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Hybrid Approaches based on Simulated Annealing, Tabu Search and Ant Colony Optimization for Solving the k-Minimum Spanning Tree Problem

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INTERNATIONAL JOURNAL OF ADVANCED COMPUTER SCIENCE AND APPLICATIONS 2021年第2期12卷 708-712页

作者： Addou, El Houcine Serghini, Abelhafid Mermri, El Bekkaye Mohammed I Univ LANO Lab FSO ESTO BV Mohamed VI BP 717 Oujda 60000 Morocco Mohammed I Univ FSO BV Mohamed VI BP 717 Oujda 60000 Morocco

In graph theory, the k-minimum spanning tree problem is considered to be one of the well-known NP hard problems to solve. This paper address this problem by proposing several hybrid approximate approaches based on the combination of simulated annealing, tabu search and ant colony optimization algorithms. The performances of the proposed methods are compared to other approaches from the literature using the same well-known library of benchmark instances.

关键词： k-Minimum spanning tree metaheuristics simulated annealing ant colony optimization algorithms tabu search approximation algorithms

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Polytope-Based Flexible Aggregation and Disaggregation Strategy for Electric Vehicles

Polytope-Based Flexible Aggregation and Disaggregation Strat...

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IEEE International Conference on Industrial Technology (ICIT)

作者： Hongyu Zou Wenyu Gao Yifan Zhang Jiawei Xia Zhi-Wei Liu College of Artificial Intelligence and Automation Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9798331521950

ISBN: (纸本)9798331521967

The substantial rise in the number of electric vehicles (EVs) presents both challenges and opportunities for the grid. EVs can participate in demand response as aggregators, thereby providing a variety of ancillary services, including peaking and frequency regulation. The study of EV cluster aggregation is of significant importance. In this paper, we put forward an aggregation and disaggregation algorithm for EV aggregators that is suitable for the accurate aggregation of flexible large-scale clusters with different charging time. The aggregation is conducted by modeling the flexibility as a polytope and describing the aggregatied value in terms of the approximate Minkowski sum. The disaggregation considers the regulation cost and user satisfaction of individual EVs while ensuring the security of the regulation commands. Simulation experiments demonstrate the effectiveness and convenience of this method.

关键词： Costs Accuracy Clustering algorithms Electric vehicles approximation algorithms Regulation Demand response Security Frequency control

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Exclusion Zones of Instant Runoff Voting

arXiv

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arXiv 2025年

作者： Tomlinson, Kiran Ugander, Johan Kleinberg, Jon Microsoft Research United States Stanford University United States Cornell University United States

Recent research on instant runoff voting (IRV) shows that it exhibits a striking combinatorial property in one-dimensional preference spaces: there is an exclusion zone around the median voter such that if a candidate from the exclusion zone is on the ballot, then the winner must come from the exclusion zone. Thus, in one dimension, IRV cannot elect an extreme candidate as long as a sufficiently moderate candidate is running. In this work, we examine the mathematical structure of exclusion zones as a broad phenomenon in more general preference spaces. We prove that with voters uniformly distributed over any d-dimensional hyperrectangle (for d > 1), IRV has no nontrivial exclusion zone. However, we also show that IRV exclusion zones are not solely a one-dimensional phenomenon. For irregular higher-dimensional preference spaces with fewer symmetries than hyperrectangles, IRV can exhibit nontrivial exclusion zones. As a further exploration, we study IRV exclusion zones in graph voting, where nodes represent voters who prefer candidates closer to them in the graph. Here, we show that IRV exclusion zones present a surprising computational challenge: even checking whether a given set of positions is an IRV exclusion zone is NP-hard. We develop an efficient randomized approximation algorithm for checking and finding exclusion zones. We also report on computational experiments with exclusion zones in two directions: (i) applying our approximation algorithm to a collection of real-world school friendship networks, we find that about 60% of these networks have probable nontrivial IRV exclusion zones;and (ii) performing an exhaustive computer search of small graphs and trees, we also find nontrivial IRV exclusion zones in most graphs. While our focus is on IRV, the properties of exclusion zones we establish provide a novel method for analyzing voting systems in metric spaces more generally. Copyright © 2025, The Authors. All rights reserved.

关键词： approximation algorithms

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Permutation Optimization Using Multivariate Dependent Estimation of Distribution Algorithm

Permutation Optimization Using Multivariate Dependent Estima...

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Computational Intelligence for Energy, Transport and Environmental Sustainability (CIETES Companion), IEEE Symposia on

作者： Yuyang Guo Chu-ge Wu Zhuo Li Yuanqing Xia BIT-BMSTU Joint School Beijing Institute of Technology Beijing China School of Automation Beijing Institute of Technology Beijing China

ISBN: (数字)9798331519681

ISBN: (纸本)9798331519698

Permutation optimization is essential in various fields, such as task scheduling, path planning. Considering the exploration ability of Estimation of Distribution algorithms (EDAs), a multivariate dependent EDA (MEDA) is proposed in this paper. In MEDA, a probability model is designed and utilized that describes the relative position of the variables. Two local enhancement operators, including swap and insertion, are designed to improve the quality of the permutations. These operators are instrumental in refining the permutation and approximating optimal solutions. The algorithm's performance is benchmarked against existing EDAs developed for permutation optimization, including the Histogram-based Sampling Algorithm, Random Key-based EDA, Multi-objective Markov Network based EDA and Bayesian Optimization-based Algorithm, demonstrating MEDA's superiority in computational efficiency and good performance. Experiments on traveling salesman problems highlight MEDA's ability to reduce computational complexity and shorten execution time, making it a viable alternative for handling large-scale permutation challenges across various domains.

关键词： Heuristic algorithms Instruments Scalability Refining Estimation Traveling salesman problems approximation algorithms Robustness Optimization Markov random fields

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Algorithm-Hardware Co-Design of a Unified Accelerator for Non-Linear Functions in Transformers

Algorithm-Hardware Co-Design of a Unified Accelerator for No...

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Design, Automation and Test in Europe Conference and Exhibition

作者： Haonan Du Chenyi Wen Zhengrui Chen Li Zhang Qi Sun Zheyu Yan Cheng Zhuo Zhejiang University Hubei University Of Technology

ISBN: (数字)9783982674100

ISBN: (纸本)9798331534646

Nonlinear functions (NFs) in Transformers require high-precision computation consuming significant time and energy, despite the aggressive quantization schemes for other components. Piece-wise Linear (PWL) approximation-based methods offer more efficient processing schemes for NFs but fall short in dealing with functions with high nonlinearities. Moreover, PWL-based methods still suffer from inevitably high latency introduced by the Multiply-And-Add (MADD) unit. To address these issues, this paper proposes a novel quadratic approximation scheme and a highly integrated, multiplier-less hardware structure, as a unified method to accelerate any unary nonlinear function. We also demonstrate implementation examples for GELU, Softmax, and LayerNorm. The experimental results show that the proposed method achieves up to 5.41% higher inference accuracy and 60.12% lower area-delay product.

关键词： Accuracy Quantization (signal) Computational modeling Europe Life estimation Transformers approximation algorithms Hardware Inference algorithms Integrated circuit modeling

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Accuracy Improvement of Ray-Tracing-Based Received Power Prediction in Office Environments

Accuracy Improvement of Ray-Tracing-Based Received Power Pre...

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European Conference on Antennas and Propagation, EuCAP

作者： Azril Haniz Hirokazu Sawada Takeshi Matsumura Wireless Sytems Laboratory National Institute of Information and Communications Technology (NICT) Yokosuka Kanagawa Japan

ISBN: (数字)9788831299107

ISBN: (纸本)9798350366327

Ray-tracing (RT) generally suffers from errors in the calculated received power especially at low frequencies where objects may be on the same order or smaller than the wavelength due to the high-frequency approximation used. Previously, an algorithm to reduce this error by attenuating the calculated received power depending on the object size with respect to wavelength was proposed and evaluated in an industrial environment. In this paper, we verified that the proposed algorithm can be applied not only to industrial environments but also to other environments such as office environments. The adjusted received power was compared with measured received power at 922 MHz, 4850 MHz, and 28.35 GHz bands taken in an office environment. Results show that the proposed algorithm could reduce the RMSE of received power calculated by RT from 14.1 dB, 7.5 dB, and 4.1 dB to 9.0 dB, 5.3 dB, and 3.7 dB for each frequency, respectively.

关键词： Power measurement Accuracy 5G mobile communication Wavelength measurement Ray tracing Attenuation measurement Size measurement Prediction algorithms approximation algorithms Frequency measurement

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Quaternionic Minkowski Reduction and Its Application in Dual-Polarized MIMO Systems

Quaternionic Minkowski Reduction and Its Application in Dual...

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International ITG Conference on Source and Channel Coding (SCC)

作者： Sebastian Stern Cong Ling Cornelia Ott Robert F.H. Fischer Institute of Communications Engineering Ulm University Germany Department of Electrical and Electronic Engineering Imperial College London United Kingdom Institute of Communications and Navigation German Aerospace Center (DLR) Germany

ISBN: (数字)9798331522896

ISBN: (纸本)9798331522902

The task of finding the shortest vectors of a lattice that form a basis thereof is known as Minkowski reduction. In this work, Minkowski reduction is adapted to discrete subgroups of quaternionic spaces defined over the set of Hurwitz integers which constitutes a Euclidean subring of the (Hamilton) quaternions. Based on a quaternionic variant of Minkowski's greatest-common-divisor condition for suitable lattice vectors, a lattice-basis-reduction algorithm is derived. To that end, a basisupdate approach is presented which takes the non-commutativity of quaternionic multiplication into account. The reduction algorithm is finally applied in multi-user multiple-input/multipleoutput (MIMO) systems with dual-polarized antennas, where the quaternionic interference is handled by lattice-reduction-aided equalization. It is shown that quaternionic Minkowski reduction achieves significantly better results than state-of-the-art Lenstra-Lenstra-Lovász (LLL) reduction and that the successive minima of quaternionic lattices are approximated quite well.

关键词： Quaternions Lattices Interference approximation algorithms Vectors MIMO Encoding Antennas

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Algorithm Design for Continual Learning in IoT Networks

Algorithm Design for Continual Learning in IoT Networks

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Shugang Hao Lingjie Duan Pillar of Engineering Systems and Design Singapore University of Technology and Design

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Continual learning (CL) is a new online learning technique over sequentially generated streaming data from different tasks, aiming to maintain a small forgetting loss on previously-learned tasks. Existing work focuses on reducing the forgetting loss under a given task sequence. However, if similar tasks continuously appear to the end time, the forgetting loss is still huge on prior distinct tasks. In practical IoT networks, an autonomous vehicle to sample data and learn different tasks can route and alter the order of task pattern at increased travelling cost. To our best knowledge, we are the first to study how to opportunistically route the testing object and alter the task sequence in CL. We formulate a new optimization problem and prove it NP-hard. We propose a polynomial-time algorithm to achieve approximation ratios of $\frac{3}{2}$ for underparameterized case and $\frac{3}{2} + {r^{1 - T}}$ for overparameterized case, respectively. Simulation results verify our algorithm’s close-to-optimum performance.

关键词： Continuing education Costs Simulation Signal processing algorithms Signal processing approximation algorithms Polynomials Speech processing Optimization Testing

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Detection and Cancellation of Multiplicative FDI Attack on Bilateral Encrypted Control System in Variable Periodic Motion

Detection and Cancellation of Multiplicative FDI Attack on B...

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IEEE/SICE International Symposium on System Integration

作者： Katsumasa Kosha Tetsuro Miyazaki Kaoru Teranishi Kiminao Kogiso Kenji Kawashima Department of Information Physics and Computing The University of Tokyo Tokyo Japan Oden Institute for Computational Engineering and Sciences The University of Texas at Austin Austin Texas USA Japan Society for the Promotion of Science Tokyo Japan Department of Mechanical and Intelligent Systems Engineering The University of Electro-Communications Tokyo Japan

ISBN: (数字)9798331531614

ISBN: (纸本)9798331531621

Teleoperation of remote assist robots has recently advanced owing to the development of communication technology. However, anonymous malicious attacks may intercept or falsify the network control system. Therefore, it is necessary to improve the security against cyber-attacks. As a countermeasure, an encrypted control method has been applied to prevent intercepting and detect the falsification of control parameters, as well as control signals by performing control operations with encrypted signals and parameters. Furthermore, we have proposed the algorithm to detect and restore the attack exploiting a vulnerability of encryption, which falsifies the plaintext by multiplying a constant factor. However, the algorithm is only effective for periodic motions with a fixed operating frequency and amplitude. If the frequency or amplitude of the motion is smaller than those of the base motion, the algorithm cannot detect the attack. To solve the problem, we propose an improved algorithm to detect and restore the attack in periodic motion with variable operating frequency and amplitude. In the proposed method, the operating frequency and amplitude are obtained through the position frequency analysis. They contribute to update the base energy, which is the average energy of corresponding periodic motion. We verified the proposed method for the bilateral control system using ElGamal encryption and experimentally confirmed its effectiveness against the FDI attack in various periodic motion.

关键词： Networked control systems System integration Cyber-physical systems approximation algorithms Polynomials Encryption Usability Robots Frequency control Cyberattack

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Weighted Sum-Rate Maximization for Large-Scale RIS-Assisted Multi-User MISO Systems

Weighted Sum-Rate Maximization for Large-Scale RIS-Assisted ...

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IEEE Conference on Wireless Communications and Networking

作者： Eduard E. Bahingayi Nemanja Stefan Perović Le-Nam Tran School of Electrical and Electronic Engineering University College Dublin Ireland Laboratoire des Signaux et Systèmes Universite Paris-Saclay CentraleSupélec France

ISBN: (数字)9798350368369

ISBN: (纸本)9798350368376

We present a low-complexity algorithm for jointly designing active and passive beamforming to maximize the weighted sum-rate (WSR) in downlink RIS-assisted communication systems. We exploit an equivalent, lower-dimensional reformulation of the WSR maximization problem to derive a closed-form solution for active beamforming optimization using the successive convex approximation (SCA) framework. For passive beamforming, we propose a scaled projected gradient method (SPGM) algorithm and a novel line search technique to improve performance. Notably, we demonstrate that the complexity of the proposed method scales linearly with the number of BS antennas and RIS reflective elements. Extensive numerical experiments demonstrate that our proposed algorithm significantly reduces both run time and computational complexity, while enhancing WSR performance over known benchmarks.

关键词： Closed-form solutions Array signal processing Search methods Reconfigurable intelligent surfaces Downlink approximation algorithms Reflector antennas Reflection Computational complexity Optimization

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