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An error-bounded median filter for correcting ECG baseline wander

HEALTH INFORMATION SCIENCE AND SYSTEMS 2023年第1期11卷 45页

作者： Zhao, Huanyu Li, Tongliang Yang, Jian Pang, Chaoyi Donghua Univ Sch Comp Sci & Technol Shanghai Peoples R China Hebei Acad Sci Inst Appl Math Shijiazhuang Peoples R China Hebei Authenticat Technol Engn Res Ctr Shijiazhuang Peoples R China NingboTech Univ Sch Comp Sci & Data Engn Ningbo Peoples R China

The baseline wander (BLW) in electrocardiogram (ECG) is a common disturbance that has a significant influence on the ECG wave pattern recognition. Many methods, such as IIR filter, mean filter, etc., can be used to correct BLW;However, most of them work on the original ECG signals. Compressed ECG data are economic for data storage and transmission, and if the baseline correction can be processed on them, it will be more efficient than we decompress them first and then do such correction. In this paper, we propose a new type of median filter CM_Filter, which works on the synopses of straight lines achieved from ECG by piecewise linear approximation (PLA) under maximum error bound. In CM_Filter, a heuristic strategy "Quick-Finding" is deduced by a property of straight lines in order to get the quality-assured median values from the synopses. The extended experimental tests demonstrate that the proposed filter is very efficient in execution time, and effective for correcting both slow and abrupt ECG baseline wander.

关键词： piecewise linear approximation Maximum error bound Median filter Synopses Baseline wander Electrocardiograms

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Enhancing Microgrid Resilience with Green Hydrogen Storage

Enhancing Microgrid Resilience with Green Hydrogen Storage

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IEEE-Power-and-Energy-Society General Meeting (PESGM)

作者： Dhankar, Shreshtha Chen, Cong Tong, Lang Cornell Univ Sch Chem Engn Ithaca NY 14853 USA Cornell Univ Sch Elect & Comp Engn Ithaca NY 14850 USA

ISBN: (纸本)9798350381849;9798350381832

We consider the problem of hydrogen storage integration in microgrids to improve the electricity supply resilience. Nonlinear effects from electrochemical models of electrolyzers and fuel cells for hydrogen storage are considered, making scheduling under the nonlinear model intractable and the conventional linear approximation infeasible. A piecewise linear model approximation with feasibility projection is proposed, resulting in a computationally efficient model predictive control for hydrogen storage operation. Several resilience performance measures, such as loss-of-load, duration-of-outage, and system cost, are used in performance evaluation. Simulations for the proposed optimization demonstrated a 13%-48% reduction in duration-of-outage, a 6.4%-21.7% reduction in system cost, and a 95% reduction in loss-of-load for critical loads compared to the scheduling algorithm involving linear model approximation. The performance gap of the proposed optimization to the benchmark involving the accurate nonlinear electrochemical model is less than 1% in most metrics.

关键词： Green hydrogen storage resilience electrochemical model piecewise linear approximation microgrid

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A statistical method for estimating piecewise linear sales trends

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JOURNAL OF MARKETING ANALYTICS 2024年第2期12卷 436-444页

作者： Moriyama, Taku Kuwano, Masashi Nakayama, Masahito Tottori Univ Dept Management Social Syst & Civil Engn 4-101 Koyama Minami Tottori 6808552 Japan Tottori Univ Grad Sch Sustainabil Sci Dept Engn 4-101 Koyama Minami Tottori 6808552 Japan

Due to the structural breaks in time series, estimated current trend of product sales differs between the case where data for the entire span are used and the case where only the most recent data are used. The purpose of this study is to establish the piecewise linear approximation (PLA) as a trend analysis method that accounts for the structural breaks. PLA uses the complete data to simultaneously estimate the breakpoints and the continuously connected trends, immediately before and after the break. Thus, PLA not only ensures the ease of interpretation of the results, but also eliminates the probability of using discretion by uniquely determining the current trend, making the estimated result reliable. The case study demonstrates the proposition that, several products' sales trends and the necessity of determining an appropriate time span for data analysis, underwent changes at least once. The method's validity is demonstrated by showing the changes of the sales trends immediately after analyzed store's renovation. Data collection from the time period immediately prior to a structural break can help identify the factors changing the product sales.

关键词： Trend analysis Structural break Time series analysis POS data piecewise linear approximation

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Cost Minimization of Integrated Sensing, Communication, and Computing in UAV-Enabled Systems 2

Cost Minimization of Integrated Sensing, Communication, and ...

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2nd International Conference on Mobile Internet, Cloud Computing and Information Security (MICCIS)

作者： Wang, Zhongyu Meng, Hongbo Cao, Yashuai Cui, Dong Chang, Zheng Yanshan Univ Sch Informat Sci & Engn Qinhuangdao Hebei Peoples R China Tsinghua Univ Dept Elect Engn Beijing Peoples R China Univ Elect Sci & Technol China Sch Comp Sci Chengdu Peoples R China

ISBN: (纸本)9798350389913;9798350389906

Unmanned aerial vehicles (UAVs) can be deployed as powerful air relays to remedy delay-sensitive computing tasks. In this paper, we propose to adopt a fixed-position UAV equipped with over-the-air computing (AirComp) ability to support computation offloading for ground users away from the base station (BS). In light of the dual-functional communication and sensing BS antenna, we develop an integrated sensing, communication, and computing (ISCC) framework, where the BS performs the sensing task, and transmits the sensing information to the UAV, enhancing the computing schedule of the UAV. Then, three models of communication, sensing, and computing are deduced, and the total cost of the delay, accuracy, and power is minimized by jointly optimizing the task scheduling variable matrix, the proportion of communication resources, and the sensing threshold. We invoke the Lagrange multiplier method, piecewise linear approximation, and quick sorting-based task scheduling algorithm to solve the problem. Simulation results show that the proposed algorithm effectively reduces the ISCC cost compared with some existing algorithms and verifies the feasibility of the proposed algorithm.

关键词： Integrated sensing communication and computing unmanned aerial vehicle cost minimization piecewise linear approximation

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piecewise linear approximation of Generators Cost Functions Using Max-Affine Functions

Piecewise Linear Approximation of Generators Cost Functions ...

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IEEE Power and Energy Society General Meeting

作者： Hamed Ahmadi José R. Martí Ali Moshref School of Electrical and Computer Engineering University of British Columbia Vancouver BC Canada BBA Vancouver BC Canada

ISBN: (纸本)9781479913022

Nonlinear functions are often encountered in power system optimizations. In this paper, an effective piecewise linear (PWL) approximation technique is introduced which shows promising performance in linearizing the nonlinear functions. This method uses a series of linear functions, called max-affine functions, to linearize a multivariate function over a bounded domain. The important advantage of this method is its ability to decide on the size of the subspaces, which other methods are not capable of. It is also shown that using the PWL approximation, significant efficiency is achievable in computation burden of most power system optimizations, such as unit commitment.

关键词： piecewise linear approximation Generators dynamos linear approximation piecewise piecewise linear approximation nonlinear functions power level Cost functions linear function Unit commitment Subspace

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Membership Function-Dependent Local Controller Design for T-S Fuzzy Systems

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IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS 2022年第2期52卷 814-821页

作者： Xie, Wen-Bo Zheng, Hua Li, Ming-Yang Ahn, Choon Ki Harbin Univ Sci & Technol Coll Automat Key Lab Adv Mfg & Intelligent Technol Minist Educ Harbin 150080 Peoples R China Shanghai Univ Sch Mechatron Engn & Automat Shanghai 200072 Peoples R China Korea Univ Sch Elect Engn Seoul 136701 South Korea

For the conservatism issue of state-feedback control for Takagi-Sugeno (T-S) fuzzy systems, a novel local controller design method and stability analysis approach are proposed in this article. First, based on a membership function piecewise linearization technique, a local linear controller is proposed to form a closed-loop system. Then, a series of system stability conditions are derived using quadratic and piecewise function approaches. Further, with a designed fuzzy local controller and fuzzy Lyapunov function, less conservative stability conditions are obtained. Finally, a simulation example is adopted to make comparisons with existing and proposed methods. The results clearly show the conservatism reduction and excellent performance of the proposed approach.

关键词： Stability analysis Lyapunov methods Fuzzy systems Closed loop systems Automation piecewise linear approximation Cybernetics Conservatism membership function (MF) state feedback Takagi-Sugeno (T-S) fuzzy system

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A Flexible and High-Precision Activation Function Unit Based on Equi-Error Partitioning Algorithm

A Flexible and High-Precision Activation Function Unit Based...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Yuan, Zelong Yuan, Siwei Liu, Pengyu Yin, Chen Xu, Lei Sheng, Weiguang Jing, Naifeng Shanghai Jiao Tong Univ Dept Micronano Elect Shanghai Peoples R China

ISBN: (纸本)9798350330991;9798350331004

The diversity of activation functions has gradually increased to accommodate different tasks in modern deep neural networks (DNNs). However, these novel activation functions involve more nonlinear operations relative to traditional activation functions, which increases the computational complexity. To address these issues, a piecewise linear (PWL) approximation algorithm called Equi-Error Partitioning Algorithm is proposed in this paper. The algorithm aims at balancing the errors between segments and solves the problem of excessive precision that exists in other PWL approximation methods and achieves on average 30.07x better mean squared error compared to the previous works. Based on this algorithm, we propose an activation function unit (AFU) which enables the addressing scheme of non-uniform segments and provides reconfigurability for all common activation functions by reloading parameters. End-to-end evaluation with several DNNs shows the accuracy loss is all less than 0.06% with 64 segments.

关键词： equi-error partition hardware architecture piecewise linear approximation non-uniform segments activation function

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piecewise linear Plus Quadratic Surrogate Model for Real -Time Optimization 12

Piecewise Linear Plus Quadratic Surrogate Model for Real -Ti...

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12th IFAC Symposium on Advanced Control of Chemical Processes (ADCHEM)

作者： Zhang, Duo Li, Xiang Kazda, Kody Shao, Zhijiang Zhejiang Univ Coll Control Sci & Engn Hangzhou 310027 Peoples R China Queens Univ Dept Chem Engn Kingston ON K7L 3N6 Canada

Surrogate models are important in real-time optimization (RTO) when the first-principles model is unavailable or computationally challenging for online optimization. Among different surrogate models, the continuous piecewise linear (CPWL) model enjoys the universal approximation ability and potential computational benefits. However, the CPWL surrogate model poses three challenges to current RTO algorithms. First, the solution of a CPWL model is always located on the boundary of a polytopic subregion, while the plant optimum may be in the interior of a subregion. Second, the CPWL model is nonsmooth, which cannot be handled by RTO methods that rely on gradient matching. Third, the resulting nonsmooth optimization subproblems are hard to solve. This paper addresses the difficulties by adding a quadratic function to the CPWL surrogate model, extending a classical RTO method to accommodate nonsmoothness, and exploiting the difference-of-convex structure of the surrogate model for efficient solution. The advantages of the proposed method are demonstrated through a benchmark problem in the RTO literature.

关键词： real-time optimization piecewise linear approximation surrogate modifier adaptation difference-of-convex

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Solution of Basset integro-differential equations by IIR digital filters

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ALEXANDRIA ENGINEERING JOURNAL 2022年第12期61卷 11899-11911页

作者： Lahboub, Driss Heyd, Rodolphe Bakak, Abderrahim Lotfi, Mohamed Koumina, Abdelaziz Cadi Ayyad Univ Lab Interdisciplinaire Rech Bioressources Energie ENS Marrakech 40000 Morocco Lab Angevin Mecan Procedes & InnovAt LAMPA Arts & Metiers ParisTech Blvd du Ronceray 2 F-49035 Angers France Cadi Ayyad Univ Mat Energy & Environm Lab LaMEE FSSM Marrakech 40000 Morocco

A new O (n) time complexity numerical method for computing the solutions of Basset integro-differential equations is presented. The method is based on the use of Laplace and bilinear transformations, leading after a precise Chebyshev rational interpolation, to the construction of first order infinite impulse response (IIR) filters. The resulting recurrence relations allow for a very accurate O (n) resolution of Basset equations. Different numerical examples are presented in order to demonstrate the applicability of the method to the study of the transient creeping flow motion of a rigid spherical particle. The results are compared on the one hand to those provided by the Talbot inversion method and on the other hand to those provided by an iterative method specially elabo-rated here to solve the Basset problem.(c) 2022 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Integro-differential equations Basset kernel Laplace transformation Infinite impulse response filters piecewise linear approximation

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PREFERENCE ROBUST MODIFIED OPTIMIZED CERTAINTY EQUIVALENT

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SIAM JOURNAL ON OPTIMIZATION 2022年第4期32卷 2662-2689页

作者： Wu, Qiong Xu, Huifu Chinese Univ Hong Kong Dept Syst Engn & Engn Management Hong Kong Peoples R China

Ben-Tal and Teboulle [Management Sci., 32 (1986), pp. 1445--1466] introduce the concept of optimized certainty equivalent (OCE) of an uncertain outcome as the maximum present value of a combination of the cash to be taken out from the uncertain income at present and the expected utility value of the remaining uncertain income. In this paper, we consider two variations of the OCE. First, we introduce a modified OCE by maximizing the combination of the utility of the cash and the expected utility of the remaining uncertain income so that the combined quantity is in a unified utility value. Second, we consider a situation where the true utility function is unknown but it is possible to use partially available information to construct a set of plausible utility functions. To mitigate the risk arising from the ambiguity, we introduce a robust model where the modified OCE is based on the worst-case utility function from the ambiguity set. In the case when the ambiguity set of utility functions is constructed by a Kantorovich ball centered at a nominal utility function, we show how the modified OCE and the corresponding worst-case utility function can be identified by solving two linear programs alternatively. We also show that the robust modified OCE is statistically robust in a data-driven environment where the underlying data are potentially contaminated. Some preliminary numerical results are reported to demonstrate the performance of the modified OCE and the robust modified OCE model.

关键词： robust modified optimized certainty equivalent ambiguity of utility function Kantorovich ball piecewise linear approximation error bounds statistical robustness

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