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Graziano, Laurent. "An axial polynomial expansion and acceleration of the characteristics method for the solution of the Neutron Transport Equation." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS389/document.
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L'objectif de ce travail de thèse est le développement d'une approximation polynomiale axiale dans un solveur basé sur la Méthode des Caractéristiques. Le contexte, est celui de la solution stationnaire de l'équation de transport des neutrons pour des systèmes critiques, et l'implémentation pratique a été réalisée dans le solveur "Two/three Dimensional Transport" (TDT), faisant partie du projet APOLLO3®. Un solveur MOC pour des géométries en trois dimensions a été implémenté dans ce code pendant un projet de thèse antécédent, se basant sur une approximation constante par morceaux du flux et des sources des neutrons. Les développements présentés dans la suite représentent la continuation naturelle de ce travail. Les solveurs MOC en trois dimensions sont capables de produire des résultats précis pour des géométries complexes. Bien que précis, le coût computationnel associé à ce type de solveur est très important. Une représentation polynomiale en direction axiale du flux angulaire des neutrons a été utilisée pour réduire ce coût computationnel.Le travail réalisé pendant cette thèse peut être considéré comme divisé en trois parties: transport, accélération et autres. La première partie est constituée par l'implémentation de l'approximation polynomiale choisie dans les équations de transmission et de bilan typiques de la Méthode des Caractéristiques. Cette partie a aussi été caractérisée par le calcul d'une série de coefficients numériques qui se sont révélés nécessaires afin d'obtenir un algorithme stable. Pendant la deuxième partie, on a modifié et implémenté la solution des équations de la méthode d'accélération DPN. Cette méthode était déjà utilisée pour l'accélération et des itérations internes et externes dans TDT pour les solveurs deux et trois dimensionnels avec l'approximation des flux plat, quand ce travail a commencé. L'introduction d'une approximation polynomiale a demandé plusieurs développements numériques regardant la méthode d'accélération. Dans la dernière partie de ce travail on a recherché des solutions pour un mélange de différents problèmes liés aux premières deux parties. En premier lieux, on a eu à faire avec des instabilités numériques associées à une discrétisation spatiale ou angulaire pas suffisamment précise, soit pour la partie transport que pour la partie d'accélération. Ensuite, on a essayé d'utiliser différentes méthodes pour réduire l'empreinte mémoire des coefficients d'accélération. L'approche qu'on a finalement choisie se base sur une régression non-linéaire au sens des moindres carrés de la dépendance en fonction des sections efficaces typique de ces coefficients. L'approche standard consiste dans le stockage d'une série de coefficients pour chaque groupe d'énergie. La méthode de régression permet de remplacer cette information avec une série de coefficients calculés pendant la régression qui sont utilisés pour reconstruire les matrices d'accélération au cours des itérations. Cette procédure ajoute un certain coût computationnel à la méthode, mais nous pensons que la réduction de la mémoire rende ce surcoût acceptable.En conclusion, le travail réalisé a été concentré sur l'application d'une simple approximation polynomiale avec l'objectif de réduire le coût computationnel et l'empreinte mémoire associées à un solveur basée sur la Méthodes des Caractéristiques qui est utilisé pour calculer le flux neutroniques pour des géométries à trois dimensions extrudées. Même si cela ne constitue pas une amélioration radicale des performances, l'approximation d'ordre supérieur qu'on a introduit permet une réduction en termes de mémoire et de temps de calcul d'un facteur compris entre 2 et 5, selon le cas. Nous pensons que ces résultats constitueront une base fertile pour des futures améliorationsThe purpose of this PhD is the implementation of an axial polynomial approximation in a three-dimensional Method Of Characteristics (MOC) based solver. The context of the work is the solution of the steady state Neutron Transport Equation for critical systems, and the practical implementation has been realized in the Two/three Dimensional Transport (TDT) solver, as a part of the APOLLO3® project. A three-dimensional MOC solver for 3D extruded geometries has been implemented in this code during a previous PhD project, relying on a piecewise constant approximation for the neutrons fluxes and sources. The developments presented in the following represent the natural continuation of this work. Three-dimensional neutron transport MOC solvers are able to produce accurate results for complex geometries. However accurate, the computational cost associated to this kind of solvers is very important. An axial polynomial representation of the neutron angular fluxes has been used to lighten this computational burden.The work realized during this PhD can be considered divided in three major parts: transport, acceleration and others. The first part is constituted by the implementation of the chosen polynomial approximation in the transmission and balance equations typical of the Method Of Characteristics. This part was also characterized by the computation of a set of numerical coefficients which revealed to be necessary in order to obtain a stable algorithm. During the second part, we modified and implemented the solution of the equations of the DPN synthetic acceleration. This method was already used for the acceleration of both inners and outers iteration in TDT for the two and three dimensional solvers at the beginning of this work. The introduction of a polynomial approximation required several equations manipulations and associated numerical developments. In the last part of this work we have looked for the solutions of a mixture of different issues associated to the first two parts. Firstly, we had to deal with some numerical instabilities associated to a poor numerical spatial or angular discretization, both for the transport and for the acceleration methods. Secondly, we tried different methods to reduce the memory footprint of the acceleration coefficients. The approach that we have eventually chosen relies on a non-linear least square fitting of the cross sections dependence of such coefficients. The default approach consists in storing one set of coefficients per each energy group. The fit method allows replacing this information with a set of coefficients computed during the regression procedure that are used to re-construct the acceleration matrices on-the-fly. This procedure of course adds some computational cost to the method, but we believe that the reduction in terms of memory makes it worth it.In conclusion, the work realized has focused on applying a simple polynomial approximation in order to reduce the computational cost and memory footprint associated to a Method Of Characteristics solver used to compute the neutron fluxes in three dimensional extruded geometries. Even if this does not a constitute a radical improvement, the high order approximation that we have introduced allows a reduction in terms of memory and computational times of a factor between 2 and 5, depending on the case. We think that these results will constitute a fertile base for further improvements
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Hofírek, Michal. "Modelování tlakových pulsací v potrubí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318683.
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This diploma thesis deals with problem of water hammer in pipes affected by viscoelastic behavior of pipe material. Mathematical model uses pressure dependent speed of sound in water air mixture. For purpose of numerical solution the Method of Characteristics with independent time step is introduced. This method is compared with commonly used methods such as Method of Characteristics (MOC) and Lax Wendroff scheme. Derived model, solved with Method of Characteristics with independent time step, is verified with experimental simulation.
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Delaney, Michael B. "Selection Method and Judicial Background Characteristics." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382372765.
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Wood, Stephen L. "Modeling of Pipeline Transients: Modified Method of Characteristics." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/456.
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The primary purpose of this research was to improve the accuracy and robustness of pipeline transient modeling. An algorithm was developed to model the transient flow in closed tubes for thin walled pipelines. Emphasis was given to the application of this type of flow to pipelines with small radius 90° elbows. An additional loss term was developed to account for the presence of 90° elbows in a pipeline. The algorithm was integrated into an optimization routine to fit results from the improved model to experimental data. A web based interface was developed to facilitate the pre- and post- processing operations.
Results showed that including a loss term that represents the effects of 90° elbows in the Method of Characteristics (MOC) [1] improves the accuracy of the predicted transients by an order of magnitude. Secondary objectives of pump optimization, blockage detection and removal were investigated with promising results.
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Chandran, Varadharajan. "Robust Method to Deduce Cache and TLB Characteristics." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308256764.
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Rahman, Mashuqur, Ulf Håkansson, and Johan Wiklund. "Grout pump characteristics evaluated with the UVP+PD method." KTH, Jord- och bergmekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107161.
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Rock grouting is performed to decrease the hydraulic conductivity around underground structures, such as tunnels and caverns. Cement grouts are often used and pumped into joint and fractures of the rock formation. Piston type pumps are mostly used for high pressure rock grouting. A pulsation effect is inevitable when using this type of pump due to the movement of the piston. The effect of this pulsation on rock grouting is yet to be known but believed to be benefi-cial for the penetration of the grout. Current flow meters used in the field are not accu-rate enough to determine the fluctuation of the flow rate when it is less than 1 l/min. In addition, currently available flow meters measure the average of the flow over a cer-tain period of time, hence the true fluctuation of the flow rate due to the pulsation of the piston remains unknown. In this paper, a new methodology, the so called ‘Ultrasound Velocity Profiling – Pressure Difference’ (UVP+PD) method has been introduced to show the pulsation effect when using a piston type pump. The feasibility of this method was successfully investigated for the direct in-line determination of the rheological properties of micro cement based grouts under field conditions (Rahman & Håkansson, 2011). Subse-quently, it was also found that this method can be very efficient to measure the fluctu-ation of the flow rate for different types of pumps. From a grouting point of view the UVP+PD method can be used to synchronize the pressure and flow of a piston type pump by measuring the pulsation effect. Conse-quently it can be used as a tool for the efficiency and quality control of different types of pumps.QC 20121221
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Kiser, Eric. "Earthquake Characteristics as Imaged by the Back-Projection Method." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10355.
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This dissertation explores the capability of dense seismic array data for imaging the rupture properties of earthquake sources using a method known as back-projection. Only within the past 10 or 15 years has implementation of the method become feasible through the development of large aperture seismic arrays such as the High Sensitivity Seismograph Network in Japan and the Transportable Array in the United States. Coincidentally, this buildup in data coverage has also been accompanied by a global cluster of giant earthquakes (Mw>8.0). Much of the material in this thesis is devoted to imaging the source complexity of these large events. In particular, evidence for rupture segmentation, dynamic triggering, and frequency dependent energy release is presented. These observations have substantial implications for evaluating the seismic and tsunami hazards of future large earthquakes. In many cases, the details of the large ruptures can only be imaged by the back-projection method through the addition of different data sets and incorporating additional processing steps that enhance low-amplitude signals. These improvements to resolution can also be utilized to study much smaller events. This approach is taken for studying two very different types of earthquakes. First, a global study of the enigmatic intermediate-depth (100-300 km) earthquakes is performed. The results show that these events commonly have sub-horizontal rupture planes and suggest dynamic triggering of multiple sub-events. From these observations, a hypothesis for the generation of intermediate-depth events is proposed. Second, the early aftershock sequences of the 2004 Mw 9.1 Sumatra-Andaman and 2011 Mw 9.0 Tohoku, Japan earthquakes are studied using the back-projection method. These analyses show that many events can be detected that are not in any local or global earthquake catalogues. In particular, the locations of aftershocks in the back-projection results of the 2011 Tohoku sequence fill in gaps in the aftershock distribution of the Japan Meteorological Agency catalogue. These results may change inferences of the behavior of the 2011 mainshock, as well as the nature of future seismicity in this region. In addition, the rupture areas of the largest aftershocks can be determined, and compared to the rupture area of the mainshock. For the Tohoku event, this comparison reveals that the aftershocks contribute significantly to the cumulative failure area of the subduction interface. This result implies that future megathrust events in this region can have larger magnitudes than the 2011 event.Earth and Planetary Sciences
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Yeung, Hway-Seen. "Evaluation of legume cooking characteristics using a rapid screening method." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2514.
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Jansen, Derek (Derek Timothy) 1963 Carleton University Dissertation Management Studies. "The influence of host country characteristics on method of entry." Ottawa.:, 1992.
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Tao, Zhengsu. "Characteristics of the transparent fluid assisted in-process measurement method /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20TAO.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 106-114). Also available in electronic version. Access restricted to campus users.
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Aimmanee, Sontipee. "Deformation and Force Characteristics of Laminated Piezoelectric Actuators." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11219.
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This research discusses the mechanical characteristics of laminated piezoelectric actuators that are manufactured at an elevated temperature, to cure the adhesive bonding the layers together, or to cure the layers made of polymeric composite material, and then cooled to a service temperature. Mainly discussed are actuators that are composed of layers of passive materials and a layer of piezoelectric material. THUNDER (THin layer UNimorph ferroelectric DrivER and sensor) and LIPCA (LIghtweight Piezo-composite Curved Actuator) actuators, which consist of layers of metal, adhesive and piezoelectric material, and carbon-epoxy, glass-epoxy and piezoelectric material, respectively, are studied and investigated in detail to understand the thermal effects due to the elevated manufacturing temperature. Owing to the large out-of-plane deformations of the THUNDER actuators as a result of cooling to the service temperature, inclusion of geometric nonlinearities in the kinematic relations is taken into consideration for prediction of the thermally-induced deformations and residual stresses. The deformations and residual stresses are predicted by using a 23-term Rayleigh-Ritz approach and more rigorous, time-consuming, finite-element analyses performed with ABAQUS. The thermally-induced deformations of THUNDER actuators can result in multiple room-temperature manufactured shapes, whereas those of LIPCA actuators (LIPCA-C1 and LIPCA-C2) exhibit single room-temperature manufactured shape. Actuation responses of these actuators caused by a quasi-static electric field applied to the piezoelectric layer are also studied with the Rayleigh-Ritz approach. It is shown that geometrical nonlinearities play an important role in the actuation responses, and these nonlinearities can be controlled by the choice of actuator geometry and the materials in the passive layers. In addition, blocking forces representing load-carrying capability of THUNDER and LIPCA actuators are determined. Support conditions and again geometrical nonlinearities are vital factor in load-resisting performances. Amongst the actuators considered, the actuated deflection and blocking forces are compared. Finally, based on the outcome of this study, new criteria for designing a new type of laminated piezoelectric actuators with improvement of performance characteristics are proposed.Ph. D.
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Ganahl, Peter Daniel. "Structured illumination as a processing method for controlling photopolymerized coating characteristics." Diss., University of Iowa, 2007. http://ir.uiowa.edu/etd/184.
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Ткачук, Юрій Якович, Юрий Яковлевич Ткачук, Yurii Yakovych Tkachuk, Максим Васильович Найда, Максим Васильевич Найда, and Maksym Vasylovych Naida. "Graphic-analytical method of defining pressure characteristics of centrifugal-vortex pumps." Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/40478.
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Centrifugal-vortex pumps are usually adopted for a small boiler feeding of a
hot-water heating system and also in the water-supply system, in the food and oil
industry.
Centrifugal-vortex pumps have rather good operating showings in the
results of successful using of the positive qualities if the centrifugal working wheel
and vortex one. They are fixed on the common shaft.
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Sananpanichkul, Wanna. "Paper and printed paper surface characteristics studied using an optical method." Thesis, Open University, 1993. http://oro.open.ac.uk/54812/.
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A non-contact optical method for evaluating surface characteristics is reviewed. The optical reflectance instrument has been improved to be able to evaluate printed surfaces. Experiments were conducted with solid prints prepared on two types of papers printed with a heatset yellow ink. Both paper surfaces and printed surfaces are characterized into two regions: above the surface plane resulting in macrosmoothness (Sm) and below the surface plane resulting in microsmoothness (Su). For a better understanding of such optical print smoothness, a printed surface model is proposed based on Barkas' classical model. It is generally known that the qualities of a print are determined by the materials and their interactions in the process, therefore the formation of printed surface characteristics has been discussed in relation to ink and paper interaction. Print smoothness is influenced by the uncompressed paper roughness and porosity, which determine the degree of ink penetration and ink distribution on the surface. Offset lithographic printing has been the most widely used printing process, printing onto paper substrates. To achieve good press performance and high quality prints, the ink has to emulsify a certain amount of fountain solution; maintenance of this ink and water balance is, therefore, very important. The effects of fountain solution emulsified in the ink on print smoothness wp-re investigated. A range, of varying amounts of fountain solutions, was emulsified in a heatset yellow ink using a high speed laboratory mixer; these 'emulsion inks' were printed as soon as possible after preparation. It was found that the print smoothness in macro regions, for both uncoated and coated papers, decreased significantly. In addition, an unpigmented ink system was employed to verify the role and the effects of pigment in the emulsification mechanism on print smoothness. The results indicated that pigment is the dominant contributor, to a smoothness decrease; and the pigment effect arises from the amount of fountain solution emulsified in the ink. It has become important to measure print quality directly and quantitatively in the developments of ink, paper and printing technologies. This method makes it possible to measure print smoothness as a criterion for print quality.
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Jewell, Jeffrey Steven. "Higher-order Runge--Kutta type schemes based on the Method of Characteristics for hyperbolic equations with crossing characteristics." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1028.
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The Method of Characteristics (MoC) is a well-known procedure used to find the numerical solution of systems of hyperbolic partial differential equations (PDEs). The main idea of the MoC is to integrate a system of ordinary differential equations (ODEs) along the characteristic curves admitted by the PDEs. In principle, this can be done by any appropriate numerical method for ODEs. In this thesis, we will examine the MoC applied to systems of hyperbolic PDEs with straight-line and crossing characteristics. So far, only first- and second-order accurate explicit MoC schemes for these types of systems have been reported. As such, the purpose of this thesis is to develop MoC schemes which are of an order greater than two.
The order of the global truncation error of an MoC scheme goes hand-in-hand with the order of the ODE solver used. The MoC schemes which have already been developed use the first-order Simple Euler (SE) and second-order Modified Euler (ME) methods as the ODE solvers. The SE and ME methods belong to a larger family of numerical methods for ODEs known as the Runge--Kutta (RK) methods. First, we will attempt to develop third- and fourth-order MoC schemes by using the classical third- and fourth-order RK methods as the ODE solver. We will show that the resulting MoC schemes can be strongly unstable, meaning that the error in the numerical solution becomes unbounded rather quickly.
We then turn our attention to the so-called pseudo-RK (pRK) methods for ODEs. The pRK methods are at the intersection of RK and multistep methods, and a variety of third- and fourth-order schemes can be constructed. We show that when certain pRK schemes are used in the MoC, at most a weak instability, or no instability at all, is present, and thus the resulting methods are suitable for long-time computations. Finally, we present some numerical results confirming that the MoC using third- and fourth-order pRK schemes have the desired accuracy.
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Müller, Nora [Verfasser]. "Stochastic Transport Equations: Method of Characteristics versus Scaling Transform Approach / Nora Müller." Bielefeld : Universitätsbibliothek Bielefeld, 2019. http://d-nb.info/1197798102/34.
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Popov, G. F., A. S. Salah, and R. V. Lazurik. "Verification of Two-Parametric Fitting Method for Determination of Electron Beam Characteristics." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/41121.
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Computer simulation of radiation processing allows correctly to schedule and control the performance of work on radiation processing installations. In particular, for radiation technology using electron beams (EBs) in the calculations it is required the values of energy characteristics of the electron irradiation. The paper [1] describes a method for the twoparametric fitting of semi-empirical model (PFSEM method) to the results of measuring the depth dependence of the absorbed dose for electron radiation performed by dosimetric wedge.
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Vennam, Sandeep. "Hygrothermal effects on free vibration characteristics of rotating composite beams." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4969.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xi, 72 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 69-72).
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BARROS, FABRICIO JOSE BRITO. "THREE-DIMENSIONAL BEAM TRACING METHOD TO OBTAIN ULTRA WIDEBAND INDOOR RADIO CHANNEL CHARACTERISTICS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16771@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREste trabalho descreve o método de traçado de feixes em três dimensões que permite a caracterização do canal em uma banda ultralarga. As características do canal são acessadas através do retardo médio, espalhamento de retardo RMS e banda de coerência. Uma análise adicional sobre a variação da potência ao longo da distância foi realizada. Os resultados obtidos foram comparados com mediadas realizadas, com o auxílio da técnica de sondagem em frequência, para validação do método utilizado.
This work describes the tridimensional beam tracing method that allows one to characterize the Ultra Wideband (UWB) indoor Radio Channel. The channel characteristics are assessed in terms of mean delay, delay spread and coherence bandwidth. An additional analysis related to power variation through distance was also evaluated. The results were compared to measurements obtained from the frequency sounding technique.
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Shaner, Samuel Christopher. "Transient method of characteristics via the Adiabatic, Theta, and Multigrid Amplitude Function methods." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92092.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 147-149).
In this thesis, we investigated the Adiabatic, Theta, and Multigrid Amplitude Function (MAF) methods for solving the Method of Characteristics (MOC) formulation of the time-dependent neutron transport equation. The transient transport versions of the 2D LRA and C5G7 benchmarks were used to assess the performance and accuracy of these methods. We began by deriving the CMFD-accelerated MOC algorithm in 2D steady state form and examining the effects of various MOC and CMFD parameters on eigenvalue convergence. The C5G7 problem showed similar acceleration performance for 2, 4, and 7 CMFD energy group structures. CMFD meshes at or near the pin-cell level resulted in the greatest speedups of 15-45x in run time and 30-240 x in number of MOC iterations for both problems. A relaxation factor on the nonlinear diffusion coefficient was required to maintain stability for both problems with optimum values between 0.4-0.7. A sensitivity study was conducted on the C5G7 and LRA transient problems to understand the effects of time step and spatial mesh sizes on the solution accuracy and run time performance. The shape function time step size had a large effect on the solution accuracy for the MAF and Theta methods in solving the LRA problem. All methods showed moderate sensitivity to the amplitude function step size, where increasing step size shifted the peak power to earlier times. The coarse mesh size did not have a significant effect on solution accuracy, but meshes on the pin-cell level were clearly preferred to reduce run time. The overall run time performance between the three methods was mixed. The MAF and Theta methods displayed ~84% speedup over the Adiabatic method for the LRA problem, but all methods had similar run times for the C5G7 problem. This inconsistency is likely due to the more drastic flux shape change during the LRA transient and the ability of the MAF and Theta methods to more accurately treat the flux shape temporal derivative. These results demonstrate that the Adiabatic, Theta, and MAF methods are computationally efficient methods for solving the time-dependent neutron transport equation and warrant further investigation. There are clear advantages to each method and the optimal method will likely depend on the transient characteristics of the problem being studied.
by Samuel Christopher Shaner.
S.M.
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Pasquini, Enrico, Heiko Baum, Bebber David van, and Denis Pendovski. "Numerical Simulation of Transient Diabatic Pipe Flow by using the Method of Characteristics." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199881.
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The following paper presents a one-dimensional numerical model for simulating transient thermohydraulic pipe flow based on the Method of Characteristics. In addition to mass and momentum conservation, the proposed scheme also guarantees compliance with the laws of thermodynamics by solving the energy equation. The model covers transient changes in fluid properties due to pressure changes, heat transfer and dissipation. The presented methodology also allows the computation of the transient temperature distribution in the pipe wall through an additional ordinary finite difference scheme. The numerical procedure is implemented in the commercial simulation software DSHplus. The capability of the code is examined by comparing the simulation results with theoretical solutions and experimental data.
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Куліш, Віктор Васильович, Виктор Васильевич Кулиш, Viktor Vasylovych Kulish, and V. I. Savchenko. "About application technique of the method of averaged characteristics to relativistic electronics problems." Thesis, Видавництво СумДУ, 2004. http://essuir.sumdu.edu.ua/handle/123456789/23721.
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LePera, Stephen D. "Development of a Novel Planar Mie Scattering Method for Measurement of Spray Characteristics." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26143.
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The work herein details an optical droplet measurement system based on planar multi-angle Mie scattering. Sizing information consists of a mean droplet diameter and droplet distribution estimates for every individual point within a planar (2D) area of interest. The planar method makes possible the fast acquisition of data within a large field of interest, and uses relatively inexpensive instrumentation.
As presented, the method demonstrated the ability to measure water droplets from a typical simplex spray nozzle, across the range of 5-50 micrometers within +/-10% of known values, and in addition return an estimate of the shape and width of the size distribution at each location within the planar region of interest. Measurements demonstrating the agreement between results from this current method and known PDA data were successfully completed for a 1-gallon-per-hour spray nozzle, and repeatability was demonstrated in 2.5-gallon-per-hour and 4.5-gallon-per-hour nozzles. Additionally the limits of the technique are explored with simulated data. Conclusions from these exercises show that the multi-angle planar Mie scattering method is capable of measuring droplet distribution characteristics and means within a nominal range of 0.3 micrometers up to 150 micrometers.Ph. D.
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Ahmadi, Rahmataba Kaveh. "Advances in calculation of minimum miscibility pressure." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3237.
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Minimum miscibility pressure (MMP) is a key parameter in the design of gas flooding. There are experimental and computational methods to determine MMP. Computational methods are fast and convenient alternatives to otherwise slow and expensive experimental procedures. This research focuses on the computational aspects of MMP estimation. It investigates the shortcomings of the current computational models and offers ways to improve the robustness of MMP estimation. First, we develop a new mixing cell method of estimating MMP that, unlike previous "mixing cell" methods, uses a variable number of cells and is independent of gas-oil ratio, volume of the cells, excess oil volumes, and the amount of gas injected. The new method relies entirely on robust P-T flash calculations using any cubic equation-of-state (EOS). We show that mixing cell MMPs are comparable with those of other analytical and experimental methods, and that our mixing cell method finds all the key tie lines predicted by MOC; however, the method proved to be more robust and reliable than current analytical methods. Second, we identify a number of problems with analytical methods of MMP estimation, and demonstrate them using real oil characterization examples. We show that the current MOC results, which assume that shocks exist from one key tie line to the next may not be reliable and may lead to large errors in MMP estimation. In such cases, the key tie lines determined using the MOC method do not control miscibility, likely as a result of the onset of L₁-L₂-V behavior. We explain the problem with a simplified pseudo-ternary model and offer a procedure for determining when an error exists and for improving the results. Finally, we present a simple mathematical model for predicting the MMP of contaminated gas. Injection-gas compositions often vary during the life of a gasflood because of reinjection and mixing of fluids in situ. Determining the MMP by slim-tube or other methods for each possible variation in the gas-mixture composition is impractical. Our method gives an easy and accurate way to determine impure CO₂ MMPs for variable field solvent compositions on the basis of just a few MMPs. Alternatively, the approach could be used to estimate the enrichment level required to lower the MMP to a desired pressure.text
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Ming-HsienLin and 林明憲. "An Evaluation Method for Shape Style Characteristics." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/gw757y.
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博士國立成功大學
工業設計學系
104
In the graphic design or the product shape of the design process, an effective graphical aesthetic evaluation tools can assist the designers to make decision in design process. The existing entropy of evaluation method which most commonly used are still not incapable to recognize and assessing the shape efficiently because of lack of project analysis and less reference for identification. The graphics cannot be effective for aesthetic evaluation and identification, therefore, to explore more graphic aesthetic analysis project can provide more graphics and aesthetics reference. This study is to improve the existing method of entropy and to propose a new graphical style characteristics evaluation method that can be applied to evaluate the characteristics of 2D graphics features as a reference to quantitative benchmarks pf graphic design decisions; The purpose is to simplify the calculation by the linear structure analysis point conversion rule will be converted into a collection of graphic pattern feature point shape feature points (SFP); and then, the effect of the elements and proportions, as well as elemental analysis pattern feature set of points generated. Eight graphics are taken to evaluate the aesthetic characteristics and composition of the evaluation contains four patterns: linear complexity H(t), the complexity of the feature point H(p), the location of the complexity H(r), the graphic complexity H(s)；and mechanical features for four graphic assessment: balance I(b), the degree of motion I(m), the smoothness of the I(s) and the elasticity intensity of the graphic I(t) et cetera. By using the strength of the performance of each characteristic values can be used to describe the aesthetic expression pattern. Whereby the difference between the graphics can be easily identified and isolated. Finally the eight cases of the trademark graphic feature value of the evaluation, from the result shows that this method can effectively evaluate graphical features, the strength of each characteristic values can help the graphic designers to interpret the differences of the graphics based on the degree of approximation or make decision based on the graphic design work.
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CHIANG, CHEN YU. "NUMERICAL SIMULATION OF GROUNDWATER CONTAMINANT TRANSPORT ON A SUPERCOMPUTER WITH INJECTION-PUMPING NETWORKS USING THE MODIFIED MOC AND MFE METHOD." Thesis, 1986. http://hdl.handle.net/1911/15962.
Full textAbstract:
To prevent the deterioration of groundwater quality, mathematical simulation models have been formulated to predict the transport of contaminants in complex aquifer systems and to design remedial schemes for the problems.
Existing analytical and numerical approaches have serious disadvantages for large-scale nonhomogeneous field problems where well-pumping or injection is involved. The major difficulties relate to numerical dispersion and oscillations in highly advective-dominated simulations, computational accuracy, excessive computer expense, grid orientation problems, and an inability for simulating with random conductivity fields.
Recent work by Ewing, Russell, and Wheeler (1983) has produced a very efficient and accurate method for miscible displacement in oil reservoirs. Their concept was adapted and then applied to groundwater contaminant transport problems in this thesis. The highly efficient code combines a mixed finite element procedure for groundwater flow and a modified method of characteristics and finite element procedure (MMOC) for the parabolic transport equation. The preconditioned conjugate gradient method was used to solve the resulting matrices for both equations.
The method has been compared with two analytical solutions on a homogeneous domain. Excellent agreements were demonstrated through relative concentration contours and breakthrough curves. The method has also been compared with the currently popular USGS Solute Transport model. More accurate resolutions were achieved for the MMOC method than for the USGS Solute Transport model. In addition, much larger time steps were allowed in the MMOC method than the USGS Solute Transport model obtaining similar resolutions.
The method has been applied to highly advective-dominated problems on a CRAY-XMP supercomputer and the results showed there are no dispersion or oscillation problems common in many existing numerical codes. The method has also been used to simulate cases with random hydraulic conductivity fields that were simulated from Turning Bands Method. Fingering phenomena developed because the concentration front is transported more rapidly in the zones of higher hydraulic conductivity. The method has been shown to be superior in many respects to currently used models in groundwater transport, especially in the presence of strong pumping or injection centers or heterogeneities in the flow field.
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Lin, Ching-Che, and 林靖哲. "An Image Enlargement Method Based on Edge Characteristics." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33189601358349583152.
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Chen, Yu-Ming, and 陳裕明. "A Fuzzy Taguchi Method for Multiple Quality Characteristics." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/45767234562885209651.
Full textAbstract:
碩士華梵大學
工業管理學系碩士班
92
The purpose of this study is to propose a quick and efficient method to assist for the manufacturing process improvement, especially, for facilitating mass production smoothly during the new product developing stage. The research employs Taguchi Quality Engineering & Fuzzy Sets Theory to analyze each quality characteristic in the SMT processes. The integration of Principal Component Analysis & Grey Relational Analysis is used for analyzing synthetically Multiple Quality Characteristics (MQC) to obtain the optimal process parameter combinations for the control factors. Thus, it aims to create one algorithmic model, which can gain the best parameter combinations efficiently to meet the design specification, for the optimization of the MQC process as well as for the engineer to follow up while handling this kind of issue. In the experimental verification, there are two methodologies applied: one is fuzzy judgment data (Qualitative Measurements); another is practical measurement data (Quantitative Measurements). Finally, this research compares these two methodologies and concludes that the fuzzy judgments can replace the practical measurements. For example, (1) The profile/resolution of solder printing can be used to represent the “soldering thickness” and replace the practical thickness measurement. (2) The visual inspection of the “printing deviation” in terms of semantic values can be used to determine the degree of deviation instead of the practical measurement. The replacements mentioned without the precise inspection facilities but the fuzzy judgments by the engineer or inspector, still won’t impact the selection of the optimal parameter combinations.
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Cheng, Han-Wen, and 鄭涵文. "Dependence of Electrical Characteristics on MoS2 Synthesis Method." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/y447cp.
Full textAbstract:
碩士國立交通大學
材料科學與工程學系奈米科技碩博士班
107
In this thesis, molybdenum disulfide (MoS2) materials with different preparation methods will be discussed. After different process treatments, we choose two types of metal Mo and Ni/Au which are used to fabricate the contact metal pad and compared the electrical effects of these process. In recent years, many studies have used exfoliation to fabricate molybdenum disulfide devices and developing many research methods to improve the electrical properties of MoS2 devices. Although this preparation way is extremely quick, convenient and the process is simple, but the MoS2 film area is very tiny and the material thickness is not uniform. Above characteristics make it difficult to apply on the industrial chain of mass production. Therefore, this work will use the recently popular molybdenum disulfide material synthesis method- chemical vapor deposition (CVD) and another two-step MoS2 synthesis method to make electrical comparisons, we will separate two parts to carry out: (1) 2-step method MoS2 device was subjected to an induce couple plasma (ICP) pretreatment and an annealing process, respectively. (2) CVD MoS2 FET is covered SiO2 capping layer on channel and executed annealing process. It is desirable to improve the sheet resistivity (rSH) and contact resistance (RC) of the MoS2 device. The results show that the 2-step method MoS2 device has a very high rSH and RC values after ICP pretreatment and high temperature annealing, which is close to the insulator state due to high defect density. The capping layer of the CVD MoS2 FET improves the ID-VG electrical properties of the device. There is also improved electrical performance after annealing at 300 °C. From the above experimental results, we can summarize that in the initial process step, we need to choose a MoS2 material with high quality, low defect and low rSH. And avoiding the degradation of MoS2 material by environment and process in the subsequent process. It is the most essential procedure in manufacture a good electrical MoS2 devices.
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黃瑞育. "Characteristics of In-O system prepared by hydrothermal method." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/j5wsph.
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巫文凱. "Field Study on Signal Characteristics of Shallow Seismic Method." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/14632221858703474476.
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Wu, Ming-Feng, and 吳銘峯. "Design Method for Copper Gong with Special Sound Characteristics." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/76057433039787026035.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
100
This work aims to develop the design method for the copper gong that has the special sound characteristics. The copper gong is a kind of traditional instrument. There are various types and shapes for gongs which percussion sounds reveal different characteristics for different geometries and dimensions. First, experimental modal analysis (EMA) is conducted on a hand-made copper gong to obtain structural modal parameters, including natural frequencies, mode shapes and modal damping ratios. The finite element (FE) model is also built to perform theoretical modal analysis. Base on the experimental modal data, the FE model is updated by adjusting the material properties for the stiffen effect of material due to manufacturing. The percussion sound spectrum is also measured by the microphone for the gong struck at different locations. The fundamental and overtone frequencies can be identified and explained by the structural mode shapes. A special type of copper gong with oval navel is also studied to characterize the sound effects for different geometry parameters. The optimization formulation for geometry design of copper gong targeting to special sound effects is presented in conjunction with the commercial finite element analysis (FEA) software. This work develops a systematic design approach, in particular for the design of copper gongs. Several design options can be implemented to fit the need for adjusting the sound characteristics of gongs. The design methodology can also be applied to other musical instruments as well, especially for those requiring special sound effects.
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Ho, Liao-Chia, and 廖嘉禾. "Characteristics of Zn2SnO4 (ZTO) nanoparticles synthesized via hydrothermal method." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/24277278027384167331.
Full textAbstract:
碩士中華技術學院
機電光工程研究所碩士班
97
Abstract The precursor powders including Zn and Sn ion with different molar ratios solution were utilized to synthesize Zn2SnO4 (ZTO) with NaOH as a basic mineralizer via hydrothermal method. Under low temperature 250oC and high pressure for 72 hours reaction time, the solution in a sealed autoclave presented supercritical condition to make the Zn and Sn ion precursor reaction. The solution was heated to form high nano-crystalline ZTO powder. The crystal structure of experimental results is investigated by X-ray diffraction (XRD). The synthesized powders with Zn/Sn molar ratios 2.5:1 showed high crystalline ZTO nanoparticles. From the scanning electron microscopy (SEM) images, the cubic surface morphology of ZTO powders can be observed. The particles were relatively uniform and well-dispersed. The Zn/Sn molar ratio 2.5:1 sample showed Raman spectra peak of 528cm-1 and 668cm-1 that the ZTO sample had a spinel structure. Powders obtained from different Zn/Sn molar ratios were used in degradation reaction with methyl blue as indicator. The Zn/Sn molar ratio 2.5:1 sample appeared the best photocatalytic activity. Ternary oxide of Zn2SnO4 is relatively superior photocatalytic activity to the binary oxide of ZnO and SnO2. In another study, precursor solution in different reaction time (12~96h) were utilized to synthesize ZTO with hydrothermal temperature 250oC, Zn/Sn molar ratio 2.5:1 and NaOH as a basic mineralizer. The result is found that the ZTO powder obtained with reaction time 72h showed higher crystalline nanoparticles and the best photocatalytic activity. Keywords: hydrothermal method, Zn2SnO4 (ZTO), mineralizer, photocatalytic activity, spinel.
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Yen, Tsai Meng, and 蔡孟諺. "Analysis of Characteristics of Induction Motor with Taguchi Method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/45845163040446315739.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
93
This research mainly analyses and improves the characteristics of a single-phase induction motor via finite element software Flux2D supplied by PEEI. Because the output torque of this motor is small but the temperature is rising fast, it is required to improve its torque output with relative low temperature rising. The research employs Flux2D to create geometry model of the motor, to set up the circuit, and to analyze the temperature and torsion characteristic of the motor, via changing primary factors such as the circles of winding, capacitor, airgap and thickness of the core. The simulated results were then compared with the experiment results. There is discrepancy between them but the trends of curve are very similar. The simulated results are hence of important reference. The improvement of torque and temperature is then studied. At last, with the Taguchi method, the best achievable values of temperature and torque are estimated. This research provides a method to the analysis and improvement of the motor characteristics by Flux2D. This method can be used by industry for identifying and modification of motor characteristics.
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Lin, Keng-hung, and 林根宏. "Investigation on emulsion characteristics using phase-inversion temperature method." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16756465072050117222.
Full textAbstract:
碩士國立臺灣海洋大學
輪機工程系
100
The effects of type and concentration of surfactants on emulsification properties and diesel engine emission characteristics of an emulsion prepared by a phase-inversion temperature method were investigated in this study. Non-ionic surfactants were used for the emulsion formation of silicon oil with de-ionic water at the first experimental stage. The engine performance and emission characteristics of soybean biodiesel, and emulsions prepared by mechanical stirring and phase-inversion temperature methods, respectively under constant engine torque and varied engine speeds were studied at the second experimental stage. The experimental results show that the emulsion prepared by the method of phase-inversion temperature had higher O2 emission, NOx emission and exhaust gas temperature while lower CO emission than the emulsion by mechanical stirring. The soybean biodiesel was found to have the lowest fuel consumption rate, brake specific fuel consumption, and CO emission while the highest exhaust gas temperature, NOx emission, and O2 emission among those three fuels.
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Huang, Run-Tang, and 黃潤棠. "Characteristics and Synthesis of Mesoporous YSZ by Sol Gel Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/e2yb77.
Full textAbstract:
碩士國立臺北科技大學
材料及資源工程系研究所
98
The purpose of this study is to synthesize the yttrium stabilized zirconia with ordered mesoporous structure by the sol-gel method. The effect of surfactant concentration, aged environment, surfactant mixing time and thermal treatment temperature on the pore formation is studied. The experimental results show that when taking non-ionic tri-block copolymer surfactant (P123) as template, porous structure of yttrium stabilized zirconia can be synthesized under 40℃ and 40% relative humidity environment followed by a 700℃ heat treatment. The diffraction peak at 2θ = 0.24 observed by small angle x-ray diffraction method indicates the existence of ordered internal pore structure arrangement. Based on the results of nitrogen isotherm adsorption-desorption measurements and Barrett-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) theories, the mesoporous structure with average pore size of 6.74 nm can be estimated. The absorption-desorption curves suggest that the material pore structure is channel structure with approximate BET surface area value of 94.24 m2/g. Other results such as the effect of amounts of surfactant on the micelle formation mechanism is clearly observed; Both BET surface area and average pore diameter markedly increase under atmospheric curing conditions; The average pore size increases with increasing surfactant mixing time and heat treatment temperature while the BET surface area decreases. After TEM observation, the morphology of yttrium stabilized zirconia porous structure prepared in this study is channel structure.
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Heo, Che-Feng, and 何奇峰. "Application of Multivariate Statistical Method in Water Quality Characteristics Analysis." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/75607122564573217892.
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Chiang, Shih-Wei, and 姜世偉. "Assessments of characteristics method with cubic interpolation for hydraulic computation." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/75583074414902054257.
Full textAbstract:
碩士國立交通大學
土木工程系
91
In the framework of specified time interval scheme, the accuracy of characteristics method is severe affected by the form of interpolation. The HP and CS characteristics methods are two types of high-order characteristics method that respectively apply Hermite cubic and cubic-spline interpolation. In this study, one-dimensional advection -diffusion equation and one-dimensional unsteady open channel flow computation are used to examine the high-order characteristics methods applied within space-line and time-line intervals. As far as practical applications and accuracy are concerned. The space-line HP and CS characteristics methods should be the better choices. The simulated results from the space-line CS characteristics method are similar to those of space-line HP characteristics method. Without tackling auxiliary spatial derivative equation, the space-line CS characteristics method is more simple and efficient than space-line HP characteristics method.
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Chen, Yun-Chih, and 陳昀芝. "Evaluation of ring characteristics of hardwoods by wounding window method." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/49030472025329166483.
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Liu, Yu-Sheng, and 劉育盛. "Applying Earth Electrical Method to Investigate Shazongliao Region Stratum Characteristics." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/11462196671311390841.
Full textAbstract:
碩士國立屏東科技大學
水土保持系所
104
To provide data of regional strata in Shanzongliao (Taitung County, Taiwan)in more detail, the earth electrical logging method applied in geophysical explorations was used in this study to compensate for the current borehole deficiencies and limitations. The Wenner array in the earth electrical logging method was employed to perform a stratigraphic profile analysis of the Shanzongliao landslide areas in Chishang Township, Taitung County. Survey points and survey lines were set up by incorporating data derived from geological boring and inclination observation tubes. 15 survey points along six survey lines were established in the Shanzongliao landslide areas. Each survey point measured approximately 30 m in depth, from which data obtained using the earth electrical logging method were used to generate ρa-a curves; the curve characteristics were then analyzed. Next, the collected data was utilized to plot the 2D stratigraphic profile by the software for stratigraphic structure analysis. Finally, the research results were compared with data obtained from boreholes and inclination observation tubes for verification. The whole process validated the advantages of the earth electrical logging method: quick, convenient, and non-destructive. By combining it with relevant data, further insight into strata information can be obtained; meanwhile, groundwater distribution and relevant effects can be further investigated. Field observations showed that some areas in the landslide region are characterized by loose, fragmented strata structures and an abundance of groundwater, which highly increase the possibility of landslide destructions. However, Analysis of the aforementioned region showed that there are still slow and stable land movements in some areas of the region. Therefore, continuous monitor or regulative engineering must be in place to enhance the conservation.
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LI, XIAN-ZHANG, and 李顯掌. "Study on multimode characteristics method for nonuniform sediment transport modeling." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/26981160424596008893.
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Huang, Szu-Wei, and 黃思瑋. "Wire Vibration Analysis of Wiresaw by Using Method of Characteristics." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/24498952103032614557.
Full textAbstract:
碩士逢甲大學
自動控制工程所
100
The energy was getting short in recent years, causing the product price to rise. To research and develop the vicarious energy is getting more and more important, of which the first choice is the solar energy. Presently, the main way to produce silicon wafer, which is the major substrate of solar cells, is multi-wire sawing technology. The main purpose of this thesis is to analyze free vibration for the wire when cutting is in progress. At first, we derived the hyperbolic vibrating partial differential equation of wire for wiresaw, and solved the hyperbolic vibrating partial differential equation by method of characteristics. Simulation was conducted with parameters provided by A-TECH SYSTEM Co., Ltd. and the results were used to analyze the influences of wire speed, wire tension, initial conditions and boundary conditions on wire vibration.
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Ke, Cheng-liang, and 柯正良. "Nanoindentation Characteristics using Finite Element Method combined with Abductive Network." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/chngwn.
Full textAbstract:
碩士國立虎尾科技大學
機械與機電工程研究所
95
The purpose of the present work was to investigate the nanoindentation process by FEM of metals, considering strain hardening effect of material. In order to verify the FEM simulation results of the mechanical parameters such as Young’s modulus, yield stress and strain hardening, and the experimental data are compared with the results of the current simulation. The abductive network was then applied to synthesize the data sets obtained from the numerical simulation. The predicted results of the mechanical properties from the prediction model are consistent with the results obtained from experiment. After employing the predictive model can provide valuable references in prediction of the mechanical parameters after nanoindentation tests. We used finite element method to is it keep mark test consumed time and metal mechanical range too big to select suitable materials difficult characteristics to avoid, can predict and analyzed the mechanical characteristics of the metal in the finite element method accurately by one kind of abductive network. But the simulation that does with finite element analysis presses the mark and tests the after treatment materials and trains the database for abductive network, because the experiment load curve has not conformed with imitate the load curve trend, and not enough to laminate, then in order to analyze the mechanical characteristics of the metal effectively , utilize two ways separately, attempt to be estimated the mechanical nature of analyzing the metal in advance by these two ways, but the time that its main purpose consumes in order to utilize the finite element in a large amount sparingly, effective and accurate mechanical characteristics and hardness of metals in advance.
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Pandya, Tara M. "Long Characteristic Method in Space and Time for Transport Problems." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7484.
Full textAbstract:
Discretization and solving of the transport equation has been an area of great
research where many methods have been developed. Under the deterministic transport
methods, the method of characteristics, MOC, is one such discretization and solution
method that has been applied to large-scale problems. Although these MOC,
specifically long characteristics, LC, have been thoroughly applied to discretize and
solve transport problems in the spatial domain, there is a need for an equally adequate
time-dependent discretization. A method has been developed that uses LC discretization
of the time and space variables in solving the transport equation. This space-time long
characteristic, STLC, method is a discrete ordinates method that applies LC
discretization in space and time and employs a least-squares approximation of sources
such as the scattering source in each cell. This method encounters the same problems
that previous spatial LC methods have dealt with concerning achieving all of the
following: particle conservation, exact solution along a ray, and smooth variation in
reaction rate for specific problems. However, quantities that preserve conservation in
each cell can also be produced with this method and compared to the non-conservative results from this method to determine the extent to which this STLC method addresses
the previous problems.
Results from several test problems show that this STLC method produces
conservative and non-conservative solutions that are very similar for most cases and the
difference between them vanishes as track spacing is refined. These quantities are also
compared to the results produced from a traditional linear discontinuous spatial
discretization with finite difference time discretization. It is found that this STLC
method is more accurate for streaming-dominate and scattering-dominate test problems.
Also, the solution from this STLC method approaches the steady-state diffusion limit
solution from a traditional LD method. Through asymptotic analysis and test problems,
this STLC method produces a time-dependent diffusion solution in the thick diffusive
limit that is accurate to O(E) and is similar to a continuous linear FEM discretization
method in space with time differencing. Application of this method in parallel looks
promising, mostly due to the ray independence along which the solution is computed in
this method.
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Yang, Huang-Yi, and 楊煌億. "Study on Elastohydrodynamic Lubrication Characteristics at Pure Squeeze Motion Using Laser Measurement Method and Inverse Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/94906908197847007673.
Full textAbstract:
碩士義守大學
機械與自動化工程學系碩士班
96
As two bodies approach each other along the normal direction, very high pressure is generated in the lubricating film between them due to squeeze effects. In consequence, an elastic dimple occurs at the center of the contact region, with related transient elastohydrodynamic lubrication (EHL) problems. These problems occur in many mechanical contact elements such as gear teeth, cams, piston rings, rolling element bearings and during the stretching process of metal sheets. The laser optical system is employed in the optical EHL impact tester to measure the oil film characteristics in the contact region between steel ball and sapphire under pure squeeze condition. The variation of oil film thickness on the contact region is observed by the principle of optical interferometry and grayscale interferometry technique. High-speed video camera with the microscope records the dynamic characteristics of lubrication in the diminutive contact region. An inverse approach of pure squeeze EHL is employed to calculate the smoothed pressure and the oil film distribution, and they are substituted into Reynolds equation to predict the pressure-viscosity index of lubricant. The least-squares method is employed to calculate the optimum value of the pressure-viscosity index. Results show that the dimple becomes deeper with increasing squeeze velocity. The dimple film thickness becomes greater as the viscosity of lubricant increases. Furthermore, the dimple becomes deeper with increasing squeeze load. Finally, the estimated pressure-viscosity index obtained by the inverse approach is compared with the experimental value of the test fluid. The largest error is 8.21%.
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Lai, Guan-Ting, and 賴冠廷. "Optimization of polishing process with multiple performance characteristics using Quality Function Deployment , Taguchi method and Grey method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/tddgzd.
Full textAbstract:
碩士國立虎尾科技大學
創意工程與精密科技研究所
98
In this study, quality function deployment (QFD) Taguchi method and grey theory to implement customers multiple quality characteristics in the polishing process of Ti-6Al-4V. In the polishing process of Ti-6Al-4V, this study uses QFD to evaluate customer requirements project and technical requirements project by questionnaire and previous experiments. Through QFD to evaluate the critical quality project, the experimental design using orthogonal array and S/N ratio of Taguchi method to find the optimal combination of the polishing parameter levels, and determine the relationship between customer requirements and technical requirements by confidence level of the analysis of variance (ANOVA). Finally, this study applying the traditional method and GM (1, N) model to analysis the priority of technical requirements. By the results of confirm experiment shows the grey theory’s result consistent with a confirm experiment. Therefore, GM (1, N) model might be more appropriate than the traditional method to apply in the QFD. Keywords：QFD, Taguchi method, Grey theory, polishing
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Orhanovic, Neven. "Time domain simulation of Maxwell's equations by the method of characteristics." Thesis, 1993. http://hdl.handle.net/1957/35593.
Full textAbstract:
A numerical method based on the the method of characteristics for hyperbolic systems
of partial differential equations in four independent variables is developed and used
for solving time domain Maxwell's equations. The method uses the characteristic
hypersurfaces and the characteristic conditions to derive a set of independent equations
relating the electric and magnetic field components on these hypersurfaces. A
discretization scheme is developed to solve for the unknown field components at each
time step. The method retains many of the good features of the original method of
characteristics for hyperbolic systems in two independent variables, such as optimal
time step, good behavior near data discontinuities and the ability to treat general
boundary conditions. The method is exemplified by calculating the time domain
response of a few typical planar interconnect structures to Gaussian and unit step excitations.
Although the general emphasis is on interconnect problems, the method is
applicable to a number of other transient electromagnetic field problems governed by
Maxwell's equations. In addition to the method of characteristics a finite difference
scheme, known in mathematic circles as the modified Richtmyer scheme, is applied
to the time domain solution of Maxwell's equations. Both methods should be useful
for efficient full wave analysis of three dimensional electromagnetic field problems.Graduation date: 1994
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Clinkard, DAVID. "Altered Vasomotion Characteristics as a Method of Investigating Vascular Phenotypic Change." Thesis, 2008. http://hdl.handle.net/1974/1507.
Full textAbstract:
Vasomotion is the spontaneous oscillation of vascular tone, occurring due to synchronization of internal calcium fluctuations between multiple vascular smooth muscle cells by gap junction and electrical communication. Although altered vasomotion has been observed in a variety of pathological situations, characterization of these alterations has been lacking. Using a novel method of spectral quantification, and two experimental models known to have altered vascular structure, the present thesis was designed to evaluate whether vasomotion characteristics could be correlated with altered vascular structure.
Rats with perinatal iron deficiency (PID) have previously been shown to possess altered vascular structure. When phenylephrine-mediated contractile and acetylcholine-mediated dilatory responses were investigated in PID animals, they both displayed blunted relaxation as compared to control vessels. When vasomotion characteristics were quantified, vessels taken from PID animals exhibited a decreased power in the very low frequency window (VLF <0.2 Hz). Changing vessel oxygenation to 10% O2 from 95% O2 did not result in significant alterations of vasomotion characteristics. The primary frequency of oscillation was investigated with a peak finder, and found to be significantly different compared to control in both the aorta and renal arteries obtained from PID animals.
To investigate the effect of antihypertensive treatment (enalapril and hydrochlorothiazide) on gap junction communication, spontaneously hypertensive rats (SHR) were subject to a 2-week intensive angiotensin converting enzyme inhibitor treatment. This treatment resulted in significant vascular structural regression. All vessels (aorta, renal, mesenteric) from treated animals had greater proportions of power in the VLF window, with both the mesenteric and renal vessels exhibiting a primary peak of oscillation around 0.2 Hz; whereas the aorta had a primary peak at 0.12 Hz. Investigating altered gap junction communication with the gap junction blocker 18-α glycyrrhetinic acid, revealed that vascular bed location was the determining factor of vasomotion response. Immunoblotting did not indicate differences in connexin 43, a major gap junction protein in the vascular smooth muscle.
These studies suggest that vasomotion characteristics can be used as a method of vascular phenotype investigation; vasomotion characteristics were significantly different in vessels taken from PID and hypertensive animals as compared to control and antihypertensive-treated animals, respectively.Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2008-09-26 11:39:44.043
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Tsai, Shang-Lin, and 蔡尚霖. "Characteristics of ZnO nanorods grown by hydrothermal method on different substrates." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/395zk5.
Full textAbstract:
碩士國立暨南國際大學
應用材料及光電工程學系
102
In this thesis, we used a non-vacuum method to produce a seed layer of ZnO nanorods which accretes on the various types of conductive and non-conductive substrate. The main ZnO NPs were grown hydrothermally with low temperature and pressure. Since we grow ZnO NRs by the hydrothermal method, the recrystallization status can be observed. We can monitor the type of crystallization and the quality of the ZnO NRs. For example, when we add the NaOH in the growing environment, the shape the ZnO become flower-like structure, which is distinct from the ZnO NRs. The experimental results indicate that, ZnO nanorods can adhere easily because of the seed layer on the substrate. We applied different experimental parameters to grow the ZnO seed layer and the ZnO NRs. To examine the experimental condition, ZnO nanorods with various structures can be observed by scanning electron microscope (SEM). In addition, we adjust the pH value in hydrothermal environment to observe the growth of ZnO nanorods. Furthermore, we perform X-ray diffraction (XRD),and energy dispersive X-ray spectroscopy (EDX) to monitor the material properties of the ZnO NRs.
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Chen, Hsieh Liang, and 陳協良. "Signal Characteristics and Enhancement of Seismic Method for Detecting Underground Cavity." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/26443213314808046583.
Full textAbstract:
碩士逢甲大學
土木及水利工程研究所
87
The purpose of this research was to discuss the signal characteristics and feasibility of various approaches of seismic method for detecting underground cavity by performing a series of numerical simulations as well as lab tests. The primary seismic method was Spectral Analysis of Surface Waves Method（SASW）. The main factors for investigation were the generation of proper seismic source, the placement of receivers, the number of times of impact, the effect of the magnitude of the time factor τ, the measurable of underground cavity, the approaches of producing various frequency and amplitudes by impact source, and the methods for processing the records of signal. The numerical simulations were performed through dispersive Green’s function. A series of lab tests were performed in a model box filling with Ottawa sand and in a poured cement plate. The series of lab tests were firstly performed in a model box filling with Ottawa sand to investigate the placement of receivers, the approaches of installing receivers on the surface of sand, and every possible seismic sources like pencils, steel balls, and steel bars, etc. Because of the cohesionless of sand, we poured a cement plate, and put a plastic pipe inside of it with 15 cm height of the center, 1 m in length, 5 cm diameter, and 80 cm away from the edge as a cavity before pouring. When performing the test on cement plate, a steel ball was used as a falling weight impact source and four receivers, two of them were installed on the surface to measure the vertical displacement, and the other two were installed on the surface to measure the horizontal part. The results of tests with Ottawa sand show that the use of coherence coefficient and cross power spectrum as threshold values for data filtering will successfully reduce large fluctuations occurred in the dispersion curve for high frequency range. And the results of tests with cement plate show the use of either fast or slow exponential functions can enhance the existence cavity. The depth of penetration of Rayleigh waves was found to be half of the wavelength of Rayleigh waves when S=D=20 cm in this research.