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Keyframe Extraction and Process Recognition Method for Assembly Operation Based on Density Clustering

IEEE ACCESS 2023年 11卷 13564-13573页

作者： Liu, Yong Qiao, Qi Shi, Shengrui Wang, Xiang Yang, Mingshun Gao, Xinqin Xian Univ Technol Fac Mech & Precis Instrument Engn Xian 710048 Peoples R China

A keyframe extraction and process recognition method for assembly operations is proposed based on density clustering to solve the problems of data redundancy and difficulty in obtaining valid data frames from the process of continuous assembly operations. A standard operation gesture set, including dynamic and static actions, was constructed by decomposing the assembly operation. The finger feature variables and comprehensive gesture feature quantized function were defined according to the finger joint structure. Based on searching for local extreme points in the function, the density clustering method was used to extract the keyframes of the assembly operation sequence to eliminate redundant data. Finally, the support vector machine algorithm model and Levinstein distance were determined to complete the keyframe recognition and assembly operation matching. A case study demonstrated that the proposed method could effectively discretize the assembly operation sequence, remove approximately 84% of redundant data frames, and achieve a comprehensive recognition rate of 92%.

关键词： Clustering algorithms Support vector machines Assembly Process control Data mining Clustering methods Feature extraction approximation algorithms Assembly operation density clustering gesture recognition keyframe extraction SVM

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Analysis of Lofgren's Tonearm Optimization

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JOURNAL OF THE AUDIO ENGINEERING SOCIETY 2023年第1-2期71卷 53-61页

作者： Hickman, A. Peet Lehigh Univ Dept Phys Bethlehem PA 18015 USA

A rigorous proof is given of the new analytic formula recently presented by Jovanovic for the linear offset p in Lofgren C alignment. An alternate but mathematically equivalent form of this formula shows explicitly that p depends weakly on 1/L-2, where L is the effective length of the tonearm. Simplified derivations of several results for Lofgren A are also presented. Approximate formulas for Lofgren C valid in the limit of large L are derived, compared with accurate numerical calculations, and shown to be sufficiently accurate to account qualitatively for the optimum values of the tonearm parameters over a wide range of L.

关键词： approximation algorithms

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Sparse Recovery of Finite Alphabet Signals Using AMP and Its Application in DoA Estimation

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IEEE SYSTEMS JOURNAL 2023年第3期17卷 3730-3740页

作者： Eghbali, Yasoub Naeiny, Mahmoud Ferdosizade Shahed Univ Dept Elect & Elect Engn Tehran *** Iran

This study presents an approximate message passing (AMP)-based method for the reconstruction of sparse signals from multiple measurement vectors. Recently, Ziniel and Schniter have provided a general analysis of the AMP algorithm. They have assumed that the nonzero elements of the sparse signals have Gaussian distribution. This article extends their proposed method to the case that the nonzero elements of sparse vectors are chosen from a discrete finite alphabet. Therefore, the proposed algorithm is called approximate message passing with finite alphabet. Based on this assumption, the passing messages have been derived and the scheduling of the algorithm has been proposed using a three-step strategy. As an application, direction of arrival (DoA) estimation of digitally modulated signals is examined using simulations. The obtained results revealed that the proposed method would improve the DoA estimation accuracy compared to the conventional methods.

关键词： approximation algorithms Sparse matrices Estimation Message passing Direction-of-arrival estimation Gaussian distribution Finite element analysis Approximate message passing (AMP) factor graph finite alphabet sparse signal recovery

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Optimal distributed covering algorithms

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DISTRIBUTED COMPUTING 2023年第1期36卷 45-55页

作者： Ben-Basat, Ran Even, Guy Kawarabayashi, Ken-ichi Schwartzman, Gregory Univ Coll London UCL London England Tel Aviv Univ Tel Aviv Israel Natl Inst Informat Chiyoda City Japan JAIST Nomi Ishikawa Japan

We present a time-optimal deterministic distributed algorithm for approximating a minimum weight vertex cover in hypergraphs of rank f. This problem is equivalent to the Minimum Weight Set Cover problem in which the frequency of every element is bounded by f. The approximation factor of our algorithm is (f + epsilon). Let Delta denote the maximum degree in the hypergraph. Our algorithm runs in the congest model and requires O(log Delta/ log log Delta) rounds, for constants epsilon is an element of (0, 1] and f is an element of N+. This is the first distributed algorithm for this problem whose running time does not depend on the vertex weights nor the number of vertices. Thus adding another member to the exclusive family of provably optimal distributed algorithms. For constant values of f and e, our algorithm improves over the (f + epsilon)-approximation algorithm of Kuhn et al. (SODA, 2006)whose running time is O(log. + logW), where W is the ratio between the largest and smallest vertex weights in the graph. Our algorithm also achieves an f -approximation for the problem in O(f log n) rounds, improving over the classical result of Khuller et al. (J algorithms, 1994) that achieves a running time of O(f log(2) n). Finally, for weighted vertex cover (f = 2) our algorithm achieves a deterministic running time of O(log n), matching the randomized previously best result of Koufogiannakis and Young (Distrib Comput, 2011). We also show that integer covering-programs can be reduced to the MinimumWeight Set Cover problem in the distributed setting. This allows us to achieve an (f inverted right perpendicularlog(2)(M)+1inverted left perpendicular+ epsilon)-approximate integral solution in O ((1 + f / log n) . (log Delta/log log Delta + (f . log M)(1.01) . log epsilon(-1) . (log Delta)(0.01))) rounds, where f bounds the number of variables in a constraint, Delta bounds the number of constraints a variable appears in, and M = max {1, inverted left perpendicular1/a(min) inverted

关键词： Distributed algorithms approximation algorithms Vertex cover Set cover

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Platform-Oriented Event Time Allocation

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2023年第3期35卷 2930-2942页

作者： Sun, Heli Wang, Ning Jia, Jingyu Huang, Jianbin Xiong, Hui He, Liang Liu, Xinwang Zhang, Shan Qiao, Shaojie Zhao, Jizhong Xi An Jiao Tong Univ Sch Comp Sci & Technol Sch Journalism & New Media Xian 710049 Shananxi Peoples R China Xi An Jiao Tong Univ Sch Comp Sci & Technol Xian 710049 Shaanxi Peoples R China Xidian Univ Sch Comp Sci & Technol Xian 710071 Shaanxi Peoples R China Hong Kong Univ Sci & Technol Artificial Intelligence Thrust Guangzhou Guangdong Peoples R China Natl Univ Def Technol Sch Comp Changsha 410073 Hunan Peoples R China Chengdu Univ Informat Technol Chengdu 610225 Sichuan Peoples R China Xi An Jiao Tong Univ Sch Comp Sci & Technol Xian 710049 Shananxi Peoples R China

Online Event-based social networks (EBSNs), such as Meetup and Whova, which provide platforms for users to publish, arrange and participate in events, have become increasingly popular. A major challenge for managing EBSNs is to generate the most satisfactory event arrangement, i.e., events are scheduled at the reasonable time to attract maximum number of participants. Existing approaches usually focus on assigning a set of events organized to time intervals, but ignore the competitive relationships among different event organizers, which will lead to event time allocations unacceptable to organizers. Thus, a more intelligent EBSNs platform that allocates social events properly in a global view (i.e., the perspective of platform) is desired. In this paper, we first formally define the problem of Platform-oriented Event Time Allocation (PETA), which contains two parts: the prediction of event feasible time period and the event time allocation. Unfortunately, we find that the PETA problem is NP-hard due to the global conflict constraints on events. Thus, we propose a method to calculate event feasible time period based on event time prediction, and then design a greedy algorithm and two approximation algorithms to solve the PETA problem. Finally, we conduct extensive experiments on both real and synthetic datasets to test the effectiveness and efficiency of the proposed algorithms.

关键词： Resource management Social networking (online) approximation algorithms Prediction algorithms Computer science Optimization Organizations Social event arrangement social network platform-oriented approximation algorithms event time allocation

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Heuristic (S, T) Solutions via an FPTAS for a One-Warehouse Multiretailer Problem

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OPERATIONS RESEARCH 2025年第3期73卷 1151-1164页

作者： Najy, Waleed Diabat, Ali Elbassioni, Khaled NYU Abu Dhabi Div Engn Saadiyat Isl Abu Dhabi 129188 U Arab Emirates NYU Tandon Sch Engn Dept Civil & Urban Engn Brooklyn NY 11201 USA Coll Comp & Math Sci Comp Sci Dept Abu Dhabi 127788 U Arab Emirates

The difficulty of analyzing and optimizing the stochastic one-warehouse multiretailer problem under the (S, T) policy motivates the need to consider approximate but high-fidelity systems that are easier to scrutinize. We consider one such model in the setting in which retailers face independent normally distributed demand with given (nonidentical) means and variances. Safety stock is computed via a type-I service-level formula that ignores allocation issues, and the cost function is computed based on a power-of-two (POT) periodic ordering policy. A critical component of finding good solutions for this problem is solving the continuous relaxation of the optimization model involved. In doing so, the linking square root term introduced by the warehouse safety stock complicates this task as the cost does not decouple by individual retailers for a fixed warehouse replenishment interval. We alleviate this issue by substituting the linking term with an accurate piecewise linear estimator. We show how this helps us design a fully polynomial-time approximation scheme for the problem. From this, we can obtain a POT policy that has a guarantee of 1.061(1 + epsilon) for small epsilon and for any base planning period and 1.021(1 + epsilon) when the base planning period is optimally chosen, which is essentially the best possible guarantee up to the deterministic result. We show via an empirical study that the algorithm proposed returns heuristic (S, T) solutions that exhibit minimal suboptimality relative to the exact solution. Further, the time needed to compute these solutions is milliseconds for a handful of retailers (in contrast to the multiple hours required by the best existing methods) and just a few minutes for a system of one million retailers.

关键词： multiechelon stochastic demand piecewise linearization approximation algorithms inventory/production

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Replica Analysis of the Linear Model With Markov or Hidden Markov Signal Priors

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IEEE TRANSACTIONS ON INFORMATION THEORY 2023年第12期69卷 7953-7975页

作者： Truong, Lan V. Univ Cambridge Dept Engn Cambridge CB2 1PZ England

This paper estimates free energy, average mutual information, and minimum mean square error (MMSE) of a linear model under two assumptions: 1) the source is generated by a Markov chain;2) the source is generated via a hidden Markov model. Our estimates are based on the replica method in statistical physics. We show that under the posterior mean estimator, the linear model with Markov sources or hidden Markov sources is decoupled into single-input AWGN channels with state information available at both encoder and decoder where the state distribution follows the left Perron-Frobenius eigenvector with unit Manhattan norm of the stochastic matrix of Markov chains. Numerical results show that the free energies and MSEs obtained via the replica method are closely approximate to their counterparts achieved by the Metropolis-Hastings algorithm or some well-known approximate message passing algorithms in the research literature.

关键词： Hidden Markov models Markov processes Estimation approximation algorithms Mutual information Interpolation Compressed sensing linear model linear regression Markov chain hidden Markov model replica method free energy minimum mean square error statistical physics maximum a posteriori estimation

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Distributed Design of Wireless Powered Fog Computing Networks With Binary Computation Offloading

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2023年第4期22卷 2084-2099页

作者： Li, Han Xiong, Ke Lu, Yang Gao, Bo Fan, Pingyi Letaief, Khaled Ben Sch Comp & Informat Technol Beijing 100044 Peoples R China Beijing Key Lab Traff Data Anal & Min Beijing 100044 Peoples R China Beijing Jiaotong Univ Frontiers Sci Ctr Smart High Speed Railway Syst Beijing 100044 Peoples R China Beijing Natl Res Ctr Informat Sci & Technol Beijing 100084 Peoples R China Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Hong Kong Univ Sci & Technol HKUST Dept Elect & Comp Engn Hong Kong Peoples R China Pengcheng Lab Shenzhen 518055 Guangdong Peoples R China

This paper investigates a multi-user wireless powered fog computing (FC) network, where multiple energy-limited wireless sensor devices (WSDs) first harvest energy from a nearby hybrid access point (HAP), and then compute their tasks locally (i.e., the local computing (LC) mode) or offload the tasks to the HAP (i.e., the FC mode) via a binary offloading policy. In order to pursue the green computing network design, an optimization problem is formulated to minimize the transmit power at the HAP by jointly optimizing the time allocation ratio and the computing mode selection vector, under the energy causality constraints and the WSDs' computing rate requirements constraints. To efficiently solve the formulated non-convex problem in a distributed manner, it is first transformed into an approximate form, and then an alternating direction method of multipliers (ADMM)-based algorithm is designed to solve the transformed problem, based on which the successive convex approximation (SCA) is adopted to improve the approximating precision in an iterative way. With the proposed ADMM-based distributed algorithm, each WSD is able to optimize its computing mode and offloading time with local channel state information (CSI), which thus is more suitable for large-scale networks. For comparison, a channel-sorting-based (CSB) centralized algorithm with global CSI is also presented, and the computational complexities of the proposed ADMM-based algorithm and the CSB algorithm are analyzed. Simulation results show that the proposed distributed algorithm achieves a comparable performance with the CSB centralized algorithm and the exhaustive search method. It is also observed that to minimize the transmit power at the HAP, the WSDs with the better channel quality are inclined to select the LC mode, which is much different from traditional sum-computation-rate maximization design.

关键词： Wireless communication Task analysis Servers Optimization Distributed algorithms approximation algorithms Resource management Fog computing binary offloading wireless power transfer power minimization successive convex approximation alternating direction method of multipliers

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A Kernel-Based Real-Time Adaptive Dynamic Programming Method for Economic Household Energy Systems

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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS 2023年第3期19卷 2374-2384页

作者： Yuan, Jun Chen, Si-Zhe Yu, Samson S. S. Zhang, Guidong Chen, Zhe Zhang, Yun Guangdong Univ Technol Sch Automat Guangzhou 510006 Guangdong Peoples R China Deakin Univ Sch Engn Waurn Ponds Vic 3216 Australia Aalborg Univ Fac Engn & Sci DK-9220 Aalborg Denmark

Modern home energy management systems (HEMSs) have great flexibility of energy consumption for customers, but at the same time, bear a range of problems, such as the high system complexity, uncertainty and time-varying nature of load consumptions, and renewable sources generation. This has brought great challenges for the real-time control. To solve these problems, we propose an HEMS that integrates a kernel-based real-time adaptive dynamic programming (K-RT-ADP) with a new preprocessing short-term prediction technique. For the preprocessing short-term prediction, we propose a gated recurrent unit-bidirectional encoder representations from the transformer (GRU-BERT) model to improve the forecasting accuracy of electrical loads and renewable energy generation. In particular, we classify household appliances into the temperature-sensitive loads, human activity sensitive loads, and insensitive/constant loads. The GRU-BERT model can incorporate weather and human activity information to predict load consumption and solar generation. For real-time control, we propose and employ the K-RT-ADP HEMS based on the GRU-BERT prediction algorithm. The objective of the K-RT-ADP HEMS is to minimize the electricity cost and maximize the solar energy utilization. To enhance the nonlinear approximation ability and generalization ability of the adaptive dynamic programming (ADP) algorithm, the K-RT-ADP algorithm leverages kernel mapping instead of neural networks. Hardware-in-the-loop experiments demonstrate the superiority of the proposed K-RT-ADP HEMS over the traditional ADP control through comparison.

关键词： Prediction algorithms approximation algorithms Real-time systems Artificial neural networks Kernel Batteries Renewable energy sources Bidirectional encoder representations from transformer home energy management system (HEMS) kernel-based adaptive dynamic programming (ADP)

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On Hierarchies of Balanced Sequences

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IEEE TRANSACTIONS ON INFORMATION THEORY 2023年第5期69卷 2923-2939页

作者： Marcovich, Sagi Etzion, Tuvi Yaakobi, Eitan Technion Israel Inst Technol Dept Comp Sci IL-3200003 Haifa Israel

Balanced sequences and balanced codes have attracted a lot of research in the last seventy years due to their diverse applications in information theory as well as other areas of computer science and engineering. There have been some methods to classify balanced sequences. This work suggests two new different hierarchies to classify these sequences. The first one is based on the largest L for which each L-tuple is contained the same amount of times in the sequence. This property is a generalization for the property required for de Bruijn sequences. The second hierarchy is based on the number of balanced derivatives of the sequence. Enumeration for each such family of sequences and efficient encoding and decoding algorithms are provided in this paper.

关键词： Redundancy Encoding Symbols Indexes Ear approximation algorithms Time complexity Balanced sequences de Bruijn sequences de Bruijn graph Knuth's balancing algorithm derivatives of sequences

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