bluuebunny/crossref_metadata_2025 huggingface dataset:
Partitioned formulation of frictional contact problems using localized Lagrange multipliers
Authors: González José A. , Park K. C. , Felippa Carlos A.
Published: October 2005

Interface treatment methods for the contact problem between non‐matching meshes have traditionally been based on a direct coupling of the contacting solids employing a master–slave strategy or classical Lagrange multipliers. These methods tend to generate strongly coupled systems that is dependent on the discretization characteristics on each side of the contact zone. In this work a displacement frame is intercalated between the interface meshes. The frame is then discretized so that the discrete frame nodes are connected to the contacting substructures using the localized Lagrange multipliers collocated at the interface nodes. The resulting methodology alleviates the need for master–slave book‐keeping and provides a partitioned formulation which preserves software modularity, facilitates non‐matching mesh treatment and passes the contact patch test. Frictional contact problems are used to demonstrate the salient features of the proposed method. Copyright © 2005 John Wiley & Sons, Ltd.
The Singlet–Triplet Separation in CF2: State‐of‐the‐Art Ab Initio Calculations and Franck–Condon Simulations Including Anharmonicity
Authors: Chau Foo‐tim , Mok Daniel K. W. , Lee Edmond P. F. , Dyke John M.
Published: October 2005

Geometrical parameters, vibrational frequencies and relative electronic energies of the X̃2B1 state of CF2− and the X̃1A1 and ã3B1 states of CF2 have been calculated. Core‐electron effects on the computed minimum‐energy geometries and relative electronic energies have been investigated, and relativistic contributions to the computed relative electronic energies calculated. Potential energy functions of the X̃2B1 state of CF2− and the X̃1A1 and ã3B1 states of CF2 have been determined, and anharmonic vibrational wavefunctions of these states calculated variationally. Franck–Condon factors including anharmonicity and Duschinsky rotation have been computed and used to simulate the ã–X̃ emission spectrum of CF2 determined by S. Koda [Chem. Phys. Lett. 1978, 55, 353] and the 364 nm laser photodetachment spectrum of CF2− obtained by R. L. Schwartz et al. [J. Phys. Chem. A 1999, 103, 8213]. Comparison between theory and experiment shows that the theoretical approach benchmarked in the present study is able to give highly reliable positions for the CF2(X̃1A1)+e←CF2−(X̃2B1) and CF2(ã3B1)+e←CF2−(X̃2B1) bands in the photoelectron spectrum of CF2− and a reliable singlet–triplet gap for CF2. It is therefore concluded that the same theoretical approach should give reliable simulated CCl2(X̃1A1)+e←CCl2−(X̃2B1) and CCl2(ã3B1)+e←CCl2−(X̃2B1) bands in the photodetachment spectrum of CCl2− and a reliable singlet–triplet gap for CCl2.
A Combined Ab Initio/Franck–Condon Study of the Ã–X̃ Single‐Vibronic‐Level Emission Spectrum of CCl2 and the Photodetachment Spectrum of CCl2−
Authors: Dyke John M. , Lee Edmond P. F. , Mok Daniel K. W. , Chau Foo‐tim
Published: October 2005

State‐of‐the‐art ab initio calculations have been carried out on the X̃1A1, ã3B1 and Ã1B1 states of CCl2 and the X̃2B1 state of CCl2−. Franck–Condon factors including anharmonicity have been calculated, between the CCl2 states, and between the CCl2− X̃2B1 state and the CCl2 states. They are used to simulate the Ã–X̃ single‐vibronic‐level (SVL) emission spectra of CCl2 determined by M.‐L. Lui et al. [PCCP 2003, 5, 352] and the 364 nm laser photodetachment spectrum of CCl2− obtained by R. L. Schwartz et al. [J. Phys. Chem. A 1999, 103, 8213]. Comparison between simulated and observed spectra confirms the vibrational assignments of the X̃2B1 SVL emission spectra and the T0 position of the Ã1B1 state of CCl2. For the photodetachment spectrum of CCl2−, spectral simulation shows that the higher binding energy ã3B1(CCl2)←X̃2B1(CCl2−) band is well separated from the X̃1A1(CCl2)←X̃2B1(CCl2−) band. It is concluded that the observed second band, which overlaps heavily with the X̃1A1(CCl2)←X̃2B1(CCl2−) band in the photodetachment spectrum of CCl2− cannot be assigned to the CCl2(ã3B1)+e→CCl2−(X̃2B1) detachment process. Further ab initio calculations carried out in the present investigation support the suggestion that the second band in the 364 nm photodetachment spectrum of CCl2− is due to detachment from an excited state of CCl2−, a linear quartet state, to a triplet state of CCl2. These calculations identify the anionic state to be the lowest 4Σg− (4Σ−) state, which photodetaches vertically to the 3Σg− (3Σ−; adiabatically ã3B1) and/or 3Πu (3Π) states of CCl2 to give the second band observed in the 364 nm photodetachment spectrum of CCl2−.
Photodissociation Study of Ethyl Bromide in the Ultraviolet Range by the Ion‐Velocity Imaging Technique
Authors: Tang Ying , Ji Lei , Zhu Rongshu , Wei Zhengrong , Zhang Bing
Published: October 2005

The photodissociation of ethyl bromide has been studied in the wavelength range of 231–267 nm by means of the ion velocity imaging technique coupled with a [2+1] resonance‐enhanced multiphoton ionization (REMPI) scheme. The velocity distributions for the Br (2P1/2) (denoted Br*) and Br (2P3/2) (denoted Br) fragments are determined, and each can be well‐fitted by a narrow single‐peaked Gaussian curve, which suggests that the bromine fragments are generated as a result of direct dissociation via repulsive potential‐energy surfaces (PES). The recoil anisotropy results show that β(Br) and β(Br*) decrease with the wavelength, and the angular distributions of Br* suggest a typical parallel transition. The product relative quantum yields at two different wavelengths are Φ234nm(Br*)=0.17 and Φ267nm(Br*)=0.31. The relative fractions of each potential surface for the bromine fragments’ production at 234 and 267 nm reveal the existence of a curve crossing between the 3Q0 and 1Q1 potential surfaces, and the probability of curve crossing decreases with the laser wavelength. The symmetry reduction of C2H5Br from C3v to Cs invokes a nonadiabatic coupling between the 3Q0 and 1Q1 states, and with higher energy photons, the probability that crossing will take place increases.
Cover Picture: Microcavity‐Controlled Single‐Molecule Fluorescence (ChemPhysChem 10/2005)
Authors: Steiner Mathias , Schleifenbaum Frank , Stupperich Clemens , Virgilio Failla Antonio , Hartschuh Achim , Meixner Alfred Johann
Published: October 2005

The cover picture shows a dipole emitter embedded in a microresonator with variable mirror separation that is excited by a tightly focused laser beam. Single dye molecules can be forced to emit into a narrow spectral window with an enhanced fluorescence rate (red curve). The efficiency of this process is determined by the interplay between the microresonator structure and the original fluorescence spectrum of the dye (grey curve). Details can be found in the Article by M. Steiner et al. on page 2190.
Periodic viscous flow: A bench‐mark problem
Authors: Goldberg I. S. , Carey G. F. , McLay R. , Phinney L.
Published: October 2005

A double‐transform technique provides a semi‐analytic solution in the form of a series expansion for unsteady axisymmetric Stokes flow in the entrance region of a semi‐infinite rigid cylindrical tube. This in turn offers an appropriate bench‐mark problem for evaluating the quality of numerical approximations. To illustrate this, periodic axial flow in a circular cylinder is considered. Some aspects of the bench‐mark problem that are of interest include the reverse flow in the wall layers, the accuracy of the approximate method in different flow regimes and the mesh grading. This bench‐mark problem and the numerical study provide some insight into practical issues pertinent to the approximate solution of unsteady and periodic flows.
On the theory of semi‐implicit projection methods for viscous incompressible flow and its implementation via a finite element method that also introduces a nearly consistent mass matrix. Part 2: Implementation
Authors: Gresho Philip M. , Chan Stevens T.
Published: October 2005

Ever since the expansion of the finite element method (FEM) into unsteady fluid mechanics, the ‘consistent mass matrix’ has been a relevant issue. Applied to the time‐dependent incompressible Navier–Stokes equations, it virtually demands the use of implicit time integration methods in which full ‘velocity–pressure coupling’ is also inherent. The high cost of such (high‐quality) FEM calculations led to the development of simpler but ad hoc methods in which the ‘lumped’ mass matrix is employed and the velocity and pressure are uncoupled to the maximum extent possible. Resulting computer codes were less expensive to use but suffered a significant loss of accuracy, caused by lumping the mass when the flow was advection‐dominated and accurate transport of ‘information’ was important. In the second part of this paper we re‐introduce the consistent mass matrix into some semi‐implicit projection methods in such a way that the cost advantage of lumped mass and the accuracy advantage of consistent mass are simultaneously realized.
Finite element methods for one‐dimensional combustion problems
Authors: Ramos J. I.
Published: October 2005

Three adaptive finite element methods based on equidistribution, elliptic grid generation and hybrid techniques are used to study a system of reaction–diffusion equations. It is shown that these techniques must employ sub‐equidistributing meshes in order to avoid ill‐conditioned matrices and ensure the convergence of the Newton method. It is also shown that elliptic grid generation methods require much longer computer times than hybrid and static rezoning procedures. The paper also includes characteristic, Petrov–Galerkin and flux‐corrected transport algorithms which are used to study a linear convection–reaction–diffusion equation that has an analytical solution. The flux‐corrected transport technique yields monotonic solutions in good agreement with the analytical solution, whereas the Petrov–Galerkin method with quadratic upstream‐weighted functions results in very diffused temperature profiles. The characteristic finite element method which uses a Lagrangian–Eulerian formulation overpredicts the flame front location and exhibits overshoots and undershoots near the temperature discontinuity. These overshoots and undershoots are due to the interpolation of the results of the Lagrangian operator onto the fixed Eulerian grid used to solve the reaction–diffusion operator, and indicate that characteristic finite element methods are not able to eliminate numerical diffusion entirely.
Numerical studies of fluid flow through tubes with double constrictions
Authors: Lee T. S.
Published: October 2005

The flow fields in the neighbourhood of double constrictions in a circular cylindrical tube were studied numerically. The effects on the streamline, velocity and vorticity distributions as the flow passes through the constrictions in the tube were studied in the Reynolds number range 5–200. Double constrictions with dimensionless spacing ratios of 1, 2, 3 and ∞ were studied for a 50% constriction.

It is noted that when the Reynolds number is below 10, no recirculation region is formed in the above constricted flow. For Reynolds numbers greater than 10, a recirculation region forms downstream of each of the constrictions. For constriction spacing ratios of 1, 2, and 3, when the Reynolds number is high, a recirculation region spreads between the valley of the constrictions. The recirculation region formed between the two constrictions has a diminishing effect on the generation of wall vorticity near the second constriction area. In general, the peak value of wall vorticity is found slightly upstream of each of the constrictions. When the Reynolds number is increased, the peak wall vorticity value increases and its location is moved upstream. Maximum wall vorticity generated by the first constriction is found to be always greater than the maximum wall vorticity generated by the second constriction. The extent of this spreading of the recirculation region from the first constriction and its effects on the second constriction depend on the constriction spacing ratio and the flow Reynolds number.
A multigrid solver for the vorticity‐velocity Navier‐Stokes equations
Authors: Napolitano M. , Catalano L. A.
Published: October 2005

This paper provides a multigrid incremental line‐Gauss‐Seidel method for solving the steady Navier‐Stokes equations in two and three dimensions expressed in terms of the vorticity and velocity variables. The system of parabolic and Poisson equations governing the scalar components of the vector unknowns is solved using centred finite differences on a non‐staggered grid. Numerical results for the two‐dimensional driven cavity problem indicate that the spatial discretization of the equation defining the value of the vorticity on the boundary is extremely critical to obtaining accurate solutions. In fact, a standard one‐sided three‐point second‐order‐accurate approximation produces very inaccurate results for moderate‐to‐high values of the Reynolds number unless an exceedingly fine mesh is employed. On the other hand, a compact two‐point second‐order‐accurate discretization is found to be always satisfactory and provides accurate solutions for Reynolds number up to 3200, a target impossible heretofore using this formulation and a non‐staggered grid.
The PROSPER General Circulation Model, an adapted form of the Sandia Ocean Modelling method: A numerical description
Authors: Zuur E. A. H.
Published: October 2005

The PROSPER General Circulation Model (PGCM) is a three‐dimensional model based on the incompressible Navier‐Stokes equations, an equation of state and the heat equation. The hydrostatic approximation and the rigid lid approximation are used. The system of equations is converted into an equivalent form in which the surface pressure is more directly expressed in terms of a two‐dimensional Poisson equation. The finite difference method is described and analysed. In particular, the iteration method within every time step to determine the new surface pressure and velocity components, and numerical diffusion aspects due to the use of the staggered Arakawa‐C grid are looked at. Since part of the development of the PGCM code is a result of studying the Sandia Ocean Modelling System (SOMS), a comparison is made with respect to the concepts used in both models.
A quadratic‐element formulation of the complex variable boundary element method
Authors: Bailey Robert T. , Hsieh C. K.
Published: October 2005

The complex variable boundary element method (CVBEM) for simply connected domains is extended to include the use of quadratic elements and interpolating functions. The derivation follows the format for linear elements given in the literature, with second‐degree Lagrange polynomials taken as the interpolating functions. The quadratic‐element CVBEM nodal‐ and interior‐point equations are given in detail, and the resulting formulation is successfully tested by solving example problems with available analytical solutions. Comparisons of computational efficiency and accuracy are made between the solutions obtained using linear and quadratic elements. Additional comparisons are made using published results from other boundary element methods.
Segmented multigrid domain decomposition procedure for incompressible viscous flows
Authors: Srinivasan Kumar , Rubin Stanley G.
Published: October 2005

The application of grid stretching or grid adaptation is generally required in order to optimize the distribution of nodal points for fluid‐dynamic simulation. This is necessitated by the presence of disjoint high gradient zones, that represent boundary or free shear layers, reversed flow or vortical flow regions, triple deck structures, etc. A domain decomposition method can be used in conjunction with an adaptive multigrid algorithm to provide an effective methodology for the development of optimal grids. In the present study, the Navier‐Stokes (NS) equations are approximated with a reduced Navier‐Stokes (RNS) system, that represents the lowest‐order terms in an asymptotic Re expansion. This system allows for simplified boundary conditions, more generality in the location of the outflow boundary, and ensures mass conservation in all subdomain grid interfaces, as well as at the outflow boundary. The higher‐order (NS) diffusion terms are included through a deferred corrector, in selected subdomains, when necessary. Adaptivity in the direction of refinement is achieved by grid splitting or domain decomposition in each level of the multigrid procedure. Normalized truncation error estimates of key derivatives are used to determine the boundaries of these subdomains. The refinement is optimized in two co‐ordinate directions independently. Multidirectional adaptivity eliminates the need for grid stretching so that uniform grids are specified in each subdomain. The overall grid consists of multiple domains with different meshes and is, therefore, heavily graded. Results and computational efficiency are discussed for the laminar flow over a finite length plate and for the laminar internal flow in a backward‐facing step channel.
Numerical simulation of cooling‐induced convective currents on a littoral slope
Authors: Horsch G. M. , Stefan H. G. , Gavali S.
Published: October 2005

The transient development of cooling‐induced flow in a triangular domain filled with water is studied by means of numerical simulation as a model for flow developing in the littoral region of lakes or coasts. The domain is fitted in polar co‐ordinates; solutions are obtained for different values of the independent parameters of the model, which are the Rayleigh number (Ra), the Prandtl number (Pr) and the slope of the domain (S). Within the ranges examined, as Ra is increased, different regimes of the developing flow are observed; these are found qualitatively to be insignificantly influenced by changes in S, whereas the flow is found to be quantitatively insensitive to Pr for high enough values of Pr. Several interesting features of the flow are depicted and integral values useful in the analysis of flow in lakes are extracted.
Space‐time finite element computation of compressible flows between moving components
Authors: Wren G. P. , Ray S. E. , Aliabadi S. K. , Tezduyar T. E.
Published: October 2005

A numerical simulation capability for the injector flow of a regenerative liquid propellant gun (RLPG) is presented. The problem involves fairly complex geometries and two pistons in relative motion; therefore a stabilized space‐time finite element formulation developed earlier and capable of handling flows with moving mechanical components is used. In addition to the specifics of the numerical method, its application to a 30 mm RLPG test firing is discussed. The computational data from the simulation of this test case are interpreted to provide information on flow characteristics, with emphasis on the tendency of the flow to separate from the injection orifice boundary of the test problem. In addition, the computations provided insight into the behaviour of the flow entering the combustion chamber.
Gene expression by human monocytes from peripheral blood in response to exposure to metals
Authors: Jost‐Albrecht Katrin , Hofstetter Willy
Published: October 2005

With increasing life expectancy and active lifestyles, the longevity of arthroplasties has become an important problem in orthopaedic surgery and will remain so until novel approaches to joint preservation have been developed. The sensitivity of the recipient to the metal alloys may be one of the factors limiting the lifespan of implants. In the present study, the response of human monocytes from peripheral blood to an exposure to metal ions was investigated, using the method of real‐time polymerase chain reaction (PCR)–based low‐density arrays. Upon stimulation with bivalent (Co2+ and Ni2+) and trivalent (Ti3+) cations and with the calcium antagonist LaCl3, the strength of the elicited monocytic response was in the order of Co2+ ≥ Ni2+ > Ti3+ ≥ LaCl3. The transcriptional regulation of the majority of genes affected by the exposure of monocytes to Co2+ and Ni2+ was similar. Some genes critically involved in the processes of inflammation and bone resorption, however, were found to be differentially regulated by these bivalent cations. The data demonstrate that monocytic gene expression is adapted in response to metal ions and that this response is, in part, specific for the individual metals. It is suggested that metal alloys used in arthroplasties may affect the extent of inflammation and bone resorption in the peri‐implant tissues in dependence of their chemical composition. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
An in vivo study of tricalcium phosphate and glutaraldehyde crosslinking gelatin conduits in peripheral nerve repair
Authors: Chen Ming‐Hong , Chen Pei‐Ru , Chen Mei‐Hsiu , Hsieh Sung‐Tsang , Huang Jing‐Shan , Lin Feng‐Huei
Published: October 2005

In order to modulate the mechanical properties of gelatin, we previously developed a biodegradable composite composed by tricalcium phosphate and glutaraldehyde crosslinking gelatin (GTG) feasible for surgical manipulation. In this study, we evaluated the in vivo applications of GTG conduit for peripheral nerve repair. The effect of sciatic nerve reconstruction was compared between resorbable permeable GTG conduits and durable impermeable silicone tubes. Traditional methods of assessing nerve recovery following peripheral nerve repair including histomorphometric and electrophysiologic features were conducted in our study. In addition, autotomy score and sciatic function index (SFI) in walking tract analysis were used as additional parameters for assessing the return of nerve function. Twenty‐four weeks after sciatic nerve repair, the GTG conduits were harvested. Microscopically, regeneration of nerves was observed in the cross‐section at the mid portion of all implanted GTG conduits. The cross‐sectional area of regenerated nerve of the GTG group was significant larger than that of the silicone group. In the compound muscle action potentials (CMAP), the mean recovery index of CMAP amplitude was 0.24 ± 0.02 for the silicone group, 0.41 ± 0.07 for the GTG group. The mean SFI increased with time in the GTG group during the evaluation period until 24 weeks. Walking tract analysis showed a higher SFI score in the GTG group at both 12 and 24 weeks. The difference reached a significant level at 24 weeks. Thus, the histomorphometric, electrophysiologic, and functional assessments demonstrate that GTG can be a candidate for peripheral nerve repair. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Low‐frequency asymptotics for dissipative Maxwell's equations in bounded domains
Authors: Weck Norbert , Witsch Karl J.
Published: October 2005

Consider a bounded domain Ω surrounded by a perfect conductor and containing a conducting cavity D. The behaviour of the solutions of the time harmonic Maxwell problem as frequency tends to 0 is analysed in this situation. Necessary and sufficient conditions on the excitations are given which guarantee the existence of a limit. This limit turns out to be the solution of some static problem.
Dissipative Maxwell's equations at low frequencies
Authors: Ramm A. G. , Weaver O. L. , Weck N. , Witsch K. J.
Published: October 2005

A study of the low‐frequency behaviour of solutions to dissipative Maxwell's equations with discontinuous coefficients is given.
Asymptotic expansions for hyperbolic–parabolic systems with a small parameter
Authors: Kreiss Gunilla
Published: October 2005

In this paper we consider initial‐boundary value problems for systems with a small parameter ϵ. The problems are mixed hyperbolic–parabolic when ϵ > 0 and hyperbolic when ϵ = 0. Often the solution can be expanded asymptotically in ϵ and to first approximation it consists of the solution of the corresponding hyperbolic problem and a boundary layer part. We prove sufficient conditions for the expansion to exist and give estimates of the remainder. We also examine how the boundary conditions should be choosen to avoid O(1) boundary layers.
The trend to a stationary state for the Lebowitz Stick model
Authors: Arkeryd L. , Ianiro N. , Triolo L.
Published: October 2005

The asymptotic behaviour of the Lebowitz stick model in kinetic theory is studied in weak* measure, L1‐ and L∞‐sense.
Resonance phenomena in infinite strings with periodic ends
Authors: Werner P.
Published: October 2005

We study the propagation of linear waves, generated by a compactly supported time‐harmonic force distribution, in an infinite string under the assumption that the material properties are p1‐periodic for x > a and p2‐periodic for x < − a. As has been pointed out in two preceding papers devoted to related configurations ([4], [5]), the combination of a time‐periodic force and a periodic spatial structure may lead to resonance phenomena. We show that the present configuration also permits resonances of orders t and t1/2 for a discrete set of frequencies. The occurrence of resonances is closely related to the presence of non‐trivial solutions of the corresponding time‐independent homogeneous problem which satisfy certain asymptotic properties (‘standing waves’).
Full low‐frequency asymptotic expansion for second‐order elliptic equations in two dimensions
Authors: Kleinman R. , Vainberg B.
Published: October 2005

The present paper contains the low‐frequency expansions of solutions of a large class of exterior boundary value problems involving second‐order elliptic equations in two dimensions. The differential equations must coincide with the Helmholtz equation in a neighbourhood of infinity, however, they may depart radically from the Helmholtz equation in any bounded region provided they retain ellipticity. In some cases the asymptotic expansion has the form of a power series with respect to k2 and k2 (ln k + a)−1, where k is the wave number and a is a constant. In other cases it has the form of a power series with respect to k2, coefficients of which depend polynomially on In k. The procedure for determining the full low‐frequency expansion of solutions of the exterior Dirichlet and Neumann problems for the Helmholtz equation is included as a special case of the results presented here.
Scattering results for measure potentials with unbounded support
Authors: Ford Richard
Published: October 2005

The eigenfunction expansion theorem and its application to the scattering operator and the scattering matrix is extended to Schrödinger operators with measure potentials with unbounded support on ℝn that are known to generate wave operators that are strongly complete. Analyticity conditions of the eigenfunctions and the scattering matrix are presented.
The sorption of mixtures under linear equilibrium partitioning and chemical transformation
Authors: Oppenheimer Seth F.
Published: October 2005

We consider the flow of a mixture, whose components are undergoing temporally and spatially varying linear equilibrium sorption partitioning and, possibly nonlinear, chemical transformations. We are able to generate an evolution system of parabolic type on the space of uniformly continuous functions and thus obtain classical solutions for arbitrary initial values.
New convergence results and preconditioning strategies for the conjugate gradient method
Authors: Kaporin I. E.
Published: October 2005

Instead of the standard estimate in terms of the spectral condition number we develop a new CG iteration number estimate depending on the quantity B = 1/ntr M/(det M)1/n, where M is an n × n preconditioned matrix. A new family of iterative methods for solving symmetric positive definite systems based on B‐reducing strategies is described. Numerical results are presented for the new algorithms and compared with several well‐known preconditioned CG methods.
A simple hybrid stress element for shear deformable plates
Authors: de Miranda Stefano , Ubertini Francesco
Published: October 2005

A new quadrilateral 4‐node element for shear deformable plates is developed based on the hybrid stress formulation. The element is designed to be simple, stable, free of locking and to pass all the patch tests. To this purpose, special attention is devoted to select displacement and stress approximations. The standard displacement interpolation is enhanced by linking the transverse displacement to the nodal rotations and an appropriate stress approximation is rationally derived. In particular, the assumed stress approximation is equilibrated within each element, co‐ordinate invariant and ruled by the minimum number of parameters. Excellent element performance is demonstrated by a wide experimental evaluation. Copyright © 2005 John Wiley & Sons, Ltd.
Mathematical analysis and numerical study to free vibrations of annular plates using BIEM and BEM
Authors: Chen J. T. , Lin S. Y. , Chen I. L. , Lee Y. T.
Published: October 2005

In this paper, the spurious eigenequations for annular plate eigenproblems by using BIEM and BEM are studied in the continuous and discrete systems. Since any two boundary integral equations in the plate formulation (4 equations) can be chosen, 6 (C) options can be considered instead of only two approaches (single‐layer and double‐layer methods, or singular and hypersingular equations) which are adopted for the eigenproblems of the membrane and acoustic problems. The occurring mechanism of the spurious eigenequation for annular plates in the complex‐valued formulations is studied analytically. For the continuous system, degenerate kernels for the fundamental solution and the Fourier series expansion for the circular boundary density are employed to derive the true and spurious eigenequations analytically. For the discrete system, the degenerate kernels for the fundamental solution and circulants resulting from the circular boundary are employed to determine the true and spurious eigenequations. True eigenequation depends on the specified boundary condition while spurious eigenequation is embedded in each formulation. It is found that the spurious eigenvalue for the annular plate is the true eigenvalue of the associated interior problem with an inner radius of the annular domain. Also, we provide three methods (SVD updating technique, Burton and Miller method and CHIEF method) to suppress the occurrence of the spurious eigenvalues. Several examples were demonstrated to check the validity of the formulations. Copyright © 2005 John Wiley & Sons, Ltd.
A mathematical framework of the bridging scale method
Authors: Tang Shaoqiang , Hou Thomas Y. , Liu Wing Kam
Published: October 2005

In this paper, we present a mathematical framework of the bridging scale method (BSM), recently proposed by Liu et al. Under certain conditions, it had been designed for accurately and efficiently simulating complex dynamics with different spatial scales. From a clear and consistent derivation, we identify two error sources in this method. First, we use a linear finite element interpolation, and derive the coarse grid equations directly from Newton's second law. Numerical error in this length scale exists mainly due to inadequate approximation for the effects of the fine scale fluctuations. An modified linear element (MLE) scheme is developed to improve the accuracy. Secondly, we derive an exact multiscale interfacial condition to treat the interfaces between the molecular dynamics region ΩD and the complementary domain ΩC, using a time history kernel technique. The interfacial condition proposed in the original BSM may be regarded as a leading order approximation to the exact one (with respect to the coarsening ratio). This approximation is responsible for minor reflections across the interfaces, with a dependency on the choice of ΩD. We further illustrate the framework and analysis with linear and non‐linear lattices in one‐dimensional space. Copyright © 2005 John Wiley & Sons, Ltd.
On the density of finite element matrices
Authors: George J. Alan
Published: October 2005

Explicit formulae for the density of a class of finite element matrices are presented. The formulae are functions of the characteristics of the mesh and the element (piecewise polynomial) employed. Results are given for two‐dimensional triangular and quadrilateral elements and three‐dimensional tetrahedral and cuboid elements. These results are useful in the management of storage in finite element computer programmes.
A comparison of preconditioned iterative techniques using rapid operator application against direct solution methods
Authors: Foresti S. , Hassanzadeh S. , Murakami H. , Sonnad V.
Published: October 2005

The p‐version of the finite element method which uses high order hierarchic basis functions within an element allows for ease of adaptive computation, and high accuracy with relatively few degrees of freedom. However, the solution time and storage requirements for large 3‐D problems can be very high when direct methods are used to factor global matrices. Iterative techniques with rapid operator application have minimal storage requirements because neither element nor global matrices are formed, but may not converge rapidly enough. We study an approach that attempts to combine the two methods by using direct factorization of the matrix corresponding to low level polynomials as a preconditioner to an iterative method at a higher polynomial level. This resulting solution scheme converges more rapidly than an unpreconditioned scheme but has much lower storage requirements than direct methods. We illustrate the effectiveness of this scheme on some large three‐dimensional problems in structural analysis.
Many‐body perturbation theory combined with time dependent DFT: A new method for the calculation of the dielectric function of solids
Authors: Del Sole Rodolfo , Pulci Olivia , Olevano Valerio , Marini Andrea
Published: October 2005

We show an approximate method to calculate the polarizability of a many‐electron system within Green's function theory in a similar way as within time‐dependent density functional theory (TDDFT). The basic idea is to join the computational simplicity of the latter with the accuracy of the former. We apply this approach to a prototype system, LiF. For comparison, we also show results obtained within other approximated TDDFT‐based methods. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitrogen‐15 in NO characterises differently reactive soil organic N pools
Authors: Oelmann Yvonne , Wilcke Wolfgang , Bol Roland
Published: October 2005

Intercropping with legumes is known to increase the plant‐available nitrogen (N) in soil, but can also increase leaching of NO to the groundwater. To minimise NO leaching risks, knowledge of the N‐release processes is essential, including an estimate of the contribution of legumes to total NO concentrations in soil. Our objectives were to answer the questions: (1) whether the presence of legume roots increases N mineralisation, and (2) whether the proportion of legume‐derived N in NO could be calculated with the help of natural abundance 15N in NO. We sampled soil monoliths of a Medicago x varia Martyn monoculture in August 2004 and set up three treatments: ‘disturbance’ (sieved to <2 mm), ‘disturbance‐roots’ (sieved to <2 mm and visible roots removed), and ‘control’ (left untreated). During an incubation period of 70 days, an N‐free nutrient solution was leached through the samples weekly. In the leachates we measured total N, total organic carbon, NO, and NH concentrations. Six of the 13 sampling dates were chosen for N isotope analysis in NO. Nitrate was separated as AgNO3. During the incubation, 3 to 6% of the initial total mass of total N (192 to 274 mg N) in soil was mineralised. Nitrogen mineralisation followed zero‐order kinetics independent of treatments. Mineralisation rates decreased in the order control (day 70: 3.7 µg NO3‐N (mg Ninitial)−1) > disturbance‐roots (2.6 µg NO3‐N (mg Ninitial)−1) > disturbance (1.9 µg NO3‐N (mg Ninitial)−1), indicating that mineralisation of legume roots did not play a major role in N mineralisation. The δ15N values jumped from ca. 3‰ to ca. 8‰ after 2 weeks of incubation, which we attributed to the contribution of two N pools. An exponential two‐pool model could not be fitted to the data. Legume‐derived soil organic matter, SOM (pool 1), was mineralised at the same rate as SOM accumulated before establishment of the legumes (pool 2). Fresh legume roots did not contribute significantly to N mineralisation. Copyright © 2005 John Wiley & Sons, Ltd.
Application of simultaneous thermal analysis mass spectrometry and stable carbon isotope analysis in a carbon sequestration study
Authors: Lopez‐Capel E. , Bol R. , Manning D. A. C.
Published: October 2005

The simultaneous analysis of evolved gases and the determination of stable isotope composition (δ13C) as part of a thermal analysis experiment have been used to (a) distinguish bulk chemical hosts for carbon (C) and nitrogen (N) within a soil and (b) track labelled C within a soil sequestration experiment. C3 and C4 dung was applied to a pasture soil, and soil samples taken for analysis. The results of thermogravimetry‐differential scanning calorimetry‐quadrupole mass spectrometry‐isotope ratio mass spectrometry (TG‐DSC‐QMS‐IRMS) show that the proportion of more refractory C (lignin‐like) is greater for the dungs than for the soil organic matter (SOM), and that this increases with time within the soil. Analysis of evolved gases shows that nitrogen is associated with the decomposition of more refractory C, and is not so strongly associated with the labile C component. IRMS analysis distinguished C3 and C4 dung, and allowed the amount of C from these sources to be estimated for the soil samples. Most dung C enters the refractory SOM fraction. This paper demonstrates the potential of TG‐DSC‐QMS‐IRMS in the investigation of SOM. Copyright © 2005 John Wiley & Sons, Ltd.
Exposure ages from relict lateral moraines overridden by the Fennoscandian ice sheet
Authors: Fabel Derek , Fink David , Fredin Ola , Harbor Jon , Land Magnus , Stroeven Arjen P.
Published: October 2005

Lateral moraines constructed along west to east sloping outlet glaciers from mountain centred, pre-last glacial maximum (LGM) ice fields of limited extent remain largely preserved in the northern Swedish landscape despite overriding by continental ice sheets, most recently during the last glacial. From field evidence, including geomorphological relationships and a detailed weathering profile including a buried soil, we have identified seven such lateral moraines that were overridden by the expansion and growth of the Fennoscandian ice sheet. Cosmogenic 10Be and 26Al exposure ages of 19 boulders from the crests of these moraines, combined with the field evidence, are correlated to episodes of moraine stabilisation, Pleistocene surface weathering, and glacial overriding. The last deglaciation event dominates the exposure ages, with 10Be and 26Al data derived from 15 moraine boulders indicating regional deglaciation 9600 ± 200 yr ago. This is the most robust numerical age for the final deglaciation of the Fennoscandian ice sheet. The older apparent exposure ages of the remaining boulders (14,600–26,400 yr) can be explained by cosmogenic nuclide inheritance from previous exposure of the moraine crests during the last glacial cycle. Their potential exposure history, based on local glacial chronologies, indicates that the current moraine morphologies formed at the latest during marine oxygen isotope stage 5. Although numerous deglaciation ages were obtained, this study demonstrates that numerical ages need to be treated with caution and assessed in light of the geomorphological evidence indicating moraines are not necessarily formed by the event that dominates the cosmogenic nuclide data.
foreword shark, skate and ray research at the mba and cefas
Authors: ellis jim , dulvy nick , o'brien carl , sims david , southall emily
Published: October 2005

for many decades, scientists at the marine biological association (mba) in plymouth and the centre for environment, fisheries and aquaculture science (cefas), formerly the directorate of fisheries research, at lowestoft have undertaken considerable research into the ecology and life histories of elasmobranch fish around the british isles.
movement of blue shark, prionace glauca, in the north-east atlantic based on mark–recapture data
Authors: queiroz nuno , lima fernando p. , maia anabela , ribeiro pedro a. , correia joão p. , m. santos antónio
Published: October 2005

a shark tagging programme along the portuguese coast was initiated in 2001 in collaboration with the national marine fisheries service. from a total of 168 blue sharks (prionace glauca) tagged, 34 sharks were recaptured (20% return rate) providing important information on this species' movement patterns for the area. a total of 28 sharks travelled less than 1000 km while at liberty for time periods ranging from 22 to 1294 days. the remaining fish travelled long distances to north-west africa, central atlantic and the bay of biscay. only one shark made a transatlantic migration, being recaptured 3187 km from the tagging site. north–south movements seem to be related to seasonal sea-surface temperature variation in the north-east atlantic. seasonal segregation of different life stages also occurs.
siphon nipping of the bivalve amiantis purpurata by the electric ray discopyge tschudii in mar del plata, argentina
Authors: arrighetti florencia , livore juan pablo , penchaszadeh pablo e.
Published: October 2005

a total of 67 discopyge tschudii was captured. individuals were sexed, measured and their stomach content analysed. siphon tips of the bivalve amiantis purpurata from each stomach were individually counted, weighed and their length and width measured. the size–frequency distribution of the local population of a. purpurata was surveyed for two years. siphons of a. purpurata were the main food item in 90% of individuals having stomach contents. the clam population was markedly bimodal, with 24 mm and 46 mm mean shell length for the younger and older size-classes, respectively. grazing by d. tschudii on a. purpurata varied with size and sex of the fish. small rays mainly ingested small siphons and large rays large siphons. nipped siphon tips were longer in male than in female rays.
reproductive biology of the blackmouth catshark, galeus melastomus (chondrichthyes: scyliorhinidae) off the south coast of portugal
Authors: costa m.e. , erzini k. , borges t.c.
Published: October 2005

the reproductive biology of 1045 female (9.5–67 cm (total length (tl)) and 1007 male (9.4–64.3 cm tl) blackmouth catsharks, galeus melastomus, was investigated. the sharks were caught off southern portugal by bottom crustacean trawlers at depths from 209 to 754 m. the sex ratio was 1:1, and this species is sexually dimorphic with males approaching maturity at smaller size than females. sexual segregation appears to be given for the stock within the study area. sexual maturity was reached at a total length above 49 cm in males and above 56 cm in females. mating and egg-deposition take place all year round, with two reproductive peaks of activity, in winter and summer. egg capsules are, on average, 54 mm long and 21 mm wide, with a maximum of 63×25 mm encountered. morphometric measurements of claspers, testes, ovaries, and oviducal glands were suitable for determining sexual maturity of blackmouth catshark.
humphead wrasse (cheilinus undulatus) rare on the west coast of india
Authors: sluka r.d. , lazarus s.
Published: October 2005

humphead wrasse (cheilinus undulatus) are widely distributed throughout the indo-pacific region, but usually at low densities. this species' distribution in india includes lakshadweep, gulf of mannar, the east coast and the andaman and nicobar islands. the abundance and distribution of this species on the west coast of india was unknown prior to this study.
implications for memetics
Authors: blackmore susan
Published: October 2005

the implications that steels & belpaeme's (s&b's) models have for memetics are discussed. the results demonstrate the power of memes (in this case colour words) to influence both concept formation, and the creation of innate concepts. they provide further evidence for the memetic drive hypothesis, with implications for the evolution of the human brain and for group differences in categorisation.
how to learn a conceptual space
Authors: chella antonio
Published: October 2005

the experiments proposed in the article by steels & belpaeme (s&b) can be considered as a starting point toward a general methodology for the automatic learning of conceptual spaces.
color categories in biological evolution: broadening the palette
Authors: christensen wayne d. , tommasi luca
Published: October 2005

the general structure of steels & belpaeme's (s&b's) central premise is appealing. theoretical stances that focus on one type of mechanism miss the fact that multiple mechanisms acting in concert can provide convergent constraints for a more robust capacity than any individual mechanism might achieve acting in isolation. however, highlighting the significance of complex constraint interactions raises the possibility that some of the relevant constraints may have been left out of s&b's own models. although abstract modeling can help clarify issues, it also runs the risk of oversimplification and misframing. a more subtle implication of the significance of interacting constraints is that it calls for a close relationship between theoretical and empirical research.
the cerebral torque and directional asymmetry for hand use are correlates of the capacity for language in homo sapiens
Authors: crow timothy j.
Published: October 2005

the claim of consistent hemispheric specialisations across classes of chordates is undermined by the absence of population-based directional asymmetry of paw/hand use in rodents and primates. no homologue of the cerebral torque from right frontal to left occipital has been established in a nonhuman species. the null hypothesis that the torque is the sapiens-specific neural basis of language has not been disproved.
a synthesis of many levels of constraints as a modern view of development
Authors: harter derek , lu shulan
Published: October 2005

the debate of nativisim versus empiricism is over the relative importance of evolutionary versus ontogenetic mechanisms. this is mostly seen today as a false dichotomy. the synthesis of these positions provides a modern viewpoint of grounded category formation. this combined view places equal importance on feedback between these levels in guiding development, and is more appropriately compared to culturalist positions.
darwin's legacy and the evolution of cerebral asymmetries
Authors: güntürkün onur
Published: October 2005

vallortigara & rogers (v&r) assume that the alignment of escape responses in gregarious species is the central evolutionary organizer of a wide range of cerebral asymmetries. although it is indeed likely that the benefits of a population asymmetry in social species outweigh its costs, it is hard to see (a) why the population should not oscillate between two subgroups with mirror-image asymmetries, (b) why solitary animals should keep their inherited population asymmetry despite a resulting fitness reduction, and (c) and why so many vertebrate species have comparable cerebral asymmetries.
the left-side bias for holding human infants: an everyday directional asymmetry in the natural environment
Authors: harris lauren julius , almerigi jason b.
Published: October 2005

to vallortigara & rogers's (v&r's) evidence of everyday directional asymmetries in the natural environment of a variety of species, we offer one more example for human beings. it is the bias for holding an infant on the left side, and it illustrates several themes in the target article.
the next frontier: moral heuristics and the treatment of animals
Authors: herzog harold a. , burghardt gordon m.
Published: October 2005

heuristics provide insight into the inconsistencies that characterize thinking related to the use of nonhuman animals. we examine paradoxes in judgments and policy related to the treatment of animals in science from a moral intuition perspective. sunstein's ideas are consistent with a model of animal-related ethical evaluation we developed twenty-five years ago and which appear readily formulated as moral heuristics.