bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mature DC from skin and skin‐draining LN retain the ability to acquire and efficiently present targeted antigen
Authors: Henri Sandrine , Siret Carole , Machy Patrick , Kissenpfennig Adrien , Malissen Bernard , Leserman Lee 
Published: April 2007

AbstractSkin‐draining LN contain several phenotypically distinguishable DC populations, which may be immature or mature. Mature DC are generally considered to have lost the capacity to acquire and present newly encountered Ag. Using antibody‐opsonized liposomes as Ag carriers, we show that mature DC purified from skin explants are able to efficiently capture liposomes, process Ag encapsulated within them and activate Ag‐specific CD4+ T cells. Explant DC from mice with Langerhans cells (LC) expressing the primate diphtheria toxin receptor that were exposed to diphtheria toxin in vivo presented Ag as well as explant DC from wild‐type mice, indicating that LC are not required and dermal DC are probably responsible for this presentation. We further show that all DC subtypes from LN that capture opsonized Ag are capable of cross‐presenting it to CD8+ T cells. Induction of additional maturation in vivo by LPS or treatment with double‐stranded RNA did not alter the Ag presentation capacity of the skin or LN DC subtypes. These results suggest that mature DC present in skin‐draining LN may play an important role in the induction of primary and/or secondary immune responses against Ag delivered to the LN that they take up by receptor‐mediated endocytosis.
Hereditary complement C7 deficiency in nine families: Subtotal C7 deficiency revisited
Authors: Rameix‐Welti Marie‐Anne , Régnier Catherine H. , Bienaimé Frank , Blouin Jacques , Schifferli Jurg , Fridman Wolf H. , Sautès‐Fridman Catherine , Frémeaux‐Bacchi Veronique 
Published: April 2007

AbstractDeficiencies in terminal complement components, including the component C7, are uncommon and associated with an increased risk of recurrent systemic neisserial infection. A total of 22 molecular defects have been reported in the C7 gene with both complete (C7Q0) and subtotal (C7SD) C7 deficiencies. In this study we report the molecular basis of nine new cases of C7 deficiencies that were characterized by exon‐specific sequence analysis. Seven different C7 gene mutations were identified corresponding to small deletions (n=2), splice site changes (n=1) and single base pair substitutions leading to nonsense (n=1) or missense (n=3) mutations. Altogether, three changes of the C7 gene (G357R, R499S and 5′ splice donor site of intron 16) account for half of the molecular defects which emphasize that a restricted number of molecular abnormalities are involved in this deficiency. We identified two patients with combined C7Q0/C7SD(R499S) and established the C7SD(R499S) frequency at about 1% in normal Caucasian population. We demonstrated that C7(R499S) mutant protein is retained in the endoplasmic reticulum whereas the wild‐type C7 is located in the Golgi apparatus. Our results provide evidence that R499S represents a loss‐of‐function polymorphism of C7 due to a defective folding of the protein.
Seismic response of rotating machines
Authors: Suarez L. E. , Singh M. P. , Rohanimanesh M. S. 
Published: April 2007

AbstractThe equations of motion of a rotor finite element subjected to six components of base excitation are developed by applying variational principles. The equations contain speed dependent gyroscopic terms, base rotation dependent parametric terms and several forcing function terms which depend upon the linear accelerations, rotational accelerations and a combination of linear and rotational velocities. To evaluate the importance of various terms, seismic response characteristics of a rotating machine subjected to simulated base excitations are studied. It is observed that even for strong rotational inputs the parametric terms in the equation of motion can be ignored without affecting the response. The rotational input terms in the forcing function, however, are quite important and can be ignored only when they are not very strong. Since the problematic parametric terms can be ignored, one can use a generalied modal analysis approach.
Behaviour of near‐source vertical and horizontal response spectra at smart‐1 array, Taiwan
Authors: Niazi M. , Bozorgnia Y. 
Published: April 2007

AbstractOver 700 accelerograms recorded from 12 earthquakes in northeast Taiwan have been analysed for investigating the behaviour of the vertical and horizontal peak and spectral ground motion in the near‐source region. Pseudo‐relative spectral velocities (PSV), at 5 per cent critical damping for 23 frequencies in the range of engineering interest have been subjected to non‐linear regression procedures in terms of magnitude and hypocentral distance. Predicted response spectra for several discrete distances and magnitudes are presented. The results show that the shape of response spectra for both vertical and horizontal components of ground motion is magnitude‐ as well as distance‐dependent.The 2/3 ratio of vertical to horizontal ground motion, commonly used in engineering applications, appears unconservative in the very near field for high frequency ground motion. However, it falls below 1/2 at distances greater than 50 km. The same ratio for peak ground velocity (PGV) and peak ground displacement (PGD) tends to increase with distance—the latter at a faster rate.
Dynamic pile‐soil‐pile interaction. Part II: Lateral and seismic response
Authors: Makris Nicos , Gazetas George 
Published: April 2007

AbstractA simplified three‐step procedure is proposed for estimating the dynamic interaction between two vertical piles, subjected either to lateral pile‐head loading or to vertically‐propagating seismic S‐waves. The starting point is the determination of the deflection profile of a solitary pile using any of the established methods available. Physically‐motivated approximations are then introduced for the wave field radiating from an oscillating pile and for the effect of this field on an adjacent pile. The procedure is applied in this paper to a flexible pile embedded in a homogeneous stratum. To obtain analytical closed‐form results for both pile‐head and seismic‐type loading pile‐soil and soil‐pile interaction are accounted for through a single dynamic Winkler model, with realistic frequency‐dependent ‘springs’ and ‘dashpots’. Final‐ and intermediate‐step results of the procedure compare favourably with those obtained using rigorous formulations for several pile group configurations. It is shown that, for a homogeneous stratum, pile‐to‐pile interaction effects are far more significant under head loading than under seismic excitation.
A shear design equation for ductile R/C members
Authors: Ichinose T. 
Published: April 2007

AbstractA design equation is proposed to prevent shear failure after flexural inelastic deformation. This equation is based on the truss‐strut model. Inelastic hinge rotation is assumed to reduce the effective strength of concrete and to increase the inclination of truss action inside hinge regions. The proposed equation is confirmed on the basis of existing experimental data. This equation is accepted in the 1990 Japanese Design Guidelines.
Optimal hybrid control of structures under earthquake excitation
Authors: Tadjbakhsh Iradj G. , Rofooei Fayaz 
Published: April 2007

AbstractOptimal control of base‐isolated and non‐base‐isolated buildings subjected to earthquake excitation is considered. The control force at any instant is determined on‐line through minimizing a quadratic time‐dependent performance index based on the total energy imparted to the structure and the control effect. This control algorithm is based upon the use of discrete actuators and sensors that exert the control force and monitor the response of the building. Having constant gain matrices makes this algorithm efficient and easy to implement. The effect of time delay on the efficiency of the algorithm is investigated. Comparisons have been made to demonstrate the effectiveness of the proposed method.
An investigation of earthquake induced pounding between adjacent buildings
Authors: Anagnostopoulos Stavros A. , Spiliopoulos Konstantinos V. 
Published: April 2007

AbstractThe response of adjacent buildings in city blocks to several strong earthquakes is analysed, taking into account the mutual collisions, or pounding, resulting from insufficient or non‐existing separation distances. The buildings are idealized as lumped‐mass, shear beam type, multi‐degree‐of‐freedom (MDOF) systems with bilinear force‐deformation characteristics and with bases supported on translational and rocking spring‐dashpots. Collisions between adjacent masses can occur at any level and are simulated by means of viscoelastic impact elements. Using five real earthquake motions the effects of the following factors are investigated: building configuration and relative size, seismic separation distance and impact element properties. It is found that pounding can cause high overstresses, mainly when the colliding buildings have significantly different heights, periods or masses. This suggests a possibility for introducing a set of conditions into the codes, combined with some special measures, as an alternative to the seismic separation requirement.
Empirical green's function corrected for source effect
Authors: Izutani Yasuo , Katagiri Fuyuki 
Published: April 2007

AbstractOne of the severe problems in the semi‐empirical method for the prediction of strong ground motions is that there is no objective criterion for choosing empirical Green's functions. It is undesirable that synthesized strong ground motions are affected by the source process of an earthquake whose record is adopted as an empirical Green's function. Through the analysis of strong motion accelerograms of two aftershocks of the 1983 Japan Sea earthquakes, it is found that characteristics of the accelerograms are dependent on the moment rate function derived from teleseismic observations. A procedure is presented for removing the effect of the source process from observed strong motion accelerograms. The thus obtained empirical Green's function expresses approximately the impulse response of the medium between the earthquake source and the observation site.
A new passive confinement model for the analysis of concrete structures subjected to cyclic and transient dynamic loading
Authors: Madas P. , Elnashai A. S. 
Published: April 2007

AbstractThe paper describes an analytical model for reinforced concrete members subjected to cyclic or transient dynamic loading. Model characterization is given in the context of a pseudo‐spatial description of the stress state. This comprises a procedure for calculating and continuously updating the transverse confinement stress for a given applied axial strain, thus accounting for the passive confinement which an element of concrete is subjected to within a structural member. Comparison with existing uniaxial models shows that the new formulation takes note of previously neglected effects, such as non‐coincident peaks of the steel and concrete stress‐strain curves, and Poisson's ratio variation during loading. Moreover, comparison with 3D concrete constitutive relationships indicates that the level of accuracy is comparable, whilst significant computing time saving is achieved by the new model. Model validation is confirmed by comparison with cyclic loading laboratory test results. Finally, two frames with the same overall strength enhancement factor are analysed under earthquake loading; the difference in the response clearly demonstrates that the model accounts for important behavioural characteristics which are hitherto neglected in comparable existing models.
A posteriori local error estimation and adaptive time‐stepping for newmark integration in dynamic analysis
Authors: Zeng L. F. , Wiberg N.‐E. , Li X. D. , Xie Y. M. 
Published: April 2007

AbstractA simple a posteriori local error estimate for Newmark time integration schemes in dynamic analysis is presented, based on the concept of a so called ‘post‐processing’ technique. In conjunction with the error estimate, an adaptive time‐stepping algorithm is described, which adjusts the time step size so that the local error of each time step is within a prescribed error tolerance. Numerical examples given in the paper indicate that the error estimate is asymptotically convergent, computationally efficient and convenient, and the adaptive time‐stepping scheme can predict a nearly optimal step size from time to time, thus making the numerical solution reliable in an efficient manner.
Spring‐viscous damper systems for combined seismic and vibration isolation
Authors: Makris N. , Constantinou M. C. 
Published: April 2007

AbstractThe coupled lateral‐vertical‐rocking dynamic response of spring‐viscous damper isolated structures is considered. The force‐displacement relation of the viscous dampers is described by an experimentally calibrated fractional derivative viscoelasticity model. The equations of motion are derived and reduced to a form for direct solution by the discrete Fourier transform method. The validity and accuracy of the derived solution are demonstrated by comparison with shake table test results.The developed analysis procedure is employed in the seismic analysis of a recently constructed isolated structure. The analytical and experimental results demonstrate that spring‐viscous damper isolation systems are capable of providing both effective seismic and vibration isolation.
An identification methodology for a class of hysteretic structures
Authors: Peng C.‐Y. , Iwan W. D. 
Published: April 2007

AbstractThis paper presents a method of identification for determining non‐linear dynamic models for certain hysteretic structures. Particular attention is given to modelling and identifying the hysteretic behaviour of structures from strong‐motion earthquake data. In this method, the response is separated into mode‐like components which are analogous to those of a linear system. Based on modelling of the generalized restoring force of each mode‐like component, both non‐hysteretic and hysteretic non‐linear models are incorporated into the general methodology. A non‐hysteretic model provides an initial estimate for a final hysteretic model. The approach is applicable even when data are available from only a small number of locations in the structure. The structural model identified from this method provides a means to predict the response to future events and, ultimately, to examine the damage to a structure as a result of an earthquake.
Dynamics of pounding when two buildings collide
Authors: Maison Bruce F. , Kasai Kazuhiko 
Published: April 2007

AbstractA formulation and solution of the multiple‐degree‐of‐freedom equations of motion for pounding between two multistorey buildings are presented. Pounding occurs at rigid horizontal diaphragms in each building. The theory is implemented into a microcomputer program and sample earthquake analyses involving pounding between 15‐storey and 8‐storey buildings are performed. The influence of building separation, relative mass, and contact location properties are assessed. Conclusions are drawn regarding response behaviour trends that are relevant to other actual pounding situations.
An efficient time‐domain soil‐structure interaction analysis based on the dynamic stiffness of an unbounded soil
Authors: Hayashi Yasuhiro , Takahashi Ikuo 
Published: April 2007

AbstractAn approximate method and a rigorous method are presented for the time‐domain soil‐structure interaction analysis, both of which use the stiffness of soil obtained numerically or experimentally in the limited frequency range. In the aseismic design of a large‐scale structure, the approximate and rigorous methods are intended to be used in a preliminary analysis and a detailed study, respectively. Both methods are based on the approximation that the first few terms of the Fourier or Taylor expansions of a frequency‐dependent function are used. The difference lies in the number of coefficients of each series, and also in the manner in which the coefficients can be determined. In order to demonstrate the validity of the proposed methods, a soil‐structure system, whose soil has a complex profile under the foundation, is analysed. The dynamic stiffness of the soil is calculated by a 3‐D hybrid approach that combines the finite element method and the boundary element method. As a result, the present methods are capable of evaluating the complexity of the soil more precisely and efficiently than conventional methods.
Lumped‐parameter model for a rigid cylindrical foundation embedded in a soil layer on rigid rock
Authors: Wolf John P. , Paronesso Antonio 
Published: April 2007

AbstractTo represent a cylindrical rigid foundation vibrating in horizontal, vertical, rocking or torsional motions embedded in a soil layer resting on rigid rock, a lumped‐parameter model is described. The coupling between the horizontal and rocking degrees of freedom is considered. For each degree of freedom eight frequency‐independent real coefficients determine the springs, dashpots and the mass of the lumped‐parameter model with two internal degrees of freedom. These coefficients are specified for various ratios of the radius of the foundation to the depth of the layer and lateral contact ratios. To derive the mechanical properties of the lumped‐parameter model a systematic procedure of curvefitting of the dynamic‐stiffness coefficient up to, in general, twice the fundamental frequency of the layer is applied, capturing the fact that below the (horizontal) fundamental frequency (cutoff frequency) no radiation of energy occurs. The lumped‐parameter model can be used to represent the soil in a standard finite‐element program for structural dynamics working in the time domain, whereby the structure can exhibit non‐linear behaviour. Stability of the unbounded soil‐layer model and of the total system is guaranteed. A hammer foundation with partial uplift of the anvil is analysed for illustration.
Fundamental characteristics of Multiple Tuned Mass Dampers for suppressing harmonically forced oscillations
Authors: Yamaguchi Hiroki , Harnpornchai Napat 
Published: April 2007

AbstractMultiple Tuned Mass Dampers (MTMD's) consisting of many tuned mass dampers (TMD's) with distributed natural frequencies are considered for suppressing effectively the harmonically forced single mode response of structures. The fundamental characteristics of MTMD's are investigated analytically with the parameters of the covering frequency range of MTMD's, the damping ratio of each TMD and the total number of TMD's. The effectiveness and the robustness of MTMD's are also discussed in comparison with those of the usual single TMD. It is found that there exists an optimum MTMD for the given total number of TMD's with the optimum frequency range and the optimum damping ratio and that the optimum MTMD is more effective than the optimum single TMD. As for the robustness, it is also clarified that a MTMD can be much more robust than a single TMD while keeping the same level of effectiveness as the optimum single TMD.
Partial eigensolution of damped structural systems by Arnoldi's method
Authors: Chen Harn C. 
Published: April 2007

AbstractAn efficient numerical algorithm is developed to solve the quadratic eigenvalue problems arising in the dynamic analysis of damped structural systems. The algorithm can even be applied to structural systems with non‐symmetric matrices. The algorithm is based on the use of Arnoldi's method to generate a Krylov subspace of trial vectors, which is then used to reduce a large eigenvalue problem to a much smaller one. The reduced eigenvalue problem is solved and the solutions are used to construct approximate solutions to the original large system. In the process, the algorithm takes full advantage of the sparseness and symmetry of the system matrices and requires no complex arithmetic, therefore, making it very economical for use in solving large problems. The numerical results from test examples are presented to demonstrate that a large fraction of the approximate solutions calculated are very accurate, indicating that the algorithm is highly effective for extracting a number of vibration modes for a large dynamic system, whether it is lightly or heavily damped.
An experimental study on active tendon control of cable‐stayed bridges
Authors: Warnitchai Pennung , Fujino Yozo , Pacheco Benito M. , Agret Remi 
Published: April 2007

AbstractActive tendon control of cable‐stayed bridges subject to a vertical sinusoidal force is experimentally and analytically studied. Emphasis is placed on the effects of linear and non‐linear internal resonances on the control (due to the presence of the cable vibration). A simple cable‐supported cantilever beam is used as a model. It is found that active tendon control is very effective in vertical girder motion with small cable vibration (girder dominated motion), whereas it is not effective in vertical girder motion with large cable vibration (cable dominated motion). Analytical prediction is very satisfactory except for the latter case.
Seismic response of light equipment in torsional buildings
Authors: Yang Yeong‐Bin , Huang Wei‐Hsi 
Published: April 2007

AbstractThis paper attempts to study the response of light equipment items attached to a multi‐storey building that may be subjected to large torsional deformations during the earthquake excitation. To account for the effect of torsion and translation, each storey of the building is modelled as two degrees of freedom (DOFs), with one DOF for translation and the other for torsion. Perturbation techniques are employed to find closed‐form expressions for the modal properties of the combined system in terms of the properties of the individual subsystems. The interaction between the equipment and building is studied for both tuned and detuned modes of vibration. Modal synthesis results obtained using the present technique based on the complete quadratic combination (CQC) method are compared with solutions obtained by other methods.
An efficient, adaptive algorithm for large‐scale random vibration analysis
Authors: Harichandran Ronald S. 
Published: April 2007

AbstractAn efficient, adaptive and robust algorithm is proposed to reduce the cost of large‐scale stationary and transient random vibration analysis of structures excited by multiple partially correlated nodal and or base excitations. The cost saving is accomplished by computing integrals selectively, and yet attempting to maintain a level of accuracy desired by the analyst. Recently, proposed closed‐form solutions for fully coherent propagating band‐limited white‐noise excitation are used to rank approximately the terms in the modal covariance matrix. Terms are then evaluated starting from the most important one, and the computations are terminated in such a way that the accuracy level requested by the user is satisfied in an approximate sense. Two variations of the algorithm are proposed: the first one is more robust and is preferred, and is recommended when computing a relatively small number (hundreds) of response quantities; the second one is more efficient when computing a very large number (thousands) of response quantities. Both variations are adaptive, and consider the closeness, damping and participation of all modes explicitly, while the first method also considers the mode shapes. The efficiency and accuracy of the algorithm is investigated by using it to compute the stationary and transient seismic response of the Golden Gate suspension bridge.