bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibration of viscoelastic foundations
Authors: Veletsos A. S. , Verbič B. 
Published: March 2007

AbstractSimple approximate solutions are presented for the steady‐state response of a massless, rigid disk, which is supported at the surface of a linear viscoelastic halfspace and is excited by a harmonically varying horizontal or vertical force, or by a harmonically varying moment about an axis in the plane of the disk. The halfspace is idealized either as a standard Voigt solid or as a constant hysteretic solid. The solution for the massless disk is then applied to the analysis of foundations with mass, and for each mode of excitation, comprehensive numerical data are presented to illustrate the effects of viscoelastic action on the response of both the massless disk and of foundations with massIt is shown that the principal effects of material damping are to increase the damping capacity of the foundation and to reduce its ‘natural’ frequency. In the mathematically equivalent representation of the elastically supported massless disk as a spring‐dashpot combination without mass, it is shown that the effective stiffness of the spring may become negative over significant ranges of the exciting frequency, and that it is preferable to model the disk‐halfspace system as an oscillator with mass, taking its spring constant equal to the static stiffness of the original system.
Prediction of buckling strengths of cylindrical shells from their natural frequencies
Authors: Radhakrishnan R. 
Published: March 2007

AbstractThe instability of thin elastic shells still remains the most challenging of all the classical problems of the theory of elasticity. It is the aim of this investigation to verify a rational experimental technique for predicting the buckling loads of cylindrical tubes under axial load as well as under external radial pressure, by measuring their natural frequencies under different loadings. Cylindrical tubes made of Hostaphan (thickness 0·254 mm and radius 100 mm) were tested under axial load and under external radial pressure in the German Air and Space Research Laboratory (Deutsche Forschungsanstalt für Luft und Raumfahrt) at Braunschweig, West Germany, and the results compared with an actual buckling test. The tests revealed that the buckling load can be predicted satisfactorily by the proposed non‐destructive vibration method of testing.
Earthquake interaction forces between two structures of different rigidities
Authors: Ban Shizuo 
Published: March 2007

AbstractA combined structure is assumed to be composed of a rigid part and a flexible part. Each component structure would have a different period of natural vibration if it were built independently. When they are combined in one structure and subjected to an earthquake, there must be generated some interaction forces so that the component structures will have a common vibration. In this paper is an analytical method described to evaluate such interaction forcesThe general principle is as follows. For each of the component structures, equations of motion taking account of the unknown interaction forces are derived first. Then by eliminating the interaction forces, equations of motion of the combined structure are obtained. After solving these equations and substituting the solution into the equations of motion of the component structures, the unknown interaction forces are obtained directlyIn the present paper, two structures corresponding to two‐degree elastic systems are considered; numerical examples also are included.
Earthquake analysis of gravity dams including hydrodynamic interaction
Authors: Chakrabarti P. , Chopra Anil K. 
Published: March 2007

AbstractA general procedure for analysis of the response of gravity dams, including hydrodynamic interaction and compressibility of water, to the transverse horizontal and vertical components of earthquake ground motion is presented. The problem is reduced to one in two dimensions considering the transverse vibration of a monolith of a dam, and the material behaviour is assumed to be linearly elasticThe complete system is considered as composed of two substructures—the dam, represented as a finite element system, and the reservoir, as a continuum of infinite length in the upstream direction governed by the wave equation. The structural displacements of the dam (including effects of water) are expressed as a linear combination of the modes of vibration of the dam with the reservoir empty. The effectiveness of this analytical formulation lies in its being able to produce excellent results by considering only the first few modes. The complex frequency response for the modal displacements are obtained first. The responses to arbitrary ground motion are subsequently obtained with the aid of the Fast Fourier Transform algorithmAn example analysis is presented to illustrate results obtained from this method. It is concluded that the method is very effective and efficient and is capable of producing results to any desired degree of accuracy by including the necessary number of modes of vibration of the dam.
Response of rectangular orthotropic plates to random excitations
Authors: Sundararajan C. , Reddy D. V. 
Published: March 2007

AbstractThe paper describes the application of the finite strip method, a modification of the finite element method, to determine the random response of rectangular plates. An example problem of a rectangular orthotropic plate, simply supported on two opposite edges and clamped on the other two, under acoustic white noise excitation is solved.
Earth Dam‐foundation interaction during earthquakes
Authors: Idriss I. M. , Mathur J. M. , Bolton Seed H. 
Published: March 2007

AbstractSeveral significant parameters that could affect interaction in a dam‐foundation system are discussed. These parameters are: (1) Fundamental periods of the dam and the foundation layer. (2) Lateral extent of the dam. (3) The material properties of the dam and the foundation layer. Five cases are analysed to illustrate the influence of these parameters on interaction. An interaction ratio, R1, relating the response of the dam‐foundation system at the base of the dam to the free field response is introduced and interaction effects are expressed in terms of this ratio; the smaller this ratio, the less are the interaction effects. For very small values of R1, it is shown that the dam‐foundation system could be decoupledThe results of the studies presented in the paper suggest that the interaction effects cannot be uniquely related to either the ratio of the period of the dam to the period of the foundation layer, or to the material properties of the dam and foundation layer. However, for the limited number of cases investigated, the interaction effects were found to be uniquely related to the ratio D/B, where D is the depth of the foundation layer and B is the width of the dam section. For values of D/B less than unity, strong interaction effects were obtained and the dam‐foundation system could only be analysed as a coupled system. For values of D/B greater than unity, the interaction appeared negligible and the dam and its foundation layer could be decoupled. It should be noted, however, that for very small values of D/B the interaction effects would decrease becaase as D approaches zero, there would be no interactionThe use of the interaction ratio, R1, and the parameter D/B should aid in assessing the need for analysing the response of the dam‐foundation as a coupled or as a decoupled system.
Stochastic considerations in seismic analysis of structures
Authors: Singh M. P. , Chu S. L. 
Published: March 2007

AbstractA method is presented for stochastic modelling of a design earthquake by a power spectral density function for seismic analysis of structures. The method can be adopted with information currently available in the form of design response spectra for earthquake motion. Accurate seismic responses of structures can be easily obtained using such stochastic models. The methods for accurate response analysis of structures with closely spaced modes and for generation of floor response spectra of a building using a prescribed ground response spectrum directly are also presented. The hypothesis that a design earthquake can be modelled by a power spectral density function is used only implicitly in developing these methods.
Correlations of peak acceleration, velocity and displacement with earthquake magnitude, distance and site conditions
Authors: Trifunac M. D. , Brady A. G. 
Published: March 2007

AbstractA brief review of proposed correlations between peak accelerations and earthquake magnitude and distance has been presented. It has been found that most investigators agree favourably on what should be the amplitude of peak accelerations for the distance range between about 20 and 200 km. For distances less than 20 km, there is significant disagreement in the predicted peak amplitudes, reflecting the lack of data there and the uncertainties associated with the extrapolation.Correlations of peak accelerations, peak velocities and peak displacements with earthquake magnitude, epicentral distance and the geologic conditions of the recording sites have been presented for 187 accelerograms recorded during 57 earthquakes. This data set describes strong earthquake ground motion in the Western United States during the period from 1933 to 1971.For large earthquakes, dependence of peak acceleration, velocity and displacement amplitudes on earthquake magnitude seems to be lost. This suggests that the amplitudes of strong ground motion close to a fault are scaled primarily by the maximum dislocation amplitudes and the stress drop, rather than the overall ‘size’ of an earthquake as measured by magnitude.The influence of geologic conditions at the recording station seems to be of minor importance for scaling peak accelerations, but it becomes noticeable for the peaks of velocity and even more apparent for the peaks of displacement.
Dynamic transient behaviour of two‐ and three‐dimensional structures including plasticity, large deformation effects and fluid interaction
Authors: Shantaram D. , Owen D. R. J. , Zienkiewicz O. C. 
Published: March 2007

AbstractThe finite element method is employed in the prediction of the dynamic transient response of two‐ and three‐dimensional solids exhibiting geometric (large deformations) and material (elasto‐plastic) non‐linearities. Explicit time marching schemes are adopted for integration of the dynamic equilibrium equation and a diagonal ‘lumped’ mass matrix is employed with a special procedure applicable to parabolic isoparametric elements. A variety of problems are presented including a solid/fluid interaction situation, and the method is shown to be able to solve economically many problems of dynamic or catastrophic nature which can occur in such structures as nuclear reactors, containment vessels, etc.
Comparative analysis of the seismic risk in sites of different seismicity
Authors: Grandori G. , Petrini V. 
Published: March 2007

AbstractFour sites (a, b, c, d) are considered of differing seismicity. The calculations, for two different buildings on each site, consisted of:

The total monetary cost as a function of the design seismic coefficient c.
The marginal cost of a saved life, ΔD/ΔL, also depending on c.
The ratios between the design seismic coefficients in the various sites, cd/ca, cd/cb, cd/cc, that lead to the same marginal cost ΔD/ΔL in all sites.
The marginal cost ΔD/ΔL turns out to be highly sensitive to uncertainties, but the other ratios are scarcely influenced by the uncertainties met in analysing the problem. This would suggest the adoption of a rationalized principle for comparing the levels of severity in the Codes for sites with differing degrees of seismicity.If a criterion for evaluating indirect cost due to damage or collapse is fixed for each building and each site the values of c corresponding to minimum monetary cost are not strongly influenced by the said uncertainties. This would make it possible to look into the problem of the minimum levels of severity in the Codes. Of course, this assumes that the levels of severity should always be higher than those corresponding to the minimum monetary cost.
Contact stresses and ground motion generated by soil‐structure interaction
Authors: Wong H. L. , Luco J. E. , Trifunac M. D. 
Published: March 2007

AbstractA study has been made of the dynamic contact stresses that the foundation of a nine‐storey reinforced concrete building exerts on the soil during forced vibration tests. The effects of the flexibility of the foundation on the contact stress distribution and on the force‐displacement relationship for the foundation have been examined in an attempt at testing several simplifying assumptions commonly used in soil‐structure interaction studies. Comparisons of calculated and observed ground displacements induced by soil‐structure interaction in the immediate neighbourhood of the building have also been presented.
Free vibrations of open‐section shear walls
Authors: Mukherjee Priya R. , Coull Alexander 
Published: March 2007

AbstractThe coupled torsional‐flexural vibration of open‐section shear walls, braced by connecting beams at each floor level, is analysed on the basis of Vlasov's theory of thin‐walled beams. The basic dynamic equations and boundary conditions are derived from Hamilton's principle, and a numerical solution obtained by the Ritz‐Galerkin method. In addition to the primary torsional and flexural inertias, secondary effects due to rotatory and warping inertia forces have also been taken into account. The method is suitable for both rigid and flexible base conditions.A series of numerical examples is presented in which analytical results are compared with available experimental data, and the effects of secondary inertia forces, base flexibility and connecting beams upon the vibration characteristics of such shear walls are examined for two different structural forms.
Frequency analysis of coupled shear wall assemblies
Authors: Cheung Y. K. , Hutton S. G. , Kasemset C. 
Published: March 2007

AbstractThe finite strip procedure is used to predict the free vibration response of both planar and non‐planar coupled shear wall assemblies. The solid walls are considered as vertical cantilever strips and a comparison is made between modelling the spandrel beams as discrete beams and as an equivalent continuum with orthotropic plate properties. It is shown that both approaches lead to essentially the same frequencies. The effects of vertical inertial forces and shear deflection are included, and structures considered may have properties that vary with height. The method presented appears to be more versatile than previously published techniques and numerical comparisons with existing methods indicate the predicted results to be accurate.
Seismic risk analysis of discrete system of sites
Authors: Taleb‐Agha Ghiath , Whitman Robert V. 
Published: March 2007

AbstractTwo efficient schemes have been developed for the analysis of discrete systems of sites. Both schemes have the same objective of finding the probability of simultaneous failure of any number of sites belonging to a given system of sites subject to threats from a given set of earthquake sources with known seismic history. In the first scheme, systems with deterministic site resistances can effectively be analysed using a non‐linear transformation of variables. In the second scheme, systems with random site resistances can be analysed. To overcome the computational difficulties involved in the analysis, a new set of simple recursive formulas has been developed and used effectively. Based on these two schemes, two efficient computer programs were prepared and used to perform a parametric study on a system of nine actual or contemplated nuclear power plants in New England. The results have shown that the problem is very sensitive to the coefficient of variation of the resistances and not so sensitive to the mean resistances.
Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1,3‐Selenazinane and 1,3‐Selenazinanone Derivatives
Authors: Sommen Geoffroy L. , Linden Anthony , Heimgartner Heinz 
Published: March 2007

AbstractThe reaction of the intermediate ketene N,Se‐hemiacetal 3, prepared from cyanomethylene derivatives 1 by treatment with Et3N and aryl isoselenocyanates 2, with bis‐electrophiles 6, 7, 9, and 11 in DMF affords tetrahydro‐1H‐1,3‐selenazine (=1,3‐selenazinane) derivatives 8, 10, and 12 in good yield (Scheme 2 and Tables 1–3). Chemical and spectroscopic evidence for the structures of the new compounds are described. The structures of 8d and 12e are established by X‐ray crystallography (Figs. 1 and 2).
New Syntheses of Retinal and Its Acyclic Analog γ‐Retinal by an Extended Aldol Reaction with a C6 Building Block That Incorporates a C5 Unit after Decarboxylation. A Formal Route to Lycopene and β‐Carotene
Authors: Valla Alain , Valla Benoist , Le Guillou Régis , Cartier Dominique , Dufossé Laurent , Labia Roger 
Published: March 2007

AbstractSince the C15 β‐end‐group aldehyde 10 ((β‐ionylidene)acetaldehyde), an excellent intermediate in the syntheses of retinoids, can be synthesized in many ways from β‐ionone, and since the corresponding acyclic C15 ψ‐end‐group aldehyde 5 can easily be synthesized from citral (1) (Scheme 3), we applied the C15+C5 route to the syntheses of γ‐retinal ((all‐E)‐8) (Scheme 3) and retinal ((all‐E)‐13) (Scheme 4), and therefore, by coupling (2×C20→C40), to the preparation of lycopene (14) and β‐carotene (15) (Scheme 5). Our new syntheses of retinal ((all‐E)‐13) and γ‐retinal ((all‐E)‐8 use an extended aldol reaction with a C6 building block that incorporates a C5 unit after decarboxylation.
Nucleosides and Oligonucleotides with Diynyl Side Chains: Base Pairing and Functionalization of 2′‐Deoxyuridine Derivatives by the Copper(I)‐Catalyzed AlkyneAzide ‘Click’ Cycloaddition
Authors: Seela Frank , Sirivolu Venkata Ramana 
Published: March 2007

AbstractOligonucleotides containing the 5‐substituted 2′‐deoxyuridines 1b or 1d bearing side chains with terminal CC bonds are described, and their duplex stability is compared with oligonucleotides containing the 5‐alkynyl compounds 1a or 1c with only one nonterminal CC bond in the side chain. For this, 5‐iodo‐2′‐deoxyuridine (3) and diynes or alkynes were employed as starting materials in the Sonogashira cross‐coupling reaction (Scheme 1). Phosphoramidites 2b–d were prepared (Scheme 3) and used as building blocks in solid‐phase synthesis. Tm Measurements demonstrated that DNA duplexes containing the octa‐1,7‐diynyl side chain or a diprop‐2‐ynyl ether residue, i.e., containing 1b or 1d, are more stable than those containing only one triple bond, i.e., 1a or 1c (Table 3). The diyne‐modified nucleosides were employed in further functionalization reactions by using the protocol of the CuI‐catalyzed Huisgen–Meldal–Sharpless [2+3] cycloaddition (‘click chemistry’) (Scheme 2). An aliphatic azide, i. e., 3′‐azido‐3′‐deoxythymidine (AZT; 4), as well as the aromatic azido compound 5 were linked to the terminal alkyne group resulting in 1H‐1,2,3‐triazole‐modified derivatives 6 and 7, respectively (Scheme 2), of which 6 forms a stable duplex DNA (Table 3). The Husigen–Meldal–Sharpless cycloaddition was also performed with oligonucleotides (Schemes 4 and 5).
Shared near neighbours neural network model: a debris flow warning system
Authors: Chang Fi‐John , Tseng Kuo‐Yuan , Chaves Paulo 
Published: March 2007

AbstractThe main purpose of this study is to develop a new type of artificial neural network based model for constructing a debris flow warning system. The Chen‐Eu‐Lan river basin, which is located in Central Taiwan, is assigned as the study area. The creek is one of the most well‐known debris flow areas where several damaging debris flows have been reported in the last two decades. The hydrological and geological data, which might have great influence on the occurrence of debris flows, are first collected and analysed, then, the shared near neighbours neural network (SNN + NN) is presented to construct the debris flow warning system for the watershed. SNN is an unsupervised learning method that has the advantage of dealing with non‐globular clusters, besides presenting computational efficiency. By using SNN, the compiled hydro‐geological data set can easily and meaningfully be clustered into several categories. These categories can then be identified as ‘occurrence’ or ‘no‐occurrence’ of debris flows. To improve the effectiveness of the debris flow warning system, a neural network framework is designed to connect all the clusters produced by the SNN method, whereas the connected weights of the network are adjusted through a supervised learning method. This framework is used and its applicability and practicability for debris flow warning are investigated. The results demonstrate that the proposed SNN + NN model is an efficient and accurate tool for the development of a debris flow warning system. Copyright © 2007 John Wiley & Sons, Ltd.
Hillslope hydrology and wetland response of two small zero‐order boreal catchments on the Precambrian Shield
Authors: Frisbee M. D. , Allan C. J. , Thomasson M. J. , Mackereth R. 
Published: March 2007

AbstractTwo Precambrian Shield zero‐order catchments were monitored from January 2003 to July 2004 to characterize their hydrological and biogeochemical characteristics prior to a forest management experiment. Hydrometric observations were used to examine temporal trends in hillslope‐wetland connectivity and the hillslope runoff processes that control wetland event response. The hillslope groundwater flux from the longer transect (E1) was continuous throughout the study period. Groundwater fluxes from a shorter and steeper hillslope (E0) were intermittent during the study period. Large depression storage elements (termed micro‐basins) located on the upper hillslope of the E1 catchment appeared to be at least partly responsible for the observed rapid wetland runoff responses. These micro‐basins were hydrologically connected to a downslope wetland by a subsurface channel of glacial cobbles that functioned as a macropore channel during episodic runoff events. The runoff response from the hilltop micro‐basins is controlled by antecedent water table position and water is quickly piped to the wetland fringe through the cobble channel during high water table conditions. During periods of low water table position, seepage along the bedrock–soil interface from the hilltop micro‐basin and other hillslopes maintained hillslope–wetland connectivity. The micro‐basins create a dynamic variable source‐area runoff system where the contributing area expands downslope during episodic runoff events. The micro‐basins occupied 30% of the E1 catchment and are a common feature on the Precambrian Shield. Copyright © 2007 John Wiley & Sons, Ltd.
Grb2‐SH3 ligand inhibits the growth of HER2+ cancer cells and has antitumor effects in human cancer xenografts alone and in combination with docetaxel
Authors: Gril Brunilde , Vidal Michel , Assayag Franck , Poupon Marie‐France , Liu Wang‐Qing , Garbay Christiane 
Published: March 2007

AbstractHER2 represents an important signaling pathway in breast and other cancers. Herceptin has demonstrated clinical activity, but resistance is common. Thus, new therapeutic approaches to the HER2 pathway are needed. Grb2 is an adaptor protein involved in Ras‐dependent signaling induced by HER2 receptors. A specific Grb2‐SH3 ligand, designed and synthesized in our laboratory, called peptidimer‐c, inhibited colony formation in HER2 overexpressing SKBr3 cancer cells. Combined treatment of peptidimer‐c with docetaxel further inhibited both colony formation and tumor cell survival compared to docetaxel treatment alone. Efficacy of this combined treatment was correlated with a reduction in the phosphorylation of MAPK and AKT. Finally, peptidimer‐c reduced the growth of a HER2+ human breast cancer (BK111) xenograft in nude mice and potentiated the antitumor effect of docetaxel in a HER2+ hormone‐independent human prostate adenocarcinoma (PAC120 HID28) xenograft. These results validate Grb2 as a new target for the HER2 pathway. © 2007 Wiley‐Liss, Inc.