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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.
21

Constructing quasi-linear oxygen uptake responses from non-linear parameters

Wilcox, Samuel L. January 1900 (has links)
Master of Science / Department of Kinesiology / Thomas J. Barstow / Purpose: Oxygen uptake (VO2) has been shown to be controlled by a nonlinear system, yet the VO2 response to ramp style exercise appears linear. We tested the hypothesis that an integrative model incorporating nonlinear parameter values could accurately estimate actual VO2 responses to ramp style exercise. Methods: Six healthy, men completed three bouts of varying ramp rate exercise (slow ramp (SR): 15 W/min, regular ramp (RR) 30 W/min, fast ramp (FR) 60W/min) and four bouts of extended-step incremental exercise, where each step lasted 5-15 min or until volitional fatigue on a cycle ergometer on separate days. The step-responses were then fit with a simple monoexponential starting at time zero (MONO) or allowing a time delay and using only the first 5 min of data (5TD). The resulting VO2 parameters from the step protocol were incorporated into an integrative model for the estimation of the VO2 response to each of the rates of ramp incremental exercise. The parameters from the actual and model ramp protocols were compared with 2 way repeated-measures ANOVAs. Results: Both Gain (G) and Mean Response Time (MRT) (or time constant) values increased significantly across work rate transitions (mean±SD; Gain:10.0±0.9, 11.6±1.1, 13.1±1.3, 17.6±3.3 ml O2/min/W; MRT:39.4±7.7, 54.0±5.4, 79.6±15.0, 180.1±56.2 s). Up to maximalVO2 the models over-estimated the actual VO2 response for FR (Gain: ACT 8.7±1.0, MONO 9.9±0.4, 5TD 10.3±0.3 ml O2/min/W). Up to 80% maximal VO2 the models accurately predicted the actual VO2 response across all ramp rates (Gain: ACT 10.7±1.1, 10.2±0.5, 9.2±1.0; MONO 11.0±0.8, 10.3±0.6, 9.2±0.5; 5TD 10.4±0.4, 10.2±0.3, 9.8±0.2 ml O2/min/W, values are listed SR,RR,FR). Conclusions: When variable parameter values (G and either MRT or time constant and time delay) were utilized by an integrative model, accurate estimations of the VO2 response to ramp incremental exercise were possible regardless of ramp rate (up to 80% maximal VO2). The increases in both G and MRT (or time constant) appear to balance each other to produce the quasi-linear VO2 responses.
22

Étude numérique de l’interaction choc/couche limite en géométrie de révolution / Numerical Study of Shock/Boundary Layer Interaction on a Cylindrical Configuration

Nakano, Tamon 12 September 2018 (has links)
Les phénomènes d’interactions choc/couche limite sont dimensionnants pour de nombreuses applications des domaines de l’aéronautique et du spatial. Ils peuvent être associés à la formation de décollements instationnaires à basse fréquence qui n’ont été étudiés jusqu’à présent qu’en géométrie plane. La présente étude vise à caractériser ce type d’interaction en configuration cylindrique. Un outil de simulation numérique directe,basé sur l’extension de schémas hybrides aux différences finies de haute précision (centrés optimisés6/WENO 5) en géométrie curviligne, a été développé et validé à travers divers cas test standards. Une première partie de l’étude se focalise sur l’influence d’un effet de courbure transverse sur le développement des propriétés d’une couche limite supersonique à Mach 3. Il est montré que l’augmentation de la courbure relative de la couche limite tend à réduire l’énergie de fluctuation à basse fréquence près de la paroi, tout en renforçant les perturbations à hautes fréquences dans la zone externe de la couche limite. En comparaison avec le cas plan, la courbure transverse induit une ré-organisation notable des structures de la couche limite et un comportement différent des invariants d’anisotropie des contraintes, mais ne conduit qu’à une légère modification des distributions de contraintes et de l’équilibre global d’énergie cinétique turbulente. Une seconde partie de l’étude se concentre sur la zone d’interaction avec une rampe de compression et le mouvement instationnaire du choc en géométrie de révolution complète. La déformation azimutale du choc est caractérisée dans son mouvement. Elle apparaît essentiellement associée à la fluctuation de la ligne de décollement et l’organisation des structures tourbillonnaires amont. Il est montré que l’énergie des modes azimutaux de pression pariétale fluctuante est plus amplifiée pour les modes d’ordre plus élevé. La contribution à l’effort latéral associé au mode 1 apparaît plus particulièrement marquée à basses fréquences dans la zone amont au point de décollement et à moyennes fréquences en aval de la zone de recollement sur la rampe où les niveaux les plus élevés de fluctuations sont observés. Il est montré que les fluctuations à basses fréquences sont en revanche portées par des modes azimutaux d’ordre de plus en plus élevé à travers la zone d’interaction. / Shock wave/boundary layer interactions (SWBLI) are present in various aerospace engineering applications.They can be associated with separated regions yielding low-frequency unsteadiness, which have mainly been studied in planar geometries. The present study aims at characterizing this type of interaction in a cylindrical configuration. A direct numerical simulation solver has been developed and validated with various test cases. It is based on a high-order finite difference based hybrid schemes (6th order centered scheme/5thorder WENO), extended to curvilinear geometries. Transverse curvature effects on properties of spatially developing supersonic boundary layer at Mach 3 are first examined. It is shown that the increase of the relative curvature of the boundary layer tends to reduce the fluctuation energy at lower frequencies near the wall, while reinforcing the perturbations at higher frequencies in the upper zone of the boundary layer.In comparison with the planar case, the transverse curvature leads to a significant re-organization of the boundary layer structures and a subsequent modified behavior of the invariants of anisotropy turbulent stress tensor. It however only leads to slightly modified distributions of Reynolds stress and a rather similar overall balance of turbulent kinetic energy through the boundary layer. The second part of this study is dedicated to the unsteady motions of the shock/separation zone in a cylinder/compression flare configuration for which the full cylindrical geometry is taken into account. The shock distortions in the azimutal direction appears to be mainly associated to the organization of the upstream vortex structures and the subsequent azimutal fluctuations of the separation line. It is shown that the energy of the fluctuating wall pressure is more amplified for higher order azimutal modes. The contributions to lateral forces, associated to the first mode, are dominated by low-frequencies only upstream of the separation line in the intermittent region. They become more dominant in the middle frequency range downstream of the reattachment zone on the ramp. It is also shown that the low-frequency activity at the wall is progressively due to higher order azimuthal modes through the interaction zone.
23

Confidential and Resilient Store of Persistent Web Objects

Mohan, Anoop 01 January 2009 (has links)
Persistent and secure store for web objects is an attractive feature in today?s web world and possess a good potential for exploration. Persistence of a storage mechanism refers to its ability to store an object for extremely long time periods. Resilience refers to its fault tolerance ability or its ability to retrieve the object completely even if a part of that object is lost due to any catastrophic failures like disk failure. It is also important that this storage mechanism is able to store this object in a secure manner. In the current world, usability of any storage mechanism is enhanced multiple times if it could be used from a web interface. This thesis considers different techniques that provide these properties and proposes a storage mechanism that makes use of information dispersal techniques that is suited to store data securely, with an emphasis on availability and resilience. A working prototype of this storage mechanism was developed as a part of this thesis and is made available as a library for program developers. This library provides APIs to store and retrieve data as well as a daemon for error control. The APIs to store and retrieve data also accepts HTTP requests, which increase its usability to web developers. The performance of this prototype was measured and is presented using graphs. Finally a demonstration of the applications of this prototype is also provided.
24

Evaluation of the mobility impacts of proposed ramp metering and merge control systems : an Interstate 35 case study

DeGaspari, Michael 05 March 2013 (has links)
Increasing demand on freeway facilities is a major challenge facing urban areas in the United States and throughout the world. Active Traffic Management (ATM) strategies can be used to increase the performance of these facilities through improved operations without the significant expenditure associated with adding capacity. One ATM strategy that has been widely deployed in the current state of practice is ramp metering, which controls the traffic demand placed on a freeway. Merge control strategies are less prevalent and largely undeveloped. This study examines the recurrently congested northbound section of Interstate Highway 35 that approaches downtown Austin, Texas. Using the VISSIM microsimulation platform, a model of this segment was developed and calibrated to reflect current peak-hour congestion. Within this model, ramp metering and merge control technologies were implemented. The impacts on traffic throughput, speed and travel time for each of these proposed systems are evaluated. / text
25

A microsimulation analysis of the mobility impacts of intersection ramp metering

Wall, William Jared 24 March 2014 (has links)
Urban freeway demand that frequently exceeds capacity has caused many agencies to consider many options to reduce congestion. A series of solutions that falls under the Active Traffic Management (ATM) banner have shown promising potential. Perhaps the most popular ATM strategy is ramp metering. Ramp metering involves limiting the access of vehicles to freeways at an entrance ramp. By doing this, freeway throughput, speeds, and travel time reliability can be increased, while the number of traffic incidents can be decreased. This study examines the application of an innovative ramp metering strategy, Intersection Ramp Metering (IRM), at a section of Loop 1 in Austin, TX. IRM implements the ramp metering function at the intersection immediately upstream of the entrance ramp, rather than on the ramp itself. A microsimulation analysis of this application is performed in VISSIM, and the results confirm that freeway throughput (+10%), and system average travel time (-14%), can be improved, as well as several other performance measures. / text
26

Estudo do sinal eletromiográfico em exercícios isométricos em diferentes velocidades de contração /

Fioramonte, Isabela Soares Kishi. January 2011 (has links)
Orientador: Rúben de Faria Negrão Filho / Banca: Fabio Micolis de Azevedo / Banca: Diego Basile Colugnati / Resumo: A velocidade de contração é um importante fator de interferência na relação entre força e eletromiografia. O presente trabalho visa promover uma melhor compreensão da relação EMG x força no quesito velocidade de contração. Foi coletado o sinal eletromiográfico de superfície do músculo bíceps braquial de dez voluntários. Os sujeitos realizaram três CIVM, onde a média das três foi considerada a capacidade máxima de força gerada pelo indivíduo sendo utilizada para a normalização dos valores de RMS. Em seguida os sujeitos foram orientados a realizar 10 contrações isométricas em rampa e 10 contrações isométricas em degrau de maneira aleatória com sobrecarga de 40% da CVM. Nos exercícios em rampa a força era incrementada de maneira gradativa de 0 a 40% da CVM, e nos exercícios em degrau o indivíduo era orientado a incrementar a força em sua máxima velocidade de contração, em ambas as velocidades de contração o voluntário realizava os exercícios com encorajamento verbal e "feedback" visual na tela do computador. Resultados: o tempo de subida em degrau variou significantemente, o aumento dos valores de RMS em rampa e em degrau foi gradativo, porém em rampa foi maior do que em degrau. O resultado neste trabalho nos permite concluir que há diferenças quando se aplica diferentes velocidades de contração. Sendo que essas diferenças podem indicar um maior recrutamento de fibras do tipo II e ativação muscular nos exercícios em rampa e que esse recrutamento pode ser gradativo. / Abstract: Filho, Presidente Prudente, 2011. The speed of contraction is an important factor that influences the relationship between strength and electromyography. The present work aims to promote a better understanding of the relation x EMG power in the issue of contraction speed. We collected surface electromyographic signal of the biceps brachii ten volunteers. The subjects performed three MVC, where the average of the three was considered the maximum force generated by person being used for the normalization of the RMS values. Then the subjects were instructed to perform 10 isometric ramps and step isometric 10 randomly loaded with 40% of MVC. In the exercise on ramp the force was increased will gradually from 0 to 40% of MVC, and exercises on step the individual was instructed to increase the force at its maximum speed of contraction in both the voluntary contraction speeds perform the exercises with verbal encouragement and visual feedback on the computer screen. Results: the ascent time in step varied significantly, the increase of RMS values in step and ramp were gradual, but a ramp was higher than in step. The result of this work allows us to conclude that there are differences when applying different speeds of contraction. Since these differences may indicate a higher recruitment of type II fibers and muscle activation exercises ramp and that recruitment may be gradual. / Mestre
27

Nájezdy pro přívěs pro přepravu stavebních strojů / Ramps for trailer for buildings machines transport

Dvořáček, Michal January 2010 (has links)
The aim of my dissertation on the subject of raids on trailer for transport of construction equipment is to propose a functional concept of rear split folding ramps for trailer construction machines with tracked and wheeled landing gear. Raids are designed as a two-part, hydraulically tilting. With an appropriate mechanism to ensure a correct function of the ramp end part at tilting. Maximum weight of the machine is 21 000 kg and departure angle is 10 °. This thesis was composed with cooperation SVAN ltd.
28

Strängnäs City Hall / Strängnäs City Hall

Jalas, Veronika January 2019 (has links)
Strängnäs City Hall is a place for the people of Strängnäs to come together. The building is separated into two parts, one part for the people working in the building and one part for the public. The part for the workers consists of a traditional brick building with views overlooking the harbor. The public part has a glass facade, inviting people into the building. Inside the visitor moves through a café into the exhibition hall, up a ramp to the chambers, and further up to the restaurant with the rooftop terrace. The ramp connects the public part to the private part of the building on each level, both physically and visually, bringing the politicians and the residents of Strängnäs together. / Strängnäs stadshall är en plats där folket i Strängnäs kommer samman för att mötas. Byggnaden består av två delar, en för de som arbetar i stadshallen, och en för besökare. Delen för dem som arbetar i stadshallen består av en traditionell tegelbyggnad, med god utsikt över hamnen. Den allmänna delen har en glasfasad som ska bjuda in folket i byggnaden. Besökaren rör sig genom caféet till utställningshallen, och därifrån uppåt med en ramp till plenisalen och vidare upp till restaurangen med takterass. Denna rampen kopplar den publika delen med den privata, både fysiskt och visuellt, och för på så sätt samman politikerna med invånarna av Strängnäs.
29

Learning and reuse of engineering ramp-up strategies for modular assembly systems

Scrimieri, Daniele, Oates, R.F., Ratchev, S.M. 04 March 2020 (has links)
Yes / We present a decision-support framework for speeding up the ramp-up of modular assembly systems by learning from past experience. Bringing an assembly system to the expected level of productivity requires engineers performing mechanical adjustments and changes to the assembly process to improve the performance. This activity is time-consuming, knowledge-intensive and highly dependent on the skills of the engineers. Learning the ramp-up process has shown to be effective for making progress faster. Our approach consists of automatically capturing information about the changes made by an operator dealing with disturbances, relating them to the modular structure of the machine and evaluating the resulting system state by analysing sensor data. The feedback thus obtained on applied adaptations is used to derive recommendations in similar contexts. Recommendations are generated with a variant of the k-nearest neighbour algorithm through searching in a multidimensional space containing previous system states. Applications of the framework include knowledge transfer among operators and machines with overlapping structure and functionality. The application of our method in a case study is discussed. / Funded by the European Commission as part of the 7th Framework Program under the Grant agreement CP-FP 229208-2, FRAME project.
30

Simulation-Based Integrated Control Algorithm for Controlling Shockwave Propagation on Freeways and Queue Spillback at On-ramps

Allam, Karteek Kumar January 2015 (has links)
No description available.

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