Wyniki wyszukiwania - BazTech

1

Model systemu antenowego mikro-satelity do odbioru telekomend w paśmie S

Klonowski P., Kurek K.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2018

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nr 6

494--497, CD

PL

Artykuł opisuje propozycję systemu antenowego mikro-satelity dla łączności pomiędzy satelitą na orbicie a naziemną stacją kontrolną. System antenowy ma umożliwiać odbiór sygnału radiowego w paśmie S, wysyłanego do satelity z Ziemi (telekomendy sterujące pracą satelity) niezależnie od orientacji satelity względem Ziemi, W artykule zaproponowano wykorzystanie w tym celu systemu dwóch anten łatkowych umieszczonych na sąsiednich ściankach małego satelity. Przedstawiono wyniki symulacji i pomiarów opracowanego modelu takiego systemu.

EN

The paper describes a proposition of the antenna system of the micro-satellite, allowing to receive a radio signal from a ground control station (telecommands send to the satellite) in S band, regardless of the satellite orientation. The proposition of the use of two patch antennas placed on two satellite walls is described, and simulations and measurement results of realized model of such system is presented.

2

An Impact of Technological Conditions on Surface Burning in Grinding of the Orbit

Stančeková Dana, Mrázik Jozef, Rybicka Iwona, Náprstková Nataša, Kraus Pavel

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 4

19--27

EN

A process of quality development helps us reveal concrete deficiences, an analysis of their origin and realization of required modifications that are needed to solve a concrete problem. One of the aims of quality development of production in bearing industries is to find out an impact of tchnological conditions to form burning of surfaces in grinding of orbits of bearing rings. We try to describe an origin of the problem, to find reasons of burned surfaces in a process of grinding and to propose such technological conditions to avoid above-stated problems and to produce the least possible number of non-identical workpieces. To lower a number of burnings in grinding of the orbit to zero percentage is not real, however, we have to try to get a minimal number of parts with damaged surface.

3

Optimum bi-impulsive non coplanar elliptic Hohmann type transfer

Kamel O. M., Soliman A. S.

Mechanics and Mechanical Engineering

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2010

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Vol. 14, nr 1

81-104

EN

We optimize the Hohmann type bi-impulsive transfer between inclined elliptic orbits having a common center of attraction, for the four feasible configurations. Our criterion for optimization is the characteristic velocity ΔvT = Δv1 + Δv2 which is a measure of fuel consumption. We assigned the optimum value of our variable x (ratio between velocity after initial impulse and velocity before initial impulse) by a numerical solution of an algebraic eight degree equation. We have a single plane change angle α. We present terse new formulae constituting a new alternative approach for tackling the problem. The derivations of formulae of our treatment are simple, straightforward and exceptionally clear. This is advantageous. By this semi-analytic analysis we avoid many complexities and ambiguity that appear in previous work.

4

Selected Accelerations and Orbital Elements of the GOCE Satellite in the Time Domain

Bobojć A.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2009

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nr 12

104-117

EN

The work contains the results of the GOCE satellite orbit simulation. The GOCE satellite orbit was presented in the aspect of the temporary changes in selected accelerations and in selected keplerian elements. The satellite accelerations due to: the geopotential, the Earth tides and the ocean tides (the radial component for both), the gravitation of the Moon and the gravitation of the Sun, were presented in function of time. The showed changes in orbital elements include the semi-major axis, eccentricity, inclination, argument of perigee and right ascension of ascending node. For the orbit determination the Cowell numerical integration method of the eighth order was used. The geopotential was described by means of the EGM96 model. The mentioned temporary changes in the selected accelerations and orbital elements were described. Most of them contain the characteristic periodic components, which are close to the satellite orbital period, the Earth's rotation period and the Moon's synodic period.

PL

Praca zawiera wyniki symulacji orbity satelity GOCE. Orbitę satelity GOCE przedstawiono w aspekcie zmian czasowych wybranych przyśpieszeń i elementów keplerowskich. Przyśpieszenia satelity spowodowane przez: geopotencjał, pływy skorupy, pływy oceaniczne (składowa radialna dla obu), grawitację Słońca i grawitację Księżyca, przedstawiono w funkcji czasu. Pokazane zmiany w elementach orbity obejmują półoś wielką, mimośród, nachylenie, argument perygeum i rektascensję węzła wstępującego. Do wyznaczenia orbity użyto całkowania numerycznego metodą Cowella ósmego rzędu. Geopotencjał opisano modelem EGM96. Opisano wspomniane zmiany czasowe wybranych przyśpieszeń i elementów orbity. Większość z nich zawiera charakterystyczne składowe okresowe, które są zbliżone do okresu orbitalnego satelity, okresu rotacji Ziemi oraz okresu synodycznego Księżyca.

5

Velocity Correction in Generalized Hohmann and Bi-elliptic Impulsive Orbital Maneuvers Using Energy Concepts

Kamel O. M., Soliman A. S.

Mechanics and Mechanical Engineering

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2008

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Vol. 12, nr 1

31-49

EN

We applied small tangential impulses due to motor thrusts at peri-apse and apo-apse perpendicular to major axis of the elliptic orbits. Our aim is to obtain a precise final orbit stemming from an initial orbit. We executed these tangential correctional velocities to all the four feasible configurations. The correctional increments of velocities ΔvA & ΔvB at the points A, B for the Hohmann transfer and at the points A, B, C for the Bi-Elliptic transfer induce the precise final orbit. Throughout the treatment we encounter relationships for both cases of transfer that describe the alteration in major axes and eccentricities due to these motor thrusts supplied by a rocket. The whole theory is a correctional improvement process.

6

Minimal actions on Cantor cubes

Turek S.

Bulletin of the Polish Academy of Sciences. Mathematics

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2003

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Vol. 51, no 2

129-138

EN

There are investigated minimal actions of countable groups on the Cantor cube of weight continuum. In particular there is shown that for every countable abelian group G there exists a homomorphism pi of G into the group Homeo(D^2omega) of all homeomorphisms of the Cantor cube D^2omega onto itself such that for every x is a member of a set D^2omega the orbit {pi{g)(x):g is a member of a set G} is dense in the cube.

7

On iterative roots of homeomorphisms of the circle

Zdun M.

Bulletin of the Polish Academy of Sciences. Mathematics

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2000

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Vol. 48, no 2

203-213

EN

In this paper we deal with the problem of existence and uniqueness of continuous iterative roots of homeomorphisms of the circle. Let F : [S^1 --> S^1] be a homeomorphism without periodic points. If the limit set of the orbit [F^k(z), k belongs to Z] equals [S^1], then F has exactly n iterative roots of n-th order. Otherwise F either has no iterative roots of n-th order or F has infinitely many iterative roots depending on an arbitrary function. In this case we determined all iterative roots of n-th order of F.

8

Set-valued iterative square roots of bijections

Powierża T.

Bulletin of the Polish Academy of Sciences. Mathematics

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1999

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Vol. 47, no 4

377-383

EN

There are different ideas how to generalize the notion of an iterative root, especially when a function does not have a "real" root. We consider a multifunction as a substitute for this notion.

9

TheBanach-Mazur compacta are absolute retracts

Antonian S.

Bulletin of the Polish Academy of Sciences. Mathematics

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1998

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Vol. 46, no 2

113-119

EN

We prove that the space N(E) of all norms on n-dimensional linear space E is a proper G-space under the natural action of the full linear group G = GL(n). The Banach-Mazur compactum Q(n) is just the orbit space of the G-space N(E). We show here that for any n [is greater than or equal to] 1, Q(n) is an absolute retract for metric spaces. We generalize this fact be showing that for a locally compact almost connected group G, its maximal compact subgroup K, and a proper G-space X, X/G is an A(N)R space provided it is metrizable and X is a K-A(N)R space.