reality, and the performative nature of methods. The implications of these issues are investigated through the examination of two practice examples in which different methods were used to support reflection on politics in social design processes. This research highlights the need to be more critical of the “good” that social design processes are working towards and the methods used to support political awareness. It also opens-up a host of new questions about how to address political issues amid the complexity and multiplicity of reality.

  • 4826.
    Vinogradova, Julia
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    On the separability of signal and interference-plus-noise subspaces in blind pilot decontamination2016Ingår i: 41st IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, 3421-3425 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Consider a multicell multiuser MIMO (multiple-input multiple-output) system with a very large number of antennas at each base station (BS). The number of users in each cell is assumed to be fixed as the number of BS antennas grows large. Under certain conditions on the powers of the transmitting users, the signal eigenvalue spectrum is asymptotically separated from the interference-plus-noise spectrum as the number of BS antennas grows large. As it was observed in [1], this phenomenon allows to mitigate the pilot contamination problem. We provide the power limits for each user in the cell of interest above which such a separation occurs asymptotically. Unlike the approximative methods used in [1], we obtain these power limits by making use of the exact asymptotic characterizations of the interference-plus-noise spectrum. The results are based on the theory of small rank perturbations of large dimensional random matrices.

  • 4827.
    Vinogradova, Julia
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    DETECTION AND MITIGATION OF JAMMING ATTACKS IN MASSIVE MIMO SYSTEMS USING RANDOM MATRIX THEORY2016Ingår i: 2016 IEEE 17TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC), IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Consider the uplink of a single-cell multiuser MIMO system with a very large number of antennas, M, at the base station (BS) and K single-antenna users. A jamming device equipped with K-J antennas transmitting signals attempts to degrade the transmission between the users and the BS. In this paper, we propose a detection algorithm of the jamming attack as well as a method for its rejection. The proposed results are based on the application of results from random matrix theory. We assume that K and K-J are fixed as M converges to infinity while the coherence interval tau is assumed to be of the same order of magnitude as M

  • 4828.
    Visuttijai, Kittichate
    et al.
    University of Skovde, Sweden; University of Gothenburg, Sweden.
    Pettersson, Jennifer
    Department of Medical and Clinical Genetics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden .
    Mehrbani Azar, Yashar
    University of Skovde, Sweden.
    van den Bout, Iman
    University of Pretoria, South Africa.
    Orndal, Charlotte
    Sahlgrens University Hospital, Sweden.
    Marcickiewicz, Janusz
    Halland Hospital Varberg, Sweden.
    Nilsson, Staffan
    Chalmers, Sweden.
    Hörnquist, Michael
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Olsson, Bjorn
    University of Skovde, Sweden.
    Ejeskar, Katarina
    University of Skovde, Sweden.
    Behboudi, Afrouz
    University of Skovde, Sweden.
    Lowered Expression of Tumor Suppressor Candidate MYO1C Stimulates Cell Proliferation, Suppresses Cell Adhesion and Activates AKT2016Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 10, e0164063Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Myosin-1C (MYO1C) is a tumor suppressor candidate located in a region of recurrent losses distal to TP53. Myo1c can tightly and specifically bind to PIP2, the substrate of Phosphoinositide 3-kinase (PI3K), and to Rictor, suggesting a role for MYO1C in the PI3K pathway. This study was designed to examine MYO1C expression status in a panel of well-stratified endometrial carcinomas as well as to assess the biological significance of MYO1C as a tumor suppressor in vitro. We found a significant correlation between the tumor stage and lowered expression of MYO1C in endometrial carcinoma samples. In cell transfection experiments, we found a negative correlation between MYO1C expression and cell proliferation, and MYO1C silencing resulted in diminished cell migration and adhesion. Cells expressing excess of MYO1C had low basal level of phosphorylated protein kinase B (PKB, a. k. a. AKT) and cells with knocked down MYO1C expression showed a quicker phosphorylated AKT (pAKT) response in reaction to serum stimulation. Taken together the present study gives further evidence for tumor suppressor activity of MYO1C and suggests MYO1C mediates its tumor suppressor function through inhibition of PI3K pathway and its involvement in loss of contact inhibition.

  • 4829.
    Viter, Roman
    et al.
    University of Latvia, Latvia.
    Tereshchenko, Alla
    Odessa National II Mechnikov University, Ukraine.
    Smyntyna, Valentyn
    Odessa National II Mechnikov University, Ukraine.
    Ogorodniichuk, Julia
    National University of Life and Environm Science, Ukraine.
    Starodub, Nickolay
    National University of Life and Environm Science, Ukraine.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Khranovskyy, Volodymyr
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ramanavicius, Arunas
    Vilnius University, Lithuania.
    Toward development of optical biosensors based on photoluminescence of TiO2 nanoparticles for the detection of Salmonella2017Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 252, 95-102 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quality control of food and agriculture production is an inseparable part of human safety and wellbeing. Salmonella infections belong to one of the most monitored pathogens in the world, therefore advanced determination of this pathogen can decrease the risks of human diseases caused by this microorganism. In this research we introduce a novel optical immunosensor for determination of Salmonella typhimurium. The immunosensor is based on Titanium dioxide (TiO2) nanoparticles deposited on glass substrates (glass/TiO2)center dot TiO2 nanoparticles exhibit an intense photoluminescence (PL) in the visible range of spectrum at room temperature. The direct immobilization of antibodies (anti-S-Ab) against Salmonella antigens on the surface of glass/TiO2 has resulted in the formation of glass/TiO2/anti-S-Ab-based structure, which was characterized by increased PL intensity and IR-shifted position of the PL peak in comparison to the same characteristics of glass/TiO2-based structure. The changes of the PL intensity and peak positions after interaction of the immobilized anti-S-Ab with Salmonella antigens (Salmonella-Ag) were used as immunosensor signal, allowing sensitive and selective detection of Salmonella-Ag in a label-free configuration. The sensitivity of the reported optical immunosensor towards Salmonella-Ag is in the range from 10(3) to 10(5) cell/ml. Some aspects of the interaction between TiO2 and biological compounds have been discussed. This work opens up new possibilities for the development of optical label-free immunosensors suitable for fast, simple and efficient analysis of Salmonella infections. (C) 2017 Elsevier B.V. All rights reserved.

    Publikationen är tillgänglig i fulltext från 2019-05-26 12:55
  • 4830.
    Vockenhuber, C.
    et al.
    Swiss Federal Institute Technology, Switzerland.
    Arstila, K.
    University of Jyväskylä, Finland.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Julin, J.
    University of Jyvaskyla, Finland.
    Kettunen, H.
    University of Jyvaskyla, Finland.
    Laitinen, M.
    University of Jyvaskyla, Finland.
    Rossi, M.
    University of Jyvaskyla, Finland.
    Sajavaara, T.
    University of Jyvaskyla, Finland.
    Thoni, M.
    Swiss Federal Institute Technology, Switzerland.
    Whitlow, H. J.
    Haute Ecole Arc Ingn, Switzerland; University of Louisiana Lafayette, LA 70504 USA.
    Energy loss and straggling of MeV Si ions in gases2017Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 391, 20-26 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present measurements of energy loss and straggling of Si ions in gases. An energy range from 0.5 to 12 MeV/u was covered using the 6 MV EN tandem accelerator at ETH Zurich, Switzerland, and the K130 cyclotron accelerator facility at the University of Jyvaskyla, Finland. Our energy-loss data compare well with calculation based on the SRIM and PASS code. The new straggling measurements support a pronounced peak in He gas at around 4 MeV/u predicted by recent theoretical calculations. The straggling curve structure in the other gases (N-2, Ne, Ar, Kr) is relatively flat in the covered energy range. Although there is a general agreement between the straggling data and the theoretical calculations, the experimental uncertainties are too large to confirm or exclude the predicted weak multi-peak structure in the energy-loss straggling. (C) 2016 Elsevier B.V. All rights reserved.

  • 4831.
    Vodder Nielsen, Kraen
    et al.
    MAN Diesel and Turbo, Denmark; Technical University of Denmark, Denmark.
    Blanke, Mogens
    Technical University of Denmark, Denmark; Norwegian University of Science and Technology, Norway.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Vejlgaard-Laursen, Morten
    MAN Diesel and Turbo, Denmark.
    Adaptive feedforward control of exhaust recirculation in large diesel engines2017Ingår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 65, 26-35 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Environmental concern has led the International Maritime Organization to restrict NOx emissions from marine diesel engines. Exhaust gas recirculation (EGR) systems have been introduced in order to comply to the new standards. Traditional fixed-gain feedback methods are not able to control the EGR system adequately in engine loading transients so alternative methods are needed. This paper presents the design, convergence proofs and experimental validation of an adaptive feedforward controller that significantly improves the performance in loading transients. First the control concept is generalized to a class of first order Hammerstein systems with sensor delay and exponentially converging bounds of the control error are proven analytically. It is then shown how to apply the method to the EGR system of a two-stroke crosshead diesel engine. The controller is validated by closed loop simulation with a mean-value engine model, on an engine test bed and on a vessel operating at sea. A significant reduction of smoke formation during loading transients is observed both visually and with an opacity sensor. (C) 2017 Elsevier Ltd. All rights reserved.

  • 4832.
    Vodder Nielsen, Kraen
    et al.
    MAN Diesel and Turbo, Denmark; Technical University of Denmark, Denmark.
    Blanke, Mogens
    Technical University of Denmark, Denmark; Norwegian University of Science and Technology, Norway.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Vejlgaard-Laursen, Morten
    MAN Diesel and Turbo, Denmark.
    Control-Oriented Model of Molar Scavenge Oxygen Fraction for Exhaust Recirculation in Large Diesel Engines2017Ingår i: Journal of Dynamic Systems Measurement, and Control, ISSN 0022-0434, E-ISSN 1528-9028, Vol. 139, nr 2, 021007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Exhaust gas recirculation (EGR) systems have been introduced to large marine engines in order to reduce NOx formation. Adequate modeling for control design is one of the bottlenecks to design EGR control that also meets emission requirements during transient loading conditions. This paper therefore focuses on deriving and validating a mean-value model of a large two-stroke crosshead diesel engine with EGR. The model introduces a number of amendments and extensions to previous, complex models and shows in theory and practice that a simplified nonlinear model captures all essential dynamics that is needed for EGR control. Our approach is to isolate and reduce the gas composition part of the more complex models using nonlinear model reduction techniques. The result is a control-oriented model (COM) of the oxygen fraction in the scavenge manifold with three molar flows being inputs to the COM, and it is shown how these flows are estimated from signals that are commonly available. The COM is validated by first comparing the output to a simulation of the full model, then by comparing with measurement series from two engines. The control-oriented nonlinear model is shown to be able to replicate the behavior of the scavenge oxygen fraction well over the entire envelope of load and blower speed range that are relevant for EGR. The simplicity of the new model makes it suitable for observer and control design, which are essential steps to meet the emission requirements for marine diesel engines that take effect from 2016.

  • 4833.
    Vogels, Chantal B. F.
    et al.
    University of Wageningen and Research Centre, Netherlands.
    Möhlmann, Tim
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. University of Wageningen and Research Centre, Netherlands.
    Melsen, Diede
    University of Wageningen and Research Centre, Netherlands.
    Favia, Guido
    University of Camerino, Italy.
    Wennergren, Uno
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Koenraadt, Constantianus J. M.
    University of Wageningen and Research Centre, Netherlands.
    Latitudinal Diversity of Culex pipiens Biotypes and Hybrids in Farm, Peri-Urban, and Wetland Habitats in Europe2016Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 11, e0166959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the presence of Culex (Cx.) pipiens mosquitoes and circulation of West Nile virus (WNV), WNV outbreaks have so far not occurred in northern Europe. The species Cx. pipiens consists of two morphologically identical biotypes, pipiens and molestus, which can form hybrids. Until now, population dynamic studies of Cx. pipiens have not differentiated between biotypes and hybrids at the European scale, nor have they used comparative surveillance approaches. We therefore aimed to elucidate the relative abundance of Cx. pipiens biotypes and hybrids in three habitat types at different latitudes across Europe, using two different surveillance traps. BG-Sentinel and Mosquito-Magnet Liberty Plus traps were placed in three habitat types (farms, peri-urban, wetlands), in three European countries (Sweden, The Netherlands, Italy). Collected Cx. pipiens mosquitoes were identified to biotype with real-time PCR. Both trap types collected equal ratios of the biotypes and their hybrids. From northern to southern latitudes there was a significant decrease of pipiens and an increase of molestus. Habitat types influenced the relative ratios of biotypes and hybrids, but results were not consistent across latitudes. Our results emphasize the need to differentiate Cx. pipiens to the biotype level, especially for proper future WNV risk assessments for Europe.

  • 4834.
    Volkov, Anton
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Ionic and electronic transport in electrochemical and polymer based systems2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Electrochemical systems, which rely on coupled phenomena of the chemical change and electricity, have been utilized for development an interface between biological systems and conventional electronics.  The development and detailed understanding of the operation mechanism of such interfaces have a great importance to many fields within life science and conventional electronics. Conducting polymer materials are extensively used as a building block in various applications due to their ability to transduce chemical signal to electrical one and vice versa. The mechanism of the coupling between the mass and charge transfer in electrochemical systems, and particularly in conductive polymer based system, is highly complex and depends on various physical and chemical properties of the materials composing the system of interest.

    The aims of this thesis have been to study electrochemical systems including conductive polymer based systems and provide knowledge for future development of the devices, which can operate with both chemical and electrical signals. Within the thesis, we studied the operation mechanism of ion bipolar junction transistor (IBJT), which have been previously utilized to modulate delivery of charged molecules. We analysed the different operation modes of IBJT and transition between them on the basis of detailed concentration and potential profiles provided by the model.

    We also performed investigation of capacitive charging in conductive PEDOT:PSS polymer electrode. We demonstrated that capacitive charging of PEDOT:PSS electrode at the cyclic voltammetry, can be understood within a modified Nernst-Planck-Poisson formalism for two phase system in terms of the coupled ion-electron diffusion and migration without invoking the assumption of any redox reactions.

    Further, we studied electronic structure and optical properties of a self-doped p-type conducting polymer, which can polymerize itself along the stem of the plants. We performed ab initio calculations for this system in undoped, polaron and bipolaron electronic states. Comparison with experimental data confirmed the formation of undoped or bipolaron states in polymer film depending on applied biases.

    Finally, we performed simulation of the reduction-oxidation reaction at microband array electrodes. We showed that faradaic current density at microband array electrodes increases due to non-linear mass transport on the microscale compared to the corresponding macroscale systems.  The studied microband array electrode was used for developing a laccase-based microband biosensor. The biosensor revealed improved analytical performance, and was utilized for in situ phenol detection.

  • 4835.
    Volkov, Anton
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Singh, Sandeep Kumar
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Stavrinidou, Eleni
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Gabrielsson, Roger
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Franco Gonzalez, Felipe
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Cruce, Alex
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Simon, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Zozoulenko, Igor
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Spectroelectrochemistry and Nature of Charge Carriers in Self-Doped Conducting Polymer2017Ingår i: Advanced Electronic Materials, ISSN 2199-160X, Vol. 3, nr 8, 1700096Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A recently developed water-soluble self-doped sodium salt of bis[3,4-ethylenedioxythiophene] 3thiophene butyric acid (ETE-S) is electropolymerized and characterized by means of spectroelectrochemistry, electron paramagnetic resonance spectroscopy, and cyclic voltammetry, combined with the density functional theory (DFT) and time-dependent DFT calculations. The focus of the studies is to underline the nature of the charge carriers when the electrochemically polymerized ETE-S films undergo a reversible transition from reduced to electrically conductive oxidized states. Spectroelectrochemistry shows clear distinctions between absorption features from reduced and charged species. In the reduced state, the absorption spectrum of ETE-S electropolymerized film shows a peak that is attributed to HOMO. LUMO transition. As the oxidation level increases, this peak diminishes and the absorption of the film is dominated by spinless bipolaronic states with some admixture of polaronic states possessing a magnetic momentum. For fully oxidized samples, the bipolaronic states fully dominate, and the features in the absorption spectra are related to the drastic changes of the band structure, exhibiting a strong decrease of the band gap when a polymeric film undergoes oxidation.

    Publikationen är tillgänglig i fulltext från 2018-06-06 12:11
  • 4836.
    Volkov, Anton
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Wijeratne, Kosala
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Mitraka, Evangelia
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Ail, Ujwala
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Zhao, Dan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Tybrandt, Klas
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Wenzel Andreasen, Jens
    Technical University of Denmark, Denmark.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. Stellenbosch University, South Africa.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Zozoulenko, Igor
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Understanding the Capacitance of PEDOT:PSS2017Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 27, nr 28, 1700329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is the most studied and explored mixed ion-electron conducting polymer system. PEDOT: PSS is commonly included as an electroactive conductor in various organic devices, e.g., supercapacitors, displays, transistors, and energy-converters. In spite of its long-term use as a material for storage and transport of charges, the fundamentals of its bulk capacitance remain poorly understood. Generally, charge storage in supercapacitors is due to formation of electrical double layers or redox reactions, and it is widely accepted that PEDOT: PSS belongs to the latter category. Herein, experimental evidence and theoretical modeling results are reported that significantly depart from this commonly accepted picture. By applying a two-phase, 2D modeling approach it is demonstrated that the major contribution to the capacitance of the two-phase PEDOT: PSS originates from electrical double layers formed along the interfaces between nanoscaled PEDOT-rich and PSS-rich interconnected grains that comprises two phases of the bulk of PEDOT: PSS. This new insight paves a way for designing materials and devices, based on mixed ion-electron conductors, with improved performance.

    Publikationen är tillgänglig i fulltext från 2018-05-15 11:58
  • 4837.
    Volpi, Riccardo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Charge Transport Simulations for Organic Electronics: A Kinetic Monte Carlo Approach2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis we focus on the modelling and simulation of organic electronic devices, investigating their structural and electronic properties. Organic devices have attracted great interest for their innovative properties, but their functioning still represent a theoretical and technological challenge. They are composed by one or more organic materials depending on the particular application. The morphology of organic devices in the single phase or at the interface is known to strongly determine mobility and efficiency of the devices. The structural disorder is studied through molecular dynamics (MD) simulations. Marcus formula is used to calculate the hopping rate of the charge carriers and the model developed is tested by simulations in a Kinetic Monte Carlo scheme. The dependence of the transfer integrals on the relative molecular orientation is achieved through a weighted Mulliken formula or through a dimer projection approach using the semi-empirical Hartree Fock method ZINDO. Electrostatic effects, have been included through atomic charges and atomic polarizabilities, calculated at the B3LYP level of theory. The inclusion of electrostatic effects has been shown (through simulations in 4PV and C60) to be crucial to obtain a good qualitative agreement with experiments, for both mobility field and temperature dependence in the single phase. In particular the external reorganization energy, calculated through the polarization of the environment, has been shown to have a great impact on the conduction, shifting the inverse Marcus region and helping CT state separation at the interface (between C60 and anthracene).

  • 4838.
    Volpi, Riccardo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Beräkningsfysik. Linköpings universitet, Tekniska fakulteten.
    Modelling Charge Transport for Organic Solar Cells within Marcus Theory2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    With the technological advancement of modern society, electronic devices are getting progressively more integrated in our everyday lives. Their continuouslygrowing presence is generating numerous concerns about costs, efficiency and the environmental impact of the electronic waste. In this context, organic electronics is finding its way through the market, allowing for potentially low-cost, light, flexible, transparent and environmentally friendly electronics. Despite the numerous successes of organic electronics, the functioning of several categories of organic devices still represents a technological challenge, due to problems like low efficiencies and stabilities (degradation over time).

    Organic devices are composed by one or more organic materials depending on the particular application. The conformation and electronic structure of the organic molecules as well as their supramolecular arrangement in the single phase or at the interface are known to strongly a affect the mobility and/or the efficiency of the device. While there is consensus on the fundamental physics of organic devices, we still lack a detailed comprehensive theory able to fully explain experimental data. In this thesis we focus on trying to expand our knowledge of charge transport in organic materials through theoretical modelling and simulation of organic electronic devices. While the methodology developed is generally valid for any organic device, we will particularly focus on the case represented by organic photovoltaics.

    The morphology of the system is obtained by molecular dynamics simulations. Marcus theory is used to calculate the hopping rate of the charge carriers and subsequently study the possibility of free charge carriers production in an organic solar cell. The theory is then compared both with Kinetic Monte Carlo simulations and with experiments to identify the main pitfalls of the actual theory and ways to improve it. The Marcus rate between two molecules depends on the molecular orbital energies, the transfer integral between the two molecules and the reorganization energy. The orbital energies and the transfer integrals between two neighbouring molecules are obtained through quantum mechanical calculations in vacuum. Electrostatic effects of the environment are included through atomic charges and atomic polarizabilities, producing a correction both to the orbital energy and to the reorganization energy. We have studied several systems in the single phase (polyphenylene vinylene, C60, PC61BM) and at the interface between two organic materials (anthracene/C60, TQ1/PC71BM).

    We show how a combination of different methodologies can be used to obtain a realistic ab-initio model of organic devices taking into account environmental effects. This allows us to obtain qualitative agreement with experimental data of mobility in the single phase and to determine whether or not two materials are suitable to be used together in an organic solar cell.

  • 4839.
    Volpi, Riccardo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Kottravel, Sathish
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Norby, Morten Sten
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Denmark.
    Stafström, Sven
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Linares, Mathieu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Effect of Polarization on the Mobility of C60: A Kinetic Monte-Carlo Study2016Ingår i: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 12, nr 2, 812-824 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a study of mobility field and temperature dependence for C60 with Kinetic Monte-Carlo simulations. We propose a new scheme to take into account polarization effects in organic materials through atomic induced dipoles on nearby molecules. This leads to an energy correction for the single site energies and to an external reorganization happening after each hopping. The inclusion of polarization allows us to obtain a good agreement with experiments for both mobility field and temperature dependence.

  • 4840.
    Volpi, Riccardo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska fakulteten.
    Linares, Mathieu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska fakulteten.
    Study of the cold charge transfer state separation at the TQ1/PC71BM interface2017Ingår i: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 38, nr 14, 1039-1048 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Charge transfer (CT) state separation is one of the most critical processes in the functioning of an organic solar cell. In this article, we study a bilayer of TQ1 and PC71BM molecules presenting disorder at the interface, obtained by means of Molecular Dynamics. The study of the CT state splitting can be first analyzed through the CT state splitting diagram, introduced in a previous work. Through this analysis, we identify the possibility of CT state splitting within Marcus Theory in function of the electric field. Once the right range of electric fields has been identified, we perform Kinetic Monte Carlo simulations to estimate percentages and times for the CT state splitting and the free charge carriers collection. Statistical information extracted from these simulations allows us to highlight the importance of polarization and to test the limits of the predictions given by the CT state splitting diagram. (c) 2017 Wiley Periodicals, Inc.

  • 4841.
    Volpi, Riccardo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Nassau, Racine
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Linares, Mathieu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Tekniska fakulteten.
    Charge-transfer state dynamics at C60-anthracene interfaces: a kinetic Monte Carlo approach2015Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The morphology of organic interfaces plays an important role in charge-transfer (CT) state splitting, and therefore has a significant impact on the efficiency of organic solar cells. In this article, we use our kinetic Monte Carlo (KMC) method on molecular dynamics-simulated anthracene-C60 interfaces to study the relation between interface morphology and CT state splitting. These KMC simulations were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface. The results show that depending on the relative orientation of the anthracene and C60 molecules, CT state splitting shows different behavior with respect to both applied field strength and applied field angle. Different orientations may be better suited for different applications. The inclusion of polarization in our model is shown to  increase CT state splitting for both orientations studied.

  • 4842.
    Volpi, Riccardo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska fakulteten.
    Nassau, Racine
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Nörby, Morten
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. University of Southern Denmark, Denmark.
    Linares, Mathieu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska fakulteten.
    Theoretical Study of the Charge-Transfer State Separation within Marcus Theory: The C-60-Anthracene Case Study2016Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, nr 37, 24722-24736 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study, within Marcus theory, the possibility of the charge-transfer (CT) state splitting at organic interfaces and a subsequent transport of the free charge carriers to the electrodes. As a case study we analyze model anthracene-C-60 interfaces. Kinetic Monte Carlo (KMC) simulations on the cold CT state were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface to simulate the action of the electric field in a bulk heterojunction (BHJ) interface. The results show that the inclusion of polarization in our model increases CT state dissociation and charge collection. The effect of the electric field on CT state splitting and free charge carrier conduction is analyzed in detail with and without polarization. Also, depending on the relative orientation of the anthracene and C-60 molecules at the interface, CT state splitting shows different behavior with respect to both applied field strength and applied field angle. The importance of the hot CT in helping the charge carrier dissociation is also analyzed in our scheme.

  • 4843.
    Volpi, Riccardo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska fakulteten.
    Santos Camilo, Ana Claudia
    University of Brasilia, Brazil.
    da Silva Filho, Demetrio A.
    University of Brasilia, Brazil.
    Lopez Navarrete, Juan T.
    University of Malaga, Spain.
    Gomez-Lor, Berta
    CSIC, Spain.
    Carmen Ruiz Delgado, M.
    University of Malaga, Spain.
    Linares, Mathieu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska fakulteten.
    Modelling charge transport of discotic liquid-crystalline triindoles: the role of peripheral substitution2017Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, nr 35, 24202-24208 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have performed a multiscale approach to study the influence of peripheral substitution in the semiconducting properties of discotic liquid-crystalline triindoles. Charge carrier mobility as high as 1.4 cm(2) V-1 s(-1) was experimentally reported for triindoles substituted with alkynyl chains on the periphery (Gomez-Lor et al. Angew. Chem., Int. Ed., 2011, 50, 7399-7402). In this work, our goal is to get a deeper understanding of both the molecular electronic structure and microscopic factors affecting the charge transport properties in triindoles as a function of the spacer group connecting the central cores with the external alkyl chains (i.e., alkyne or phenyl spacers groups). To this end, we first perform Quantum Mechanical (QM) calculations to assess how the peripheral substitution affects the electronic structure and the internal reorganization energy. Secondly, boxes of stacked molecules were built and relaxed through molecular dynamics to obtain realistic structures. Conformational analysis and calculations of transfer integrals for closed neighbours were performed. Our results show that the insertion of ethynyl spacers between the central aromatic core and the flexible peripheral chains results in lower reorganization energies and enhanced intermolecular order within the stacks with a preferred cofacial 60 degrees staggered conformation, which would result in high charge-carrier mobilities in good agreement with the experimental data. This work allows a deeper understanding of charge carrier mobility in columnar phases, linking the structural order at the molecular level to the property of interest, i.e. the charge carrier mobility. We hope that this understanding will improve the design of systems at the supramolecular level aiming at obtaining a more defined conducting channel, higher mobility and smaller fluctuations within the column.

  • 4844.
    Voltes-Dorta, Augusto
    et al.
    University of Edinburgh, Scotland.
    Rodriguez Deniz, Hector
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Suau-Sanchez, Pere
    Cranfield University, England.
    Passenger recovery after an airport closure at tourist destinations: A case study of Palma de Mallorca airport2017Ingår i: TOURISM MANAGEMENT, ISSN 0261-5177, Vol. 59, 449-466 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the context of increased concern about the resilience of critical transport infrastructure to external events and the impact of such events on local tourism industries, this paper analyzes the ability of tourism-oriented airports to relocate departing passengers in the event of an unexpected airport closure. A case study of Palma de Mallorca airport is presented. Using an MIDT dataset on passenger itineraries in August 2014, several closure scenarios are simulated, and disrupted passengers are relocated to minimum-delay itineraries. Aggregate delays and relocation rates are used to assess the impact of each scenario, with a particular focus on UK and Germany markets. The results provide useful benchmarks for the development of policies aimed at minimizing the impact on stranded tourists, such as allowing for passenger connections, establishing a protocol for interline cooperation, and improving intermodal transfers. These measures will help mitigate the negative impacts on airline loyalty and destination image. (C) 2016 Elsevier Ltd. All rights reserved.

  • 4845.
    von Hacht, Karl-Johan
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Garden Monitoring with Embedded Systems2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In today’s modern society the process of handling crops in an accountable way withoutloss have become more and more important. By letting a gardener evaluate the progressof his plants from relevant data one can reduce these losses and increase effectiveness ofthe whole plantation. This work is about the construction of such a system composedfrom a developers perspective of three different platforms, from the start of data samplingwithin the context of gardening to and end user easily able to understand the data thentranslated. The first platform will be created from scratch with both hardware andsoftware, the next assembled from already finished hardware components and build withsimpler software. The last will essentially only be a software solution in an alreadyfinished hardware environment.

  • 4846.
    Voronov, Sergii
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Data-driven lead-acid battery lifetime prognostics2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    To efficiently transport goods by heavy-duty trucks, it is important that vehicles have a high degree of availability and in particular avoid becoming standing by the road unable to continue the transport mission. An unplanned stop by the road does not only cost due to the delay in delivery, but can also lead to a damaged cargo. High availability can be achieved by changing components frequently, but such an approach is expensive both due to the frequent visits to a workshop and also due to the component cost. Therefore, failure prognostics and flexible maintenance has significant potential in the automotive field for both manufacturers, commercial fleet owners, and private customers.

    In heavy-duty trucks, one cause of unplanned stops are failures in the electrical power system, and in particular the lead-acid starter battery. The main purpose of the battery is to power the starter motor to get the diesel engine running, but it is also used to, for example, power auxiliary units such as cabin heating and kitchen equipment. Detailed physical models of battery degradation is inherently difficult and requires, in addition to battery health sensing which is not available in the given study, detailed knowledge of battery chemistry and how degradation depends on the vehicle and battery usage profiles.

    The main aim of the given work is to predict the lifetime of lead-acid batteries using data-driven approaches. Main contributions in the thesis are: a) the choice of the Random Survival Forest method as the model for predicting a conditional reliability function which is used as the estimator of the battery lifetime, b) variable selection for better predictability of the model and c) variance estimation for the Random Survival Forest method.

    When developing a data-driven prognostic model and the number of available variables is large, variable selection is an important task, since including non-informative variables in the model have a negative impact on prognosis performance. Two features of the dataset has been identified, 1) there are few informative variables, and 2) highly correlated variables in the dataset. The main contribution is a novel method for identifying important variables, taking these two properties into account, using Random Survival Forests to estimate prognostics models. The result of the proposed method is compared to existing variable selection methods, and applied to a real-world automotive dataset.

    Confidence bands are introduced to the RSF model giving an opportunity for an engineer to observe the confidence of the model prediction. Some aspects of the confidence bands are considered: a) their asymptotic behavior and b) usefulness in the model selection. A problem of including time related variables is addressed in the thesis with arguments why it is a good choice not to add them into the model. Metrics for performance evaluation are suggested which show that the model can be used to find and optimize cost of the battery replacement.

  • 4847.
    Voronov, Sergii
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Jung, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Heavy-duty truck battery failure prognostics using random survival forests2016Ingår i: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2016, Vol. 49, nr 11, 562-569 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Predicting lead-acid battery failure is important for heavy-duty trucks to avoid unplanned stops by the road. There are large amount of data from trucks in operation, however, data is not closely related to battery health which makes battery prognostic challenging. A new method for identifying important variables for battery failure prognosis using random survival forests is proposed. Important variables are identified and the results of the proposed method are compared to existing variable selection methods. This approach is applied to generate a prognosis model for lead-acid battery failure in trucks and the results are analyzed. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 4848.
    Voronov, Sergii
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Jung, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Variable selection for heavy-duty vehicle battery failure prognostics using random survival forests2016Ingår i: PHME 2016 Proceedings of the Third European Conference of the Prognostics and Health Management Society 2016, Bilbao, Spain July 5–8, 2016 / [ed] Ioana Eballard and Anibal Bregon, 2016, 649-659 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Prognostics and health management is a useful tool for more flexible maintenance planning and increased system reliability. The application in this study is lead-acid battery failure prognosis for heavy-duty trucks which is important to avoid unplanned stops by the road. There are large amounts of data available, logged from trucks in operation. However, datais not closely related to battery health which makes battery prognostic challenging. When developing a data-driven prognostics model and the number of available variables is large,variable selection is an important task, since including non-informative variables in the model have a negative impact on prognosis performance. Two features of the dataset has been identified, 1) few informative variables, and 2) highly correlated variables in the dataset. The main contribution is a novel method for identifying important variables, taking these two properties into account, using Random Survival Forests to estimate prognostics models. The result of the proposed method is compared to existing variable selection methods,and applied to a real-world automotive dataset. Prognostic models with all and reduced set of variables are generated and differences between the model predictions are discussed, and favorable properties of the proposed approach are highlighted.

  • 4849.
    Vrotsou, Katerina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Fuchs, Georg
    Fraunhofer Institute IAIS, Sankt-Augustin, Germany.
    Andrienko, Natalia
    Fraunhofer Institute IAIS, Sankt-Augustin, Germany; City University London, London, UK.
    Andrienko, Gennady
    Fraunhofer Institute IAIS, Sankt-Augustin, Germany; City University London, London, UK.
    An Interactive Approach for Exploration of Flows Through Direction-Based Filtering2017Ingår i: Journal of Geovisualization and Spatial Analysis, ISSN 2509-8810, Vol. 1, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper is concerned with the representation and exploration of flows, defined as spatial interactions between geographic locations. Flows are challenging to display in a comprehensible manner due to the nature of the data, which are characterized by many crossings and overlaps leading to clutter. A number of different strategies have been suggested for addressing this problem, which commonly involve reducing the search space, aggregating the data or simplifying the representations often at the cost of information loss or distortion of spatial context. We propose an interactive approach for exploring large and highly connected networks of flows without distorting the geographical space and without losing the context overview in the process. The approach is based on a flow-specific interaction technique for filtering the data by direction, that enables an analyst to successively identify underlying spatial arrangement patterns. We illustrate our approach through exploring flows of tourists and locals in the Greater London area.

  • 4850.
    Vukajlovic Plestina, Jelena
    et al.
    Ecole Polytech Federal Lausanne, Switzerland.
    Derek, Vedran
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. Rudjer Boskovic Institute, Croatia.
    Francaviglia, Luca
    Ecole Polytech Federal Lausanne, Switzerland.
    Amaduzzi, Francesca
    Ecole Polytech Federal Lausanne, Switzerland.
    Potts, Heidi
    Ecole Polytech Federal Lausanne, Switzerland.
    Ivanda, Mile
    Rudjer Boskovic Institute, Croatia.
    Fontcuberta i Morral, Anna
    Ecole Polytech Federal Lausanne, Switzerland.
    Nanoporous silicon tubes: the role of geometry in nanostructure formation and application to light emitting diodes2017Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, nr 26, 265101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Obtaining light emission from silicon has been the holy grail of optoelectronics over the last few decades. One of the most common methods for obtaining light emission from silicon is to reduce it to a nanoscale structure, for example by producing porous silicon. Here, we present a method for the large-area fabrication of porous silicon microtubes by the stain etching of silicon micropillar arrays. We explain and model how the formation of the microtubes is influenced by the morphology of the substrate, especially the concave or convex character of the 3D features. Light emission is demonstrated at the micro- and nanoscale respectively by photo- and cathodoluminescence. Finally, we demonstrate a 0.55 cm(2) device that can work as a photodetector with 2.3% conversion efficiency under one sun illumination, and also as a broadband light emitting diode, illustrating the applicability of our results for optoelectronic applications.

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