This paper describes a digital servo-system with a driving electromotor which substitutes the existing electrohydraulical servo-system on an IR localizer control device. Thus realized, a digital electrical servo-system provides requested accuracy of positioning and tracking with minimal velocities.
This paper presents the results of research into the comparison of power obtained with one and two contra-rotating hydro turbines in a Venturi tube for the given number of revolutions per minute and the given water velocity at the tube entry. The results were obtained with commercial software for numerical fluid dynamics. The numerical simulations for two turbines rotating in opposite directions with equal angular velocities showed that a considerable power drop occurred in the front turbine, whereas the total power is somewhat larger than that for one turbine.
Changes in vehicle performances represent important changes of the overall condition of a vehicle and are analyzed regarding its life, ie. its mileage. Since real operational loads are generally considered to be mechanical, temperature-based and structural, the analysis of operational loads of motor vehicles and their elements focuses on the causes of condition changes. The initial criterion for estimating the exploitation reliability and readiness factors of motor vehicles is the frequency of 'in failure' condition occurrence. All other criteria result from the mathematical transformation of this criterion. The obtained data and the PROEFI software package have been used for determining the parameters of three observed distributions: normal, exponential and Veibull. An optimal distribution has been chosen using the Kolmogorov-Smirnof test for a significance level of 0.20.
This paper analyses the criticality of a technical system using the criticality analysis of system parts from the point of view of possible failure effects. Failure analyses, performed throughout a technical system lifecycle, are generally conducted as to determine and isolate failure causes as well as to define prevention measures and subsequent interventions. The term failure analysis involves a procedure for determining some of the following: 1) failures due to degradation of lubricant; 2) failures due to incorrect lubrication; 3) failures due to poor quality of lubricant; 4) mechanism of failure development; 5) failures due to construction error; 6) causes, types and effects of failures. One of the optimal methods of failure analysis is the FTA-Fault Tree Analysis.
A complex continual system design model based on the reliability theory is presented in the paper. If a goal function interval is defined in advance, and can be accurately determined on the basis of experience with similar systems and operation modes, then overall reliability allocation can result in obtaining demanded reliability intervals for each subsystem, each assembly and each mechanical element. In this way the goal function level is brought into direct relation with the reliability interval level of each constituent element of the system.
The forces and moments affecting an underwater projectile under conditions of static and dynamic stability are presented and the equations of movement are derived. The models for calculating the forces and moments expressed in the body - fixed coordinate system of the underwater projectile are given as well.
The new compound CL-20, a cyclic nitramine with the highest crystal density (over 2.0 g/cm3), is the most powerful non-nuclear explosive. The three-step synthesis of hexanitrohexaazaisowurtzitane (HNIW or CL-20) has been described. The CL-20 has the highest density and the highest detonation velocity among existing explosives as well as the highest energy among existing energetic ingredients for explosives, gun propellants and rocket propellants. Same explosive formulations based on the CL-20, energetic polymers, aluminium and ammoniumperchlorate are presented. Their densities and detonation velocities are also presented.
In order to reduce aircraft maintenance costs, particularly costs for repairing aircraft of older generations, it is necessary to adopt a relevant strategy for dealing with corrosion - application of corrosion preventive compounds (CPCs). The experiences of the Australian Air Force maintains service concerning CPCs are given in the paper. Application of corrosion prevention compounds could postpone repair till predicted time for maintenance.
Simulation models can be widely applied in training individuals, units and commanding units of the Serbian Army during the process of military education and training. The simulation model offered in the paper can be applied during marching of military units in order to solve tactical situations and ethical challenges. It can be also used for military education and training of the officers of the Serbian Army.
An approach to evaluation and analysis of military motorcades has been given, regarding the application in practice in particular. The analysis focuses on the criteria of combat readiness, which present the efficiency of motorcade mobility. The objective of the paper is to improve the control of motorcade mobility through a real-time mobility efficiency evaluation.
The definition, advantages, conditions for implementation and results of the research of necessity of implementation are analyzed as well as the basic characteristics of the organization of distance education systems. The example of an implementation in the Belgrade Academy of Computer Sciences is given as well.
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