THE RISK ANALYSIS OF SEISMIC ACTIVITY INCIDENCE IN ROMANIA

In Romania there is one of most powerful seismic activity region from Europe, known as Vrancea. In the past 300 years, a single major seismic event occurred with an epicenter outside this area (1916). This paper starts from going over all major seismic events, with a magnitude of over 6 degrees on Richter’s scale, which were documented. Was tested the most plausible statistic behavioral model and was determined the probabilities for future large scale earthquakes, by different time horizons.

ESTIMATION LIKELIHOOD OF SPEED OF CHANGE OF DIAGNOSTIC PARAMETERS OF TRANSFORMERS

Methods of classification retrospective data on independent groups of homogeneous data and estimations of reliability the assumption of constant speed of deterioration during normative service life are developed.

THE CONCEPTUAL FRAMEWORK FOR CONSTRUCTION PROJECT RISK ASSESSMENT

The environment in which the project schedule will be executed is far from being static. Projects are subject to various uncertainties that have negative effect on activity durations. This is most apparent in the case of construction projects. The frequency and impact of risks depend on project-specific, contractor-specific and location-specific conditions. Identifying critical sources of risk is crucial to minimize disturbance in project development and assure success. The paper presents risk analysis and assessment framework. For the risk evaluation, the AHP was adopted in the paper. The proposed risk model is based on evaluating and weighting the particular project’s characteristics and expected conditions. The method to assist planners in determining activity duration distribution parameters according to risk level is presented. This approach, combined with simulation technique, is argued to improve project planning and evaluation of risk mitigation alternatives.

DISTRIBUTIONS OF NUMBERS OF CONNECTIVITY COMPONENTS

IN RECURSIVELY DEFINED GRAPHS WITH UNRELIABLE ARCS

In this paper a problem of accuracy and approximate calculations of connectivity characteristics in recursively defined random graphs is considered. This problem is solved using low and upper bounds for numbers of connectivity components in graphs and limit theorems of probability theory: law of large numbers and central limit theorem.

О.А. Tkachev

DETERMINATION OF MEAN TIME TO FAILURE OF A NETWORK CONSISTING

OF IDENTICAL NON-REPAIRABLE ELEMENTS

It is suggested the analytical model permitting to get expression for determination of mean time to failure of a network consisting of identical non-repairable elements that fail independently of one another and have exponential distribution of time to failure. To determine values of obtained expressions it is necessary to determine probability of network failure in failure of defined quantity of its elements. This factor may be determined exactly with analysis of all possible combinations of failed elements or approximately with Monte-Carlo method.

CFBLTQ: A Closed Feed Back Loop Type Queuing System; Modeling and Analysis

This paper presents an innovative approach to solve probability distributions of a closed feed back loop type queuing system with general service time distribution. This model is applied to a multi-processors system where some of its nodes are performed a repair procedure during a node’s malfunction condition. Our model is appropriate for a multiprocessor system that employs a common bus or for a multi-node system in computer network. A meticulous analysis of the system’s model has been conducted and numerical results have been obtained to scrutinize the proposed model.

COOPERATIVE EFFECTS IN COMPLETE GRAPH WITH LOW RELIABLE ARCS 

An analysis of the limit Pn = A of connectivity probability (CP)  of complete graph with  nodes and independent arcs which have working probability n^-a is made. It is proved that for 0<a<1 we have the equality A=1 and for 1<a the equality A=0.

DUBBED THE REPLACEMENT SYSTEM WITH CONTROL

An expression for the function of readiness duplicated system in the Laplace transform and its significance is the steady state for arbitrary distributions of time to failure and recovery of constituent elements. In these expressions have introduced the parameter reliability monitoring the state of the elements after their refusal. The value of this option allows you to take into account the duration of the recovery elements after their refusal. Because of this, a generalization of the result  obtained  B.V. Gnedenko, ready for the duplicated system with control of the state elements.

AVAILABILITY AND RELIABILITY MEASURES FOR MULTISTATE SYSTEM BY USING MARKOV REWARD MODEL

This paper describes some  models and measures of reliability for multistate systems. The expected cumulative reward for the continuous time Markov  reward models are used for deriving the structure function for a multistate system where the system and its components can have different performance levels ranging from perfect functioning to complete failure. The suggested approach presents with respect to the non-homogeneous and homogeneous Markov reward model of two stochastic process for computation of these availability and reliability measures. A particular case for three  levels is analyzed numerically by assuming Weibull and exponential distributions for failure and repair times.

MATHEMATICAL MODELS OF DECISION SUPPORT SYSTEM FOR THE HEAD

OF THE FIREFIGHTING DEPARTMENT ON RAILWAYS

Using such a DSS can significantly reduce the time to evaluate the situation and making decisions on the organization of firefighting units to eliminate fire techniques to produce efficient thinking at training officers fire departments railroads, and develop knowledge base DSS. Future directions of the development of DSS are its use in research networks, comprising some QS with different characteristics, and models that take into account the loss of combat vehicles and servants, and the sequence of different disciplines to focus on capabilities rolling stock, affected by fire.

ASYMPTOTIC OPTIMUM QUANTIZATION OF THE CASUAL SIGNAL WITH BLANKS BETWEEN QUANTA

In article generalization of a problem of optimum quantization of a casual signal with blanks between quanta is presented. Unlike known works the law of distribution of a casual signal with quanta is received. Instead of the integer decision of a problem the approached asymptotic decision is offered at a great number of quanta and the estimation of its accuracy is given. Besides, the decision of the given problem is received at fuzzy values of parameters of a blank and a population mean of an initial random variable with the normal law of distribution.

A GENERAL ANALYTICAL SOLUTION FOR THE OCCURRENCE PROBABILITY

OF A SEQUENCE OF ORDERED EVENTS FOLLOWING A POISON STOCHASTIC PROCESS

The author presents a general analytical solution determining “the Occurrence probability of a sequence of events each following Poison Stochastic Process”. Generally, this probability is described under the form of an integral equation of order “n”. Where “n” is number of the elementary events in the examined sequence. As far as the author can tell, the solution is original. It will be of a great interest to a wide range of system reliability problems such as: sequential calculations, dominos effects, dynamics fault trees, Markov systems, priority AND gates, events trees, stochastic optimisation, acceleration techniques for Monte-Carlo simulation.