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Mikropolární kontinuum a jeho aplikace ve stavební mechanice / Micropolar continuum and its applications in structural mechanicsFleischerová, Beáta January 2022 (has links)
Práca sa zaoberá mechanikou kontinua. Konkrétne je zameraná na lineárnu elasticitu homogénnych izotropných pevných telies. Pre dve rôzne kontinuá – klasické kontinuum a mikropolárne je odvodená silná aj slabá formulácia. Cosseratovo (mikropolárne) kontinuum predstavuje rozšírenie ku klasickému, kde je uvažovaný ďalší stupeň voľnosti - nezávislá rotácia. Mikropolárne kontinuum definuje ďalšie dve materiálové konštanty, ktoré súvisia s rotáciou. V súčasnosti je metóda konečných prvkov veľmi populárny spôsob približného riešenia rovníc lineárnej elasticity. Pre účely diplomovej práce bol vyvinutý program pre MKP riešenie 2D rovinných úloh. Pre lepšiu predstavu o vplyvu rôznych parametrov na správanie sa oboch kontinuí analyzujeme jednoduchý príklad konzolového nosníka. Riešenia analyzujeme s využitím 4-uzlového štvorhranného elementu, ktorý je jedným z najpoužívanejších pre MKP. V Cosseratovom kontinue by mali byť rotácie previazené skrz parameter vnútornej dĺžky, čo by sa malo odzrkadliť zvýšenou tuhosťou telesa. Úlohou práce je porovnať výsledky z oboch kontinuí a potvrdiť tento predpoklad.
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Secure degrees of freedom on widely linear instantaneous relay-assisted interference channelHo, Zuleita K.-M., Jorswieck, Eduard January 2013 (has links)
The number of secure data streams a relay-assisted interference channel can support has been an intriguing problem. The problem is not solved even for a fundamental scenario with a single antenna at each transmitter, receiver and relay. In this paper, we study the achievable secure degrees of freedom of instantaneous relay-assisted interference channels with real and complex coefficients. The study of secure degrees of freedom with complex coefficients is not a trivial multiuser extension of the scenarios with real channel coefficients as in the case for the degrees of freedom, due to secrecy constraints. We tackle this challenge by jointly designing the improper transmit signals and widely-linear relay processing strategies.
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Kokboksundersökningar i naturvetenskapliga läromedel : En läromedelsanalys av hur många och vilka typer av laborativa aktiviteter som framställs i olika naturvetenskapliga läromedelAlmgren, Kajsa January 2022 (has links)
In this study, the aim has been to investigate how different educational materials in the nature science subjects are designed with the intention of how many and what types of laboratory activities the pupils will encounter to contextualize the abstract nature of science to develop their understanding of the content and working methods of science. In order for the pupils to have the opportunity to develop a scientific understanding, it is necessary that they have the opportunity to use their senses to interpret the text that is presented to them. Through various sensual, experimental, and practical activities, pupils can gain an understanding of the abstract phenomena, concepts, and explanatory models of natural science. In today's schools, there are many teachers who use educational materials as their point of departure when teaching science. Educational materials have an important role in science teaching, but depending on how the educational materials are designed, they provide different conditions for learning. In this study, the number of laboratory activities, that appear in different educational materials for science teaching, is investigated, as well as whether these laboratory activities are designed in terms of their degree of freedom and openness. The following questions have been addressed in order to achieve the purpose of the study: - How many laboratory activities can be found in the various educational materials?- Are there more laboratory activities in any of the three nature-oriented subjects, biology, physics, or chemistry? - What types of laboratory activities do the pupils encounter in the educational materials and what degree of openness and freedom do they include? The investigation has been carried out through a qualitative and quantitative text and content analysis where various educational materials have been analyzed based on the context-based learning (CBL) theory and the theory of laboratory classification. The results of the qualitative and quantitative text and content analysis showed that certain educational materials give the pupils more opportunities to connect the scientific content to real experiences. The results also showed that some educational materials have a greater variety of different laboratory forms where the pupils have the opportunity to develop an understanding of the different working methods and content of the natural sciences. The conclusion that can be drawn after this study is therefore that it is important that teachers carefully review the various2educational materials to gain insight into their design. Through insight into the design of the educational materials, the teacher can then supplement the educational materials with, for example, laboratories of varying degrees of openness and freedom to give the pupils the opportunity to fulfill the goals in the curriculum.
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Exploratory study of market entry strategies for digital payment platformsMarcinkowska, Anna January 2018 (has links)
The digital payment industry has become one of the fastest evolving markets in the world, but in the wake of its rapid advancement, an ever increasing gap between academic theory and the actual reality of this market widens - and especially so when it comes to entry theory. It is widely acknowledged that the world is moving towards an ever more homogeneous economy, but despite the fact that payment preferences differ greatly from country to country - research on this subject continues to revolve mainly around localized efforts. But as historical inequalities between poor and rich societies continue to dissipate - learning from nations at the forefront of technological advancement increases the likelihood that the developed strategy becomes applicable to an increased number of countries. By selecting a nation most conducive to technological growth, the purpose of this report is to map the present dynamics in its digital payment industry using both recent and traditional market entry theory. However, studies geared towards globalized strategy formulation cannot be assumed as having guaranteed access to internal company-data at all times. So in order to facilitate such studies, the level of dependency on primary data required for conducting such research needs to be understood first, which is why the work in this report is constrained strictly to data of secondary nature. This, not only to further map the characteristics of this market, but also to see how open the market is to public inspection. Ultimately, the academic contribution becomes that of providing a road-map towards adapting currently available market entry theory to suit the rapidly evolving conditions of the digital payment industry from a global perspective and, when failing to do so, the aim is to also explore avenues for further research towards this end goal.
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Perspective vol. 27 no. 4 (Dec 1993)VanderVennen, Robert E., Fernhout, Harry 31 December 1993 (has links)
No description available.
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Perspective vol. 27 no. 1 (Mar 1993)Fernhout, Harry, Meiboom, John, Klein, Reinder J., VanderVennen, Robert E., Walsh, Brian J. 31 March 1993 (has links)
No description available.
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Perspective vol. 17 no. 5 (Dec 1983)Seerveld, Calvin, Zylstra, Bernard, VanderVennen, Robert E., Van Ginkel, Aileen, Cooper, Justin, McIntire, C. T. 31 December 1983 (has links)
No description available.
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An exploration of the relevance of a doctorate degree in the South African Police ServiceMakgopa, Lazarus January 2019 (has links)
The primary aim of this study was to explore the relevance that serving and former SAPS members who hold an academic doctorate degree attach to such a degree in the SAPS occupational environment. From a qualitative standpoint, data was collected through phenomenological in-depth individual interviews with serving and former SAPS members who hold an academic doctorate degree. In addition, a comprehensive review of the relevant national and international literature was conducted to obtain a better understanding of this phenomenon. A thematic data analysis process was followed to analyse the collected data.
Various objectives were fulfilled in the completion of this study:
The relevance of an academic doctorate degree, as experienced by serving and former SAPS members, in their occupational environment was explored, identified and described.
The value that SAPS doctorate graduates add to the SAPS was explored, identified and described.
Recommendations were made regarding the optimal, efficient and effective utilisation of doctorate SAPS graduates in the occupational environment of the SAPS.
The findings of this study indicate that holding a doctorate degree in the SAPS generally adds value to the various aspects of policing. However, it was found that not all doctorate graduates in the SAPS are appropriately placed and placement is not necessarily influenced by graduates’ academic qualifications. Based on the findings of this study, a framework for the appropriate placement of doctorate graduates in the SAPS was developed. This framework could serve as a management tool to sensitise SAPS management to the relevance of an academic doctorate degree. In addition, this framework could act as a management tool guiding the SAPS management regarding the correct placement of academic doctorate graduates in the organisation. This study contributes significantly to the understanding of the relevance of a doctorate degree in the SAPS, thereby contributing to new knowledge related to this phenomenon. / Police Practice / Ph. D. (Police Science)
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Aplicação de abordagens de controle motor na análise temporal e de desempenho em arqueiros de elite / Motor control approaches in temporal and performance factors on elite archersReiser, Fernando Carvalheiro 11 March 2019 (has links)
O Tiro com Arco é uma modalidade olímpica na qual os atletas exibem diversas estratégias de coordenação muscular na preparação do disparo da flecha, principalmente no período da liberação do clicker, tornando dificultosa a interpretação da coordenação de arqueiros no que tange à sua pontuação. Deste modo, algumas técnicas, como a Análise de Vetor Codificado e co-ativação/inibição recíproca, provenientes de abordagens de Controle Motor, podem ajudar-nos a desvendar quais parâmetros em comum que estes arqueiros utilizam quando atiram e sua relação com seu desempenho obtido durante o disparo sequencial de flechas. O objetivo do trabalho foi o de avaliar a coordenação muscular utilizada por arqueiros da seleção brasileira durante uma simulação qualificatória olímpica, através da técnica eletromiográfica. Participaram 11 arqueiros da seleção brasileira; idade: 25,2±4,9 anos, altura: 1,72±0,12m, peso: 68,6±11,8 kg, FITA score: 1258±43 pontos, Qualificação: 632±20 pontos, Flecha média: 8,7±0,3 pontos. A análise EMG foi dividida em 0,5s antes e 0,15s após a liberação do clicker. Foi utilizado o valor RMS deste sinal de doze músculos: no lado que traciona a corda (dominante) - FSD (Flexor Superficial dos dedos); ED (Extensor dos dedos); BBL (Bíceps Braquial); TBL (Tríceps Braquial Cabeça longa); GD (Grande Dorsal) PMC (Peitoral Maior Clavicular); TS (Trapézio Superior); SAD (Serrátil Anterior); RA (Reto Abdominal) e ML (Multífido Lombar). Lado não dominante (nD) DPnD (Deltóide Posterior); SAnD (Serrátil Anterior), no qual foram criados em 14 pares de análise (agonista-antagonista: FSD-ED; BBL-TBL; GD-PMC; TS-SAD; RA-ML; distal-proximal: FSD-BBL; FSD-TBL; ED-BBL; ED-TBL; e mistos: PMC-SAD; GD-TS; SAD-SAnD; SAnD-DPnD; GD-DPnD), para a análise dentro das técnicas de Co-ativação/Inibição Reciproca e Análise de Vetor Codificado. Nos resultados; oito pares (FSD-ED; BBL-TBL; TS-SAD; FSD-BBL; FSD-TBL; ED-TBL; SAD-SAnD; SAnD-DPnD) co-ativaram diferentemente na transição de blocos (p<0.05); e 12 (FSD-ED; BBL-TBL; GD-PMC; TS-SAD; FSD-BBL; FSD-TBL; ED-BBL; ED-TBL; PMC-SAD; SAD-SAnD; SAnD-DPnD; GD-DPnD) co-ativaram diferentemente na comparação do escore obtido (p<0.05). Em nove pares, os arqueiros, evidenciaram diferentes estratégias de inibição recíproca na transição de blocos (FSD-ED; BBL-TBL; TS-SAD; FSD-BBL; FSD-TBL; ED-BBL; ED-TBL; SAD-SAnD; SAnD-DPnD) (p<0.05); um (TS-SAD) na análise de flechas (p<0.05); e nove (FSD-ED; BBL-TBL; FSD-BBL; FSD-TBL; ED-BBL; ED-TBL; SAD-SAnD; SAnD-DPnD; GD-DPnD) na análise do escore. A análise de Vetor Codificado apresentou que, no total de flechas disparadas nove pares (FSD-ED; GD-PMC; FSD-BBL; FSD-TBL; ED-BBL; ED-TBL; PMC-SAD; SAD-SAnD; SAnD-DPnD) mudaram a moda de fase de coordenação na transição de ajustes posturais, enquanto no desempenho 11 pares (FSD-ED; BBL-TBL; GD-PMC; TS-SAD; FSD-BBL; FSD-TBL; ED-BBL; ED-TBL; PMC-SAD; SAD-SAnD; SAnD-DPnD) evidenciaram tais mudanças. As técnicas apresentadas no presente estudo revelaram parâmetros em comum associados com as sequências temporais de disparo de flechas e com os escores obtidos por arqueiros de elite, isto corrobora com a complexidade da análise do desempenho em atletas de alto rendimento, contudo também colocam a disposição técnicas que ajudam na filtragem e verificação desses parâmetros outrora divergentes / Archery is an Olympic sport in which the athletes exhibit several muscular coordination patterns in the arrow shooting, mainly in the clicker falls tempo, making difficult the interpretation of the coordination of archers in what concerns to their score. Thus, some techniques, such as Vector Coding and co-activation/reciprocal inhibition, from Motor Control approaches, can help us to discover what common patterns these archers use when firing and their relation to their obtained performance during the sequential firing of arrows. Aim: evaluate the muscular coordination used by archers of the Brazilian team during an Olympic qualifying simulation, using the electromyographic technique. Eleven archers of the Brazilian team participated; age: 25.2 ± 4.9 years, height: 1.72 ± 0.12m, weight: 68.6 ± 11.8 kg, FITA score: 1258 ± 43 points, Qualification: 632 ± 20 points, Mean arrow: 8.7 ± 0.3 points. The EMG analysis was divided in 0.5s before and 0.15s after the release of the clicker. The RMS value of this twelve-muscle signal was used: drawning arm (dominant side) - FDS (Flexor Digitorum Superficilis); ED (Extensor Digitorum); BB (Biceps Brachii); TBL (Triceps Brachii - Long Head); LD (Latissimus Dorsi) PMC (Pectoralis Major Clavicular Head); UT (Upper Trapezius); ASD (Anterior Serratus); RA (Rectus Abdominis) and LM (Lumbar Multifidus). Non-dominant side (nD) DPnD (Posterior deltoid) and ASnD (Anterior Serratus non-dominant side); pairs created (Agonist-Antagonist: FDS-ED, BBL-TBL, LD-PMC, UT-ASD, RA-LM; Distal-Proximal: FDS-BBL, FDS-TBL, ED-BBL, ED-TBL and the pairs glenohumeral-scapular: PMC-SAD, GD-TS, SAD-SAnD, SAnD-DPnD, GD-DPnD) for analysis of co-activation/reciprocal inhibition and Vector Coding. Results; eight pairs (FDS-ED, BB-TBL, UT-ASD, FDS-BB, FDS-TBL, ED-TBL, ASD-ASnD, ASnD-DPnD) coactivated differently in blocks transition (p<0.05); and 12 (FDS-ED, BB-TBL, LD-PMC, UT-ASD, FDS-BB, FDS-TBL, ED-BB, ED-TBL, PMC-ASD, ASD-ASnD, ASnD-DPnD, LD-DPnD) co-activated differently in the score comparison (p<0.05). Also, the archers displayed different strategies of reciprocal inhibition in the blocks transition (FDS-ED, BB-TBL, UT-ASD, FDS-BB, FDS-TBL, ED-BBL, ED-TBL, ASD-ASnD; ASnD-DPnD) (p<0.05); one (UT-ASD) in the arrow analysis (p<0.05); and nine (FDS-ED, BB-TBL, FDS-BBL, FDS-TBL, ED-BBL, ED-TBL, ASD-ASnD, ASnD-DPnD, LD-DPnD) in the score analysis. Nine Vector Coding pairs (FDS-BB, FDS-TBL, ED-BB, ED-TBL, PMC-ASD, ASD-ASnD, ASnD- DPnD) changed the coordination phase mode in postural adjustments transition, while 11 pairs (FDS-ED; BB-TBL; LD-PMC; UT-ASD; FDS-BB; FDS-TBL; ED-BB; ED-TBL, PMC-ASD, ASD-ASnD, ASnD-DPnD) showed such changes in score analysis. The techniques presented in the present study revealed common parameters associated with temporal shoot-out and scores obtained by elite archers, dispite the complexity of performance analysis in high-performance athletes
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Géante éolienne offshore (GEOF) : analyse dynamique des pales flexibles en grandes transformations / Large scale offshore wind turbines (GEOF) : dynamic analysis of flexible blades undergoing large displacements and large rotationsBoujelben, Abir 15 November 2018 (has links)
L’objectif de ce travail porte sur le développement d’un modèle d’interaction fluide-structure adapté à la dynamique des éoliennes de grandes tailles avec des pales flexibles qui se déforment de manière significative sous l’effet de la pression exercée par le vent. Le modèle développé est basé sur une approche efficace d’IFS partitionnée pour un fluide incompressible et non visqueux en interaction avec une structure flexible soumise a des grandes transformations. Il permet de fournir une meilleure estimation de la charge aérodynamique et de la réponse dynamique associée du système (pales, mat, attachements, câbles) avec un temps de calcul raisonnable et pour des simulations sur des longues périodes. Pour la modélisation structurale, un élément fini de type solide 3D est développé pour l’étude dynamique des pales d’éolienne soumises à des grands déplacements et des grandes rotations. Une amélioration du comportement en flexion est proposée par l’introduction des degrés de liberté en rotation et l’enrichissement du champ de déplacements afin de décrire plus précisément la flexibilité des pales. Cet élément solide est apte de capter des modes de hautes fréquences qui peuvent s’avérer néfastes pour la stabilité du calcul. Deux techniques sont donc proposées pour les contrôler : la régularisation de la matrice masse et le développement des schémas d’intégration robustes de conservation et de dissipation d’énergie. Les chargements aérodynamiques sont modélisés en utilisant la Panel Method. Il s’agit d’une méthode aux frontières, relativement rapide par rapport à la CFD mais suffisamment précise pour calculer la distribution de la pression exercée sur la pale. Les modèles fluide et structure interagissent via un algorithme de couplage partitionné itératif dans lequel des considérations particulières sont prises en compte dans le contexte des grandes transformations. Dans un effort visant à instaurer un indicateur de fatigue dans la méthodologie proposée, des câbles précontraints sont introduits reliant le mat de l’éolienne au support. Une nouvelle formulation complémentaire en termes de contraintes est ainsi développée pour l’analyse dynamique des câbles 3D en comportement élasto-visco-plastique. Chaque méthode proposée a été d’abord validée sur des cas tests pertinents. Par la suite, des simulations numériques d’éoliennes avec des pales flexibles sont effectuées en vue d’affiner la compréhension de leur comportement dynamique et l’intérêt que la flexibilité des pales peut apporter à leur fonctionnement. / In this work, a numerical model of fluid-structure interaction is developed for dynamic analysis of giant wind turbines with flexible blades that can deflect significantly under wind loading. The model is based on an efficient partitioned FSI approach for incompressible and inviscid flow interacting with a flexible structure undergoing large transformations. It seeks to provide the best estimate of true design aerodynamic load and the associated dynamic response of such system (blades, tower, attachments, cables). To model the structure, we developed a 3D solid element to analyze geometrically nonlinear statics and dynamics of wind turbine blades undergoing large displacements and rotations. The 3D solid bending behavior is improved by introducing rotational degrees of freedom and enriching the approximation of displacement field in order to describe the flexibility of the blades more accurately. This solid iscapable of representing high frequencies modes which should be taken under control. Thus, we proposed a regularized form of the mass matrix and robust time-stepping schemes based on energy conservation and dissipation. Aerodynamic loads are modeled by using the 3D Vortex Panel Method. Such boundary method is relatively fast to calculate pressure distribution compared to CFD and provides enough precision. The aerodynamic and structural parts interact with each other via a partitioned coupling scheme with iterative procedure where special considerations are taken into account for large overall motion. In an effort to introduce a fatigue indicator within the proposed framework, pre-stressed cables are added to the wind turbine, connecting the tower to the support and providing more stability. Therefore, a novel complementary force-based finite element formulation is constructed for dynamic analysis of elasto-viscoplastic cables. Each of theproposed methods is first validated with differents estexamples.Then,several numerical simulations of full-scale wind turbines are performed in order to better understand its dynamic behavior and to eventually optimize its operation.
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