Jacek Mazurkiewicz

Complex Systems and Dependability

Typical contemporary complex system is a multifaceted amalgamation of technical, information, organization, software and human (users, administrators and management) resources. Complexity of such a system comes not only from its involved technical and organizational structure but mainly from complexity of information processes that must be implemented in the operational environment (data processing, monitoring, management, etc.). In such case traditional methods of reliability analysis focused mainly on technical level are usually insufficient in performance evaluation and more innovative methods of dependability analysis must be applied which are based on multidisciplinary approach to theory, technology and maintenance of systems operating in real (and very often unfriendly) environments. This monograph presents selected new developments in such areas of dependability research as system modelling, tools and methodologies for system analysis, data security, secure system design and specific dependability aspects in specialized technical applications. Many practical cases illustrate the universal rule that complexity and multiplicity of system processes, their concurrency and their reliance on embedded intelligence (human and artificial) significantly impedes construction of strict mathematical models and calls for application of intelligent and soft computing methods.

Analysis of Critical Situations in Discrete Transport Systems

A paper presents an approach to critical situations analysis related to discrete transport systems (DTS). The critical situation is understood as sudden shortage of some system recourses resulting in the transport system performance degradation. The analysis is realized based on availability calculation of DTS. The system is described by the formal model, which includes reliability and functional parameters of DTS. The availability and average availability of the system - defined in a functional way by delayed tasks realization – is discussed as a function of different essential parameters when the DTS is organized. The proposed analysis is based on the modeling and simulating of the system behavior using Monte-Carlo approach. The paper presents some exemplar systems – based on real Polish Post DTS - modeling and results.

New Results in Dependability and Computer Systems

DepCoS RELCOMEX is an annual series of conferences organized by the Institute of Computer Engineering, Control and Robotics (CECR), Wrocaw University of Technology, since 2006. Its idea came from the heritage of the other two cycles of events: RELCOMEX Conferences (1977 89) and Microcomputer Schools (1985 95) which were then organized by the Institute of Engineering Cybernetics, the previous name of CECR. In contrast to those preceding meetings focused on the conventional reliability analysis, the DepCoS mission is to develop a more comprehensive approach to computer system performability, which is now commonly called dependability. Contemporary technical systems are integrated unities of technical, information, organization, software and human resources. Diversity of the processes being realized in the system, their concurrency and their reliance on in-system intelligence significantly impedes construction of strict mathematical models and calls for application of intelligent and soft computing methods. The submissions included in this volume illustrate variety of problems that need to be explored in the dependability analysis: methodologies and practical tools for modeling, design and simulation of the systems, security and confidentiality in information processing, specific issues of heterogeneous, today often wireless, computer networks, or management of transportation networks.

Functional availability analysis of discrete transport system simulated by SSF tool

The paper presents an approach to availability calculation of discrete transport system (DTS). The system is described by the formal model, which includes reliability and functional parameters of DTS. The availability and average availability of the system – defined in a functional way – is discussed as a function of different essential parameters when the DTS is organised. The proposed analysis is based on the modelling and simulating of the system behaviour. Monte Carlo simulation is used to encourage reliability and stochastic functional parameters. The simulator is built using scalable simulation framework (SSF). No restriction on the system structure and on a kind of distribution is the main advantage of the method. The paper presents some exemplar system modelling and results.

Economic analysis of discrete transport systems

A method of economic, reliability and functional analysis related to discrete transport systems is presented. The proposed analysis is based on observations of changes of states and their coincidence. The Monte Carlo simulation is used for proper reliability and functional parameters calculation. No restriction on the system structure and on a kind of distribution is the main advantage of the method. The problem is essential in vehicle maintenance defining. Authors present an exemplar system analysis.

Functional Availability Analysis of Discrete Transport System Realized by SSF Simulator

The paper describes a novel approach to functional availability analysis of discrete transport systems realized using Scalable Simulation Framework (SSF). The proposed method is based on modeling and simulating of the system behavior by Monte Carlo simulation. No restriction on the system structure and on a kind of distribution is the main advantage of the method. The paper presents some exemplar system modeling. The authors stress the problem of influence of the functional parameters on final system availability. The problem described in the paper is practically essential for defining an organization of vehicle maintenance and transport system logistics.

Fuzzy Economic Analysis of Simulated Discrete Transport System

The paper presents fuzzy economic analysis of discrete transport systems in a function of system element reliability. Such approach can be used for a description of different problems related to transport logistics. No restriction on the system structure and on a kind of distribution is the main advantage of the proposed solution. Additionally the results of reliability and functional analysis can be used as a basis for economic aspects discussion related to discrete transport system. Fuzzy approach allows to reduce the problem of assumptions of reliability distributions.

Neural network and optical correlators for infrared imaging based face recognition

This paper deals with the problem of thermovision application for biometric people recognition. The main goal of research was the automatization of recognition process and proving, whether the infrared imaging can be exploited for realization of the biometric system. First, the data base composed of 270 images made in different conditions, was built. Next, the multilayer perception and two optical correlators such as joint transform correlator and 4f correlator, were applied. Each system was designed for realizing two various tasks: verification and identification. Finally, the systems were tested and evaluated according to the Face Recognition Vendor Tests (FRVT). Achieved results proved that temperature distribution on the human face is a biometric trait and people can be efficiently recognized with usage of infrared imagery.

Comparison of data driven models for the valuation of residential premises using KEEL

The experiments aimed to compare data driven models for the valuation of residential premises were conducted using KEEL (Knowledge Extraction based on Evolutionary Learning) system. Twelve different regression algorithms were applied to an actual data set derived from the cadastral system and the registry of real estate transactions. The 10-fold cross validation and statistical tests were applied. The lowest values of MSE provided models constructed and optimized by means of support vector machine, artificial neural network, decision trees for regression and quadratic regression, however differences between them were not statistically significant. Worse performance revealed algorithms employing evolutionary fuzzy rule learning. The experiments confirmed the usefulness of KEEL as a powerful tool with its numerous evolutionary algorithms together with classical learning approaches to carry out laborious investigation on a practical problem in a relatively short time.

Availability of Discrete Transport System Simulated by SSF Tool

A paper presents an approach to availability calculation of discrete transport system (DTS). The system is described by the formal model, which includes reliability and functional parameters of DTS. The availability and average availability of the system - defined in a functional way - is discussed as a function of different essential parameters when the DTS is organized. The proposed analysis is based on the modeling and simulating of the system behavior. Monte Carlo simulation is used to encourage reliability and stochastic functional parameters. The simulator is built using scalable simulation framework (SSF). No restriction on the system structure and on a kind of distribution is the main advantage of the method. The paper presents some exemplar system modeling and results.