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Fouari, Aziz. "Contribution à l'étude de la diffusion de la chaleur en aval d'une source linéaire placée dans un jet plan turbulent." Rouen, 1986. http://www.theses.fr/1986ROUES013.
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Etude expérimentale du champ de vitesse moyenne et des fluctuations de vitesse, des champs de température moyenne et de fluctuations de température. Comparaison avec d'autres écoulements turbulents (couche limite turbulente, turbulence de grille, écoulement de conduite). Modèle physique basé sur le comportement relatif du sillage instantané et du sillage moyen décrivant les deux zones du processus de diffusion dans le cas de la couche limite turbulente et le jet plan turbulent
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Ступак, Олександр Юрійович. "Кінематичний аналіз плоского важільного механізму програмними засобами(робота)". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/29553.
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У наш час завдання кінематичного аналізу механізмів найчастіше вирішуються графічними або аналітичними методами. З розвитком мов програмування та можливостей відповідних середовищ розробки стає можливою реалізація кінематичного аналізу плоских важільних механізмів програмними методами. Запропонована реалізація являється комбінованим графоаналітичним методом, оскільки аналітичне рішення засноване на графічних побудовах та рішенні відповідних геометричних задач. За допомогою мови програмування Processing реалізовано програмне забезпечення для кінематичного аналізу простих важільних механізмів. Кінематичний аналіз, важільний механізм, мова програмування Processing.<br>Nowadays, the problem of kinematic analysis of mechanisms is most often solved by graphical or analytical methods. According to the development of programming languages and the possibility of corresponding development environments, it becomes possible to implement the kinematic analysis of flat lever mechanisms using software methods. The proposed implementation is a combined graphoanalytical method, since the analytical solution is based on graphical constructions and the solution of the corresponding geometric problems. Using the programming language Processing implemented software for the kinematic analysis of simple lever mechanisms.
Kinematic analysis, lever mechanism, programming language Processing.<br>В наше время задача кинематического анализа механизмов чаще всего решаются графическими или аналитическими методами. По развитию языков программирования и возможности соответствующих сред разработки становится возможна реализация кинематического анализа плоских рычажных механизмов программными методами. Предложен а реализация является комбинированном графоаналитическим методом, поскольку аналитическое решение основано на графических построениях и решении соответствующих геометрических задач. С помощью языка программирования Processing реализовано программное обеспечение для кинематического анализа простых рычажных механизмов. Кинематический анализ, рычажный механизм, язык программирования Processing.
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Cabrera, Gomez Jose Julian. "Velocity-dip analysis in the plane-wave domain." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30604.
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Plane-wave decomposition and slant stack transformation have recently gained much interest as viable routes to perform a variety of prestack processing tasks, such as velocity estimation, migration, filtering, deconvolution, and velocity inversion. To further complement the current advances, the problem of earth model parameter estimation and prestack structural imaging are addressed in this work. Unlike existing methods, the algorithms presented here make a novel and systematic use of the plane-wave domain to determine migration and interval velocities, interface dip angles and common-shot gather reflector images.
To start, a method is developed to estimate migration velocities and interface dip angles in earth models composed of planar, dipping reflecting interfaces separating homogeneous layers, and where straight-ray travelpaths to the reflecting interfaces can be assumed. The method consists of transforming a common-shot gather into the plane-wave domain, where a semblance analysis search along cosinusoid trajectories is performed. Since the cosinusoid trajectories are functions of the migration velocity and interface dip angle, selection of the maximum semblance values yields the best estimates to the desired earth model parameters.
To remove the straight-ray assumption of the velocity-dip analysis method, a recursive technique is developed to estimate
interval velocities and interface dip angles via a ray tracing algorithm. This technique essentially generates plane-wave domain traveltimes for a range of interval velocities and interface dip angles, and computes the error between the generated and observed plane-wave traveltimes. The minimum error determines the best estimates of the earth model parameters.
With the information attained in the velocity-dip analysis algorithm, a plane-wave based imaging method is developed to produce prestack common-shot gather images of the reflecting interfaces. The method consists of transforming a common-shot gather into the plane-wave domain, where a velocity-dip semblance analysis is performed. Then, the plane-wave components are downward extrapolated and recombined via a dip-incorporated inverse slant-stack transformation to produce the spherical-wave field that would have been recorded by receivers placed on the reflecting interfaces. The dip incorporation consists of redefining the angle of emergence of the plane waves. Finally, a simple mapping algorithm converts the offset and time coordinates of the reconstructed wave field to the true horizontal location and two-way vertical time of the reflection points. This results in the desired prestack migrated images of the reflecting interfaces.
In this thesis, a novel algorithm to perform plane-wave decomposition via Fourier transforms is also proposed. This algorithm consists of the application of the double fast Fourier
transform to the input data, followed by complex vector multiplications with essentially the Fourier representation of the Bessel function J0 . A numerical singularity is avoided by applying an analytical expression that approximately accounts for the singular point contribution. An inverse fast Fourier transform from frequency to time gives the desired plane-wave seismogram.
The techniques proposed in this work have yielded encouraging results on synthetic and field data examples. The examples demonstrate, for the first time, the systematic use of the plane-wave domain in processing seismic reflection data from common-shot gather data to the plane-wave domain, to velocity and dip angle analysis and to prestack structural imaging. It is believed that the results from this work will help researchers as well as practising geophysicists to become better acquainted with plane-wave domain processing.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate
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Collins, Justin Andrew. "Velocity and free surface measurements of free plane jets." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17888.
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Windholtz, Timothy Nolan. "Plane-Strain Formability of Sheet Metal at High Velocity." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332509672.
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Buono, Jared. "Assessing the Ecohydrologic Consequences of Woody Plant Encroachment." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195347.
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This three part study attempted to enhance our understanding of vegetation change and its potential effects on ecohydrology in drylands. The first study developed a method to measure the velocity of shallow overland flow. Under rainfall simulation, dye tracers were applied to runoff and photographed to calculate mean surface velocity. Results showed this approach was a significant improvement explaining 13% more of the variation in mean velocity compared to traditional methods. Results from the first study were used to compare hydraulic parameters on shrub- and grass-dominated plots in the second study. Previous research has suggested microtopography in shrublands acts to concentrate flow, leading to increased runoff velocity compared to grasslands. However, present findings showed that flow velocities were similar on many grass and shrub plots; only plots with ground cover > 90% exhibited significantly lower flow velocities, and some shrub-dominated plots had lower flow velocities than grass-dominated plots implying that horizontal water flux is reduced under certain states of woody plant encroachment. In terms of ground cover characteristics, velocity increased rapidly with increases in the fraction of bare soil, up to a value of ~20% bare soil. Above ~20% bare soil, basal gap became a dominant factor suggesting a possible threshold where spatial metrics related to the distance between plants become important indicator of shallow flow velocity. The third study tested an approach to quantify woody plant canopy metrics over large areas. Radar has been used to map biomass in forests but few studies have examined open canopy ecosystems. Field measurements of shrublands were compared to satellite images to identify the relationship between radar signal and height and cover of woody vegetation. Results indicated that radar signal increased positively with shrub height or shrub volume explaining 74% and 90% of the variation, respectively. The effect of surface roughness and sub-canopy species on radar signal appears reduced when images are collected at large incidence angles.
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Jiao, Junru. "Residual migration velocity analysis in the plane wave domain : theory and applications /." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3023551.
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Styles, Julie M. "A wind tunnel study of the velocity field above a model plant canopy." [Canberra] : CSIRO Land and Water, 1997. http://nla.gov.au/nla.arc-13482.
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Thesis (B.Sc. (Honours)) - Australian National University, 1997.<br>Title from title screen (viewed on May 20, 2002). "A thesis submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science (Honours)"--Title screen. Bibliography: p. 64-66. Available full text via the internet.
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Salamanca, Gabriel Enrique Dicelis. "Estudo integrado da camada de basalto em Bebedouro - SP, Bacia do Paraná: relocalização dos sismos induzidos por poços tubulares." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-10082011-215956/.
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Dicelis, G. E., Estudo Integrado da Camada de Basalto em Bebedouro SP, Bacia do Paraná: Relocalização dos sismos induzidos por poços tubulares, 2011. Dissertação de Mestrado Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, SP. A partir de 2004, a população do distrito de Andes, Bebedouro (SP), passou a sentir pequenos tremores de terra. Uma rede sismográfica instalada em 2005 mostrou que os sismos locais são induzidos por poços tubulares profundos usados para irrigação de lavouras (Assumpção et al., 2007). Neste projeto de pesquisa foi melhorada a localização desses sismos, usando análise da forma de onda e os tempos de chegada das ondas P e S, com o propósito de efetuar uma melhor análise da sismicidade induzida. Para isto foram aproveitados resultados de estudos anteriores como sísmica de refração, dispersão de ondas de superfície, sondagem elétrica vertical, função do receptor e TDEM. Para obter o melhor modelo de velocidades 1D, foram testados diferentes algoritmos de localização e técnicas de relocalização de hipocentros, para aproximadamente 3000 microtremores gravados pela rede sismográfica no período 2005 2010. Os resultados mostraram que as profundidades focais dos sismos relocalizados ficaram em sua maioria dentro da camada de basalto, a menos de 500m de profundidade. Este resultado confirma que os sismos estão relacionados com a perturbação do equilíbrio de tensões (pressões) geológicas, em zonas de fraturas já existentes dentro da camada de basalto. Foi usada uma combinação de correlação cruzada e tempos de chegada para analisar um conjunto de sismos, baseada na similaridade dos seus sismogramas. Foi melhorada a distribuição hipocentral o que permitiu determinar claramente uma solução do plano focal de um cluster, o que indicou a existência de uma falha normal de orientação WNW-ESSE e mergulho para o norte, com extensão NNE-SSW (eixo-T). Este mecanismo pode complementar os dados de esforços na região sudeste.<br>Dicelis, G. E., Integrated Study of the basalt layer in Bebedouro SP, Paraná Basin: Relocation of earthquakes induced by wells, 2011. Master dissertation - Institute of Astronomy, Geophysics and Atmospheric Sciences of the University of Sao Paulo, Brazil. Since 2004 the population of the district of Andes, Bebedouro SP, began to feel small earthquakes. A seismograph network installed in 2005 showed that earthquakes are caused by local deep wells used for irrigation of crops (Assumpção et al., 2007). In this research project we improved the location of these earthquakes, using analysis of waveform and the arrival times of P and S waves, in order to make a better analysis of the induced seismicity. To better relocate the events we determined a velocit model using results of previous studies such as seismic refraction, surface wave dispersion, vertical electrical sounding, receiver function and TDEM. The best fit 1D model was achieved testing different localization algorithms and techniques for relocation of hypocenters for approximately 3000 microtremors recorded by seismograph network to the period 2005 2010. The results showed that the focal depths of the relocated earthquakes are mostly within the basalt layer, less than 500m depth. This confirms that the earthquakes are related with disturbance of geological stresses (pressures) in pre-existing fracture zones within the basalt layer. We used a combination of cross-correlation and arrival times for analyze a set of earthquakes, based on the similarity of their recorded seismograms. The hypocentral distribution was improved allowing a clear determination of the best fit fault plane solution for one cluster, which indicates the existence of a normal fault with direction WNW-ESE and dip to the north, with NNE-SSW extension (T-axis). This mechanism may complement the stress data in the Southeast Brazil.
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Harsha, Senusi Mohamed. "Interpretation of Southern Georgia coastal plain velocity structure using refraction and wide-angle reflection methods." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/25886.
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Zhou, Yu. "Simulation of High-velocity Penetration for Rigid Projectile into Plain Concrete Target using Discrete Element Method." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31325.
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Penetration of high velocity is of concern for both civilian and military research for decades, and computerized simulation is the scholarâ s focus in recent years. This study presents a study on the Discrete Element Method (DEM) simulation of plain concrete targetâ s behavior under high-velocity penetration of rigid projectile.
In this thesis, different types of research works including empirical, analytical and numerical methods in penetration by the previous scholars were carefully reviewed. A DEM-based concrete model was established by using software PFC3D. The major micro-variables of the simulation program were calibrated according to the required macro-mechanical parameters. Meanwhile, their correlations within the concrete range were studied, with the sensitivity analysis and the corresponding regression equations.
With the established digital concrete model, penetration simulation tests were carried out. The results of penetration depth versus impact velocity were compared with the experimental and empirical calculated results from Forrestalâ s work in 1994. A good agreement was obtained. Some other simulation studies, like projectile mass, geometry, penetrating acceleration, concrete response stress, strain, and strain-rate were also conducted to study the constitutive properties in this thesis.<br>Master of Science
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Tetzlaff, Gerd, and Uwe Hoppmann. "Die Leistung von AEOLUS II in Abhängigkeit von mittlerem Windprofil und Turbulenz im Bereich der Rotorfläche." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-212831.
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Synchrone Messungen der Windgeschwindigkeit und die Leistung von Windkraftanlagen dienen der Ermittlung der Kennlinien der Anlagen. Die existierenden Vorschriften zur Vermessung enthalten bezüglich der Strömungseigenschaften des Windes nahezu keine Spezifikationen. Diese sind jedoch notwendig, um die erreichbare Genauigkeit und Repräsentativität der vermessenen Kennlinie zu quantifizieren. Messungen am Standort der AEOLUS II-Anlage in Wilhelmshaven dienten dazu, bei einer Anlagenvermessung die Eigenschaften der Strömung und die Kennlinie gemeinsam zu untersuchen. Es wurde gefunden, daß die Strömungseigenschaften wie die vertikale Windscherung, die Winddrehung über der Höhe, die turbulenten Schwankungen der Windgeschwindigkeit und der Windrichtung die Leistung von Windenergieanlagen bei gleicher mittlerer Windgeschwindigkeit erheblich verändern. Dabei wirken sowohl Standorteigenschaften als auch die Witterung auf die Ergebnisse der Vermessung. Am gleichen Standort können in anisotropem Gelände die Werte der Kennlinie auch bei mehrmonatigen Vermessungen wegen der Variabilität der Windrichtung Unterschiede von mehr als 10 % aufweisen. Der größte Einzeleffekt wird von der vertikalen Windscherung verursacht, die Wirkung der Drehung des mittleren Windvektors über der Rotorfläche ergab sich als kleinerer Effekt. Die Wirkung der turbulenten Schwankungen von Geschwindigkeit und Richtung weisen meist unterschiedliche Vorzeichen auf, so daß die Rolle dieser Schwankungen insgesamt meist klein bleibt. Die Vermessung einer Kennlinie mit einer kleineren systematischen Abweichung von im Mittel weniger als etwa 5 bis 10 % erfordert eine genaue Strömungsspezifikation sowohl für den Vermessungs- als für den Betriebsstandort, die bisher nicht in hinreichendem Maße in den entsprechenden Richtlinien und Vorschriften enthalten sind<br>Power curves ofwind energy convetras need synchronous measurements of wind and power. The existing specification on the wind measurements are rather poor, however necessary. AEOLUS II-measurments and the wind measurments served to quantify the role of the different atmospheric parameters. Thus it was possible to define the influence on the power output of the machine as a function of the vertical wind shear, the wind veer with height, the turbulent fluctuations with the average wind speed being constant. As a consequence site properties and weather conditions both influence the measurements of the power curve. As a major result it was found that these factors may alter the power curve by as much as 10 %. The largest single effect is produced the effects of the vertical wind shear, The turbulent fluctuations are somewhat smaller in their effect, because speed and direction effects tend to compensate each other. lt may be concluded that a highly accurate power curve - meaning errors to be less than 10 % - requires a fully specified set of weather and site parameters
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Sushanta, Mitra. "Breakup Process of Plane Liquid Sheets and Prediction of Initial Droplet Size and Velocity Distributions in Sprays." Thesis, University of Waterloo, 2001. http://hdl.handle.net/10012/931.
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Spray models are increasingly becoming the principal tools in the design and development of gas turbine combustors. Spray modeling requires a knowledge of the liquid atomization process, and the sizes and velocities of subsequently formed droplets as initial conditions. In order to have a better understanding of the liquid atomization process,the breakup characteristics of plane liquid sheets in co-flowing gas streams are investigated by means of linear and nonlinear hydrodynamic instability analyses. The liquid sheet breakup process is studied for initial sinuous and varicose modes of disturbance. It is observed that the sheet breakup occurs at half-wavelength intervals for an initial sinuous disturbance and at full-wavelength intervals for an initial varicose disturbance. It is also found that under certain operating conditions, the breakup process is dictated by the initial varicose disturbance compare to its sinuous counterpart. Further, the breakup process is studied for the combined mode and it is found that the sheet breakup occurs at half- or full-wavelength intervals depending on the proportion of the individual sinuous and varicose disturbances. In general, the breakup length decreases with the increase in the Weber number, gas-to-liquid velocity and density ratios. A predictive model of the initial droplet size and velocity distributions for the subsequently formed spray is also formulated here. The present model incorporates the deterministic aspect of spray formation by calculating the breakup length and the mass-mean diameter and the stochastic aspect by statistical means through the maximum entropy principle based on Bayesian entropy. The two sub-models are coupled together by the various source terms signifying the liquid-gas interaction and a prior distribution based on instability analysis, which provides information regarding the unstable wave elements on the two liquid-gas interfaces. Experimental investigation of the breakup characteristics of the liquid sheet is performed by a high speed CCD camera and the measurement of the initial droplet size and distributions is conducted by phase-Doppler interferometry. Good agreement of the theoretical breakup length with the experiment is obtained for a planar, an annular and a gas turbine nozzle. The predicted initial droplet size and velocity distributions show reasonably satisfactory agreement with experimental data for all the three types of nozzles. Hence this spray model can be utilized to predict the initial droplet size and velocity distributions in sprays, which can then be implemented as a front-end subroutine to the existing computer codes.
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Marsden, Katelyn Randi Lee. "Cerebral blood flow velocity : does it play a role in symptom exacerbation during exercise in concussed athletes?" Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45239.
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Exercise frequently results in exacerbation of symptoms following a sports-related concussion (SRC). However, the mechanism(s) behind this phenomenon has yet to be determined. It is possible that an inability to regulate cerebral blood flow (CBF) may lead to over-perfusion, and thus cause the exacerbation of symptoms seen during exercise. It was hypothesized that: 1) CBF velocity during exercise will be greater in SRC. 2) Severity of symptoms will be correlated with CBF velocity during exercise and 3) day-to-day variability in CBF velocity will be greater in SRC compared to control subjects. Subjects refrained from caffeine, alcohol and exercise 24hrs prior to testing. Blood velocity was monitored using transcranial Doppler targeting both the middle and posterior cerebral artery (MCAv and PCAv). Exercise was performed on a stationary bike at 30% and 70% predicted heart rate reserve (HRR) for 2-3 minutes and changes in MCAv and PCAv were compared to baseline at rest. Symptoms were evaluated using SCAT2 pre and post-exercise. Subjects included 6 subjects (5 males and 1 female) diagnosed with sport-related concussion (mean ± standard deviation; age: 17.5±2 years, BMI: 24±1 kg/m²) and 6 healthy control-subjects (5 males and 1 female; age: 20±2 years, BMI: 22±2 kg/m²). Concussed subjects were tested at the same time of day on Day 4±1, Day 8±1, Day 17±3 and Day 29±1 following injury. Assessment of day-to-day variability also conducted using the test-retest method with the inclusion of a subgroup of control subjects (n=12). Results demonstrated that 1) there was no effect of concussion on resting MCAv or PCAv over the month post-injury. In addition, no effect of concussion was seen on the relative changes in MCAv or PCAv at either 30% or 70% HRR. 2) A linear regression revealed a relationship between the increase in both number and severity of symptoms and MCA velocity response to 70% HRR (R² = 0.37). 3) Concussion did not significantly change day-to-day variability over the course of testing. Taken together, these results demonstrate that SRC does not significantly impact CBF responses during mild to moderate exercise; however, MCAv response may play a role in symptom exacerbation during exercise.
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Thakur, Sandeep. "Cleaning flax fibre; extracting and identifying antimicrobials and measuring water absorption of plant stems." ASABE-CSBE Joint conference 2014, Montreal, 2014. http://hdl.handle.net/1993/30686.
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Decorticated flax contains a significant amount of shive content, which limits applications of flax fibre. Separation of shives from the fibre is essential to improve the quality of flax fibre. Pneumatic method and a Sorter were implemented to meet the above objective. Terminal velocities of individual flax fibre and shive particles were investigated and their width, length, and mass were recorded. A sorting method was used for separation of short and long fibre for two grades of fibre: Grade 1 and Grade 2, with initial fibre purities of 51% and 15%, respectively. The ranges of terminal velocities for shive and fibre particles were 1.13 to 4.09 m/s and 0.51 to 1.07 m/s, respectively, which were significantly different. Fibre purity of approximately 80% for Grade 1 and 66% for Grade 2 were recorded from sorting, which were a significant improvement when compared to the initial purities. This study demonstrated the potential of the pneumatic and sorting methods for improving fibre quality.
With the increase in resistant strains of microorganisms to antibiotics, researchers have started to explore plant parts to discover new antimicrobials. Since medieval times all portions of plants were used medicinally. Plant tissues, including stems, possess secondary metabolites (SMs), which have known antimicrobial properties. The purpose of this study was to investigate: the presence of antimicrobial compounds in stem extracts of canola, flax, hemp, and sweet clover; and study sorption-desorption behavior of their powdered stem material. GC-MS analysis of all extracts showed the presence of many SMs, including fatty acids, terpenoids, steroids, and sterols, etc. Many of the SMs found in the extracts have previously shown antimicrobial activity against a broad spectrum of organisms according to literature. Water sorption isotherms of stems showed a typical IUPAC Type II sigmoid curve similar to natural fibres. Equilibrium moisture content (EMC) of canola and sweet clover was significantly higher than flax and hemp at 95% RH, which were all higher than the fibre saturation point of wood (27%). The preliminary investigation via GC-MS showed promising results and water absorptivity results of stems can be used as the initial key property for many applications.<br>October 2015
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Riener, Manuel [Verfasser], and Henrik [Akademischer Betreuer] Beuther. "The detailed velocity structure and distribution of 13CO emission in the Galactic plane / Manuel Riener ; Betreuer: Henrik Beuther." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/121424291X/34.
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Fimiani, Fosca. "Study of the calibration method of pressure-velocity probes and its application in a field of progressive plane waves." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10817/.
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This dissertation presents a calibration procedure for a pressure velocity probe.
The dissertation is divided into four main chapters. The first chapter is divided into six
main sections. In the firsts two, the wave equation in fluids and the velocity of sound in gases
are calculated, the third section contains a general solution of the wave equation in the case
of plane acoustic waves. Section four and five report the definition of the acoustic impedance
and admittance, and the practical units the sound level is measured with, i.e. the decibel scale.
Finally, the last section of the chapter is about the theory linked to the frequency analysis of a
sound wave and includes the analysis of sound in bands and the discrete Fourier analysis, with
the definition of some important functions.
The second chapter describes different reference field calibration procedures that are used to
calibrate the P-V probes, between them the progressive plane wave method, which is that
has been used in this work. Finally, the last section of the chapter contains a description of the
working principles of the two transducers that have been used, with a focus on the velocity one.
The third chapter of the dissertation is devoted to the explanation of the calibration set up and
the instruments used for the data acquisition and analysis. Since software routines were extremely
important, this chapter includes a dedicated section on them and the proprietary routines most
used are thoroughly explained. Finally, there is the description of the work that has been done,
which is identified with three different phases, where the data acquired and the results obtained
are presented. All the graphs and data reported were obtained through the Matlab® routine.
As for the last chapter, it briefly presents all the work that has been done as well as an
excursus on a new probe and on the way the procedure implemented in this dissertation could
be applied in the case of a general field.
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Worcester, Katherine Sara. "EFFECTS OF INERTIAL LOAD ON SAGITTAL PLANE KINEMATICS DURING FLYWHEEL-BASED RESISTANCE TRAINING SQUATS." UKnowledge, 2018. https://uknowledge.uky.edu/khp_etds/57.
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Background: Training to increase muscular power is essential for improving athletic performance in most sports. Weight training (WT) is a common means for training muscular power. Another modality, flywheel resistance training (FRT), may be superior for improving muscular power. However, few studies have examined if FRT is kinematically similar to WT, or if FRT kinematics change with increasing inertial load. The purposes of this study were to determine how sagittal plane joint kinematics are affected by increasing inertial load during FRT squats, and to determine how FRT squat joint kinematics compare to WT squat joint kinematics.
Methods: Subjects (n=9) completed three visits for this study. On the first visit subjects completed squat 1 repetition maximum (1RM) testing. The second visit served as a full FRT familiarization session in which subjects performed one set of 5 maximal effort FRT squats at each inertial load (0.050, 0.075, and 0.100 kgm2). On the third visit, subjects were videoed in the sagittal plane while performing the FRT squat protocol. Subjects then completed 5 maximal velocity repetitions of WT squats with the barbell loaded according to the Kansas Squat Test (KST) protocol. Kinematic differences between inertial loads were determined via 1-way repeated measures ANOVAS while differences between FRT and WT were determined with paired T-tests.
Results: There were no differences in peak sagittal plane knee, trunk-hip, trunk (absolute) or ankle angles between inertial loads. Peak and mean joint angular velocities decreased with increasing inertial loads at the knee and trunk-hip. Mean joint angular velocities decreased at the ankle with increasing inertial loads, while peak and mean trunk (absolute) angular velocities were unaffected. No statistical analyses were conducted for FRT and WT comparison as not enough subjects met the criteria (n=3).
Conclusions: Sagittal plane joint kinematics are largely maintained despite increasing inertial load during FRT squats. Lower extremity joint angular velocities decreased with increasing inertial load. If training for muscular power and knee extensor velocity is the goal, then the inertia of 0.050 kgm2 is most suitable.
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Bellec, Morgane. "Études du couplage entre turbulence et gradient de température pour l'intensification des transferts de chaleur dans les récepteurs solaires à haute température." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0005/document.
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Une voie prometteuse pour améliorer le rendement des centrales solaires à tour consiste à chauffer de l'air pressurisé à haute température afin d'alimenter un cycle thermodynamique de Brayton. Pour cela, il est indispensable de concevoir des récepteurs solaires performants,permettant de forts transferts de chaleur vers le fluide. Le développement de tels récepteurs passe par une compréhension fine de leurs écoulements internes. Il s'agit d'écoulements complexes, combinant de hauts niveaux de turbulence et un fort gradient de température entre la paroi irradiée par le flux solaire concentré et la paroi arrière isolée. On se propose dans ce travail de réaliser une étude amont numérique et expérimentale de ce type d'écoulements.D'une part, des mesures de vitesse par SPIV (vélocimétrie par images de particules stéréoscopique) sont effectuées dans une soufflerie de canal plan turbulent lisse dont la cellule de mesure est représentative d'un récepteur solaire surfacique. On observe en particulier l'influence d'un chauffage asymétrique sur les statistiques de la turbulence. Ces mesures sont d'autre part complétées par des simulations fines LES (simulation des grandes échelles)menées dans les conditions de la soufflerie. Pour finir, une simulation LES d'un canal plan texturé sur une paroi par une géométrie innovante est conduite. Cette architecture interne du récepteur combine des générateurs de tourbillon et des riblets afin d'intensifier les échanges de chaleur vers le fluide<br>A promising line of research to increase the efficiency of solar tower power plants consists in heating pressurized air to high temperatures in order to fuel a Brayton thermodynamic cycle. This requires to design effective solar receivers that allow for intense heat transfers toward the fluid. To develop such receivers, an in-depth understanding of their internal flows is needed. These are complex flows, combining strong turbulence and strong temperature gradient between the concentrated sun irradiated wall and the back insulated wall.The aim of this work is to investigate numerically and experimentally such flows.On one hand, velocities are measured by SPIV (Stereoscopic Particle Image Velocimetry) in a turbulent channel flow wind tunnel whom measurement cell is similar to a surface solar receiver. The influence of an asymmetric heating on the turbulence statistics are especially investigated. These measurements are supplemented by Large Eddy Simulations run under the same conditions as the wind tunnel. Finally, a Large Eddy Simulation is run in a channel flow textured on one wall by an innovative geometry. This internal receiver design combines vortex generators and riblets in order to enhance the heat transfers
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Kanaki, Kalliopi. "Electric Field and Drift Characteristics Studies for the Multiwire Chambers of the Third Plane of HADES." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-29306.
Full textAbstract:
Aim of this report is the investigation of suitable operational conditions for the drif{}t chambers MDC III installed in the HADES setup. The simulations performed showed that operating the drif{}t chambers in a mode with nearly constant electron drif{}t velocity in a predominant part of the cell allows a more precise and fast tracking. This is particularly important for electrons and positrons; here the invariant dilepton mass must be reconstructed with high precision to get a resolution of $\Delta M/M\approx 1\%$ for the $\omega$ and $\phi$ mass peaks and thus a chance to verify also small in-medium mass shif{}ts. This helps to realize the physics program at HADES which focuses on the search for such mass shif{}ts to get insight into the in-medium behaviour of hadrons in dense strongly interacting matter.
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Kanaki, Kalliopi. "Electric Field and Drift Characteristics Studies for the Multiwire Chambers of the Third Plane of HADES." Forschungszentrum Rossendorf, 2003. https://hzdr.qucosa.de/id/qucosa%3A21758.
Full textAbstract:
Aim of this report is the investigation of suitable operational conditions for the drif{}t chambers MDC III installed in the HADES setup. The simulations performed showed that operating the drif{}t chambers in a mode with nearly constant electron drif{}t velocity in a predominant part of the cell allows a more precise and fast tracking. This is particularly important for electrons and positrons; here the invariant dilepton mass must be reconstructed with high precision to get a resolution of $\Delta M/M\approx 1\%$ for the $\omega$ and $\phi$ mass peaks and thus a chance to verify also small in-medium mass shif{}ts. This helps to realize the physics program at HADES which focuses on the search for such mass shif{}ts to get insight into the in-medium behaviour of hadrons in dense strongly interacting matter.
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Coelho, Fernando José Vinhas Sousa. "Medição da velocidade de chama plana laminar de misturas metano/ar e gás natural/ar utilizando o método de fluxo de calor." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/103804.
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A velocidade de queima laminar adiabática de reações de combustão é um parâmetro chave, relacionado à cinética química do combustível, a qual define características importantes como a forma e a faixa de estabilidade de uma chama. Nos últimos anos, um grande esforço vem sendo direcionado para a determinação precisa desse parâmetro para diferentes combustíveis, porém a grande diversidade de técnicas e metodologias de medição existente acarreta em uma grande dispersão entre os resultados encontrados na literatura. Dentre as várias técnicas disponíveis, o método do fluxo de calor destaca-se por fornecer medidas de velocidade de chama adiabática com boa precisão. O método, diferentemente dos demais existentes, não depende de extrapolações e é capaz de obter chamas aproximadamente adiabáticas. Neste estudo, foi construída uma bancada de trabalho baseada no método do fluxo de calor com a finalidade de medir a velocidade de chama plana laminar adiabática de diferentes misturas entre combustível e comburente. Foram realizadas medições para pré-misturas metano/ar e gás natural/ar em diferentes razões de equivalência (0,65 a 1,5) para a temperatura de 298 K e pressão atmosférica. Uma análise das possíveis fontes de erro é apresentada utilizando-se 95 % de intervalo de confiança, resultando em uma incerteza de 2,8 % para a pré mistura estequiométrica metano/ar para a qual a velocidade de chama encontrada foi de 35,4 cm/s. Nas mesmas condições, para a mistura gás natural/ar foi obtido o resultando de 34,8 cm/s, para a proporção estequiométrica com uma incerteza de 3,1 %. O experimento apresenta incertezas de medição tanto maiores quanto mais afastadas da condição estequiométrica a chama se apresenta, chegando a 20 % para chamas ricas com razão de equivalência 1,5. As medições obtidas para diferentes razões de equivalência mostram-se de acordo com os resultados encontrados na literatura, apresentando valor absoluto e de incertezas dentro dos padrões do método.<br>The adiabatic laminar burning velocity of a fuel/oxidant mixture is a key parameter in combustion. It defines important flame characteristics like its shape and stability range. In the last years, a great effort has been employed on the precise determination of this parameter for different fuels. The diversity of techniques and extrapolation methods for achieving adiabatic flame data results in the large scatter found in literature. Among various techniques available, the heat flux method is known to provide adiabatic burning velocity measurements with good accuracy. The method does not depend on extrapolations and is able to produce flames that closely reach the adiabatic condition. In this study, a workbench was built based on the heat flux method aiming at measuring the adiabatic laminar flame velocity of different fuel and oxidant mixtures. Data were obtained for methane/air and natural gas/air mixtures for different equivalence ratios (0.65 to 1.5) at 298 K and 1 atm. An analysis of possible error sources is also presented using 95% of confidence interval. For a soichiometric methane/air mixture the flame speed was found to be 35.4 cm/s with 2.8% of uncertainty. Under the same conditions, for a stoichiometric natural gas/air mixture the value obtained was 34.8 cm/s with an uncertainty of 3.1%. The experiment shows that the uncertainties increase as the premixture deviates from the stoichiometric condition, reaching 20% for an equivalence ratio of 1.5. The measurements obtained for different equivalence ratios are consistent with results found in the literature and with acceptable uncertainties for the method.
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Tetzlaff, Gerd, and Uwe Hoppmann. "Die Leistung von AEOLUS II in Abhängigkeit von mittlerem Windprofil und Turbulenz im Bereich der Rotorfläche." Universität Leipzig, 1996. https://ul.qucosa.de/id/qucosa%3A15043.
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Synchrone Messungen der Windgeschwindigkeit und die Leistung von Windkraftanlagen dienen der Ermittlung der Kennlinien der Anlagen. Die existierenden Vorschriften zur Vermessung enthalten bezüglich der Strömungseigenschaften des Windes nahezu keine Spezifikationen.
Diese sind jedoch notwendig, um die erreichbare Genauigkeit und Repräsentativität der vermessenen Kennlinie zu quantifizieren. Messungen am Standort der AEOLUS II-Anlage in Wilhelmshaven dienten dazu, bei einer Anlagenvermessung die Eigenschaften der Strömung und die Kennlinie gemeinsam zu untersuchen. Es wurde gefunden, daß die Strömungseigenschaften wie die vertikale Windscherung, die Winddrehung über der Höhe, die turbulenten
Schwankungen der Windgeschwindigkeit und der Windrichtung die Leistung von Windenergieanlagen bei gleicher mittlerer Windgeschwindigkeit erheblich verändern. Dabei wirken sowohl
Standorteigenschaften als auch die Witterung auf die Ergebnisse der Vermessung. Am gleichen Standort können in anisotropem Gelände die Werte der Kennlinie auch bei mehrmonatigen Vermessungen wegen der Variabilität der Windrichtung Unterschiede von mehr als 10 % aufweisen. Der größte Einzeleffekt wird von der vertikalen Windscherung verursacht, die Wirkung der Drehung des mittleren Windvektors über der Rotorfläche ergab sich als kleinerer Effekt. Die Wirkung der turbulenten Schwankungen von Geschwindigkeit und Richtung weisen meist unterschiedliche Vorzeichen auf, so daß die Rolle dieser Schwankungen insgesamt meist klein bleibt. Die Vermessung einer Kennlinie mit einer kleineren systematischen Abweichung von im Mittel weniger als etwa 5 bis 10 % erfordert eine genaue Strömungsspezifikation sowohl für den Vermessungs- als für den Betriebsstandort, die bisher nicht in hinreichendem Maße in den entsprechenden Richtlinien und Vorschriften enthalten sind.<br>Power curves ofwind energy convetras need synchronous measurements of wind and power. The existing specification on the wind measurements are rather poor, however necessary. AEOLUS II-measurments and the wind measurments served to quantify the role of the different atmospheric parameters. Thus it was possible to define the influence on the power output of the machine as a function of the vertical wind shear, the wind veer with height, the turbulent fluctuations with the average wind speed being constant. As a consequence site properties and weather conditions both influence the measurements of the power curve. As a major result it was found that these factors may alter the power curve by as much as 10 %. The largest single effect is produced the effects of the vertical wind shear, The turbulent fluctuations are somewhat smaller in their effect, because speed and direction effects tend to compensate each other. lt may be concluded that a highly accurate power curve - meaning errors to be less than 10 % - requires a fully specified set of weather and site parameters.
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Castro, Alfredo José Alvim de. "Análise experimental de velocidade crítica em elemento combustível tipo placa plana para reatores nucleares de pesquisa." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85133/tde-23052017-160724/.
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Os elementos de combustível de um reator nuclear de pesquisa tipo MTR (\"Material Testing Reactor\") são, em sua grande maioria, formados por placas de combustível revestidas com alumínio contendo no cerne silicileto de urânio (U3Si2) disperso em matriz de alumínio. Essas placas possuem espessura da ordem de milímetros e comprimentos muito maiores em relação à sua espessura. Elas são dispostas paralelamente no conjunto que forma o elemento combustível, de maneira a formar canais entre elas com poucos milímetros de espessura, por onde escoa o fluido de refrigeração (água leve ou água pesada). Essa configuração, associada à necessidade de um escoamento com altas vazões para garantir o resfriamento das placas em operação, pode gerar problemas de falhas mecânicas das placas de combustível devido às vibrações induzidas pelo escoamento nos canais e, consequentemente, acidentes de proporções graves no caso de velocidade crítica que possa gerar o colapso das placas. Embora não haja ruptura das placas de combustível durante o colapso, as deflexões permanentes excessivas das placas podem causar bloqueio do canal de escoamento no núcleo do reator e levar ao superaquecimento nas placas. Para este trabalho, foram desenvolvidas uma bancada experimental com capacidade para altas vazões volumétricas (Q=100 m3/h) e uma seção de testes que simula um elemento combustível do tipo placa com três canais de resfriamento. A seção de testes foi construída com placas de alumínio e acrílico e foi instrumentada com sensores de deformação, sensores de pressão, um acelerômetro e um tubo de pitot. As dimensões da seção de testes foram baseadas nas dimensões do Elemento Combustível do Reator Multipropósito Brasileiro (RMB), cujo projeto está sendo coordenado pela Comissão Nacional de Energia Nuclear - CNEN. Os experimentos realizados alcançaram o objetivo de chegar à condição de velocidade crítica de Miller com o colapso das placas. A velocidade crítica foi atingida com 14,5 m/s levando a consequente deformação plástica das placas que formam o canal do escoamento. O canal central na entrada da seção de testes apresentou uma abertura de 3 mm em seu centro, causando um grande bloqueio do escoamento nos canais laterais. Este comportamento foi v constatado visualmente durante a desmontagem da seção de testes, ilustrado e discutido na análise de resultados apresentado neste trabalho. O bloqueio dos canais também foi observado por meio de gráficos de queda de pressão e por gráficos das deformações da entrada, centro e saída das placas contra a velocidade média da seção de testes. Observou-se uma queda da resistência hidráulica da seção de testes devido ao aumento da seção transversal de escoamento no canal central e um aumento exponencial das deformações quando da ocorrência da velocidade crítica. Comparativamente, o valor experimental obtido para velocidade crítica na seção de testes foi da ordem de 85% do valor obtido por cálculo com a expressão teórica de Miller. Os experimentos realizados permitiram um melhor entendimento da interação fluido estrutura em elementos de combustível tipo placa como: valores de frequências de vibrações naturais, instabilidade fluido elástica e desenvolvimento de técnicas para a detecção de valores de velocidade crítica.<br>The fuel elements of a MTR (Material Testing Reactor) type nuclear reactor are mostly composed of aluminum-coated fuel plates containing the core of uranium silica (U3Si2) dispersed in an aluminum matrix. These plates have a thickness of the order of millimeters and are much longer in relation to their thickness. They are arranged in parallel in the assembly forming the fuel element to form channels between them a few millimeters in thickness, through which there is a flow of the coolant (light water or heavy water). This configuration, combined with the need for a flow at high flow rates to ensure the cooling of the fuel element in operation, may create problems of mechanical failure of fuel plate due to the vibration induced by the flow in the channels. In the case of critical velocity may cause collapse of the plates. Although there is no rupture of the fuel plates during collapse, excessive permanent deflections of the plates can cause blockage of the flow channel in the reactor core and lead to overheating in the plates. For this study were developed an experimental bench capable of high volume flows (Q = 100 m3/h) and a test section that simulates a plate-like fuel element with three cooling channels. The test section was constructed with aluminum and acrylic plates and was instrumented with straingauge sensors, pressure sensors, accelerometer and a tube of pitot. The dimensions of the test section were based on the dimensions of the Fuel Element of the Brazilian Multipurpose Reactor (RMB), whose project is being coordinated by the National Commission of Nuclear Energy (CNEN). The experiments performed attained the objective of reaching Miller\'s critical velocity condition with the collapse of the plates. The critical velocity was reached with 14.5 m/s leading to the consequent plastic deformation of the plates forming the flow channel. The central channel had a 3mm aperture in its center, causing a large blockage of the flow in the lateral channels. This behavior was observed visually during the disassembly of the test section, illustrated and discussed in the results analysis presented in this work. Blocking of the channels was also observed by means of graphs of pressure drop and graphs of the deformations of the entrance, center and exit of the plates against the average speed vii of the section of tests. It was observed a decrease of the hydraulic resistance of the section of tests due to the increase of the transversal section of flow in the central channel and an exponential increase of the deformations when the critical speed occurrence. Comparatively, the value obtained for critical velocity in the test section through the experiments was of the order of 85% of the value obtained by calculation with Miller\'s theoretical expression. The experiments allowed a better understanding of the structure fluid interaction in plate type fuel elements such as: natural vibration frequency values, elastic fluid instability and development of techniques for the detection of critical velocity values.
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SAKAI, Yasuhiko, Nobuhiko TANAKA, and Takehiro KUSHIDA. "On the Development of Coherent Structure in a Plane Jet (Part1, Characteristics of Two-Point Velocity Correlation and Analysis of Eigenmodes by the KL Expansion)." The Japan Society of Mechanical Engineers, 2006. http://hdl.handle.net/2237/9011.
Full text
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Abtahi, Seyed Ali. "Ultrafast Laser Sampling of a Plant Tissue and ion Conductivity Measurement for Investigation of Light Stress Generation Mechanisms." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc31522/.
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In this study we applied ultra-short laser pulses on a biological sample (Arabidopsis), in order to cut it precisely in a square pattern and subsequently use it for studying stress generation mechanisms. For this purpose, we utilized femtosecond laser pulses at 100 fs pulse width and 80 MHz repetition rate. We took two processing parameters into consideration such as laser power, laser exposure time which is related to the stage speed. Therefore, we were able to find the laser optimum conditions for ablation of biological tissues. The mutant and wildtype (control) obtained from laser cutting with a size of 500 µm × 500 µm were directly transferred (in-situ with laser cutting) into a microfabricated chamber containing ~500 nanoliters deionized water for measuring ion conductivity. The ion conductivity is a signature of cell-death mechanisms caused by various stresses. A light with intensity of 100 µmol was exposed to the samples for 2 hours and 20 minutes as a source of stress. A quantitative electrical analysis with high accuracy was assured by utilizing a microchamber, which enables a measurement in nanoliter volume. We measured the impedance which is reciprocal of conductivity using a lock-in amplifier and a precise current source at frequency of 130 Hz. Initially high impedance of mutant sample tended to drop within 2 hours and finally approached the constant value which signified that the cell death mechanism was complete. However, the wildtype sample demonstrated approximately constant impedance (conductivity) during the experiment.
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CASTRO, ALFREDO J. A. de. "Análise experimental de velocidade crítica em elemento combustível tipo placa plana para reatores nucleares de pesquisa." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28022.
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Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-17T17:27:31Z
No. of bitstreams: 0<br>Made available in DSpace on 2017-11-17T17:27:31Z (GMT). No. of bitstreams: 0<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Os elementos de combustível de um reator nuclear de pesquisa tipo MTR (\"Material Testing Reactor\") são, em sua grande maioria, formados por placas de combustível revestidas com alumínio contendo no cerne silicileto de urânio (U3Si2) disperso em matriz de alumínio. Essas placas possuem espessura da ordem de milímetros e comprimentos muito maiores em relação à sua espessura. Elas são dispostas paralelamente no conjunto que forma o elemento combustível, de maneira a formar canais entre elas com poucos milímetros de espessura, por onde escoa o fluido de refrigeração (água leve ou água pesada). Essa configuração, associada à necessidade de um escoamento com altas vazões para garantir o resfriamento das placas em operação, pode gerar problemas de falhas mecânicas das placas de combustível devido às vibrações induzidas pelo escoamento nos canais e, consequentemente, acidentes de proporções graves no caso de velocidade crítica que possa gerar o colapso das placas. Embora não haja ruptura das placas de combustível durante o colapso, as deflexões permanentes excessivas das placas podem causar bloqueio do canal de escoamento no núcleo do reator e levar ao superaquecimento nas placas. Para este trabalho, foram desenvolvidas uma bancada experimental com capacidade para altas vazões volumétricas (Q=100 m3/h) e uma seção de testes que simula um elemento combustível do tipo placa com três canais de resfriamento. A seção de testes foi construída com placas de alumínio e acrílico e foi instrumentada com sensores de deformação, sensores de pressão, um acelerômetro e um tubo de pitot. As dimensões da seção de testes foram baseadas nas dimensões do Elemento Combustível do Reator Multipropósito Brasileiro (RMB), cujo projeto está sendo coordenado pela Comissão Nacional de Energia Nuclear - CNEN. Os experimentos realizados alcançaram o objetivo de chegar à condição de velocidade crítica de Miller com o colapso das placas. A velocidade crítica foi atingida com 14,5 m/s levando a consequente deformação plástica das placas que formam o canal do escoamento. O canal central na entrada da seção de testes apresentou uma abertura de 3 mm em seu centro, causando um grande bloqueio do escoamento nos canais laterais. Este comportamento foi v constatado visualmente durante a desmontagem da seção de testes, ilustrado e discutido na análise de resultados apresentado neste trabalho. O bloqueio dos canais também foi observado por meio de gráficos de queda de pressão e por gráficos das deformações da entrada, centro e saída das placas contra a velocidade média da seção de testes. Observou-se uma queda da resistência hidráulica da seção de testes devido ao aumento da seção transversal de escoamento no canal central e um aumento exponencial das deformações quando da ocorrência da velocidade crítica. Comparativamente, o valor experimental obtido para velocidade crítica na seção de testes foi da ordem de 85% do valor obtido por cálculo com a expressão teórica de Miller. Os experimentos realizados permitiram um melhor entendimento da interação fluido estrutura em elementos de combustível tipo placa como: valores de frequências de vibrações naturais, instabilidade fluido elástica e desenvolvimento de técnicas para a detecção de valores de velocidade crítica.<br>Tese (Doutorado em Tecnologia Nuclear)<br>IPEN/T<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP<br>CNPq:481193/2012-0
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Farkas, I., A. Aszodi, J. Elter, et al. "The European project FLOMIX-R: Description of the experimental and numerical studies of flow distribution in the reactor primary circuit(Final report on WP 3)." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28628.
Full textAbstract:
The flow distribution in the primary circuit of the pressurized water reactor was studied with experiments and Computational Fluid Dynamics (CFD) simulations. The main focus was on the flow field and mixing in the downcomer of the pressure vessel: how the different factors like the orientation of operating loops, the total loop flow rate and the asymmetry of the loop flow rates affect the outcome. In addition to the flow field studies the overall applicability of CFD methods for primary circuit thermal-hydraulic analysis was evaluated based on the CFD simulations of the mixing experiments of the ROCOM (Rossendorf Coolant Mixing Model) test facility and the mixing experiments of the Paks NPP. The experimental part of the work in work package 3 included series of steady state mixing experiments with the ROCOM test facility and the publication of results of Paks VVER-440 NPP thermal mixing experiments. The ROCOM test facility models a 4-loop KONVOI type reactor. In the steady-state mixing experiments the velocity field in the downcomer was measured using laser Doppler anemometry and the concentration of the tracer solution fed from one loop was measured at the downcomer and at the core inlet plane. The varied parameters were the number and orientation of the operating loops, the total flow rate and the (asymmetric) flow rate of individual loops. The Paks NPP thermal mixing experiments took place during commissioning tests of replaced steam generator safety valves in 1987-1989. It was assumed that in the reactor vessels of Paks VVER-440 NPP equipped with six loops the mixing of the coolant is not ideal. For the realistic determination of the active core inlet temperature field for the transients and accidents associated with different level temperature asymmetry a set of mixing factors were determined. Based on data from the online core monitoring system and a separate mathematical model the mixing factors for loop flows at the core inlet were determined. In the numerical simulation part of the work package 3 the detailed measurements of ROCOM tests were used for the validation of CFD methods for primary circuit studies. The selected steady state mixing experiments were simulated with CFD codes CFX-4, CFX-5 and FLUENT. The velocity field in the downcomer and the mixing of the scalar were compared between CFD simulations and experiments. The CFD simulations of full scale PWR included the simulation of Paks VVER-440 mixing experiment and the simulation of Loviisa VVER-440 downcomer flow field. In the simulations of Paks experiments the experimental and simulated concentration field at the core inlet were compared and conclusions made concerning the results overall and the VVER-440 specific geometry modelling aspects like how to model the perforated elliptic bottom plate and what is the effect of the cold leg bends to the flow field entering to the downcomer. With Loviisa simulations the qualitative comparison was made against the original commissioning experiments but the emphasis was on the CFD method validation and testing. The overall conclusion concerning the CFD modelling of the flow field and mixing in the PWR primary circuit could be that the current computation capacity and physical models also in commercial codes is beginning to be sufficient for simulations giving reliable and useful results for many real primary circuit applications. However the misuse of CFD methods is easy, and the general as well as the nuclear power specific modelling guidelines should be followed when the CFD simulations are made.
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Farkas, I., A. Aszodi, J. Elter, et al. "The European project FLOMIX-R: Description of the experimental and numerical studies of flow distribution in the reactor primary circuit(Final report on WP 3)." Forschungszentrum Rossendorf, 2005. https://hzdr.qucosa.de/id/qucosa%3A21689.
Full textAbstract:
The flow distribution in the primary circuit of the pressurized water reactor was studied with experiments and Computational Fluid Dynamics (CFD) simulations. The main focus was on the flow field and mixing in the downcomer of the pressure vessel: how the different factors like the orientation of operating loops, the total loop flow rate and the asymmetry of the loop flow rates affect the outcome. In addition to the flow field studies the overall applicability of CFD methods for primary circuit thermal-hydraulic analysis was evaluated based on the CFD simulations of the mixing experiments of the ROCOM (Rossendorf Coolant Mixing Model) test facility and the mixing experiments of the Paks NPP. The experimental part of the work in work package 3 included series of steady state mixing experiments with the ROCOM test facility and the publication of results of Paks VVER-440 NPP thermal mixing experiments. The ROCOM test facility models a 4-loop KONVOI type reactor. In the steady-state mixing experiments the velocity field in the downcomer was measured using laser Doppler anemometry and the concentration of the tracer solution fed from one loop was measured at the downcomer and at the core inlet plane. The varied parameters were the number and orientation of the operating loops, the total flow rate and the (asymmetric) flow rate of individual loops. The Paks NPP thermal mixing experiments took place during commissioning tests of replaced steam generator safety valves in 1987-1989. It was assumed that in the reactor vessels of Paks VVER-440 NPP equipped with six loops the mixing of the coolant is not ideal. For the realistic determination of the active core inlet temperature field for the transients and accidents associated with different level temperature asymmetry a set of mixing factors were determined. Based on data from the online core monitoring system and a separate mathematical model the mixing factors for loop flows at the core inlet were determined. In the numerical simulation part of the work package 3 the detailed measurements of ROCOM tests were used for the validation of CFD methods for primary circuit studies. The selected steady state mixing experiments were simulated with CFD codes CFX-4, CFX-5 and FLUENT. The velocity field in the downcomer and the mixing of the scalar were compared between CFD simulations and experiments. The CFD simulations of full scale PWR included the simulation of Paks VVER-440 mixing experiment and the simulation of Loviisa VVER-440 downcomer flow field. In the simulations of Paks experiments the experimental and simulated concentration field at the core inlet were compared and conclusions made concerning the results overall and the VVER-440 specific geometry modelling aspects like how to model the perforated elliptic bottom plate and what is the effect of the cold leg bends to the flow field entering to the downcomer. With Loviisa simulations the qualitative comparison was made against the original commissioning experiments but the emphasis was on the CFD method validation and testing. The overall conclusion concerning the CFD modelling of the flow field and mixing in the PWR primary circuit could be that the current computation capacity and physical models also in commercial codes is beginning to be sufficient for simulations giving reliable and useful results for many real primary circuit applications. However the misuse of CFD methods is easy, and the general as well as the nuclear power specific modelling guidelines should be followed when the CFD simulations are made.
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Lismonde, Baudouin. "Champ de vitesse au bord d'attaque et dans le spot laminaire d'un écoulement sur une plaque plane." Grenoble 1, 1987. http://www.theses.fr/1987GRE10074.
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Calcul numerique des champs de vitesse, de pression et de temperature dans la zone pres du bord d'attaque ou il faut utiliser une approximation d'ordre 3 de la couche limite. Mesure des trois composantes de la vitesse de l'ecoulement perturbe par un microjet instantane traversant la couche limite laminaire
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Hill, Michelle Denise. "Damage resistance and tolerance investigation of carbon/epoxy skinned honeycomb sandwich panels." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/10072.
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This thesis documents the findings of a three year experimental investigation into the impact damage resistance and damage tolerance of composite honeycomb sandwich panels. The primary area of work focuses on the performance of sandwich panels under quasi-static and low-velocity impact loading with hemispherical and flat-ended indenters. The damage resistance is characterised in terms of damage mechanisms and energy absorption. The effects of varying the skin and core materials, skin thickness, core density, panel boundary conditions and indenter shape on the transverse strength and energy absorption of a sandwich panel have been examined. Damage mechanisms are found to include delamination of the impacted skin, core crushing, limited skin-core de bonding and top skin fibre fracture at high loads. In terms of panel construction the skin thickness is found to dominate the panel strength and energy absorption with core density having a lesser influence. Of the external factors considered the indenter noseshape has the largest effect on both failure load and associated damage area. An overview of existing analytical prediction methods is also included and the most significant theories applied and compared with the experimental results from this study. The secondary area of work expands the understanding obtained from the damage resistance study and assesses the ability of a sandwich panel to withstand in-plane compressive loading after sustaining low-velocity impact damage. The importance of the core material is investigated by comparing the compression-after-impact strength of both monolithic carbon-fibre laminates and sandwich panels with either an aluminium or nomex honeycomb core. The in-plane compressive strength of an 8 ply skinned honeycomb sandwich panel is found to be double that of a 16 ply monolithic laminate, with the type of honeycomb also influencing the compressive failure mechanisms and residual compressive strength. It is concluded that under in-plane loading the stabilising effect of the core opposes the de-stabilising effect of any impact damage.
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Fu, Li. "Rhéologie des polymères dans les contacts confinés : tribologie des interfaces étudiées par un nouveau dispositif couplant FRAPP et nanotribologie." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE030/document.
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Ce travail porte sur le développement d’une nouvelle technique expérimentale dédiée à l’étude de la rhéologie mise en jeux lors du glissement d’une pointe rigide sur une surface de polymère. Ce travail s'est déroulé progressivement de l'échelle mésoscopique vers l'échelle nanométrique. Pour cette dernière, la zone ciblée est la zone interfaciale confinée et cisaillée.Pour mettre en évidence les comportements de la zone cohésive, nous avons étudié un système de réseaux interpénétrés de polymères (RIPs) CR39-PMMA. Grâce à leurs propriétés ajustables, nous pourrons utiliser les RIPs sont utilisés comme substrat pour étudier la zone interfaciale en variant facilement les paramètres rhéologiques.Pour étudier les propriétés de la zone interfaciale, des couches phospholipidiques de DSPC ont été choisies comme matériau modèle. Leurs structures ont été étudiées par la réflectivité spéculaire de neutron. Nous montrons que la structure des couches supportées de DSPC est robuste, et le taux d’humidité́ relative joue un rôle important sur la structure. Les essais de glissement sur des couches de DSPC ont permis de relever les influences des paramètres mécaniques et environnementaux sur la contrainte de cisaillement Le développement du NanoTribo-FRAPP permet de caractériser le cisaillement des couches de DSPC sur une lame de verre, tout en mesurant la vitesse d’écoulement locale des couches moléculaires nanométriques. Nous pouvons ainsi estimer les plans de glissement en fonction de la vitesse<br>This work deals with the development of a new experimental technique and its application to study the rheology of a highly confined and sheared interfacial zone involved in the sliding of a rigid tip on a polymer suface. This tribological work has been conducted gradually from the mesoscopic scale to the nanoscale.To highlight the behavior of the cohesive zone, we studied an interpenetrating polymer network system (INPs) CR39-PMMA. Thanks to their adjustable properties, we may use the INPs as a substrate to study the interfacial zone by easily varying the rheological parameters.To study the rheological properties in the interfacial zone, the phospholipid layers of DSPC have been chosen as model material. The structures have been studied by the neutron reflectivity experiments. We show that the structure of supported layers of DSPC is robust, and the relative humidity plays a key role on it. Sliding tests on the DSPC layers reveals the influences of mechanical and environmental parameters on the shear stress. The development of NanoTribo-FRAPP allows to characterize the shear conditions of DSPC layers, with the measurements of local velocity of these of nanoscale molecular layers. This gives us access to estimate the slip planes as a function of imposed velocity
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Viglioni, Humberto Henrique de Barros. "Dinâmica de vórtices em superfícies com aplicações ao problema de dois vórtices no toro plano." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/45/45132/tde-03042017-161053/.
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Este trabalho apresenta uma dedução das equações para a dinâmica de vórtices em superfícies utilizando argumentos físicos e balanço de momento, obtendo o resultado já conhecido devido a Boatto/Koiller e Hally. Na primeira parte, elaboramos uma releitura da contribuição de diversos pesquisadores incluindo, além dos já citados, o trabalho de Marchioro e Pulvirenti sobre a propriedade de localização para a equação de Euler e também a importante contribuição de Flucher e Gustafsson no que diz respeito à determinação da função de Green e função de Robin hidrodinâmicas em domínios do plano. Na segunda parte revisamos o problema da dinâmica de um traçador passivo induzida por um vórtice no disco unitário e estendemos para o caso com vorticidade de fundo constante. Por fim, analisamos a dinâmica de dois vórtices no toro plano, a qual reduz-se ao estudo da dinâmica do centro de vorticidade com hamiltoniana dada pela função de Green. É feita uma descrição das bifurcações das curvas de níveis desta hamiltoniana com respeito a variações do parâmetro modular. Mostramos que o campo hamiltoniano em questão é preservado por biholomorfismos e, portanto, o espaço dos parâmetros pode ser reduzido ao espaço de Moduli do toro plano. Mudanças dentro de uma mesma classe de equivalência por biholomorfismos podem alterar apenas a classe de homotopia das curvas de nível.<br>In this thesis the equations for the motion of vortices on Riemannian surfaces is studied. Using conservation of momentum and physical arguments, the classical equations of Hally and Boatto/Koiller are recovered. Then the localization result for the Euler\'s equation with flat metric (Marchioro and Pulvirenti) and the determination of the Green\'s and Robin\'s functions on plane domains are revisited in the context of Riemannian surfaces. On a second part of the thesis two examples are analyzed. At first the dynamics of a passive tracer in the unit disk on the flat plane with constant background vorticity. At second the dynamics of two vortices on flat tori. This last system is integrable. The dynamics is determined by the level sets of the Green\'s function which depends on the modular parameter of the torus. The full bifurcation diagram of the system as a function of the module parameter is determined.
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Kokkalis, Efstratios. "Fluid dynamic assessments of spiral flow induced by vascular grafts." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/5b96492f-983f-4baa-8e48-20da6939e65c.
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Peripheral vascular grafts are used for the treatment of peripheral arterial disease and arteriovenous grafts for vascular access in end stage renal disease. The development of neo-intimal hyperplasia and thrombosis in the distal anastomosis remains the main reason for occlusion in that region. The local haemodynamics produced by a graft in the host vessel is believed to significantly affect endothelial function. Single spiral flow is a normal feature in medium and large sized vessels and it is induced by the anatomical structure and physiological function of the cardiovascular system. Grafts designed to generate a single spiral flow in the distal anastomosis have been introduced in clinical practice and are known as spiral grafts. In this work, spiral peripheral vascular and arteriovenous grafts were compared with conventional grafts using ultrasound and computational methods to identify their haemodynamic differences. Vascular-graft flow phantoms were developed to house the grafts in different surgical configurations. Mimicking components, with appropriate acoustic properties, were chosen to minimise ultrasound beam refraction and distortion. A dual-beam two-dimensional vector Doppler technique was developed to visualise and quantify vortical structures downstream of each graft outflow in the cross-flow direction. Vorticity mapping and measurements of circulation were acquired based on the vector Doppler data. The flow within the vascular-graft models was simulated with computed tomography based image-guided modelling for further understanding of secondary flow motions and comparison with the experimental results. The computational assessments provided a three-dimensional velocity field in the lumen of the models allowing a range of fluid dynamic parameters to be predicted. Single- or double-spiral flow patterns consisting of a dominant and a smaller vortex were detected in the outflow of the spiral grafts. A double- triple- or tetra-spiral flow pattern was found in the outflow of the conventional graft, depending on model configuration and Reynolds number. These multiple-spiral patterns were associated with increased flow stagnation, separation and instability, which are known to be detrimental for endothelial behaviour. Increased in-plane mixing and wall shear stress, which are considered atheroprotective in normal vessels, were found in the outflow of the spiral devices. The results from the experimental approach were in agreement with those from the computational approach. This study applied ultrasound and computational methods to vascular-graft phantoms in order to characterise the flow field induced by spiral and conventional peripheral vascular and arteriovenous grafts. The results suggest that spiral grafts are associated with advanced local haemodynamics that may protect endothelial function and thereby may prevent their outflow anastomosis from neo-intimal hyperplasia and thrombosis. Consequently this work supports the hypothesis that spiral grafts may decrease outflow stenosis and hence improve patency rates in patients.
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Čamaj, Peter. "Stabilizační a autopilotní systém pro RC model letadla." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-221051.
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The master thesis deals with design and realization of stabilizing and autopilot system, which is used in radio controlled model planes. The thesis contains a proposal of hardware platform, which is able to control the plane model based on data measured from a sensor system. Moreover, this thesis describes a software implementation of individual modules, which is measured the onboard values. The basic principles of stabilization and autonomous flight control are also summarized. In conclusion, the system is subjected to flight tests.
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Tounsi, Rami. "Comportement des structures en nids d'abeilles sous sollicitations dynamiques mixtes compression/cisaillement et effet de l'orientation des cellules." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2014. http://tel.archives-ouvertes.fr/tel-01002421.
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Les nids d'abeille d'aluminium combinent légèreté et grande capacité d'absorption d'énergie. Ils sont alors de plus en plus utilisés dans les secteurs du transport (automobile, aéronautique ...) pour contribuer conjointement à l'allègement structural et à la sécurité. Dans cette thèse, le comportement à l'écrasement des nids d'abeille est étudié en tenant compte de l'effet combiné de l'angle d'orientation dans le plan des cellules, de l'angle de chargement et de la vitesse de sollicitation, que la littérature ne relate pas. Un dispositif de chargement mixte compression/cisaillement est conçu pour mener l'étude expérimentale. L'analyse des résultats porte sur le pic initial d'effort, le plateau d'effort, ainsi que sur les modes de déformation. Les résultats montrent une augmentation de la résistance sous sollicitation dynamique dépendante de l'angle de chargement Ψ. Elle devient moins significative quand l'angle de chargement augmente jusqu'à atteindre un angle critique. Pour Ψ > Ψcritique, les réponses quasi-statiques sont même plus élevées que les réponses dynamiques. Une étude numérique est alors entreprise. Elle permet de comprendre ce phénomène qui est imputé aux mécanismes de déformation locaux des cellules. Les résultats numériques montrent également que l'effet de l'angle d'orientation □ dans le plan est plus prononcé sur la force tangentielle que sur la force normale, que cela influence également les modes d'effondrement et donc la réponse mécanique. Ces simulations numériques, couplées aux résultats expérimentaux, permettent alors de dissocier les composantes normale et tangentielle de la réponse des nids d'abeille et d'identifier les paramètres d'un critère macroscopique de résistance exprimé en fonction de la vitesse d'impact, de l'angle de chargement et de l'angle d'orientation dans le plan. Finalement, dans le but de réduire le coût des simulations numériques, un modèle élément fini (EF) réduit basé sur un critère de périodicité tenant compte de l'angle d'orientation dans le plan est proposé et son domaine de validité est évalué.
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Guo, Bowen. "Superresolution Imaging Using Resonant Multiples and Plane-wave Migration Velocity Analysis." Diss., 2017. http://hdl.handle.net/10754/625420.
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Seismic imaging is a technique that uses seismic echoes to map and detect underground geological structures. The conventional seismic image has the resolution limit of λ/2, where λ is the wavelength associated with the seismic waves propagating in the subsurface. To exceed this resolution limit, this thesis develops a new imaging method using resonant multiples, which produces superresolution images with twice or even more the spatial resolution compared to the conventional primary reflection image.
A resonant multiple is defined as a seismic reflection that revisits the same subsurface location along coincident reflection raypath. This reverberated raypath is the reason for superresolution imaging because it increases the differences in reflection times associated with subtle changes in the spatial location of the reflector. For the practical implementation of superresolution imaging, I develop a post-stack migration technique that first enhances the signal-to-noise ratios (SNRs) of resonant multiples by a moveout-correction stacking method, and then migrates the post-stacked resonant multiples with the associated Kirchhoff or wave-equation migration formula. I show with synthetic and field data examples that the first-order resonant multiple image has about twice the spatial resolution compared to the primary reflection image.
Besides resolution, the correct estimate of the subsurface velocity is crucial for determining the correct depth of reflectors. Towards this goal, wave-equation migration velocity analysis (WEMVA) is an image-domain method which inverts for the velocity model that maximizes the similarity of common image gathers (CIGs). Conventional WEMVA based on subsurface-offset, angle domain or time-lag CIGs requires significant computational and memory resources because it computes higher dimensional migration images in the extended image domain. To mitigate this problem, I present a new WEMVA method using plane-wave CIGs. Plane-wave CIGs reduce the computational cost and memory storage because they are directly calculated from prestack plane-wave migration, and the number of plane waves is often much smaller than the number of shots. In the case of an inaccurate migration velocity, the moveout of plane-wave CIGs is automatically picked by a semblance analysis method, which is then linked to the migration velocity update by a connective function. Numerical tests on synthetic and field datasets validate the efficiency and effectiveness of this method.
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Jiao, Junru 1959. "Residual migration velocity analysis in the plane wave domain : theory and applications." 2001. http://hdl.handle.net/2152/10600.
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Yang, Che-Ming, and 楊哲銘. "Applications of velocity-dependent friction law on catastrophic plane failure and accretionary wedge." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/9837rn.
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博士<br>國立中央大學<br>應用地質研究所<br>105<br>The friction coefficient of a fault gouge or sliding plane dominates the fault dynamics and kinematics of a landslide. However, the friction coefficient and behavior of fault gouges or sliding planes are influenced by the slip rate, displacement, normal stress, pore pressure, water content, temperature, mineral content, particle size, and shear structure. We performed a series of rotary shear tests under different experimental conditions from low to high velocity to establish the velocity-dependent friction law. Accordingly, the friction coefficient can be evaluated by varying the slip rate and accumulated slip displacement. This study presents two applications of the velocity-dependent friction law, a kinematic analysis of catastrophic planar failure and an estimation of the strength of the detachment fault of the accretionary wedge. The first target is the famous planar failure of Tsaoling landslide, Taiwan, which was triggered by the 1999 Chi-Chi earthquake. We adopted Newmark displacement analysis with velocity-displacement dependent friction law to reproduce the kinematic history of the Tsaoling landslide, considering the phases of initiation, acceleration, collision, and deposition. For the second application, we present a modified critical taper model with nonlinear Hoek-Brown failure criterion and utilize field investigations and laboratory tests to estimate the wedge strength in western central Taiwan. The slip velocity dependent friction coefficient of the detachment fault can be obtained via a series of rotary shear tests with a wide slip rate range. Consequently, the rotary shear test and velocity-dependent friction law can be applied successfully to quantify the kinematics of the catastrophic landslide and the critical taper angle of accretionary wedge, even as their temporal and spatial scales are extremely different.
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Huang, Yu-Chih, and 黃有志. "Site Effect and Near Surface S Wave Velocity Structure in Lan-Yang Plain." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/10227474040060202164.
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碩士<br>國立中央大學<br>地球物理研究所<br>91<br>The purpose of this study is trying to understand the site effect and to compute near surface S wave velocity structure of the Lan-Yang plain. We used very dense microtremor measurements to study the site effect, and used portable seismic array to estimate the near surface sediment''s S wave velocity structure.
In this study, we performed 354 microtremor measurements, and analyzed site effect by applying single station spectral ratio method (Nakamura, 1989). After that, we conducted 9 portable seismic arrays. The analysis procedures can be categorized as (1) Frequency- Wavenumber analysis to get the dispersion curve, (2) to search the good velocity models using genetic algorithm, and (3) to refine the SURF and GA searched models using traditional surface wave inversion technique.
From the predominant frequency of microtremor measurement, we can figure out the alluvium thickness become thicker toward the sea. But there were some higher region (thinner alluvium) beside the east of I-lan and Lotung cities, and north of Lan-Yang River cutlet. The portable seismic arrays also showed similar results. This research result was slightly different from previous study.
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Song-Nan, Tsau, and 曹松楠. "The Relationship Between Ultrasonic Velocity and Metallography of Boiler Tube of Power Plane." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/22182245601002509084.
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碩士<br>國立臺灣科技大學<br>機械工程研究所<br>84<br>For developing new evaluation technology of deteriation of
boiler tube the relationships between ultrasonic velocity and
deterioration of boiler tube must be find. In this study, the
image analysis technology was used to quantify metallography
characteristics of new, creeping tested & used boiler tubes
that were cutted from characteristics (velocity & attenuation)
and hardness was tested,too.TPC Da-Lin power station.
Ultrasonic the experiment results,the relationships between
ultrasonic velocity change, From metallography characteristics
and deteriorated degree was more reliable than ultrasonic
attenuation.
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Chen, Mei-Ling, and 陳美伶. "Sediment Velocity Structures in the Taiwan Strait and the Coastal Plain of west Taiwan." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/05196469270688784417.
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碩士<br>國立中央大學<br>地球物理研究所<br>95<br>The method of reflection seismic imaging displays subsurface structures in time rather than in depth. One therefore needs to know the 3-D distribution of subsurface velocity in order to convert seismic time into depth and obtain 3-D subsurface depth structures. I use borehole and seismic data to compute a 3-D sediment velocity structure in the Taiwan Strait and the coastal plain in west Taiwan by using V0-k method. The V0-k method assumes that velocity increases with increasing depth in a linear form, in which V0 is the initial velocity at the seabed or on the ground surface, and k represents the rate of increase of the velocity with increasing depth. Fitting velocity with depth to a linear form for each data set obtains V0 (intercept) and k (slope) pairs, and gridding these values obtains the spatial distribution of V0 and k. The lateral variation of V0 reflects sediment characteristics with lower values in the basin and higher values in the western foothills. The variation of k correlates to the lithology difference and lateral structural variation. The value of k is exceptionally high in the areas of hardly compactible basement highs. Parameters of V0 and k were gridded in a 3-D depth volume. Comparing the velocity depth structures to seismic images, one finds that (1) the vertical velocity variation is mainly controlled by burial compaction of sediments; (2) the lateral velocity variation is caused by stratal offset resulted from major normal or reverse faulting; and (3) the isovelocity curves shown on cross-sections may reflect the geometry of the basement structure. Finally, I use the drilled depths of the Oligocene breakup unconformity (generally < 4 km in depth) and its corresponding depths as converted from seismic data and using the proposed velocity model to test the validity of the 3-D velocity model. The comparison yields a value of 4.78% of mean percentage error between drilled and predicted depths, indicating that the proposed velocity model predicts subsurface velocity reasonably well down to, at least, 4 km in depth.
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Su, Chao-wei, and 蘇超偉. "Velocity and temperature distributions of turbulent plane jet interaction with the nonlinear oppositive progressive wave." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/51758174594641110236.
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碩士<br>國立中山大學<br>海洋環境及工程學系研究所<br>98<br>The present extends analytical results obtained by Hwung et al. (1981) and considers non-linearity of waves to study variation horizontal velocity, temperature distribution induced by interaction of 2-D plane jet and waves. On the steady state, the nonlinear wave is considered as external force in motion equations, property of momentum conservation of jet flow, and radiation stress are applied to analyze interaction of waves- jet flow in arbitrary profile. The scale function ε1α1(x), ε2α2(x) between variation function f (x,y)and velocity distribution can also be obtained. The non-dimensional theoretical solution is also helpful to estimate characteristics in the physical field. The momentum equation and velocity distribution of interaction without property of temperature diffusion are employed to find variation of temperature in the central axis and temperature distribution for arbitrary sections.
Based on experiment and theory obtained by Hwung et al(1981), it is found that time-averaged horizontal velocity and temperature bath are Gaussian distribution, coefficient of horizontal velocity, and temperature distribution are 0.105, 0.148, respectively. In the present, two coefficients considered as non-linearity of waves c1=0.119 and c2=0.151 are determined. In other words, it is shown that exact solution and boundary effect included non-linearity of waves is related to velocity of jet flow, wave periods, relative depth and steepness of waves.
Comparing with experiment indicated analytical solution of the present for MSE is well conform to known experimental results and better than linear results obtained by Huang et al.(1981). The influence due to interaction of 2-D turbulent jet flow and Stokes waves can be obtained by using dimension analysis. Moreover, variation inside the flow also can be estimated.
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Pan, Min-yan, and 潘旻諺. "Ultrasonic Estimation of Vector Blood Velocity using Speckle Tracking with Coherent Plane Wave Compounding Imaging." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/83969428745442844327.
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碩士<br>國立臺灣科技大學<br>電機工程系<br>98<br>Doppler technique is commonly used in medical ultrasound system. However, conventional Doppler is limited by the flow angle and the maximum detectable velocity. This research was designed to combine the high frame rate imaging system and the speckle tracking technique to provide accurate estimation of the vector velocity. The high accuracy of speckle tracking technique depends on high image quality and high frame rate. In this study, we investigate the coherent plane wave compounding imaging approach (CPWC) to improve the efficacy of blood velocity estimation in speckle tracking technique. In plane wave excitation, the ultrasound is not focused during the transmissions to increase the frame rate at the cost of degraded image quality. By compounding coherently the images obtained with several plane waves with different angles, both the image quality and SNR can be improved. It is also combined with the recursive technique to reduce the acquisition time by providing several high resolution images with different features for speckle tracking. This will benefit the estimation accuracy in flow imaging and elastography. Moreover, the continuous flow image data will also help the design of the wall filter to separate the blood flow from tissue.
The result in this study indicates that the STD and BIAS performance of the lateral velocity component tracking of CPWC in any Doppler angles is better than Single plane wave excitation approach (SPWE). The STD performance of the lateral velocity component tracking will decrease while the axial velocity component increases. Although the STD performance of the axial velocity component tracking of CPWC in any Doppler angles is still better than SPWE, the BIAS performance is inferior due to the point-spread-function shift by the axial movement of the imaged target. At the same time, the BIAS performance will decrease while the axial velocity component increases between the compounded images.
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Lin, Che-Min, and 林哲民. "Shallow velocity structure, site effect and 3D seismic wave simulation of the western plain of Taiwan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/7394aq.
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博士<br>國立中央大學<br>地球物理研究所<br>97<br>The shallow S-wave velocity structures and site effect of the western plain of Taiwan were respectively estimated by the microtremor array measurements and dense station measurements. The complete 3D velocity model was constructed with the shallow structures to simulate the seismic wave propagation in the western plain.
Seven microtremor arrays estimated the S-wave velocity structures from the surface to a depth of 3 km. The velocities at near-surface were very slow and increased gradually. And several interfaces with substantial S-wave velocity variations were found. The depths of the last two main interfaces in deeper part corresponded to the tops of the Pliocene and upper Miocene formations, respectively. Further, the average S-wave velocities of the Plio-Pleistocene, Pliocene, and Miocene formations were estimated in this study. The existence of the Peikang Basement High affects the features of these two interfaces and the shallow structures of the western plain. The H/V ratios of microtremor apparently amplify in the frequency range 1.0~2.0Hz in the center of western plain. The eastern part of western plain showed the higher predominant frequencies or the non-amplified effect of rock site. But, the area along the coast exhibits the mixed predominant frequency because the velocity variations of deep alluvium are gradual with some local thin structures in surface. Based on that the H/V ratios confirme with the theoretic SH wave transfer functions, the GA-Haskell method was developed to simulate H/V ratios and estimate shallow velocity structures. The capability of this method was tested and confirmed in the microtremor research of Hanoi region, Vietnam. The shape of basement and velocity structures in Hanoi region were figured out by the GA-Haskell method. Unfortunately, the complex site effect of the western plain is not suitable for the analyses of GA-Haskell method.
The active sources of TAIGER in western plain excited the strong surface waves in the low velocity layers of near-surface. And the slow surface waves can be simulated based on the shallow velocity model estimated by the microtremor array. The three main interfaces indicated by the microtremor array and Vs30 were combined with the 3D tomography velocity structure to constructe the complete 3D velocity model of the western plain. Finally, the parallel 3D PSM/FDM method were used to simulate the seismic waveforms of 1993 Tapu and 1998 Rueyli earthquakes. The observed waveforms of the western plain were reproduced by the simulations. The characters of seismic wave propragation and the surface waves were simulated based on the complete 3D velocity model. The shallow S-wave velocity model generates the longer and more complex seismic waveform in the western plain of Taiwan.
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Wang, K. D., and 王凱達. "Low Velocity Impact Response of Plain-Weaved and Double-Walled GFRP Composites Utilized A Drop-Weight Impact Tower." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/24594329712814273314.
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碩士<br>國立成功大學<br>航空太空工程學系<br>88<br>The purpose of this thesis is to study the impact response and damage development of plain-weaved and Double-wall GFRP composites. The plain-weaved contain two different layers which are 8-plys and 11-plys, and double-walled include two types which are Parabeam-3mm and Parabeam- 6mm. We are using a Drop-Weight Impact Tower with a hemispherical tup in ascending impact Energy to do a series experiments for four laminates respectively. Utilizing the force Sensor (PCB) and data acquisition system (NI), we can get the impact force and absorbed energy histories in different impact energy. By the information of these curves, we can realize the condition of impact deformation、damage and energy absorbed during the impact. With comparing the relationship between the impact force and impact kinetic energy of each laminate, it could become the basis to estimate the ability of impact resistance.
In this thesis, we also introduce the “Energy-Balance Model” which could predict the impact force by balancing the impact kinetic energy of the impactor and the sum of strain energies due to each deformation. From the experiments, we know it should add the damage energy to the energy-balance equation to conform with really situations. Finally, we use the commercial finite element code MARC to simulate the behavior of impact. For the relative low velocity cases, the impact force and the velocity of impactor during impact are well captured for the plain-weaved.
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Li, Zong-Heng, and 李宗恆. "Velocity and temperature distributions of turbulent plane jet interaction with the nonlinear oppositive progressive gravity wave and ocean current." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/97288184079624127190.
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碩士<br>國立中山大學<br>海洋環境及工程學系研究所<br>99<br>The variation of velocity and temperature distribution in arbitrary profile along the centerline in turbulent which encounters non-linearity regular progressive gravity wave and steady uniform flow right in front are investigated analytically and verified by existing experiments. Firstly, the action of periodic waves and current are incorporated into the equation of motion as an external force and applied radiation stress for evaluating the velocity distribution over arbitrary lateral cross section. Based on the momentum exchange after the interaction between turbulent plane jet and oppositive non-linearity wave and uniform flow, the physical characteristics of jet-wave and current are able to be determined theoretically.
Secondly, there are critical sections in both velocity and temperature transport processes when the turbulent plane jet influenced by wave and current motion. Fluctuating function will be close to infinity, is the order of wave sharpness; Average velocity for every wave period along the centerline approach to zero, That’s thanks to the momentum of plane jet is extruded by the momentum of wave and current, Beyond the critical section, characteristics of the jet is no longer existing, such phenomena mean that only the wave and current dominating. Velocity and temperature distribution in the zone of flow developed are Gaussian curve, as has been measured in experiment. The momentum extrusion of counter flow in jet is significant in the deep water and small wave; The velocity distribution coefficient is changing with the increasing of counter flow velocity, owing to the entrainment effect, and the potential core will reducing with the increasing of counter flow velocity.
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Fu, Liou Jia, and 劉家輔. "Development of a Arterial Wall Abnormalities Sensor System Base on Pulse Wave Velocity, Resonant Bandwidth and Three Dimension Phase plane." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/74934576394494155699.
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碩士<br>東南科技大學<br>電機工程研究所<br>102<br>The phenomenon of pulse beat is generated when heart press blood to vascular. Through the pulse beating can understand the function of the heart and blood vessels elastic. Typical pulse wave is mainly composed of P-wave and R-wave, its waveform is a regular oscillatory behavior. However, the actual pulse wave appears irregular oscillation due to abnormal of the physiological.This paper attempts to summarize the relationship between physiologic abnormalities and the pulse wave oscillation. In order to find another way to determine the physiological abnormalities, we construct pulse wave velocity, resonant bandwidth and three dimension phase plane to determine abnormal occurrence. This research also propose a new type of Chinese pulse diagnosis acquisition system, we use conductive polymer as a material made of sensors, because it has a soft, plastic characteristics can be made of non-rigid pulse diagnosis instrument.Finally,We use self-developed human-machine interface to perform pulse diagnosis signal capture and analysis.
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Краснокутський, Юрій Вікторович. "Аналіз ефективності роботи блоку ЗАЕС від температури води охолодження конденсаторів парових турбін". Магістерська робота, 2020. https://dspace.znu.edu.ua/jspui/handle/12345/3763.
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Краснокутський Ю. В. Аналіз ефективності роботи блоку ЗАЕС від температури води охолодження конденсаторів парових турбін : кваліфікаційна робота магістра спеціальності 144 "Теплоенергетика" / наук. керівник А. С. Мних. Запоріжжя : ЗНУ, 2020. 88 с.<br>UA : Робота викладена на 88 сторінках друкованого тексту, містить 7 таблиць, 11 рисунків. Перелік посилань включає 41 джерел з них на іноземній мові 3. В роботі наведено опис роботи блоку ЗАЕС та конденсаційної парової турбіни, виконано детальний розрахунок параметрів пари по ступеням парової турбіни. Проаналізовано шляхи підвищення ефективності роботи блоку ЗАЕС від температури води охолодження конденсаторів парових турбін.<br>EN : The work is presented on 88 pages of printed text, contains 7 tables,11figures.The list of references includes 41sources, 3 of them in foreign language.The ways of increase of efficiency of operation of the ZNPP unit from water temperature of cooling of condensers of steam turbines arе analyzed. The existing dangerous and harmful factors that occur at NPPs and can affect service personnel are analyzed.
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Veloso, Simão Pedro Matos. "Estudo experimental para a otimização e o controlo automático de uma cortina de ar." Master's thesis, 2016. http://hdl.handle.net/10316/39008.
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Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra<br>Sempre que se abre uma porta de acesso a um espaço climatizado ou a uma câmara
frigorífica/refrigeração, ocorrem trocas de ar e de energia através dessa porta. Com o intuito de
reduzir as perdas energéticas para o ambiente exterior, recorre-se frequentemente ao uso de
dispositivos de cortinas de ar, utilizadas como barreiras aerodinâmicas. Estes equipamentos,
quando corretamente dimensionados, são capazes de reduzir as trocas de energia em mais de
50%, e quando comparados com outros dispositivos, possuem a vantagem de permitir o livre
acesso aos espaços climatizados/refrigerados.
Esta dissertação possui como objetivo, em primeiro lugar, o estudo experimental de um
equipamento de cortina de ar de jato plano vertical e descendente, com vista à determinação da
velocidade ótima do jato (que permite atingir a eficiência máxima de vedação), para diferentes
configurações paramétricas; em seguida, pretende-se desenvolver e testar um sistema de controlo
automático para a cortina de ar, com a capacidade de adaptação da velocidade do jato de ar às
condições variáveis de cada lado da porta de acesso. Para tal, utilizou-se uma instalação
laboratorial, constituída por duas salas contíguas de dimensões semelhantes, ligados por uma
porta sobre a qual se encontra instalado um dispositivo de cortina de ar. Para o controlo e
especificação das temperaturas ambiente nos espaços utilizou-se, na “sala fria”, uma unidade de
refrigeração com o grupo evaporador/ventilador e um termoconvetor elétrico na “sala quente”,
para simular o ambiente exterior de uma câmara refrigerada.
De forma a avaliar a capacidade de a cortina de ar minimizar as trocas de energia entre os dois
espaços, i.e., a fuga de frio da sala refrigerada, efetuaram-se ensaios experimentais com a cortina
de ar acionada, tomando como referência os resultados dos ensaios com a cortina desligada, para
cada configuração paramétrica. Neste estudo evidenciou-se que a velocidade ótima do jato
depende significativamente da altura da porta e da diferença de temperatura entre as salas. Os
resultados obtidos contribuíram para a proposta de uma correlação empírica para a velocidade
ótima do jato em função destes dois parâmetros. Com base no estudo experimental, foi
desenvolvido e testado um dispositivo eletrónico de controlo automático da velocidade do jato
que permite que a cortina de ar se adapte autonomamente à variação das condições ambiente em
simultâneo com um funcionamento próximo da eficiência máxima de vedação. Os ensaios
realizados comprovaram os benefícios deste sistema, ainda que seja necessário efetuar melhorias.<br>Every time a door is opened to access a climatized space or a freezing/refrigeration chamber, air
and energy exchanges occur across the doorway. In order to reduce the energy losses to the
outdoor ambient, air curtains are frequently used to act as aerodynamic barriers. When correctly
dimensioned, these equipments are capable of reducing the energy exchanges over 50%, and
when compared to other devices they have the advantage of allowing free access to climatized
or refrigerated spaces.
The main objectives of the present dissertation are, first, to experimentally study a downward
vertically-blowing air curtain device (ACD) aiming to determine the optimal jet velocity (that
allows for the maximum sealing efficiency of a refrigerated chamber) in different parametric
configurations; and then, to develop and test an automatic control system for the ACD that might
adapt the jet velocity to variable conditions from each side of the doorway. For these purposes,
a laboratorial set-up was used, composed by two contiguous rooms with similar dimensions,
which are connected by a doorway having an air curtain device installed on top of it. For the
control and specification of the ambient temperatures in the rooms, a refrigeration unit was used
in the “cold room” with the evaporator/ventilator group, and an electric fan coil in the “warm
room”, which simulates the outdoor ambient of a refrigerated chamber.
In order to evaluate the air curtain capacity of minimizing the energy exchanges between the two
spaces, i.e., the cold leakage from the refrigerated room, experimental tests were conducted with
the ACD blowing, taking as a reference the results of the corresponding tests with the curtain
turned off, for each parametric configuration. In this study, it was clear that the jet optimum
velocity is significantly dependent on the doorway height and on the temperature difference
between the two sides. The obtained results contributed to the proposal of an empiric correlation
for the jet optimum velocity as a function of those two parameters. Based on this correlation, an
electronic device was developed for the automatic control of the jet velocity, allowing the air
curtain to adapt itself to variable ambient conditions while permanently work close to its optimal
sealing efficiency. The tests conducted proved the benefits of this feature, although indicating
the need of some improvements.