Experimental Investigation of Elastodissipative Characteristics of Carbon-Fiber-Reinforced Plastics

A procedure is described for the experimental study of elastodissipative properties of carbon-fiber-reinforced plastic (CFRP) structures. Experimental values of dissipation factors are given for angle-ply structures with a reinforcing angle varying from 0 to 90°. Elastodissipative characteristics of two types of CFRP are identified. The values obtained can be used for predicting the properties of complex CFRP structures. It is shown that the energy absorption in sandwich structures with CFRP skins and a honeycomb core is mainly governed by properties of the skins.     

Handling the valuation of the predicates in a fuzzy model

Given a fuzzy model, and therefore a graded valuation of the predicates, several handlings of such a valuation are possible. For example, we can change the set of truth values, modify the scale, cut the predicates, and identify truth values. In this exploratory paper we analyze some of the properties preserved under these handlings. To do this we refer to an approach to fuzzy semantics in which the valuation structures can vary freely inside a given type.     

On the differentiation between the magnetic anomalies of cylinders and disks

The magnetic anomaly patterns due to thin lateral deposits ofore can be very similar to those due to deposits in extendedmagma root structures which potentially may be more importantfrom a geophysical point of view. New forms of the solutionsfor the anomalous magnetic field due to vertical cylinders andto thin disks are given; these are suitable for fast computation.For various values of the local magnetization vector of thebody, the measured anomaly patterns are obtained and featuresare identified which serve to differentiate the patterns dueto a thin disk from those due to a semi-infinite vertical cylinder.     

Estudio probabilista del daño por choque según la metodología PEER. Aplicación a un paso superior sísmicamente aislado

Bridges with deck supported either on sliding or elastomeric bearings are common in mid-seismicity regions. Pounding between deck and abutments is linked with their main seismic vulnerabilities, which can be assessed by estimating the probability of a given state of damage being reached in a given time period. This paper presents a state of the art methodology used to solve that problem, as well as its application to the assessment of the vulnerability of an overpass placed in Granada area (South-east of Spain), belonging to the previously mentioned typology.The Pacific Earthquake Engineering Research Center methodology will be adapted and applied. Their main steps will be briefly presented, although the identification and characterization of damage likely to occur will be described in more detail. The model of the structure, and specially pounding modeling, will also be detailed.Results are interesting since this bridge can be considered as a representative of a widespread class. The adapted methodology may be applied to similar structures. Also, probability values obtained may serve as benchmarks.     

Optimal Claiming in an Automobile Insurance System with Bonus-Malus Structure

A motorist involved in an accident will have to decide whether to claim from his insurance company or not when he is at fault. An optimal decision rule can only be determined in the light of future developments and future decisions, since the consequences of claiming or not claiming are felt in the subsequent year's premiums. In this paper, optimal no-claim limits are determined for a common Dutch type of insurance policy with bonus-malus structures, using generalized Markovian programming. The computational results are given for various values of the expected number of accidents per year.     

Consistent initialization for DAEs in Hessenberg form

For nonlinear DAEs, we can hardly make a reasonable statement unless structural assumptions are given. Many results are restricted to explicit DAEs, often in Hessenberg form of order up to three. For the DAEs resulting from circuit simulation, different beneficial structures have been found and exploited for the computation of consistent initial values. In this paper, a class of DAEs in nonlinear Hessenberg form of arbitrary high order is defined and analyzed with regard to consistent initialization. For this class of DAEs, the hidden constraints can be systematically described and the consistent initialization can be determined step-by-step solving linear subproblems, an approach hitherto used for the DAEs resulting from circuit simulation. Finally, it is shown that the DAEs resulting from mechanical systems fulfill the defined structural assumptions. The algorithm is illustrated by several examples.     

Solución de la cinemática directa de la plataforma Gough-Stewart general usando un algoritmo híbrido de optimización

The direct kinematics problem for parallel robots can be stated as follows: given values of the joint variables, the corresponding Cartesian variable values, the pose of the end-effector, must be found. Most of the times the direct kinematics problem involves the solution of a system of non-linear equations. The most efficient methods to solve such kind of equations assume convexity in a cost function which minimum is the solution of the non-linear system. In consequence, the capacity of such methods depends on the knowledge about an starting point which neighboring region is convex, hence the method can find the global minimum. This article propose a method based on probabilistic learning about an adequate starting point for the Dogleg method which assumes local convexity of the function. The proposed method efficiently avoids the local minima, without need of human intervention or apriori knowledge, thus it shows a more robust performance than the simple Dogleg method or other gradient based methods. To demonstrate the performance of the proposed hybrid method, numerical experiments and the respective discussion are presented. The proposal can be extended to other structures of closed-kinematics chains, to the general solution of systems of non-linear equations, and to the minimization of non-linear functions.     

弹性正交索网结构动力学的各类非传统Hamilton型变分原理

根据古典阴阳互补和现代对偶互补的基本思想,通过罗恩早已提出的一条简单而统一的新途径,系统地建立了正交索网结构几何非线性弹性动力学的各类非传统Hamilton型变分原理．这种新的非传统Hamilton型变分原理能反映这种动力学初值-边值问题的全部特征．文中首先给出正交索网结构几何非线性动力学的广义虚功原理的表式,然后从该式出发,不仅能得到正交索网结构几何非线性动力学的虚功原理,而且通过所给出的一系列广义Legendre变换,还能系统地成对导出正交索网结构几何非线性弹性动力学的5类变量、4类变量、3类变量和2类变量非传统Hamilton型变分原理的互补泛函、以及相空间非传统Hamilton型变分原理的泛函与1类变量非传统Hamilton型变分原理势能形式的泛函．同时,通过这条新途径还能清楚地阐明这些原理的内在联系．     

Entropic measure of the order-disorder character in lattice systems in the representation of coordination Cayley tree graphs

We systematically expound the infodynamical method for analyzing lattice and grid systems. We establish the logic and algorithm for mapping given objects to coordination Cayley tree graphs and present their main properties. Tree graphs of grid systems are complicated objects, and the principle of cluster-type simplicial decomposition can be used to study them. Based on a simplicial decomposition, we construct the enumerating structures, from which we construct entropy-type functionals. We pose the percolation problem on Cayley tree graphs in a nonconventional sense, which may be considered for both enumerating structures and their entropies. The corresponding entropy percolational dependences and their critical indices can be considered sufficiently universal measures of order in lattice systems. The simpliciality also implies an analogy with the fractality principle. We introduce three types of fractal characteristics and give analytic expressions for fractal dimensions for the tangential and streamer representations and for the Mandelbrot shell.     

Knowledge structure,knowledge granulation and knowledge distance in a knowledge base

One of the strengths of rough set theory is the fact that an unknown target concept can be approximately characterized by existing knowledge structures in a knowledge base. Knowledge structures in knowledge bases have two categories: complete and incomplete. In this paper, through uniformly expressing these two kinds of knowledge structures, we first address four operators on a knowledge base, which are adequate for generating new knowledge structures through using known knowledge structures. Then, an axiom definition of knowledge granulation in knowledge bases is presented, under which some existing knowledge granulations become its special forms. Finally, we introduce the concept of a knowledge distance for calculating the difference between two knowledge structures in the same knowledge base. Noting that the knowledge distance satisfies the three properties of a distance space on all knowledge structures induced by a given universe. These results will be very helpful for knowledge discovery from knowledge bases and significant for establishing a framework of granular computing in knowledge bases.     

Optimization of Euclidean distance threshold in the application of recurrence quantification analysis to heart rate variability studies

An integrated approach is proposed to solve the optimization problem of the Euclidean distance threshold ε in recurrence quantification analysis (RQA), which is increasingly applied in the study of heart rate variability (HRV). In this paper, ε is inversely computed from a given recurrence rate (REC), the percentage of recurrence points. From the inversely computed ε, two other RQA output variables: determinism (DET), the percentage of recurrence points forming diagonal line structures, and laminarity (LAM), the percentage of recurrence points forming vertical and horizontal structures, are computed out as well. The trend of DET, LAM values at different REC levels (DLR trend) is introduced to comprehensively represent the dynamic properties of a time series. Based on the DLR trend, the variation of discrimination power, represented by the average loss (or Bayes risk), of DET and LAM, at different REC values is analyzed. Surrogate techniques are used to generate reliable test data sets for the discrimination evaluation. In particular, the results show that (1) the optimal REC can be much higher than the widely used 1% REC, and (2) after the optimization, the average loss can be reduced compared to 1% REC. It is also demonstrated that the optimal ε depends on the dynamic source and RQA variables, and the DLR trend based ε optimization method can improve RQA discrimination analysis especially for the short term HRV analysis.     

Least Square Control Problems in Nonreflexive Spaces

We consider a control problem in a Banach space with a bounded observer, but an unbounded controller which takes values in the extrapolated Favard class. A least square regulator problem can be formulated if the observer and the admissible controls take values in Hilbert spaces. We prove that for this type of LQR-problem the value function is given by a Riccati operator, and that a bounded state feedback based on the Riccati operator yields the optimal control. April 30, 1999     

混合Copula模型在中国股市的应用

首先给出了描述相依结构的混合Copula模型,然后给出寻求混合Copula模型的EM算法,最后以中国股市的实际数据进行了实证分析,说明混合Copula模型是可以用来描述中国股市的相依结构.     

Endolocality meets homomorphism-homogeneity: a new approach in the study of relational algebras

We study the problem of characterizing all relations that can be defined from the fundamental relations of a given relational structure using positive existential formulæ. The notion of κ-endolocality is introduced in order to measure the complexity of relational structures with respect to this task. The hierarchy of κ-endolocal structures is thoroughly analysed in algebraic and model-theoretic ways. Interesting cross-connections with homomorphism-homogeneous relational structures are revealed. The interrelations between endolocal relational structures and several model-theoretic notions are collected in the Main Theorem. This Main Theorem is demonstrated to be a useful tool for studying relational algebras and, in particular, weak Krasner algebras. For example, a short proof of F. Börners characterization of weak Krasner clones on a countable set is given.     

An invariant of nonpositively curved contact manifolds

We define an invariant of contact structures and foliations (on Riemannian manifolds of nonpositive sectional curvature) which is upper semi-continuous with respect to deformations and thus gives an obstruction to the topology of foliations which can be approximated by isotopies of a given contact structure.     

Wackelige Gelenkwerke und wackelige Polyeder in Der sphärischen Geometrie

Infinitesimal rigidity and shakiness of jointed rodworks or polyhedra have been of major interest in recent research in geometry. In this paper structures of this type are investigated in spheres and projective spaces. A transformation is given showing that essentially no new structures occur in these spaces compared with the euclidean case. The main tool is the projective invariance of shaky structures. Shaky structures in euclidean space can be obtained as affine sections of shaky structures in a projective space of the same dimension.     

Inspection and maintenance optimization methods

Three methods of the optimal planning of the inspection and maintenance of offshore structures are described. The models are based on respectively: the maximization of the effect of inspections, measured by the total importance value of the errors detected, subject to a given total economical budget; the minimization of the total costs of obtaining respectively: a given importance value of errors detected or given numbers of inspections of various types. Special selections of the importance values of structural elements give problems of the maximization of the reliability of the structural system, or the minimization of the economical consequences of failures, or the minimization of the sum of the costs of inspections and failure-consequences, subject to a given total failure probability of the system.Different failure types of elements and time schedules of inspections can be included in the model.An extension of the incremental method of Fox is applied, and an evaluation measure is given for the calculation of bounds of the optimal objective value, or given numbers of inspections are planned by application of continuous linear programming with integral solutions.     

Structural models with qualitative values

In fields of study from cognition to organizations and social networks , empirical structures have been formally represented in terms of graph theoretical models. When the empirical relationships can be seen as valued, a valued graph or digraph is called for. Values have been conventionally identified with real numbers, but other sorts of entities (most often signs) have been used. In this paper, we demonstrate a general system under which graphs and digraphs with values that are not numbers may be used to represent various important properties and features of empirical structures. Special cases include multiplexity of relationships, formal and informal linkages in organizational structures, systems and their environments, and structural consistency principles. The general system incorporates a matrix methodology which permits the convenient analysis of empirical structures. These cases are also intended to exemplify the ways in which valued relational models may be developed to extend this kind of formalization and its methodology to other areas of substantive interest.     

基于数值分布的激励型综合评价方法

针对激励评价中的等级划分问题,本文提出了一种基于数值分布的等级划分方法,相比于现有的等级划分方法,该方法能够综合考虑数值分布情况来划分等级,并结合本文提出的等级划分法对密度算子进行拓展,提出了一种基于数值分布的激励型综合评价方法。首先本文从数值分布的角度提出了一种新的等级划分方法,从而得出各等级区间的等级区间分界点;其次确定等级系数,并结合指标值和等级区间分界点给出各指标的权向量,给出一种不需要进行归一化处理的等级权向量确定方法,该方法能够较好的解决归一化处理带来的不公平性;再次根据密度算子思想对评价数据进行集结得出评价结果;最后通过一个算例对该方法进行验证,结果表明该方法可以实现对被评价对象科学激励的作用。该方法尤其适用于企业员工激励、省市综合排名、高校人才选拔等问题。