Solution Of Structural Problems Research Articles

Toward Optimality of Proper Generalised Decomposition Bases

The solution of structural problems with nonlinear material behaviour in a model order reduction framework is investigated in this paper. In such a framework, greedy algorithms or adaptive strategies are interesting as they adjust the reduced order basis (ROB) to the problem of interest. However, these greedy strategies may lead to an excessive increase in the size of the ROB, i.e., the solution is no more represented in its optimal low-dimensional expansion. Here, an optimised strategy is proposed to maintain, at each step of the greedy algorithm, the lowest dimension of a Proper Generalized Decomposition (PGD) basis using a randomised Singular Value Decomposition (SVD) algorithm. Comparing to conventional approaches such as Gram–Schmidt orthonormalisation or deterministic SVD, it is shown to be very efficient both in terms of numerical cost and optimality of the ROB. Examples with different mesh densities are investigated to demonstrate the numerical efficiency of the presented method.

3D Tomographic Inversion of TEM Sounding Data

Abstract —One of the main objectives of geoelectric prospecting is mapping of the consolidated low-conductivity basement geometry. To resolve the issue, it will be equally important to delineate local structures at the bottom of the sedimentary complex and to estimate the misinterpretation of results due to the presence of areas with nonuniform conductivity in the stratified geologic cross section. Another relevant objective of EM sounding is to resolve the problem of delineation of anticlinal oil and gas traps. The horizontally layered model with a local inclusion of 3D abnormal areas is certain to fit for the above-mentioned objectives. The study is concerned with the technique of nonstationary EM sounding. When applied for the solution of structural problems, this technique considers the uniform distribution of fields within relatively large volume units of the space explored. Consequently, it results in the more efficient application of the perturbation technique (Born approximation) for the solution of the forward electrodynamics problem. The study presents the findings of 3D tomographic inversion with the use of synthetic and physical modeling data. They definitely allow us to acknowledge that the proposed mathematical apparatus for 3D inversion based on Born linearization of the forward problem has proved to be quite applicable.

A physical perspective of the element‐based finite volume method and FEM‐Galerkin methods within the framework of the space of finite elements

SUMMARYThe literature shows an increasing number of works focused on investigating the behaviour of methods that uses concepts of control volumes in the solution of structural problems. In recent years, new approaches using unstructured meshes have been proposed, most of which addressing new applications and, to a lesser extent, the underling physical perspective. This paper presents a unified approach to the element‐based finite volume method and FEM‐Galerkin within the framework of the finite element space. Numerical examples highlight some accuracy issues associated with the element‐based finite volume method developed in this work. Copyright © 2014 John Wiley & Sons, Ltd.

Laboratory of N.V. Belov as a school of highly qualified experts

The occasion of Nikolai Vasil’evich Belov’s 120th birthday is a good reason for recalling the works of this prominent representative of the pleiad of famous Russian and foreign crystallographers. Not only experts in structural crystallography passed through his school. The number of postgraduates that became candidates of sciences (and some, later, doctors) under the guidance of Belov is amazing. Many of his students organized and headed new laboratories at the Institute of Crystallography and at other institutes. We all remember the original methods proposed by Belov for determining the atomic structure of crystals in periods before and after the time when computers arose. New directions in the study of minerals and the solution of structural problems of crystal chemistry, crystal physics, and materials science continue in the community of crystallographers. They are being actively developed, and not only by Belov’s students.

An Approach to Masonry Structural Analysis by the No-Tension Assumption—Part I: Material Modeling, Theoretical Setup, and Closed Form Solutions

The prevalent feature that characterizes masonry structures and makes them dissimilar from modern reinforced concrete and steel structures is quite definitely their inability to resist tensile stresses. Therefore, it is natural that the material model that is intended to be an “analog” of real masonry cannot resist tensile stress but possibly behaves elastically under pure compression, opening a perspective on the adoption of the no-tension (NT) material constitutive assumption. Founded on the NT theory, the basic direction and aim of the present work is to propose a unified treatment of masonry structures presenting an overall and comprehensive up-to-date insight in the analysis of masonry constructions while providing basic and advanced concepts and tools already available or original. The note is intended to lead to several notable results including, just to mention some of the outcomes, that the St. Venant’s postulate does not hold in NT solids, no energy is dissipated by fracture, special accommodations for discontinuous loads are needed, and the relevant developments are provided, among other significant outcomes such as the identification of operative procedures for engineering solutions of structural problems. In the first part of the paper, the basics for the foundation of a NT material theory are illustrated, and the relevant principles for structural analysis, mainly identified in the classic energy theorems and suitably adapted to the material at hand, are formulated. In (apparently) simple cases, closed-form solutions can be obtained, or, at least, the solution process can be prepared after a preliminary screening of the equilibrium scenario. The application to two-dimensional no-tension elasticity is then illustrated in the last section, with reference to two sample cases. The first example proves that the solution in a NT panel acted on by vertical loads on the top is clearly identified in terms of stress, but if discontinuities are present in the load pattern, these reflect in some strong singularities in the deformation field that requires to deepen the problem. The second example is concerned with a NT-elastic half-plane, and a technique to find approximate solutions is outlined and carried on in detail. In Part II of the note, it is demonstrated that discontinuous or lumped load patterns can be looked at as frontier cases: They are not in contrast, but in some sense they are not natural to NT solids. Still in Part II, it is shown how the equilibrium problem can be managed both through the strain and the stress approach.

Fuzzy Structure Generation: A New Efficient Tool for Computer‐Aided Structure Elucidation (CASE).

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Fuzzy Structure Generation: A New Efficient Tool for Computer-Aided Structure Elucidation (CASE)

Contemporary Computer-Aided Structure Elucidation (CASE) systems are heavily based on the utilization of 2D NMR spectra. The utilization of HMBC/GHMBC and COSY/GCOSY correlations generally assumes that these correlations result from (2-3)JCH and (2-3)JHH spin-spin couplings, respectively, and consequently these values are used as the default setting in these systems. Our previous studies1,2 have shown that about half of the problems studied actually contain some correlations of 4-6 bonds, so-called "nonstandard" correlations. In such cases the initial 2D NMR data are contradictory, and the correct solution is therefore not directly attainable. Unfortunately nonstandard correlations and the number of intervening bonds usually cannot be identified experimentally. In this work we suggest a new approach that we term Fuzzy Structure Generation. This allows the solution of structural problems whose 2D NMR data contain an unknown number of nonstandard correlations having different and unknown lengths. Suggested methods for the application of Fuzzy Structure Generation are described, and their application is illustrated by a series of real-world examples. We conclude that Fuzzy Structure Generation is efficient, and there is no real alternative at present in terms of a universal practical method for the structure elucidation of organic molecules from 2D NMR data.

Semantic integration of conceptual schemas

Our goal is to work out an integration process which makes it possible to give a global design schema obtained from several schemas, each of them describing the same reality viewed in different ways, in order to obtain the fullest view. Problems and conflicts arise during the schema integration. They are due to the several ways of representing the semantic knowledge and of structuring knowledge (using the same design model). When the detection and solution of structural problems are model dependent, the detection and solution of semantic problems are not model dependent. To represent the semantic of the words which are used in a schema, we have defined a model of a thesaurus drawn from the domain dealing with the meaning of words: linguistics. In this paper, we will show the interest in using this fuzzy thesaurus when design schema are being integrated.

Electron diffraction study of molecular structure of salts of oxo acids and complex halides. 1. Approach to solution of structural problem

Electron diffraction study of molecular structure of salts of oxo acids and complex halides. 1. Approach to solution of structural problem

Solution of Structural Problems in the Topia Ag-Au-Pb-Zn District, Durango, Mexico, Using Laser Decrepitation and Capacitance Manometer Gas Analysis for Fluid Inclusion Geobarometry

Solution of Structural Problems in the Topia Ag-Au-Pb-Zn District, Durango, Mexico, Using Laser Decrepitation and Capacitance Manometer Gas Analysis for Fluid Inclusion Geobarometry

On the solution of creep induced buckling in general structure

This paper considers the pre and post buckling behavior of general structures exposed to high temperature fields for long durations wherein creep effects become significant. The solution to this problem is made possible through the use of closed upper bounding constraint surfaces which enable the development of a new time stepping algorithm. This permits the stable and efficient solution of structural problems which exhibit indefinite tangent properties. Due to the manner of constraining/bounding successive iterates, the algorithm developed herein is largely self adaptive, inherently stable, sufficiently flexible to handle geometric material and boundary induced nonlinearity, and can be incorporated into either finite element or difference simulations. To illustrate the capability of the procedure, as well as, the physics of creep induced pre and post buckling behavior, the results of several numerical experiments are included.

A unified formulation of the finite and boundary element methods, using energy methods

This paper presents an overall view of the employment of energy methods to the solution of structural problems. This kind of formulation, when applied to the boundary element method, starting with the application of the Petrov-Galerkin method to the domain, instead of its boundary, followed by an integration by parts, permits us to maintain the variational interpretation of the method, that is, the idea of the approximate minimization of a quadratic functional, associated with the structural problem under consideration.

Use of the computer for the solution of structural problems in organic chemistry by the methods of molecular spectroscopy

Use of the computer for the solution of structural problems in organic chemistry by the methods of molecular spectroscopy

Use of the INDOR Technique in the Solution of Structural Problems in Organophosphorus Chemistry

Angewandte Chemie International Edition in EnglishVolume 7, Issue 10 p. 814-815 Communication Use of the INDOR Technique in the Solution of Structural Problems in Organophosphorus Chemistry Doz. Dr. R. Kosfeld, Doz. Dr. R. Kosfeld Institut für Physikalische Chemie der Technischen Hochschule, 51 Aachen (Germany)Search for more papers by this authorDipl.-Chem. G. Hägele, Dipl.-Chem. G. Hägele Institut für Anorganische Chemie der Universität, 4 Düsseldorf, Ulenbergstr. 127–129 (Germany)Search for more papers by this authorProf. Dr. W. Kuchen, Corresponding Author Prof. Dr. W. Kuchen Institut für Anorganische Chemie der Universität, 4 Düsseldorf, Ulenbergstr. 127–129 (Germany)Institut für Anorganische Chemie der Universität, 4 Düsseldorf, Ulenbergstr. 127–129 (Germany)Search for more papers by this author Doz. Dr. R. Kosfeld, Doz. Dr. R. Kosfeld Institut für Physikalische Chemie der Technischen Hochschule, 51 Aachen (Germany)Search for more papers by this authorDipl.-Chem. G. Hägele, Dipl.-Chem. G. Hägele Institut für Anorganische Chemie der Universität, 4 Düsseldorf, Ulenbergstr. 127–129 (Germany)Search for more papers by this authorProf. Dr. W. Kuchen, Corresponding Author Prof. Dr. W. Kuchen Institut für Anorganische Chemie der Universität, 4 Düsseldorf, Ulenbergstr. 127–129 (Germany)Institut für Anorganische Chemie der Universität, 4 Düsseldorf, Ulenbergstr. 127–129 (Germany)Search for more papers by this author First published: October 1968 https://doi.org/10.1002/anie.196808142Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume7, Issue10October 1968Pages 814-815 RelatedInformation

Operational Analog Simulation of the Vibration of a Beam and a Rectangular Multicellular Structure

A feasibility study of the use of an operational analog computer for solution of structural problems was undertaken. A beam problem and a rectangular multicellular structure problem were run to test the method. In this paper, which is a progress report, it is shown that the method is highly competitive with digital computer and passive-element computer methods for solution of any structural problem.

Small Pseudochitinous and Resinous Microfossils: New Tools for the Subsurface Geologist

The study of the Chitinozoa (possibly an extinct order of marine protozoans) and Tasmanites (probably a family of fossil algae) is generally included in the field of palynology, along with the study of polospores. Work in the Williston basin and other areas containing Paleozoic carbonate rocks indicates that the Chitinozoa and Tasmanites make ideal tools for use by the subsurface geologist. Because of their nearly indestructible nature, these fossils may be concentrated in and recovered from the insoluble residue from drill chips used in normal sample examination. They are well adapted for use as an aid in solving problems of correlation, zonation, and age dating. In the Williston basin the Chitinozoa and Tasmanites have been used as an aid in the reconstruction of the Or ovician surface section, in the subdivision of this section, and in extending these subdivisions into the subsurface. These micro-microfossils have aided in the solution of structural problems, and offer possibilities as a tool for age dating of Paleozoic rocks over very wide areas.

Small Pseudochitinous and Resinous Microfossils: New Tools for Subsurface Geologist: ABSTRACT

The study of palynomorphs (small, nearly indestructible fossils) is generally included in the field of palynology, along with the study of polospores. Palynomorphs and polospores are included in a group of fossils sometimes designated as micro-microfossils because of their small size. Work in the Williston Basin and other areas containing Paleozoic carbonate rocks indicate that certain groups of palynomorphs make an ideal tool for use by the subsurface geologist. These fossils, chiefly the Chitinozoa (possibly an extinct order of marine protozoans) and Tasmanites (probably a family of fossil algae), may be concentrated in and recovered from the insoluble residue from drill chips utilized in the course of normal sample examination. They are well adapted for use as an aid i solving problems of correlation, zonation, and age-dating. In the Williston Basin the Chitinozoa and Tasmanites have been used as an aid in the reconstruction of the Ordovician surface section, in the subdivision of this section, and in carrying these subdivisions into the subsurface. These micro-micro-fossils have aided in the solution of structural problems, and offer possibilities as a tool for age-dating of Paleozoic rocks over very wide areas. End_of_Article - Last_Page 958------------

Operational Analog Simulation of the Vibration of a Beam and a Rectangular Multicellular Structure

A feasibility study of the use of an operational analog computer for solution of structural problems was undertaken. A beam problem and a rectangular multicellular structure problem were run to test the method. In this paper, which is a progress report, it is shown that the method is highly competitive with digital computer and passive-element computer methods for solution of any structural problem.

Use of Modern Computers in Structural Analysis

How automatic computer works and how it may be used in solution of structural problems; functional description of digital computer; automatic computer program; computer methods of structural analysis; matrix formulation of load-deformation relationship; examples given.

Application du dosage quantitatif dans 1'infra-rouge de groupements fonctionnels et radicaux spécifiques à la résolution de problèmes chimiques: Spectres d'absorption infra-rouges des depsides—note n [1

The possibility of applying the KBr-disc technique in the quantitative infra-red analysis of specific structural groups was studied. In particular the method was applied to establish the formula of complex ethers derived from aromatic acids, such as caffeic, and alicyclic polyhydroxy-acids such as quinic acid. It was found that the spectra of the more complex compounds show a perfect additivity of the spectra of the simple starting materials, both qualitatively and quantitatively. When assigning particular bands to specific oscillators (C=O, C=C) or to entire caffeic and quinic radicals and allowing for the relative molecular concentration, empirical absorption coefficients can be calculated for every oscillator or radical. It is then also possible to calculate beforehand the amount of absorbance expected for specific bands in similar compounds. The agreement between calculated and experimental values is very satisfactory and allows the solution of structural problems which are difficult to solve by chemical methods.