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Connectivity-Based Localization Scheme for Social Internet of Things

IEEE TRANSACTIONS ON computational SOCIAL SYSTEMS 2022年第6期9卷 1671-1681页

作者： Zhou, Mu Li, Yaohua Pu, Qiaolin Nie, Wei Wilford, Arigye Jiang, Qing Chongqing Univ Posts & Telecommun Sch Commun & Informat Engn Chongqing 400065 Peoples R China

Different from the social network which only focuses on the interaction between people, the integration of social networks and the internet of things (IoT) leads to multi-directional interactions of human to human, human to thing, and thing to thing. The social IoT is composed of a large number of heterogeneous devices, which can improve the scalability of resource and service. Meanwhile, the heterogeneous devices have uneven computing power and different location information measurement types (e.g., the distance, angle, and hop count). Therefore, a localization approach with easy-to-obtain measurement data and low requirements on the computing power is needed. In this article, we propose a localization approach for the social IoT by combining the fuzzy rough set theory and the ridge regression extreme learning machine (RRELM). First of all, a location fingerprint database is constructed. Different from the traditional location fingerprint database, the location fingerprint database here stores the minimum hop counts between the reference node (RN) and the anchor node (AN) instead of the received signal strength (RSS). Second, the fuzzy rough set theory is used to compute the significant degree of each AN, and the ANs that contribute little to the positioning result are removed. This approach not only relieves the storage pressure of the location fingerprint database but also reduces the computational complexity of user position estimation. Third, the RRELM is trained by using the samples in the location fingerprint database. Finally, by inputting the newly collected minimum hop counts from the user to each AN into the trained RRELM, the user's position is estimated. From the extensive experimental results, the proposed approach has high positioning accuracy and low computational complexity, which is suitable for the social IoT.

关键词： Location awareness Databases Training Rough sets Internet of Things Estimation computational complexity Extreme learning machine (ELM) fingerprint database fuzzy rough set localization social IoT

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Dimension Is Compression

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THEORY OF COMPUTING SYSTEMS 2013年第1期52卷 95-112页

作者： Lopez-Valdes, Maria Mayordomo, Elvira Univ Zaragoza Dept Informat & Ingn Sistemas Inst Invest Ingn Aragon I3A Zaragoza Spain

Effective fractal dimension was defined by Lutz (2003) in order to quantitatively analyze the structure of complexity classes. Interesting connections of effective dimension with information theory were also found, in fact the cases of polynomial-space and constructive dimension can be precisely characterized in terms of Kolmogorov complexity, while analogous results for polynomial-time dimension haven't been found. In this paper we remedy the situation by using the natural concept of reversible time-bounded compression for finite strings. We completely characterize polynomial-time dimension in terms of polynomial-time compressors.

关键词： computational complexity Information theory Effective dimension

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Joint Beamforming and Reflecting Elements Optimization for Segmented RIS Assisted Multi-User Wireless Networks

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2024年第3期73卷 3820-3831页

作者： Wang, Xiaoqing Zheng, Rui Du, Fei Zhao, Xiongwen Zhang, Yu Xu, Yunhe Geng, Suiyan Qin, Peng North China Elect Power Univ Sch Elect & Elect Engn State Key Lab Alternate Elect Power Syst Renewable Beijing 102206 Peoples R China Anhui Univ Informat Mat & Intelligent Sensing Lab Anhui Prov Hefei 230601 Peoples R China

The emerging reconfigurable intelligent surface (RIS) is a prospective technique to modulate the wireless channel and improve performance, in which large amounts of passive elements manipulate independently, inevitably resulting in a high-dimensional optimization problem that is intractable to solve. With the aim to strike a balance between optimality and complexity for RIS assisted multi-user systems, in this article, we formulate the achievable sum rate maximization problem under a novel RIS segmentation structure, where the distributions and sizes of each segmentation can be adaptively adjusted. Since the formulated optimization problem considering the quality of service (QoS) requirements for the users is non-convex, we suggest a computationally-efficient approach to derive an optimal solution by exploiting fractional programming, successive convex approximation (SCA), greedy algorithm, and alternating optimization. Finally, numerical simulations reveal that the proposed optimization design enables RIS to configure by grouping elements into some sub-surfaces without significant performance degradation while with much lower computational complexity than conventional element-wise optimization RIS. Moreover, our proposed adjustable segmentation outperforms the fixed one employing the determined positions and equal number of reflecting elements in each sub-surface. Additionally, the results demonstrate that the optimization of segmentation is much more significant than the phase shift optimization, showing the superiority and practical significance of the sub-surface segmentation strategy.

关键词： Optimization Channel estimation Array signal processing Quality of service Performance gain computational modeling computational complexity Multi-user networks reflecting phase shift optimization reconfigurable intelligent surface (RIS) assisted communication system sub-surface segmentation

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AN ANALYSIS OF THE IMPACT OF THE INITIAL SAMPLE ON EVOLUTIONARY METAMODEL-ASSISTED OPTIMIZATION

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APPLIED ARTIFICIAL INTELLIGENCE 2013年第8期27卷 669-699页

作者： Tenne, Yoel Ariel Univ Dept Mech & Mechatron Engn IL-40700 Ariel Israel

The modern engineering design process often employs computer simulations to evaluate candidate designs, a setup that results in computationally expensive black-box optimization problems. An established framework to solve such problems is with evolutionary metamodel-assisted algorithms, in which the metamodel provides the evolutionary algorithm with approximate function values at a lower computational cost when compared with the simulation. Such evolutionary optimizers require an initial sample of points, which are then used to train an initial metamodel and to enable the main optimization search. This setup implies that the initial sample can significantly impact the effectiveness of the optimization search. Two main approaches for generating the initial sample are statistical sampling, in which the sample points are generated by sampling a statistical distribution, and the more recent search-based sampling, which uses a population-based algorithm to generate the sample points. Leveraging on the importance of the initial sample, this study presents a detailed comparison of methods for generating the initial sample, and analyzes in detail their impact on the evolutionary metamodel-assisted search in a variety of optimization scenarios. It concludes with a set of recommendations for selection of the sampling method.

关键词： ENGINEERING design MATHEMATICAL optimization PROBLEM solving MATHEMATICAL models COMPUTER simulation computational complexity EVOLUTIONARY algorithms

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Efficient two-level interior point method for optimal pumped hydrostorage scheduling exploiting the nonsparse matrix structure

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IEE PROCEEDINGS-GENERATION TRANSMISSION AND DISTRIBUTION 2001年第1期148卷 41-47页

作者： Wu, YC Natl Lien Ho Inst Technol Dept Elect Engn Miao Li 360 Taiwan

The primal-dual interior point method (PDIPM) has proven to be an efficient tool for power system optimisation problems. Its computational efficiency heavily relies on sparsity techniques. Hence, when optimisation problems cannot be formulated into sparse form, PDIPM then may not be the right choice for these problems, because the computational efficiency drops significantly in factorisation of a dense matrix. A nonsparse power-system optimisation problem containing either-or constraints, pumped hydrostorage (PHS) scheduling, is presented and a two-level predictor-corrector version of PDIPM (PCPDIPM) is proposed to cope with this nonsparse and NP-hard problem. To overcome the difficulty associated with the dense matrix structure, a special data transformation is proposed. By further exploiting the dense matrix structure, the performance of PCPDIPM is not deteriorated by the nonsparse structure. On the contrary, the computational efficiency is dramatically improved due to exploiting this structure. Moreover, to solve the difficulty associated with either-or constraints, an effective two-level LP procedure is proposed. To illustrate the performance of the proposed methodology, numerical results are carried out on two test cases. These results show that the presented two-level PCPDIPM solves the pHS scheduling effectively.

关键词： dense matrix factorisation optimisation computational complexity Power systems nonsparse problem Optimisation techniques either-or constraints matrix algebra Algebra sparsity techniques Pumped storage stations and plants two-level LP procedure NP hard problem data transformation two-level interior point method nonsparse power-system optimisation power generation scheduling pumped-storage power stations nonsparse matrix structure dense matrix structure power system optimisation computational efficiency optimal pumped hydrostorage scheduling

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ON THE NUMBER OF LINEAR PARTITIONS OF THE (M, N)-GRID

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INFORMATION PROCESSING LETTERS 1991年第3期38卷 163-168页

作者： ACKETA, DM ZUNIC, JD UNIV NOVI SAD FAC ENGN INST APPL BASIC DISCIPLINES YU-21000 NOVI SAD YUGOSLAVIA

A relationship between linear partitions and minimal pairs of a finite point set in the plane was established in [2]. This relationship is used here for counting the number of linear partitions of the set of points of the (m, n)-grid, a rectangular part of the infinite grid. In order to optimize this counting, an O(mn) algorithm is introduced for traversing all those pairs (i, j) of mutually simple natural numbers i and j, such that 1 less-than-or-equal-to i less-than-or-equal-to m, 1 less-than-or-equal-to j less-than-or-equal-to n.

关键词： computational GEOMETRY computational complexity LINEAR PARTITIONS POINT SETS (M,N)-GRIDS IN THE PLANE

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Phoneme-based vector quantization in a discrete HMM speech recognizer

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IEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING 1997年第1期5卷 26-32页

作者： Zhang, YX Togneri, R Alder, M Motorola Australian Research Centre Botany NSW Australia Department of Electrical Engineering University of Western Australia Perth Australia Department of Mathematics University of Western Australia Perth Australia

The quantization distortion of vector quantization (VQ) is a key element that affects the performance of a discrete hidden Markov modeling (DHMM) system. Many researchers have realized this problem and tried to use integrated feature or multiple codebook in their systems to offset the disadvantage of the conventional VQ, However the computational complexity of those systems is then increased. Investigations have shown that the speech signal space consists of finite clusters that represent phoneme data sets from male and female speakers and reveal Gaussian distributions. In this paper we propose an alternative VQ method in which the phoneme is treated as a cluster in the speech space and a Gaussian model is estimated for each phoneme. A Gaussian mixture model (GMM) is generated by the expectation-maximization (EM) algorithm for the whole speech space and used as a codebook in which each code word is a Gaussian model and represents a certain cluster. An input utterance would be classified as a certain phoneme or a set of phonemes only when the phoneme or phonemes gave highest likelihood. A typical discrete HMM system was used for both phoneme and isolated word recognition. The results show that the phoneme-based Gaussian modeling vector quantization classifies the speech space more effectively and significant improvements in the performance of the DHMM system have been achieved.

关键词： Vector quantization Hidden Markov models Speech recognition Partitioning algorithms computational efficiency Australia Associate members computational complexity Gaussian distribution Clustering algorithms

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Nondeterministic stack register machines

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THEORETICAL COMPUTER SCIENCE 1997年第1-2期178卷 37-76页

作者： Clote, P Institut für Informatik Ludwig-Maximilians-Universität München Theresienstr. 39 D-80333 München Germany

For integer k greater than or equal to O, let sRM(n(O(1)),k) denote the collection of relations computable by a stack register machine with stack registers bounded by a polynomial p(n) in the input n, and work registers bounded by k. Let NsRM(n(O(1)),k) denote the analogous class accepted by nondeterministic stack register machines. In this paper, nondeterminism is shown to provide no additional power. Specifically, NSRM(n(O(1)),0) = SRM(n(O(1)),0), NSRM(n(O(1)),1) = SRM(n(O(1)),1), NSRM(n(O(1)),k) = SRM(n(O(1)),k), for k greater than or equal to 4, SRM(n(O(1)),k) = ALMTIME, for k greater than or equal to 4.

关键词： computational complexity

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On the complexity of Pure-Strategy Nash Equilibria in Congestion and Local-Effect Games

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MATHEMATICS OF OPERATIONS RESEARCH 2008年第4期33卷 851-868页

作者： Dunkel, Juliane Schulz, Andreas S. MIT Ctr Operat Res Cambridge MA 02139 USA MIT Alfred P Sloan Sch Management Cambridge MA 02139 USA

Rosenthal's congestion games constitute one of the few known classes of noncooperative games possessing pure-strategy Nash equilibria. In the network version, each player wants to route one unit of flow on a single path from her origin to her destination at minimum cost, and the cost of using an arc depends only on the total number of players using that arc. A natural extension is to allow for players controlling different amounts of flow, which results in so-called weighted congestion games. While examples have been exhibited showing that pure-strategy Nash equilibria need not exist anymore, we prove that it is actually strongly NP-hard to determine whether a given weighted network congestion game has a pure-strategy Nash equilibrium. This is true regardless of whether flow is unsplittable or not. In the unsplittable case, the problem remains strongly NP-hard for a fixed number of players. In addition to congestion games, we provide complexity results on the existence and computability of pure-strategy Nash equilibria for the closely related family of bidirectional local-effect games. Therein, the cost of a player taking a particular action depends not only on the number of players choosing the same action, but also on the number of players settling for (locally) related actions.

关键词： noncooperative games pure-strategy Nash equilibria computational complexity congestion games local-effect games

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A Metric Between Probability Distributions on Finite Sets of Different Cardinalities and Applications to Order Reduction

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2012年第10期57卷 2464-2477页

作者： Vidyasagar, Mathukumalli Univ Texas Dallas Erik Jonsson Sch Engn & Comp Sci Richardson TX 75080 USA

In this paper we define a metric distance between probability distributions on two distinct finite sets of possibly different cardinalities. The metric is defined in terms of a joint distribution on the product of the two sets, which has the two given distributions as its marginals, and has minimum entropy. Computing the metric exactly turns out to be NP-hard. Therefore an efficient greedy algorithm is presented for finding an upper bound on the distance. We then study the problem of optimal order reduction in the metric defined here. It is shown that every optimal reduced-order approximation must be an aggregation of the original distribution, and that optimal reduced order approximation is equivalent to finding an aggregation with maximum entropy. This problem also turns out to be NP-hard, so again a greedy algorithm is constructed for finding a suboptimal reduced order approximation. Taken together, all the results presented here permit the approximation of an independent and identically distributed (i.i.d.) process over a set of large cardinality by another i.i.d. process over a set of smaller cardinality. In future work, attempts will be made to extend this work to Markov processes over finite sets.

关键词： computational complexity entropy greedy algorithms mutual information probability distributions

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