Octavian Pastravanu

• Doctor of Engineering
• Professor (Full) at "Gheorghe Asachi" Technical University of Iasi

This book develops a nonstandard approach to control systems analysis and design, exploring the properties of a new type of model called non-recursive behavioural models, unlike the recursive behavioural models of classical state space representation. For a real plant exhibiting a linear behaviour in the vicinity of any operating point, a non-recur...

See DOI. _______ The concept of “componentwise asymptotic stability” (abbreviated CWAS) was initially introduced as a special type of stability for single-model linear systems, with continuous- or discrete-time dynamics. Subsequently, the framework was enlarged to encompass linear systems with interval-type uncertainties. For both these classes of...

See full-text. ______ A mathematical framework dedicated to flow-invariance study is proposed for continuous-time linear dynamics, with respect to general-shape contractive sets-defined by the class of proper C-sets (convex and compact sets, including the origin as an interior point), for which a constant-rate exponential decrease is considered. Th...

See DOI. ______ The paper constructs a mathematically rigorous support for flow-invariance analysis of discrete-time linear system dynamics, with respect to a large family of contractive sets, considered in the comprehensive form of proper C-sets, exponentially decreasing with a certain rate. The first part develops a general algebraic point of vie...

See DOI ____ In this paper the authors have developed a Convolutional Neural Network architecture adapted to Speech-to-Text research field. This type of network has been chosen due to its capacity to extract the relevant features and its popularity in classification problems. A particular model for a Speech-to-Text application has been designed. Th...

See DOI ___ The paper proves a new sufficient condition for the stability of switched linear systems with mode-dependent average dwell-time (MDADT). This condition is formulated in general terms of matrix-measure inequalities that are correlated with the properties of the switching signals. We show that our result is able to incorporate, as particu...

See DOI ____ The current research extends the issue of componentwise stabilization of interval systems (ISs) - previously addressed by us, from a symmetrical to the broader, non-symmetrical framework. The considered issue means the individual monitoring of each closed-loop state variable by keeping it inside of a "box" that decreases exponentially....

See DOI _____ The paper considers the discrete- or continuous-time dynamics of arbitrary switching linear systems, for which new results are developed on set invariance testing. The invariance analysis refers to a class of contractive sets, previously studied only for a few simple cases; our developments cover the general circumstances of polyhedra...

See DOI. _____ The key result of the paper exploits the duality of arbitrary switching positive linear systems, in order to derive a sufficient condition for the existence and construction of diagonal quadratic copositive Lyapunov functions. This condition is less conservative than a result also relying on duality, recently reported in the literatu...

See DOI ____ The paper proposes developments for the set-invariance scenarios applicable to continuous-time bidirectional associative memories (abbreviated as BAMs). The new results represent sufficient conditions for testing the existence of exponentially contractive invariant sets with polyhedral shape. Two theorems are stated, so as to cover the...

See DOI _____ The work is placed within the area of qualitative analysis of arbitrary switching linear systems, focusing on the existence of quadratic Lyapunov functions for discrete- or continuous-time dynamics. Our investigations express a series of connotations on the utilization of a criterion (amply cited in the control engineering literature)...

See DOI ____ The paper belongs to the area of qualitative analysis of the dynamics for discrete-time arbitrary switching linear systems. The purpose of our research is to develop a rigorous comparative study between two criteria for testing the existence of λ-contractive polyhedral sets with respect to the switching systems. Despite the common obje...

See DOI ____ The paper considers the nonlinear dynamics of a large class of continuous-time Hopfield neural networks (abbreviated as HNNs). Our research proposes sufficient conditions for testing the existence of contractive invariant sets with general form, defined by p-norms, 1≤p≤∞, which are weighted by rectangular, full column rank, non-negativ...

Perron-Frobenius theory, well-known for non-negative matrices, is applied to the study of a category of economic systems described by Leontief-type models. For the considered models, the paper presents a qualitative point of view, oriented towards the solution existence / non-existence, as well as a quantitative point of view, oriented towards the...

See DOI. _______ The role played by column representatives is expanded in the study of the properties exhibited by the trajectories of arbitrary switching linear systems. Previous contributions on the employment of column representatives focused on positive dynamics and linear copositive Lyapunov functions associated with exponentially contractive...

See DOI. ______ The paper explores the properties of positive interval dynamic systems in continuous-time, via two types of techniques, and develops a comparative study between the two approaches. The first type is based on the properties of the row and column representatives corresponding to the vertex set of the interval matrix A = [A-, A+] in R^...

The concept of diagonally invariant exponential stability (abbr. DIES) was originally introduced for single-model linear systems and subsequently expanded in the study of linear systems with interval-type uncertainties and linear systems with arbitrary switching. The results presented in this article refer to new approaches to DIES characterization...

See DOI ____ The paper focuses on the class of Lyapunov functions defined by diagonally weighted Holder vector p-norms for arbitrary switching linear systems with discrete-time dynamics. Our work is motivated by the simple forms of such Lyapunov function candidates, as well as by the mathematical perspective of getting a generalized result able to...

See DOI. ____ Our work comments a result on common diagonal Lyapunov functions (CDLFs), reported by a recent article, and proposes a substantial extension. The discussed result refers to sets of continuous-time positive linear time-invariant (LTI) systems and ensures the existence of CDLFs with quadratic form. We prove that exactly the same hypothe...

See DOI. _______ For stability analysis of discrete-time arbitrary switching positive linear systems, we introduce a new class of switched copositive Lyapunov functions (abbreviated as CLFs) and we investigate their test power. The new class means “switched max-type CLFs” and it is defined by generalizing the “mode-independent max-type CLFs” (that...

See DOI. ____ The paper provides new results for testing the flow-invariance of time-dependent sets with arbitrary shapes, with respect to trajectories of continuous-time nonlinear systems. The approach represents a generalization of a criterion used in the qualitative analysis of ordinary differential equations with solutions in closed sets with h...

See DOI. ______ Metzler matrices are algebraically characterized by having nonnegative off-diagonal entries and, from the dynamical point of view, define continuous-time positive systems. Our work studies polytopes of Metzler matrices and linear dynamics generated by such sets. The first part of the paper explores the algebraic properties of matrix...

See DOI ____ The paper considers the dynamics of discrete-time polytopic systems. Two types of results are presented. The first type refers to the estimation of the spectrum location for the matrix polytope that defines the behavior of a given system. The approach relies on the theory of representatives applied to a set of nonnegative matrices buil...

See DOI. _______ The paper considers switched positive linear systems that operate with either arbitrary switching or average dwell time. For each operation manner, two types of stability criteria with complementary forms are presented, which provide distinct sufficient conditions for exponential stability of the system. The complementarity refers...

See DOI ____ The Schur, respectively Hurwitz, diagonal stability of a complex interval matrix C relative to a Hölder p-norm, 1 ≤ p ≤ ∞, abbreviated as SDSp, respectively HDSp, is defined in terms of a matrix inequality using the respective norm. This approach generalizes the SDSp, respectively HDSp, of real interval matrices previously studied by t...

See full-text. _______ The paper studies the set invariance properties exhibited by the linear dynamics of interval matrix systems (abbreviated IMSs). The considered sets have non-symmetrical shapes defined by arbitrary Hölder p-norms and are exponentially contractive (with exponential timedecrease). For such sets we provide two types of results th...

See full-text. _______ Consider an arbitrary switching positive system whose (discrete-or continuous-time) dynamics is defined by the matrix set A. The class of copositive Lyapunov functions called "polyhedral" is characterized by necessary and sufficient conditions derived from the solvability of some inequalities built with the matrices in A, and...

See DOI ___ The paper proposes an algebraic setting for the concrete construction of linear copositive Lyapunov functions associated with arbitrary switching positive systems; this approach complements a series of already reported results that are limited to the existence problem. Our development encompasses both discrete- and continuous-time dynam...

See DOI ___ The paper proposes a series of developments to the switched linear copositive Lyapunov function (SLCLF) method, applied for the stability analysis of arbitrary switching discrete-time linear systems. The new results refer to the integration of quantitative information on the SLCLF decreasing rate with the existing SLCLF framework that m...

The main purpose of this work is to show that the Perron-Frobenius eigenstructure of a positive linear system is involved not only in the characterization of long-term behavior (for which well-known results are available) but also in the characterization of short-term or transient behavior. We address the analysis of the short-term behavior by the...

See DOI. _______ Our paper proposes a framework that allows the construction of several types of diagonal Lyapunov functions for discrete- and continuous-time interval systems. The Lyapunov function candidates are defined as weighted vector norms, where the weighting matrices are diagonal and positive definite. For the existence of such Lyapunov fu...

See DOI. ________ The first part of this article presents invariance criteria for a stochastic differential equation whose state evolution is constrained by time-dependent security tubes. The key results of this section are derived by considering an equivalent problem where the square of distance function represents a viscosity solution to an adequ...

See DOI. _________ Let C=A+jB be a complex interval matrix, where A,B\inR^(n×n) are real interval matrices, and j^2=−1; denote by D+ the set of positive definite diagonal n×n matrices. The Schur [respectively Hurwitz] diagonal stability of C, abbreviated as SDS [respectively HDS], is defined in terms of the Stein [respectively Lyapunov] inequality...

See DOI. _________ The paper aims to expand the stability analysis framework based on copositive Lyapunov functions (CLFs) for arbitrarily switching positive systems with continuous- or discrete-time dynamics. The first part focuses on max-type CLFs. It provides an algebraic characterization (in terms of weak quasi-linear inequalities), as well as...

See DOI. _______ Our work discusses a conjecture formulated for supporting the stability analysis of polytopic systems, within the context of enlarging our explorations from real to complex statespace models. This conjecture refers to a property of the spectral radius that is true for real matrices and we assumed to be adaptable to complex matrices...

See DOI. _______ The paper proposes two estimation methods for the spectral radius of a complex interval matrix. These methods exploit different properties of the interval matrix and construct distinct numerical approaches, so that their results dispute, from case to case, the precision of the estimation. This complementarity of the two methods rec...

See DOI. _______ The paradigm of Petri nets offers a rich modeling power that has been successfully exploited in many different application domains as manufacturing, logistic, traffic, computer and biological domains. In order to develop and analyze Petri models in an efficient and systematic way, appropriate software tools are required. Among the...

See full-text (Contents). In Romanian (158 p). _______ Cartea îşi propune un studiu al modelelor matematice ale sistemelor fizice, atât din punct de vedere analitic, cât şi din punct de vedere al simulării pe calculator. Un astfel de studiu are drept scop înţelegerea conexiunilor ce există între descrierile matematice ale dinamicilor şi comportarea...

See DOI. ______ Our work proposes two methods that estimate the eigenvalue bounds (left/right for real and imaginary parts) of complex interval matrices. The first method expresses each bound as an algebraic sum of weighted matrix measures, where the measure corresponds to the spectral norm and the weighting matrix is diagonal and positive definite...

See full-text (Contents). In Romanian (340 p). _______ Materialul este orientat pe studierea sistemelor dinamice liniare şi continue. Sunt abordate probleme care includ construcţia de modele matematice pentru sisteme fizice, analiza acestor modele şi controlul în buclă închisă al proceselor. Astfel, cartea oferă un suport de studiu atât celor care...

See DOI. ________ Our paper explores the solvability of the closed Leontief models, described by weak inequalities. We analyze the existence of two types of solutions defined for such models, namely feasible and, respectively equilibrium solutions. Our developments take into consideration the role of the following elements that characterize the mod...

See full-text (Chapter Contents). In Romanian (90p). _______ Sistemele cu evenimente discrete (acronim consacrat SED) sunt sisteme dinamice , invariante in timp, neliniare, cu stari discrete, a caror evolutie este determinata de aparitia evenimentelor.

The paper considers the class of matrix polytopes with a dominant vertex and the class of uncertain dynamical systems defined in discrete time and continuous time, respectively, by such polytopes. We analyze the standard concept of stability in the sense of Schur—abbreviated as SS (resp., Hurwitz—abbreviated as HS), and we develop a general framewo...

See DOI. ______ The paper proposes a methodology for estimating the eigenvalue bounds of complex interval matrices. The theoretical development is based on the use of matrix measures induced by arbitrary absolute and monotone vector norms, as well as the weighting of the matrix norms (implicitly of the matrix measures) by diagonal matrices with pos...

See DOI. ______ Nagumo's condition, also known as the sub-tangency condition, characterizes the set invariance with respect to the trajectories of dynamical systems. The general formulation of Nagumo's condition considers a comprehensive framework, referring to time-variant nonlinear systems and generic sets with arbitrary shapes. For time-variant...

See IEEE Xplore. ________ The research explores the robustness of closed-loop CWEAS (componentwise exponential asymptotic stability) with respect to plant and/or controller uncertainties. The main focus is placed on the fragility/nonfragility analysis that quantifies the controller contribution to the closed-loop robustness. We develop a computer-a...

See IEEE Xplore. _____ A matrix M ∈ ℝnxn is a P0-matrix if every principal minor of M is nonnegative. We use this concept in a generalized form, called row (column)-P0-property, which refers to a finite set of matrices M = {M1,..., MN} ⊂ ℝnxn. In the current work, the set M collects matrices of the form Mθ = Aθ - rI, θ = 1,..., N, with Aθ ∈ ℝnxn es...

See DOI. _____ By considering arbitrary Holder p-norms in the state space, the current paper studies the existence of exponentially contractive sets that are invariant with respect to the trajectories of discrete-time switching linear systems. We first provide necessary and sufficient conditions for testing if state-space sets (characterized by cer...

See DOI. _______ The paper proposes analysis and design techniques for switching linear systems (whose commutations occur in an arbitrary manner from the internal dynamics point of view, being determined by exogenous agents). We define and characterize (by “if and only if” conditions) two properties, namely (i) diagonally invariant exponential stab...

The paper develops a study on the evaluation of right bounds for the eigenvalue ranges of interval matrices. Given an arbitrary interval matrix  , a right bound approximates the right end point of the eigenvalue range -defined as an exact value, denoted by () I  , which, generally speaking, is not directly calculable. We consider two classes of m...

See DOI. ___________ This article analyses the flow (positive) invariance of different types of time-dependent sets with respect to the dynamics of interval systems (state-space models described by interval matrices) in both discrete and continuous time. The investigated sets have general shapes, defined in terms of Hőlder vector p-norms, . The tim...

See IEEE Xplore. _______ The paper proposes a new approximation method for the upper and lower bounds of the real parts of interval matrix eigenvalues. As a theoretical support, we exploit the properties of the matrix measures corresponding to monotonic (or, equivalently, absolute) vector norms. The numerical approach focuses on the use of the resu...

See IEEE Xplore. ________ For polytopic matrices and polytopic systems we introduce the concept of diagonal stability with respect to a p-norm, 1 ≤ p ≤ ∞. We address both the discrete-time and the continuous-time cases. We prove the equivalence between this algebraic concept and the following properties of uncertain linear dynamics described by pol...

See IEEE Xplore. ________ An algorithmic framework is developed for auto- matic deployment of car-like robots based on Linear Temporal Logic (LTL) formulae over a set of regions of interest in the environment. The environment and the regions of interest are a priori known, and the robot has non-negligible size and restricted steering capabilities....

See DOI. ___________ The paper presents a procedure for creating a probabilistic finite-state model for a mobile robot and for finding a sequence of controllers ensuring the highest probability for reaching a desired region. The approach starts by using results for controlling affine systems in simpliceal partitions, and then it creates a finite re...

See DOI ________ The paper improves the existing qualitative results on switched positive systems () () j x t A x t = ɺ , 1, , j N = … , by using non-strict quasilinear inequalities of the form T T j v A rv = ≺ , 0 r < , 0 v ≻ (in place of strict linear inequalities 0 T j v A ≺ , 0 v ≻) and invoking the Perron-Frobenius eigenstructure for essential...

See DOI. ______ The first part of this note identifies and analyzes two weak points of the commented paper . i) Example 1 reports an incorrect result for which we provide a complete explanation and correction. ii) The practical use of Theorem 1 reveals major drawbacks such as a severe limitation in the applicability (due to the restrictive conditio...

See DOI. ____ The paper revisits the boundedness for the trajectories of cellular neural networks (abbreviated as CNNs) and proposes a refined approach to this property. Our refinement envisages sufficient conditions for the existence of invariant sets with respect to the CNN dynamics. First, we construct a general framework which considers bounded...

Tome LVII (LXI), Fasc. 1, pp. 71 - 85, Zbl Math 1363.93066. See full-text. ______ The existence of important connections between the dynamics of discrete-time linear systems and matrix algebra is well-known even at the level of undergraduate courses dealing with state-space models. Nevertheless the emphasis is traditionally placed on the eigenvalue...

Let AI={A∈Rn×n|A-⩽A⩽A+} be an interval matrix and 1⩽p⩽∞. We introduce the concept of Schur and Hurwitz diagonal stability, relative to the Hölder p-norm, of AI, abbreviated as SDSp and HDSp, respectively. This concept is formulated in terms of a matrix inequality using the p-norm, which must be satisfied by the same positive definite diagonal matri...

Vol. XXX, pp. 159-169. ______ A general framework has been developed to explore the positively (flow) invariant sets, for a large class of time-variant, nonlinear dynamical systems. Thus, we introduce the concept of “diagonal invariance” defined by timedependent diagonal matrices and for arbitrary H¨older norms. The flow invariance results are form...

See full-text. _______ This paper discusses the practical utilization of a mathematical result reported in the interval matrix literature, which provides estimations for the right-end points of the eigenvalue ranges. Our investigation is motivated by the fact that very few results of this type are available for the analysis of interval matrices; at...

See DOI. _______ For linear time-variant systems x˙(t)=A(t)x(t), we consider Lyapunov function candidates of the form Vp(x,t)=||H(t)x||p, with 1≤p≤∞, defined by continuously differentiable and non-singular matrix-valued functions, H(t):R+→Rn×n. We prove that the traditional framework based on quadratic Lyapunov functions represents a particular cas...

The paper considers parametric uncertain systems of the form , where is either a convex hull, or a positive cone of matrices, generated by the set of vertices . Denote by the matrix measure corresponding to a vector norm . When is a convex hull, the condition , , is necessary and sufficient for the existence of common strong Lyapunov functions an...

See full-text (Chapter Contents). In Romanian (87p). ________ Activitatea de modelare constă în definirea unui ansamblu de reprezentari matematice ale sistemelor, in masura sa sustina varietatea abordarilor din problemele de analiza si proiectare, impuse de specificul proceselor conduse si de cerintele de performanta solicitate. Acest capitol este...

See DOI. ________ For linear time-variant systems x(t) = A(t)×(t), we consider Lyapunov function candidates of the form Vp(x,t) = H(t)xp, with 1≤p≤∞, defined by matrix-valued functions, H(t): R+ → Rn×n, continuously differentiable and non-singular. We prove that the traditional framework based on quadratic Lyapunov functions represents a particular...

See DOI. ________ The paper explores the flow (positively) invariant sets with respect to the trajectories of recurrent neural networks (RNNs). There are considered two types of sets, namely with arbitrary time-dependence and exponentially decreasing. The sets can have general shapes, defined by Hölder p-norms. The first part of the paper develops...

See DOI. ________ Significant research effort has been directed towards developing vehicle systems that reduce the energy consumption of an automobile and because pressure control valves are used as actuators in many control applications for automotive systems, a proper dynamic model is necessary. Starting from equations found in literature, where...

The class of instruments available for set invariance analysis with respect to linear system dynamics is significantly wider for sets that are symmetrical (relative to the state space origin), compared with the nonsymmetrical case. Our work provides a new result for testing the invariance of non symmetrical sets, described by general forms. For any...

Control valves are the mechanical (or electrical) to fluid interface in hydraulic systems, and the knowledge of their performance characteristics is essential. Pressure control valves employ feedback and may be properly regarded as servo control loops. Because of that, a proper dynamic design is necessary to achieve stability. Starting from equatio...

See DOI. ______ In this paper we propose a new scheme based on adaptive critics for finding online the state feedback, infinite horizon, optimal control solution of linear continuous-time systems using only partial knowledge regarding the system dynamics. In other words, the algorithm solves online an algebraic Riccati equation without knowing the...

Bulletin of the Polytehnic Institute of Iaşi. Automatic Control and Computer Science Tome LV (LIX), Fasc 4, pp 9–28. Zbl Math 1212.93006 ______________ During the last few years automotive actuators have become mechatronic systems in which mechanical components coexist with electronics and computing devices and because pressure control valves are...

Invariant-set-based techniques represent a research direction in systems engineering emerged during the last two decades. The authors of the current paper have brought some noticeable contributions to the development of this direction. The exposition of our results is connected to the international evolution of the field. Our material offers an ove...

See full-text (Contents). In English (x + 150 p). Software Petri Net Toolbox https://www.mathworks.com/products/connections/product_detail/petri-net-toolbox.html _______________________________________________________________________ This book presents the package Petri Net Toolbox (abbreviated as PN Toolbox) for MATLAB, which bridges the PN forma...

See full-text (Contents). In Romanian (v+174 p). _______ Cartea prezinta câteva teme de studiu care au fost considerate drept esenţiale pentru introducerea cititorului în universul amplu al reţelelor neurale artificiale. Parcurgerea acestor teme asigură înţelegerea proprietăţilor de clasificare şi aproximare pe care le posedă anumite tipuri de reţe...

Many works dealing with the stability analysis of interval systems developed criteria based on matrices that majorize (in a certain sense) the interval matrices describing the system dynamics. Besides this already classical employment, we prove that the majorant matrices also contain valuable information for the study of the exponentially decreasin...

See DOI. ____ The componentwise stability of a linear system is a special type of asymptotic stability induced by the existence of exponentially decreasing rectangular sets that are invariant with respect to the free response. An interval system () () () x t Ax t Bu t = + , [ , ] A A A − + ∈ , [ , ] B B B − + ∈ , is componentwise stabilizable if th...

See DOI. ______ The paper presents mathematical developments that support new design techniques for constrained stabilization of linear systems. The constraints can operate on (i) state variables, (ii) state variables and feedback matrix gain, or (iii) state variables and control actions. The state variable constraints in (i) - (iii) exploit the pr...

Buletinul Institutului Politehnic din Iaşi, Automatic Control and Computer Science Section, Tome LIV (LVIII), Fasc 1, pp. 25-34, Zbl Math 1210.93073. See full-text. __________ The paper considers state-space observers for continuous- and discrete-time linear systems. The estimation accuracy can be increased if, for the error equation, the component...

See full-text (Contents). In Romanian (viii + 108 p). _____ Cartea propune o colecţie de teme de studiu pe care experienţa noastră didactică şi de cercetare le recomandă drept elemente cheie pentru manipularea reţelelor Petri. Parcurgerea temelor propuse asigură acumularea de cunoştinţe privind mai multe tipuri de reţele Petri (reţele netemporizate...

See full-text. ______ This paper formulates and proves two types of necessary and sufficient conditions for the characterization of positively (flow) invariant sets with respect to the state-space trajectories of the time-varying (non-autonomous) linear systems in both continuous- and discrete-time case. These conditions are expressed in terms of i...

See full-text. _______ The paper develops an extensive analysis of the time-dependent sets that are positively invariant with respect to the dynamics of interval matrix systems. The interval matrix systems may be described by discrete-or continuous-time equations. For the invariant sets, the time dependence is considered arbitrary, and the shape is...

See DOI. ______ The paper generalizes the concept of diagonal-type Lyapunov functions for arbitrary Holder vector p-norms, 1lesplesinfin. For p=2 this is equivalent with the usual quadratic form V(x)=x^TDeltax, where Delta is a positive definite diagonal matrix, x is a real vector, and T denotes transposition. We provide concrete expressi...

See DOI. ___ In this paper we propose a new adaptive critic scheme for finding on-line the state feedback, infinite-horizon, optimal control solution of linear continuous-time systems using only partial knowledge regarding the system dynamics, i.e. no knowledge regarding the system A matrix is needed. This is in effect an adaptive control scheme fo...

See DOI. ____ The paper explores the connections between the Perron-Frobenius (PF) theory and the flow-invariant sets with respect to the dynamics of linear systems. Our analysis includes both discrete-and continuous-time systems, and the results are separately formulated for linear dynamics generated by the following types of matrices: (i) (essent...

See DOI. ______ The paper explores the role played by the majorant matrices in the qualitative analysis of interval systems with discrete- or continuous-time dynamics. We prove that, besides the classical usage in stability testing, the majorant matrices provide valuable information for the study of the exponentially decreasing sets, invariant with...

The paper considers a class of continuous-time linear systems with uncertain parameters and develops a methodology for the design of linear feedback laws which, besides stabilization, ensure the constraining of the state-space trajectories inside contractive boxes exponentially decreasing to the equilibrium point. These constraints allow a continuo...

See full-text. ___ The paper presents the most relevant issues of our didactic experience accumulated during eight years of teaching physical modeling based on the bond-graph method (BGM). First we analyze the necessity of bridging the standard knowledge of Physics to the construction of Control Engineering models and emphasize the strong points of...

Scientific Bulletin of The POLITEHNICA University of Timisoara, Transaction on Automatic Control and Computer Science, vol. 52 (66), no. 1, p. 31-36. See full-text. _______ The paper develops novel criteria for the stability analysis of positive linear systems. Unlike traditional approaches focusing on quadratic-type Lyapunov functions, we conside...

Vol. 9 (59), no. 1, pp. 61-75. Zbl Math 1150.34020 _________ The Bidirectional Associative Memories (BAMs) represent an important category of recurrent neural networks with continuous-time (CT) or discrete time (DT) dynamics, described by differential equations or difference equations, respectively. The paper considers the general case of BAMs with...

See DOI. ______ Let A = (aij) be a real square matrix and 1 ≤ p ≤ ∞. We present two analogous developments. One for Schur stability and the discrete-time dynamical system x(t + 1) = Ax(t), and the other for Hurwitz stability and the continuous-time dynamical system over(x, ̇) (t) = Ax (t). Here is a description of the latter development. For A, we...

The paper provides new results for the state-space analysis of positive linear systems, with arbitrary initial conditions and constant input signals. These results explore the invariance properties in the dynamics of asymptotically stable positive linear systems. We prove there exist families of time-dependent sets, defined in terms of Hölder p-nor...

See DOI. _____ The paper provides new results on the flow (positive) invariance of the families of 0-symmetrical sets, which are defined by arbitrary Hölder norms and time-dependent diagonal matrices. Thus, we introduce the concept of “diagonal invariance” as a system property with local or global character. For this property, we formulate sufficie...

The Petri Net Toolbox (PN Toolbox) for MATLAB is a software package that offers instruments for the simulation, analysis and design of untimed, deterministic and stochastic P-/T-timed and stochastic Petri nets (PNs). The facilities available in this toolbox are appropriate for studying the dynamics of many classes of discrete-event systems. The Pet...

See full-text. ______ The Faculty of Automatic Control and Computer Science within Technical University "Gheorghe Asachi" of Iasi, one of the leading training and research centre in the field of automatic control and computer science from Romania, has celebrated in the University year 2002 – 2003 40 years from the appearance of the first courses in...

Scientific Bulletin of The POLITEHNICA University of Timisoara, Transaction on Automatic Control and Computer Science, vol: 51(65), no: 2, pp.29-34. See full-text. ______ Neural-network-based classification is a classical topic for the training programs in various areas of applied informatics and computer engineering. Therefore the organization of...