Advanced Numerical Analysis Research Articles

Stability of photovotaic spatial soliton with two-wavelength components

An approximate method is presented to calculate the full width at half maximum(F WHM) of photovoltaic(PV) spatial solitons(PVSSs) with twowavelengths component . An advanced numerical analysis i ndicates that two coaxial hyperbolic secant beams, provided that they satisfy th e functional relations of FWHM with amplitudes of this type of PVSS, will be ver y close to solitons when they propagate in PV crystals. Besides, this type of PV S S tends to be stable against small axial perturbations and small refractive inde x perturbations due to variations of temperature of the crystal. However, if the pro files of intensity of two coaxial signal beams with different wavelengths diff e r mildly from those of PVSS, the two beams will tend to experience cycles of co mpression and expansion; and if the profiles of intensity of the signal beams di ffer significantly from those of PVSS, these two signal beams will diffuse endle ssly.

Influence of equivalent bolt length in finite element modeling of T-stub steel connections

In this paper the development and implementation of a finite element model for simple T-stub steel connections is presented. Material and geometric non-linearities as well as contact and friction have been implemented in the model. The model is validated by comparison with experimental data found in the literature, for configurations exhibiting different failure mechanisms and featuring different bolt preloading levels. The impact of bolt length considered in the model is investigated and is shown to be of primary importance. This issue is representative of the continuously increasing use of advanced numerical analysis, supported by progress in computational mechanics, as a tool for practical design of engineering structures.

Engineering optimization of an improved plancha stove

This paper presents an engineering model of an improved plancha stove and demonstrates the use of advanced numerical analysis to improve plancha stove effectiveness. The advanced numerical techniques used include coupling a genetic algorithm searcher with a computational fluid dynamics evaluation of the stove performance. The plancha stove is a popular stove design. Built from steel, brick, or cement, the plancha stove is a sealed stove with a steel or cast-iron cooking surface. This permits the combustion gases to be exhausted from the living quarters via a chimney. Frying of breads (i.e., tortillas) and other foods is performed directly on the cooking surface of the stove. In contrast, cooking operations requiring boiling or simmering are performed by placing a pot containing the food on the cooking surface. Because of this two-tiered arrangement (flame-stove, surface-pot-food), the plancha stove is thought to be less efficient than stoves in which the cookpot is in direct contact with the flame. There are several standard efficiency tests; in most cases these involve heating and boiling a given amount of water, measuring the fuel used, and accounting for latent and sensible heat. On this basis, efficiency is established as the ratio between the heat absorbed by the water and heat released by the fuel. Plancha stoves are used for a variety of cooking tasks, and many of these tasks conflict with one another. For example, cooking tortillas requires a large area heated to moderate temperatures (∼250°C); simmering requires a small area of slightly higher temperatures (∼400°C); and bringing a large pot to a quick hard boil is most efficient with very high temperatures (>600°C). Because of this, traditional measures of efficiency do not provide a complete understanding of the fitness of the stove for specific applications. Using numerical modeling and experimental testing, this paper demonstrates how a measure of fitness can be used to provide a more complete understanding of plancha stove efficiency and effectiveness. This understanding can be used to assess various plancha stove designs and to determine which design provides the most benefit in a specific application.

Development of a Highly Loaded Rotor Blade for Steam Turbines. 1st Report, Cascades Performance.

Turbine manufacturers have been concerned about efficient utilization of limited energy resources and prevention of environmental pollution. For steam turbine power plants, a higher efficiency gain is necessary to reduce the fuel consumption rate. Blade configurations have been studied for reductions of profile loss and endwall loss that lead to decreased steam turbine internal efficiency, by applying recent aerodynamic technologies based on advanced numerical analysis methods. This paper discusses increase of pitch-chord ratio by 14% (reduction of rotor blade numbers by 14%) and increased blade aerodynamic loading without deterioration of performance. A new rotor cascade is found which improves blade performance, especially at the root section where the reduction in the energy loss coefficient is about 40%. This rotor blade also provides lower manufacturing cost.

SOIL-STRUCTURE INTERACTION ANALYSES FOR CHESTFIELD TUNNEL, KENT.

Keywords: W S ATKINS , KENT COUNTY COUNCIL SOILS , STRUCTURES , INTERACTION , ANALYSIS , TUNNELS , ADVANCED , NUMERICAL , FINITE ELEMENTS , FINITE DIFFERENCE , METHODS , COMPUTERS , COSTS , SAVINGS , WORKS , PERMANENT , A299 , RESEARCH , BEHAVIOUR , PLASTICITY , CLAYS , BACKFILL , FILL , TUNNELLING , CONCRETE , REINFORCED , BOX , CUT AND COVER , LONDON CLAY , CELLS , TWIN , GROUND , DEFORMATION , LOADING , LOADS , STIFFNESS , ELASTIC , SOLUTIONS , FLAC , FAST , LANGRANGIAN , MEMBERS , FORCES , DEFLECTION , PORTAL , MODELS , CROSS SECTIONS , BENDING , LONGITUDINAL , ROADS , HIGHWAYS , STRUCTURES , DESIGN , CONTINUUM , DESKTOP , SETTLEMENT , INST CHESTFIELD , KENT UK ... Show All

Applied electromagnetics research and application

Applied electromagnetics researches have been done in the laboratory as one of off-pile research activities. Applied electromagnetics is very important for the design and analysis of magnetic confinement fusion devices and nondestructive evaluation of nuclear fission reactors. Especially, we have developed many numerical analytic methods to solve electromagnetomechanical coupled phenomena in fusion first walls. The numerical results have been validated by the experiments. On the other hand, magnetic nondestructive evaluation plays one of the most important inspections of commercial fission reactor. We are proceeding this magnetic nondestructive evaluation research based on many advanced numerical analysis techniques and the state-of-art sensor technology. Here we describe the analysis of eddy current and magnetic damping of the fusion first wall and several new numerical and experimental techniques in the magnetic nondestructive evaluation for nuclear engineering.

Some aspects of using the SimuSolv program for environmental, pharmacokinetics and toxicological applications

Using “model-aided research” techniques to quantify the above mentioned processes is enabled with a math modeling tool like the SimuSolv simulation, parameter estimation and optimization software package. Complex, multiresponse and multicompartment processes can not be represented in a rigorous fashion with traditional, and more empirical, linearization techniques. Advanced numerical integration, sensitivity analysis, nonlinear statistics and nonlinear optimization methods are necessary to fully describe a process in a truly mechanistic sense. Realizing this higher level approach to math modeling without being an expert in numerical methods or computing can be accomplished via the SimuSolv software. This model-aided research process and the mathematical components imbedded therein as well as the application in several examples are described.

Parallel Computers : A Personal Overview

This paper offers a brief and general introduction to parallel computers and a description of the PACE (Process for Aerodynamic Computation & Evaluation) parallel computer project executed by the Advanced Numerical Research & Analysis Group (ANURAG), Hyderabad. Also included are a brief review of the global scene as well as the author's personal reflections on recent trends in the country in the area of parallel computers This paper offers a brief and general introduction to parallel computers and a description of the PACE (Process for Aerodynamic Computation & Evaluation) parallel computer project executed by the Advanced Numerical Research & Analysis Group (ANURAG), Hyderabad. Also included are a brief review of the global scene as well as the author's personal reflections on recent trends in the country in the area of parallel computers

Development of Parallel Algorithms for Computer Vision

Computer vision is an important research area where computationally-intensive and time critical problems need to be solved routinely. This paper described some parallel algorithms for image processing and computational geometry applicable to the field of 'robot vision' which was developed using PACE parallel computer, a closely coupled message passing MIMD machine, designed and developed at the Advanced Numerical Reserach & Analysis Group, Hyderabad.

Numerical Methods Based on Sinc and Analytic Functions.

Many mathematicians, scientists, and engineers are familiar with the Fast Fourier Transform, a method based upon the Discrete Fourier Transform. Perhaps not so many mathematicians, scientists, and engineers recognize that the Discrete Fourier Transform is one of a family of symbolic formulae called Sinc methods. Sinc methods are based upon the Sinc function, a wavelet-like function replete with identities which yield approximations to all classes of computational problems. Such problems include problems over finite, semi-infinite, or infinite domains, problems with singularities, and boundary layer problems. Written by the principle authority on the subject, this book introduces Sinc methods to the world of computation. It serves as an excellent research sourcebook as well as a textbook which uses analytic functions to derive Sinc methods for the advanced numerical analysis and applied approximation theory classrooms. Problem sections and historical notes are included.

Advances in Numerical Analysis, Vol. I: Nonlinear Partial Differential Equations and Dynamical Systems.

Advances in Numerical Analysis, Vol. I: Nonlinear Partial Differential Equations and Dynamical Systems.

Advances in Numerical Analysis, Vol. II: Wavelets, Subdivision Algorithms, and Radial Basis Functions.

Advances in Numerical Analysis, Vol. II: Wavelets, Subdivision Algorithms, and Radial Basis Functions.

Pose determination of parameterized object models from a monocular image

Abstract Pose determination of parameterized object models plays an important role in verification of model based recognition systems and real-time tracking of objects in images. Described herein is a data structure that models 3D parametric objects. Algorithms are presented for obtaining analytical partial derivatives of distance functions from projected model edges and endpoints to corresponding image segments, with respect to changes in model and camera parameters. These parameters include rotational, translational, scale and dilation in camera and object model. Solving for camera and model parameters in a 2D image (pose determination) is a nonlinear least squares paradigm. Weights are considered for line-to-line and point-to-point matchings to allow for the applicability of the methods to images with noisy data. A number of complex models are tested, and convergence to proper values occurs from a wide range of initial error, using advanced numerical analysis techniques. The experimentation suggests that by treating the model and camera parameters uniformly, correct pose determination can be obtained from minimal matching information relative to the number of matches required per component individually. The robust verification of model parameters thus simplifies associated object recognition problems.

Strength Predictions in Bonded Joints-Current Thoughts and Research at the University of Bristol, U.K.

Abstract Our basic aim is to devise methods of predicting the strength of adhesively-bonded joints. We recognise that to do this on a full scientific basis, using a combination of material science and advanced numerical analysis for stress and strain analysis, is only possible in a university or advanced industrial laboratory.

気液二相流数値解析用ベンチマーク問題 （ＩＩ） 解析上の困難さに遭遇する課題

The present status and future problems of numerical analysis on two-phase flow dynamics were investigated in the Working Group of Two-Phase Flow in the Special Committee on Advanced Numerical Analysis of Thermal Hydraulics, AESJ. It is clarified from the study that the present technology of numerical analysis still has many problems to be solved through further investigations. Then, phenomena of difficulty in analyzing numerically have been picked up. It is made clear the phenomena may be classified into three categories; (1) related to flow condition, (2) related to thermal non-equilibrium state, and (3) related to numerical method. Many researchers require common problems for the further investigations. Therefore, the benchmark problems have been selected based on these categories.In the Working Group, benchmark problems related to (1) and (2) and selected in the previous paper have been reconsidered and selected additionally. Furthermore, benchmark problems concerning (3) have been selected. Summaries of these benchmark problems authorized by many researchers are presented in this paper.

気液二相流数値解析用ベンチマーク問題 （１） 解析上の困難さに遭遇する課題

The present status of numerical analysis on two-phase flow dynamics has been reviewed and systematized in the Working Group of Two-Phase Flow in the Special Committee on Advanced Numerical Analysis of Thermal Hydraulics, AESJ. It is seen from the research study that the present technology of numerical analysis still has many problems to be solved through further investigations. Then, phenomena of difficulty in analyzing numerically have been picked up. It is made clear the phenomena may be classified into three categories; (1) related to flow condition, (2) related to thermal non-equilibrium state and (3) related to numerical method.Common problems to many researchers are required for the further investigations. Hence, the benchmark problems have been selected based on these categories. The following are represented in this paper:(1) Purpose and methodology of selecting the benchmark problems, (2) Summaries of the benchmark problems concerning flow condition and thermal non-equilibrium state which have been selected and authorized by many specialists.

Current development in the numerical treatment of ocean acoustic propagation

Many methods exist for determining the solution of linear ocean acoustic wave propagation problems. A number of solutions have been found by conventional analytic methods. These methods have been refined in recent years and their computation enhanced by advances in numerical analysis and the availability of supercomputers. However, no single method exists that is adequate for all applications mainly due to our inability to handle sophisticated variable ocean environments and the present limitation on computer speed and accuracy. Still a number of important contributions for determining solutions have recently been developed. These contributions plus effective numerical procedures permit environmental conditions to be handled, in part, realistically in a systematic manner. This survey begins with a brief review of existing problems and the progress toward their solutions. Among the most important contributions made in recent years are: “the improved parabolic equation,” “the numerical treatment of ocean interface conditions,” “the wide angle wave equation,” and “the numerical solution of three-dimensional ocean acoustic problems”; we choose to highlight the “wide angle wave equation.” A discussion on a range of unsolved problems is given which is used to emphasize the need for further reasearch.

Operator-theoretic and computational approaches to Ill-posed problems with applications to antenna theory

A general framework for regularization and approximation methods for ill-posed problems is developed. Three levels in the resolution processes are distinguished and emphasized: philosophy of resolution, regularization-approximation schema, and regularization algorithms. Dilemmas and methodologies of resolution of ill-posed problems and their numerical implementations are examined in this framework with particular reference to the problem of finding numerically minimum weighted-norm least-squares solutions of first kind integral equations (and more generally of linear operator equations with nonclosed range). A common problem in all these methods is delineated: each method reduces the problem of resolution to a nonstandard minimization problem involving an unknown critical parameter whose optimal value is crucial to the numerical realization and amenability of the method. The nonstandardness results from the fact that one does not have explicitly, or a priori, the function to be minimized; it has to built up using additional information, convergence rate estimates, and robustness conditions, etc. Several results are developed that complement recent advances in numerical analysis and regularization of inverse and ill-posed (identification and pattern synthesis) problems. An emphasis is placed on the role of constraints, function space methods, the role of generalized inverses, and reproducing kernels in the regularization and stable computational resolution of these problems. The results will be applied specifically to problems of antenna synthesis and identification. However the thrust of the paper is devoted to the interdisciplinary character of operator-theoretic and numerical methods for ill-posed problems.

Note on a global homotopy

In a lecture given at the M.R.C. Symposiucn on Recent Advances in Numerical Analysis in May, 1978, H. B. Keller discussed a global homotopy method for finding solutions of f (u) = 0. At that time he was unable to show that one of the hypotheses of his main result is satisfied by almost all initial points for paths determined by his method. The purpose of this note is to fill that gap in Keller's result.

On the computational competitiveness of full-information maximum-likelihood and three-stage least-squares in the estimation of nonlinear, simultaneous-equations models

While full-information maximum-likehood (FIML) estimation has long been considered an important theoretical econometric estimation technique, computational considerations have greatly restricted its use in practice. Recent advances in numerical analysis and in computational software, however, have combined to provide algorithms capable of carrying out the FIML calculations quite efficiently relative to past standards. This paper compares the computational competitiveness of FIML with its most popular competitor, 3SLS, in the estimation of a variety of linear and non-linear (in parameters and variables) models. The nonlinear full-information maximum-likelihood (NLFIML) estimator is described and a computatíonally efficient approximation, TRUNFIML, is defined. Nonlinear three-stage least-squares (NL3SLS) is accomplished by the method of Jorgenson-Laffont. Comparisons are made on the basis of numbers of iterations to convergence, number of function evaluations, and total computer CPU time required, this latter figure being most relevant to a comparison of computational effort and cost.