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EN
This paper describes a question of evaluation necessity of bridge cranes using the method of limit deformation state and oscillation damping. The solution was performed by means of theoretical analysis and an experimental verification at the selected bridge crane. The final result sounds that in the case of a correct strength computing of given bridge crane, it is not necessary to also check deformation and damping of oscillation as well.
EN
In the paper, we study oscillation of the half-linear second order delay differential equations of the form [formula]. We introduce new monotonic properties of its nonoscillatory solutions and use them for linearization of considered equation which leads to new oscillatory criteria. The presented results essentially improve existing ones.
EN
. This article concerns the oscillatory behavior of solutions to second-order damped nonlinear differential equations with a superlinear neutral term. The results are obtained by a Riccati type transformation as well as by an integral criterion. Examples illustrating the results are provided and some suggestions for further research are indicated.
EN
The working process and regularities of the functioning of vibrating and vibro-impact machines based on hydroimpulse drive with a singlestage valve pulser are analyzed. The essential characteristics determining the conditions for the excitation and existence of periodic oscillations of the valve-pulser shut-off valve are determined. Using the criterion of A. Hurwitz, based on the differential equation of motion, the existence of undamped periodic oscillations of the valve-pulser shut-off valve is analytically justified.
PL
Przeanalizowano działanie i regularność pracy maszyn wibracyjnych oraz maszyn poddawanych wibracjom opartych na napędzie hydro-impulsowym z jednostopniowym zaworem impulsowym. Określono podstawowe cechy wpływające na warunki wzbudzenia oraz występowania drgań okresowych zaworu impulsowego. Przy zastosowaniu kryterium A. Hurwitza, opartego na równaniu różniczkowym ruchu, istnienie nietłumionych drgań okresowych zaworu impulsowego jest analitycznie uzasadnione.
EN
The rational method of implementation of dual-frequency resonant systems with multiple eigenfrequencies of oscillations is considered. The efficiency of implementation of such operation modes is substantiated by the use of a pulsed electromagnetic drive with oscillations frequency of 50 Hz. The analysis of the vibrating system dynamics is carried out on the basis of numerical modelling of the system of nonlinear ordinary differential equations. The influence of inertia of auxiliary oscillating mass on the indexes of acceleration of the working device, namely on its maximum value and on the fundamental harmonics ratio, is investigated. The structure of a partial module, which is a means of modernization of single-frequency resonant systems, is proposed.
PL
Rozważana jest racjonalna metoda implementacji systemów rezonansowych o dwóch częstotliwościach z wieloma częstotliwościami drgań własnych. Efektywność realizacji takich trybów pracy jest uzasadniona przez zastosowanie impulsowego napędu elektromagnetycznego o częstotliwości drgań 50 Hz. Analiza dynamiki układu wibracyjnego przeprowadzana jest na podstawie numerycznego modelowania układu nieliniowych równań różniczkowych zwyczajnych. Zbadano wpływ bezwładności pomocniczej masy oscylacyjnej na wskaźniki przyspieszenia urządzenia roboczego, a mianowicie na jej wartość maksymalną i na współczynnik podstawowej harmonicznej. Zaproponowano strukturę modułu częściowego, który jest środkiem do modernizacji układów rezonansowych o jednej częstotliwości.
EN
The main purpose of this paper is to improve recent oscillation results for the second-order half-linear delay differential equation [formula] under the condition [formula]. Our approach is essentially based on establishing sharper estimates for positive solutions of the studied equation than those used in known works. Two examples illustrating the results are given.
EN
In this paper, sufficient conditions for oscillation of the second order differential equations with several sublinear neutral terms are established. The results obtained generalize and extend those reported in the literature. Several examples are included to illustrate the importance and novelty of the presented results.
EN
The research goal was to develop an improved water purification technology for public reservoirs by adding the vibrocavitation purification before a reagent method with sodium hypochlorite, produced via electrolysis of salt. The main tasks of the research include the determination of vibrocavitation treatment efficiency and the development of a new low-frequency vibration resonance cavitation process for water purification, as well as equipment for this process. The vibroresonance method supporting the intensity of spatial displacements of cavitation exciters was developed on the basis of the theory of cavitation fields in liquids. While using this method, it was possible to establish the boundary conditions for stable support of the cavitation field created by low-frequency vibrations. The developed method is based on the formation of high intensive cavitation fields in liquids by vibratory decks. The advanced technological scheme of water purification for pools and public use reservoirs was proposed, which includes the addition of resonance vibrocavitators to a closed circulation cycle of water purification with the reagent method.
EN
In this paper, we consider systems of impulsive nonlinear neutral delay partial differential equations with distributed deviating arguments and sufficient conditions for the oscillation of the system under the Dirichlet boundary condition. The main results are illustrated by one example.
EN
In this paper, we derive some sufficient conditions for the oscillatory and asymptotic behavior of solutions of the higher order nonlinear neutral delay dynamic equation with positive and negative coefficients. The results of this paper extend and generalize the results of [S. Panigrahi and P. Rami Reddy, Oscillatory and asymptotic behavior of fourth order non-linear neutral delay dynamic equations, Dyn. Contin. Discrete Impuls. Syst. Ser. AMath. Anal. 20 (2013), 143-163] and [S. Panigrahi, J. R. Graef and P. Rami Reddy, Oscillation results for fourth order nonlinear neutral dynamic equations, Commun. Math. Anal. 15 (2013), 11-28]. Examples are included to illustrate the validation of the results.
EN
The purpose of this paper is to give general solutions of linear difference equations which are related to the Euler-Cauchy differential equation [formula] or more general linear differential equations. We also show that the asymptotic behavior of solutions of the linear difference equations are similar to solutions of the linear differential equations.
EN
This paper deals with the oscillation of a certain class of second order difference equations with a sub-linear neutral term. Using some inequalities and Riccati type transformation, four new oscillation criteria are obtained. Examples are included to illustrate the main results.
PL
W dyskusjach nad właściwościami energetycznymi obwodów elektrycznych z uporem powraca pogląd, że straty energii przy jej przesyle ze źródła zasilania do odbiornika powodowane są oscylacjami tej energii. Dużą rolą w utrwalaniu tego poglądu ma norma DIN 40100, która wprowadziła koncepcję rozkładu mocy chwilowej p(t) na moc chwilową wejściową pv(t) (dodatnią) oraz moc chwilową powrotną pr(t) (ujemną). Niniejszy artykuł pokazuje, że nie ma wyraźnego związku między współczynnikiem mocy obwodu oraz stratami energii przy jej przesyle a mocą wejściową pv(t) oraz mocą powrotną pr(t). W artykule pokazano również, że oscylacje energii między źródłem zasilania a odbiornikiem nie mają wpływu na współczynnik mocy odbiornika, oraz wykazano, że nie ma w obwodach elektrycznych żadnego zjawiska fizycznego, które wymagałoby wprowadzenia do jego opisu pojęcia mocy biernej Q, co oznacza, że moc bierna Q nie jest wielkością fizyczną.
EN
In discussions on power properties of electrical circuits recurrent point of view is expressed that the energy loss is caused by the energy oscillation. The spread of this opinion is instigated by Standard DIN 40100, which introduced the concept of the instantaneous power pv(t) decomposition on an input instantaneous power pv(t) (positive) and a returning instantaneous power pr(t) (negative). The paper demonstrates that there is no clear relation between the power factor and the energy loss at its delivery on the input and the returning instantaneous powers pv(t) and pr(t). Moreover, it is shown in the paper that the energy oscillation between the supply source and the load has no effects on the power factor. It was shown as well that there is no physical phenomenon in electrical circuits that requires the concept of the reactive power, which means that the reactive power is not a physical quantity.
14
EN
The springing support in a driver’s seat is a very serious issue, such that manufacturers are increasing their efforts to optimize the dynamic properties of this kind of seat. The main optimization criterion is vibration insulation efficiency with regard to health research and associated health standards and regulations. This article deals with the definition of the optimal driver’s seat properties in relation to two examples of springing systems with different kinds of damping. The first case involves the springing support of a driver’s seat that uses a pneumatic spring and a telescopic hydraulic damper. In the second case, the damping effect is achieved by two pneumatic springs whose forces effect a phase shift due to a throttle valve located in the connecting piping system.
EN
We study the classification schemes for nonoscillatory solutions of a class of nonlinear two dimensional systems of first order delay dynamic equations on time scales. Necessary and sufficient conditions are also given in order to show the existence and nonexis-tence of such solutions and some of our results are new for the discrete case. Examples will be given to illustrate some of our results.
EN
In this paper, we present some oscillation criteria for second order nonlinear delay difference equation with non-positive neutral term of the form ∆(an (∆zn )α )+qn f(xn-σ) )=0, n>no >0, where zn - xn - pn xn-r, and α is a ratio of odd positive integers. Examples are provided to illustrate the results. The results obtained in this paper improve and complement to some of the existing results.
EN
This note is concerned with the oscillation of third order nonlinear delay differential equations of the form (r2(t) (r1(t)y'(t))')' +p(t)y'(t) + q(t)ƒ(y(g(t))) = 0. (*) In the papers [A.Tiryaki, M.F. Aktas, Oscillation criteria of a certain class of third order nonlinear delay differential equations with damping, J. Math. Anal. Appl. 325 (2007), 54-68] and [M.F. Aktas, A. Tiryaki, A. Zafer, Oscillation criteria for third order nonlinear-functional differential equations, Applied Math. Letters 23 (2010), 756-762], the authors established some sufficient conditions which insure that any solution of equation (*) oscillates or converges to zero, provided that the second order equation (r2(t)z'(t))' + (p(t)/r1(t))z(t) =0 (**) is nonoscillatory. Here, we shall improve and unify the results given in the above mentioned papers and present some new sufficient conditions which insure that any solution of equation (*) oscillates if equation (**) is nonoscillatory. We also establish results for the oscillation of equation (*) when equation (**) is oscillatory.
18
Content available Oscillation systems from hyper-deforms elements
EN
In construction of machines more and more often are used materials called hyper-elastic, for example: foam structures, materials based on natural and synthetic rubbers and other materials subjecting large deformations. The porous structures are produced on the basis of different synthetic materials, thermoplastic polymers and thermosetting. Subject of porous materials is studied by many scientists around the world. Porous materials (also called cellular plastics, foam plastics or foamed plastics) include gas phase dispersed in a solid phase of polymeric material. Properties of such systems depends on the properties of the polymer warp and cell structure, comprising the gas phase. Approach previously used to anticipate and interpreting the behaviour of the hyper-deformable structures, which use the theory of hyperelastic materials, does not resolve the issue because it only describes the elastic properties. The article presents an original methodology developed structural identification the viscoelastic properties of hyperdeformable materials, and in particular modern construction materials from the group of plastics and composites of elastomers, foams, etc. The aim of the article was an oscillation analysis in systems from elements of incompressible and the description of phenomena setting in during of work of suchlike systems.
EN
In this paper, the authors investigated oscillatory and asymptotic behavior of solutions of a class of nonlinear higher order neutral differential equations with positive and negative coefficients. The results in this paper generalize the results of Tripathy, Panigrahi and Basu [5]. We establish new conditions which guarantees that every solution either oscillatory or converges to zero. Moreover, using the Banach Fixed Point Theorem sufficient conditions are obtained for the existence of bounded positive solutions. Examples are considered to illustrate the main results.
20
Content available Polymers foam structure numerical identification
EN
Polymers found regard among engineers and researcher their special proprieties. Now, we find using the polymers at present in the most advanced technically the branches of industry. In construction of machines, more and more often are practical used hyperdeform materials. The group of construction materials, called hyperdeformable, includes among others: elastomers, plastics made based on rubber, thermoplastic structures, such as polycarbonate, gels and sols, composites and foams: open and closed pores. Porous structures are produced on the basis of different materials, synthetic thermoplastic polymers and thermosetting. The problem of porous materials is taken in many research centres in the world. Porous materials (also called cellular plastics, foam plastics or foamed plastics) include gas phase dispersed in a solid phase of polymeric material. Properties of such systems depend on the properties of the polymer warp and cell structure comprising the gas phase. Approach previously used to anticipate and interpret the behaviour of the hyperdeformable structures, using the theory of hyperelastic materials, does not resolve the issue because it only describes the elastic properties. The article presents an original methodology developed structural identification the viscoelastic properties of hyperdeformable materials, and in particular modern construction materials from the group of plastics and composites of elastomers, foams, etc
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