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Performance Analysis of a Coupled System based on Organic Rankine Cycle and Double Effect Absorption Refrigeration for Waste Heat Recovery in Data Center

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Journal of Thermal Science 2025年第1期34卷 188-205页

作者： LI Peng XU Jiaqi WANG Binbin LIU Jianyang zhao Wensheng HAN Zhonghe School of Energy Power and Mechanical Engineering North China Electric Power University Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology North China Electric Power University

During data center operation,it generates a significant volume of low-grade waste *** recover waste heat,a coupled system including solar collector,double effect absorption refrigeration and organic Rankine cycle is *** system performance is analyzed in *** the organic Rankine cycle,five organic working fluids(R245fa,R245ca,R123,R11,and R113) are selected.R245fa,R113 and R245ca obtain the maximum net power output,thermal efficiency and exergy efficiency,*** the double effect absorption refrigeration system,the evaporation temperature,condensation temperature,and generation pressure affect the COP and exergy *** the generator pressure is unchanged,the COP increases with increasing evaporation temperature and decreasing condensation *** the COP reaches 1.3,the COP slightly decreases as the evaporation temperature or condensation temperature ***,the exergy efficiency of refrigeration systems exhibits the same trend as the COP,and the exergy efficiency maximum value appears at approximately 0.32.A new performance indicator,rPUE,was defined to evaluate the data center power utilization *** flow distribution ratio and heat source temperature were optimized with multi-objective *** the mass flow distribution rate is 0.6 and the heat source temperature is 441.5 K,rPUE and the total unit production costs of the system obtain the optimal solution.

关键词： Exergy

Wave effect of gravitational waves intersected with a microlens field Ⅱ:An adaptive hierarchical tree algorithm and population study

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 241-254页

作者： Xikai Shan Guoliang Li Xuechun Chen Wen zhao Bin Hu Shude Mao Department of Astronomy Tsinghua University Purple Mountain Observatory Chinese Academy of Sciences Institute for Frontier in Astronomy and Astrophysics Beijing Normal University School of Physics and Astronomy Beijing Normal University School of Astronomy and Space Science University of Science and Technology of China CAS Key Laboratory for Researches in Galaxies and Cosmology Department of Astronomy University of Science and Technology of ChinaChinese Academy of Sciences

The gravitational lensing wave effect generated by a microlensing field embedded in a lens galaxy is an inevitable phenomenon in strong lensed gravitational waves （SLGWs）.This effect presents both challenges and opportunities for the detection and application of ***,investigating this wave effect requires computing a complete diffraction integral over each microlens in the *** is extremely time-consuming due to the large number of microlenses （10～3-10～6）.Therefore,simply adding all the microlenses is ***,the complexity of the time delay surface makes the lens plane resolution a crucial factor in controlling numerical *** this paper,we propose a trapezoid approximation-based adaptive hierarchical tree algorithm to meet the challenges of calculation speed and *** find that this algorithm accelerates the calculation by four orders of magnitude compared to the simple adding method and is one order of magnitude faster than the fixed hierarchical tree algorithm proposed for electromagnetic *** importantly,our algorithm ensures controllable numerical errors,increasing confidence in the *** with our previous work （***.66,239511,2023）,this paper addresses all numerical issues,including integral convergence,precision,and computational time1).Finally,we conducted a population study on the microlensing wave effect of SLGWs using this algorithm and found that the microlensing wave effect cannot be ignored,especially for Type II SLGWs （from saddle position of the time delay surface） due to their intrinsic geometric structures and their typical intersection with a denser microlensing ***,more than 33%（11%） of SLGWs have a mismatch larger than 1%（3%） compared to the unlensed ***,we found that the mismatch between signal pairs in a doubly imaged GW is generally larger than 10-3,and 61%（25%） of signal pairs have a mismatch larger than 1%（3%）.Therefo

关键词： gravitational lensing diffractional integral algorithm gravitational wave

Experimental study of dual nano-network, high-temperature resistant aerogel material as an integration of thermal management functions

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Journal of Energy Chemistry 2025年第1期100卷 157-170页

作者： Yueyue Xiao Tianke Mao Zun zhao Yuelei Pan Heping Zhang Xudong Cheng State Key Laboratory of Fire Science University of Science and Technology of China

Thermal management system is highly desirable to guarantee the performance and thermal safety of lithium-ion batteries,but it reduces the energy density of battery modules and even is unable to provide highly effective ***,a thermal management function integrated material is presented based on high-temperature resistant aerogel and phase change material and is applied at both charge–discharge process and thermal runaway *** this sandwich structure Paraffin@SiC nanowire/Aerogel sheet （denoted as PA@SAS） system,SiC nanowires endow the middle aerogel sheet （SAS） a dual nano-network *** enhanced mechanical properties of SAS were studied by compressive tests and dynamic mechanical ***,the thermal conductivity of SAS at 600°C is only 0.042 W/（m K）.The surface phase change material layers facilitate temperature uniformity of batteries （surface temperature difference less than 1.82°C） through latent ***,a large-format battery module with four 58 Ah LiNi0.5Co0.2Mn0.3O2LIBs was ***@SAS successfully prevents thermal runaway propagation,yielding a temperature gap of 602°C through the 2 mm-thick cross ***@SAS also exhibits excellent performance in other safety issues such as temperature rise rate,flame heat flux,*** lightweight property and effective insulation performance achieves significant safety enhancement with mass and volume energy density reduction of only 0.79%and 5.4%,*** originality of the present research stems from the micro and macro structure design of the proposed thermal management material and the combination of intrinsic advantages of every *** work provides a reliable design of achieving the integration of thermal management functions into an aerogel composite and improves the thermal safety of lithium-ion batteries.

关键词： Thermal insulation

Channel pruning on frequency response

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Science China(Information Sciences) 2025年第1期68卷 159-170页

作者： Hang LIN Yifan PENG Lin BIE Chenggang YAN Xibin zhao Yue GAO School of Software Tsinghua University School of Automation Hangzhou Dianzi University

Network pruning has a significant role in reducing network parameters and accelerating the inference time of the network. Some existing methods prune the network based on the frequency of the data, and finally obtain a sub-network with high accuracy. However, according to our experimental analysis, different frequencies of information in the data contribute differently to the accuracy of the model, and using this information directly for pruning without making a selection will lead to incorrect results. We believe that pruning should retain the convolutional kernels in the network that process important information, while those kernels that process unimportant information should be removed. In this paper, we first investigate the meaning of each frequency band information in the spectrum and their contribution to the prediction accuracy of the network,and according to these results, we propose a new pruning method based on frequency response(PFR). Our PFR finds and removes the convolutional kernels in the network that specialize in processing unimportant information, resulting in a compact neural network model. PFR obtains significant experimental results on different datasets, for example, a 56.0% raduction of float points operations(FLOPs) on Res Net-50 and only 0.37% of Top-1 accuracy degradation on the Image Net dataset.

关键词： deep learning model compression filter pruning channel pruning frequency response

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Engineering nanoparticle structure at synergistic Ru-Na interface for integrated CO2 capture and hydrogenation

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Journal of Energy Chemistry 2025年第1期100卷 779-791页

作者： Hanzi Liu Ling Cen Xinlin Xie Lei Liu zhao Sun Zhiqiang Sun Hunan Engineering Research Center of Clean and Low-Carbon Energy Technology School of Energy Science and Engineering Central South University

The development of dual functional material for cyclic CO2capture and hydrogenation is of great significance for converting diluted CO2into valuable fuels,but suffers from kinetic limitation and deactivation of adsorbent and ***,we engineered a series of RuNa/γ-Al2O3materials,varying the size of ruthenium from single atoms to clusters/*** coordination environment and structure sensitivity of ruthenium were quantitatively investigated at atomic *** findings reveal that the reduced Ru nanoparticles,approximately 7.1 nm in diameter with a Ru-Ru coordination number of 5.9,exhibit high methane formation activity and selectivity at 340°*** Ru-Na interfacial sites facilitate CO2migration through a deoxygenation pathway,involving carbonate dissociation,carbonyl formation,and ***-situ experiments and theoretical calculations show that stable carbonyl intermediates on metallic Ru nanoparticles facilitate heterolytic C–O scission and C–H bonding,significantly lowering the energy barrier for activating stored CO2.

关键词： Carbon capture and utilization

国土空间规划背景下黄河流域水生态空间格局演变特征及其影响因素

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水土保持研究 2025年第2期32卷 178-190页

作者：薄立明赵浪尹力张翔魏伟武汉大学中国发展战略与规划研究院武汉430072 武汉大学城市设计学院武汉430072 中国地质大学(武汉)国家地理信息系统工程技术研究中心武汉430078 湖北省人居环境工程技术研究中心武汉430072

[目的]科学认知黄河流域上、中、下游水生态空间格局演化特征及影响因素,促进水资源用途管制客体向国土空间规划体系治理系统的融入,推动黄河流域生态保护和高质量发展。[方法]采用空间转移矩阵、最优地理探测器等量化模型分析黄河流域... 详细信息

[目的]科学认知黄河流域上、中、下游水生态空间格局演化特征及影响因素,促进水资源用途管制客体向国土空间规划体系治理系统的融入,推动黄河流域生态保护和高质量发展。[方法]采用空间转移矩阵、最优地理探测器等量化模型分析黄河流域上、中、下游水生态空间格局演变的区域差异,剖析了水生态空间格局演变路径并揭示其内在影响因素。[结果](1)黄河流域水生态空间规模为2.76万km^(2),仅占流域国土总面积的2.28%,上、中、下游水生态空间规模占比为22∶2∶3,研究期内规模性扩张了4 989.90 km^(2),上游地区增长规模最大,下游地区增长幅度最剧烈。(2)上游地区水生态空间主要与其他生态空间发生交叉转换,引起水生态空间大规模扩张,其次是与农业空间交互转换造成水生态空间小规模流失;中游地区水生态空间主要与农业空间发生交叉转换,其次是其他生态空间,引起水生态空间小规模扩张;下游地区农业空间向水生态空间的转换引起水生态空间大规模扩张的同时水生态空间也规模性转换为城镇空间。(3)上游地区水生态空间规模性扩张核心影响因素是水资源“液态化”的水文循环过程,流失则是主要由第一、三产业发展诉求驱动;中游地区水生态空间格局演变整体表现为政府财政所主导的适配地区自然地理条件、社会经济发展的水资源调配过程;下游地区则是水生态空间伴随城镇化进程在农业地区和城镇地区的转移。[结论]黄河流域上、中、下游水生态空间格局演变特征、路径和影响因素差异显著,需要根据各区域水资源保护利用的发展定位,建立起共同治理、协同发展的流域协作体系。

关键词：水生态空间国土空间规划用途管制时空格局黄河流域

Rise of β-furanosyl ribonucleosides as the extant RNA component facilitated by simple divalent transition-metal minerals

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Science China Chemistry 2025年

作者： Qianqian Chen Haoxing Xu Bingyue zhao Yeersen Patehebieke Zerun zhao Xiao Wang School of Chemistry and Chemical Engineering Nanjing University Frontiers Science Center for Critical Earth Material Cycling Nanjing University

The selective nucleoside synthesis through direct condensation between nucleobase and unactivated sugar in aqueous media has long been a formidable obstacle for the early chemical transformations hypothesized to construct the RNAWorld, due to product complexity and the low selectivity of the desired isomer. The preference of β-furanoside, the extant RNA component, has never been documented. Here we report an aqueous ribosylation mediated by divalent transition-metal ions, which unprecedentedly enhances the selectivity of furanosyl ribonucleosides as opposed to the traditionally predominating pyranosyl ones, with the furanoside/pyranoside ratio reaching up to 9/1. Furthermore, β-furanoside stands out for the first time as the most prevalent isomer in the presence of zinc and ammonium salts. The mechanism of this selectivity is elucidated with density functional theory calculations. The selectivity for β-furanoside can be further elevated via the adsorption on a zinc mineral. These findings exhibit as the first example that the selection of nucleosides with the desired, canonical configuration might be completed in the early stage of the RNA-forming process as opposed to later evolution, promoted by simple and widespread transition-metal minerals. The study may also find its value in synthetic chemistry as a guideline for developing a sustainable and selective glycosylation process.

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Transition metal clusters with precise numbers of atoms anchored on graphdiyne as multifunctional electrocatalysts for OER/ORR/HER:a computational study

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Rare Metals 2024年第7期43卷 3107-3117页

作者： Xin-Yang Liu jing-wei Liu Gang Li jing-Xiang zhao College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin 150025China

Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and *** this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 *** addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,***,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.

关键词： Density functional theory Graphdiyne Single-cluster catalysts Multifunctional electrocatalysts Overpotential

基于热辨识技术的硅基防热材料高温热导率测量

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工业加热 2017年第3期46卷 12-15页

作者：杨驰刘娜张利嵩应伟景昭北京航天长征飞行器研究所高超声速飞行器防隔热与热控技术中心北京100076

硅基防热材料是高超声速飞行器防热系统用重要材料之一,但由于硅基防热材料在高温条件下存在着复杂的物理化学变化,使得高温热导率的获取变得困难,这已成为飞行器防热系统精细化设计的主要制约瓶颈。基于热导率辨识方法,设计了一种能够... 详细信息

硅基防热材料是高超声速飞行器防热系统用重要材料之一,但由于硅基防热材料在高温条件下存在着复杂的物理化学变化,使得高温热导率的获取变得困难,这已成为飞行器防热系统精细化设计的主要制约瓶颈。基于热导率辨识方法,设计了一种能够实现硅基防热材料高温热导率测量的试验测量装置,对硅基防热材料在常温~800℃热导率进行了测量,并将测得的热导率外推应用到其他试验状态。结果表明,测得的硅基防热材料高温热导率合理可靠,具有很高的工程精度。该试验测量装置可实现不同温度下热导率的同步测量,测量成本低,效率高,这对其他防热材料的高温热导率测量具有重要的参考价值。

关键词：硅基防热材料测量装置高温热导率