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Rare Metals 2021年第5期40卷 1232-1238页

作者： tian-chi ji Min-Xiang Pan Hong-Liang Ge Qiong Wu Peng-Yue Zhang Magnetism Key Laboratory of Zhejiang Province China Jiliang UniversityHangzhou 310018China

In the present work,the magnetization reversal behavior for the melt spinning(Nd_(0.8)Ce_(0.2))_(2)Fe_(12)Co_(2-x)Zr_(x)B(x=0,0.5)permanent alloys with high coercivity was investigated by analyzing the hysteresis curves and the recoil *** to the Zr-free alloy,the Zr-doped sample obtains higher magnetic properties:coercivity of H_(cj)=650.5 kA·m^(-1),squareness of H_(k)/H_(cj)=0.76 and maximum energy product of(BH)_(max)=131.0 kJ·m^(-3).The first-order reversal curves(FORCs)analysis was taken to identify optimal conditions of exchange coupling for the Zr-free and Zr-doped *** coercivity mechanism of theα-Fe/Nd_(2)Fe_(14)B nanocomposite alloys was analyzed by the angular dependence of the coercive field as measured for the Zr-doped *** results show that the magnetic reverse process of the Zr-doped sample can be explained by the pinning model.

关键词： Magnetization reversal Coercivity mechanism First-order reversal curve(FORC) Nanocomposite

Forced boiling of nonazeotropic immiscible mixture in a supercapillary microchannel array for ultra-high heat flux removal with chip junction temperature below 85℃

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Science china(Technological Sciences) 2024年第5期67卷 1364-1380页

作者： SUN Bo BAO YuChen tian Tong LI ji School of Engineering Science University of Chinese Academy of SciencesBeijing100049China Laboratory of Advanced Thermal Management Technologies School of Engineering ScienceUniversity of Chinese Academy of SciencesBeijing100049China

In this study,a structure-optimized two-phase microchannel heat sink with sintered submicron nucleation sites was developed and *** copper-based microchannels had a rectangular cross-section with an equivalent hydraulic diameter of 222μ*** subcooled flow boiling characteristics were comprehensively compared between pure HFE-7100 and a non-azeotropic,immiscible binary mixture of HFE-7100 and water,considering heating areas of 1 and 5 cm^(2).The total heating power input to the test section were 100–1500 and 250–3000 W for a 1 and 5 cm^(2)heat source,respectively,with a flow rate ranging from 50 to150 L/*** to pure HFE-7100,the non-azeotropic immiscible binary mixture of HFE-7100/water in the sintered porous microchannels exhibited a much higher overall heat transfer coefficient and lower power *** maintain the junction temperature of a high power electronic chip below 85℃,the proposed supercapillary microchannel heat sink could effectively dissipate the heat flux of 1275 W/cm^(2)over 1 cm^(2)heat source and 500 W/cm^(2)over 5 cm^(2)heat *** addition,the volume ratio of the binary mixture strongly influence the two-phase flow heat transfer *** optimal volume ratio exist in terms of the thermal resistance–pumping power minimization(HFE-7100:water=2:8 is recommended in this study).The findings of this investigation on the flow boiling properties of non-azeotropic immiscible mixtures help fill a gap in the related field.

关键词： microchannel sintered powder coating submicron nucleation cavities nonazeotropic immiscible ultra-high heat flux

Performance evaluation for multi-target tracking with temporal dimension specifics

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chinese Journal of Aeronautics 2024年第2期37卷 446-458页

作者： Zhenzhen SU Hongbing ji Cong tian Yongquan ZHANG School of Computer Science and Technology Xidian UniversityXi’an 710071China School of Electronic Engineering Xidian UniversityXi’an 710071China

With the great development of Multi-Target Tracking(MTT)technologies,many MTT algorithms have been proposed with their own advantages and *** to the fact that requirements to MTT algorithms vary from the application scenarios,performance evaluation is significant to select an appropriate MTT algorithm for the specific application *** this paper,we propose a performance evaluation method on the sets of trajectories with temporal dimension specifics to compare the estimated trajectories with the true *** proposed method evaluates the estimate results of an MTT algorithm in terms of tracking accuracy,continuity and ***,its computation is based on a multi-dimensional assignment problem,which is formulated as a computable form using linear *** enhance the influence of recent estimated states of the trajectories in the evaluation,an attention function is used to reweight the trajectory errors at different time ***,simulation results show that the proposed performance evaluation method is able to evaluate many aspects of the MTT *** evaluations are worthy for selecting suitable MTT algorithms in different application scenarios.

关键词： Multi-target tracking Temporal dimension specifics Performance evaluation Random finite sets Linear programming

Anthracene-bridged“Texas-sized”box for the simultaneous detection and uptake of tryptophan

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chinese Chemical Letters 2024年第9期35卷 175-178页

作者： Dan Luo jinya tian jianqiao Zhou Xiaodong chi State Key Laboratory of Materials Processing and Die&Mold Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Shenzhen Huazhong University of Science and Technology Research Institute Shenzhen 518057China

Tryptophan(Trp)is an essential amino acid that plays a critical role in human *** increasing demand for Trp has created a highly promising market,underscoring the urgent necessity for the development of efficient strategies for the simultaneous detection and uptake of ***,we report an expanded“Texas-sized”molecular box(An-TxSB),which incorporates luminescent anthracene bridging subunits and molecular recognition *** luminescent molecular box demonstrates exceptional sensitivity to Trp in water,permitting its precise quantification with a notably low limit of detection(LOD)of 0.42μmol/***,An-TxSB facilitates the proficient uptake of Trp from simulated water samples,thereby revealing an impressive Trp adsorption capacity of up to 226.0μmol/g.

关键词： Macrocycles Host-guest chemistry Biomolecular sensors Molecular recognition Adsorption

Review of the Configuration and Transient Stability of Large-scale Renewable Energy Generation through Hybrid DC Transmission

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CES Transactions on Electrical Machines and Systems 2024年第2期8卷 115-126页

作者： Xinshou tian Yongning chi Longxue Li Hongzhi Liu Institute of Energy Power Innovation North China Electric Power UniversityBeijing 102206China china Electric Power Research Institute No.15Xiaoying East RoadQingheHaidian DistrictBeijing 100192China.

Based on the complementary advantages of Line Commutated Converter(LCC)and Modular Multilevel Converter(MMC)in power grid applications,there are two types of hybrid DC system topologies:one is the parallel connection of LCC converter stations and MMC converter stations,and the other is the series connection of LCC and MMC converter stations within a single *** hybrid DC transmission system faces broad application prospects and development potential in large-scale clean energy integration across regions and the construction of a new power system dominated by new energy sources in *** paper first analyzes the system forms and topological characteristics of hybrid DC transmission,introducing the forms and topological characteristics of converter-level hybrid DC transmission systems and system-level hybrid DC transmission ***,it analyzes the operating characteristics of LCC and MMC inverter-level hybrid DC transmission systems,provides insights into the transient stability of hybrid DC transmission systems,and typical fault ride-through control ***,it summarizes the networking characteristics of the LCC-MMC series within the converter station hybrid DC transmission system,studies the transient characteristics and fault ridethrough control strategies under different fault types for the LCC-MMC series in the receiving-end converter station,and investigates the transient characteristics and fault ride-through control strategies under different fault types for the LCC-MMC series in the sending-end converter station.

关键词： Hybrid DC transmission Transient stability Configuration Control system

Giant piezotronic effect in ferroelectric field effect transistor

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Nano Research 2024年第9期17卷 8465-8471页

作者： Haiming Zhang Mengshuang chi Shidai tian tian Liang jitao Liu Xiang Zhang Lingyu Wan Zhong Lin Wang Junyi Zhai Center on Nanoenergy Research School of Physical Science&TechnologyGuangxi UniversityNanning 530004China Beijing Key Laboratory of Micro-Nano Energy and Sensor Center for High-Entropy Energy and SystemsBeijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 101400China School of Nanoscience and Engineering University of Chinese Academy of ScienceBeijing 100049China School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 610054China Georgia Institute of Technology AtlantaGA 30332USA

The piezotronics effect utilizes a piezopotential to modulate and control current in *** materials,as a type of piezoelectric materials,possess piezoelectric coefficients that are significantly larger than those found in conventional piezoelectric ***,we propose a strain modulated ferroelectric field-effect transistor(St-FeFET)utilizing external strain instead of gate voltage to achieve ferroelectric modulation,which eliminates the need for gate *** applying a very small strain(0.01%),the St-FeFET can achieve a maximum on-off current ratio of 1250%and realizes a gauge factor(GF)of 1.19×10^(6),which is much higher than that of conventional strain *** work proposes a new method for realizing highly sensitive strain sensors and presents innovative approaches to the operation methods of ferroelectric field-effect transistors as well as potential applications for coupling of strain sensors and various devices across different fields.

关键词： ferroelectric field-effect transistors piezotronics [Pb(Mg_(1/3)Nb_(2/3))O_(3)]_((1-x)^(-))[PbTiO_(3)]_(x)(PMN-PT) strain sensors

Microseismic observations reveal that internal waves intensify seabed methane release

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Science china Earth Sciences 2024年第10期67卷 3186-3203页

作者： Zhaoyang tian Yonggang jiA Junjiang ZHU tian CHEN Hui WANG Chunsheng ji Chengyu LIU Longyu LU Manchao HE Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering Ocean University of ChinaQingdao 266100China Frontiers Science Center for Deep Ocean Multispheres and Earth System Key Lab of Submarine Geosciences and Prospecting TechniquesMOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China Guangzhou Marine Geological Survey China Geological SurveyGuangzhou 511458China Shandong Earthquake Agency Jinan 250014China State Key Laboratory for Tunnel Engineering China University of Mining and Technology(Beijing)Beijing 100083China

Internal waves transport material and energy from the upper water column to the deep ocean, disturbing seabed sediments and resulting in phenomena such as seabed erosion and changes in topography. On the northern slope of the South china Sea and in many coastal margins worldwide, the zones with internal wave action closely overlap with areas where natural gas hydrates are present. However, due to significant differences in the spatial and temporal scales, understanding the influence of internal waves on methane releases from deep seabeds is challenging. In this study, in situ observations of seabed microseismicity and internal waves are conducted at water depths of 655 meters and 1450 meters in the Pearl River Canyon of the South china Sea. The microseismicity caused by internal waves and seabed methane releases is identified, and a method to establish the correlation between internal waves and seabed methane releases through the use of microseismic recordings is proposed, aiming to obtain direct observational evidence of internal waves intensifying seabed methane releases. The results show that internal waves and seabed methane releases generate significant microseismic signals, indicating the continuous influence of internal waves on the deep seabed of the northern slope of the South china Sea and revealing active methane release phenomena on the seabed. At both long and short time scales, internal waves increase the frequency of seabed methane releases by 4.2 times and 2.4 times, respectively, while also enhancing the intensity of these releases. These changes are influenced by the alterations in seabed flow velocity, pressure, and temperature that are induced by internal wave activities. This study emphasizes that microseismic signals are effective carriers of information for multiscale geological processes on seabeds and suggests that internal waves exacerbate marine geological hazards and contribute to global climate change by intensifying seabed methane relea

关键词： Internal waves Seabed methane release Microseismic observation Ocean bottom seismometer Northern slope of the South china Sea

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Electrical discharge and arc milling with automatic tracking of optimal flushing direction:A novel high-efficiency compound machining method

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chinese Journal of Aeronautics 2024年第3期37卷 351-364页

作者： Xinlei WU Yonghong LIU Pengxin ZHANG Liang QI Dege LI chi MA Renjie ji College of Mechanical and Electronic Engineering China University of Petroleum(East China)Qingdao 266580China School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China

The arc milling method has the advantages of high machining efficiency and low cost and is independent of the strength and hardness of machined ***,frequent electrode back-offs and the risk of workpiece burning may occur if erosion products are not removed *** this study,it was found that the flushing method of the working medium had a significant impact on the machining performance of arc *** on this,a novel highefficiency compound machining method of electrical discharge and arc milling with automatic tracking of the optimal flushing direction was *** automatic tracking optimizer for external working medium injection was designed to determine the optimal external flushing direction according to the feed *** influence of flushing methods,working mediums,and machining parameters on the machining efficiency,tool electrode wear rate,machining error,and surface integrity of titanium alloys were *** results indicated that better machining performance and environmental friendliness were achieved using the compound flushing method of outer compressed air and inner deionized ***,the automatic tracking flushing method in the opposite direction of the feed direction showed superior results compared to other *** material removal rate with the opposite direction injection could be increased up to 1.62 times that of the same direction,and the relative electrode wear rate could be reduced by 14.76%.This novel method has broad application prospects for machining parts with difficult-to-cut materials in aerospace and military industries.

关键词： Arc milling Dielectric Difficult-to-cut materials Electric discharge machining Erosion Material removal rate

Upconverting and downshifting circularly polarized luminescence in a superstructural helix

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Science china Chemistry 2024年第8期67卷 2571-2577页

作者： Honghan ji Bin Wu Enquan tian Chao Ren Xue jin Liangliang Zhu Pengfei Duan CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology(NCNST)Beijing 100190China State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China University of chinese Academy of Sciences Beijing 101408China

The modulation of circularly polarized luminescence(CPL) has become an increasingly prominent area of research. In this study,we propose a unique “one-excitation-to-three-emissions” CPL system through the co-assembly of an upconversion system,incorporating one sensitizer(Pt(II) mesotetraphenyl tetrabenzoporphyrine, Pt TPBP) and two annihilators(R/S-DPA and R/SBDP) within liquid crystals. The chiral nature of the annihilators induces a transformation of the nematic liquid crystal into chiral nematic liquid crystals(N*LC), establishing an excellent chiral matrix. Upon the incorporation of the sensitizer Pt TPBP and subsequent excitation at 635 nm, the system demonstrates two independent triplet–triplet annihilation photon upconversion(TTA-UC) with the emission in blue and yellow, aided by thermally activated triplet–triplet energy transfer(TTET). This is accompanied by the simultaneous generation of upconverting circularly polarized luminescence(UC-CPL) and downshifting near-infrared circularly polarized luminescence(DS-CPL) originating from the residual luminescence of Pt TPBP. Remarkably,fine-tuning the ratio between the two annihilators allows the TTA-UC system to exhibit multicolor CPL emission with an amplified luminescence dissymmetry factor(glum, reaching up to 0.6). Our study unveils a previously unreported “one-excitation-to-three-emissions” system and provides a versatile strategy for modulating CPL emissions, surpassing conventional methodologies.

关键词： circularly polarized luminescence triplet–triplet annihilation upconversion near-infrared emission chiral nematic liquid crystal luminescence dissymmetry factor

Advanced Machine Learning Methods for Prediction of Blast-Induced Flyrock Using Hybrid SVR Methods

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1595-1617页

作者： ji Zhou Yijun Lu Qiong tian Haichuan Liu Mahdi Hasanipanah jiandong Huang College of Civil and Environmental Engineering Hunan University of Science and EngineeringYongzhou425006China Hunan Provincial Key Laboratory of Intelligent Protection and Utilization Technology in Masonry Artifacts Hunan University of Science and EngineeringYongzhou425006China School of Civil Engineering Guangzhou UniversityGuangzhou510006China Institute of Research and Development Duy Tan UniversityDa Nang550000Vietnam School of Engineering&Technology Duy Tan UniversityDa Nang550000Vietnam

Blasting in surface mines aims to fragment rock masses to a proper ***,flyrock is an undesirable effect of blasting that can result in human *** this study,support vector regression(SVR)is combined with four algorithms:gravitational search algorithm(GSA),biogeography-based optimization(BBO),ant colony optimization(ACO),and whale optimization algorithm(WOA)for predicting flyrock in two surface mines in ***,three other methods,including artificial neural network(ANN),kernel extreme learning machine(KELM),and general regression neural network(GRNN),are employed,and their performances are compared to those of four hybrid SVR *** modeling,the measured and predicted flyrock values are validated with some performance indices,such as root mean squared error(RMSE).The results revealed that the SVR-WOA model has the most optimal accuracy,with an RMSE of 7.218,while the RMSEs of the KELM,GRNN,SVR-GSA,ANN,SVR-BBO,and SVR-ACO models are 10.668,10.867,15.305,15.661,16.239,and 18.228,***,combining WOA and SVR can be a valuable tool for accurately predicting flyrock distance in surface mines.

关键词： Flyrock induced by blasting optimization algorithms SVR GRNN