bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational aspects of a seismic performance test method using on‐line computer control
Authors: Shing Pui‐Shum B. , Mahin Stephen A. 
Published: March 2007

AbstractThe basic computational procedure of a newly developed seismic performance test méthod is presented and examined in this paper. This method uses a direct step‐by‐step integration technique to compute the displacement response of a test specimen subjected to a numerically specified seismic excitation record, utilizing the non‐linear restoring forces actually developed by the specimen during the experiment. Due to the limitations of the experimental procedure and conditions, special analytical assumptions and numerical methods must be adopted. The adequacy of such analytical techniques is evaluated and possible computational errors are identified. An improved numerical integration algorithm is also proposed for this specific application. It has been found that the method can be a reliable and powerful experimental tool provided appropriate analytical and numerical criteria, as discussed in this paper, are observed.
Response spectra for torsion, rocking and rigid foundations
Authors: Rutenberg Avigdor , Heidebrecht Arthur C. 
Published: March 2007

AbstractSimple procedures are proposed for computing response spectra for torsional and rocking input ground motions assuming horizontally travelling waves of constant shape. It is shown that harmonic relationships exist between the rotational spectra and the corresponding translational spectra, and that SV rather than PSV is the correct basis for deriving the angular displacement, velocity and acceleration response spectra. An approximation enabling the use of the standard tripartite logarithmic response spectra is discussed. Simple expressions for ‘accidental’ eccentricity and rocking input effects are presented. Also proposed are multipliers to spectral ordinates to account for the filtering effects of rigid base mats resting on Winkler type foundations. For wave transit times shorter than half the natural period of the structure, these multipliers can be approximated by the frequency dependent averaging coefficients given in the literature, which are dependent, however, on the response, rather than the input, frequency.
Response of tanks to vertical seismic excitations
Authors: Haroun Medhat A. , Tayel Magdy A. 
Published: March 2007

AbstractA method for analyzing the earthquake response of elastic, cylindrical liquid storage tanks under vertical excitations is presented. The method is based on superposition of the free axisymmetrical vibrational modes obtained numerically by the finite element method. The validity of these modes has been checked analytically and the formulation of the load vector has been confirmed by a static analysis. Two forms of ground excitations have been used: step functions and recorded seismic components. The radial and axial displacements are computed and the corresponding stresses are presented. Both fixed and partly fixed tanks are considered to evaluate the effect of base fixation on tank behaviour. Finally, tank response under the simultaneous action of both vertical and lateral excitations is calculated to evaluate the relative importance of the vertical component of ground acceleration on the overall seismic behaviour of liquid storage tanks.
Vibrations of beams fully or partially supported on elastic foundations
Authors: Eisenberger M. , Yankelevsky D. Z. , Adin M. A. 
Published: March 2007

AbstractExact stiffness and consistent mass matrices for beams on elastic foundations are derived. Using these matrices it is possible to find the natural frequencies and mode shapes of vibrations, for beams fully or partially supported on elastic foundations. Several examples are given for frequencies and mode shapes of beams partially supported on elastic foundations.
Seismic response of light internal equipment in base‐isolated structures
Authors: Kelly James M. , Tsai Hsiang‐Chuan 
Published: March 2007

AbstractThe seismic response of light secondary systems in a building is dependent on the response of the primary structural system to the seismic ground motion with the result that very high accelerations can be induced in such secondary systems. This response can be reduced through the use of aseismic base isolation which is a design strategy whereby the entire building can be decoupled from the damaging horizontal components of seismic ground motion by the use of some form of isolation system.The paper presents a theoretical analysis of the response of light equipment in isolated structures and a parallel experimental programme both of which show that the use of base isolation can not only attenuate the response of the primary structural system but also reduce the response of secondary systems. Thus, the design of equipment and piping in a base‐isolated building is very much simpler than that for a conventionally founded structure: inelastic response and equipment‐structure interaction need not be considered and multiple support response analysis is rendered unnecessary.Although an isolation system with linear elastic bearings can reduce the acceleration of the structure, it may be accompanied by large relative displacements between the structure and the ground. A system using lead‐rubber hysteretic bearings, having a force‐displacement relation which is approximately a bilinear loop, can reduce these displacements. A parallel experimental programme was carried out to investigate the response of light equipment in structures isolated using lead‐rubber bearings. The experimental results show that these bearings can dissipate energy and limit the displacement and acceleration of the structure but are less effective in reducing the accelerations in the internal equipment.The results of both the analysis and the tests show that base isolation is a very effective method for the seismic protection of light equipment items in buildings.
Fuzzy optimum design of aseismic structures
Authors: Guang‐Yuan Wang , Wen‐Quan Wang 
Published: March 2007

AbstractIt was pointed out in our previous paper that there exists a vast amount of fuzzy information in both objective and constraint functions of optimum design of structures. Then the idea of fuzzy optimum design of structures was first proposed and the problem with fuzzy allowable intervals of the physical variables (structural responses and sizes) could be solved via the α‐level cut approach.In this paper, the procedure of fuzzy optimum design of aseismic structures is further developed. For this purpose, the concepts and definitions of fuzzy predictive earthquake intensity, fuzzy response spectrum and fuzzy structural response are given. A solution of the programming problems with generalized fuzzy constraints (including both fuzzy constraint functions and their fuzzy allowable intervals) is put forward; one of its special cases is the χ‐level cut solution in Reference 1. The satisfaction degree of a fuzzy constraint function to its fuzzy allowable interval is defined, by which the problem considered is transformed into a series of non‐fuzzy programmings. Then, a series of optimum points can be obtained which make up the solution of the fuzzy programming.As the solution of fuzzy programming contains not one but a series of optimum points, a two‐step approach is presented to the fuzzy optimum design of aseismic structures. The first step is to find out the set of minimum cost design points corresponding to different design levels. In the second step, both construction cost and earthquake‐caused loss expectation in the service life of the structure are traded off to find the optimum design level as well as a corresponding optimum design scheme.
Dynamic finite element analysis of three‐dimensional soil models with a transmitting element
Authors: Werkle Horst 
Published: March 2007

AbstractA method for the dynamic finite element analysis of a non‐axisymmetric soil model with an axisymmetric boundary is presented. In the non‐axisymmetric soil domain an arbitrary discretization with three‐dimensional isoparametric solid elements is used. At the boundary a transmitting element is arranged. It is based on the semi‐analytical element of Waas and Kausel. The transformation of the stiffness matrix of the Waas/Kausel element with cyclic symmetric displacements to general displacement fields is presented. For earthquake excitation the forces acting on the discretized domain are given. The method is illustrated by the dynamic analysis of an embedded box‐type building. The distribution and magnitude of significant section forces are discussed.
Structural response for six correlated earthquake components
Authors: Ghafory‐Ashtiany Mohsen , Singh Mahendra P. 
Published: March 2007

AbstractThe paper examines the effect on the structural response of the inevitable correlation which exists between the six earthquake components acting along a set of structural axes. The rotational components are expressed in terms of the spatial derivatives of the translational components. For the calculation of response, modal analysis is employed so that ground response spectra can also be used as seismic input. A methodology is developed to obtain the maximum mean square response which can occur in a structure, irrespective of its orientation with respect to the impinging seismic waves. The application of this methodology for the calculation of design response is advocated, especially for asymmetric structures. For the assumed model of seismic wave motion, the numerical results show a significant contribution to the response from the rotational components. This contribution is, however, expected to be reduced by structural foundation averaging and interaction effects. Further studies with more complete models of seismic wave motions, and their interaction with structural foundations, are thus warranted for a realistic evaluation and characterization of the rotational inputs for design purposes.
Earthquake analysis of arch dams including dam–water interaction, reservoir boundary absorption and foundation flexibility
Authors: Fok Ka‐Lun , Chopra Anil K. 
Published: March 2007

AbstractThe available substructure method and computer program for the steady‐state, harmonic response analysis of arch dams, including the hydrodynamic effects, are extended to consider flexibility of the foundation rock and to include Fourier synthesis of harmonic responses to obtain the earthquake response of arch dams. By efficient evaluation of hydrodynamic terms, interpolation of frequency response functions and more efficient computer programming, the computational costs for analysing arch dams have been reduced by an order of magnitude relative to the available procedure.
Fire‐cracked rock features on sandy landforms in the Northern Rocky Mountains: Toward establishing reliable frames of reference for assessing site integrity
Authors: Thoms Alston V. 
Published: March 2007

AbstractIn cool coniferous forest settings of the Northern Rocky Mountains, well‐preserved fire‐cracked rock (FCR) features within 30 cm of the surface on ostensibly stable, sandy upland landforms date to the last six millennia. Isolated FCR and artifacts sometimes extend a meter or more below surface, which is suggestive of in situ burial. A paucity of intact features in the lower solum, however, is consistent with the downward migration of deeply buried artifacts by biomechanical processes, especially floralturbation. Moreover, an absence of credible sediment source areas usually precludes colluvial deposition, and results of grain‐size analysis reported herein are inconsistent with eolian deposition. Site disarticulation rates tend to be faster on landforms in warmer forested regions of south‐central North America, given that most intact FCR features there date only to the last two millennia. The very presence of millennia‐old FCR features in these diverse settings, however, is a testament to their durability and utility as measures of site integrity. © 2007 Wiley Periodicals, Inc.
Depression in older adults: exploring the relationship between goal setting and physical health
Authors: Street Helen , O'Connor Moira , Robinson Hayley 
Published: March 2007

AbstractDepression in older adults is associated with a decreased quality of life, increased physical and emotional suffering and an increased risk of death and is often associated with declining physical health. Older people with physical illness have higher rates of depression and studies have also noted the particularly high rate of co‐morbidity between depressive disorder and general medical conditions. However, other studies have shown those suffering from poor physical health do not necessarily become depressed and, in particular, the goal setting style of the individual impacts on the relationship between poor physical health and depression. This study argues that those who are conditional goal setters and suffer from poorer physical health will be more prone to depression as their perceived ability to achieve their goals is negatively impacted. One hundred and eighty‐seven participants were recruited for this study. The participants completed the Centre for Epidemiological Studies Depression Inventory and the physical health subscale of the SF‐12 Health Survey. Participants were asked to rank their three most important goals and to give the main reason for setting each of their top three goals. The results showed that poorer physical health is associated with higher depression scores. Correlations revealed significant negative associations between physical health and depression, physical health and progress towards goal and progress towards goal and depression. A partial correlation between physical health and depression scores controlling for progress demonstrated that the relationship between physical health and depression is mediated through perceived progress. Implications for clinical practice are highlighted. Copyright © 2007 John Wiley & Sons, Ltd.
Modeling low‐frequency fluctuation and hemodynamic response timecourse in event‐related fMRI
Authors: Kay Kendrick N. , David Stephen V. , Prenger Ryan J. , Hansen Kathleen A. , Gallant Jack L. 
Published: March 2007

AbstractFunctional magnetic resonance imaging (fMRI) suffers from many problems that make signal estimation difficult. These include variation in the hemodynamic response across voxels and low signal‐to‐noise ratio (SNR). We evaluate several analysis techniques that address these problems for event‐related fMRI. (1) Many fMRI analyses assume a canonical hemodynamic response function, but this assumption may lead to inaccurate data models. By adopting the finite impulse response model, we show that voxel‐specific hemodynamic response functions can be estimated directly from the data. (2) There is a large amount of low‐frequency noise fluctuation (LFF) in blood oxygenation level dependent (BOLD) time‐series data. To compensate for this problem, we use polynomials as regressors for LFF. We show that this technique substantially improves SNR and is more accurate than high‐pass filtering of the data. (3) Model overfitting is a problem for the finite impulse response model because of the low SNR of the BOLD response. To reduce overfitting, we estimate a hemodynamic response timecourse for each voxel and incorporate the constraint of time‐event separability, the constraint that hemodynamic responses across event types are identical up to a scale factor. We show that this technique substantially improves the accuracy of hemodynamic response estimates and can be computed efficiently. For the analysis techniques we present, we evaluate improvement in modeling accuracy via 10‐fold cross‐validation. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
Mutual‐information‐based approach for neural connectivity during self‐paced finger lifting task
Authors: Chen Chun‐Chuan , Hsieh Jen‐Chuen , Wu Yu‐Zu , Lee Po‐Lei , Chen Shyan‐Shiou , Niddam David M. , Yeh Tzu‐Chen , Wu Yu‐Te 
Published: March 2007

AbstractFrequency‐dependent modulation between neuronal assemblies may provide insightful mechanisms of functional organization in the context of neural connectivity. We present a conjoined time‐frequency cross mutual information (TFCMI) method to explore the subtle brain neural connectivity by magnetoencephalography (MEG) during a self‐paced finger lifting task. Surface electromyogram (sEMG) was obtained from the extensor digitorum communis. Both within‐modality (MEG‐MEG) and between‐modality studies (sEMG‐MEG) were conducted. The TFCMI method measures both the linear and nonlinear dependencies of the temporal dynamics of signal power within a pre‐specified frequency band. Each single trial of MEG across channels and sEMG signals was transformed into time‐frequency domain with use of the Morlet wavelet to obtain better temporal spectral (power) information. As compared to coherence approach (linear dependency only) in broadband analysis, the TFCMI method demonstrated advantages in encompassing detection for the mesial frontocentral cortex and bilateral primary sensorimotor areas, clear demarcation of event‐ and non‐event‐related regions, and robustness for sEMG ‐ MEG between‐modality study, i.e., corticomuscular communication. We conclude that this novel TFCMI method promises a possibility to better unravel the intricate functional organizations of brain in the context of oscillation‐coded communication. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
Relation between muscle and brain activity during isometric contractions of the first dorsal interosseus muscle
Authors: van Duinen Hiske , Renken Remco , Maurits Natasha M. , Zijdewind Inge 
Published: March 2007

AbstractWe studied the relationship between muscle activity (electromyography, EMG), force, and brain activity during isometric contractions of the index finger, on a group and individual level. Ten subjects contracted their right or left index finger at 5, 15, 30, 50, and 70% of their maximal force. Subjects received visual feedback of the produced force. We focused our analysis on brain activation that correlated with EMG. Brain activity of specific anatomical areas (region‐of‐interest analysis, ROI) was quantified and correlated with EMG activity. Furthermore, we tried to distinguish between brain areas in which activity was modulated by the amount of EMG and areas that were active during the task but in which the activity was not modulated. Therefore, we used two regressors simultaneously: (1) the produced EMG and (2) the task (a categorical regressor). As expected, activity in the motor areas (contralateral sensorimotor cortex, premotor areas, and ipsilateral cerebellum) strongly correlated with the amount of EMG. In contrast, activity in frontal and parietal areas (inferior part of the right precentral sulcus, ipsilateral supramarginal gyrus, bilateral inferior parietal lobule, bilateral putamen, and insular cortex) correlated with activation per se, independently of the amount of EMG. Activity in these areas was equal during contractions of the right or left index finger. We suppose that these areas are more involved in higher order motor processes during the preparatory phase or monitoring feedback mechanisms. Furthermore, our ROI analysis showed that muscle and brain activity strongly correlate in traditional motor areas, both at group and at subject level. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
An assessment of some open issues in the analysis of foreign exchange intervention
Authors: Vitale Paolo 
Published: March 2007

AbstractWe discuss some fundamental aspects of the study of foreign exchange intervention. In particular, we analyse some unresolved issues, such as the secrecy puzzle, the relevance of the signalling and portfolio‐balance effect hypotheses, the identification of the impact of foreign exchange intervention on currency values. We argue that: (i) the unresolved nature of these issues is partly due to the absence of a market microstructure perspective in most of the existing analysis of foreign exchange intervention; and (ii) that recent promising advances in this strand of research have not fully exploited the potential of such perspective. Copyright © 2007 John Wiley & Sons, Ltd.
DFT studies using supercells and projector‐augmented waves for structure, energetics, and dynamics of glycine, alanine, and cysteine
Authors: Maul R. , Ortmann F. , Preuss M. , Hannewald K. , Bechstedt F. 
Published: March 2007

AbstractA large variety of gas phase conformations of the amino acids glycine, alanine, and cysteine is studied by numerically efficient semi‐local gradient‐corrected density functional theory calculations using a projector‐augmented wave scheme and periodic boundary conditions. Equilibrium geometries, conformational energies, dipole moments, vibrational modes, and IR optical spectra are calculated from first principles. A comparison of our results with values obtained from quantum‐chemistry methods with localized basis sets and nonlocal exchange‐correlation functionals as well as with experimental data is made. For conformations containing strong intramolecular hydrogen bonds deviations in their energetic ordering occur, which are traced back to different treatments of spatial nonlocality in the exchange‐correlation functional. However, even for these structures, the comparison of calculated and measured vibrational frequencies shows satisfying agreement. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007.
Time‐correlated single photon counting FLIM: Some considerations for physiologists
Authors: Medine Claire N. , Mcdonald Angela , Bergmann Axel , Duncan Rory R. 
Published: March 2007

AbstractRecent developments in cellular imaging now permit the minimally invasive study of protein interactions in living cells. These advances are of enormous interest to cell biologists, as proteins rarely act in isolation, but rather in concert with others in forming cellular machinery. Up until recently, all protein interactions had to be determined in vitro using biochemical approaches. This biochemical legacy has provided cell biologists with the basis to test defined protein‐protein interactions not only inside cells, but now also with spatial resolution. More recent developments in TCSPC imaging are now also driving towards being able to determine protein interaction rates with similar spatial resolution, and together, these experimental advances allow investigators to perform biochemical experiments inside living cells. Here, we discuss some findings we have made along the way which may be useful for physiologists to consider. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Vertex partitions and maximum degenerate subgraphs
Authors: Matamala Martín 
Published: March 2007

AbstractLet G be a graph with maximum degree d≥ 3 and ω(G)≤ d, where ω(G) is the clique number of the graph G. Let p1 and p2 be two positive integers such that d = p1 + p2. In this work, we prove that G has a vertex partition S1, S2 such that G[S1] is a maximum order (p1‐1)‐degenerate subgraph of G and G[S2] is a (p2‐1)‐degenerate subgraph, where G[Si] denotes the graph induced by the set Si in G, for i = 1,2. On one hand, by using a degree‐equilibrating process our result implies a result of Bollobas and Marvel [1]: for every graph G of maximum degree d≥ 3 and ω(G)≤ d, and for every p1 and p2 positive integers such that d = p1 + p2, the graph G has a partition S1,S2 such that for i = 1,2, Δ(G[Si])≤ pi and G[Si] is (pi‐1)‐degenerate. On the other hand, our result refines the following result of Catlin in [2]: every graph G of maximum degree d≥ 3 has a partition S1,S2 such that S1 is a maximum independent set and ω(G[S2])≤ d‐1; it also refines a result of Catlin and Lai [3]: every graph G of maximum degree d≥ 3 has a partition S1,S2 such that S1 is a maximum size set with G[S1] acyclic and ω(G[S2])≤ d‐2. The cases d = 3, (d,p1) = (4,1) and (d,p1) = (4,2) were proved by Catlin and Lai [3]. © 2007 Wiley Periodicals, Inc. J Graph Theory 55: 227–232, 2007