A perturbation technique has been developed in Part I to consider the computation of the normal forms for general multiple-degree-of-freedom autonomous systems. In this paper, the perturbation approach is extended to ...
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We investigate variants of Lloyd's heuristic for clustering high dimensional data in an attempt to explain its popularity (a half century after its introduction) among practitioners, and in order to suggest improv...
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Consider Alice and Bob, who have some shared secret which helps Alice to identify Bob-impersonators, and Eve, who does not know their secret. Eve wants to impersonate Bob and "fool" Alice. If Eve is computat...
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ISBN:
(纸本)1595933832
Consider Alice and Bob, who have some shared secret which helps Alice to identify Bob-impersonators, and Eve, who does not know their secret. Eve wants to impersonate Bob and "fool" Alice. If Eve is computationally unbounded, how long does she need to observe Bob before she can impersonate him? What is a good strategy for Eve? If (cryptographic) one-way functions exist, an efficient Eve cannot impersonate even very simple Bobs, but if they do not exist, can Eve learn to impersonate any efficient Bob? We formalize these questions in a new computational learning model, which we believe captures a wide variety of natural learning tasks, and tightly bound the number of observations Eve makes in terms of the secret's entropy. We then show that if one-way functions do not exist, then an efficient Eve can learn to impersonate any efficient Bob nearly as well as an unbounded Eve. For the full version of this work see (Naor & Rothblum, 2006).
Wireless sensor networks are tightly associated with the underlying environment in which the sensors are deployed. The global topology of the network is of great importance to both sensor network applications and the ...
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ISBN:
(纸本)1595932860
Wireless sensor networks are tightly associated with the underlying environment in which the sensors are deployed. The global topology of the network is of great importance to both sensor network applications and the implementation of networking functionalities. In this paper we study the problem of topology discovery, in particular, identifying boundaries in a sensor network. Suppose a large number of sensor nodes are scattered in a geometric region, with nearby nodes communicating with each other directly. Our goal is to find the boundary nodes by using only connectivity information. We do not assume any knowledge of the node locations or inter-distances, nor do we enforce that the communication graph follows the unit disk graph model. We propose a simple, distributed algorithm that correctly detects nodes on the boundaries and connects them into meaningful boundary cycles. We obtain as a byproduct the medial axis of the sensor field, which has applications in creating virtual coordinates for routing. We show by extensive simulation that the algorithm gives good results even for networks with low density. We also prove rigorously the correctness of the algorithm for continuous geometric domains. Copyright 2006 ACM.
By using the Lagrange interpolation formula and the technology of signature of equality, a (k, n) threshold nominative proxy signature scheme is proposed, where an original signer delegates his (her) signing power to ...
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By using the Lagrange interpolation formula and the technology of signature of equality, a (k, n) threshold nominative proxy signature scheme is proposed, where an original signer delegates his (her) signing power to a proxy, who generates a nominative signature on behalf of the original signer and only k or more active verifiers in the n nominees (verifiers) nominated by the proxy signer can verify the signature signed by the proxy. If necessary, these (k or more) active nominees (verifiers) can prove its validity to a third party. In this scheme, the secret shares are generated and en- crypted by the original signer. At the same time, the ciphertexts of the secret shares are used as parts of the signature. Then, the secret shares need not be sent to the nominees (verifiers) secretly. The ordinary nominative proxy signature can be viewed as a (1, 1) threshold nominative proxy signature. The ordinary nominative proxy signature can be viewed as a special case of a (k, n) threshold nominative proxy signature. According to the security analysis of this paper, it is found that our scheme is secure against a proxy signing key forgery attack and existential forgery on an adaptive chosen message attack.
In wireless sensor networks (WSN), reliable monitoring of a phenomenon (or event detection) depends on the collective data provided by the target cluster of sensors and not on any individual node. In this paper we def...
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Three parallel sorting algorithms have been implemented and compared in terms of their overall execution time. The algorithms implemented are the odd-even transposition sort, parallel merge sort and parallel rank sort...
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Three parallel sorting algorithms have been implemented and compared in terms of their overall execution time. The algorithms implemented are the odd-even transposition sort, parallel merge sort and parallel rank sort. A homogeneous cluster of workstations has been used to compare the algorithms implemented. The MPI library has been selected to establish the communication and synchronization between the processors. The time complexity for each parallel sorting algorithm will also be mentioned and analyzed.
This paper deals with a discretization approach to solve ill-posed operator equations based on Tikhonov regularization strategy. By ordinary numerical integration method, the operator equation can be discretized to a ...
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This paper deals with a discretization approach to solve ill-posed operator equations based on Tikhonov regularization strategy. By ordinary numerical integration method, the operator equation can be discretized to a matrix equation, and then discrete Tikhonov regularization algorithm can be established with matrix singular value decomposition (SVD). As compared with the continuous regularization for operator equations and ordinary discrete regularization by projection methods, this algorithm can reach an optimal convergence rate under a concrete restriction for the discretization level and the right hand-side data by which the optimal regularization parameter can be easily determined. Numerical results are presented showing that the algorithm here is effective and practical.
A new type of timed alternating finite automata (TAFA) called omega deterministic timed alternating finite automata (Ω-DTAFA) is described. DTAFA and Ω-DTAFA are synchronous and parallel computational models used fo...
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A new type of timed alternating finite automata (TAFA) called omega deterministic timed alternating finite automata (Ω-DTAFA) is described. DTAFA and Ω-DTAFA are synchronous and parallel computational models used for modeling real-time constraints computations and developing software systems. These models are extended with a finite set of mutually exclusive real-valued clocks on events which trigger the state transitions of the automaton. We consider some well-known automata-theoretic properties of TAFA, and investigate those properties in the case of Ω-DTAFA. We then show that, unlike timed finite automata (TFA) and TAFA, Ω-DTAFA are closed under all Boolean operations, including the complementation. Moreover, we show that the addition of alternation, timing, and determinism to finite automata increase their expressive and descriptional parallel power, as measured by the size of the automaton which has immediate practical applications in software and real-time systems.
Due to cost constraints and limited sensing capability of sensor nodes, it may be impossible or unrealistic for a wireless sensor network to provide full area coverage in some circumstances. In this paper, we introduc...
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Due to cost constraints and limited sensing capability of sensor nodes, it may be impossible or unrealistic for a wireless sensor network to provide full area coverage in some circumstances. In this paper, we introduce the novel concept of information-oriented sensing coverage, which measures the actual information utility obtained by a wireless sensor network. An information-oriented sensor deployment algorithm is proposed. The algorithm makes use of the fact that in many applications the importance or the information utility at different locations is non-uniform across the sensing field. The effectiveness of the proposed algorithm is studied using simulation. Being a pioneering effort in this area, our work paves a new direction of sensor deployment.
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