127 resultados para 136-843A

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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用1.755GeV136Xe离子在真空室温环境下辐照叠层聚酰亚胺薄膜,通过红外和紫外光谱测量研究了高电子能损离子辐照引起的化学降解及炔基产生效应。红外测量结果表明,典型官能团随辐照注量的增加指数降解,且径迹芯中所有官能团均遭到破坏,对应8.8(最小能损,第一层)和11.5keV/nm(最大能损,第五层)电子能损,136Xe辐照聚酰亚胺的平均降解半径分别为3.6和4.1nm。而相应能损条件下炔基的生成截面分别为5.6和5.9nm大于官能团的降解截面。紫外结果表明辐照引起的吸光度的改变随辐照注量线性增加,发色团的产生效率随电子能损的增大而增加。

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研究了 1 5.1 4MeV/u136  Xe离子在不同批次的 3 2k× 8bits静态存储器中所引起的单粒子效应 .获得了单粒子翻转和单粒子闭锁截面与入射角度的依赖关系 .将单粒子效应截面与灵敏区中沉积的能量相联系 ,而不是线性能量转移(LET)值 .估计了灵敏体积的深度和死层的厚度 .

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利用 450MeV的82 Se束流轰击139La靶 ,通过核子转移反应产生了136 Ba ,用在束γ谱学方法测量了其激发态的γ衰变 ,观测到了它的 1 0 +态同质异能态并得到该同质异能态的寿命为 94ns.

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A numerical model for shallow-water equations has been built and tested on the Yin-Yang overset spherical grid. A high-order multimoment finite-volume method is used for the spatial discretization in which two kinds of so-called moments of the physical field [i.e., the volume integrated average ( VIA) and the point value (PV)] are treated as the model variables and updated separately in time. In the present model, the PV is computed by the semi-implicit semi-Lagrangian formulation, whereas the VIA is predicted in time via a flux-based finite-volume method and is numerically conserved on each component grid. The concept of including an extra moment (i.e., the volume-integrated value) to enforce the numerical conservativeness provides a general methodology and applies to the existing semi-implicit semi-Lagrangian formulations. Based on both VIA and PV, the high-order interpolation reconstruction can only be done over a single grid cell, which then minimizes the overlapping zone between the Yin and Yang components and effectively reduces the numerical errors introduced in the interpolation required to communicate the data between the two components. The present model completely gets around the singularity and grid convergence in the polar regions of the conventional longitude-latitude grid. Being an issue demanding further investigation, the high-order interpolation across the overlapping region of the Yin-Yang grid in the current model does not rigorously guarantee the numerical conservativeness. Nevertheless, these numerical tests show that the global conservation error in the present model is negligibly small. The model has competitive accuracy and efficiency.

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使用光学多道分析仪(OMA)详细收集了氢氧气体爆炸产物激励下,两种不同粒度的铝粉在不同氧含量条件下快速反应的低分辨和高分辨光谱。实验结果表明在240~850nm的光谱范围内的辐射以连续辐射为主,并有较弱的铝原子线和AlO的B2Σ+→X2Σ+带光谱。

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本文用简化模型分析托卡马克装置,建议用等离子体往径向速度振荡和角向磁场振荡的相互作用产生一个定常环向电动势以驱动稳态电流。这可由按一定相位差调制两个外加参量来达到。按反应堆参数估计,这种调制频率可以是工业频率。

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<正> 中国力学学会、中国航空学会、中国机械工程学会联合召开的第2届全国疲劳学术会议,于1984年10月8—11日在四川峨眉西南交通大学举行,参加会议代表150多人,宣读和交流126篇论文,并进行了专题讨论,论文内容大致包括以下几个方面。

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The interaction of water waves and seabed is studied by using Yamamoto's model, which takes into account the deformation of soil skeletal frame, compressibility of pore fluid flow as well as the Coulumb friction. When analyzing the propagation of three kinds of stress waves in seabed, a simplified dispersion relation and a specific damping formula are derived. The problem of seabed stability is further treated analytically based on the Mohr-Coulomb theory. The theory is finally applied to the coastal problems in the Lian-Yun Harbour and compared with observations and measurements in soil-wave tank with satisfactory results.

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研讨有限体积(FV)方法重构近似高精度的作用问题.FV方法中积分近似采用中点规则为二阶精度时,重构近似高精度(精度高于二阶)的意义和作用是一个有争议的问题.利用数值摄动技术"。0构造了标量输运方程的积分近似为二阶精度、重构近似为任意阶精度的迎风型和中心型摄动有限体积(PFV)格式.迎风 PFV格式无条件满足对流有界准则(CBC),中心型PFV格式为正型格式,两者均不会产生数值振荡解.利用 PFV格式求解模型方程的数值结果表明:与一阶迎风和二阶中心格式相比,PFV格式精度高、对解的问断分辨率高、稳定性好、雷诺数的适用范围大,数值地"证实"重构近似高精度和PFV格式的实际意义和好处.

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液化天然气运输船液货舱热维护系统是一个结构复杂的、具有第三类边界条件的、多层平壁的稳态导热与自然对流及辐射换热相互耦合的三维复杂传热系统。针对这一复杂系统,考虑了船体主要构件、骨材、空腔空气对流、表面间的辐射对换热的影响,建立了数学模型,并给出了基于通用软件ANSYS的数值计算方法;还以某艘LNG运输船为例,进行了温度场的有限元分析。结果表明,所给出的对LNG运输船液货舱热维护系统的热分析方法是有效的。

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《高等断裂力学》系统论述断裂力学的基本概念、理论基础、力学原理、分析方法以及断裂力学的实验测定和工程应用。深入阐明了断裂力学各个重要发展阶段的新颖学术思想和原创性工作,同时融会贯通地介绍了国内学者在作者熟悉的若干领域内的创造性贡献。  《高等断裂力学》共14章。第1章介绍断裂力学的历史背景和发展脉络;第2~5章介绍线弹性断裂力学;第6~8章论述弹塑性断裂力学;第9及第10章分别介绍疲劳裂纹扩展和界面裂纹;第11~14章阐述裂纹体弹性动力学和裂纹动态扩展。  《高等断裂力学》适合从事断裂力学研究和应用的科技工作者及工程师使用和参考,也可供力学专业的高年级本科生和研究生阅读参考.

目录

丛书序
序言
第1章 引论
1.1 历史背景
1.2 工程意义
1.3 脆性破坏特征
1.4 断裂力学起源与发展
参考文献

第2章 线弹性断裂力学
2.1 裂纹尖端弹性应力场
2.2 应力强度因子理论
2.3 裂纹扩展能量原理
2.4 裂纹尖端塑性区
2.5 厚度对KC的影响
2.6 裂纹扩展阻力曲线
参考文献

第3章 应力强度因子分析方法
3.1 Williams级数展开与边界配置法
3.2 复变函数方法
3.3 权函数法
3.4 积分变换法
3.5 奇异积分方程
3.6 有限单元法
参考文献

第4章 平面应变断裂韧性
4.1 标准试样
4.2 试样取向与制备
4.3 测试仪器和有效性分析
4.4 KR曲线测试
参考文献

第5章 复合型裂纹的脆断理论
5.1 复合型裂纹变形特征
5.2 应力参数准则
5.3 分支裂纹应力强度因子
5.4 能量释放率准则
5.5 复合型裂纹脆断试验
5.6 理论与实验比较
5.7 塑性变形对金属材料复合型裂纹脆性断裂的影响
参考文献

第6章 弹塑性断裂力学
6.1 J积分原理
6.2 HRR奇性场
6.3 J积分准则
6.4 J控制扩展
6.5 断裂韧性JIC测试
6.6 Dugdale模型
6.7 带状颈缩区模型
6.8 裂纹张开位移准则
参考文献

第7章 裂纹顶端弹塑性高阶场
7.1 高阶场基本方程
7.2 一阶场和二阶场
7.3 高阶场前5项完整结果
7.4 J-Q双参数方法
7.5 J-k断裂准则
7.6 平面应力裂端弹塑性场
参考文献

第8章 理想弹塑性介质扩展裂纹尖端场
8.1 v=0.5时的裂尖渐近场
8.2 v<0.5时的裂尖场
8.3 理想弹塑性介质Ⅲ型扩展裂纹
8.4 扩展裂纹与J积分
参考文献

第9章 疲劳裂纹扩展
9.1 等幅载荷下裂纹扩展
9.2 影响疲劳裂纹扩展的因素
9.3 裂纹闭合效应
94疲劳裂纹扩展门槛值确定
95等幅载荷下疲劳裂纹寿命预测
96变幅载荷下疲劳寿命预测
97缺口根部的疲劳裂纹
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第10章 界面裂纹
101弹性界面力学
102界面裂纹弹性断裂力学
10.3 典型的界面断裂问题
10.4 界面断裂试验
参考文献

第11章 弹性动力学基本概念及方法
11.1 动态惯性效应
11.2 线弹性动力学基本方程
11.3 复变解析函数
11.4 Laplace变换
11.5 Wiener-Hopf分解
11.6 动态断裂的能量概念
参考文献

第12章 静止裂纹的弹性动力学基本解
121突加反平面剪切载荷
12.2 突加裂纹面正压力
12.3 突加平面内剪切应力情况
124有限长裂纹面突加载荷情况
12.5 动态载荷裂纹的起始扩展
参考文献

第13章 均匀材料中动态扩展裂纹
13.1 动态裂纹定常扩展
13,2裂纹面上集中剪切力
133黏结区模型
13.4 Broberg问题
13.5 对称扩展剪切裂纹
136时间无关载荷作用下裂纹扩展
13.7 时间相关载荷作用下裂纹扩展
13.8 II型超剪切波扩展裂纹
13.9 裂纹尖端超弹性区对I、II型裂纹速度的影响
参考文献

第14章 双材料界面动态裂纹扩展
14.1 准静态动态裂纹扩展
14.2 双材料界面裂纹含接触区跨音速扩展
14.3 界面裂纹的超音速扩展
参考文献
索引

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A Nd:glass regenerative amplifier has been set up to generate the pumping pulse with variable pulse width for an optical parametric chirped-pulse amplification (OPCPA) laser system. Each pulse of the pulse train from a cw self-mode-locking femtosecond Ti:sapphire oscillator is stretched to approximate to300 ps at 1062 nm to be split equally and injected into a nonlinear crystal and the Nd:glass regenerative amplifier, as the chirped signal pulse train and the seed pulse train of the pumping laser system, respectively. By adjusting the cavity length of the regenerative amplifier directly, the width of amplified pulse could be varied continuously from approximate to300 ps to approximate to3 ns. The chirped signal pulse for the OPCPA laser system and the seed pulse for the pumping laser system come from the same oscillator, so that the time jitter between the signal pulse and the pumping pulse in optical parametric amplification stages could be <10 ps. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

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In the present study, single-molecule fluorescence microscopy was used to examine the characteristics of plasma membrane targeting and microdomain localization of enhanced yellow fluorescent protein (eYFP)-tagged wild-type Dok5 and its variants in living Chinese hamster ovary (CHO) cells. We found that Dok5 can target constitutively to the plasma membrane, and the PH domain is essential for this process. Furthermore, single-molecule trajectories analysis revealed that Dok5 can constitutively partition into microdomain on the plasma membrane. Finally, the potential mechanism of microdomain localization of Dok5 was discussed. This study provided insights into the characteristics of plasma membrane targeting and microdomain localization of Dok5 in living CHO cells. (C) 2008 Elsevier B.V. All rights reserved.