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1
Bowe, Elizabeth Anne. "Response of articular and growth plate chondrocytes of biomechanical pressure." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423923.
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Toffin, Eric. "Active control of a coupled plate-cylinder system." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06162009-063337/.
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Davidson, Paul Cameron. "Design of plate panels under biaxial compression, shear and lateral pressure." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46272.
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Chu, Pearl. "Nonaxisymmetric radiation patterns of a vibrating elastic plate." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17902.
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Nasr, Ahmed. "Computational and experimental studies of flow through a plate valve." Thesis, University of Strathclyde, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243954.
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Mohn, Gordon, and Timo Nafz. "Swash plate pumps – the key to the future." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200055.
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Due to many advantages, swash plate pumps are wide spread in hydraulic systems. The main advantages are the through drive capability, the adjustability and most of all, the high power density. Their application range is limited, historically, to 450bar including medium and higher volume sizes. In higher pressure range, constant pumps such as wobbling disks or radial piston pumps are normally used. This is because the higher stressed parts can be dimensioned much bigger. Pumps with lower power such as constant displacement gear pumps are generally used in low price applications. In order to enlarge the application range of swash plate pumps, their advantages have to be further improved and strengthened. This paper shows by example how the pressure of the basic series A4VSO was increased up to a nominal pressure of 630bar and the historical pressure mark of 450bar could be exceeded. This increase in pressure level enables for example steel treatment manufacturers to reduce their component sizes without the need of a pressure transducer. Furthermore the power density of the redesigned HA4VSO was increased by 36%, compared to the standard A4VSO, by significantly increasing the self-priming speed.
On the other side of the application range, in lower power mobile applications such as small tractors, forklift and skid steer loader, there is an increasing demand for less exhaust emissions and better fuel economy. The energy saving potential by changing from a hydraulic system with constant hydraulic pumps to variable hydraulic pumps is already proven on high power applications. By developing the variable axial piston pump A1VO to the requirements of lower horse power application, it is now also possible to realize such savings in lower horse power applications. Furthermore efficiency of the pump itself can be improved. An example of this is shown by way of the new A4 series 33.
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McBrien, Robert K. 1958. "Pressure measurements for periodic fully developed turbulent flow in rectangular interrupted-plate ducts." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65434.
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ADAME, WALLACE MOREIRA. "ON THE ANALYSIS BEHAVIOUR OF CYLINDRICAL PRESSURE VESSELS CONSIDERING PLATE TO SHELL JUNCTION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36065@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Este trabalho apresenta a análise numérica de vasos de pressão cilíndricos modelados por cascas e placas axissimétricas submetidas a carregamento de pressão interna uniformemente distribuída, utilizando-se a técnica de elementos finitos. São consideradas análises de junções entre superfícies com diferentes espessuras, tais como paredes finas (razão entre o raio e a espessura superior a 10) e moderadamente espessas (razão entre o raio e a espessura inferior a 5). Os campos de deslocamento considerados são os referentes aos elementos planos axissimétricos. A partir deste modelo são avaliadas as tensões na transição entre as superfícies e os resultados comparados com soluções analíticas simplificadas. Conclui-se que a solução analítica aproximada é aceitável para uma grande faixa de valores envolvendo placas e cascas de espessuras moderadamente espessas, enquanto que, para paredes finas, a análise por elementos finitos é necessária para verificação do comportamento das tensões na junção. Testes numéricos utilizando o programa ANSYS são apresentados para demonstrar o desempenho de análises lineares axissimétricas, empregando elementos quadráticos em comparação com as soluções analíticas e avaliando também as limitações do modelo analítico na região da descontinuidade geométrica do modelo proposto.
This work presents the numerical analysis of cylindrical pressure vessels, modeled using axisymmetric shells and plates elements under internal pressure loads. The numerical analysis considers surface joints for various surface thickness ratios, from thin (ratio between radius and thickness greater than 10) to thick (ratio between radius and thickness less than 5) shells. Element displacement fields of axisymmetric plane elements are used to evaluate the stress state at the surfaces junctions, and the obtained results are compared to simplified analytical solutions. It is concluded that analytical approximate results present an acceptable solution for a large range of plates to shells geometries up to moderately thick shells, whereas for thin shells the finite element solution is necessary to be considered in order to accurately verify the stresses at plate to shell junction. Numerical tests applying ANSYS program are presented to demonstrate the performance of linear axisymmetric analysis applying quadratic elements in comparison to the analytical solutions also evaluating the limitations of the analytical model in the region of the geometric discontinuity of the proposed model.
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Ferrari, Alberto. "Analytical model for the prediction of wrinkling of rear pressure bulkheads." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8587/.
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In Airbus GmbH (Hamburg) has been developed a new design of Rear Pressure Bulkhead (RPB) for the A320-family. The new model has been formed with vacuum forming technology. During this process the wrinkling phenomenon occurs. In this thesis is described an analytical model for prediction of wrinkling based on the energetic method of Timoshenko. Large deflection theory has been used for analyze two cases of study: a simply supported circular thin plate stamped by a spherical punch and a simply supported circular thin plate formed with vacuum forming technique. If the edges are free to displace radially, thin plates will develop radial wrinkles near the edge at a central deflection approximately equal to four plate thicknesses w0/ℎ≈4 if they’re stamped by a spherical punch and w0/ℎ≈3 if they’re formed with vacuum forming technique. Initially, there are four symmetrical wrinkles, but the number increases if the central deflection is increased. By using experimental results, the “Snaptrhough” phenomenon is described.
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Gresko, Lawrence Sebastian. "Characteristics of wall pressure and near-wall velocity in a flat plate turbulent boundary layer." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14373.
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LaBine, Anne M. "An experimental investigation of pressure of a simple dam break generated wave impacting a plate." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98970.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (page 51).
It is desirable to measure pressure of a wave striking a vertical surface because this information can be used to determine the strength needed in the building materials of marine structures that may be struck by tall waves. These waves may be caused by storms, tsunamis, or dam breaks and can cause serious damage. This thesis presents two experiments aimed at measuring the pressure exerted by a wave. In both experiments, a series of water waves are released from a reservoir. One wave is released at a time and the waves vary in the initial height of water in the reservoir. In the first experiment, pressure is calculated using a force sensor to determine the force on a paddle and a high-speed camera to determine the contact area. It was found that wave pressure increases as the initial height increases. The pressures ranged from 5+/-2kPa at 25+/-1cm initial water height and 12+/-2kPa at 45+/-1cm initial water height. In the second experiment, pressure is measured at multiple vertical and horizontal locations on a vertical cantilevered plate. A sensor located in the middle of the plate horizontally and 1.25in from the bottom recorded the highest maximum pressure for all trials. The pressures from this sensor for this experiment ranged from 1.6+/-0.1kPa at 20+/-1cm initial water height and 7.4+/-.4kPa at 45+/-1cm initial water height.
by Anne M. LaBine.
S.B.
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Huang, Xiaochen, Bing Xu, and Junhui Zhang. "The influence of the swash plate oscillation on pressure ripple in variable displacement axial piston pump." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71101.
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The displacement of the variable displacement pumps can be adjusted by changing the swivel angle of the swash plate. In fact, the swivel angle oscillates because of the oscillating torque on the swash plate, which caused by the pressure fluctuation of the piston chamber. The swivel angle is most often considered as a constant value in previous studies. However, the oscillation of the swash plate leads to an additional movement of the piston, which has an impact on the pressure fluctuation and the flow ripple. In this study, an improved model of a self-supplied variable displacement pump is established. The swash plate oscillation under different operating conditions is presented. In order to investigate the effect of the swash plate oscillation on the pressure ripple, a comparison between the case of the fixed swash plate and the oscillated swash plate is conducted. Results show the pressure ripple with an oscillated swash plate shows a smaller pressure ripple. It also shows that the nine pistons and the control mechanism both affect the pressure ripple and flow fluctuation.
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Stith, Jason C. "RAILROAD TRACK PRESSURE MEASUREMENTS AT THE RAIL/TIE INTERFACE USING TEKSCAN SENSORS." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/213.
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It has been desirable for years to develop non-intrusive/non-invasiveprocedures to determine the pressures and stresses at various levels andinterfaces in the railroad track structure in order to optimize track designs andimprove subsequent track performance. Recent research has developedsatisfactory procedures for measuring pressures in the track structure at theballast/subballast/subgrade levels using earth pressure cells. The researchreported in this thesis documents the development of a technique for measuringthe pressures in the track, at the rail/tie plate/tie interfaces, using a very thinpressure sensitive Tekscan sensor. The Tekscan Measurement System uses asensor composed of a matrix-based array of force sensitive cells, similar to ministrain gauges, to obtain accurate pressure distributions between two surfaces inthe track. This thesis specifically describes: 1) the optimum procedure to installthe sensors into the track, 2) the recommended practices to effectively collectdata with the software, and 3) the accepted techniques for analyzing the results.Both laboratory calibration and in-track testing have been conducted and theresults are presented. The findings attest to the usefulness and practicality of theprocedure for accurately measuring pressures in railroad tracks. The proceduremay also be applicable for a wide variety of specific track related measurementssuch as validating curve geometric criteria, assessing crossing diamond impactpressures, and evaluating the advantages/disadvantages of various types of tieplates, fastenings and tie compositions.
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Abuhaiba, Mohammad. "Mathematical Modeling and Analysis of a Variable Displacement Hydraulic Bent Axis Pump Linked to High Pressure and Low Pressure Accumulators." Connect to full text in OhioLINK ETD Center, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1240528916.
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Dissertation (Ph.D.)--University of Toledo, 2009.Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy degree in Mechanical Engineering." Bibliography: leaves 203-209.
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Zauer, Mario, Frank Meissner, Rudolf Plagge, and André Wagenführ. "Capillary pore-size distribution and equilibrium moisture content of wood determined by means of pressure plate technique." De Gruyter, 2016. https://tud.qucosa.de/id/qucosa%3A38475.
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This paper deals with the determination of the capillary pore-size distribution (CPSD) and equilibrium moisture content (EMC) of untreated and thermally modified (TM) Norway spruce [Picea abies (L.) Karst.] by means of the pressure plate technique (PPT). Desorption experiments were conducted at very high values of relative humidity (RH) in the range between 99.2% and 100%. The thermal modification of spruce results in an alteration of the CPSD, owing to the formation of intercellular cracks in the middle lamella, as a result of cell-wall compression. The desorption curves for both untreated and TM spruce show an extremely upward bend at 99.97% RH. This step reflects an EMC of 38.1% for untreated spruce and 33.8% for TM spruce. None of the samples shrunk during the PPT measurements. Following desorption experiments at 97.4% RH, all samples shrunk. This step reflects an EMC of 27.9% for untreated spruce and 21.7% for TM spruce.
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Mohamed, Aly Ould Sidi Mohamed. "Etude d'un jet d'air plan mince à grande vitesse : action sur une plaque plane." Valenciennes, 1993. https://ged.uphf.fr/nuxeo/site/esupversions/4b2832a5-70ea-4fb4-9ac0-ad724a113a85.
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Le sujet de cette thèse se place dans le cadre des études expérimentales relatives aux jets plans minces a grande vitesse. Les jets étudiés sont caractérisés par des nombres de Reynolds modérés et les buses utilisées sont situées à des faibles distances de la plaque faisant obstacle au jet. L’inclinaison du jet sur la plaque et l'écoulement dans la région du noyau potentiel sont étudiés avec un intérêt particulier. Les expériences menées au cours de cette étude ont montre l'importance du développement des couches limites le long des parois de la buse testée. Les allures des profils de pression et de contrainte de cisaillement sur une plaque plane sont données et sont semblables à celles d'un écoulement incompressible. Des pressions effectives négatives sur la plaque sont enregistrées quand le jet est incline et une explication de ce phénomène est proposée. L’analyse faite dans ce mémoire met en évidence des profils semblables pour la contrainte de cisaillement et apporte des informations concernant la contrainte maximale de cisaillement dans le cas des jets compressibles. Les résultats obtenus dans ce travail sont compares avec des corrélations issues de la littérature et relatives a des jets incompressibles en adaptant ces corrélations. Les distributions de pression et de contrainte de cisaillement sur la paroi obtenues expérimentalement sont utilisées pour valider un calcul fait par la méthode des volumes finis dans le cas de jets compressibles perpendiculaires à la plaque. L’accord entre les résultats expérimentaux et ceux de la modélisation numérique est satisfaisant
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lida, Takao, Naureen Mahbub Rahman, Akihiro Matsui, Hiromi Yamazawa, and Jun Moriizumi. "The Measurement of Size Distribution of Indoor Natural Radioactive Aerosols by Imaging Plate Technique." American Institite of Physics, 2008. http://hdl.handle.net/2237/12043.
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Lo, Tzu-Wei. "A new sensor concept for simultaneous measurement of pressure, temperature and thickness of plate structures using modified wave propagation theory." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2598.
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This thesis presents a multi-purpose sensor concept viable for the simultaneous
measurement of pressure, temperature and thickness of plate structures. It also
establishes the knowledge base necessary for future sensor design. Thermal-Acousto
Photonic Non-Destructive Evaluation (TAP-NDE) is employed to remotely initiate and
acquire interrogating ultrasonic waves. Parameters including pressure, temperature and
plate thickness are determined through exploring the dispersion features of the
interrogating waves. A theoretical study is performed, through which a modified wave
propagation theory applicable to homogeneous, isotropic, linear elastic materials is
formulated along with an associated numerical model. A numerical scheme for solving
the model is also developed using FEMLAB, a finite element based PDE solver. Gabor
Wavelet Transform (GWT) is employed to map numerical time waveforms into the joint
time-frequency domain. Wave time-frequency information enables dispersion curves to
be extracted and material pressure, temperature and thickness to be determined. A sensor
configuration design integrating the wave generation and sensing components of the
proven TAP-NDE technology is also developed.
Conclusions of the research are drawn from wave dispersion obtained corresponding
to the following ranges of parameters: 300-500kHz for frequency, 25-300oC for
temperature, 1-3mm for plate thickness, and 6 10 1?? - 7 1 10 ?? N/m for pressure. Each of
the three parameters considered in the study has a different level of impact on plate wave
dispersion. Plate thickness is found to have the most impact on wave dispersion,
followed by temperature of the plate. The effect attributable to pressure is the least
prominent among the three parameters considered. Plate thickness and temperature can
be readily measured while simultaneously resolved using dispersion curves. However,
pressure variation can only be differentiated when the plate is smaller than 1mm in thickness. It is observed that the thicker the plate, the faster the frequency group velocity.
Also, the group velocities of all frequency components considered are seen to increase
with increasing temperature, but decrease with increasing pressure.
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Memory, Curtis Lynn. "Numerical Simulation of Vortex Generating Jets in Zero and Adverse Pressure Gradients." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2098.pdf.
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Candanedo, Ibarra José A. "Time-mean wall static pressure distributions and module friction factors for spatially periodic fully developed flows in interrupted-plate rectangular ducts." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80002.
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An experimental study of spatially periodic fully developed flows of air in straight rectangular ducts with interrupted-plate inserts is presented. These flows have features similar to those produced in plate-fin passages of compact heat exchanger cores. The formulation of mathematical models and numerical solution methods for the prediction of these flows continues to be a challenging and largely unattained goal. The main goal of this work is to contribute experimental results suitable for testing and refining such models and solution methods. Airflows in nine different interrupted-plate rectangular ducts were considered. Reynolds numbers considered (based on Kays and London's definition of hydraulic diameter and the maximum average streamwise velocity) ranged from about 2,000 to 65,000. Time-mean static pressure distributions along the axial centreline of the top wall of the ducts, and module friction factor versus Reynolds number data, all in the spatially periodic fully developed region, were obtained.
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Claesson, Joachim. "Thermal and hydraulic performance of compact brazed plate heat exchangers operating as evaporators in domestic heat pumps." Doctoral thesis, KTH, Energiteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-110.
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This thesis investigates the performance of compact brazed plate heat exchangers (CBE) operating as evaporator in heat pump applications. The thesis, and the performances investigated, has been divided into three main sections; One zone evaporator performance; Two zone evaporator performance; and finally Local performance. The 'One zone evaporator performance' section considers the evaporator as one "black box". It was found that "approaching terminal temperatures" were obtained as low overall heat flux is employed. It was also found that the total area averaged film heat transfer coefficient was affected by changes of the brine mass flow rate. This indicates that the widespread Wilson plot method may not be used to determine flow boiling heat transfer coefficients. Further, it seems that co- and counter-current flow configuration performs equally well if the superheat is kept low. A numerical simulation of the above investigations indicates that a nucleate boiling model better predicts the performance compared to a convective evaporation model. Finally, the significant impact of the refrigerant inlet distributor design was illustrated using several CBEs with different inlet geometries but with identical heat transfer surfaces. The 'Two zone evaporator performance section' considers the evaporator as two "black boxes", i.e. the boiling and superheating boxes. Thermochromic liquid crystals (TLC) was used to determine the boiling heat transfer area. The resulting flow boiling heat transfer coefficient was found to correlate with heat flux. The superheated heat transfer area was then estimated using single phase correlations. It was observed that the TLC measurements and the predicted superheating area did not agree. Possible causes for this deviation were discussed. The most likely explanation found was the presence of mist flow at the higher vapor quality range in the boiling section of the evaporator. The 'Local Performance' section considers local pressure drop and flow boiling heat transfer. The Chisholm parameter was found not to be a constant and was found to correlate well with the kinetic energy per volume. The resulting predictions of the pressure drop were better than ± 10%. The resulting local flow boiling heat transfer coefficient, at different vapor quality, mass flux and heat flux, was compared to flow boiling correlations available in the literature. It was found that the saturated nucleate pool boiling correlation by Cooper (1984) and narrow channel flow boiling correlations (Tran 1999, Lazarek and Black 1982) predicted the experimental data better than several traditional flow boiling correlations, developed for larger tubes.QC 20100524
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Bouainouche, Mokrane. "Etude de l'interaction entre un jet plan à grande vitesse et un film liquide." valenciennes, 1995. https://ged.uphf.fr/nuxeo/site/esupversions/2f38b9a7-3e25-4c6f-968e-e4d2d3c14d4a.
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La première partie de l'étude s'intéresse à la modélisation de l'impact d'un jet de gaz plan et mince sur une paroi plane en vue d'en déduire les distributions de pression et de contrainte de cisaillement sur la paroi. Dans la deuxième partie, ces résultats sont utilisés pour étudier le comportement d'un film liquide visqueux entraîné par le déplacement vertical d'une bande et soumis à l'action d'un jet. Les actions du jet sur la surface sont déterminées par un calcul numérique en utilisant un schéma de type volume fini. L’écoulement d'un jet bidimensionnel, turbulent et compressible sur une plaque plane est modélisé en utilisant le modèle de turbulence k- avec des fonctions de paroi. Pour réduire l'influence du maillage près de la paroi sur le calcul de la contrainte de cisaillement pariétale, une loi de paroi hybride est proposée en utilisant simultanément la loi de paroi logarithmique et sa forme généralisée. Les distributions de pression et de contrainte de cisaillement sont calculées et validées par des mesures expérimentales. L’équation du mouvement du film liquide est écrite en considérant le terme d'accélération, négligé dans les études précédentes. Le modèle est appliqué a un processus de galvanisation et validé par des résultats expérimentaux obtenus dans des conditions diversesThe first part of this study deals with the modelling of the impact of a thin plane gas jet a flat plate in order to define the pressure and shear stress distributions on the wall. In the second part, these results are used to study the behavior of viscous film liquid on the strip moving upward and submitted to the jet action. The jet actions are determined by a numerical computation based on finite volume scheme. The impingement of a plane two dimensional turbulent and compressible jet is modelised using the k-ɛ model combined to the wall functions. In order to reduce the near wall gnd influence on the shear stress calculation, a hybrid wall law is proposed resulting from simultaneous use of the logarithmic law and generalized one. Pressure and shear stress distributions on the flat plane are calculated and validated by experimental data. The motion of liquid coating is modelised by taking into account the inertia terms, neglected in the previous studies. This model is applied to the galvanization process and compared with measurements obtained in various conditions
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Moravcová, Eva. "Projekt bytového domu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225375.
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This is a residential house in Brno. The supporting structure is reinforced concrete. The building has one basement and six floors. Vertical load-bearing structures are made up of reinforced concrete columns and walls. Horizontal load-bearing structures are formed by slabs (bearing in both directions). The staircase is concrete slab. Foundation is on piles. Infill vertical structures are brick. In the fifth floor pool is located.
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Koryčanský, Roman. "Ventilace tlakové obálky reaktoru GFR." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231459.
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This paper describes the design of the ventilation pressure cover of the demonstrator GFR. The first part is a brief research project GFR and the effects of temperature on the inside structures. In the following part is calculated balance heat losses within the pressure cover for three cases: non-insulated, fully-insulated and partially insulated surface of the reactor. The following is a design of a heat sink for partially insulated surface.
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Ruggiero, Eric John. "Modeling and Control of SPIDER Satellite Components." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28489.
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Space satellite technology is heading in the direction of ultra-large, lightweight structures deployable on orbit. Minimal structural mass translates into minimal launch costs, while increased satellite bus size translates into significant bandwidth improvement for both radar and optical applications. However, from a structural standpoint, these two goals are in direct conflict with one another, as large, flexible structures possess terrible dynamic properties and minimal effective bandwidth. Since the next level of research will require active dynamic analysis, vibration control, and shape morphing control of these satellites, a better-suited name for this technology is Super Precise Intelligent Deployables for Engineered Reconnaissance, or SPIDER. Unlike wisps of cobweb caught in the wind, SPIDER technology will dictate the functionality and versatility of the satellite much like an arachnid weaving its own web.
In the present work, a rigorous mathematical framework based on distributed parameter system theory is presented in describing the dynamics of augmented membranous structures. In particular, Euler-Bernoulli beam theory and thin plate theory are used to describe the integration of piezoelectric material with membranes. In both the one and two dimensional problems, experimental validation is provided to support the developed models. Next, the linear quadratic regulator (LQR) control problem is defined from a distributed parameter systems approach, and from this formulation, the functional gains of the respective system are gleaned. The functional gains provide an intelligent mapping when designing an observer-based control system as they pinpoint important sensory information (both type and spatial location) within the structure.
Further, an experimental investigation into the dynamics of membranes stretched over shallow, air-filled cavities is presented. The presence of the air-filled cavity in close proximity to the membrane creates a distributed spring and damping effect, thus creating desirable system dynamics from an optical or radar application perspective. Finally, in conjunction with the use of a pressurized cavity with a membrane optic, a novel basis is presented for describing incoming wavefront aberrations. The new basis, coined the clamped Zernike polynomials, provides a mapping for distributed spatial actuation of a membrane mirror that is amiable to the clamped boundary conditions of the mechanical lens. Consequently, based on the work presented here and being carried out in cooperation with the Air Force Research Laboratory Directed Energy Directorate (AFRL / DE), it is envisioned that a 1 m adaptive membrane optic is on the verge of becoming a reality.Ph. D.
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Zuanetti, Bryan. "Plate Impact Experiments for Studying the Dynamic Response of Commercial-Purity Aluminum at Temperatures Approaching Melt." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1557132337419911.
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Langarkhorshid, Alimuhammad Rezaeipour. "A study of heat transfer, pressure drop and residence time distribution for two-phase, two component flow in a plate and frame heat exchanger." Thesis, University of East London, 1985. http://roar.uel.ac.uk/1228/.
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This thesis presents a literature review and the results of the present investigation for the upward flow of mixtures of air and water, water or air only in the channel of two Alfa-Laval plate heat exchangers. The flow patterns and their areas in the channel were identified photographically and visually. For both single-phase and two-phase flow, the embossed section of the channel was occupied by the slow and fast zones of flow. The ratio of the areas of these zones varied from nearly one to negligibly small as the flow rate of the phase(s) was increased gradually. These data were correlated empirically with the flow variables of the phase(s). High speed photography was used to analyse mixing in the channel as well as each cell formed by the herringbone patterns of the plates. The data on the flow patterns were used to develop a mathematical model of mixing in the channel to predict the exit concentration profiles of the phase(s). The residence time distribution of the phase(s) predicted by the present model compared very well with the experimental data for both singlephase and two-phase flow of the phases. However, the fit between the experimental and predicted exit concentrations was exceptionally good at high flow rates of the phase(s). The fractional volume of air occupied in the mixture of two-phase flow derived from the mean residence time of twophase flow were correlated empirically with dimensionless groups. The mixing parameters of the gamma distribution model were also correlated with the single-phase and two-phase flow dimensionless groups. The mean heat transfer film coefficients of water (hsL) and mixtures of air and water (htp) for the clean plates were correlated empirically. A Nusselt type equation was used to correlate the mean heat transfer film coefficients for water. The ratio (htp/hsL) was also correlated empirically against single-phase and two-phase dimensionless groups by two correlations which suggest the presence of two widely different flow patterns and mixing characteristics in the channel. Within the range of the variables investigated the values of htp increased by 53 to 340 percent over those for hsL. The pressure drop data for both metal and perspex plate heat exchangers were analysed with the Fanning friction factor (fr) v. Reynolds Number of water or air type of relationships. For air and water two different curves were obtained for the fr: Re relationships. For the analysis of the two-phase pressure data, an empirical approach incorporating the use of the dimensionless groups viz. the ratio of the liquid to gas superficial Reynolds Numbers and the Lockhart & Martinelli parameter (XLM) was found to correlate the twophase friction factor data extremely well. Finally, the pressure drop data were correlated equally well by a Lockhart & Martinelli (12) plot similar to that presented for the tubes.
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Sharef, Hajan, and Marek Potari. "Koncept på ett hydrauliskt mothåll." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12141.
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New technology in the automotive industry is the key to success. Therefore, it is appreciated when people come with new design ways to solve problems. This leads to innovation in the automotive industry that will lead to better and more environmentally friendly cars. This report presents a concept on a pushing counter lever spring which provides the same characteristics of force curve as a diaphragm spring in a pressure plate of a car has. The mechanism is to be used for long-term testing and evaluating clutch pedals. The work describes the development process and the manufacture of a prototype. The program Creo (CAD / 3D) is largely used to construct the components. As are the subprograms Mechanism Design and Simulate to simulate the movement and loads. Excel is a great help at the theoretical calculation of the mechanism and to evaluate the theory behind the concept. The result shows how to simulate a diaphragm spring in the pressure plate in a car for long-term testing of clutch pedals. The goal is to accurately mimic the force curve of a diaphragm spring, in order to design better pedals, and thus reduce the weight on the pedals to in turn reduce fuel consumption to protect the environment is one of the most important factors of all in the automotive industry.
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Naik, Pratin J., Ganesh K. Seeniraj, and Ram S. Chandran. "A study into forces and moments acting on the swash plate of an axial piston pump using a novel approach to reduce pressure and flow pulsations." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71105.
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In hydraulic pumps, typically in axial piston pumps, reduction of pressure and flow ripples was attempted by providing relief grooves and pre-compression for noise reduction. Pre-compression is normally achieved by using the dead space between pump ports in the valve plate. Also valve plate profile modification is required, if system operating conditions such as pump output pressure and flowrate change, to maintain optimum operating conditions for reduced pressure/flow ripple. An earlier simulation study confirmed effectiveness of varying dead centre position to reduce pressure and flow ripples. A specifically designed mechanism, outlined in the earlier work, achieves this goal by varying the dead centre position of the pump swash plate. This study reports on the findings of the effect of varying dead centre position and groove configurations on forces and moments acting on the swash plate for various operating conditions. The simulation model cited in the earlier work was used in this study. This information is vital for the design of an actuating mechanism to vary dead centre position of a pump valve plate. These simulations were run using MATLAB/Simulink and S-functions. Results of this study are promising.
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Vlček, Josef. "Vliv turbulentního modelu na simulace proudění vzduchu v okolí průtokoměru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220887.
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Purpose of this thesis is to check influence of turbulent model used for simulation of flow close to primary elementi inserted into piping. The goal is to check if results computed by these models are equal and how precise is their prediction.
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Carlsson, Matthias. "Development and Characterization of Parallel-Plate Avalanche Counters for Nuclear Physics Experiments." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354818.
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Parallel-plate avalanche counters, PPACs, are commonly used to detect fission fragments. The PPAC detects them and mark (very accurately) the time of detection. Such measurements can be used to measure the neutron energy (via time-of-flight) to study neutron-induced fission.This project report provides a method that, together with the discussed improvements, allows the fabrication of good quality PPAC detectors. Several PPACs are manufactured and the electrodes are built from 0.9 µm thick mylar foils which are evaporated with a 40-80 nm thin layer of aluminum.The developed PPACs are characterized with well known radioactive Cf and Am sources (the source characterization also found in this report), and compared against each other. Additionally, the PPAC signal amplitude spectrum are found to follow theoretical expectations with regards to angular dependence, gas pressure and an applied electrode voltage.At a specific applied electrode voltage and range of gas pressures (3-9 mbar), the measured time resolutions are 2.24-1.38 ns. A trend is observed for finer time resolutions at higher gas pressures.Parallel-plate avalanche counters, PPACs, används ofta för att detektera fissionsfragment. PPAC:en detekterar fragmenten med väldigt god tidsupplösning och således kan PPAC detektorer användas till att mäta neutron energier (mha. flygtidsmetoden), vilka uppmätts för att studera neutroninducerad fission.Det här projektet och den här rapporten beskriver en metod, med föreslagna förbättringar, som möjliggör tillverkning av PPAC detektorer av bra kvalitet. Under projektet har flera PPACs byggts med elektroder gjorda av 0.9 µm tunn mylar förångade med 40-80 nm aluminium. De tillverkade PPAC detektorerna är karaktäriserade med väl kända radioaktiva Cf- och Am-källor (dessa karaktäriseras även i den här rapporten). Detektorerna är sedan jämförda mot varandra och är funna att följa teoretiska förväntningar med avseende på vinkel-, gastryck- och pålagd elektrodspänningsberoende.Resultaten av projektet, som besvarar flera tidigare frågeställningar och bekräftar vissa antaganden, flyttar utsikten och förståelsen framåt för hur PPACs fungerar och vad forskarna kan uppnå med dem.
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Šimberský, Michal. "Simulace proudění vzduchu a stanovení trvalé tlakové ztráty pro normalizovanou clonu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220891.
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This master’s thesis deals with the simulation of flow through the normalized orifice plate. There is described flow measurement with flowmeters, which reduces the cross-section of the pipe and causes the pressure difference before and after the flowmeter. Following is a description methods of modeling of turbulent flow and a description of software for the simulation of flow from the company Ansys. The theoretical part is followed a practical part, which is focused on determining the permanent pressure loss caused by the orifice plate and the verification of straight pipeline lengths between orifice and obstacle.
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Johnson, Johanna. "Aspects of Flexographic Print Quality and Relationship to some Printing Parameters." Doctoral thesis, Karlstad : Faculty of Technology and Science, Chemical Engineering, Karlstads universitet, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1793.
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Endre, Robert. "Brottsskeden kring infästning av stålpelare." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-11957.
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En utfackningsvägg är en icke bärande väggkonstruktion, ofta av trä som har för syfte att minimera energiförbrukningen för byggnader i betong. Inuti konstruktionen används ibland stålpelare för att bära ovanliggande konstruktioner. Stålpelarna utsätts för laster som de måste dimensioneras för. Över och under pelarna svetsas plåtar fast för att öka den belastade arean och hindra brott i betongen. I detta examensarbete har därför en datormodell i programmet Excel framtagits. Modellen dimensionerar kantpelare i stål enligt Eurokoderna. De brottsfall som ingår i modellen är genomstansning, prägling, spjälkning, avstånd till betongkant, reducering vid håltagning i betong, tryckkraftskapacitet för fot respektive topplåtarna och böjmoment för plåtarna. Genomstansning är ett koniskt sprött brott som sker i betongen, det spröda brottet sker direkt utan förvarning och betongplattas bärförmåga sjunker snabbt vilket kan leda till ras. Prägling är en lokal krossning av betongen och spjälkningen innebär att på grund av tryckkraften så uppstår en horisontell dragkraft i betongen vilket kan leda till brott. Då det är svårt att uppfatta i Eurokoderna för hur avståndet mellan plåtarna och betongkanten påverkar hållfastheten har därför en beräkningsmetod framställts, likvärdigt gäller för påverkan av håltagning nära en pelare. Exempel på hål kan vara trappor, hissar eller håltagning för värmestammar till radiatorer. Plåtarna beräknas i tvärsnittsklass tre. Modellen är uppbygg så att olika dimensioner och kvalitéer väljs, hållfastheten för konstruktionen beräknas och sedan redovisa om lasten klaras eller inte. I och med det så kan till exempel olika dimensioner och kvalitéer testas fram för att få en så optimal konstruktionslösning som möjligt. Avgränsningar har gjorts. Modellen beräknar bara de olika brottsfall som ovan nämns och berör endast kvadratiska VKR- profiler och plåtar. Pelare har beräknats som ledat infäst i båda upplagen där endast tryckkrafter dimensionerat betongen och plåtarna. Under det första skedet av arbetet så har fakta inhämtning för det olika brottsfallen gjort. Fakta har hämtats från litteratur, rapporter, undersökningar, forskningar, tidigare lösningar, diskussion med branscherfarna och tidigare respektive nyare regelverk. Därefter har datormodellen gjorts, målet med modellen är att få ett snabbt resultat och en komplett redovisning. Därför är modellen uppbygg så att varje brottsfall har en egen flik och kan redovisas enskilt. För att modellen ska kunna användas av utomstående har standardbeteckningar, bilder och kommentarer använts. Modellen har kontrollerats med diverse beräkningsexempel och program för att få ett trovärdigt/användbart resultat. Slutsats: En väl fungerande modell har tagits fram och som kan användas av utomstående byggnadsingenjörer med minst gymnasieingenjörsutbildning.A infill wall is a non-bearing wall construction, often is made af wood, which has the aim of minimizing the energy consumption of buildings in concrete. The inside the construction is sometimes steel designed for supporting the overlyingstructures. Steel studs are subjected to loads that they must be dimensioned to support. Above and below the colums plates are welded to increase the loaded area and prevent damages to the concrete. In this thesis a computer program in Excel has been created, the program dimensions border pillars in steel that follows the Eurocodes. Included in the program is punching, local pressure, splitting, distance to concrete, reduction when drilling in concrete, compression load capacity of foot and top plates, and bending torque the plates. Punching is a conical damage that occurs in the concrete, the damage occurs without warning and the concrete’s bearing capacity decreases rapidly which can lead to collapse. Local pressure is a local damage of the concrete and splitting, meaning that because of the pressure force arising can lead to a horizontal thrust in the concrete, which can lead to injuries. Since it is difficult to perceive the distance between the plates and the concrete edge of structural strength in the Eurocodes a calculation method has been made, equally applies to the consequences when drilling near a pillar. Examples of holes can be stairs, elevators or holes for heat strain for radiators. The plates are calculated in cross-section class three. The program is built so that different dimensions and qualities is selected, then the program calculates the strength of the structure and reports if will support the load. Different dimensions and qualities can be tested to get the optimal structure sollution. Limits have been set, the program only calculates the various injuries mentioned above and applies only to square VKR-sections and plates. Pillar has been calculated as articulated in both secured repository where the only pressure forces dimensioned concrete and plates. During the first phase of the work, gathering facts for the various types of damages has been done. Facts have been gathered from literature, reports, studies, researches, previous solutions, discussions with industry experienced and previous and more recent regulations. Since then, the computer program has been made, the goal of the program is to get a quick result and a complete report. Therefore, the program is made so that all damages is on different tabs and can be reported separately. So that the program can used by third parties standard names, images and comments are used. The program has been checked with various calculation examples and applications to achieve a credible / useful result. Conclusion: A well-functioning model has been developed and can be used by structural engineers with a education at least of technical college.
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Torres, Lorena Chagas. "O conceito de equilíbrio hidráulico e termodinâmico da água no solo aplicado ao estudo da curva de retenção e murchamento de plantas." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-04052016-095719/.
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Estimativas sobre alterações climáticas globais têm aumentando a demanda por estudos sobre propriedades dos solos relativamente secos e limitações impostas à absorção de água pelas plantas em condições de escassez hídrica. Neste estudo, fatores que influenciam a retenção da água no solo e o murchamento de plantas foram avaliados com base no conceito de equilíbrio da água no solo. Objetivou-se com este estudo: (i) avaliar a confiabilidade de medições do conteúdo de água no solo sob altas sucções matriciais em câmaras de pressão, usando como referência a técnica de ponto de orvalho (ii) avaliar as interações entre espécies de plantas e solos com diferentes classes texturais no ponto de murcha permanente (iii) investigar as relações entre equilíbrio hidráulico da água no solo e murchamento de plantas a partir do conceito de corte hidráulico. Para tanto, um experimento para avaliar a influência dos tipos de solos e espécies de plantas, no ponto de murcha permanente foi conduzido em casa de vegetação da Escola Superior de Agricultura \"Luiz de Queiroz\" da Universidade de São Paulo, Piracicaba, São Paulo. Avaliou-se o murchamento de plantas de girassol (Helianthus annuus L.), milho (Zea mays L.) e soja (Glycine max L.). Os solos utilizados no estudo foram coletados na camada superficial (0-10 cm) em quatro áreas, selecionadas com o objetivo de obter classes texturais contrastantes, localizadas no município de Piracicaba, São Paulo, Brasil. Sub-amostras foram utilizadas para determinação da distribuição do tamanho de partículas e atributos químicos. Amostras indeformadas foram coletadas para a determinação da curva de retenção da água no solo pela técnica de câmaras de pressão. Adicionalmente, amostras deformadas foram utilizadas para determinação das características de retenção da água no solo pela técnica do ponto de orvalho em altos valores de sucções matriciais. Os dados de retenção de água no solo foram ajustados a modelos empíricos para estimativas da sucção matricial e conteúdo de água relacionada à água em equilíbrio hidráulico (água residual). Foram observadas similaridades nas determinações das características de retenção da água no solo entre as técnicas de câmaras de pressão e ponto de orvalho, sugerindo a boa drenagem das amostras de solo em câmaras de pressão. Interações significativas foram observadas entre os tipos de solos e espécies de plantas no ponto de murcha permanente, indicando que o movimento de água no contínuo solo-planta-atmosfera foi dependente de resistências relacionadas tanto ao solo quanto às plantas. Ou seja, tanto à capacidade do solo em transportar água até raízes, quanto à habilidade das plantas em absorver a água transportada, assim como, aos processos de regulação de água que ocorrem nas plantas. A abordagem baseada no conteúdo de água residual para o intervalo de sucções matriciais de 0 a 15.000 hPa não foi adequada para ilustrar a condição de equilíbrio hidráulico da água no solo, definidos pelo corte hidráulico, e relações com as sucções matriciais em ocorre o murchamento de plantas.Estimates about climate changes have increased the demand for studies of the properties of relatively dry soil and limitations on the plants water uptake in conditions of water scarcity. In this study, factors influencing the soil water retention and wilting plants were evaluated based on the concept of soil water equilibrium. The objectives of this study were: (i) to evaluate the reliability measurements of the soil water retention on pressure plate apparatus at high matric suctions using as reference the dew point meter (ii) to evaluate the interactions between soil types and plant species at permanent wilting point (iii) investigate the relationship between the hydraulic equilibrium of soil water and the plant wilting based on the hydraulic cut-off concept. A pot experiment to evaluate the effect of plant and soil types at permanent wilting point was carried out in a greenhouse at the Agricultural\'s College \"Luiz de Queiroz\" from University of São Paulo in Piracicaba, São Paulo, Brazil. Soil samples were collected at the topsoil (0-10 cm) from four different locations around the city of Piracicaba, São Paulo, Brazil. Subsamples were taken to determine the particle size distribution and chemical analysis. To determine soil water retention curve 30 soil samples were collected with undisturbed soil cores. The soils were selected to have a range of texture and organic carbon content. The wilting was evaluated using plants of sunflower (Helianthus annuus L.), maize (Zea mays L.) and soybean (Glycine max L.). The soil water retention data were fitted to the empirical models for estimating the matric suction and water content related soil water at hydraulic equilibrium (residual water content). Similar soil water content were observed for measurements at pressure plate apparatus and dew point meter, suggesting good drainage of the soil samples in pressure plate apparatus for the dry range of soil water retention curve. Significant interactions were observed between soil types and plant species at permanent wilting point, indicating that the water movement in the soil-plant-atmosphere continuum was dependent of resistances related to soil and the plants properties. The approach based on the residual water content for the matric suctions from 0 to 15,000 hPa was not adequate to illustrate the hydraulic equilibrium of the soil water defined by the cut-hydraulic and relations with the matric suction at wilting plants.
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Björk, Erik. "Energy Efficiency Improvements in Household Refrigeration Cooling Systems." Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93061.
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This thesis is based on eight articles all related to the characteristics of the cooling system and plate evaporator of a household refrigerator. Through these articles, knowledge is provided that can be used to increase the operational efficiency in household refrigeration. Papers A, B and C focus on heat transfer and pressure drop in a commonly used free convection evaporator – the plate evaporator. Applicable correlations are suggested on how to estimate the air side heat transfer, the refrigerant side pressure drop and the refrigerant side heat transfer. Papers D, E and F hold a unique experimental study of the refrigerant charge distribution in the cooling system at transient and steady state conditions. From this cyclic losses are identified and estimated and ways to overcome them are suggested. In paper G the topic “charging and throttling” is investigated in an unparalleled experimental study based on more than 600 data points at different quantities of charge and expansions device capacities. It results in recommendations on how to optimize the capillary tube length and the quantity of refrigerant charge. Finally, Paper H holds a thermographic study of the overall cooling system operating at transient conditions. Overall, a potential to lower the energy use by as much as 25 % was identified in the refrigerator studied. About 10 % was found on the evaporator’s air side. 1-2 % was identified as losses related to the edge effect of the evaporator plate. About 8 % was estimated to be cyclic losses. About 5 % was found in cycle length optimization. It is believed that most of these findings are of general interest for the whole field of household refrigeration even though the results come from one type of refrigerator. Suggestions of simple means to reduce the losses without increasing the unit price are provided within the thesisQC 20120411
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Cuarelli, Gilberto. "Mise en œuvre des nouvelles technologies pour l'évaluation du contrôle postural et de l’analyse de la marche." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI084/document.
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Certains besoins de santé spécifiques ont contribué au développement du travail présenté ici, en particulier dans le domaine de la kinésithérapie dans lequel l’étude de l’équilibre postural est étudiée. Les solutions qui existent aujourd'hui sur le marché sont coûteuses, disponibles uniquement dans les grands hôpitaux ou dans des salles dédiées, avec un faible taux de fréquentation de la population, principalement dans des endroits plus éloignés des grands centres urbains. Ce travail a été développé en collaboration avec une équipe constituée de kinésithérapeutes, de chercheurs en génie électrique et en génie mécanique du laboratoire G-SCOP, Grenoble INP, Institut d’Ingénierie, Univ. Grenoble Alpes, France. Cette équipe cherche des solutions à faible coût qui répondent aux besoins de la société en général, en mettant l'accent sur la santé, mais également sur la vulgarisation scientifique, en diffusant ses travaux lors de manifestations de type fête de la Sciences dans la région et pour la communauté. Les travaux ont débuté avec une plateforme de force développée en 2016, conjointement par des chercheurs de l'UNESP (une Université de l'état Sao Paulo au Brésil) et du laboratoire G-SCOP. A cette solution a été ajoutée une nouvelle interface électronique, développée dans le but de fournir des informations sur le déplacement du centre de pression du patient. Un mécanisme a également été mis en place pour assurer la synchronisation entre les informations capturées par les capteurs installés sur la plate-forme et un capteur Microsoft Kinect. De nouveaux outils logiciels ont été proposés pour capturer et analyser les résultats. Le traitement des données permet de créer un modèle tridimensionnel détaillé contenant la cinématique de plusieurs articulations du corps humain et leur comportement respectif en fonction du temps. La mise en œuvre du capteur Kinect synchronisé avec la plate-forme de force permet de comparer le Centre de Pression avec le Centre de masse en vue de proposer un outil plus léger et moins cher à la communauté des praticiens hospitaliersSome specific health needs contributed to the development of the work presented here, especially in Physical Therapy in which the Postural Equilibrium is studied. The solutions that exist today in the market are of expensive, available only in large hospitals or in dedicated rooms, with low index of attendance to the population, mainly in places more distant of the great urban centers. This work was developed in cooperation with a team constituted of Phisiotherpists, Electrical Engineering and Mechanical Engineering from of the G-SCOP Laboratory, Grenoble INP, Institute of Engineering Univ. Grenoble Alpes, France. This team seeks low cost solutions that meet the needs of society in general, with a focus on health, but also with a focus on the popularization of science, disseminating its work in basic schools in the region and also in the community. The work began with a strength platform developed in 2016, jointly by researchers from UNESP, Sao Paulo, Brasil, and the G-SCOP Laboratory. To this solution was added a new electronic interface, developed with the purpose of providing information on the displacement of the patient pressure center. A mechanism was also implemented to ensure synchronization between information captured by sensors installed on the platform and a Microsoft Kinect sensor. New software tools were developed to capture and analyze the results. The data treatment allows the creation of a detailed three-dimensional model, containing the kinematics of several joints of the human body and their respective positional behavior, as a function of time. With the implementation of the Kinect sensor, synchronised with the force platform, it is also possible to evaluate the kinematic and positional biomechanical parameters
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Píška, Jakub. "Dignostika zhášecího pochodu u stejnosměrného stykače." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413235.
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Cílem této diplomové práce bylo provést diagnostiku vysokonapěťového stejnosměrného stykače se zaměřením na zpětnou komutaci a lepení oblouku, navrhnout a ověřit úpravy, které odstraní tyto negativní jevy. Měření obloukového napětí, tlaku a pomocí rychlokamery byly použity při diagnostice těchto jevů. Změny na arcrunnerech a jhu magnetického obvodu byly využity při jejich odstraňování. Úpravy na arcrunneru zmenšily skokové nárusty délky oblouku a úpravy na jhu navýšily sílu na oblouk mezi rozevírajícími se kontakty. Navrhnuté změny na stykači snížily časovou ztrátu v důsledku zpětné komutace, a tak zkrátily čas přenosu oblouku.
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Saunders, Nathan William. "Efficacy of a 6-week Neuromuscular Training Program for Improving Postural Control in Figure Skaters." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1305044478.
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Lundberg, Lennart. "Blood-membrane interaction and treatment of haemodialysis patients : a study of various factors." Doctoral thesis, Umeå universitet, Medicin, 1994. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-101310.
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Henke, Douglas J. (Douglas John). "Elastic-plastic hull plate response to slamming induced pressures." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/39969.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1992 and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.Includes bibliographical references (leaves 76-78).
by Douglas J. Henke.
M.S.
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Sjöholm, Henrik. "Pressure Effects in Orifice Cavitation Modeling." Thesis, Umeå universitet, Institutionen för fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-176885.
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In this thesis computational models for cavitating flows around orifice plates has been studied and compared. The goal was to fit a model with experimental data and this was done with some success, although problems with numerical stability, long calculation times and geometry overfitting remain. Cavitation is a complex fluid phenomenon that can occur in pressurized liquid flows. It starts when the liquid pressure is lowered below the boiling pressure and water that undergoes cavitation forms vapor which later implodes violently. This process can cause problems such as noise, vibrations and corrosion in piping systems. Loud noise is a nuisance, however powerful vibrations and corrosion can have serious consequences for the structural integrity of pipes. The for example lessened performance, leakages or even failure. Therefore the minimization of cavitation is often a goal in orifice and piping design. Vattenfall AB, together with Forsmark and Ringhals nuclear plants have studied cavitating flows around orifice plates used for flow limitation. A set of data from laboratory tests made by Vattenfall was used as the basis of analysis. Existing computational models in OpenFOAM were tested and evaluated based on their ability to model the experimental data accurately, as well as their computational performance and stability. The cavitation phenomenon was difficult to simulate using established methods so a new method was created and verified. It is based on the Kunz cavitation model together with Large Eddy Simulations, but with turbulence as a predictor of cavitation. The new computational model will serve as a tool for knowing how to design orifices in the future, so that laboratory experiments will not have to be conducted for each new piping design.
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Franceschelli, Luca. "Cooling Performance Analysis and Design of an Instrumented Radiator in a MotoGP Wind Tunnel Model." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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The present thesis work was developed in collaboration with the Ducati Corse Aerodynamic Department. It is focused on the measurement system employed on the MotoGP Wind Tunnel model in order to evaluate the cooling performances at the radiators.
As first, an analysis of the current methodology is conducted. Based on the arrangement of hybrid-Kiel probes behind the radiators, it was observed that an improvement in the calibration procedure is required in order to account for inter-probe and support frame interference. Furthermore, a correlation process with the CFD simulation was carried out. A good agreement in trend with CFD results was displayed, despite a low accuracy. The need for higher spatial resolution was stated.
In order to update the CFD implementation of the actual water radiator, the latter has been characterized in terms of pressure drop on a dedicate radiator test bench, provided by Dallara Automobili. A suitable convergent frame has been designed for the purpose.
Finally, a new methodology for cooling performance evaluation was developed and calibrated. The method exploits a set of static and Kiel probes in a dummy radiator core. An honeycomb structure and a perforated plate are implemented to reproduce the real radiator behaviour.
Experiments have been performed with half-radiator equipped with the new set up and the other half instrumented with Pitot tubes, showing good agreement between the two probe-types.
A set of plates have been characterized. It allowed also to highlight the relevance of the solid part distribution - and related holes' diameter - on the pressure drop and the effect on the measured pressures from the probes.
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Kovalíková, Mária. "Statické zajištění kostela v Ludslavicích." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227609.
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This thesis is drafting static protection church horizontal pretension, especially at the level of foundations and walls. Furthermore, the design of a new increase the stiffness of reinforced concrete towers and other prestress. The role was also producing construction drawings for the design of static security.
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Mutter, Nathan J. "Stress concentration factors for v-notched plates under axisymmetric pressure." Honors in the Major Thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1461.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Engineering and Computer Science
Mechanical Engineering
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Underwood, Nicholas. "Pulse pressure testing and analysis of steel plates with openings." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/15273/.
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Steel plates are widely used in a variety of civil engineering applications for load bearing structural components, due to their favourable strength to weight ratio. Many of these plates have openings that are commonly used for reducing weight, access for utilities or for inspection in shipping and offshore installations. However the influence of these openings to the structural component’s robustness and resilience against blast loading is relatively unknown, with limited research conducted in this subject to date. Due to the high costs associated with offshore facilities they are typically very congested. This coupled with the producing, processing, storing and transporting of hydrocarbon materials means that explosions and subsequent fires are major hazards with severe consequences. In the event of an explosion, the blast load will initially impact the secondary structure (large spanning plated sections) and then transfer through to the primary structure, highlighting their critical consideration in safety assessments. Plated structures are also known to cause confinement, which in turn will results in higher overpressures, making the consequences of an event more severe. The aim of this research was to investigate the combined influence that openings have on the overpressure and the structural response of thin ductile plates subjected to extreme dynamic transverse loads. This was achieved by conducting a set of well-defined experiments investigating the response of 1/8 scale (0.5 m square) mild steel plates with openings subjected to pulse pressure loading. Six central (scaled) openings were considered; circular (50, 75 and 100 mm) and extended circular (50 by 75, 75 by 100 and 100 by 125 mm) representative of typical offshore and shipping applications. Each plate design was assessed with two boundary conditions (restrained and non-restrained) and two nominal loading conditions. The boundary conditions adopted in this study allowed the response to be bounded, and enabled them to be practicably modelled in FEA-analyses and in the simplified analytical approaches. A pulse pressure test facility was used to generate nominal pulse pressure loads (25 and 50 psi) applied over a time (100 to 200+ ms load duration) representative of extreme explosion loading conditions offshore. All plates exhibited a mode I type failure (large inelastic deformation) highlighting the large reserve strength in such members. The work has shown that the inclusion of an opening (<5% of the exposed panel area) does not significantly degrade the structural resistance when damage is restricted to large inelastic deformation. The reduction in stiffness due to the hole is compensated by the reduced area to which the load is applied. The data generated in the laboratory tests was used to develop and validate finite element models. In general, excellent correlation was observed between the experimental failure modes and the permanent displacements, within an average difference of 12% and 15% for the restrained and non-restrained plates respectively. The finite element models also provided a useful insight into the various failure processes and transient behaviour which could not be observed experimentally. A simplified analytical model was developed to predict the response of the plates and was validated against the experimental data. The results for the permanent displacements compared favourably with the restrained plates at the two nominal pressures (6.5% at 25 psi and 7% at 50 psi), but correlated less well with the non- restrained ones (10% at 25 psi and 3% at 50 psi). Correct definition of support conditions along with a detailed description of the development of plasticity, as shown in the finite element models was fundamental in accurately predicting response of the non-restrained plates. The simplified techniques developed are cost effective compared with more sophisticated finite element methods making them suitable for preliminary engineering design studies. Ultimately this study provides evidence to suggest that small (circular or extended circular) openings positioned away from areas of high stress, could be used as a passive system to mitigate the influences of an explosion event offshore. This has many benefits in the form of reducing weight, reducing confinement (thus lowering overpressures) and reducing the loading applied to these members, and subsequently reducing the loading transferred through to the primary structure.
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Chen, Zi Qi. "Delamination buckling of pressure-loaded laminated cylindrical shells and panels." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/21227.
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Marques, Alfredo Manuel Nobre. "Modelação e avaliação do desempenho de permutadores de calor." Master's thesis, Universidade de Évora, 2009. http://hdl.handle.net/10174/20930.
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O estudo de permutadores de calor baseado em modelos é um tipo de abordagem que, nas últimas décadas, tem merecido particular atenção, tanto pelos investigadores como em desenvolvimento de aplicações práticas, já que estes equipamentos são equipamentos imprescindíveis no funcionamento da generalidade das indústrias, sistemas de energia (centrais termoeléctricas, refinarias, etc.), sistemas de climatização e sistemas de propulsão terrestre, aeronáutica e marítima. Em instalações de máquinas marítimas, os permutadores de calor são determinantes para o bom funcionamento do navio, pois são utilizados tanto na instalação propulsora como em vários sistemas auxiliares. Nos últimos anos, por motivos de eficiência e de espaço ocupado, tem-se assistido à substituição de permutadores de calor do tipo corpo cilíndrico e feixe tubular por permutadores de calor de placas. O presente trabalho centrou-se no estudo de permutadores de calor de placas, tendo como objectivo fundamental contribuir para o desenvolvimento do estado da arte neste domínio do conhecimento, através do ensaio e modelação de permutadores de calor de placas com corrugações do tipo "chevron". Desenvolveu-se em quatro fases. A primeira fase consistiu na obtenção de valores experimentais relativos a um permutador de calor de placas e a um permutador de corpo cilíndrico e feixe tubular, integrados numa bancada de ensaio de permutadores de calor, existente nos laboratórios da ENIDH (Escola Superior Náutica Infante D. Henrique). Para idênticas condições de funcionamento compararam-se valores experimentais, tendo-se assim verificado as razões que motivaram a substituição anteriormente referida. Ainda nesta fase efectuou se a análise da incerteza experimental, bem como a avaliação das grandezas que mais contribuem para essa incerteza. A segunda fase consistiu na modelação analítica do permutador de calor de placas, através da utilização de correlações existentes na bibliografia. Uma vez que os resultados obtidos não foram satisfatórios, estabeleceram-se novas correlações através das quais se desenvolveu um modelo cujos resultados mostraram uma boa concordância com os resultados experimentais. Para condições próximas da potência máxima, foi determinada a sensibilidade do modelo desenvolvido relativamente a variações possíveis de se verificar em instalações de máquinas marítimas. A terceira fase consistiu na simulação numérica tridimensional do permutador de calor de placas, utilizando um código comercial CFD, através da qual se analisou a influência das corrugações, das condições de fronteira e dos topos das placas no comportamento do permutador de calor de placas. Apesar de serem de aplicação trabalhosa e de processamento lento, as simulações numéricas conduziram a resultados satisfatórios, do ponto de vista de engenharia, e abrem caminho para a modelação de outras geometrias de permutadores de calor. A quarta fase consistiu na análise do comportamento do permutador de calor de placas quando os fluidos envolvidos fossem, para além da água doce, a água do mar e o óleo lubrificante (típicos de instalações de máquinas marítimas. Esta análise foi efectuada através do modelo analítico, baseado nas novas correlações desenvolvidas. - ABSTRACT: The study of heat exchangers based on models is an approach that has received major attention in the last decades, both in research and in the development of applications for industrial equipments. The use of heat exchangers is universal in power stations, refineries, air-conditioning systems and propulsion systems (land, aeronautical and maritime). ln marine power plants, heat exchangers are essential for the correct operation of the ship, considering they are used in main propulsion machinery and in auxiliary systems. During the last years, for reasons of efficiency and occupied space, conventional shell and tube heat exchangers have been replaced by more efficient and compact plate heat exchangers. This work is focused on the study of plate heat exchangers, being the key objective to contribute to the development of the state of the art in this field through testing and modeling of plate heat exchanger with corrugate plate type "chevron". The present work has been developed in four phases: The first phase consisted in obtaining experimental data of plate and shell and tube heat exchangers from a heat exchanger training bench existing at ENIDH (Escola Superior Náutica Infante D. Henrique). For identical operating conditions, experimental data has been analyzed and compared and reason that motivated the replacement of the heat exchangers has been confirmed. Also, in this working phase, experimental uncertainty and evaluation of the quantities that most contribute for this uncertainty have been analyzed. The second phase consisted in the analytical modeling of the same plate heat exchangers, through the use of correlations available in the literature. Since the results obtained were not satisfactory, new correlations were developed, which resulted in a new model that showed a good agreement with experimental data. For conditions dose to the maximum power, the sensitivity of the developed model was evaluated considering possible changes in the operating conditions of real marine propulsion plants. The third phase consisted three-dimensional numerical simulation of same plate heat exchangers, using a commercial computer fluid dynamics (CFD) application. The influence of plate configuration, boundary conditions and plate tops on the behavior of plate heat exchangers has been analyzed. Despite being laborious and a computationally heavy numerical simulations led to satisfactory result, from an engineering point of view, and open new possibilities for the simulation of heat exchangers with other geometrical configurations. The fourth phase consisted in the analysis of the heat exchanger performance when different fluids like fresh water, sea water and lubricating oil, typical of marine power plants. This analysis was carried out using the model based on new correlations developed in the phase two, mentioned above.
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Ntamba, Ntamba Butteur Mulumba. "Non-Newtonian pressure loss and discharge coefficients for short square-edged orifices plates." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1252.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011.Despite the extensive research work carried out on flow through short square-edged orifice plates over the last century (e.g. Johansen, 1930; Benedict, 1977; Alvi et al., 1978; Swamee, 2005; ESDU, 2007), gaps in the engineering data still exist for certain ranges of flow conditions and geometries. The majority of data available in the literature are for Newtonian fluids in the turbulent flow regime (ESDU, 2007). Insufficient data have been observed for the orifice with pipe diameter ratio, β = 0.2, in the laminar flow regime. There are no experimental data for β = 0.3 and 0.57. The objective of this thesis was to conduct wide-ranging experimental studies of the flow in orifice plates, which included those geometrical configurations, by measuring pressure loss coefficients and discharge coefficients across the orifice plates using both Newtonian fluids and non-Newtonian fluids in both laminar and turbulent flow regimes. The test work was conducted on the valve test rig at the Cape Peninsula University of Technology. Four classical circular short square-edged orifice plates having, β = 0.2, 0.3, 0.57 and 0.7, were tested. In addition, two generation 0 Von Koch orifice plates (Von Koch, 1904), with equivalent cross sectional area were also tested for β = 0.57. Water was used as Newtonian fluid to obtain turbulent regime data and also for calibration purposes to ensure measurement accuracy and carboxymethyl cellulose, bentonite and kaolin slurries were used at different concentrations to obtain laminar and transitional loss coefficient data. The hydraulic grade line method was used to evaluate pressure loss coefficients (Edwards et al., 1985), while the flange tap arrangement method was used to determine the discharge coefficients (ESDU, 2007). A tube viscometer with three different pipe diameters was used to obtain the rheological properties of the fluids. The results for each test are presented in the form of pressure loss coefficient (kor) and discharge coefficient (Cd) against pipe Reynolds number (Re)
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Laffay, Paul. "Etude aéroacoustique de la détente d'un écoulement haute pression à travers des plaques perforées." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC020/document.
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Le bruit généré par la détente d'un écoulement sous pression à travers des plaques multi-perforées ou des diaphragmes est étudié expérimentalement. Cette analyse est menée sur deux configurations géométriques distinctes dans lesquelles la plaque perforée est placée à la sortie d'un conduit cylindrique (configuration de jet libre) ou à l'intérieur de celui-ci (configuration de jet confiné).Dans un premier temps, une étude paramétrique acoustique est effectuée pour ces deux configurations en variant les caractéristiques géométriques des plaques perforées et les points de fonctionnement dans des régimes subsoniques et supersoniques. Les différentes sources de rayonnement pouvant apparaitre sur de tels systèmes de détente, sont alors identifiées. Par ailleurs, les effets acoustiques de chacun des paramètres géométriques sont mis en lumière, offrant ainsi une aide à la conception silencieuse de tels systèmes. Dans un second temps, l'intérêt est porté sur l'analyse de la composante à large bande dominante: le bruit de mélange. Cette étude est menée sur la configuration de jet libre et s'appuie sur des visualisations strioscopiques ainsi que sur des mesures de vélocimétrie par image de particules couplées à des acquisitions acoustiques en champ lointain. Dans le cas des diaphragmes, les différents résultats mettent en évidence des mécanismes sources du bruit de mélange similaires à ceux observés dans la littérature pour les jets isolés issus de tuyères. Le rayonnement à l'aval, dominant, est généré par l'interaction de grosses structures turbulentes cohérentes à la fin du cône potentiel du jet, tandis que dans les autres directions, le bruit est généré par la turbulence de petite échelle dans les couches de cisaillement du jet.Pour les plaques multi-perforées, des mécanismes comparables sont également identifiés. Néanmoins, selon la géométrie de ces plaques, deux zones sources distinctes du rayonnement aval sont identifiées favorisant l'apparition de deux bosses dans les spectres en champ lointain. Dans le cas de perforations éloignées, la bosse à plus haute fréquence domine le spectre aval et l'interaction des grosses structures turbulentes se produit au niveau de la fin du cône potentiel des jets. Lorsque les perforations sont en revanche proches, c'est la bosse à basse fréquence qui domine et l'interaction des grosses structures turbulentes cohérentes semble se produire près de la fin du cône potentiel du gros jet équivalent formé à l'aval à partir du mélange de l'ensemble des jets issus des perforations. Dans les autres directions, l'espacement des perforations joue également un rôle important sur le rayonnement acoustique, du fait d'une interaction plus ou moins rapide des jets entre eux. Cela a alors pour effet de modifier les zones de cisaillement et en conséquence le rayonnement acoustique de la même manière que dans la direction avalThe noise generated by the expansion of a pressurized flow through multi-perforated plates or diaphragms is experimentally investigated. The analysis is conducted on two distinct geometrical configurations in which the perforated plate is placed at the outlet of (free jet configuration) or inside (ducted jet configuration) a cylindrical duct.Firstly, an acoustic parametric study is carried out on these two configurations for various perforated plate geometries and for a number of operating points ranging from subsonic to supersonic. The different acoustic sources that can arise from such systems are thus identified. Furthermore, the effect of each geometrical parameter onto the radiated sound field is highlighted, thus providing guidelines for the silent design of such pressure release devices.In a second step, the focus is on the dominant broadband component, that is, the mixing noise. This part of the study is dedicated to the free jet configuration and is based on Schlieren imaging, as well as on Particle Image Velocimetry measurements, both coupled far-field sound measurements.In the diaphragm cases, the aerodynamic results show that the source mechanisms are similar to those reported in the literature about isolated jets from conventional nozzles. The downstream radiation is generated by the interaction of large coherent structures at the end of the jet potential core, while in the other directions it is generated by the small-scale turbulence from the shear layer.For multi-perforated plates, comparable mechanisms are also observed. However, depending on the plate geometry, two distinct source regions contributing to the downstream radiation are identified. They explain the presence of two broadband humps in the far-field spectra. In the case of widely spaced perforations, the higher frequency hump in the downstream spectrum increases and the interaction of the large turbulent structures occurs mainly at the end of the potential core of the small jets issuing the perforations. Conversely, when these perforations are close to each other, the small jets rapidly merge into a single larger one that has a longer potential core. As a result, larger coherent structures interact downstream of the small jet mixing region and therefore, a low-frequency hump dominates the downstream spectrum. In the other directions, the perforation spacing has also a significant impact on the acoustic radiation, due to a more or less rapid interaction of the jets. Consequently, the turbulence, as well as the shear zones of the various mixing layers, are modified. The geometric parameters thus have similar effects on the cross-stream as on the downstream radiation