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Dissertations / Theses on the topic 'Initial parameter'
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Elago, David. "Robust computational methods for two-parameter singular perturbation problems." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1693_1308039217.
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<p>This thesis is concerned with singularly perturbed two-parameter problems. We study a tted nite difference method as applied on two different meshes namely a piecewise mesh (of Shishkin type) and a graded mesh (of Bakhvalov type) as well as a tted operator nite di erence method. We notice that results on Bakhvalov mesh are better than those on Shishkin mesh. However, piecewise uniform meshes provide a simpler platform for analysis and computations. Fitted operator methods are even simpler in these regards due to the ease of operating on uniform meshes. Richardson extrapolation is applied on one of the tted mesh nite di erence method (those based on Shishkin mesh) as well as on the tted operator nite di erence method in order to improve the accuracy and/or the order of convergence. This is our main contribution to this eld and in fact we have achieved very good results after extrapolation on the tted operator finitete difference method. Extensive numerical computations are carried out on to confirm the theoretical results.</p>
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Bichard, James. "Some examples of the spatial evolution of two-parameter processes with non-adapted initial conditions." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3119/.
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The central result of this thesis is an enlargement of filtrations result for the filtration (Fx; x ≥ 0), where Fx = σ{Bys : y ≤ x, s ∈ [0,∞)} and (Bxt; x ∈ R, t ∈ [0,∞)) is a Brownian sheet on a complete probability space. Although this is a fairly straightforward extension of a result presented in [Yor97] for Brownian filtrations, it is of use to us in a couple of applications. The first is a discussion of ‘bridged’ Brownian sheets, in which we try to describe the law of a Brownian sheet which is fixed along some curve in the parameter space. The second application is a study of the spatial evolution of solutions to the stochastic heat equation. We fix a starting point in space, and describe the spatial evolution as driven by an (Fx; x ≥ 0)-adapted noise. Unfortunately, we find that the initial condition is not in F0. If we add this initial information to (Fx; x ≥ 0), the driving noise is no longer a martingale, but our enlargement result allows us to write a semimartingale decomposition, in some sense. We are in fact able to write a system of stochastic differential equations which describe the spatial evolution of solutions, such that each equation is driven by a martingale with respect to this larger filtration.
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Roy, Sayan Basu. "Relaxing persistence of excitation for parameter convergence in adaptive control : an initial excitation based approach." Thesis, IIT, Delhi, 2019. http://eprint.iitd.ac.in:80//handle/2074/8067.
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McWilliam, Noel J. "Parameter identification and initial state reconstruction for linear and non-linear systems with applications to anti-cancer drug pharmacokinetics and gap-phase forest canopy models." Thesis, University of Warwick, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399502.
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Cameron, Neil. "Identifying pilot model parameters for an initial handling qualities assessment." Thesis, University of Glasgow, 2002. http://theses.gla.ac.uk/4824/.
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It is desirable to make an assessment of likely handling qualities to identify any deficiencies in a helicopter control system at an early stage in the design process before an expensive and potentially dangerous prototype is constructed. Inverse simulation offers a modelling technique that can be used for generating the data needed for such an assessment. Inverse simulation differs from conventional forward simulation in that the vehicle flight path is the input and the state and control time histories required for the task are generated. The inverse algorithm however, does not account for the pilot contribution to the flight data, thus the work herein demonstrates a method whereby this can be achieved. To incorporate pilot effect into the Helinv generated data, the latter is applied as the command signal to the Man-Machine Control System (MMCS), which is a closed loop system encompassing the helicopter vehicle dynamics and a model of the pilot known as the Precision Pilot Model (PPM). The PPM Human Equalisation Characteristics (REC) are determined via a constrained optimisation technique and the pilot effect is added in the system output. Validation of this technique is achieved through a case study whereby several operators, with different levels of experience, pilot a reduced order Puma helicopter model through a predefined mission task in a flight simulator constructed during the project. The equalisation characteristics are then determined for each pilot and compared with those generated using Helinv. A handling qualities assessment is presented for both sets of results and conclusions concerning the validity of Helinv with additional pilot effect finally drawn.
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Rossouw, Abrie. "Determining the initial design parameters of a radial-inflow turbine / Abrie Rossouw." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1373.
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McCabe, John Michael Arnold Christopher J. "Parameters to facilitate the creation of initial response capsules for survivors of prodigious disasters." Auburn, Ala., 2006. http://hdl.handle.net/10415/1299.
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Donley, Stephen John. "Initial identification and investigation of parameters for choosing the most appropriate rapidly assembled or deployable structure." Thesis, Springfield, Va. : Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA393183.
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Lainio, Nellie, and Christian Östanbäck. "Kalkylanalys av stambyten : En jämförelse av stambytesprojekt för att belysa viktiga parametrar vid initial kalkylering." Thesis, KTH, Byggteknik och design, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232169.
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Sweden’s real estate portfolio has a major renovation requirement. A large part of the renovations that need to be carried out are pipe replacement projects. These are major projects and not all housing associations are aware of the extent financial consequences it brings. Therefore, planning in the economy throughout the project are important. This thesis aims at seeing what affects a production estimate to differ from the actual final cost.ÅF infrastructure division thought that their calculations of the estimated cost for production too often differs to the actual final cost. At a first meeting with ÅF, it appeared that there has been discussion and thought for solutions to the problem for some time. The thesis is based on 3 issues that will provide answers on how to make a better production estimate.In order to answer the questions, project managers have been interviewed and literature has been studied. The assigned reference objects have been analyzed and compared in tables. This thesis has resulted in the insight of that the project managers at ÅF are relatively good at estimating the original cost of what the contractor produces for the pipe replacement projects. After the analysis, recommendations have been presented that can be developed and implemented in the ÅF approach to calculate their estimated cost of production even better. By calculating the costs that are not included in the original cost for the contractors in a more methodical manner, based on experience, the production cost can be optimized.The work has been going on for a limited time with delimitations and a selection of projects. The results presented in the report should be applied with caution and awareness about the differences in the projects.
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Liu, Jiaping. "A Study on Distribution Learning of Generative Adversarial Networks." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41250.
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This thesis is an exploration of the properties of shallow generative adversarial networks (GANs). We focus on several aspects of GANs to investigate the learnability of a class of distributions using shallow GANs and conduct experiments to explore the influence of these aspects on the performance of the GAN models. We identify and analyze several pathological phenomena in theoretical analysis and experiments, and propose potential solutions for them.
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Munzarová, Markéta. "Quantum chemical calculations of EPR parameters for transition metal complexes." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9587938.
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Day, Stephen Paul. "Approaches to ab-initio GIPAW-DFT calculations of NMR parameters in disordered materials." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/78781/.
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The use of ab initio Density Functional Theory (DFT) to calculate key Nuclear Magnetic Resonance (NMR) parameters has been shown to be very successful in a variety of cases. These calculations allow one to extract meaningful data from NMR measurements by providing a foundation for spectral peak assignment. However, first principle calculations for disordered systems, typically based on a single realisation of the disorder, are inadequate if the NMR parameters depend sensitively on the location of the disordered species. In this thesis, a number of different approaches for characterising disorder in solids are presented. The aim of which is to overcome current challenges regarding the computational cost of conventional supercell approaches that make it difficult to perform a direct study of the complete configurational ensemble for any supercell with a sufficient simulation cell. A case study is presented for the Ge-based apatite La7.5Ca2.5Ge6O25.75 that shows that the number of configurations one needs to consider can be vastly reduced by exploiting the symmetry of the system over a wholly enumerative approach, although exhaustive statistical averaging of the atomic positions required to reproduce the atomic resolution afforded by the solid-state NMR (ssNMR) measurement makes this problem intractable via this methodology. The sodium potassium niobate system (NaxK1-xNbO3) is studied across a series of compositions between the ordered KNbO3 and NaNbO3 end-members. This novel material exhibits purely atomic position / permutation disorder that is reflected in initial 23Na and 93Nb MAS NMR studies, but the true explanation of the disorder described by this data is not well understood. The Special Quasi-random Structure (SQS) approach to studying this disorder is presented as a computationally cheaper alternative to the supercell approach. It is noted that further studies are required to assess whether this is an adequate description of the NaxK1-xNbO3 system due the complications of modelling the complex tilting patterns exhibited by these structures. A combined ssNMR and GIPAW-DFT approach is reported to resolve the complex disorder within the vaterite polymorph of calcium carbonate. The computational data for the various structural candidates in the literature is utilised to simulate the highly sensitive DOR data, thereby elevating the predictive capability of this complementary approach to substantiate the stacking model of vaterite that views the material as a dynamic system under ambient conditions.
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Johnson, Clive. "The use of periodic ab initio methods in the determination of NMR quadrupole parameters." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270038.
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Campbell, Jesse. "A discourse analysis of the initial negotiation of therapeutic parameters and the development of new problem descriptions, in two different psychological therapies." Thesis, University of East London, 2009. http://roar.uel.ac.uk/3730/.
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This thesis uses discourse analysis to compare systemic and cognitive-behavioural therapies, in terms of, the process of initial negotiation between client and therapist over therapeutic parameters, and the development of new problem descriptions. It also compares the theoretical description of the application of each therapy with the actual application of each therapy. The first section develops an argument for an approach to process research which is based on bottom-up naturalistic analysis of the way language is used in therapy. In doing so, it highlights the limitations of the positivist process and outcome research traditions, and provides an account of the range of established approaches to discourse analysis. The approach to analysis used draws on traditions of conversation analysis and discourse analysis. Several sub-themes are discussed within each of the two main analytic foci; negotiation of parameters and development of problem descriptions. The final section summarises the findings according to the analytic foci, and discusses the implications of the findings for clinical practice, and topical professional and political developments. Further indicated research and validity issues are also discussed.
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Nyberg, Anton, and Dennis Svensson. "Jämförelse av smörjmedel från olika tillverkare genom undersökning av kritiska parametrar." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-96553.
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Nästan alla maskiner och fordon behöver smörjning i någon form. Cellulosatorkar tillverkade av Andritz AB är inte något undantag. Dessa maskiner innehåller en mängd olika komponenter som är i behov av smörjning. För Andritz som har kunder över hela världen uppstår ett problem när dessa kunder söker alternativ till de smörjmedel som Andritz i första hand rekommenderar. Detta arbete har till syfte att kunna ge olika alternativ på smörjmedel oberoende från vilken tillverkare. I arbetet har en lista tagits fram med alternativa smörjmedel från olika smörjmedelstillverkare. Arbetet innefattar även de kritiska faktorer hos smörjmedel som måste uppfyllas för att de ska kunna ersätta varandra. En livstidsanalys, eftersmörjningsintervall och initial fettfyllning för hårt belastade rullager i en av Andritz cellulosatork ingår även i arbetet.
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Weiss, Paula. "Ab initio and Direct Quasiclassical Trajectory Study of the F + CH₄ → HF + CH₃ and F + C₂H₆ → HF + C₂H₅ Reactions." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35340.
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The reparametization of semiempirical Hamiltonians is an emerging method used
in direct dynamics studies. The use of semiempirical Hamiltonians in direct dynamics
studies diminishes the computational cost of trajectory calculations and negates the need
for an analytical potential energy surface when performing reaction dynamics studies.
The reparametization of semiempirical Hamiltonians increases the agreement with
experiment and high level ab initio theory. We have chosen to create one set of new
parameters that apply to two related reactions, F + CH4 â HF + CH3 and F + C2H6 â HF
+ C2H5. We have performed an electronic structure study for these reactions. The ab
initio data obtained from the electronic structure study is then used as the reference for a
reparametization of the PM3 Hamiltonian. The reparametization has improved the ab
initio and PM3 reaction energy and potential energy surface scan agreement. This new
set of parameters for PM3 (SRP-PM3) is used to perform a direct quasiclassical trajectory
study of the reactions. The vibrational and rotational HF distributions calculated using
SRP-PM3 are compared with experiments. We have observed an improvement in the
agreement with experimental vibrational distributions but have seen no change in the
rotational distributions.<br>Master of Science
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Alexander, Craig L. "Ab initio scattering from random discrete charges and its impact on the intrinsic parameter fluctuations in nano-CMOS devices." Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426514.
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Тартагашев, М. Д., Олександра Іванівна Карінцева, Александра Ивановна Каринцева та Oleksandra Ivanivna Karintseva. "Максимальный прогиб шарнирно опертой балки от произвольно расположенной нагрузки". Thesis, Сумский государственный университет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/39913.
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Rouf, S. A. (Syed Awais). "Paramagnetic NMR chemical shift theory:combined ab initio/density-functional theory method." Doctoral thesis, University of Oulu, 2017. http://urn.fi/urn:isbn:9789526216850.
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Abstract In this thesis, the classic Kurland-McGarvey theory for the nuclear magnetic resonance (NMR) chemical shift is presented in a modern framework for paramagnetic systems containing one or more unpaired electrons. First-principles computations are carried out for the NMR shielding tensors in paramagnetic transition-metal complexes. A combined ab initio/density-functional theory (DFT) approach is applied to obtain the necessary electron paramagnetic resonance (EPR) property tensors, i.e., the g-tensor, zero-field splitting tensor (D) and hyperfine coupling tensors (A). In DFT, both the generalised-gradient approximation and hybrid DFT are applied to calculate A. The complete active space self-consistent field theory (CASSCF) and N-electron valence-state perturbation theory (NEVPT2) are applied to calculate the g- and D-tensors. Scalar relativistic effects are included at the second-order Douglas-Kroll-Hess level for the g- and D-tensors and, for A, at the fully relativistic four-component matrix-Dirac-Kohn-Sham level. This methodology is applied to study ¹³C and ¹H chemical shifts and shielding anisotropies in a series of Co(II) pyrazolylborate complexes, a Cr(III) quinolyl-functionalised cyclopentadienyl complex, Ni(II) acetylacetonate complexes and various metallocenes. The results obtained from these calculations are generally in a good agreement with the experimental data, in some cases, for Ni(II) complexes, allowing to correct the experimental spectral signal assignment. CASSCF/NEVPT2 computations (especially for the D-tensor) are more accurate than DFT, which is useful for the purpose of obtaining the NMR chemical shifts. The computational results obtained are dependent on the choice of molecular geometry (experimental X-ray or computationally optimised), wavefunction used for g and D (CASSCF or NEVPT2), DFT functional for A, and the quality of the basis sets. The locally dense basis method used for the CASSCF/NEVPT2 computations is less expensive and gives equally good results for g and D as fully balanced basis sets. The scalar relativistic influences are usually small for g and D, but are large for A. Due to that, scalar relativistic effects are important for the chemical shift and shielding anisotropy, especially for carbon nuclei. These first-principles computations based on combined ab initio/DFT methodology are promising for the treatment of important electron correlation and scalar relativistic effects in the calculation of pNMR chemical shifts and shielding anisotropies. This work provides a straightforward platform for further development of pNMR shielding theory in terms of first-principles wavefunctions, as well as for applications in current problems in bio- and materials sciences, including low-temperature experiments<br>Original papers The original papers are not included in the electronic version of the dissertation. Vaara, J., Rouf, S. A., & Mareš, J. (2015). Magnetic Couplings in the Chemical Shift of Paramagnetic NMR. Journal of Chemical Theory and Computation, 11(10), 4840–4849. https://doi.org/10.1021/acs.jctc.5b00656 Rouf, S. A., Mareš, J., & Vaara, J. (2015). ¹H Chemical Shifts in Paramagnetic Co(II) Pyrazolylborate Complexes: A First-Principles Study. Journal of Chemical Theory and Computation, 11(4), 1683–1691. https://doi.org/10.1021/acs.jctc.5b00193 Rouf, S. A., Jakobsen, V. B., Mareš, J., Jensen, N. D., McKenzie, C. J., Vaara, J., & Nielsen, U. G. (2017). Assignment of solid-state ¹³C and ¹H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations. Solid State Nuclear Magnetic Resonance, 87, 29–37. https://doi.org/10.1016/j.ssnmr.2017.07.003 Rouf, S. A., Mareš, J., & Vaara, J. (2017). Relativistic Approximations to Paramagnetic NMR Chemical Shift and Shielding Anisotropy in Transition Metal Systems. Journal of Chemical Theory and Computation, 13(8), 3731–3745. https://doi.org/10.1021/acs.jctc.7b00168 http://jultika.oulu.fi/Record/nbnfi-fe201801031039
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Camur, Yakup. "A Computational Study On Nitrotriazine Derivatives." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609362/index.pdf.
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In this study, all possible mono, di and trinitro-substituted triazine compounds as potential candidates for high energy density materials (HEDMs) have been investigated by using quantum chemical treatment. Computational chemistry is a valuable tool for estimating the potential candidates for high energy density materials. Geometric features and electronic structures of these nitro-substituted triazines have been systematically studied using ab initio and density functional theory (DFT, B3LYP) at the level of 6-31G(d,p), 6-31+G(d,p), 6-311G(d,p), 6-311+G(d,p), cc-pVDZ. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that 2G derivative with the predicted densities of 1.9 g/cm3, detonation velocities of 9.43 km/s, and detonation pressures of 40.68 GPa may be novel potential candidates of high energy density materials (HEDMs). Moreover, thermal stabilities were investigated by calculating bond dissociation energies (BDE) at B3LYP/6-311G(d,p) level. Detailed molecular orbital (MO) investigation have been performed on these potential HEDMs.
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Negodaev, Igor. "The calculation of the thermal dependency of the magnetic susceptibility in extended systems with ab initio electronic structure parameters." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/31934.
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La tesi estudia l'acoblament magnètic en sistemes de diferent dimensionalitat amb mètodes multireferencials. L’objectiu principal del treball és calcular propietats macroscòpiques, com la dependència de la susceptibilitat magnètica amb la temperatura, a partir de la constant d'intercanvi magnètic calculada, J. Aquest paràmetre microscòpic quantifica la interacció magnètica entre dos centres i es pot extreure per ajust de la corba de susceptibilitat experimental en sistemes finits però això no és possible en sistemes magnètics infinits com cadenes o capes 2D.
L’estratègia del treball és calcular J en petits clusters i simular els sistemes estesos utilitzant aquesta J en l’Hamiltonià de Heisenberg en models de 8 a 16 centres. Amb l’espectre obtingut es construeixen les corbes de dependència tèrmica de la susceptibilitat magnètica que, comparades amb les experimentals, donen la possibilitat de quantificar les interaccions magnètiques dels materials estudiats a nivell microscòpic.
S'han estudiat diferents tipus de sistemes estesos com cadenes i xarxes hexagonals, on els centres magnètics són ions de metalls de transició.<br>The thesis studies the magnetic coupling in systems of different dimensionality, by using multireference methods. The aim of the work is to determine macroscopic properties such as the thermal dependency of magnetic susceptibility, from the calculated magnetic exchange constant J. This microscopic parameter quantifies the magnetic interaction between two magnetic sites and can be extracted from the experimental susceptibility curve in finite systems. However this extraction is not possible in extended magnetic systems such as chains or 2D-layers.
The strategy followed consists in calculating J in small clusters and in simulating the extended systems by introducing the calculated J in the Heisenberg Hamiltonian of 8 to 16 site models. From the spectrum, the thermal dependency of the magnetic susceptibility is the calculated. When compared to the experimental one, this curve gives a quantification of the magnetic interactions of the studied materials at the microscopic level.
We have studied different types of extended systems such as chains and hexagonal lattices, where the magnetic sites are transition metal ions.
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SLIWINSKI, JEAN-FRANCOIS. "Caracteristiques cliniques et paracliniques d'une population de 165 patients atteints de sarcoidose : valeur predictive de differents parametres biologiques initiaux." Lyon 1, 1988. http://www.theses.fr/1988LYO1M285.
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Turchetto, Arianna <1988>. "Determinazione di parametri di riga di inquinanti atmosferici mediante spettroscopia infrarossa a diodo laser e calcoli ab initio." Master's Degree Thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3370.
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Michels, Yves. "Reconstruction tomographique d'objets déformables pour la cryo-microscopie électronique à particules isolées." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD031/document.
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La cryo-microscopie électronique à particules isolées est une modalité d’imagerie permettant d’estimer la structure 3D de molécules. L’obtention d’un volume 3D est effectué par des algorithmes de reconstruction tomographique après acquisition par un microscope électronique à transmission d’un ensemble d’images de projection de l’objet observé. Les méthodes de reconstruction tomographique existantes permettent de déterminer la structure des molécules avec des résolutions proches de l’angström. Cependant la résolution est dégradée lorsque les molécules observées sont déformables. Les travaux réalisés au cours de cette thèse contribuent au développement de méthodes de traitement informatique des données (projections) dans le but de prendre en compte les déformations de l’objet observé dans le processus de reconstruction tomographique ab initio. Les problématiques principales abordées dans ce mémoire sont l’estimation des paramètres de projection basée sur la réduction de dimension non-linéaire, la détection des arêtes erronées dans les graphes de voisinages pour l’amélioration de la robustesse au bruit des méthodes de réduction de dimension, et la reconstruction tomographique basée sur un modèle paramétrique du volume<br>Single particle cryo-electron microscopy is a technique that allows to estimate the 3D structure of biological complex. The construction of the 3D volume is performed by computerized tomography applied on a set of projection images from transmission electron microscope. Existing tomographic reconstructionalgorithms allow us to visualize molecular structure with a resolution around one angstrom. However the resolution is degraded when the molecules are deformable. This thesis contributes to the development of signal processing method in order to take into account the deformation information of the observed object for the ab initio tomographic reconstruction. The main contributions of this thesis are the estimation of projection parameters based on non-linear dimensionreduction, the false edges detection in neighborhood graphs to improve noise robustness of dimension reduction methods, and tomographic reconstruction based on a parametric model of the volume
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Ferchichi, Olfa. "Étude des propriétés structurales et spectroscopiques de peroxydes aux niveauxDFT et ab initio." Thesis, Reims, 2020. http://www.theses.fr/2020REIMS017.
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Les travaux présentés dans ce manuscrit sont consacrés à l’étude des paramètres structuraux et des spectres IR et UV des trois peroxydes défiant toute description théorique précise pendant plus que trente ans.Le premier résultat atteint dans cette thèse montre que le désaccord entre les expérimentateurs et les théoriciens concernant l'angle de torsion COOC de diméthyl peroxyde s’explique par une structure dynamique avec un mouvement de torsion très lent. Une deuxième étude a été réalisée sur la molécule FOOF pour laquelle les théoriciens ont échoué pendant des décennies à obtenir la bonne structure d'équilibre. Nous avons alors réussi de montrer que la vraie raison est liée à la planéité de la surface d'énergie potentielle, conduisant à des mouvements de grande amplitude. La structure d'équilibre doit être donc moyennée par la vibration pour obtenir des longueurs de liaison précises. La dernière étude est menée sur le peroxyde de chlore, ClOOCl, l'une des molécules clés contribuant à l'appauvrissement de l'ozone stratosphérique. Le premier résultat montre que la structure de ClOOCl doit être moyennée par la vibration tout en incluant les effets de la corrélation core-valence et les effets relativistes pour améliorer les résultats et avoir plus de précision. Le deuxième résultat prouve que la décomposition de ClOOCl en O2 + 2Cl sur les surfaces de l'état excité ne se produit pas en deux étapes, mais suit un mécanisme concerté. Finalement, nous avons demontré que les isomères ClClOO et ClOClO contribuent également à la destruction catalytique de l'ozone. Ces résultats constituent alors une nouvelle découverte sans précédent<br>This PhD research is devoted to the study of the structural parameters and the IR and UV spectra of three peroxides which have been challenging scientists for many decades. The first result achieved in this thesis shows that the disagreement between experimentalists and theorists concerning the COOC torsional angle of dimethyl peroxide could be explained by a dynamic structure with a very slow torsional movement. A second study was carried out on the FOOF molecule for which theorists had failed, for decades, to obtain an accurate equilibrium structure. We successfully demonstrated that the true reason is related to the flatness of the potential energy surface, leading to large-amplitude motions. The equilibrium structure must therefore be averaged vibrationally to obtain accurate bond lengths. The last study concerns chlorine peroxide, ClOOCl, one of the key molecules contributing to stratospheric ozone depletion. The first result shows that the structure of ClOOCl not only needs to be averaged vibrationally but that core-valence correlation and relativistic effects must also be accounted for. The second result proves that the decomposition of ClOOCl into O2 + 2Cl on excited state surfaces does not occur in two steps, but follows a concerted mechanism. It has finally been demonstrated that the isomers ClClOO and ClOClO also contribute to the catalytic destruction of ozone. These results represent a completely new and unprecedented discovery
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Jabri, Atef. "Spectroscopie à haute résolution de molécules organiques d'intérêt astrophysique et atmosphérique contenant un ou deux rotateurs internes." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC218/document.
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Durant ma thèse, j'ai étudié cinq molécules d'intérêt astrophysique et atmosphérique en utilisant la spectroscopie à haute résolution dans les régions spectrales microonde, millimétrique et infrarouge lointain. Il s'agit du thioformate de méthyleCH3SCH(O), de sulfure de diméthyle (CH3)2S, de méthacroléine CH3C(CHO)CH2, d'acétate de vinyle CH3C(O)OCHCH2 et d'acétate de butadiènyle CH3C(O)O(CH)3CH2. Tous les spectres de ces molécules étudiées possèdent comme point en commun un mouvement de grande amplitude de rotation interne de un ou deux groupes méthyles CH3 qui aboutit à un dédoublement des raies. Ainsi, une modélisation spectrale spécifique pour chaque molécule est nécessaire afin de reproduire leurs spectres à la précision expérimentale et déterminer un ensemble de paramètres spectroscopiques à trés haute précision.Les molécules de thioformate de méthyle et de sulfure de diméthyle sont potentiellement détectables dans le milieu interstellaire (MIS) étant donné qu'elles sont les analogues soufrés du formiate de méthyle CH3OCH(O) et du diméthyle éther (CH3)2O, deux molécules relativement abondantes dans le MIS. Nous avons effectué pour la première fois une étude spectroscopique complète au laboratoire pour ces molécules, étude qui est indispensable pour fournir aux astrophysiciens des listes de fréquences et d'intensités de raies qui leur permettront dans le futur de détecter ces espèces et d'exploiter les spectres observés dans le MIS avec les radiotélescopes au sol et/ou embarqués. La méthacroléine est l'un des composés de l'oxydation des isoprènes émis dans la troposphère et elle joue un rôle important dans la chimie de l'atmosphère terrestre. Notre travail dans le domaine microonde a permis de mieux comprendre sa structure moléculaire et sa stabilité.Enfin, deux molécules d'esters carboxyliques ont été étudiées pendant ma thèse dans les régions spectrales des microondes comprises entre 2 et 40 GHz. J'ai complété l'étude du spectre microonde de l'acétate de vinyle CH3COOCHCH2 et j'ai étudié pour la première fois le spectre de deux isomères d'acétate de butadiènyle CH3COO (CH)3CH2. Outre que la validation des calculs de chimie quantiques effectués, cette étude a permis une meilleure compréhension de l'évolution des valeurs de barrières de potentielles entravant la rotation interne en fonction de la structure chimique<br>During my thesis, I studied five molecules of astrophysical and atmospheric interest using high-resolution spectroscopy in the spectral regions of microwave, millimeterwave and far infrared. These molecules are methyl thioformate CH3SCH(O), dimethyl sulfide(CH3)2S, methacrolein CH3C(CHO)CH2, vinyl acetate CH3C(O)OCHCH2 and butadienylacetate CH3C(O)O(CH)3CH2. All of their spectra have in common a large amplitude motion,the internal rotation of the methyl group(s) CH3 leading to a splitting of the lines. Then, iused a specific theoretical modeling for each molecule in order to reproduce their spectra at experimental accuracy and to determine a set of spectroscopic parameters with very highprecision.Methyl thioformate and dimethyl sulfide are potentially detectable in the interstellar medium(MIS) as they represent the sulfur analogues of methyl formate CH3OCH(O) and dimethylether (CH3)2O, two molecules relatively abundant in the MIS. I performed a complete spectroscopic study in laboratory in order to provide astrophysicists with lists of frequencies and intensities of lines, which enable them to exploit the observed spectra in the MIS.Methacrolein is one of the compounds of the oxidation of isoprene emitted in the troposphereand plays an important role in the chemistry of the earth's atmosphere. Our studies in themicrowave range enables us to better determine its molecular structure which is useful inorder to better understand its stability. Finally, two ester molecules have been studied in the microwave spectral regions between2 and 40 GHz. The study of the microwave spectrum of vinyl acetate CH3COOCHCH2 is completed and the spectrum of two isomers of butadienyl acetate CH3COO(CH)3CH2 is studied for the first time.In addition to the validation of quantum chemistry calculations, this study allowed a better under standing of the evolution of potential barrier values du to internal rotation as a function of chemical structure
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Jabri, Atef. "Spectroscopie à haute résolution de molécules organiques d'intérêt astrophysique et atmosphérique contenant un ou deux rotateurs internes." Electronic Thesis or Diss., Sorbonne Paris Cité, 2016. https://theses.md.univ-paris-diderot.fr/JABRI_Atef_2_va_20161128.pdf.
Full textAbstract:
Durant ma thèse, j'ai étudié cinq molécules d'intérêt astrophysique et atmosphérique en utilisant la spectroscopie à haute résolution dans les régions spectrales microonde, millimétrique et infrarouge lointain. Il s'agit du thioformate de méthyleCH3SCH(O), de sulfure de diméthyle (CH3)2S, de méthacroléine CH3C(CHO)CH2, d'acétate de vinyle CH3C(O)OCHCH2 et d'acétate de butadiènyle CH3C(O)O(CH)3CH2. Tous les spectres de ces molécules étudiées possèdent comme point en commun un mouvement de grande amplitude de rotation interne de un ou deux groupes méthyles CH3 qui aboutit à un dédoublement des raies. Ainsi, une modélisation spectrale spécifique pour chaque molécule est nécessaire afin de reproduire leurs spectres à la précision expérimentale et déterminer un ensemble de paramètres spectroscopiques à trés haute précision.Les molécules de thioformate de méthyle et de sulfure de diméthyle sont potentiellement détectables dans le milieu interstellaire (MIS) étant donné qu'elles sont les analogues soufrés du formiate de méthyle CH3OCH(O) et du diméthyle éther (CH3)2O, deux molécules relativement abondantes dans le MIS. Nous avons effectué pour la première fois une étude spectroscopique complète au laboratoire pour ces molécules, étude qui est indispensable pour fournir aux astrophysiciens des listes de fréquences et d'intensités de raies qui leur permettront dans le futur de détecter ces espèces et d'exploiter les spectres observés dans le MIS avec les radiotélescopes au sol et/ou embarqués. La méthacroléine est l'un des composés de l'oxydation des isoprènes émis dans la troposphère et elle joue un rôle important dans la chimie de l'atmosphère terrestre. Notre travail dans le domaine microonde a permis de mieux comprendre sa structure moléculaire et sa stabilité.Enfin, deux molécules d'esters carboxyliques ont été étudiées pendant ma thèse dans les régions spectrales des microondes comprises entre 2 et 40 GHz. J'ai complété l'étude du spectre microonde de l'acétate de vinyle CH3COOCHCH2 et j'ai étudié pour la première fois le spectre de deux isomères d'acétate de butadiènyle CH3COO (CH)3CH2. Outre que la validation des calculs de chimie quantiques effectués, cette étude a permis une meilleure compréhension de l'évolution des valeurs de barrières de potentielles entravant la rotation interne en fonction de la structure chimique<br>During my thesis, I studied five molecules of astrophysical and atmospheric interest using high-resolution spectroscopy in the spectral regions of microwave, millimeterwave and far infrared. These molecules are methyl thioformate CH3SCH(O), dimethyl sulfide(CH3)2S, methacrolein CH3C(CHO)CH2, vinyl acetate CH3C(O)OCHCH2 and butadienylacetate CH3C(O)O(CH)3CH2. All of their spectra have in common a large amplitude motion,the internal rotation of the methyl group(s) CH3 leading to a splitting of the lines. Then, iused a specific theoretical modeling for each molecule in order to reproduce their spectra at experimental accuracy and to determine a set of spectroscopic parameters with very highprecision.Methyl thioformate and dimethyl sulfide are potentially detectable in the interstellar medium(MIS) as they represent the sulfur analogues of methyl formate CH3OCH(O) and dimethylether (CH3)2O, two molecules relatively abundant in the MIS. I performed a complete spectroscopic study in laboratory in order to provide astrophysicists with lists of frequencies and intensities of lines, which enable them to exploit the observed spectra in the MIS.Methacrolein is one of the compounds of the oxidation of isoprene emitted in the troposphereand plays an important role in the chemistry of the earth's atmosphere. Our studies in themicrowave range enables us to better determine its molecular structure which is useful inorder to better understand its stability. Finally, two ester molecules have been studied in the microwave spectral regions between2 and 40 GHz. The study of the microwave spectrum of vinyl acetate CH3COOCHCH2 is completed and the spectrum of two isomers of butadienyl acetate CH3COO(CH)3CH2 is studied for the first time.In addition to the validation of quantum chemistry calculations, this study allowed a better under standing of the evolution of potential barrier values du to internal rotation as a function of chemical structure
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Sebastianutti, Marco. "Geodesic motion and Raychaudhuri equations." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18755/.
Full textAbstract:
The work presented in this thesis is devoted to the study of geodesic motion in the context of General Relativity. The motion of a single test particle is governed by the geodesic equations of the given space-time, nevertheless one can be interested in the collective behavior of a family (congruence) of test particles, whose dynamics is controlled by the Raychaudhuri equations. In this thesis, both the aspects have been considered, with great interest in the latter issue. Geometric quantities appear in these evolution equations, therefore, it goes without saying that the features of a given space-time must necessarily arise. In this way, through the study of these quantities, one is able to analyze the given space-time. In the first part of this dissertation, we study the relation between geodesic motion and gravity. In fact, the geodesic equations are a useful tool for detecting a gravitational field. While, in the second part, after the derivation of Raychaudhuri equations, we focus on their applications to cosmology. Using these equations, as we mentioned above, one can show how geometric quantities linked to the given space-time, like expansion, shear and twist parameters govern the focusing or de-focusing of geodesic congruences. Physical requirements on matter stress-energy (i.e., positivity of energy density in any frame of reference), lead to the various energy conditions, which must hold, at least in a classical context. Therefore, under these suitable conditions, the focusing of a geodesics "bundle", in the FLRW metric, bring us to the idea of an initial (big bang) singularity in the model of a homogeneous isotropic universe. The geodesic focusing theorem derived from both, the Raychaudhuri equations and the energy conditions acts as an important tool in understanding the Hawking-Penrose singularity theorems.
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Коптєва, Наталія Юріївна. "Автоматизована система переміщення виробів мобільними транспортними засобами". Магістерська робота, Київський національний університет технологій та дизайну, 2021. https://er.knutd.edu.ua/handle/123456789/19243.
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Дипломна магістерська робота присвячена підвищенню ефективності роботи транспортно-складської системи шляхом автоматизації виконання операцій прийому виробів на склад і відвантаження їх зі складу за допомогою мобільних транспортних засобів. Запропоновано використання робастної системи управління рухом мобільних транспортних засобів при автоматизації переміщення вантажів у транспортно-складській системі, яка дозволяє усунути недоліки існуючих автоматизованих систем переміщення виробів. Запропоновано і досліджено імітаційну модель автоматизованого складу, алгоритм його функціонування та автоматизовану систему управління рухом мобільного транспортного засобу по заданій трасі. Показано підвищення ефективності функціонування транспортно-складських систем шляхом використання мобільних керованих транспортних засобів і автоматизації операцій переміщення виробів при використанні методу синтезу лінійних регуляторів з інтервальними параметрами, що заснований на побудові областей розширеного D-розбиття у діапазоні вибору коефіцієнтів регулятора.<br>Дипломная магистерская работа посвящена повышению эффективности работы транспортно-складской системы путем автоматизации выполнения операций приёма изделий на склад и отгрузки их со склада с помощью мобильных транспортных средств. Предложено использование робастной системы управления движением мобильных транспортных средств при автоматизации перемещения грузов в транспортно-складской системе, позволяющей устранить недостатки существующих автоматизированных систем перемещения изделий. Предложены и исследованы имитационная модель автоматизированного склада, алгоритм его функционирования и автоматизированная система управления движением мобильного транспортного средства по заданной трассе. Показано повышение эффективности функционирования транспортно-складских систем путем использования мобильных управляемых транспортных средств и автоматизации операций перемещения изделий при использовании метода синтеза линейных регуляторов с интервальными параметрами, основанного на построении областей расширенного D-разбиения в диапазоне выбора коэффициентов регулятора.<br>The master's thesis is devoted to improving the efficiency of the transport and warehouse system by automating the operations of receiving products at the warehouse and shipping them from the warehouse using mobile vehicles. The use of a robust control system for the movement of mobile vehicles is proposed for automating the movement of goods in a transport and warehouse system, which makes it possible to eliminate the disadvantages of existing automated systems for moving products. A simulation model of an automated warehouse, an algorithm for its functioning and an automated control system for the movement of a mobile vehicle along a given route are proposed and investigated. An increase in the efficiency of the functioning of transport and warehouse systems is shown by using mobile controlled vehicles and automating the operations of moving products when using the method of synthesis of linear controllers with interval parameters, based on the construction of regions of extended D-partitioning in the range of choice of controller coefficients.
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Chiang, Wen Shin, and 蔣文心. "Parameter Identification for Parabolic Initial-boundary Value Problem." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/53836384016955784570.
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Li, Chia-Chi, and 李佳祁. "Effective Initial Guess Methods for Parameter Estimation in Ordinary Differential Equation Models." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/55981039748932632151.
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碩士<br>大同大學<br>化學工程學系(所)<br>97<br>The success of parameter estimation of ordinary differential equations usually hinges on a set of good initial guess of unknown parameters. Therefore, the aim of this work is to develop a computation method to provide the problem of parameter estimation of ordinary differential equations with these initial estimated parameters.
Our proposed computation method is to minimize an objective function derived from the governing differential equations in which the terms of states and the derivatives of states are provided by the fitted states and the derivative of these fitted states based on the available measurable data. The resulting objective function will be either linear or non-linear with respect to the unknown parameters. We can solve the resulting minimization problem via a linear or nonlinear programming effectively. The obtained estimated parameters can be used as the initial guesses for traditional parameter estimation of ordinary differential equations.
In this work, a batch toluene hydrogenation reaction system, a semi-batch hydrogenation of 3-hydroxypropanol reaction system, a batch dehydrogenation reaction system and a batch etherification of glycerol reaction system were used as testing examples to examine the applicability of the proposed method to find a set of reliable initial guess of unknown parameters for a given problem. For all these testing problems, our method can provide the Luus-Jaakola (LJ) and Easy-fit (EF) methods with a good initial guess of unknown parameters to find out the final estimated parameters properly. However, improvement of the curve fitting method may still need to give better parameter estimation results for ordinary differential equations.
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Sahu, Subal Ranjan. "Numerical Solution for Multi-parameter Singularly Perturbed Initial and Boundary Value Problems." Thesis, 2020. http://ethesis.nitrkl.ac.in/10226/1/2020_PhD_SRSahu_515MA1013_Numerical.pdf.
Full textAbstract:
The main objective of this thesis is to provide some efficient numerical techniques for solving various class of singularly perturbed ordinary and partial differential equations. Generally, in singular perturbation problems(SPPs), a small parameter " known as “singular perturbation parameter” is involved as the coefficient of the highest order derivatives. When the parameter " goes to zero, the perturbations are operative over a thin region, where the dependent variable undergoes very rapid change on the domain of interest. These thin regions are frequently referred as boundary layers. Due to the layer behavior, classical numerical methods are unfit for solving such problems on uniform meshes unless the mesh size is too small in comparison with the ". Also, these approaches on a uniform mesh fails to decrease the maximum pointwise error until the size of mesh and the parameter " have the same order of magnitude. In this context, sufficient mesh points are placed inside the layers to produce a satisfactory numerical approximation. These drawbacks motivate to develop parameter uniform numerical methods, where the maximum pointwise error on discrete maximum norm are independent of the parameter. The theme of this thesis is, therefore, to analyze, improve and optimize some parameter-uniform numerical methods for singularly perturbed initial and boundary value problems. This is accomplished by constructing special type of layer adapted meshes resolving the boundary layers. At first, a hybrid numerical scheme is proposed for singularly perturbed initial value problems on layer adapted meshes like standard Shishkin mesh (S-mesh), Bakhvalov-Shishkin mesh (B-S mesh) and Vulanovic mesh (V-mesh). The finite difference scheme combines the second order central difference scheme on the fine mesh with a modified midpoint upwind scheme on the coarse mesh which provides a second order optimal accuracy for both numerical solution and scaled numerical derivatives. Then, a new spline based hybrid finite difference technique is introduced which combines the cubic spline difference scheme on the fine mesh with a modified midpoint upwind scheme on the coarse mesh. It is observed, that the newly proposed hybrid scheme on the B-S mesh is optimal and more accurate than the one obtained on the S-mesh. Thereafter, two parameter SPP is considered which contains a delay term. Till date no result exists so far for two parameter SPP containing a delay term. To obtain "-uniform convergence for such model, an upwind scheme is used followed by a hybrid scheme on S-mesh. Then, such idea is extended for a singularly perturbed parabolic reaction-diffusion problem with time delay. In this context, an upwind scheme is used for the space direction on S-mesh and B-S mesh and the implicit Euler scheme for the time variable is used on an uniform mesh to approximate the solution. It is shown that the proposed scheme is of first order rate of convergence which is optimal on B-S mesh. To increase the rate of convergence, a hybrid scheme which consists the upwind scheme, midpoint upwind scheme and the second order central difference scheme for the spatial derivatives and the backward Euler scheme on a uniform mesh in the time derivative is developed, which provides a second second order accuracy. Finally, a singularly perturbed parabolic PDE containing both positive and negative shift arguments (small) in the space variable as well as delay in the time variable is approximated by using the upwind finite difference scheme for space on Shishkin type meshes and the backward Euler scheme for time derivative on uniform mesh. It is observed that the proposed method is " uniform convergent and first order with respect to both space and time. Extensive numerical results are shown in shape of tables and figures which confirm the theoretical findings.
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O'Shay, Justin. "Initial Waves from Deformable Submarine Landslides: A Study on the Separation Time and Parameter Relationships." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10991.
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Earthquake and submarine mass failure are the most frequent causes of tsunami waves. While the process of the tsunami generation by earthquakes is reasonably well understood, the generation of tsunami waves during submarine mass failure is not. Estimates of the energy released during a tsunamigenic earthquake and respective tsunami wave draw a clear picture of the efficiency of the tsunami-generating process. However for submarine landslides, this is not as straightforward because the generation process has never been recorded in nature making energy inferences very difficult. Hence the efficiency of submarine landslide as tsunami generators is yet to be conclusively determined. As the result of this uncertainty, different equations, derived from experimental data or theory, result in leading-wave amplitude that vary over 6 orders of magnitude for the same initial slide conditions. To arrive at more robust estimates of the leading-wave characteristics and associated runup, the spatiotemporal dynamics of the coupling between the slide body and water column needs to be investigated. The duration the water surface deformation is coupled with the slide motion is an essential question to shed light on the energy transfer. A parametric study is conducted with the state of-the-art hydrocode iSALE in order to shed light on this complex geophysical event. The mass, viscosity, and depth of submergence are the particular slide parameters varied and their relationship to runup and decoupling time is analyzed.
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LI, JIAN-YU, and 李健瑜. "Exploring the Effect of Initial and Boundary Values on Parameter Estimation of Latent Class Model." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/12762969756160022837.
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碩士<br>國立臺北大學<br>統計學系<br>95<br>Latent Class Model is applied in the area of psychology and science of behaviors. After obtaining the original data, researchers will classify the respondents and analyze mutual relationship among them to get statistical inferences. This paper mainly emphasizes on district data and applies EM(Expectation Maximization) algorithm to estimate the proportions of groups from the latent classes of the respondents.
The simulated data used in parameter estimation is generated by employing Monte Carlo simulation. The empirical experiments were then carried on a total of 160 combinations based on the number of latent classes, the number of questions, the sample size and the initial value approaches. Each experiment is repeated 1000 times then applied EM (Expectation Maximization) algorithm. The algorithm is combined with E-step and M-step. With estimated values and theoretical values to induce its statistical inference including the bias and the Mean Square Error of the underlying parameters.
The empirical results show the negative correlation between sample size and bias. Also, as the number of latent classes increases, the estimation of the underlying parameters gets poor. As for the initial value approaches used herein, the first and the second one demonstrated their superiority. Besides parameter estimation, the multiple regression on five related variables shows significant relationship.
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Yadav, Akash. "Experimental Study and Data Analysis of Water Transport and Their Initial Fate in Through Unsaturated or Dry Bioreactor Columns Filled with Different Porous Media." Thesis, 2013. http://hdl.handle.net/10919/24266.
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The electro-kinetic characteristics of different material bioreactor columns for treating water and waste water are experimentally studied. Separate columns of unsaturated gravels (~6mm) and ball clay were assessed for electro-kinetic characteristics by dosing water at a hydraulic loading rate of 50ml/min and 10ml/min. Similarly locally available organic materials such as sawdust, Moringa oleifera sheets and textile clothe pieces were also empirically analyzed. Size effects of the bio-reactor columns were also studied.
The effluent from textile clothe and gravel reactor respectively showed an increase in pH while a depreciation in pH in the effluent was observed in the Moringa Oleifera reactor and sawdust reactor. This may be due to leaching of acidic organic components for sawdust and Moringa Oleifera . In gravels effluent pH depreciated with increase in flow rate but the general trend of the effluent pH curve showed an initial improvement before it slowed down to an asymptote for a specific constant dosage and height. A multi-parameter stochastic linear model for change in pH as a function of column height, dosage rate, time for specific volume discharge and change in electrical conductivity between influent and effluent was derived. A general stochastic model was also developed to characterize pH change in any bioreactor irrespective of the material media.
Thirty centimeters of gravel exhibited an increase in conductivity with increase in flow rate while conductivity dipped with increasing flow rate when the gravel column height was halved. The measure of organic compounds in water decreased with increasing percolation rate through gravel. The chemical oxygen demand ratio within the gravel improved to unity showing increased containment of organic compounds with time. Organic textile clothes reactor also illustrated increased conductivity with increasing flow but conductivity dipped with increase in column height. For Moringa Oleifera reactors, a dosage of water at 10ml/min showed a significant improvement in conductivity with increase in column height.
An initial depreciation in temperature curve was observed within clay and gravel reactor. With increase in depth there was an increase in temperature within the gravel as the saturation by water improved. In sawdust reactors this was not the trend. A birth process model is proposed to simulated temperature within a bioreactor as a function of time irrespective of any specific material used as bioreactor media.
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Yang, Chi-I., and 楊期壹. "Initial Parameters Problem of WNN based on Particle Swarm Optimization." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/g6a39u.
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Zhang, Taiming. "Simulation of fuzzy dynamic systems with multiple fuzzy parameters and initial conditions." 2012. http://hdl.handle.net/1993/5196.
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Under some conditions in real world, precise parameters and/or initial values of dynamic systems are hard to be determined. Fuzzy Differential Equation (FDE) is a powerful tool to model dynamical systems with the uncertainty of impreciseness. This thesis presents the first numerical solution for Fuzzy Differential Equations with multiple fuzzy parameters and initial Values (FDEPIV) problems.
Previous approaches for solving the FDEs only focused on FDEs with single fuzzy condition. In this thesis, we applied the proper fuzzy arithmetic on Runge-Kutta method for solving the FDEPIV problems with multiple fuzzy parameters and initial conditions. Furthermore, comparing with directly applying the extension principle in solving FDEPIV, the complexity of the proposed method is much lower, and parallelization of the proposed algorithm is feasible. Numerical examples of the FDEPIV problems are presented to demonstrate the effectiveness of the proposed method.
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Chen, Hsin-Chin, and 陳信欽. "Optimized Backoff Parameters for Initial Ranging and Bandwidth Request in WiMAX Networks." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/92231274987990615604.
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碩士<br>國立彰化師範大學<br>資訊工程學系<br>97<br>According to the latest version of the IEEE 802.16 standard, the backoff parameters of its contention resolution mechanism are far from the optimal setting since this strategy incurs a high collision probability and channel utilization is degraded in congested scenario. Besides, the problem of choosing the right set of backoff parameters for the current network level remains unsolved and left as an open issue. Based on above observations, we propose that a proper choice of the CW parameter values based on channel status has a great influence on overall network performance. Hence, in this thesis, we propose a simple, yet pragmatic algorithm that allows the base station to dynamically adjust its backoff parameters based on run-time measurements of channel status. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the scheme. The proposed solution works very well in providing a remarkable performance improvement in heavy loaded BWA systems.
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Chen, Dar-der, and 陳達德. "Duration of Initials in Mandarin: In Search of Fundamental Acoustic Parameters." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/92196264195000057853.
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碩士<br>國立中正大學<br>語言學研究所<br>86<br>To construct a durational model of acoustic parmeters based on duration of initials in Mandarin, research of the durational pattern of initials is the primary work to be done. In the present experiment, 84 bisyllabic words including 21 Mandarin initials spoken in a carrier phrase were analyzed.
Duration of initials was measured from digital spectrograms, and was found to vary widely with the following factors: manner of articulation, place of articulation and adjacent vowels. The durational patterns of these initials in stressed words preceding the same vowel are here presented, and their
accuracy as well as the consistency of the durational measurements are examined.
Attempts are made to classify Mandarin initials based on the acoustic parameter of duration. This classification will improve the understanding of the production and perception of Mandarin.
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Peng, Yu-Min, and 彭宇民. "Determination of initial electron parameters for Monte Carlo simulation of Varian 21EX 6MV photon beams." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67400285399847912486.
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碩士<br>國立清華大學<br>生醫工程與環境科學系<br>94<br>Determination of initial electron parameters for Monte Carlo simulation of Varian 21EX LINACs 6MV photon beams
PURPOSES
Previous studies have demonstrated that the Monte Carlo simulation is an accurate method for dose simulation in radiotherapy. Accurate dose calculation requires precise characterization of the accelerator geometry and parameterization of the initial electron beam incident on the target. The objective of the current study was to determine optimal initial electron parameters for Monte Carlo simulation of the 6 MV photon beam (Varian 21EX) at CGMH—Linkou.
MATERIALS AND METHODS
The EGSnrc user code BEAM (BEAM06) was used for dose simulation in this work. The geometry was input into BEAM from proprietary diagrams supplied by Varian for the 21EX Linac. The optimal initial electron parameters were determined by evaluating dose difference between simulated and measured percentage depth doses (PDD) and lateral profiles at 1.5, 10 and 20 cm depths for 10 10 and 40 40 cm2 fields through trial-and-error processes. It started with an initial guess of the mean energy of electrons with fixed energy and radial spread. Once the optimal mean energy was determined, optimized energy spread was sought followed by determination of radial intensity distribution. Dose difference evaluation was performed using the κα factor and off-axis ratio (OAR). The κα factor is defined as the fraction of the voxels with absolute dose difference less than α% of the maximum measured central axis dose. Data evaluation (κα test) for PDD was done for depth range between 1.5 and 20 cm. Lateral position of 90% field size was used for OAR evaluation and κα tests for lateral profiles were performed within the center 90% field width.
RESULTS
Penetration of percentage depth curves increases with increasing mean energy of initial electrons, especially for 10 10 cm2 field but insensitive to energy spread and almost independent of radial spread.
OARs of lateral profiles decrease with increasing mean energy of initial electrons. Radial spread had great impact on OAR especially for 40 40 cm2 field but insensitivity to energy spread.
Energy distribution of the initial electrons was concluded to be a Gaussian distribution with mean energy equal to 6.2 MeV and FWHM setting 0.235 MeV. The optimal intensity distribution obtained in this work is a radially symmetric Gaussian distribution with FWHM equal to 1 mm.
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Bourassa, Justin. "Analysis of initial condensation and the effects of distillers' spent grain pellet orientation and superheated steam operating parameters on effective moisture diffusivity." 2015. http://hdl.handle.net/1993/30667.
Full textAbstract:
Distillers’ spent grain (DSG) is a by-product of ethanol production and used for swine feed supplement due to its nutrient composition. Lowering the moisture content of DSG using superheated steam (SS) drying can be more energy efficient compared to hot air drying. One objective was to investigate parameters associated with SS drying on DSG including maximum condensation, condensation time, and restoration time. Increasing SS temperature from 120 to 180 °C and SS velocity from 1.0 to 1.4 m/s resulted in a 97% and 67% decrease in maximum condensation, respectively. Another objective was to determine the effect of SS temperature, velocity, and pellet orientation on effective moisture diffusivity of DSG pellets. The diffusion model was based on finite cylinder geometry accounting for volumetric shrinkage. The diffusivity coefficient was determined to be 1.56 × 10-8 m2/s. A significant effect of pellet orientation on moisture diffusivity was found during the constant drying-rate period.<br>October 2015
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Chiu, Chien-Hsien, and 邱建賢. "Comparisons of Estimators of Lifetime Distribution and Its Parameters for Highly Reliable Products Based on Initial Degradation Data." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/21241776075562327016.
Full textAbstract:
碩士<br>國立清華大學<br>統計學研究所<br>91<br>Rapid advances in technology, development of highly sophisticated products, intense global competition, and increasing customer expectations have put new pressures on manufacturers to produce high-quality products. Customers expect purchased products to be reliable and safe. In other words, customer expect products be able to perform their intended function under usual operating conditions, for some specified period of time. The problems that come along are how to obtain the information of product reliability. But, today, many products are designed and manufactured to function for a long period of time before they fail. The problem of obtaining failure data to apply traditional statistical tools to predict lifetime distribution becomes more difficult. An alternative is to use data on a quality characteristic (QC) whose degradation over time is highly correlated with product failure. If degradation paths can be modeled properly, and the product fails when the QC’s degradation path first passes a critical value, then predicting the product’s failure time or the lifetime can be made without actually observing the product’s failure. Instead one will obtain what will be termed as the initial data from the early stage of reliability testing. A Wiener process is typical for describing a degradation process since it allows non-constant variance and non-zero correlation among data collected over time. In this paper we first review how a Wiener process was used to describe the continuous degradation path of a quality characteristic of the product. We compare the MLES and UMVUES of the mean and variance of lifetime distribution of the product, all based on initial data. Next, we propose an estimator of the lifetime distribution and compare it with the corresponding MLE. Then using an example in the literature, we demonstrate that our proposed estimator of the lifetime distribution is better than the MLE. The example is about the light intensity of light emitting diodes (LEDs). The data we use to obtain various estimates are all collected only from the product’s initial observed degradation path.
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Rieber, Jean [Verfasser]. "Hämodynamische Parameter bei der initialen Atherogenese in-vivo beim cholesteringefütterten Kaninchen / vorgelegt von Jean Rieber." 2003. http://d-nb.info/96861082X/34.
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