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A global model for evaluating discharge characteristics and performance of hollow cathodes

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 72-84页

作者： Tian, Feng Miao, long Xia, Qimeng wu, Zhiwen Wang, Ningfei Hou, Xiao Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China Beijing Inst Technol Chongqing Innovat Ctr Chongqing 404100 Peoples R China

Hollow cathode, with the highest plasma density, current density, and temperature, becomes one of the most important components in the electro-thruster system. As the electric-propulsion thruster performance is directly related to the ionization rate, reliability, and lifetime of the hollow cathode, this paper develops a global model to study the effects of discharge current, gas flow rate, and gas species on the discharge characteristics in the insert and orifice regions of the hollow cathode. The emitter wall temperatures of hollow cathodes predicted by the global model are compared with experimental results from NSTAR thruster neutralization cathodes, confirming the model's validity. The influence of hollow cathode emitter material and structure sizes on the plasma parameters in the internal regions was also evaluated. The simulation results show that there is an optimal matching relationship between the discharge current and gas flow rate to guarantee the maximum ionization rate. The optimal working region for the hollow cathode has been determined under different energetic, regime and structural parameters. The global model established in this paper can quickly determine the key structure and operating parameters of hollow cathode at the design stage, and provide the theoretical basis for hollow cathode design and development. (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： Hollow cathode Global model Electric propulsion Discharge characteristics Optimal matching relationship ION PROPULSION SIMULATION

Enhanced energy density and fast-charging ability via directional particle configuration

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Journal of Energy Chemistry 2024年第3期90卷 152-164,I0005页

作者： Xiongwei wu Shanguang lv Jiabao Li Xingrong yin Xuewen wu Jun Liu Jie Zhang Yuhan Yu Bei long Hunan yinfeng New Energy Co.Ltd. Changsha 410019HunanChina

The limited energy density of lithium-ion capacitors poses a significant obstacle to their widespread application,primarily stemming from the inability of the electrodes to simultaneously fulfill both high energy density and rapid charging *** data demonstrate that a directional particle configuration can enhance charging speed while maintaining high-capacity density,but it is rarely ***,we have developed a particle-level electrochemical model capable of reconstructing an electrode with a directional particle *** employing this method,an investigation was conducted to explore how the spatial morphology characteristics of particle configuration impact the energy storage characteristics of *** demonstrate that rational particle configuration can effectively enhance the transport of lithium ions and create additional space for lithium-ion *** the same particle size distribution,the best electrode can increase the discharge capacity by up to132.4% and increase the charging SOC by 11.3% compared to the ordinary electrode under the condition of 6 *** findings provide a further understanding of the energy storage mechanism inside the anisotropic particle distribution electrode,which is important for developing high-performance lithium-ion capacitors.

关键词： Supercapacitor Gradient design strategies Energy storage Charge transport

Less pressure contributes to gravity-driven membrane ultrafiltration with greater performance:Enhanced driving efficiency and reduced disinfection by-products formation potential

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Journal of Environmental Sciences 2024年第3期137卷 407-419页

作者： Xiaoting wu Yufei Li Zhaoyang Su long Tian Muhammad Saboor Siddique Wenzheng Yu Colleges of Forestry Northeast Forestry UniversityHarbin 150040China State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

Gravity-driven membrane(GDM)systems have been well developed previously;however,impacts of driving(i.e.,transmembrane)pressure on their performance received little attention,which may infuence GDM *** this study,we evaluated 4 GDM systems via altering the transmembrane pressure from 50 mbar to 150 mbar with 2 groups,treating surface water in Beijing,*** showed that less driving pressure was more ***,compared to groups(150 mbar),groups under a pressure of 50 mbar were found to have greater normalized permeability and lower total *** the whole operation period,the quality of effuents was gradually *** example,the removal efficiency of UV254was significantly improved;particularly,under low driving pressure,the removal efficiency of UV254in PES GDM system increased by 11.91%,as compared to the corresponding system under high driving *** observation was consistent with the reduction on disinfection by-products(DBPs)formation potential;groups under 50 mbar achieved better DBPs potential control,indicating the advantages of lower driving *** were analyzed and responsible for these differences,and distinct distributions of bacteria communities of two GDM systems under 50 and 150 mbar may be responsible for various humic-like substances removal ***,GDM systems under less pressure should be considered and expected to provide suggestions on the design of GDM systems in real applications.

关键词： Ultrafiltration Gravity driven operation Membrane fouling Biofilms Disinfection by-products

Representation learning: serial-autoencoder for personalized recommendation

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Frontiers of Computer Science 2024年第4期18卷 61-72页

作者： yi ZHU yishuai GENG Yun LI Jipeng QIANG Xindong wu School of Information Engineering Yangzhou UniversityYangzhou 225127China Key Laboratory of Knowledge Engineering with Big Data(Ministry of Education of the People’s Republic of China) Hefei University of TechnologyHefei 230009China School of Computer Science and Information Engineering Hefei University of TechnologyHefei 230009China

Nowadays,the personalized recommendation has become a research hotspot for addressing information *** this,generating effective recommendations from sparse data remains a ***,auxiliary information has been widely used to address data sparsity,but most models using auxiliary information are linear and have limited *** to the advantages of feature extraction and no-label requirements,autoencoder-based methods have become quite ***,most existing autoencoder-based methods discard the reconstruction of auxiliary information,which poses huge challenges for better representation learning and model *** address these problems,we propose Serial-Autoencoder for Personalized Recommendation(SAPR),which aims to reduce the loss of critical information and enhance the learning of feature ***,we first combine the original rating matrix and item attribute features and feed them into the first autoencoder for generating a higher-level representation of the ***,we use a second autoencoder to enhance the reconstruction of the data representation of the prediciton rating *** output rating information is used for recommendation *** experiments on the MovieTweetings and MovieLens datasets have verified the effectiveness of SAPR compared to state-of-the-art models.

关键词： personalized recommendation autoencoder representation learning collaborative filtering

Parallel Computing Based Solution for Reliability-constrained Distribution Network Planning

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1147-1158页

作者： Yaqi Sun Wenchuan wu yi Lin Hai Huang Hao Chen State Key Laboratory of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Sichuan Energy Internet Research Institute Tsinghua UniversityChengduChina State Grid Fujian Electric Power Co.Ltd. FuzhouChina

The main goal of distribution network(DN)expan-sion planning is essentially to achieve minimal investment con-strained by specified reliability *** reliability-constrained distribution network planning(RcDNP)problem can be cast as an instance of mixed-integer linear programming(MILP)which involves ultra-heavy computation burden espe-cially for large-scale *** this paper,we propose a parallel computing based solution method for the RcDNP *** RcDNP is decomposed into a backbone grid and several lateral grid problems with ***,a parallelizable aug-mented Lagrangian algorithm with acceleration method is devel-oped to solve the coordination planning *** lateral grid problems are solved in parallel through coordinating with the backbone grid planning ***-Seidel iteration is adopted on the subset of the convex hull of the feasible region constructed by *** mild conditions,the opti-mality and convergence of the proposed method are *** tests show that the proposed method can significant-ly reduce the solution time and make the RcDNP applicable for real-worldproblems.

关键词： Distribution network expansion planning reliability parallel computing

Global-local combined features to detect pain intensity from facial expression images with attention mechanism

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Journal of Electronic Science and Technology 2024年第3期22卷 80-93页

作者： Jiang wu yi Shi Shun Yan Hong-Mei Yan Yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou313001China MOE Key Laboratory for Neuroinformation School of Life Science and TechnologyUniversity of Electronic Science and Technology of ChinaChengdu611731China College of Engineering University of California at Santa BarbaraSanta Barbara93106USA

The estimation of pain intensity is critical for medical diagnosis and treatment of *** the development of image monitoring technology and artificial intelligence,automatic pain assessment based on facial expression and behavioral analysis shows a potential value in clinical *** paper reports a framework of convolutional neural network with global and local attention mechanism(GLA-CNN)for the effective detection of pain intensity at four-level thresholds using facial expression ***-CNN includes two modules,namely global attention network(GANet)and local attention network(LANet).LANet is responsible for extracting representative local patch features of faces,while GANet extracts whole facial features to compensate for the ignored correlative features between *** the end,the global correlational and local subtle features are fused for the final estimation of pain *** under the UNBC-McMaster Shoulder Pain database demonstrate that GLA-CNN outperforms other state-of-the-art ***,a visualization analysis is conducted to present the feature map of GLA-CNN,intuitively showing that it can extract not only local pain features but also global correlative facial *** study demonstrates that pain assessment based on facial expression is a non-invasive and feasible method,and can be employed as an auxiliary pain assessment tool in clinical practice.

关键词： Attention Convolutional neural network Facial expression Pain intensity

New food sources and production systems:a comparison of international regulations and China’s advancements in novel foods with synthetic biology

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Food Science and Human Wellness 2024年第5期13卷 2519-2542页

作者： Xin Liu Di wu yi Shao Yongning wu Key Laboratory for Deep Processing of Major Grain and Oil(The Chinese Ministry of Education) College of Food Science and EngineeringWuhan Polytechnic UniversityWuhan 430023China Institute for Global Food Security School of Biological SciencesBelfast B795DLUnited Kingdom NHC Key Laboratory of Food Safety Risk Assessment China National Center for Food Safety Risk AssessmentBeijing 100021China Department of Nutrition and Food Safety Peking Union Medical CollegeResearch Unit of Food SafetyChinese Academy of Medical SciencesBeijing 100021China

The global shift towards sustainable food systems has sparked innovations in food sources and production systems,including cell-based meat,plant-based food products,precision fermentation,and 3D food *** advancements pose regulatory challenges and opportunities,with China emerging as a critical player in adopting and regulating new food *** review explores the international landscape of new food sources and production systems(NFPS),focusing on China’s role and regulatory approaches compared to global *** this comparative analysis,we aim to contribute to the ongoing dialogue on food safety regulation,offering insights and recommendations for policymakers,industry stakeholders,and researchers engaged in the global food system’s *** comprehensive overview underscores the dynamic nature of regulatory frameworks governing NFPS,highlighting the international efforts to ensure food safety,consumer protection,and the sustainable evolution of the food industry.

关键词： New food sources Food production system Food safety International regulation Synthetic biology China

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Weighted Probability Density Estimator with Updated Bandwidths

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Journal of Systems Science & Complexity 2024年第2期37卷 886-906页

作者： wu yi YU Wei WANG Xuejun PRAKASA RAO B L S School of Big Data and Artificial Intelligence Chizhou UniversityChizhou 247000China School of Big Data and Statistics Anhui UniversityHefei 230601China CR Rao Advanced Institute of Mathematics Statistics and Computer ScienceHyderabad 500046India

In this paper,the authors study a class of weighted version of probability density *** is shown that the weighted estimator contains some existing estimators of probability density,no matter they are recursive or *** statistical results including weak consistency,strong consistency,rate of strong consistency,and asymptotic normality are established under some mild ***,the random weighted estimator is also *** numerical simulations and a real data analysis are presented to study the numerical performances of the estimators.

关键词： Asymptotic normality consistency numerical simulation probability density real data analysis updated bandwidths weighted estimator

Two-Dimensional Perovskite Single Crystals for High-Performance X-ray Imaging and Exploring MeV X-ray Detection

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Energy & Environmental Materials 2024年第1期7卷 139-146页

作者： Xieming Xu yiheng wu yi Zhang Xiaohui Li Fang Wang Xiaoming Jiang Shaofan wu Shuaihua Wang Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Division of Nuclear Technology and Applications Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

Scintillation semiconductors play increasingly important medical diagnosis and industrial inspection ***,two-dimensional(2D)perovskites have been shown to be promising materials for medical X-ray imaging,but they are mostly used in low-energy(≤130 keV)*** detection of MeV X-rays,which ensure thorough penetration of the thick shell walls of containers,trucks,and aircraft,is also highly desired in practical industrial ***,scintillation semiconductors for high-energy X-ray detection are currently ***,This paper reports a 2D(C_(4)H_(9)NH_(3))_(2)PbBr_(4)single crystal with outstanding sensitivity and stability toward X-ray radiation that provides an ultra-wide detectable X-ray range of between 8.20 nGy_(air)s^(-1)(50 keV)and 15.24 mGy_(air)s^(-1)(9 MeV).The(C_(4)H_(9)NH_(3))_(2)PbBr_(4)single-crystal detector with a vertical structure is used for high-performance X-ray imaging,delivering a good spatial resolution of 4.3 Ip mm^(-1)in a plane-scan imaging *** ionic migration in the 2D perovskite enables the vertical device to be operated with hundreds of keV to MeV X-ray radiation at high bias voltages,leading to a sensitivity of 46.90μC Gy_(air)-1 cm^(-2)(-1.16 Vμm^(-1))with 9 MeV X-ray radiation,demonstrating that 2D perovskites have enormous potential for high-energy industrial applications.

关键词： MeV X-ray detection single-crystal X-ray detectors two-dimensional perovskites X-ray imaging