bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mapped infinite elements for three‐dimensional multi‐region boundary element analysis
Authors: Moser W. , Duenser Ch. , Beer G. 
Published: September 2004

AbstractA formulation for an infinite boundary element (BE) is presented, which allows the modelling of infinite surfaces. The concept is that the finite surface is mapped to an infinite surface using special mapping functions. Using such mapping functions together with linear and quadratic interpolation for the displacements and the tractions, respectively, the desired decay behaviour can be modelled. The implementation of the proposed infinite elements becomes straightforward, since the Cauchy principal value, as well as the free term, are evaluated for the finite and infinite BEs with exactly the same techniques. The element developed can be used in a multi‐region BE analysis of piecewise homogeneous domains, or for domains with joints and faults. The accuracy of the element is tested on some benchmark problems. Finally, a practical application in tunnelling is shown. Copyright © 2004 John Wiley & Sons, Ltd.
Finite element formulations of strain gradient theory for microstructures and the C0–1 patch test
Authors: Soh Ai‐Kah , Wanji Chen 
Published: September 2004

AbstractBased on finite element formulations for the strain gradient theory of microstructures, a convergence criterion for the C0–1 patch test is introduced, and a new approach to devise strain gradient finite elements that can pass the C0–1 patch test is proposed. The displacement functions of several plane triangular elements, which satisfy the C0 continuity and weak C1 continuity conditions are evaluated by the C0–1 patch test. The difference between the proposed C0–1 patch test and the C0 constant stress and C1 constant curvature patch tests is elucidated.An 18‐DOF plane strain gradient triangular element (RCT9+RT9), which passes the C0–1 patch test and has no spurious zero energy modes, is proposed. Numerical examples are employed to examine the performance of the proposed element by carrying out the C0–1 patch test and eigenvalue test. The proposed element is found to be without spurious zero energy modes, and it possesses higher accuracy compared with other strain gradient elements. Copyright © 2004 John Wiley & Sons, Ltd.
A posteriori error estimates for the mixed finite element method with Lagrange multipliers
Authors: Gatica Gabriel N. , Maischak Matthias 
Published: September 2004

AbstractWe consider the mixed finite element method with Lagrange multipliers as applied to second‐order elliptic equations in divergence form with mixed boundary conditions. The corresponding Galerkin scheme is defined by using Raviart‐Thomas spaces. We develop a posteriori error analyses yielding a reliable and efficient estimate based on residuals, and a reliable and quasi‐efficient estimate based on local problems, respectively. Several numerical results illustrate the suitability of these a posteriori estimates for the adaptive computation of the discrete solutions. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
An immersed interface method for anisotropic elliptic problems on irregular domains in 2D
Authors: Dumett Miguel A. , Keener James P. 
Published: September 2004

AbstractThis work is a generalization of the immersed interface method for discretization of a nondiagonal anisotropic Laplacian in 2D. This first‐order discretization scheme enforces weakly diagonal dominance of the numerical scheme whenever possible. A necessary and sufficient condition depending on the mesh size h for the existence of this scheme at an interior grid point is found in terms of the anisotropy matrix. A linear programming approach is introduced for finding the weights of the schemes. The method is tested with a parametrized family of anisotropic Poisson equations. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Examples of successful architectural integration of PV: Germany
Authors: Hagemann Ingo B. 
Published: September 2004

AbstractIn Germany building‐integrated photovoltaics (BIPV) are developing rapidly, and much progress has been achieved in the past five years. BIPV can be used today in different ways on both existing and new buildings. Architects and designers are discovering BIPV. With the help of custom‐made products available on the German market they are beginning to explore the technical limits of an aesthetic and structural integration of PV in buildings. As a result some exciting high‐profile building projects with PV have been built, for example, the small service pavilion Meereslauschen in Steinhude or the new headquarters building of the Wood Trade Association in Munich. These projects show that the use of PV is very varied and offers opportunities for creative architects. However non‐technical problems still need to be solved to allow a meaningful and widespread application of PV in the built environment. To decrease costs it is essential to develop further standard BIPV components. The aim of such developments should be to replace standard PV modules by products in which PV and structural building elements are melded into one design and structural unit. Copyright © 2004 John Wiley & Sons, Ltd.
PV on noise barriers
Authors: Nordmann Thomas , Clavadetscher Luzi 
Published: September 2004

AbstractPV on noise barriers has been around for 14 years. During this time considerable progress has been achieved not only on the PV module technology, but also in the construction of photovoltaic noise barriers (PVNB). The first plant was built in Switzerland in 1989; at present there are numerous plants with a total documented power of about 850 kWp in operation in Europe. This paper gives a short overview on the progress and state of the art of PVNB in Europe. Copyright © 2004 John Wiley & Sons, Ltd.
Examples of successful architectural integration of PV: Australia
Authors: Prasad Deo K. , Snow Mark 
Published: September 2004

AbstractAn abundance of solar energy resources in Australia and the application of remote area power systems (RAPS) are well known. Numerous locations, isolated from the electricity grid have benefited from photovoltaic energy supply with economic justification and provided a platform from which the scientific knowledge and expertise has grown over 30 years. Of current global relevance is the transition and growth of photovoltaic applications in the urban environment through building‐integrated PV (BiPV) and its use as a clever building material. Energy market dynamics in Australia and low‐priced fossil fuels limit the present market potential for BiPV. Showcase projects and government programmes have provided the much needed impetus to develop and introduce BiPV products to the building industry and, importantly, experiment with architectural design solutions that strive to offer added benefits to the built environment. This paper discusses examples of successful integration of PV and lessons learnt in the process. The importance of high ambient temperature conditions, thermal performance and smart electrical configurations to minimise shading influences, are considered to be particularly relevant. Copyright © 2004 John Wiley & Sons, Ltd.
Change of memory formation according to STDP in a continuous‐time neural network model
Authors: Watanabe Hidenori , Watanabe Masataka , Aihara Kazuyuki , Kondo Shunsuke 
Published: September 2004

AbstractGerstner and colleagues have proposed a learning rule in which the incrementation of synaptic weight is adjusted according to the time difference between neuron firing and spike arrival. In this study, a continuous‐time associative memory model is constructed by using a learning rule based on that idea, and the functions of the learning rule are investigated. First, a continuous‐time associative memory model is constructed on the basis of the learning rule in continuous time, in which the neuron can store memory as the synchronous firing dynamics of the neuron. A result is presented in which multiple memory patterns can be recalled simultaneously under the proposed model. Then, using the proposed learning rule, an attempt is made to compose a nesting structure formed by arbitrary memory patterns. Based on the above series of results, it is shown that the learning rule has the function of modifying the memory storage structure according to changes in the environment. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(12): 57–66, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10324
Design of a graphical history browser with Undo facility, and visual search analysis
Authors: Masuda Hisanori , Imamiya Atsumi 
Published: September 2004

AbstractExisting interactive systems provide the user with various tools to make the system recover from an error. Most direct‐manipulation graphical interfaces, for example, include an Undo/Redo tool, by which the user can cancel an erroneous action. However, they are only simple mechanisms or provide only a command history represented by a text list, from which it is difficult to find the command or state desired by the user. The purpose of this paper is to realize an interface which helps the user to utilize Undo selectively and easily, to discuss the design and implementation of a graphical history browser, and to describe a visual search experiment and analysis utilizing the history browser. The history browser includes the following functions. (1) Operation commands for each figure object are grouped. (2) The graphical history composed of snapshots of the operation screen is provided as a flip comic. In order to examine the effectiveness of command grouping, an experimental comparison is made with the conventional techniques without grouping. As a result, the effectiveness of command grouping for the experimental task is shown from the viewpoints of task execution time and subjective evaluation by the subject. In addition, in order to investigate the features of the history browser and the behavior of the user in history search, a task experiment is performed in which two methods of history display—display of the history browser and parallel displays of two figures—are used to search visually for the difference between the two figures. The task execution time, the error, and the eye‐movement data of the subject are analyzed, and it is shown that by utilizing the flip function of the history browser, the user can find differences quickly and exactly from the specified stimulus display. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(12): 32–45, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10431
Cost‐effective compilation techniques for Java Just‐in‐Time compilers
Authors: Shudo Kazuyuki , Sekiguchi Satoshi , Muraoka Yoichi 
Published: September 2004

AbstractJava Just‐in‐Time compilers must satisfy a number of requirements in conflict with each other. Effective execution of generated code is not the only requirement: compilation time, memory consumption, and compliance with the Java Virtual Machine specification are also important. We have developed a Java Just‐in‐Time compiler that requires relatively little implementation labor. Another important objective is developing an adequate base of follow‐up research utilizing this compiler. The proposed compilation techniques involve low compilation cost and low development cost. This paper also describes the optimization methods implemented in the compiler, for instance, instruction folding, exception handling with signals, and code patching. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(12): 10–24, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10564
Decay for travelling waves in the Gross–Pitaevskii equation
Authors: Gravejat Philippe 
Published: September 2004

We study the limit at infinity of the travelling waves of finite energy in the Gross–Pitaevskii equation in dimension larger than two: their uniform convergence to a constant of modulus one and their asymptotic decay.

Résumé
Nous étudions la limite à l’infini des ondes progressives d’énergie finie pour les équations de Gross–Pitaevskii en dimension supérieure ou égale à deux : leur convergence uniforme vers une constante de module un et leur comportement asymptotique.
Regularity for degenerate elliptic problems via p-harmonic approximation
Authors: Duzaar Frank , Mingione Giuseppe 
Published: September 2004

We introduce a new method to prove regularity of solutions to certain degenerate elliptic problems. The method is based on the

p

-harmonic approximation lemma, recently proved by the authors in [F. Duzaar, G. Mingione, The

p

-harmonic approximation and the regularity of

p

-harmonic maps, Calc. Var., 2004, in press], that allows to approximate functions with

p

-harmonic functions in the same way as the classical harmonic approximation lemma (going back to De Giorgi) does via harmonic functions. The method presented here also bypasses certain difficulties arising when treating some degenerate and singular problems with a weak structure, such as degenerate and singular quasiconvex integrals, and provides transparent and elementary proofs.

Résumé

Nous introduisons une nouvelle méthode pour prouver la régularité des solutions de certains problèmes elliptiques dégénérés. La méthode se base sur le lemme d’approximation

p

-harmonique (prouvé récemment par les auteurs dans [F. Duzaar, G. Mingione, The

p

-harmonic approximation and the regularity of

p

-harmonic maps, Preprint Dip. Mat. Univ. Parma, 2002] qui permet d’approximer des fonctions par des fonctions

p

-harmoniques de la même façon où le lemme d’approximation harmonique classique (qui rémonte à De Giorgi) le permettait avec des fonctions harmoniques. Le méthode présentée ici évite aussi des difficultés qui apparaissent dans certains problèmes dégénérés et singuliers avec structure faible, comme des intégrales quasiconvexes dégénérés et singuliers, et fournit des preuves élémentaires et transparentes.
Positive solutions of slightly supercritical elliptic equations in symmetric domains
Authors: Molle Riccardo , Passaseo Donato 
Published: September 2004

This paper deals with existence and multiplicity of solutions for problem

P(ε,Ω)

below, which concentrate and blow-up at a finite number of points as

ε→0

. We give sufficient conditions on

Ω

which guarantee that the following property holds: there exists

\bar k(Ω)

such that, for each

k⩾
\bar k(Ω)

, problem

P(ε,Ω)

, for

ε>0

small enough, has at least one solution blowing up as

ε→0

at exactly

k

points. Exploiting the properties of the Green and Robin functions, we also prove that the blow up points approach the boundary of

Ω

as

k→∞

. Moreover we present some examples which show that

P(ε,Ω)

may have

k

-spike solutions of this type also when

Ω

is a contractible domain, not necessarily close to domains with nontrivial topology and, for

ε>0

small and k large enough, even when it is very close to star-shaped domains.

Résumé

Nous démontrons que, si le domaine

Ω

satisfait certaines conditions, le problème

P(ε,Ω)

ci-dessous, pour

ε>0

suffisamment petit et

k

grand, admet des solutions qui pour

ε→0

se concentrent et explosent exactement en

k

points. Nous prouvons aussi que le point de concentration s’approche du bord de

Ω

quand

k→∞

et que le nombre de solutions est arbitrairement grand pourvu que

ε

soit suffisamment petit. La méthode de démonstration repose sur les propriétés des fonctions de Green et de Robin du laplacien sur

Ω

. De plus nous donnons des exemples qui montrent que parmi les ouverts bornés

Ω

qui satisfont nos conditions, il y en a aussi de contractiles, qui ne sont pas de perturbations d’ouverts non contractiles et peuvent même être arbitrairement proches de domaines étoilés.
Existence and nonexistence results for anisotropic quasilinear elliptic equations
Authors: Fragalà Ilaria , Gazzola Filippo , Kawohl Bernd 
Published: September 2004

We consider a new class of quasilinear elliptic equations with a power-like reaction term: the differential operator weights partial derivatives with different powers, so that the underlying functional-analytic framework involves anisotropic Sobolev spaces. Critical exponents for embeddings of these spaces into

L^q

have two distinct expressions according to whether the anisotropy is “concentrated” or “spread out”. Existence results in the subcritical case are influenced by this phenomenon. On the other hand, nonexistence results are obtained in the at least critical case in domains with a geometric property which modifies the standard notion of starshapedness.

Résumé

Nous considérons une nouvelle classe d’équations elliptiques quasilinéaires avec un terme de réaction de type puissance : les dérivées partielles ont des puissances différentes dans l’opérateur différentiel, de façon que l’espace fonctionnel naturel devient un espace de Sobolev anisotrope. Les exposants critiques pour les injections de ces espaces dans

L^q

ont des expressions différentes qui dépendent de la “concentration” de l’anisotropie. Nos résultats d’existence dans le cas sous-critique sont influencés par ce phenomène. D’autre part, nos résultats de non existence dans le cas critique et sur-critique sont obtenus dans des domaines ayant une propriété qui modifie la notion usuelle d’ensemble étoilé.
Optimal bundling of transmembrane helices using sparse distance constraints
Authors: Sale Ken , Faulon Jean‐Loup , Gray Genetha A. , Schoeniger Joseph S. , Young Malin M. 
Published: September 2004

AbstractWe present a two‐step approach to modeling the transmembrane spanning helical bundles of integral membrane proteins using only sparse distance constraints, such as those derived from chemical cross‐linking, dipolar EPR and FRET experiments. In Step 1, using an algorithm, we developed, the conformational space of membrane protein folds matching a set of distance constraints is explored to provide initial structures for local conformational searches. In Step 2, these structures refined against a custom penalty function that incorporates both measures derived from statistical analysis of solved membrane protein structures and distance constraints obtained from experiments. We begin by describing the statistical analysis of the solved membrane protein structures from which the theoretical portion of the penalty function was derived. We then describe the penalty function, and, using a set of six test cases, demonstrate that it is capable of distinguishing helical bundles that are close to the native bundle from those that are far from the native bundle. Finally, using a set of only 27 distance constraints extracted from the literature, we show that our method successfully recovers the structure of dark‐adapted rhodopsin to within 3.2 Å of the crystal structure.
Simulating evolution by gene duplication of protein features that require multiple amino acid residues
Authors: Behe Michael J. , Snoke David W. 
Published: September 2004

AbstractGene duplication is thought to be a major source of evolutionary innovation because it allows one copy of a gene to mutate and explore genetic space while the other copy continues to fulfill the original function. Models of the process often implicitly assume that a single mutation to the duplicated gene can confer a new selectable property. Yet some protein features, such as disulfide bonds or ligand binding sites, require the participation of two or more amino acid residues, which could require several mutations. Here we model the evolution of such protein features by what we consider to be the conceptually simplest route—point mutation in duplicated genes. We show that for very large population sizes N, where at steady state in the absence of selection the population would be expected to contain one or more duplicated alleles coding for the feature, the time to fixation in the population hovers near the inverse of the point mutation rate, and varies sluggishly with the λth root of 1/N, where λ is the number of nucleotide positions that must be mutated to produce the feature. At smaller population sizes, the time to fixation varies linearly with 1/N and exceeds the inverse of the point mutation rate. We conclude that, in general, to be fixed in 108 generations, the production of novel protein features that require the participation of two or more amino acid residues simply by multiple point mutations in duplicated genes would entail population sizes of no less than 109.
Crystallographic identification of Ca2+ and Sr2+ coordination sites in synaptotagmin I C2B domain
Authors: Cheng Yuan , Sequeira Sonia M. , Malinina Lucy , Tereshko Valentina , Söllner Thomas H. , Patel Dinshaw J. 
Published: September 2004

AbstractSynaptotagmin I has two tandem Ca2+‐binding C2 domains, which are essential for fast synchronous synaptic transmission in the central nervous system. We have solved four crystal structures of the C2B domain, one of them in the cation‐free form at 1.50 Å resolution, two in the Ca2+‐bound form at 1.04 Å (two bound Ca2+ ions) and 1.65 Å (three bound Ca2+ ions) resolution and one in the Sr2+‐bound form at 1.18 Å (one bound Sr2+ ion) resolution. The side chains of four highly conserved aspartic acids (D303, D309, D363, and D365) and two main chain oxygens (M302:O and Y364:O), together with water molecules, are in direct contact with two bound Ca2+ ions (sites 1 and 2). At higher Ca2+ concentrations, the side chain of N333 rotates and cooperates with D309 to generate a third Ca2+ coordination site (site 3). Divalent cation binding sites 1 and 2 in the C2B domain were previously identified from NMR NOE patterns and titration studies, supplemented by site‐directed mutation analysis. One difference between the crystal and NMR studies involves D371, which is not involved in coordination with any of the identified Ca2+ sites in the crystal structures, while it is coordinated to Ca2+ in site 2 in the NMR structure. In the presence of Sr2+, which is also capable of triggering exocytosis, but with lower efficiency, only one cation binding site (site 1) was occupied in the crystallographic structure.
Quantification of helix–helix binding affinities in micelles and lipid bilayers
Authors: Lomize Andrei L. , Pogozheva I.D. , Mosberg H.I. 
Published: September 2004

AbstractA theoretical approach for estimating association free energies of α‐helices in nonpolar media has been developed. The parameters of energy functions have been derived from ΔΔG values of mutants in water‐soluble proteins and partitioning of organic solutes between water and nonpolar solvents. The proposed approach was verified successfully against three sets of published data: (1) dissociation constants of α‐helical oligomers formed by 27 hydrophobic peptides; (2) stabilities of 22 bacteriorhodopsin mutants, and (3) protein‐ligand binding affinities in aqueous solution. It has been found that coalescence of helices is driven exclusively by van der Waals interactions and H‐bonds, whereas the principal destabilizing contributions are represented by side‐chain conformational entropy and transfer energy of atoms from a detergent or lipid to the protein interior. Electrostatic interactions of α‐helices were relatively weak but important for reproducing the experimental data. Immobilization free energy, which originates from restricting rotational and translational rigid‐body movements of molecules during their association, was found to be less than 1 kcal/mole. The energetics of amino acid substitutions in bacteriorhodopsin was complicated by specific binding of lipid and water molecules to cavities created in certain mutants.