bluuebunny/crossref_metadata_2025_split huggingface dataset:
Global existence in rate‐independent infinitesimal strain gradient plasticity
Authors: Neff Patrizio 
Published: December 2008

AbstractWe propose a model of infinitesimal strain gradient plasticity including phenomenological Prager type linear kinematical hardening and nonlocal kinematical hardening due to dislocation interaction. The model is a thermodynamically admissible model of infinitesimal plasticity involving only the Curl of the non‐symmetric plastic distortion p. Linearized spatial and material covariance under constant infinitesimal rotations is satisfied. Uniqueness of strong solutions of the infinitesimal model is obtained if two non‐classical boundary conditions on the plastic distortion p are introduced: ṗ.τ = 0 on the microscopically hard boundary ΓD ⊂ ∂Ω and [Curl p ].τ = 0 on the microscopically free boundary ∂Ω\ΓD, where τ are the tangential vectors at the boundary ∂Ω. Moreover, a weak reformulation of the infinitesimal model allows for a global in‐time solution of the corresponding rate‐independent initial boundary value problem. The method of choice are a formulation as a quasi‐variational inequality with symmetric and coercive bilinear form. Use is made of new Hilbert‐space suitable for dislocation density dependent plasticity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of vehicular traffic system
Authors: Nugrahani E. H. 
Published: December 2008

AbstractThe behavior of traffic systems controlled by traffic lights on a single lane is presented using the optimal velocity model. The effect of different traffic light control strategies on the traffic flow is discussed using three different strategies, i.e. the synchronized, green wave, and random offset. Some simulation results on the model using cellular automata are presented. The flow‐density diagrams are analyzed using these strategies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An overview of fast component‐by‐component constructions of lattice rules and lattice sequences
Authors: Nuyens Dirk , Cools Ronald 
Published: December 2008

AbstractSince the initial work by I. H. Sloan and his collaborators on the component‐by‐component construction of good lattice rules for the approximation of multivariate integrals, a lot of variations on this theme have been published. These include various function spaces, prime and composite number of points, intermediate‐rank rules, polynomial lattice rules and extensible rules. We sketch the different variations and discuss the properties needed to have a fast component‐by‐component construction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Existence and uniqueness of level sets for spiral crystal growth
Authors: Ohtsuka Takeshi 
Published: December 2008

AbstractWe outline a new level set approach for spirals whose evolution follows the generalized curvature flow with a constant driving force. Our basic idea is that a spiral can be expressed as the intersection of an auxiliary surface and a Riemannian surface. Also we state and discuss the basic ideas for the uniqueness and existence of spiral motion using the level set approach. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of magnetic fields on crystal growth
Authors: Kao A. , Djambazov G. , Pericleous K. , Voller V. 
Published: December 2008

AbstractThe effects of a constant uniform magnetic field on thermoelectric currents during dendritic solifification were investigated using an enthalpy based numerical model. It was found that the resulting Lorentz force generates a complex flow influencing the solidification pattern. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large‐scale high‐fidelity atomistic simulations for emerging materials and electronics devices
Authors: Polizzi E. 
Published: December 2008

AbstractThe quest for ever higher levels of detail and realism in nanoelectronics simulations presents formidable modeling and computational challenges. These simulations are expected, however, to benefit from the development of specific advanced mathematical techniques and high‐performance parallel algorithms to achieve high‐fidelity simulations of materials and transport problems. Here, we propose to investigate novel simulation strategies which aim to go beyond qualitative predictions by proposing quantitative simulations from the atomistic scale to the transistor macroscale. Results obtained on carbon nanotubes to compute the electron density using these advanced techniques and first‐principle calculations, are presented here. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The differentiation‐enabled NAGWare Fortran compiler
Authors: Riehme Jan , Naumann Uwe , Christianson Bruce 
Published: December 2008

AbstractWe present a research prototype of the differentiation‐enabled NAGWare Fortran compiler. The compiler provides built‐in automatic differentiation capabilities for the generation of code for computing first and second derivatives of numerical simulation codes written in Fortran. Tangent‐linear, adjoint, and second‐order adjoint code is obtained by a semantic transformation of the compiler's intermediate representation. Three successful reference applications are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale methods for the wave equation
Authors: Engquist Bjorn , Holst Henrik , Runborg Olof 
Published: December 2008

AbstractWe consider the wave equation in a medium with a rapidly varying speed of propagation. We construct a multiscale scheme based on the heterogeneous multiscale method, which can compute the correct coarse behavior of wave pulses traveling in the medium, at a computational cost essentially independent of the size of the small scale variations. This is verified by theoretical results and numerical examples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastic‐plastic sandwich beams with optimized properties for the impact case
Authors: Schmidt Jürgen , Winter Werner , Kuhn Günther 
Published: December 2008

AbstractAn approach for the design of lightweight sandwich beams with optimal performance under low velocity impact loading is presented. Exemplary for beams with stainless steel faces and aluminium foam cores a procedure is proposed that bases on simulation results using an explicit finite element code. Experimental tests assure the accuracy of numerical analyses and provide data to fit the applied plastic compressible material model. By means of a multicriteria optimization method failure mechanisms are identified which dissipate a maximum of energy and lead to minimal deflections as well as to minimal beam thickness and weight at the same time. Face and core thicknesses are used as design variables. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the influence of the kink's asymptotic field on crack propagation
Authors: Schütte H. , Molla‐Abbasi K. 
Published: December 2008

AbstractThe aim of the presentation is to highlight the influence of the kink, developing at the beginning of mixed‐mode crack growth, on the propagation behavior of the crack. Le et al. (1999) have shown that the variational principle of a body containing a crack results in the principle of maximum energy release rate incorporating the stress intensity factors of the kinked crack. In the present paper, the influence of the kink and the kinking angle, resulting in a singular field around the corner, on the crack growth is analyzed. The generalized stress intensity factors at the kink's corner are computed with the help of a FEM strategy. The influence of these on the T‐stresses and the combined plastic zone is presented (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Undergraduate computational science and engineering education: Undergraduate internships section of a SIAM working group report
Authors: Shiflet Angela B. 
Published: December 2008

AbstractThe SIAM Working Group on Undergraduate Computational Science and Engineering (CSE) Education, chaired by Peter Turner (Clarkson University), wrote a report on the topic, which states that a “common feature among CSE programs is the requirement for an internship in the form of an undergraduate research experience” [1][2]. The report and this article elaborate on the value of such experiences and how students, often with the help of faculty members, can obtain internships. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Generalized solutions of integral‐functional equations: construction and applications in power industry
Authors: Sidorov Nikolay A. , Sidorov Denis N. , Trufanov Andrey V. 
Published: December 2008

AbstractDeterministic approaches to the Volterra models learning is considered. First approach is based on kernels identification procedure and the second one employs product indegration method. Generalized solutions of linear and nonlinear integral Volterra equations are also addressed covering the discontinuous solutions cases. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multipoint nonlocal boundary value problem for Schrödinger equations
Authors: Ashyralyev Allaberen , Sirma Ali 
Published: December 2008

AbstractThe multipoint nonlocal boundary value problem for Schrödinger equations in a Hilbert space are investigated. Stability estimates for the solution of this problem are established. The first and second order accuracy difference schemes for the approximate solution of this multipoint nonlocal boundary value problem are presented. The stability of these difference schemes is established. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Starting with the right matrices
Authors: Strang Gilbert 
Published: December 2008

AbstractOver the past 20 years we have developed a course that combines applied mathematics with scientific computing. Each lecture discusses a model problem and a code to solve it. The course is popular with engineering students and their departments, who want exposure to ideas and also to software (including MATLAB). The need to move beyond the old formula‐ based approach is widely recognized.The starting point is to understand the second difference matrices that appear everywhere in scientific computing and simulation. Four special matrices with fixed and free and periodic boundary conditions (and ‐1,2,‐1 on all interior diagonals) have names. They become familiar. We discuss the “A'CA framework” for so many numerical methods and engineering applications. The Computational Science and Engineering course 18.085 will be videotaped for MIT's OpenCourseWare ocw.mit.edu. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A directed binding model of motor protein motion on protein filaments
Authors: Bolterauer H. , Tuszynski J.A. 
Published: December 2008

AbstractWe propose a new mechanism of motor protein motion on protein filaments, treating the heads as extended objects connected by an elastic neck linker region. In our model, ATP hydrolysis provides chemical energy while directed binding is key in force generation coupled with an elastic neck linker region storing elastic energy. Simulations of the differential equation of motion, based on this model, agree with experiment for both kinesin and its analog, Ncd, and can also be applied to myosin. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Acoustic simulations with higher order finite and infinite elements
Authors: Estorff Otto von , Petersen Steffen , Biermann Jan 
Published: December 2008

AbstractThe efficiency of finite element based simulations of Helmholtz problems is primarily affected by two facts. First, the numerical solution suffers from the so‐called pollution effect, which leads to very high element resolutions at higher frequencies. Furthermore, the spectral properties of the resulting system matrices, and hence the convergence of iterative solvers, deteriorate with increasing wave numbers. In this contribution the influence of different types of polynomial basis functions on the efficiency and stability of interior as well as exterior acoustic simulations is analyzed. The current investigations show that a proper choice for the polynomial shape approximation may significantly increase the performance of Krylov subspace methods. In particular, the efficiency of higher order finite and infinite elements based on Bernstein polynomial shape approximation and the corresponding iterative solution strategies is assessed for practically relevant numerical examples including the sound radiation from rolling vehicle tires. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Functional differential equations arising in cell‐growth
Authors: Wake G. C. , Begg R. E. 
Published: December 2008

AbstractNon‐local differential equations are notoriously difficult to solve. Cell‐growth models for population growth of a cohort structured by size, simultaneously growing and dividing, give rise to a class of non‐local eigenvalue problems, whose “principal” eigenvalue is the time‐constant for growth/decay. These and other novel non‐local problems are described and solved in special cases in this paper. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A singular function boundary integral method for elliptic problems with singularities
Authors: Xenophontos Christos , Georgiou Georgios , Elliotis Miltiades 
Published: December 2008

AbstractIn this work we present a singular function boundary integral method for elliptic problems with boundary singularities. In this method, the approximation is constructed from the truncated asymptotic expansion for the solution near the singular point and the Dirichlet boundary conditions are weakly enforced by means of Lagrange multiplier functions. The resulting discrete problem is posed and solved on the boundary of the domain, away from the point of singularity. We are able to show that the method approximates the generalized stress intensity factors, i.e. the coe cients in the asymptotic expansion, at an exponential rate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An evaluation of test statistics for detecting temporary change in Bl(1,1,1,1) models
Authors: Zaharim Azami , Ismail Amiruddin , Abdullah Shahrum , Mohamed Ibrahim , Ahmad Ibrahim 
Published: December 2008

AbstractA study is carried out to investigate the sampling properties of the outlier test statistics of a procedure developed for detecting temporary change in BL(1,1,1,1) processes. It is done with respect to the sample size, the type of outlier and the size of the coefficients of the BL(1,1,1,1) process. The results show that, in general, the outlier detection procedure is capable of detecting TC, although the performance is affected if ω is large. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical solution of a minimax ergodic optimal control problem
Authors: S. Aragone Laura , Soledad Aronna María , Lotito Pablo A. 
Published: December 2008

AbstractIn this work we consider an L∞ minimax ergodic optimal control problem with cumulative cost. We approximate the cost function as a limit of evolutions problems. We present the associated Hamilton‐Jacobi‐Bellman equation and we prove that it has a unique solution in the viscosity sense. As this HJB equation is consistent with a numerical procedure, we use this discretization to obtain a procedure for the primitive problem. For the numerical solution of the ergodic version we need a perturbation of the instantaneous cost function. We give an appropriate selection of the discretization and penalization parameters to obtain discrete solutions that converge to the optimal cost. We present numerical results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sedimentation of volcanic particles
Authors: Bonadonna C. , Phillips J.C. 
Published: December 2008

AbstractVolcanic eruptions present many hazards including pyroclastic flows and volcanic mud flows (lahars) that together have caused the death of more than 65000 people in the last two centuries (e.g. eruptions of Tambora 1815, Mount Pelee 1902 and Nevado del Ruiz 1985). However tephra (volcanic rock and glass fragments) can be transported in the atmosphere for long times and distances after the eruptive event, representing one of the most widespread hazards with significant human health consequences and the potential to significantly affect crucial economical sectors such as agriculture, social services, tourism and industry. In addition, the associated deposits retain a considerable amount of information of the generating processes, such as total erupted mass, initial grainsize distribution and also important constraints on plume dynamics and eruption intensity. As a result, the study of tephra fallout is crucial to the understanding of volcanic processes and to the hazard assessment of volcanoes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability analysis of thermodynamic lubrication problems in journal bearings
Authors: Durany J. , Pereira–Pérez J. , Varas F. 
Published: December 2008

AbstractA new numerical scheme (which combines FEM, FVM and BEM methods) for solving thermohydrodynamic lubrication transient problems with cavitation is described. The algorithm is then applied to study the stability of a journal‐bearing system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Art, mathematics & cultural industry: new trends in the digital era
Authors: Lorenzi M.G. , Francaviglia M. 
Published: December 2008

AbstractIn view of modern technologies proper of the Digital Era we shortly discuss some recent activities of our research groups in the broad field of Cultural Industry, where Art, Mathematics and Physics are gaining new interrelationships concerning the use of Digital Art and Web Technologies in the domain of Scientific Communication and Visualization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of a transport mediating switch
Authors: Gedeon Tomáš , Boczko Erik , Mischaikow Konstantin 
Published: December 2008

AbstractWe show that dynamics of a general toggle switch that mediates transport between cellular compartments, converges to a unique periodic orbit in two limiting cases. These results can be perturbed for a restricted, but biologically ubiquitous model. This robustness may be the reason why only the restricted switch appears to be operating in Nature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic methods for spherically symmetric MHD α2‐dynamos
Authors: Günther U. , Kirillov O.N. 
Published: December 2008

AbstractWe consider two models of spherically‐symmetric MHD α2–dynamos; one with idealized boundary conditions (BCs); and one with physically realistic BCs. As it has been shown in our previous work, the eigenvalues λ of a model with idealized BCs and constant α–profile α0 are linear functions of α0 and form a mesh in the (α0, λ)–plane. The nodes of the spectral mesh correspond to double‐degenerate eigenvalues of algebraic and geometric multiplicity 2 (diabolical points). It was found that perturbations of the constant α –profile lead to a resonant unfolding of the diabolical points with selection rules of the resonant unfolding defined by the Fourier coefficients of the perturbations. In the present contribution we present new exact results on the spectrum of the model with physically realistic BCs and constant α. For non‐degenerate (simple) eigenvalues perturbation gradients are found at any particular α0. We briefly discuss the spectral behavior of the α2–dynamo operator over a family of homotopic deformations of the BCs between idealized ones and physically realistic ones. Furthermore, we demonstrate that although the spectral singularities are lifted, a memory about their locations remains deeply imprinted in the homotopic family of spectral deformations due to a hidden underlying invariance. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanoscale dendritic organoplatinum antitumor drugs
Authors: Howell B.A. , Fan D. , Rakesh L. 
Published: December 2008

AbstractOrganoplatinum compounds exhibit broad antitumor activity. Cisplatin [cis‐ dichlorodiammine platinum (II)] is the most prominent of this family and is currently the most prescribed cancer drug. It is widely used for the treatment of human testicular, ovarian, bladder, head and neck carcinomas. However, it is an extremely toxic compound and side effects such as nephrotoxicity and myelotoxicity are major drawbacks for its use in clinical applications. A way to combat the side effects associated with the administration of platinum drugs would be to generate a prodrug conjugate that, when present in the extracellular fluid, would slowly release active platinum species at a level below the threshold for side effects. Traditionally, linear hydrophilic polymers have been examined for potential application as carrier platforms for these drugs. The advent of dendrimers, which are highly branched macromolecules with precisely controlled nanoscale size, shape and end‐group functionality, has provided an excellent opportunity to design and formulate novel multivalent time‐release drug systems. For example, treatment of a generation 4.5 (carboxylate surface) poly(amidoamine) [PAMAM] dendrimer with diaquo(1,2‐diaminocyclohexane) platinum(II) generates a nanoparticle with forty platinum moieties attached at the surface. This polymer‐drug conjugate displays a very good release profile for the platinum species. Under physiological conditions about 80% of the platinum units are released over the first 24 hours. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal long‐distance transport systems in nature: control and applications (Poster Presentation)
Authors: Kizilova Natalya 
Published: December 2008

AbstractLong‐distance conducting systems in high plants and animals are presented by networks of rigid tubes with porous walls (in plants) or distensible tubes with impermeable walls (in animals). Geometrical relationships between the diameters, lengths and branching angles of separate conducting vessels have been studied and the results of the comparative analysis are presented. It was shown that the principles of construction of the transport systems are similar in animals and plants and correspond to the optimal pipelines with impermeable and permeable walls accordingly. The optimization criterion is the total energy expenses W for the fluid delivery and construction of the system. Global optimality at the systemic level is provided by local optimality conditions in each conducting element. It is shown that complexity of the branching system of the optimal tubes leads to certain regularities in the hydraulic and wave properties of the systems. The obtained regularities and the principles of design of the long‐distance transportation networks in Nature can be used in biomedical applications and technique. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Maximal growth rate at the Rosensweig instability: theory, experiment, and numerics
Authors: Knieling Holger , Lange Adrian , Matthies Gunnar , Rehberg Ingo , Richter Reinhard 
Published: December 2008

AbstractWe investigate the growth of a pattern of liquid crests emerging in a layer of magnetic liquid when subjected to a magnetic field oriented normally to the fluid surface. After a step like increase of the magnetic field, the temporal evolution of the pattern amplitude is measured by means of a Hall‐sensor array. The extracted growth rate is compared with predictions from linear stability analysis by taking into account the nonlinear magnetization curve M (H). The remaining discrepancy can be resolved by numerical calculations via the finite element method. By starting with a finite surface perturbation it can reproduce the temporal evolution of the pattern amplitude and the growth rate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)