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A parallel equivalence algorithm based on MPI for GNSS data processing

JOURNAL OF SPATIAL SCIENCE 2021年第3期66卷 513-532页

作者： Jiang, Chunhua Xu, Tianhe Du, Yujun Sun, Zhangzhen Xu, Guochang Shandong Univ Inst Space Sci Weihai Shandong Peoples R China

A modified algorithm combining equivalence theory with MPI technology to improve Global Navigation Satellite System data processing efficiency is presented. The reservation of covariance matrix, elimination of unknowns and parallelism of the equivalence algorithm are derived. Experimental results show that the algorithm can improve the efficiency of processing 100 IGS stations by 56% with negligible precision loss. Moreover, the proposed approach has higher efficiency than the leastsquares and Gauss-Jordan parallel method and this advantage is more obvious as computational scale increases. Further experiments on a clustershow the more nodes used, the higher the efficiency it can achieve.

关键词： Global navigation satellite system equivalence algorithm precision analysis Message-Passing-Interface parallel parameter estimation

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White-Box AES Implementation Revisited

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JOURNAL OF COMMUNICATIONS AND NETWORKS 2016年第3期18卷 273-287页

作者： Baek, Chung Hun Cheon, Jung Hee Hong, Hyunsook Seoul Natl Univ Dept Math Sci Seoul South Korea

White-box cryptography presented by Chow et al. is an obfuscation technique for protecting secret keys in software implementations even if an adversary has full access to the implementation of the encryption algorithm and full control over its execution platforms. Despite its practical importance, progress has not been substantial. In fact, it is repeated that as a proposal for a white-box implementation is reported, an attack of lower complexity is soon announced. This is mainly because most cryptanalytic methods target specific implementations, and there is no general attack tool for white-box cryptography. In this paper, we present an analytic toolbox on white-box implementations of the Chow et al.'s style using lookup tables. According to our toolbox, for a substitution-linear transformation cipher on n bits with S-boxes on m bits, the complexity for recovering the key obfuscated in the white-box implementation is O((3n/max(m(Q), m))2(3max(mQ,m)) + 2min {(n/m) L(m+3)2(2m), (n/m) L(3)2(3m) + n log L . 2(L/2)}), where m(Q) is the input size of nonlinear encodings, m(A) is the minimized block size of linear encodings, and L = lcm(m(A), m(Q)). As a result, a white-box implementation in the Chow et al.'s framework has complexity atmost O (min {(2(2m)/m) n(m+4), n log n.2(n/2) }), which is much less than 2(n). To overcome this, we introduce an idea that obfuscates two advanced encryption standard (AES)-128 ciphers at once with input/output encoding on 256 bits. To reduce storage, we use a sparse unsplit input encoding. As a result, our white-box AES implementation has up to 110-bit security against our toolbox, close to that of the original cipher. More generally, we may consider a white-box implementation of the t parallel encryption of AES to increase security.

关键词： Advanced encryption standard (AES) block cipher equivalence algorithm specialized affine white-box cryptography white-box implementation

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Short-term reliability evaluation of protection systems in smart substations based on equivalent state spaces following semi-Markov process

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第9期10卷 2225-2230页

作者： Li, Shenghu Hua, Yuting Hefei Univ Technol Sch Elect Engn & Automat Hefei 230009 Peoples R China

The reliability analysis of protection systems in smart substations helps to improve their designed functions, whose difficulty lies in the complex configuration with various components. To avoid the dimension disaster, the state spaces of the protection systems may be aggregated to several lumped states. When the states do not satisfy the balance criterion, it is newly found that the lumped states not following the Markov process introduce notable error to the short-term reliability. To avoid this, an equivalence algorithm based on the semi-Markov process (SMP) is newly proposed. It is derived that the residence time distributions of the lumped states are the weighted averages of the distributions of the states to be lumped. The kernel matrix of the SMP, the instantaneous probability, and its sensitivity, are derived from the transfer rates and distributions. The numerical results validate accuracy of the proposed algorithm, which shows that the traditional model underestimates the availability. It underestimates sensitivity of the time source (TS), while overestimates those of the others. The probabilities of the proposed algorithm are more sensitive to the TS, while those of the traditional model are more sensitive to the merging unit and the ethernet switch.

关键词： substation protection power system reliability Markov processes matrix algebra probability short-term reliability evaluation protection systems smart substations equivalent state spaces semi Markov process SMP residence time distributions lumped states kernel matrix instantaneous probability transfer rates time source sensitivity Ethernet switch merging unit equivalence algorithm

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A Comprehensive Methodology to Implement Business Intelligence and Analytics Through Knowledge Discovery in Databases 1

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6th International Conference on Mining Intelligence and Knowledge Exploration (MIKE)

作者： Belfo, Fernando Paulo Andreica, Alina Banca Polytech Inst Coimbra ISCAC Coimbra Business Sch Coimbra Portugal Babes Bolyai Univ Cluj Napoca Fac European Studies Cluj Napoca Romania

ISBN: (数字)9783030059187

ISBN: (纸本)9783030059187;9783030059170

Business intelligence is used by companies for analysing business information, providing not only historical or current views on business operations, but also providing predictions about the business. Consequently, knowledge discovery in databases can support the implementation of business intelligence solutions, especially in order to deal with the reality of big data, using diverse data mining techniques that can help to better prepare the data and to create improved models. The current paper proposes a methodology to implement business intelligence and analytics solutions, based on the CRISPDM methodology, where the application of simplification and equivalence algorithms in modelling data representations can be used for improving the process of business management. This promising approach can boost business intelligence and analytics by using alternative techniques for discovering and presenting new knowledge about the business. The application of simplification and equivalence algorithms within the business context enables finding the most comprehensive or relevant knowledge, represented for instance as association rules, and bringing a real competitive advantage for the stakeholders.

关键词： Business intelligence Knowledge discovery in databases Data mining equivalence algorithm Canonical representation

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WORST-CASE ANALYSIS OF SET UNION algorithmS

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JOURNAL OF THE ACM 1984年第2期31卷 245-281页

作者： TARJAN, RE VANLEEUWEN, J STATE UNIV UTRECHT DEPT COMP SCIUTRECHTNETHERLANDS

This paper analyzes the asymptotic worst-case running time of a number of variants of the well-known method of path compression for maintaining a collection of disjoint sets under union. We show that two one-pass methods proposed by van Leeuwen and van der Weide are asymptotically optimal, whereas several other methods, including one proposed by Rein and advocated by Dijkstra, are slower than the best methods. © 1984, ACM. All rights reserved.

关键词： equivalence algorithm inverse Aekermann's function set union

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Finding Dominators in Directed Graphs: 收藏
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引用; SIAM Journal on Computing 1974年第1期3卷 62-89页; 作者： Robert Tarjan; This paper describes an algorithm for finding dominators in an arbitrary directed graph. The algorithm uses depth-first search and efficient algorithms for computing disjoint set unions and manipulating priority queue... 详细信息; This paper describes an algorithm for finding dominators in an arbitrary directed graph. The algorithm uses depth-first search and efficient algorithms for computing disjoint set unions and manipulating priority queues to achieve a time bound of $O (V \log V + E)$; 来源：评论; 学校读者我要写书评

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Set Merging algorithms

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SIAM Journal on Computing 1973年第4期2卷 294-303页

作者： J. E. Hopcroft J. D. Ullman

This paper considers the problem of merging sets formed from a total of n items in such a way that at any time, the name of a set containing a given item can be ascertained. Two algorithms using different data structures are discussed. The execution times of both algorithms are bounded by a constant times $nG(n)$, where $G(n)$ is a function whose asymptotic growth rate is less than that of any finite number of logarithms of n.

关键词： algorithm algorithmic analysis computational complexity data structure equivalence algorithm merging property grammar set spanning tree

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Finding Minimum Spanning Trees

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SIAM Journal on Computing 1976年第4期5卷 724-742页

作者： David Cheriton Robert Endre Tarjan

This paper studies methods for finding minimum spanning trees in graphs. Results include 1. several algorithms with $O(m\log \log n)$ worst-case running times, where n is the number vertices and m is the number of edges in the problem graph; 2. an $O(m)$ worst-case algorithm for dense graphs (those for which m is $\Omega (n^{1 + \varepsilon } )$ for some positive constant $\varepsilon $); 3. an $O(n)$ worst-case algorithm for planar graphs; 4. relationships with other problems which might lead general lower bound for the complexity of the minimum spanning tree problem.

关键词： equivalence algorithm graph algorithm minimum spanning tree priority queue

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DATA-STRUCTURES AND algorithmS FOR DISJOINT SET UNION PROBLEMS

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COMPUTING SURVEYS 1991年第3期23卷 319-344页

作者： GALIL, Z ITALIANO, GF TEL AVIV UNIV DEPT COMP SCIIL-69978 TEL AVIVISRAEL UNIV ROME LA SAPIENZA DIPARTIMENTO INFORMAT & SISTEMISTI-00185 ROMEITALY

This paper surveys algorithmic techniques and data structures that have been proposed to solve the set union problem and its variants. The discovery of these data structures required a new set of algorithmic tools that have proved useful in other areas. Special attention is devoted to recent extensions of the original set union problem, and an attempt is made to provide a unifying theoretical framework for this growing body of algorithms.

关键词： equivalence algorithm PARTITION SET UNION TIME COMPLEXITY

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