We introduce notions of local and interweight spectra of an arbitrary coloring of a Boolean cube, which generalize the notion of a weight spectrum. The main objects of our research are colorings that are called perfec...
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We introduce notions of local and interweight spectra of an arbitrary coloring of a Boolean cube, which generalize the notion of a weight spectrum. The main objects of our research are colorings that are called perfect. We establish an interrelation of local spectra of such a coloring in two orthogonal faces of a Boolean cube and study properties of the interweight spectrum. Based on this, we prove a new metric property of perfect colorings, namely, their strong distance invariance. As a consequence, we obtain an analogous property of an arbitrary completely regular code, which, together with his neighborhoods, forms a perfect coloring.
Ever since the birth of coding theory almost 60 years ago, researchers have been pursuing the elusive goal of constructing the "best codes," whose encoding introduces the minimum possible redundancy for the ...
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Ever since the birth of coding theory almost 60 years ago, researchers have been pursuing the elusive goal of constructing the "best codes," whose encoding introduces the minimum possible redundancy for the level of noise they can correct. In this article, we survey recent progress in list decoding that has led to efficient error-correction schemes with an optimal amount of redundancy, even against worst-case errors caused by a potentially malicious channel. To correct a proportion rho (say 20%) of worst-case errors, these codes only need close to a proportion r of redundant symbols. The redundancy cannot possibly be any lower information theoretically. This new method holds the promise of correcting a factor of two more errors compared to the conventional algorithms currently in use in diverse everyday applications.
Automatic discrimination of speech and music is an important tool in many multimedia applications. This article presents an evolutionary, fuzzy, rules-based speech/music discrimination approach for intelligent audio c...
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Automatic discrimination of speech and music is an important tool in many multimedia applications. This article presents an evolutionary, fuzzy, rules-based speech/music discrimination approach for intelligent audio coding, which exploits only one simple feature, called Warped LPC-based Spectral Centroid (WLPC-SC). Comparison between WLPC-SC and the classical features proposed in the literature for audio classification is performed, aiming to assess the good discriminatory power of the proposed feature. The length of the vector for describing the proposed psychoacoustic-based feature is reduced to a few statistical values (mean, variance, and skewness), which are then transformed to a new feature space, applying linear discriminant analysis (LDA), with the aim of increasing the classification accuracy percentage. The classification task is performed applying a support vector machine (SVM) to the features in the transformed space. The final decision is made by a fuzzy expert system, which improves the accuracy rate provided by the SVM, taking into account the audio labels assigned by this classifier to past audio frames. The accuracy rate improvement due to the fuzzy expert system is also reported. Experimental results reveal that our speech/music discriminator is robust and fast, making it suitable for intelligent audio coding.
Two codes C (1) and C (2) are said to be weakly isometric if there exists a mapping J: C (1) -> C (2) such that for all x, y in C (1) the equality d(x, y) = d holds if and only if d(J(x), J(y)) = d, where d is the ...
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Two codes C (1) and C (2) are said to be weakly isometric if there exists a mapping J: C (1) -> C (2) such that for all x, y in C (1) the equality d(x, y) = d holds if and only if d(J(x), J(y)) = d, where d is the code distance of C (1). We prove that Preparata codes of length n a parts per thousand yen 2(12) are weakly isometric if and only if the codes are equivalent. A similar result is proved for punctured Preparata codes of length at least 2(10) - 1.
Cooperative communication has been shown to be an effective technique enabling single-antenna users to share their antennas to create a virtual MIMO system, thus providing extra spatial diversity in wireless networks....
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Cooperative communication has been shown to be an effective technique enabling single-antenna users to share their antennas to create a virtual MIMO system, thus providing extra spatial diversity in wireless networks. Distributed coding is a type of channel coding strategy developed for cooperative wireless networks. As opposed to conventional channel coding schemes, distributed coding constructs the whole codeword in a distributed manner among the cooperative users. Properly designed distributed coding can effectively approach the capacity of cooperative wireless networks. The aim of this article is to present an overview of recent development in distributed coding design in cooperative wireless networks.
The subspace metric is an object of active research in network coding. Nevertheless, little is known on codes over this metric. In the present paper, several classes of codes over subspace metric are defined and inves...
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The subspace metric is an object of active research in network coding. Nevertheless, little is known on codes over this metric. In the present paper, several classes of codes over subspace metric are defined and investigated, including codes with distance 2, codes with the maximal distance, and constant-distance constant-dimension codes. Also, Gilbert-type bounds are presented.
Three groups of slightly enriched UO(2) fueled, hexagonal light-water moderated lattice critical experiments were analyzed with the APOLLO code at the Hungarian Academy of Sciences KFKI AEKI Reactor Analysis Laborator...
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Three groups of slightly enriched UO(2) fueled, hexagonal light-water moderated lattice critical experiments were analyzed with the APOLLO code at the Hungarian Academy of Sciences KFKI AEKI Reactor Analysis Laboratory, in collaboration with CEA. The work was a part of the NURESIM project where KFKI undertook to develop and qualify some calculation schemes for hexagonal problems using APOLLO2 version 2.7. in the first step non-perturbed asymptotic lattices characterized by material buckling, regular lattice perturbed by different content of gadolinium and reactivity coefficient measurements were chosen for simulation. The modeling approaches used in this analysis are discussed for selected cases. Generally the results performed by the French code using the JEF 2.2 based CEA93.V7 group library were compared to the measurements but in some cases inter-comparisons were performed to both Monte Carlo solutions as well as against results of the Hungarian lattice transport code MULTICELL based on ENDF-B/VI nuclear data. Even if the agreement between calculations and measurements differs for different codes using different nuclear data and methods the overall agreement among measured and calculated figures are good. (C) 2009 Elsevier Ltd. All rights reserved.
Families of finite graphs of large girth were introduced in classical extremal graph theory. One important theoretical result here is the upper bound on the maximal size of the graph with girth >= 2d established in...
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Families of finite graphs of large girth were introduced in classical extremal graph theory. One important theoretical result here is the upper bound on the maximal size of the graph with girth >= 2d established in even circuit theorem by Erdos. We consider some results on such algebraic graphs over any field. The upper bound on the dimension of variety of edges for algebraic graphs of girth >= 2d is established. Getting the lower bound, we use the family of bipartite graphs D(n, K) with n >= 2 over a field K, whose partition sets are two copies of the vector space K-n. We consider the problem of constructing homogeneous algebraic graphs with a prescribed girth and formulate some problems motivated by classical extremal graph theory. Finally, we present a very short survey on applications of finite homogeneous algebraic graphs to coding theory and cryptography. (C) 2008 Elsevier Inc. All rights reserved.
In this paper, we report the development and verification of a method of characteristics (MOC) code, PEACH, at Shanghai Jiao Tong University. Both the usual flat-source step characteristics (SC) scheme and the linear ...
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In this paper, we report the development and verification of a method of characteristics (MOC) code, PEACH, at Shanghai Jiao Tong University. Both the usual flat-source step characteristics (SC) scheme and the linear source (LS) approximation scheme are adopted for the tracking calculation along the neutron trajectory. The assembly-based modular ray tracing (AMRT) technique that possesses a good geometric flexibility and high efficiency is employed, which makes PEACH able to deal with practical LWR assembly and core problems. Moreover, in order to reduce the computational time of the MOC iteration process, both the multi/few-group two-level cell-based coarse mesh finite difference (CMFD) acceleration and the exponential function interpolation technique are used. This results in a significant acceleration. Numerical results for the OECD NEA C5G7 MOX benchmark problem and a 69-group BWR mini-core problem demonstrate that PEACH is accurate and efficient. Numerical results also demonstrate that the LS scheme is more efficient than the SC scheme, taking less time and system memory to generate results of comparable accuracy. In addition, we find that MOC with CMFD acceleration always converges with almost the same number of outer iterations regardless of the physical problem size and the discretization parameters used. This shows an ideal linear relationship between the run time and the geometric size of the problem. (C) 2009 Elsevier Ltd. All rights reserved.
We consider regular block and convolutional LDPC codes determined by paritycheck matrices with rows of a fixed weight and columns of weight 2. Such codes can be described by graphs, and the minimum distance of a code ...
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We consider regular block and convolutional LDPC codes determined by paritycheck matrices with rows of a fixed weight and columns of weight 2. Such codes can be described by graphs, and the minimum distance of a code coincides with the girth of the corresponding graph. We consider a description of such codes in the form of tail-biting convolutional codes. Long codes are constructed from short ones using the "voltage graph" method. On this way we construct new codes, find a compact description for many known optimal codes, and thus simplify the coding for such codes. We obtain an asymptotic lower bound on the girth of the corresponding graphs. We also present tables of codes.
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