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Optimization of ECAP-RAP process for preparing semisolid billet of 6061 aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 792-800页

作者： zu-jian Yang Kai-kun Wang Yan Yang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization Jinchang 737100China

6061 aluminum alloy semisolid billet was prepared by the equal-channel angular processing(ECAP)-recrystallization and partial(RAP)process(a combination of equal-channel angular processing and recrystallization and partial remelting).The effects of different process parameters on the alloy microstructure were studied and the quantitative relationship between the process parameters and microstructure was established by response surface methodology(RSM)to optimize the process *** to the orthogonal test,the holding temperature and holding time of the four ECAP-RAP process parameters were found to have the greatest impact on the microstructural characteristics,including average grain size and average shape *** RSM,it was also found that when the average grain size or the average shape factor is optimized separately,another will be *** the two indexes were simultaneously considered,the optimal process parameters were found to be a holding temperature of 623°C and holding time of 13 min,and the corresponding average grain size and average shape factor were 35.97μm and 0.8535,***,comparing the experimental and predicted values,the reliability of the established response surface model was verified.

关键词： 6061 aluminum alloy equal-channel angular pressing semisolid microstructure response surface methodology

Energy Estimate for the Type-Ⅱ Superconducting Film

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Acta Mathematica Sinica,English Series 2008年第1期24卷 75-86页

作者： Kwang Ik KIM zu Han LIU Department of Mathematics Pohang University of Science and Technology Pohang 790-784 Republic of Korea Department of Mathematics Xuzhou Normal University Xuzhou 221116 P. R. China

We study the minimizers of the Ginzburg-Landau model for variable thickness, superconducting, thin films with high k, placed in an applied magnetic field hex, when hex is of the order of the ＂first critical field＂, i.e. of the order of ｜lnε｜. We obtain the asymptotic estimates of minimal energy and describe the possible locations of the vortices.

关键词： superconductivity Ginzburg-Landau functional free boundary problem

A probabilistic model based on the peak-over-threshold approach for risk assessment of airport controllers’performance

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Journal of Safety Science and Resilience 2024年第1期5卷 110-118页

作者： Lili zu Yijie Lu Min Dong College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Engineering and Applied Science George Washington UniversityWashington DC 20052USA College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Airport tower control plays an instrumental role in ensuring airport ***,obtaining objective,quantitative safety evaluations is challenging due to the unavailability of pertinent human operation *** study introduces a probabilistic model that combines aircraft dynamics and the peak-over-threshold(POT)approach to assess the safety performance of airport *** applied the POT approach to model reaction times extracted from a radiotelephony dataset via a voice event detection *** model couples the risks of tower control and aircraft operation to analyze the influence of human *** data from radiotele-phony communications and the Base of Aircraft Data(BADA)database,we compared risk levels across *** findings revealed heightened airport control risks under low demand(0.374)compared to typical conditions(0.197).Furthermore,the risks associated with coupling under low demand exceeded those under typical de-mand,with the final approach stage presenting the highest risk(4.929×107).Our model underscores the significance of human factors and the implications of mental disconnects between pilots and controllers for safety ***,these consistent findings affirm the reliability of our probabilistic model as an evaluative tool for evaluating the safety performance of airport tower *** results also illuminate the path toward quantitative real-time safety evaluations for airport controllers within the *** recommend that airport regulators focus on the performance of airport controllers,particularly during the final approach stage.

关键词： Safety evaluation Performance Probabilistic model Task demand Airport controller

Distribution management system framework based on security region for future low carbon distribution systems

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Journal of Modern Power Systems and Clean Energy 2015年第4期3卷 544-555页

作者： Jun XIAO Qibo HE Guoqiang zu Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjinChina

In this paper,a new Distribution Management System(DMS)framework based on security region is ***,the concept of Distribution System Security Region(DSSR)is *** is capable to describe the N-1 security boundary of the whole distribution network,including the secure output range of *** new theoretic tool provides a chance for the implementation of real-time security analysis and active controls in ***,this paper proposes and describes five security states for distribution ***,an upgraded DMS enhanced with DSSR is proposed,which consists of advanced security functions such as preventive and predictive control of the trajectory of operating ***,a practical case is presented to simulate the proposed DSSR-enhanced DMS,in which both the security region of network and the output range of DGs are *** security functions are also *** conclusion,the new DMS framework aims to help operate the system closed to its security boundary in order to improve the efficiency significantly within same security *** work is beneficial for future low carbon distribution systems with high penetration rate of DGs.

关键词： DMS Security region N-1 security Distributed generation Preventive control Low carbon

Probing the dark side of the Universe with weak gravitational lensing effects

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Research in Astronomy and Astrophysics 2014年第9期14卷 1061-1120页

作者： Li-Ping Fu zu-Hui Fan Shanghai Key Lab for Astrophysics Shanghai Normal University Department of Astronomy School of Physics Peking University

Arising from gravitational deflections of light rays by large-scale struc- tures in the Universe, weak-lensing effects have been recognized as one of the most important probes in cosmological studies. In this paper, we review the main progress in weak-lensing analyses, and discuss the challenges in future investigations aiming to understand the dark side of the Universe with unprecedented precisions.

关键词： cosmology: dark matter and dark energy -- large-scale structure of uni- verse -- gravitational lensing

Light-induced electro-rotation:Microspheres spin in micro-manipulation using light-induced dielectrophoresis

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Science China(Technological Sciences) 2011年第11期54卷 3035-3046页

作者： NI ZhongHua zu ShuCun CHEN Ke Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments School of Mechanical Engineering Southeast University Nanjing 210096 China

According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark regions on the photoconductive layer was ***,the phenomenon of the light-induced electro-rotation(LIER) caused by the light-induced rotating electric field was confirmed numerically and experimentally for the first *** may be helpful to go out of the dilemma that only the dipole moment model,based on the effect of light-induced partial potentials,can be used for LIDEP theoretical calculation *** the FEM simulation and the electro-rotating experiment of yeast cells,it was found that the direction of yeast's LIER is relevant to the distance between its location and the edge of optical electrode,and the spin velocity of LIER is inversely proportional to that ***,the LIER torques in the three-electrode mode show a non-uniform distribution where the LIDEP forces are harmful for a particle spinning stably around a fixed ***,a four-electrode double-layer mode was proposed for the first time and the finite element simulation results agreed with the expected design,suggesting a new way for the dielectric spectrum measurement based on LIER.

关键词： light-induced dielectrophoresis light-induced electro-rotation microfluidic device

Viability Property of Jump Diffusion Processes on Manifolds

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Acta Mathematicae Applicatae Sinica 2016年第2期32卷 349-354页

作者： Xue-hong ZHU Guang-zu LIU School of Science Nanjing University of Aeronautics and Astronautics School of Electronic and Optical Engineering Nanjing University of Science and Technology

In this note, we give a necessary and sufficient condition for viability property of diffusion processes with jumps on closed submanifolds of Rm. Our result is the system is viable in a closed submanifold K iff the coefficients are tangent to K along K if the equation is in the sense of stratonovich integral and the solution jumps from K to K.

关键词： viability property viscosity solution manifold

Magnetic Properties of a Mixed Spin-2 and Spin-5/2 Heisenberg Ferrimagnetic System on a Two-Dimensional Honeycomb Lattice： Green＇s Function Approach

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Communications in Theoretical Physics 2007年第4期47卷 741-746页

作者： YAO Kai-Lun LI Jian-Wen LIU zu-Li FU Hua-Hua zu Lin Department of Physics Huazhong University of Science and Technology Wuhan 430074 China International Center of Material Physics the Chinese Academy of Sciences Shenyang 110015 China

The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the different interactions in the Hamiltonian is explored. When only the nearest-neighbor interaction and the single-ion anisotropy are included, our results indicate that there are compensation points at finite temperatures. When the next-nearest-neighbor interaction exceeds a minimum value that depends on the other parameters in the Hamiltonian, the compensation point disappears. The next-nearest-neighbor interaction has the effect of changing the compensation temperature.

关键词： Heisenberg ferrimagnetic Green function spin-wave spectra magnetization critical temperature compensation temperature

Equilibrium of Organic Matter in Heavy Fraction for Three Long-term Experimental Field Soils in China

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Pedosphere 2006年第2期16卷 177-184页

作者： YIN Yun-Feng CAI zu-Cong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 （China）.

Considerable evidence that the soil organic matter （OM） level in agricultural soils will gradually over time reach an equilibrium state under certain bioclimatic conditions and for certain cropping systems has been accumulating. Although models or long-term experiments have been used, this research used physical fractionation procedure to attain an soil OM equilibrium value. To obtain soil OM equilibrium values in the heavy fraction, typical soils from three long-term field experiments at Fengqiu and Yingtan State Key Agro-Ecological Experimental Stations in China were studied using a simple density fractionation procedure and employing the Langmuir equation. Results for the fluvo-aquic soil with organic fertilizer treatments indicated that the soil OM equilibrium value in the heavy fraction was twofold more than that in the inorganic treatments; however, for the paddy soil developed on red soil the OM equilibrium value in the heavy fraction for both treatments was almost identical. It suggested that for fiuvo-aquic soils the increased potential of OM for the heavy fraction in the long run was larger for the organic than the inorganic fertilizer applications, whereas for paddy soils developed on red soils under the same conditions the present OM content in the heavy fraction was at or close to this equilibrium level for all treatments, and increased potential was very limited.

关键词： equilibrium value heavy fraction Langmuir equation soil organic matter