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Tungsten 2024年第3期6卷 610-620页

作者： Jia-Hao Ye Liu-Jie Xu Ji-kang hu School of Materials Science and Engineering Henan University of Science and Technology National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials Henan University of Science and Technology

In this work,isothermal compression experiments of macroporous W-4.8 vol.%ZrO2（W-4.8ZrO2） at 1300-1600℃ and strain rate of 0.005-1 s-1were carried out on a Gleeble-1500D thermo-mechanical simulator.The dynamic recovery of W-4.8ZrO2is the main "softening" mechanism.On the basis of Arrhenius model,the initial constitutive equation is established by exploring the influence of temperature,strain rate and rheological stress.Based on Arrhenius model,the relationship between flow stress,strain rate and deformation temperature is established.Considering the influence of strain,the improved constitutive equation and the law of material constant changing with the strain are obtained.After that,the hot processing maps were drawn on the basis of the dynamic material model,which is used to analyze the instability mechanism of the W-4.8ZrO2,and determine the appropriate hot working process parameters(temperature:1350-1450℃,strain rate:0.1-1 s-1).

关键词： Tungsten alloy Flow characteristics Constitutive equation Hot processing maps

Reproducible Learning of Gaussian Graphical Models via Graphical Lasso Multiple Data Splitting

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Acta Mathematica Sinica,English Series 2024年

作者： kang hu Danning LI Binghui LIU KLAS and School of Mathematics & Statistics Northeast Normal University

Gaussian graphical models (GGMs) are widely used as intuitive and efficient tools for data analysis in several application domains. To address the reproducibility issue of structure learning of a GGM,it is essential to control the false discovery rate (FDR) of the estimated edge set of the graph in terms of the graphical model. Hence, in recent years, the problem of GGM estimation with FDR control is receiving more and more attention. In this paper, we propose a new GGM estimation method by implementing multiple data splitting alternatively. Instead of using the node-by-node regressions to estimate each row of the precision matrix, we suggest directly estimating the entire precision matrix using the graphical Lasso in the multiple data splitting, and our calculation speed is p times faster than the previous speed. We show that the proposed method can asymptotically control FDR, and the simulation study suggests that with suitable FDR and power results, the proposed method has significant advantages in computational efficiency. Finally, we demonstrate the usefulness of the proposed method through a real data analysis.

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Normalized glandular dose coefficients for digital breast tomosynthesis using detailed Chinese breast models

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Nuclear Science and Techniques 2024年第5期35卷 42-59页

作者： Jia-Hao Wang Rui Qiu An-kang hu Ye-Qi Liu Zhen Wu hui Zhang Jun-Li Li Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging Ministry of EducationTsinghua UniversityBeijing 100084China Joint Institute of Tsinghua University Nuctech Company Limited BeijingBeijing 100084China

The rise in breast cancer diagnoses among Chinese women has necessitated the use of X-ray breast screening,which carries a radiation risk.This study aimed to provide a dosimetry protocol for the Chinese female population to replace the traditional standard that utilizes simplified breast models,for the accurate estimation of the mean glandular dose of a patient undergoing digital breast tomosynthesis(DBT).The first set of detailed Chinese female breast models and representative breast parameters was constructed.Considering backscatter radiation and computational efficiency,we improved the combination of these models and the Chinese reference adult female whole-body voxel phantom.Image acquisition for four commercial DBT systems that are widely employed in China was simulated using the Monte Carlo method to obtain the normalized glandular dose coefficients of DBT(D_(gN)^(DBT))and the glandular depth dose(D_(g)^(dep)(z))for different breast characteristics and X-ray spectra.We calculated a series of DDBT gN values for breasts with different percentage mass glandularities(5%,25%,50%,75%,and 100%)and compressed breast thicknesses(2,3,4,5,6,and 7 cm)at various tube potentials(25,28,30,32,35,and 49 kV)and target/filter combinations(W/Rh,W/Al,Mo/Mo,Rh/Rh,and Rh/Ag).The parameter dependence of the breast characteristics and beam conditions on D_(gN)^(DBT) in detailed breast models was investigated.The D_(gN)^(DBT) results were 14.6-51.0%lower than those of the traditional dosimetry standard in China.The difference in D_(gN)^(DBT) was mainly due to a decrease in the depth of the main energy deposition area caused by the glandular distribution along the depth direction.The results obtained in this study may be used to improve breast dosimetry in China and provide more detailed information on risk assessment during DBT.

关键词： Digital breast tomosynthesis Normalized glandular dose coefficients Detailed breast model Monte Carlo simulation

Compressive and Sealing Characteristics of PTFE under Cyclic Loading-unloading

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Journal of Wuhan University of Technology(Materials Science) 2015年第1期30卷 181-184页

作者：张宁 LI Qiang hu kang 李青 School of Energy and Power Engineering Huazhong University of Science and Technology The State Key Laboratory of Technologies in Space Cryogenic Propellants Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Compressive and sealing characteristics of PTFE under cyclic loading-unloading at room temperature are studied in order to evaluate the cyclic sealing performance of control valve comprehensively. The unloading characteristics are different from the loading ones, therefore there is hysteresis between the unloading and loading curves. Compressive hysteresis is the main factor that causes sealing hysteresis. The leakage rate of PTFE complies with the power law before it enters the relatively stable region. Lastly, the effect of working pressure on the compressive and sealing characteristics is discussed. The experimental results show that the working pressure has little effect on compressive deformation but has a great influence on leakage rate.

关键词： PTFE compression sealing cyclic loading-unloading working pressure

“追剧”以“追爱”:青年女性的准社会型情感互动与关系建构

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太原理工大学学报（社会科学版） 2024年第3期42卷 126-134页

作者：胡康北京外国语大学国际新闻与传播学院北京100087 墨尔本大学文化与传播学院墨尔本3010

追看爱情剧是当代青年女性屡见不鲜的媒介行为之一。文章运用深度访谈法,研究青年女性在追看爱情剧过程中所表露出的准社会型情感互动与关系建构现象。研究发现,处于不同关系状态(单身或有伴侣)的青年女性在追看爱情剧时会与媒介人物之... 详细信息

追看爱情剧是当代青年女性屡见不鲜的媒介行为之一。文章运用深度访谈法,研究青年女性在追看爱情剧过程中所表露出的准社会型情感互动与关系建构现象。研究发现,处于不同关系状态(单身或有伴侣)的青年女性在追看爱情剧时会与媒介人物之间形成准社会型情感互动与亲密关系,以此满足自身对情感的期待、幻想或补偿,但是女性在获取情感的过程中并非一帆风顺。她们或将面对“关系维系”所带来的“失意”感,或将失落于因媒介人物的“全面撒播”而带来的“失恋”感。此外,追看爱情剧所表现出的准社会行为也间接反映了当代青年女性面临的社会问题。

关键词：青年女性准社会情感互动关系建构追剧媒介人物

Seat tightness of pneumatic cryogenic control valve

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中国科学：技术科学英文版 2013年第8期56卷 2066-2069页

作者： ZHANG Ning LI Qiang LI Qing hu ZhongJun hu kang School of Energy and Power Engineering Huazhong University of Science and Technology State Key Laboratory of Technologies in Space Cryogenic Propellants Technical Institute of Physics and ChemistryChinese Academy of Sciences Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of Sciences

Pneumatic cryogenic control valves(PCCV)are designed to meet the special requirements for the large cryogenic helium refrigeration system.Polychlorotrifluoroethylene(PCTFE)is adopted as the flat seal material of the valve seat.The leakage rates and compressive strain of the PCTFE gasket with different sealing stress are tested at both room temperature(293 K)and liquid nitrogen temperature(77 K).After 300 open/close cycles,the experimental results show that the sealing properties of the PCTFE gasket are improved.The leakage rates are about 10-8(293 K)and 10-4(77 K)Pam3 s-1 respectively.Finally,the effects of working pressure on sealing characteristics are discussed.The working pressure has little effect on compressive strain but it has a great influence on leakage rate.The leakage rate is linear with the working pressure of inlet at room temperature,but at liquid nitrogen temperature the leakage rate is linear with the square of the working pressure.

关键词：密封性能低温阀座气动调节阀 PCTFE 工作压力液氮温度

Ventilation Optimization for Reduction of Indoor Air Temperature of Main Transformer Room in Urban Indoor Substation by the Variational Method

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Journal of Thermal Science 2019年第5期28卷 1089-1101页

作者： LIU Yun YE Wenjie LI Yonghua CHEN Tiantian hu kang School of Energy Power and Mechanical Engineering North China Electric Power University Baoding 071003 China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing 100084 China

Urban indoor substations are widely used for electrical power distribution in urban networks. However, they have the problems of heat dissipation and ventilation in main transformer room, which not only influence the thermal behavior of main transformer, but also decrease the lifetime, reliability, and precision of other electronic equipment. In this contribution, we developed a new ventilation optimization method based on the variational method to solve the aforementioned problems. First, we applied the minimum average temperature of indoor air as the optimization objective combined with some constrains to establish a Lagrange function, and employed the variational method to deduce some optimized governing equations that the optimum indoor patterns should meet the minimum indoor air average temperature. Finally, a typical main transformer room model was taken as an example to demonstrate the applications of the newly developed ventilation optimization method. It was concluded that the inflowing fresh air needed to sweep more area of heating walls to take away more heat, and reduce the average temperature of indoor air. Furthermore, based on the optimized air velocity distribution, we redesigned the ventilation arrangements and reduced the indoor average temperature prominently(from 337.44 K to 314.82 K), which can provide the guidance to design the ventilation of main transformer room to improve the reliability of electronic equipment in main transformer room.

关键词： urban indoor substation main transformer room ventilation optimization variational principle average temperature of indoor air

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航空大型复杂钛框预锻成形初始毛坯优化

塑性工程学报 2024年第1期31卷 99-107页

作者：魏科陈飞黄龙胡康宏南昌航空大学航空制造工程学院江西南昌330063 首尔国立大学材料科学与工程系&RIAM 韩国首尔08826

以某TA15钛合金框为例,采用数值模拟、响应面分析及物理模拟实验相结合的方法对预锻成形的初始毛坯形状尺寸进行了优化。构建了初始毛坯的参数化几何模型;建立了预锻成形有限元模型和响应面实验方案;以型腔各区域同时靠模为目标,根据不... 详细信息

以某TA15钛合金框为例,采用数值模拟、响应面分析及物理模拟实验相结合的方法对预锻成形的初始毛坯形状尺寸进行了优化。构建了初始毛坯的参数化几何模型;建立了预锻成形有限元模型和响应面实验方案;以型腔各区域同时靠模为目标,根据不同初始毛坯的模拟结果,建立毛坯几何尺寸与模具型腔充填之间的定量关联关系,并通过极值求解计算出最优毛坯几何尺寸;最后采用有限元模拟和物理模拟实验验证了初始毛坯优化的可靠性和准确性。结果表明,该方法能有效克服大型复杂钛框预锻成形中常见的填充不满、成形载荷过大等问题,实现预锻件在型腔不同区域同时靠模。

关键词：航空大型钛框预锻成形填充不满初始毛坯优化设计

Nonlinear optical polyimide with high thermal stability prepared by simultaneous poling and polymerization

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Chinese Science Bulletin 2001年第10期46卷 827-831页

作者： hu kang Wei Wu Peiji Wu Cheng Ye Chinese Acad Sci Ctr Mol Sci Organ Solids Lab Beijing 100080 Peoples R China

The high Tg polyimide embedded with a novel imidazol-typed chromophore 2-[5-(4-nitrostilbenyl)thienyl]-4,S-di(4-aniinophenyl)imidazole (NSTDAPI) was prepared using the 'simultaneous poling and polymerization' technique. The glass transition temperature (Fg) is 304℃ and the initial decomposition temperature (Td) is 330℃. The in-situ second harmonic generation (in-situ SHG) measurement was performed to study its poling behavior and the stability of the poling-induced orientation. The nonlinear optical (NLO) coefficient d33 of poled polyimide film is 32.2 pm/V at 1064 nm fundamental wavelength. The SHG signal of the poled polymer film was quite stable below 200℃, and then began to decay rapidly above 220℃. The half-decay temperature of dipole orientation for the film is 250℃.

关键词： poled polymer functionalized polyimide simultaneous poling and polymerization second harmonic generation thermal stability of poling-induced orientation.

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丙烷脱氢装置低温回收区设备和管道布置设计

广州化工 2024年第3期52卷 131-134页

作者：胡康宁中石化宁波工程有限公司浙江宁波315103

丙烷脱氢项目作为国内近年来快速发展的项目,但目前国内对丙烷脱氢项目的工程经验和项目研究还较缺少。依据国内某丙烷脱氢装置低温回收区设备和管道布置设计经验,阐述低温回收区设备管道布置工艺流程和注意事项,通过图表分析、方案对... 详细信息

丙烷脱氢项目作为国内近年来快速发展的项目,但目前国内对丙烷脱氢项目的工程经验和项目研究还较缺少。依据国内某丙烷脱氢装置低温回收区设备和管道布置设计经验,阐述低温回收区设备管道布置工艺流程和注意事项,通过图表分析、方案对比一一研究总结低温回收区设备和管道布置设计要点。低温回收区存在大量的低温回收区关键核心设备是冷箱,做好冷箱的设备和管道布置设计,是整个低温回收区设备和管道布置设计成功的基石。

关键词：低温回收设备布置管道布置冷箱