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Modeling of Rectangular Microchannel Heat Sink with Non-Uniform Channels and Multi-Objective Optimization

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Journal of Thermal Science 2024年第5期33卷 1701-1711页

作者： SHANG Xueshuo wang Yixin LI Qingwen wang Rui CUI zheng SHAO Wei Institute of Advanced Technology Shandong UniversityJi'nan 250014China Institute of Thermal Science and Technology Shandong UniversityJi'nan 250014China Shandong Institute of Advanced Technology Ji'nan 250100China

Rectangular microchannel heat sinks(MCHS)are widely used to cool high-heat-flux electronic ***,previous studies focused mainly on MCHS with uniform channels(UCs).This study considers a microchannel heat sink with non-uniform channels(NUCs).A mathematical model is developed based on energy equations and the Darcy flow *** expressions for total thermal resistance and coolant pressure drop are derived using the thermoelectric *** and numerical simulations are performed to verify the mathematical *** non-uniformity increases,total coolant pressure drop decreases but at the cost of higher thermal *** overall performance of NUCs is better than that of UCs because of their lower ratio of pumping power to cooling *** transfer performance of NUCs changes little for more than 120 channels and depends mainly on channel arrangement.A multi-objective optimization is conducted to minimize the thermal resistance and pumping power of an *** optimal NUC saves 64%pumping power compared with a conventional UC for the total thermal resistance of 0.1℃/W,indicating that the use of non-uniform channels could be very helpful to reduce the flow resistance of MCHS.

关键词： microchannel heat sink non-uniform channel mathematical model multi-objective optimization

Steady-state Voltage Security-constrained Optimal Frequency Control for Weak HVDC Sending-end AC Power Systems

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 658-669页

作者： Qiangqiang wang Liangzhong Yao Jian Xu Yuping zheng Wei Li Wei wang School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network(Wuhan University) Wuhan 430072China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation(State Grid Electric Power Research Institute)Nanjing 211106China

Due to the fact that a high share of renewable energy sources(RESs)are connected to high-voltage direct current(HVDC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVDC sending-end AC power systems have *** has resulted in potential system operating problems such as overvoltage and overfrequency,which occur simultaneously when block faults exist in the HVDC *** this study,a steady-state voltage security-constrained optimal frequency control method for weak HVDC sending-end AC power systems is *** integrated virtual inertia control of RESs is employed for system frequency *** dynamic reactive power compensation devices are utilized to control the voltage of all nodes meet voltage security ***,an optimization model that simultaneously considers the frequency and steady-state voltage security constraints for weak HVDC sending-end AC power systems is *** optimal control scheme with the minimum total cost of generation tripping and additional dynamic reactive power compensation required is obtained through the optimization *** are conducted on a modified IEEE 9-bus test system and practical Qing-Yu line commutated converter based HVDC(LCC-HVDC)sending-end AC power system to verify the effectiveness of the proposed method.

关键词： Renewable energy source(RES) high-voltage direct current(HVDC) AC power system optimal frequency control steady-state voltage security dynamic reactive power compensation

Precision tuning of highly efficient Pt-based ternary alloys on nitrogen-doped multi-wall carbon nanotubes for methanol oxidation reaction

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Journal of Energy Chemistry 2024年第1期88卷 242-251,I0006页

作者： Xingqun zheng zhengcheng wang Qian Zhou Qingmei wang Wei He Shun Lu College of Safety Engineering Chongqing University of Science&TechnologyChongqing 401331China College of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China School of Chemistry and Chemical Engineering Guizhou UniversityGuizhou 550025GuiyangChina Department of Chemistry University of Rhode IslandKingston 02881Rhode IslandUnited States Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China

The electrochemical methanol oxidation is a crucial reaction in the conversion of renewable *** enable the widespread adoption of direct methanol fuel cells(DMFCs),it is essential to create and engineer catalysts that are both highly effective and robust for conducting the methanol oxidation reaction(MOR).In this work,trimetallic PtCoRu electrocatalysts on nitrogen-doped carbon and multi-wall carbon nanotubes(PtCoRu@NC/MWCNTs)were prepared through a two-pot synthetic *** acceleration of CO oxidation to CO_(2) and the blocking of CO reduction on adjacent Pt active sites were attributed to the crucial role played by cobalt atoms in the as-prepared *** precise control of Co atoms loading was achieved through precursor *** physicochemical techniques were employed to analyze the morphology,element composition,and electronic state of the *** investigations and theoretical calculations confirmed that the Pt_(1)Co_(3)Ru_(1)@NC/MWCNTs exhibit excellent electrocatalytic performance and durability for the process of *** enhanced MOR activity can be attributed to the synergistic effect between the multiple elements resulting from precisely controlled Co loading content on surface of the electrocatalyst,which facilitates efficient charge *** interaction between the multiple components also modifies the electronic structures of active sites,thereby promoting the conversion of intermediates and accelerating the MOR ***,achieving precise control over Co loading in PtCoRu@NC/MWCNTs would enable the development of high-performance catalysts for DMFCs.

关键词： Ternary alloys Electrocatalysts Methanol oxidation reaction Electron transfer Theoretical calculations

Intensifying electrified flow-through water treatment technologies via local environment modification

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 17-25页

作者： zheng-Yang Huo Xiaoxiong wang Xia Huang Menachem Elimelech School of Environment and Natural Resources Institute of Ecological CivilizationRenmin University of ChinaBeijing 100872China Institute for Ocean Engineering Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Center of Double Helix Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Department of Chemical and Environmental Engineering Yale UniversityNew HavenCT 06520-8286USA

Removing high-risk and persistent contaminants from water is challenging,because they typically exist at low concentrations in complex water *** flow-through technologies are viable to overcome the limitations induced by mass transport for efficient contaminant *** the local environment of the flow-through electrodes offers opportunities to further improve the reaction kinetics and selectivity for achieving near-complete removal of these contaminants from ***,we present state-of-the-art local environment modification approaches that can be incorporated into electrified flow-through technologies to intensify water *** first show methods of nanospace incorporation,local geometry adjustment,and microporous structure optimization that can induce spatial confinement,enhanced local electric field,and microperiodic vortex,respectively,for local environment *** then discuss why local environment modification can complement the flow-through electrodes for improving the reaction rate and ***,we outline appropriate scenarios of intensifying electrified flow-through technologies through local environment modification for fit-for-purpose water treatment applications.

关键词： Point-of-use water treatment Electrified membrane Advection-enhanced mass transport Water decontamination and disinfection Emerging contaminants

Preparation and Swelling Kinetic Analysis of Poly (HPMC-co-AA-co-AM) Super Absorbent Resin

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 790-799页

作者：马砺 wang Xin LIU Xixi WEI Gaoming GUO ying School of Safety Science and Engineering Xi’an University of Science and TechnologyXi'an 710054China Key Laboratory of Coal Fire Disaster Prevention Xi’an University of Science and TechnologyXi'an 710054China School of Energy Engineering Xi’an Uni-versity of Science and TechnologyXi'an 710054China Yanzhou Coal Mining Co. Ltd.Zoucheng 237500China

Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking ***,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction *** optimized conditions are obtained by the experiment repeating for several *** water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,***,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are *** is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.

关键词： super absorbent resin swelling kinetics water absorption graft copolymerization hydroxypropyl methyl cellulose

The Squeeze & Excitation Normalization Based nnU-Net for Segmenting Head & Neck Tumors

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Chinese Journal of Electronics 2024年第3期33卷 766-775页

作者： Juanying XIE ying PENG Mingzhao wang School of Computer Science Shaanxi Normal University

Head and neck cancer is one of the most common malignancies in the *** propose SE-nnU-Net by adapting SE(squeeze and excitation) normalization into nnU-Net,so as to segment head and neck tumors in PET/CT images by combining advantages of SE capturing features of interest regions and nnU-Net configuring itself for a specific *** basic module referred to convolution-ReLU-SE is designed for *** the encoder it is combined with residual structure while in the decoder without residual *** loss function combines Dice loss and Focal *** specific data preprocessing and augmentation techniques are developed,and specific network architecture is ***,the deep supervised mechanism is introduced to calculate the loss function using the last four layers of the decoder of *** SE-nnU-net is applied to HECKTOR 2020 and HECKTOR 2021 challenges,respectively,using different experimental *** experimental results show that SE-nnU-Net for HECKTOR 2020 obtained 0.745,0.821,and 0.725 in terms of Dice,Precision,and Recall,respectively,while the SE-nnU-Net for HECKTOR 2021 obtains 0.778 and 3.088 in terms of Dice and median HD95,*** SE-nnU-Net for segmenting head and neck tumors can provide auxiliary opinions for doctors diagnoses.

关键词： Image segmentation Head Data preprocessing Artificial neural networks Network architecture Data models Neck

Shifts in chemical and microbiological properties belowground of invader Ageratina adenophora along an altitudinal gradient

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Journal of Plant Ecology 2022年第3期15卷 561-570页

作者： Wei-Tao Li Yu-Long zheng Rui-Fang wang zheng-ying wang Yan-Mei Liu Xiong Shi Zhi-Yong Liao Yang-Ping Li Yu-Long Feng CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303China Center of Conservation Biology Core Botanical GardensChinese Academy of SciencesMengla 666303China College of Life Sciences University of Chinese Academy of SciencesBeijing 100049China College of Agriculture and Forestry Puer UniversityPuer 665000China College of Bioscience and Biotechnology Liaoning Key Laboratory for Biological Invasions and Global ChangesShenyang Agricultural UniversityShenyang 110866China

Tropical mountain ecosystems are usually colonized by numerous invasive plant species and represent an ideal‘natural laboratory’to study the effects of altitude on plant *** aim of this study was to investigate the soil chemical and microbiological properties along an altitudinal gradient on a mountain colonized by the invader Ageratina *** soil of *** was collected over an altitudinal gradient(1400–2400 m)in Ailao Shan,*** determined soil organic carbon(C),nutrient contents,enzyme activities,bacterial community composition as well as C and nitrogen(N)contents of the plant *** stoichiometric indices were calculated to estimate the relative C,N or P limitations of the microbial *** was a significant effect of altitude on soil organic C in the rhizosphere,and a turning point in these measured variables was detected at an altitude of 2000 *** low elevations,the rapid growth of invasive plants depleted the deficient phosphorus(P)in tropical soils,leading to microbial P limitation;at high elevations,microbes invested more energy to obtain C from resistant litter,leading to microbial C *** beta diversity and soil pH contributed most to the altitudinal differences in ecoenzymatic stoichiometry,and Proteobacteria and Acidobacteria were the dominant bacterial phyla that determined the nutrient uptake status of *** results demonstrate how microbial nutrient acquisition belowground of *** along an altitudinal gradient,which could contribute to further knowledge about the effects of altitude on biological invasion.

关键词： Ageratina adenophora nutrients ecoenzymatic stoichiometry microbial metabolic limitation bacterial community

KeyEE:Enhancing Low-Resource Generative Event Extraction with Auxiliary Keyword Sub-Prompt

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Big Data Mining and Analytics 2024年第2期7卷 547-560页

作者： Junwen Duan Xincheng Liao ying An Jianxin wang Hunan Key Laboratory of Bioinformatics School of Computer Science and EngineeringCentral South UniversityChangsha 410083China Big Data Institute Central South UniversityChangsha 410083China

Event Extraction(EE)is a key task in information extraction,which requires high-quality annotated data that are often costly to *** classification-based methods suffer from low-resource scenarios due to the lack of label semantics and fine-grained *** recent approaches have endeavored to address EE through a more data-efficient generative process,they often overlook event keywords,which are vital for *** tackle these challenges,we introduce KeyEE,a multi-prompt learning strategy that improves low-resource event extraction by Event Keywords Extraction(EKE).We suggest employing an auxiliary EKE sub-prompt and concurrently training both EE and EKE with a shared pre-trained language *** the auxiliary sub-prompt,KeyEE learns event keywords knowledge implicitly,thereby reducing the dependence on annotated ***,we investigate and analyze various EKE sub-prompt strategies to encourage further research in this *** experiments on benchmark datasets ACE2005 and ERE show that KeyEE achieves significant improvement in low-resource settings and sets new state-of-the-art results.

关键词： natural language processing Event Extraction(EE) Multi-Prompt Learning(MPL) low-resource

Behaviors analysis of on-coming cluster based on knowledge under cluster security requirements

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 448-462页

作者： Zhang, Huixia Liang, Yan Shi, ying wang, Yuedong Ma, Chaoxiong wang, Ran Northwestern Polytech Univ Sch Automat Xian 710129 Peoples R China Minist Educ Key Lab Informat Fus Technol Xian 710129 Peoples R China

Analysis of cluster behaviors of the on-coming cluster is an essential measure for high value locations on the battlefield. Unlike target tracking and clustering analysis, cluster behaviors analysis under cluster security requirements remains an open issue, which is a joint analysis of clustering, intent reasoning and activity regions. To address this issue, a framework for cluster behaviors analysis is proposed by incorporating expert knowledge and domain knowledge, and a knowledge-assisted score function with is designed to improve the accuracy of intent reasoning network, overcoming the effects of possible knowledge errors. The framework consists of three modules for cluster analysis, intent reasoning and activity region analysis for typical tasks, in which an intent reasoning network is constructed to obtain cluster intents by using a hybrid knowledge and data driven approach. Furthermore, considering the complexity of the battlefield environment, different tasks and corresponding activity region optimization functions are designed for cluster activity region analysis, which are vital elements of cluster behaviors analysis. Simulations demonstrate the effectiveness of the proposed cluster behaviors analysis framework. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Cluster analysis Intent reasoning Activity region analysis Cluster behavior Battlefield environment SYSTEMS