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  • 45101. Wang, Yanan
    et al.
    Luo, Sjijian
    Liu, S
    Lu, Y
    Hansen, Preben
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Crafting Concrete as a Material for Enhancing Meaningful Interactions2017Ingår i: HCI International 2017, Springer , 2017Konferensbidrag (Refereegranskat)
  • 45102. Wang, Yanbo
    et al.
    Min, Qingfei
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Understanding the effects of trust and risk on individual behavior toward social media platforms: A meta-analysis of the empirical evidence2016Ingår i: Computers in human behavior, ISSN 0747-5632, E-ISSN 1873-7692, Vol. 56, s. 34-44Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Trust and risk have been theorized and empirically approved as the most influential factors affecting individual behavior toward social media platforms (SMPs). However, the evidence is scattered and the understanding of the effects is ambiguous:To address this problem, a rigorous and quantitative meta analysis was conducted to investigate the empirical evidence of 43 studies in information systems research between 2006 and 2014. The findings suggested that trust and risk both had significant effects on individual behavior toward SMPs but that trust had a stronger effect. Moderating effects of trust objects (community members vs. platforms) and platform types (virtual communities vs. social networking sites) were found. Surprisingly, culture was found to exert no moderating effect. This paper contributes more generalized knowledge to social media research literature to the theory with regard to the influence of trust and risk on individual behavior toward SMPs. The knowledge serves as the foundation for future research efforts in social media. Implications for practice are discussed.

  • 45103.
    Wang, Yanlu
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Functional Network Identification in Human Resting-state fMRI using Hierarchical Clustering by Time-Lagged Correlations.2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Utveckling av funktionell magnetresonans (fMRI, functional Magnetic Resonance Imaging) baserad på mätning av blodets syremättnad i hjärnan (Blood Oxygen Level Dependent, BOLD) har gett forskare nya metoder för kartläggning av hjärnans funktionella nätverk hos människor och djur. BOLD-tekniken mäter blodets syresättning som påverkas av neural aktivitet. Forskning angående metodutvecking har tidigare fokuserat på modeller för att minimera empiriska parametrar från användarsidan och optimera existerande algoritmer för att kunna applicera traditionella analysalgoritmer interaktivt. Relativt få har lagt fokus på den temporala aspekten av fMRI data.

    I denna undersökning designerar vi en ny modell som tar hänsyn till tidsfördröjningar som kan finnas i fMRI data. Modellen implementeras som en del av ett komplett analysprogram för hantering av fMRI data. För att hitta funktionella nätverk används en hierarkisk klusteralgorithm med ett distansmått baserat på maximal korrelation med avseende på olika tidsfördröjningar.

    Jämnfört med kluster från en distansmatris baserad på nollfördröjningskorrelation, kan vår metod generellt identifiera fler strukturer och funktionella nätverk som är konsistenta med etablerad literatur. Detta förstärker kausaliteten mellan korrelation i fMRI tidserier och funktionella nätverk. Vi drar slutsatsen att en modell som tar i hänsyn tidsfördröjningar kan innebära en förbättring av metodik för analys av fMRI data.

  • 45104.
    Wang, Ying
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    Lv, Weiyi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    Indoor video-based smoke detection2011Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Traditional smoke detection methods need sensors close to the source of the smoke. In order to avoid this disadvantage, this thesis presents a method for indoor video based smoke detection. In addition, it helps to improve the success rate of detection, as well as reducing the false detection rate of suspected smoke. This method consists of two parts. First, we create a Gaussian mixture model to detect smoke color pixels. Then, we use the smoke’s dynamic features to detect the smoke area and extract it from the area found in the first step, and in that way we can find the real smoke area. Our results show that this method can detect the smoke even before the flame appears. This will provide earlier warnings of fire, thus reducing economic losses and casualties.

  • 45105. Wang, Ying
    et al.
    Shaw, Philip
    Stockholm University.
    Transfer and universality: collocation use in advanced Chinese and Swedish learner English2008Ingår i: ICAME Journal/International Computer Archive of Modern English, ISSN 0801-5775, E-ISSN 1502-5462, ICAME Journal, Vol. 32, s. 201-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Research hitherto has tended to show that, like vocabulary errors, wrong collocations are often due to transfer from L1, and hence that greater typological difference from the target language leads to more serious collocational errors. We tested this hypothesis by comparing the collocational errors of Swedish and Chinese students. 100 university students from each environment wrote a short essay following the same prompt. The most common verbs were identified and then all occurrences of verb + noun collocations with have, do, take and make were investigated. Collocations were divided into free and restricted and then into target-like and non-target-like. The results showed that the two groups chose similar sets of noun collocates and made similar types and proportions of errors. This suggests that intralingual factors are as important as L1 transfer in this area.

  • 45106.
    Wang, You
    et al.
    Institute for Network Sciences and Cyberspace, Tsinghua University.
    Bi, Jun
    Institute for Network Sciences and Cyberspace, Tsinghua University.
    Vasilakos, Athanasios
    University of Western Macedonia.
    An Identifier-Based Approach to Internet Mobility:: A Survey2016Ingår i: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 30, nr 1, s. 72-79Artikel i tidskrift (Refereegranskat)
  • 45107.
    Wang, Yuan
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Matematiska och systemtekniska institutionen.
    Knowledge management from Theory to Practice: A road map for small and medium sized enterprises2007Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Nowadays, business activities become more and more complex; they entangle numerous aspects of knowledge: legal, financial, management, information technology, and so on. Knowledge Management, a still novel solution for most organization, aims boost and optimize the knowledge transfers in organization. The thesis is about should and how small and middle medium enterprises apply knowledge management. The author argues the content of knowledge management, and how implements those ideas into real business environment.

  • 45108.
    Wang, Yuanmao
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    A Space-Filling Technique for the Visualization of Planar st-graph2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Graphs currently attract an increasing number of computer scientists due to their widely adoptions in different areas. However, when people perform graph drawing, one of the most critical issues they need to concern is atheistics, i.e., to make the graph more suitable for human perceptions. In this work, we will aim at exploring one specific kind of graph ''planar st-graphs'' with space-filling technique in Info Vis area. We would cover edge crossing elimination, layer assignment, graph drawing algorithms, and new development of space-filling technique in planar st-graphs drawing etc. The final aim of this project is to develop a new algorithm to draw planar st-graphs based on a space-filling visualization approach with minimum edge crossings and maximum space usage.

  • 45109.
    Wang, Yue
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Matematiska och systemtekniska institutionen.
    Implementation of a Software Extraction Process2008Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [en]

    Software metrics are a useful tool for assessing software quality and for making predictions. But currently the interpretation of the measured values is based on personal experience and gut feeling. Not much information is available about thresholds and possible ranges of the metric values. In order to be able to define thresholds on which general recommendations could be based, quantitative data has to be obtain for allowing statistical evaluations and further investigations. So far the collection of test projects requires significant manual interaction for downloading and describing metadata.

    This thesis describes a process for automatically obtaining, storing and maintaining a large number of open software projects from SourceForge.NET [1]. The projects are stored in a local folder structure; the meta-data is stored in a local database. The process is automated as far as possible, repeatable, transparent, extendible and flexible.

  • 45110.
    Wang, Yue
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Web services for a Software Development Platform2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Web service is a sophisticated SOA technology with a lot of infrastructure. In this thesis we will get to understand the core aspects and advance futures of Web services and get a solution based on Sauer-Danfoss’s requirements. The critical requirement include to find appropriate Web services application server, to realize an automatic update process and to get a general overview of Web services technology. The challenges in this thesis is obviously in getting understand Web services architecture and programming in unfamiliar language using chosen Web services framework.

  • 45111.
    Wang, Yufeng
    et al.
    Nanjing University of Posts and Telecommunications, Nanjing.
    Bu, Yuanting
    Nanjing University of Posts and Telecommunications, Nanjing.
    Vasilakos, Athanasios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Jin, Qun
    Waseda University.
    Energy-Efficient Localization and Tracking on Smartphones: Design Principle and Solutions2016Ingår i: CFI '16: Proceedings of the 11th International Conference on Future Internet Technologies, New York: ACM Digital Library, 2016, s. 29-35Konferensbidrag (Refereegranskat)
    Abstract [en]

    In recent years, various location based services (LBS) have witnessed great development and are being prevalently used in our life. However, as the foundation of various LBS applications, localization consumes large energy of resource-constraint mobile terminals, especially on smartphones. This paper explicitly proposes three technical principles, substitution, adaption and collaboration to guide energy-efficient localization and tracking schemes on smartphones. Then several typical schemes in indoor or outdoor environments are respectively summarized and compared under the umbrella of those three principles. Moreover, the context-assisting techniques are also discussed to design energy-efficient LBS applications. Finally, the quantitative metrics to measure the tradeoff between energy and localization performance are summarized. The primary goal of this paper is to comprehensively classify and provide a summary on the sporadic localization schemes (with energy-efficiency as main concern), possible solutions and tradeoffs, and facilitate to develop and deploy the energy-efficient LBS applications.

  • 45112.
    Wang, Yufeng
    et al.
    Nanjing University of Posts and Telecommunications.
    Dai, Wei
    Nanjing University of Posts and Telecommunications.
    Zhang, Bo
    Nanjing University of Posts and Telecommunications.
    Ma, Jianhua
    Hosei University.
    Vasilakos, Athanasios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Word of Mouth Mobile Crowdsourcing: Increasing Awareness of Physical, Cyber, and Social Interactions2017Ingår i: IEEE MultiMedia, E-ISSN 1070-986X, Vol. 24, nr 4, s. 26-37Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By fully exploring various sensing capabilities and multiple wireless interfaces of mobile devices and integrating them with human power and intelligence, mobile crowdsourcing (MCS) is emerging as an effective paradigm for large-scale multimedia-related applications. However, most MCS schemes use a direct mode, in which crowdworkers passively or actively select tasks and contribute without interacting and collaborating with each other; such a mode can hamper some time-constrained crowdsourced tasks. This article explores a different approach: MCS based on word of mouth (WoM), in which crowdworkers, apart from executing tasks, exploit their mobile social networks and/or physical encounters to actively recruit other appropriate individuals to work on the task. The authors describe a WoM-based MCS architecture and typical applications, which they divide into Internet-scale and local scale. They then systematically summarize the main technical challenges, including crowdworker recruitment, incentive design, security and privacy, and data quality control, and they compare typical solutions. Finally, from a systems-level viewpoint, they discuss several practical issues that must be resolved. This article is part of a special issue on cybersecurity.

  • 45113.
    Wang, Yufeng
    et al.
    Nanjing University of Posts and Telecommunications, Nanjing.
    Vasilakos, Athanasios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Ma, Jianhua
    Hosei University, Tokyo.
    VPEF: A simple and effective incentive mechanism in community-based autonomous networks2015Ingår i: IEEE Transactions on Network and Service Management, ISSN 1932-4537, E-ISSN 1932-4537, Vol. 12, nr 1, s. 75-86, artikel-id 7029119Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper focuses on incentivizing cooperative behavior in community-based autonomous networking environments (like mobile social networks, etc.), in which through dynamically forming virtual and/or physical communities, users voluntarily participate in and contribute resources (or provide services) to the community while consuming. Specifically, we proposed a simple but effective EGT (Evolutionary Game Theory)-based mechanism, VPEF (Voluntary Principle and round-based Entry Fee), to drive the networking environment into cooperative. VPEF builds incentive mechanism as two simple system rules: The first is VP meaning that all behaviors are voluntarily conducted by users: Users voluntarily participate (after paying round-based entry fee), voluntarily contribute resource, and voluntarily punish other defectors (incurring extra cost to those so-called punishers); The second is EF meaning that an arbitrarily small round-based entry fee is set for each user who wants to participate in the community. We presented a generic analytical framework of evolutionary dynamics to model VPEF scheme, and theoretically proved that VPEF scheme's efficiency loss defined as the ratio of system time, in which no users will provide resource, is 4/(8 + M). M is the number of users in community-based collaborative system. Finally, the simulated results using content availability as an example verified our theoretical analysis

  • 45114. Wang, Z.
    et al.
    Esturo, J. M.
    Seidel, H. -P
    Weinkauf, Tino
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsvetenskap och beräkningsteknik (CST). Max Planck Institute for Informatics, Germany .
    Stream Line-Based Pattern Search in Flows2016Ingår i: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a method that allows users to define flow features in form of patterns represented as sparse sets of stream line segments. Our approach finds similar occurrences in the same or other time steps. Related approaches define patterns using dense, local stencils or support only single segments. Our patterns are defined sparsely and can have a significant extent, i.e., they are integration-based and not local. This allows for a greater flexibility in defining features of interest. Similarity is measured using intrinsic curve properties only, which enables invariance to location, orientation, and scale. Our method starts with splitting stream lines using globally consistent segmentation criteria. It strives to maintain the visually apparent features of the flow as a collection of stream line segments. Most importantly, it provides similar segmentations for similar flow structures. For user-defined patterns of curve segments, our algorithm finds similar ones that are invariant to similarity transformations. We showcase the utility of our method using different 2D and 3D flow fields.

  • 45115. Wang, Z.
    et al.
    Esturo, J. Martinez
    Seidel, H. -P
    Weinkauf, Tino
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsvetenskap och beräkningsteknik (CST). Max Planck Institute for Informatics.
    Pattern Search in Flows based on Similarity of Stream Line Segments2014Ingår i: Proc. Vision, Modeling and Visualization, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a method that allows users to define flow features in form of patterns represented as sparse sets of stream line segments. Our approach finds similar occurrences in the same or other time steps. Related approaches define patterns using dense, local stencils or support only single segments. Our patterns are defined sparsely and can have a significant extent, i.e., they are integration-based and not local. This allows for a greater flexibility in defining features of interest. Similarity is measured using intrinsic curve properties only, which enables invariance to location, orientation, and scale. Our method starts with splitting stream lines using globally-consistent segmentation criteria. It strives to maintain the visually apparent features of the flow as a collection of stream line segments. Most importantly, it provides similar segmentations for similar flow structures. For user-defined patterns of curve segments, our algorithm finds similar ones that are invariant to similarity transformations. We showcase the utility of our method using different 2D and 3D flow fields.

  • 45116.
    Wang, Z.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Junesand, Carl
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Metaferia, Wondwosen
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Hu, C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    InP lateral overgrowth technology for silicon photonics2010Ingår i: Optics InfoBase Conference Papers, Optical Society of America (OSA) , 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Epitaxial Lateral Overgrowth has been proposed as a key technology of a novel hybrid integration platform for active silicon photonic components. By fabricating silicon oxide mask on top of a thin InP seed layer, we can use the so called defect necking effect to filter out the threading dislocations propagating from the seed layer. By optimizing the process, thin dislocation free InP layers have been successfully obtained on top of silicon wafer. The obtained characterization results show that the grown InP layer has very high quality, which can be used as the base for further process of active photonic components on top of silicon.

  • 45117. Wang, Z.
    et al.
    Seidel, H. -P
    Weinkauf, Tino
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsvetenskap och beräkningsteknik (CST).
    Hierarchical Hashing for Pattern Search in 3D Vector Fields2015Ingår i: Proc. Vision, Modeling and Visualization, 2015, s. 1-48Konferensbidrag (Refereegranskat)
    Abstract [en]

    The expressiveness of many visualization methods for 3D vector fields is often limited by occlusion, i.e., interesting flow patterns hide each other or are hidden by laminar flow. Automatic detection of patterns in 3D vector fields has gained attention recently, since it allows to highlight user-defined patterns and separate the wheat from the chaff. We propose an algorithm which is able to detect 3D flow patterns of arbitrary extent in a robust manner. We encode the local flow behavior in scale space using a sequence of hierarchical base descriptors, which are pre-computed and hashed into a number of hash tables. This ensures a fast fetching of similar occurrences in the flow and requires only a constant number of table lookups. In contrast to many previous approaches, our method supports patterns of arbitrary shape and extent. We achieve this by assembling these patterns using several smaller spheres. The results are independent of translation, rotation, and scaling. Our experiments show that our approach encompasses the state of the art with respect to both the computational costs and the accuracy.

  • 45118. Wang, Z.
    et al.
    Seidel, H. -P
    Weinkauf, Tino
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsvetenskap och beräkningsteknik (CST).
    Multi-field Pattern Matching based on Sparse Feature Sampling2016Ingår i: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 22, nr 1, s. 807-816Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an approach to pattern matching in 3D multi-field scalar data. Existing pattern matching algorithms work on single scalar or vector fields only, yet many numerical simulations output multi-field data where only a joint analysis of multiple fields describes the underlying phenomenon fully. Our method takes this into account by bundling information from multiple fields into the description of a pattern. First, we extract a sparse set of features for each 3D scalar field using the 3D SIFT algorithm (Scale-Invariant Feature Transform). This allows for a memory-saving description of prominent features in the data with invariance to translation, rotation, and scaling. Second, the user defines a pattern as a set of SIFT features in multiple fields by e.g. brushing a region of interest. Third, we locate and rank matching patterns in the entire data set. Experiments show that our algorithm is efficient in terms of required memory and computational efforts.

  • 45119.
    Wang, Zhao
    et al.
    KTH.
    Xiao, Ming
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Poor, H. V.
    Secrecy degrees of freedom of wireless X networks using artificial noise alignment2015Ingår i: IEEE International Symposium on Information Theory - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 616-620Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of transmitting confidential messages in the M × K wireless X network is considered, in which each transmitter intends to send one confidential message to every receiver. In particular, the secrecy degrees of freedom (SDOF) of the considered network are studied by an artificial noise alignment (ANA) approach, which integrates interference alignment and artificial noise transmission. At first, an SDOF upper bound is derived for the M × K X network with confidential messages (XNCM) to be equation. By proposing an ANA approach, it is shown that the SDOF upper bound is tight when either K = 2 or M = 2 for the considered XNCM with time/frequency varying channels. For K, M ≥ 3, it is shown that an SDOF of equation can be achieved, even when an external eavesdropper appears. The key idea of the proposed scheme is to inject artificial noise into the network, which can be aligned in the interference space at receivers for confidentiality. The proposed method provides a linear approach for secure interference alignment.

  • 45120.
    Wang, Zhe
    Örebro universitet, Handelshögskolan vid Örebro universitet.
    Communiation between Citizens and Government: An Investigation of Citizen´s Attitude in China2008Självständigt arbete på avancerad nivå (masterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 45121.
    Wang, Zhe
    Örebro universitet, Handelshögskolan vid Örebro universitet.
    Developing the evaluation model of government website: an investigation of "Annual Report on China´s Government Website"2007Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 45122.
    Wang, Zhiping
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Capacity-constrained production-inventory systems: modelling and analysis in both a traditional and an e-business context2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis addresses issues in production-inventory systems in both a traditional and an e-business context, with an emphasis on capacity considerations. The general aim of the thesis is to model capacity-constrained production-inventory systems and thereby provide theoretical frameworks for control as well as design of these systems.

    The research has been conducted in two different contexts. In the traditional context, an extensive survey of the literature on capacity-constrained production-inventory systems is first presented. Production-inventory systems with capacity limitations are then modelled using the Laplace transform and input-output analysis for deterministic and stochastic demand situations, respectively. In the formulation of the model for the deterministic demand situations, the focus is on the way in which the fundamental balance equations for inventory and backlogs need to be modified. In the formulation for stochastic demand situations, the model extends previous theory in the direction of capacity considerations combined with uncertainty in external demand. The results of the modelling and analysis in the traditional context contribute to the development of a theoretical background for production-inventory system control applying the Laplace transform approach and input-output analysis.

    In the e-business context, those aspects which are affected by e-business based customer ordering systems, and hence influence production-inventory systems, are studied. A mathematical model based on the assumption of a simple e-business model of direct sales channels is presented. Since e-business significantly facilitates customisation, models of two different production systems which consider customisation are provided. The production-inventory systems are then developed into an extended system where customers are included. For this system, a multiple objective formulation is obtained, in view of the importance of customers. The results of the modelling and analysis in the ebusiness context contribute insights and perspectives on ways to design and control ebusiness influenced production - inventory systems.

  • 45123.
    Wang, Zhiping
    Linköpings universitet, Institutionen för produktionsekonomi. Linköpings universitet, Tekniska högskolan.
    Capacity-constrained production-inventory systems: using Laplace transforms and input-output analysis2001Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This work is concerned with multi-level, multi-stage capacity-constrained production-inventory problems. The aim is to provide a contribution to a theoretical background for Material Requirements Planning (MRP) using the Laplace Transform approach and Input-Output Analysis.

    In an extensive literature survey, we summarise the work on the capacitated lot-sizing problem (CLSP) within both the deterministic and the stochastic environments. Certain aspects related to model formulation are highlighted. It was found that methods for solving this class of problems have been concentrating on heuristics and mathematical programming.

    Unlike classic methods, this thesis formulates models for capacityconstrained production-inventory systems using the Laplace transform and input-output analysis. As a first step to incorporate capacity limitations into previous theory, we introduce alternative formulations of extensions to MRP theory in order to incorporate capacity constraints. We focus our attention on the way in which the fundamental balance equations for inventory and backlogs need to be modified.

    Then we develop a stochastic model, in which external demand for end items is assumed to be unknown. Unlike the classic total cost objective function, the Net Present Value is used as the objective function. As an intermediate result, the backlog function for a discrete time demand process is derived. Besides, an extension of the model is presented in which both capacity and demand are considered along a continuous time scale, without time buckets.

    Numerical examples are provided to explain the theory both in the deterministic and in the stochastic situations.

  • 45124.
    Wang, Zhiping
    et al.
    Linköpings universitet, Institutionen för datavetenskap, EISLAB - Economic Information Systems. Linköpings universitet, Tekniska högskolan.
    Rapp, Birger
    Linköpings universitet, Institutionen för datavetenskap, EISLAB - Economic Information Systems. Linköpings universitet, Tekniska högskolan.
    Modelling customisation in production-inventory systems2004Ingår i: Proceedings of the 2nd World POM Conference, 2004Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    With the implementation of e-business, customisation is increasingly becoming a competitive strategy for manufacturing companies. From both theoretical and practical perspectives, however, there is limited knowledge about the influence of customisation on the operational level. In this paper, we model two different production systems: the single machine production system with a cyclical production policy and the serial production system with a decoupling point, where customisation is considered. These models provide a theoretical framework for designing a production-inventory system in practice. As for the solutions yielded by the models, the most interesting finding is that capacity requirement increases with customer order lead-time in the serial production system in one of the cases’ solutions, which is counterintuitive. This result is due to the complexity of the relationship between the variables of decoupling point position and capacity requirements and the parameter of customer order leadtime in the mathematical formulation.

  • 45125.
    Wanganga, George
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Effective Requirements Management2004Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    In many smaller companies, requirements management is a daunting challenge. Smaller groups mean fewer resources, and many organizations focus their efforts on design, development and testing not on managing requirements. Some small organizations may perceive requirements management as an activity only for large organizations that have complex products and large staffs to support the effort. Poor and uncontrolled requirement engineering processes yield low quality, highly expensive software products. Obviously, customers are highly dissatisfied with such systems. One of the most critical requirement engineering processes that grossly contribute to this misnomer is lack of “effective requirements management” Information Technology Associates (ITA) has had many challenges resulting from some poor and uncontrolled requirements engineering processes. Lack of effective requirements traceability has also had its share in plaguing ITA in software development activities. ITA started small and so it handled its requirements documentation manually as it only dealt with few customer requirements. Time has seen the company expand, and manual handling of customer requirement became difficult. This master thesis therefore aims to investigate: ♦ The state-of-practice, regarding requirements engineering and requirements management within a medium-sized software development company. ♦ How to successfully implement effective requirement management process within the ITA Company. ♦ How to successfully migrate ITA Company into this RE process while ensuring minimum hassles.

  • 45126.
    Wangel, Josefin
    et al.
    Designing Social Innovation.
    Mazé, Ramia
    RISE, Swedish ICT, Interactive Institute. Design Research Unit.
    de Jong, Annelise
    Designing Social Innovation.
    Höjer, Mattias
    Designing Social Innovation.
    Backcasting and Design for Sustainable Social Practices2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Policy and design are fundamentally about the future – about changing the course of individuals and communities, setting patterns for new actions and, in the case of sustainable development, steering toward preferred futures. This paper sets out to explore the theoretical and methodological basis for creating, understanding and representing sustainable futures in terms of altered practices of consumption, through the integration of futures studies, design epistemology and social practice theory. As an introduction to this exploration, we present these three perspectives and generate questions for discussion and future work.

  • 45127. Wangler, A
    et al.
    Ekenberg, Love
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Johannesson, P
    Bridging High-Level Enterprise Models to Implementation-Oriented Models: Proceedings of SoMet2003Konferensbidrag (Övrigt vetenskapligt)
  • 45128. Wangler, B.
    et al.
    Andersson, Birger
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Data- och systemvetenskap, DSV.
    Bergholtz, Maria
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Data- och systemvetenskap, DSV.
    Johannesson, Paul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Data- och systemvetenskap, DSV.
    Conceptual models and levels of modeling2006Ingår i: 5th International Conference on Business Informatics Research, BIR 2006, International Conference on Business Informatics Research , 2006, s. 9-16Konferensbidrag (Refereegranskat)
    Abstract [en]

    Conceptual modeling is a powerful tool for describing, defining and understanding some world under consideration. To properly understand conceptual modeling one can turn conceptual modeling on itself and develop meta models. In this paper we inquiry into the relation between conceptual models and meta models. We identify and discuss some issues in modeling and in meta modeling that have puzzled our minds in recent work with ontologies.

  • 45129. Wanjira, Judith
    et al.
    Hallberg, David
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Systems for improved social (e-)care provision2011Konferensbidrag (Övrigt vetenskapligt)
  • 45130.
    WANNERÖ AVRAMIDOU, LINDA
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    RENNEMARK, MARIA
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Att levandegöra ett museum: med hjälp av medieteknik2017Självständigt arbete på grundnivå (kandidatexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I detta kandidatarbete undersöker vi hur man med medieteknik kan levandegöra och väcka liv i ett museum där utvecklingen idag nästintill står still. Barn och ungdomar har en bristfällig interaktion med museet idag och därför blev vår utmaning att se till hur vi, med deras hjälp, kan väcka deras intresse och med medietekniken som verktyg knyta nya och starkare relationer däremellan. Museet har en begränsad budget vilket utmanade oss att hitta en lösning som är hållbar och klarar att överleva på sikt utan pengar som stöd. Vi undersöker vägar att ta oss fram genom design workshops där vi skapar tillsammans med barnen och ungdomarna för att skapa ett “happy place”. Vi undersöker teknik, såsom Parallax Scrolling, att arbeta med och som kan vara passande för att skapa nytt liv. Vi ger utrymme för ett nytt sätt att tänka och idéer som kan gynna i flera led. Nyckelord: Barnens museum, medieteknik, webbplats, designworkshop, parallax scrolling.

  • 45131.
    Wanngren, Niklas
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Dynamove – Multi agent navigation using velocity obstacles.2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med detta examensarbete är att undersöka lokal navigering och undanmanövrering i virtuella världar. Målet är att konstruera en algoritm som förbättrar några av de problem med till exempel oscilleringar som finns idag. Detta har gjorts med hjälp av en egenkonstruerad testmiljö och den metod som examensarbetet i huvudsak har riktat in sig på är Velocity obstacles samt dess iterationer. Olika teorier och angreppssätt har testats och utvärderats för att på så sätt få ett så bra resultat som möjligt med de målen som satts upp. Arbetet har gjort på och i samarbete med Avalanche Studios.

    Resultatet av examensarbetet är en algoritm som heter Dynamove. Dynamove är en kombination av befintliga metoder samt nya angreppssätt inom de områden som navigering och undanmanävrering med Velocity obstacles består av. De som skiljer Dynamove från tidigare algoritmer är metoderna som används för placering av Velocity obstacles? samt uträkning och val av ny hastighet. Med dessa förändringar lyckades Dynamove få ett väsentligt minskat kollisionsantal och endast en tredjedel så hög oscilleringsfrekvens. Detta gör Dynamove till ett bättre alternativ än andra algoritmer.

  • 45132.
    Waora, Dushant Singh
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    WordHunch: Server kommunikation och Datahantering i MySQL och Java2015Självständigt arbete på avancerad nivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Målet med detta projekt var att utforma en kommunikation och databassystem för ett multiplayer ordbaserat spel åt Tweakers HB. Tweakers HB är ett produktbolag som utvecklar mobila applikationer där Wordhunch är en utav deras produkter. Systemet är en webbaserad API som stöds av en databas system för att kunna hantera olika aspekter av ett multiplayer ordbaserat spel. API: et kommer att användas av en Android applikation som utvecklas av andra utvecklare på Tweakers HB. Kommunikationssystemet har tagits fram med Extreme Programming samt testdriven utveckling. Utvecklingen skedde med välkända och beprövade metoder för att kunna säkerställa att ett system med hög kvalitet levereras. Båda system utnyttjar gamla och vältestade verktyg så som MySQL för databashantering medan REST-arkitektur används för kommunikationssystem. I slutet av utvecklingen uppfylldes alla ställda krav. System klarar av prestandakravet enligt de tester som utfördes. Under testning har flera komplikationer uppstått som inte var kända under utvecklingen eller före som t.ex. ta fram det korrekta ord när ett felstavat ord har skickats in.

  • 45133.
    Waqar, Hafiz Umer
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Comparison between .NET and Java EEImplementation of Cash & Bank System2013Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The demands of software engineering increases with everyday passed and every organization

    shows interest to work on daily routine work in the computerized system to improve efficiency

    and accuracy of data. Most of organization demands different kinds of computerized software

    solutions that developed in modern technologies. There are different software development

    technologies that is getting popular with the passage of time and provide high quality product to

    their user. It is not an easy to decide which technology choose to develop computerized system

    where most software falls. The primary purpose of thesis is to compare two different modern

    software development technologies by develop an application with same functional

    requirements. This thesis report will help to user for selection of software development

    technology.

    Cash and bank financial application is choose to develop using .NET and Java Enterprise

    Edition. Microsoft Visual Studio development environment is used for .NET development and

    NetBeans IDE is used for Java Enterprise Edition application. .NET framework contains many

    language that are interrelated with each other like C#, VB, J#, C++ and F#. Cash and bank

    application is develop in C# and Java programming languages and persistence storage of data is

    design in Microsoft SQL Server. Cash and bank application is develop with three tier

    architecture and layer approach. The syntax of .NET and Java Enterprise Edition is quite similar

    but procedure to establish connection, data retrieval and handling the data in different way. NET

    platform provide built in libraries, components and efficient user controls that helps for fast

    development in short period of time.

  • 45134.
    Waqas, Ahmad
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Kamal, Fawad
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Modeling Patterns in Software Design2007Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Software patterns provide solutions to recurring design problems, provide a way to reason about the quality attributes, and support stakeholders in understanding the system. Naturally, the use of software patterns emerges from the requirements of the software. Use Cases have been a traditional and authentic approach to document these requirements. We propose a way to mine these patterns by sing use cases and advocate their significance in saving resources and time. For this purpose, an open-source system is discussed and four design patterns are mined with the help of use cases elicited from the documentation and literature available for the selected system. Patterns mined in this system are then document in GOF format.Furthermore, the consequences of few patterns on quality attributes are studied and an additional design pattern is proposed to improve the quality of the system.

  • 45135.
    Waqas, Ahmad
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Kamal, Fawad
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Modeling Patterns in Software Design2007Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Software patterns provide solutions to recurring design problems, provide a way to reason about the quality attributes, and support stakeholders in understanding the system. Naturally, the use of software patterns emerges from the requirements of the software. Use Cases have been a traditional and authentic approach to document these requirements. We propose a way to mine these patterns by sing use cases and advocate their significance in saving resources and time. For this purpose, an open-source system is discussed and four design patterns are mined with the help of use cases elicited from the documentation and literature available for the selected system. Patterns mined in this system are then document in GOF format.Furthermore, the consequences of few patterns on quality attributes are studied and an additional design pattern is proposed to improve the quality of the system.

  • 45136.
    Ward, Mattias
    et al.
    Örebro universitet, Handelshögskolan vid Örebro universitet.
    Pettersson, Magnus
    Örebro universitet, Handelshögskolan vid Örebro universitet.
    Cloud Computing: Vilka svenska företag lämpar det sig för?2011Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Cloud computing spås av många som framtiden för IT och innebär att man över internet hyr datorkraft och programvara istället för att köpa in datorer och mjukvarulicenser till företaget. Då mycket av den forskning som finns syftar till främst amerikansk kontext har den här undersökningen genomförts med fokus på svenska företag. Den här undersökningen syftar till att ta reda på vilka typer av företag i Sverige som har störst respektive minst nytta av cloud computing och har genomförts med hjälp av kvalitativa intervjuer med fyra svenska IT-företag. I undersökningen framkommer det att det kan vara svårt att hitta en specifik bransch eller storlek av företag som är speciellt väl lämpat för att använda sig av cloud computing, det gäller snarare att utifrån en specifik verksamhet undersöka hur man på bästa sätt kan dra nytta av cloud computing. Däremot finns vissa förutsättningar som skiljer olika företagstyper åt när det gäller cloud computing som presenteras i uppsatsen.

  • 45137. Ward, N. G.
    et al.
    Werner, S. D.
    Novick, D. G.
    Shriberg, E. E.
    Oertel, Catharine
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Morency, L. -P
    Kawahara, T.
    The similar segments in social speech task2013Ingår i: CEUR Workshop Proceedings, 2013, Vol. 1043Konferensbidrag (Refereegranskat)
    Abstract [en]

    Similar Segments in Social Speech was one of the Brave New Tasks at MediaEval 2013. The task involves finding segments similar to a query segment, in a multimedia collection of informal, unstructured dialogs among members of a small community.

  • 45138. Warhurst, Samantha
    et al.
    Madill, Catherine
    McCabe, Patricia
    Ternström, Sten
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Musikakustik.
    Yiu, Edwin
    Heard, Robert
    Perceptual and Acoustic Analyses of Good Voice Quality in Male Radio Performers2017Ingår i: Journal of Voice, ISSN 0892-1997, E-ISSN 1873-4588, Vol. 31, nr 2, s. 259.e1-259.e12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives

    Good voice quality is an asset to professional voice users, including radio performers. We examined whether (1) voices could be reliably categorized as good for the radio and (2) these categories could be predicted using acoustic measures.

    Participants and Methods

    Male radio performers (n = 24) and age-matched male controls performed “The Rainbow Passage” as if presenting on the radio. Voice samples were rated using a three-stage paired-comparison paradigm by 51 naive listeners and perceptual categories were identified (Study 1), and then analyzed for fundamental frequency, long-term average spectrum, cepstral peak prominence, and pause or spoken-phrase duration (Study 2).

    Results

    Study 1: Good inter-judge reliability was found for perceptual judgments of the best 15 voices (good for radio category, 14/15 = radio performers), but agreement on the remaining 33 voices (unranked category) was poor. Study 2: Discriminant function analyses showed that the SD standard deviation of sounded portion duration, equivalent sound level, and smoothed cepstral peak prominence predicted membership of categories with moderate accuracy (R2 = 0.328).

    Conclusions

    Radio performers are heterogeneous for voice quality; good voice quality was judged reliably in only 14 out of 24 radio performers. Current acoustic analyses detected some of the relevant signal properties that were salient in these judgments. More refined perceptual analysis and the use of other perceptual methods might provide more information on the complex nature of judging good voices.

  • 45139. Warmer, Cos
    et al.
    Kamphuis, René
    Mellstrand, Per
    Gustavsson, Rune
    Distributed Control in Electricity Infrastructures2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Different driving forces push the electricity production towards decentralization. As a result, the current electricity infrastructure is expected to evolve into a network of networks, in which all system parts communicate with each other and influence each other. Multiagent systems and electronic markets form an appropriate technology needed for control and coordination tasks in the future electricity network. We present the PowerMatcher, a market-based control concept for supply and demand matching (SDM) in electricity networks. In a simulation study we show the ability of this approach to raise the simultaneousness of electricity production and consumption within (local) control clusters. This control concept can be applied in different business cases like reduction of imbalance costs in commercial portfolios or virtual power plant operation of distributed generators. Two PowerMatcher-based field test configurations are described, one currently in operation, one currently under construction

  • 45140.
    Warne, Markus
    KTH, Skolan för datavetenskap och kommunikation (CSC), Medieteknik och interaktionsdesign, MID.
    Photogrammetric software as an alternative to 3D laser scanning in an amateur environment2015Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Photogrammetric software today is at a level where it is accessible to the mainstream public and without larger effort is able to reconstruct digital 3D models from photographic input.  This thesis investigates the performance of photogrammetricly reconstructed models and evaluates them by comparing the results to their corresponding reconstructed models from a 3D laser scanner with a focus on smaller objects in an amateur environment. The evaluation is performed on four different objects, which are all individually compared to their scanned counterpart. They are compared both with a subjective judgment of quality and by numerically measuring the point-to-point distance on the models. From the results conclusions are drawn that the methods can produce similar results albeit there are many performance factors discovered for a good reconstructions with photogrammetry. The properties of the physical object and the quality of the visual input data stand out as the most important factors.

  • 45141.
    Warnhag, Anton
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    WOM awareness: A quantitative analysis of word of mouth marketing’s effects on the use of social network services2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Marketing has become obsessed with word of mouth. Though long known to be important for consumer decisions, social media has put it into overdrive, providing the infrastructure to launch big campaigns that nonetheless enters people’s consciousness on a very personal level thanks to messages being passed along by friends. This thesis explores what social media users think about this part of their user experience, attempting to answer how widespread awareness is and how their attitude to it affects their own use. Results show that a large majority of users in Sweden are aware that their spreading the word about a product or service can be considered a form of advertising, and that it also affects their own method of sharing. However, how much they use these services is not affected. Implications for social media providers and marketers are discussed.

  • 45142.
    Warnquist, Håkan
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Computer-Assisted Troubleshooting for Efficient Off-board Diagnosis2011Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This licentiate thesis considers computer-assisted troubleshooting of complex products such as heavy trucks. The troubleshooting task is to find and repair all faulty components in a malfunctioning system. This is done by performing actions to gather more information regarding which faults there can be or to repair components that are suspected to be faulty. The expected cost of the performed actions should be as low as possible.

    The work described in this thesis contributes to solving the troubleshooting task in such a way that a good trade-off between computation time and solution quality can be made. A framework for troubleshooting is developed where the system is diagnosed using non-stationary dynamic Bayesian networks and the decisions of which actions to perform are made using a new planning algorithm for Stochastic Shortest Path Problems called Iterative Bounding LAO*.

    It is shown how the troubleshooting problem can be converted into a Stochastic Shortest Path problem so that it can be efficiently solved using general algorithms such as Iterative Bounding LAO*.  New and improved search heuristics for solving the troubleshooting problem by searching are also presented in this thesis.

    The methods presented in this thesis are evaluated in a case study of an auxiliary hydraulic braking system of a modern truck. The evaluation shows that the new algorithm Iterative Bounding LAO* creates troubleshooting plans with a lower expected cost faster than existing state-of-the-art algorithms in the literature. The case study shows that the troubleshooting framework can be applied to systems from the heavy vehicles domain.

  • 45143.
    Warnquist, Håkan
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Kvarnström, Jonas
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerade datorsystem. Linköpings universitet, Tekniska fakulteten.
    Doherty, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerade datorsystem. Linköpings universitet, Tekniska fakulteten.
    A Modeling Framework for Troubleshooting Automotive Systems2016Ingår i: Applied Artificial Intelligence, ISSN 0883-9514, E-ISSN 1087-6545, Vol. 30, nr 3, s. 257-296Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a novel framework for modeling the troubleshooting process for automotive systems such as trucks and buses. We describe how a diagnostic model of the troubleshooting process can be created using event-driven, nonstationary, dynamic Bayesian networks. Exact inference in such a model is in general not practically possible. Therefore, we evaluate different approximate methods for inference based on the Boyen–Koller algorithm. We identify relevant model classes that have particular structure such that inference can be made with linear time complexity. We also show how models created using expert knowledge can be tuned using statistical data. The proposed learning mechanism can use data that is collected from a heterogeneous fleet of modular vehicles that can consist of different components. The proposed framework is evaluated both theoretically and experimentally on an application example of a fuel injection system.

  • 45144.
    Warnquist, Håkan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Kvarnström, Jonas
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Doherty, Patrick
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Institutionen för datavetenskap, UASTECH – Teknologier för autonoma obemannade flygande farkoster. Linköpings universitet, Tekniska högskolan.
    Exploiting Fully Observable and Deterministic Structures in Goal POMDPs2013Ingår i: Proceedings of the 23rd International Conference on Automated Planning and Scheduling (ICAPS) / [ed] Daniel Borrajo, Subbarao Kambhampati, Angelo Oddi, Simone Fratini, AAAI Press, 2013, s. 242-250Konferensbidrag (Refereegranskat)
    Abstract [en]

    When parts of the states in a goal POMDP are fully observable and some actions are deterministic it is possibleto take advantage of these properties to efficiently generate approximate solutions. Actions that deterministically affect the fully observable component of the world state can be abstracted away and combined into macro actions, permitting a planner to converge more quickly. This processing can be separated from the main search procedure, allowing us to leverage existing POMDP solvers. Theoretical results show how a POMDP can be analyzed to identify the exploitable properties and formal guarantees are provided showing that the use of macro actions preserves solvability. The efficiency of the method is demonstrated with examples when used in combination with existing POMDP solvers.

  • 45145.
    Warnquist, Håkan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Kvarnström, Jonas
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning.
    Doherty, Patrick
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Iterative Bounding LAO*2010Ingår i: ECAI 2010: 19th European Conference on Artificial Intelligence - Volume 215 Frontiers in Artificial Intelligence and Applications / [ed] Helder Coelho, Rudi Studer and Mike Wooldridge, IOS Press , 2010, s. 341-346Konferensbidrag (Refereegranskat)
    Abstract [en]

    Iterative Bounding LAO* is a new algorithm for epsilon- optimal probabilistic planning problems where an absorbing goal state should be reached at a minimum expected cost from a given initial state. The algorithm is based on the LAO* algorithm for finding optimal solutions in cyclic AND/OR graphs. The new algorithm uses two heuristics, one upper bound and one lower bound of the optimal cost. The search is guided by the lower bound as in LAO*, while the upper bound is used to prune search branches. The algorithm has a new mechanism for expanding search nodes, and while maintaining the error bounds, it may use weighted heuristics to reduce the size of the explored search space. In empirical tests on benchmark problems, Iterative Bounding LAO* expands fewer search nodes compared to state of the art RTDP variants that also use two-sided bounds.

  • 45146.
    Warnquist, Håkan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Kvarnström, Jonas
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Doherty, Patrick
    Linköpings universitet, Institutionen för datavetenskap, KPLAB - Laboratoriet för kunskapsbearbetning. Linköpings universitet, Tekniska högskolan.
    Planning as Heuristic Search for Incremental Fault Diagnosis and Repair2009Ingår i: Proceedings of the Scheduling and Planning Applications Workshop (SPARK) at the 19th International Conference on Automated Planning and Scheduling (ICAPS), 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we study the problem of incremental fault diagnosis and repair of mechatronic systems where the task is to choose actions such that the expected cost of repair is minimal. This is done by interleaving acting with the generation of partial conditional plans used to decide the next action. A diagnostic model based on Bayesian Networks is used to update the current belief state after each action. The planner uses a simplified version of this model to update predicted belief states. We have tested the approach in the domain of troubleshooting heavy vehicles. Experiments show that a simplified model for planning improves performance when troubleshooting with limited time.

  • 45147.
    Warnquist, Håkan
    et al.
    Scania CV AB, Södertälje, Sweden.
    Nyberg, Mattias
    Scania CV AB, Södertälje, Sweden.
    Biteus, Jonas
    Scania CV AB, Södertälje, Sweden.
    Guided Integrated Remote and Workshop Troubleshooting of Heavy Trucks2014Ingår i: International Journal of Commercial Vehicles, ISSN 1946-391X, Vol. 7, nr 1, s. 25-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When a truck or bus suffers from a breakdown it is important that the vehicle comes back on the road as soon as possible. In this paper we present a prototype diagnostic decision support system capable of automatically identifying possible causes of a failure and propose recommended actions on how to get the vehicle back on the road as cost efficiently as possible.

    This troubleshooting system is novel in the way it integrates the remote diagnosis with the workshop diagnosis when providing recommendations. To achieve this integration, a novel planning algorithm has been developed that enables the troubleshooting system to guide the different users (driver, help-desk operator, and mechanic) through the entire troubleshooting process.

    In this paper we formulate the problem of integrated remote and workshop troubleshooting and present a working prototype that has been implemented to demonstrate all parts of the troubleshooting system.

  • 45148.
    Warpefelt, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Cues and insinuations: Indicating affordances of non-player characters using visual indicators2015Ingår i: Proceedings of DiGRA 2015: Diversity of play: Games – Cultures – Identities, Digital Games Research Association , 2015, s. 1-12Konferensbidrag (Refereegranskat)
    Abstract [en]

    Non-player characters (NPCs) provide an important service in video games in that they provide an active connection to the narrative through their behavior, as if they were actors in a play. In this study, we aim to explore in what ways the visual appearance of an NPC affects how players perceive their role in the game, and what criteria players use to evaluate the role of NPCs based on visual information. This is done by performing a survey of players, where the respondents are asked to determine the role that a number of NPCs had given their visual appearance, and describe how they decided the roles of the NPCs.

  • 45149.
    Warpefelt, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Mind the Gap: Exploring the social capability of non-player characters2013Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Among the most important factors governing enjoyment of computer games is immersion, or the feeling the player has of being in the game world. This feeling allows the player to be transported into the world of the game, where they can experience grand adventures and riveting tales. Many factors contribute to the feeling of immersion, but as with any story-based experience the actors in the story are of the utmost importance. If the actors perform poorly, however, the player's feeling of immersion will be lessened, and the game will become less entertaining. Therefore, the Non-Player Characters (NPCs) inhabiting the game world must act in such a way that they are perceived as believable. Unfortunately, this is not always the case, and NPCs often disrupts the player's feeling of immersion. The purpose of this research is to describe how we can create NPCs who behave in ways that are conducive to player immersion, and who better portray the story of the game. This is done by identifying the current issues affecting the believability of NPC behavior. Over the course of the studies described in this thesis, we have developed a method by which problematic behaviors can be identified and described. This was done by studying NPCs in modern games using video recordings, and using an analytical tool to identify the specific factors that affect the believability of their behavior. In the end, we identified a number of such factors that affect the believability of NPCs, chief among them the inability of NPCs to perceive the world. By improving the way in which NPCs perceive the world, and more importantly how players perceive that NPCs perceive the world, we can greatly improve NPC believability.

  • 45150.
    Warpefelt, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    The Non-Player Character: Exploring the believability of NPC presentation and behavior2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Over the last few decades there has been immense growth in the video game industry, and we have seen great improvements in both graphics and audio. Unfortunately, the development of artificial intelligence (AI) and non-player characters (NPCs) has not proceeded at the same pace. Although there have undoubtedly been improvements, the field as a whole has lagged behind its siblings.

    Many of the problems with NPCs stem from the fact that they do not achieve a sufficient level of believability, particularly in the social arena. This is primarily related to the fact that the NPCs do not behave in ways that align with the expectations of the player. This can lead to the player misunderstanding the role and purpose of the NPC, which damages the believability of the game. By extension, this lessens the enjoyment the player can derive from the game. Hence, it is imperative that the design of the NPC be in line with player expectations.

    This thesis takes a holistic view of NPCs, encompassing their design, evaluation, and player perceptions. It uses a design science methodology, and primarily uses qualitative and interpretative methods. It will provide a description of the various types of NPCs found in games, what their design elements are, and how they are interpreted by players.

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