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Stage identification and process optimization for fast drilling EDM of film cooling holes using KBSI method

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Advances in Manufacturing 2023年第3期11卷 477-491页

作者： Jian Wang Xue-Cheng Xi ya-ou zhang Fu-Chun Zhao Wan-Sheng Zhao State Key Laboratory of Mechanical System and Vibration Shanghai 200240People's Republic of China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240People's Republic of China

Fast drilling electrical discharge machining(EDM)is widely used in the manufacture of film cooling holes of turbine ***,due to the various hole orientations and severe electrode wear,it is relatively intricate to accurately and timely identify the critical moments such as breakout,hole completion in the drilling process,and adjust the machining strategy *** breakout detection and hole completion determination methods are not suitable for the high-efficiency and fully automatic production of film cooling holes,for they almost all depend on preset thresholds or training data and become less appropriate when machining condition *** the breakout and hole completion detection problems can be abstracted to an online stage identification problem,in this paper,a kurtosis-based stage identification(KBSI)method,which uses a novel normalized kurtosis to denote the recent changing trends of gap voltage signals,is developed for online stage *** identification accuracy and generalization ability of the KBSI method have been verified in various machining *** improve the overall machining efficiency,the influence of servo control parameters on machining efficiency of each machining stage was analyzed experimentally,and a new stage-wise adaptive control strategy was then proposed to dynamically adjust the servo control parameters according to the online identification *** performance of the new strategy is evaluated by drilling film cooling holes at different hole *** results show that with the new control strategy,machining efficiency and the machining quality can be significantly improved.

关键词： Fast drilling electrical discharge machining(EDM) Film cooling holes Breakout detection Hole completion determination Stage identification Process optimization

Alleviating the anisotropic microstructural change and boosting the lithium ions diffusion by grain orientation regulation for Ni-rich cathode materials

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Journal of Energy Chemistry 2024年第1期88卷 213-222,I0005页

作者： Xinyou He Shilin Su Bao zhang Zhiming Xiao Zibo zhang Xing ou Engineering Research Center of the Ministry of Education for Advanced Battery Materials School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083HunanChina Zhejiang Power New Energy Co.Ltd Zhuji 311899ZhejiangChina

Generally,layered Ni-rich cathode materials exhibit the morphology of polycrystalline secondary sphere composed of numerous primary *** the arrangement of primary particles plays a very important role in the properties of Ni-rich *** disordered particle arrangement is harmful to the cyclic performance and structural stability,yet the fundamental understanding of disordered structure on the structural degradation behavior is ***,we have designed three kinds of LiNi_(0.83)Co_(0.06)Mn_(0.11)O_(2) cathode materials with different primary particle orientations by regulating the precursor coprecipitation *** finite element simulation and in-situ characterization,the Li^(+)transport and structure evolution behaviors of different materials are ***,the smooth Li^(+)diffusion minimizes the reaction heterogeneity,homogenizes the phase transition within grains,and mitigates the anisotropic microstructural change,thereby modulating the crack evolution ***,the optimized structure evolution ensures radial tight junctions of the primary particles,enabling enhanced Li^(+)diffusion during dynamic ***-loop bidirectional enhancement mechanism becomes critical for grain orientation regulation to stabilize the cyclic *** precursor engineering with particle orientation regulation provides the useful guidance for the structural design and feature enhancement of Ni-rich layered cathodes.

关键词： Ni-rich cathode Grain orientation regulation Anisotropic microstructural change Precursor engineering Li~+-ions diffusion

Examining the Spatiotemporal Dynamics and Determinants of Land Urbanization in Prefecture-level Cities,China

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Chinese Geographical Science 2024年第1期34卷 19-33页

作者： yaNG Zhen ZHU Huxiao zhang Xinlin ou Xiangjun School of Geography Geomatics and Planning&Urban-rural Integration Development Research InstituteJiangsu Normal UniversityXuzhou221116China

Examining the spatiotemporal dynamics and determinants of land urbanization is critical for promoting healthy urban development and the rational use of land *** on the dataset consisting of land use change data and selected factors in 2010 and2020,this study used visual analysis to reveal the spatiotemporal dynamics of land urbanization across prefecture-level cities in ***,the driving forces underlying land urbanization were examined by using geographical detector *** are the findings:1)we find that there exist notable spatial variances in land urbanization across prefecture-level ***,the differentiation in land urbanization between the northern and southern cities is more pronounced than that between the coastal and inland cities,or between the eastern and western ***-level cities located in central and western China have experienced the most rapid growth in land ***,the growth rate in northeastern China is the lowest,while the velocity in eastern China remains relatively *** using spatial autocorrelation analysis,this study reveals that the land urbanization level in prefecture-level cities has significant spatial agglomeration.2)We further find that land urbanization in China is influenced by factors related to urban land supply and demand,and urban population growth,economic growth,land financial and political incentive have greater impact on land urbanization than other factors.3)We also find that the impacts of determinants on China’s land urbanization vary over time,the explanatory power of economic development increased,while the explanatory power of state forces *** argue that integrating the supply and demand factors of land urbanization can provide a more comprehensive understanding of the driving mechanisms underlying land urbanization in China and other transitional countries,and help decision-makers in these countries formulate more detailed and specif

关键词： land urbanization spatial pattern influencing factor geographical detector China

Heat dissipation of carbon shell in ZrC-SiC/TaC coating to improve protective ability against ultrahigh temperature ablation

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Journal of Advanced Ceramics 2024年第7期13卷 1080-1091页

作者： Yuyu zhang Xuemeng zhang Hongkang ou Bozhe Wang Jia Sun Qiangang Fu Science and Technology on Thermostructural Composite Materials Laboratory Shaanxi Key Laboratory of Fiber Reinforced Light-Weight CompositesNorthwestern Polytechnical UniversityXi’an 710072China System Design Institute of Hubei Aerospace Technology Academy Wuhan 430040China

To efficiently decrease ablation heat accumulation and improve the ability of ZrC-SiC/TaC coatings to protect carbon/carbon(C/C)composites,a thermally conductive nanonetwork with a ceramic@carbon core-shell structure was designed and ***-derived SiC/TaC with a graphene carbon shell was synthesized and introduced into a ZrC coating by supersonic atmospheric plasma spraying(SAPS).Graphene shell paths increased the heat transfer capability by lowering the surface temperature to approximately 200℃during oxyacetylene *** heat dissipation of the graphene shell in the ZrC-SiC/TaC@C coating reduced the volatilization of low-melting-point phases and delayed the sintering of ZrO2 ***,the graphene shell in ZrC-SiC/TaC@C coating decreased the mass and linear ablation rates by 91.4%and 93.7%compared to ZrC-SiC/TaC coating,*** work provided a constructive idea for improving the ablation resistance of the coatings by incorporating carbon nanomaterials as a function of heat dissipation.

关键词： carbon/carbon(C/C)composites carbon nanomaterials core-shell structure polymer-derived ceramic(PDC) ablation resistance

Luminescence and magnetic properties of bifunctional nanoparticles composited by nitrogen-doped graphene quantum dots and gadolinium

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Journal of Rare Earths 2024年第4期42卷 716-723页

作者： Wanli zhang Hao Zhou Meigui ou Donghao Sun Chunlin yang College of Materials and Metallurgy University of GuizhouGuiyang550025China National Local Co-construction Engineering Laboratory for High Performance Metal Structure Material and Manufacture Technology Guiyang550025 China College of Chemistry and Materials Engineering Guiyang UniversityGuiyang550003China

In this paper,nitrogen-doped graphene quantum dots(N-GQDs)were combined with gadolinium ions(Gd^(3+))by a surface modification to obtain magneto-optical dual-functional N-GQDs/Gd^(3+)*** morphology of obtained composite was characterized by field emission scanning electron microscopy and transmission electron *** and magnetic properties were measured by a fluorescence spectrophotometer and a vibrating sample magnetometer,*** indicate that well-dispersed spherical N-GQDs/Gd^(3+)nanoparticles have an average diameter of 7 nm.N-doping significantly increases the luminesce nce of particles with an optimal luminescence intensity at 20℃and pH=9.X-ray photoelectron spectroscopy results indicate that the N-doping introduces pyrrolic N as an electron donor,enhancing fluorescence by increasing the surface electron cloud density of *** addition,density functional theory calculation results reveal that N-doping reduces the band gap of NGQDs/Gd^(3+),enabling electronic transitions to higher energy levels and generating more activation sites,thereby enhancing *** to N-GQDs/Gd^(3+)prepared at 20℃,the saturated magnetization of particles prepared at 40℃is 0.85 emu/g,indicating a better magnetic *** above results suggest that bifunctional nanomaterials N-GQDs/Gd^(3+)with excellent optical properties and magnetism can be better used for fluorescence and magnetic resonance imaging.

关键词： Nitrogen-doped graphenequantum dots Gadolinium Luminescence Magnetism Rare earths

Re-examination of statistical relationships between dietary fats and other risk factors,and cardiovascular disease,based on two crucial datasets

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Quantitative Biology 2024年第1期12卷 117-127页

作者： Jiarui ou Le zhang Xiaoli Ru College of Computer Science Sichuan UniversityChengduChina Department of Gynecology and Obstetrics Beijing Chao-Yang HospitalCapital Medical UniversityBeijingChina

Cardiovascular disease(CVD)is the major cause of death in many regions around the world,and several of its risk factors might be linked to *** improve public health and the understanding of this topic,we look at the recent Minnesota Coronary Experiment(MCE)analysis that used t-test and Cox model to evaluate CVD ***,these parametric methods might suffer from three problems:small sample size,right-censored bias,and lack of long-term *** overcome the first of these challenges,we utilize a nonparametric permutation test to examine the relationship between dietary fats and serum total *** address the second problem,we use a resampling-based rank test to examine whether the serum total cholesterol level affects CVD *** the third issue,we use some extra-Framingham Heart Study(FHS)data with an A/B test to look for meta-relationship between diets,risk factors,and CVD *** show that,firstly,the link between low saturated fat diets and reduction in serum total cholesterol is ***,reducing serum total cholesterol does not robustly have an impact on CVD hazards in the diet ***,the A/B test result suggests a more complicated relationship regarding abnormal diastolic blood pressure ranges caused by diets and how these might affect the associative link between the cholesterol level and heart disease *** study not only helps us to deeply analyze the MCE data but also,in combination with the long-term FHS data,reveals possible complex relationships behind diets,risk factors,and heart disease.

关键词： A/B test bioinformatics cardiovascular disease nonparametric statistics

Development of a convolutional neural network based geomechanical upscaling technique for heterogeneous geological reservoir

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2111-2125页

作者： Zhiwei Ma Xiaoyan ou Bo zhang Earth and Environmental Sciences Division Los Alamos National LaboratoryLos AlamosUSA Civil and Environmental Engineering University of AlbertaEdmontonCanada

Geomechanical assessment using coupled reservoir-geomechanical simulation is becoming increasingly important for analyzing the potential geomechanical risks in subsurface geological ***,a robust and efficient geomechanical upscaling technique for heterogeneous geological reservoirs is lacking to advance the applications of three-dimensional(3D)reservoir-scale geomechanical simulation considering detailed geological ***,we develop convolutional neural network(CNN)proxies that reproduce the anisotropic nonlinear geomechanical response caused by lithological heterogeneity,and compute upscaled geomechanical properties from CNN *** CNN proxies are trained using a large dataset of randomly generated spatially correlated sand-shale realizations as inputs and simulation results of their macroscopic geomechanical response as *** trained CNN models can provide the upscaled shear strength(R^(2)>0.949),stress-strain behavior(R^(2)>0.925),and volumetric strain changes(R^(2)>0.958)that highly agree with the numerical simulation results while saving over two orders of magnitude of computational *** is a major advantage in computing the upscaled geomechanical properties directly from geological realizations without the need to perform local numerical simulations to obtain the geomechanical *** proposed CNN proxybased upscaling technique has the ability to(1)bridge the gap between the fine-scale geocellular models considering geological uncertainties and computationally efficient geomechanical models used to assess the geomechanical risks of large-scale subsurface development,and(2)improve the efficiency of numerical upscaling techniques that rely on local numerical simulations,leading to significantly increased computational time for uncertainty quantification using numerous geological realizations.

关键词： Upscaling Lithological heterogeneity Convolutional neural network(CNN) Anisotropic shear strength Nonlinear stressestrain behavior

Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

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Petroleum Science 2024年第3期21卷 2048-2065页

作者： Qing-Ping Li Jin-ya zhang Jia-Xiang zhang Yong-Xue zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural Gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

A Comprehensive Review on Mechanisms and Applications of Rare-Earth Based Perovskite Nanocrystals

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Chinese Journal of Chemistry 2024年第9期42卷 1032-1056页

作者： Xiaoshan zhang Yikun Wang Xiang Wu Feilong Wang Qiongrong ou Shuyu zhang Academy for Engineering and Technology Institute of Future LightingFudan UniversityShanghai 200433China School of Information Science and Technology Institute for Electric Light SourcesFudan UniversityShanghai 200433China

Rare earth(RE)ions,with abundant 4f energy level and unique electronic arrangement,are considered as substitutes for Pb^(2+)in perovskite nanocrystals(PNCs),allowing for partial or complete replacement of lead and minimizing environmental *** review provides a comprehensive overview of the characteristics of RE-doped PNCs,including up-conversion luminescence,down-conversion luminescence,and quantum confinement effects,***,RE doping has been found to effectively suppress defect formation,reduce nonradiative recombination,enhance photoluminescence quantum yield(PLQY),and even allow for controlling over the morphology of the *** review also highlights the recent advancements in lead-free RE-based perovskites,especially in the case of Eu-based perovskites(CsEuBr_(3) and CsEuCl_(3)).Furthermore,it briefly introduces the applications of PNCs in various fields,such as perovskite solar cells(PSCs),luminescent solar concentrators(LSCs),photodetectors(PDs),and light-emitting diodes(LEDs).A systematic discussion on the luminescence mechanisms of RE-doped PNCs and lead-free RE-based perovskites is provided,along with an outlook on future research *** ultimate goal of this review is to provide guidance for the development of RE-based perovskite optoelectronic devices.

关键词： Perovskite nanocrystals Rare earth Lead-free perovskite lon doping Rare earth-based perovskite nanocrystals