bluuebunny/crossref_metadata_2025_split huggingface dataset:
An efficient numerical tank for non‐linear water waves, based on the multi‐subdomain approach with BEM
Authors: Wang Pei , Yao Yitao , Tulin Marshall P. 
Published: August 2005

AbstractAn efficient 2D non‐linear numerical wave tank called LONGTANK has been developed based on a multi‐subdomain (MSD) approach combined with the conventional boundary element method (BEM). The multi‐subdomain approach aims at optimized matrix diagonalization, thus minimizing the computing time and reserved storage. The CPU per time step in LONGTANK simulation is found to increase only linearly with the number of surface nodes, which makes LONGTANK highly efficient especially when simulating long‐time wave evolutions in space.Appropriate treatment of special points on the boundary ensures high resolution in LONGTANK simulation beyond initial deformation and breaking, which allows detailed study of breaking criterion, breaker morphology, breaking dissipation, vorticity generation, etc.Detailed numerical implementation has been given with demonstration of LONGTANK simulations.
A Bayesian approach to determining connectivity of the human brain
Authors: Patel Rajan S. , Bowman F. DuBois , Rilling James K. 
Published: August 2005

AbstractRecent work regarding the analysis of brain imaging data has focused on examining functional and effective connectivity of the brain. We develop a novel descriptive and inferential method to analyze the connectivity of the human brain using functional MRI (fMRI). We assess the relationship between pairs of distinct brain regions by comparing expected joint and marginal probabilities of elevated activity of voxel pairs through a Bayesian paradigm, which allows for the incorporation of previously known anatomical and functional information. We define the relationship between two distinct brain regions by measures of functional connectivity and ascendancy. After assessing the relationship between all pairs of brain voxels, we are able to construct hierarchical functional networks from any given brain region and assess significant functional connectivity and ascendancy in these networks. We illustrate the use of our connectivity analysis using data from an fMRI study of social cooperation among women who played an iterated “Prisoner's Dilemma” game. Our analysis reveals a functional network that includes the amygdala, anterior insula cortex, and anterior cingulate cortex, and another network that includes the ventral striatum, orbitofrontal cortex, and anterior insula. Our method can be used to develop causal brain networks for use with structural equation modeling and dynamic causal models. Hum Brain Mapp, 2005. © 2005 Wiley‐Liss, Inc.
Hemispheric asymmetry of sulcus‐function correspondence: Quantization and developmental implications
Authors: Hasnain Mohammed K. , Fox Peter T. , Woldorff Marty G. 
Published: August 2005

AbstractSpatial covariances between the geometric centers of human occipital sulci and visual functional areas were calculated to reduce the spatial variance of functional‐area locations between subjects. Seven visual areas in each occipital hemisphere were retinotopically mapped, using horizontal‐ and vertical‐meridian stimuli and 15O PET in 11 subjects. Sulcal locations were determined using anatomic brain models derived from high‐resolution MRI images. Location variability for sulci and functional areas was similar in magnitude, with average standard deviations of (2.7x, 5.3y, 5.7z) mm and (4.3x, 5.4y, 5.3z) mm, respectively. Sulcal locations were predictive of functional‐area locations (i.e., significant spatial covariance) in the minority of structure‐function pairings tested (25 of 168). Location variability was reduced by an average of 27% for functional areas showing significant covariation with sulcal features. Early‐developing sulci were stronger predictors of functional‐area location than late‐developing sulci. Sulcus‐function covariance was stronger in the left occipital lobe than in the right occipital lobe. Notably, the left calcarine fissure demonstrated powerful covariances with functional areas in both hemispheres, suggesting that it serves as a developmental “anchor” for functional areas in the occipital cortex. These findings support the hypothesis that hemispheric lateralization of function is reflected in the strength of correspondence between cortical surface anatomy and function. Hum Brain Mapp, 2005. © 2005 Wiley‐Liss, Inc.
Rat bone marrow stromal cell osteogenic differentiation and fibronectin adsorption on chitosan membranes: The effect of the degree of acetylation
Authors: Amaral I. F. , Lamghari M. , Sousa S. R. , Sampaio P. , Barbosa M. A. 
Published: August 2005

AbstractCell adhesion, migration, and proliferation of a few anchorage‐dependent cells cultured on chitosan (Ch) matrices are influenced by the degree of N‐acetylation (DA) of Ch. In the present work, we examined the influence of the DA on the attachment, spreading, proliferation, and osteogenic differentiation of rat bone marrow stromal cells (rBMSCs). Ch membranes were characterized in terms of surface morphology, roughness, and wettability, and in terms of adsorption of an adhesive protein, fibronectin (Fn). Chs with DAs in the range of 4 to 49% were used. Among the Ch samples, the DA of 4% led to the highest Fn surface concentration, both from single protein solution and from diluted serum. Furthermore, the levels of Fn adsorbed from serum found for this DA were threefold higher than for the tissue culture polystyrene control, indicating that in the presence of competitive proteins Ch is more specific toward Fn adsorption than tissue culture polystyrene. rBMSCs cultured on Ch carrying a DA of 4% were able to spread, proliferate, and differentiate, reaching a higher level of osteogenic differentiation than on the control, despite the lower cell attachment observed for all Ch samples. Because the Ch sample with a DA of 4% showed the highest Fn adsorption from serum, we suggest that cell adhesion, spreading, and osteogenic differentiation of rBMSCs on Ch may be mediated by the adsorbed layer of Fn. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Steroid hormone receptor signaling in tumorigenesis
Authors: Singh Rajesh R. , Kumar Rakesh 
Published: August 2005

AbstractExcessive activation of the hormone signaling pathways is implicated in several disorders of the target tissues, with cancer being one of the most serious fallouts. Steroid hormone receptors are key proteins through which steroid hormones convey their signals to the cells. Deregulated activity of the hormone receptors due to their altered activation; stability or sub‐cellular localization is heavily implicated in the onset and progress of cancers. The role played by estrogen and its receptors in breast cancer remains the most thoroughly investigated steroid‐dependent cancer system till date. Choosing it as an example, we have summarized the molecular mechanisms underlying the action of the estrogen receptors (ERs) in manifesting the effects of the estrogens in the cells. A special emphasis is placed on the molecular mechanism of their functionality, role of the coactivator proteins, and the reasons for the deregulated signaling. The therapeutic approaches resulting from the mechanistic study of the ER action and their efficacies are also discussed. J. Cell. Biochem. 95: 490–505, 2005. © 2005 Wiley‐Liss, Inc.
Thermal modelling using ASTEC3 software
Authors: Poole N. J. , Sarvar F. , Witting P. A. , McKenzie W. H. 
Published: August 2005

AbstractThis paper describes the application of ASTEC3, a general purpose analogue electronic circuit simulation package, to the analysis of thermal properties of given structures. The modelling of each system is considered for both conduction and convection mechanisms, radiation being assumed to play a very minor role in heat dissipation from most electrical circuits. A procedure is given for the modelling of one‐, two‐ and three‐dimensional thermal problems which is then used for the simulation of relatively simple examples. The results obtained with ASTEC3 are compared with results determined by using more traditional and independent techniques.
A new time‐domain model for spontaneous emission in semiconductor lasers and its use in predicting their transient response
Authors: Lowery Arthur James 
Published: August 2005

AbstractSpontaneous emission noise power, although small in magnitude, affects many aspects of the semiconductor laser's operation. An accurate model has been developed for it for use in the transmission‐line laser model (TLLM), which is a time‐domain, wideband, dynamic, non‐adiabatic semiconductor laser model. The effects of approximations used in other dynamic laser models are then investigated by comparison with the results from the TLLM. The study shows that the representation of this noise power has an important bearing on the damping of modelled transient oscillations.
Radio frequency simulation of a complex printed circuit board layout by the quasi‐static boundary element method
Authors: Milsom R. F. , Scott K. J. 
Published: August 2005

AbstractA method for analysing the electrical effect of a set of conducting strips is presented. This method is applied to modelling the electrical behaviour of conducting tracks on a printed circuit board (PCB). Unlike most other published work, this analysis is not restricted to the case where the tracks are parallel. The problem is formulated in terms of an admittance matrix. A boundary element method incorporating image theory is used to produce a system of linear equations. These are solved to yield the required admittance matrix, which can then be incorporated into a standard circuit analysis package. Comparisons between measured and predicted circuit performance for a complex layout show close agreement up to at least 1 GHz.
A comparison of the dispersion characteristics associated with the TLM and FD‐TD methods
Authors: Choi Dennis H. 
Published: August 2005

AbstractThis paper presents the dispersion characteristics of the FD‐TD algorithm by showing the numerical phase and group velocities of the TEM, TE or TM modal solutions. For the TEM wave propagation, there exist three fundamental directions to which phase and group velocities can be expressed by only a single variable (wave numberkor frequency ω). Those special directions were chosen to show the dispersive nature of the FD‐TD algorithm of which the group and phase velocities depend explicitly on frequencies.In view of similarities between the TLM and FD‐TD algorithms, a comparison of phase velocity characteristics of both methods was made. Under the special condition where the stability factorsis larger than 1/2, the FD‐TD algorithm is found less dispersive than that of the original TLM. However, newly developed symmetrical TLM method appears less dispersive than the FD‐TD algorithm.In the numerical simulation of waveguide modal solutions, it was found that there exists an optimum frequency which provide least numerical error in the FD‐TD application. A procedure, which determines the stability factorsand the maximum allowed frequencyFmaxfor the best numerical results, is proposed in this paper.
Coupling between electromagnetic fields and multimode transmission systems using TLM
Authors: Naylor P. , Christopoulos C. 
Published: August 2005

AbstractThe coupling between incident electromagnetic fields and lossless, multimode, multiconductor, transmission systems is studied using transmission‐line modelling (TLM). Model predictions compared well with experimental multimode results. The model presented is suitable for studying electromagnetic compatibility problems in the time‐domain.
Concurrent processing: The key to rapid probabilistic potential methods
Authors: Fusco V. F. 
Published: August 2005

AbstractThis paper shows how probabilistic potential methods based on the Monte Carlo approach can be efficiently mapped onto an array of concurrent processors and how the resulting algorithm can provide rapid solutions of harmonic function problems. The method described here exploits the natural concurrency of the Monte Carlo approach. Computation is achieved by use of a low‐cost array of transputers linked to a PC‐AT. The resulting methodology is powerful and the ideas suggested should have application to many other modelling techniques used for field modelling.A microstrip geometry is used as the discussion vehicle throughout this paper. This geometry was selected since it exhibits a number of the important topological features required in a general problem, e.g. Dirichlet boundary conditions and mixed dielectric. The design of the parallel algorithm used is discussed in detail, and typical results are given.
A computer program for waveguide analysis using high‐order, vector, finite elements
Authors: Webb J. P. , Forghani B. 
Published: August 2005

AbstractA computer program has been written for the analysis and design of arbitrarily shaped waveguides, containing dielectric and magnetic materials. The program calculates the propagating modes of the waveguide by the three‐component vector finite element method. High accuracy is achieved by the use of high‐order elements, and by the inclusion of singular trial functions near sharp metal edges. An efficient algorithm based on the conjugate gradient method is used to solve the algebraic eigenvalue problem. Results are given for rib waveguide and fin‐line.
Combined fine–coarse mesh transmission‐line modelling method for diffusion problems
Authors: Ait‐Sadi R. , Lowery A. J. , Tuck B. 
Published: August 2005

AbstractThe paper presents a combined fine–coarse mesh TLM method. This technique reduces the memory storage and the computational time when modelling complex structures. In the combined fine–coarse mesh model, the region of interest is covered with a set of transmission‐line fine meshes. The remaining part is covered with regular (or irregular) coarse meshes. The fine‐mesh nodes are connected through busbars to the adjacent coarse‐mesh nodes. The combined fine–coarse mesh TLM technique is applied to some diffusion problems. Significant savings in computational time and memory storage are obtained without loss of accuracy.
Substructuring of space and time in TLM diffusion applications
Authors: Pulko S. H. , Halleron I. A. , Phizacklea C. P. 
Published: August 2005

AbstractA simple method is described for spatial substructuring of meshes used in TLM diffusion routines in such a way as to enable discontinuous mesh lines to be used. A method of operating TLM diffusion routines using different timesteps in different spatial regions is also described. For both aspects, results are compared with those derived using standard TLM techniques.
Electromagnetic scattering from conductor‐coated material bodies
Authors: Analoui Morteza , Kagawa Yukio 
Published: August 2005

AbstractA moment method solution is presented to compute electromagnetic scattering from material bodies. The bodies are supposed to be homogeneous, arbitrarily shaped and lossy; they can be coated with very thin perfect conductors in some parts. A formulation of the scattering problem is made in terms of the equivalent surface current densities for which mixed potentials are used. The equivalent currents are expanded in the space‐domain by a triangular expansion function on the triangulated surfaces of the scatterer. The Galerkin procedure is carried out to test boundary integral equations and reduce the functional form of the equations to a partitioned matrix equation. The solution is applied to the scattering problem of a dielectric slab, a thin conductor coated by absorber material and a rectangular patch on a grounded dielectric slab. The computed backscattering radar cross‐section and surface current densities of the structures are presented and some of the results are compared with experimental data.
Large signal periodic time‐domain simulation
Authors: Whight K. R. , Gough P. A. , Walker P. 
Published: August 2005

AbstractA novel algorithm has been implemented within our new semiconductor device simulation program TESSA that allows large signal periodic time‐domain simulation to be performed by integrating over just one period of the excitation. Conventionally the need to integrate out initial transients, over many cycles, had effectively made such simulations impracticable. The algorithm can also be implemented in the field of circuit simulation so a combined large signal circuit/device simulation package is now a practical possibility.
Application of an efficient algorithm for solving the one‐band effective mass equation self‐consistently in the modelling of some low‐dimensional structure devices
Authors: Wilson Stephen P. , Allsopp Duncan W. E. , Morton Christopher G. 
Published: August 2005

AbstractAn efficient algorithm is presented for the self‐consistent numerical solution of the single‐band effective mass equation. This algorithm has a different form depending on whether the effective mass is modelled as continuous or piecewise continuous. Coupled with a Poisson solver, an established algorithm is applied for the attainment of self‐consistency. The rate of convergence to a self‐consistent solution is investigated, and the solvers are applied to three different structures to demonstrate its versatility and robustness. The first of these is a nominally undoped quantum well AlGaAs/GaAs heterostructure, the second a doubly δ‐doped GaAs homostructure and lastly a quasi‐square well modulation‐doped field effect transistor. The algorithm is of sufficient efficiency so as to allow the software to run reasonably quickly on a modern microcomputer.
Time‐domain numerical modelling of microwave non‐linear circuits
Authors: Dalle C. , Rolland P. A. , Friscourt M. R. 
Published: August 2005

AbstractA numerical time‐domain modelling of non‐linear microwave circuits is presented. It is based on a numerical procedure allowing the solution of the integro‐differential equation driving the instantaneous electrical behaviour of a lumped‐element circuit while accounting for the semiconductor device by means of an accurate numerical macroscopic model. This modelling is firstly validated by studying the DC turn‐on and DC forward–reverse commutation of a PIN diode. The diode voltage and current waveform are qualitatively consistent with experimental ones, Moreover, the predicted recovery time values are found to be in good agreement with those issued from the classical analytical theory. Secondly, in order to illustrate the present capabilities of the model, the whole transient response of a back‐to‐back silicon PIN diode passive power limiter to a high‐input‐RF‐power pulse is described. It is demonstrated that in the present case of a 2 μm‐long PIN diode, the high‐input‐power steady‐state operation only relies on one diode. To our knowledge, it is the first time this kind of simulation is applied to a two‐diode circuit.
Transient response of lossy transmission lines with arbitrary loads
Authors: Wong Chi‐Chung , Chan Yick‐Fung 
Published: August 2005

AbstractIn this paper, the method of transmission‐line modelling is used to determine the transient response of a lossy transmission line. Non‐linearity and frequency‐dependent parameters (R and G) can be included without undue difficulty. Several numerical examples are described and are compared with exact and/or experimental results. In all cases good agreements are obtained.
Parallel implementation of cellular systems for numerical modelling
Authors: Thiele L. 
Published: August 2005

AbstractThere is an increasing interest in the numerical modelling of physical and biological processes using cellular automata or cellular systems. One of the main advantages in using the concept of cellular systems is the inherent high degree of parallelism. The purpose of the contribution is to formally relate two different areas: time‐domain modelling of physical processes using cellular systems and massive parallel implementations. At first, an overview of applications of cellular systems in computation theory and in modelling of physical systems and an overview of implementations of cellular systems is given. The subsequent sections address the following two questions: (1) Which class of algorithms can be interpreted as cellular systems. (2) Can cellular systems be efficiently simulated on a given parallel architecture. Results concerning these issues are presented.
Concurrent boundary element computation
Authors: McDowall D. S. , Lee T. W. , Fusco V. F. 
Published: August 2005

AbstractA major limitation of the boundary element method (BEM) for the solution of electrical potential problems is the long computational time required. However, a large portion of the calculations involved can be viewed as being parallel in nature and can therefore be computed concurrently. This paper makes an effort to increase the efficiency of the BEM process using transputer‐based multiprocessor computing techniques. The algorithms developed may equally well be applied to any multiprocessor system. The application selected to demonstrate the technique is the solution of an electrostatic problem governed by a two‐dimensional Laplace equation.A parallel algorithm for problem setup and field extraction using BEM is designed and implemented on a transputer array. Special attention is directed to the utilization of the parallel processors to achieve maximum efficiency. The analysis in this work concentrates on the communication strategies for passing data between processors as well as a consideration of the workload attributed to each processor.The parallel algorithms were implemented using 3L Parallel Fortran; however, the choice of topology for the overall BEM implementation was limited by the fact that certain parts of the algorithm could only utilize a pipeline configuration of processors. Comprehensive results for the parallel BEM algorithm are given and they are encouraging, indicating that parallel processing has much to offer when applied to the boundary element method.
The efficiency of transmission‐line matrix modelling—a rigorous viewpoint
Authors: Enders Peter , De Cogan Donard 
Published: August 2005

AbstractThe difference equations of the scalar linear transmission‐line matrix (TLM) routine as introduced by Johns for numerically solving the diffusion equation are shown to be isomorphic to Goldstein's correlated random walk model of diffusion. For the infinite homogeneous bar their exact solution is derived algebraically and given in the form of Jacobi polynomials. This puts the TLM algorithm on a sounder mathematical and physical basis. The accuracy in solving the diffusion equation is investigated in general form and thus its astonishing efficiency explained. Several other basic questions of this numerical technique are also discussed.
Redundancy and its implications in TLM diffusion models
Authors: Pulko S. H. , Wilkinson A. J. , Gallagher M. 
Published: August 2005

AbstractRedundancy in the simplest form of a two‐dimensional TLM network is identified and a method of eliminating it is described. Results obtained using the non‐redundant algorithm are compared with those derived from the standard, redundant algorithm. The non‐redundant approach is extended to deal with non‐uniform elemental capacitance; a cylindrical geometry is taken as an example of this. The scope for and benefits of rendering TLM diffusion models non‐redundant are discussed.