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SAR Imaging Based on Deep Unfolded Network With Approximated Observation

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2022年 60卷

作者： Kang, Le Sun, Tianchi Luo, Ying Ni, Jiacheng Zhang, Qun Air Force Engn Univ Inst Informat & Nav Xian 710077 Peoples R China Collaborat Innovat Ctr Informat Sensing & Underst Xian 710077 Peoples R China Fudan Univ Key Lab Informat Sci Electromagnet Waves Minist Educ Shanghai 200433 Peoples R China

Compressed sensing (CS)-based synthetic aperture radar (SAR) imaging methods are showing superior potential in imaging performance over classical matched filtering-based methods. However, the CS-based methods require much more computational cost to solve the iterative optimization composed of large-scale matrix operators. To hold the improvement of imaging performance and reduce the computational cost, in this article, we propose a novel SAR imaging method by a deep unfolded network (DUN) of an iterative shrinkage threshold algorithm (ISTA) with the approximated observation of a range-Doppler algorithm (RDA) operator. The proposed method takes the radar echoes as the input to learn the imaging procedure. First, the approximated observation is utilized in an SAR imaging model to reduce the size of the DUN. Moreover, we use ISTA as an example to introduce how to establish DUN with approximated observation, in which the detailed structure to handle the complex-valued radar echoes is also designed. Finally, the autoencoder is utilized to calculate the difference of the echoes rather than the imaging results, so that we can train the proposed network by unsupervised learning. The experiments of point targets, surface targets, and real scenes show that the proposed imaging method is superior in terms of imaging performance and computing efficiency.

关键词： Radar polarimetry Radar imaging Imaging Synthetic aperture radar Radar Signal processing algorithms approximation algorithms Approximated observation deep unfolded network (DUN) iterative shrinkage threshold algorithm (ISTA) Kronecker decomposition synthetic aperture radar (SAR) imaging

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Remove Minimum (RM): An Error-Tolerant Scheme for Cardinality Estimate by HyperLogLog

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IEEE TRANSACTIONS ON DEPENDABLE AND SECURE COMPUTING 2022年第2期19卷 966-977页

作者： Reviriego, Pedro Martinez, Jorge Rottenstreich, Ori Liu, Shanshan Lombardi, Fabrizio Univ Carlos III Madrid Madrid 28911 Spain Univ Antonio Nebrija Madrid 28040 Spain Technion Dept Comp Sci IL-3200003 Haifa Israel Technion Dept Elect Engn IL-3200003 Haifa Israel Northeastern Univ Dept Elect & Comp Engn Boston MA 02115 USA

Estimating the number of distinct elements is required in many computing applications. For example, we may want to estimate the number of unique users accessing a service, or the number of different words in a text. This problem is known as count distinct or cardinality estimate and has been widely studied. An accurate naive approach is to keep a list of distinct elements and for each upcoming one check such list and add it when it is not found. However, this is not practical for large cardinalities because it would require storing a large number of elements. Over the years, many algorithms have been proposed to provide cardinality estimates without storing elements and using less memory. One of the state-of-the-art algorithms for cardinality estimate is the HyperLogLog (HLL);it provides a good estimate over a large range of cardinality values using a small array of counters. As HLL is implemented in computing systems, it is exposed to soft errors that can corrupt bits stored in memories or registers. To avoid data corruption, memories are commonly protected with Error Correction Codes (ECCs). ECCs however incur in significant overhead because protection needs additional memory cells per word to store the parity check bits as well as additional computation for checking them. For achieving data protection, an alternative approach that can be of low-overhead exploits features of the implemented algorithms to detect and correct errors. In other scenarios, the algorithm must be executed on a system that is not protected with parity or ECCs and thus protection must be implemented at the algorithmic level. In this article, we first study the impact of soft errors on the HLL algorithm by performing simulation by error injection. The results show that the algorithm is quite robust and can filter out most errors. However, for large cardinalities, there are some errors that can cause a large discrepancy in the HLL estimate. This occurs when the uppermost bit with a value of o

关键词： Registers Radiation detectors Signal processing algorithms Memory management Arrays Electronic mail approximation algorithms Cardinality soft errors HyperLogLog error tolerance

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Static Timing Analysis for Single-Flux-Quantum Circuits Composed of Various Gates

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IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 2022年第5期32卷 1页

作者： Kawaguchi, Takahiro Takagi, Kazuyoshi Takagi, Naofumi Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan Mie Univ Grad Sch Engn Tsu Mie 5148507 Japan

Superconductive single-flux-quantum (SFQ) circuits operate with very high clock frequency and its timing design is a difficult task. In circuit design, static timing analysis (STA) is a key process for evaluating and verifying the timing of a circuit design. Conventional timing analysis for SFQ circuits focuses on circuits composed of clocked gates and splitters;however, practical SFQ circuits are composed of various gates, i.e., not only clocked gates but also other gates, such as nondestructive read-out, confluence buffer, and clockless logic gates. In this article, to express timing constraints of both clocked gate cells and other cells, we define timing requirements of cells as minimum and maximum acceptable intervals on ordered pairs of input pins. Via these, we express timing constraints of cells in an SFQ circuit design. Furthermore, to eliminate unnecessary pessimism during variation-aware timing analysis, we propose a method of common path pessimism removal (CPPR) for SFQ circuits composed of various cells. We implement an STA tool using the defined timing constraints and the CPPR method. The experimental results show that our STA tool verifies the timing of SFQ circuits composed of various cells.

关键词： Timing Pins Logic gates Clocks Delays Circuit synthesis approximation algorithms Clockless logic gates common path pessimism removal (CPPR) confluence buffer (CB) single-flux-quantum (SFQ) circuit static timing analysis (STA) nondestructive read-out (NDRO)

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Improved Approximate Expectation Propagation Massive MIMO Detector with Second-Order Richardson Iteration

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WIRELESS COMMUNICATIONS & MOBILE COMPUTING 2022年第0期2022卷

作者： Deng, Qian Chen, Xuehui Fu, Wanting Liang, Xiaopeng Xie, Shilong Shu, Feng Wu, Yuan Yuan Hainan Univ Coll Informat & Commun Engn Haikou 570228 Hainan Peoples R China Gannan Univ Sci & Technol Ganzhou 341000 Peoples R China

The expectation propagation (EP) detector achieves significantly better performance than the linear detectors (such as minimum mean squared error detector) in massive MIMO systems, which has drawn great attention recently. EP's approximation (EPA) algorithm simplifies the update formula of the EP algorithm by reexpressing the moment matching condition so that the number of matrix inversions in the EP algorithm is reduced to one. However, the expense is that the EPA algorithm requires higher accuracy for this inversion;otherwise, the bit-error-rate (BER) performance will suffer serious losses. To tackle this issue, the SORI iterative algorithm is introduced to obtain the high-precision result of this inversion to ensure the good BER performance of the EPA algorithm. First, the new expression of the SORI iterative algorithm is derived under the equivalent real-valued system. Second, the improved EPA-SORI algorithm is then introduced by the SORI algorithm, which is used to approximate the initial value of the EPA algorithm under the real-valued system. Finally, by designing the initial solution and the relaxation factor of the EPA-SORI iterative algorithm, the convergence rate can be quickly increased without increasing the complexity. Simulation and complexity results exhibit that in various massive MIMO system configurations, the proposed EPA-SORI algorithm can achieve the same BER performance as the Exact EP algorithm with significantly lower complexity. At the same time, compared with MMSE and the existing EPA algorithms, the proposed EPA-SORI algorithm has a better performance-complexity trade-off advantage, which is more obvious in scenarios with high modulation order and a large number of users.

关键词： approximation algorithms

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Mobility-Aware and Delay-Sensitive Service Provisioning in Mobile Edge-Cloud Networks

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2022年第1期21卷 196-210页

作者： Ma, Yu Liang, Weifa Li, Jing Jia, Xiaohua Guo, Song Australian Natl Univ Res Sch Comp Sci Canberra ACT 2601 Australia City Univ Hong Kong Dept Comp Sci Kowloon 83 Tat Chee Ave Hong Kong Peoples R China Hong Kong Polytech Univ Hong Kong Peoples R China

Mobile edge computing (MEC) has emerged as a promising technology to push the cloud frontier to the network edge, provisioning network services in proximity of mobile users. Serving users at edge clouds can reduce service latency, lower operational cost, and improve network resource availability. Along with the MEC technology, network function virtualization (NFV) is another promising technique that implements various network service functions as pieces of software in cloudlets (servers or clusters of servers). Providing virtualized network service for mobile users can improve user service experience, simplify network service deployment, and ease network resource management. However, mobile users move in networks arbitrarily, and different users usually request different services with different resource demands and delay requirements. It thus poses a great challenge to providing reliable and seamless virtualized network services for mobile users in an MEC network while meeting their individual delay requirements, subject to resource capacities on the network. In this paper, we focus on the provisioning of virtualized network function services for mobile users in MEC that takes into account user mobility and service delay requirements. We first formulate two novel optimization problems of user service request admissions with the aims to maximize the accumulative network utility and accumulative network throughput for a given time horizon, respectively. We then devise a constant approximation algorithm for the utility maximization problem. We also develop an online algorithm for the accumulative throughput maximization problem. We finally evaluate the performance of the proposed algorithms through experimental simulations. Experimental results demonstrate that the proposed algorithms are promising.

关键词： Cloud computing approximation algorithms Delays Mobile computing Mobile handsets Prediction algorithms Servers Mobile Edge computing network function virtualization VNF instance deployment virtualized service provisioning approximation and online algorithms delay-sensitive request admission utility gain maximization user mobility cloudlets or edge-clouds resource allocations and provisioning in MEC optimization problems

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A Robust Passive Islanding Detection Technique With Zero-Non-Detection Zone for Inverter-Interfaced Distributed Generation

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IEEE ACCESS 2022年 10卷 96296-96306页

作者： Pangedaiah, B. Reddy, P. L. Santosh Kumar Obulesu, Y. P. Kota, Venkata Reddy Alghaythi, Mamdouh L. Lakireddy Bali Reddy Coll Engn Elect & Elect Engn Dept Mylavaram 533003 Andhra Pradesh India Vellore Inst Technol Sch Elect Engn Vellore 632014 Tamil Nadu India JNTUK Elect & Elect Engn Dept Kakinada 533003 Andhra Pradesh India Jouf Univ Coll Engn Dept Elect Engn Sakaka 72388 Al Jouf Saudi Arabia

In this paper, a new and efficient passive islanding detection technique for a grid-connected hybrid distributed generating system has been proposed using Second Generation Wavelet Transform (SGWT) and Maximum Overlap Discrete Wavelet Transform (MODWT). In this technique, the ripple content of the voltage signal is measured at the Point of Common Coupling (PCC) and it is monitored through the decomposition of the signal by applying SGWT and MODWT technique up to suitable finer levels. This algorithm able to detects all kinds of islanding at nearly 0.3 sec, even with zero power mismatch. It is verified on a wide range of operational conditions and is also validated in various non-islanding conditions. Furthermore, the proposed technique is simple, there is no need for a classifier requirement, not depends on system parameters, zero non-detection zone (NDZ), and its operation is independent of the capacity and nature of distributed generation (DG) connected to the utility grid.

关键词： Islanding Discrete wavelet transforms Signal processing algorithms Voltage measurement Renewable energy sources Classification algorithms approximation algorithms Power grids Time-domain analysis Grid connected distributed generation maximum overlap discrete wavelet transform passive islanding detection second generation wavelet transform time domain analysis zero-non-detection zone

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Optimal Leader-Following Consensus Control of Multi-Agent Systems: A Neural Network Based Graphical Game Approach

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IEEE TRANSACTIONS ON NETWORK SCIENCE AND ENGINEERING 2022年第5期9卷 3590-3601页

作者： Ren, Yunxiao Wang, Qishao Duan, Zhisheng Peking Univ Coll Engn Dept Mech & Engn Sci State Key Lab Turbulence & Complex Syst Beijing 100871 Peoples R China Beihang Univ Dept Dynam & Control Beijing 100191 Peoples R China

In this article, the optimal leader-following consensus control problem of multi-agent systems is solved using a novel neural network-based (NN-based) integrated heuristic dynamic programming (IHDP) algorithm under a distributed learning framework. The optimal controller is designed to find a Nash equilibrium of the multi-agent differential graphical game. According to the principle of optimality, this problem can be transformed into solving a set of coupled Hamilton-Jacobi-Bellman (HJB) equations, which are difficult to solve directly because of the nonlinearity and strong coupling of the equations. The proposed algorithm combines policy iteration (PI) and value iteration (VI), and the Nash equilibrium of performance index among agents is achieved distributedly, i.e., all agents update their control inputs only use local information. The convergence of the algorithm is rigorously proved. Neural network (NN) approximation implementation is given for the unknown structures of local value functions of agents. The effectiveness of the algorithm is verified by numerical simulation.

关键词： Games Multi-agent systems Heuristic algorithms Artificial neural networks approximation algorithms Mathematical models Cost function Differential graphical game HJB equation multi-agent systems neural network optimal control

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Privacy Preservation of Optimization Algorithm Over Unbalanced Directed Graph

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IEEE TRANSACTIONS ON NETWORK SCIENCE AND ENGINEERING 2022年第4期9卷 2164-2173页

作者： Yan, Jiaojiao Cao, Jinde Southeast Univ Sch Math Jiangsu Prov Key Lab Networked Collect Intelligen Nanjing 210096 Peoples R China Southeast Univ Frontiers Sci Ctr Mobile Informat Commun & Secur Sch Math Nanjing 210096 Peoples R China Purple Mt Labs Nanjing 211111 Peoples R China Yonsei Univ Yonsei Frontier Lab Seoul 03722 South Korea

This paper proposes an algorithm with the property of privacy preservation to solve the multi-agent optimization problem, where the communication topology is a fixed and strongly connected directed graph with a row stochastic weight matrix. Here, we consider the external eavesdropper attack model and take the gradient information of the objective function as the agent's privacy information. In this algorithm, each agent adds an additional state variable that interacts with it with a time-varying weight. And this new variable performs gradient iterative calculation. The original state variable interacts with the new variable and the original neighbors. It is proved that the algorithm converges to the optimal solution of the problem and at the same time achieves the purpose of privacy preservation. In addition, the algorithm neither requires additional hidden signals, nor does it increase a large amount of calculation. Finally, a simulation example is given to verify the performance of the algorithm.

关键词： Optimization Privacy Directed graphs Stochastic processes Linear programming approximation algorithms Topology Distributed optimization privacy preservation unbalanced directed graph row stochastic additional state variables

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A Spectral Feature Selection Approach With Kernelized Fuzzy Rough Sets

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IEEE TRANSACTIONS ON FUZZY SYSTEMS 2022年第8期30卷 2886-2901页

作者： Chen, Jinkun Lin, Yaojin Mi, Jusheng Li, Shaozi Ding, Weiping Minnan Normal Univ Sch Math & Stat Zhangzhou 363000 Peoples R China Minnan Normal Univ Sch Comp Sci Zhangzhou 363000 Peoples R China Hebei Normal Univ Hebei Int Joint Res Ctr Math & Interdisciplinary Sch Math Sci Shijiazhuang 050024 Hebei Peoples R China Xiamen Univ Dept Artificial Intelligence Xiamen 361005 Peoples R China Nantong Univ Sch Informat Sci & Technol Nantong 226019 Peoples R China

Feature evaluation is an important issue in constructing a feature selection algorithm in kernelized fuzzy rough sets, which has been proven to be an effective approach to deal with nonlinear classification tasks and uncertainty in learning problems. However, the feature evaluation function developed with kernelized fuzzy rough sets cannot better reflect the affinity relationship of samples and is time-consuming. To overcome these drawbacks, in this article, the problem of feature selection with kernelized fuzzy rough sets is studied based on the spectral graph theory. First, the within-class and between-class sample similarity matrices by using kernelized fuzzy approximation operators are constructed. Two operators, which can capture the affinity relationship of samples, are then introduced based on the sample similarity matrices. The proposed operator can be regarded as the sum of the weighted kernelized fuzzy approximation operators. Second, based on the ratio criterion, a feature evaluation function and its corresponding feature selection algorithm FRKF are presented, which can effectively evaluate the importance of features. Third, to illustrate the performance of the proposed algorithm, extensive experiments have been carried out to compare FRKF and other well-known feature selection methods, including the feature ranking methods and feature subset selection methods on various classification tasks. The experimental results on real-world datasets demonstrate that FRKF achieves the high performances in terms of the robustness, efficiency, and effectiveness.

关键词： Feature extraction Rough sets Kernel approximation algorithms Graph theory Task analysis Uncertainty Feature evaluation feature selection fuzzy rough sets kernel spectral graph theory

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Taming the knight's tour: Minimizing turns and crossings

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THEORETICAL COMPUTER SCIENCE 2022年 902卷 1-20页

作者： Besa, Juan Jose Johnson, Timothy Mamano, Nil Osegueda, Martha C. Williams, Parker Univ Calif Irvine Irvine CA 92697 USA Columbia Univ New York NY 10027 USA

We introduce two new metrics of "simplicity" for knight's tours: the number of turns and the number of crossings. We give a novel algorithm that produces tours with 9.25n + O (1) turns and 12n + O (1) crossings on an n x n board, and we show lower bounds of (6 - epsilon)n and 4n - O (1) on the respective problems of minimizing these metrics. Hence, our algorithm achieves approximation ratios of 9.25/6 + o(1) and 3 + o(1). Our algorithm takes linear time and is fully parallelizable, i.e., the tour can be computed in O (n(2)/p) time using p processors in the CREW PRAM model. We generalize our techniques to rectangular boards, high-dimensional boards, symmetric tours, odd boards with a missing corner, and tours for (1, 4)-leapers. In doing so, we show that these extensions also admit a constant approximation ratio on the minimum number of turns, and on the number of crossings in most cases. (C) 2021 Published by Elsevier B.V.

关键词： Graph drawing Chess Hamiltonian cycle approximation algorithms

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