Wyniki wyszukiwania - BazTech

1

Oddziaływania czarnych dziur

Szybka Sebastian J.

Postępy Fizyki

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2023

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T. 74, z. 3

15--23

PL

Końcowym stadium niepohamowanego kolapsu grawitacyjnego jest pojedynczy obiekt zwany czarną dziurą. Czy czarne dziury zawsze mają taką samą uniwersalną postać? Chociaż twierdzenie o jednoznaczności czarnych dziur udziela pozytywnej odpowiedzi na to pytanie, to każde twierdzenie jest tylko tak silne, jak jego założenia. Przez wiele lat fizycy nie potrafili wykluczyć istnienia stacjonarnych konfiguracji dwóch czarnych dziur, które mogłyby wspólnie tworzyć bardziej złożony obiekt. Obecnie znamy rozwiązanie tego problemu.

EN

The final stage of an unrestrained gravitational collapse is a single object known as a black hole. Do black holes always have the same universal form? Although the uniqueness theorem provides a positive answer to this question, every theorem is only as strong as its assumptions. For many years physicists were unable to exclude the existence of stationary configurations of two black holes that could form together a more complex object. Currently, we know the solution to this problem.

2

Improved MCBDS for defending against gray hole and black hole attacks in MANETs

Haghighi A., Mizanian K., Mirjalily G.

Advances in Science and Technology. Research Journal

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2016

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Vol. 10, nr 30

1--8

EN

Mobile Ad-hoc Networks (MANETs) are widely used nowadays. Because of their characteristics as open media, dynamic topology, being infrastructure-less and lack of centralized monitoring, MANET is vulnerable to a wide range of attacks like blackhole and grayhole. Blackhole and grayhole attacks refer to the attacks that breach the security by performing packet forwarding and routing misbehavior and cause denial of service in MANETs. In this paper we improved our previous work on MCBDS, we reduced false-positive rate more than before and on average it dropped to zero. The proposed method employs Network Simulator-2 (NS-2) to validate the effectiveness under different scenarios. Simulation results show that improved MCBDS has same performance as CBDS in terms of throughput and end-to-end delay and as much as the presence of malicious nodes increased, improved MCBDS performs better than CBDS.

3

On the Mathematical Analysis of Black-Hole Information Loss Paradox

Vishal V., Siddharth B., Venkatachalam C.

International Letters of Chemistry, Physics and Astronomy

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2013

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Vol. 13

8-12

EN

A black-hole is an astronomical entity which possesses infinite density at its gravitational singularity or singular point. The capacity of a black-hole to completely rip-off an entire solar system without leaving any evidence is to be noted. A debate has been going on over the past few decades regarding the information storage in black-holes. The discovery of Hawking radiation, which predicts complete evaporation of mass violates unitarity ie. Conservation of probability and energy fails. Recent discoveries suggest that regular remnant of black-hole survives evaporation , as a result information of the object devoured can be contained. These remnants are grouped into embedded sub-manifolds. These manifolds are the result of a five-dimensional constant curvature bulk in space-time. Five-dimensional gravity can be recovered from brane-world resulting from equations of bulk geometry. Gravity can be explained by space-time theory and also quantum theory in the form of Gravitons. On observing the manifold, the gravitons show deformations in dimensions, rather than being constant. The perturbations in geometry can be related to embedding functions which should remain differentiable and regular. Regularity is related to the inverse functions theorem. Manifold observations followed by a mathematical approach can possibly retain information about objects devoured by the black-hole.

4

Czarne Dziury - najbardziej tajemnicze obiekty kosmosu

Hemka L.

Nowa Elektrotechnika

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2006

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nr 5 (21)

21--23

5

Complexity of Searching for a Black Hole

Czyzowicz J., Kowalski D., Markou E., Pelc A.

Fundamenta Informaticae

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2006

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Vol. 71, nr 2,3

229-242

EN

A black hole is a highly harmful stationary process residing in a node of a network and destroying all mobile agents visiting the node, without leaving any trace. We consider the task of locating a black hole in a (partially) synchronous network, assuming an upper bound on the time of any edge traversal by an agent. The minimum number of agents capable to identify a black hole is two. For a given graph and given starting node we are interested in the fastest possible black hole search by two agents, under the general scenario in which some subset of nodes is safe and the black hole can be located in one of the remaining nodes. We show that the problem of finding the fastest possible black hole search scheme by two agents is NP-hard, and we give a 9.3-approximation for it.