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Improved Proximal Policy Optimization Algorithm for Sequential Security-constrained Optimal power Flow Based on Expert Knowledge and Safety Layer

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Journal of Modern power Systems and Clean {1. 2024年第3期12卷 742-753页

作者： Yanbo Chen Qintao Du Honghai Liu Liangcheng Cheng Muhammad Shahzad Younis State key {1. of Alternate Electrical power System with Renewable energy Sources and School of Electrical&Electronic Engineering North China Electric Power UniversityBeijing 102206China School of Engineering Xining UniversityXining 810008Chinaand Key Laboratory of Smart Operation of New Energy Power SystemMinistry of EducationQinghai UniversityXining 810016China China Electric power Research Institute Nanjing 210003China National University of Sciences and technology Islamabad44000Pakistan

In recent years,reinforcement learning(RL)has emerged as a solution for model-free dynamic programming problem that cannot be effectively solved by traditional optimization *** has gradually been applied in the fields such as economic dispatch of power systems due to its strong selflearning and self-optimizing ***,existing economic scheduling methods based on RL ignore security risks that the agent may bring during exploration,which poses a risk of issuing instructions that threaten the safe operation of power ***,we propose an improved proximal policy optimization algorithm for sequential security-constrained optimal power flow(SCOPF)based on expert knowledge and safety layer to determine active power dispatch strategy,voltage optimization scheme of the units,and charging/discharging dispatch of energy storage *** expert experience is introduced to improve the ability to enforce constraints such as power balance in training process while guiding agent to effectively improve the utilization rate of renewable ***,to avoid line overload,we add a safety layer at the end of the policy network by introducing transmission constraints to avoid dangerous actions and tackle sequential SCOPF *** results on an improved IEEE 1.8-bus system verify the effectiveness of the proposed algorithm.

关键词： Sequential security-constrained optimal power flow(SCOPF) expert experience safety layer renewable energy safe reinforcement learning

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Design strategy and relevant flow mechanisms of highly loaded 3D compressor tandem cascades

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Chinese Journal of Aeronautics 2024年第7期37卷 220-235页

作者： Xiaochen MAO Yunyu WANG Zhihua DING Hao CHENG Bo LIU School of power and {1. Northwestern Polytechnical UniversityXi’an 710129China The National key {1. of Science and technology on Aerodynamic Design and Research Xi’an 710129China Xi’an Thermal power Research Institute Co.Ltd Xi’an 710072China

To investigate the design strategy of highly loaded tandem cascades at both the midspan and endwall,the overall performance and flow mechanisms of four typical tandem cascades based on the optimization were analyzed from multiple perspectives *** results show that the interference effects on the Front Blade(FB)and Rear Blade(RB)should not be overlooked during the design phase,and the design strategies at the midspan and endwall are completely *** the midspan,the optimization aims to increase the interference effects and the strength of the gap jet while maintaining the same load on the FB and ***,the endwall optimal airfoil exhibits weakening interference effects,advancement of the gap jet location,and load transfer from the FB to *** further analysis of flow characteristics,the midspan optimal airfoil is beneficial for inhibiting the low-energy fluid from interacting with the suction surface of RB under the design condition,but results in earlier occurrence of corner *** endwall optimal airfoil helps suppress the development of the secondary flow and delay the onset of corner ***,by combining the benefits of these two design approaches,additional forward sweep effects are achieved,further enhancing the performance of the tandem cascade.

关键词： Tandem cascade Interference effect Vortex structure Load split Compressor

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Distributed Stochastic Scheduling of Massive Backup Batteries in Cellular Networks for Operational Reserve and Frequency Support Ancillary Services

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Journal of Modern power Systems and Clean {1. 2024年第2期12卷 393-404页

作者： Kun Li Jiakun Fang Xiaomeng Ai Shichang Cui Rongkang Zhao Jinyu Wen State key {1. of advanced Electromagnetic Engineering and technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China IEEE

Base station(BS)backup batteries(BSBBs),with their dispatchable capacity,are potential demand-side resources for future power *** enhance the power supply reliability and post-contingency frequency security of power systems,we propose a two-stage stochastic unit commitment(UC)model incorporating operational reserve and post-contingency frequency support provisions from massive BSBBs in cellular networks,in which the minimum backup energy demand is considered to ensure BS power supply *** energy,operational reserve,and frequency support ancillary services are co-optimized to handle the power balance and post-contingency frequency security in both forecasted and stochastic variable renewable energy(VRE)***,we propose a dedicated and scalable distributed optimization framework to enable autonomous optimizations for both dispatching center(DC)and *** BS model parameters are stored and processed locally,while only the values of BS decision variables are required to upload to DC under the proposed distributed optimization framework,which safeguards BS privacy *** studies on a modified IEEE 1.-bus system demonstrate the effectiveness of the proposed method in promoting VRE accommodation,ensuring post-contingency frequency security,enhancing operational economics,and fully utilizing BSBBs'energy and power ***,the proposed distributed optimization framework has been validated to converge to a feasible solution with near-optimal performance within limited ***,numerical results on the Guangdong 500 kV provincial power system in China verify the scalability and practicality of the proposed distributed optimization framework.

关键词： Base station backup battery operational reserve frequency security distributed optimization privacy

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Nanodiamond:a promising metal-free nanoscale material in photocatalysis and electrocatalysis

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Rare Metals 2024年第8期43卷 3501-3552页

作者： Xiao-Wu Gao Zi-Wei Zhao Yang He Sai-Fei Fan Ke-Ran Jiao Si-Yu Lou Xin-Yue Han Peng-Fei Song Rong Cai Zhun Hu Zhong-Jie Jiang Yong-Jie Wang Jia-Qi Zhu Guangdong Provincial key {1. of Semiconductor Optoelectronic Materials and Intelligent Photonic Systems School of ScienceHarbin Institute of TechnologyShenzhen 518055China National key {1. of Science and technology on advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150080China School of advanced {1. Xi'an Jiaotong-Liverpool UniversitySuzhou215000China Department of Biosciences Rice UniversityHoustonTX 77251USA Institute of Industrial Catalysis School of Chemical Engineering and TechnologyXi'an Jiaotong UniversityXi'an 710049China Guangzhou key {1. for Surface Chemistry of energy Materials New Energy Research Institute&Guangdong Engineering and Technology Research Center for Surface Chemistry of Energy MaterialsCollege of Environment and EnergySouth China University of TechnologyGuangzhou 510006China

Benefiting from its surface-rich functional groups,eco-friendliness,impressive electrochemical properties,excellent light absorption,structural tunability at the atomic/morphological level,and ultra-high stability under harsh conditions,nanodiamond has emerged as a promising carbon-based non-metallic material in the field of energy conversion such as electrocatalysis and ***,nanodiamond,as a new generation of green catalysts,can overcome the poisoning of catalysts by complex pollutants in {1. oxidation processes,thus effectively removing organic matter from water,which is unparalleled in reducing the cost of water purification and avoiding secondary cross-contamination of water by traditional heavy metal-based ***,we review the research and development of nanodiamonds as major electrocatalysts and photocatalysts for energy conversion and for air/water treatment for environmental *** relevant properties,trimming strategy,mechanistic understanding,and design principles of nanodiamond as a catalyst are described,as well as the challenges and prospects of this emerging field.

关键词： Carbon materials Nanodiamond Electrocatalysis Photocatalysis energy conversion Pollutant treatment

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Impact of Ni particle size on CO_(2)activation and CO formation during reforming process:A density functional theory study

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Frontiers in energy 2024年第4期18卷 525-534页

作者： Juntian NIU Shengzhuo CHEN Xianrong ZHENG Haiyu LIU Yan JIN Jingyu RAN College of Electrical and power Engineering Taiyuan University of TechnologyTaiyuan 030024China key {1. of Low-grade energy Utilization Technologies and Systems(Ministry of Education) Chongqing UniversityChongqing 400044China

In recent years,the dry reforming of methane(DRM)reaction has gained widespread attention due to its effective utilization of two major greenhouse *** Ni-based catalysts for DRM exhibit a strong dependence on particle size,however,the reaction mechanisms involved remain *** this work,the effect of metal particle size on CO_(2)activation and CO formation was explored in the DRM reaction using the density functional ***/MgO(x=1.,25,37)was constructed to investigate the CO_(2)activation and the formation of CO during the DRM *** is found that CO_(2)is more inclined to undergo chemisorption on Nix/MgO before *** the variation in particle size,the main activation pathway of CO_(2)on the catalyst *** the smallest Ni1./MgO,CO_(2)tends to directly dissociate,while on the larger Ni25/MgO and Ni37/MgO,the hydrogenation dissociation of CO_(2)is more kinetically *** to Ni1./MgO and Ni37/MgO,the oxidation of surface C atoms and the oxidation of CH occur more readily on Ni25/*** indicates that C atoms are less likely to form on Ni25 particle and are more easily to be *** some extent,the results suggest that Ni25/MgO exhibits superior resistance to carbon formation.

关键词： particle size Ni/MgO catalyst CO_(2)activation CO formation

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High-stability temperature control and frequency-domain analysis of sandwich-like insulation design based on phase change materials for satellite thermal management

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Science China(Technological Sciences) 2024年第8期67卷 2387-2404页

作者： WANG ZiHan HE ChenBo HU Yang TANG GuiHua key {1. of Thermo-Fluid Science and Engineering Ministry of EducationSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

High-stability thermal management is critical for the measurements of high sensitivity for temperature, but also challenging because any small thermal disturbances could lead to unacceptable temperature fluctuations. The present work delivers a design for passive temperature control, customized for a component in the satellites for gravitational wave detection. A novel sandwichlike structure is proposed with the configurations of proper materials, consisting of a layer of insulation material and two layers of nanocomposite phase change materials, bringing an integration of heat insulation and absorption/storage. Its performance is examined using an improved thermal network model and the revised transfer function method(TFM). The basic results of the two methods are validated by present COMSOL simulations and available numerical and experimental data in the literature. An effective reduction of temperature fluctuation is achieved to the scale of 0.1.K, even under two thermal disturbances from different directions: a radiative heat flux of 20 W m~(-2)(inside) and a temperature fluctuation of about 20 K(outside). Moreover,the TFM is employed to analyze the effects of the frequency of thermal disturbance: excellent damping performance is obtained for over 3.2 mHz and the underlying mechanism is discussed. Overall, the present design is expected to be combined with active temperature control to explore more possible ways for temperature control with higher stability.

关键词： temperature control sandwich insulation structure phase change material thermal network model transfer function method

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Regulating the inner Helmholtz plane structure at the electrolyte-electrode interface for highly reversible aqueous Zn batteries

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Journal of energy Chemistry 2024年第8期95卷 57-67,I0002页

作者： Jianghe Liu Sanlue Hu Hexin Guo Guobin Zhang Wen Liu Jianwei Zhao Shenhua Song Cuiping Han Baohua Li Shenzhen key {1. on power Battery Safety and Shenzhen Geim Graphene Center Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055GuangdongChina Shenzhen key {1. of advanced Materials School of Materials Science and EngineeringHarbin Institute of TechnologyShenzhen 518055GuangdongChina Faculty of Materials Science and energy Engineering/Institute of {1. for Carbon Neutrality Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055GuangdongChina Shenzhen HUASUAN technology Co. Ltd.Shenzhen 518055GuangdongChina

The development of aqueous Zn batteries is limited by parasitic water reactions,corrosion,and dendrite *** address these challenges,an inner Helmholtz plane(IHP)regulation method is proposed by employing low-cost,non-toxic maltitol as the electrolyte *** preferential adsorption behavior of maltitol can expel the water from the inner Helmholtz plane,and thus hinder the immediate contact between Zn metal and H_(2)***,strong interaction between maltitol and H_(2)O molecules can restrain the activity of H_(2)***,the"IHP adsorption effect"along with the low LUMO energy level of maltitol-CF_(3)SO_(3)^(-)can promote the in-situ formation of an organic-inorganic complex solid electrolyte interface(SEI)*** a result,the hydrogen/oxygen evolution side reaction,corrosion,and dendrites issues are effectively suppressed,thereby leading to highly reversible and dendrite-free Zn plating/*** Zn‖I_(2)battery with hybrid electrolytes also demonstrates high electrochemical performance and ultralong cycling stability,showing a capacity retention of 75%over 20000 charge-discharge cycles at a large current density of 5 A g^(-1..In addition,the capacity of the device has almost no obvious decay over20000 cycles even at-30℃.This work offers a successful electrolyte regulation strategy via the IHP adsorption effect to design electrolytes for high-performance rechargeable Zn-ion batteries.

关键词： Inner Helmholtz plane Adsorption effect Dendrite suppression SEI layer Zn||I_(2)battery

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Micro-nanoarchitectonic of aluminum-hydrogel propellant with static stability and dynamic rheology

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Frontiers of Chemical Science and Engineering 2024年第4期18卷 87-96页

作者： Huiyan Guo Huaiyu Li Hongzhi Zhang Lun Pan Chengxiang Shi Kang Xue Xiangwen Zhang Ji-Jun Zou key {1. for advanced Fuel and Propellant of Ministry of Education School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

The aluminum-water system is a promising propellant due to high energy and low signal characteristics,and the gel form is easier to store and *** this work,hydrogels of water and aluminum particles were prepared using the low-molecular-weight gellant *** various physical properties of gel systems,including the water loss rate,phase transition temperature,and centrifugal stability at different gellant and aluminum contents,were *** properties were assessed through shear thinning tests,thixotropy tests,strain sweep analysis,and frequency sweep *** microstructure of the gel was obtained through scanning electron microscopy *** results show that the aluminum-hydrogel network structure is composed of micron-scale aluminum and agarose nanosheets,and the unique micro-nanostructure endows the gel with excellent mechanical strength and thermal stability,which improve with increasing gellant and aluminum ***,the gel with 2% agarose and 20% aluminum had the best performance;the storage modulus reached 90647 Pa,which was within the linear viscoelastic region,and the maximum withstand pressure was 1.1.2 kPa,which was 1.8.8% greater than that of the pure ***,the gel demonstrates remarkable shear thinning behavior and can undergo gel-sol transformation upon shearing or heating to exceeding 1.4℃.

关键词： aluminum-water propellant gelled propellant rheological property mechanical strength

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Exceptional mechanical performance and macroscale superlubricity enabled by core-shell-like MoS_(2)/B_(4)C film

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Science China(Technological Sciences) 2024年第7期67卷 2018-2030页

作者： REN SiMing GAO ZhenRong FAN Xin WANG HaiXin WANG LiPing key {1. of advanced Marine Materials Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China

Molybdenum disulfide(MoS_(2)) films are widely deployed in industrial applications owing to their inherent interlayer slip characteristics, offering energy consumption savings and prolonged mechanical part performance. Nevertheless, their practical utility is limited by environmental constraints and the limitations of preparation techniques, which hinder the attainment of robust superlubricity(friction coefficient 1.. Herein, through magnetron sputtering {1., we synthesize a core-shell-like nanocomposite composed of MoS_(2)nanosheets encapsulating B_(4)C. The core-shell-like structure enables the resulting films to preferentially grow crystalline MoS_(2), providing them with outstanding mechanical properties and efficient lubrication over a wide range of temperatures. Remarkably, such film achieves robust macroscale superlubricity and an ultralow wear rate(1.7 ×1.^(-8)mm^(3)N-1.^(-1.) under high contact stress in a mild vacuum environment. This noteworthy outcome is primarily attributable to the self-segmentation of the macroscale contact interface during the friction process, involving:(1. a large amount of wear debris is embedded into the wear track to create extensive micro-sized asperities;(2) a nanolayer of amorphous carbon enriched with oxide nanoparticles is formed on the uppermost part of these asperities;(3) numerous incommensurate nanocontacts comprising nanoparticles and highly oriented MoS_(2)nanosheets are established, culminating in the achievement of robust superlubricity. Our pioneering design, coupled with the elucidation of the underlying superlubricity mechanism, holds significant promise for advancing the development of robust and high-performance lubricants.

关键词： MoS_(2)/B_(4)C nanocomposites core-shell-like structure H/E ratio high-temperature friction macroscale superlubricity

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Numerical study on the effective thermal conductivity and thermal tortuosity of porous media with different morphologies

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Science China(Technological Sciences) 2024年第6期67卷 1685-1694页

作者： DU Shen LI Dong LI Meng-Jie HE Ya-Ling key {1. of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China

Effective thermal conductivity and thermal tortuosity are crucial parameters for evaluating the effectiveness of heat conduction within porous *** direct pore-scale numerical simulation method is applied to investigate the heat conduction processes inside porous structures with different *** thermal conduction performances of idealized porous structures are directly compared with real foams across a wide range of *** foam structures are reconstructed using X-ray computed tomography and image processing techniques,while Kelvin and Weaire-Phelan structures are generated through periodic unit cell *** detailed temperature fields inside the porous structures are determined by solving the heat conduction equation at the pore *** results present that the equivalent thermal conductivity of Kelvin and Weaire-Phelan structures is similar to and greater than that of the real foam structure with the same strut *** thermal tortuosity of real foam structure is relatively larger and the heat conduction path becomes straighter by adopting the anisotropic *** thermal tortuosity of the fluid channels for Kelvin,Weaire-Phelan,and real foam structures is close to *** thermal conductivity of porous structures with heat transfer fluid increases as the thermal conductivity ratio of fluid to solid becomes larger.A small porosity of porous media leads to a larger equivalent thermal conductivity due to the dominant contribution of porous skeleton in the heat conduction *** derived from parallel and series models,as well as the Maxwell-Eucken models,provide decent predictions of effective thermal conductivity,with an average error of less than 8%in the entire range of thermal conductivity ratio.

关键词： volumetric solar receiver porous morphology direct pore-scale simulation equivalent thermal conductivity thermal tortuosity empirical correlation

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