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Design Optimization and Operating Performance of S-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand Scenarios

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Journal of Thermal Science 2024年第1期33卷 190-206页

作者： yang Jingze yang zhen DUAN Yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce *** the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand *** addition,the cycle design condition will directly affect the off-design *** this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced *** show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient *** average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient *** multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature *** the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance

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Sum-Rate Maximization in Active RIS-Assisted Multi-Antenna WPCN

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China Communications 2024年第6期21卷 23-39页

作者： Jiang Jie Lyu Bin Chen Pengcheng yang zhen School of Communications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology Nanjing UniversityNanjing 210003China

In this paper,we propose an active reconfigurable intelligent surface(RIS)enabled hybrid relaying scheme for a multi-antenna wireless powered communication network(WPCN),where the active RIS is employed to assist both wireless energy transfer(WET)from the power station(PS)to energyconstrained users and wireless information transmission(WIT)from users to the receiving station(RS).For further performance enhancement,we propose to employ both transmit beamforming at the PS and receive beamforming at the *** formulate a sumrate maximization problem by jointly optimizing the RIS phase shifts and amplitude reflection coefficients for both the WET and the WIT,transmit and receive beamforming vectors,and network resource *** solve this non-convex problem,we propose an efficient alternating optimization algorithm with the linear minimum mean squared error criterion,semidefinite relaxation(SDR)and successive convex approximation ***,the tightness of applying the SDR is *** results demonstrate that our proposed scheme with 10 reflecting elements(REs)and 4 antennas can achieve 17.78%and 415.48%performance gains compared to the single-antenna scheme with 10 REs and passive RIS scheme with 100 REs,respectively.

关键词： active reconfigurable intelligent surface beamforming sum-rate maximization wireless powered communication network

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Examining the Spatiotemporal Dynamics and Determinants of Land Urbanization in Prefecture-level Cities,China

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Chinese Geographical Science 2024年第1期34卷 19-33页

作者： yang zhen ZHU Huxiao ZHANG Xinlin OU Xiangjun School of Geography Geomatics and Planning&Urban-rural Integration Development Research InstituteJiangsu Normal UniversityXuzhou221116China

Examining the spatiotemporal dynamics and determinants of land urbanization is critical for promoting healthy urban development and the rational use of land *** on the dataset consisting of land use change data and selected factors in 2010 and2020,this study used visual analysis to reveal the spatiotemporal dynamics of land urbanization across prefecture-level cities in ***,the driving forces underlying land urbanization were examined by using geographical detector *** are the findings:1)we find that there exist notable spatial variances in land urbanization across prefecture-level ***,the differentiation in land urbanization between the northern and southern cities is more pronounced than that between the coastal and inland cities,or between the eastern and western ***-level cities located in central and western China have experienced the most rapid growth in land ***,the growth rate in northeastern China is the lowest,while the velocity in eastern China remains relatively *** using spatial autocorrelation analysis,this study reveals that the land urbanization level in prefecture-level cities has significant spatial agglomeration.2)We further find that land urbanization in China is influenced by factors related to urban land supply and demand,and urban population growth,economic growth,land financial and political incentive have greater impact on land urbanization than other factors.3)We also find that the impacts of determinants on China’s land urbanization vary over time,the explanatory power of economic development increased,while the explanatory power of state forces *** argue that integrating the supply and demand factors of land urbanization can provide a more comprehensive understanding of the driving mechanisms underlying land urbanization in China and other transitional countries,and help decision-makers in these countries formulate more detailed and specif

关键词： land urbanization spatial pattern influencing factor geographical detector China

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ControlService: a containerized solution for control-algorithm-as-a-service in cloud control systems

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Science China(Information Sciences) 2024年第08期67卷 172-189页

作者： Chenggang SHAN Runze GAO zhen yang Wei ZHANG Yuanqing XIA School of Artificial Intelligence Zaozhuang University School of Automation Beijing Institute of Technology

As an extension of networked control systems, cloud control systems(CCSs) have emerged as a new control paradigm to improve the service quality of emerging control missions, such as data-driven modeling and automated vehicles. Existing studies have used the workflow-based restructured method to optimize the computation-intensive algorithms in the CCSs. However, the challenges here are how to define and submit these algorithms' workflows as cloud services and execute these algorithms' workflows in a containerized manner. Based on these challenges, we propose a containerized solution for the control-algorithm-as-a-service(C3aS) in the CCSs, namely Control Service. It offers the control algorithm as a cloud workflow service and uses a customized workflow engine to realize the containerized execution. First, we employ a cloud workflow representation method to define a control algorithm into an abstract cloud workflow form. Afterward, we provide a cloud service representation of the abstract cloud workflow. Next, we design a workflow engine and submit the cloud service to this workflow engine to implement containerized execution of this cloud service in the CCSs. In the experiment, we discuss the cloud service form and containerized implementation of the subspace identification method. Experimental results show that the proposed Control Service has significant performance advantages in computational time, reduction percentage, and speedup ratio compared with the baseline method.

关键词： cloud control systems control-algorithm-as-a-service containerization workflow engine cloud workflow service subspace identification

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Sedimentary Environment and Mineralization of the Black Shale Polymetallic Layer in the Early Cambrian,SW China:Constraints from in situ LA-ICP-MS Analysis of Pyrite

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 416-429页

作者： yang zhen FU Yong LI Chao CAI Xi GUO Chuan College of Eco-Environmental Engineering Guizhou Minzu UniversityGuiyang 550025China College of Resources and Environmental Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Karst Georesources and the Environment Ministry of EducationGuizhou UniversityGuiyang 500025China National Research Center for Geoanalysis Chinese Academy of Geological SciencesBeijing 100037China

A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou *** mineral that makes up the polymetallic layer is related to the sedimentary *** analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of *** results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan *** isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional *** sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from ***,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.

关键词： sedimentary environment black shale polymetallic layer pyrite early Cambrian

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Cooperative UAV search strategy based on DMPC-AACO algorithm in restricted communication scenarios

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Defence Technology（防务技术） 2024年第1期31卷 295-311页

作者： Shiyuan Chai zhen yang Jichuan Huang Xiaoyang Li Yiyang Zhao Deyun Zhou School of Electronics and Information Northwestern Polytechnical UniversityXi'an 710072China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China The 93147th Unit of Chinese PLA Air Force Chengdu610091China

Improvement of integrated battlefield situational awareness in complex environments involving dynamic factors such as restricted communications and electromagnetic interference(EMI)has become a contentious research *** certain mission environments,due to the impact of many interference sources on real-time communication or mission requirements such as the need to implement communication regulations,the mission stages are represented as a dynamic combination of several communication-available and communication-unavailable ***,the data interaction between unmanned aerial vehicles(UAVs)can only be performed in specific communication-available *** cooperative search algorithms cannot handle such situations *** solve this problem,this study constructed a distributed model predictive control(DMPC)architecture for a collaborative control of UAVs and used the Voronoi diagram generation method to re-plan the search areas of all UAVs in real time to avoid repetition of search areas and UAV collisions while improving the search efficiency and safety *** attention mechanism ant-colony optimization(AACO)algorithm is proposed for UAV search-control decision *** search strategy is adaptively updated by introducing an attention mechanism for regular instruction information,a priori information,and emergent information of the mission to satisfy different search expectations to the maximum *** results show that the proposed algorithm achieves better search performance than traditional algorithms in restricted communication constraint scenarios.

关键词： Unmanned aerial vehicles(UAV) Cooperative search Restricted communication Mission planning DMPC-AACO

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Influence of filler characteristics on particle removal in fluid catalytic cracking slurry under an alternating electric field

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Petroleum Science 2024年第3期21卷 2102-2111页

作者： Qiang Li Hui-zhen yang Can yang Qing-Zhu Qiu Wei-Wei Xu Zhao-Zeng Liu College of New Energy China University of Petroleum(East China)

The characteristics of the packing material under an alternating electric field are an important factor in the removal of FCCS particles. In this study, the electric field distribution of a separation unit consisting of packed spheres under an alternating electric field is simulated, and the movement mechanism of catalyst particles is analysed. An "effective contact point" model is derived to predict the adsorption of filler contact points on catalyst particles under the alternating electric field, and the model is validated by simulations and experiments. The numerical calculation and experimental results indicate that the electrical properties of the filler spheres, the filler angle θ, and the frequency f of the alternating electric field affect the adsorption of catalyst particles. As the frequency of the electric field increases, the particle removal efficiency of the high-conductivity filler(silicon carbide) increases and then settles, and the separation efficiency of the low-conductivity filler(glass, zirconia) is not sensitive to the change in electric field frequency.

关键词： Fluid catalytic cracking slurry (FCCS) Particle AC electric field Fillers Removal

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Structural disruption of melanin-like polymers with boosted UV protection

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Science China Chemistry 2024年第5期67卷 1653-1663页

作者： zhen yang Xianheng Wang Wanjie Bai Zikun Zou Haoxing Wu Yiwen Li Department of Radiology Huaxi MR Research CenterFunctional and Molecular Imaging Key Laboratory of Sichuan ProvinceNational Clinical Research Center for GeriatricsWest China HospitalSichuan UniversityChengdu 610041China College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China

Manipulating the energy structure of materials represents an efficient way to regulate their light absorption behaviors. For example, constructing donor-acceptor(D-A) structures to increase the polarizability and reduce the energy bandgap of local molecules has been widely used in the field of organic photovoltaics with ordered structures. Remarkably, even in disordered and chaotic systems such as melanin-like polydopamine(PDA), visible and near-infrared light absorption can be significantly improved using this strategy. However, there has been a noticeable dearth of research on the ultraviolet(UV) light absorption regulation of bioinspired polymers with disordered and chaotic architectures by tailoring the D-A microstructures. In this study, a series of benzoheterocyclic molecules with strong electron-donating features screened by molecular simulation calculations were involved in disrupting the D-A structures within PDA. The destruction of D-A structures promoted the increase of the energy band gap and finally boosted the UV absorption of PDA. The resulting PDA nanoparticles with enhanced UV absorption were further employed to fabricate UV shielding composite films to protect the growth of plants from harmful UV radiation. This research may open up new avenues for structural disruption of bioinspired polymers for enhanced photoprotection applications.

关键词： melanin-like polymers polydopamine D-A structure UV absorption photoprotection

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Conservation genomics provides insights into genetic resilience and adaptation of the endangered Chinese hazelnut, Corylus chinensis

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Plant Diversity 2024年第3期46卷 294-308页

作者： zhen yang Lisong Liang Weibo Xiang Lujun Wang Qinghua Ma Zhaoshan Wang Key Laboratory of Tree Breeding and Cultivation National Forestry and Grassland AdministrationResearch Institute of ForestryChinese Academy of ForestryBeijing 100091China National Engineering Research Center of Eco-Environment Protection for yangtze River Economic Belt China Three Gorges CorporationBeijing 100083China Rare Plants Research Institute of yangtze River China Three Gorges CorporationYichang 443133China Research Institute of Economic Forest Cultivation and Processing Anhui Academy of ForestryHefei 230031China

Global climate change has increased concerns regarding biodiversity ***,many key conservation issues still required further research,including demographic history,deleterious mutation load,adaptive evolution,and putative *** we generated the first chromosome-level genome of the endangered Chinese hazelnut,Corylus chinensis,and compared the genomic signatures with its sympatric widespread ***-C yunnanensis *** found large genome rearrangements across all Corylus species and identified species-specific expanded gene families that may be involved in *** genomics revealed that both *** and the *** complex had diverged into two genetic lineages,forming a consistent pattern of southwestern-northern *** size of the narrow southwestern lineages of both species have decreased continuously since the late Miocene,whereas the widespread northern lineages have remained stable(***) or have even recovered from population bottlenecks(*** complex) during the *** with ***-C. yunnanensis complex,*** showed significantly lower genomic diversity and higher inbreeding ***,*** carried significantly fewer deleterious mutations than ***-C. yunnanensis complex,as more effective purging selection reduced the accumulation of homozygous *** also detected signals of positive selection and adaptive introgression in different lineages,which facilitated the accumulation of favorable variants and formation of local ***,both types of selection and exogenous introgression could have mitigated inbreeding and facilitated survival and persistence of ***,our study provides critical insights into lineage differentiation,local adaptation,and the potential for future recovery of endangered trees.

关键词： Conservation genomics Demographic history Inbreeding Genetic load Runs of homozygosity Local adaptation

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Tuning the ferroelectricity of Hf0.5Zr0.5O2 with alloy electrodes

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Science China(Information Sciences) 2024年第8期67卷 321-330页

作者： Keqin LIU Bingjie DANG Zhiyu yang Teng ZHANG zhen yang Jinxuan BAI Zelun PAN Ru HUANG Yuchao yang Beijing Advanced Innovation Center for Integrated Circuits School of Integrated Circuits Peking University School of Electronic and Computer Engineering Peking University Center for Brain Inspired Chips Institute for Artificial Intelligence Peking University Center for Brain Inspired Intelligence Chinese Institute for Brain ResearchBeijing

Tuning ferroelectricity of Hf0.5Zr0.5O2is crucial for facilitating its practical applications in various fields, including in-memory and neuromorphic computing. Previous studies have revealed that the electrodes have a significant influence on ferroelectricity, and changing electrode materials can realize different but discrete ferroelectric polarization values. Here, we introduce an alloy-electrode method, in order to achieve gradual and accurate modulation of ferroelectric polarization, especially useful for matching the polarization charges at the interface of ferroelectric insulators and ferroelectric semiconductors. Au and W electrodes are chosen as baselines for realizing weak and strong ferroelectric polarization, where the intermediate states can be achieved by adjusting the ratio of metals in the Au-W alloy. To demonstrate the generality of this approach, the Cu-W alloy electrode is also realized for tuning ferroelectric polarization. The effect of alloy electrodes on device leakage current, endurance, and retention is evaluated. In addition, the temperature stability of ferroelectric capacitors is tested, where limited changes in both remnant polarization and coercive voltages are observed, showing the great potential of the ferroelectric hafnium oxide. Such gradual modulation of ferroelectric polarization could facilitate the application of Hf0.5Zr0.5O2in in-memory and neuromorphic computing.

关键词： ferroelectric hafnium oxide alloy electrode gradual modulation temperature stability

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