In this thesis project, the possibility to make use of a mechanical spring to achieve stiffness adjustability in a shock absorber for mountain bikes is evaluated. A mechanical spring increases the shock absorber’s sensitivity compared to a fully adjustable air spring. Today, there are no mechanical springs available on the market that offer enough stiffness adjustment to suit different riders with large variation in weight. Therefore, a mechanical spring with a wide stiffness adjustment range could be ground-breaking if it is possible to implement in mountain bike shock absorbers. The work has been carried out in accordance with a product- and concept development approach where the final concept design has been optimised analytically and verified numerically. The developed spring has been integrated in a new damper design and the complete damper and spring system has been dimensioned to fit current mountain bike frames. The result is a prototype shock absorber with a spring to suit riders between 70-88kg. An alternative spring for cyclists between 59-75kg has also been proposed. Since these springs have been made to fit current mountain bikes, it was possible to conclude that a mechanical spring witha wide range of adjustable stiffness is feasible for mountain bike application. With available spring steels, it is not possible to accommodate every rider with only one spring. It is however possible to achieve adjustment that is suitable for a rider weight range of roughly 15-16kg. This is between 70-110% more than similar products available on the market can offer. / I detta examensarbete utvärderas möjligheten att använda en mekanisk fjäder för att uppnå justerbar fjäderstyvhet hos en stötdämpare avsedd för terrängcykling. En mekanisk fjäder ökar stötdämparens känslighet jämfört med en fullt justerbar luftfjäder. I dagsläget finns på marknadeningen mekanisk fjäder vilken kan erbjuda tillräcklig justeringsmån för att passa cyklister med stor viktvariation. Därför kan en mekanisk fjäder med ett brett styvhetsspann vara banbrytande om en sådan kan tillämpas på dagens terrängcyklar. Arbetet har utförts som ett produkt- och konceptutvecklingsprojekt där den slutliga konceptdesignen har optimerats analytiskt och verifierats numeriskt. Den fjäder som tagits fram har integrerats i en ny dämparkonstruktion och stötdämparsystemet har dimensionerats för att passa dagens terrängcyklar. Resultatet är en prototyp av en stötdämpare med en fjäder som passar cyklister mellan 70-88kg. En alternativ fjäder passande cyklister mellan 59-75kg har också tagits fram. Eftersom en justerbar fjäder vars design möjliggör användning i en stötdämpare för dagens terrängcyklar har slutsatsen dragits att en justerbar mekanisk fjäder kan fungera inom detta tillämpningsområde. Det är inte möjligt med dagens material att utforma en mekanisk fjäder med tillräckligt justerbar styvhet föratt passa alla åkare. Det är däremot möjligt att använda en fjäder som passar cyklister inom ett viktspann på omkring 15-17kg. Detta är mellan 70–110% mer än vad liknande produkter tillgängliga på marknaden idag kan erbjuda.

In this thesis, the dynamic performances of kinematically and dynamically adjustable planar mechanisms have been investigated. An adjustable mechanism is here defined to be a mechanism where some of the kinematic and/or dynamic parameters are changed in a controlled manner in order to optimize the dynamic behaviour of the mechanism in spite of variable operating conditions. Here, variable operating conditions refer to variable load(s) on the mechanism and/or variable desired input motion. The dynamic behaviour of the mechanism may be optimized via minimization of the actuator torque/force fluctuations, minimization of energy consumed by the actuators etc. According to the type of the adjustable parameter, the adjustable mechanisms are classified into two groups namely, dynamically adjustable mechanisms and kinematically adjustable mechanisms. Mechanisms, where the main concern is to change a dynamic parameter(s) are called dynamically adjustable mechanisms. In the kinematically adjustable mechanisms, on the other hand , the main concern is to change a kinematic parameter(s). The main objective of this study is to investigate the benefits of adjustable planar mechanisms, regarding different dynamic behaviours under variable operating conditions. To achieve this objective , various simulations have been performed on the computer. In these simulations, practical constraints that will exist in a real application have been taken into account as much as possible. The results reveal that, in many cases, the dynamic behaviour of a planar mechanism may be improved quite extensively via adjustable mechanisms which are obtained from the original mechanisms with slight modifications.

Why Do Borrowers Choose Arms Over FRMS? : A Behavioral Investigation in the U.S. and Japan by Masaki Mori In the U.S., a considerable number of borrowers still choose adjustable rate mortgages (ARMs) over fixed rate mortgages (FRMs), even with historically low interest rates. During 2004-2005, when interest rates remained at 30-year lows, ARMs accounted for approximately one-third of all mortgage originations. Kahneman and Tversky's Prospect Theory’s reflection hypothesis suggested that people tend to be more risk-averse in positive decision situations, while they tend to be more risk-seeking when making negative choices. The first purpose of this study is to examine descriptive reasons for the popularity of ARMs in the U.S. People of different cultures often evaluate uncertain events in different ways. Hofstede developed a cultural dimension, uncertainty avoidance (UA), where UA is defined as the extent to which people feel threatened by uncertain situations. The second purpose of this study is to test the role of UA on the choice of mortgage products using data from two cultures (U.S. and Japan), potentially differing in attitude toward uncertain situations. Controlled experiments were conducted using 92 U.S. participants and 49 Japanese participants. Results of analysis supported Prospect Theory’s reflection hypothesis, suggesting that risk-averse people tend to become more risk-seeking when choosing a mortgage type, leaning more toward ARMs when people frame the mortgage choice problem as part of a loss situation. The results of the intercultural comparison portion of the study supported the research hypothesis that UA works as a moderating variable for Prospect Theory’s reflection hypothesis, suggesting that risk-averse people with lower UA scores more dramatically change from a risk-averse preference for a fixed-rate bond to a more risk-seeking preference for an adjustable-rate mortgage, than risk-averse people with higher UA scores do. Overall, results of this study suggested that borrowers behave differently depending on their propensity for current consumption, the level of UA, and how they frame the mortgage choice decision. This study contributes to existing mortgage choice literature by incorporating psychological and cultural traits to examine borrowers’ attitudes towards interest rate risk with regard to residential mortgages. The findings are of great importance globally for governments and lenders in creating and introducing new mortgage products in countries with diverse cultures.

Šiuo metu Pasaulyje skrandžio apjuosimo reguliuojama juosta operacijos sudaro apie 43 % visų chirurginių operacijų, atliekamų nutukimui gydyti. Iki šiol nėra pilnai ištirta operacijoje naudojamų skrandį apjuosiančių reguliuojamų juostų konstrukcijos skirtumų įtaka gydymo rezultatams, taip pat nėra priimtų pacientų atrankos šiai operacijai kriterijų. Disertacijoje palyginome vienerių metų nutukimo chirurginio gydymo rezultatus naudojant skirtingas skrandį apjuosiančias reguliuojamas juostas – SAGB ir MiniMizer Extra. Nustatėme, kad skrandžio apjuosimo reguliuojama juosta operacija yra efektyvus ir saugus nutukimo gydymo būdas: vidutinis procentinis perteklinio kūno masės indekso sumažėjimas buvo 33,1 ± 21,9%; vertinant pagal BAROS, 34.1% pacientų pasiekė patenkinamą, 30,6% - gerą, 9,4% – labai gerą ir 2,4% – puikų gydymo rezultatą; pasitaikė 5 (4,9%) „didžiosios” komplikacijos. Esminių skirtumų tarp lygintų juostų efektyvumo ir komplikacijų skaičiaus po vienerių metų po operacijos nenustatyta: vidutinis procentinis perteklinio kūno masės indekso sumažėjimas SAGB ir MiniMizer Extra grupėse buvo atitinkamai 28,9 ± 21,3% ir 36,8 ± 22.1%, p=0.075, o „didžiųjų” komplikacijų skaičius atitinkamai 0 (0%) ir 5 (9.3%), p=0.069. 40 metų ir vyresni pacientai geresnių rezultatų pasiekė naudojant MiniMizer Extra juostą - vidutinis procentinis perteklinio kūno masės indekso sumažėjimas buvo 37,5 ± 20,8% prieš 23,6 ± 13,8 % SAGB grupėje, p=0.002. Pacientai, kurių pradinis KMI ≤ 47, geresnių... [toliau žr. visą tekstą] / It has been estimated that LAGB represents about 42% of bariatric operations performed worldwide. There are a number of different adjustable gastric bands available. Few attempts have been made to compare the influence of band design differences for efficiency and complication rate. There are no accepted criteria for choosing this particular operation. In the dissertation we compared one year results after adjustable gastric banding using different adjustable gastric bands – SAGB and MiniMizer Extra. We have determined that laparoscopic adjustable gastric banding is effective and safe bariatric procedure: the average percentage of initial excess body mass index loss was 33,1 ± 21,9%; 34.1% of patients achieved fair, 30,6% - good, 9,4% - very good and 2,4% - excellent results according to BAROS; only 5 (4,9%) major complications were diagnosed. No radical differences were stated between the efficiency and complication rate of the compared adjustable gastric bands: the average percentage of initial excess body mass index loss in SAGB and MiniMizer Extra groups was 28,9 ± 21,3% and 36,8 ± 22.1% respectively, p=0.075; major complication rate was 0 (0%) and 5 (9.3%) respectively, p=0.069. Patients at the age of 40 and older achieved better results using MiniMizer Extra band - the average percentage of initial excess body mass index loss was 37,5 ± 20,8% versus 23,6 ± 13,8% in SAGB group, p=0.002. Patients with initial BMI ≤ 47 achieved better results using MiniMizer Extra band... [to full text]

This Master´s thesis deals with construction design adjustable track of tractor rear axle in a company Zetor Tractors a.s. At the very beginning there is an overview of different possibilities adjustable track from other world´s producers of tractors. Afterwards there is my constructional working from selection variant of suspension to final project. In this case the thesis contains required calculations of the whole device. Thesis also contains the stress and strain analysis of significant part of construction using a numerical approach of finite element method (FEM) and drawing documentation of the project constructed device.

[pt] Os sistemas de potência são projetados para operar com rígidos requisitos de qualidade, de modo que, as usinas hidrelétricas devem gerar energia, mantendo tensão e freqüência elétrica constantes. No método clássico de geração, a freqüência é controlada pelo sistema regulador de velocidade de turbina, que tende a manter a rotação da turbina fixa na velocidade síncrona. Como durante a operação da usina, as condições físicas como, por exemplo, altura de queda e vazão, não reproduzem as de projeto durante todo o tempo, o ponto de operação da turbina pode afastar-se da região de máxima eficiência por longos períodos, reduzindo seu rendimento total. Este trabalho aborda a utilização da máquina de dupla alimentação com conversor estático em seu rotórico para geração hidrelétrica em regime de velocidade ajustável, com desacoplamento entre a velocidade da turbina e a freqüência do sistema, apresentando os benefícios obtidos através do uso desta tecnologia. / [en] Power systems are designed to operate under strong quality requirements, so that hydroelectric plants have to produce energy with constant voltage and frequency. According to classical generation schemes, frequency is controlled by the speed governors, which tend to maintain the turbine rotating speed fixed at a synchronous speed. During the plant life the basic variables, such as water head and flow, are not the same as those assumed for the design, the turbine s operating point can go out of the region for maximal efficiency for long periods of time, decreasing than the plant total efficiency. This dissertation brings up the use of a double-fed machine with a static converter connected to the rotor s circuit for adjustable speed generation, with the decoupling of the turbine speed and the system frequency. This work does also show the improvements of the use of this technology.

Stucture simple, faible coût, grand espace de travail et technologie mature, ces avantages font que les manipulateurs sériels sont largement utilisés dans de nombreux domaines industriels. Avec le développement rapide de l'industrie et les diverses applications des manipulateurs sériels, de nouvelles exigences strictes sont souhaitées, telles que la stabilité robuste, la grande précision de positionnement et la cadence élevée.Un des moyens efficaces pour améliorer les performances mentionnées est la conception de manipulateurs sériels à découplage dynamique. Dans ce cadre, l'objectif de cette thèse est de valider une structure simple permettant de réaliser un découplage dynamique complet des manipulateurs sériels en tenant compte de la charge embarquée.Le chapitre 1 présente les solutions connues et décrit les inconvénients liés aux différentes techniques permettant une simplification de la dynamique des manipulateurs. L'étude de la bibliographie a permis d'affiner les objectifs à atteindre. Le chapitre 2 traite de la conception de manipulateurs sériels réglables à dynamique linéarisée et découplée. Sans la charge embarquée, la méthode développée réalise le découplage dynamique par rotation inverse des bras et par redistribution optimale des masses. La charge embarquée qui conduit à une perturbation au niveau des équations dynamiques dedécouplage est compensée par la commande.Le chapitre 3 envisage un nouveau concept de découplage dynamique qui consiste à relier aux bras initiaux d'un manipulateur sériel, deux bras additionnels pour réaliser un mécanisme Scott-Russell. Les mouvements opposés des bras du mécanisme Scott-Russell associés à une redistribution optimale des masses permettent de supprimer les termes non linéaires des équations dynamiques du manipulateur. Le modèle linéaire et découplé ainsi obtenu permet de tenir compte de la charge embarquée.Dans le chapitre 4, on considère les propriétés de robustesse (incertitudes paramétriques) de quatre modèles de manipulateurs sériels (un manipulateur couplé, un manipulateur découplé par la commande et les deux manipulateurs découplés qui sont issus des chapitres 2 et 3). Les études qualitatives sont effectuées par simulation en utilisant la même loi de commande optimale et la même trajectoire de référence. Les résultats des simulations permettentde conclure sur la robustesse des manipulateurs décrits aux chapitres 2 et 3 par rapport au manipulateur couplé et au manipulateur découplé par la commande.La méthodologie de conception et les techniques de commande proposées sont illustrées par des simulations réalisées à l'aide des logiciels ADAMS et MATLAB. Les simulations ont confirmé l'efficacité des approches développées. / Simple structure, low cost, large workspace and mature technology, these advantages make the serial manipulators are widely used in many industrialfields. With the rapid development of industry and various applications of serial manipulators, new strict requirements are proposed, such as highstability, high positioning accuracy and high speed operation.One of the efficient ways to improve the mentioned performances is the design of manipulators with dynamic decoupling. Therefore, the goal in thisthesis is to find simple structure pennitting to carry out complete dynamic decoupling of serial manipulators taking into account the changing payload.The review, given in Chapter I, sunmarizes the known solutions and discloses the drawbacks of different techniques permitting a simplification of thedynamics of manipulators. lt allows an identification of objectives that are of interest and should be studied \within the framework of this thesis.Chapter 2 deals with the design of adjustable serial manipulators with linearized and decoupled dynamics. Without payload, the developed methodaccomplishes the dynamic decoupling via opposite rotation of links and optimal redistribution of masses. The payload which leads to the perturbation ofThe dynamic decoupling equations is compensated by the optimal control technique.Chapter 3 deals with a new dynamic decoupling concept, which involves connecting to a serial manipulator a two-link group forming a Scott-Russell mechanism combined with optimal redistribution of masses allows the cancellation of the coefficients of nonlinear terms in the manipulator's dynamic equations. Then, by using the control, the dynamicdecoupling taking into account the changing payload is achieved.In chapter 4, robustness properties (parametric uncertainties) of four various models of serial manipulators (one coupled manipulator, one decoupled manipulator by feedback linearization and the two decoupled manipulators that modeled in chapters 2 and 3) are considered. The given comparison performed via simutations is achieved with the same optimal control law and the same reference trajectory. Simulation results allow one to derive robustness assessments of manipulators described in chapters 2 and 3.The suggested design methodology and control techniques are illustrated by simulations carried out using ADAMS and MATLAB software, which have confirmed the efficiency of the developed approaches.

Bretton Woods system has never been a main topic of Czech economic literature even though it strongly influenced finance of the most developed countries between 1944 and 1971 (1973). This diploma thesis is an attempt to analyze this important historical phenomena in international finance and the last metal oriented system in the history. The first chapter brings the most important terms and definitions that are necessary for better understanding of this problem. It is followed by chapters analysing international finance development in this area starting with the interwar period, followed by creation of Bretton Woods Monetary System in 1944 and first very successful and hopeful years that finally came to an end with accumulation of more problems that put a strain on the system such as for instance creation of long term dollar deficits by United States. This paper also analyzes the most important problems, finds similarities between Bretton Woods System and European Monetary System and tries to answer a question if this system or any monetary system like that can be successful on a long term basis.

This diploma thesis includes research in the structural parts of milling machines and designs of a console adjustable. This diploma thesis includes necessary calculations, adjustable worktable assembly drawing, selected drawing documentation, 3D model and model in an immersive virtual reality.

This diploma thesis deals with the design of pneumatic pressure switch with adjustable hysteresis. In the thesis is carried out the introduction in the theory of compressed air and research of the pressure switches at the market. Based on the gathered information and customer specification, the design draft of the pressure switch has been created. In the thesis are described three main parts of the prototype: transform of the pressure, adjustable hysteresis and synchronization of the microswitches. In the end of the thesis is described the testing of prototype and summary of the results.