pattern characteristics of an evolution between two classes pattern recognition involves two phases learning and recognition using fuzzy theory the first phase consists mainly in learning membership functions of classes the recognition phase or diagnosis consists in computing membership degrees of the data to classes and deciding in which class the data fits more appropriately in real time processes the system may evolve from one class to another the main idea of this paper is to propose a method that is able to learn and recognize this evolution the learning phase is based on fuzzy interval regressions the second part presents a method that gives a diagnosis depending on the percentage of evolution a decision method is suggested at the end

bifurcations for a predator prey system with two delays in this paper a predator prey system with two delays is investigated by choosing the sum of two delays as a bifurcation parameter we show that hopf bifurcations can occur as crosses some critical values by deriving the equation describing the flow on the center manifold we can determine the direction of the hopf bifurcations and the stability of the bifurcating periodic solutions in addition special attention is paid to the global continuation of local hopf bifurcations using a global hopf bifurcation result of j wu symmetric functional differential equations and neural networks with memory trans amer math soc 350 1998 4799 4838 we may show the global existence of periodic solutions

a generalized time quantifier approach to approximate reasoning abstract in this paper a rather expressive fuzzy temporal logic for linear time is introduced first this logic is a multivalued generalization lukasiewicz style of a two valued linear time temporal logic based on e g the until operator second it is obtained by introducing a generalized time quantifier a generalization of the partition operator investigated by shen applied to fuzzy time sets in this fuzzy temporal logic generalized compositional rules of inference suitable for approximate reasoning in a temporal setting are presented as valid formulas some medical examples illustrate our approach

multi dimensional fuzzy reasoning this paper suggests a method of multi dimensional fuzzy reasoning concerned with both modus ponens and modus tollens it also discusses an example to show how the method works

permanence and positive periodic solution for the single species nonautonomous delay diffusive models abstract single species nonautonomous delay diffusion models with nonlinear growth rates are investigated some sufficient conditions are determined that guarantee the permanence of the species and the existence of a positive periodic solution which is global attractively

approximation to a class of non autonomous systems by dynamic fuzzy inference marginal linearization method in this paper a dynamic fuzzy inference marginal linearization dfiml method is proposed for modeling nonlinear dynamic systems this method can transfer a group of input output data into a time variant fuzzy system with variable coefficients it is shown that solutions of time variant fuzzy systems generalized by dfiml method are universal approximators to solutions of a class of non autonomous systems also the analytical solutions of these time variant fuzzy systems can be obtained finally a simulation example is provided to illustrate the validity and potential of the developed techniques

fuzzy controls under various fuzzy reasoning methods abstract a fuzzy logic controller consists of linguistic control rules tied together by means of two concepts fuzzy implications and a compositional rule of inference most of the existing fuzzy logic controllers are based on the approximate reasoning method due to mamdani this paper introduces other fuzzy implications such as the arithmetic rule and maximin rule for linguistic control rules and compares control results for a plant model with first order delay under various approximate reasoning methods moreover control results are compared when the widths of fuzzy sets of linguistic control rules are changed

stability criteria for a system involving two time delays a system of two autonomous ordinary differential equations with two discrete time delays is considered with a view to determining the stability of equilibria using the nyquist criterion on the characteristic equation estimates on the length of delays are given for which a system which is stable in the absence of delays remains stable conditions are also derived for there to be no change in stability even for unbounded delays the above mentioned criteria are applied to a system modeling competitive interacting populations and to a predator prey system

stability and hopf bifurcation in a delayed competition system abstract in this paper hopf bifurcation for two species lotka volterra competition systems with delay dependence is investigated by choosing the delay as a bifurcation parameter we prove that the system is stable over a range of the delay and beyond that it is unstable in the limit cycle form i e there are periodic solutions bifurcating out from the positive equilibrium our results show that a stable competition system can be destabilized by the introduction of a maturation delay parameter further an explicit algorithm for determining the direction of the hopf bifurcation and the stability of the bifurcating periodic solutions is derived by using the theory of normal forms and center manifolds and numerical simulations supporting the theoretical analysis are also given

harmless delays for uniform persistence abstract this paper studies a two dimensional predator prey system with a finite number of discrete delays our purpose is to demonstrate that the time delays are harmless for uniform persistence of the solutions of the system the results are obtained by constructing suitable persistence functionals

global existence of positive periodic solutions of periodic predator prey system with infinite delays abstract a set of easily verifiable sufficient conditions is derived for the global existence of periodic solutions with strictly positive components for a periodic predator prey system with infinite delays by using the method of coincidence degree

identification of a linear system from inexact data a three variable example abstract in 1901 pearson formulated the general problem of how to fit a hyperplane in the most efficient way to a system of points in a data space this problem is still not exactly solved in all its generality as kalman and los have shown all statistical attemps to solve the problem have failed because each of them can provide only prejudicial and statistical but not objective and mathematical solutions however exact mathematical solutions do exist for special cases this paper s main principle of linear identification from inexact data provides the mathematical framework in which the problem and the deficiencies of the statistical solutions are conveniently discussed in particular those of the least squares regression and statistical common factors schemes it will be argued that the exact common factors or frisch scheme offers most promise to direct us to complete and exact solutions even though it imposes severe restrictions on the orders of the systems because of wilson s inequality throughout this paper the problem and its various solution schemes are illustrated by an empirical example consisting of three data variables describing the profitability performance of some large u s bank holding companies for this empirical example the frisch scheme provides a unique solution contrary to some earlier pessimistic conclusions

t type fuzzy memory cells abstract the paper deals with design problems of trigger t type fuzzy memory cell the authors suggest six types of t cell which can be used in temporal fuzzy logic memory item of 1 fuzzy bit information converter from fuzzy date to fuzzy time interval cell of fuzzy register item of fuzzy memory fuzzy delay circuit and so on generally speaking in addition to hirota and ozawa s fuzzy jk flip flop fuzzy t memory cells which introduce time memory action into fuzzy inference machines are observed

a strategy of problem solving in a fuzzy reasoning network this paper deals with the development of a strategy of problem solving in a fuzzy reasoning network the propositions involved are temporal knowledge representation with hierarchical or network structure in a fuzzy sense and forward and backward fuzzy reasoning the strategies as developed might be applicable to various fuzzy reasoning problems existing in the real world

fuzzy automata with fuzzy relief this paper shows a definition of a fuzzy automaton which has the state input and output sets as fuzzy sets the state transition function is defined as moving on a fuzzy relief with fuzzy peak states and boundaries between different membership functions after the definition of fuzzy automaton with fuzzy relief the paper deals with a generalization simulation and realization of such a fuzzy automaton the paper links the defined fuzzy automaton to an existing fuzzy jk memory cell and to well known fuzzy automata defined on the basis of crisp sets

fuzzy flip flop and fuzzy registers abstract the concept of fuzzy flip flop has already been proposed two types of characteristic equations that are set type and reset type of fuzzy flip flop have been introduced as an extended form of that of binary j k flip flop using the concepts of fuzzy negation t norm and s norm operations the aim of this article is to present the hardware implementation of a fuzzy flip flop fuzzy negation t norm and s norm are restricted to complementation min max respectively for the sake of practical use fundamental properties of fuzzy flip flop based on complementation min and max operations are mentioned first then its characteristics are graphically shown through computer simulation experimental results of a min max type fuzzy flip flop circuit in voltage mode are presented finally an idea of a fuzzy shift register which can store and shift the membership function information defined on a finite universe of discourse is presented

fuzzy algorithmic control of a model car by oral instructions this paper is concerned with an experimental study of fuzzy algorithmic control of a model car a fuzzy algorithmic controller is designed by referring to an operator s experience and knowledge the car is equipped with ultrasonic sensing devices and a micro computer it is controlled by oral instructions such as go straight turn right enter garage and go out of garage

the prejudices of least squares principal components and common factors schemes we prove mathematically that the least squares regression scheme is of little use for identification from inexact data even in the low noise case its results depend solely on the prejudice concerning which subsets of variables are chosen as regressands and which as regressors from a given set of data variables in practice least squares regression results are always biased and depend on the relative noise levels while even the signs of the estimates are completely determined by the arbitrary choice of the regressands if the number of underlying relationships is misspecified the principal components or statistical common factor scheme fares a similar fate since the choice of how many principal components or common factors to retain is essentially prejudiced and not determined by the data both schemes produce artificial and unexplained correlations among the residuals for the principal components scheme this occurs because it usually violates wilson s inequality a fortiori we prove exactly why in practice factor indeterminancy occurs the exact ideal multiple common factor scheme of frisch and thurstone has not yet been solved except for small numbers six and less of data variables

global stability for infinite delay lotka volterra type systems abstract in this paper sufficient conditions are established for the global stability of the saturated equilibrium of an infinite delay nonautonomous lotka volterra type system the present work is distinguished from previous work principally be allowing the system to be nonautonomous and relaxing the traditional requirement that the undelayed intraspecific competition dominates both the delayed intraspecific competition as well as the interspecific interactions we require the undelayed intraspecific competition to dominate the latter but not the former

approximate reasoning with time abstract the need to make time dependent assumptions is frequently encountered in many systems especially in dynamical systems this paper presents a theoretical study of the representation and manipulation of some vague concepts in the temporally changing world our approach to the modeling is based on zadeh s theory of possibility we introduce a concept of similarity index in reasoning with time we present two different types of widely used models one rule based and another resolution based for reasoning with time we consider simply yet concrete examples to illustrate the usefulness of the proposed models

dynamical membership functions an approach for adaptive fuzzy modelling new approaches in fuzzy modelling in order to solve practical limitations found in classic adaptive fuzzy modelling are considered an interesting contribution in the fuzzy logic field in this work an approach for the development of dynamical fuzzy models is presented the approach allows to incorporate the system dynamics into the fuzzy membership functions which are defined in terms of the sample mean value and the variance of each variable of the fuzzy model from the input and output values of the system to be modelled these fuzzy membership functions defined as dynamical functions have adjustable parameters which are adapted by using a conventional off line gradient descent based algorithm in this way after the learning process the resulted fuzzy model has non static membership functions dependent on the available values of the variables at time t some application examples to illustrate the performance of the proposed dynamical adaptive fuzzy model on system identification are presented and the experimental results are discussed in order to remark the capabilities of the new fuzzy model

attention to time in fuzzy logic abstract today s fuzzy logic deals with fuzzification fuzzy inference and defuzzification problems at a fixed time point but in binary logic as a comparable option to fuzzy logic we have by the side of decisions within a fixed time point still memory time dependent switching functions finite automata regular expressions and so on all these items need time as a basic variable if we ask ourselves for such or similar items within fuzzy logic we can rapidly conclude that we must in the first instance make basic definitions and relations for the time variable this paper considers a time variable in the domain of fuzzy logic we try to put up a fuzzy set as a fuzzy time variable time dependent fuzzy rule fuzzy time operator and similar items which can give us a new time extension of fuzzy logic

periodic solution and almost periodic solution for a nonautonomous lotka volterra dispersal system with infinite delay abstract this paper studies a nonautonomous lotka volterra dispersal systems with infinite time delay which models the diffusion of a single species into n patches by discrete dispersal our results show that the system is uniformly persistent under an appropriate condition the sufficient condition for the global asymptotical stability of the system is also given by using mawhin continuation theorem of coincidence degree we prove that the periodic system has at least one positive periodic solution further obtain the uniqueness and globally asymptotical stability for periodic system by using functional hull theory and directly analyzing the right functional of almost periodic system we show that the almost periodic system has a unique globally asymptotical stable positive almost periodic solution we also show that the delays have very important effects on the dynamic behaviors of the system

a nonautonomous predator prey system with stage structure and double time delays in the present paper we study a nonautonomous predator prey model with stage structure and double time delays due to maturation time for both prey and predator we assume that the immature and mature individuals of each species are divided by a fixed age and the mature predator only attacks the immature prey based on some comparison arguments we discuss the permanence of the species by virtue of the continuation theorem of coincidence degree theory we prove the existence of positive periodic solution by means of constructing an appropriate lyapunov functional we obtain sufficient conditions for the uniqueness and the global stability of positive periodic solution two examples are given to illustrate the feasibility of our main results

necessary and sufficient conditions for permanence and global stability of a lotka volterra system with two delays in this paper we seek necessary and sufficient conditions for the permanence and the global asymptotic stability of a positive equilibrium for a lotka volterra system with two delays

estimating linear statistical relationships this paper on estimating linear statistical relationships includes three lectures on linear functional and structural relationships factor analysis and simultaneous equations models the emphasis is on relating the several models by a general approach and on the similarity of maximum likelihood estimators under normality in the different models in the first two lectures the observable vector is decomposed into a systematic part and a random error the systematic part satisfies the linear relationships estimators are derived for several cases and some of their properties given estimation of the coefficients of a single equation in a simultaneous equations model is shown to be equivalent to estimation of linear functional relationships

dynamical fuzzy reasoning and its application to system modeling abstract many fuzzy reasoning methods do not consider temporal information even though time delays are an inherent part of many kinds of information exchange we propose therefore a method of dynamical fuzzy reasoning that has a time delay between premise and consequent in fuzzy rule base knowledge in this paper we consider this reasoning method qualitatively and show how to apply it to system models whose basis is system dynamics

fuzzy reasoning as a control problem different from the dominant view of treating fuzzy reasoning as generalization of classical logical inference in this paper fuzzy reasoning is treated as a control problem a new fuzzy reasoning method is proposed that employs an explicit feedback mechanism to improve the robustness of fuzzy reasoning the fuzzy rule base given a priori serves as a controlled object and the fuzzy reasoning method serves as the corresponding controller the fuzzy rule base and the fuzzy reasoning method constitute a control system that may be open loop or closed loop depending on the underlying reasoning goals constraints the fuzzy rule base the fuzzy reasoning method and the corresponding reasoning goals constraints define the three distinct ingredients of fuzzy reasoning while various existing fuzzy reasoning methods are essentially a static mapping from the universe of single fuzzy premises to the universe of single fuzzy consequences the new fuzzy reasoning method maps sequences of fuzzy premises to sequences of fuzzy consequences and is a function of the underlying reasoning goals constraints the monte carlo simulation shows that the new fuzzy reasoning method is much more robust than the optimal fuzzy reasoning method proposed in our previous work the explicit feedback mechanism embedded in the fuzzy reasoning method does significantly improve the robustness of fuzzy reasoning which is concerned with the effects of perturbations associated with given fuzzy rule bases and or fuzzy premises on fuzzy consequences the work presented in this paper sets a new starting point for various principles of feedback control and optimization to be applied in fuzzy reasoning or logical inference and to explore new forms of reasoning including robust reasoning and adaptive reasoning it can be also expected that the new fuzzy reasoning method presented in this paper can be used for modeling and control of complex systems and for decision making under complex environments

rank reducibility of a symmetric matrix and sampling theory of minimum trace factor analysis one of the intriguing questions of factor analysis is the extent to which one can reduce the rank of a symmetric matrix by only changing its diagonal entries we show in this paper that the set of matrices which can be reduced to rankr has positive lebesgue measure if and only ifr is greater or equal to the ledermann bound in other words the ledermann bound is shown to bealmost surely the greatest lower bound to a reduced rank of the sample covariance matrix afterwards an asymptotic sampling theory of so called minimum trace factor analysis mtfa is proposed the theory is based on continuous and differential properties of functions involved in the mtfa convex analysis techniques are utilized to obtain conditions for differentiability of these functions

permanence extinction and balancing survival in nonautonomous lotka volterra system with delays in this paper the periodic n species lotka volterra competition systems with time delays are considered the sufficient conditions are derived for the permanence extinction and balancing survival of the system some known results are improved and unified further our results suggest that under some conditions the introduction and the variance of the time delays will be either harmless or useless conjecture about the effect of time delays on some global behaviors of the system is advanced

permanence and global attractivity of delay diffusive prey predator systems with the michaelis menten functional response in this paper the author investigates two species nonautonomous delay diffusive preypredator models with michaelis menten functional response sufficient conditions are derived for permanence of the species further the author also establishs the sufficient conditions that guarantee the arbitrary positive periodic solution of the systems is global attractive

representation and use of imprecise temporal knowledge in dynamic systems abstract in this paper the importance of representation and use of imprecise temporal knowledge for problem solving in industrial dynamic systems is emphasized first a representation of imprecise temporal knowledge is then given for describing the dynamic behavior of systems a novel problem on on line temporal matching and numeric matching is presented and a method for solving this problem is proposed a method for fuzzy proposition reasoning and temporal reasoning is put forward finally as two application examples the fault diagnosis of a fluidized catalytic cracking unit is taken up to illustrate the usefulness of the proposed knowledge representation and methods

towards a general theory of action and time abstract a formalism for reasoning about actions is proposed that is based on a temporal logic it allows a much wider range of actions to be described than with previous approaches such as the situation calculus this formalism is then used to characterize the different types of events processes actions and properties that can be described in simple english sentences in addressing this problem we consider actions that involve non activity as well as actions that can only be defined in terms of the beliefs and intentions of the actors finally a framework for planning in a dynamic world with external events and multiple agents is suggested

analysis and design of time variant fuzzy systems based on dynamic fuzzy inference in this paper a class of time variant fuzzy systems is designed and analyzed firstly a novel model of dynamic fuzzy inference dfi is proposed and the corresponding dfi method is obtained then the response abilities of time variant fuzzy systems constructed by the dfi method are analyzed some sufficient conditions for time variant fuzzy systems as step functions fitted functions and interpolation functions are derived furthermore a sufficient and necessary condition for time variant fuzzy systems as interpolation functions is also deduced in addition the approximation problem of time variant fuzzy systems is discussed it is proved that time variant fuzzy systems constructed by the dfi method are universal approximators to a class of nonlinear systems in addition the approximation accuracy of the corresponding time variant fuzzy systems is investigated finally a simulation experiment is provided to demonstrate how to design a time variant fuzzy system in order to approximate a given nonlinear system to a desired accuracy

stability and bifurcation analysis on a ratio dependent predator prey model with time delay a ratio dependent predator prey model with time delay due to the gestation of the predator is investigated by analyzing the corresponding characteristic equations the local stability of a positive equilibrium and a semi trivial boundary equilibrium is discussed respectively further it is proved that the system undergoes a hopf bifurcation at the positive equilibrium using the normal form theory and the center manifold reduction explicit formulae are derived to determine the direction of bifurcations and the stability and other properties of bifurcating periodic solutions by means of an iteration technique sufficient conditions are obtained for the global attractiveness of the positive equilibrium by comparison arguments the global stability of the semi trivial equilibrium is also addressed numerical simulations are carried out to illustrate the main results

fuzzy reasoning method by optimizing the similarity of truth tables this paper presents a new fuzzy reasoning method by optimizing the similarity of truth tables os method for short its basic idea is to find a fuzzy set such that the truth tables generated by the antecedent rule and the consequent rule are as similar as possible based on this idea the principle of os method and the fuzzy reasoning with os method are given and discussed and then the os methods with certain similarity measure and several fuzzy implications are investigated finally numerical examples are analyzed to compare the proposed method with compositional rule of inference cri method

permanence and stability of a predator prey system with stage structure for predator a stage structured predator prey system with delays for prey and predator respectively is proposed and analyzed mathematical analysis of the model equations with regard to boundedness of solutions permanence and stability are analyzed some sufficient conditions which guarantee the permanence of the system and the global asymptotic stability of the boundary and positive equilibrium respectively are obtained

slide a simple adaptive defuzzification method we introduce a parameterized family of defuznfica tion operators called the semi linear defuzzification slide method this method is based upon a simple transformation of the fuzzy output set of the controller we suggest an algorithm for the learning of the parameter from a data set in an attempt to simplify the parameter learning we suggest a modified version of the slide method which results in a simple learning algorithm the development of the learning algorithm is based upon the use of the kalman filter n fuzzy logic control systems l 2 the defuzzification i step involves the selection of one value as the output of the controller more specifically starting with a fuzzy subset possibility distribution f over the output space x of the controller the defuzzification step uses this fuzzy subset to select a representative element x the two most often used methods of defuzzification found in the literature are the center of area coa and mean of maxima mom 3 6 methods we recall that the mom method takes as its defuzzified value the mean of the elements that attain the maximum membership grade in f the coa method takes as its defuzzified value d ci ui xi where ui f xi cj f xj in 7 and 8 we formulated a general defuzzification method via basic defuzzification distribution badd transformations the main idea of this badd approach is to transform the possibility distribution f into a probability distribution p and then the defuzzified value is the expected value of the probability distribution the process of transforming f into p was seen as a two step process the first step was to transform f into a new possibility distribution e and then to normalize e to obtain p the step of obtaining e from f involved the use of a badd transformation in which e xi f z where 6 e o co it was shown in 7 that the generalized badd method implies the coa and mom methods as special cases in particular the coa method is obtained for a 1 and the mom is obtained for 6 00 when s 0 we get a defuzzified value that is the unweighted mean of the output space d xi xi the badd transformation has the advantage of being based on a single parameter which allows us the potential of adaptively learning the best method of defuzzification for a given controller while the family of all defuzzified values that can be obtained by the generalized badd defuzzification method was parameterized an undesirable property of the method was the nonlinear

a fuzzy temporal rule based velocity controller for mobile robotics this paper describes a velocity controller implemented on a nomad 200 mobile robot the controller has been developed for wall following behaviour and its design is modularized into two blocks angular and linear velocity control a simple design and implementation was made for the former with the aim of focusing the design efforts on the linear velocity control block in order to remark the usefulness of this task the latter has been implemented using an explicit model for knowledge representation and reasoning called fuzzy temporal rules ftrs this model enables to explicitly incorporate time as a variable due to which the evolution of variables in a temporal reference can be described using this mechanism we obtain linear velocity values that are adapted to each different circumstance and thus a higher average velocity as well as smoother and more robust behaviours are achieved

on a delay differential equation for single specie population variations on considere l equation differentielle scalaire a retard n t n t a bn t n t 1 on suppose a b constantes positives et on etudie les solutions pour t 0 telles que n t n 0 t 1 t 0 avec n 0 t une fonction initiale donnee positive et continue on obtient des resultats sur la limitation et le comportement asymptotique des solutions

fuzzy constraint networks for signal pattern recognition this paper deals with representation and reasoning on information concerning the evolution of a physical parameter by means of a model based on the fuzzy constraint satisfaction problem formalism and with which it is possible to define what we call fuzzy temporal profiles ftp based on fundamentally linguistic information this model allows the integration of knowledge on the evolution of a set of parameters into a knowledge representation scheme in which time plays a fundamental role the ftp model describes the behaviour of a physical parameter on the basis of a set of signal events and which allows the evolution of the parameter between each pair of events to be modelled as signal episodes given the fundamentally linguistic nature of the information represented the consistency analysis of this information is an essential task nevertheless the obtention of the minimal representation of the network that defines an ftp is an np hard problem in spite of this we supply algorithms guaranteeing local levels of consistency that allow to correct a large proportion of the errors committed by a human expert in the linguistic description of the profile furthermore we propose a new topology whose consistency can be guaranteed in polynomial time we also study the applicability of this model in the recognition of signal patterns

persistence and attractivity in an n species ratio dependent predator prey system with distributed time delays an n species ratio dependent predator prey food chain model with distributed time delays is investigated it is shown that the system is permanent under some appropriate conditions and sufficient conditions are obtained for the global attractivity of the positive equilibrium of the system