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Thermal Property Enhancement of a Novel Shape-Stabilized Sodium Acetate Trihydrate-Acetamide/Expanded Graphite-Based Composite Phase Change Material

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Journal of Thermal Science 2024年第4期33卷 1564-1576页

作者： AN Zhoujian HOU Wenjie DU Xiaoze HUANG Zhongzheng MOMBEKI PEA Hamir Johan ZHANG Dong LIU Xiaomin college of energy and power engineering Lanzhou University of Technology key laboratory of Multi-supply system with Solar energy and Biomass of Gansu province Gansu Natural energy Research Institute

Phase change materials(PCMs) are a kind of highly efficient thermal storage materials which have a bright application prospect in many fields such as energy conservation in buildings,waste heat recovery,battery thermal management and so on.Especially inorganic hydrated salt PCMs have received increasing attention from researchers due to their advantages of being inexpensive and non-flammable.However,inorganic hydrated salt PCMs are still limited by the aspects of inappropriate phase change temperature,liquid phase leakage,large supercooling and severe phase separation in the application process.In this work,sodium acetate trihydrate was selected as the basic inorganic PCM,and a novel shape-stabilized composite phase change material(CPCM) with good thermal properties was prepared by adding various functional additives.At first,the sodium acetate trihydrate-acetamide binary mixture was prepared and the melting point was adjusted using acetamide.Then the binary mixture was incorporated into expanded graphite to synthesize a novel shape-stabilized CPCM.The thermophysical properties of the resultant shape-stabilized CPCM were systematically investigated.The microscopic morphology and chemical structure of the obtained shape-stabilized CPCM were characterized and analyzed.The experiment results pointed out that acetamide could effectively lower the melting point of sodium acetate trihydrate.The obtained shape-stabilized CPCM modified with additional 18%(mass fraction) acetamide and 12%(mass fraction) expanded graphite exhibited good shape stability and thermophysical characteristics:a low supercooling degree of 1.75℃ and an appropriate melting temperature of 40.77℃ were obtained;the latent heat of 151.64 kJ/kg and thermal conductivity of 1.411 W/(m·K) were also satisfactory.Moreover,after 50accelerated melting-freezing cycles,the obtained shape-stabilized CPCM represented good thermal reliability.

关键词： sodium acetate trihydrate melting point modification agent expanded graphite shape stability thermal conductivity enhancement

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Distributed Robust Optimal Dispatch of Regional Integrated energy systems Based on ADMM Algorithm with Adaptive Step Size

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Journal of Modern power systems and Clean energy 2024年第3期12卷 852-862页

作者： Zhoujun Ma Yizhou Zhou Yuping Zheng Li Yang Zhinong Wei the college of energy and Electrical engineering Hohai University State Grid jiangsu Electric power Co. Ltd. State key laboratory of Smart Grid Protection and Control NARI Group Corporation

This paper proposes a distributed robust optimal dispatch model to enhance information security and interaction among the operators in the regional integrated energy system(RIES). Our model regards the distribution network and each energy hub(EH) as independent operators and employs robust optimization to improve operational security caused by wind and photovoltaic(PV) power output uncertainties, with only deterministic information exchanged across boundaries. This paper also adopts the alternating direction method of multipliers(ADMM) algorithm to facilitate secure information interaction among multiple RIES operators, maximizing the benefit for each subject. Furthermore, the traditional ADMM algorithm with fixed step size is modified to be adaptive, addressing issues of redundant interactions caused by suboptimal initial step size settings. A case study validates the effectiveness of the proposed model, demonstrating the superiority of the ADMM algorithm with adaptive step size and the economic benefits of the distributed robust optimal dispatch model over the distributed stochastic optimal dispatch model.

关键词： Uncertainty Costs power systems Stochastic processes Renewable energy sources Optimization methods Adaptation models

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Novel sandwich structured glass fiber Cloth/Poly(ethylene oxide)-MXene composite electrolyte

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Nano Materials Science 2024年第1期6卷 60-67页

作者： Yu-Qin Mao Guang-He Dong Wei-Bin Zhu Yuan-Qing Li Pei Huang Shao-Yun Fu college of aerospace engineering Chongqing UniversityChongqing400044China State key laboratory of power Transmission Equipment and system Security and New Technology Chongqing UniversityChongqing400044China

Recently,poly(ethylene oxide)(PEO)-based solid polymer electrolytes have been attracting great attention,and efforts are currently underway to develop PEO-based composite electrolytes for next generation high performance all-solid-state lithium metal batteries.In this article,a novel sandwich structured solid-state PEO composite electrolyte is developed for high performance all-solid-state lithium metal batteries.The PEO-based composite electrolyte is fabricated by hot-pressing PEO,LiTFSI and Ti_(3)C_(2)T_(x) MXene nanosheets into glass fiber cloth(GFC).The as-prepared GFC@PEO-MXene electrolyte shows high mechanical properties,good electrochemical stability,and high lithium-ion migration number,which indicates an obvious synergistic effect from the microscale GFC and the nanoscale MXene.Such as,the GFC@PEO-1 wt%MXene electrolyte shows a high tensile strength of 43.43 MPa and an impressive Young's modulus of 496 MPa,which are increased by 1205%and 6048%over those of PEO.Meanwhile,the ionic conductivity of GFC@PEO-1 wt%MXene at 60℃ reaches 5.01×10^(-2) S m^(-1),which is increased by around 200%compared with that of GFC@PEO electrolyte.In addition,the Li/Li symmetric battery based on GFC@PEO-1 wt%MXene electrolyte shows an excellent cycling stability over 800 h(0.3 mA cm^(-2),0.3 mAh cm^(-2)),which is obviously longer than that based on PEO and GFC@PEO electrolytes due to the better compatibility of GFC@PEO-1 wt%MXene electrolyte with Li anode.Furthermore,the solid-state Li/LiFePO_(4) battery with GFC@PEO-1 wt%MXene as electrolyte demonstrates a high capacity of 110.2–166.1 mAh g^(-1) in a wide temperature range of 25–60C,and an excellent capacity retention rate.The developed sandwich structured GFC@PEO-1 wt%MXene electrolyte with the excellent overall performance is promising for next generation high performance all-solid-state lithium metal batteries.

关键词： Solid polymer electrolyte Ti_(3)C_(2)T_(x)MXene Poly(ethylene oxide) Glass fiber cloth All-solid-state Li metal Battery

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Work-function-induced interfacial electron redistribution of MoO_(2)/WO_(2) heterostructures for high-efficiency electrocatalytic hydrogen evolution reaction

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Rare Metals 2024年第2期43卷 489-499页

作者： Tong-Fei Li Jing Li Lu-Ping Zhang Jia-Wei Ke Meng-Xing Fan Li-Fang Zhang Cheng-Wei Deng Yi Sun Tao Qian Cheng-Lin Yan School of Chemistry and Chemical engineering Nantong UniversityNantong226019China jiangsu key laboratory of New power Batteries Jiangsu Collaborative Innovation Centre of Biomedical Functional MaterialsSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing210023China aerospace Hydrogen energy Technology(Shanghai)Co.Ltd. Shanghai201800China key laboratory of Core Technology of High Specific energy Battery and key Materials for Petroleum and Chemical Industry College of EnergySoochow UniversitySuzhou215006China Light Industry Institute of Electrochemical power Sources Suzhou215006China

The engineering of the electronic configurations of active sites,together with the production of more accessible active sites through heterostructure design,has been established as a forceful methodology for boosting water electrolysis performance.Herein,a facile approach is developed to fabricate well-dispersed MoO_(2) and WO_(2) nanoparticles with abundant heterointerfaces entrapped in N,P-doped carbon nanofibers(referred to as MoO_(2)/WO_(2)@N,P-CNFs hereafter)as hydrogen evolution reaction(HER)electrocatalysts in alkaline and acidic electrolytes.Extensive spectroscopic analyses and theoretical findings manifest that the heterointerface formed by the work function modulation of MoO_(2)/WO_(2) triggers the spontaneous electron redistribution from MoO_(2)to WO_(2) and a built-in electric field,which is essential to promote water adsorption,optimize the H-intermediate adsorption energy,result in the enhanced charge transfer efficiency,and ultimately increase the intrinsic HER activity.Simultaneously,the intimate confinement of MoO_(2)/WO_(2) heterostructures in the porous carbon substrate can restrain the active sites from unfavorable coarsening and detachment,thus ensuring facilitated HER kinetics and outstanding structural robustness.As a result,MoO_(2)/WO_(2)@N,P-CNFs exhibit superior catalytic HER performance in acidic and basic solutions,requiring 118 and 95 mV overpotentials to achieve 10 mA·cm^(−2),respectively,surpassing a number of reported non-noble metal-based electrocatalysts.This work provides guidelines for the rational design and construction of special metallic heterocomponents with optimized interfacial electronic structure for various electrochemical technologies.

关键词： Electrospinning MoO_(2)/WO_(2) heterostructure Work function Hydrogen evolution reaction

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Performance analysis of the tight combination of GPS, BDS, GALILEO,and QZSS mixed frequencies signals

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Geodesy and Geodynamics 2024年第4期15卷 366-378页

作者： Yu Han Fangjun Qin Xugang Lian Shengliang Wang Leiyuan Qian Wenhua Huang college of Electrical engineering Naval University of Engineering college of Mining engineering Taiyuan University of Technology State key laboratory of Satellite Navigation system and Equipment Technology State key laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences China energy engineering Group Shanxi Electric power engineering CO.LTD.

With the gradual development and modernization of satellite navigation systems, using observation information from multi-GNSS has become one of the hot-spot issues in recent years. Multi-system loose combinations form double-difference observation equations within their respective systems, and the positioning effect is improved. However, the interchangeability and compatible interoperability between global navigation satellite systems(GNSS) cannot be truly realized. At the same time, when the number of visible satellites decreases abruptly, the positioning performance deteriorates sharply. This paper focuses on the GNSS multi-system tight combination relative positioning technique, gives a mathematical model of multi-system tight combination relative positioning considering differential intersystem bias(DISB), and analyzes the time-varying characteristics of DISB at overlapping and nonoverlapping frequencies among GPS/Galileo, GPS/BDS, and GPS/QZSS in terms of receiver brand, temperature, and receiver restart. The GNSS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology. The results show that compared with loose combination, the ambiguity-fixed rate increases from 62.18% to 97.60% for static data and from 74.97% to 99.53% for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.

关键词： GNSS Mix frequencies Redundancy Tight combination Differential inter-system bias

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Neutral color and self-healable electrochromic system based on CuI/Cu and I_(3)^(-)/I^(-)conversions

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Nano Research 2024年第5期17卷 4437-4443页

作者： Junsen Zhong Bingkun Huang Kunjie Yang Zuju Ma Lingyu Du Ning Luo Fengjiao Tang Chuanxin Hou Fuyi Jiang Litao Kang college of Environment and Materials engineering Yantai UniversityYantai 264005China School of energy and power engineering Shandong UniversityJinan 250061China Shandong laboratory of Advanced Materials and Green Manufacturing(Yantai) Yantai 264001China

The electrochromic(EC)mechanisms of inorganic materials are usually based on reversible cation insertion/extraction or metal deposition/dissolution,which are plagued by ion trapping and dendrite growth,respectively.In this paper,a novel conversion-type electrochromic mechanism is proposed,by making good use of the CuI/Cu redox couple.This CuI-based electrochromic system shows a neutral color switching from transparent and dim grey.By simply increasing the bleaching voltage,I_(3)^(-)/I^(-)redox couple can be further activated.The generated I_(3)^(-)will readily react with Cu,effectively improving the conversion reversibility and thereby rejuvenating the degraded electrochromic performance.Thanks to the well-designed electrode and the self-healing ability,this conversion electrochromic system achieves rapid response times(tcoloring:23 s,tbleaching:6 s),decant optical modulation amplitude(26.4%),high coloration efficiency(86.15 cm^(2)·C^(-1)),admirable cyclic durability(without performance degradation after 480 cycles)and excellent optical memory ability(transmittance variation<1%after 10 h open-circuit storage).The establishment of this conversion-type electrochromism may inspire the exploration of novel electrochromic materials and devices.

关键词： electrochromic CuI conversion reaction self-healing neutral color

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Asymmetrically coordinated single atom Cu catalyst with unsaturated C-Cu-N structure for CO_(2) reduction to CO

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Nano Research 2024年第5期17卷 3911-3918页

作者： Zheng Liu Yuxuan Liu Jingqiao Zhang Ting Cao Zhiyi Sun Juzhe Liu Huishan Shang State key laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China SEPA key laboratory of Eco-Industry Chinese Research Academy of Environmental SciencesBeijing 100012China The key laboratory of Resources and Environmental system Optimization Ministry of EducationCollege of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China School of Chemical engineering Zhengzhou UniversityZhengzhou 450001China

Single atom catalysts(SACs)play a crucial role in energy catalysis due to their distinct coordination environment and high atomic utilization efficiency.This study focuses on the synthesis of a monatomic Cu catalyst with Cu-N1C1 coordination anchored to N-doped Ti_(3)C_(2)T_(x) MXene(Cu SA@N-Ti_(3)C_(2)T_(x))to achieve efficient reduction of CO_(2) to CO.Detailed characterization,including morphology and multispectral analysis,confirmed the uniform distribution of asymmetrically coordinated Cu atoms in unsaturated C-Cu-N bridge fragments on Ti_(3)C_(2)T_(x).The Cu SA@N-Ti_(3)C_(2)T_(x) catalyst exhibited an excellent CO selectivity with Faraday efficiency of 97.4%at-0.58 V vs.reversible hydrogen electrode(RHE)and satisfactory durability.The in situ X-ray absorption fine structure(XAFS)results confirmed that the carbon dioxide reduction reaction(CO_(2)RR)product distribution is mainly affected by potential-dependent valence change of Cu species.These findings highlight the extensive potential of tuning coordination structure of MXene-based single-atom catalysts for CO_(2) reduction reactions.

关键词： cooper single atom atomic regulation MXene Ti_(3)C_(2)T_(x) CO_(2)reduction

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Multi-Resource Collaborative Service Restoration of a Distribution Network with Decentralized Hierarchical Droop Control

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Protection and Control of Modern power systems 2024年第1期9卷 19-37页

作者： Wei Zhang Cong Zhang Jiayong Li Lipeng Zhu Shiran Cao Wen Huang Zhikang Shuai college of Electrical and Information engineering Hunan UniversityChangshaChina Hunan University ChangshaChina CSEE Journal of power and energy systems Chinese Journal of Electrical Engineerin

To improve the resilience of distribution networks(DNs)in the event of extreme natural disasters such as typhoons and rainstorms,it is imperative to efficiently implement distribution service restoration(DSR)to restore loads as soon as possible.In previous studies,DSR has mainly adopted the distributed resource model with droop or PQ control.This inhibits the exploitation of the potential of distributed generators(DGs)in load restoration when the DN loses support from the upstream transmission network.Thus,this paper proposes a multi-resource collaborative service restoration(MRCSR)approach for DNs incorporating local soft open points,DGs,and tie switches.The MRCSR model is developed by integrating a decentralized hierarchical droop control(DHDC)strategy and incorporating the frequency and voltage features of the load demand.A two-stage iterative feedback optimization(TSIFO)algorithm is then developed to analyze the MRCSR model in an accurate and efficient manner.Finally,the proposed model and algo-rithm are tested on the modified IEEE 33-bus system and a practical distribution system of the Taiwan power Company to verify their effectiveness and advantages over existing approaches.

关键词： service Service integrating

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An improved nonlinear onboard adaptive model for aero-engine performance control

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Chinese Journal of Aeronautics 2023年第10期36卷 317-334页

作者： Qian CHEN Hanlin SHENG Tianhong ZHANG jiangsu province key laboratory of aerospace power system College of Energy and Power EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

The onboard adaptive model can achieve the online real-time estimation of performance parameters that are difficult to measure in a real aero-engine,which is the key to realizing modelbased performance control.It must possess satisfactory numerical stability and estimation accuracy.However,the positive definiteness of the state covariance matrix may be destroyed in filter estimation because of the existence of some uncertain factors,such as the accumulated measurement error,noise,and disturbance in the strongly nonlinear engine system,inevitably causing divergence of estimates of Cholesky decomposition-based Spherical Unscented Kalman Filter(SUKF).Therefore,this paper proposes an improved SUKF algorithm(iSUKF)and applies it to the performance degradation estimation of the engine.Compared to SUKF,the iSUKF mainly replaces the Cholesky decomposition with the Singular Value Decomposition(SVD),which is numerically stable without any strict requirement for the state covariance matrix.Meanwhile,a correction factor is designed to assess the measurement deviation between the real engine and the nonlinear onboard model to correct the state covariance matrix,thus maintaining better numerical stability of parameters estimated by the filter.Then,an offline correction strategy is also proposed to eliminate the influence of the degradation of unestimated health parameters or the filter’s inadequate estimation of the coupled health parameters.This action effectively promotes the onboard adaptive model’s estimation accuracy concerning the degradation of the engine’real health parameters and its performance parameters.Finally,the simulation results show that the iSUKF can maintain the numerical stability of the filter’s estimation of health parameters.Compared with the existing methods,the offline correction strategy improves the estimation accuracy of the iSUKF-based nonlinear onboard adaptive model for the performance parameters of the real engine by more than 50%.The proposed method will provide feasible technical support for

关键词： Aero-engine Onboard adaptive model Spherical unscented Kalman filter Parameter estimation iSUKF

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Neural network-based model predictive control with fuzzy-SQP optimization for direct thrust control of turbofan engine

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Chinese Journal of Aeronautics 2022年第12期35卷 59-71页

作者： Yangjing WANG Jinquan HUANG Wenxiang ZHOU Feng LU Wenhao XU jiangsu province key laboratory of aerospace power system College of Energy and Power EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

A nonlinear model predictive control method based on fuzzy-Sequential Quadratic Programming(SQP)for direct thrust control is proposed in this paper for the sake of improving the accuracy of thrust control.The designed control system includes four parts,namely a predictive model,rolling optimization,online correction,and feedback correction.Considering the strong nonlinearity of engine,a predictive model is established by Back Propagation(BP)neural network for the entire flight envelope,whose input and output are determined with random forest algorithm and actual situation analysis.Rolling optimization typically uses SQP as the optimization algorithm,but SQP algorithm is easy to trap into local optimization.Therefore,the fuzzy-SQP algorithm is proposed to prevent this disadvantage using fuzzy algorithm to determine the initial value of SQP.In addition to the traditional three parts of model predictive control,an online correction module is added to improve the predictive accuracy of the predictive model in the predictive time domain.Simulation results show that the BP predictive model can reach a certain degree of predictive accuracy,and the proposed control system can achieve good tracking performance with the limited parameters within the safe range。

关键词： Direct thrust control Fuzzy-SQP algorithm Limit protection Neural network Nonlinear model predictive control Random forest Turbofan engine

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