Kołowrocki Krzysztof, Kwiatuszewska-Sarnecka Bożena, Soszyńska-Budny Joanna
Reliability and risk improvement with components quantitative and qualitative redundancy of bulk cargo transporter
The joint general model of reliability of complex technical systems at variable operation conditions linking a semi-Markov modelling of the system operation processes with a multi-state approach to system reliability analysis and reliability improvement are applied in maritime transport to reliability and risk optimization of a bulk cargo transportation system.[full text]
Kołowrocki Krzysztof, Soszyńska-Budny Joanna
Complex system operation cost optimization
The general model of a complex system changing its safety structure, its components safety parameters and its operation cost during the variable operation process and linear programming are applied to optimize the system operation process in order to get the system operation cost optimal values. The optimization problem allowing to find the optimal values of the transient probabilities of the complex system operation process at the particular operation states that minimize the system unconditional operation cost mean value in the safety states subset not worse than a critical system safety state under the assumption that the system conditional operation cost mean values in this safety state subset at the particular operation states are fixed is presented. Further, the procedure of finding the optimal values operation cost is presented and applied to the exemplary complex technical system.[full text]
Kołowrocki Krzysztof, Torbicki Mateusz
Reliability of large three-dimensional nanosystems
Basic notions and agreements on reliability of three-dimensional nanosystems are introduced. The asymptotic approach to the three-dimensional nanosystem reliability investigation is presented and the nanosystem limit reliability function is defined. Auxiliary theorems on limit reliability functions of three-dimensional nanosystems composed of large number of independent nanocomponents are formulated and the classes of limit reliability functions for a homogeneous series and series-parallel nanosystems are fixed. A model of a three-dimensional series and series-parallel nanosystem with dependent nanocomponents is created and the class of limit reliability functions identical with the class in the previous case is fixed as well. The asymptotic approach to reliability evaluation of exemplary three-dimensonal series and series-parallel nanosystem with dependent nanocomponents is presented and its accuracy is discussed.[full text]
Kosmowski Kazimierz T., Śliwiński Marcin, Piesik Emilian
Integrated safety and security analysis of hazardous plants and systems of critical infrastructure
This article addresses an integrated safety and security analysis approach of hazardous industrial plants and systems of critical infrastructure. Nowadays due to new hazards that emerge there are opinions among experts that these issues require an integrated approach in life cycle, from the design concept, through the design and operation of the plant, to its decommissioning. It is proposed to start from an interesting methodology known as the security vulnerability analysis (SVA) developed for hazardous plants of chemical industry. It is based on rings of protection concept to secure widely understood assets. This concept seems to be compatible with layer of protection analysis (LOPA), which is consistent with functional safety concept of the control and protection systems including cyber security aspects. It is outlined how to use these approaches in an integrated way for safety and security analysis of hazardous industrial plants and systems of critical infrastructure.[full text]
Kosmowski Kazimierz T.
Designing issues of the alarm system in context of functional safety and human factors
This article addresses selected aspects of the alarm system and human factors that should be evaluated during the design and operation of an industrial hazardous installation. In such installations the layer of protection analysis (LOPA) methodology is often applied for simplified risk analysis based on defined accident scenarios. To reduce and control the risks the safety instrumented functions (SIFs) are identified and their safety integrity levels (SILs) determined taking into account defined criteria the risk evaluation results. Given SIF is implemented using the basic process control system (BPCS), the alarm system (AS) and the safety instrumented system (SIS). Nevertheless a crucial role plays the human-operator undertaking safety-related decisions during potential abnormal situations and accidents. Below some issues concerning requirements for the alarm system design in context of human factors are outlined and discussed.[full text]
Kosmowski Kazimierz T.
Methodological issues of functional safety and reliability assessment of critical systems in industrial hazardous plants
The aim of this article is to identify and discuss some methodological issues that are of interest among functional safety specialists and experts after publication of the second edition of international standards IEC 61508 and IEC 61511, including the design and implementing the safety-related functions of higher safety integrity levels and protection layers. The basic role of safety-related systems is to reduce effectively and to control in time the individual and/or societal risk with regard to its tolerable levels. These issues include: risk criteria, reliability data, probabilistic models of systems operating in high and/or low mode, dependent failures, human reliability analysis, security of programmable safety-related systems, and reducing uncertainty issues in decision making process applying the cost-benefit analysis. Selected aspects of these issues are discussed and some challenges requiring further research are indicated.[full text]
Kostogryzov Andrey, Nistratov Andrey, Zubarev Igor, Stepanov Pavel, Grigoriev Leonid
About accuracy of risks prediction and importance of increasing adequacy of used probabilistic models
The work purpose is the quantitative proof of importance and necessity of increasing adequacy of probabilistic models, described by probability distribution functions (PDF) of time between losses of system integrity. For purpose achievement the analysis of probabilistic metrics of risks and the elementary forms to establish an admissible risks is carried out, some ways of increasing an adequacy of probabilistic models for complex structures are described. Possibilities of extracting the latent knowledge from an adequate PDF are shown. Practical value of the researches are the revealed possibilities for a substantiation of more effective system decisions at the expense of increasing accuracy of risks prediction. Effects are demonstrated by examples.[full text]
Kwiatuszewska-Sarnecka Bożena
Reliability and risk function improvement of bulk cargo transportation system
In the paper the basic notions of the ageing multistate systems reliability analysis are introduced. The multistate system reliability functions are defined and the mean values of the multistate system lifetimes in the reliability state subsets and in the particular reliability states are determined. The notion of the multistate system risk function and the moment of the system exceeding the critical reliability state are introduced. Further, in the developed reliability models, it is assumed that the system’s components have the multistate Weibull reliability functions with various parameters in their different reliability state subsets. Under this assumption, the proposed multistate system reliability models are applied in maritime transport to the reliability analysis of a bulk cargo transportation system and its reliability function, moreover other main characteristics are determined.[full text]
Malinowski Jacek
A Markov model of a complex technical system operating in basic and emergency modes
A complex technical system built of independent repairable components with constant failure and repair rates is examined. The system can operate in either basic or emergency mode, and its behavior is modeled by a three-state Markov process. It is demonstrated how to obtain closed formulas for the state probabilities of this process and the so-called importances of individual components to the inter-state transitions. Such an importance is defined as the probability that a component’s failure/repair causes a transition between two given states of the modeling process. The obtained formulas allow to compute a number of reliability parameters characterizing the dynamics of the system’s operation. The obtained results are illustrated by their application to an exemplary reliability block diagram that can be a model of a power supply network, a gas or oil pipeline system, etc.[full text]
Mazurkiewicz Jacek
Network transport systems dependability analysis with critical situations discussion
The paper describes the analysis and discussion of the transport network systems in case of the critical situation that happens during ordinary work. The formal model is proposed –the point of view combines hardware and software resources as well as task definition and dispatcher role. The types of failure, procedures and methodology to reduce the consequences of the system faults are pointed and categorized. The functional and reliability measures are defined. The approach to modeling is based on the system behavior observation. The definition of the critical situation sets are created by reliability, functional and human reasons. No restriction on the system structure and on a kind of distribution describing the system functional and reliability parameters is the main advantage of the approach. The proposed solution seems to be essential for the owner and administrator of the transportation systems.[full text]
Rakowsky Uwe Kay
On the basic concepts of safety engineering
The basic concepts of safety engineering and functional safety frameworks are presented and discussed in this paper. The scope includes safety aspects, which are deeply rooted in philosophy e.g. the principles of causality, determinability, and randomness. Moreover, concepts are presented, which are subject of standardisation, engineering association activities, and aspects, practitioners struggling with in daily business, e.g. failure and fault; architecture and structure; redundancy and channels. The paper closes with a brief glance on engineering ethics.[full text]
Sugier Jarosław
Efficiency of FPGA architectures in implementations of AES, Salsa20 and Keccak cryptographic algorithms
The aim of this paper is to test efficiency of automatic implementation of selected cryptographic algorithms in two families of popular-grade FPGA devices from Xilinx: Spartan-3 and Spartan-6. The set of algorithms include the Advanced Encryption Standard (AES) used worldwide as a symmetric cipher along with two hash algorithms: Salsa20 (developed with ECRYPT Stream Cipher Project) and Keccak permutation function (core of the new SHA-3 standard). The ciphers were expressed in 5 architectures: the basic iterative one (one instance of a round in hardware) and its four derivatives created by loop unrolling and pipelining. With each of the architectures implemented in both Spartan devices this gave the total of 30 test cases, which, upon automatic implementation, created a comprehensive and consistent base for comparison of the ciphers, applied architectures and FPGA devices used for implementation.[full text]
Kołowrocki Krzysztof, Tchórzewska-Cieślak Barbara, Piegdoń Izabela
Modelling reliability of water supply network
The operation process of the complex technical system is considered and its operation states are introduced. The semi-Markov process is used to construct a general probabilistic model of the considered complex technical system operation processes. Further, a general reliability analytical model of complex two-state technical systems related to their operation processes is constructed. An exemplary application of this model to a simplified fragment of the main water supply network operating at variable conditions is presented as well.[full text]
Tchórzewska-Cieślak Barbara, Pietrucha-Urbanik Katarzyna, Bajer Jarosław
Crisis situation management issues in urban areas water supply
In paper the methods of comprehensive analysis of reliability, safety and operation of the water supply system were presented. The main goal of this work is to present the problems associated with the WSS functioning in terms of belonging to critical infrastructure. The analysis of the WSS functioning in face of emergency events occurrence should be one of the priority actions taken by the water companies. The paper presents an application of reliability and safety analysis of water supply in emergency situations.[full text]
Walkowiak Tomasz
Fuzzy quality analysis of web services implemented in virtualised environment
The paper describes the quality analysis of web services implemented in virtualised environment. It takes into account the reliability and performance aspects of software and hardware elements of the web service. The presented state-transitional model considers the reconfiguration process to maintain the continuity of business services. The reconfiguration is based in on the redeployment of virtual machines so for some time the system operates in a degraded state. Author propose two quality measures based on the web service availability and maximum handled requests calculated at each of degradation levels. Moreover, authors proposed to model the web service reliability parameters by fuzzy numbers. A method for calculating fuzzy membership functions of quality measures are also presented.[full text]
Woch Marta
Comparison evolutionary algorithms with Metropolis-Hastings method exemplified by high-fatigue Wohler curve parameter identification
In this work, evolutionary algorithms together with the Metropolis-Hastings sampling technique have been used for parameter identification of the Wohler curve of duraluminum alloy 2024-T3. An evolutionary algorithm is a subset of evolutionary computation, a generic population-based metaheuristic optimization algorithm. The Metropolis-Hasting algorithm is one of the most widespread Markov chain Monte Carlo methods for posterior distribution estimation. In this contribution, both algorithms have been presented to estimate the probability density functions using Wohler parameters as a case study. Results were shown in terms of distribution shape and parameter correlations and the differences, arising from applied algorithms, have been compared. The information about parameter distributions of Wohler equation is useful to prepare risk analyses based on statistical safe life approach. The safe life approach can be met, for instance, in assessing the reliability of an aircraft.[full text]