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1.
  • Worbin, Linda (författare)
  • Designing dynamic textile patterns
  • 2010
  • Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
    • Designing Dynamic Textile Patterns Progress in chemistry, fibres and polymers technology provides textile designers with new expressive materials, making it possible to design dynamic textile patterns, where several different expressions are inherent in the same textile, textiles that, for example, could alternate between a striped and checkered pattern. Textiles are traditionally designed and produced to keep a given, static expression during their life cycle; a striped pattern is supposed to keep its stripes. In the same way textile designers are trained to design for static expressions, where patterns and decorations are meant to last in a specific manner. However, things are changing. The textile designer now deals also with a new raw material, a dynamic textile, ready to be further designed, developed and/or programmed, depending on functional context. This transformation in practice is not an easy one for the designers. Designers need to learn how to design with these new materials and their specific qualities, to be able to develop the full expressional potential inherent in “smart textiles design”. The aim of this thesis is to display, and discuss, a methodology for designing dynamic textile patterns. So far, something that mainly has been seen in different experimental and conceptual prototypes, in artistic expressions and for commercial efforts etc. In terms of basic experimental research this thesis explores the turn in textile design practice through a series of design experiments with focus on contributing to identifying and characterizing new design variables, new design methods and new design techniques as a foundation for dynamic textile patterns.
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2.
  • Hilletofth, Per (författare)
  • Demand-Supply Chain Management
  • 2010
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Purpose: This research aims to enhance the current understanding and knowledge of the demand-supply chain management (DSCM) concept by determining its elements, benefits, and requirements, as well as by analyzing key elements of the concept. Methodology: This research has utilized the case study strategy and the survey strategy, however, the case study strategy dominates. The case study research has involved five companies originating from Sweden and the collection of empirical data mainly from in-depth interviews with key persons representing senior and middle management. The survey research targeted the largest firms in Sweden and Finland and empirical data was collected through an online questionnaire. Findings: This research has established that the main elements of DSCM include market orientation, coordination of the demand and supply processes, viewing the demand and supply processes as being equally important, as well as value creation, differentiation, innovativeness, responsiveness, and cost-efficiency in the demand and supply processes. It has also been revealed that the main benefits of DSCM include enhanced competiveness, enhanced demand chain performance, as well as enhanced supply chain performance, while the main requirements of DSCM include organizational competences, company established principles, demand-supply chain collaboration, and information technology support. A key element of DSCM further investigated is differentiation focused supply chain design. It has been shown that these efforts can be organized into a process of five stages. In addition, it is important that this process is addressed in parallel with the new product development (NPD) process, that information is exchanged between them, and that they are directed on the basis of the same segmentation model. Another key element of DSCM further investigated is coordination between NPD and SCM. This research has identified several significant linkages between these management directions, which motivate the use of an integrative NPD process where the NPD functions are aligned with the main supply functions in the company and other sales-related functions supporting the commercialization. A final key element of DSCM further investigated is the significance of regarding the demand processes and the supply processes as being equally important. This research has revealed that logistics outsourcing can be risky, if it results in the supply processes being considered less important. Nevertheless, if senior management regards the outsourced processes as equally important as the in-house processes, the effect of logistics outsourcing on company strategies and direction in SCM could be reduced and logistics outsourcing could instead provide an opportunity to improve the design and differentiation of the supply chain. Research limitations/implications: This research has proposed, described, and further analyzed a demand-supply oriented management approach. Such a management approach stresses that the demand processes and the supply processes have to be coordinated and directed at an overlying level, in order to gain and sustain a competitive advantage in competitive and fragmented markets. This research is mainly explorative in nature, and more empirical data, from similar and other research settings, is needed to further validate the findings. Another limitation of the research is that it is essentially limited to Swedish companies (even if some Finnish companies are involved in the survey), however, many of the case companies have a large international presence and are among the top three in their industries, facts which provide some grounds for generalization. Practical implications: This research provides researchers and practitioners with insights into how to develop a demand-supply oriented business. It shows that companies should organize themselves around understanding how customer value is created and delivered, as well as how these processes and management directions can be coordinated. In order for this to occur, the demand and supply processes must be considered as being equally important and the firm needs to be managed jointly and in a coordinated manner by the demand- and supply-side of the company. It is also important that value creation is considered in both the demand and supply processes. Originality/value: Despite strong arguments from both researchers and practitioners for a demand-supply oriented management approach only a minority of companies appear to have effectively coordinated the demand and supply processes. This might be influenced by the lack of research examining how the demand and supply processes can be coordinated, what benefits can be gained by coordinating them, and what requirements are necessary to succeed. This research contributes by investigating these types of aspects further.
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3.
  • Pejlare, Johanna, 1976 (författare)
  • On Axioms and Images in the History of Mathematics
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This dissertation deals with aspects of axiomatization, intuition and visualization in the history of mathematics. Particular focus is put on the end of the 19th century, before David Hilbert's (1862–1943) work on the axiomatization of Euclidean geometry. The thesis consists of three papers. In the first paper the Swedish mathematician Torsten Brodén (1857–1931) and his work on the foundations of Euclidean geometry from 1890 and 1912, is studied. A thorough analysis of his foundational work is made as well as an investigation into his general view on science and mathematics. Furthermore, his thoughts on geometry and its nature and what consequences his view has for how he proceeds in developing the axiomatic system, is studied. In the second paper different aspects of visualizations in mathematics are investigated. In particular, it is argued that the meaning of a visualization is not revealed by the visualization and that a visualization can be problematic to a person if this person, due to a limited knowledge or limited experience, has a simplified view of what the picture represents. A historical study considers the discussion on the role of intuition in mathematics which followed in the wake of Karl Weierstrass' (1815–1897) construction of a nowhere differentiable function in 1872. In the third paper certain aspects of the thinking of the two scientists Felix Klein (1849–1925) and Heinrich Hertz (1857–1894) are studied. It is investigated how Klein and Hertz related to the idea of naïve images and visual thinking shortly before the development of modern axiomatics. Klein in several of his writings emphasized his belief that intuition plays an important part in mathematics. Hertz argued that we form images in our mind when we experience the world, but these images may contain elements that do not exist in nature.
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4.
  • Gebäck, Tobias, 1977 (författare)
  • On boundary value problems for intracellular subdiffusion and signaling pathways, and for geometric flows
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The main part of this thesis concerns mathematical models for diffusion of proteins inside cells, including reactions between the proteins. Initially, such models are applied to describe signaling pathways in yeast cells, and the properties of the model are studied, especially in relation to models that do not include diffusion. The results show that it is sometimes necessary to include diffusion in the model to capture important aspects of the biological system. The thesis also contains work on the numerical methods used to compute solutions to the reaction-diffusion equations inside domains. Specifically, the Immersed Interface Method, which allows efficient numerical solution inside arbitrary domains using uniform rectangular grids, is applied on Boolean grids, which give the same accuracy as uniform grids while using fewer grid points. The third part of the thesis also concerns models for protein diffusion inside cells, but now describing the phenomenon subdiffusion (or anomalous diffusion), which has been observed inside cells and manifests itself as a qualitatively different, and slower, diffusion behaviour of proteins. The cause of this phenomenon is the crowdedness of the interior of the cell, where other proteins and larger structures interfere with the motion of the proteins. In the thesis, a new mathematical model for anomalous diffusion in the form of a parabolic pseudo-differential equation is proposed, and a proof of existence of solutions for boundary value problems representing anomalous diffusion inside a cell is given. Experiments using Fluorescence Correlation Spectroscopy which support the model have also been performed. Finally, the thesis contains a convergence result for a computational scheme for approximation of mean curvature flows inside a domain, that is the description of the motion of surfaces which move at each point with a velocity depending on the mean curvature at that point. The scheme allows a quite general dependence on the curvature and concerns the case when the moving surface is inside a domain and intersects the domain boundary at a right angle.
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5.
  • Liwång, Hans (författare)
  • Risk-based ship security analysis : a decision-support approach
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The protection of shipping does not come without hazards and threats for military forces, individual civilian ship operators and crews. With particular focus on security threats, this thesis is about how to prepare for such operations without introducing unnecessary risks, i.e., supporting conscious risk-taking related to ship security. It examines both civilian and military aspects of maritime security and therefore draws from the experience of both fields.Maritime safety regulations, guidelines and methods have a history and culture of systematic research, development and implementation. In contrast, international security is highly politicised and therefore less transparent. Unfortunately, comprehensive studies of ship security risk are rare. Moreover, applying risk-based approaches to security areas requires special considerations, and the limited research in this field has led to a knowledge gap.To reduce the identified challenges with respect to security risk analysis, the goal of this thesis is to improve security decision support by defining an approach to ship security analysis. To increase overall safety, this approach must facilitate compromises between traditional maritime safety and maritime security. Accordingly, the objective is to develop an approach that is both systematic and gives the decision maker an appropriate picture of the security risks. To examine the requirements for a security decision-support approach, the work in the appended papers studies both threats to naval vessels and the security threat posed to commercial vessels by pirates. The results of the studies can be used to further develop military doctrines and civilian guidelines.This study shows that the description and quantification of the (concept of) operation in the risk analysis is central for implementing both security and naval ship survivability. In addition, the crew’s risk perception, procedural safeguards and how the implemented risk controls are perceived have an important role not only in risk analysis but also in deciding the effectiveness of implemented controls. It is also concluded that only using expected values—not collecting and using uncertainties—in the analysis can lead to misleading results. Therefore, the uncertainty treatment offered by a quantitative approach is crucial for risk understanding, especially if the aim is to find robust control options or to support the development of a resilient culture.
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6.
  • Lund, Anja (författare)
  • Melt spun piezoelectric textile fibres : an experimental study
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Melt Spun Piezoelectric Textile Fibres - an Experimental Study ANJA LUND Department of Materials and Manufacturing Technology Chalmers University of Technology ABSTRACT The manufacturing and characterisation of piezoelectric textile fibres are described in this thesis. A piezoelectric material is one that generates an electric voltage when deformed, a property which exists in a number of materials. The polymer with the strongest known piezoelectric effect today is poly(vinylidene fluoride) (PVDF), however it must be processed under certain conditions to become piezoelectric. This study shows that piezoelectric bicomponent PVDF-based fibres can be produced by melt spinning, which is a common and relatively simple fibre spinning method. The melt spinning process must include cold drawing, as this introduces a polar crystalline structure in the polymer. The fibres must also be electroded, which is done by producing bicomponent fibres with a core-and-sheath structure. The core is electrically conductive and constitutes an inner electrode consisting of a carbon black/polymer compound, whereas the sheath is PVDF and constitutes the piezoelectric component. Being sensitive to both deformation and temperature changes, these fibres are anticipated to be useful in a number of sensor applications. The flexibility and small size of the fibres makes it possible to include them as miniature-sensors in structures or garment without affecting the shape or comfort.
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7.
  • Salomonsson, Kent (författare)
  • Meso-Mechanical Modeling and Analysis of Adhesive Layers
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis is concerned with the modeling, simulation and analysis of adhesive layers. By use of an in situ scanning electron microscopy study it is found that the adhesive studied in the present thesis has a very complex structure with two different compounds, a mineral and an epoxy/thermoplastic blend. A representative volume element (RVE) model is developed to study the behavior of the adhesive layer at the meso-level. It is a continuum model where interface finite elements are implemented at the boundaries of the continuum elements in order to enable crack initiation and propagation of micro cracks. On a structural level, two deformation modes, modes I and II, dominate the behavior of thin adhesive layers. With the RVE it is possible reproduce experimental stress-deformation relations from both modes. However, in a real structure, mixed mode loading usually occur. A range of mode mixes is studied, using the RVE, from an un-loaded state until fracture of the layer. The results indicate that the behavior of the interface elements dominate for mode mixes close to mode I and plasticity in the continuum elements dominates for mode II dominated mode mixes. Furthermore, effects of large root curvatures of the adherends is analyzed numerically by simulating plastically deforming double cantilever beam specimens using the finite element model. The developed RVE is implemented in the models to simulate the behavior of the adhesive layer. By this methodology, virtual experiments can be analyzed with extreme detail. It is shown that in-plane straining of the adhesive layer significantly influences the strength of adhesive joints at large plastic strain of the adherends. There is a never ending need in industries to minimize computational time. To this end, an interphase finite element for structural analyses is developed. The element considers in-plane straining of the adhesive layer due to large curvatures of surrounding substrates.
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8.
  • Winroth, Mats (författare)
  • On Manufacturing Strategies : Competing Through Inter-Organizational Collaboration
  • 2004
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Globalization increases the competition among small and medium sized companies. It is possible for their customers, often large systems integrators, to choose suppliers from all around the world. Swedish suppliers are often not competitive only regarding cost consequently simple work tasks are more and more located in low wage countries. One way for the Swedish suppliers to compete is to collaborate with other suppliers, thus adding extra value for their customers. If companies plan to collaborate they need however to coordinate their activities to enable efficient product realization. The companies have different production systems and manufacturing strategies that should be coordinated. The purpose of this research is to investigate the role of manufacturing strategies and the relations between manufacturing strategies and design of production systems in different organizational settings. Organizational aspects on collaborative manufacturing settings are also studied. The research has been carried out through a number of case studies, thus adding empirical value to existing theory. A production system framework is proposed that links the competitive priorities of the company and the manufacturing strategies to the design of the production system. This framework can be used to highlight the dynamic interaction between companies in inter-organizational collaborative manufacturing settings involving small- and medium sized enterprises. In collaborative settings, there is one main flow of information, i.e. from a dominating partner, normally the systems integrator, to a more subordinate partner, normally the supplier. The concept of asymmetric domination is introduced, showing this asymmetric situation. The asymmetric domination gives input to decisions regarding which competitive priorities the collaborative setting should aim at fulfilling with its production systems. The selforganizing aspect on collaborative settings is introduced as a mean to enable more efficient operations. Mutual work tasks are facilitated through reduction of the formal control. Finally, experiences from a number of studies of manufacturing networks in Sweden are synthesized and an integration framework for handling the complexity in collaborative networks is introduced.
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9.
  • Johansson, Helena, 1971- (författare)
  • Mathematical Reasoning : In physics and real-life context
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis is a compilation of four papers in which mathematical reasoning is examined in various contexts, in which mathematics is an integral part. It is known from previous studies that a focus on rote learning and procedural mathematical reasoning hamper students’ learning of mathematics. The aims of this thesis are to explore how mathematical reasoning affects upper secondary students’ possibilities to master the physics curricula, and how real-life contexts in mathematics affect students’ mathematical reasoning. This is done by analysing the mathematical reasoning requirements in Swedish national physics tests; as well as by examining how mathematical reasoning affects students’ success on the tests/tasks. Furthermore, the possible effect of the presence of real-life contexts in Swedish national mathematics tasks on students’ success is explored; as well as if the effect differs when account is taken to mathematical reasoning requirements. The framework that is used for categorising mathematical reasoning, distinguishes between imitative and creative mathematical reasoning, where the latter, in particular, involves reasoning based on intrinsic properties. Data consisted of ten Swedish national physics tests for upper secondary school, with additional student data for eight of the tests; and six Swedish national mathematics tests for upper secondary school, with additional student data. Both qualitative and quantitative methods were used in the analyses. The qualitative analysis consisted of structured comparisons between representative student solutions and the students’ educational history. Furthermore, various descriptive statistics and significance tests were used. The main results are that a majority of the physics tasks require mathematical reasoning, and particularly that creative mathematical reasoning is required to fully master the physics curricula. Moreover, the ability to reason mathematically creatively seems to have a positive effect on students’ success on physics tasks. The results indicate additionally, that there is an advantage of the presence of real-life context in mathematics tasks when creative mathematical reasoning is required. This advantage seems to be particularly notable for students with lower grades.
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10.
  • Ohlsson, Claes, 1970- (författare)
  • Folkets fonder? : En textvetenskaplig studie av det svenska pensionssparandets domesticering
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The social and political background for this study is the change in Sweden from a system of a collective pension scheme to a system that includes elements of individual responsibility and a higher personal involvement of Swedes in pension saving funds. This phenomenon has been conceptualized as domestication, a metaphor that serves as a unifying notion in this study. The aim is to capture the idea of controlling markets from the perspective of individual investors. Two groups of texts are studied, advertising materials from banks and information from the PPM agency, responsible for the fund- based premium pension. What role do these texts play in the domestication of pension savings in commercial funds?The investigation includes a careful analysis of the settings of the texts and an identification of text purposes. Another matter of interest is the part that textual genres and their institutional framework play in the process. The methods are qualitative close reading techniques, held together by a view of language as a communicative and social phenomenon. Domestication in- volves the construction of informal relations between senders and the con- ceived reader together with individual-focused strategies. The senders share strategies of informalisation and individualisation but genres have differenti- ating roles in the actualization of domestication strategies. Domestication stabilizes the shared discourse of the banks and the PPM agency. It is how- ever doubtful that the focus on the individual’s responsibility has helped to gain trust in a pension system partially based on commercial funds. 
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