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Effect of heat treatment on microstructural evolution,mechanical properties and tribological properties of H13 steel prepared using selective laser melting

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Journal of Iron and Steel Research International 2024年第5期31卷 1246-1259页

作者： li-xiong Han Yan Wang Shi-feng liu Zhao-hui Zhang Wei liu Xin Yang Dang-shen Ma Jian Zhou Ying-kang Wei College of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina Zhejiang University City College Hangzhou310015ZhejiangChina China Iron and Steel Research Institute Group Co. Ltd.Beijing100081China

H13 tool steel was successfully prepared by selective laser melting(SLM)*** effects of heat treatment on the microstructure,mechanical properties,and tribological properties of SLMed H13 steel were *** heat treatment process involved a solution treatment and a double aging treatment of the deposited H13 tool steel prepared by *** aim is to optimize the microstructure and mechanical properties of SLMed H13 *** to the rapid heating and cooling effects of SLM,carbide precipitation in the deposited H13 steel was not uniform and residual stresses were *** purpose of the solution treatment is to dissolve the solution at a high temperature to eliminate the residual stresses and defects introduced by the SLM-forming *** solution treatment and first aging treatment produced the precipitation of small carbides at the grain boundaries and inside the crystals,which increased the hardness of SLMed H13 *** hardness increased from 538±4.0 HV of the as-deposited sample to 548±5.8 HV of samples after the first aging ***,the ultimate tensile strength and the elongation at break decreased from 1882 MPa and 11.5%in the as-deposited sample to 1697 MPa and 7.9%in those after the first aging treatment,***,the friction coefficient and wear rate in the as-deposited sample decreased from 0.5160 and 2.36×10^(–6)mm^(−3)N^(−1)m^(−1)to 0.4244 and 1.04×10^(–6)mm^(−3)N^(−1)m^(−1),***,the distribution of carbides inside the crystals was not *** second aging treatment adjusted the morphology of carbide precipitation and made it more uniform,but the precipitation of carbides grew and settled at the bottom of the grain *** hardness decreased to 533±6.7 HV compared with that with the first aging treatment,but the ultimate tensile strength and plasticity reached a balance(1807 MPa,14.05%).Accordingly,the friction coefficient and wear rate also showed a stable and decreasin

关键词： Selective laser melting H13 steel Solution aging Double aging Friction and wear Retained austenite

Estimation of tunnel axial orientation in the interlayered rock mass using a comprehensive algorithm

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2579-2590页

作者： hui li Weizhong Chen Xianjun Tan State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

The axial selection of tunnels constructed in the interlayered soft-hard rock mass affects the stability and safety during *** optimization is primarily based on experience or comparison and selection of alternative values under specific geological *** this work,an intelligent optimization framework has been proposed by combining numerical analysis,machine learning(ML)and optimization *** automatic and intelligent numerical analysis process was proposed and coded to reduce redundant manual *** conventional optimization algorithm was developed from two aspects and applied to the hyperparameters estimation of the support vector machine(SVM)model and the axial orientation optimization of the ***,the comprehensive framework was applied to a numerical case study,and the results were compared with those of other *** results of this study indicate that the determination coefficients between the predicted and the numerical stability evaluation indices(STIs)on the training and testing datasets are 0.998 and 0.997,*** a given geological condition,the STI that changes with the axial orientation shows the trend of first decreasing and then increasing,and the optimal tunnel axial orientation is estimated to be 87.This method provides an alternative and quick approach to the overall design of the tunnels.

关键词： Tunnel Building information modeling Design optimization Particle swarm optimization Support vector machine(SVM)

Efficacy of Mild Hypothermia for the Treatment of Patients with Cardiac Arrest

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Chinese Medical Journal 2015年第11期128卷 1536-1542页

作者： Yu Gao kang-li hui Yu-Jie Wang lin Wu Man-lin Duan Jian-Guo Xu De-Xin li Jinling Hospital Medical School of Nanjing University Nanjing Jiangsu 210000 China Department of Anesthesiology Jinling Hospital School of Medicine Nanjing University Nanjing Jiangsu 210000 China

Background： Therapeutic hypothermia has been recommended for the treatment of cardiac arrest patients who remain comatose after the return of spontaneous circulation. The aim of this study was to evaluate the effectiveness and safety of mild hypothermia on patients with cardiac arrest by conducting a meta-analysis. Methods： The relevant trials were searched in Cochrane library, PubMed, Web of Science, Embase, CNKI and Wan Fang Data from the date of their establishment to October 2014. Thereafter, the studies retrieved were screened based on predeflned inclusion and exclusion criteria. Data were extracted, and the quality of the included studies was evaluated. A meta-analysis was conducted using the Cochrane Collaboration Review Manager 5.2 sottware. Results： Six randomized controlled trials involving 531 cases were included, among which 273 cases were assigned to the treatment group and the other 258 cases to the control group. The meta-analysis indicated that mild hypothermia therapy alter cardiac arrest produced significant differences ill survival rate （relative risk [RR] =1.23, 95% confidence interval [C/]： 1.02-1.48, P = 0.03） and neurological function （RR - 1.33, 95% （.7： 1.08-1.65, P - 0.007） alter 6 months compared with normothermia therapy. However, no significant differences were observed in the survival to the hospital discharge （RR = 1.35, 95% CI： 0.87-2.10, P - 0.1 8）, favorable neurological outcome at hospital discharge （RR = 1.53, 95% CI： 0.95 2.45, P = 0.08） and adverse events. Conclusions： The meta-analysis demonstrated that mild hypothermia can improve the survival rate and neurological function of patients with cardiac arrest after 6 months. On the other hand, regarding the survival to hospital discharge, favorable neurological outcome at hospital discharge, and adverse events, our meta-analysis produced nonsignificant results.

关键词： Cardiac Arrest Cardiopulmonary Resuscitation Mild Hypothermia Neurological Function Survival Rate

Machine Learning-based Identification of Contaminated Images in light Curve Data Preprocessing

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Research in Astronomy and Astrophysics 2024年第4期24卷 287-295页

作者： hui li Rong-Wang li Peng Shu Yu-Qiang li Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Space Object and Debris Observation Chinese Academy of SciencesNanjing 210023China

Attitude is one of the crucial parameters for space objects and plays a vital role in collision prediction and debris *** light curves to determine attitude is the most commonly used *** photometric observations,outliers may exist in the obtained light curves due to various ***,preprocessing is required to remove these outliers to obtain high quality light *** statistical analysis,the reasons leading to outliers can be categorized into two main types:first,the brightness of the object significantly increases due to the passage of a star nearby,referred to as“stellar contamination,”and second,the brightness markedly decreases due to cloudy cover,referred to as“cloudy contamination.”The traditional approach of manually inspecting images for contamination is time-consuming and ***,we propose the utilization of machine learning methods as a *** Neural Networks and SVMs are employed to identify cases of stellar contamination and cloudy contamination,achieving F1 scores of 1.00 and 0.98 on a test set,*** also explore other machine learning methods such as ResNet-18 and light Gradient Boosting Machine,then conduct comparative analyses of the results.

关键词： techniques:image processing methods:data analysis light pollution

Optical and electrical anisotropy regulation engineering of low-dimensional materials toward polarized detection and imaging applications

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Rare Metals 2024年第7期43卷 2968-2993页

作者： Jian-Bin Zhang Nan Zhou li-hui Zhang Cong-hui Shang Jia-Xuan li Yi Zhao Guo-hui Jia Ru-Sen Yang Hua Xu Xiao-Bo li Shaanxi Joint Key Laboratory of Graphene Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for AerospaceShaanxi Joint Key Laboratory of GrapheneSchool of Advanced Materials and NanotechnologyXidian UniversityXi'an710126China Guangzhou Institute of Technology Xidian UniversityGuangzhou 710068China Xi'an Thermal Power Research Institute Co. LtdXi'an 710054China Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi'an Xi'an 710119China

Polarized-sensitive image sensors are a kind of photodetector with great development potential due to their enhanced ability to detect and identify the target objects from the aspect of spatial,spectral and polarized ***,low-dimensional anisotropic materials with inherent anisotropic properties,ultrathin thickness,tunable bandgap and feasible integration with complementary metal oxide semiconductor(CMOS)fabrication processes have attracted great interest for their facilitation of polarized photodetector devices *** the polarized detection performance of low-dimensional materials to satisfy realistic needs stimulates the exploration of modulation of anisotropic *** this review,we comprehensively introduce the latest research progress in modulating the optical and optoelectronic anisotropy characteristics of low-dimensional *** strategy of anisotropy regulation through crystal structure engineering and coupling system is discussed ***,the latest progress in image recognition applications using anisotropic low-dimensional materials is reviewed in ***,we summarize the challenge and propose future opportunities in the practical application of polarized-sensitive imaging photodetectors based on low-dimensional anisotropic materials.

关键词： Anisotropy Polarized detection Image recognition Low-dimensional materials

Vision-Based Adaptive Prescribed-Time Control of UAV for Uncooperative Target Tracking with Performance Constraint

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Journal of Systems Science & Complexity 2024年第5期37卷 1956-1977页

作者： SHE Xuehua MA hui REN Hongru li Hongyi School of Automation and the Guangdong Provincial Key Laboratory of Intelligent Decision and Cooperative Control Guangdong University of TechnologyGuangzhou 510006China School of Mathematics and Statistics Guangdong University of TechnologyGuangzhou 510006China College of Electronic and Information Engineering and Chongqing Key Laboratory of Generic Technology and System of Service Robots Southwest UniversityChongqing 400715China

This paper discusses the uncooperative target tracking control problem for the unmanned aerial vehicle(UAV)under the performance constraint and scaled relative velocity constraint,in which the states of the uncooperative target can only be estimated through a vision *** the limited detection range,a prescribed performance function is designed to ensure the transient and steady-state performances of the tracking ***,the scaled relative velocity constraint in the dynamic phase is taken into account,and a time-varying nonlinear transformation is used to solve the constraint problem,which not only overcomes the feasibility condition but also fails to violate the constraint ***,the practically prescribed-time stability technique is incorporated into the controller design procedure to guarantee that all signals within the closed-loop system are *** is proved that the UAV can follow the uncooperative target at the desired relative position within a prescribed time,thereby improving the applicability of the vision-based tracking *** results have been presented to prove the validity of the proposed control strategy.

关键词： Nonlinear transformation performance constraint prescribed-time tracking uncooperative target vision-based measurement

Effects of physical properties of supercritical water on heat transfer characteristics of single particle within a particle cluster Author links open overlay panel

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Particuology 2024年第8期91卷 291-302页

作者： Xiaoyu li Bowei Zhang huibo Wang hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049China

The complex physical properties of supercritical water(SCW)make the heat transfer characteristics of particles within a particle cluster *** heat transfer characteristics of single particle within a particle cluster in SCW,influenced by surrounding particles,have not been effectively *** numerical simulations were conducted to investigate the heat transfer characteristics of particle clusters in SCW under different *** results were compared and analyzed with those from constant property *** was found that Reynolds number(Re)and the void fraction of particle cluster have no special effects on the variation trends of Nusselt number(Nu)for the focused ***,the particle temperature had a significant effect on the variation trends of *** effect of Re on the heat transfer rate exponent(η)of the focused particle can be divided into two zones:a significant effect zone and a non-significant effect *** effect of void fraction onηin the non-significant effect zone was *** the non-significant effect zone,ηdecreased with the increasing particle *** the significant effect zone,the variation trends ofηbecame more *** fundamental reason for this series of phenomena is the changes in distribution of physical properties.A model forηwas developed for the non-significant effect *** model can filter out the effects of Re and certain particle cluster spatial configurations,and it demonstrates good predictive performance.

关键词： Supercritical water Particle cluster Heat transfer characteristics Heat transfer rate exponent Physical properties correction

Robust Interval State Estimation for Distribution Systems Considering Pseudo-measurement Interval Prediction

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 179-188页

作者： Xu Zhang Wei Yan Meiqing Huo hui li the School of Electrical Engineering Chongqing UniversityChongqing 400044China

Interval state estimation(ISE)can estimate state intervals of power systems according to confidence intervals of predicted pseudo-measurements,thereby analyzing the impact of uncertain pseudo-measurements on ***,predicted pseudo-measurements have prediction errors,and their confidence intervals do not necessarily contain the truth values,leading to estimation biases of the *** solve this problem,this paper proposes a pseudo-measurement interval prediction framework based on the Gaussian process regression(GPR)model,thereby improving the prediction accuracy of pseudo-measurement confidence ***,a weight assignment strategy for improving the robustness of weighted least squares(WLS)ISE is *** strategy quantifies the deviation between the pseudo-measurement intervals and their estimated intervals and assigns smaller weights to the pseudo-measurement intervals with larger deviations,thereby improving the estimation accuracy and robustness of the *** paper adopts the data from the supervisory control and data acquisition(SCADA)system of the New York Independent System Operator(NYISO).It verifies the advantages of the GPR method for pseudo-measurement interval prediction by comparing it with the quantile regression and neural network *** addition,this paper demonstrates the effectiveness of the proposed weight assignment strategy through the IEEE 14-bus ***,the differences in the estimation accuracy and the bad data identification between the robust interval state estimation and deterministic state estimation are discussed.

关键词： Interval state estimation interval analysis pseudo-measurement Gaussian process regression(GPR)

Mitigation of black carbon emissions could immediately reduce 6.3% of glacier melting in the Qilian Mountains

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Advances in Climate Change Research 2024年第4期15卷 725-736页

作者： Ji-Zu CHEN Wen-Tao DU Shi-Chang kang Xiang QIN Wei-Jun SUN li-hui LUO Yang li Jun-Hua YANG You-Yan JIANG Qilian Shan Station of Glaciology and Eco-environment Key Laboratory of Cryospheric Science and Frozen Soil EngineeringNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Geography and Environment Shandong Normal UniversityJinan 250014China Zhangye Meteorological Bureau Zhangye 734000China Lanzhou Regional Climate Center Lanzhou 730020China Institute of International Rivers and Eco-security Yunnan UniversityKunming 650500China Gansu Provincial Industry Technology Center of Inteligent Equipment and Big Data for Disaster Prevention Northwest Institute of Eco-Environment and ResourcesChinese Academy of ScienceLanzhou 730000China

Global warming in tandem with surface albedo reduction caused by black carbon(BC)deposition on glaciers accelerated glacier melting;however,their respective contributions remain *** in the Qilian Mountains are crucial for the development of oases in the Hexi Corridor;however,their area has decreased by more than 20%over the past ***,this study developed a dynamic deposition model for light-absorbing particles(LAPs),coupled with a surface energy and mass balance *** comprehensively assessed the effects of BC and warming on the melting of a typical glacier in the Qilian Mountains based on the coupled *** on the glacier surface caused 13.1%of annual glacier-wide melting,of which directly deposited atmospheric BC reduced the surface albedo by 0.02 and accounted for 9.1%of glacier *** air temperature during 2000-2010 has increased by 1.5°C relative to that during the 1950s,accounting for 51.9%of current glacier ***,BC emission have increased by 4.6 times compared to those of the early Industrial Revolution recorded in an ice core,accounting conservatively for 6.3%of current glacier *** BC emissions has a limited influence on current glacier melting;however,in the long-term,mitigation should exert a noteworthy impact on glacier melting through the self-purification of glaciers.

关键词： Glacier Melting Black carbon Simulation Qilian Mountains