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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
811

FPGA based data acquistion and digital pulse processing for PET and SPECT

Bousselham, Abdel Kader January 2007 (has links)
The most important aspects of nuclear medicine imaging systems such as Positron Emission Tomography (PET) or Single Photon Emission Computed Tomography (SPECT) are the spatial resolution and the sensitivity (detector efficiency in combination with the geometric efficiency). Considerable efforts have been spent during the last two decades in improving the resolution and the efficiency by developing new detectors. Our proposed improvement technique is focused on the readout and electronics. Instead of using traditional pulse height analysis techniques we propose using free running digital sampling by replacing the analog readout and acquisition electronics with fully digital programmable systems. This thesis describes a fully digital data acquisition system for KS/SU SPECT, new algorithms for high resolution timing for PET, and modular FPGA based decentralized data acquisition system with optimal timing and energy. The necessary signal processing algorithms for energy assessment and high resolution timing are developed and evaluated. The implementation of the algorithms in field programmable gate arrays (FPGAs) and digital signal processors (DSP) is also covered. Finally, modular decentralized digital data acquisition systems based on FPGAs and Ethernet are described.
812

Dynamic Vehicle-Track Interaction of European Standard Freight Wagons with Link Suspension

Jönsson, Per-Anders January 2007 (has links)
The link suspension is the most prevailing suspension system for freight wagons in Central and Western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis investigates the dynamic performance of freight wagons and comprises five parts: In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed. The second part focuses on the lateral force-displacement characteristics of the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve the understanding of various mechanisms and phenomena in link suspension systems, a simulation model is developed. In the third part the multibody dynamic simulation model is discussed. The previous freight wagon model developed at KTH is able to explain many of the phenomena observed in tests. In some cases, however, simulated and measured running behaviour differ. Therefore, a new simulation model is presented and validated against on-track test results. The performance of standard two-axle freight wagons is investigated. The most important parameters for the running behaviour of the vehicle are the suspension characteristics. The variation in characteristics between different wagons is large due to geometrical tolerances of the components, wear, corrosion, moisture or other lubrication. The influence of the variation in suspension characteristics and other parameters on the behaviour of the wagon, on tangent track and in curves, is discussed. Finally, suggestions for improvements of the system are made. A majority of the traffic related track deterioration cost originates from freight traffic. With heavier and faster freight trains the maintenance cost is likely to increase. In the fourth part the possibility to improve ride comfort and reduce track forces on standard freight wagons with link suspension is discussed. The variation of characteristics in link suspension running gear is considerable and unfavourable conditions leading to hunting are likely to occur. Supported by on-track tests and multibody dynamic simulations, it is concluded that the running behaviour of two-axled wagons with UIC double-link suspension as well as wagons with link suspension bogies (G-type) can be improved when the running gear are equipped with supplementary hydraulic dampers. Finally in the fifth part the effects of different types of running gear and operational conditions on the track deterioration marginal cost — in terms of settlement in the ballast, component fatigue, wear and RCF — is investigated. Considerable differences in track deterioration cost per produced ton-km for the different types of running gear are observed. Axle load is an important parameter for settlement and component fatigue. Also the height of centre of gravity has significant influence on track deterioration, especially on track sections with high cant deficiency or cant excess. / QC 20100802
813

De första verksamhetsåren : en studie av sex olika företag / The first years of a corporate : a study of six different companies

Halse, Pehr, Trulsson, Jonas January 2009 (has links)
Syfte: Vi kommer i denna promemoria försöka skapa en förståelse för hur det är att driva ett nystartat företag samt vad som påverkar företagaren/företaget under de första åren. Vad tycker företagare att de kan stöta på för utmaningar under de första åren? Hur utvecklas ett företag och vad kan hända i det under de första åren? Metod: Det är den kvalitativa metoden och det hermeneutiska synsättet som har använts i denna uppsats. Vidare har vi arbetat med primärdata insamlad från intervjuer på ett induktivt arbetssätt. Teorin har insamlats från litteratursökning på högskolan i Gävles bibliotek samt genom internetsökningar. Analysen har skett genom en jämförelse mellan empiri och teori. Sedan har diskussionen om analysen samt slutsatser redovisats i efterföljande kapitel följt av egna kommentarer samt lärdomar. Resultat & slutsats: Vi har genom uppsatsen sett att empiri och teori delvis stämmer överrens med varandra. Dock har vi kommit fram till att empirin inte helt stämmer överrens med det teoretiska materialet om entreprenörskap. Det viktigaste vi har kommit fram till är att läran om entreprenörskap bäst erhålls genom empiriska studier i stället för teoretiska. Förslag till fortsatt forskning: Begränsningar i uppsatsen är bland annat att forskningen endast representerar ett mindre urval företagare samt teoretiska källor. För framtiden vill vi se en djupare och mer omfattande forskning för att se om våra slutsatser trots begränsningarna är korrekta. Uppsatsens bidrag: Inom uppsatsens problemområde ser vi att praktisk kunskap är mycket mer givande än teoretisk, när man driver ett företag. Uppsatsen visar för utbildningsorganisationer samt intresserade att den teori som finns i dagsläget ej är komplett. Med det menas att utbildning inom företagande bör ske av företagare och inte genom teori och/eller av praktiskt okunniga inom området. / Aim: In this study we are going to try to create an understanding of how a new corporate can be operated and how it/the owner can be affected during the first years. What challenges does corporate owners think they can be exposed of during the first years? How does a corporate develop and what can happen during the first years? Method: We used the qualitative method and the view of hermeneutics in this essay. Further on we worked with primary data based on interviews in an inductive way of investigation. The theory was collected from the library of the University of Gävle with help of their search engine and through searching the internet. Analyzing has been conducted through a comparison between empirical and theoretical data. The discussions about the analyze and the final result have later on been shown in the following chapters followed by our own comments and what we've learned. Result & Conclusions: From writing this essay we've seen that empirical and theoretical data partly tells the same. Our final results have shown us that empirical and theoretical data of entrepreneurship doesn't correspond to each other. The most important aspect of entrepreneurship is given through empirical studies instead of theoretical studies. Suggestions for future research: Some of the limitations in this essay are that the research only represents a minor selection of corporate and theoretical sources. For future studies we want to see a deeper and wider research to see if our conclusions, though the restrictions, are correct. Contribution of the thesis: Within the approach of the essay we have seen that practical knowledge is more giving than theoretical, when running a corporation. For educational organizations and those who are interested in the subject, the theoretical data that is known today aren't complete. With that said the education to be an entrepreneur should be led by those who are running a company and not through theoretical data and/or not by those who lack competence.
814

The Effectiveness of Resistance Exercises in the Management of Medial Tibial Stress Syndrome

Bard, Amanda E 01 April 2013 (has links)
Medial tibial stress syndrome (MTSS) is a stress and overuse injury that presents as pain on the medial aspect of the lower two-thirds of the tibia. It is most often caused by repetitive actions on hard surfaces such as running, marching, and dancing. Individuals most affected by MTSS are runners, members of the military, dancers, and athletes that play soccer, volleyball and basketball. While MTSS has a relatively standard presentation of pain on the medial aspect of the tibia, it can occasionally be mistaken for other injuries such as stress fractures or compartment syndrome. If a diagnosis is unsure, methods such as x-ray, bone-scan, and MRI can be utilized to better obtain the correct diagnosis. A variety of treatments exist for MTSS including, ice, massage, muscle strengthening, and rest. A combination of these various techniques is most often what is employed. In this study, the effectiveness of a set of resistance ankle exercises in combination with ice and massage was tested and compared to that of ice and massage alone. The hypothesis was that athletes receiving the exercises as part of their treatment, in addition to the icing and massaging, would have a greater decrease in pain from MTSS than athletes just receiving ice and massage as treatment. The exercises would strengthen the muscles of the lower leg that, when weak, can contribute to the development of MTSS. Results indicated that the exercises yielded a more significant decrease in pain from MTSS than ice and massage alone.
815

Mikrotypografins inverkan på läsbarheten hos tryckt brödtext : En forskningsöversikt / How microtypography affects the legibility of running text in print : A research review

Skoglund, Gabriel January 2012 (has links)
Hur en texts typografiska utformning påverkar hur enkel den blir att läsa är en fråga som har sysselsatt forskare under lång tid. Förhoppningen har varit att få en bättre förståelse för hur läsning går till och hur man bäst bör sätta text för att underlätta för läsaren. Ett problem har dock varit att skapa medvetenhet om forskningens resultat bland dem som arbetar med att sätta text. Tanken med detta examensarbete var att skapa en överblick av forskningen, med inriktning på hur mikrotypografin, det vill säga den typografi som berör detaljer i textens utformning, påverkar läsbarheten i brödtext. Efter litteratursökningar valdes tio vetenskapligt publicerade empiriska studier på detta område ut. Artiklarna beskrevs och diskuterades med hänsyn till deras metodik och deras resultat. Följande mikrotypografiska faktorer behandlades i studierna: skillnader i läsbarhet mellan typsnitt, x-höjdens och teckenavståndets inverkan på läsbarheten, skillnader i läsbarhet mellan gemener, versaler och kursiv text samt skillnader i läsbarhet mellan olika bokstavsformer. Slutsatsen var att forskningen kring läsbarhet ger intressanta inblickar i hur typografin inverkar på läsprocessen. Det begränsade antalet studier på varje område samt brist på studier utförda på svenska gör det dock svårt att skapa konkreta riktlinjer för hur text bör sättas. Vidare konstaterades att studier utförda i samarbete mellan forskare och typografiskt kunniga vore en möjlig metod att sprida kunskap till de typografiska yrkena och öka sannolikheten för praktisk tillämpning av forskningsresultaten. / How the typographic design of a document affects how easy it is to read is a subject that has long been of interest to researchers. The aim has been to reach a better understanding of the reading process, and to find an ideal way to design text for maximum legibility. However, the researchers have seemingly failed to raise awareness about their results in the typographic community. The aim of this thesis was to create an overview of the research into how microtypography – the typography concerned with individual letters and sentences – affects the legibility of running text. Ten empirical studies on this subject, published in scientific journals, were selected after literature searches. The methods and results of the studies were described and discussed. The studies were concerned with the following microtypographic factors: differences in legibility between typefaces, the role of x-height and letter spacing in, differences in legibility between lower case, upper case and italic letters as well as differences in legibility between specific letter shapes. The conclusion was that legibility research gives interesting insights into how typography can influence the reading process. However, the limited amount of studies found concerning each typographic factor, as well as the lack of studies concerning Swedish typography makes it hard to create typographic guidelines for Swedish typographers based on the research. It was also concluded that studies conducted in cooperation between researchers and typographers might be a way to raise awareness about the research and lead to greater practical application of research results.
816

The Research And Application of Control system of electrical sports equipment

Huang, Jia-Shing 30 July 2002 (has links)
This paper explores the problem of electrical sports equipment includes 2D-animation, storage media and the safety-protection over out of control of speed and the supporting supervisory control apparatus. This paper succeeded in developing a highly efficient DSP-based motor driver system in the form of a jogging machine which employs IVSC and RISC control law. The simulation and experimental results show that the proposed system meets the requirements of servo tracking with excellent transient, steady state responses and robustness. This paper design a multi-functional FPGA uses in control system of sports equipment to provide the designing flexibility for different scales, solutions to the difficulties of production and maintenance, and the extension for future development of sports equipment.
817

"Something more than fantasy": fathering postcolonial identities through Shakespeare

Waddington, George Roland 28 August 2008 (has links)
Not available / text
818

Rörelse i förskolan : En essä skriven för att fördjupa ämneskunnandet och vinna insikt om olika förutsättningar för barns rörelse inomhus / Movement in preschool : An essay written for increasing the subject knowledge and gaining insight into the  conditions of children's movement indoors

Gjersvold, Emelie January 2015 (has links)
Denna essä tar sin utgångspunkt i två självupplevda händelser som speglar varandra i form av kaosartat spring inomhus och strukturerad rörelseaktivitet utomhus. Händelserna skapar starka motsatta känslor inom mig och jag undrar varför jag anser att det ibland är okej att röra på sig och ibland inte.  Syftet med denna essä är att studera rörelse på förskolan utifrån olika perspektiv och utvinna kunskap om vad rörelse på förskolan innebär. Genom att undersöka flera olika perspektiv på rörelse har jag en vision om att skaffa mig tillräckligt med kunskap för att skapa bra förutsättningar för barns rörelse inomhus. Miljön ska locka alla individer oavsett kön och därför har jag även valt att undersöka vad tidigare forskning säger om pojkars och flickors rörelse. Frågorna som ligger till grund för studien öppnar upp för att distansera mig från dilemmat och skapa förståelse genom nya perspektiv. Hur ser jag på rörelse, hur ser andra på rörelse och vad kan ligga till grund för barnens kroppsliga uttryck för rörelse?   Essän syftar till att rikta blicken mot mig själv och mitt agerande i händelserna, vad jag gjorde bra och vad jag kunde ha gjort annorlunda. Genom att reflektera med en pendlande rörelse mellan teorier, mina tankar och mina händelser, försöker jag synliggöra vad som är min praktiska kunskap. Jag ställer mig kritisk mot den forskning som påstår att stora barngrupper är stressande för barn och vuxna, då min upplevelse av fenomenet är annorlunda. Min praktiska kunskap, baserad på mina två års erfarenheter med stora barngrupper, säger mig att med välorganiserade strukturer blir även detta ett framgångsrikt arbetssätt.   Essän i sig är en metod där jag genom att utgå från mina egna erfarenheter, reflekterar kring dessa med hjälp av andra teorier. Att skriva en essä handlar om processkrivande där jag undersöker ett fenomen ur flera olika perspektiv. Till grund för framskridandet av min studie ligger även hermeneutiken med sin tanke om att tolka meningen bakom och fenomenologin genom att se på ett fenomen så som det upplevs av människan som subjekt. / This essay is based on two self-perceived events that reflect each other in the form of chaotic indoor running and structured outdoor movement activity. The events create strong opposing emotions within myself and I wonder why I think that sometimes it is acceptable to move around and sometimes it is not.   The purpose of this essay is to study movement in preschool from different perspectives and extract knowledge about what movement in preschool means. By exploring multiple perspectives on motion, I strive to gather enough knowledge to create exemplary conditions for children's movement indoors. The environment should attract all individuals regardless of gender and therefore I have chosen to examine what earlier research says about boys and girls movement. The questions that form the basis for the study allow me to distance myself from the dilemma and create an understanding through new perspectives. How do I view movement? How do others view movement and what could be the underlying factors for the children's physical expression of movement?   The essay intends to look inwards at my thought processes and outwards at my actions in the events. What I did well and what I could have done differently? By reflecting continuously between theories, my thoughts and my events, I try to highlight my practical knowledge. I find myself critical of the research that says that large groups of children are stressful for children and adults, as my experience of the phenomenon is to the contrary. My practical knowledge, based on my two years of experience with large groups of children, tells me that with well-organized structures even large groups can be a successful approach.   The essay itself is a method whereby I start from my own experiences and then reflect on those experiences with the help of other theories. The essay itself is a writing process throughout which I examine a phenomenon from different perspectives. The underlying theoretical perspectives of my study are hermeneutics with the idea of interpreting the meaning behind the situation and phenomenology, by looking at a phenomenon as it affects humans as subjects.
819

Training intensity distribution, physiological adaptation and immune function in endurance athletes

Neal, Craig M. January 2011 (has links)
Exercise intensity and its distribution is probably the most important and most heavily debated variable of endurance training. Training induces adaptation but also induces stress responses. Controlling the training-intensity distribution may provide a mechanism for balancing these two effects. It has been reported that elite endurance athletes train with a high volume and load, relative to the sport. These athletes spend the vast majority (>80%) of training time at relatively low intensities (lower than the lactate threshold, zone one), and therefore <20% of training time above the lactate threshold (zones two and three). Experimental studies support the beneficial effects of a high training volume in zone one, and show detrimental effects of replacing zone one training with training in zone two. This is likely due to enhanced recovery from training in zone one compared with training in zone two. The acute recovery following training sessions in zones two and three has been reported to not be different, but the recovery following training in zone one has been reported to be faster. Improvements in physiological adaptation and endurance performance have been reported to be greater following training programmes with higher exercise intensities. Therefore, it has been suggested that a polarised training model, which includes ~80% of training in zone one with ~20% of training in zone three is more beneficial than a threshold training model, with the majority of training in zone two. However, research into an optimal training-intensity distribution is limited. Therefore, the aims of this thesis were to assess the effectiveness of training-intensity distribution on the improvements in physiological adaptation, endurance performance and assess if manipulating training-intensity distribution had an effect on immune function. Study one revealed that the lactate threshold, the lactate turnpoint and maximal performance measures in swimming, cycling and running, assessed using the methods outlined in the study, are reproducible in trained endurance athletes. These tests can therefore be used by trained endurance athletes as part of a physiological testing programme to assess not only endurance performance, but also to demarcate training intensity zones for exercise intensity prescription and monitor moderate to large adaptations to training. Practitioners should take care when deciding on the duration between tests to test for adaptations from training, as adaptations need to be greater than these detected test-retest variations to be considered physiologically meaningful. To the best of the author’s knowledge, study two was the first study to have assessed training-intensity distribution in a group of multisport athletes. Training was monitored over a 6-month period, and testing took place every two months to assess the effect of the training on physiological adaptation. Although speculative due to the number of variables involved, the results suggest that a greater proportion of training time spent in zone one and a lower proportion of training time spent in zone two is beneficial to physiological adaptation. However, given the number of variables associated with assessing the training-intensity distribution in multisport athletes, it is not easy to draw conclusions as to the effectiveness of the training in the different disciplines on the key measures of adaptation in the different disciplines. Study two highlighted the need for future research to focus on experimental manipulation of training-intensity distribution and thus improve our understanding of its impact on the training-induced adaptations in endurance athletes. Study three manipulated the training-intensity distribution in trained endurance athletes in just one discipline, to reduce the number of variables involved. A polarised training model was compared to a threshold training model on the effectiveness to improve physiological adaptation and endurance performance. Results revealed that a polarised training model is recommended for trained cyclists wishing to maximally improve performance and physiological adaptation over a short-term (six week) training period. The first part of study four assessed the effect of a polarised and a threshold training model on immune function markers in trained cyclists. Both endurance training programmes had similar volume, and were sufficient to induce improvements in performance and physiological adaptation. However, despite likely differences in recovery, both training programmes had no effect on the proportion of low or high differentiated or senescent CD8+ or CD4+ T-cells in blood. Therefore, training adaptation was achieved at no cost to this particular aspect of immune function. From these results and evidence from previous studies, it seems likely that athletes need to be overreached to induce any change in immune function following a period of intensified training. The second part of study four assessed the impact of an ironman triathlon race on Epstein-Barr virus (EBV) and Varicella-Zoster virus (VZV) antibody titres and the frequency of low and high differentiated and senescent blood T-cells in trained endurance athletes. Previous work has revealed that an ironman triathlon race increases the proportion of senescent CD4+ T cells and decreases the proportion of naive CD4+ T cells, and thus induces changes the immune space which could leave an individual at a greater risk of infection. This study however, did not find any changes in the proportions of these T cell subsets following an ironman triathlon race. The mean results of this study suggest that there is no relationship between EBV and VZV-specific antibody concentrations and the proportion of senescent, low and highly differientiated T cells. However, on analysis of individual subject data, it seems possible that subjects with a high antibody titre for EBV or VZV 3 wks before a competition might be more at risk of infection post race. A greater subject number would be needed in order to make a more conclusive statement about this relationship. The results of this thesis suggest that future research is required in the area of training-intensity distribution. Firstly, our understanding of the physiological mechanisms responsible for the effectiveness of a polarised training model in trained endurance athletes is limited, and thus studies should attempt to address this issue. Our current knowledge on the mechanisms underlying a blunted T cell response following strenous exercise is also limited. A change in the immune space to a greater proportion of senescent T cells and a lower proportion of naive T cells might contribute to this blunted response. In the current thesis however, the proportions of these T cell markers were unchanged following the training/racing interventions. It is possible that with a higher training load, there could be changes in these markers, and thus this is an exciting area that could have potential implications on athlete health. Finally, testing for antibody titres in endurance athletes is possibly an avenue to detect individuals at the greatest risk of infection if subjected to a large physical and/or mental stress. This could have implications on maintaining athlete health and therefore, allowing athletes to train consistently.
820

Liposomal verkapselte Glukokortikosteroide in der Therapie der mdx-Maus als Modell der Duchenneschen Muskeldystrophie / Liposomal and free prednisolone do not affect the early disease course in mdx dystrophic mice

Weller, Charlotte 27 September 2010 (has links)
No description available.

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