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1
Oladeinde, Abiola Omobolaji. « Linear demultiple solution based on bottom-multiple generator (BMG) approximation : subsalt example ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/4407.
Texte intégralRésumé :
Significant quantities of hydrocarbons are found in complex salt environments.
One of the modern challenges of exploration and production activities is to image below
salt. This challenge arises from the complexities of salt structures, weak primaries from
the subsalt, and the interference of free-surface multiples with the weak primaries of the
subsalt. To effectively process subsalt data, we need to develop a method of attenuating
free-surface multiples that preserves the amplitude and phase of primaries and does not
introduce artifacts at either near and far offsets. In this thesis, we will demonstrate that
the weak primaries of the subsalt can be preserved while attenuating free-surface
multiples. The method used for the demonstration is the bottom-multiple generator
(BMG) reflector approximation. This technique requires that a portion of the data
containing only primaries be defined. A multidimensional convolution of the data
containing only primaries with the actual data will predict free-surface multiples and
hence is used to attenuate free-surface multiples from the actual data. This method is one
of the most effective methods for attenuating free-surface multiples; however, the method requires muting data at the BMG location. One of the issues investigated in this
thesis, is to establish the sensitivity of the BMG demultiple technique when the mute at
the BMG location end up cutting some seismic reflections, which can be the case in
complex environments such as the Gulf of Mexico and Gulf of Guinea, where freesurface
multiples interfere with primaries. For this investigation, we generated synthetic
data through the 2D elastic finite-difference modeling technique. The synthetic seismic
data contain primaries; free-surface multiples, and internal multiples, and direct waves
acquired over a 2D geological model that depicts a shallow-water geology.
In this thesis, we also investigate if the first step of the BMG demultiple
technique can sufficiently attenuate free-surface multiples. For this investigation, we
designed a 2D geological model, which depicts the deep offshore environment, and we
generated synthetic data through the 2D elastic finite-difference modeling technique.
After performing the various investigations mentioned above, the following
conclusions were made, that the demultiple result is not affected when the mute at the
BMG location end up cutting some primaries, that the first step of the BMG demultiple
technique is not sufficient for the demultiple, and that the weak subsalt primaries are
preserved during demultiple processes. We compared shot gathers and zero offset data
before and after the demultiple.
2
Buchanan, John Telfer. « Solution methods for multiple objective decision models ». Thesis, University of Canterbury. Operations Research, 1985. http://hdl.handle.net/10092/4360.
Texte intégralRésumé :
This thesis is concerned with an investigation of solution methods for continuous multiple objective decision models (MODM's). A number of different solution methods which have appeared in the literature are reviewed with an emphasis on the underlying concepts of the methods. The following chapter examines the solution of MODM’S from the other side, namely the behavioural aspects of decision making. Having gained an appreciation of exactly how people do make decisions I the intent of the thesis is twofold. Firstly, to develop new solution methods which can accommodate the decision maker (DM) in whatever his or her particular decision strategy is. And secondly, it is to empirically examine four solution methods with respect to users' preferences among them. Of these four solution methods, three are among the most well known in the literature and all can cite practical application.
Two new solution methods have been developed. Both of these methods are based on a specific formulation of the MODM which is known as the maxmin formulation. The theory of the maxmin formulation is developed in Chapter 4. By using the Lagrange multipliers at the optimal solution, suitable pairwise tradeoff information can be presented to the DM. This forms the basis for the first solution method, which interacts with the DM as he or she progressively provides preference information. The other solution method makes use of a branch of Psychology called Social Judgement Theory and incorporates this into the solution method. This second method is especially applicable to the multiple DM situation.
In the empirical examination of solution methods it was found that one solution method was clearly preferred over the other three. The thesis concludes with a discussion of approaches for reducing the number of objectives in a MODM.
3
Witt, Andreas. « Multiple hierarchies : new aspects of an old solution ». Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2006/865/.
Texte intégralRésumé :
In this paper, we present the Multiple Annotation approach, which solves two problems: the problem of annotating overlapping structures, and the problem that occurs when documents should be annotated according to different, possibly heterogeneous tag sets. This approach has many advantages: it is based on XML, the modeling of alternative annotations is possible, each level can be viewed separately, and new levels can be added at any time. The files can be regarded as an interrelated unit, with the text serving as the implicit link. Two representations of the information contained in the multiple files (one in Prolog and one in XML) are described. These representations serve as a base for several applications.
4
Banks, Jeffrey T. « Multiple photon reactions of organic molecules in solution ». Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6788.
Texte intégralRésumé :
This thesis presents the results from numerous studies on the multiple photon reactions of organic molecules in solution. The initial investigations on the selectivities of radical fragmentation reactions from ground and excited states required the use of both pulsed and continuous wave laser techniques. Laser flash photolysis techniques were used to determine the $\alpha,\alpha$-dimethoxybenzyl radicals undergo fragmentation from the excited state with a quantum yield which is close to one. High intensity laser-jet photolysis was used to determine the selectivities for the excited state fragmentation of unsymmetrically substituted $\alpha,\alpha$-dialkoxybenzyl. It was found that the excited radicals show no selectivity upon fragmentation whereas the ground state radical fragmentations are governed by the thermodynamic stability of the radical products. Lack of a suitable method for the production of semi-preparative amounts of multiple photon reaction products in our own laboratory led us to develop a new technique which utilizes pulsed lasers. By irradiating small droplets of solution with the focused output from a pulse laser we were able to induce multiple photon reactions with efficiencies which are comparable to the laser-jet technique. A direct comparison was made for the case of diphenylmethyl radicals in carbon tetrachloride and methanol. This method, dubbed laser-drop photolysis, was used, along with laser-flash photolysis techniques and conventional lamp irradiations, to investigate and compare the chemistry for several transient species from both the ground and excited states. A number of unique reaction pathways have been found to occur from the excited states of the transient intermediates. For example, ground state 1,1-diphenylethoxyl radicals undergo a neophyl-like rearrangement to yield 1-phenoxy-1-phenylethyl radicals. From the excited state this radical undergoes $\beta$-scission, a process which does not occur from the ground state radical. Irradiation of small drops of liquid by the focused output from high powered pulse lasers results in their destruction in a manner similar to the ablative photodecomposition of organic polymers. We have investigated the dynamics of the drop explosion by taking Polaroid photographs with a time resolution of $\sim$20 ns by using a second pulsed laser as the flash for the camera. The destruction of the drops occurs in the $\mu$s time scale and a model has been proposed which is consistent with the dynamics of drop explosion. Further, pyrene has been used in attempts to probe the temperature increase inside the drop just prior to its explosion.
5
Baxter, Rodney Charles. « The thermodynamics of binary liquid mixtures of compounds containing multiple bonds ». Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1016079.
Texte intégralRésumé :
Excess thermodynamic properties have been determined for several binary liquid mixtures with the aim of testing various thermodynamic theories and postulates. Excess molar enthalpies, HEm, have been determined using an LKB flow microcalorimeter and excess molar volumes, VEm, have been determined using an Anton Paar vibrating tube densitometer. The activity coefficients at infinite dilution ƴ∞₁₃, have been determined using an atmospheric pressure gas-liquid chromatograph. The excess molar enthalpies and the excess molar volumes have been measured at 298.15 K for systems involving the bicyclic compounds decahydronaphthalene (decalin), 1,2,3,4-tetrahydronaphthalene (tetralin), bicyclohexyl, or cyclohexylbenzene mixed with 1- hexene, 1-hexyne, 1-heptene, 1-heptyne, cyclohexene, 1,3-cyclohexadiene, 1,4- cyclohexadiene, or benzene. These excess properties have also been measured for systems where the bicyclic compound has been replaced with benzene, cyclohexane or n-hexane. The results show defmite trends related to the size, shape, and the degree of unsaturation of the component molecules. The Flory theory has been used to predict excess molar enthalpies and excess molar volumes for {(a bicyclic compound or benzene or cyclohexane or n-hexane) +(an n-alkane or a 1-alkene or a 1-alkyne or a cycloalkane or cyclohexene or a cycloalkadiene or benzene)}. The one parameter equations offer reasonably good correlations between the predicted and the experimental results. More insight into the origins of the contnbutions to the excess thermodynamic properties for these systems has been gained by considering the approximate equations of Patterson and co-workers, which separate the interactional and the free volume contributions to the excess molar enthalpy and the excess molar volume. The one parameter equations have adequately rationalized a good deal of the observed behaviour for HEm and VEm. The theory of Liebermann and co-workers, which does not employ any adjustable parameters, has not been as successful at predicting the excess thermodynamic properties for the above systems. The activity coefficients at infinite dilution have been measured at 278.15 K, 288.15 K and 298.15 K for n-bexane, 1-bexene, 1-hexyne, n-heptane, 1-heptene, 1-heptyne, cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, and benzene, in decalin, tetralin, bicyclohexyl, and cyclohexylbenzene. Solvent losses from the column have been accounted for by an extrapolation procedure. The activity coefficient results together with the HEm and VEm values have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution. The partial molar excess properties at infinite dilution for decalin mixtures are similar to those for bicyclohexyl mixtures. There is also a similarity between the properties of the tetralin mixtures and the cyclohexylbenzene mixtures. The cycloalkadienes, benzene and the 1-alkynes exhibit a strong dissociation effect on being mixed with the saturated solvents, decalin and bicyclohexyl, but associate strongly with tetralin and with cyclohexylbenzene. The Flory theory bas been used to predict activity coefficients at infinite dilution from the experimentally determined HEm results for { (n-bexane or 1-hexene or 1-hexyne or naheptane or 1-heptene or 1-beptyne) + (a bicyclic compound)}. The theory is much better at predicting values for mixtures where both components are either saturated molecules or are unsaturated molecules than for {saturated + unsaturated} mixtures.
6
Hollenbeck, Richard. « Understanding the challenges of implementing a multiple solution norm ». College Park, Md. : University of Maryland, 2009. http://hdl.handle.net/1903/9526.
Texte intégralRésumé :
Thesis (Ph. D.) -- University of Maryland, College Park, 2009.Thesis research directed by: Dept. of Curriculum and Instruction. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
7
Wendt, Charles G. « Multiple-valued programmable logic array minimization by solution space search ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA278033.
Texte intégral
8
Lian, Zhengyi. « Discontinuous Galerkin solution of the Boltzmann equation in multiple spatial dimensions ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41560.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 77-79).
This thesis focuses on the numerical solution of a kinetic description of small scale dilute gas flows when the Navier-Stokes description breaks down. In particular, it investigates alternative solution techniques for the Boltzmann equation typically used when the Knudsen number (ratio of molecular mean free path to characteristic length scale of flow) exceeds (approximately) 0.1. Alternative solution methods are required because the prevalent Boltzmann solution technique, Direct Simulation Monte Carlo (DSMC), experiences a sharp rise in computational cost as the deviation from equilibrium decreases, such as in low signal flows. To address this limitation, L. L. Baker and N. G. Hadjiconstantinou recently developed a variance reduction technique [5] in which one only simulates the deviation from equilibrium. This thesis presents the implementation of this variance reduction approach to a Runge-Kutta Discontinuous Galerkin finite element formulation in multiple spatial dimensions. Emphasis is given to alternative algorithms for evaluating the advection operator terms, boundary fluxes and hydrodynamic quantities accurately and efficiently without the use of quadrature schemes. The collision integral is treated as a source term and evaluated using the variance-reduced Monte Carlo technique presented in [10, 9]. For piecewise linear (p = 1) and quadratic (p = 2) solutions to the Boltzmann equation in 5 spatial dimensions, the developed algorithms are able to compute the advection operator terms by a factor of 2.35 and 2.73 times faster than an algorithm based on quadrature, respectively; with the computation of hydrodynamic quantities, the overall performance improvement is a factor of 8.5 and 10, respectively.
(cont.) Although the collision integral takes up to 90% or more of the total computation cost, these improvements still provide tangible efficiency advantages in steady-flow calculations in which less expensive transient collision-operator calculation routines are used during a substantial part of the flow development. High order convergence in physical space has been verified by applying the implemented RKDG method on a test problem with a continuous solution. Furthermore, when applied to pressure driven Poiseuille flow through a rectangular channel, the steady state mass flux in the collisionless limit (where exact results exist) agrees within 0.5%, 0.8% and 1.2% of that obtained by Sone and Hasegawa [14] for aspect ratios of 1, 2 and 4 respectively under a spatial resolution of 52 x103 . For Kn = 0.2, 1 and 10, our results agree with those obtained by Sone and Hasegawa [14] from solutions of the linearized Boltzmann-Krook-Welander(BKW) equation by comparing them at an "equivalent" Knudsen number of 1.27Kn [21]. These results validate the implementation and demonstrate the feasibility of the variance-reduced RKDG method for solving the full Boltzmann equation in multiple spatial dimensions. To pursue higher accuracy for this pressure driven flow problem, a p = 1 scheme was found to be more efficient than a p = 2 scheme at a coarser spatial discretization. This can be achieved by using finer spatial discretization and non-uniform spacing to generate more elements near regions of discontinuities or large variations in the molecular distribution function.
by Zhengyi Lian.
S.M.
9
Lulec, Andac. « Solution Of Sparse Systems On Gpu Architecture ». Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613355/index.pdf.
Texte intégralRésumé :
The solution of the linear system of equations is one of the core aspects of Finite Element Analysis (FEA) software. Since large amount of arithmetic operations are required for the solution of the system obtained by FEA, the influence of the solution of linear equations on the performance of the software is very significant.
In recent years, the increasing demand for performance in the game industry caused significant improvements on the performances of Graphical Processing Units (GPU). With their massive floating point operations capability, they became attractive sources of performance for the general purpose programmers. Because of this reason, GPUs are chosen as the target hardware to develop an efficient parallel direct solver for the solution of the linear equations obtained from FEA.
10
Sfrappini, Alessandro. « BLE Embedded Solution for Gait Analysis on Subjects Affected by Multiple Sclerosis ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23783/.
Texte intégralRésumé :
Multiple sclerosis (MS), also known al encephalomyelitis disseminata, is a demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged.
The majority of patients either present with or transition into a progressive course, characterised by the gradual accumulation of disability independent of clinical relapses, which usually significantly affect their ability to walk.
This thesis follows the development of a low power embedded device for activity recognition and gait assessment.
The Bluetooth Low Energy protocol is studied and applied for wireless communication between the device and a smartphone.
A machine learning approach is implemented to detect walking-related activities during the day. Then, data analysis extracts the mobility-related data and uses it to compute gait-related information.
11
Yu, Kui. « Multiple morphologies of polystyrene-b-poly(ethylene oxide) diblock copolymers in dilute solution ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0020/NQ56703.pdf.
Texte intégral
12
Yu, Kui 1967. « Multiple morphologies of polystyrene-b-poly(ethylene oxide) diblock copolymers in dilute solution ». Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36076.
Texte intégralRésumé :
Multiple morphologies of self-assembled aggregates of polystyrene- b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers in dilute solution have been studied. The PS blocks are relatively long compared to the PEO blocks. The aggregates are prepared by the addition of water or methanol to the copolymer solutions in N,N-dimethylformamide (DMF), dioxane, or tetrahydrofuran (THF) to induce the aggregation of the PS blocks. Aqueous solutions of the aggregates are obtained by dialysis with water. Morphologies are directly studied by transmission electron microscopy (TEM).The morphogenic effect of the copolymer composition indicates that as the EO content in the diblock decreases, the morphology of the self-assembled aggregates changes progressively through spheres, rods, bilayers, and ultimately to inverted aggregates. The observed bilayers include lamellae, vesicles, tubules and large compound vesicles (LCVs), and the inverted aggregates include inverted (hollow) hoops with a hexagonal array and large compound micelles (LCMs).
The morphological transition from vesicles to inverted hoops is investigated, and a three-step mechanism is proposed. This mechanism involves a thickening of the vesicle walls accompanied by the formation of the hollow rods in the walls, and a decrease in the size of the original water core. Possible mechanisms of the formation of large vesicles from lamellae, as well as tubules and LCVs from vesicles are discussed.
The formation of the self-assembled aggregates with various morphologies is believed to be mainly controlled by the balance of three interactions arising from the core, the corona, and the core-solvent interface. Any factors, such as the addition of salt, which affect the balance will cause morphological changes. Accordingly, the morphogenic effects of added electrolytes, temperature, the common solvent, and the precipitant are studied. The study shows that various morphologies can be prepared from one diblock copolymer.
13
Nechma, Tarek. « Parallel sparse matrix solution for direct circuit simulation on a multiple FPGA system ». Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/347886/.
Texte intégralRésumé :
SPICE, from the University of California, at Berkeley, is the de facto world standard for circuit simulation. SPICE is used to model the behaviour of electronic circuits prior to manufacturing to decrease defects and hence reduce costs. However, accurate SPICE simulations of today's sub micron circuits can often take days or weeks on conventional processors. In a nutshell, a SPICE simulation is an iterative process that consists of two phases per iteration, namely, model evaluation followed by a matrix solution. The model evaluation phase has been found to be easily parallelisable unlike the subsequent phase, which involves the solution of highly sparse and asymmetric matrices. In this thesis, we present an FPGA implementation of a sparse matrix solver hardware,geared towards matrices that arise in SPICE circuit simulations. As such, we demonstrate how we extract parallelism at di�erent granularities to accelerate the solution process. Our approach combines static pivoting with symbolic analysis to compute an accurate task ow-graph which e�ciently exploits parallelism at multiple granularities and sustains high oating-point data rates. We also present a quantitative comparison between the performance of our hardware protrotype and state-of-the-art software package running on a general purpose PC equipped with a 2.67 GHz six-core 12 thread Intel Core Xeon X5650 microprocessor and 6 GB memory. We report average speedups of 9.65�, 11.83�, 17.21� against UMFPACK, KLU, and Kundert Sparse matrix packages respectively. We also detail our approach to adapt our sparse LU hardware prototype from a single-FPGA architecture to a multi-FPGA system to achieve higher acceleration ratios up to 38� for certain circuit matrices.
14
Pokrud, Boonyarit. « H∞ optimal control : general solution by interpolation and design with multiple objective functions ». Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/847911/.
Texte intégralRésumé :
A new method for solving Hinfinity control problems is developed. The method makes use of the Youla parametrization to characterize the set of all stabilizing controllers K(s) in terms of a stable function Q(s). and also to transform the Hinfinity control problem into a model-matching problem with an objective function E(s) being linear in Q(s). The model-matching problem is then solved by using the interpolation results of Hung. In the general case (i.e. problems of the 3rd kind) closed-form state-space characterizations of optimal and suboptimal solutions for Q(s) and E(s) are given. Furthermore, the solutions generally only require to solve two standard algebraic Riccati equations of smaller size than the McMillan degree of the (generalized) plant. This has an advantage of alleviating the computation burden associated with the ?-iteration required for determining the attainable minimum of ||E(s)||[infinity]. The Hinfinity approach to feedback design with multiple objective functions is studied in this thesis. For a system with two objective functions T[i](s), (i = 1, 2) a design criterion of minimizing the function max (||T[1](s)||[infinity], ||T[2](s)||[infinity]) subject to internal stability of the closed-loop system is proposed. The problem is formulated as an Hinfinity control problem and an iterative algorithm for obtaining a solution is given. A numerical example is given to illustrate the effectiveness of the proposed design technique for tightly bounding and shaping the frequency responses of two objective functions. The application of Hinfinity feedback design techniques to the control of flexible structures is investigated. Experiments are conducted in order to evaluate the use of the Hinfinity approach to the control of flexible structures. An Hinfinity optimal controller is designed and implemented in a laboratory system to manoeuvre a cantilever flexible beam and simultaneously control its vibrations. The controller performance is then assessed. The results obtained are shown to be satisfactory and encouraging.
15
Calik, Hatice. « Exact solution methodologies for the p-center problem under single and multiple allocation strategies ». Doctoral thesis, Bilkent University, Ankara, Turkey, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/238641.
Texte intégral
16
Pittman, Mary Ellen. « Multiple solution strategies in the middle school mathematics classroom : The role of the teacher ». Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219047.
Texte intégral
17
Yu, Xianhui. « Numerical solution of multiple front phase change problems for modeling ice thermal storage systems ». Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06062008-163715/.
Texte intégral
18
Mudavanhu, Blessing. « A new renormalization method for the asymptotic solution of multiple scale singular perturbation problems / ». Thesis, Connect to this title online ; UW restricted, 2002. http://hdl.handle.net/1773/6794.
Texte intégral
19
Kurc, Ozgur. « A Substructure Based Parallel Solution Framework for Solving Linear Structural Systems with Multiple Loading Conditions ». Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6923.
Texte intégralRésumé :
This study presented a substructure based parallel linear solution framework for the static analysis of linear structural engineering problems having multiple loading conditions. The framework was composed of two separate programs designed to work on PC Clusters having the Windows operating system. The first program was responsible for creating the optimum substructures for the parallel solution and first partitioned the structure in such a way that the number of substructures was equal to the number of processors. Then, the estimated condensation time imbalance of the initial substructures was adjusted by iteratively transferring nodes from the substructures with slower estimated condensation times to the substructures with faster estimated condensation times. Once the final substructures were created, the second program started the solution. Each processor assembled its substructures stiffness matrix and condensed it to the interface with other substructures. The interface problem was solved by a parallel variable band solver. After computing the interface unknowns, each processor calculated the internal displacements and element stresses or forces. Examples which illustrate the applicability and efficiency of this approach were also presented. In these examples, the number of processors was varied from one to twelve to demonstrate the performance of the overall solution framework.
20
Balsa, Carlos Jorge da Rocha. « Inexact Subspace Iteration to Accelerate the Solution of Linear Systems with Multiple Right-Hand Sides ». Phd thesis, Toulouse, INPT, 2006. http://oatao.univ-toulouse.fr/7470/1/balsa.pdf.
Texte intégralRésumé :
We propose a two-phase acceleration technique for the solution of Symmetric and Positive Definite (SPD) linear systems with multiple right-hand sides. In the first phase we compute some partial spectral information related to the ill conditioned part of the given coefficient matrix and, in the second phase, we use this information to improve the convergence of the Conjugate Gradient (CG) algorithm. This approach is adequate for large scale problems, like the simulation of time dependent differential equations, where it is necessary to solve consecutively several linear systems with the same coefficient matrix (or with matrices that present very close spectral properties) but with changing right-hand sides. To compute the spectral information, we combine the block Conjugate Gradient algorithm with the Subspace Iteration to build a purely iterative algorithm, that we call Block-CGSI. We analyze the convergence of the blockCG algorithm and exploit the possibility of reducing the total amount of computational work by controlling in a same appropriate manner the accuracy during the solution of linear systems at each subspace iteration. We also improve the global convergence of this algorithm by using Chebyshev polynomials as a spectral filtering tool when building the starting vectors. The concept of “sliding window” was also introduced as an algorithmic feature that enables the computation of a near-invariant subspace of any dimension. The spectral information computed by the BlockCGSI algorithm is then used to remove the effect of the smallest eigenvalues in two different ways: either by building a Spectral Low Rank Update (SLRU) preconditioner that basically adds the value 1 to the approximated eigenvalues, or by performing a deflation of the initial residual in order to remove part of the solution corresponding to the smallest eigenvalues. Both techniques yield important reductions of the total number of iterations and computational work in each subsequent runs of the Conjugate Gradient algorithm. We report on experiments on a 2D diffusion equation as well as on two applications coming from Computational Fluid Dynamics (CFD). The analysis of costs and benefits, in terms of floating point operations, helps to validate the strategy as a good way to speed up the solution of symmetric and positive definite linear systems
21
Golan, Jonathan, et Joel Kallin. « Measuring Improvements and the Effects of Multiple and Unique Solution Puzzles on Sudoku Solving Algorithms ». Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166739.
Texte intégralRésumé :
In this paper we compare various Sudoku solving algorithms in order to determine what kind of run-time improvements different optimizations can give. We will also examine what kind of effect the existence of multiple solutions in the puzzles has on our result.
22
Bathurst, Graeme N. « A Newton solution for the harmonic analysis of power systems with multiple non-linear devices ». Thesis, University of Canterbury. Electrical Engineering, 1999. http://hdl.handle.net/10092/7411.
Texte intégralRésumé :
This thesis describes a new algorithm for the harmonic analysis of power systems.
Existing non-linear models are incorporated into a structure that allows very general configurations that are linked by linear ac and dc systems. A three phase loadflow is included at the power frequency and the steady-state is solved iteratively using a real-valued, positive frequency, full Newton technique. This structure allows electrical and non-electrical variables to be solved simultaneously. The resultant process is fast, robust and shows excellent comparison with time domain simulation.
The harmonic characteristics of large power conversion installations such as HVdc and high-pulse LVdc are investigated. The effects of system operation on the harmonic transfer through an HVdc link are investigated using the multiple run feature of the algorithm. Also, the representation of bipolar HVdc links is investigated and justifications for accurate dc system representation shown.
The harmonic domain converter has been generalised, and a representation of the zigzag transformer developed. Using this the effects of outage conditions of a high-pulse installation are modelled, and a proposal is given for the minimisation of low order harmonic generation during this condition.
Finally, a fast numerical technique for the accurate calculation of non-linear device impedances is described. This is used in conjunction with simplified converter models to assess the impact of the converter on the linear ac system impedance. A comparison is made between the different methods of harmonic analysis and a quantitative assessment of their accuracy given.
23
Balsa, Carlos Jorge da Rocha Dayde Michel Palma José Laginha. « Inexact subspace iteration to accelerate the solution of linear systems with multiple right-hand sides ». Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000315.
Texte intégralRésumé :
Reproduction de : Thèse de doctorat : Informatique et télécommunications : Toulouse, INPT : 2006. Reproduction de : Thèse de doctorat : Informatique et télécommunications : Porto, FEUP : 2006.Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. 47 réf.
24
McKee, Matthew Gary. « The Influence of Branching and Intermolecular Interactions on the Formation of Electrospun Fibers ». Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29370.
Texte intégralRésumé :
The implications of chain topology and intermolecular interactions on the electrospinning process were investigated for linear and randomly branched polymers. Empirical correlations were developed based on solution rheological measurements that predict the onset of electrospun fiber formation and average fiber diameter. In particular, for neutral, non-associating polymer solutions, the minimum concentration required for fiber formation was the entanglement concentration (Ce), and uniform, bead-free fibers were formed at 2 to 2.5 Ce. This was attributed to entanglement couplings stabilizing the electrospinning jet and preventing the Raleigh instability. Moreover, the influence of molar mass and degree of branching on electrospun fiber diameter was eliminated when the polymer concentration was normalized with Ce, and the fiber diameter universally scaled with C/Ce to the 2.7 power.
Polymers modified with quadruple hydrogen bonding groups were investigated to determine the role of intermolecular interactions on the solution rheological behavior and the electrospinning process. In nonpolar solvents, the hydrogen bonding functionalized polymers displayed significant deviation from the electrospinning behavior for neutral solutions due to the strong intermolecular associations of the multiple hydrogen bonding groups. The predicted electrospinning behavior was recovered when the hydrogen bonding interactions were screened with a polar solvent. Moreover, it was observed that branching and multiple hydrogen bonding afforded significant processing advantages compared to functionalized, linear analogs of equal molar mass. For example, branched chains in the unassociated state possessed a larger Ce compared to the linear chains, which indicated a lower entanglement density of the former. However, in the associated state the linear and branched chains possessed nearly equivalent Ce values, suggesting a similar entanglement density. Thus, the branched polymers displayed significantly lower viscosities in the unassociated state compared to linear polymers, while still retaining sufficient entanglements in the associated state due to the reversible network structure of the multiple hydrogen bond sites.
The solution rheological and processing behavior of polyelectrolyte solutions was also investigated to discern the role of electrostatic interactions on electrospun fiber formation. In particular, the polyelectrolyte solutions formed nano-scale electrospun fibers with an average fiber diameter 2 to 3 orders of magnitude smaller than neutral polymer solutions of equivalent viscosity and C/Ce. This was attributed to the very high electrical conductivity of the polyelectrolyte solutions, which imparted a high degree of charge repulsion in the electrospinning jet and increased the extent of plastic stretching in the polymer filament. In fact, the average diameter of the polyelectrolyte fibers under certain conditions was less than 100 nm, which makes them good candidates for protective clothing applications due to their high specific surface area. Moreover, the neutral polymer solution electrospinning behavior was recovered after the addition of NaCl, which screened the electrostatic charge repulsions along the polyelectrolyte main chain. Finally, electrospun, biocompatible phospholipid membranes were produced from solutions of entangled worm-like lecithin micelles. This is the first example of successfully electrospinning low molar mass, amphiphilic compounds into uniform fibers. Electrospinning the phospholipid worm-like micelles into nonwoven fibrous mats will afford direct engineering of bio-functional, high surface area membranes without the use of multiple synthetic steps, complicated electrospinning setups, or post processing surface treatments.Ph. D.
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Zhao, Xiaolin. « Reducing Unnecessary Sign-ups by The Development Solution of Super-client Driving Multiple Sub- clients( SDMS) ». Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301239.
Texte intégralRésumé :
Nowadays more and more web applications are becoming part of everybody’s daily life. Lots of Internet users are bothered by having to create new accounts on websites. But at the same time, it is believed that sign-up as well as sign-in is a good registration solution which is difficult to replace. In this thesis we considered a certain scenario in which a number of people need a short period of co-operation for certain tasks by using a web application. If everyone creates an account, it will be significantly annoying since it will increase everyone’s work and extend the working period. Due to such consideration we have supplied a possible solution that one user with an account works as a super-client, and then generates short-lived login codes or links for others who work as sub-clients. This solution is called SDMS which is short for Super-client Driving Multiple Sub-clients. The thesis work contains the description and analysis of SDMS as well as designing and developing an example application. The example application is an online board game assistance platform, whose user scenario exactly fulfils the case of multiple users co-operating for a certain task that has been mentioned in the previous paragraph. Finally, we draw the conclusion that SDMS could improve the user experience in certain scenarios.Numera blir allt fler webbapplikationer en del av allas dagliga liv. Massor av Internetanvändare stors av att behöva skapa nya konton på webbplatser. Men samtidigt tror man att både registrering och inloggning ar en bra registreringslösning som ar svar att ersatta. I denna avhandling övervägde vi ett visst scenario dar ett antal personer behöver en kort period av samarbete for vissa uppgifter genom att använda en webbapplikation. Om alla skapar ett konto blir det väldigt irriterande eftersom det kommer att oka allas arbete och förlänga arbetsperioden. Pa grund av sådan övervägande har vi tillhandahållit en möjlig lösning att en användare med ett konto fungerar som en superklient och sedan genererar kortlivade inloggningskoder eller lankar for andra som arbetar som underklienter. Denna lösning kallas SDMS, vilket ar en förkortning for Super-client Driving Multiple Sub-clients. Examensarbetet innehåller beskrivning och analys av SDMS samt utformning och utveckling av en exempelapplikation. Exempelapplikationen ar en online brädspelassistansplattform, vars användarscenario exakt uppfyller fallet med att flera användare samarbetar for en viss uppgift som har nämnts i föregående stycke. Slutligen drar vi slutsatsen att SDMS kan förbättra användarupplevelsen i vissa scenarier.
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Wang, Bao. « Numerical Simulation of Detonation Initiation by the Space-Time Conservation Element and Solution Element Method ». The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1293461692.
Texte intégral
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Mazi, Aikaterini. « Seawater intrusion risks and controls for safe use of coastal groundwater under multiple change pressures ». Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-103137.
Texte intégralRésumé :
In the era of intense pressures on water resources, the loss of groundwater by increased seawater intrusion (SWI), driven by climate, sea level and landscape changes, may be critical for many people living in commonly populous coastal regions. Analytical solutions have been derived here for interface flow in coastal aquifers, which allow for simple quantification of SWI under extended conditions from previously available such solutions and are suitable for first-order regional vulnerability assessment and mapping of the implications of climate- and landscape-driven change scenarios and related comparisons across various coastal world regions. Specifically, the derived solutions can account for the hydraulically significant aquifer bed slope in quantifying the toe location of a fresh-seawater sharp interface in the present assessments of vulnerability and safe exploitation of regional coastal groundwater. Results show high nonlinearity of SWI responses to hydro-climatic and groundwater pumping changes on the landside and sea level rise on the marine side, implying thresholds, or tipping points, which, if crossed, may lead abruptly to major SWI of the aquifer. Critical limits of coastal groundwater change and exploitation have been identified and quantified in direct relation to prevailing local-regional conditions and stresses, defining a safe operating space for the human use of coastal groundwater. Generally, to control SWI, coastal aquifer management should focus on adequate fresh groundwater discharge to the sea, rather than on maintaining a certain hydraulic head at some aquifer location. First-order vulnerability assessments for regional Mediterranean aquifers of the Nile Delta Aquifer, the Israel Coastal Aquifer and the Cyprus Akrotiri Aquifer show that in particular the first is seriously threatened by advancing seawater. Safe operating spaces determined for the latter two show that the current pumping schemes are not sustainable under declining recharge.The thesis was founded by two research programmes: NEO private-academic sector partnership and Ekoklim, a strategic governmental funding through Stockholm University
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.
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Moreau, Gilles. « On the Solution Phase of Direct Methods for Sparse Linear Systems with Multiple Sparse Right-hand Sides ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN084/document.
Texte intégralRésumé :
Cette thèse se concentre sur la résolution de systèmes linéaires creux dans le contexte d’applications massivement parallèles. Ce type de problèmes s’exprime sous la forme AX=B, où A est une matrice creuse d’ordre n x n, i.e. qui possède un nombre d’entrées nulles suffisamment élevé pour pouvoir être exploité, et B et X sont respectivement la matrice de seconds membres et la matrice de solution de taille n x nrhs. Cette résolution par des méthodes dites directes est effectuée grâce à une étape de factorisation qui réduit A en deux matrices triangulaires inférieure et supérieure L et U, suivie de deux résolutions triangulaires pour calculer la solution.Nous nous intéressons à ces résolutions avec une attention particulière apportée à la première, LY=B. Dans beaucoup d’applications, B possède un grand nombre de colonnes (nrhs >> 1) transformant la phase de résolution en un goulot d’étranglement. Elle possède souvent aussi une structure creuse, donnant l’opportunité de réduire la complexité de cette étape.Cette étude aborde sous des angles complémentaires la résolution triangulaire de systèmes linéaires avec seconds membres multiples et creux. Nous étudions dans un premier temps la complexité asymptotique de cette étape dans différents contextes (2D, 3D, facteurs compressés ou non). Nous considérons ensuite l’exploitation de cette structure et présentons de nouvelles approches s’appuyant sur une modélisation du problème par des graphes qui permettent d’atteindre efficacement le nombre minimal d’opérations. Enfin, nous donnons une interprétation concrète de son exploitation sur une application d’électromagnétisme pour la géophysique. Nous adaptons aussi des algorithmes parallèles aux spécificités de la phase de résolution.Nous concluons en combinant l'ensemble des résultats précédents et en discutant des perspectives de ce travailWe consider direct methods to solve sparse linear systems AX = B, where A is a sparse matrix of size n x n with a symmetric structure and X and B are respectively the solution and right-hand side matrices of size n x nrhs. A is usually factorized and decomposed in the form LU, where L and U are respectively a lower and an upper triangular matrix. Then, the solve phase is applied through two triangular resolutions, named respectively the forward and backward substitutions.For some applications, the very large number of right-hand sides (RHS) in B, nrhs >> 1, makes the solve phase the computational bottleneck. However, B is often sparse and its structure exhibits specific characteristics that may be efficiently exploited to reduce this cost. We propose in this thesis to study the impact of the exploitation of this structural sparsity during the solve phase going through its theoretical aspects down to its actual implications on real-life applications.First, we investigate the asymptotic complexity, in the big-O sense, of the forward substitution when exploiting the RHS sparsity in order to assess its efficiency when increasing the problem size. In particular, we study on 2D and 3D regular problems the asymptotic complexity both for traditional full-rank unstructured solvers and for the case when low-rank approximation is exploited. Next, we extend state-of-the-art algorithms on the exploitation of RHS sparsity, and also propose an original approach converging toward the optimal number of operations while preserving performance. Finally, we show the impact of the exploitation of sparsity in a real-life electromagnetism application in geophysics that requires the solution of sparse systems of linear equations with a large number of sparse right-hand sides. We also adapt the parallel algorithms that were designed for the factorization to solve-oriented algorithms.We validate and combine the previous improvements using the parallel solver MUMPS, conclude on the contributions of this thesis and give some perspectives
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Dromard, Juliette. « Vers une solution de contrôle d’admission sécurisée dans les réseaux mesh sans fil ». Thesis, Troyes, 2013. http://www.theses.fr/2013TROY0028/document.
Texte intégralRésumé :
Les réseaux mesh sans fil (Wireless Mesh Networks-WMNs) sont des réseaux facilement déployables et à faible coût qui peuvent étendre l’Internet dans des zones où les autres réseaux peuvent difficilement accéder. Cependant, plusieurs problèmes de qualité de service (QoS) et de sécurité freinent le déploiement à grande échelle des WMNs. Dans cette thèse, nous proposons un modèle de contrôle d’admission (CA) et un système de réputation afin d’améliorer les performances du réseau mesh et de le protéger des nœuds malveillants. Notre système de CA vise à assurer la QoS des flux admis dans le réseau en termes de bande passante et de délai tout en maximisant l’utilisation de la capacité du canal. L’idée de notre solution est d’associer au contrôle d’admission une planification de liens afin d’augmenter la bande passante disponible. Nous proposons également un système de réputation ayant pour but de détecter les nœuds malveillants et de limiter les fausses alertes induites par la perte de paquets sur les liens du réseau. L’idée de notre solution est d’utiliser des tests statistiques comparant la perte de paquets sur les liens avec un modèle de perte préétabli. De plus, il comprend un système de surveillance composé de plusieurs modules lui permettant détecter un grand nombre d’attaques. Notre CA et notre système de réputation ont été validés, les résultats montrent qu’ils atteignent tous deux leurs objectifsWireless mesh networks (WMNs) are a very attractive new field of research. They are low cost, easily deployed and high performance solution to last mile broadband Internet access. However, they have to deal with security and quality of service issues which prevent them from being largely deployed. In order to overcome these problems, we propose in this thesis two solutions: an admission control with links scheduling and a reputation system which detects bad nodes. These solutions have been devised in order to further merge into a secure admission control. Our admission control schedules dynamically the network’s links each time a new flow is accepted in the network. Its goal is to accept only flows which constraints in terms of delay and bandwidth can be respected, increase the network capacity and decrease the packet loss. Our reputation system aims at assigning each node of the network a reputation which value reflects the real behavior of the node. To reach this goal this reputation system is made of a monitoring tool which can watch many types of attacks and consider the packet loss of the network. The evaluations of our solutions show that they both meet their objectives in terms of quality of service and security
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De, Boer Jeroen Wouter. « Approximate Models And Solution Approaches For The Vehicle Routing Problem With Multiple Use Of Vehicles And Time Windows ». Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609620/index.pdf.
Texte intégralRésumé :
In this study we discuss the Vehicle Routing Problem with multiple use of vehicles (VRPM). In this variant of the routing problem the vehicles may replenish at any time at the depot.
We present a detailed review of existing literature and propose two mathematical models to solve the VRPM. For these two models and their several variants we provide computational
results based on the test problems taken from the literature. We also discuss a case study in which we are simultaneously dealing with side constraints such as time windows, working hour limits, backhaul customers and a heterogeneous vehicle fleet.
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Vega-Nevarez, Juan. « Online Path Planning and Control Solution for a Coordinated Attack of Multiple Unmanned Aerial Vehicles in a Dynamic Environment ». Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5551.
Texte intégralRésumé :
The role of the unmanned aerial vehicle (UAV) has significantly expanded in the military sector during the last decades mainly due to their cost effectiveness and their ability to eliminate the human life risk. Current UAV technology supports a variety of missions and extensive research and development is being performed to further expand its capabilities. One particular field of interest is the area of the low cost expendable UAV since its small price tag makes it an attractive solution for target suppression. A swarm of these low cost UAVs can be utilized as guided munitions or kamikaze UAVs to attack multiple targets simultaneously. The focus of this thesis is the development of a cooperative online path planning algorithm that coordinates the trajectories of these UAVs to achieve a simultaneous arrival to their dynamic targets. A nonlinear autopilot design based on the dynamic inversion technique is also presented which stabilizes the dynamics of the UAV in its entire operating envelope. A nonlinear high fidelity six degrees of freedom model of a fixed wing aircraft was developed as well that acted as the main test platform to verify the performance of the presented algorithmsID: 031001316; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Houman A. Sadri.; Title from PDF title page (viewed March 26, 2013).; Thesis (M.A.)--University of Central Florida, 2012.; Includes bibliographical references (p. 89-99).
M.S.E.E.
Masters
Electrical Engineering and Computing
Engineering and Computer Science
Electrical Engineering; Controls and Robotics
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Kil, Hyun Joo. « Design & ; Synthesis of Peptidomimetics Adopting Secondary Structures for Inhibition of p53/MDM2 Protein-protein Interaction and Multiple Myeloma Cell Adhesion ». Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5051.
Texte intégralRésumé :
The protein-protein interactions (PPIs) occur when two or more proteins are bound together. Also, this protein-protein interactions (PPIs) cause the various biological processes in the body. Due to this reason, abilities of controlling or inhibiting PPIs can give us promising advantages like (1) better understanding of biological systems, (2) development of new diagnostic approaches for health or disease, and (3) establishment of novel molecular therapeutics. Many proteins adopt the secondary structures, where most of protein-protein interactions take place. -Helices and -sheets are the prevalent secondary conformations, but there are extended secondary structures such as -hairpins, -turns, 310 helix, and so on. As a result, construction of molecules mimicking these protein secondary structures is tractable target for drug design.
Moreover, in drug discovery, designing peptidomimetics or non-peptidic mimetics is a popular strategy instead using peptides or truncated peptides because peptides or truncated peptides are prone to proteolysis and degraded in the body. Also, peptidomimetics and non-peptidic mimetics have not only the similar topology as peptides but also resistance to proteolysis. Due to these advantages, in this study, peptidomimetics or non-peptidic mimetics were synthesized and tested for different targets: (1) synthesis of non-peptidic -helical mimetics for p53-MDM2 inhibition, (2) solution-phase synthesis of -hairpin peptide for the inhibition of multiple myeloma cells (MM) adhesion, and (3) synthesis of -hairpin peptoid-peptide hybrids.
The synthesis in all three different studies was succeeded, but they still need some improvements. For instance, non-peptidic -helical mimetics, terpyrimidyl derivatives, were synthesized successfully, but they did not show any bioactivity against p53-MDM2. Also, they have a solubility problem. Based on these results, it is necessary to improve the pharmacokinetic properties and bioactivity by changing the substituents on the rings or structures.
The -hairpin peptide for the second case already showed good bioactivity against multiple myeloma (MM). For the next level of bio-study, the considerable amount of a -hairpin peptide was demanded. In order to make the substantial -hairpin peptide, the solution phase peptide synthesis was chosen instead of the solid phase peptide synthesis because of the cost-effect. Two methodology were tried for the solution-phase peptide synthesis: (1) segment ligation and (2) continuous synthesis. In the former case, the -hairpin peptide synthesis was successful, but, in the latter case, it is necessary to investigate the appropriate coupling reagents for each step.
Peptoid-peptide hybrids has been one of the popular peptidomimetics in the last two decades. Also, mimicking the peptide secondary structure in peptoids has been studied extensively these days. The combination of these two factors was the goal for the third case. Because peptoid-peptide hybrids with a secondary structure can be recognizable by native proteins and resistant to proteolysis. So far, three sets of peptoid-peptide hybrids were synthesize and checked the secondary structure formation by using NMR. However, there was no indication of the secondary structure formation in the three sets of peptoid-peptide hybrids. This result suggests that it is necessary to introduce the more constrained components in peptoid-peptide hybrids.
In the above three chapters, it has been tried to find the new drug candidates by synthesizing peptidomimetics or non-peptidic mimetics. Even though the synthesis was successful, some intended results such as the bioactivity or the secondary structure formation were not obtained. However, these results can give us the inspirations to improve properties of peptidomimetics or non-peptidic mimetics for a certain purpose, which leads to earn the intended results and eventually find new drug candidates.
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Ak, Aykagan. « Berth and quay crane scheduling problems, models and solution methods / ». Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26652.
Texte intégralRésumé :
Thesis (Ph.D)--Industrial and Systems Engineering, Georgia Institute of Technology, 2009.Committee Chair: Erera, Alan L.; Committee Member: Ergun, Ozlem; Committee Member: Savelsbergh, Martin; Committee Member: Tetali, Prasad; Committee Member: White III, Chelsea C.. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Pinel, Xavier. « A perturbed two-level preconditioner for the solution of three-dimensional heterogeneous Helmholtz problems with applications to geophysics ». Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0033/document.
Texte intégralRésumé :
Le sujet de cette thèse est le développement de méthodes itératives permettant la résolution degrands systèmes linéaires creux d'équations présentant plusieurs seconds membres simultanément. Ces méthodes seront en particulier utilisées dans le cadre d'une application géophysique : la migration sismique visant à simuler la propagation d'ondes sous la surface de la terre. Le problème prend la forme d'une équation d'Helmholtz dans le domaine fréquentiel en trois dimensions, discrétisée par des différences finies et donnant lieu à un système linéaire creux, complexe, non-symétrique, non-hermitien. De plus, lorsque de grands nombres d'onde sont considérés, cette matrice possède une taille élevée et est indéfinie. Du fait de ces propriétés, nous nous proposons d'étudier des méthodes de Krylov préconditionnées par des techniques hiérarchiques deux niveaux. Un tel pre-conditionnement s'est montré particulièrement efficace en deux dimensions et le but de cette thèse est de relever le défi de l'adapter au cas tridimensionel. Pour ce faire, des méthodes de Krylov sont utilisées à la fois comme lisseur et comme méthode de résolution du problème grossier. Ces derniers choix induisent l'emploi de méthodes de Krylov dites flexiblesThe topic of this PhD thesis is the development of iterative methods for the solution of large sparse linear systems of equations with possibly multiple right-hand sides given at once. These methods will be used for a specific application in geophysics - seismic migration - related to the simulation of wave propagation in the subsurface of the Earth. Here the three-dimensional Helmholtz equation written in the frequency domain is considered. The finite difference discretization of the Helmholtz equation with the Perfect Matched Layer formulation produces, when high frequencies are considered, a complex linear system which is large, non-symmetric, non-Hermitian, indefinite and sparse. Thus we propose to study preconditioned flexible Krylov subspace methods, especially minimum residual norm methods, to solve this class of problems. As a preconditioner we consider multi-level techniques and especially focus on a two-level method. This twolevel preconditioner has shown efficient for two-dimensional applications and the purpose of this thesis is to extend this to the challenging three-dimensional case. This leads us to propose and analyze a perturbed two-level preconditioner for a flexible Krylov subspace method, where Krylov methods are used both as smoother and as approximate coarse grid solver
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Davidsson, Camilla, et Elina Anderson. « Caught in the twilight zone : Mobile money - one solution to the multiple expectations faced by married women in Mbarara, Uganda ». Thesis, Linnéuniversitetet, Institutionen för samhällsstudier (SS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-42183.
Texte intégralRésumé :
Women’s subordination in marital relations is a problematic issue causing socio-economic imbalance between spouses. These issues are found within the system of Uganda’s patriarchal society. Mobile money (m-money) is a service that entered the Ugandan market in 2009 that allows transferring and withdrawing money and paying bills with your cellphone without being connected to a formal bank. Earlier research shows positive impact of m-money use for women’s entrepreneurship in a male-privileged society. These realities render interest towards investigating how m-money effects women and if it has any impact on their self esteem in their marital relation. The study aims to understand the effect of women’s use of m-money in a marital relation. The field study was carried out in Mbarara using interviews and observations to approach the issue. Ugandan women have a lower position within the marital relation as well as in society in general since it is the man who heads of the family. The study reveals an existing lack of trust between spouses, resulting in the exclusion of one another from their individual finances. This lack of trust becomes an impediment of mutual support within the marriage. Furthermore the study shows that women from a higher strata use m-money as a security line of income and gives leeway to meet both traditional expectations such as care taking of children and modern expectations to be employed within the formal sector. The lower strata of women who use m-money tend to protect the money from their husbands who have different priorities than their wives. Through m-money women are given a tool allowing them to circumvent economic confrontations between the spouses and the societal hierarchal structures. The economic security creates a reality where women are less vulnerable because of their independence. The gained independence can however be deemed as a less bad alternative to dependence as it gives them a stronger foundation to manage the combination of the above-mentioned traditional and modern expectations within society.
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DiMarco, Sandra. « Solution-Focused Family Weekends in an Addictions Treatment Facility : An Action Treatment-and-Research Study ». Diss., NSUWorks, 2019. https://nsuworks.nova.edu/shss_dft_etd/53.
Texte intégralRésumé :
For the past 69 years, since the start of the addiction treatment system in the United States, treatment providers have been utilizing the same interventions in rehab centers, the majority of which are based on outdated ideas about substance misusers. Though the premise of such interventions has been questioned by researchers, treatment providers continue to utilize them. Family therapy, in particular, shows promising results for substance misusers and their families; it has been cited as the most powerful form of intervention in addiction treatment. Nevertheless, family therapy is underrepresented in the addiction literature and rehab centers. Furthermore, postmodern models of family therapy are even more scarce within these contexts.
The purpose of this study was twofold: to explore the viability of an underrepresented, alternative approach to treatment, and to explore the personal, organizational, and clinical processes occurring throughout the development of a systemic family program implemented in an adult inpatient rehab center with an individualistic approach. The researcher modified action research methodology to analyze archival data acquired from a completed clinical project, which was implemented over the course of three weekends. The researcher adapted categorizing and coding procedures from action research in order to analyze 34 personal journal entries and 11 supervision meetings, all of which illuminated the changes in the personal, organizational, and clinical processes that occurred throughout the clinical project. To illustrate the viability of a solution-focused, multiple family group (SFBT-MFG) approach for substance misusers and their families, the researcher collected and analyzed a total of 79 client and family evaluation surveys, 19 pretreatment change questionnaires, and six staff evaluation surveys.
The results of this study support an SFBT-MFG approach for adult substance misusers and their families. The researcher identified enhanced communication, understanding, honesty, and support as key themes, along with nine other themes, in the evaluation surveys completed by the participants in the family weekends. The study can help other marriage and family therapists undergo their own processes of integration when practicing systemically in a culture guided by individualistic notions of mental health.
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Lokman, Banu. « Approaches For Multi-objective Combinatorial Optimization Problems ». Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608443/index.pdf.
Texte intégralRésumé :
In this thesis, we develop two exact algorithms and a heuristic procedure for Multiobjective
Combinatorial Optimization Problems (MOCO). Our exact algorithms
guarantee to generate all nondominated solutions of any MOCO problem. We test the
performance of the algorithms on randomly generated problems including the Multiobjective
Knapsack Problem, Multi-objective Shortest Path Problem and Multi-objective
Spanning Tree Problem. Although we showed the algorithms work much better than the
previous ones, we also proposed a fast heuristic method to approximate efficient frontier
since it will also be applicable for real-sized problems. Our heuristic approach is based
on fitting a surface to approximate the efficient frontier. We experiment our heuristic on
randomly generated problems to test how well the heuristic procedure approximates the
efficient frontier. Our results showed the heuristic method works well.
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Uriarte, Sabín Leticia. « Inverse Heat Conduction problem of the Quenching a Rotary Cylinder by Multiple Water Impinging Jets ». Thesis, Högskolan i Gävle, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-36529.
Texte intégralRésumé :
The thesis deals with solving the time dependent inverse heat conduction and heat transfer problem of the quenching process of a rotary solid cylinder by multiple impinging water jets. The development of such investigation consists of two parts that complement each other. As is the case of any scientific experiment, first of all, an initial hypothesis will be set to be demonstrated theoretically. The numerical validation is carried out with a series of artificial cooling curve data and sensitivity analyses in the inverse solution. Then, a series of recorded temperature data were implemented into the inverse solution to predict the surface heat transfer during the quenching process.The numerical study consists of the solution of a two-dimensional linear time dependent inverse heat conduction problem based on the Generalized Minimal Residual Method (GMRES). The inverse solution method is based on the solution of an iterative problem, validated by a set of artificial temperature data. Such solution allows the prediction of the surface temperature and heat flux distribution in the quenching process, making use of recorded internal temperatures of the specimen. In order to solve the problem, the Matlab and Comsol Multiphysics programs were used. The GMRES algorithm was written as Matlab code, while the computational domain was defined in Comsol Multiphysics. Moreover, both programs collaborated in the solution of the inverse problem. Once the problem was solved, a sensitivity analysis was carried out in order to study the dependence of the numerical result on various parameters and optimize the inverse solution setup for application of recorded experimental data.The validated inverse solution setup examined by the sensitivity analyses was used on a set of experimental data, allowing the demonstration of the initially proposed hypothesis. This sensitivity analyses were performed consecutively for different key parameters regarding the numerical definition of the problem. The values for the parameters were considered optimal when minimum values for the error of the predicted surface temperature were recorded. In this case, the analyzed parameters were the m-value, mesh cell size, effect of noise, initial quenching temperature and quenching cooling rate. The connection between the experimental and numerical studies is obvious, as the first oneprovides the latter with input data of the inner temperature data of the specimen for the solving of the inverse problem, as is the case of the practical application of the code developed in the present thesis, and the inverse solution is essential in order to predict thesurface temperature and heat flux that are key information in studying quenching systems.
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SHIMODA, Masatoshi, Hideyuki AZEGAMI et Toshiaki SAKURAI. « Numerical Solution for Min-Max Shape Optimization Problems (Minimum Design of Maximum Stress and Displacement) ». 日本機械学会, 1998. http://hdl.handle.net/2237/12154.
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Lee, Jeffrey K. « A model for solving the capacitated facility location with multiple feasible facility sizes and an evaluation of a microcomputer based solution method ». Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/24358.
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Abbas, Aghababazadeh Farnoosh. « Estimating the Local False Discovery Rate via a Bootstrap Solution to the Reference Class Problem : Application to Genetic Association Data ». Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33367.
Texte intégralRésumé :
Modern scientific technology such as microarrays, imaging devices, genome-wide association studies or social science surveys provide statisticians with hundreds or even thousands of tests to consider simultaneously. Testing many thousands of null hypotheses may increase the number of Type $I$ errors. In large-scale hypothesis testing, researchers can use different statistical techniques such as family-wise error rates, false discovery rates, permutation methods, local false discovery rate, where all available data usually should be analyzed together. In applications, the thousands of tests are related by a scientifically meaningful structure. Ignoring that structure can be misleading as it may increase the number of false positives and false negatives. As an example, in genome-wide association studies each test corresponds to a specific genetic marker. In such a case, the scientific structure for each genetic marker can be its minor allele frequency.
In this research, the local false discovery rate as a relevant statistical approach is considered to analyze the thousands of tests together. We present a model for multiple hypothesis testing when the scientific structure of each test is incorporated as a co-variate. The purpose of this model is to incorporate the co-variate to improve the performance of testing procedures. The method we consider has different estimates depending on the tuning parameter. We would like to estimate the optimal value of that parameter by considering observed statistics. Thus, among those estimators, the one which minimizes the estimated errors due to bias and to variance is chosen by applying the bootstrap approach. Such an estimation method is called an adaptive reference class method. Under the combined reference class method, the effect of the co-variates is ignored and all null hypotheses should be analyzed together.
In this research, under some assumptions for the co-variates and the prior probabilities, the proposed adaptive reference class method shows smaller error than the combined reference class method in estimating the local false discovery rate, when the number of tests gets large. We describe the adaptive reference class method to the coronary artery disease data, and we use simulation data to evaluate the performance of the estimator associated with the adaptive reference class method.
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SHIMODA, Masatoshi, Hideyuki AZEGAMI et Toshiaki SAKURAI. « Multiobjective Shape Optimization of Linear Elastic Structures Considering Multiple Loading Conditions (Dealing with Mean Compliance Minimization problems) ». 日本機械学会, 1996. http://hdl.handle.net/2237/12155.
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Williams, Matthew J. « A Heuristic Solution to the Pickup and Delivery Problem with Applications to the Outsized Cargo Market ». Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1238514369.
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Matar, Merheb Rachel Rima. « Caractérisation d’une nouvelle génération de détergents stabilisateurs des transporteurs abc en solution : cristallisation de BmrA, transporteur ABC bactérien ». Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10303.
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En raison de leur résistance aux agents chimiothérapeutiques, les transporteurs ABC de phénotype MDR ont attiré l'attention de la communauté scientifique. Notre projet vise à trouver des conditions dans lesquelles les transporteurs ABC restent fonctionnels en solution pour aboutir à la cristallisation de ces protéines dans une conformation active. Dans ce but, nous avons conçu et développé une nouvelle classe de détergents, à base de calix[4]arène, qui stabilisent ces protéines. Afin de résoudre la structure 3D à résolution atomique du transporteur ABC bactérien "BmrA", responsable de la résistance aux antibiotiques, nous avons utilisé une approche classique utilisant des détergents commerciaux en parallèle à nos détergents innovants. En présence de la Foscholine 12, nous avons obtenu des cristaux diffractant jusqu’à 5 Å de résolution. Cependant, les données de diffraction n’étaient pas suffisantes pour déterminer la structure tridimensionnelle complète de la protéine, seuls les domaines transmembranaires ont été résolus. D'autre part, nous avons atteint l'objectif de l'extraction, la purification et la stabilisation de ce transporteur à l'aide des détergents à base de calix [4] arène. Nous avons également montré que ces détergents promeuvent et améliorent la cinétique de cristallisation de BmrA, une étape que nous sommes en train d’optimiser, pour obtenir des cristaux de meilleure résolution, pour résoudre la structure 3D de BmrA qui sera utilisé pour concevoir des inhibiteurs adaptésDue to their preponderance in the resistance to chemotherapies, the MDR ABC transporters have drawn the attention of the scientific community. Our project aimed at finding conditions in which ABC transporters are active in solution to lead the crystallization of these proteins in an active conformation. In this purpose, we conceived and developed a new class of detergents, based on calix[4]arene ring, that stabilize these proteins. In order to solve the 3D-structure to atomic resolution of bacterial ABC transporter “BmrA” responsible for antibiotic resistance, we used a classical approach with commercial detergents in addition to the innovative ones. We have crystallized the protein in presence of Foscholine 12 with a diffraction resolution up to 5 Å. The data was incomplete; solving partially the structure of the transmembrane domains. On the other hand, we have reached the objective of extraction, purification and stabilization of this transporter by using calix[4]arene-based detergents. We have also shown that these detergents promote and enhance the kinetics of crystallization of BmrA, a step that we are improving, to get crystals of better resolution, for resolving the BmrA 3D-structure which will be used to design adapted inhibitors
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Gaber, Tarek. « Support consumers' rights in DRM : a secure and fair solution to digital license reselling over the Internet ». Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/support-consumers-rights-in-drm-a-secure-and-fair-solution-to-digital-license-reselling-over-the-internet(6b653587-36d3-4074-8578-5eaacdb68004).html.
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Consumers of digital contents are empowered with numerous technologies allowing them to produce perfect copies of these contents and distribute them around the world with little or no cost. To prevent illegal copying and distribution, a technology called Digital Rights Management (DRM) is developed. With this technology, consumers are allowed to access digital contents only if they have purchased the corresponding licenses from license issuers. The problem, however, is that those consumers are not allowed to resell their own licenses- a restriction that goes against the first-sale doctrine. Enabling a consumer to buy a digital license directly from another consumer and allowing the two consumers to fairly exchange the license for a payment are still an open issue in DRM research area. This thesis investigates existing security solutions for achieving digital license reselling and analyses their strengths and weaknesses. The thesis then proposes a novel Reselling Deal Signing (RDS) protocol to achieve fairness in a license reselling. The idea of the protocol is to integrate the features of the concurrent signature scheme with functionalities of a License Issuer (LI). The security properties of this protocol is informally analysed and then formally verified using ATL logic and the model checker MOCHA. To assess its performance, a prototype of the RDS protocol has been developed and a comparison with related protocols has been conducted. The thesis also introduces two novel digital tokens a Reselling Permission (RP) token and a Multiple Reselling Permission (MRP) token. The RP and MRP tokens are used to show whether a given license is single and multiple resalable, respectively. Moreover, the thesis proposes two novel methods supporting fair and secure digital license reselling. The first method is the Reselling Deal (RD) method which allows a license to be resold once. This method makes use of the existing distribution infrastructure, RP, License Revocation List (LRL), and three protocols: RDS protocol RD Activation (RDA) protocol, and RD Completion (RDC) protocol. The second method is a Multiple License Reselling (MLR) method enabling one license to be resold N times by N consumers. The thesis presents two variants of the MLR method: RRP-MR (Repeated RP-based Multi-Reselling) and HC-MR (Hash Chain-based Multi-Reselling). The RRP-MR method is designed such that a buyer can choose to either continue or stop a multi-reselling of a license. Like the RD method, the RRP-MR method makes use of RP, LI, LRL, and the RDS, RDA, and RDC protocols to achieve fair and secure reselling. The HC-MR method allows multiple resellings while keeping the overhead on LI at a minimum level and enable a buyer to check how many times a license can be further resold. To do so, the HC-MR utilises MRP and the hash chain cryptographic primitive along with LRL, LI and the RDS, RDA and RDC protocols. The analysis and the evaluation of these three methods have been conducted. While supporting the license reselling, the two methods are designed to prevent a reseller from (1) continuing using a resold license, (2) reselling a non-resalable license, and (3) reselling one license a unauthorised number of times. In addition, they enable content owners of resold contents to trace a buyer who has violated any of the usage rights of a license bought from a reseller. Moreover, the methods enable a buyer to verify whether a license he is about to buy is legitimate for re-sale. Furthermore, the two methods support market power where a reseller can maximise his profit and a buyer can minimise his cost in a reselling process. In comparison with related works, our solution does not make use of any trusted hardware device, thus it is more cost-effective, while satisfying the interests of both resellers and buyers, and protecting the content owner's rights.
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Ni, Marcus. « Automated Hybrid Singularity Superposition and Anchored Grid Pattern BEM Algorithm for the Solution of the Inverse Geometric Problem ». Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5827.
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A method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of the estimated cavity(ies)/flaw(s) geometry(ies) is accomplished by utilizing an anchored grid pattern upon which cubic spline knots are restricted to move in the search for unknown geometry. Solution of the inverse problem is achieved using a genetic algorithm accelerated with the Nelder-Mead non-linear simplex. To optimize the cubic spline interpolated geometry, the flux (Neumann) boundary conditions are minimized using a least squares functional. The automated algorithm successfully reconstructs single and multiple subsurface cavities within two dimensional mediums. The solver is also shown to accurately predict cavity geometries with random noise in the boundary condition measurements. Subsurface cavities can be difficult to detect based on their location. By applying different boundary conditions to the same geometry, more information is supplied at the boundary, and the subsurface cavity is easily detected despite its low heat signature effect at the boundaries. Extensions to three-dimensional applications are outlined.M.S.M.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering; Thermo-Fluids
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ZONGO, WEND BENEDO EMMANUEL. « BOUNDARY VALUE PROBLEMS FOR QUASI-LINEAR AND HIGHER-ORDER ELLIPTIC OPERATORS AND APPLICATION TO BIFURCATION AND STABILIZATION ». Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/892091.
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In this thesis, we are interested in the study of nonlinear eigenvalue problem and the controllability of partial differential equations in a smooth bounded domain with boundary.
The first part is devoted to the analysis of an eigenvalue problem for quasilinear elliptic operators involving homogeneous Dirichlet boundary conditions.
We investigate the asymptotic behaviour of the spectrum of the related problem by showing on the one hand the bifurcation results from trivial solutions using the Krasnoselski bifurcation theorem and bifurcation from infinity using the Leray-Schauder degree on the other hand. We also prove the existence of multiple critical points using variational methods and the Krasnoselski genus.
At last, we show a stabilization result for the damped plate equation with logarithmic decay of the associated energy. The proof of this result is achieved by means of a proper Carleman estimate for the fourth-order elliptic operators involving the so-called Lopatinskii-Šapiro boundary conditions and a resolvent
estimate for the generator of the damped plate semigroup associated with these
boundary conditions.
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Zander, Johan. « Modelling mechanical properties by analysing datasets of commercial alloys ». Licentiate thesis, Stockholm : Industriell teknik och management, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4527.
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Gasmi, Sana. « Solutions périodiques multiples de l'équation de Duffing ». Paris 6, 2008. http://www.theses.fr/2008PA066047.
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Dans cette thèse, on s'intéresse à l'existence de solutions périodiques multiples pour une équation différentielle scalaire non linéaire du second ordre avec dissipation linéaire en présence d'une force extérieure périodique. On prouve l'existence d'exactement 3 solutions borne es asymptotes aux solutions quelconques de l' équation u''+cu'+|u|p u-u =f(t) lorsque t tend vers l'infini sous une certaine condition de petitesse sur le terme f et pour c assez grand. Ensuite, on prouve l'existence de N solutions sous-harmoniques pour l'équation de Duffing forcée avec dissipation x''+g(x)+ cx' = epsilonf(t) et on en déduit dans certains cas l'existence d'un grand nombre de sous harmoniques périodiques et anti-périodiques
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Seh-Jin, CHANG. « A Generalization of the Revelation Principle in an Informationally Decentralized Economy ». 名古屋大学大学院経済学研究科附属国際経済政策研究センター, 2009. http://hdl.handle.net/2237/14043.
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