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Discrete Points (discrete + point)
Selected AbstractsSeismic evaluation of 1940s asymmetric wood-frame building using conventional measurements and high-definition laser scanningEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2009Khalid M. Mosalam Abstract This study presents results from shake table experiments of a wood-frame building conducted at the University of California, Berkeley. A 13.5-ft × 19.5-ft two-story wood-frame building representing San Francisco 1940s design of a residential building with a garage space on the first story (house-over-garage) was tested. The test building was subjected to scaled ground motion based on Los Gatos record from Loma Prieta 1989 earthquake. The strong motion time history was scaled to match design spectra of a site in Richmond district of San Francisco. The test results demonstrated the seismic vulnerability of the test building due to soft story mechanism and significant twisting when shaken in two horizontal directions. In addition to conventional instrumentation for measuring acceleration and position of selected points of the test building, high-definition laser scanning technology was employed to assess global and local anomalies of the building after the shake table tests. The analysis conducted in this study showed very good correlation between conventional data recorded from position transducers and the laser scans. These laser scans expanded limits of conventional data at discrete points and allowed analyzing the whole building after shaking. Copyright © 2009 John Wiley & Sons, Ltd. [source] Bond rolling resistance and its effect on yielding of bonded granulates by DEM analysesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2006M. J. Jiang Abstract A discrete element modelling of bonded granulates and investigation on the bond effect on their behaviour are very important to geomechanics. This paper presents a two-dimensional (2-D) discrete element theory for bonded granulates with bond rolling resistance and provides a numerical investigation into the effect of bond rolling resistance on the yielding of bonded granulates. The model consists of mechanical contact models and equations governing the motion of bonded particles. The key point of the theory is that the assumption in the original bond contact model previously proposed by the authors (55th CSCE-ASCE Conference, Hamilton, Ont., Canada, 2002; 313,320; J. Eng. Mech. (ASCE) 2005; 131(11):1209,1213) that bonded particles are in contact at discrete points, is here replaced by a more reliable assumption that bonded particles are in contact over a width. By making the idealization that the bond contact width is continuously distributed with the normal/tangential basic elements (BE) (each BE is composed of spring, dashpot, bond, slider or divider), we establish a bond rolling contact model together with bond normal/tangential contact models, and also relate the governing equations to local equilibrium. Only one physical parameter , needs to be introduced in the theory in comparison to the original bond discrete element model. The model has been implemented into a 2-D distinct element method code, NS2D. Using the NS2D, a total of 86 1-D, constant stress ratio, and biaxial compressions tests have been carried out on the bonded granular samples of different densities, bonding strengths and rolling resistances. The numerical results show that: (i) the new theory predicts a larger internal friction angle, a larger yielding stress, more brittle behaviour and larger final broken contact ratio than the original bond model; (ii) the yielding stress increases nonlinearly with the increasing value of ,, and (iii) the first-yield curve (initiation of bond breakage), which define a zone of none bond breakage and which shape and size are affected by the material density, is amplified by the bond rolling resistance in analogous to that predicted by the original bond model. Copyright © 2006 John Wiley & Sons, Ltd. [source] A reproducing kernel method with nodal interpolation propertyINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2003Jiun-Shyan Chen Abstract A general formulation for developing reproducing kernel (RK) interpolation is presented. This is based on the coupling of a primitive function and an enrichment function. The primitive function introduces discrete Kronecker delta properties, while the enrichment function constitutes reproducing conditions. A necessary condition for obtaining a RK interpolation function is an orthogonality condition between the vector of enrichment functions and the vector of shifted monomial functions at the discrete points. A normalized kernel function with relative small support is employed as the primitive function. This approach does not employ a finite element shape function and therefore the interpolation function can be arbitrarily smooth. To maintain the convergence properties of the original RK approximation, a mixed interpolation is introduced. A rigorous error analysis is provided for the proposed method. Optimal order error estimates are shown for the meshfree interpolation in any Sobolev norms. Optimal order convergence is maintained when the proposed method is employed to solve one-dimensional boundary value problems. Numerical experiments are done demonstrating the theoretical error estimates. The performance of the method is illustrated in several sample problems. Copyright © 2003 John Wiley & Sons, Ltd. [source] Identification and adaptive control of some stochastic distributed parameter systemsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2001B. Pasik-Duncan Abstract An important class of controlled linear stochastic distributed parameter systems is that with boundary or point control. A survey of some existing adaptive control problems with their solutions for the boundary or the point control of a partially known linear stochastic distributed parameter systems is presented. The distributed parameter system is described by an analytic semigroup with cylindrical white noise and a control that occurs only on the boundary or at discrete points. The unknown parameters in the model appear affinely in both the infinitesimal generator of the semigroup and the linear transformation of the control. The noise in the system is a cylindrical white Gaussian noise. Strong consistency is verified for a family of least-squares estimates of the unknown parameters. For a quadratic cost functional of the state and the control, the certainty equivalence control is self-optimizing, that is the family of average costs converges to the optimal ergodic cost. Copyright © 2001 John Wiley & Sons, Ltd. [source] Step and pulse response methods for identification of wiener processesAICHE JOURNAL, Issue 2 2006Ho Cheol Park Abstract Lack of simple identification methods for nonlinear processes hinders field applications of nonlinear control systems. For identification methods that are as simple as those for the first order plus time delay models of linear dynamical processes, graphical and least squares methods to identify Wiener-type nonlinear processes from standard responses, such as step, pulse, and square-wave responses, are proposed. Static nonlinear functions are identified independently in Wiener-type nonlinear processes. Graphical methods extract discrete points of the nonlinear static function or a continuous non-parametric model of the nonlinear static function iteratively. The least squares method provides a parametric model of the nonlinear static function. The identified static nonlinear function can be used to design a simple linearizing control system. To illustrate the proposed identification methods, simulation and experimental results are given. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] A quantitative comparison of the ontogeny of two closely-related Upper Devonian phacopid trilobitesLETHAIA, Issue 2 2005CATHERINE CRÔNIER The best insight into the development of Devonian phacopids has been obtained from Trimerocephalus lelievrei Crônier & Feist, 1997, a Famennian phacopine from Morocco, where changes in size and shape have been quantified. In this study, a morphometric approach has been used: (1) to retrodeform and then establish patterns of morphological variation in a well preserved but tectonically deformed assemblage belonging to another phacopine species Weyerites ensae (Richter & Richter, 1926), a Famennian phacopine from Thuringia, and (2) to establish patterns of developmental and evolutionary changes within two closely related species: Weyerites ensae and Trimerocephalus lelievrei. The method of retrodeformation using a set of discrete points presumed to be homologous on all studied individuals, has demonstrated that the next analyses are possible on the retrodeformed material as compared to the undeformed material. Morphometric analysis based on outline analysis has permitted demonstration of progressive shape change in agreement with ontogenetic ordination and a comparison of changes in size and shape in Weyerites ensae. The main changes in shape appear to occur in the meraspid period, whereas increase in size takes place mainly in the holaspid period. This pattern, already reported for Trimerocephalus lelievrei, can be generalized for phacopine trilobites from the Late Devonian. Moreover, the comparison of the two ontogenetic trajectories has shown that most of the differences are related to ,structural' changes, probably linked to a relative pre- post-displacement. The results suggest that ecological adaptation may be studied by examining the changes in development that occur within species through time and space. [source] Prediction of the Bivariate Molecular Weight-Long Chain Branching Distribution in High-Pressure Low-Density Polyethylene AutoclavesMACROMOLECULAR THEORY AND SIMULATIONS, Issue 6 2007Apostolos Krallis Abstract In the present study a population balance approach is described to follow the time evolution of bivariate molecular weight-long chain branching (MW-LCB) distributions in high pressure low density polyethylene autoclaves. The model formulation is based on a sectional grid method, the so-called fixed pivot technique (FPT). According to this method, the ,live' and ,dead' polymer chain populations are assigned to a selected number of discrete points. Then, the resulting dynamic discrete-continuous molar species equations for ,live' and ,dead' polymer chains are solved at the specified grid points. It is shown that a very good agreement exists between theoretical results and experimental data which proves the capability of the FPT method in calculating the joint MW-LCB distribution for branched polymers. [source] Assessing the default risk by means of a discrete-time survival analysis approachAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 4 2008Daniele De Leonardis Abstract In this paper, the problem of company distress is assessed by means of a multi-period model that exploits the potentialities of the survival analysis approach when both survival times and regressors are measured at discrete points in time. The discrete-time hazards model can be used both as an empirical framework in the analysis of the causes of the deterioration process that leads to the default and as a tool for the prediction of the same event. Our results show that the prediction accuracy of the duration model is better than that provided by a single-period logistic model. It is also shown that the predictive power of the discrete-time survival analysis is enhanced when it is extended to allow for unobserved individual heterogeneity (frailty). Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||