Bożena Babiarz

RELIABILITY ASSESSMENT OF HEAT SUPPLY SYSTEMS IN THEIR OPERATIONAL PROCESS

 

This paper presents an analysis of  the operational process of heat supply system, taking into consideration its reliability. The specific character of the operation of heat-supply systems has been considered in this work. In the process of  exploitation of heat-supply systems five operational states have been distinguished, using as a criterion the level of indoor temperature decrease in residential rooms. The method of modelling the reliability of heat-supply systems is worked out. The methodology of determining the overall index of heat-supply system reliability has been presented. The measure of heat-supply system reliability has been taken to be as the scale/quantity of inadequate supply of heat power at a given state. Calculations have been carried out regarding the changeability of exterior conditions for one of the groups of customers – residential users. On the basis of the operational data for the heat supply system with two heat sources,  shortfalls of heat power and the probability of their occurrence have been calculated as an application of this methodology.

 

 

R. V. Kakubava

Multi-line Markov  closed queuing system for two maintenance operations

 

In the given paper multi-component standby system with renewable elements is considered. For it multi-line closed Markov queuing model for two maintenance operations – replacements and renewals, is constructed and investigated.  In this model the numbers of main elements as well as standby ones, also the numbers of replacement units as wall as renewal ones are arbitrary.  An economic criterion for dependability planning (structural control) of considered system is introduced, the optimization problem is stated and partially investigated.

 

 

R. Lisi, M. F. Milazzo, G. Maschio

RISK ASSESSMENT OF EXPLOSIVE ATMOSPHERES IN WORKPLACES  

 

The application of the Directive 99/92/EC deals with the safety and health protection of workers potentially exposed to explosive atmospheres and requires the assessment of explosion risks. These can arise by the release of inflammable substances typical of industries classified as major hazards, but they often may be generated in other industries where inflammable materials are handled. Risk assessment of explosive atmospheres is required in both cases, for this purpose, in this article a quantitative approach has been proposed. The paper describes the main aspects of the methodology, based on a probabilistic risk assessment, and finally its application to a case-study.

 

 

R. Dubčáková, P. Praks

Statistical modelling of indoor radon concentration using meteorological parameters 

 

The radon volume activity in buildings is generally time variable. Its variability is caused by many natural and man-made factors. An example of these factors includes meteorological parameters, soil properties, characteristics of the building construction, properties of water used in the building and also the behavior of inhabitants. These factors can influence each other and also they are related with the exposition of inhabitants.

This article reports a continual indoor radon monitoring and a statistical evaluation of a dataset obtained by the 18 days-long measuring in a house located in the Czech Republic.

The contributions of carefully selected meteorological parameters and human influences were also observed. Results of the observation were divided into two parts (inhabited, uninhabited) and analyzed in relation with the indoor radon concentration. The multiplied linear regression was applied to model obtained datasets.

Results of time series analyses of the continual indoor radon concentration and the meteorological monitoring are presented and discussed as well.

 

 

G.Tsitsiashvili, A. Losev

CALCULATION OF CONNECTIVITY PROBABILITY IN RECURSIVELY DEFINED RANDOM NETWORKS

 

In this paper a problem of a construction of new and practically interesting classes of recursively defined networks, including internet type networks, with sufficiently fast algorithms of calculation of connectivity probability is considered. For this aim recursive and asymptotic formulas of connectivity probability calculation are constructed. Asymptotic formulas are based on assumptions that all network arcs are low reliable or there are high reliable and low reliable arcs in considered network. For example in radial-circle scheme radial arcs may be high reliable and circle arcs – low reliable.

 

 

Yakov Genis

RELIABILITY ASSESSMENT OF SYSTEMS WITH PERIODIC MAINTENANCE UNDER RARE FAILURES OF ITS ELEMENTS

 

There is investigated а model of a system with the highly reliable elements, where the periods of functioning are changed by the periods of maintenance. The system must be operational only in the periods of functioning although the restoration in these periods is not provided. The system is completely restored in the nearest period of maintenance. Since the elements of system are highly reliable, the reserve of system is rarely exhausted during each period of functioning. Therefore it is possible to use the results, obtained for the systems with fast restoration, for the reliability assessment of system, which is not restorable in the periods of the functioning. The estimations of indices of failure-free performance and maintainability of such systems are obtained.

 

 

M. Zajac, D. Valis

FUNDAMENTAL RISK ASSESSMENT IN EXAMPLE OF TRANSSHIPMENT SYSTEM

 

The paper represents discussion about risk assessment for transhipment system in reduces data condition. As a particular example transhipment system is presented. Article can be treated as first estimation. Future work and objectives are characterized in the end.

 

 

G.Sh. Tsitsiashvili

ASYMPTOTIC ANALYSIS OF LATTICE RELIABILITY

 

Asymptotic formulas for connection probabilities in a rectangular lattice with identical and independent arcs are obtained.. For a small number of columns these probabilities may be calculated by the transfer matrices method. But if the number of columns increases then a calculation complexity increases significantly. A suggested asymptotic method allows to make calculations using a sufficiently simple geometric approach in a general case.

 

 

Al. Isaic-Maniu, I. M. Dragan

THE RISK OF OPERATIONAL INCIDENTS IN BANKING INSTITUTIONS

 

Banking-financial institutions are organizations which might be included in the category of complex systems. Consequently, they can be applied after adaptation and particularization, in the general description and assessment methods of the technical or organizational systems. The banking-financial system faces constrains regarding the functioning continuity. Interruptions in continuity as well as operational incidents represent risks which can lead to the interruption of financial flows generation and obviously of profit. Banking incidents include from false banknote, cloned cards, informatics attacks, false identity cards to ATM attacks. The functioning of banking institutions in an incident-free environment generates concern from both risk assessment and forecasting points of view.