bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frequency‐domain analysis of time‐integration methods for semidiscrete finite element equations—part II: Hyperbolic and parabolic–hyperbolic problems
Authors: Muğan Ata , Hulbert Gregory M. 
Published: August 2002

AbstractTime‐integration methods for semidiscrete finite element equations of hyperbolic and parabolic– hyperbolic types are analysed in the frequency domain. The discrete‐time transfer functions of six popular methods are derived, and subsequently the forced response characteristics of single modes are studied in the frequency domain. Three characteristic numbers are derived which eliminate the parameter dependence of the frequency responses. Frequency responses and L2‐norms of the phase and magnitude errors are calculated, and comparisons are given of the methods. As shown; the frequency‐domain analysis explains all time‐domain properties of the methods, and gives more insight into the subject. Copyright © 2001 John Wiley & Sons, Ltd.
Application of upper bound method to the powder‐forging of cup‐shaped axisymmetric preforms for estimating punch load
Authors: Cho J. R. , Jeong H. S. 
Published: August 2002

AbstractThis paper is concerned with the analytic derivation of the punch load required to forge cup‐shaped axisymmetric porous preforms. Splitting the two‐dimensional preform domain into three rectangular regions, we assumed the kinematically admissible velocity fields to apply the upper bound method. According to the resulting formulas, we developed an incremental numerical algorithm for computing time‐discretized step‐wise punch loads and preform volumes. In order to illustrate the validity of the proposed estimate, we compared the numerical results obtained by the present analysis with those by the finite element simulation. From the comparison made through different preform dimensions, we observed that the present analysis expects the reliable upper bounds of process step‐wise punch loads. Copyright © 2001 John Wiley & Sons, Ltd.
A variance propagation algorithm for stochastic heat and mass transfer problems in food processes
Authors: Scheerlinck Nico , Verboven Pieter , Stigter Johannes D. , De Baerdemaeker Josse , Van Impe Jan F. , Nicolai Bart M. 
Published: August 2002

AbstractA variance propagation algorithm for stochastic coupled heat and mass transfer problems subjected to first order autoregressive random process boundary conditions was developed. The algorithm is based on the finite element formulation of Luikov's coupled heat and mass transfer equations and involves the numerical solution of coupled Lyapunov and Sylvester matrix differential equations. It offers a cheap alternative to the Monte Carlo method for the computation of the mean value and variance of the temperature and moisture content field. The algorithm is generally applicable and can easily be inserted in any existing finite element code. Also, it can be extended to other types of random processes. The algorithm was applied to analyse the drying of a soybean kernel. Simulation results show that random fluctuations of the process conditions may cause considerable variability of the temperature and the moisture content within the drying soybean kernel. This is an important feature to take into account for the design of a drying process, and for thermal food processes in general. Copyright © 2001 John Wiley & Sons, Ltd.
Iterative solution of large‐scale acoustic scattering problems with multiple right hand‐sides by a domain decomposition method with Lagrange multipliers
Authors: Tezaur Radek , Macedo Antonini , Farhat Charbel 
Published: August 2002

AbstractAn extension of the FETI‐H method is designed for the solution of acoustic scattering problems with multiple right‐hand sides. A new local pre‐conditioning of this domain decomposition method is also presented. The potential of the resulting iterative solver is demonstrated by numerical experiments for two‐dimensional problems with high wavenumbers, as many as 2.5 million complex degrees of freedom, and a sweep on the angle of the incident wave. Preliminary results for a three‐dimensional submarine problem are also included. The FETI‐H method, whose numerical scalability with respect to the mesh and subdomain sizes was previously established, is shown here to be also numerically scalable with respect to the wavenumber. Copyright © 2001 John Wiley & Sons, Ltd.
An improved weighting method with multibounds formulation and convex programming for multicriteria structural optimization
Authors: Zhang W. H. , Domaszewski M. , Fleury C. 
Published: August 2002

AbstractThis paper presents an improved weighting method for multicriteria structural optimization. By introducing artificial design variables, here called as multibounds formulation (MBF), we demonstrate mathematically that the weighting combination of criteria can be transformed into a simplified problem with a linear objective function. This is a unified formulation for one criterion and multicriteria problems. Due to the uncoupling of involved criteria after the transformation, the extension and the adaptation of monotonic approximation‐based convex programming methods such as the convex linearization (CONLIN) or the method of moving asymptotes (MMA) are made possible to solve multicriteria problems as efficiently as for one criterion problems. In this work, a multicriteria optimization tool is developed by integrating the multibounds formulation with the CONLIN optimizer and the ABAQUS finite element analysis system. Some numerical examples are taken into account to show the efficiency of this approach. Copyright © 2001 John Wiley & Sons, Ltd.
A large‐strain elasto–plastic shell formulation using the Morley triangle
Authors: Kolahi A. S. , Crisfield M. A. 
Published: August 2002

AbstractThe paper describes a large‐strain elasto–plastic formulation for shells, which is based on the faceted ‘Morley triangle’, with rotation variables only being provided at each mid‐side in the form of a rotation about the side.A co‐rotational formulation is adopted, with the local deformation gradient being obtained from a polar decomposition using F=RU. The material description is then based around ‘logeU’, with U being decomposed into principal directions. Plasticity is treated with the aid of the multiplicative F=FeFp. In contrast to many earlier formulations with the Morley triangle, the current formulation is invariant to the node numbering. In order to achieve this invariance, it is necessary to re‐visit the origins of the Morley triangle and to re‐cast the formulation as a special form of ‘discrete‐Kirchhoff approach’. The associated constraint is now applied in relation to the ‘current configuration’. Copyright © 2001 John Wiley & Sons, Ltd.
An efficient parallel procedure for the simulation of crack growth using the cohesive surface methodology
Authors: Lingen F. J. , Tijssens M. G. A. 
Published: August 2002

AbstractSimulations of crack growth that are based on the cohesive surface methodology typically involve ill‐conditioned systems of equations and require much processing time. This paper shows how these systems of equations can be solved efficiently by adopting the domain decomposition approach in which the finite element mesh is partitioned into multiple blocks. The system of equations is then reduced to a much smaller system of equations that is solved with an iterative algorithm in combination with a powerful two‐level preconditioner. Although the solution algorithm is more efficient than a direct solution algorithm on a single‐processor computer, it becomes really attractive when used on a parallel computer. This is demonstrated for a large scale simulation of crack growth in a polymer using a Cray T3E with 64 processors. Copyright © 2001 John Wiley & Sons, Ltd.
Fully stressed frame structures unobtainable by conventional design methodology
Authors: Mueller Keith M. , Burns Scott A. 
Published: August 2002

AbstractA structure is said to be fully stressed if every member of the structure is stressed to its maximum allowable limit for at least one of the loading conditions. Fully stressed design is most commonly used for small and medium size frames where drift is not a primary concern. There are several potential methods available to the engineer to proportion a fully stressed frame structure. The most commonly used methods are those taught to all structural engineering students and are very easy to understand and to implement. These conventional methods are based on the intuitive idea that if a member is overstressed, it should be made larger. If a member is understressed, it can be made smaller, saving valuable material.It has been found that a large number of distinct fully stressed designs can exist for a single frame structure subjected to multiple loading conditions. This study will demonstrate that conventional methods are unable to converge to many, if not most, of these designs. These unobtainable designs are referred to as ‘repellers’ under the action of conventional methods. Other, more complicated methods can be used to locate these repelling fully stressed designs. For example, Newton's method can be used to solve a non‐linear system of equations that defines the fully stressed state. However, Newton's method can be plagued by divergence and also by convergence to physically meaningless solutions. This study will propose a new fully stressed design technique that does not have these problems. Copyright © 2001 John Wiley & Sons, Ltd.
Higher‐order boundary element methods for transient diffusion problems. Part I: Bounded flux formulation
Authors: Grigoriev M. M. , Dargush G. F. 
Published: August 2002

AbstractDespite the significant number of publications on boundary element methods (BEM) for time‐dependent problems of heat diffusion, there still remain issues that need to be addressed, most importantly accuracy of the numerical modelling. Although very precise for steady‐state problems, the common boundary element methods applied to transient problems do not yield highly accurate numerical solutions. This paper investigates the reasons that prohibit achievement of a high level of accuracy for transient heat diffusion problems with continuous temperature and bounded heat flux solutions. In order to greatly enhance the commonly used boundary element formulations, we propose higher‐order time interpolation functions, including quadratic and quartic approximations. We show that the use of higher‐order time functions greatly reduces the numerical error concentrated in the corner regions, and results in very good uniformity of the flux and temperature distributions along the boundaries for problems where uniform distributions are expected.In order to highlight the importance of proper resolution both in time and space for the transient problems, we consider one‐ and two‐dimensional formulations in this paper. High‐order boundary elements using quartic shape functions, as well as high‐order bi‐quartic volume cells, are used to attain mesh‐independent numerical solutions. We consider four transient heat diffusion problems that possess exact solutions to investigate the convergence rate and accuracy of the higher‐order boundary element formulations. A very high level of accuracy is possible for both one‐ and two‐dimensional formulations. Additionally, we show that the accuracy of a commercially available finite‐element code is far less than that of the boundary element methods for a given spatial and temporal discretization. Copyright © 2002 John Wiley & Sons, Ltd.
A parallel computational method in steady power‐law creep
Authors: Klebanov I. M. , Davydov A. N. 
Published: August 2002

AbstractA new approach to parallelization of materially non‐linear problems in solid mechanics is developed. It is based on approximating generalized models of subdomains. The procedure does not retain the same substructuring technique used in a linear version. The convergence proof of the single‐ and multilevel‐domain decomposition algorithms uses the principle of minimum potential energy dissipation and investigated properties of the substructural models. The high efficiency of the approach introduced is shown through the study of several examples. The method developed in this paper for steady creep can be used without modification to solve non‐linear elasticity problems and, at active loading, plasticity problems for bodies of the power‐law strain–stress diagrams. Copyright © 2001 John Wiley & Sons, Ltd.
A generalized recursive formulation for constrained flexible multibody dynamics
Authors: Bae D. S. , Han J. M. , Choi J. H. , Yang S. M. 
Published: August 2002

AbstractThis research develops a relative co‐ordinate formulation for the multibody flexible dynamics. The velocity transformation method is notationally compact, because the Cartesian generalized velocities are simultaneously transformed to the relative generalized velocities in a matrix form. However, inherent computational efficiency in the recursive kinematics between two adjacent bodies has not been exploited. This research presents a recursive formulation which is both notationally compact and computationally efficient. The velocity transformation method is used to derive the equations of motion and their derivatives. Matrix operations associated with the velocity transformation matrix in the resulting equations of motion and their derivatives are classified into several categories. A joint library of the generalized recursive formulas is developed for each category. When one category is encountered in implementing the equations of motion and their derivatives, the corresponding recursive formulas in the category are invoked. When a new force or joint module is added to a general purpose programme in the relative co‐ordinate formulation, the modules for the rigid body are not reusable for the flexible body. Since the flexible body dynamics handles additional generalized co‐ordinates associated with deformation, implementation of the flexible dynamics is generally complicated and prone to coding mistakes. A virtual rigid body is introduced at every joint and force reference frames. A virtual flexible body joint is introduced between two body reference frames of the virtual and original bodies. This makes a flexible body subjected to only the kinematic admissibility condition for the virtual flexible body joint. As a result, the only extra work to handle the flexible bodies is to add the virtual flexible body joint modules in all recursive formulas. Since computation time in a relative co‐ordinate formulation is approximately proportional to the number of relative co‐ordinates, computational overhead due to the additional virtual bodies and joints are minor. Meanwhile, implementation convenience is dramatically improved. Copyright © 2001 John Wiley & Sons, Ltd.
Rapid Skill Obsolescence in an IT Company: A Case Study of Acxiom Corporation
Authors: Standridge Jeff , Autrey Ramona 
Published: August 2002

AbstractAlthough most employees in this fast‐changing business world need to keep their skills up‐to‐date, nowhere is this requirement as essential as among information technology workers. At Acxiom Corporations, an IT company, this need was pressing. And the firm found that reliance on the classic KSA—knowledge, skills, and abilities—measures was not meeting the need. Instead, it took a broader look at corporate goals and how its people could meet them—and has linked targeted behaviors to the achievement of those goals, making them the basis for career development, performance, evaluation, and compensation. © 2001 by John Wiley & Sons, Inc.
Strategic adaptation to change: A practical system for achieving breakthrough performance
Authors: Stein Martin M. 
Published: August 2002

AbstractOne of the best ways to understand the value of and need for organizational learning is to begin by setting a
goal. Then examine the organizational barriers to achieving it—and design the policies, programs, and
practices that will overcome them. This process, properly sustained, can continuously upgrade an
organization's core competencies and intellectual capital. People get energized, knowledge gets communicated
and applied, and change becomes a challenge rather than a threat. © 2002 Wiley Periodicals,
Inc.
A wake‐up call for not only terrorist threats
Authors: Viollis Paul 
Published: August 2002

AbstractThe terrorist attacks of September 11 underscore the omnipresent threats posed to employers. In addition to
those to our personal and national security from terrorists, incidents of workplace violence have increased more
than 750 percent in the last three years. The onus is on each organizational leader and business professional to
closely scrutinize this epidemic of violence, uncover the common denominators, and expeditiously formulate
solutions before tragedy strikes. We must embrace a new corporate environment free of the full range of recognized
hazards. © 2002 Wiley Periodicals, Inc.
Obstacles—and Overcoming Them—to Leadership Among Professional Workers
Authors: Fisher Jr. James R. 
Published: August 2002

AbstractIt's not news that, over the past few decades, the heart of the U.S. workforce has traded blue collars for white. Management, the author argues, has not changed commensurately. He outlines the need for leadership to replace traditional top‐down management, identifies obstacles to leadership by professional workers and discusses how those obstacles can, and must, be overcome. © 2001 John Wiley & Sons, Inc.
What Companies Do Beyond the Basics To Retain Scarce Talent
Authors: Herman Roger E. , Gioia‐Herman Joyce L. 
Published: August 2002

AbstractMost companies are suffering from staffing difficulties, increasing the importance of employee retention. Creative approaches are giving many employers a competitive edge in the war for talent. Examples of the strategies of enlightened employers offer models to follow and may stimulate some refreshing ideas. © 2001 John Wiley & Sons, Inc.
Blocking of carbachol‐induced calcium mobilization by glutamate receptor antagonists
Authors: Naarala Jonne , Tervo Pirkko , Loikkanen Jarkko , Savolainen Kai 
Published: August 2002

AbstractThe aim of this study was to explore whether glutamatergic‐ and muscarinic cholinergic receptor systems have interactions in controlling intracellular calcium concentrations. We report here that cholinergic receptor‐stimulated elevations of intracellular calcium can be blocked dose‐dependently by N‐methyl‐D‐aspartate (NMDA) and metabotropic glutamate receptor antagonists, but not by an AMPA/kainate antagonist, in human SH‐SY5Y neuroblastoma cells. It seems likely that cholinergic and glutamatergic receptor classes may be under partial control of each other. There are number of in vivo observations to suggest that, in addition to cholinergic system, also other neurotransmitter systems are involved in cholinergic neuronal excitation and subsequent convulsions. The SH‐SY5Y cell line may prove to be a useful in vitro model to study cholinergic and glutamatergic interactions.
The spatial pattern of the vacuolation (‘spongiform change’) in the cerebral cortex in variant Creutzfeldt‐Jakob disease (vCJD)
Authors: Armstrong R. A. , Cairns N. J. , Ironside J. W. , Lantos P. L. 
Published: August 2002

AbstractThe spatial pattern of the vacuolation (‘spongiform change’) was studied in areas of the cerebral cortex in 11 cases of variant Creutzfeldt‐Jakob disease (vCJD). The vacuoles were evenly distributed along the cortex in 40/106 (38%) areas studied and randomly distributed in 6/106 (5.6%) areas. In 22/106 (21%) areas, the vacuoles were aggregated into clusters, 50–1600 μm in diameter and which were distributed in a regular pattern parallel to the pia mater. In 38/106 (36%) areas, large clusters of vacuoles, at least 1600 μm in diameter, were present. No significant differences in spatial patterns were observed between the different cortical regions or between the upper and lower laminae. In addition, age at onset and duration of the disease had no significant affect on spatial patterns. The spatial distribution of the vacuolation contrasts with that reported in sporadic CJD (sCJD) suggesting a different pattern of cortical degeneration in vCJD.
Tetraethylammonium‐induced changes in intracellular calcium in Alzheimer donor fibroblasts
Authors: Brzyska Maria , Michalski Andrzej , Elbaum Danek 
Published: August 2002

AbstractIn this paper we analyzed the operation of K+ channels by measuring the extracellular calcium influx in response to tetraethylammonium (TEA) depolarization. We compared TEA‐induced intracellular calcium changes in fibroblasts obtained from Alzheimer Disease (AD) patients, aged (AC) and young (YC) healthy subjects. Subsequently we analyzed the effects of incubation of these fibroblasts with beta‐amyloid on calcium responses. Our results indicated that depolarization with TEA did not abolish calcium responses in any of the tested cell groups. TEA‐elicited calcium changes in AD cells were significantly greater than those observed in AC or YC cells. Responses were delayed in AD fibroblasts with respect to AC or YC cells. Incubation with beta‐amyloid did not alter the other effects: response amplitude in AD cells was still greater than in AC or YC cells; AD responses were still delayed with respect to AC and YC responses. These results support the earlier findings that calcium responses were altered in AD cells but suggest their delay rather than inhibition.
Sulfatide does not induce apoptosis in arylsulfatase A‐deficient cells
Authors: Habetha Matthias 
Published: August 2002

AbstractDeficiency of arylsulfatase A (ASA) causes metachromatic leukodystrophy (MLD). Patients suffering from this inherited disease show reduced or complete loss of ability to degrade sulfatide. Sulfatide is an abundant lipid of mammalian cellular membrances and preferentially localised in brain tissue. Neurological symptoms of MLD‐patients, therefore, may be caused by increased amoounts of cellular sulfatide. In the present study I have tested this idea by treating various cell lines with sulfatide and examining the rate of apoptosis. Four mammalian cell lines including the mouse glial cell lines 11+/+C1 and ASA‐deficient 17–/–A1 have been used. I show that exogenously applied sulfatide was incorporated and intracellularly stored in these cells. Incorporation of sulfatide was at a lower level in the presence of recombinant ASA. FACS analysis of propidiumiodide stained cells revealed that treatment of cells with sulfatide had no effect on apoptosis.
Tonotopic mapping of c‐fos expression in the dorsal cochlear nucleus of the hamster
Authors: Bahu Samer J. , Kaltenbach James A. , Zhang Jinsheng , Khariwala Samir S. , Afman Chad E. , Hnatiuk Mark 
Published: August 2002

AbstractWe used the hamster as a model for identifying frequency specific loci in the dorsal cochlear nucleus (DCN) using c‐fos immunocytochemistry. Animals were divided into three groups. The animals in the first group were stimulated with tone bursts at a frequency of 5kHz, those in the second group at 10kHz, and those in the third at 17kHz. The bursts were 50 msecs in duration and were presented for 1 hour at 67 dB SPL (4/sec). Brain tissue was obtained and procedures for c‐fos assay were performed. Following stimulation distinct clusters of immunolabeled nuclei were found within the DCN. Cluster locations varied as a function of frequency. For the 5 kHz stimulus group, clusters were found at a mean position of 33% of the distance from the lateral to the medial extremities of the DCN. For exposures of 10 kHz, the bands were positioned approximately 50% of this distance, and for 17 kHz at approximately 67% of the lateral to medial distance. These results are consistent with the pattern of tonotopic organization which has been demonstrated in the DCN using electrophysiological procedures.