Models for reliability and availability of one telecommunication system consisting of four telecommunication stations connected in ring by duplex lines are presented. The models are developed based on the grouping of possible states of the analyzed system using the Markov models for transition probabilities between particular states of the system.
Increased demands for low cost of hardware, small size and low power consumption of equipment in cellular mobile communications have driven designers to resurrect the direct conversion receiver. Long abandoned in favor of the mature superheterodine receiver, the direct conversion receiver has emerged over the last decade. Direct conversion reception has several qualities which makes it very suitable for integration as well as multi-band multi-standard operation. This paper describes the characteristics of the direct conversion receiver as well as the inherent imperfections of the superheterodine receiver from the aspect of integration.
Sensitivity of several types of explosives to heat impulse has been examined by measuring the delay time as a function of temperature. The values of activation energy an the pre-exponential factors in the Semionov equation have been determined on the basis of the experimental results. The effects of the examined sample mass, granulation and crystal size on the sensitivity to heat impulse have been also investigated. These parameters are shown to have a significant effect on the sensitivity of explosives. Therefore, it is necessary to standardize the procedure of test sample preparation in order to get comparable results.
These investigations included experimental and theoretical study of acetone vapours influence on the propellant mechanical properties. The tests were carried out on two defined propellants. Herein shown are the results of the mechanical tests of both non-treated and treated propellants as well as an attempt to explain the observed phenomenon.
A method for calculation the loss of muzzle velocity is presented. The model is based on an erosion of the origin of rifling (elongation of propellant chamber and the known models of interior ballistics of Opokov and Drozdov. First, a computer version of these models is modified. The calculations are made for howitzers using a two-part cartridge. The numerical model has been applied to repair documents and ballistic tables.
Steering wheels vibrations around king pins, known as "shimmy", produce a harmful influence on motor vehicle steering parameters. They appear to be a result of the influence of road irregularities, clearance in the steering system, wheels unbalance, wheels and tires nonuniformity, etc. In a vehicle steering system design process, an optimal choice of vehicle parameters is of major importance for minimum values of wheels shimmy. This paper presents an attempt to model a truck steering system with power and mechanical steering so as to study steering wheels shimmy.
This study deals with several methods of rejecting the extreme values of a particular random variable during an experiment or testing. The described methods are illustrated by a number of examples obtained by a specially developed computer program.
The study analyzes the forces affecting a parachuting system at the moment of its opening at different heights and flight velocities. The strain peak occurs at the moment when the filling of the parachute cupola with air is to be finished. Therefore, a special attention during calculations is paid to the cupola and the elements connecting it with the rest of the parachuting system. The study presents the calculation methodology for a parachuting system without a brake-parachute and for systems with one or more brake-parachutes.
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