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IEEE 93rd Vehicular Technology Conference (VTC-Spring)

作者： Lin, Jianzhen Pan, Cunhua He, Chunlong Wang, Kezhi Shenzhen Univ Guangdong Key Lab Intelligent Informat Proc Shenzhen Peoples R China Queen Mary Univ London Sch Elect Engn & Comp Sci London England Northumbria Univ Dept Comp & Informat Sci Newcastle Upon Tyne Tyne & Wear England

ISBN: (纸本)9781728189642

This paper investigates a UAV-enabled wireless downlink system, where a UAV-enabled base station flies above a group of Internet of things devices (IoTDs) and transmits data to them. In order to ensure the fairness among all IoTDs, we jointly optimize scheduling association and UAV trajectory to maximize the minimal throughput of all IoTDs under the 3-dimensional (3-D) channel model. Meanwhile, to ensure the stability of communication, we aim to guarantee a high probability of line-of-sight (LoS) links between the UAV and all IoTDs. The optimization problem is non-convex and we propose an iterative algorithm based on the block coordinate descent and successive convex approximation to solve it. Furthermore, we show the convergence of the algorithm through simulations. It is shown that the proposed algorithm achieves higher data rate than the traditional scheme without guaranteeing the LoS probability.

关键词： UAV communication trajectory iterative algorithm

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EMPIRICALLY ACCELERATING SCALED GRADIENT PROJECTION USING DEEP NEURAL NETWORK FOR INVERSE PROBLEMS IN IMAGE PROCESSING

EMPIRICALLY ACCELERATING SCALED GRADIENT PROJECTION USING DE...

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

作者： Lee, Byung Hyun Chun, Se Young UNIST Grad Sch AI Seoul South Korea Seoul Natl Univ INMC Dept ECE Seoul South Korea

ISBN: (纸本)9781728176055

Recently, deep neural networks (DNNs) have shown advantages in accelerating optimization algorithms. One approach is to unfold finite number of iterations of conventional optimization algorithms and to learn parameters in the algorithms. However, these are forward methods and are indeed neither iterative nor convergent. Here, we present a novel DNN-based convergent iterative algorithm that accelerates conventional optimization algorithms. We train a DNN to yield parameters in scaled gradient projection method. So far, these parameters have been chosen heuristically, but have shown to be crucial for good empirical performance. In simulation results, the proposed method significantly improves the empirical convergence rate over conventional optimization methods for various large-scale inverse problems in image processing.

关键词： scaled gradient projection deep neural network iterative algorithm convergence

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An iterative model-free feature screening procedure: Forward recursive selection

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KNOWLEDGE-BASED SYSTEMS 2022年 246卷

作者： Xia, Siwei Yang, Yuehan Civil Aviat Flight Univ China Sch Sci Deyang Peoples R China Cent Univ Finance & Econ Sch Stat & Math Beijing Peoples R China

Many researchers have studied the combinations of machine learning techniques and traditional statistical strategies, and proposed effective procedures for complicated data sets. Yet, there is still some lack of running time and prediction accuracy. In this paper, we propose an iterative feature screening procedure, named forward recursive selection. We combine the random forest and forward selection to address the model-based limitations and the related requirements. We also use the forward strategy with a limited number of iterations to improve the computational efficiency. To provide the theoretical guarantees of this method, we calculate functions of the permutation importance of this algorithm in different models and data with group structures. Numerical comparisons and empirical analysis support our results, and the proposed procedure works well. (c) 2022 Elsevier B.V. All rights reserved.

关键词： Random forest Forward selection iterative algorithm Statistical modeling

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Analytics and Optimization Techniques on Feeder Identification in Smart Grids 19

Analytics and Optimization Techniques on Feeder Identificati...

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19th International Conference on Smart Technologies (IEEE EUROCON)

作者： Aranburu, Larraitz Unzueta, Aitziber Garin, M. Araceli Modrono, Juan, I Amezua, Aitor Univ Basque Country Dept Matemat Leioa Bizkaia Spain Univ Basque Country Dept Matemat Aplicada Blbao Bizkaia Spain Univ Basque Country Dept Metodos Cuantitat Blbao Bizkaia Spain Univ Basque Country Dept Metodos Cuantitat Bilbao Bizkaia Spain ZIV Automat Zamudio Bizkaia Spain

ISBN: (纸本)9781665432993

One of the problems faced by electric power distribution system operators is to know with certainty the actual location of all their assets in order to manage properly the grid and provide the best service to their customers. In this work, we present a procedure for the identification of low voltage feeders or distribution lines in smart grids that is based on the mathematical formulation of the problem as an optimization model. In particular, we define the model with 0-1 variables (as many as meters to be identified in the different feeders) and with as many restrictions as the number of points in time that are considered. Given the large size of the problem in practice, the use of conventional optimization software becomes unfeasible. Based on this approach, and making use of the linear relaxation of the problem, some analytics over the coefficients (i.e., meter loads) and the special structure of the problem itself, we have developed an iterative procedure that allows us to recover the entire solution of the initial model in an efficient way. We have carried out a computational experience on a set of anonymized real data, obtaining results that support the efficiency of the proposed procedure.

关键词： connectivity model integer optimization iterative algorithm linear relaxation smart meter datasets

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A Novel Sensor-less On-line Estimation Method of IGBT Junction Temperature 12

A Novel Sensor-less On-line Estimation Method of IGBT Juncti...

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12th IEEE Energy Conversion Congress and Exposition-Asia (ECCE-Asia)

作者： Zhan, Cao Zhu, Lingyu Zhang, Yaxin Ji, Shengchang Zhang, Jian Yu, Chaoyun Xi An Jiao Tong Univ State Key Lab Elect Insulat & Power Equipment Xian Peoples R China China Southern Power Grid Technol Co LTD Guangzhou Peoples R China

ISBN: (纸本)9781728163444

Thermal management and condition monitoring of power converters demand the accurate estimation of the junction temperature of insulated-gate bipolar transistor (IGBT). With existing iteration methods, the junction temperature is fed forward to calculate the power loss and derive the junction temperature of the next cycle, causing the problem of accumulated calculation error. This letter proposes a novel iterative algorithm to improve the calculation accuracy. Unlike the conventional solutions, utilizing the junction temperature of the previous moment to calculate the power losses, the proposed iteration method uses junction temperature and power losses of the same moment to tackle the accumulated error problem. Since the iterative equation has unique solution, the convergence value is the actual junction temperature and power losses. The initial power losses has no influence on the result, so it is not necessary to obtain the accurate power loss for the estimation of junction temperature. Power cycling experiment is performed to verify the advantages of the novel iterative algorithm. The novel method solves the accumulated error compared to the traditional method. The accuracy of the novel method is also verified by the result of 100mA current test during power cycling.

关键词： IGBT junction temperature iterative algorithm power loss power cycling

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Field and Numerical Investigations of Wave Effects on Groundwater Flow and Salt Transport in a Sandy Beach

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WATER RESOURCES RESEARCH 2022年第11期58卷

作者： Yu, Shengchao Wang, Chaoyue Li, Hailong Zhang, Xiaolang Wang, Xuejing Qu, Wenjing Southern Univ Sci & Technol Sch Environm Sci & Engn State Environm Protect Key Lab Integrated Surface Shenzhen Peoples R China Univ Hong Kong Dept Earth Sci Hong Kong Peoples R China Hebei GEO Univ Hebei Ctr Ecol & Environm Geol Res Sch Water Resources & Environm Shijiazhuang Hebei Peoples R China

Coastal dynamic forces, such as waves and tides, altogether drive groundwater circulation and salt transport in the intertidal zone. However, few numerical studies have ever considered the combined effects of waves and tides. In this study, the fluctuations of wave height are integrated with tidal level together using an iterative least squares fitting method, in which the wave height can be acquired from measured sea level in the surf zone, and this fitted wave height is further verified by wind speed. Groundwater flow and salt transport were then simulated using the MARUN code to evaluate the impacts after considering wave effect. The simulated equivalent freshwater head and salinity of the model with wave effect presented less difference with the measured data compared with the simulated results of the model without wave effect. After incorporating the wave effect in a model, submarine groundwater discharge (SGD) was increased, among which recirculated SGD grew more rapidly than the fresh, leading to the proportion of the fresh SGD accounting for a small proportion (1.1%). The water influx and efflux rates increased greatly especially during the period of high wave height. Most of the influx occurred in the intertidal zone, while a considerable amount of efflux occurred in the subtidal zone. The iterative algorithm to separate the wave height from the mixed field data can be employed to identify and quantify the respective effects of tides and the combined effects of waves and tides on the density-dependent beach groundwater flow.

关键词： coastal beach iterative algorithm tidal level wave height wave setup

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Complex Variable Multi-phase Distribution System State Estimation Using Vectorized Code

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Journal of Modern Power Systems and Clean Energy 2020年第4期8卷 679-688页

作者： Izudin Džafić Rabih A.Jabr Tarik Hrnjić IEEE Faculty of Electrical Engineering University of SarajevoZmaja od Bosne bb 71000 SarajevoBosnia and Herzegovina Department of Electrical&Computer Engineering American University of BeirutP.O.Box 11-0236Riad El-Solh/Beirut 11072020Lebanon

With the advent of advanced energy management systems in distribution systems,there is a growing interest in rapid and reliable code for distribution system state estimation(DSSE)in large-scale *** DSSE methods employed in the industry are based on load scaling as they are well suited to the abundance of *** to the paucity of real-time measurements in DSSE,phasor measurement units(PMUs)have been proposed as a potential solution to increase the estimation ***,load scaling methodologies are not extendable for exploiting *** paper proposes a high-performance DSSE method that can handle the PMUs together with all common measurement types in industrial *** using Wirtinger calculus,the method operates entirely in complex variables and employs the latest version of advanced vector extensions(AVX-2)to reap the maximum potential of computer processing *** paper highlights the derivation of complex DSSE in matrix form,from which one can infer the implications on code reliability and *** results are reported on large-scale multi-phase distribution systems,and they are contrasted with a publicly available code for DSSE in real *** simulation results show that loop unrolling in AVX-2 contributes about a two-fold increase in the solving speed.

关键词： iterative algorithm least squares approximation optimization method distribution system state estimation

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A fast computational algorithm for computing outer pseudo-inverses with numerical experiments

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2022年 408卷

作者： Dehghan, Mehdi Shirilord, Akbar Amirkabir Univ Technol Fac Math & Comp Sci Dept Appl Math Tehran Polytech 424 Hafez Ave Tehran 15914 Iran

In many studies in applied sciences and engineering one should find outer pseudo inverse of a matrix. In this paper, we propose a new efficient algorithm for computing the outer pseudo-inverse of a matrix. We study the convergence analysis of the new algorithm. Finally, test problems and simulation results support the theoretical approach. (c) 2022 Elsevier B.V. All rights reserved.

关键词： Outer pseudo-inverses Efficiency index iterative algorithm Convergence

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Bumpless H∞ control for periodic piecewise linear systems

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AUTOMATICA 2022年 135卷

作者： Song, Xiaoqi Lam, James Univ Hong Kong Dept Mech Engn Pokfulam Rd Hong Kong Peoples R China HKU Shenzhen Inst Res & Innovat HKU SIRI Shenzhen 518057 Peoples R China

This paper investigates the bumpless H-infinity control problem based on exponential stability and L-2-gain analyses for a class of periodic piecewise linear systems. A novel characterization of bumpless transfer among a variety of subsystem controllers satisfying some interpolation constraints is introduced. By utilizing adjustable interpolation functions and multiple Lyapunov functions, more flexibility is provided so as to guarantee a desirable closed-loop performance and trajectory smoothness. Since the problem formulated boils down to a feasibility problem involving nonlinear matrix inequalities, an iterative algorithm which solves a series of convex optimization problems is developed. Numerical examples are presented to show the validity of the proposed methods. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Bumpless transfer H-infinity performance Interpolative controllers iterative algorithm Periodic piecewise systems

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Reconfigurable Intelligent Surface Empowered Underlaying Device-to-Device Communication

Reconfigurable Intelligent Surface Empowered Underlaying Dev...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Yang, Gang Liao, Yating Liang, Ying-Chang Tirkkonen, Olav Univ Elect Sci & Technol China Chengdu Peoples R China Aalto Univ Aalto Finland

ISBN: (纸本)9781728195056

Reconfigurable intelligent surfaces (RIS) are a new and revolutionary technology to achieve spectrum, energy- and cost-efficient wireless networks. This paper studies the resource allocation for RIS-empowered device-to-device (D2D) communication underlaying a cellular network, in which an RIS is employed to enhance desired signals and suppress interference between paired D2D and cellular links. We maximize the sum rate of D2D users and cellular users by jointly optimizing the resource reuse indicators, the transmit power and the RIS's passive beamforming. To solve the formulated non-convex problem, we first propose an efficient user-pairing scheme based on relative channel strength to determine the resource reuse indicators. Then, the transmit power and the RIS's passive beamforming are jointly optimized by an iterative algorithm, based on the techniques of alternating optimization, successive convex approximation, Lagrangian dual transform and quadratic transform. Numerical results show that the proposed design outperforms the traditional D2D network without RIS.

关键词： Device-to-device communication reconfigurable intelligent surfaces passive beamforming power allocation iterative algorithm

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