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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.
11

Conformal Vector Fields With Respect To The Sasaki Metric Tensor Field

Simsir, Muazzez Fatma 01 January 2005 (has links) (PDF)
On the tangent bundle of a Riemannian manifold the most natural choice of metric tensor field is the Sasaki metric. This immediately brings up the question of infinitesimal symmetries associated with the inherent geometry of the tangent bundle arising from the Sasaki metric. The elucidation of the form and the classification of the Killing vector fields have already been effected by the Japanese school of Riemannian geometry in the sixties. In this thesis we shall take up the conformal vector fields of the Sasaki metric with the help of relatively advanced techniques.
12

The Efficacy of Incorporating Partial Squats in Maximal Strength Training

Bazyler, Caleb D., Sato, Kimitake, Wassinger, Craig A., Lamont, Hugh S., Stone, Michael H. 01 November 2014 (has links)
The efficacy of incorporating partial squats in maximal strength training. J Strength Cond Res 28(11): 3024–3032, 2014—The purpose of our study was to examine the effects of 2 different training methods on dynamic and isometric measures of maximal strength. Seventeen recreationally trained men (1 repetition maximum [1RM] squat: 146.9 ± 22.4 kg) were assigned to 2 groups: full range of motion (ROM) squat (F) and full ROM with partial ROM squat (FP) for the 7-week training intervention. Repeated measures analysis of variance revealed that there was a statistically significant group-by-time interaction for impulse scaled at 50, 90, and 250 milliseconds at 90° of knee flexion and rate of force development at 200 milliseconds with 120° of knee flexion (p ≤ 0.05). There was also a statistically significant time effect (p ≤ 0.05) for the 1RM squat, 1RM partial squat, isometric squat peak force allometrically scaled (IPFa) 90°, IPFa 120°, and impulse allometrically scaled at 50, 90, 200, and 250 milliseconds at 90° and 120° of knee flexion. Additionally, the FP group achieved statistically larger relative training intensities (%1RM) during the final 3 weeks of training (p ≤ 0.05). There was a trend for FP to improve over F in 1RM squat (+3.1%, d = 0.53 vs. 0.32), 1RM partial squat (+4.7%, d = 0.95 vs. 0.69), IPFa 120° (+5.7%, d = 0.52 vs. 0.12), and impulse scaled at 50, 90, 200, and 250 milliseconds at 90° (+6.3 to 13.2%, d = 0.50–1.01 vs. 0.30–0.57) and 120° (+3.4 to 16.8%, d = 0.45–1.11 vs. 0.08–0.37). These larger effect sizes in the FP group can likely be explained their ability to train at larger relative training intensities during the final 3 weeks of training resulting in superior training adaptations. Our findings suggest that partial ROM squats in conjunction with full ROM squats may be an effective training method for improving maximal strength and early force-time curve characteristics in men with previous strength training experience. Practically, partial squats may be beneficial for strength and power athletes during a strength-speed mesocycle while peaking for competition.
13

Navrhování konstrukcí vozovek pomocí dimenzačního programu Alize / Design of road constructions with the programme Alize

Grošek, Jiří January 2013 (has links)
This master’s thesis deals with the analysis of stress, fatigue and the assessment of frost effects in program ALIZE as it is prescribed in norm NFP 98-086 and comparing with the regulation TP 170 Designing roadways of roads and program LayEps.
14

Dynamic characterization and analysis of aerial lifts

Hernandez, Eileen Cynthia 14 November 2012 (has links)
Aerial lifts are used to elevate people and material to high heights. There are many different types of aerial lifts which have vastly different dynamics characteristics. Thus, a new categorization for aerial lifts was created and organizes them by their kinematics. Many accidents occur while using aerial lifts. Hazards of aerial lifts and current solutions to those hazards were reviewed to understand the causes of the accidents. Some major accidents are due to the complex dynamics and flexibility of aerial lifts, such as oscillations and tip-overs. Oscillations of full-size aerial lifts were experimentally tested to determine frequencies in different configurations. Machine-motion induced oscillations of an articulating aerial lift were simulated and analyzed for both non-overcenter and overcenter configurations. Input shaping was used to achieve reduction in machine-motion induced oscillations. Tip-over stability margin was used to simulate and analyze the stability of both non-overcenter and overcenter configurations. The effect of increased platform mass on tip-over stability margin was also analyzed. The results in this thesis are a categorization of aerial lifts including their hazards and methods of reducing those hazards, an experimental verification of the dynamic response of full-size aerial lifts, a fully dynamic tip-over prediction model of double-boom articulating aerial lift by applying flexibility in the joints and realistic velocity profiles, and a detailed study of the dynamics of a double-boom articulating aerial lift.
15

Contribuição ao projeto de circuitos integrados de reguladores de tensão com charge pump em tecnologia CMOS : aceleração do tempo de partida, redução do ripple, redução do efeito kick-back e técnica indireta de medida da tensão de saída / Contribution to the integrated circuit design related to voltage regulator with charge pump circuit embedded in CMOS technology : fast startup improvement, ripple and kick-back effect reduction and new techinique of indirect output voltage measurement

Terçariol, Walter Luis, 1975- 12 December 2014 (has links)
Orientador: José Antonio Siqueira Dias / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-26T13:53:46Z (GMT). No. of bitstreams: 1 Tercariol_WalterLuis_D.pdf: 1322557 bytes, checksum: 4f45518a1a62907cd9a61afa627408c3 (MD5) Previous issue date: 2014 / Resumo: Este trabalho visa compilar três contribuições na melhoria dos projetos de reguladores de tensão com unidades de bombeamento de carga embutidos (células elevadoras de tensão Dickson - BC). A primeira aborda uma técnica inovadora de arranque na partida deste módulo elevador quando habilitado. Este projeto se refere à aceleração da inicialização do modulo BC, tendo como objetivo a diminuição do intervalo de tempo da rampa ascendente da tensão de saída Vo até atingir o nível alvo de regulação. A técnica consiste em gerenciar o aumento da freqüência do relógio de bombeamento entregue as unidades de bombeamento durante a fase de subida, quando a regulação estiver estabelecida o sistema se regenera voltando ao estado original de freqüência de bombeamento natural. Uma segunda proposta inovadora de projeto é referente à homogeneização e redução da aleatoriedade da ondulação da tensão de saída Vo, referente ao regulador com o modulo BC embutido, baseado em comparadores com trava, com proposta de redução do erro de comparação devido ao efeito aleatório durante o estagio de comparação comumente encontrado neste tipo de abordagem, a técnica consiste em suprimir o acoplamento capacitivo nocivo durante a fase de isolamento elétrico no processo de comparação mantendo o espelho de corrente do comparador na região de saturação. Esta técnica visa proporcionar uma redução significativa da capacitância de desacoplamento utilizada para filtragem da tensão Vo. Uma terceira e última contribuição é referente a uma inovadora técnica de medição indireta da tensão de saída Vo do regulador com módulo BC baseada em uma medida simples e precisa dos pares tensão da porta e fonte (VPS) e corrente elétrica do dreno (Idreno) de um dispositivo NMOS de alta tensão adicionado de modo que duas tensões conhecidas (preestabelecidas) são aplicadas na porta do dispositivo e as respectivas correntes de dreno são mensuradas e uma terceira desconhecida (oriunda do regulador elevador BC) desconhecida pode ser extrapolada de forma simples. Esta técnica visa ser útil para medição de reguladores de baixa potencia pois o carregamento do regulador (Vo) é quase nulo.Todas as inovações e melhorias propostas foram analisadas em veículos de teste (silício) e com as provas de conceito, feitas em simulações elétricas / Abstract: This work aims to compile contributions in improving designs based on voltage regulators with voltage elevator with built-in charge pump CP. The first deals with an innovative technique rump-up this module when enabled. This project refers to the acceleration of startup the CP module, aiming at the reduction of the period of stabilization of the ramp output voltage Vo to the level of regulation target. The technique is to manage increasing the frequency of pumping clock during the phase of rump up and when the setting established the system regenerates back to the original state pumping frequency. A second innovative project proposal was made on the homogenization and reduction of the ripple of the output voltage Vo, referring to the regulator with the |CP module, based on latch comparators , alignment error reduction proposal because of the random effect during the stage comparison commonly found in this type of approach, the technique is to remove the harmful capacitive coupling during electrical isolation phase on the comparison keeping the comparator current mirror in saturation region. This technique aims to provide a significant reduction in the decoupling capacitance used for filtering the voltage Vo. A third and final contribution is related to an innovative technique of indirect measurement of the output voltage Vo of the regulator module CP, based on a simple and accurate measure of the gate voltage and couples the drain electric current of a high voltage NMOS device / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica
16

Řízení modelu výtahu s průmyslovou sběrnicí AS-Interface / Control of lift model with the fieldbus AS-Interface

Goryl, Stanislav January 2014 (has links)
The aim of the master thesis is to create and verify the control algorithm of a personal lift. First part of the thesis focuses on a literature review investigating the requirements for personal lifts. Based on the information found in the review, selected measures were implemented in the model so that it would be the most suitable to the requirements for personal lifts. A brief introduction of the lift and its norms is followed by a description of the programme and control algorithm, including the description of the used add-on instructions. Last part describes the visualization which is used to control the lift model. In addition to controlling, the visualization provides statistical data, the current status of the programme and information about the set parameters, inputs, outputs and faults.
17

Hur MDR påverkar tillverkare av personlyftar och rullstolar - Standarder och upphandlingskrav / Influences of MDR on Manufacturers of Patient Lifts and Wheelchairs - Standards and Procure Requirements

Wronska, Sofia January 2023 (has links)
Sedan 2021 regleras medicintekniska produkter inom EU av förordningen MDR (EU 2017/745). Det primära syftet med regelverket är att säkerställa ändamålsenliga produkter med hög säkerhet. Det nya regelverket ställer högre krav på företag som tillverkar medicintekniska produkter samt andra aktörer inom den medicintekniska industrin. De mer omfattande kraven innebär att det blir mer utmanande att uppfylla samtliga kriterier som krävs för att kunna lansera medicintekniska produkter på unionsmarknaden. Detta examensarbete har undersökt hur företag som tillverkar specifika medicintekniska produkter som rullstolar och personlyftar upplever förutsättningarna för att nå marknaden. För att undersöka tidigare studier kring ämnet har en litteraturstudie genomförts och sedan utformades intervjufrågor med hjälp av samtliga handledare. Frågorna besvarades av företag som tillverkar rullstolar eller personlyftar. Som komplement till de semistrukturerade intervjuerna har upphandlingar undersökts med syfte att kartlägga vilka standarder som refereras till som skall-krav vid inköp av rullstolar och personlyftar. Resultatet visar att de ökade kraven påverkar större medicintekniska företag, men att mindre företag påverkas i högre utsträckning enligt intervjuobjekten. Dessutom noteras att standarder nämns mindre frekvent i upphandlingar än vad de intervjuade personerna hävdar. Slutligen anser intervjuobjekten att det är värdefullt att följa standarder vid utveckling och marknadsföring av personlyftar och rullstolar. / Since 2021, the Medical Device Regulation (MDR) has regulated medical devices within the EU (EU2017/745). The regulation’s primary purpose is to ensure fit-for-purpose products with high safety standards. The new regulatory framework imposes strict requirements on companies manufacturing medical devices and other actors within the medical device industry. The more extensive requirements make meeting all the criteria necessary for launching medical devices on the European Union market more challenging. This thesis has examined how companies that manufacture medical devices, especially wheelchairs and patient lifts, perceive the conditions for reaching the market. A literature review was conducted to examine previous studies on the subject. Then, interview questions were formulated with the assistance of supervisors to participate by companies manufacturing wheelchairs or patient lifts. Procurements were examined to complement the semi-structured interviews and map out which standards are mandatory requirements in procuring wheelchairs and patient lifts. The results indicate that the increased requirements affect larger medical device companies, but the interviewees say smaller companies are more affected.  Additionally, standards are mentioned less frequently in procurements than what the interviewed individuals claim. Finally, the semi-structured interviews revealed that the interviewees consider it valuable to adhere to standards in developing and marketing wheelchairs and patient lifts.
18

Preventing Back Injury in Caregivers

Dutta, Tilak 21 August 2012 (has links)
Caregivers injure their backs more than workers in any other industry. Efforts to reduce injuries have been on-going for decades with limited results. Mechanical lift devices have been incorporated into clinical practice over the past 30 years to reduce the risk of injury from patient lifting. Yet injury rates remain high. The use of mechanical lifts may be partly to blame. While these devices assist with lifting patients, they also introduce new activities that result in caregivers experiencing unsafe loading on the spine. We measured loads on the lower back during manoeuvres of the two most common lift types (overhead and floor) as well as during sling insertion. A new device called SlingSerterTM was evaluated for use in the clinical environment. We also investigated spine shrinkage as a measurement tool for estimating cumulative load. Caregivers worked alone and in pairs for both lift maneuvering and sling insertion activities. Overhead lift use resulted in much lower loads than floor lift use. We conclude caregivers can safely operate overhead lifts alone, while floor lift use remained unsafe even with two caregivers. Less-experienced caregivers had higher loads than more-experienced counterparts when using floor lifts. There was no corresponding effect of experience with overhead lift use and we found this to be a further benefit of overhead lifts over floor lifts. Most caregivers exceeded the safe limit for spine compression during sling insertion, though a single caregiver was at no higher risk of injury than two caregivers working together. Clinicians who tested SlingSerterTM agreed the device would be useful in clinical practice, particularly with bariatric patients and other special patient populations that are difficult to roll or turn. Finally, we investigated a novel method for estimating cumulative load based on spine shrinkage. There is growing recognition that excess cumulative load may be responsible for back injury. We found the variability in spine shrinkage was too large to estimate cumulative load directly. However, the technique may still be useful for determining the relative importance of the load from different activities to the cumulative total.
19

Preventing Back Injury in Caregivers

Dutta, Tilak 21 August 2012 (has links)
Caregivers injure their backs more than workers in any other industry. Efforts to reduce injuries have been on-going for decades with limited results. Mechanical lift devices have been incorporated into clinical practice over the past 30 years to reduce the risk of injury from patient lifting. Yet injury rates remain high. The use of mechanical lifts may be partly to blame. While these devices assist with lifting patients, they also introduce new activities that result in caregivers experiencing unsafe loading on the spine. We measured loads on the lower back during manoeuvres of the two most common lift types (overhead and floor) as well as during sling insertion. A new device called SlingSerterTM was evaluated for use in the clinical environment. We also investigated spine shrinkage as a measurement tool for estimating cumulative load. Caregivers worked alone and in pairs for both lift maneuvering and sling insertion activities. Overhead lift use resulted in much lower loads than floor lift use. We conclude caregivers can safely operate overhead lifts alone, while floor lift use remained unsafe even with two caregivers. Less-experienced caregivers had higher loads than more-experienced counterparts when using floor lifts. There was no corresponding effect of experience with overhead lift use and we found this to be a further benefit of overhead lifts over floor lifts. Most caregivers exceeded the safe limit for spine compression during sling insertion, though a single caregiver was at no higher risk of injury than two caregivers working together. Clinicians who tested SlingSerterTM agreed the device would be useful in clinical practice, particularly with bariatric patients and other special patient populations that are difficult to roll or turn. Finally, we investigated a novel method for estimating cumulative load based on spine shrinkage. There is growing recognition that excess cumulative load may be responsible for back injury. We found the variability in spine shrinkage was too large to estimate cumulative load directly. However, the technique may still be useful for determining the relative importance of the load from different activities to the cumulative total.

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