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SiC-Si-ZrSiO_4 Multiphase Oxidation Protective Coating for Carbon/Carbon Composites

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Journal of Materials Science & Technology 2008年第6期24卷 941-944页

作者： Yulei zhang hejun LI Qiangang FU Kezhi LI Dangshe HOU C/C Composites Technology Research Center Laboratory of Superhigh Temperature Composites Northwestern Polytechnical University Xi/an 710072 China

In order to improve the anti-oxidation property of carbon/carbon （C/C） composites, a novel SiC-Si-ZrSiO4 multiphase oxidation protective coating was produced on the surface of C/SiC coated carbon/carbon compo ites by a pack cementation technique. The phase composition and microstructure of the as-prepared coatings were characterized by XRD （X-ray diffraction）, SEM （scanning electron microscopy） and EDS （energy dispersive spectroscopy）. Oxidation behavior of the multiphase coated C/C composites was also investigated. It showed that the as-prepared coating characterized by excellent oxidation resistance and thermal shock re- sistance could effectively protect C/C composites from oxidation at 1773 K for 57 h in air and endure the thermal cycle between 1773 K and room temperature for 12 times, whereas the corresponding weight loss is only 1.47%. The excellent oxidation protective ability of the SiC-Si-ZrSiO4 coating could be attributed to the C/SiC gradient inner layer and the multiphase microstructure of the coating.

关键词： Carbon/carbon composites Oxidation Coating

The Effect of Different Freeze-Thaw Cycles on Mortar Gas Permeability and Pore Structure

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Fluid Dynamics & Materials Processing 2023年第6期19卷 1623-1636页

作者： Wei Chen Ao Xu hejun zhang Mingquan Sheng Yue Liang Frederic Skoczylas School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhanChina CNRS Centrale LilleUMR9013-LaMcube-Laboratoire de Mécanique Multiphysique et MultiéchelleUniversitéde LilleLilleFrance

Two different freeze-thaw cycles(FTC)are considered in this study to assess the related impact on gas permeability and micro-pore structure of a *** are the water-freezing/water-thawing(WF-WT)and the air-freezing/air-thawing(AF-AT)*** problem is addressed experimentally through an advanced nuclear magnetic resonance(NMR)technique able to provide meaningful information on the relationships among gas permeability,pore structure,mechanical properties,and the number of *** is shown that the mortar gas permeability increases with the number of FTCs,the increase factor being 20 and 12.83 after 40 cycles for the WF-WT and AF-AT,*** results also confirm that gas permeability hysteresis phenomena occur during the confining pressure loading and unloading process.

关键词： Mortar freeze-thaw cycles gas permeability pore structure NMR mechanical properties

Control of Bursaphelenchus xylophilus in the State-owned Sishibacao Forest Farm of Yunyang County,China

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Agricultural Biotechnology 2023年第2期12卷 127-132页

作者： Chunhua TANG hejun zhang Yunyang State-owned Sishibacao Forest Farm Chongqing 400000China Chongqing Bainian Forestry Technology Co. Ltd.Chongqing 400000China

In view of the fact that pine wood nematode disease is the most dominant disease in Pinus massoniana forests,which has the characteristics of strong infectivity,fast transmission speed,and great difficulty in prevention and control,a brief description was made to the occurrence status of pine wood nematode disease and difficulties faced with its control in the State-owned Sishibacao Forest Farm of Yunyang County,China,followed by the analysis on the prevention and control measures from aspects of strict control,epidemic situation monitoring,joint prevention and control,and clearance of infected trees,as well as the existing problems of pine wood nematode ***,reasonable suggestions including strengthening the construction of talent team were put forward,aiming to provide a beneficial reference for the scientific,efficient,and reasonable control of pine wood nematode disease in Pinus massoniana *** of Yunyang State-owned Sishibacao Forest Farm.

关键词： Pine wood nematode disease Occurrence status Control measures

基于DWARF的Bootloader远程交叉调试模型

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计算机工程 2006年第24期32卷 60-62页

作者：张和君张跃清华大学深圳研究生院嵌入式系统与技术实验室深圳518055

研究了嵌入式系统在Bootloader单支撑环境下的远程交叉调试问题,设计并实现了Bootloader远程交叉调试模型,并达到源码级别的调试。主机端采用DWARF调试规范,负责分析目标文件的调试信息,向目标机上的Bootloader发送机器级的调试命令;Boo... 详细信息

研究了嵌入式系统在Bootloader单支撑环境下的远程交叉调试问题,设计并实现了Bootloader远程交叉调试模型,并达到源码级别的调试。主机端采用DWARF调试规范,负责分析目标文件的调试信息,向目标机上的Bootloader发送机器级的调试命令;Booloader接收并处理调试命令。该模型为嵌入式系统的应用程序开发提供了良好的调试手段。

关键词：引导装载程序远程交叉调试 DWARF调试规范嵌入式系统

Oxidation Protective C/SiC/Si-SiC Multilayer Coating for Carbon/Carbon Composites Applying at 1873 K

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Journal of Materials Science & Technology 2010年第12期26卷 1139-1142页

作者： Yulei zhang,hejun Li,Xinfa Qiang and Kezhi Li C/C Composites Research Center,State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi an 710072,China [a] C/C Composites Research Center State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi(an 710072 China

A C/SiC/Si-SiC multilayer coating for protecting carbon/carbon （C/C） composites against oxidation was prepared by slurry and pack cementation. X-ray diffraction （XRD） and energy dispersive spectroscopy （EDS） analysis showed that the inner coating obtained from the slurry and pack cementation was a C/SiC gradient layer acting as bonding layer, and the exterior coating formed in the second pack cementation was a Si-SiC double phase coating. Oxidation tests at 1873 K in air showed that the coating exhibited excellent oxidation protective ability and thermal shock resistance. The coating could effectively protect C/C composites from oxidation at 1873 K in air for 170 h and undergo the thermal cycling between 1873 K and room temperature for 8 cycles. The weight loss of the coated C/C composites is due to the formation of cracks and holes in the coating and the volatilization of SiO2 glass at high temperature.

关键词： Carbon/carbon composites Oxidation Coating

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激光跟踪仪多参数误差模型与标定

仪器仪表学报 2020年第9期41卷 20-30页

作者：张和君马俊杰张军深圳市中图仪器股份有限公司深圳518071 贵州航天计量测试技术研究所贵阳550009

针对激光跟踪仪在加工、装调、运输、使用过程中产生的误差与状态变动等问题,从系统的机械和光路理想结构出发,分析机械轴系安装误差、光学准直误差、转镜安装误差、编码器偏心等系列误差的形成机理,建立包含主要19项光机误差的运动学... 详细信息

针对激光跟踪仪在加工、装调、运输、使用过程中产生的误差与状态变动等问题,从系统的机械和光路理想结构出发,分析机械轴系安装误差、光学准直误差、转镜安装误差、编码器偏心等系列误差的形成机理,建立包含主要19项光机误差的运动学模型。研究系统综合误差模型的标定方法,提出一套现场标定方案和数值优化求解方法,实现对系统综合误差的一次性精确标定及补偿,提高模型参数的标定精度以及工业现场的标定效率。试验及应用表明,采用该误差模型优化方法,测量标准圆轨迹发生器的半径标准差可达8μm,圆平面的平面度标准差0.036μm,基于ASME B89.4.19双面测试的空间坐标测量误差能够减少到10×10-6以内。

关键词：激光跟踪仪跟踪反射镜误差模型圆轨迹发生器数值优化

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基于多层次细节模型的动态切削力仿真

中国机械工程 2007年第12期18卷 1430-1433,1500页

作者：何伟宾鸿赞张何军华中科技大学武汉430074

为了缓解雕刻曲面数控加工过程物理仿真的仿真速度与仿真精度的矛盾,减少仿真的计算量和缩短仿真时间,介绍了雕刻曲面数控加工过程仿真的多层次细节模型和基于该模型的动态切削力的仿真方法。基于雕刻曲面的多层次细节模型的动态切削力... 详细信息

为了缓解雕刻曲面数控加工过程物理仿真的仿真速度与仿真精度的矛盾,减少仿真的计算量和缩短仿真时间,介绍了雕刻曲面数控加工过程仿真的多层次细节模型和基于该模型的动态切削力的仿真方法。基于雕刻曲面的多层次细节模型的动态切削力的仿真,可以根据工件毛坯不同的几何形状、仿真要求、工艺参数等在曲面上不同的区域和不同的细节层次上进行,为校验和优化数控加工程序提供依据。

关键词：雕刻曲面多层次细节加工过程仿真动态切削力

Experimental Study on Afforestation in the Engineering Treatment Areas in the Hydro-fluctuation Zone of the Three Gorges Reservoir:A Case Study on the Engineering Treatment Area in the Wuxi Section of the Daning River

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Agricultural Biotechnology 2022年第4期11卷 161-163页

作者： Zhengchun WANG Xiang FU Haiyan JIANG Qiang XIE hejun zhang Chongqing Academy of Forestry Chongqing 400036China Chongqing University Chongqing 400045China Chongqing Jiaotong University Chongqing 400074China Chongqing Bainian Forestry Technology Co. Ltd.Chongqing 40000China

Through the Betula nigra afforestation test in the engineering treatment area of the Wuxi Section of the Daning River in Chongqing,the feasibility of arbor vegetation restoration in the comprehensive management of the engineering treatment areas of the Three Gorges Reservoir was *** results showed that:(1)before the flooding in the project area,the survival rate of *** seedlings was high,over 95%,and(2)in 2021,after a water storage period,affected by factors such as seedling specifications,flood and flooding time,the survival rate of the seedlings planted in 2020 was low,and the one-year-old seedlings were greatly competed by weeds and grew ***-year-old *** seedlings were replanted in 2021,and the survival rate of the *** seedlings was 100%in ***-year-old *** seedlings have strong adaptability and have little impact on the stability of the engineering treatment area,and can be used as afforestation tree species in engineering treatment areas of hydro-fluctuation zones.

关键词： Hydro-fluctuation zone Engineering treatment area Vegetation restoration Water birch

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整体式浇筑箱梁的预制施工工艺及质量控制

铁道建筑 2006年第12期46卷 15-16页

作者：张合君中铁九局集团第一工程有限公司辽宁锦州121000

以沈山高速公路出口连接线工程中箱形梁施工实践为例,介绍了整体式连续浇筑箱梁的施工工艺及质量控制,对混凝土配合比设计、内模板设计安装、混凝土浇筑等技术措施及质量控制进行了阐述,为同类构件的预制施工提供了一些参考借鉴。

关键词：预制箱梁整体浇筑施工工艺质量控制