NATURAL DISASTERS AND STRUCTURAL SURVIVABILITY

The term “disaster” is known to denote any environmental changes putting human lives under treat or materially deteriorating living conditions. A considerable part of disasters comprises natural calamities. These disasters can originate inside Earth (earthquakes, volcanic processes), near or on its surface (disturbance of slope stability, karsts, considerable changes in soil conditions and ground’s settlements). The causes of disasters can as well be associated with a water, either at a liquid (flood, tsunami) or at a frozen state (complex or glacier avalanches), and, finally with atmospheric conditions. In many cases successions of interdependent disasters are possible, including these occurring in different media (earthquake-tsunami, earthquake-landslide, and lands-flood etc.).       

DYNAMIC MODEL OF AIR APPARATUS PARK

The article is devoted to construction and research of dynamic stochastic model of park of aircrafts. A stochastic is enclosed in all of natural characteristic exploitations of this set of apparatuses: times of flight and landing, possibility of receipt of damage on flight, including the past recovery air apparatus; times of repair. The estimations of total possible flights are got for the any fixed interval of time.

An asymptotic analysis of a reliability of internet type networks

In this paper a problem of a construction of accuracy and asymptotic formulas for a reliability of internet type networks is solved. Analogously to [1] such network is defined as a tree where each node is connected directly with a circle scheme on a lower level with n>0 nodes. A construction of accuracy and asymptotic formulas for probabilities of an existence of working ways between each pair of nodes of the internet type network is based on a recursive definition of these networks and on asymptotic formulas for a reliability of a random port. This asymptotic formula represents the port reliability as a sum of probabilities of a work for all ways between initial and final nodes of this port. An estimate of a relative error and a complexity of these asymptotic calculations for a radial-circle scheme are shown.

A study of asymptotic availability modeling for a Failure and a repair rates following a Weibull distribution

The overall objective of the maintenance process is to increase the profitability of the operation and optimize the availability. However, the availability of a system is described according to lifetime and downtime. It is often assumed that these durations follow the exponential distribution. The work presented in this paper deals with the problem of availability modeling when the failure and repair rates are variable. The lifetime and downtime were both governed by models of Weibull (the exponential model is a particular case). The differential equation of the availability was formulated and solved to determine the availability function. An analytical model of the asymptotic availability was established as a theorem and proved. As results deduced from this study, a new approach of modeling of the asymptotic availability was presented. The developed model allowed an easy evaluation of the asymptotic availability. The existence of three states of availability for a system has been confirmed by this evaluation. Finally, these states can be estimated by comparing the shape parameters of the Weibull model for the failure and repair rates.

Object Oriented Commonalities in Universal Generating Function for Reliability and in C++

The main idea of Universal Generating Function is exposed in reliability applications. Some commonalities in this approach and the C++ language are discussed.

SOME INFERENCES ON THE RATIO AVERAGE LIFETIME/TESTING TIME IN ACCEPTANCE SAMPLING PLANS FOR RELIABILITY INSPECTION

In this paper we construct effective single sampling plans for reliability inspection, when the distribution of failure times of underlying objects obey a Weibull law. To this purpose we use the index average lifetime (E (T)/testing time (T) for two values of E(T) - acceptable and non acceptable ones - and known shape parameter (K) of the Weibull cdf. We derive also a relationship between this index and reliability function R(t) of the assumed statistical law. A numerical illustrations is provided in the case of Rayleigh cdf - that is for a Weibull shape k = 2.

An ACCURACY OF ASYMPTOTIC FORMULAS IN CALCULATIONS OF A RANDOM NETWORK RELIABILITY

In this paper a problem of asymptotic and numerical estimates of relative errors for different asymptotic formulas in the reliability theory are considered. These asymptotic formulas for random networks are similar to calculations of Feynman integrals. A special interest has analytic and numerical comparison of asymptotic formulas for the most spread Weibull and Gompertz distributions in life time models. In the last case it is shown that an accuracy of asymptotic formulas is much higher.