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  • Kristén, Lars (författare)
  • Possibilities offered by interventional sports programmes to children and adolescents with physical disabilities an explorative and evaluative study
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>Today, sport is a topic that interests and engages many people. However, pursuing sporting activities and being a member of a sports club is not a matter of course for children and adolescents with physical disabilities. The overall aim of this thesis is to study the possibilities offered by interventional sports programmes to children and adolescents with physical disabilities and to describe in what way they can be offered meaningful physical activities as well as active participation in sport clubs, with a view to improving their health and socialisation through sport. The thesis includes three descriptive and one evaluative study.</p> <p>The results of the thesis rest on a combination of methods: practical- empirical experiences based on theoretical reasoning, interviews in line with a method inspired by phenomenography, and data from questionnaires analysed by descriptive and analytical statistics. The results are also based on a variety of data sources i.e. children, young people and parents as well as theory triangulation i.e. socialisation and health. According to the findings, sports programmes offered possibilities to children and adolescents with physical disabilities for improving their health and socialisation. An important component of the sports programmes were sports clubs that offered meaningful physical activities as well as active participation. Guidelines for co-operation in and the organisation of sports programme for children and adolescents with physical disabilities were of great importance and should involve the families as well as sports organisations and local authorities. The children and adolescents regarded sport as a form of social arena to enhance their participation in society and as a means for achieving better health. They also stressed the importance of knowledge and experiencing nature as factors that promote an active and healthy lifestyle. The parents regarded sport as a form of health education and as a means for their children to achieve increased participation in society. The parents also stressed the fact that the learning process was important for empowering the children to influence their life situation. The findings also illustrate the importance of building co-operation between the habilitation centre, sports clubs and families of children with physical disabilities by means of a working team, as well as the importance of the sports movement opening up its activities to children and adolescents with functional disabilities and each sports club appointing a contact person with special responsibility for this target group. Continued external support was regarded as necessary in order to assist the sports clubs in implementing permanent and well-functioning activities in partnership with a personal sport and health counsellor, who advises and supports the children and adolescents to participate in physical activity.</p>
  • Grönlund, Erik (författare)
  • Microalgae at wastewater pond treatment in cold climate : an ecological engineering approach
  • 2004
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>Three types of wastewater ponds in subarctic climates were investigated, each of them highly dependent on microalgae. They were fellingsdams, i.e. wastewater stabilization ponds complemented with chemical precipitation, high-rate algal ponds (HRAPs), and a type of aquaculture interface ponds between a wastewater treatment plant and the natural surrounding.</p> <p>From a microalgae taxa perspective green algae and cryptophytes were dominant in the wastewater ponds. Green algae and cryptophytes were also, together with chryso- and haptophytes, dominating the hypereutrophic and eutrophic stages of the natural lakes. Biomasses in the different types of ponds were of very different order of magnitude. From 100-1000 mg/l in the stabilization ponds during summer and 10-100 mg/l in spring and autumn, 70- 90 mg/l in a HRAP in autumn, to 5-30 mg/l in the most hypereutrophic stage in the natural ponds, 1-10 mg/l in the eutrophic stage, and below 1 mg/l in the oligotrophic stage.</p> <p>The connection between wastewater pond treatment and the field of ecological engineering was recognized. Future development of pond technology may benefit from a stronger connection to the theoretical framework of systems ecology developed in collaboration with the field of ecological engineering and ecotechnology.</p>
  • Dahlén, Leon (författare)
  • Numerical and experimental study of performance of a hydraulic motor
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>The aim of this study was to develop an understanding of the fluid properties that influence the efficiency of hydraulic systems in a steady-state, especially components in hydrostatic transmission systems under different running conditions. The aim has also been to investigate and model the sources of losses in hydraulic machines, in order to estimate the losses, taking fluid properties into account. Finally, the technique of optimization has been introduced in order to improve the efficiency of a distributor valve in a radial piston hydraulic motor, Marathon M200. From an experimental field-test, which was performed on a belt conveyer using a hydrostatic transmission system, the overall efficiency of the hydrostatic transmission was compared when using a mineral oil, Shell Tellus TX 68, a synthetic fluid, Mobil SHC 526, and a vegetable fluid, Binol Hydrap II. The experimental field-test showed that vegetable and synthetic fluids improve the efficiency compared to mineral oil. The three fluids have the same viscosity but experimental tests showed that the temperature ()- and pressure() -viscosity coefficient differs between them. It was also found that the pressure-viscosity coefficient () of mineral oil was higher compared to vegetable and synthetic fluids. The proposed steady-state model gives greater accuracy regarding overall efficiency than the Wilson model, when examining fluid properties that differ in other aspects than their viscosity. The study has focused on losses in lubricated sliding contacts within a radial piston hydraulic motor, Marathon M200, and an analysis of the losses has been made using the finite element method (FEM). A FEM software package, Solvia, which takes into account fluid properties, such as temperature- and pressure- viscosity coefficient, heat conduction and specific heat, has been used to simulate the behaviour and to estimate the losses in tribological contact. This approach of simulation has been applied to two different tribological contact within the hydraulic motor: to a journal bearing contact and to a hydrostatic annular multi-recess plane thrust bearing. By using an FEM software package linked to an optimization algorithm, the losses in the tribological contact in a distributor valve were reduced significantly. The study shows that the optimized geometry of the distributor valve in the motor can successfully be improved, with regard to losses, by small changes in the geometry. Combining an FEM software package with the optimization routine offers an effective tool for designers to simulate and improve the efficiency of a hydraulic unit.</p>
  • Isaksson, Per (författare)
  • On crack growth under compressive stresses
  • 2001
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>This thesis concerns fractures subjected to compressive stresses. In the four papers appended fracture behavior in brittle as well as ductile materials is studied. In the first paper, an expression for the mode II stress intensity factor at a straight extended kink has been calculated under the condition that crack opening is suppressed during crack growth. The expression has been found as a function of the mode II stress intensity factor K2 at the parent crack, the direction and length of the kink, and the difference between the remote compressive normal stresses perpendicular to, and parallel with, the plane of the parent crack. Crack growth directions have been suggested based on the result. At a sufficiently high non-isotropic compressive normal stress, so that the crack remains closed, the crack will propagate along a curved path maximizing the mode II stress intensity factor. Only at an isotropic compressive normal stress will the crack continue straight ahead in its original plane without directional change. By analyzing experimental crack growth patterns in paper two, the conclusion is that crack paths experimentally observed indicate that mode II crack growth under compression in some brittle materials follow a propagation path described by a function y=gx^b. In fact, the agreement between the experiments and the propagation path prescribed by the model, in which b=3/2, is astonishingly good since b was found in the interval [1.43-1.58] in all the experiments studied. Further, the investigation of the curvature parameter g has revealed that g also agree with the simplified model, even though not as good as the exponent b. However, the experimentally observed g differs in general less than 15% from the theoretical value predicted by the analytical model discussed in paper I. In paper three, a directional crack growth criterion in a compressed elastic perfectly-plastic material is considered. A slip-line solution is derived for evaluation of the stresses at the crack tip, which considers hydrostatic pressure and friction between the crack surfaces. Based upon the slip-line solution a projection stress based model is discussed for prediction of the direction of initiated crack growth. The opening displacement of an extended kink has been examined in paper four, using a finite element procedure. The conclusion is that an over-critical pressure in the plastic zone surrounding the crack tip suppresses crack opening regardless the direction of crack growth. The only possibility seems to be shear mode crack growth, which occur straight ahead in the crack plane if the crack is assumed to follow the plane of maximum shear stress. At a sub-critical hydrostatic pressure, or lower friction between the crack surfaces, the crack can extend via a kink subjected to local opening mode. An expression for the critical value determining fracture mode has been found as a function of hydrostatic pressure and friction between the crack surfaces assuming the fracture process to be predominantly controlled by local tensile stresses at the crack tip. The crack growth directions predicted by the projection stress based criterion in paper three are comparable with the directions maximizing the opening displacement of an extended kink computed in paper four.</p>
  • Gao, Chuansi (författare)
  • Slip and fall risk on ice and snow : identification, evaluation and prevention
  • 2004
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Slip and fall accidents and associated injuries on ice and snow are prevalent among outdoor workers and the general public in winter in many regions of the world. To understand and tackle this multi-factorial problem, a multidisciplinary approach was used to identify and evaluate slip and fall risks, and to propose recommendations for prevention of slips and falls on icy and snowy surfaces. Objectives were to present a systems perspective of slip and fall accidents and related risk factors; to evaluate the integration of slip resistance, thermal insulation, and usability of footwear by subjective trials. Further, to study the interaction mechanisms between footwear soling material and ice; to investigate and describe the relationship of ice and snow living experience and participation in winter sports with slips and falls; and to explain the role and mechanisms of lower extremity muscles in maintaining gait dynamic balance on inclined icy surface. The following methods were applied: 1) a systematic analysis of multiple risk factors through literature review; 2) direct observation; 3) videotaping; 4) subjective evaluations of slipperiness, thermal comfort and usability using rating scales; 5) a tribological study of the Coefficient of Friction (COF); 6) a questionnaire survey to identify and evaluate risk factors related to slips and falls; 7) a biomechanical study of human locomotion on ice. A systematic analysis of slips and falls on icy and snowy surfaces made it possible to use a multi-faceted approach to evaluation and prevention. The slip resistance, thermal insulation and usability of footwear tested were not suitably integrated, indicating the need of improving anti-slip properties and usability of footwear for use in cold environments. The artificially abrasive wear of soling materials improved slip resistance on hard ice, but not on melting ice. When comparing hard ice, melting ice and lubricated steel surfaces, the highest slip resistance was observed on hard ice, then on lubricated steel plate. Melting ice was most slippery. Curling footwear with crepe rubber soling showed significantly higher COF than other types. The footwear tested included winter footwear, professional footwear, safety footwear, and footwear considered to be slip resistant by manufacturers did not provide adequate protection against slips and falls on melting ice. Thus, additional measures should be taken to reduce slip and fall risk on melting ice. Slip and fall events declined with increased living experience in cold environments and winter sports participation. Biomechanical studies showed both increased and decreased magnitudes of gait muscle activities (EMG) at different gait phases and a generating of cautious gait strategies with an anticipated icy surface. These findings provided insights into how the proactive kinetic and kinematic adjustments of gait are achieved and the control mechanisms of stabilizing gait and posture through certain muscle activities when ascending on an icy slope. The mechanisms identified may be applied to develop intervention, rehabilitation and training techniques, which prevent slip and fall risks and associated injuries on icy surfaces and to improve performance in human locomotion, e.g., for winter sports. Measurement methods of slipperiness on ice and snow, related standards, task-related factors, slip resistant footwear, and intervention programs should be further studied and developed.
  • Barth, Henrik, 1971- (författare)
  • Barriers to growth and development in small firms
  • 2004
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>The purpose of the extended summary is to develop the understanding of the existence and reasons behind barriers to growth and development in small firms. More specifically, four questions are addressed: (1) What do we know about the term barrier, how can it be defined? (2) What types of barriers to growth and development have been identified? (3) How can barriers to growth and development be addressed in a framework? and (4) How do the results of the appended papers (Papers I-V) contribute to the research field of barriers to growth and development?</p><p>A literature review was undertaken to answer the first two questions. The literature review was conducted in two phases. The conceptual and operational definition of barriers was addressed in the first phase. The results reveal diverse ways of focusing on barriers, which made it necessary to address similar terms, such as problem and causes of business failure in the second phase of the literature review. The different terms used in the papers of the literature review are discussed in order to determine whether or not the understanding of their content is coherent and conceptual. Based on the conceptual understanding and definition of barriers, the different aspects focused on in the literature were discussed, which led to the second question, What are the various aspects of barriers to growth and development?</p><p>The knowledge gained from the literature review and the development of the understanding of the barrier concept led to the third question, Can barriers to growth and development be addressed in a framework? The discussion takes its starting point in the studies identified in the literature review and is related to some of the appended papers (Papers I and II). Similarities and differences between frameworks used in the papers identified in the literature review are discussed and, based on this knowledge, a framework for barriers to growth and development in small firms is presented. The framework distinguishes two types of barriers, namely internal/external barriers and tangible/intangible barriers.</p><p>The knowledge available in the reviewed papers within the field of barriers to growth and development in small firms in combination with the results from the appended papers (Papers I-V) resulted in the fourth question. Part of the contribution of the appended papers concerns the operational definition, for example that barriers to innovation should be categorised as either occurring or preventing firms from innovating (Paper II), while other contributions concern specific types of barriers, for example the importance of managerial skills (Paper V). Overall, the contribution focuses on conditional factors, such as strategy and planning, organisation and management, and institution and policy factors, in relation to growth and development.</p>
  • Fredriksson, Maria (författare)
  • From Customer Satisfaction to Citizen Interaction : a cooperation model for community development based on Total Quality Management
  • 2004
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>Dagens problem med arbetslöshet och neddragningar i den offentliga sektorn kräver nya lösningar, där vanliga medborgare kan få mer aktiva roller än idag, som individer eller i grupp. Syftet med denna avhandling är att bidra med en sådan lösning, i form av en samverkansmodell för utveckling av lokala samhällen, baserad på offensiv kvalitetsutveckling och på medverkan av många invånare. Modellen utvecklas stegvis med hjälp av observerade erfarenheter och uppfattningar hos tre olika intressentgrupper i två svenska samhällen. Forskningen bygger också på litteraturstudier och befintliga teorier. De tre grupperna är de pionjärer som startat utvecklingsprojekten, de vanliga invånarna och de lokala kommunpolitikerna. Avhandlingens disposition följer denna uppdelning.</p><p> </p><p>Avhandlingen innehåller två fallstudier. Den första berör använd-ningen av offensiv kvalitetsutveckling som stöd för utveckling i ett lokalt samhälle. Arbetet bedrivs inom en icke-vinstdrivande organisation som bygger på frivilligt engagemang. Erfarenheterna från detta jämförs, i den andra fallstudien, med ett annat samhälle där offensiv kvalitetsutveckling inte används, men där ambitionerna är desamma. Här organiseras arbetet inom både en icke-vinstdrivande och en vinstdrivande organisation.</p><p> </p><p>Analyserna visar att offensiv kvalitetsutveckling kan användas framgångsrikt inom samhällsutvecklingen, även om några av dess verktyg och metoder tolkas på nya sätt, eller inte används alls. Eftersom offensiv kvalitetsutveckling bör användas med hänsyn till en organisations mål, så är en viss flexibilitet både väntad och önskvärd. När det gäller managementfrågor, så bör ledarskapet vara både ”mjukare” och mer diplomatiskt när det gäller obetalt och frivilligt arbete, i jämförelse med situationen i ett kommersiellt företag. En annan observation är att detta arbete med samhällsutveckling bedrivs bäst inom grupper som definieras av situationer och aktiviteter som är typiska för livet eller för samhället. En aktiv invånare kan gå med i en viss grupp efter intresse. Detta är en modifierad version av ”kvalitetscirklar” enligt recept från offensiv kvalitetsutveckling. I en oberoende, mer teoretisk studie i denna avhandling, diskuteras användningen av offensiv kvalitetsutveckling inom nya samhälls-sektorer.</p><p> </p><p>I både de studerade lokala samhällena finns svårigheter att engagera och aktivera fler invånare, vilket innebär att mandatet kan ifrågasättas för stora projekt som strävar efter att förbättra livskvaliteten för alla invånare. Det är också problem med att rekrytera och förnya ledarskapet, och med att kommunicera med, framförallt, de lokala politikerna. Trots detta så är dessa politiker i allmänhet positiva till privata initiativ som i de två samhällena, och tycker att liknande projekt kan bli mycket viktiga för den framtida utvecklingen av små samhällen på landsbygden. De tycker också att de upplevda svagheterna kan åtgärdas om utvecklingsarbetet definieras och organiseras tydligt, om information och kommunikation förbättras, och om de aktiva invånarna skaffar sig bättre kunskaper om procedurer och begränsningar inom den politiska styrningen av samhällena.</p><p> </p><p>Dessa och andra observationer av de två samhällena leder till en modell där samarbetet mellan olika intressegrupper utvecklas i tre faser; starten, etableringen och fortsättningen av arbetet. Varje fas diskuteras separat, och olika råd ges för hur problemen som förväntas uppstå kan antingen undvikas eller åtgärdas.</p>
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