collocation methods for the solution of von karman dynamic non linear plate systems the von karman nonlinear dynamic partial differential system over rectangular domains is considered and numerically solved using both the chebyshev collocation and legendre collocation methods for the spatial discretization and the implicit newmark scheme combined with a non linear fixed point algorithm for the temporal discretization as the system is non linear involving operators of different orders different timescales and may contain initial boundary incompatible conditions at the domain s corners it is our aim to highlight some of the difficulties inherent in its numerical treatment using collocation methods we begin by examining the chebyshev collocation scheme considered in comput meth appl mech engrg 193 6 8 2004 575 in that work filtering was used to stabilize the full von karman system however the source of the instability was not discussed we first show that ic bc incompatibilities are not the culprits and demonstrate empirically that the source of the instability was the numerical treatment of the linear cross derivative terms found in the in plane equations we prove mathematically that although the continuous linear system is well posed the chebyshev collocation solution of problems involving cross derivatives and second order time derivatives is unstable instead of adding sufficient filtering to counter the energy growth due to the linear terms we employ the legendre collocation method we show empirically and prove that the legendre collocation scheme for the linear system has the necessary characteristics to remain stable nevertheless the collocation treatment of the non linear terms still causes the solution to be unstable at long time we thus return to advocating a filtering solution but in this case only filtering the non linear terms to compensate for the inherent aliasing error due to our collocation treatment of these terms we conclude by comparing the results of filtered chebyshev collocation solution non linear terms filtered legendre collocation solution and a simplified von karman solution omitting the inertial terms in the in plane equations as presented in loc cit

continuous time relaxation labeling processes abstract we study the dynamical properties of two new relaxation labeling schemes described in terms of differential equations and hence evolving in continuous time this contrasts with the customary approach to defining relaxation labeling algorithms which prefers discrete time continuous time dynamical systems are particularly attractive because they can be implemented directly in hardware circuitry and the study of their dynamical properties is simpler and more elegant they are also more plausible as models of biological visual computation we prove that the proposed models enjoy exactly the same dynamical properties as the classical relaxation labeling schemes and show how they are intimately related to hummel and zucker s now classical theory of constraint satisfaction in particular we prove that when a certain symmetry condition is met the dynamical systems behavior is governed by a liapunov function which turns out to be the negative of a well known consistency measure moreover we prove that the fundamental dynamical properties of the systems are retained when the symmetry restriction is relaxed we also analyze the properties of a simple discretization of the proposed dynamics which is useful in digital computer implementations simulation results are presented which show the practical behavior of the models

stability and vibration of thick laminated composite sector plates this study presents a simple analytical formulation for the eigenvalue problem of buckling and free vibration analysis of shear deformable laminated sector plates made up of cylindrically orthotropic layers the non axisymmetric formulation in cylindrical coordinates is discretized in space domain in terms of two dimensional chebyshev polynomials several combinations of simply supported clamped and free edge conditions are considered convergence study has been carried out and the obtained results are compared with the results of laminated square plates and isotropic sector plates available in literature extensive results pertaining to critical buckling loads and natural frequencies are presented effects of boundary conditions number of layers moduli ratio rotary and in plane inertia plate thickness sector angle and annularity are studied

using choquet integral as preference model in interactive evolutionary multiobjective optimization we propose an interactive multiobjective evolutionary algorithm that attempts to discover the most preferred part of the pareto optimal set preference information is elicited by asking the user to compare some solutions pairwise this information is then used to curb the set of compatible user s value functions and the multiobjective evolutionary algorithm is run to simultaneously search for all solutions that could potentially be the most preferred compared to previous similar approaches we implement a much more efficient way of determining potentially preferred solutions that is solutions that are best for at least one value function compatible with the preference information provided by the decision maker for the first time in the context of evolutionary computation we apply the choquet integral as a user s preference model allowing us to capture interactions between objectives as there is a trade off between the flexibility of the value function model and the complexity of learning a faithful model of user s preferences we propose to start the interactive process with a simple linear model but then to switch to the choquet integral as soon as the preference information can no longer be represented using the linear model an experimental analysis demonstrates the effectiveness of the approach

g dominance reference point based dominance for multiobjective metaheuristics abstract one of the main tools for including decision maker dm preferences in the multiobjective optimization mo literature is the use of reference points and achievement scalarizing functions a p wierzbicki the use of reference objectives in multiobjective optimization in g fandel t gal eds multiple criteria decision making theory and application springer verlag new york 1980 pp 469 486 the core idea in these approaches is converting the original mo problem into a single objective optimization problem through the use of a scalarizing function based on a reference point as a result a single efficient point adapted to the dm s preferences is obtained however a single solution can be less interesting than an approximation of the efficient set around this area as stated for example by deb in k deb j sundar n udaya bhaskara rao s chaudhuri reference point based multiobjective optimization using evolutionary algorithms international journal of computational intelligence research 2 3 2006 273 286 in this paper we propose a variation of the concept of pareto dominance called g dominance which is based on the information included in a reference point and designed to be used with any mo evolutionary method or any mo metaheuristic this concept will let us approximate the efficient set around the area of the most preferred point without using any scalarizing function on the other hand we will show how it can be easily used with any mo evolutionary method or any mo metaheuristic just changing the dominance concept and to exemplify its use we will show some results with some state of the art methods and some test problems

an interactive evolutionary multi objective optimization algorithm with a limited number of decision maker calls this paper presents a preference based method to handle optimization problems with multiple objectives with an increase in the number of objectives the computational cost in solving a multi objective optimization problem rises exponentially and it becomes increasingly difficult for evolutionary multi objective techniques to produce the entire pareto optimal front in this paper an evolutionary multi objective procedure is combined with preference information from the decision maker during the intermediate stages of the algorithm leading to the most preferred point the proposed approach is different from the existing approaches as it tries to find the most preferred point with a limited budget of decision maker calls in this paper we incorporate the idea into a progressively interactive technique based on polyhedral cones the idea is also tested on another progressively interactive approach based on value functions results are provided on two to five objective unconstrained as well as constrained test problems

evolutionary algorithms with preference polyhedron for interval multi objective optimization problems multi objective optimization problems mops with interval parameters are ubiquitous in real world applications existing evolutionary optimization methods however aim to obtain a set of well converged and evenly distributed pareto optimal solutions in this paper we presented a novel evolutionary algorithm ea that interacts with a decision maker dm during the optimization process to obtain the most preferred solution the theory of preference polyhedron for the optimization problem with interval parameters was developed first an interactive evolutionary algorithm iea for mops with interval parameters was then proposed based on the theory of preference polyhedron the algorithm periodically provides a set of non dominated solutions to the dm a preference polyhedron is constructed in the objective space by taking the worst solution chosen by the dm as the vertex the solutions with the same rank are sorted based on the polyhedron constructed finally our method was empirically evaluated on several mops with interval parameters where the value functions were used to simulate the dm s responses the numerical results indicated that our method is simpler and more efficient than the a posteriori method

relaxation labeling using augmented lagrange hopfield method a novel relaxation labeling rl method is presented based on augmented lagrangian multipliers and the graded hopfield neural network alh in this method an rl problem is converted into a constrained optimization problem and solved by using the augmented lagrangian and hopfield techniques the alh method yields results comparable to the best of the existing rl algorithms in terms of the optimized objective values yet it is more suitable for analog neural implementation experimental results are presented

3 d vibration analysis of annular sector plates using the chebyshev ritz method abstract the three dimensional free vibration of annular sector plates with various boundary conditions is studied by means of the chebyshev ritz method the analysis is based on the three dimensional small strain linear elasticity theory the product of chebyshev polynomials satisfying the necessary boundary conditions is selected as admissible functions in such a way that the governing eigenvalue equation can be conveniently derived through an optimization process by the ritz method the boundary functions guarantee the satisfaction of the geometric boundary conditions of the plates and the chebyshev polynomials provide the robustness for numerical calculation the present study provides a full vibration spectrum for the thick annular sector plates which cannot be given by the two dimensional 2 d theories such as the mindlin theory comprehensive numerical results with high accuracy are systematically produced which can be used as benchmark to evaluate other numerical methods the effect of radius ratio thickness ratio and sector angle on natural frequencies of the plates with a sector angle from 120 to 360 is discussed in detail the three dimensional vibration solutions for plates with a re entrant sector angle larger than 180 and shallow helicoidal shells sector angle larger than 360 with a small helix angle are presented for the first time

generalized lexicographic multiobjective combinatorial optimization application to cryptography this paper formalizes a family of prioritized multicriteria optimization problems and assesses the corresponding up to date known suboptimal solutions the resulting framework is then employed to characterize and search for boolean functions which are valuable for a robust symmetric mainly block cipher design the proposed optimality definitions generalize the lexicographic method by establishing an ordered sequence of multiobjective combinatorial optimization problems which in turn gathers the relative relevance of the criteria so that the optimal solutions can be obtained from a sequential application of the pareto efficiency the relationship among the different formulable problems is characterized in terms of both their respective solutions sets and computing costs since in practice only a limited set of functions can be evaluated i e are known the best known pareto efficient functions are also defined finally this framework is employed to obtain new functions having known pareto max

the ipicea g a new hybrid evolutionary multi criteria decision making approach using the brushing technique various preference based multi objective evolutionary algorithms have been developed to help a decision maker search for his her preferred solutions to multi objective problems in most of the existing approaches the decision maker preferences are formulated either by mathematical expressions such as the utility function or simply by numerical values such as aspiration levels and weights however in some sense a decision maker may find it easier to specify preferences visually by drawing rather than using numbers this paper introduces such a method namely the brushing technique using this technique the decision maker can specify his her preferences easily by drawing in the objective space combining the brushing technique with one existing algorithm picea g we present a novel approach named ipicea g for an interactive decision making the performance of ipicea g is tested on a set of benchmark problems and is shown to be good

solving the discrete multiple criteria problem using convex cones an interactive method employing pairwise comparisons of attainable solutions is developed for solving the discrete deterministic multiple criteria problem assuming a single decision maker who has an implicit quasi concave increasing utility or value function the method chooses an arbitrary set of positive multipliers to generate a proxy composite linear objective function which is then maximized over the set of solutions the maximizing solution is compared with several solutions using pairwise judgments asked of the decision maker responses are used to eliminate alternatives using convex cones based on expressed preferences and then a new set of weights is found that satisfies the indicated preferences the requisite theory and proofs as well as a detailed numerical example are included in addition the results of some computational experiments to test the effectiveness of the method are described

in plane and shear buckling analysis of fg cntrc annular sector plates based on the third order shear deformation theory using a numerical approach abstract the buckling analysis of thick composite annular sector plates reinforced with functionally graded carbon nanotubes cnts is presented under in plane and shear loadings based on the higher order shear deformation theory it is considered that the plate is resting on the pasternak type elastic foundation the overall material properties of functionally graded carbon nanotube reinforced composites fg cntrcs are estimated through the micromechanical model the governing equations are derived on the basis of the higher order shear deformation plate theory and the quadratic form of the energy functional of the system is presented an efficient numerical method is presented in the context of variational formulation to obtain the discretized version of stability equations the validation of the present study is demonstrated through comparisons with the results available in the literature and then comprehensive numerical results are given to investigate the impacts of model parameters on the stability of cnt reinforced composite annular sector plates

approximating the maximum weight clique using replicator dynamics given an undirected graph with weights on the vertices the maximum weight clique problem mwcp is to find a subset of mutually adjacent vertices a clique having the largest total weight this is a generalization of the problem of finding the maximum cardinality clique of an unweighted graph which is the special case of the mwcp when all vertex weights are equal the problem is np hard for arbitrary graphs and so is the problem of approximating it within a constant factor we present a parallel distributed heuristic for approximating the mwcp based on dynamics principles it centers around a continuous characterization of the mwcp a purely combinatorial problem and lets it be formulated in terms of continuous quadratic programming one drawback is the presence of spurious solutions and we present their characterizations to avoid them we introduce a regularized continuous formulation of the mwcp and show how it completely solves the problem the formulation naturally maps onto a parallel distributed computational network whose dynamical behavior is governed by the replicator equations these are dynamical systems introduced in evolutionary game theory and population genetics to model evolutionary processes on a macroscopic scale we present theoretical results which guarantee that the solutions provided by our clique finding replicator network are actually those sought experimental results confirm the effectiveness of the proposed approach

on the foundations of relaxation labeling processes a large class of problems can be formulated in terms of the assignment of labels to objects frequently processes are needed which reduce ambiguity and noise and select the best label among several possible choices relaxation labeling processes are just such a class of algorithms they are based on the parallel use of local constraints between labels this paper develops a theory to characterize the goal of relaxation labeling the theory is founded on a definition of con sistency in labelings extending the notion of constraint satisfaction in certain restricted circumstances an explicit functional exists that can be maximized to guide the search for consistent labelings this functional is used to derive a new relaxation labeling operator when the restrictions are not satisfied the theory relies on variational cal culus it is shown that the problem of finding consistent labelings is equivalent to solving a variational inequality a procedure nearly identical to the relaxation operator derived under restricted circum stances serves in the more general setting further a local convergence result is established for this operator the standard relaxation labeling formulas are shown to approximate our new operator which leads us to conjecture that successful applications of the standard methods are explainable by the theory developed here observations about con vergence and generalizations to higher order compatibility relations are described

chebyshev series solution to non linear boundary value problems in rectangular domain abstract the von karman equations governing the behavior of moderately large deformations of rectangular plates are expressed in displacement field a methodology based on chebyshev polynomials approximation to analyze the non linear boundary value problems in rectangular domain is developed these non linear partial differential equations of motion are linearized using quadratic extrapolation techniques the inertia and dissipative terms are evaluated by employing houbolt implicit time marching scheme the spatial discretization of the differential equations generates incompatibility viz greater number of equations than the unknowns the multiple linear regression analysis based on the least square error norm is employed to overcome the incompatibility and a compatible solution is obtained convergence study has been carried out the clamped and simply supported immovable rectangular plates subjected to static and dynamic loadings are analyzed results have been compared with the results obtained by other numerical and analytical methods

free and forced vibrations of plates by boundary and interior elements a direct boundary element method is developed for the dynamic analysis of thin elastic flexural plates of arbitrary planform and boundary conditions the formulation employs the static fundamental solution of the problem and this creates not only boundary integrals but surface integrals as well owing to the presence of the inertia force thus the discretization consists of boundary as well as interior elements quadratic isoparametric elements and quadratic isoparametric or constant elements are employed for the boundary and interior discretization respectively both free and forced vibrations are considered the free vibration problem is reduced to a matrix eigenvalue problem with matrix coefficients independent of frequency the forced vibration problem is solved with the aid of the laplace transform with respect to time and this requires a numerical inversion of the transformed solution to obtain the plate dynamic response to arbitrary transient loading the effect of external viscous or internal viscoelastic damping on the response is also studied the proposed method is compared against the direct boundary element method in conjunction with the dynamic fundamental solution as well as the finite element method primarily by means of a number of numerical examples these examples also serve to illustrate the use of the proposed method

solution of von karman dynamic non linear plate equations using a pseudo spectral method abstract the von karman non linear dynamic partial differential system over rectangular domains is solved by the chebyshev collocation method in space and the implicit newmark time marching scheme in time in the newmark scheme a non linear fixed point iteration algorithm is employed we monitor both temporal and spatial discretization errors based on derived analytical solutions demonstrating highly accurate approximations we also quantify the influence of a common modeling assumption which neglects the in plane inertia terms in the full von karman system demonstrating that it is justified a comparison of our steady state von karman solutions to previous results in the literature and to a three dimensional high order finite element analysis is performed showing an excellent agreement other modeling assumptions such as neglecting in plane quadratic terms in the strain expressions are also addressed

on the free transverse vibration of annular and circular thin sectorial plates subject to certain complicating effects abstract the rayleigh ritz method with orthogonally generated polynomials as admissible functions is used to obtain an eigenvalue equation for the free transverse vibration of thin annular sectorial plates circular sectorial plates are treated with this equation by permitting the inner radius to become negligibly small the plates may be of isotropic or polar orthotropic material of uniform or radially and or circumferentially varying thickness and may include interior circumferential or radial line supports numerical values for the natural frequency parameters of several different plates are presented and compared with previously published values where available

group aggregation of pairwise comparisons using multi objective optimization in group decision making multiple decision makers dms aim to reach a consensus ranking of alternatives in a decision problem the differing expertise experience and potentially conflicting interests of the dms will result in the need for some form of conciliation to achieve consensus pairwise comparisons are commonly used to elicit values of preference of a dm the aggregation of the preferences of multiple dms must additionally consider potential conflict between dms and how these conflicts may result in a need for compromise to reach group consensus we present an approach to aggregating the preferences of multiple dms utilizing multi objective optimization to derive and highlight underlying conflict between the dms when seeking to achieve consensus extracting knowledge of conflict facilitates both traceability and transparency of the trade offs involved when reaching a group consensus further the approach incorporates inconsistency reduction during the aggregation process to seek to diminish adverse effects upon decision outcomes the approach can determine a single final solution based on either global compromise information or through utilizing weights of importance of the dms within multi criteria decision making we present a case study within the analytical hierarchy process from which we derive a richer final ranking of the decision alternatives

differential quadrature method for vibration analysis of shear deformable annular sector plates this paper presents differential quadrature solutions for free vibration analysis of moderately thick annular sector plates based on the mindlin first order shear deformation theory numerical characteristics of the differential quadrature method are illustrated through solving selected annular sector plates with different boundary conditions relative thickness ratios inner to outer radius ratios and various sector angles parametric studies in terms of the vibration frequency parameters are thoroughly investigated

stability and vibration of mindlin sector plates an analytical approach this study presents a simple analytical formulation for the eigenvalue problem of buckling and free vibration analysis of mindlin sector plates the nonaxisymmetric formulation in cylindrical coordinates is discretized in the space domain in terms of two dimensional chebyshev polynomials the formulation facilitates application of several combinations of simply supported clamped and free edge conditions convergence study has been carried out and the obtained results are compared with those available in the literature extensive results pertaining to critical buckling loads and natural frequencies are presented effects of boundary conditions plate thickness and annularity are studied

relaxation labeling algorithm for information integration and its convergence relaxation labeling is an iterative and parallel processing scheme which has been used to implement information integration in the framework of relaxation labeling two sources of given information is encoded in a form of constraints and that of certainty measures of the labels respectively with this formulation the information integration is implemented by the relaxation operator by forcing neighborhood constraint satisfaction various versions of relaxation labeling algorithm have been proposed by other researchers and their applications to image processing scene analysis object identification have produced satisfactory and partially satisfactory results in the past as an iterative algorithm the convergence properties of relaxation labeling have been investigated by some researchers a new relaxation labeling algorithm is developed and presented in this paper the motivation as well as the performance of the new algorithm is discussed its local and global convergence properties are established analytically and numerically it is also demonstrated that the convergence analysis of the new algorithm can be easily generalized

interactive evolutionary multi objective optimization for quasi concave preference functions we present a new hybrid approach to interactive evolutionary multi objective optimization that uses a partial preference order to act as the fitness function in a customized genetic algorithm we periodically send solutions to the decision maker dm for her evaluation and use the resulting preference information to form preference cones consisting of inferior solutions the cones allow us to implicitly rank solutions that the dm has not considered this technique avoids assuming an exact form for the preference function but does assume that the preference function is quasi concave this paper describes the genetic algorithm and demonstrates its performance on the multi objective knapsack problem

general geometric good continuation from taylor to laplace via level sets good continuation is the gestalt observation that parts often group in particular ways to form coherent wholes perceptual integration of edges for example involves orientation good continuation a property which has been exploited computationally very extensively but more general local global relationships such as for shading or color have been elusive while taylor s theorem suggests certain modeling and smoothness criteria the consideration of level set geometry indicates a different approach using such first principles we derive for the first time a generalization of good continuation to all those visual structures that can be abstracted as scalar functions over the image plane based on second order differential constraints that reflect good continuation our analysis leads to a unique class of harmonic models and a cooperative algorithm for structure inference among the different applications of good continuation here we apply these results to the denoising of shading and intensity distributions and demonstrate how our approach eliminates spurious measurements while preserving both singularities and regular structure a property that facilitates higher level processes which depend so critically on both of these classes of visual structures

multiple criteria decision making multiattribute utility theory the next ten years management science and decision science have grown exponentially since midcentury two closely related fields central to this growth are multiple criteria decision making mcdm and multiattribute utility theory maut this paper comments on the history of mcdm and maut and discusses topics we believe are important in their continued development and usefulness to management science over the next decade our aim is to identify exciting directions and promising areas for future research

an interactive evolutionary metaheuristic for multiobjective combinatorial optimization we propose an evolutionary metaheuristic for multiobjective combinatorial optimization problems that interacts with the decision maker dm to guide the search effort toward his or her preferred solutions solutions are presented to the dm whose pairwise comparisons are then used to estimate the desirability or fitness of newly generated solutions the evolutionary algorithm comprising the skeleton of the metaheuristic makes use of selection strategies specifically designed to address the multiobjective nature of the problem interactions with the dm are triggered by a probabilistic evaluation of estimated fitnesses while memory structures with indifference thresholds restrict the presentation of solutions resembling those that have already been rejected the algorithm has been tested on a number of random instances of the multiobjective knapsack problem mokp and the multiobjective spanning tree problem most simulation results indicate that the algorithm requires only a small number of comparisons to be made for satisfactory solutions to be found