Ribiniai pavojaus skirstiniai tinklinėse sistemose

The subject of this work is the analysis of hazard distribution in the network systems. In the age when transport flows in the railway and road systems, information flows in the internet channels, etc. intensify, hazard distribution in the network systems becomes a more relevant and important issue.  In the paper various theoretical hazard type distributions in the network systems are analysed. Mathematical model of hazard distribution and accumulation in the nodes of the network was created.Santraukos nėra

Smart optical rotation speed transducer

This paper presents a transducer that was designed for rotation speed measurement of water meter impeller during verification procedure of counting mechanisms. In many cases, particularly when wet type water meters are verified, the impeller is obstructed by dregs, rust, etc. and therefore is hardly visible. When using filtration both in spatial and frequency domains, steady and reliable measurements are obtained. Both theoretical and experimental results are presented in this paper. In this research work transfer function of smart rotational speed measurement transducer is shown and various modes of input parameters are modeled. The reliability of the transducer output signal and its response to optical disturbances are modeled and real signals from transducer prototype are give

A method for air flow measurement using high frequency vibrations

Air flow measurements are very important in technological processes. A new air flow measurement method is proposed. The method is based on the interaction of air flow with the end of a fiber waveguide located in the flow. As the result of this interaction, random high frequency vibrations are generated in the fiber waveguide. The stochastic transducers are created for the realization of this method. The stochastic transducer consists of the fiber waveguide, the piezoceramic element and the preamplifie

Estimation of surface roughness using high frequency vibrations

Surface roughness is an important parameter for evaluating the quality of material surfaces. It affects the tribological and optical properties of the materials. The paper proposes a new method for estimation of surface roughness, which is based on measurement of high frequency vibrations that are generated when air flow interacts with the surface of a solid body. It was determined that intensity of high frequency vibrations depends on surface roughness. Sandpapers with different magnitudes of surface roughness were used for the experimental stud

Kvazigardelinių atsitiktinių dydžių serijų sumų skirstinių asimptotinė analizė

We consider the formal asymptotic expansion of probability distribution of the sums of independent random variables. The approximation was made by using infinitely divisible probability distributions.  Diskretų k-matį atsitiktinį vektorių ξ = (ξ1, ξ2, . . . , ξk) vadinsime kvazigardeliniu, jeigu jo koordinatės ξ1, . . . , ξk yra kvazigardeliniai atsitiktiniai dydžiai ξi, t. y. ξi įgyja reikšmes (βi, νi) = β1iν1i + · · · + βkiiνkii, νji = 0,±1,±2, . . . , βji > 0 ir vektoriausβi = (β1i, . . . , βkii) koordinatės yra tiesiškai nesurištos racionalių skaičių kūne. Yra įrodyta, kad vietoje kvazigardelinio vektoriaus ξ1, galima nagrinėti gardelinį atsitiktinį vektorių θ= (θ1, . . . , θm) erdvėje Rm, kur m = k1 + k2 + · · · + kk. Toliau mes kalbėsime apie kvazigardelinius atsitiktinius vektorius, kurių klasei priklauso ir gardeliniai atsitiktiniai vektoriai (žiūr. [1]). &nbsp

The research system for vibration analysis in domestic installation pipes

A measurement and data processing system was developed for investigation of processes that influence sound propagation in pipes, which are commonly used in residence building industry. An impact-type excitation was mainly used for a controlled wide-band frequency mechanical vibrations excitation. Pipe surface vibrations were measured by means of accelerometers and microphones. Scanning device was used for positioning transducers over a tested pipe. The wave propagation and vibration analysis in pipeline segments of several types of pipes (plastic and metallic) was carried out. Because of various pipes working conditions, empty and filled pipes were tested as well. The experimental data indicates that both in metal and plastic pipes vibrations up to several kilohertz may propagate with low attenuation facto

Asimptotiniai skleidiniai normalinės aproksimacijos atveju

We consider the asymptotic behavior of the convolution P*n(A\sqrt{n}) of a k-dimensional probability distribution P(A) as n \to  \infty for A from the \sigma-algebra M of Borel subsets of Euclidian space Rk or from its subclasses.  Nagrinėjame k-mačio tikimybinio skirstinio P(A) sąsūkos P*n(A\sqrt{n}) asimptotinį elgesį, kai n \to  \infty ir A priklauso Euklido erdvės Rk poaibių  \sigma-algebrai M arba jos siauresniems poaibiams

Method for the measurement of the stratification of concentrated suspensions

A simple, fast and precise method for evaluation of precipitate formation kinetics and its amount in concentrated suspensions that are stored in closed containers after production has been developed. The method is based on the measurement of the mechanical pendulum period change over time. The principles of the development of this method are presented: theoretical fundamentals of measurement using this method have been analyzed; it was proved that the swing period and amplitude change rate are informative pendulum parameters; a pendulum variant was determined experimentally that allows to avoid the error introduced by the movement of suspension inside the container and reduces the requirements for the container mass uniformity; it was determined that in order to reduce the error it is appropriate to start the period duration measurement from the 5 period from the beginning of the swing; the dependence of the swing period on the mass of the precipitate was evaluated experimentall

Acoustic wave synthesis in dispersive media

There are many applications in non destructive testing, calibration of acoustic emission transducers, medicine, mechatronics etc., where waveguides with dispersive wave propagation properties are used. Generation of arbitrary displacements in this kind of waveguides is important and difficult. Possible solution to this problem is application of wave synthesis technique. This research shows that suggested technique allows to obtain arbitrary displacements of known form and duration in plates and stripes. Measurements of displacements were done in steel plate and stripe. Scanning of surfaces proved that it is possible to obtain arbitrary displacements in selected areas of the waveguides

Dynamic compensation of rotating blades imbalance

The purpose of this paper is to research an effect of factors that are creating an imbalance of fan rotating blades and to estimate the possibility of compensation for this parasitic effect. For this purpose the measurement system including hardware and software was developed. Measurements of vibrations and dynamic pressure of rotating two-blades fan, blades profile and lift force parameters at various rotation speed were performed. This paper presents compensation possibilities when mechanical and aerodynamic imbalance occurs