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Pereira, E. "Adaptive closed-loop control of arterial pressure during anaesthesia." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379565.
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Woo, Youngjin. "Inelastic Analysis of the Loop Tack Test for Pressure Sensitive Adhesives." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29237.
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A numerical analysis of the loop tack test is presented to study the behavior of the strip and the influence of several factors, and the results are compared with experimental ones. The numerical results can be applied to model the performance of a pressure sensitive adhesive (PSA). Since the simulation of the loop tack test includes geometrical and material nonlinearities, it is solved numerically by the finite element method. The finite element program ABAQUS is used throughout the research. As the teardrop shaped loop is pushed down onto the adhesive and then pulled up, the variation of the loop behavior is investigated using two-dimensional (2D) and three-dimensional (3D) models. A bilinear elastic-plastic constitutive law is used for the strip. The deformation of the pressure sensitive adhesive is approximated as uniaxial extension of independent adhesive strands. A Winkler-type nonlinear elastic foundation and a viscoelastic foundation are used to model the PSA. A nonlinear elastic spring function is used, which is composed of a compression region for the bonding phase and a tension region for the debonding phase. A debonding failure criterion is assumed, in which an adhesive strand will debond when it reaches a certain length. During the bonding phase, it is assumed that the loop is perfectly bonded, and the contact time is not included. Curves of the pulling force versus the top displacement (i.e., tack curves) are obtained throughout the simulation. A parametric study is made with respect to the nonlinear spring function parameters, experimental uncertainties, and strip thickness. Anticlastic bending behavior is shown in the 3D analysis, and the contact patterns are presented. The effects of the elasticity modulus of the PSA for the elastic foundation and the displacement rate for the viscoelastic model are investigated.Ph. D.
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Williams, NuRocha Lyn. "Elastic Analysis of the Loop Tack Test for Pressure Sensitive Adhesives." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33983.
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The loop tack test measures the tack (instant grip) of an adhesive. An analytical model of
this test seems to be lacking and is the subject of this research. The strip is investigated
using several mathematical formulations, and the solutions are obtained numerically.
The loop is created from a flexible elastic strip that is bent into a teardrop shape, with its
ends clamped together. The strip is tested in a cycle, in which the loop is first pushed
onto the surface, compressing the adhesive. Then the loop is pulled up, and gradually
debonds from the substrate. The loop is assumed to be nonlinearly elastic and
inextensible.
The mechanics of the loop tack test are studied in order to determine the impact of
various factors on adhesive performance. These factors include the stiffness of the
backing, the stiffness and thickness of the adhesive, the elongation of the adhesive before
debonding, and the contact time.
The relationship between the applied force and the vertical deflection of the loop's ends
is determined, as well as that between the applied force and the contact length. Also, the
maximum "pull - off" force needed to remove the substrate from the loop is obtained
from the results. Shapes of the loop during the cycle are found.
This research will increase understanding of the behavior of the adhesive and backing
during the loop tack test. With the computer model that has been developed, any set of
parameters and conditions can be analyzed, and improvements can be made in the test
procedure.Master of Science
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HAMDAN, MOHAMMAD OMAR. "LOOP HEAT PIPE (LHP) MODELING AND DEVELOPMENT BY UTILIZING COHERENT POROUS SILICION (CPS) WICKS." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1049987207.
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Ma, Jinge. "Design of Frequency Output Pressure Transducer." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804933/.
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Piezoelectricity crystal is used in different area in industry, such as downhole oil, gas industry, and ballistics. The piezoelectricity crystals are able to create electric fields due to mechanical deformation called the direct piezoelectric effect, or create mechanical deformation due to the effect of electric field called the indirect piezoelectric effect. In this thesis, piezoelectricity effect is the core part. There are 4 parts in the frequency output pressure transducer: two crystal oscillators, phase-locked loop (PLL), mixer, frequency counter. Crystal oscillator is used to activate the piezoelectricity crystal which is made from quartz. The resonance frequency of the piezoelectricity crystal will be increased with the higher pressure applied. The signal of the resonance frequency will be transmitted to the PLL. The function of the PLL is detect the frequency change in the input signal and makes the output of the PLL has the same frequency and same phase with the input signal. The output of the PLL will be transmitted to a Mixer. The mixer has two inputs and one output. One input signal is from the pressure crystal oscillator and another one is from the reference crystal oscillator. The frequency difference of the two signal will transmitted to the frequency counter from the output of the mixer. Thus, the frequency output pressure transducer with a frequency counter is a portable device which is able to measure the pressure without oscilloscope or computer.
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Laurenti, Rafael. "The Karma of Products : Exploring the Causality of Environmental Pressure with Causal Loop Diagram and Environmental Footprint." Doctoral thesis, KTH, Industriell ekologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-184223.
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Environmental pressures from consumer products and mechanisms of predetermination were examined in this thesis using causal loop diagram (CLD) and life cycle assessment (LCA) footprinting to respectively illustrate and provide some indicators about these mechanisms. Theoretical arguments and their practical implications were subjected to qualitative and quantitative analysis, using secondary and primary data. A study integrating theories from various research fields indicated that combining product-service system offerings and environmental policy instruments can be a salient aspect of the system change required for decoupling economic growth from consumption and environmental impacts. In a related study, modes of system behaviour identified were related to some pervasive sustainability challenges to the design of electronic products. This showed that because of consumption and investment dynamics, directing consumers to buy more expensive products in order to restrict their availability of money and avoid increased consumption will not necessarily decrease the total negative burden of consumption. In a study examining product systems, those of washing machines and passenger cars were modelled to identify variables causing environmental impacts through feedback loops, but left outside the scope of LCA studies. These variables can be considered in LCAs through scenario and sensitivity analysis. The carbon, water and energy footprint of leather processing technologies was measured in a study on 12 tanneries in seven countries, for which collection of primary data (even with narrow systems boundaries) proved to be very challenging. Moreover, there were wide variations in the primary data from different tanneries, demonstrating that secondary data should be used with caution in LCA of leather products. A study examining pre-consumer waste developed a footprint metric capable of improving knowledge and awareness among producers and consumers about the total waste generated in the course of producing products. The metric was tested on 10 generic consumer goods and showed that quantities, types and sources of waste generation can differ quite radically between product groups. This revealed a need for standardised ways to convey the environmental and scale of significance of waste types and for an international standard procedure for quantification and communication of product waste footprint. Finally, a planning framework was developed to facilitate inclusion of unintended environmental consequences when devising improvement actions. The results as a whole illustrate the quality and relevance of CLD; the problems with using secondary data in LCA studies; difficulties in acquiring primary data; a need for improved waste declaration in LCA and a standardised procedure for calculation and communication of the waste footprint of products; and systems change opportunities for product engineers, designers and policy makers.Jury committee
Henrikke Baumann, Associate Professor
Chalmers University of Technology
Department of Energy and Environment
Division of Environmental System Analysis
Joakim Krook, Associate Professor
Linköpings Universitet
Department of Management and Engineering (IEI) / Environmental Technology and Management (MILJÖ)
Karl Johan Bonnedal, Associate Professor
Umeå University
Umeå School of Business and Economics (USBE)
Sofia Ritzén, Professor
KTH Royal Institute of Technology
School of Industrial Engineering and Management
Department of Machine Design
Integrated Product Development
QC 20160405
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Foschi, Edoardo. "Design of a return circuit for an open loop wind tunnel." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21536/.
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This work is about the design of two different solutions of a return circuit for the subsonic open loop wind tunnel of the University of Bologna placed in the laboratory of aerodynamics. The possibility of realizing a return circuit was born from the idea of moving the current wind tunnel to a different place. Realizing a closed-type wind tunnel could permit a better installation with reduced costs since the starting point of the project is an existing tunnel. Two different design solutions are shown in order to satisfy different conditions of allocation: one model has vertical development, the other has horizontal development. The conceptual phase is followed by a study of the pressure losses in order to evaluate which design solution could be the best.
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Sutherland, Erika Susanne. "Analysis of the performance and stability of a passive recirculation loop for hydrogen delivery to a PEM fuel cell system." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/443.
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Proton Exchange Membrane (PEM) fuel cells are becoming an increasingly important alternative to combustion engines as the fossil fuel reserves are depleted. Several papers have presented steady state analyses of the system, but few are known to present dynamic analysis of the flow and control of the hydrogen delivery process. This thesis presents the dynamic analysis of hydrogen delivery to a PEM fuel cell system. The hydrogen is delivered to the anode with use of an ejector for passive recirculation. The system to be studied consists of the manifolds, ejector, and pressure control valve. Models describing the elements of the anode delivery systems are formulated. The governing nonlinear equations are solved analytically and numerically, and the regimes of stable hydrogen delivery process are established. The linearized models are used for performance analysis and optimization of the hydrogen delivery process. The nonlinear model is used to improve the simulation of the dynamics of the PEM fuel cell system and validate the parameters at optimal linearized stability. Experiments are conducted to find the parameters used in the model, as well as validate the results. Both the linear and nonlinear models are implemented in Simulink and tested against the laboratory data from the PEM fuel cell system. The analysis showed that the models have the same time constant and dynamic behavior as the PEM system. The optimal parameters for stability and a faster response with no oscillations in the output are obtained. The redesigned valve and resulting dynamics of the PEM fuel cell system provides improved system performance.
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Peterson, Zachary W. "Closed-Loop Thrust and Pressure Profile Throttling of a Nitrous Oxide/Hydroxyl-Terminated Polybutadiene Hybrid Rocket Motor." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1400.
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Hybrid motors that employ non-toxic, non-explosive components with a liquid oxidizer and a solid hydrocarbon fuel grain have inherently safe operating characteristics. The inherent safety of hybrid rocket motors offers the potential to greatly reduce overall operating costs. Another key advantage of hybrid rocket motors is the potential for in-flight shutdown, restart, and throttle by controlling the pressure drop between the oxidizer tank and the injector. This research designed, developed, and ground tested a closed-loop throttle controller for a hybrid rocket motor using nitrous oxide and hydroxyl-terminated polybutadiene as propellants. The research simultaneously developed closed-loop throttle algorithms and lab scale motor hardware to evaluate the fidelity of the throttle simulations and algorithms. Initial open-loop motor tests were performed to better classify system parameters and to validate motor performance values. Deep-throttle open-loop tests evaluated limits of stable thrust that can be achieved on the test hardware. Open-loop tests demonstrated the ability to throttle the motor to less than 10% of maximum thrust with little reduction in effective specific impulse and acoustical stability. Following the open-loop development, closed-loop, hardware-in-the-loop tests were performed. The closed-loop controller successfully tracked prescribed step and ramp command profiles with a high degree of fidelity. Steady-state accuracy was greatly improved over uncontrolled thrust.
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Fernandez, Alvarez Juan Jose. "Design of a high-pressure research flow loop for the experimental investigation of liquid loading in gas wells." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2358.
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ARRAGATTU, PRAVEEN KUMAR. "OPTIMAL SOLUTIONS FOR PRESSURE LOSS AND TEMPERATURE DROP THROUGH THE TOP CAP OF THE EVAPORATOR OF THE MICRO LOOP HEAT PIPE." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1152120112.
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Trivedi, Dyuti Kishorbhai. "Simulation of a Complete Cardiovascular Loop: Development of a Simulink Based Pressure-Flow Model to Obtain the Origin of the Electrical Impedance Cardiogram." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1232729044.
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Thesis (M.S.)--University of Akron, Dept. of Chemical and Biomedical Engineering, 2009."May, 2009." Title from electronic thesis title page (viewed 8/2/2009) Advisor, Bruce C. Taylor; Committee members, Daniel B. Sheffer, Dale H. Mugler; Department Chair, Daniel B. Sheffer; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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PONUGOTI, PRIYANKA. "STUDY OF TRANSIENT BEHAVIOR OF THE EVAPORATOR OF THE MICRO LOOP HEAT PIPE AND MODIFICATIONS TO THE EXISTING GLOBAL MODEL." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1152120818.
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Veydt, Aaron. "System Level Thermal Hydraulic Performance of Water-Based and PAO-Based Alumina Nanofluids." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1293473550.
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Javorčeková, Lenka. "Analýza surogát pro určení významnosti interakce mezi kardiovaskulárními signály." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400986.
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The aim of this diploma thesis was to get familiar with methods to generate surrogates and how to apply them on cardiovascular signals. The first part of this diploma thesis describes the basic theory of baroreflex function and methods to generate surrogate data. Surrogate data were generated from data, acquired from the database, by using three different methods. In the next part of this diploma thesis, coherence significance between blood pressure and heart intervals was calculated by using surrogates. In the end two hypotheses were defined and tested by which it was detected whether the orthostatic change of the measurement position has effect on the causal coherence change and baroreflex function.
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Kunz, Jan. "Převodník s HART rozhraním." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-240938.
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This diploma thesis describes design and development of creating field instrument demonstration kit. Kit is capable of measuring multiple sensors such as thermocouples, RTDs, or pressure sensors, analogue sensor simulation is also provided. Sensor’s side is isolated from output, which is composed of 4 - 20 mA current loop and HART interface. Current loop also provides power supply and kit can communicate via HART also when alarm current (3,2 mA) is set. Basic safety features like open wire detection, over and undervoltage protection are also implemented.
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Morato, José Benedito. "Comparação da eficácia dos modos de desmames de ventilação mecânica automatizados: um estudo de bancada." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/5/5150/tde-14062011-165704/.
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INTRODUÇÃO: O desmame da ventilação mecânica é um processo complexo que requer avaliação e interpretação de parâmetros clínicos objetivos e subjetivos. O atraso no processo de desmame pode expor o paciente a um desconforto desnecessário, aumentar o risco de complicações e custos. Os modos de desmame automatizados podem acelerar a extubação e diminuir a carga de trabalho da equipe da UTI. Há diversos modos automatizados de desmame disponíveis que foram avaliados, separadamente, em populações selecionadas, com resultados divergentes em relação ao desmame convencional. No entanto, os modos automáticos desmame não foram comparados entre si, nem sistematicamente avaliados, em condições específicas, mas comuns, como a ansiedade extrema ou esforços inspiratórios inefetivos. OBJETIVOS: Comparar os modos Smartcare®, ASV® e MRV® quanto a eficácia no desmame da ventilação mecânica. MÉTODOS: Estudo de bancada para avaliar os três diferentes modos de desmame automatizado: adaptive support ventilation (ASV®), mandatory rate ventilation (MRV®) and Smartcare®. Nós simulamos os pacientes usando um simulador pulmonar programável (ASL 5000 - Ingmar Medical) com o padrão respiratório, mecânica respiratória e CO2 arterial de derivados de artigos publicados em periódicos médicos para criar duas condições: 1.extubação provável: mecânica pulmonar normal, ansiedade extrema, idosos normais, padrão de respiração irregular extrema (Cheyne-Stokes), doença pulmonar restritiva; 2. extubação improvável: mecânica pulmonar alterada, com e sem esforços inspiratórios ineficazes. RESULTADOS: Os pacientes com extubação possível, ansiedade extrema, o padrão de respiração irregular moderada e extubação impossível foram diagnosticados corretamente por todos os modos. Os pacientes com Cheyne-Stokes foram diagnosticados impropiamennte por todos os modos, mas o modo Smartcare® diagnosticou corretamente quando a opção de distúrbio neurológico foi ativado. Apenas o Smartcare® diagnosticou corretamente o paciente com respiração rápida e superficial, devido à doença pulmonar restritiva. Somente o modo MRV® diagnosticou impropriamente o paciente com esforços inspiratórios ineficazes. O nível de estabilização da pressão de suporte variou para cada modo. ASV® e MRV® atingiram nível de pressão de suporte estável mais rápido do que Smartcare®. No entanto, especialmente para ASV®, não houve estabilização da pressão de suporte, mas oscilação da pressão ao longo de um grande intervalo. CONCLUSÃO: Os três modos de desmame automatizada tiveram desempenho correto na maioria dos pacientes, mesmo em condições adversas, como a ansiedade extrema. Pacientes com respiração rápida e superficial, devido à doença pulmonar restritiva, esforços inspiratórios ineficazes e Cheyne Stokes, foram impropriamente diagnosticados, dependendo do modo. ASV® e MRV® tem respostas mais rápidas, mas apresentaram grande variação do nível da pressão de suporte, especialmente de modo a ASV®INTRODUCTION: Weaning from mechanical ventilation is a complex process requiring assessment and interpretation of both objective and subjective clinical parameters. Delay in weaning process may expose the patient to unnecessary discomfort and increased risk of complications, and increasing the cost of care. Automated weaning modes could quicken the extubation and decrease the ICU team workload. Many automated weaning modes were now available. They were separately evaluated in selected populations with divergent results when compared to conventional weaning. However the automated weaning modes were not compared among them, neither systematically evaluated in challenging but common conditions, as extreme anxiety or ineffective inspiratory efforts. OBJECTIVES: Compare Smartcare®, ASV® and MRV® effectiveness in weaning of mechanical ventilation. METHODS: Bench study to evaluate three different automated weaning modes: adaptive support ventilation (ASV®), mandatory rate ventilation (MRV®) and Smartcare®. We simulated the patients using a programmable lung simulator (ASL 5000 Ingmar Medical) with the breathing pattern, respiratory mechanics and arterial CO2 derived from published medical journals articles to create two conditions: 1. Successful extubation: normal lung mechanic, extreme anxiety; old normal adult, extreme irregular breathing pattern (Cheyne-Stokes), restrictive lung disease; 2. Unsuccessful extubation: altered pulmonary mechanics with and without ineffective inspiratory efforts. RESULTS: Patients with successful extubation, extreme anxiety, moderate irregular breathing pattern and unsuccessful extubation were properly diagnosed by all modes. Patients with Cheyne-Stokes were improperly diagnosed by all modes, but the Smartcare® mode properly diagnosed when the neurologic disorder option was activated. Only Smartcare® properly diagnosed the patient with rapid shallow breathing due to restrictive lung disease. Only MRV improperly diagnosed the patient with ineffective inspiratory efforts. The pressure support level that each mode stabilized varied. ASV® and MRV® reached a stable pressure support level faster than Smartcare®. However, especially for ASV®, there was not stabilization oscillation of the pressure support level over a large range. CONCLUSIONS: The three automated weaning modes performed properly in most patients, even in challenging conditions, as extreme anxiety. Patients with rapid shallow breathing due to restrictive lung disease, ineffective inspiratory efforts and Cheyne-Stokes were improperly diagnosed depending on the mode. ASV® and MRV® have faster responses, but they presented large pressure support level variation, especially the ASV® mode
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Svedberg, Anna. "Improvement of the retention-fromation relationship using three-component retention aid systems." Doctoral thesis, KTH, Fiberteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96259.
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Libert, Nicolas. "Réanimation guidée sur la pression artérielle dans le choc hémorragique." Thesis, Sorbonne Paris Cité, 2018. https://theses.md.univ-paris-diderot.fr/Libert_Nicolas_2_complete_20180924.zip.
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Le choc hémorragique est à l’origine de 50 % des décès après un traumatisme grave. Dans ce contexte d’urgence, les objectifs hémodynamiques reposent uniquement sur le maintien d’une cible de pression artérielle basse. Les recommandations européennes sur la prise en charge des traumatisés graves hémorragiques conseillent un niveau de 80 à 90 mmHg de pression artérielle systolique jusqu’au contrôle complet du saignement et 80 mmHg de pression artérielle moyenne en cas de traumatisme crânien grave associé. Cependant, il manque actuellement des données sur la relation entre le niveau de pression artérielle, la microcirculation et l’oxygénation tissulaire. Dans un modèle d’étude de la microcirculation villositaire intestinale chez la souris, nous avons observé une relation linéaire entre la pression artérielle moyenne, la pO2 intestinale et la microcirculation intestinale. Un niveau de pression artérielle moyenne <60 mmHg était associé à une altération microcirculatoire et à la survenue d’une hypoxie intestinale. La réanimation initiale du choc hémorragique consiste prioritairement en l’administration de remplissage vasculaire. De la noradrénaline est fréquemment associée précocement de manière à limiter la dilution. Le maintien d’objectifs hémodynamiques stricts dans ce contexte d’urgence où de nombreuses tâches doivent être réalisées en même temps est complexe. L’administration de noradrénaline nécessite une certaine expertise pour cibler des objectifs de pression artérielle étroits. Dans la suite de notre travail, nous avons développé et testé un système de réanimation automatisée en boucle fermée guidée sur la pression artérielle dans des modèles de choc hémorragique. Le système de réanimation automatisée contrôlait le remplissage vasculaire ou l’association remplissage vasculaire et noradrénaline. Dans ces études, la performance de la réanimation automatisée était excellente, au minimum similaire à celle d’un médecin spécialiséHemorrhagic shock is responsible for 50 % of the deaths after severe trauma. In this emergency context, hemodynamic goals are based solely on maintaining a low blood pressure. European guidelines on the management of major bleeding after trauma recommend targeting a systolic arterial pressure goal of 80-90 mmHg while hemorrhage is not stopped yet and of 80 mmHg of mean arterial pressure in case of severe head injury. However, data on the relationship between blood pressure level, microcirculation and tissue oxygenation are currently missing. In a study model of intestinal villous microcirculation in mice, we observed a linear relationship between mean arterial pressure, intestinal pO2 and intestinal microcirculation. A mean arterial blood pressure level <60 mmHg was associated with microcirculatory impairment and to occurrence of intestinal hypoxia.Fluid guided resuscitation is the cornerstone of early hemorrhagic shock treatment. Norepinephrine is frequently associated with fluid resuscitation to limit dilution. Maintenance of strict hemodynamic objectives in such emergency context where many tasks must be performed at the same time is complex. Norepinephrine administration requires some expertise to target narrow blood pressure goals. In the rest of our work we have developed and tested a closed-loop resuscitation system guided on arterial blood pressure in hemorrhagic shock models. The closed-loop resuscitation system controlled fluid administration alone or a combination of fluid and norepinephrine. In these studies, the performance of closed-loop resuscitation was excellent, at least similar to that of a specialist physician
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Matraji, Imad. "Contribution à la commande non linéaire robuste des systèmes d'alimentation en air des piles à combustible de type PEM." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2013. http://tel.archives-ouvertes.fr/tel-00983443.
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La pile à combustible (PàC) est un dispositif qui produit de l'électricité à partir d'une réaction chimique entre l'hydrogène et l'oxygène. Le système à PàC nécessite un certain nombre d'auxiliaires pour fonctionner. Pour cela, un système de commande est indispensable pour optimiser la performance de la PàC.Dans ce travail de thèse, nous nous sommes intéressés à trois types de problématiques de commande de la PàC. La première est celle de l'optimisation de la puissance délivrée par la PàC en contrôlant le rapport d'excès d'oxygène via le débit d'air du compresseur ; en prenant en compte les variations paramétriques, les incertitudes et les perturbations externes. Ce problème est résolu en utilisant la commande non-linéaire par mode glissant d'ordre 2. Deux types d'algorithme sont synthétisés, l'algorithme du mode glissant d'ordre 2 sous-optimal et l'algorithme du Super Twisting adaptatif. Les performances de ces lois de commande ont été validées grâce à un simulateur Hardware In Loop. La deuxième concerne la maximisation de la puissance nette fournie par la pile, tout en maintenant le fonctionnement du compresseur centrifuge dans sa zone nominale et tout en évitant le manque d'oxygène à la cathode, lors des variations rapides de charge. La solution proposée pour résoudre ce problème est un gestionnaire de charge qui consiste en un filtre à coefficient de filtrage ajustable. Deux approches d'ajustement de ce coefficient basées sur la technique de l'Extremum Seeking sont appliquées, comparées et validées expérimentalement. La troisième problématique abordée dans cette thèse est celle de la régulation de la différence de pression entre l'anode et la cathode, lors de variations de charge en présence de variations paramétriques et d'incertitudes. Une solution basée sur un contrôleur multi-variable par mode glissant d'ordre 2 associé à une étude de robustesse est proposée.
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Olsen, Peter A. "Shear Modulus Degradation of Liquefying Sand: Quantification and Modeling." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1214.
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A major concern for geotechnical engineers is the ability to predict how a soil will react to large ground motions produced by earthquakes. Of all the different types of soil, liquefiable soils present some of the greatest challenges. The ability to quantify the degradation of a soil's shear modulus as it undergoes liquefaction would help engineers design more reliably and economically. This thesis uses ground motions recorded by an array of downhole accelerometers on Port Island, Japan, during the 1995 Kobe Earthquake, to quantify the shear modulus of sand as it liquefies. It has been shown that the shear modulus of sand decreases significantly as it liquefies, apparently decreasing in proportion to the increasing excess pore water pressure ratio (Ru). When completely liquefied, the shear modulus of sand (Ru = 1.0) for a relative density of 40 to 50% is approximately 15% of the high-strain modulus of the sand in its non-liquefied state, or 1% of its initial low-strain value. Presented in this thesis is an approach to modeling the shear modulus degradation of sand as it liquefies. This approach, called the "degrading shear modulus backbone curve method" reasonably predicts the hysteretic shear stress behavior of the liquefied sand. The shear stresses and ground accelerations computed using this method reasonably matches those recorded at the Port Island Downhole Array (PIDA) site. The degrading shear modulus backbone method is recommended as a possible method for conducting ground response analyses at sites with potentially liquefiable soils.
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Pešl, Jiří. "Implementace rozhraní IO-Link do snímačů tlaku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-220337.
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This thesis is concerned with the measurement of physical quantities. Thesis describes sensors in general terms and requirements, which delivers latest trends in the field of automation. The main theme of this thesis is sensors for meassuring pressure, and their connection to the automation chain. In the next part thesis describes the design of the converter for connecting SMART sensors for pressure measuring, that use HART communication protocol, to the automation systems managed by a communication protocol IO-link. First will be described in detail various communication standards by their ISO OSI model, and on this theoretical basis will be based design of converter between communication protocol HART and communication protocol IO-Link. The last part will be Designed software for this converter.
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Mariette, Kevin. "Contrôle en boucle fermée pour la réduction active de traînée aérodynamique des véhicules." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI088.
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Le contrôle actif de l’écoulement à l’arrière des véhicules se déplaçant à grande vitesse est un moyen de diminuer efficacement la consommation énergétique des véhicules par la réduction de la traînée aérodynamique. L’intérêt des méthodes actives est leur possible adéquation avec des conditions environnementales variables pour une modification minimale de la forme des véhicules, contrairement aux systèmes exclusivement passifs (profilage, ailerons aérodynamiques …). Toutefois, le contrôle actif nécessite un apport d’énergie qui réduit sa rentabilité énergétique finale. À l’aide d’essais expérimentaux sur une maquette de véhicule simplifié, cette thèse recherche comment employer un contrôle actif à base de jets pulsés à haute fréquence pour assurer une réduction de traînée de véhicule performante, robuste et énergétiquement rentable. Ces recherches sont axées sur : (i) la compréhension des phénomènes à l’origine de la traînée de pression, (ii) la définition d’un modèle de l’écoulement pour le contrôle, et (iii) l’implémentation expérimentale de méthodes de contrôle de traînée efficaces, robustes et à moindre coût énergétique. Les tests en soufflerie réalisés au cours de cette thèse se basent sur les stratégies de contrôle par mode glissant et de commande par extremum seeking qui permettent de concevoir de nouvelles solutions de réduction de la traînée visant à l’amélioration de la robustesse et de la rentabilité du contrôle par jets pulsés. Cette thèse s’inscrit dans le projet ANR ActivRoad issu de la collaboration de trois laboratoires de recherche : le Laboratoire Ampère (INSA, Lyon), l’Institut Pprime (ENSMA, Poitiers) et le LMFA (Centrale, Lyon) ; et le soutien de deux acteurs industriels : le groupe PSA et Volvo TrucksActive flow control techniques can decrease the aerodynamic drag acting on a vehicle moving at high velocity. Instead of exclusively passive techniques, active control can reduce the pressure drag on a vehicle under a wider range of operating conditions without requiring large modifications of the functional shape of the vehicles. However, active control devices require an additional source of energy, which may decrease the global efficiency of the control. Our work aims to reduce significantly the drag of ground vehicles with efficiency and robustness thanks to high frequency pulsed jet control. We present experimental studies on a simplified bluff body mock-up of a ground vehicle and we seek to understand the phenomena linked to the pressure drag on a vehicle. In this thesis, we propose a modelling methodology of the vehicle’s turbulent wake adapted for control purposes. Finally, we design and test experimentally different closed-loop control methods of the wake with high frequency pulsed air jets. The experimental studies performed in a wind tunnel show the efficient application of sliding mode control and extremum seeking techniques for a robust drag control with energy cost considerations. This thesis was financed by the French National Research Agency (ANR) and contributes to the project ActivRoad involving three French laboratories: Ampère (INSA, Lyon), Pprime Institute (ENSMA, Poitiers), and the LMFA (Centrale, Lyon); and two automotive companies: PSA group and Volvo Trucks
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Fasoldt, Ruth. "My little housewife : a look at the social pressures on college educated women in the 1950s /." Access resource online, 2009. http://scholar.simmons.edu/handle/10090/12572.
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Chandelier, Marie. "Le loup dans la presse française contemporaine : analyse des fonctionnements argumentatifs médiatiques." Thesis, Montpellier 3, 2018. http://www.theses.fr/2018MON30086.
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L’augmentation des populations de loups provoque des conflits dus aux interactions de l'espèce avec les activités économiques rurales (pastoralisme et agriculture). Ces conflits impliquent des acteurs issus de l’économie rurale, de la chasse, de l’écologie ou encore de la politique. Le loup a un statut législatif différent qui induit une protection stricte, mais sa gestion fait l'objet de dérogation conduisant à la mise en place de tirs ponctuels sur des animaux. L'espère tend, dans les débats à être considérés comme nuisibles. L’objectif de la thèse est d’identifier l’influence que peut avoir le statut législatif de l’espèce sur les procédés argumentatif utilisés dans les débats, et sur les discours médiatiques consacrés à ces débatsThe thesis focuses on the representation of controversies involving wolves in the french media, at a national and regional level
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Schoemacker, Florian, Felix Fischer, and Katharina Schmitz. "Damping strategies for energy efficient pressure controllers of variable displacement pumps." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71108.
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In hydraulic-mechanically controlled variable displacement pumps, the actual pump controller produces additional power losses. Due to the low damping coefficients of all pump controller’s components, hydraulic-mechanically pressure controlled pumps use to oscillate while adjusting the pressure level in the hydraulic system. In several state-of-the-art variable pump controllers, a damping orifice connects the control actuator’s displacement chamber with the reservoir. This bypass dampens the movement of the control actuator but also leads to bypass losses during steady-state operation of the pump. A new concept for damping via feedback loops avoiding bypass losses is presented in t his paper.
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Zahlan, Hussam Ali Mustafa. "Derivation of a Look-Up Table for Trans-Critical Heat Transfer in Water-Cooled Tubes." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32433.
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This thesis describes the development and validation of a look-up table capable of predicting heat transfer to water flowing vertically upward in a circular tube in the trans-critical pressure range from 19 to 30 MPa. The table was based on an extensive and screened experimental database and its trends were smoothened to remove unrealistic scatter and physically implausible discontinuities. When compared to other prediction methods, the present look-up table approximated the experimental data closer in values and trends. Moreover, unlike existing prediction methods, the table applies not only to normal heat transfer conditions but also to conditions with heat transfer deterioration and enhancement. A separate multi-fluid look-up table for trans-critical heat transfer was also developed, which besides the existing water database incorporated new measurements in carbon dioxide; the latter were collected at the University of Ottawa supercritical flow loop under conditions of interest for the current Super-Critical Water-Cooled Reactor designs, for which few water data were available in the literature. Existing fluid-to-fluid scaling laws were tested and two additional sets of scaling laws were proposed, which are applicable not only to the supercritical pressure region, but also to the high pressure subcritical region. The multi-fluid table is applicable to water at conditions of normal and abnormal heat transfer, but its applicability to model fluids is restricted to the normal heat transfer mode.
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Montagnac, Gilles. "Spectroscopie Raman résonnante UV in situ à haute température ou à haute pression." Thesis, Lyon, École normale supérieure, 2012. http://www.theses.fr/2012ENSL0784/document.
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Dans cette thèse, la spectroscopie Raman résonante UV (SRRUV) est appliquée pour la première fois à l'étude ‘in situ’ de matériaux carbonés à très haute température (> 2000 K) ou à haute pression (< 1 GPa).La thèse est constituée de trois parties. La première aborde notre travail de caractérisation en SRRUV (1) de films semi conducteurs de diamants ultra-nano-cristalins, (2) des kérogènes issues de météorites chondritiques et de charbons, et (3) des tholins, échantillons de carbone-hydrogène-azote, synthétisés comme analogues de l'atmosphère de Titan.L’intérêt pour ces phases du carbone en planétologie et en science des matériaux nous a poussé à mettre en œuvre leur étude ‘in situ’ en SRRUV. La seconde partie de la thèse est consacrée au développement d'une platine chauffante, grâce à laquelle les spectres Raman du graphite sous sa forme pyrolitique et HOPG ont été mesurés jusqu'à 2700 K. Ces données valident les modèles anharmoniques théoriques d’interaction électron-phonon et phonon-phonon. Le spectre Raman du graphite a été étalonné en fonction de la température et devient un « thermomètre » à très haute température.Dans la troisième partie de cette thèse, une presse à enclumes opposées a été modifiée pour suivre en SRRUV les changements structuraux de cristaux moléculaires très luminescents. Les vibrations intramoléculaires du cristal de pérylène sont étudiées sous pression par SRRUV. Ce composé est un cristal formé de molécules organiques polyaromatiques, avec des propriétés de semi-conducteur. Les effets de la pression sur certains modes de vibrations sont non linéaires et mettent en évidence des changement structuraux et de planéité de la moléculeI applied UV resonant Raman spectroscopy (UVRRS) to an ‘in situ’ study of carbon materials at very hight temperature (> 2000 K) or at high pressure (< 1 GPa).The advantages of UVRRS are presented in the first part of this PHD thesis, and used to investigate details of the composition and structure of disordered carbon materials such as: (1) n-type nanocrystalline films, (2) carbonaceous matter in chondrites and (3) tholins, HCN synthetic samples of Titan 's atmosphere.‘In situ’ Raman studies are limited to 2000 K by the visible black-body emission. I designed a high temperature cell to perform UVRRS above this limit. The second part of the manuscript presents Raman spectra of pyrolitic graphite and HOPG up to 2700 K. This data are consistent with anharmonic models up to 900 K, and show the coupling effects of electron-phonon and phonon-phonon. The last one dominates the anharmonicity above 1000 K. The Raman spectra was calibrated as a function of temperature and became a “thermometer” up to 2700 K.For high pressure measurements in the third part, I modified an anvil cell to study by UVRRS, the vibrational changes induced by pressure on very luminescent molecular organic crystals. I present an analysis at 244 nm of resonant Raman modes of perylene crystal under hydrostatic pressure up to 0.8 GPa. Some of them have a non linear feature under pressure, revealing structural and planar modifications of the molecules
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Vallée, Fabrice. "Concept des boucles vélocité-pression aortiques comme monitorage de la post-charge ventriculaire gauche." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCC112.
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La post-charge ventriculaire est un phénomène complexe impliquant simultanément des phénomènes de résistances vasculaires, de compliance artérielle et de réexions des ondes pulsatiles. Ces phénomènes physiologiques ne peuvent être évalués par une analyse classique avec l'étude indépendante des valeurs de la pression artérielle ou du débit cardiaque. Cependant, une analyse couplée des vélocités Doppler aortiques et de la pression artérielle avec la réalisation des boucles vélocités pression (VP Loops) peuvent nous apporter ces informations. En effet, les résultats de nos différents travaux de recherche retrouvent que les angles GALA et Beta, deux paramètres issus de la VP Loop : (1) reflètent la compliance artérielle et les phénomènes d'ondes de réflexion, (2) discriminent avec une forte puissance les patients porteurs de risque cardiovasculaire et (3) permettent de différencier et de titrer les différents vasoconstricteurs utilisés au bloc opératoire. Ce travail de thèse retrace les travaux ayant amené la mise au point d'un moniteur incluant le monitorage des VP Loop et comporte: (1) le "proof en concept" des VP Loop, (2) la mise au point des VP Loop avec la synchronisation des signaux de Doppler et de pression en temps réel ainsi que le développement d'une fonction de transfert pour reconstruire la courbe de pression aortique, (3) la comparaison des paramètres de la VP Loop sur l'ensemble de l'aorte thoracique et (4) une étude sur les variations de ces paramètres en fonction des thérapeutiques utilisés au bloc opératoire. Ces différents travaux ont conduits à la réalisation de 6 articles originaux publiés ou soumis, 10 abstracts dans des congrès nationaux ou internationaux, un brevet international AP-HP et une collaboration active avec la société Deltex Medical© pour la mise au point d'un moniteur incluant les VP Loop. De futurs travaux devraient s'attacher à étudier l'impact sur la morbi-mortalité d'une prise en charge au bloc opératoire guidée par le monitorage des VP Loop pour les patients à risqueVentricular afterload is a complex phenomenon involving simultaneous phenomena of vascular resistance, arterial compliance and pulsatile wave reflections. These physiological phenomena cannot be evaluated by conventional analysis with the independent study of blood pressure or cardiac output values. However, a combined analysis of aortic Doppler velocities and blood pressure with the realization of pressure velocity loops (VP Loops) can provide us with this information. Indeed, the results of our differents research find that the angles GALA and Beta, two parameters derived from the VP Loop: (1) repeat arterial compliance and reflection wave phenomena, (2) discriminate with high power against patients with cardiovascular risk and (3) allow to differenciate and titrate vasoconstrictor used in the operating room. This thesis work retraces the work that led to the development of a monitor including VP Loop monitoring and includes: (1) the "proof in concept" of VP Loop, (2) the development of VP Loop with synchronization of Doppler and pressure signals in real time as well as the development of a transfer function to reconstruct the aortic pressure curve, (3) the comparison of VP Loop parameters over the entire thoracic aorta and (4) a study on the variations of these parameters according to the therapies used in the operating theatre. These recent studies have led to the production of 6 original articles published or submitted, 10 abstracts in national or international conferences, an international patent and an active collaboration with Deltex Medical© for the development of a monitor including VP Loop. Future work should focus on studying the impact on morbidity and mortality of management in the operating room guided by VP Loop monitoring for at-risk patients
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Crosby, Jessica Renee. "Expanding the Performance Envelope of the Total Artificial Heart: Physiological Characterization, Development of a Heart Failure Model, And Evaluation Tool for Mechanical Circulatory Support Devices." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/344221.
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Heart failure (HF) affects an estimated 5.8 million Americans, accounting for near 250,000 deaths each year. With shortages in available donor hearts, mechanical circulatory support (MCS) has emerged as a life-saving treatment for advanced stage HF. With growth in MCS use, a clinical and developmental need has emerged for a standard characterization and evaluation platform that may be utilized for inter-device comparison and system training. The goal of this research was to harness SynCardia's total artificial heart (TAH) to meet this need. We first sought to characterize the TAH in modern physiological terms - i.e. hemodynamics and pressure-volume loops. We then developed a model of HF using the TAH and mock circulatory system operating in a reduced output mode. We demonstrated that MCS devices could be incorporated and evaluated within the HF model. Finally, we characterized the operational envelope of SynCardia's Freedom (portable), Driver operating against varying loading conditions. Our results describe the hemodynamic envelope of the TAH. Uniquely, the TAH was found not to operate with time-varying elastance, to be insensitive to variations in afterload up to at least 135 mmHg mean aortic pressure, and exhibit Starling-like behavior. After transitioning the setup to mimic heart failure conditions, left atrial pressure and left ventricular pressure were noted to be elevated, aortic flow was reduced, sensitivity to afterload was increased, and Starling-like behavior was blunted, consistent with human heart failure. The system was then configured to allow ready addition of ventricular assist devices, which upon placement in the flow circuit resulted in restoration of hemodynamics to normal. Lastly, we demonstrated that the Freedom Driver is capable of overcoming systolic pressures of 200 mmHg as an upper driving limit. Understanding the physiology and hemodynamics of MCS devices is vital for proper use, future device development, and operator training. Characterization of the TAH affords insight into the functional parameters that govern artificial heart behavior providing perspective on differences compared to the human heart. The use of the system as a heart failure model has the potential to serve as a valuable research and teaching tool to foster safe MCS device use.
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Childers, Rachel Caitlin. "The Role of Tissue Modulus and Cardiac Fibroblast Phenotype in Volume Overload Induced Heart Failure." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480335744116284.
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Berthomier, Maud. "De la musique et des mots. La critique rock à l’aune de la littérature (1966-1975)." Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT5010.
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Dans la seconde moitié des années soixante naissent aux États-Unis le rock et la critique rock.Les participants de ces deux sphères s'unissent jusqu'à former une camaraderie, mais de cette rencontre surgit aussi un troisième champ. Ni vraiment musical, ni totalement critique, celui-ci est avant tout « littéraire ». Il nous met au défi de parler de critique rock pour mieux discuter de littérature et non de musique. C'est dans ce paradoxe apparent que Lester Bangs évolue par exemple. Génie tutélaire de ce petit groupe d'auteurs formés au sein des premiers fanzines et magazines rock, il ne décrit pas seulement les mythes rock ; il interroge aussi leur écriture. Plus avant, ce qui se dessine dans ses textes est le portrait du jeune écrivain « débutant » issu de la grande tradition du « journalisme littéraire ». Cela crée des liens entre les conditions d'accès à l'écriture dans la presse et le devenir « écrivain » en littérature. De même, trouve-t-on des annonces et des échos de ces discours dans le « cinéma direct » américain de l'époque, ainsi que dans la critique rock française. Le film Dont Look Back de Donn Alan Pennebaker par exemple montre déjà dès 1965 la nécessité de la création d'une critique non-journalistique sur le rock. Puis, Yves Adrien s'inspire de l'œuvre de Lester Bangs. Et enfin aujourd'hui à plus de quarante ans de distance, toujours Nick Tosches, Peter Guralnick, Greil Marcus et Lenny Kaye reconstruisent en paroles cette première expérience d'écriture et de publication. Aussi, cette thèse étudiera la création inattendue d'un champ littéraire au sein de la critique rock sur un plan mythographique : bien qu'éphémère, celui-ci s'avèrera fécondIn the second half of the sixties, rock music and rock criticism emerge in the United States. The protagonists of the two spheres gather to create a sense of camaraderie, but a third field also arises from that encounter. It is first and foremost a literary one, neither really musical, nor completely criticism-oriented. As a result, it challenges us to discuss rock criticism in order to better understand literature rather than music. Lester Bangs in particular dwells within that apparent paradox. As the figurehead of this little group of authors formed in early rock fanzines and magazines, he not only describes the rock myths but also discusses the way they are written. The portrait of the “aspiring writer” originating from the tradition of “literary journalism” also appears in his texts. This links the conditions of writing in the press to the situation of the fresh writer-to-be in literature. Similarly, auguries and echoes of such discourses can be found during the same period in American “direct cinema” and French rock criticism. For instance Donn Alan Pennebaker already underlines in 1965 the need for a non-journalistic criticism on rock in his documentary Dont Look Back. Later, Yves Adrien follows Lester Bangs works. Finally, forty years on, Nick Tosches, Peter Guralnick, Greil Marcus and Lenny Kaye continue today to reshape verbally this initial experience of writing and publishing. This thesis studies the unexpected birth of a new literary field through mythography. Though short-lived, it was nonetheless fecund
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Lin, Yet-Zen, and 林逸人. "LOOP ANTENNA FOR TIRE-PRESSURE DETECTION." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/15636792111324573026.
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碩士大同大學
電機工程學系(所)
100
A printed loop antenna driven by a low voltage IC-chip is mounted on a test unit to detect the tire pressure of an automobile car. Aside from the antenna, the unit contains a battery, a pressure sensor, and the transmitting circuits. The antenna input impedance is matched to the chip’s output impedance of 7.9 - j159.6 ohm at 434 MHz. To achieve this goal, the antenna contains two printed split rings spacing at a distance of 4 mm. The two rings are analyzed as a transformer in which the smaller ring is the primary coil and the larger one is the second coil. When the antenna is used as a transmitter, the linking loss is -49dBm at the receiving end which is 3m away from the antenna. Compared with the theoretical value of the linking loss, the difference is 3.3dB.
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Park, Jae-Sung. "Open loop and servo-controlled micromachined capacitive pressure sensors." 2002. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Lin, Shuo-Yen, and 林碩彥. "Heat transfer and Pressure drop in a Reverse Thermosyphon Loop." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88232721517938882491.
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碩士淡江大學
機械與機電工程學系碩士班
103
The conventional thermosyphon in a closed system, also referred as a “bottom-heat-type” thermosyphon, depends on the natural upward movement of vapor steam, hot fluid and the downward movement of cold liquids. Nevertheless, the reverse thermosyphon loop (RTL) could not only transfer heat from a heat source near the top to a heat sink at the bottom but also transfer heat from bottom to top as a conventional thermosyphon. The self-acting downward heat transfer devices are very useful for solar heating system, ground source heat pump (GSHP), and waste heat recovery. The experiment is expected to explore the issue of different input power, tilt angle and change the downward heat transfer pipe diameters. Discussion the heat transfer and pressure drop of the reverse thermosyphon loop.
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Ritchie, John Andrew. "PRESSURE MEASUREMENT INSTRUMENTATION IN A HIGH TEMPERATURE MOLTEN SALT TEST LOOP." 2010. http://trace.tennessee.edu/utk_gradthes/829.
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A high temperature molten salt test loop that utilizes FLiNaK (LiF-NaF-KF) at 700ºC has been proposed by Oak Ridge National Laboratory (ORNL) to study molten salt flow characteristics through a pebble bed for applications in high temperature thermal systems, in particular the Pebble Bed – Advanced High Temperature Reactor (PB-AHTR). The University of Tennessee Nuclear Engineering Department has been tasked with developing and testing pressure instrumentation for direct measurements inside the high temperature environment. A nickel diaphragm based direct contact pressure sensor is developed for use in the salt. Capacitive and interferometric methods are used to infer the displacement of the diaphragm. Two sets of performance data were collected at high temperatures. The fiber optic, Fabry-Perot interferometric sensor was tested in a molten salt bath. The capacitive pressure sensor was tested at high temperatures in a furnace under argon cover gas.
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Tsai, Meng-Chieh, and 蔡孟捷. "Development of a peripheral blood vessel pressure-volume loop measurement system." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/97697454106821931928.
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碩士中原大學
生物醫學工程研究所
98
This study proposes to construct a system to obtain blood pressure and impedance signal using non-invasive impedance device and continuous blood pressure measurement device. We acquire impedance signal using ring electrode system to feed high-frequency, low- intensity constant current source into subject’s forearm. It measures beat-to-beat impedance signal originated from the blood flow though the peripheral vessel. We then used the positive relationship between the impedance change and the volume to obtain the vessel volume change. Equipped with information of pressure and volume, we could plot the pressure-volume loop. It is known that the left ventricular pressure-volume loop contains a number of feature points indicating the performance of cardiac function. Therefore, in this study, the same principle is used to discuss the peripheral vessel pressure-volume loop. In this study, impedance signal of the peripheral blood vessel and blood pressure waveform were obtained from twelve young volunteers, using the custom-made system. The subjects went through the cold pressor test by immerging the subject’s left leg in the ice water. The blood pressure and impedance changed were recorded. The results illustrated that the pressure-volume loop, as it was expected, demonstrated the contraction phenomenon after stimulation. Additionally, it is a easy measurement that can be used to investigate the compliance and characteristic of peripheral blood vessel.
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Yuang, Li Chung, and 李春源. "A Windows Based Pressure Volume Loop Analysis System for Clinical Research." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/87255961470073751117.
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碩士中原大學
醫學工程學系
88
The real-time pressure and volume information from left ventricle representing the condition of the heart. The real-time pressure and volume can be graphed in two dimensional space using volume as X-axis and pressure as Y-axis that is to construct the pressure and volume relationship into a loop, called PV-loop. Many parameters can be calculated and extracted from this relationship. These parameters are the indexes that are using in evaluating the performance of the left ventricle. However, the procedure of extracting these parameters was very awkward and inconvenience. A turnkey type of data extraction is needed. Therefore, this thesis responds to such demands and is reporting a windows-base program that can be used to extract the data clinically. The data extracting procedure is compatible to published data. The extracted and calculated parameters have been compare to common accepted system using Student T-test and correlation. The accuracy of the parameters compared is in acceptable range, within 95%.
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Chen, Chieh-En, and 陳傑恩. "A Real-time Ventricular Pressure-Volume Loop Measurement System with the Conductance Catheter." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/04084867098924944471.
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碩士國立成功大學
電機工程學系碩博士班
96
Electrical impedance measurement technique is widely used in biomedical researchers and applications, such as a conductance catheter. The conductance catheter is used to measure real-time ventricular impedance, and then the measured impedance is converted to ventricular volume. While incorporating with pressure signals, a real-time ventricular pressure-volume loop plot can be obtained, which is a standard tool for researchers and doctors to evaluate the cardiac functions. The main purpose of my research is to develop a real-time measurement system for the conductance catheter. Instead of traditional instrument designed with analog elements for processing, a high speed DSP chip, TMS320F2812 made by Texas Instrument, is used to be the core for digital signal processing. Besides, peripheral analog circuits are needed for signal sensing. Moreover, a graphic user interface, implemented by LabView and a data acquisition card, is designed to illustrate the measurement result immediately. Next, some other equipments are designed to verify the system and finally the in-vivo experiment is performed. (1) An emulator that can mimic the special measured voltage signals is constructed. During the system development stage, the emulator is served as a benchmark to test the functionality and bandwidth of the system. (2) A ventricle-imitated environment is constructed that can test if the system can work for real situation. (3) In vivo Rat experiment that can test the system whether it can work for in-vivo measurement. According to the measurement results, the designed system does work well.
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Wu, Chi Yeong, and 吳志勇. "Thermal-Hydraulic Oscillations in a Low Pressure Two-Phase Natur -al Circulation Loop at Low Powers." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/49832354865588031557.
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Wu, Zhi-Yong, and 吳志勇. "Thermal-Hydraulic Oscillations in a Low Pressure Two-Phase Natur -al Circulation Loop at Low Powers." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/29197368276536205825.
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Loeffler, Kathryn Rose. "Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts." 2012. http://hdl.handle.net/2152/20018.
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The design, fabrication, and in-vivo testing of an implantable device to measure the pressure-volume (PV) relationship in the hearts of conscious, untethered rats is presented. Volume is measured using a tetrapolar catheter positioned in the left-ventricle which emits a 20kHz current field across the LV blood pool and parallel heart tissue and measures the resulting voltage. The admittance method is used to instantaneously remove the contribution of the parallel heart muscle and Wei’s non-linear blood conductance-to-volume equation is used to calculate volume. Pressure is measured with a strain gauge sensor at the tip of the catheter. The implant was designed to be small, light, and low-power. An average implant occupies 5 cm3, weighs 8g, and on a single charge collects data for 2 months taking 43 samples per day. Collected data is transmitted wirelessly via RF to a base station where it is recorded. The functionality of the implant and measurement system was verified in six rat experiments. In all experiments, ambulatory PV loops were measured on implantation day. Viable pressure data was recorded for 11 days in one rat; in another rat viable admittance data was collected for 10 days. Changing catheter position and non-constant blood resistivity are considered as sources of error in the volume measurement. Pressure drift due to changing atmospheric pressure is considered as a source of error in the pressure measurement. Lastly, alternative uses for the implant and directions for future improvement are considered.text
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(11197311), Jay V. Shah. "Development of a Closed-Loop, Implantable Electroceutical Device for Glaucoma." Thesis, 2021.
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Glaucoma is the leading cause of irreversible blindness worldwide. While current therapies aim to lower elevated intraocular pressure (IOP) to prevent blindness, they often do not provide the desired long-term efficacy, can fail over time, and have systemic side effects. Electroceutical stimulation can be a solution to many of these current issues with glaucoma treatment, as it is believed to have fewer systemic side effects and quicker response times. The goal of this work is to develop and demonstrate a novel system using electrical stimulation to lower intraocular pressure. I present data from a human clinical study and an ongoing clinical trial of the IOPTx™ system, a wearable electroceutical for treating glaucoma, that provides preliminary evidence of efficacy and safety. Furthermore, no current glaucoma treatments allow for closed-loop, continuous monitoring of IOP, requiring more frequent doctor visits or forcing patients and clinicians to operate in the dark. Using an electroceutical therapeutic device with closed-loop feedback and continuous IOP recording can improve glaucoma management. I combined a pressure sensor with this electroceutical therapy, implanted the sensor and stimulation coils in rabbits, and stimulated the eyes. However, to better understand the optimal stimulation parameters, long-term effects, and mechanisms of action, an integrated circuit is designed as part of a fully implantable, closed-loop device. The chip was fabricated in 0.18 µm CMOS process and validated on the benchtop and in vivo. In the future, this electroceutical device has the potential to be a novel treatment for patients suffering from glaucoma.
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(6615704), Rachael Swenson. "Design of a Closed Loop System for Glaucoma Treatment including Measurement of Intraocular Pressure and Therapeutic Stimulation of the Eye." Thesis, 2019.
Find full textAbstract:
Glaucoma is the leading cause of irreversible blindness worldwide effecting more than 2.7 million people in the U.S alone. Treatments exist in the form of both pharmaceutical and surgical options, but often do not provide the desired efficacy. For example, the failure rate of a trabeculectomy procedure is 39% within 5 years. Additionally, none of the current glaucoma treatments allow for closed loop monitoring of pressure, therefore requiring more frequent doctor visits. Glaucoma management can be improved through the use of a closed loop application of electroceutical treatment. The goal is to develop an implantable device that will be inserted into the eye to monitor intraocular pressure (IOP) and provide responsive therapeutic stimulation to the eye. I designed a discrete pressure monitoring system that interacts with a bare die piezoresistive pressure sensor. The system is based on a Wheatstone bridge design which translates the input resistances of the pressure sensor into a voltage output. This system has an average accuracy of 0.53 mmHg and draws 295 µW of power. I then combined this pressure system with data processing code and Howland current pump stimulation circuitry. This simulation system can output up to 1.05 mA of current for electroceutical intraocular stimulation to lower IOP. Future work will involve miniaturizing the circuitries in the form of an ASIC and packaging the entire system into an ocular implant. This implant can wirelessly monitor IOP and provide therapeutic stimulation to lower IOP. A reliable, closed loop method of lowering IOP would greatly benefit the ever-growing population affected by glaucoma.
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Musini, Vijaya Manavendra. "A systematic review of the blood pressure lowering efficacy of thiazide and loop diuretics in the treatment of primary hypertension." Thesis, 2000. http://hdl.handle.net/2429/10427.
Full textAbstract:
Context- First-line treatment of hypertension with low- or high-dose thiazide
therapy compared to placebo or untreated control group reduced blood pressure
to a similar extent but their effect on mortality or coronary events appeared to be
different.
Objectives.- To determine the dose-related decrease in systolic and diastolic
blood pressure, withdrawal due to adverse drug effects and metabolic adverse
effects of thiazide and loop diuretic monotherapy compared to a placebo control,
for a duration of 3-12 weeks, in patients with primary hypertension (SBP > 160
and/or DBP > 90 mmHg).
Design.- A systematic review of all randomised placebo controlled trials.
Setting.- Electronic databases were searched using the standard search
strategy of the Cochrane Hypertension Review group. Data were analysed using
Review Manager 4.0.
Participants.- 33 trials, involving 4,811 patients reported data on thiazides and
only 3 trials involving 150 patients reported data on loop diuretics.
Results.- BP lowering efficacy: The dose of thiazide approaching near
maximal systolic and diastolic blood pressure lowering efficacy with the best
overall estimate in mm Hg identified was: hydrochlorothiazide 25 mg/day (9/5);
chlorthalidone 12.5 mg/day (10/3) and indapamide 1.0 mg/day (7/4). The overall
best estimate for combined doses of all thiazide drugs was 10/4 mm Hg. Lowand
high-dose thiazides lowered blood pressure to a similar extent.
Evidence relating to loop diuretics is insufficient to determine a dose-related
effect on any of the outcome measures.
Withdrawal due to adverse drug effects were similar to the placebo group in
low and high-dose thiazide trials. The overall relative risk of withdrawal due to
adverse events for thiazides was 1.2(0.8, 1.2).
Metabolic adverse effects: Combined high doses of all thiazide drugs showed a
significant decrease in serum potassium levels as compared to combined lowdoses.
A significant decrease in serum potassium and a significant increase in
serum uric acid, creatinine, triglyceride and total cholesterol were observed
compared to the placebo control group.
Conclusion.- The lowest range of clinically used doses of thiazide diuretic
showed near maximal blood pressure lowering efficacy and a lower incidence of
adverse metabolic effects. It is recommended that there is no advantage to
using doses higher than those defined as low dose.
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LIN, CHING-YUAN, and 林敬原. "An experimental study of thermal performance for a two phase loop thermosyphon with scale-roughened boiling surface at vacuum pressure." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/87333961989154696704.
Full textAbstract:
碩士國立高雄海洋科技大學
輪機工程研究所
102
As an attempt to reduce the degradation of the thermal performance for a Two Phase Loop Thermosyphon (TPLT) operated at vacuum pressures due to the effects of boiling instabilities, this experimental study proposed the scale-roughened evaporator to increase nucleate sites, reduce bubble waiting time and moderate the pressure waves transmitted from bubble eruptions for reducing the interface oscillations so that the overall thermal performances of the TPLT can be improved. With the heater power of evaporator (Q) and the condenser thermal resistance (Rth,con) as the controlling parameters, the thermodynamic cycles, thermal networks, boiling instabilities for two TPLTs with smooth and scale-roughened evaporators are comparatively analyzed. The variations of the saturated pressures against boiling number (Bo) and Rth,con in each evaporator of the two TPLTs are also examined. The tested Q and Rth,con are in the respective ranges of 90-210W and 0.25-0.45 KW-1. With the scale-roughened evaporator, the thermal resistances caused by the pre-heating effects as a result of the boiling instabilities are considerably reduce due to the weakened pressure wave oscillations, the reduced bubble waiting time and the extension of nucleate boiling regime. With the reduced boiling instabilities, the cooling power consumptions over the condenser for the scale-roughened TPLT are considerably reduced to 1/1.5~1/2.5 times of those required for the smooth-walled TPLT. The empirical correlations for evaluating the boiling heat transfer rates, saturated pressures of evaporator and the total thermal resistance of present scale-roughened TPLT are generated as the design references for the relevant industries. Keywords: Two Phase Loop Thermosyphon, Scale-roughened Evaporator, Boiling instabilitiy.
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Amiri, Amir Reza. "Pressure Dependence and Volumetric Properties of Short DNA Hairpins." 2010. http://hdl.handle.net/1807/25408.
Full textAbstract:
Previous studies of short DNA hairpins have revealed that loop and stem sequences can significantly affect the thermodynamic stability of short DNA hairpins. Nevertheless, there has not been sufficient investigation into the pressure-temperature stability of DNA hairpins, and the current thermodynamic knowledge of DNA hairpins’ stability is limited to the temperature domain. In this work, we report the effect of hydrostatic pressure on the helix-coil transition temperature (TM) for eleven short DNA hairpins at different salt concentrations by performing UV-monitored melting. The studied hairpins form by intramolecular folding of 16-base self-complementary DNA oligo¬deoxy¬ribonucleotides. Model dependent (van’t Hoff) transition parameters such as ΔHvH and transition volume (ΔV) were estimated from analysis of optical melting transitions. Experiments revealed the ΔV for denaturation of these molecules range from -2.35 to +6.74 cm3mol-1. The difference in the volume change for this transition is related to differences in the hydration of these molecules.
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"The Effect of Leading-Edge Geometry on the Induced Drag of a Finite Wing." Master's thesis, 2019. http://hdl.handle.net/2286/R.I.53549.
Full textAbstract:
abstract: This study identifies the influence that leading-edge shape has on the aerodynamic characteristics of a wing using surface far-field and near-field analysis. It examines if a wake survey is the appropriate means for measuring profile drag and induced drag. The paper unveils the differences between sharp leading-edge and blunt leading-edge wings with the tools of pressure loop, chordwise pressure distribution, span load plots and with wake integral computations. The analysis was performed using Computational Fluid Dynamics (CFD), vortex lattice potential flow code (VORLAX), and a few wind-tunnels runs to acquire data for comparison. This study found that sharp leading-edge wings have less leading-edge suction and higher drag than blunt leading-edge wings.
The blunt leading-edge wings have less drag because the normal vector of the surface in the front section of the airfoil develops forces at opposed skin friction. The shape of the leading edge, in conjunction with the effect of viscosity, slightly alter the span load; both the magnitude of the lift and the transverse distribution. Another goal in this study is to verify the veracity of wake survey theory; the two different leading-edge shapes reveals the shortcoming of Mclean’s equation which is only applicable to blunt leading-edge wings.Dissertation/Thesis
Masters Thesis Aerospace Engineering 2019
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Newlove, Therese A. "Methodological and psychological predictors of the white coat effect." Thesis, 1998. http://hdl.handle.net/2429/8431.
Full textAbstract:
The purpose of the study was to examine psychological and methodological
factors which would predict the white coat effect (WCE). The WCE is defined as the
difference (mm Hg) between ambulatory and office measured blood pressure (BP). Sixty
three community volunteers participated in this study. Participants were divided into 3
Response style groups: (1) Office responders had ambulatory BP values which were
lower than office BP, (2) Non responders showed a minimal difference between office
and ambulatory BP, and (3) Home responders had significantly higher ambulatory BP
compared to office BP. Participants were asked to have a series of BP readings taken by
a physician, nurse and by themselves and participate in 24 hour ambulatory monitoring.
State and trait self-report psychological measures were completed.
Self measured BP was the most representative of ambulatory BP for the sample as
a whole, and in particular for the Home responders. State anxiety, previously dismissed
as mediating factor in the expression of the white coat effect, proved to discriminate
between the groups. Office responders had significantly higher levels of state anxiety,
directly related to BP measurements, compared to Home and Non responders.
Habituation to the experience of having BP measured by a physician, and habituation of
the anxiety prior to the BP measurement, was different among the three groups. Trait
psychological variables did not distinguish group membership. Self measured systolic
BP, state anxiety prior to self measured BP, habituation to physician measured BP and
the anxiety preceding it, were entered as predictors variables in a discriminant function
analyses. These variables were able to correctly classify group membership for 63% of
the sample.
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Raghavan, Karthik 1981. "Design of a wireless bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats." 2009. http://hdl.handle.net/2152/18383.
Full textAbstract:
Left ventricular (LV) volume analysis in small animals has proven difficult because of the small size of the hearts and the rapid heart rate. Furthermore, there is a substantial contribution to the signal from both the blood as well as the muscle. Admittance - based measurement techniques has been proven effective in eliminating the muscular component and estimating the blood component accurately. The key factor that makes this measurement effective is the fact that the measurement is made in the complex plane, which measures both the magnitude as well as the phase of the complex phasor. This dissertation presents the design of a wireless telemetric device that measures impedance magnitude and phase measurements along with pressure from conscious, ambulatory rats. Using this impedance data along with other calibration data such as blood resistivity, stroke volume etc., volume is determined.text