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A simple and efficient re‐analysis procedure is presented for large‐scale structural systems. The procedure is based on using a mixed formulation with the fundamental unknowns consisting of both stress and displacement parameters. The other key elements of the procedure are: (a) lumping of the large number of design variables into a single tracing parameter; (b) operator splitting or additive decomposition of the different arrays in the finite element equations of the modified structure into the corresponding arrays of the original structure plus correction terms; and (c) application of a reduction method through the successive use of the finite element method and the classical Bubnov‐Galerkin technique. The finite element method is first used to generate a few approximation vectors (or modes). Then the amplitudes of these modes are computed by using the Bubnov—Galerkin technique. The re‐analysis procedure is applied to the linear static and free vibration problems of plate and shell structures. Changes in both the sizing and shape (configuration) design variables are considered. The high accuracy of the proposed technique, for sizable changes in the design variables, is demonstrated by means of numerical examples of composite plates and shells.

Two efficient computational procedures are presented for generating the global approximation vectors used in conjunction with the reduction methods for the large‐deflection non‐linear analysis of symmetric structures with unsymmetric boundary conditions. Both procedures are based on restructuring the governing equations for each of the unsymmetric global approximation vectors to delineate the different contributions to the symmetric and antisymmetric components of this vector. In the first procedure the unsymmetric global approximation vectors are approximated by linear combinations of symmetric and antisymmetric modes, which are generated by using the finite element method. The amplitudes of these modes are computed by using the classical Rayleigh‐Ritz technique. The second procedure is based on using a preconditioned conjugate gradient (PCG) technique for generating the global approximation vectors, and selecting the preconditioning matrix to be the matrix associated with the symmetric response. In both procedures the size of the analysis model used in generating the global approximation vectors is identical to that of the corresponding structure with symmetric boundary conditions. The similarities between the two procedures are identified, and their effectiveness is demonstrated by means of two numerical examples of large‐deflection, non‐linear static problems of shells.

A computational procedure is presented for the re‐analysis of large unsymmetric structural systems. The procedure is based on a novel partitioning strategy in which the responses of both the original and modified structures are approximated by linear combinations of symmetric and antisymmetric response vectors (or modes), each obtained by using a fraction of the degree of freedom of the finite element model of the structure. The other key elements of the procedure are: (a) lumping of the large number of design variables into a single tracing parameter; (b) operator splitting or restructuring of the governing finite element equations to delineate the symmetric and antisymmetric vectors constituting the responses of the original and modified structures; and (c) a stable and efficient iterative process for generating the response of the modified structure. The re‐analysis procedure is applied to linear static analysis of framed structures. Design modifications consisted of removing members resulting in topologically unsymmetric structures. The potential of the procedure on multiprocessor computers is discussed and its effectiveness is demonstrated by means of two numerical examples.

Error indicators are introduced as part of a simple computational procedure for improving the accuracy of the finite element solutions for plate and shell problems. The procedure is based on using an initial (coarse) grid and a refined (enriched) grid, and approximating the solution for the refined grid by a linear combination of a few global approximation vectors (or modes) which are generated by solving two uncoupled sets of equations in the coarse grid unknowns and the additional degrees of freedom of the refined grid. The global approximation vectors serve as error indicators since they provide quantitative pointwise information about the sensitivity of the different response quantities to the approximation used. The three key elements of the computational procedure are: (a) use of mixed finite element models with discontinuous stress resultants at the element interfaces; (b) operator splitting, or additive decomposition of the finite element arrays for the refined grid into the sum of the coarse grid arrays and correction terms (representing the refined grid contributions); and (c) application of a reduction method through successive use of the finite element method and the classical Bubnov—Galerkin technique. The finite element method is first used to generate a few global approximation vectors (or modes). Then the amplitudes of these modes are computed by using the Bubnov—Galerkin technique. The similarities between the proposed computational procedure and a preconditioned conjugate gradient (PCG) technique are identified and are exploited to generate from the PCG technique pointwise error indicators. The effectiveness of the proposed procedure is demonstrated by means of two numerical examples of an isotropic toroidal shell and a laminated anisotropic cylindrical panel.

A computational procedure is presented for the efficient non‐linear dynamic analysis of quasi‐symmetric structures. The procedure is based on approximating the unsymmetric response vectors, at each time step, by a linear combination of symmetric and antisymmetric vectors, each obtained using approximately half the degrees of freedom of the original model. A mixed formulation is used with the fundamental unknowns consisting of the internal forces (stress resultants), generalized displacements and velocity components. The spatial discretization is done by using the finite element method, and the governing semi‐discrete finite element equations are cast in the form of first‐order non‐linear ordinary differential equations. The temporal integration is performed by using implicit multistep integration operators. The resulting non‐linear algebraic equations, at each time step, are solved by using iterative techniques. The three key elements of the proposed procedure are: (a) use of mixed finite element models with independent shape functions for the stress resultants, generalized displacements, and velocity components and with the stress resultants allowed to be discontinuous at interelement boundaries; (b) operator splitting, or restructuring of the governing discrete equations of the structure to delineate the contributions to the symmetric and antisymmetric vectors constituting the response; and (c) use of a two‐level iterative process (with nested iteration loops) to generate the symmetric and antisymmetric components of the response vectors at each time step. The top‐ and bottom‐level iterations (outer and inner iterative loops) are performed by using the Newton—Raphson and the preconditioned conjugate gradient (PCG) techniques, respectively. The effectiveness of the proposed strategy is demonstrated by means of a numerical example and the potential of the strategy for solving more complex non‐linear problems is discussed.

A two‐step computational procedure is presented for reducing the size of the analysis model for an anisotropic symmetric structure to that of the corresponding orthotropic structure. The key elements of the procedure are: (a) decomposition of the stiffness matrix into the sum of an orthotropic and non‐orthotropic (anisotropic) parts; and (b) successive application of the finite element method and the classical Rayleigh—Ritz technique. The finite element method is first used to generate few global approximation vectors (or modes). Then the amplitudes of these modes are computed by using the Rayleigh—Ritz technique. The global approximation vectors are selected to be the solution corresponding to zero non‐orthotropic matrix and its various‐order derivatives with respect to an anisotropic tracing parameter (identifying the non‐orthotropic material coefficients). The size of the analysis model used in generating the global approximation vectors is identical to that of the corresponding orthotropic structure. The effectiveness of the proposed technique is demonstrated by means of numerical examples and its potential for solving other quasi‐symmetric problems is discussed.

An object‐oriented event‐driven immersive virtual environment is described for the creation of virtual labs (VLs) for simulating physical experiments. Discussion focuses on a number of aspects of the VLs, including interface devices, software objects, and various applications. The VLs interface with output devices, including immersive stereoscopic screen(s) and stereo speakers; and a variety of input devices, including body tracking (head and hands), haptic gloves, wand, joystick, mouse, microphone, and keyboard. The VL incorporates the following types of primitive software objects: interface objects, support objects, geometric entities, and finite elements. Each object encapsulates a set of properties, methods, and events that define its behavior, appearance, and functions. A “container” object allows grouping of several objects. Applications of the VLs include viewing the results of the physical experiment, viewing a computer simulation of the physical experiment, simulation of the experiment’s procedure, computational steering, and remote control of the physical experiment. In addition, the VL can be used as a risk‐free (safe) environment for training. The implementation of virtual structures testing machines, virtual wind tunnels, and a virtual acoustic testing facility is described.

The chapter examines and challenges the assumed necessity of a linkage between remembered series of exchanges, amicable social relations, and prestige found in the work of Marcel Mauss and many subsequent theorists of reciprocity and gift exchange.

The chapter uses the nearly 500 year history of the giving and taking of the Koh-i-noor Diamond by rulers of South and Central Asia, commencing with Babur, the first Mughal emperor, and ending with Queen Victoria, which includes some gift giving and much taking by force, to explore what happens when only two of the three elements Mauss assumed central to understanding gift exchange are present.

Based on a review of the historical material, the chapter demonstrates that though historical narratives or memories of exchanges were central to enhancing the prestige of the parties to the exchange and the diamond itself, that process could and did occur in the absence of any on-going amicable social relations, including in situations in which exchange or transfer of the diamond were coerced and nothing was given in return to the dispossessed former owner of the gem.

By suggesting an alternative configuration of the factors necessary for the association of exchange and prestige, the chapter provides the opportunity to reconsider assumptions common in the literature on gift exchange and further enhance our understanding of this central element of social theory.

The purpose of this review is to narrate the microbiological quality of variety of street foods which are largely consumed by the Bangladeshi people of all ages. However, these foods are prone to microbial contamination. Most of the vendors lack the awareness on hygiene during preparing, processing or handling the foods. The insufficiency in regular microbiological analysis further casts the possibility of disease onset. The need of microbial analyses of these foods also remains unclear to the consumers, which, in turn, results in microbial infections and intoxications remaining unnoticed.

The present review focused on the microbiological quality of the street foods projected from the locally conducted researches on street foods, and pondered on the possible management from a microbiological perspective for ensuring consumer safety.

This paper provides comprehensive information on the microbiological quality of street foods, requirement of maintenance of hygiene by the vendors and consumers and the necessity of adopting proper management during food preparation.

Demonstration of microbial prevalence in the street foods may bring imperative information on food safety and security. The conclusive message of this review is about the general consciousness on the microbiological aspects of street food contamination.