Wyniki wyszukiwania - Biblioteka Nauki

1

Magnetic problems as a benchmark for genetic algorithm`s operators

100%

Gwizdałła T.

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2007

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tom z. 160

115-123

EN

In the paper it is presented the analysis of results and dynamics of evolutionary optimization applied to the well known magnetic Ising model. The data were obtained using different models and genetic operators and allow to formulate some more general conclusion concerning the possibilities of solving real NP-hard problems propted by physics.

2

Numerical analysis of a front support landing gear dynamics as the example of chosen MCAD and CAE systems integration in the case of the military transport aircraft design

80%

Niezgoda T. , Małachowski J. , Budzyński A.

|

2006

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tom Vol. 13, No. 2

341-350

EN

The paper presents the example of MCAD and CAE environments integration in the case of the military transport aircraft front gear dynamic analysis. The gear exact MCAD model is presented with the manner of its simplification. Simplified model is physically similar to the exact one: results of numerical static analysis are the same in both cases. To ensure the credibility of the dynamic analysis, a model kinematics one took place - the gear configuration changed (“airborne” - “airfield”) with the measurements of chosen values. Simulation was verified with the real experiment results. The gear drop test has been simulated with the measurement of the fall-down velocity and absorber displacement. By the progressive results comparison of digital and real experiments, the stiffness-dumping values were attached to the spring/dumper Lagrange elements that simulate the behavior of the absorber gas-oil mixture. The gear model shock sensitivity has been analysed by simulations of landing process with gear invasion through chosen airfield obstructions. Aircraft fall-down velocity can be safely increased by 30% and it can operate on slightly damaged concrete airfields and rough surfaces. The shimmy vibration model sensitivity took place. It is proved that such a phenomenon can’t appear during the correct aircraft maintenance.

3

Dynamic behavior of bone-implant substitute systems. Numerical and experimental study

80%

Nowak B. , Kaczmarek M. , Kubik J.

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2009

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tom Vol. 47 nr 3

617-628

EN

In this paper, a study of substitute systems of an implanted bone was presented from the point of view of elaboration of a method for dia- gnosing the state of integrity of the bone-implant attachment based on vibrational techniques. Dynamic parameters of the systems were esha- blished as sets of eigenfrequencies/resonance frequencies using numerical procedures and experimental modal analysis. The shifts of values of the parameters were discussed in relation to the loosening of contact between the bone and implant. The numerical and experimental results were compared and their consequences for application of vibrational techniques to real anatomical systems discussed.

PL

W pracy przedstawiono badania układów zastępczych zaimplantowanej kości udowej, które dotyczą rozwijania nowych metod diagnostycznych opartych na technikach drganiowych. Wyznaczono zbiory parametrów dynamicznych układów w postaci częstotliwości własnych i rezonansowych dla badań numerycznych i eksperymentalnych. Zmiany parametrów dynamicznych przedyskutowane zostały w kontekście odspajania implantu od kości. Porównano także wyniki badań numerycznych i eksperymentalnych oraz przeanalizowano możliwości zastosowania tej metody w układach anatomicznych.

4

The dynamics deformations of the Bear Cave rock mass

80%

Mąkolski K. , Kaczałek M.

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2000

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tom z. 7/53

67-76

EN

The paper presents the geodetic measurement results of vertical displacements of benchmarks inside and outside the Bear Cave in the period 1984 - 1999. The results of benchmark displacements and the comparative analysis results of measured height differences between benchmarks in relation to their position at the detected and expected tectonic faults are presented. The geodetic results have been analysed in relation to stability of rock masses after finishing of excavation in neighbouring stone mine.

5

Mathematical modeling of body braces in a railway vehicle

80%

Pshinko A. M. , Blokhin Y. P. , Myamlin S. V.

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2002

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tom nr 1

269-276

EN

As a rule, a railway vehicle is considered as a system consisting of solid bodies when spatial oscillations are mathematically modelled. Such bodies in a freight four-axle car with three-piece bogies are: a car body, bolsters, side frames, wheelsets. When describing a mathematical model, certain assumptions are being usually made as to absence of linear or angular relative movements of bodies in a system. The suggested model takes into account all types of relative movements in all directions (3 linear and 3 angular ones). The types of braces are assumed to be as follows: the elastic brace, the dissipative one, dry friction ones, or their combinations. If it is necessary to restrict body movements in whatever direction, the brace parameter is given as equal to the structure's rigid characteristic. The 'wheel-rail' contact is considered as a specific kind of brace. Thus, the unification of description of braces among system parts can be obtained - in this way simplifying modelling as a whole. Appropriate computer software has been developed. The software debugging was done by means of setting single vertical and horizontal rail irregularities. It made possible correcting the types and parameters for chosen braces among bodies of the system. During the calculation process, stochastic vertical and horizontal irregularities on rails were set. The results of theoretical studies and experiments have been compared. The adequate correlation of all dynamic features compared has been obtained.

PL

Opracowano matematyczny model pojazdu szynowego uwzględniający wszystkie rodzaje ruchu we wszystkich kierunkach (trzy - liniowe, trzy - kątowe). Opracowano odpowiednie oprogramowanie komputerowe. Zostało ono zweryfikowane i sprawdzone przez zadawanie pojedynczych poziomych i pionowych nieregularności szyny. Pozwoliło to na korektę typów i parametrów połączeń głównych elementów systemu. Podczas procesu obliczeniowego były uwzględnione stochastyczne wartości poziomych i pionowych nieregularności szyn. Porównano rezultaty badań teoretycznych i eksperymentalnych oraz przedstawiono korelacje pomiędzy nimi.

6

Aktywne uszczelnianie z pływającym pierścieniem

80%

Kundera C.

|

1999

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tom nr 4

501-511

PL

W pracy przedstawiono koncepcję aktywnego uszczelnienia z pływającym pierścieniem. Zaproponowano układy sterowania położeniem pierścienia tak, aby w czasie pracy utrzymywana była założona szczelina. Zastosowano dwie metody sterowania, z regulatorem liniowym oraz z regulatorem adaptacyjnym. Sformułowano model matematyczny aktywnego uszczelnienia. Do obliczeń sił hydrodynamicznych wykorzystano liniowe zależności wyprowadzone przez Marcinkowskiego (1992). Przedstawiono wyniki przekładowych obliczeń cyfrowych dla uszczelnienia bez i z układem sterowania.

EN

In the paper a conception of active annular seal with floating ring is shown. The control method is based on adjusting the motion of the floating ring in order to maintain a desired seal gap. Two alternative designs of system control, first system based on linear controller second on the adaptive controller, were presented. A mathematical model of active annular seal is formulated. In numerical solution using linearized expressions describing on the hydrodynamic forces were proposed by Marcinkowski (1992). Results of numerical calculation for seal without and with system control are shown.

7

Prescribing growth type of complete Riemannian manifolds of bounded geometry

80%

Badura M.

Annales Polonici Mathematici

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2000

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tom 75

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nr 2

167-175

EN

We describe certain properties of growth types of nondecreasing sequences. We build a complete, connected Riemannian surface of bounded geometry and of a given growth type provided that the type satisfies some natural conditions.

8

One dimensional kinetic model of CMM passive scanning probes

80%

Krajewski G. , Woźniak A.

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2009

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tom Vol. 3, No. 4

172-174

EN

Scanning probes, also known as measuring probes, are one of the most used solution for coordinate measuring machines (CMM), because of ability to collect large amount of measuring points as well as fast measurements. Fast measurement and accuracy of measuring system have recently determined two critical parameters which decide about effectiveness of the machine. Dynamic is the most significant factor limiting accuracy of measurement. Majority of research into scanning CMM does not separate the performance of the probing system from the other error sources of the machines, so a real error influenced by the probing system is not deeply determined. This paper presents the scanning probe model regardless the machine links. Determined model makes possible to better understand the probing process with higher speeds and optimize the measuring process. Finally (future work), optimization algorithms will be proposed and applied to the probing system and the result will be improved accuracy.

9

Anisotropic damage evolution in shock wave-loaded viscoplastic plates

80%

Stoffel M.

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2008

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tom Vol. 60, nr 4

285-301

EN

In the design of structural elements, which are used for protection against explosions, the damage evolution until failure has to be predicted in numerical simulations. However, in the literature a wide variety of damage models is available based on different approaches, e.g. phenomenological and micromechanical theories. Furthermore, the consequences of connections between new damage models and the constitutive equations accounting for elastic-viscoplasticity are unclear. The same problem occurs if structural theories, involving hypotheses, are combined with damage laws. In order to verify the calculated results, experiments with structures subjected to pressure waves are necessary. For this reason, an experimental validation method by means of shock tubes is used in the present study to verify the isotropic and anisotropic damage models. The measured deformations and experimentally observed failure modes can then be compared to the simulated results.

10

Dynamika jako element muzyki w poezji XX wieku (na przykładzie wybranych wierszy Stanisława Barańczaka)

80%

Cudzich-Budniak K.

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nr 1

246-256

XX

My text is treating about the dynamics as an element of music, which is possible to be found also in the poetic texts. It’s the new and creative theory, so all examples are very subjective and their meaning is understood only from my own prospect. In my point of view, we can indicate element of music which is dynamics (what means all changes connecting to volume), in the lyrics. The poet Stanisław Barańczak in his creativity was talking about the most important and difficult things, that’s why it needed very impres-sive way of expression.

11

Dynamics of a thick-walled spherical casing loaded with a time depending internal pressure

80%

Włodarczyk E. , Zielenkiewicz M.

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2008

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tom Vol. 46 nr 1

21-40

EN

The problem of radial vibration of a thick-walled spherical casing, loaded with an internal pressure, which is a time function, is studied. We assumed that the material of the casing is incompressible. Furthermore, the linear elasticity theory is applied in the considerations. By means of these simplifications, an analytical solution of dynamics of the thick-walled spherical casing loaded with the internal pressure has been obtained. This solution may be used for estimation of strength of spherical ballistic casings which are applied to explosive driven specimen in ring tests. Moreover, the results of this paper contribute to the theory of vibration of continuous engineering systems.

PL

Zbadano problem radialnych drgań grubościennej osłony kulistej obciążonej udarowo wewnętrznym ciśnieniem impulsowym. Założono, że materiał osłony jest sprężyście nieściśliwy. Przy takim uproszczeniu uzyskano zamknięte analityczne rozwiązali zagadnienia dynamiki osłony kulistej w ramach liniowej teorii sprężystości. Okazuje się, że osłona kulista wykonana z materiału nieściśliwego, podobnie jak rura, obciążona wewnętrznie udarowo, zachowuje się jak układ o jednym stopniu swobody. Częstotliwość kołowa drgań własnych osłony kulistej jest kilkakrotnie większa od częstotliwości rury o tej samej średnicy wewnętrznej i grubości ścianki. Przedstawione rozwiązanie można wykorzystać do szacowania wytrzymałości kulistych osłon balistycznych stosowanych przy wybuchowym napędzaniu cienkościennych pierścieni używanych w badaniach dynamicznych właściwości materiałów. Poza tym, przedstawione wyniki badań dają dodatkowy wkład wiedzy do teorii drgań technicznych układów ciągłych.

12

Scaling features of ambient noise at different levels of local seismic activity. A case study for the Oni seismic station

80%

Matcharashvili T. , Chelidze T. , Javakhishvili Z. , Zhukova N.

Acta Geophysica

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2012

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tom Vol. 60, no. 3

809-832

EN

Investigation of dynamical features of ambient seismic noise is one of the important scientific and practical research challenges. We investigated scaling features of the ambient noises at the Oni seismic station, Georgia, using detrended fluctuation analysis method. Data from this seismic station, located in the epicentral zone of Oni M6.0, 2009, earthquake, were selected to include time periods with different levels of local seismic activity. It was shown that the investigated ambient noise is persistent longrange correlated at calm seismic conditions in the absence of earthquakes. Fluctuation features of the analyzed ambient noises were affected by local earthquakes, while remote seismic activity caused just slight quantitative changes. Processes related to the preparation of a strong local earthquake may cause quantifiable changes in fluctuation features of ambient noises. Fluctuation features of seismic noise for periods of increased local seismic activity cease to be long-range correlated and appear to become a complicated mixture of random and correlated behaviours.

13

A novel method for vibration surveillance during high speed ball end milling of flexible details

80%

Kaliński K. J.

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2007

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tom Vol. 17, no. 3

271-282

EN

The paper is devoted to vibration surveillance of unsteady systems, which are idealized by the finite element method. Ball end milling of flexible details is observed very frequently in case of modern machining centres. Tool-workpiece relative vibration may lead to a loss of stability and cause a generation of self-excited chatter vibration. The paper proposes the method of minimizing vibration level, based on matching the spindle speed to the optimal phase shift. As result of a milling process modeling, we get a hybrid system in which are separated: - Modal subsystem. It is a stationary model of one-side-supported flexible detail. - Structural subsystem, i.e. non-stationary discrete model of ball end mill and cutting process. - Connective subsystem as conventional contact point between tool and workpiece. The method has been developed with success. Modal model of the workpiece allowed us to determine an optimal spindle speed. Modal assurance criterion (MAC) has been assessed and confirmed good agreement between experimental and theoretical modal model. Results of computer simulation, as well as - of experimental investigation on the Mikron VCP 600 milling machine mean to be in support. Hence amplitude values for chosen optimal spindle speed became relatively smaller than for the other ones.

14

Dynamic Behavior of Simple Insertion Sort Algorithm

80%

Grabowski F. , Strzałka D.

|

2006

|

tom Vol. 72, nr 1-3

155-165

EN

This paper deals with new analytical and experimental aspects of influence of data structure and algorithm on sort dynamics. Traditional analysis of data structure-algorithm interface which based on computational complexity is incomplete because do not considers of dynamical effects in area between extremely best and worst cases of computing time. The main aim of this paper are investigations of the impact of long-term dependencies in data structure on sort efficiency. This approach treats interface data structure-algorithm as the complex system in opposition to the classical computational analysis which treats this interface as simple deterministic system. This new approach makes possibilities to determine power spectral density of sorting process and test the existence of 1/f noise in this process which in fact is not noise but reflects the intrinsic dynamic (data flow disturbances inside system) of selforganized computer system. The idea presented in this paper shows how complex system behavior provide a good perspective to analysis of whole computer system as well.

15

Mathematical model of a pipelay spread

71%

Szczotka M. , Wojciech S. , Maczyński A. , Szczotka M. , Wojciech S. , Maczyński A.

|

16

Dynamic loading of the pulley block in a hoisting installation in normal operating conditions

70%

Wolny S.

|

2009

|

tom Vol. 54, no 2

261-284

EN

In order to develop reliable criteria for assessing the working condition of hoisting installations incorporating a pulley block, in the context of their fatigue endurance in the function of service time and depending on the type of hoisting gear. A thorough fatigue analysis is required to find the real loads and their time variations, necessitating the study of dynamic processes during the normal operating conditions of a hoisting gear and in emergency. This study is limited to dynamic processes during the normal service. Predicted data are verified experimentally through measurements of loading of selected elements of the analysed system using a real object.

PL

Opracowanie kryteriów oceny stanu technicznego elementów górniczego urządzenia wyciągowego w tym koła pędnego, ze szczególnym uwzględnieniem trwałości zmęczeniowej w funkcji czasu eksploatacji i rodzaju urządzenia wyciągowego, wymaga przeprowadzenia gruntownej analizy wytrzymałościowo-zmęczeniowej, uwzględniającej rzeczywiste wartości ich obciążeń oraz zmiany tego obciążenia w czasie. Nie można jednak tego osiągnąć bez wnikliwych studiów nad dynamiką procesów zachodzących w czasie normalnej eksploatacji urządzenia jak również awarii. Rozważania zawarte w pracy ograniczono do analizy zjawisk dynamicznych zachodzących w czasie normalnej eksploatacji. Uzyskane rezultaty zweryfikowano pomiarami obciążeń wybranych elementów analizowanego układu na obiekcie rzeczywistym.

17

Determination of critical speeds of a centrifugal pump impeller in annular seals

70%

Kundera C. , Marcinkowski W. A.

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tom Vol. 17, no. 3

873-883

EN

The paper deals with combined transverse and angular vibrations of a single-disc impeller in annular seals. The formulated equations of vibrations include additional (i.e., inertia, damping, potential, gyroscopic and circular) hydrodynamic forces and moments occurring in clearances of non-contact seals. The study involved performing digital calculations to determine the natural frequencies in two models of the rotor, both for constant pressure drops in seals and for a square relationship between the pressure drops and the rotational frequency of the impeller. It was also necessary to estimate the influence of the conicity of the annular clearance gaps in non-contacting seals on the natural and critical frequencies of the rotor.

18

Nonlinear Dynamics of a Controlled Stirred Tank Bioreactor With Predator-Prey Relationship

70%

Tabiś B. , Skoneczny S. , Stryjewski W. S.

Chemical and Process Engineering

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2014

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tom 35

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nr 3

349-360

EN

The paper presents the dynamic characteristics of a continuous tank bioreactor for microbiological process, with a developed predator-prey food chain. The presence of the predator microorganism considerably influences the position and stability character of steady-states. There appears to exist a wide range of unstable steady-states and high-amplitude oscillations of state variables. Without automatic control, the system can operate only in unsteady conditions. From technological point of view, this circumstance is unfavorable. It was shown that oscillations can be removed by employing automatic control with continuous P or PI controllers. Moreover, the use of a controller with integrating element causes removal of the predator from the bioreactor. The paper discusses an application of this phenomenon for practical purposes.

19

Application of active magnetic bearings for identification of the force generated in the labirynth seal

70%

Kozanecka D. , Kozanecki Z. , Lech T. , Kaczmarek A.

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2007

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tom Vol. 45 nr 1

53-60

EN

A magnetic bearing system of a rotating shaft is characterized by a unique feature that consists in the possibility of monitoring static and dynamic loads (reactions) of each bearing under normaI operation of the machine. In the paper, an identification procedure of bearing response forces, which allows for simultaneous measurement of the journal position with respect to the bush and the controI currents that flow in magnetie bearing bush windings, is presented. The proposed procedure ensures effective protection of the rotating shaft supported in active magnetic bearings against too high loads and displacements that can occur in the rotating system. Experimental investigations were carried out on test rigs wit h the shaft supported in active magnetic bearings.

PL

System łożyskowania magnetycznego wirującego wału charakteryzuje unikatowa możliwość pozwalająca na monitorowanie obciążeń statycznych i dynamicznych (reakcji) w czasie pracy maszyny. W artykule przedstawiono procedurę identyfikacji sił reakcji łożyska, pochodzących od działającego uszczelnienia labiryntowego, która polega na jednoczesnym pomiarze pozycji czopa w panwi oraz prądu płynącego w uzwojeniach elektromagnesów panwi. Eksperymentalną weryfikacją procedury przeprowadzono na stanowisku badawczym maszyny z wałem podpartym w aktywnych łożyskach magnetycznych.

20

Nové výpůjčky a jejich ekvivalenty v češtině, francouzštině, řečtině a polštině

70%

Hildenbrand Z. , Polická A.

Časopis pro moderní filologii (Journal for Modern Philology)

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2014

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tom 96

|

nr 1

100-110

XX

This paper aims to present contemporary French neological studies and focuses on new loanwords and their dissemination in four languages — French in France, Czech, Polish and Greek. The first results of an ongoing European research project are presented; the adoption of neologisms (mainly loanwords from English) succeeds differently and at different times in each of the four countries depending on the (non-)existence of local word equivalents.