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The effect of vibrations on the behaviour of lubricated elastohydrodynamic contactsZhang, Xingnan January 2017 (has links)
It is known that rolling element bearings are the second most extensively used machine components in various mechanisms and machines. Consequently, the demand of pursuing higher bearing performance, increased load carrying capacity and prolonged operation life is crucial. The lubrication regime in which rolling element bearings operate is called Elastohydrodynamic Lubrication (EHD). The EHD lubrication regime in steady-state conditions, where working parameters such as load, geometry or speed of the surfaces are constant, is nowadays well understood. Nevertheless, in practice EHD contacts never work in completely steady-state regimes. For example, the contacts of rolling element bearings operating in a machine, which runs at constant speed, has no shock loading from the end effector still experience variable loading when the rolling elements enter and exit the loaded zone and variable speed at the start up and shut down of the machine. Factors related to the working cycle of the machine or mechanism cannot be avoided or simply the start or stop of those will always introduce unsteadiness into the EHD contacts. Vibrations in EHD contacts cause variation of load, and implicitly pressure and contact size, fluctuations of film thickness, which in their turn cause localized fluctuations of the pressure. The vibrational behavior is directly related to noise generation, which significantly influences bearing performance. The current research is focused on the effect of forced harmonic vibrations on oil and grease lubricated EHD contacts. Experiments were carried out using a test rig that simulates real – life EHD contacts by a steel ball on glass disc contact. The method used for measuring the lubricant film thickness was optical interferometry, adapted for the specifics of this research. Lubricant film thickness was measured in systematically – designed tests where a wide range of lubricants and working parameters was employed. The trends of EHD film behaviour under variable loading were evaluated and maps of the likelihood of film thickness perturbation occurrence were drawn for the first time. An analytical model of the lubricant film thickness variation during rapid variation of load was also devised and successfully compared to the experimental findings. The systematic study of the effect of vibrations upon EHD film recovery in limited lubricant supply conditions was also carried out and published. An experimental study on the effect of vibrations was successfully extended into grease-lubricated contacts. The scientific information gained will be a useful tool in the hands of both, lubricants and machine elements producers, with the aim of extending the life expectancy of those elements.
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A BIOMECHANICAL ANALYSIS OF A SPECIALIZED LOAD CARRIAGE TECHNIQUE AND THE DEVELOPMENT OF AN ASSISTIVE LOAD CARRIAGE DEVICEKudryk, IAN 29 September 2008 (has links)
During field observations of professional movers, it was noticed that some experienced movers carried loads posterior to their pelvis. The purpose of this study was two-fold: (1) to assess the biomechanical differences between hand-held load carriage anterior (AC) and posterior (PC) to the pelvis; and, (2) to determine if an assistive load carriage device could reduce muscle effort while carrying loads either anterior or posterior to the pelvis.
In the first laboratory study, an electromyographic (EMG) analysis was conducted while participants carried a load on a treadmill using AC and PC techniques. The subjects conducted three trials of AC and PC techniques while EMG data were being collected. All trial data were normalized to their respective iMVE values. An amplitude probability distribution function (APDF) was used to compare EMG amplitudes between carrying techniques.
Results indicated that PC reduced EMG activity of the erector spinae (>50% reduction), trapezius, and anterior deltoid (p<0.05) as well as increasing EMG activity in the posterior deltoid (p<0.05). Eighty percent of the subjects reported that the PC method felt awkward. Due to its awkwardness, many individuals may not use the PC technique; thus, the second purpose of the study was to design an assistive movers’ pack to aid in AC and PC techniques and make the PC method easier to perform.
In the second study, subjects were asked to walk unloaded while EMG was recorded. The subjects then performed the AC and PC methods with and without the assistive device. All EMG signals were normalized to unloaded gait followed by EMG APDF analyses.
Findings from the first study were confirmed, in that PC, compared to AC significantly reduced erector spinae activity (p<0.05) and focused shoulder activity to the posterior deltoid. Secondly, the assistive device effectively reduced flexor digitorum activity (>40% reduction, p<0.03) and anterior deltoid activity (>75% reduction, p=0.5) in both AC and PC. Erector spinae EMG remained similar to their respective unassisted conditions. The assistive load carriage device may be an effective ergonomic tool in both AC and PC techniques. Subjective surveys indicate that the assistive device decreased the awkwardness in performing the PC technique. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2008-09-29 16:58:19.305
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Hur blir man luleåbo? : Upplevelser av att skapa och bibehålla sociala nätverk som medflyttare till sin partners ursprungliga kommunBorg, Angelica January 2022 (has links)
Under de kommande åren utvecklas ett flertal industrier i Norrbottens län vilket leder till utmaningar med kompetensförsörjning. Satsningarna antas fordra en stor befolkningsökning i länet, en strategi för detta är att locka tillbaka de personer som tidigare lämnat länet, så kallade hemvändare. De familjemedlemmar som flyttar tillsammans med en hemvändare, så kallade medflyttare, kan ställas inför utmaningar att skapa sociala nätverk på den nya platsen. Eftersom medflyttarna har en indirekt koppling till platsen, genom hemvändaren, är deras upplevelser av att skapa sociala nätverk intressanta. Med bakgrund i detta har Luleå kommun gett i uppdrag att studera medflyttares upplevelser av att flytta till kommunen. Det teoretiska begreppet sociala nätverk används för att förstå medflyttarnas upplevelser. Syftet med uppsatsen är att kartlägga sociala nätverk hos vuxna medflyttare som flyttar till sin partners ursprungliga kommun. För att uppfylla syftet har följande frågeställningar utformats: Vilka sociala nätverk skapar respektive bibehåller vuxna medflyttare vid flytten till Luleå? Vilken betydelse upplever vuxna medflyttare att de sociala nätverken har haft för derasvilja att bo kvar i kommunen? Vad anser vuxna medflyttare att arbetsgivare, kommun och andra offentliga institutionerverksamma inom kommunen kan göra för att underlätta för medflyttare att skapa sociala nätverk? Fem vuxna medflyttare intervjuades om deras upplevelser av att flytta till Luleå, de tillfrågades om sina sociala nätverk av grannar, den egna familjen, partnerns familj, vänner och kollegor. De fick också värdera de olika nätverken samt beskriva positiva respektive negativa upplevelser avatt ha kontakt med kommun, arbetsgivare och andra offentliga instanser som verkar i kommunen. Resultaten visar att partnerns nätverk är avgörande för medflyttarnas upplevelser av den första tiden i Luleå men att medflyttarna sedan lösgör sig allt mer från sin partner och skapar egna sociala nätverk. Resultaten visar också att de sociala nätverk som är mest utmanande för medflyttarna att skapa också är de sociala nätverk som är mest betydelsefulla för att de ska vilja stanna kvar i kommunen. Avslutningsvis visar resultaten på att kommunen, arbetsgivares och andra offentliga instansers insatser och aktiviteter påverkar medflyttarnas möjligheter att skapa sociala nätverk. / In the coming years, a number of industries will be developed in Norrbotten County, which pose challenges with the supply of competence. The investments are assumed to require a substantial increase in population in the county, a strategy for this is to attract back the people who havepreviously left the county, so-called returnees. The family members who move together with areturnee, so-called co-movers, may face challenges in creating social networks in the new place. Since the co-movers have an indirect connection to the place, through the returnee, their experiences of creating social networks are interesting. Based on this, Luleå municipality has commissioned a study of co-movers' experiences of moving to the municipality. The theoretical concept of social networks is used to understand the experiences of co-movers. The purpose of the thesis is to map social networks of adult co-movers who move to their partner's native municipality. To fulfill the purpose, the following issues have been formulated: What social networks do adult co-creators create and maintain when moving to Luleå? What significance do adult co-movers contribute to social networks for their desire to stayin the municipality? What do adult co-movers think that employers, municipalities and other public institutionsactive in the municipality can do to make it easier for co-movers to create social networks? Five adult co-movers were interviewed about their experiences of moving to Luleå, they were asked about their social networks of neighbours, their own family, partner's family, friends and colleagues. They also evaluated the various networks and described positive and negative experiences of having contact with the municipality, employers and other public institutions that operate in the municipality. The results show that the partner's network is crucial for the co-movers' experiences during their initial time in Luleå, but that the co-movers then become increasingly detached from their partner and create their own social networks. The results also show that the social networks that are most challenging for co-movers to create are also the social networks thatare most important for their desire to stay in the municipality. The results show that the municipality's, employers' and other public bodies' efforts and activities affect the migrants' opportunities to create social networks.
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PERSONAL RAPID TRANSIT IN UPTOWN CINCINNATI: BROADENING TRAVEL OPTIONSTAMHANE, ASHWINI ANIL January 2006 (has links)
No description available.
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Miljöinriktat Management : Ett paradigm på frammarsch / Environmental Management : A rising paradigmAlaraj, Alexander, Hård, Viktor January 2009 (has links)
Vi har gjort en studie som syftar till att undersöka hur miljödebatten och klimatfrågan påverkat dagens organisationer. I ett led att genomföra studien har vi utgått från vår kvalificerade gissning innebärande att ett nytt paradigm har gett sig till känna. Paradigmet benämns som miljöinriktat management. Vår problemdiskussion utmynnar i frågeställningar om hur organisationer bör hantera uppkomsten av miljöinriktat management. Vidare frågor som berörs är hur ledare bör hantera paradigmskiftet och vilka risker ett utelämnande av miljöinriktat management innebär. Studien är relevant då många organisationer enligt oss idag saknar beredskapsplaner för hur de ska anpassa sig till ett nytt paradigm. Anledningen till att vi vill behandla den här problematiken beror på att vi anser att många organisationers framtida överlevnad kan hänga på att ledarna öppnar sina sinnen för nytänkande. De behöver även upplysas eller påminnas om vad ett paradigmskifte egentligen innebär. Vi är inte ute efter att lösa problemen utan snarare är miljöproblemens karaktär av sådan art att de måste kontrolleras och hanteras. Uppsatsen fokuserar på att skapa en större förståelse inom området. I ett led att samla in information och se vad dagens organisationer har för inställning till det nya paradigmet har vi genomfört tre djupintervjuer enligt en kvalitativ metod. Hanterandet av insamlat material sker genom en abduktiv process för att således få fördjupad kunskap om fenomenet. Vi är alltså inte ute efter att göra anspråk på en allmängiltig sanning. Respondenterna har varit miljöchefer från Volvo personvagnar, Renova samt Gryaab. Resultatet från intervjuerna kopplas samman till de teorier vi behandlat genom ett användande av den narrativa kunskapsformen. I tolkningsarbetet har vi använt Hernadis hermeneutiska triad för att först rekonstruera intervjuerna. Vidare dekonstrueras texten, monteras ned för bland annat finna bakomliggande motiv, för att slutligen konstruera eller författa en egen text inom området. De kunskaper vi erhållit under arbetets gång mynnar ut i en narrativ modell som vi kommit att kalla ”organisationens evolutionsprocess”. Slutsatser som kan dras genom den är att organisationer ständigt påverkas av signaler utifrån av olika karaktär och styrka. Modellen förklarar hur organisationen likt en organism anpassar sig i en evolutionär process till det förändrade landskapet. En organisations grundförutsättning för att hantera processen är flerkretsinlärning som innebär ett kontinuerligt ifrågasättande av verksamhetens operationsregler. Det här är viktigt för att undkomma fällan som rör vanliga tankemönster, det så kallade psykiska fängelset.
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Analýza konkurenční výhody SBU (v organizační struktuře VŠE) / Analysis of the Competitive Advantages of an SBU (within the Organizational Structure of the University of Economics, Prague)Landová, Jana January 2011 (has links)
The goal of this thesis is to define the competitive advantages of a strategic business unit (SBU) that is within the organization structure of the University of Economics, Prague (VŠE). The Central and East European Studies Program (CESP) operates as an SBU within VŠE. This is a one-semester paid program that is part of the of foreign language programs at the university. The program's advantages were defined on the basis of a survey of CESP's competition on the market for free movers in the Czech Republic, a SWOT analysis, and the evaluation of a survey of CESP's students. In the future, CESP should be promoted with a focus on these advantages and the program should be further developed accordingly so as to attract new students to VŠE.
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The Integration Processes of Migrants and Refugees in GermanyFreitas Monteiro, Teresa 02 January 2024 (has links)
In dieser Dissertation untersuche ich verschiedene Aspekte des Integrationsprozesses von Migranten und Flüchtlingen, insbesondere wie sich ihre Präsenz auf die Protestaktivitäten und Einstellungen von Einheimischen auswirkt. Die vier Kapitel bauen auf der bestehenden Literatur auf und zielen darauf ab, diese in mehreren Aspekten zu ergänzen. Das erste und das zweite Kapitel verbessern unser Verständnis der kausalen Auswirkungen der Bedingungen im Heimatland auf die Rückkehrabsichten und die Arbeitsmarktintegration von Migranten im Zielland sowie das Verständnis der Auswirkungen traumatischer Erfahrungen während der Flucht auf die Arbeitsmarktintegration von Flüchtlingen. Das dritte Kapitel befasst sich mit der soziokulturellen Integration von Familienmigranten in einem Land, das nicht ihre erste Wahl darstellt. Das vierte Kapitel untersucht die Auswirkungen der Anwesenheit von Ausländern auf die Protestaktivität einer bestimmten Gruppe von Einheimischen und wie sich diese Proteste auf die Besorgnis über Fremdenfeindlichkeit und Intoleranz auf nationaler Ebene auswirken. Die Ergebnisse der Dissertation sollen die politischen Entscheidungsträger über die potenziellen Nebenwirkungen der Migrationspolitik informieren und empirische Erkenntnisse liefern, die zur Verbesserung bestehender und zur besseren Gestaltung künftiger politischer Maßnahmen beitragen. / In this PhD thesis, I look at different aspects of the integration process of migrants and refugees, and how their presence affects the protest activity and attitudes of natives. The four chapters build on and aim to extend the existing literature along several dimensions. The first and second chapters improve our understanding of the causal effect of home country conditions on migrants' return intentions and labour market outcomes at destination and of the effect of traumatizing experiences along the journey on refugees' labour market integration. The third chapter explores the socio-cultural integration of family migrants in a country that was not their primary choice, while the fourth chapter examines the effect of the presence of foreigners on the protest activity of a particular group of natives and how these protests affect worries about xenophobia and intolerance at the national level. The findings in the dissertation aim to inform policymakers on the potential side-effect of migration policies and to provide empirical evidence that help improve existing policies and better design future ones.eral dimensions.
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Color Feature Integration with Directional Ringlet Intensity Feature Transform for Enhanced Object TrackingGeary, Kevin Thomas January 2016 (has links)
No description available.
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Testování žáků mladšího školního věku z anglického jazyka / Testing Young English Language LearnersURBANOVÁ, Lenka January 2013 (has links)
This diploma thesis deals with the theme of testing young learners in English. The thesis consists of two main parts - theoretical and practical. The theoretical part deals with testing as one form of assessment. Language skills and subskills are studied and Cambridge Young Learners English Tests are described there in detail. This part also tries to find out the answers to essential questions concerning testing. The practical part investigates how the preparation before CYLET tests and their taking influenced the existing level of pupil´s language skills. The second part also asks whether these tests motivate the students for their further development in English. The case study is based on a one-year observation, the results from questionnaires, and an interview with the teacher who prepared pupils for the exam. The thesis is finished by short essay titled: Why are CYLET tests so motivating?
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Hybird Central Solvers for Hyperbolic Conservation LawsMaruthi, N H January 2015 (has links) (PDF)
The hyperbolic conservation laws model the phenomena of nonlinear waves including discontinuities. The coupled nonlinear equations representing such conservation laws may lead to discontinuous solutions even for smooth initial data. To solve such equations, developing numerical methods which are accurate, robust, and resolve all the wave structures appearing in the solutions is a challenging task. Among several discretization techniques developed for solving hyperbolic
conservation laws numerically, Finite Volume Method (FVM) is the most popular. Numerical
algorithms, in the framework of FVM, are broadly classified as upwind and central discretization
methods. Upwind methods mimic the features of hyperbolic conservation laws very well. However, most of the popular upwind schemes are known to suffer from the shock instabilities. Many upwind methods are heavily dependent on eigen-structure, therefore methods developed for one system of conservation laws are not straightforwardly extended to other systems. On the contrary, central discretization methods are simple, independent of eigen-structure, and therefore, are easily extended to other systems.
In the first part of the thesis, a hybrid central discretization method is introduced for Euler equations of gas dynamics. This hybrid scheme is then extended to other hyperbolic conservation laws namely, shallow water equations of oceanography and ideal magnetohydrodynamics equations. The baseline solver for the new hybrid scheme, Method of Optimal Viscosity for Enhanced Resolution of Shocks (MOVERS), is an accurate scheme capable of capturing grid aligned steady discontinuities exactly. This central scheme is free from complicated Riemann solvers and therefore is easy to implement. This low diffusive algorithm produces sonic glitches at the expansion regions involving sonic points and is prone to shock instabilities. Therefore it requires an entropy fix to avoid these problems. With the use of entropy fix the exact discontinuity capturing property of the scheme is lost, although sonic glitches and shock instabilities are avoided. The motivation for this work is to develop a numerical method which exactly preserves the steady contacts, is accurate, free of multi-dimensional shock instabilities and yet avoids the entropy fix. This is achieved by constructing a coefficient of numerical diffusion based on pressure gradient sensor. The pressure gradients are known to detect shocks and they vanish across contact discontinuities. This property of pressure sensor is utilized in constructing the coefficient of numerical diffusion. In addition to the numerical diffusion of the baseline solver, a numerical diffusion based on the pressure sensor, scaled by the maximum of eigen-spectrum, is used to avoid shock instabilities. At contact discontinuities, pressure gradients vanish and coefficient of numerical diffusion of MOVERS is automatically retained to capture steady contact discontinuities exactly. This simple hybrid central solver is accurate, captures steady contact discontinuities exactly and is free of multi-dimensional shock instabilities. This novel method is extended to shallow water and ideal magnetohydrodynamics equations in a similar way.
In the second part of the thesis, an entropy stable central discretization method for hyperbolic conservation laws is introduced. In a quest for optimal numerical viscosity, development of entropy stable schemes gained importance in recent times. In this work, the entropy conservation equation is
used as a guideline to fix the coefficient of numerical diffusion for smooth regions of the flow. At the large gradients, coefficient of numerical diffusion of baseline solver is used. Switch over between smooth and large gradients of the flow is done using limiter functions which are known to distinguish between smooth and high gradient regions of the flow. This simple and stable central scheme termed MOVERS-LE captures grid aligned steady discontinuities exactly and is free of shock instabilities in multi-dimensions. Both the above algorithms are tested on various well established benchmark test problems.
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