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Wide Class (wide + class)
Selected AbstractsDimensional response analysis of yielding structures with first-mode dominated responseEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2006Nicos Makris Abstract This paper introduces a new way of estimating the inelastic response of first-mode dominated structures with behaviour that can be approximated with the elastoplastic idealization. The proposed approach emerges from formal dimensional analysis and is liberated from the response of the elastic system. The application of the proposed method hinges upon the existence of a distinct time scale and a length scale that characterize the most energetic component of the ground shaking. Such time and length scales emerge naturally from the distinguishable pulses which dominate a wide class of strong earthquake records; they are directly related with the rise time and slip velocity of faulting, and can be formally extracted with validated mathematical models published in the literature. The most decisive feature of this work is that the inelastic response curves that result with the proposed approach assume similar shapes for different values of the normalized yield displacement. Because of this similarity the paper proposes a single inelastic response curve which offers directly the maximum inelastic displacement of the structure given the energetic pulse period and pulse amplitude of the ground shaking. When the proposed method is applied to MDOF structures it is not capable to estimate interstorey drifts nor is capable to capture the effects of negative stiffness which may result due to P-delta effect. Copyright © 2006 John Wiley & Sons, Ltd. [source] Robust Predictions for Bilateral Contracting with ExternalitiesECONOMETRICA, Issue 3 2003Ilya Segal The paper studies bilateral contracting between one principal and N agents when each agent's utility depends on the principal's unobservable contracts with other agents. We show that allowing deviations to menu contracts from which the principal chooses bounds equilibrium outcomes in a wide class of bilateral contracting games without imposing ad hoc restrictions on the agents' beliefs. This bound yields, for example, competitive convergence as N ,, in environments in which an appropriately-defined notion of competitive equilibrium exists. We also examine the additional restrictions arising in two common bilateral contracting games: the "offer game" in which the principal makes simultaneous offers to the agents, and the "bidding game" in which the agents make simultaneous offers to the principal. [source] THE DIFFUSIVE SPREAD OF ALLELES IN HETEROGENEOUS POPULATIONSEVOLUTION, Issue 3 2004Garrick T. Skalski Abstract The spread of genes and individuals through space in populations is relevant in many biological contexts. I study, via systems of reaction-diffusion equations, the spatial spread of advantageous alleles through structured populations. The results show that the temporally asymptotic rate of spread of an advantageous allele, a kind of invasion speed, can be approximated for a class of linear partial differential equations via a relatively simple formula, c= 2,rD, that is reminiscent of a classic formula attributed to R. A. Fisher. The parameters r and D, represent an asymptotic growth rate and an average diffusion rate, respectively, and can be interpreted in terms of eigenvalues and eigenvectors that depend on the population's demographic structure. The results can be applied, under certain conditions, to a wide class of nonlinear partial differential equations that are relevant to a variety of ecological and evolutionary scenarios in population biology. I illustrate the approach for computing invasion speed with three examples that allow for heterogeneous dispersal rates among different classes of individuals within model populations. [source] A G space theory and a weakened weak (W2) form for a unified formulation of compatible and incompatible methods: Part I theoryINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2010G. R. Liu Abstract This paper introduces a G space theory and a weakened weak form (W2) using the generalized gradient smoothing technique for a unified formulation of a wide class of compatible and incompatible methods. The W2 formulation works for both finite element method settings and mesh-free settings, and W2 models can have special properties including softened behavior, upper bounds and ultra accuracy. Part I of this paper focuses on the theory and fundamentals for W2 formulations. A normed G space is first defined to include both continuous and discontinuous functions allowing the use of much more types of methods/techniques to create shape functions for numerical models. Important properties and a set of useful inequalities for G spaces are then proven in the theory and analyzed in detail. These properties ensure that a numerical method developed based on the W2 formulation will be spatially stable and convergent to the exact solutions, as long as the physical problem is well posed. The theory is applicable to any problems to which the standard weak formulation is applicable, and can offer numerical solutions with special properties including ,close-to-exact' stiffness, upper bounds and ultra accuracy. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dynamic stiffness for piecewise non-uniform Timoshenko column by power series,part II: Follower forceINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2001A. Y. T. Leung Abstract A follower force is an applied force whose direction changes according to the deformed shape during the course of deformation. The dynamic stiffness matrix of a non-uniform Timoshenko column under follower force is formed by the power-series method. The dynamic stiffness matrix is unsymmetrical due to the non-conservative nature of the follower force. The frequency-dependent mass matrix is still symmetrical and positive definite according to the extended Leung theorem. An arc length continuation method is introduced to find the influence of a concentrated follower force, distributed follower force, end mass and stiffness, slenderness, and taper ratio on the natural frequency and stability. It is found that the power-series method can handle a very wide class of dynamic stiffness problem. Copyright © 2001 John Wiley & Sons, Ltd. [source] Some recent finite volume schemes to compute Euler equations using real gas EOSINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2002T. Gallouët Abstract This paper deals with the resolution by finite volume methods of Euler equations in one space dimension, with real gas state laws (namely, perfect gas EOS, Tammann EOS and Van Der Waals EOS). All tests are of unsteady shock tube type, in order to examine a wide class of solutions, involving Sod shock tube, stationary shock wave, simple contact discontinuity, occurrence of vacuum by double rarefaction wave, propagation of a one-rarefaction wave over ,vacuum', , Most of the methods computed herein are approximate Godunov solvers: VFRoe, VFFC, VFRoe ncv (,, u, p) and PVRS. The energy relaxation method with VFRoe ncv (,, u, p) and Rusanov scheme have been investigated too. Qualitative results are presented or commented for all test cases and numerical rates of convergence on some test cases have been measured for first- and second-order (Runge,Kutta 2 with MUSCL reconstruction) approximations. Note that rates are measured on solutions involving discontinuities, in order to estimate the loss of accuracy due to these discontinuities. Copyright © 2002 John Wiley & Sons, Ltd. [source] Mixture-based adaptive probabilistic controlINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2 2003Miroslav Kárný Abstract Quasi-Bayes algorithm, combined with stabilized forgetting, provides a tool for efficient recursive estimation of dynamic probabilistic mixture models. They can be interpreted either as models of closed-loop with switching modes and controllers or as a universal approximation of a wide class of non-linear control loops. Fully probabilistic control design extended to mixture models makes basis of a powerful class of adaptive controllers based on the receding-horizon certainty equivalence strategy. Paper summarizes the basic elements mentioned above, classifies possible types of control problems and provides solution of the key one referred to as ,simultaneous' design. Results are illustrated on mixtures with components formed by normal auto-regression models with external variable (ARX). Copyright © 2003 John Wiley & Sons, Ltd. [source] Limit cycle computation for describing function approximable nonlinear systems with box-constrained parametric uncertaintiesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2005P. S. V. Nataraj Abstract We propose an algorithm to compute the limit cycle set of uncertain non-rational nonlinear systems with nonlinear parametric dependencies. The proposed algorithm computes the limit cycles for a wide class of uncertain nonlinear systems, where the transfer function of the linear element and describing function of the nonlinear element need to be only continuous with respect to the parameters and continuously differentiable with respect to the amplitude and frequency of periodic input signal. The proposed algorithm guarantees that the limit cycles are reliably computed to a prescribed accuracy, and that none of the actual limit cycle point is missed out irrespective of the tightness of the prescribed accuracy. Moreover, for a prescribed accuracy, the proposed algorithm computes all the limit cycles in a finite number of iterations, and an upper bound for this number is also computable. The algorithm is demonstrated on a challenging non-rational example with nonlinear parametric dependencies. Copyright © 2005 John Wiley & Sons, Ltd. [source] THE EQUAL ABSOLUTE SACRIFICE PRINCIPLE REVISITEDJOURNAL OF ECONOMIC SURVEYS, Issue 2 2009Peter J. Lambert Abstract We summarize the literature on equal absolute sacrifice income taxes, and make some extensions. We adapt the utilitarian equal sacrifice criterion to a wide class of rank-dependent social welfare functions, and find that liabilities depend on both income and position in the distribution. We investigate whether such taxes need be progressive, using a combination of analytics and simulation, and in the process uncover tax functions not previously recognized as equating sacrifices. Finally, out of horizontal equity considerations a new concept of ,the equal treatment of equals' by an income tax emerges, with implications for future work whose significance is discussed. [source] Public Goods Provision: On Generalizing the Jackson,Moulin MechanismJOURNAL OF PUBLIC ECONOMIC THEORY, Issue 1 2006YAN YU Jackson and Moulin (1992) proposed a simple mechanism to implement a wide class of cost-sharing rules for the provision of a binary public good. Bag (1997) generalized this mechanism to divisible public goods under the assumption of "constant marginal benefit." This paper generalizes the Jackson,Moulin mechanism to a broader setting, including the cases of both decreasing and constant marginal benefit. Moreover, this paper shows the impossibility of generalizing the mechanism further. [source] Inferences from DNA data: population histories, evolutionary processes and forensic match probabilitiesJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 2 2003Ian J. Wilson Summary. We develop a flexible class of Metropolis,Hastings algorithms for drawing inferences about population histories and mutation rates from deoxyribonucleic acid (DNA) sequence data. Match probabilities for use in forensic identification are also obtained, which is particularly useful for mitochondrial DNA profiles. Our data augmentation approach, in which the ancestral DNA data are inferred at each node of the genealogical tree, simplifies likelihood calculations and permits a wide class of mutation models to be employed, so that many different types of DNA sequence data can be analysed within our framework. Moreover, simpler likelihood calculations imply greater freedom for generating tree proposals, so that algorithms with good mixing properties can be implemented. We incorporate the effects of demography by means of simple mechanisms for changes in population size and structure, and we estimate the corresponding demographic parameters, but we do not here allow for the effects of either recombination or selection. We illustrate our methods by application to four human DNA data sets, consisting of DNA sequences, short tandem repeat loci, single-nucleotide polymorphism sites and insertion sites. Two of the data sets are drawn from the male-specific Y-chromosome, one from maternally inherited mitochondrial DNA and one from the , -globin locus on chromosome 11. [source] Proportion of non-zero normal means: universal oracle equivalences and uniformly consistent estimatorsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 3 2008Jiashun Jin Summary., Since James and Stein's seminal work, the problem of estimating n normal means has received plenty of enthusiasm in the statistics community. Recently, driven by the fast expansion of the field of large-scale multiple testing, there has been a resurgence of research interest in the n normal means problem. The new interest, however, is more or less concentrated on testing n normal means: to determine simultaneously which means are 0 and which are not. In this setting, the proportion of the non-zero means plays a key role. Motivated by examples in genomics and astronomy, we are particularly interested in estimating the proportion of non-zero means, i.e. given n independent normal random variables with individual means Xj,N(,j,1), j=1,,,n, to estimate the proportion ,n=(1/n) #{j:,j /= 0}. We propose a general approach to construct the universal oracle equivalence of the proportion. The construction is based on the underlying characteristic function. The oracle equivalence reduces the problem of estimating the proportion to the problem of estimating the oracle, which is relatively easier to handle. In fact, the oracle equivalence naturally yields a family of estimators for the proportion, which are consistent under mild conditions, uniformly across a wide class of parameters. The approach compares favourably with recent works by Meinshausen and Rice, and Genovese and Wasserman. In particular, the consistency is proved for an unprecedentedly broad class of situations; the class is almost the largest that can be hoped for without further constraints on the model. We also discuss various extensions of the approach, report results on simulation experiments and make connections between the approach and several recent procedures in large-scale multiple testing, including the false discovery rate approach and the local false discovery rate approach. [source] Nonlinear functionals of the periodogramJOURNAL OF TIME SERIES ANALYSIS, Issue 5 2002GILLES FAY A central limit theorem is stated for a wide class of triangular arrays of nonlinear functionals of the periodogram of a stationary linear sequence. Those functionals may be singular and not-bounded. The proof of this result is based on Bartlett decomposition and an existing counterpart result for the periodogram of an independent and identically distributed sequence, here taken to be the driving noise. The main contribution of this paper is to prove the asymptotic negligibility of the remainder term from Bartlett decomposition, feasible under short dependence assumption. As it is highlighted by applications (to estimation of nonlinear functionals of the spectral density, robust spectral estimation, local polynomial approximation and log-periodogram regression), this extends may results until then tied to Gaussian assumption. [source] Time Changes for Lévy ProcessesMATHEMATICAL FINANCE, Issue 1 2001Hélyette Geman The goal of this paper is to consider pure jump Lévy processes of finite variation with an infinite arrival rate of jumps as models for the logarithm of asset prices. These processes may be written as time-changed Brownian motion. We exhibit the explicit time change for each of a wide class of Lévy processes and show that the time change is a weighted price move measure of time. Additionally, we present a number of Lévy processes that are analytically tractable, in their characteristic functions and Lévy densities, and hence are relevant for option pricing. [source] A limiting absorption principle for scattering problems with unbounded obstaclesMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 14 2001Anne-Sophie Bonnet-Bendhia Abstract A generalized mode matching method that applies to a wide class of scattering problems is developed in the time harmonic two-dimensional Helmholtz case. This method leads by variational means to an integro-differential formulation whose unknown is the trace of the field on an unbounded one-dimensional interface. The well-posedness is proved after a careful study of the rather original functional framework. Owing to a fundamental density result,based upon some properties of a singular integral operator similar to the Hilbert transform,the limiting absorption principle related to this original formulation is established. Finally, two other situations are emphasized. Copyright © 2001 John Wiley & Sons, Ltd. [source] Natural gas storage valuation and optimization: A real options applicationNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 3 2009Matt Thompson Abstract In this article, we present an algorithm for the valuation and optimal operation of natural gas storage facilities. Real options theory is used to derive nonlinear partial-integro-differential equations (PIDEs), the solution of which give both valuation and optimal operating strategies for these facilities. The equations are designed to incorporate a wide class of spot price models that can exhibit the same time-dependent, mean-reverting dynamics, and price spikes as those observed in most energy markets. Particular attention is paid to the operational characteristics of real storage units. These characteristics include working gas capacities, variable deliverability and injection rates, and cycling limitations. We illustrate the model with a numerical example of a salt cavern storage facility that clearly shows how a gas storage facility is like a financial straddle with both put and call properties. Depending on the amount of gas in storage the relative influence of the put and call components vary. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009 [source] Robust parameter-free algebraic multilevel preconditioningNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 6-7 2002Y. Notay Abstract To precondition large sparse linear systems resulting from the discretization of second-order elliptic partial differential equations, many recent works focus on the so-called algebraic multilevel methods. These are based on a block incomplete factorization process applied to the system matrix partitioned in hierarchical form. They have been shown to be both robust and efficient in several circumstances, leading to iterative solution schemes of optimal order of computational complexity. Now, despite the procedure is essentially algebraic, previous works focus generally on a specific context and consider schemes that use classical grid hierarchies with characteristic mesh sizes h,2h,4h, etc. Therefore, these methods require some extra information besides the matrix of the linear system and lack of robustness in some situations where semi-coarsening would be desirable. In this paper, we develop a general method that can be applied in a black box fashion to a wide class of problems, ranging from 2D model Poisson problems to 3D singularly perturbed convection,diffusion equations. It is based on an automatic coarsening process similar to the one used in the AMG method, and on coarse grid matrices computed according to a simple and cheap aggregation principle. Numerical experiments illustrate the efficiency and the robustness of the proposed approach. Copyright © 2002 John Wiley & Sons, Ltd. [source] Peculiar band gap structure of graphene nanoribbonsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007Motohiko Ezawa Abstract Graphene nanoribbons are quasi-one-dimensional meterials with finite width. Characterizing a wide class of nanoribbons by edge shape and width, we make a systematic analysis of their electronic properties. The band gap structure of nanoribbons is shown to exhibit a valley structure with stream-like sequences of metallic or almost metallic nanoribbons. Among them, all zigzag nanoribbons are metallic, and armchair nanoribbons are metallic by period of 3. We find that these stream-like sequences correspond to equi-width curves, and that the band gap of chiral and armchair nanoribbons oscillate as a function of the width. Furthermore a possible application of nanoribbons to nanoelectronics is discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Varieties of Faith-Related AgenciesPUBLIC ADMINISTRATION REVIEW, Issue 6 2001Steven Rathgeb Smith Although some recent literature suggests religious social service agencies can help governments reach important social program goals, the true social organization and services of the agencies remain in dispute. This article interviews officials in the wide class of "faith-related" agencies in two cities to consider two aspects of this issue: the ties or "coupling" of agencies to faith, and the impact of coupling on agency structure and service programming. The results suggest that many sampled agencies are loosely tied to faith in terms of resources, more tightly coupled in terms of authority, and moderately coupled with respect to culture; that certain aspects of service-delivery technology are heavily secularized in many agencies; that faith is more influential in such matters as the agencies' choices of services; and that the larger, potentially more secularized agencies that might be least likely to be characterized as faith based balance differing sets of resources and thereby can more fully deliver services that arguably express faith in action. Given this finding and that most agencies profess a focus on protecting the dignity and rights of clients rather than on individual responsibility or other themes that are stressed by some recent policy proposals, governments need to be extremely selective in funding agencies to promote those proposals' themes. [source] Consumption, Aggregate Wealth, and Expected Stock ReturnsTHE JOURNAL OF FINANCE, Issue 3 2001Martin Lettau This paper studies the role of fluctuations in the aggregate consumption,wealth ratio for predicting stock returns. Using U.S. quarterly stock market data, we find that these fluctuations in the consumption,wealth ratio are strong predictors of both real stock returns and excess returns over a Treasury bill rate. We also find that this variable is a better forecaster of future returns at short and intermediate horizons than is the dividend yield, the dividend payout ratio, and several other popular forecasting variables. Why should the consumption,wealth ratio forecast asset returns? We show that a wide class of optimal models of consumer behavior imply that the log consumption,aggregate wealth (human capital plus asset holdings) ratio summarizes expected returns on aggregate wealth, or the market portfolio. Although this ratio is not observable, we provide assumptions under which its important predictive components for future asset returns may be xpressed in terms of observable variables, namely in terms of consumption, asset holdings and labor income. The framework implies that these variables are cointegrated, and that deviations from this shared trend summarize agents' expectations of future returns on the market portfolio. [source] H2 -OPTIMAL SAMPLED-DATA CONTROL FOR PLANTS WITH MULTIPLE INPUT AND OUTPUT DELAYSASIAN JOURNAL OF CONTROL, Issue 2 2006Konstantin Yu. ABSTRACT The sampled-data H2 -optimization problem for plants with multiple input and output delays is considered. An equivalent discrete-time system is constructed and numerical algorithm for computing matrices of its state-space realization is presented. It is proved that stability of this system is equivalent to stability of original sampled-data system. The proposed method can be applied to a wide class of digital control problems for continuous-time plants with multiple input and output delays. [source] R&D Subsidies versus R&D Cooperation in a Duopoly with Spillovers and PollutionAUSTRALIAN ECONOMIC PAPERS, Issue 1 2002Emmanuel Petrakis We introduce pollution, as a by-product of production, into a non-tournament model of R&D with spillovers. Technology policy takes the form of either R&D subsidisation or pre-competitive R&D cooperation. We show that, when the emissions tax is exogenous, the optimal R&D subsidy can be negative, i.e. there should be a tax on R&D, depending on the extent of the appropriability problem and the degree of environmental damage. In a wide class of cases, depending on the parameter values, welfare in the case of R&D cooperation, is lower than welfare in the case of R&D subsidisation. [source] Quantitative steps in symbiogenesis and the evolution of homeostasisBIOLOGICAL REVIEWS, Issue 3 2003S. A. L. M. KOOIJMAN ABSTRACT The merging of two independent populations of heterotrophs and autotrophs into a single population of mixotrophs has occurred frequently in evolutionary history. It is an example of a wide class of related phenomena, known as symbiogenesis. The physiological basis is almost always (reciprocal) syntrophy, where each species uses the products of the other species. Symbiogenesis can repeat itself after specialization on particular assimilatory substrates. We discuss quantitative aspects and delineate eight steps from two free-living interacting populations to a single fully integrated endosymbiotic one. The whole process of gradual interlocking of the two populations could be mimicked by incremental changes of particular parameter values. The role of products gradually changes from an ecological to a physiological one. We found conditions where the free-living, epibiotic and endobiotic populations of symbionts can co-exist, as well as conditions where the endobiotic symbionts outcompete other symbionts. Our population dynamical analyses give new insights into the evolution of cellular homeostasis. We show how structural biomass with a constant chemical composition can evolve in a chemically varying environment if the parameters for the formation of products satisfy simple constraints. No additional regulation mechanisms are required for homeostasis within the context of the dynamic energy budget (DEB) theory for the uptake and use of substrates by organisms. The DEB model appears to be closed under endosymbiosis. This means that when each free-living partner follows DEB rules for substrate uptake and use, and they become engaged in an endosymbiotic relationship, a gradual transition to a single fully integrated system is possible that again follows DEB rules for substrate uptake and use. [source] Linear vs. nonlinear selection for the propagation speed of the solutions of scalar reaction-diffusion equations invading an unstable equilibriumCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 5 2004Marcello Lucia We revisit the classical problem of speed selection for the propagation of disturbances in scalar reaction-diffusion equations with one linearly stable and one linearly unstable equilibrium. For a wide class of initial data this problem reduces to finding the minimal speed of the monotone traveling wave solutions connecting these two equilibria in one space dimension. We introduce a variational characterization of these traveling wave solutions and give a necessary and sufficient condition for linear versus nonlinear selection mechanism. We obtain sufficient conditions for the linear and nonlinear selection mechanisms that are easily verifiable. Our method also allows us to obtain efficient lower and upper bounds for the propagation speed. © 2004 Wiley Periodicals, Inc. [source] | |||||||||||||||||||