Wyniki wyszukiwania - Biblioteka Nauki

1

The physics of superdeep penetration phenomenon

100%

Owsik J. , Jach K. , Usherenko S. , Usherenko Y. , Figovsky O. , Sobolev V.

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2008

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tom Vol. 49, no 1

3-25

EN

While solving the problem of superdeep penetration, a dilemma appears: will we deal with an unusual mechanism of effective transformation of impact energy of a clot into energy of separate strikers motion or will it be a process of additional energy emission? It was shown that all possibilities of explanation of the decrease in resistance to a striker at its movement in a solid body due to the mechanism of economical use of the kinetic energy, are considered (so-called dead end was stated). Estimations of a minimum energy necessary for superdeep penetration have been performed. The obtained results have proved that the kinetic energy of a collision of a clot of discrete (separate) strikers with a barrier makes only 5-10% of the total amount of the energy loss. It was shown that the process of cavitation of microcavities in dense plasma is the source of additional energy, providing implementation of superdeep penetration.

2

Mechanical energy fluctuations during walking of healthyand ACL-reconstructed subjects

88%

Winiarski S.

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2008

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tom Vol. 10, nr 2

57-63

EN

In a clinical gait analysis, mechanical energy is the gait variable which can validate the energetic state of the disorder of patient’s movement. The purpose of this study was to explore the possibilities of employing the total mechanical energy in estimating the mechanical cost of transport in normal and pathological human gait. One of the basic methods of determining mechanical energy (inverted pendulum model) was used to estimate the external mechanical work performed by the walking subjects based on externally observable measurements. Gait data was collected for healthy able-bodied men and patients after ACL reconstruction during physiotherapy process who demonstrate larger lateral center of gravity (CoG) excursions during gait. Based on predictions of the body’s CoG trajectory during walking, algorithms were developed to determine the changes in components of total mechanical energy in normal and pathological gait. The utility of calculating mechanical energy in a patient population is questioned.

3

An experience of using the method of direct numerical simulation of large-scale turbulence to the computation of supersonic turbulent shear layer

75%

Tixtinskaya J.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

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1999

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tom nr 9

213-219

EN

One of the modification of Large Eddy Simulation method is developed. It is applied to the problem of mixing of two supersonic flows. Kelvin-Helmholtz instability is obtained. Instantaneous data are averaged and the shear layer thickness is calculated. It is compared with the experimental one. The conclusion about the sensitivity of the method to the change in model constants is made.

4

Reaction mechanism study using total kinetic energy and prescission particle multiplicity in medium mass nuclei

75%

Yuasa-Nakagawa K. , Nakagawa T. , Yoshida K. , Liu X. , Lee S. M. , Jiang D. X. , Aoki Y. , Kasagi J. , Furutaka K.

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1998

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tom Vol. 43, nr 3

281-290

EN

We measured γ-ray multiplicity and light charged particle (LCP) multiplicity simultaneously in coincidence with binary decay fragments in the reaction of (sup 84)Kr + (sup 27)Al at the incident energy of 8.5 MeV/nucleon. We observed the prescission LCP multiplicities and total kinetic energy (TKE) of heavy fragments as a function of the angular momentum of the system applying the measured γ-ray multiplicity as an angular momentum filter. For this reaction the fusion-fission process seems to occur dominantly only at the angular momentum ∼ 70ħ which is concluded from the dependence of prescission proton multiplicity on the TKE. The charge distribution of binary decay fragments changes from the symmetric mass division to asymmetric one with increasing the γ-ray multiplicity.

PL

Zmierzono jednocześnie krotności kwantów γ i lekkich cząstek naładowanych w koincydencji z fragmentami binarnego rozpadu w reakcji (sup 84)Kr + (sup 27)Al przy energii pierwotnej 8.5 MeV/nukleon. Wyznaczono krotności cząstek naładowanych i całkowitą energię kinetyczną ciężkich fragmentów w funkcji momentu pędu układu, wykorzystując zmierzoną krotność kwantów γ jako filtr momentu pędu. W przypadku rozważanej reakcji process fusion-fission wydaje się występować głównie przy momencie pędu ∼ 70ħ, co wywnioskowano z zależności krotności protonów pre-scission od całkowitej energii kinetycznej. Rozkład ładunku fragmentów zmienia się wraz ze zwiększającą się krotnością kwantów γ od podziału symetrycznego do asymetrycznego.

5

A mathematical model of the parachute system at a descent stage

75%

Brusov V. , Denezkina I. , Morozov N.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

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2001

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tom nr 11

21-24

EN

This paper deals with the following mathematical models of the parachute system(PS): - Mathematical model of the PS motion at the inflation and descent stages, - Mathematical model of the parachute inflation, When solving the considered problems the descending object is assumed to be a solid body, the parachute canopy has a symmetrical form, and the PS moves a calm atmosphere at a subsonic speed. The PS motion at the stages of inflation and decent is described by a system of ordinary differential equations. A model of the PS inflation is described in terms of the theory of soft permeable shells reinforced by flexible ribbons. The mathematical models used in calculations allow for finding a trajectory, determination of the kinetic parameters of the PS motion, and computation of the forces acting in the canopy structural elements and forces acting in the joint between the parachute and body.

6

Układ do wyznaczania energii kinetycznej pocisków o niewielkiej prędkości

63%

Tuśnio J. , Tuśnio N.

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2012

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tom Vol. 53, nr 9

114-117

PL

W artykule przedstawiono konstrukcję urządzenia umożliwiającego wyznaczenie energii kinetycznej poruszających się z niewielką prędkością pocisków wystrzeliwanych z wyrzutni lub służącej zabawie imitacji broni palnej, w której wyrzucenie pocisku odbywa się za pomocą mechanizmu sprężynowego. Wyznaczanie energii odbywa się w sposób pośredni poprzez pomiar czasu przelotu pocisku pomiędzy bramką optyczną i akustyczną, krótkie impulsy oznaczające początek i koniec przelotu zostają wprowadzone do komputera, gdzie odstęp między nimi zostaje przeliczony na prędkość lotu a następnie na podstawie wpisanej wcześniej wartości masy pocisku zostaje obliczona energia kinetyczna wyrobu.

EN

The paper presents the design of the device allowing determination of the kinetic energy of moving at low speed and launched from launcher or serving imitation firearms play in which a projectile is thrown with a spring mechanism. Determination of energy takes place in an indirect way by measuring time of flight of the projectile between the optical and acoustic goal, short pulses indicating the beginning and end of the trip will be entered into the computer, where the distance between them is converted to airspeed and then on the basis of previously entered values of projectile mass is calculated kinetic energy of the product.

7

On the added mass effect for porous media

63%

Kosiński W. , Kubik J. , Hutter K.

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2002

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tom Vol. 54, nr 5-6

479-495

EN

Consider a porous solid skeleton saturated with N fluid constituents. To describe the saturation condition and the immiscibility of the mixture constituents (phases), N+1 volume fraction parameters are introduced. In the energy equation an added mass effect is incorporated in the form of a constitutive assumption. This allows to include, on the phenomenological level, the influence of the pore structure of the solid constituent on the kinetic energy formulation of the whole mixture. Its consequences are deduced; they lead to a new form of the kinetic energy in the balance law of energy, from which a new form of motion equations are deduced. A particular case of one fluid component in the isotropic case is considered.