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Particuology 2024年第7期90卷 404-411页

作者： Hanqiao che Yuanhe Yue Zhaohua Jiang Duan Li School of Mechanical engineering Guangxi UniversityNanningGuangxi530004China School of chemical engineering University of BirminghamBirminghamB152TTUK Hebei engineering Research Center of Advanced energy Storage Technology and equipment School of Energy and Environmental EngineeringHebei University of TechnologyTianjin300401China Hebei Key Laboratory of Thermal Science and energy Clean Utilization School of Energy and Environmental EngineeringHebei University of TechnologyTianjin300401China School of Mechatronics and vehicle engineering Chongqing Jiaotong UniversityChongqing400074China School of Instrumentation and Opto-electronic engineering Beihang UniversityBeijing 100191China

The transient heat transfer behaviours in a packed bed have been studied using coupled computational fluid dynamics(CFD)and discrete element method(DeM).Intra-particle thermal diffusion,which is a crucial but rarely explored issue,is considered by introducing a one-dimensional diffusion equation in the DeM *** achieve a sufficiently long physical time of simulations,we further reduce the computational cost by applying periodic boundary condition to a small segment of the packed *** study demonstrates a shifting peak heat flow rate from the bottom to the top of the packed bed during the initial warming *** affirm that the influence of thermal diffusion within a particle is noteworthy only for particles exhibiting a high Biot number(e.g.,Bi=1.2).This insight enriches our understanding of heat transfer mechanisms in packed beds and their practical engineering applications.

关键词： Packed bed Intra-particle heat transfer CFD–DeM

Faster-than-Nyquist signaling based on filter bank multicarrier modulation with joint optimization

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Journal of Systems engineering and electronics 2022年第6期33卷 1208-1223页

作者： che Hui PeNG Dingxiang GUO Fachang BAI Yong School of Information and Communication engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Ruijie Networks Co. LtdFuzhou 350002China School of Information and Communication engineering Hainan UniversityHaikou 570228China

Multi-carrier faster-than-Nyquist(MFTN)can improve the spectrum efficiency(Se).In this paper,we first analyze the benefit of time frequency packing MFTN(TFP-MFTN).Then,we propose an efficient digital implementation for TFP-MFTN based on filter bank multicarrier *** time frequency packing ratio pair in our proposed implementation scheme is optimized with the Se ***,the joint optimization for the coded modulation MFTN based on extrinsic information transfer(eXIT)chart is *** Monte-Carlo simulations are carried out to verify performance gain of the joint inner and outer code *** results demonstrate that the TFPMFTN has a 0.8 dB and 0.9 dB gain comparing to time packing MFTN(TP-MFTN)and higher order Nyquist at same Se,respectively;the TFP-MFTN with optimized low density parity check(LDPC)code has a 2.9 dB gain comparing to that with digital video broadcasting(DVB)*** with previous work on TFP-MFTN(Se=1.55 bit/s/Hz),the Se of our work is improved by 29%and our work has a 4.1 dB gain at BeR=1×10^(-5).

关键词： faster-than-Nyquist filter bank multi-carrier time-frequency packing(TFP) spectrum efficiency(Se) joint optimization

effects of Biochar Application on Soil Organic Carbon in Degraded Saline-sodic Wetlands of Songnen Plain,Northeast China

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Chinese Geographical Science 2021年第5期31卷 877-887页

作者： che Qianjin LI Min ZHANG Zhongsheng 无 Yancheng Tearchers School Yancheng 224002China North Jiangsu Institute of Agricultural and Rural Modernization Yancheng 224002China Northeast Institute of Geography and Agroecology Chinese Academy of SciencesChangchun 130012China Xinfeng Middle School Yancheng 224100China

Biochar amendment is considered as an efficient practice for improving carbon storage in ***,to what extent that biochar application promotes organic carbon in saline-sodic soils remains poorly *** comparing soil organic carbon(SOC)contents change before and after biochar addition,we deciphered the driving factors or processes that control SOC change in response to biochar application.A limited increase in SOC was observed,about by 1.16%-12.80%,even when biochar was applied at the rate of 10%of bulk soil *** application enhanced soil dissolved organic carbon(DOC)significantly by up to 67%.It was estimated that about 50%SOC was allocated to small macroaggregates(250-2000μm,CPOC),and SOC in silt and clay-sized particles(ecreased obviously after biochar *** biomass increased with biochar amendment,of which actinomycetes(ACT),fungus(FUN),protozoon(PRO),and bacteria with straight-chain saturated fatty acids(OB)increased *** linear regression models implied that DOC was governed by ACT and soil N∶P ratio,while SOC mostly depended on *** principal component analysis and the partial least square path model(PLS-PM)indicated that biochar addition aggravated nitrogen limitation in saline-sodic soils,and effects of microorganisms on regulating SOC greatly depended on nitrogen *** application had vastly changed interactions between environmental factors and SOC in saline-sodic *** of nutrients on SOC shifted to great inhibition from strong stimulation after biochar addition,meanwhile,aggregation was the only factor presenting positive effects on *** to eliminate nutrient limitation and better soil aggregation process should be considered in priority when biochar was used to improve SOC in saline-sodic soils.

关键词： biochar saline-sodic soil soil organic carbon phospholipid fatty acid nutrient Songnen Plain China

Dynamic Phasor Modeling and Low-frequency Oscillation Analysis of Single-phase vehicle-grid System

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CSee Journal of Power and energy Systems 2023年第1期9卷 158-171页

作者： Xiaoqin Lyu Xiaoru Wang Yulong che Longyuan Li School of electrical engineering Southwest Jiaotong UniversityChengdu 610031China

In practical operations,low-frequency oscillation(LFO)occurs and leads to converter blocking when multiple electrical rail vehicles at the platform are powered by the traction *** paper proposes a small-signal model in state-space form for multiple vehicle-grid systems based on a dynamic *** model uses the phasor amplitude and phase as variables to accurately describe the dynamics of the converter phase-domain *** eigenvalue based-method is introduced to investigate the LFO with advantages of acquiring all oscillatory modes and analyzing participation *** low-frequency dominant modes are identified by *** shape reveals that one of the modes involves the oscillations between the grid-connected converters and the traction network,and the other one involves the oscillations among these *** the sensitivities of these two low-frequency modes to different system parameters are *** factors of system state variables,when the number of connected vehicle increases,are ***,the theoretical analysis is verified by nonlinear time-domain simulations and the modal analysis based on the estimation of signal parameters via the rotational invariance techniques(eSPRIT)method.

关键词： Dynamic phasor eigenvalue analysis electrical railway grid-connected converter low-frequency oscillation participation factors

A novel compound data classification method and its application in fault diagnosis of rolling bearings

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International Journal of Intelligent Computing and Cybernetics 2017年第1期10卷 80-90页

作者： Anxin Sun Ying che College of Optical and electronic Information Changchun University of Science and TechnologyChangchunChina

Purpose-The purpose of this paper is to provide a fault diagnosis method for rolling *** bearings are widely used in industrial appliances,and their fault diagnosis is of great importance and has drawn more and more *** on the common failure mechanism of failure modes of rolling bearings,this paper proposes a novel compound data classification method based on the discrete wavelet transform and the support vector machine(SVM)and applies it in the fault diagnosis of rolling ***/methodology/approach-Vibration signal contains large quantity of information of bearing status and this paper uses various types of wavelet base functions to perform discrete wavelet transform of vibration and *** vectors are constructed based on several time-domain indices of the denoised *** is then used to perform classification and fault *** the optimal wavelet base function is determined based on the diagnosis ***-experiments of fault diagnosis of rolling bearings are carried out and wavelet functions in several wavelet families were *** results show that the SVM classifier with the db4 wavelet base function in the db wavelet family has the best fault diagnosis ***/value-This method provides a practical candidate for the fault diagnosis of rolling bearings in the industrial applications.

关键词： Support vector machine Fault diagnosis Data classification Discrete wavelet transform Rolling bearing

Boosting battery state of health estimation based on self-supervised learning

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Journal of energy chemistry 2023年第9期84卷 335-346页

作者： Yunhong che Yusheng Zheng Xin Sui Remus Teodorescu Department of energy Aalborg UniversityAalborg 9220Denmark

State of health(SoH) estimation plays a key role in smart battery health prognostic and ***,poor generalization,lack of labeled data,and unused measurements during aging are still major challenges to accurate SoH *** this end,this paper proposes a self-supervised learning framework to boost the performance of battery SoH *** from traditional data-driven methods which rely on a considerable training dataset obtained from numerous battery cells,the proposed method achieves accurate and robust estimations using limited labeled data.A filter-based data preprocessing technique,which enables the extraction of partial capacity-voltage curves under dynamic charging profiles,is applied at *** learning is then used to learn the aging characteristics from the unlabeled data through an *** learned network parameters are transferred to the downstream SoH estimation task and are fine-tuned with very few sparsely labeled data,which boosts the performance of the estimation *** proposed method has been validated under different battery chemistries,formats,operating conditions,and *** estimation accuracy can be guaranteed by using only three labeled data from the initial 20% life cycles,with overall errors less than 1.14% and error distribution of all testing scenarios maintaining less than 4%,and robustness increases with *** with other pure supervised machine learning methods demonstrate the superiority of the proposed *** simple and data-efficient estimation framework is promising in real-world applications under a variety of scenarios.

关键词： Lithium-ion battery State of health Battery aging Self-supervised learning Prognostics and health management Data-driven estimation

Parameter estimation of LFM signals based on time reversal

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Journal of Systems engineering and electronics 2023年第3期34卷 674-681页

作者： MA Xinjie QI Wei che Kaijun WU Gang School of electronic Science and engineering Xiamen UniversityXiamen 361005China Beijing Institute of Tracking and Telecommunications Technology Beijing 100094China Jiuquan Satellite Launch Center Jiuquan 736200China

In this paper,parameter estimation of linear frequency modulation(LFM)signals containing additive white Gaussian noise is *** the center frequency estimation of an LFM signal is affected by the error propagation effect,resulting in a higher signal to noise ratio(SNR)threshold,a parameter estimation method for LFM signals based on time reversal is *** proposed method avoids SNR loss in the process of estimating the frequency,thus reducing the SNR *** simulation results show that the threshold is reduced by 5 dB compared with the discrete polynomial transform(DPT)method,and the root-mean-square error(RMSe)of the proposed estimator is close to the Cramer-Rao lower bound(CRLB).

关键词： linear frequency modulation(LFM)signal time reversal Cramer-Rao lower bound(CRLB) parameter estimation

Weight hierarchies of linear codes satisfying the almost chain condition

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Science in China(Series F) 2003年第3期46卷 175-186页

作者：陈文德 TorleivKlφve Laboratory of Systems and Control Information Security CenterInstitute of Systems ScienceAcademy of Mathematics and System SciencesChinese Academy of SciencesBeijing 100080China Department of Informatics University of Bergen Bergen High Techology Center N-5020 Bergen Norway

The weight hierarchy of a linear [n, k;q] code C over GF(q) is the sequence (d1,d2,..., dk) where dr is the size of the smallest support of an r-dimensional subcode of C. An [n,k;q] code satisfies the chain condition if there exists subcodes D1 D2 … Dk = C of C such that Dr has dimension r and support of size dr for all r. Further, C satisfies the almost chain condition if it does not satisfy the chain condition, but there exist subcodes Dr of dimension r and support of size dr for all r such that D2 D3 Dk = C and D1 D3. A simple necessary condition for a sequence to be the weight hierarchy of a code satisfying the almost chain condition is given. Further, explicit constructions of such codes are given, showing that in almost all cases, the necessary conditions are also sufficient.

关键词： weight hierarchy linear code almost chain condition.

An innovative inertial parameters identification method for non-cooperative space targets based on electrostatic interaction

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Chinese Journal of Aeronautics 2024年第9期37卷 417-432页

作者： Heng JING Zixuan ZHeNG Dejia che Jianping YUAN National Key Laboratory of Aerospace Flight Dynamics Northwestern Polytechnical UniversityXi'an 710072China School of Astronautics Northwestern Polytechnical UniversityXi'an 710072China

Inertial characteristics of non-cooperative targets are crucial for space capture and sub-sequent on-orbit *** methods for identifying inertial parameters involve proximity operations,which are associated with the risk of collision with non-cooperative *** paper introduces a long-range,contactless method for identifying the inertial parameters of a non-cooperative target during the pre-capture ***,electrostatic interaction is used as an external excitation to alter the target's motion.A force estimation algorithm that uses measure-ments from visual and potential sensors is proposed to estimate the electrostatic interaction and eliminate the need for force ***,a recursive estimation-identification framework is presented to concurrently estimate the coupled motion state,weak electrostatic interaction,and inertial parameters of the *** simulation results show that the proposed method extends the identification distance to 170 times that of the previous method while maintaining high identifica-tion precision forall parameters.

关键词： Non-cooperative target Inertial parameters identification electrostatic interaction Force estimation Dynamical coupling

Multi-timescale optimization scheduling of interconnected data centers based on model predictive control

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Frontiers in energy 2024年第1期18卷 28-41页

作者： Xiao GUO Yanbo che Zhihao ZHeNG Jiulong SUN energy Power Electrical Automation and Information EngineeringTianjin UniversityTianjin 300072China

With the promotion of“dual carbon”strategy,data center(DC)access to high-penetration renewable energy sources(ReSs)has become a trend in the ***,the uncertainty of ReS poses challenges to the safe and stable operation of DCs and power *** this paper,a multi-timescale optimal scheduling model is established for interconnected data centers(IDCs)based on model predictive control(MPC),including day-ahead optimization,intraday rolling optimization,and intraday real-time *** day-ahead optimization stage aims at the lowest operating cost,the rolling optimization stage aims at the lowest intraday economic cost,and the real-time correction aims at the lowest power fluctuation,eliminating the impact of prediction errors through coordinated multi-timescale *** simulation results show that the economic loss is reduced by 19.6%,and the power fluctuation is decreased by 15.23%.

关键词： model predictive control interconnected data center multi-timescale optimized scheduling distributed power supply/landscape uncertainty