bluuebunny/crossref_metadata_2025_split huggingface dataset:
JaMP: an implementation of OpenMP for a Java DSM
Authors: Klemm Michael , Bezold Matthias , Veldema Ronald , Philippsen Michael 
Published: April 2007

AbstractAlthough OpenMP is a widely agreed‐upon standard for the C/C++ and Fortran programming languages for the semi‐automatic parallelization of programs for shared memory machines, not much has been done on the binding of OpenMP to Java that targets clusters with distributed memory. This paper presents three major contributions: (1) JaMP is an adaptation of the OpenMP standard to Java that implements a large subset of the OpenMP specification with an expressiveness comparable to that of OpenMP; (2) we suggest a set of extensions that allow a better integration of OpenMP into the Java language; (3) we present our prototype implementation of JaMP in the research compiler Jackal, a software‐based distributed shared memory implementation for Java. We evaluate the performance of JaMP with a set of micro‐benchmarks and with OpenMP versions of the parallel Java Grande Forum (JGF) benchmarks. The micro‐benchmarks show that OpenMP for Java can be implemented without much overhead. The JGF benchmarks achieve a good speed‐up of 5–8 on eight nodes. Copyright © 2007 John Wiley & Sons, Ltd.
Parallelization and scalability of a spectral element channel flow solver for incompressible Navier–Stokes equations
Authors: Hamman C. W. , Kirby R. M. , Berzins M. 
Published: April 2007

AbstractDirect numerical simulation (DNS) of turbulent flows is widely recognized to demand fine spatial meshes, small timesteps, and very long runtimes to properly resolve the flow field. To overcome these limitations, most DNS is performed on supercomputing machines. With the rapid development of terascale (and, eventually, petascale) computing on thousands of processors, it has become imperative to consider the development of DNS algorithms and parallelization methods that are capable of fully exploiting these massively parallel machines. A highly parallelizable algorithm for the simulation of turbulent channel flow that allows for efficient scaling on several thousand processors is presented. A model that accurately predicts the performance of the algorithm is developed and compared with experimental data. The results demonstrate that the proposed numerical algorithm is capable of scaling well on petascale computing machines and thus will allow for the development and analysis of high Reynolds number channel flows. Copyright © 2007 John Wiley & Sons, Ltd.
Efficient parallelization of the iterative solution of a coupled fluid–structure interaction problem
Authors: Hughes Martyn D. , Chen Ke 
Published: April 2007

AbstractIn this paper we consider the parallelization of the generation and iterative solution of coupled linear systems modelling the interaction of an acoustic field in a fluid medium with an elastic structure immersed in the fluid. The particular case studied is that of a hollow steel sphere in water. The aim of the work is to speed up the generation and solution of the systems. We describe the methods used, which involve special sparse storage arrangements and a novel application of a sparse approximate inverse preconditioning technique, and present results showing that the methods are very effective in terms of speeding up the generation and iterative solution of the systems. Copyright © 2007 John Wiley & Sons, Ltd.
Interaction of HLA‐B27 homodimers with KIR3DL1 and KIR3DL2, unlike HLA‐B27 heterotrimers, is independent of the sequence of bound peptide
Authors: Kollnberger Simon , Chan Antoni , Sun Mei‐Yi , Ye Chen Li , Wright Cynthia , di Gleria Kati , McMichael Andrew , Bowness Paul 
Published: April 2007

AbstractHLA‐B27 can form beta‐2 microglobulin (β2m)‐associated heterotrimers (HLA‐B27) and β2m‐free homodimers (B272). Here, we study the role of complexed peptide in the interaction of these forms of B27 with the killer cell immunoglobulin (Ig)‐like receptors KIR3DL1 and KIR3DL2 and with Ig‐like transcripts LILRB1 and LILRB2. HLA‐B27 tetramers complexed with three of five different naturally processed self peptides and three of seven pathogen‐derived epitopes bound to KIR3DL1‐expressing transfectants and NK cells. Heterotrimeric complexes containing peptides with charged amino acids at position 8 did not bind to KIR3DL1; however, studies with analogue peptides demonstrated that these are not the only peptide residues involved in binding. KIR3DL1 ligation by HLA‐B27 inhibited NK cell IFN‐γ production in a peptide‐dependent fashion. B27 but not HLA‐A2, B7 or B57 heavy chains formed homodimers in the presence of peptide epitopes. B272 bound to KIR3DL1, KIR3DL2 and LILRB2 but not LILRB1. KIR3DL2 ligation by B272 inhibited NK and T cell IFN‐γ production. By contrast with HLA heterotrimers, B272 binding to KIR did not depend on the sequence of the bound peptide. Differences in KIR binding to classical HLA and B272 could be involved in the pathogenesis of spondyloarthritis.
GITR/GITRL: More than an effector T cell co‐stimulatory system
Authors: Nocentini Giuseppe , Ronchetti Simona , Cuzzocrea Salvatore , Riccardi Carlo 
Published: April 2007

AbstractGlucocorticoid‐induced TNFR‐related protein (GITR) is a member of the TNFR superfamily, expressed in several cells and tissues including T lymphocytes, NK cells and antigen‐presenting cells (APC). GITR activation, upon interaction with its ligand (GITRL), functions as a co‐activating signal. GITRL is mainly expressed on APC and GITR/GITRL interaction is important for the development of immune response. This review summarizes recent results about the GITR/GITRL system, focusing on the interplay between APC, effector and regulatory T cells.
The flaminio obelisk in Rome: Vibrational characteristics as part of preservation efforts
Authors: Bongiovanni G. , Çelebi M. , Clemente P. 
Published: April 2007

AbstractThe purpose of the paper is to study the vibrational characteristics of the Flaminio Obelisk in Rome as part of general studies being performed for preservation purposes. The scope of the paper is limited to dynamic analysis using a finite element model and comparison of the results with those from the measured response to forced vibrations. The state of preservation of the monument is described as well as the sonic method used to evaluate the integrity of the sections. The results of the sonic tests are used to determine reductions in the cross‐sectional properties. A stick model including two rotational frequency independent soil springs at the basement level of the obelisk is developed. A good agreement between the numerical and the experimental results is obtained for the natural frequencies and for the modal shapes. A response spectrum and stress analysis according to the Italian Seismic Code is performed considering and evaluating the degraded characteristics of sections.
Soil‐structure interaction effects on strong motion accelerograms recorded on instrument shelters
Authors: Luco J. E. , Anderson J. G. , Georgevich M. 
Published: April 2007

AbstractThe distortions of earthquake ground motions recorded in small instrument shelters as a result of soil‐structure interaction effects are investigated by means of a theoretical parametric study. A total of 12 foundation geometries varying in basal radius, embedment depth and extension above the ground surface and a number of soil profiles including uniform and layered soil models were considered. The results obtained show significant amplification and deamplification of the free‐field ground motion for sufficiently soft soils (β<200 m/sec) and sufficiently high frequencies (f>20 Hz).
Estimation of structural parameters in time domain: A substructure approach
Authors: Koh Chan Ghee , See Lin Ming , Balendra Thambirajah 
Published: April 2007

AbstractA substructure approach is used to estimate the stiffness and damping coefficients of structures from measurement of dynamic responses. The structures are decomposed into smaller subsystems for which state and observation equations are formulated and solved by the method of extended Kalman filter with a weighted global iteration algorithm. Substructural identification methods with and without overlapping members are proposed. In both methods, the convergence of the structural parameters to the optimal values is improved significantly with less computation time as compared to a complete structural approach. Numerical simulation studies are performed for three types of structures, namely a shear building, a plane frame building and a plane truss bridge. The effects of measurement noise and response observations required for identification of system parameters are also investigated.
Seismic ground motion simulations from a class of spatial variability models
Authors: Zerva Aspasia 
Published: April 2007

AbstractAn improved version of the spectral representation method (References 12–14) for the generation of simulations of random processes and random fields by means of the Fast Fourier Transform algorithm is developed. The new formulation produces simulations that are ergodic in the mean without any restricting assumptions at the origin of the spectra and leads to a faster convergence rate of the stochastic characteristics of the simulations to those of the random field. As an example of the methodology, simulations in space and time based on a spatial variability model for the seismic ground motions are generated.
Application of FE‐BE‐IBE coupling to dynamic interaction between alluvial soil and rock canyons
Authors: Chuhan Zhang , Pekau O. A. , Feng Jin 
Published: April 2007

AbstractA method of coupling finite elements (FE), boundary elements (BE) and infinite boundary elements (IBE) in the frequency domain is presented for wave propagation and soil‐structure interaction problems. The procedure has the advantage of being suitable for considering non‐homogeneous materials in the near region and the radiation condition at the far field. At the same time, the displacement field on the traction free boundary of the semi‐plane is simulated by the IBE rather than by additional discretization of the ground surface as is required in the normal BE procedure. Verification examples show that excellent accuracy is achieved compared with the results by Wong18 who used the generalized inverse method. Finally, the proposed procedure is employed to obtain the response of a semi‐elliptical rock canyon‐alluvial deposit under seismic P and SV waves. Amplification behaviour due to the alluvial soil is observed to be significant for the given geometric dimensions of the canyon and the mechanical properties of the media under the excitation of the El Centro and Parkfield earthquakes.
Active control of the seismic response of structures by combined use of base isolation and absorbing boundaries
Authors: Luco J. E. , Mita A. , Wong H. L. 
Published: April 2007

AbstractThe relative advantages of several control strategies to reduce the seismic response of multi‐storey structures are studied. The strategies involve the separate or combined use of passive base isolation mechanisms and active control forces. The base isolation mechanism is modelled as an equivalent linear soft storey with high damping. The active control forces are selected so that an absorbing boundary is obtained at the top of the structure and non‐reflecting or reflecting boundaries are obtained at the base of the building. It is found that the best results are obtained when a passive base isolation system is combined with an active absorbing boundary placed at the top of the building. However, the incremental gains resulting from adding a base isolation system to a structure already controlled by a roof‐top active absorbing boundary are significant only for relatively soft base isolation systems. Also, the incremental gains appear to decrease as the number of storeys of the structure increases.
Site‐dependent models of earthquake ground motion
Authors: O'connor Jennifer M. , Ellingwood Bruce R. 
Published: April 2007

AbstractRandom vibration analyses of structural systems subjected to seismic loading are dependent upon the characterization of earthquake ground motion as a stochastic process. The response of structural systems to earthquakes is dependent strongly on the local geological conditions, which should be incorporated into seismological models of ground motion. In the study presented herein, three previously developed ground‐motion models are adapted to incorporate site‐dependent characteristics. Records obtained from two recording stations in California are used as a basis for the ground‐motion models. Single‐degree‐of‐freedom (SDOF) oscillators are subjected to ensembles of accelerograms generated from these models, and both elastic and inelastic response are considered. Response statistics are compared to those generated by the analysis of structural response to ensembles of recorded motion from the two sites. The important features of the ground motion for effective reproduction of response statistics are identified, and observations are made on the sensitivity of specific response parameters to site‐dependent characteristics of the ground motion.
Verification of two‐dimensional non‐linear analysis of sand‐structure system by examining the results of the shaking‐table test
Authors: Ohtsuki Akira , Hirota Masanori , Ishimura Kikuo , Yokoyama Kazutomo , Fukutake Kiyoshi 
Published: April 2007

AbstractThe verification of a two‐dimensional non‐linear analysis based on a hybrid constitutive model, which consists of the Ramberg‐Osgood model extended to two‐dimensional problems and a dilatancy model, is discussed through a comparison of the shaking‐table test results for a one‐storey structure standing on a dry sandy deposit with those for the same on a saturated sandy deposit. Since the relationships G vs. γ and h vs. γ for shear strains of 10−5−10−3 can be obtained accurately by an inversion analysis of the resonance curve of the sandy deposit the proposed non‐linear method can represent well the observed non‐linear response of the dry or the saturated sandy deposit including the structure. This method, however, should be applied carefully to assess the response of a soil‐structure system when the three‐dimensional interaction affects significantly the response of the model. An equivalent linear analysis using a sway‐rocking model is applied to simulate the non‐linear ground motion including the three‐dimensional interaction, and it is found that the sway‐rocking model can also represent well the non‐linear response of the system.
Reliability‐based design of R/C water tank structures under seismic action
Authors: Möller Oscar , Rubinstein Marcelo 
Published: April 2007

AbstractBased on a reliability level 2 method, a procedure is proposed to design reinforced concrete structures for elevated tanks subjected to seismic action, with a specified probability of failure in a 50‐year design life.To evaluate the probability of failure the ultimate limit state is obtained when the top column displacement demanded by the earthquake, a random variable, reaches the allowable displacement, which is here treated as deterministic.The seismic action is characterized probabilistically by the power spectral density function of the ground acceleration, which is obtained from a design spectrum. The strength and ductility of an annular column section of confined reinforced concrete for cyclic loads are evaluated with design aids.Design charts are made for a given tank capacity and specified seismic zone that allow one to choose different combinations of strength, stiffness and ductility for the same tolerable probability of failure. A step by step method is suggested for the design of the annular column section, choosing finally the most convenient design. The advantage of this methodology is shown through a numerical example.
Response spectrum method for multi‐support seismic excitations
Authors: Kiureghian Armen Der , Neuenhofer Ansgar 
Published: April 2007

AbstractA new response spectrum method is developed for seismic analysis of linear multi‐degree‐of‐freedom, multiply supported structures subjected to spatially varying ground motions. Variations of the ground motion due to wave passage, loss of coherency with distance and variation of local soil conditions are included. The method is based on fundamental principles of random vibration theory and properly accounts for the effects of correlation between the support motions as well as between the modes of vibration of the structure.
Analytical expressions for three different modes in harmonic motion of sliding structures
Authors: Iura Masashi , Matsui Kunihito , Kosaka Iku 
Published: April 2007

AbstractThe problem of response of sliding structures subjected to harmonic support motions is considered. The periodic motions, consisting of the three different modes, stick‐stick, stick‐slip and slip‐slip, are a significant part of the responses to harmonic excitations. Assuming the periodicity of the motion, the condition of the initiation of the slip‐slip motion is derived. Then analytical expressions for the occurrence of the periodic motions are obtained without integrating the equations of motion. The accuracy of the analytical expressions is confirmed by comparison with numerical results herein obtained. It is observed that the numerical results are sensitive to the starting and ending times of slip motions.
Damping and response measurement on A small‐scale model of A cable‐stayed bridge
Authors: Garevski Mihail A. , Severn Roy T. 
Published: April 2007

AbstractA small‐scale model of an existing cable‐stayed bridge has been designed and built. Hammer, sinusoidal and random signal tests have been performed to determine the dynamic characteristics of the model. An attempt has been made to evaluate the real effect of the vibration of stays upon system damping. Initial measurements have been performed for a model where there was no vibration of the stays because of the absence of appropriately scaled additional mass of these stays. In this way the effect of the cables was eliminated in damping measurement. During the second series of measurements appropriate mass has been added to the stays, causing them to take part in the vibration. The comparison of the measured damping of the model for each case makes possible the estimation of the effect of the stays upon the system damping. By using the shaking table, two types of seismic excitation were applied, with corresponding response quantities in the critical sections being measured. Good agreement between the analytical and the experimental results was achieved.
A three‐stage identification approach for hysteretic systems
Authors: Loh Chin‐Hsiung , Chung Sheng‐Tsai 
Published: April 2007

AbstractThis paper deals with the identification of the parameters of a smoothed hysteretic model which was proposed by Bouc and Wen with emphasis on restoring force hysteresis. The problem of estimating the parameters of this system on the basis of input‐output data, possibly noise corrupted, is considered. Through the application of various simulated time histories from the hysteretic model, a three‐stage systematic method of system identification was proposed. Four different methods of identification are arranged and conducted in this three‐stage system identification. The first stage, a sequential regressional analysis is used to identify the equivalent linear system from which elastic or inelastic response can be identified. The identified parameters can be used in the stage when the system is in elastic response. In the second stage, both time domain least‐squares method and Gauss‐Newton method are applied. The convergence of the Gauss‐Newton method can be guaranteed if the identified results from least‐squares method are adopted as the initial values for Gauss‐Newton method. In the third stage, the extended Kalman filtering technique is needed to identify the noise‐corrupt data. Application of this algorithm to a SDOF non‐deteriorating system is verified.
Propagation and amplification of seismic waves in 2‐D valleys excited by obliquely incident P‐ and SV‐waves
Authors: Papageorgiou Apostolos S. , Kim Jaekwan 
Published: April 2007

AbstractThe seismic motion in sediment‐filled valleys due to incident SH‐waves has been studied exhaustively. However, the response of such geologic structures to incident SV‐ and P‐waves has not been studied as thoroughly. The response of a 2‐D model of the valley of Caracas, Venezuela—a NS cross‐section through the Palos Grandes district—to incident plane SV‐ and P‐waves is investigated using the discrete wave number boundary element method. It is observed that the differences in the predictions of the 1‐D and 2‐D models are more pronounced for SV‐waves than for SH‐waves, especially when SV‐waves are incident at (or near) the critical angle ic. The valley responds very strongly to the horizontally propagating P‐wave (SP‐wave) which is induced when SV‐waves, incident at the critical angle, interact with the free surface of the half‐space. However, the SP‐wave, being a wave diffracted at a boundary, is likely to be sensitive to impedance contrasts, to the presence of other interfaces in the medium, and to the topography surrounding the valley. These aspects of the problem need further investigation.
Cone models for a soil layer on a flexible rock half‐space
Authors: Wolf John P. , Meek Jethro W. 
Published: April 2007

AbstractA modified truncated cone model is used to calculate approximately the dynamic response of a disk on the surface of a soil layer resting on flexible rock. The procedure is analogous to that for a layer on rigid rock, the only modification being that the reflection coefficient —α at the layer–rock interface is no longer equal to −1. The modified value of α can be determined straightforwardly by considering one‐dimensional wave propagation along the cone. The low‐ and high‐frequency limits lead to a frequency‐independent α, which allows the dynamic analysis to be performed directly in the familiar time domain. This cone represents a wave pattern with amplitude decay and also incorporates the reflection at the free surface and the reflection‐refraction at the layer–rock interface. The results for the static stiffness of the disk are highly accurate for a wide range of geometrical and material properties of the layer and the rock. For the dynamic stiffness the agreement with the exact solution is satisfactory.
Performance of composite steel/concrete members under earthquake loading. Part I: Analytical model
Authors: Elnashai A. S. , Elghazouli A. Y. 
Published: April 2007

AbstractThis paper presents an advanced non‐linear model developed for the analysis of composite steel/concrete frame structures subjected to cyclic and dynamic loads. The formulation consists of beam‐column cubic finite elements accounting for geometric non‐linearities and material inelasticity. The non‐linear cyclic concrete model considers confinement effects and the constitutive relationship for steel includes the effect of local buckling and variable amplitude cyclic degradation. The model is calibrated and compared with experimental data from cyclic and pseudo‐dynamic tests conducted by the writers on a new ductile partially‐encased composite beam‐column. The accuracy and efficiency of the developed model are demonstrated through the correlation between the experimental results and analytical simulations. In a companion paper, the model is used to conduct parametric studies leading to important conclusions for ductility‐based earthquake‐resistant design.