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Formation and migration of space charge packet in low density polyethylene

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Science china(Technological Sciences) 2005年第3期48卷 354-360页

作者： ZHENG Feihu 1., ZHANG Yewen 1., {1. Bin 1., Zhu Jianwei 1.& wu Changshun 2 1. Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, china 2. china National Center for Quality Supervision and Test of Electric Ware and Cable, Shanghai 200093, china 1. Pohl Institute of Solid State Physics Tongji University 200092 Shanghai China 2. china National Center for Quality Supervision and Test of Electric Ware and Cable 200093 Shanghai China

Pressure wave propagation (PWP) method was utilized to observe the space charges packet-like behavior in sheet samples of low-density polyethylene (LDPE) under the relative low electric field. The experimental results show that space charge packets are always generated at the anode and move across the sample to the cathode regardless of the polarity of DC voltage. This paper discusses the migration of space charge packets at 30–40°C, the possible charge resource of space charge packets carriers and trap level of the space charge.

关键词： solid dielectric,low-density polyethylene,space charge packet,trap.

Flooding 1.90s along the Yangtze River, has it concern of global warming?

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Journal of Geographical Sciences 2001年第1期11卷 43-52页

作者： gong Dao-yi1. Z{1. Jin-hong2, WANG Shao-wu2 (1. Key Laboratory of Environmental Change and Natural Disaster, Institute of Resources Science, beijing Normal University, beijing 1.0875, china 2. Department of Geophysics, Peking University, beijing 1.0871. beijing Normal University Key Laboratory of Environmental Change and Natural Disaster Institute of Resources Science Beijing China (GRID:grid.20513.35) (ISNI:***) Peking University Department of Geophysics Beijing China (GRID:grid.11135.37) (ISNI:***)

There were a series of severe floods along the middle to lower reaches of the Yangtze River (Changjiang River) in china during the 1.90s. The extensive summer (June, July and August) precipitation is mostly responsible for the flooding. The summer rainfall in the 1.80s and the 1.90s is much higher than that in the previous 3 decades. The means for 1.90–1.99 is +87.62 mm above normal, marked the 1.90s the wettest decade since the 1.50s. Six stations with a time span of 1.80–1.99 are selected to establish century-long rainfall series. This series also shows that the 1.90s is the wettest decade during the last 1.0 years. In the wettest 1. years, four occurred in the 1.90s (1.91. 1.96, 1.98 and 1.99). Both global and china’s temperature show there is a relative lower air temperature during the 1.60–1.70s, and a rapid warming in the 1.80–1.90s. Comparisons of rainfall between 1.60–1.79 and 1.80–1.99 show there are dramatic changes. In the cold period 1.60–1.79, the summer rainfall along the Yangtze River is 3.8 % to 4.7 % below the normal, during the warm period 1.80–1.99, over 8.4 % to 1..2 % of summer rainfall occurs. Over the whole eastern china, the summer rainfall shows opposite spatial patterns from the 1.60–1.70s to 1.80–1.90s. The consistent trend toward more rainfall with global warming is also presented by the greenhouse scenario modeling. A millennial Drought/flood Index for the middle to lower reaches of the Yangtze River showed that although the surplus summer rainfall in the 1.90s is the severest during the past 1.0 years, it is not outstanding in the context of past millennium. Power spectra of the Drought/flood Index show significant interdecadal periods at 33.3 and 1..8 years. Thus, both the natural interdecadal variations and the global warming may play important roles in the frequent floods witnessed during the last two decades.

关键词： summer rainfall Yangtze River global warming interdecadal variation

Distribution Features of the Residual Stress For T-Joints by Laser Welding

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稀有金属材料与工程 2011年第S4期40卷 130-133页

作者： He Enguang1.gong S{1.ili1.wu Bing1.2,Chen Li1.1.cience and Technology on Power Beam Processes Laboratory,AVIC beijing Aeronautical Manufacturing Technology Research Institute,beijing 1.0024,china 2 School of Material Science and Engineering,Xi`an Jiaotong University,Xi`an 71.049,china AVIC beijing Aeronaut Mfg Technol Res Inst Sci & Technol Power Beam Proc Lab Beijing 100024 Peoples R China Xi An Jiao Tong Univ Sch Mat Sci & Engn Xian 710049 Peoples R China

The residual stress of T-joints for SUS304 stainless steel by YAG laser welding was measured by the method of hole-drilling,and the effects of heat treatment and hardness distribution of weld joints on the distribution of residual stress for T-joints were *** results showed that the maximum of longitudinal residual tensile stress for T-joints was about *** maximum of residual stress was not more than 40MPa after heat treatment,the peak of residual stress reduced *** gradient of residual stress distribution was also reduced *** hardening phenomenon occurred for T-joints,and the hardness of weld and heat affected zone was both higher than the hardness of base metal,the peak of hardness occurred in the fusion *** effect of strain hardening phenomenon of weld and heat affected zone on the residual stress distribution of T-joints for SUS304 stainless steel was obvious,which made longitudinal residual tensile stress become higher.

关键词： stainless steel laser welding T-joints heat treatment

The effects of centrally administered fluorocitrate via inhibiting glial cells on working memory in rats

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Science china(Life Sciences) 2009年第8期52卷 701-709页

作者： WANG Lei1.2,LI Chao-Cui1.WANG gong-{1.1.& CAI Jing-Xia1.1.Section of Brain and Behavior,Kunming Institute of Zoology,the Chinese Academy of Sciences,Kunming 650223,china 2 Graduate School of the Chinese Academy of Sciences,beijing 1.0049,china 1. Section of Brain and Behavior Kunming Institute of Zoology the Chinese Academy of Sciences Kunming 650223 China 2. Graduate School of the Chinese Academy of Sciences Beijing 100049 China

Although prefrontal and hippocampal neurons are critical for spatial working memory,the function of glial cells in spatial working memory remains *** this study we investigated the function of glial cells in rats' working *** glial cells of rat brain were inhibited by intracerebroventricular(icv) injection of fluorocitrate(FC).The effects of FC on the glial cells were examined by using electroencephalogram(EEG) recordings and delayed spatial alternation *** icv injection of 1. μL of 0.5 nmol/L or 5 nmol/L FC,the EEG power spectrum recorded from the hippocampus increased,but the power spectrum for the prefrontal cortex did not change,and working memory was *** an icv injection of 1. μL of 20 nmol/L FC,the EEG power spectra in both the prefrontal cortex and the hippocampus increased,and working memory *** icv injection of 1. μL of 50 nmol/L FC,the EEG power spectra in both the prefrontal cortex and in the hippocampus decreased,and working memory was *** results suggest that spatial working memory is affected by centrally administered FC,but only if there are changes in the EEG power spectrum in the prefrontal ***,the prefrontal glial cells relate to the working memory.

关键词： glial cell fluorocitrate prefrontal cortex hippocampus electroencephalogram power spectrum spatial working memory

Residual Stress Measurement in Electron Beam Welded Joints of 50mm Thick Titanium Alloy

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稀有金属材料与工程 2011年第S4期40卷 44-48页

作者： wu Bing1.2,Zhang Jianxun1.Liu C{1.an1.gong S{1.ili2 1.tate Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 71.049,china2Science and Technology on Power Beam Processes Laboratory,beijing Aeronautical Manufacturing Technology Research Institute,beijing 1.0024,china beijing Aeronaut Mfg Technol Res Inst Sci & Technol Power Beam Proc Lab Beijing 100024 Peoples R China Xi An Jiao Tong Univ State Key Lab Mech Behav Mat Xian 710049 Peoples R China

For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in residual stress distribution characteristics of electron beam welding joints,which thickness is 50 mm,were measured using blind-hole method with local layer-by-layer *** of post-welding heat treatment on the residual stress distribution also *** results show that blind-hole method with local layer-by-layer removal is suitable to measure residual stresses in thick plate,and good to reflect the welded residual stress distribution of large *** stress of the test samples in the weld and heat affected zone has high stress level,and internal stress dramatic changes with thickness in this *** heat treatment,the samples' stress distributions were significantly *** samples' transverse and longitudinal residual stress are basically the *** is obvious.

关键词： electron beam welding thick plate residual stress measurement blind-hole method local layer-by-layer removal re-sidual stress distribution

Effect of trace Zn,P and Mg additions on microstructure and mechanical properties of Nb-Si-Ti alloys

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Progress in Natural Science:Materials International 2011年第2期21卷 139-145页

作者： Mei-ling wu,S{1.-suo LI,Li-wu JIANG,Sheng-kai gong,Ya-fang HAN School of Materials Science and Engineering,Beihang University,beijing 1.01.1.china School of Materials Science and Engineering Beihang University Beijing 100191 China

The effects of Zn,P and Mg additions on the microstructure and mechanical properties of Nb-22Ti-3Si alloys were studied. The phases of Nbss and Nb3Si presented in Nb-22Ti-3Si(AC1.,Nb-22Ti-3Si-0.2Zn(AC2) and Nb-22Ti-3Si-0.2Mg alloys(AC3). The Nb-22Ti-3Si-0.2P(AC4) alloy consisted of Nbss,Nb3Si network and eutectic cell of Nbss/α-*** the addition of Zn,the Nb3Si network was broken and the volume fraction of Nbss increased from 92%to 96%.The values of fracture toughness of the alloy AC2 at ambient temperature increased from 22,58 MPa·m1.2to 26.41.MPa·m1.*** values of compressive strength for the Zn-added alloy at ambient temperature and 1.250℃increased from 1.525.1. MPa to 1.652.44 MPa,and from 268.52 MPa to 284.1. MPa,*** with the alloy AC1.the addition of P promoted the formation ofα-Nb5Si phase but the values of fracture toughness and compressive strength of alloy at room temperature and 1.250℃*** contrast,the addition of Mg improved the compressive strength at ambient temperature and 1.50℃from 1.525.1. MPa to 1.61..08 MPa and from 268.52 MPa to 348.28 MPa,*** relationship between the microstructure and the mechanical properties was discussed.

关键词： Nb-Si-Ti alloy Zn addition P Mg microstructure mechanical property

Greenhouse gas emissions from a constructed wetland for municipal sewage treatment

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Journal of Environmental Sciences 2002年第1期14卷 27-33页

作者： TAI Pei dong 1. LI Pei jun 1., SUN Tie heng 1. HE Yao wu 1. ZHOU Qi xing 1.{1. Zong qiang 1. Motoyuki Mizuochi 2, Yuhei Inamori 2 (1.Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 1.001., china. 2 National Insti Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110015 Chin

The fluxes of greenhouse gases (methane and nitrous oxide) emission from a constructed wetland in the Eastern china as municipal sewage treatment were measured from June 1.99 to August 2000 by the closed chamber method. The constructed wetland for municipal sewage treatment is a significant source of methane, up to 976 6×1. 6 g CH 4/a, which was emitted from the constructed wetland with the area of 495000 m 2 and wastewater loading rate of 1.000 m 3/d. Its daily mean methane flux reached 5 22 g CH 4/(m 2·d), 250 times as much as that in natural wetland in the same latitude region. 227 8 mg CH 4 was produced from the treatment of 1.liter wastewater, up to 700—1.00 times as much as that in the secondary treatment. The emission of nitrous oxide from the constructed wetland is not higher than that from secondary treatment of wastewater, only 0 07 mgN 2O/L.

关键词： greenhouse gas emission constructed wetland municipal sewage methane nitrous oxide

The　Analysis　and　Numerical　Simulation　of　Dynamical　Functions　of　the　Transpiration　Cooling　Control　System　with　Surface　Ablation

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Journal of Systems Engineering and Electronics 1994年第1期5卷 44-52页

作者： Xu Yanhou wu Guangyu(Department of Modern Mechanics,University of Science & Technology of{1., Hefei, 230026)gong Guanghui(Graduate School of USTC, beijing, 1.0039)Yang Xueshi(P.O.Box 1.2-206, beijing, 1.0854) Department of Modern Mechanics University of Science & Technology of China Hefei 230026 Graduate School of USTC Beijing 100039 P.O. Box 1.2-206 Beijing 100854

This problem is a nonlinear control system with variable-domain distributed parameter. In this paper, the numerical simulation of the dynamic functions has been carried out by transforming this problem to a fixed-domain initial-boundary value problem, and the numerical results are obtained: (1. Thedistribution of temperature rises, the ablation amount and velocity of the thermal shield vary with the time; (2) The maximum ablating velocity, the time of the ablation beginning and ending related to thetranspiration quantity. This method succeeds in overcoming the difficulty brought up by variable *** the other hand, the critical transpiration quantity for the surface to start ablating, the maximum ablating velocity and time of the ablation ending are obtained theoretically.

关键词： Ablation,Transpiration cooling Variable domain Distributed parameter control NumericalSimulation

^(60)Coγ线体外照射对大鼠肺巨噬细胞膜的损伤

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辐射研究与辐射工艺学报 1989年第2期7卷 15-20页

作者：胡连平龚诒芬吴德昌军事医学科学院放射医学研究所

本文报告^(60)Co-γ线体外照射大鼠肺巨噬细胞(Alveolar Macrophage简称AM)对胞浆膜和溶酶体膜的损伤效应。大鼠AM在体外经^(60)Coγ线照射0-500 Gy后,培养24h,以上清液中乳酸脱氢酶(LDH)和β-葡萄糖醛苷酶(β-glu)活性占全部酶活性的%... 详细信息

本文报告^(60)Co-γ线体外照射大鼠肺巨噬细胞(Alveolar Macrophage简称AM)对胞浆膜和溶酶体膜的损伤效应。大鼠AM在体外经^(60)Coγ线照射0-500 Gy后,培养24h,以上清液中乳酸脱氢酶(LDH)和β-葡萄糖醛苷酶(β-glu)活性占全部酶活性的%变化,定量表达膜损伤的程度。实验结果表明,AM接受0、1.0、200、300、400和500Gy后24h内上清液中LDH和β-glu活性占全部酶活性的%随剂量增大而增高,上清液中LDH活性%分别为35.7、41.0、45.8、48.1.49.8和51.3%;上清液中β-glu活性%分别为7.0、9.7、1..5、1..7、1..5和1..3%,说明辐射引起AM胞浆膜和溶酶体膜损伤与剂量的依赖关系。用扫描电镜和透射电镜均观察到AM胞浆膜和溶酶体膜受损的形态学证据。本文还就反映AM膜受损的指标,辐射致膜损伤的时相性以及膜损伤的意义进行了扼要的讨论。

关键词：肺巨噬细胞膜鼠钴 γ线照射