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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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Patel, Darshan Shyam. "A Real-Time Technique for the Correction of Invasive Blood Pressure Measurements using Counter Pressure." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1205764260.
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Guilhem, Mathieu. "Conception and optimization of a piezo-optic pressure transducer : application to high hydrostatic pressures sensing." Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/GUILHEM_Mathieu_2010.pdf.
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La mesure de pression est un domaine vieux de plusieurs siècles, dont le développement a été motivé par l’importance de ses applications technologiques. Le but de ce travail est de proposer une technique de mesure de fortes pression hydrostatiques par capteur optique à bas coût. De nombreux types de capteurs de pression ont été développés au cours du temps, et la première partie de ce document présente une vue d’ensemble du domaine. Nous nous concentrons ensuite sur les techniques optiques et présentons leurs avantages et inconvénients. Au vu de notre cahier des charges, nous choisissons de développer un capteur de pression basé sur l’effet piezo-optique, c’est à dire l’apparition d’une biréfringence dans un matériau diélectrique soumis à une force extérieure. La Partie II du mémoire présente les différents outils qui seront par la suite utilisés pour modéliser le capteur proposé : tout d’abord nous rappelons les détails de la théorie de la polarisation, son origine physique ainsi que le formalisme de Mueller-Stokes. Nous nous intéressons ensuite aux interactions entre une lumière polarisée et un milieu diélectrique, en présentant l’effet piezo-optique ainsi que les effets polarisant des réflexions à une interface. Les effets présentés sont modélisés par leur matrice de Mueller afin de simplifier l’étude à suivre. Dans la Partie III nous proposons un concept original de capteur de pression, utilisant une approche novatrice par rapport à celle usuellement mise en œuvre. Le capteur proposé est basé sur l’analyse d’une lumière dont la polarisation est modifiée par la traversée d’un milieu diélectrique rendu biréfringent par la pression à mesurer. Certains aspects du capteur sont optimisés, et ses inconvénients discutés. Cette étude aboutit à la proposition d’un capteur dans lequel les éléments polarisant discrets ont été remplacés par des réflexions successives. Ce nouveau concept est modélisé, puis nous présentons les différentes sources potentielles d’erreur de mesure et proposons des solutions pour compenser celles qui prédominent. La Partie IV présente la validation expérimentale des concepts précédents. Nous décrivons la conception, la calibration et la validation d’un polarimètre de Mueller par Transformée de Fourier, conçu dans le but d’étudier la dépendance de l’effet piezo-optique à la température. Ensuite nous présentons la réalisation d’un démonstrateur de capteur piezo-optique de pression. Les essais effectués sont en accord avec les prédictions théoriques et valident donc le principe du capteur développé au cours de ce travailThe measurement of pressure is a field that has been studied for centuries due to its important technological implications. Our goal is to propose an original method to measure high hydrostatic pressures using a low cost optical sensor. A number of pressure sensors have been developed over the years, and the first part of this work presents an overview of the main ones. We then focus on optical pressure sensors, discuss the advantages and inconveniences of each method with regards to our constraints, and decide to develop the concept of a sensor based on the piezo-optic effect, i. E. The stress-induced birefringence in a transparent dielectric subjected to a force. We presents the tools that will be used to modelize the piezo-optic pressure sensor: we first review the theory of polarization of light, from its physical origin to the Mueller-Stokes formalism; we then focus on the interaction of polarized light with matter: we discuss the theory of the piezooptic effect and the polarization effects of total and partial reflections at an interface. Both effects are modelized in terms of their Mueller matrices. We then propose an original concept for a pressure sensor, using an approach different from the one usually seen in polarimetric sensors. First the concept of a piezo-optic pressure sensor is presented where polarized light interacts with a dielectric material subjected to a pressure; the resulting state of polarization is analyzed by a second polarizer and a photodetector. Some aspects of the sensor are optimized while its shortcomings are listed. In light of this analysis we propose a revised concept to addresses these issues. The new proposal uses carefully oriented reflections to replace all polarizing elements, enabling simpler and cheaper production. We modelize this device, analyze its optical behavior, and then present the different sources of measurement error. Most of them are negligible, and we present methods to mitigate the influence of these that are not. Part IV focuses on the experimental validation of the concepts presented so far. We describe the conception, calibration and validation of a Fourier Transform Mueller polarimeter that we intend to use to study the temperature dependence of the piezo-optic effect. We build a prototype based on the initial concept of the piezo-optic pressure sensor presented in Part III, and test its response to pressure. Its behaviour is found to be coherent with theoretical predictions, and these measurement serve to validate the concept of the sensor that was developed during this work
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Vincent, David Robert. "Integrated design for an optically driven micromachined silicon pressure transducer." Thesis, University of Southampton, 1993. https://eprints.soton.ac.uk/394151/.
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Pakdel, Zahra. "Characterization, Modeling of Piezoelectric Pressure Transducer for Facilitation of Field Calibration." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/76791.
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Currently in the marketplace, one of the important goals is to improve quality, and reliability. There is great interest in the engineering community to develop a field calibration technique concerning piezoelectric pressure sensor to reduce cost and improve reliability.
This paper summarizes the algorithm used to characterize and develop a model for a piezoelectric pressure transducer. The basic concept of the method is to excite the sensor using an electric force to capture the signature characteristic of the pressure transducer.
This document presents the frequency curve fitted model based on the high frequency excitation of the piezoelectric pressure transducer. It also presents the time domain model of the sensor. The time domain response of the frequency curve fitted model obtained in parallel with the frequency response of the time domain model and the comparison results are discussed. Moreover, the relation between model parameters and sensitivity extensively is investigated.
In order to detect damage and monitor the condition of the sensor on line the resonance frequency comparison method is presented. The relationship between sensitivity and the resonance frequency characteristic of the sensor extensively is investigated. The method of resonance monitoring greatly reduces the cost of hardware.
This work concludes with a software implementation of the signature comparison of the sensor based on a study of the experimental data. The software would be implemented in the control system.Master of Science
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Sorvoja, H. (Hannu). "Noninvasive blood pressure pulse detection and blood pressure determination." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514282728.
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Abstract
This thesis describes the development of pressure sensor arrays and a range of methods suitable for the long-term measurement of heart rate and blood pressure determination using a cuff and a pressure sensor array on the radial artery. This study also reviews the historical background of noninvasive blood pressure measurement methods, summarizes the accuracies achieved and explains the requirements for common national and international standards of accuracy.
Two prototype series of pressure transducer arrays based on electro-mechanical film (EMFi) were designed and tested. By offering high (∼TΩ) resistance, EMFi is an excellent material for low-current long-term measurement applications. About 50 transducer arrays were built using different configurations and electrode materials to sense low-frequency pressure pulsations on the radial artery in the wrist. In addition to uniform quality, essential requirements included an adequate linear response in the desired temperature range. Transducer sensitivity was tested as a function of temperature in the range of 25–45 °C at varying static and alternating pressures. The average sensitivity of the EMFi used in the transducers proved adequate (∼2.2 mV/mmHg and ∼7 mV/mmHg for normal and high sensitive films) for the intended purpose.
The thesis also evaluates blood pressure measurements by the electronic palpation method (EP) and compares the achieved accuracy to that of the oscillometric method (OSC) using average intra-arterial (IA) blood pressure as a reference. All of these three measurements were made simultaneously for each person. In one test group, measurements were conducted on healthy volunteers in sitting and supine position during increasing and decreasing cuff pressure. Another group, comprising elderly cardiac patients, was measured only in the supine position during cuff inflation. The results showed that the EP method was approximately as accurate as the OSC method with the healthy subjects and slightly more accurate with the cardiac patient group. The advantage of the EP method is that also the wave shape and velocity of arterial pressure pulses is available for further analysis, including the assessment of arterial stiffness.
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Dowden, Matthew Richard Barcroft. "Using Pressure Transducers for Noninvasive Heart and Respiratory Monitoring." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/34214.
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Detecting heart and respiratory rates is an essential means of providing emergency medical care. Current methods of detecting such signals include the widely used electrocardiography (ECG) method. Other more manual methods of heart and respiratory rate estimation require a practitioner to constantly observe the patient. These methods are time consuming and detract valuable time from emergency medical care. This thesis presents a novel, hands off, heart and respiratory monitor (HARMONI). It uses pressure transducers and medical tubing placed on a personâ s chest. The tubing is plugged off at one end, and then attached to a pressure transducer at the other end. The transducer sees spikes in voltage whenever the pressure inside the tubing changes. Heart and respiratory rates both cause expansion in the chest, increasing the pressure in the tubing, and causing the transducer to see a change in voltage. The method was first validated, and then tested in a simulated environment. Finally, the device was transformed in to a full system prototype. Human tests were conducted to correlate the signal with that of an industry standard ECG device. This thesis explains how heart and respiratory rates can be derived using signal processing techniques and a simple non-invasive sensor. This device is a rapidly deployable tool that has the potential to save lives specifically in mass casualty situations. It would be a force multiplier, allowing a single responder to monitor multiple casualties, saving time and lives.Master of Science
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CABRERA, LIZETH STEFANÍA BENAVIDES. "HIGH SENSITIVITY PRESSURE TRANSDUCER FOR BIOMEDICAL APPLICATIONS, BASED ON GMI SENSOR PHASE READING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=31070@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Esta dissertação tem por objetivo o desenvolvimento de um transdutor de pressão de alta sensibilidade, baseado nas características de fase da impedância de sensores de Magnetoimpedância Gigante. A configuração do dispositivo visa a aplicações biomédicas, tais como medições da onda de pulso arterial e de sua velocidade de propagação. Projetou-se um sistema de transdução de pressão em tensão, que contém um módulo intermediário baseado em um magnetômetro GMI. O protótipo implementado inclui uma estrutura mecânica, responsável pela transdução de pressão em campo magnético, e um circuito eletrônico, responsável pela conversão deste em uma tensão elétrica de saída. A conversão de pressão em campo magnético é feita por meio de uma fonte de campo magnético aderida a uma membrana elástica. Foram realizados estudos comparativos empregando agulhas magnetizadas e ímãs permanentes como fontes móveis de campo. Por sua vez, o elemento sensor GMI utilizado foi experimentalmente caracterizado, a fim de se obter suas curvas características de módulo e fase, em função do campo magnético. O circuito eletrônico de transdução foi projetado e avaliado de forma computacional e experimental. As principais características do mesmo são detalhadas ao longo do texto e as previsões teórico-computacionais são comparadas com os resultados experimentais obtidos. Por sua vez, parâmetros chave do protótipo desenvolvido são minuciosamente analisados, tais como: sensibilidade, linearidade e resposta em frequência. Também, avalia-se a densidade espectral de ruído do transdutor desenvolvido e estima-se sua resolução na banda de passagem. Os resultados obtidos indicam que o protótipo de baixo custo desenvolvido apresenta alta resolução e alta sensibilidade, além de uma banda de passagem compatível com a requerida pelas aplicações biomédicas nas quais deseja-se empregá-lo. Dessa forma, espera-se que o dispositivo desenvolvido contribua para o avanço tecnológico do ferramental utilizado no setor da saúde.
This dissertation aims at the development of a high sensitivity pressure transducer, based on the phase impedance characteristics of Giant Magnetoimpedance sensors. The configuration is intended to employ the developed device in biomedical applications, such as in measurements of arterial pulse wave and pulse wave velocity. A transduction system of pressure into voltage was designed, which contains an intermediate module based on a GMI magnetometer. The idealized prototype contains a mechanical structure, responsible for converting pressure into magnetic field, and an electronic circuit, responsible for converting the latter into a voltage output. The conversion of pressure into magnetic field is performed by means of a magnetic field source adhered to an elastic membrane. Comparative studies were carried out using magnetized needles and permanent magnets as field sources. In turn, the GMI sensor element was experimentally characterized in order to evaluate how its impedance magnitude and phase are affected by the magnetic field. The influence of the cable length used to interconnect the GMI sensor to the electronic circuit is also discussed. The electronic transduction circuit was designed and analyzed by computational and experimental evaluations. The main features of the circuit are detailed throughout the text and the theoretical and computational predictions are compared with the obtained experimental results. Furthermore, the key parameters of the developed prototype are meticulously analyzed, such as: sensitivity, linearity and frequency response. Also, the spectral noise density of the developed transducer is evaluated and its resolution in the passband is estimated. The obtained results indicate that the developed prototype presents low cost of manufacture and operation, high resolution, high sensitivity and a passband compatible with the requirements imposed by the biomedical applications of interest. In this way, it is intended that the device developed in the present Dissertation contributes to the technological enhancement of measurement equipment used in health sector.
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Panhorst, Eric M. "Evapotranspiration Measurement and Simulation due to Poplar Trees at a Phytoremediation Site." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33648.
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A railroad yard in Oneida, Tennessee was contaminated with creosote in the 1950s and 1960s through cross tie treatment. The problem was discovered in 1990 and phytoremediation in combination with an interception trench was chosen as the remediation strategy. Hybrid poplar trees (1,036) were planted in 1997 within 0.7 acres. The goals of the phytoremediation system are to prevent migration of the contaminant off the site and clean up the contaminant in-situ. This study is focused on quantifying the rate of evapotranspiration of the phytoremediation system and then determining the effect on groundwater flow. This will be accomplished by quantifying evapotranspiration using a water budget, applying White's Equation, comparing groundwater recession curves, creating a groundwater flow model, and examining water table elevations obtained at the site. Calculations of water use by the poplar trees in early September 1999 ranged from 0.62 to 1.34 gal/day/tree. The volume of evapotranspiration calculated for the trees during 1999 is 140,292 gallons. Total evapotranspiration determined by the water budget for 1998 is 1,570,064 gallons. Evaluation of the water level data over a period of several years shows significant lowering of the water table (fluctuations of up to four feet) during the summer and fall months due to evapotranspiration. Although calculated evapotranspiration rates are not as high as seen in the literature, continued monitoring of the site should show large increases in evapotranspiration rates in the future as the poplar trees mature.Master of Science
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Ferezin, Evaldo. "Modelagem dinâmica de transdutor de pressão piezorresistivo para sistemas hidráulicos através de dados experimentais da resposta à entrada degrau." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-05022016-133734/.
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Este trabalho apresenta a modelagem da parte dinâmica de dois transdutores de pressão tipo piezorresistivo. Geralmente processos de calibração dinâmica usam bancadas sofisticadas, mas neste trabalho procurou-se um processo simples e de baixo custo. A metodologia baseou-se em aumentar lentamente a pressão, fornecida por um sistema hidráulico básico, até que ocorresse a explosão de um diafragma e, com isso, obteve-se um degrau de pressão, supostamente ideal. Considerado como sistemas lineares, com a resposta obtida verificou-se qual a ordem e o tipo de sistema correspondente à resposta do transdutor. Através dos dados experimentais determinou-se os parâmetros dinâmicos do modelo matemático. Foram obtidos modelos matemáticos lineares de segunda ordem de cada transdutor. As respostas dos modelos mostram ter uma concordância satisfatória quando comparadas aos dados experimentais.This work presents a dynamic modeling method for two hydraulic piezoresistive pressure transducers. Usually the dynamic calibration processes apply sophisticated devices, but in this work a simple and low cost process was searched. The methodology was based on increasing the pressure slowly, supplied by a basic hydraulic system, up to a diaphragm explosion, assumed as an ideal step pressure variation. Considered as linear systems, the responses obtained were verified and compared with a second order linear system. Using the experimental data, the dynamic parameters of the mathematical model were determined for each of the two transducers. The theoretical responses of the models showed to have a satisfactory agreement when compared with the experimental data.
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Sharifian, Seyed Ahmad. "Fibre optic pressure transducers for disturbance measurements in transient aerodynamic research facilities." University of Southern Queensland, Faculty of Engineering and Surveying, 2003. http://eprints.usq.edu.au/archive/00001509/.
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Experiments in the study of transient aerodynamics typically require pressure measurements with a high spatial and temporal resolution. Existing commercial pressure transducers are expensive and they provide a spatial resolution only on the order of millimetres. The full bandwidth of commercial devices (which extends to around 200 kHz) can only be utilised by exposing the transducer to the flow environment with very little thermal or mechanical protection. If insufficient protection is provided, the expensive commercial devices are likely to be damaged. Inexpensive pressure sensors based on extrinsic Fabry-Perot fibre optic interferometry are capable of measurement with a high spatial and temporal resolution. Thermal protection or isolation for these sensors is still required, but they can be exposed directly to the flow if the sensors are disposable (low cost). Excessive thermal or mechanical protection is not required for these sensors because the damaging heat transfer and particle impacts that may occur in transient aerodynamic facilities generally occur after the useful test flow. In this dissertation, a variety of construction techniques for diaphragm-based Fabry-Perot fibre optic pressure sensors were investigated and the advantages and disadvantages of all techniques are compared. The results indicate that using a zirconia ferrule as the substrate, a liquid adhesive as the bonding layer, and a polished copper foil as the diaphragm provide the best results. It is demonstrated that a spatial resolution on the order of 0.1 mm and a bandwidth to more than 100 kHz can be achieved with such constructions. A variety of problems such as hysteresis, response irregularity, low visibility and sensor non-repeatability were observed. By using a thinner bonding layer, a larger bonding area, longer cavity length, increased calibration period, and applying load cycling to the diaphragm, the hysteresis was minimized. Sensor response irregularity was also minimized using a polished diaphragm. Visibility increased to about 90% using active control of the cavity length during the construction process. Non-repeatability was found to be a consequence of adhesive viscoelasticity and this effect was minimized using a thin layer of adhesive to bond the diaphragm to the substrate. Due to the effects of adhesive viscoelasticity, the pressure sensors indicate an error of up to 10% of mean value for the reflected shock pressure. This error could not be further reduced in the current sensors configuration. Some new configurations are proposed to decrease the effect of sensor non-repeatability. The effect of pretensioning the diaphragm was investigated analytically but the results do not indicate any considerable advantage for the levels of pretension likely to be achieved in practice. However, the results do indicate that pretension effects caused by an environmental temperature change can damage the sensor during storage. The effect of the initial diaphragm deflection on the sensor performance and temperature sensitivity was modelled and the results show that an initial diaphragm deflection can improve the sensor performance. The effect of the thermal isolation layer on the sensor performance was also investigated and the results show that for a shock tube diaphragm bursting pressure ratio up to 5.7, heat transfer does not contribute to sensor errors for the first millisecond after shock reflection. However, it was found that the use of a thin layer of low viscosity grease can protect the sensor for about 20 ms while only decreasing its natural frequency by typically 17%. The grease layer was also found to decrease the settling time of a low damping ratio sensor by 40%. The sensor was successfully employed to identify an acoustic disturbance in a shock tube.
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Maher, Theresa Anne. "Development of a transducer for detecting pressure load between a garment and the body." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-03172010-020357/.
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Harris, David Malcolm. "The effect of pre-exposing the microbial population on gas production using the Pressure Transducer Technique." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242337.
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Alibrahim, Anas. "The measurement of maximal bite force in human beings." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/73283c8a-eee6-468b-8300-b79c12ad9f51.
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Background: Registering a true maximum bite force on the most commonly-used force transducers is problematic. It is often believed that this is related mainly to discomfort and the fear of breaking teeth. Objectives: The aim of the project was to compare the suitability of different bite force measuring transducers including ones which were designed to improve subject comfort. The transducers used were a traditional strain-gauge transducer with and without covering with ethylene vinyl acetate (EVA) sheets, and a newly-developed pressure transducer. Methods: Five separate studies were performed in this project. The experiments were carried out on human volunteer subjects (aged 24 to 41 years). They were all dentate with no missing anterior teeth and with no crowns on these teeth. The following procedures were used in some or all of the studies: measurement of MVBF, electrical stimulation of the masseter muscle, and EMG recording from two pairs of jaw closing muscles. Results: The highest MVBF values were recorded on the pressure transducer, mean (± S.D.) 464 N ± 224 N; followed by the strain-gauge transducer with EVA sheets, 243 ± 80 N; and last of all the strain-gauge transducer with silicone indices, 165 ± 35 N; or acrylic indices, 163 ± 82 N. Significantly higher maximum potential bite forces were predicted by twitch interpolation for the pressure transducer (730 ± 199 N) than for the strain-gauge transducer with EVA sheets, 354 ± 67 N (Paired t test, P < 0.05). Significantly higher EMGs of the masseter and anterior temporalis muscles were found to be associated with MVBFs on the pressure transducer than with MVBFs on the strain-gauge transducer with EVA sheets (Paired t test, P < 0.05). Conclusions: It is concluded that: a) the pressure transducer system and to a lesser extent the strain-gauge transducer covered with EVA sheets seemed to overcome the fear associated with biting on the hard surfaces of the strain-gauge transducer alone; b) the pressure transducer may have some multi-directional capabilities which allow for total bite forces, or at least larger parts of them, to be recorded than on a uni-directional strain-gauge transducer.
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Dominguez, Ontiveros Elvis Efren. "Wall-pressure and PIV analysis for microbubble drag reduction investigation." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2582.
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The effects of microbubbles injection in the boundary layer of a turbulent channel flow are investigated. Electrolysis demonstrated to be an effective method to produce microbubbles with an average diameter of 30 ??m and allowed the placement of microbubbles at desired locations within the boundary layer.
Measurement of velocity fluctuations and the instantaneous wall shear stress were carried out in a channel flow facility.
The wall shear stress is an important parameter that can help with the characterization of the boundary layer. This parameter can be obtained indirectly by the measurement of the flow pressure at the wall.
The wall shear stress in the channel was measured by means of three different independent methods: measurement of the pressure gradient by a differential pressure transducer, Particle Image Velocimetry (PIV), and an optical wall shear stress sensor. The three methods showed reasonable agreement of the wall shear stress values for single-phase flow. However, differences as skin friction reductions were observed when the microbubbles were injected. Several measurements of wall-pressure were taken at various Reynolds numbers that ranged from 300 up to 6154. No significant drag reduction was observed for flows in the laminar range; however, a drag reduction of about 16% was detected for turbulent Reynolds numbers.
The wall-pressure measurements were shown to be a powerful tool for the measurement of drag reduction, which could help with the design of systems capable of controlling the skin friction based on feedback given by the wall-pressure signal.
The proposed measurement system designed in this work has capabilities for application in such diverse fields as multiphase flows, drag reduction, stratified flows, heat transfer among others. The synchronization between independent systems and apparatus has the potential to bring insight about the complicated phenomena involved in the nature of fluid flows.
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Jenne, Kirk E. "Acoustic cymbal transducers-design, hydrostatic pressure compensation, and acoustic performance." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FJenne.pdf.
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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, March 2004.Thesis advisor(s): Thomas R. Howarth, Dehua Huang. Includes bibliographical references (p. 67-69). Also available online.
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LOUZADA, DANIEL RAMOS. "DEVELOPMENT OF A HIGH SENSITIVITY PRESSURE TRANSDUCER, BASED ON THE PHENOMENON OF GIANT MAGNETOIMPEDANCE EFFECT, FOR BIOMEDICAL APPLICATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9237@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORA presente dissertação apresenta o desenvolvimento de um transdutor de pressão de alta sensibilidade, desenvolvido para aplicações biomédicas. O transdutor é baseado em um sensor de magnetoimpedância gigante (MIG), anteriormente desenvolvido, pelo Laboratório de Biometrologia da PUC-Rio. O conhecimento a cerca das principais características do fenômeno MIG serviu de guia para as ações que foram tomadas, a fim de se estabelecer uma configuração que apresentasse maior sensibilidade ao transdutor. Mesmo que algumas dificuldades encontradas, principalmente devidas a características acústicas não levadas em consideração, apontem para a necessidade de aperfeiçoamentos, com a configuração desenvolvida no presente trabalho já é possível obter o registro do pulso arterial carotídeo. Comparações entre o transdutor ora desenvolvido e com outros transdutores de pressão existentes no mercado também destinados a aplicações biomédicas, apontam para uma sensibilidade do transdutor ora desenvolvido de magnitude igual ou mesmo superior aos convencionais.
This dissertation presents a high sensitivity pressure transducer, developed for biomedical applications. The transducer is based on a Giant Magnetoimpedance (GMI) sensor previously developed at the Laboratory of Biometrology of PUC-Rio. Knowing the main characteristics of the phenomenon and of the GMI strips used, the configuration which should yield the highest possible sensitivity has been implemented. Even though some enhancements in the acoustic characteristics of the transducer are still necessary, it was already possible to record the carotid arterial pulse. Comparing the transducer herein presented with other pressure transducers also destined to biomedical applications, it already has a sensitivity of the same order of magnitude or even higher.
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Sileshi, Zinash. "Development of a simple in vitro gas production technique, using a pressure transducer, to estimate digestion of some Ethiopian forages." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241462.
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Yantzer, Brenda Kay. "Torsion-Induced Pressure Distribution Changes in Human Intervertebral Discs: an In Vitro Study." [Tampa, Fla] : University of South Florida, 2005. http://purl.fcla.edu/usf/dc/et/SFE0001397.
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Dibaji, Seyed Ahmad Reza. "Nonlinear Derating of High Intensity Therapeutic Ultrasound Beams using Decomposition of Gaussian Mode." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1458900246.
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Dvoracek, Pavel. "Hydrogeological framework, conceptual and numerical groundwater flow model of Laidley Creek catchment, Queensland, Australia." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61559/2/Pavel_Dvoracek_Thesis.pdf.
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This thesis studies the water resources of Laidley Creek catchment within the Lockyer Valley where groundwater is used for intensive irrigation of crops. A holistic approach was used to consider groundwater within the total water cycle. The project mapped the geology, measured stream flows and groundwater levels, and analysed the chemistry of the waters. These data were integrated within a catchment-wide conceptual model, including historic and rainfall records. From this a numerical simulation was produced to test data validity and develop predictions of behaviour, which can support management decisions, particularly in times of variable climate.
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Філіпова, Н. Ю. "Дослідження роботи сферичного електропружного п’єзокерамічного перетворювача з акустичним заповненням." Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/63903.
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Сучасні підводні електроакустичні перетворювачі набули досить складних конструкцій в зв’язку з технологічними прийомами закріплення, забезпечення електроізоляції, герметизації і необхідної міцності перетворювачів. Гідростатичний тиск являється одним з основних факторів, що впливає на ефективність, розміри, вартість перетворювача та можливості його використання. Отже, створення конструкції перетворювача, що протидіє зовнішньому гідростатичному тиску з врахуванням особливостей взаємодії механічних, акустичних та електричних полів, а також способів елекродування і використання електричного навантаження електродів є сучасною актуальною задачею.
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Leschka, Stephan. "Entwurfsmethoden und Leistungsgrenzen elektromechanischer Schallquellen für Ultraschallanwendungen in Gasen im Frequenzbereich um 100 kHz." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1134573918125-13603.
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Air-borne ultrasonic transducers are optimised to achieve a maximal sound pressure in a frequency range around 100 kHz. Moreover, the radiation of a high acoustic power is desired, which requires a large transducer area. Within this dissertation the ultrasonic transducers are, therefore, optimised to operate in the resonance mode. Using this operating point the maximal force is fed into the transducer while it is charged with the lowest loss possible. Many applications of air-borne ultrasound need a sufficient bandwidth in addition to a high sound pressure, that s why the swinging mass of the transducer has to be minimised. For these reasons, air-borne capacitive and piezoelectric film transducers take centre stage of these examinations. New network models of the stripe membrane and the pre-stressed stripe plate are derived to optimise these ultrasonic transducers. Besides its mechanical tension and its bending stiffness, the new network model of the pre-stressed and pressure loaded stripe plate takes also the stiffness caused by the shape of the plate into account. The examined transducers achive a maximal piston velocity around 1 m/sUltraschallwandler für Anwendungen in Luft werden zur Bereitstellung eines maximalen Schalldrucks im Frequenzbereich um 100 kHz optimiert. Sie sollen außerdem die Abstrahlung einer großen Schallleistung zulassen, was eine große Wandlerfläche voraussetzt. Deshalb werden in dieser Arbeit die Ultraschallsender für den Resonanzbetrieb optimiert, wo man die maximale Krafteinspeisung bei minimalen Verlusten einstellt. Viele Anwendungen von Ultraschall in Luft benötigen neben einem hohen Schalldruckpegel auch eine ausreichende Bandbreite, wozu die schwingende Masse der Wandler zu minimieren ist. Deshalb stehen kapazitive und piezoelektrische Folienwandler im Resonanzbetrieb im Vordergrund der Untersuchungen. Zur Optimierung dieser Ultraschallsender werden die Netzwerkmodelle der Streifenmembran und der gespannten Streifenplatte abgeleitet. Neben der mechanischen Spannung und der Biegesteifigkeit berücksichtigt das Netzwerkmodell der gespannten und statisch druckbelasteten Streifenplatte die Formversteifung. Die untersuchten Wandler erreichen eine maximale Kolbenschnelle um 1 m/s
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Leschka, Stephan. "Entwurfsmethoden und Leistungsgrenzen elektromechanischer Schallquellen für Ultraschallanwendungen in Gasen im Frequenzbereich um 100 kHz." Doctoral thesis, Technische Universität Dresden, 2003. https://tud.qucosa.de/id/qucosa%3A24606.
Full textAbstract:
Air-borne ultrasonic transducers are optimised to achieve a maximal sound pressure in a frequency range around 100 kHz. Moreover, the radiation of a high acoustic power is desired, which requires a large transducer area. Within this dissertation the ultrasonic transducers are, therefore, optimised to operate in the resonance mode. Using this operating point the maximal force is fed into the transducer while it is charged with the lowest loss possible. Many applications of air-borne ultrasound need a sufficient bandwidth in addition to a high sound pressure, that s why the swinging mass of the transducer has to be minimised. For these reasons, air-borne capacitive and piezoelectric film transducers take centre stage of these examinations. New network models of the stripe membrane and the pre-stressed stripe plate are derived to optimise these ultrasonic transducers. Besides its mechanical tension and its bending stiffness, the new network model of the pre-stressed and pressure loaded stripe plate takes also the stiffness caused by the shape of the plate into account. The examined transducers achive a maximal piston velocity around 1 m/s.Ultraschallwandler für Anwendungen in Luft werden zur Bereitstellung eines maximalen Schalldrucks im Frequenzbereich um 100 kHz optimiert. Sie sollen außerdem die Abstrahlung einer großen Schallleistung zulassen, was eine große Wandlerfläche voraussetzt. Deshalb werden in dieser Arbeit die Ultraschallsender für den Resonanzbetrieb optimiert, wo man die maximale Krafteinspeisung bei minimalen Verlusten einstellt. Viele Anwendungen von Ultraschall in Luft benötigen neben einem hohen Schalldruckpegel auch eine ausreichende Bandbreite, wozu die schwingende Masse der Wandler zu minimieren ist. Deshalb stehen kapazitive und piezoelektrische Folienwandler im Resonanzbetrieb im Vordergrund der Untersuchungen. Zur Optimierung dieser Ultraschallsender werden die Netzwerkmodelle der Streifenmembran und der gespannten Streifenplatte abgeleitet. Neben der mechanischen Spannung und der Biegesteifigkeit berücksichtigt das Netzwerkmodell der gespannten und statisch druckbelasteten Streifenplatte die Formversteifung. Die untersuchten Wandler erreichen eine maximale Kolbenschnelle um 1 m/s.
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Palmer, Jason. "Precise pressure sensor temperature compensation algorithms." Diss., Online access via UMI:, 2007.
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Li, Junhong Li. "Pier Streamlining as a Bridge Local Scour Countermeasure and the Underlying Scour Mechanism." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1518565785864439.
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Михайленко, Ігор Всеволодович. "Напівпровідникові перетворювачі механічних величин з використанням поперечних тензоефектів." Thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/30025.
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Дисертація присвячена розробленню фізико-технологічних засад створення та дослідженню перетворювачів механічних величин на основі поперечних ефектів в анізотропних напівпровідниках.
Розроблені фізичні основи побудови перетворювачів механічних величин з використанням поперечних ефектів і проведено їх дослідження на експериментальних зразках. Продемонстрована перспективність використання перетворювачів на основі ефекту тензо-е.р.с. як в дискретному, так і в інтегральному виконанні для створення датчиків сили і тиску, які працюють в діапазоні температур 233-373 K. Виявлений ряд концентраційних ефектів у германії і запропоновані перетворювачі оригінальних конструкцій, таких як диференціальний тензотранзистор, безконтактний лінійний датчик переміщень на основі магнітоконцентраційного ефекту, порогові датчики кута повороту і сили на основі осцилісторного ефекту з можливістю управління порогом переключення. Дослідження, що проведені, підтверджують перспективність практичного використання поперечних ефектів у багатодолинних напівпровідниках для створення перетворювачів механічних величин.The purpose of the work is to develop a physical basis for transducers of mechanical values design and technology using transverse tenso-effects. The object of the research - characteristics of transverse effects caused by induced anisotropy in Si and Ge. The subject of research are transducers of mechanical values based on the transverse tenso-effects in Si and Ge. The result of the research is the development of both MEMS integrated pressure transducers and the industrial device for measuring the pressure of liquid media. The introduction substantiates the relevance of the topic, shows the relationship with scientific programs and plans, formulates purpose and objectives of scientific research, outlines the novelty and practical significance of the results obtained, indicates the personal contribution of the applicant, provides data on the validation of the results The First chapter analyzes phenomena leading to transverse effects. Consideration given in terms of anisotropy of conductivity, which is interpreted as the non-collinearity of the vectors of electric field and current. It allows using similar formal apparatus in the analysis of various effects. In particular, the cases of anisotropy induced by deformation and magnetic field have been examined. The Second chapter is devoted to the study of discrete tenso-emf transducers. In the proposed tenso-emf transducers, problems of matching the temperature dependencies of the sensitivity and impedances of individual strain gages are virtually eliminated. The dynamic range of the non-fixed tenso-emf transducer was about 120 dB. The Third chapter contains the results of the design and study of transducers using concentration effects in Ge in combination with other physical effects. New types of mechanical transducers proposed, such as differential tenso-transistor, non-contact linear displacement sensor, threshold angle sensors, and oscillistor-effect based force sensor. The Fourth chapter is devoted to the development of an integrated pressure transducer using MEMS technology. Problems of the physical principle of sensing element operation, optimization of the elastic element topology and design of the converter as a whole, as well as a choice of optimal manufacturing technology processes, are solved here. The sensitivity of the integrated transducer with a membrane thickness of 100 μm was 0.02 1/MPa at a nominal conversion range of 1 MPa and a 100% strength margin. Tests of the manufactured series of MEMS integrated transducer showed that the additive component of the error and its change in the range 233-373 K are, respectively, 1% and 1% ... 2% of the nominal signal, which is at least an order of magnitude smaller than the corresponding parameters of a strain gauge Wheatstone bridge. The Fifth chapter describes the design and test results of devices developed on the basis of tenso-emf transducers research. Such devices, introduced for industrial use, are remote manometer transducers PDM-2 and PDMT-1. These devices are designed to measure oil and bitumen wells pressure in the range 0 ... 2.5 MPa, with a nominal output signal of 100 mV. In addition, PDMT-1 transmits information about temperature. The PDM-2 device has passed the State Testing and was recommended for serial production. The conducted studies confirm the high potential of the practical application of transverse effects in multi-valley semiconductors for the development of mechanical values sensors.
Диссертация посвящена разработке физико-технологических принципов создания и исследованию преобразователей механических величин на основе поперечных эффектов в анизотропних полупроводниках. Разработаны физические основы построения преобразователей механических величин с использованием поперечных эффектов и проведено их исследование на экспериментальных образцах. Продемонстрирована перспективность использования преобразователей на основе эффекта тензо-э.д.с. как в дискретном, так и в интегральном исполнении для создания датчиков силы и давления, работающих в диапазоне температур 233-373K. Обнаружен ряд концентрационных эффектов в германии и предложены преобразователи оригинальных конструкций, таких как дифференциальный тензотранзистор, бесконтактный линейный датчик перемещений на основе магнитоконцентрационного эффекта, пороговые датчики угла поворота и силы на основе осциллисторного эффекта с возможностью управления порогом переключения. Проведенные исследования подтверждают перспективность практического использования поперечных эффектов в многодолинных полупроводниках для создания преобразователей механических величин.
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Михайленко, Ігор Всеволодович. "Напівпровідникові перетворювачі механічних величин з використанням поперечних тензоефектів." Doctoral thesis, Київ, 2019. https://ela.kpi.ua/handle/123456789/30024.
Full textAbstract:
Дисертація присвячена розробленню фізико-технологічних засад створення та дослідженню перетворювачів механічних величин на основі поперечних ефектів в анізотропних напівпровідниках.
Розроблені фізичні основи побудови перетворювачів механічних величин з використанням поперечних ефектів і проведено їх дослідження на експериментальних зразках. Продемонстрована перспективність використання перетворювачів на основі ефекту тензо-е.р.с. як в дискретному, так і в інтегральному виконанні для створення датчиків сили і тиску, які працюють в діапазоні температур 233-373 K. Виявлений ряд концентраційних ефектів у германії і запропоновані перетворювачі оригінальних конструкцій, таких як диференціальний тензотранзистор, безконтактний лінійний датчик переміщень на основі магнітоконцентраційного ефекту, порогові датчики кута повороту і сили на основі осцилісторного ефекту з можливістю управління порогом переключення. Дослідження, що проведені, підтверджують перспективність практичного використання поперечних ефектів у багатодолинних напівпровідниках для створення перетворювачів механічних величин.
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Young, Albert Min-Hsien. "Microfabricated pressure transducers based on anti-resonant reflecting optical waveguides." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12214.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 142-149).
by Albert Min-Hsien Young.
Ph.D.
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Law, Jesse Townsend. "Application of the van der Pauw structure as a piezoresistive pressure sensor a numerical study /." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/law/LawJ0807.pdf.
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Ha, Sang-Woo. "Instrumentation for pressure measurement during thermal decomposition of binders in multilayer ceramic capacitors /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426065.
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Nevill, Andrew John. "A foot pressure measurement system utilising PVdF and copolymer piezoelectric transducers." Thesis, University of Kent, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303993.
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Hulan, Gregory T. "A microprocessor based air pressure controller." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44114.
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A microprocessor based air pressure controller is discussed. The particular
implementation was designed around an existing pressure measurement, and display unit.
The unit is controlled by a 6809 microprocessor. It is shown that due to the many
functions that the unit must perform and control, a microprocessor based system is a
good choice. The controller is economical since it uses standard chips, yet it is very
accurate since it uses state of the art pressure transducers. Experimental results and the
user friendly interface will also be discussed. A commented listing of the controller
software, and the circuit diagrams are appended.
Master of Science
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Harris, John N. "Referenced pressure and temperature sensitive coatings using solid state phosphors /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8577.
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Oram, C. E. "Aerodynamic surface pressure measurement in atmosphere and wind tunnel on a vertical axis wind turbine blade using pressure transducers." Thesis, Cranfield University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375937.
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Qi, Haiming. "Analysis and design of a contact pressure distribution measuring system." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64066.
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Manning, Gavin N. "A new ultrasound intensity meter : characterization and optimization." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26496.
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The principle of operation of a novel rotating disk ultrasonic intensity meter is studied. Its characteristics are explained by a competition between acoustic radiation pressure and viscous drag on the disk. Acoustic streaming does not play a significant role in the operation of this meter as it is now configured.
Experiments are described which were done to find the optimum dimensions and position for a nylon disk. In this optimum configuration, the rotation rate of the disk is related to the ultrasonic intensity by a power law. This relationship is theoretically predicted and found to hold as the ultrasonic intensity varies by a factor of at least ten.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Sprague, Susan, and Andrew Chorney. "A COMPARISON OF METHODS FOR MEASUREMENT OF PRESSURE IN HYDRAULIC LINES." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606795.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThis presentation summarizes a study characterizing strain gages and pressure transducers used to measure the fluid pressure within aircraft hydraulic lines. A series of laboratory calibrations and finite element analyses was performed to demonstrate the quality of data from both pressure transducers and strain gages under variations in both temperature and external strains on the hydraulic lines. Strain gages showed a marked susceptibility to external strains on hydraulic lines, and wide variations in susceptibility to temperature changes. Pressure transducers were found to be relatively immune to both conditions. It is recommended that strain gages be used for trend data only.
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Ferguson, Derek. "The development of air-cooling techniques for fast response pressure transducers in high temperature environments." Thesis, Cranfield University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387639.
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HEINE, ALFREDO JORGE BAHIA. "DEVELOPMENT OF METHODOLOGY FOR CALIBRATING PIEZOELECTRIC TRANSDUCERS USED IN INTERNAL BALLISTICS FOR TRANSIENT PRESSURE MEASUREMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5851@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROEXÉRCITO BRASILEIRO
A presente pesquisa de mestrado, de interesse da indústria de armamento, mais especificamente no controle de qualidade de lotes de munição, relaciona-se com o desenvolvimento de metodologia para calibração de transdutor piezelétrico para medição de pressão transiente cuja duração é da ordem de milisegundos. Como sua principal contribuição, o trabalho disponibiliza metodologia própria de calibração ainda não disponível no País, atribuindo confiabilidade a medições realizadas em fenômenos associados ao que se denomina balística interna, que se constitui no estudo científico dos processos que ocorrem no interior de uma arma de fogo a partir do instante de iniciação (ignição) do propelente. Não obstante a faixa de pressão estudada, de 34,7 a 349,8 bar), ser baixa se comparada com as pressões desenvolvidas na balística interna, que podem até superar 6000 bar, a simples substituição do gerador de pressão por outro de maior capacidade é suficiente para a calibração numa faixa mais larga utilizando-se a mesma metodologia. O complexo processo de balística interna foi simulado em condições laboratoriais pela submissão brusca do sensor piezelétrico, objeto da calibração, originalmente montado em uma câmara diminuta (cerca de dez vezes menor que o volume total de fluido pressurizado) de óleo à pressão atmosférica, a um pico de pressão induzido pela comunicação da câmara a uma linha de óleo pressurizada à pressão de calibração pré-determinada através de uma bomba hidráulica, pressão esta que caracteriza um ponto de calibração. Complementando o aparatus experimental utilizado para simular o fenômeno da balística interna, foi utilizado um sistema de medição com tempo de resposta compatível (rise time < 5 us) à ordem de grandeza da duração do fenômeno estudado. O aparatus experimental utilizado é tal que permite alterar a duração desses eventos por meio de uma válvula de restrição, o que resultou em eventos com duração de 2 a 2200 ms. O monitoramento do sinal de resposta do transdutor piezelétrico no curso da calibração realizada permite estabelecer o tempo-limite associado ao qual o sinal mantém-se isento de indesejável atenuação, considerada fonte de erro na medição de pressão. O processo de calibração desenvolveu-se para 10 pontos distintos, perfazendo um total de 340 experimentos (variando-se o transiente de pressão imposto ao transdutor), monitorando-se o sinal de resposta do transdutor contra o valor da pressão medida por um manômetro calibrado pelo laboratório de pressão da PUC-Rio, credenciado pelo INMETRO e, portanto, assegurando rastreabilidade das medições ao Sistema Internacional de Unidades. Alterações no aparatus experimental permitem que calibrações usualmente realizadas em regime de pressurização sejam também realizadas em regime de despressurização, viabilizando, dentre outras análises possíveis, o estudo de estabilidade e histerese do sinal do transdutor. O método experimental desenvolvido não apenas mostrou-se tecnicamente viável e adequado às condições laboratoriais da faixa de pressão na qual foi validado (34,7 a 349,8 bar), como também se mostrou viável economicamente. A incerteza associada a esse método, obviamente, é maior que aquela obtida com uma balança de peso morto, que se baseia num método primário. A incerteza associada ao método de calibração desenvolvido no presente trabalho de pesquisa pode ser diminuída se for usado um sistema de medição de tensão com melhor exatidão.
The current research, of armaments industry s interest, more specifically in the quality control of ammunition lots, is related to the development of methodology for calibrating piezoelectric transducers for transient pressure measurements associated with events whose duration is of the order of milliseconds. As its main contribution, this work presents proper methodology, not available yet in the Country, to ensure reliability to measurements of pressure in internal ballistics, which is the scientific study of the operating processes within the gun from at the moment when the burning process of the propellant is initiated. In spite of the low transient pressure range studied, 34,7 to 349,8 bar, when compared with the pressures developed in internal ballistics, up to 6000 bar, the simple replacement of the pressure generator for another one of larger capacity is enough to allow for calibration in a wider pressure range using the same methodology. The complex process associated to internal ballistics was simulated in laboratorial conditions by the abrupt exposure of the piezoelectric sensor, object of the calibration, planned and originally mounted in a small oil chamber (about ten times smaller than the total volume of fluid pressurized) maintained at atmospheric pressure, to a pressure peak introduced by the communication of the small chamber to a line of oil pressurized at a desired calibration pressure level by means of a hydraulical pump used to feed the oil system. Each calibration pressure condition corresponds to what is called a calibration point. Complementing the experimental apparatus used to simulate the phenomenon of the internal ballistics, an adequate measurement system (rise time < 5 us, therefore adequate to the time duration of the studied phenomenon) was used. The experimental apparatus employed is such that the time duration of the events could be changed by means of a restriction valve, allowing events with duration from about 2 to 2200 ms. Within the calibration process, the monitoring of the piezoelectric transducer output signal allowed for establishing a specific time-limit to ensure that the signal remained exempt of undesirable attenuation, considered a source of error in the measurement of the transient pressure. The calibration process was developed for 10 distinct points, totalizing 340 experiments (varying the transient pressure to which the transducer is exposed), monitoring the output signal of the transducer against the value of the pressure measured with a manometer calibrated in the accredited pressure laboratory of PUC-Rio, traceable to the national standard maintained by the Brazilian National Metrology Laboratory (INMETRO) and, therefore, ensuring overall traceability of measurements to the International System of Units (SI). Modifications introduced in the experimental apparatus used allow that calibrations usually carried out under a regime of pressurization may also be carried out under a regime of unpressurization, making possible other studies such as stability and hysteresis of the transducer s output signal. From the technical point of view the experimental method proved to be feasible and suitable to the laboratorial conditions for the pressure range to which it was validated (34,7 to 349,8 bar). It also revealed economically viable. Although validated, the uncertainty associated with the proposed method, obviously is greater than the uncertainty associated with a dead weight tester, which is based on a primary method. However, the uncertainty associated with the method of calibration herein proposed can be minimized whenever a more accurate voltage measurement system is used.
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Slavíček, Ondřej. "Dynamické charakteristiky běžně používaných snímačů tlaku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254445.
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This thesis deals with the dynamic properties of electric pressure transducers. These are properties that are reflected in the measurement of rapid, time-dependent processes. They could be described in two ways. Either by using amplitude and phase frequency response characteristics, or just one particular value. Natural frequency, cutoff frequency or time constant. These parameters indicate the extreme values for the use of measuring devices in the measurement of time-dependent processes. In this work will be described procedures for determining these parameters.
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Zacot, Chimi I. "Shipboard wireless sensor networks utilizing Zigbee technology." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FZacot.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2006.Thesis Advisor(s): Xiaoping Yang. "September 2006." Includes bibliographical references (p. 59). Also available in print.
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Sachanandani, Rajiv M. Lombardo Stephen. "Failure analysis of green ceramic bodies during thermal debinding." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6491.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Stephen Lombardo. Includes bibliographical references.
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Chalfi, Toufik Yacine. "Pressure loss associated with flow area change in micro-channels." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24725.
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Saxey, David W. "A high-resolution superconducting pressure gauge and irreversible magnetic effects in Nb and NbTi wires." University of Western Australia. School of Physics, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0007.
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A high resolution pressure gauge has been developed for use in thermodynamic measurements along the lambda line in liquid helium. The gauge was designed to operate at cryogenic temperatures and provide pressure measurements up to 30bar, with an accuracy of 3 × 10¯¹ºbar in a 1Hz bandwidth. Experiments reported here show the gauge to have met these specifications; at least for measurements close to zero pressure, at temperatures close to 4.5K. It is expected that operation at higher pressures, and at temperatures closer to the lambda transition, will result in similar or even improved performance. The gauge consists of a titanium-alloy diaphragm with a superconducting position transducer read-out. Compensation techniques internal to the superconducting circuit were used to eliminate any significant sensitivity to temperature fluctuations and in-line acceleration. For high values of common-mode rejection, thermal compensation revealed a non-linear temperature characteristic which was exploited to provide a further reduction in the temperature sensitivity. Acceleration compensation was achieved up to a common-mode rejection of more than 78dB. Present performance appears to be limited by thermal gradient fluctuations at low frequencies and at higher frequencies by a noise source which appears to originate beyond the superconducting transducer. It is expected that some further improvement may be gained in this higher frequency band simply by trapping a larger persistent current in the superconducting circuit. In the course of development and characterization of the gauge several anomalous effects were discovered and investigated. In response to changes in temperature, the gauge was found to exhibit irreversible behaviour in a variety of ways. These phenomena were fully investigated and found to be complex in nature. A critical state model was employed which was successful in explaining many of the observed effects. Other authors have observed apparently related behaviour in samples of niobium and some have developed similar critical state models which give results generally consistent with those reported here. However, these latter works have not investigated the presence of such effects within superconducting wires; neither have they considered the implications for devices based upon superconducting wire circuits. It appears this anomalous behaviour may be relevant to a broad range of instruments employing superconducting wire circuits similar to that used here. If this is the case, the results presented here have significant consequences for the performance of such devices
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Cresta, Tony J. "Biomechanical evaluation of independent transfers and pressure relief tasks in persons with SCI : pilot study." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001807.
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Coraucci, Guilherme de Oliveira. "Sensor de pressão microeletronico baseado no efeito piezoresistivo transversal em silicio." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259037.
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Orientador: Fabiano FruettDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-12T17:39:52Z (GMT). No. of bitstreams: 1 Coraucci_GuilhermedeOliveira_M.pdf: 8439243 bytes, checksum: d062ad2bf9b0e8eaae04ac2443802dab (MD5) Previous issue date: 2008
Resumo: Apresentamos neste trabalho um sensor de pressão piezorresistivo de multiterminais totalmente compatível com o processo de fabricação CMOS, constituído de um piezoelemento sensível ao estresse mecânico disposto sobre uma membrana microfabricada. O layout deste piezoelemento permite maximizar o efeito do estresse mecânico sobre a deflexão das equipotenciais distribuídas sobre sua região ativa. Utilizamos a análise baseada no Método de Elementos Finitos no projeto da membrana, bem como na definição da disposição dos piezoelementos sobre a mesma. O sensor foi fabricado em duas tecnologias diferentes: CMOS 0,3 ?m MAS (Austria Mikro Systeme International) - disponibilizado pelo Projeto Multi-Usuário PMU-FAPESP - e CCS/Unicamp (Centro de Componentes Semicondutores da Unicamp). Realizamos a membrana, no sensor fabricado na tecnologia AMS, através de um processo de desbaste mecânico da pastilha de silício. Já para o sensor fabricado na tecnologia do CCS/Unicamp, utilizamos um aparato de corrosão química (solução de KOH) para corrosão anisotrópica do silício monocristalino e, desta forma, obtivemos uma membrana com maior qualidade. Realizamos o estudo, analítico e numérico, da dependência da tensão de saída do piezoelemento de multiterminais com relação ao estresse mecânico. Os sensores fabricados apresentaram sensibilidade proporcional ao número de contatoscorrente de entrada e pouca dependência desta sensibilidade com sua geometria para uma grande faixa de variação de suas dimensões. Na tecnologia AMS, o sensor apresentou uma sensibilidade de 0,24 mV/psi e na tecnologia CCS/Unicamp 4,8 mV/psi com linearidade máxima de aproximadamente 5,6% FSO
Abstract: This work describes a CMOS-Compatible multiterminal piezoresistive pressure sensor based on the transversal piezoresistive effect, which consists of a piezotransducer fabricated on a membrane. The layout of this piezoelement is designed in such a way that its sensitivity is improved by maximizing the effect of the mechanical stress over the equipotential lines distribution in its active region. We performed Element Finite analyses in both membrane and piezoelement designs. The sensor was fabricated using two different technologies: CMOS 0,35 ?m AMS process (Austria Mikro Systeme International) - supported by the Fapesp Multi-User Project - and CCS/Unicamp process (Center for Semiconductor Components). In the AMS process, we realized a diaphragm by reducing the thickness of the die through a mechanical polishing process. In the sensor fabricated at CCS/Unicamp process, a backside bulk micro-machining was performed by using an automated KOH chemical etching apparatus, which provides a well-controlled anisotropic etching process. The sensor sensitivity is proportional to the number of input current terminals. The sensor sensitivity dependence related to its geometry is minimized even for a wide range of the sensor layout's aspect-ratio. In the AMS process, sensor's sensitivity amounted to 0.24 mV/psi and in the CCS/Unicamp process the sensitivity amounted to 4,8 mV/psi with a maximum linearity of about 5,6% FSO
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
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Pham, Thanh Tuong. "Design, Modeling, and Experiment of a Piezoelectric Pressure Sensor based on a Thickness-Shear Mode Crystal Resonator." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984155/.
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This thesis presents the design, modeling, and experiment of a novel pressure sensor using a dual-mode AT-cut quartz crystal resonator with beat frequency analysis based temperature compensation technique. The proposed sensor can measure pressure and temperature simultaneously by a single AT-cut quartz resonator. Apart from AT-cut quartz crystal, a newly developed Langasite (LGS) crystal resonator is also considered in the proposed pressure sensor design, since LGS can operate in a higher temperature environment than AT-cut quartz crystal. The pressure sensor is designed using CAD (computer aided design) software and CAE software - COMSOL Multiphysics. Finite element analysis (FEA) of the pressure sensor is performed to analyze the stress- strain of the sensor's mechanical structure. A 3D printing prototype of the sensor is fabricated and the proposed sensing principle is verified using a force-frequency analysis apparatus. Next to the 3D printing model verification, the pressure sensor with stainless steel housing has been fabricated with inbuilt crystal oscillator circuit. The oscillator circuit is used to excite the piezo crystal resonator at its fundamental vibrational mode and give the frequency as an output signal. Based on the FEA and experimental results, it has been concluded that the maximum pressure that the sensor can measure is 45 (psi). The pressure test results performed on the stainless steel product shows a highly linear relationship between the input (pressure) and the output (frequency).
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Antony, Albin. "Fault tree analysis for automotive pressure sensor assembly lines." Diss., Online access via UMI:, 2006.
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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Systems Science and Industrial Engineering Department, 2006.Includes bibliographical references.
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Abbas, Syed Farhat. "Development of a low cost shock pressure sensor." Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182538469.
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