液Ar冲击压缩特性的理论计算

用exp-6有效两体势模型和液体变分微扰理论计算了液Ar冲击压缩曲线,在35GPa以下的压力范围内计算的冲击压缩曲线与Thiel及Nellis等人的实验数据及其它理论的计算结果符合较好。计算结果表明文中所选的势较为准确地反映了液体分子间的相互作用。也对较高冲击压力下理论计算的冲击曲线和实验结果之间的偏差作了分析,结合不透明度实验的结果,我们认为当压力超过35GPa,温度在12000K以上时,液Ar体系电子激发对系统热力学状态有较大影响。     

等离子体源离子渗氮 1Cr18Ni9Ti 奥氏体不锈钢磨损特性的试验研究

用等离子体源离子渗氮，即低能（１～３ｋｅＶ）、超大剂量（１０１９～１０２０ｉｏｎｓ／ｃｍ２量级）Ｎ＋注入－同步扩散改性技术，在２８０℃和３８０℃下处理１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢，获得了最大深度分别为１．６μｍ和１０．６μｍ，固溶Ｎ的最高原子浓度均约为２５％的Ｎ过饱和面心立方相（γＮ）改性层．销－盘磨损试验表明：在２ｍ／ｓ和较宽负荷范围（等效正应力０．２～２．８ＭＰａ）条件下，高硬度（ＨＫ０．１Ｎ２２００）的γＮ相改性层具有较高的承载能力和较长的耐磨寿命．高度过饱和Ｎ在母相奥氏体中的固溶强化作用，是使等离子体源离子渗氮奥氏体不锈钢耐磨性提高的主要原因．     

高温高密度液氦冲击压缩特性理论研究

选择高密度液氦作为研究对象,采用F.H.Ree修正的WCA状态方程和改进的分子流体微扰变分统计理论（MCRSR）,并且考虑液氦体系低温量子力学效应,计算了一次和二次冲击压力在0～108 GPa、对应温度为471～32 790 K范围内的高压物态方程。在确定体系分子间相互作用时,通过实验数据拟合选取了较合理的指数6势参数。理论计算结果与实验数据吻合较好。     

TiNi合金冲击相变过程中温度变化规律的实验研究

针对初始SME(shape memory effect)和PE(pseudo-elastic)状态TiNi合金试样,采用带有红外测温系统的SHPB冲击压缩装置,实时测量了冲击相变过程中两种材料试样表面瞬态温度,并根据实验结果计算了相应的温度变化。实验结果表明,冲击加载相变过程中,温度随相变应变的增大而升高,当应变最大时,温度最高;卸载过程中,对初始PE状态试样,温度降低,对初始SME状态试样,温度保持最高温度不变或降低,这同加载最高温度有关;卸载完成后,两种试样温度均高于其初始温度。计算温度结果表明,相变耗散功对加、卸载相变过程中温度变化的作用不可忽略。     

液氮冲击压缩特性及其分子离解相变研究

利用液氮制冷技术制取液氮样品 ,以二级轻气炮为加载工具 ,对液氮样品进行平面冲击压缩 ,实验测量了液氮 10～ 6 0GPa一次冲击Hugoniot数据。实验结果显示 ,33GPa以上氮的冲击波速度 -粒子速度关系式与低压段有明显差别 ,表现为氮的压缩系数增大。经理论计算和分析 ,可以认为液氮在冲击压力 33GPa以上 ,液氮体系会发生分子离解相变。     

冲击压缩LY12铝向不同充气介质卸载后的光反射率实验研究

用二级氢气炮作为冲击压缩加载工具和多通道瞬态辐射高温计作为主要测量系统,对装有初始压力为6 MPa和1.2 MPa的氦气、氘气和氢氘混合气体冲击压缩等离子体的光谱幅亮度历史进行了测量。根据实测记录信号波形的有关特征量,拟合得到了冲击压缩LY12铝基板表面光反射率R。结果发现:受冲击LY12铝基板表面对340~800 nm波长向不同充气介质氦气、氘气和氢氘混合气体等离子体卸载后的光反射率为约0.4,为静态下铝基板反射率(约0.8)的一半。并对动态加载下反射率降低的机理进行了探讨。     

弯曲疲劳短裂纹扩展规律研究

本文对３５ＣｒＭｏ钢和４２ＣｒＭｏ钢带穿透短裂纹（初始裂纹长度ａ＝０．１～０．５ｍｍ）的试件进行了弯曲疲劳试验研究，得到了在弯曲疲劳加载下短裂纹扩展速率的计算表达式以及应力比，试件厚度对短裂纹扩展的影响。     

金属样品与窗口之间的缝隙对冲击波温度测量的影响

利用块状铁样品测得了pH=184GPa,pH=193GPa两个冲击压力下的样品/窗口界面温度,分别按照Gallagher等人最新发表的蓝宝石在高压下的热传导率和按照汤文辉的理论计算的蓝宝石在高压下的热传导率数据及三层介质热传导模型的结果计算了铁在这两个压力下的温度,并与Bass及汤文辉等人发表的数据及McQueen的理论计算值进行了比较。本文用三层介质模型得到t→∞时的（实际只要t在约30-50ns以后）结果与已经发表和理想界面模型实验数据符合较好,这说明金属样品与窗口之间的缝隙对冲击波温度测量没有影响。     

液氘的冲击压缩特性——自由电子气模型计算

用自由电子气模型对自由电子气(费米能为5eV)的冲击压缩雨贡纽曲线、冲击温度进行了数值计算。结果表明，自由电子气的冲击压缩极限近似为初始密度的4倍。     

反应金属冲击反应过程的理论分析

基于1维冲击波理论和粉末材料的冲击温度计算模型对反应金属的冲击响应行为、冲击温度及冲击反应过程进行了理论分析,分别考虑了材料密实度、冲击速度对冲击压力、冲击温度的影响;结合粉末材料冲击温度计算结果及冲击反应的化学动力学方法,提出了考虑反应效率的反应金属冲击反应理论模型。利用新模型得到的计算结果与已有实验结果吻合较好。反应金属的冲击反应行为受密实度、冲击速度及材料种类影响明显。 更多还原     

The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

Preface

This special issue of PARTICUOLOGY is devoted to the first UK-China Particle Technology Forum taking place in Leeds, UK, on 1-3 April 2007. The forum was initiated by a number of UK and Chinese leading academics and organised by the University of Leeds in collaboration with Chinese Society of Particuology, Particle Technology Subject Group （PTSG） of the Institution of Chemical Engineers （IChemE）, Particle Characterisation Interest Group （PCIG） of the Royal Society of Chemistry （RSC） and International Fine Particle Research Institute （IFPRI）. The forum was supported financially by the Engineering and Physics Sciences Research Council （EPSRC） of United Kingdom,     

基于鲁棒滤波的捷联导引头视线角速度估计方法

针对捷联导引头无法直接获取视线角速度等信息的问题,研究了鲁棒滤波在大气层外飞行器捷联导引头视线角速度估计中的应用。为了建立非线性滤波估计模型,考虑目标视线角速度的慢变特性,采用一阶马尔科夫模型建立了状态方程;推导了视线角速度的解耦模型,并建立了量测方程;考虑到实际应用中存在系统噪声统计特性失准的问题,基于Huber-Based鲁棒滤波方法,设计了视线角速度滤波器,并完成了基于Huber-Based滤波方法和扩展卡尔曼滤波方法的数学仿真。仿真结果表明Huber-Based滤波方法的视线角、视线角速度及视线角加速度估计精度分别达到0.1140'、0.1423'/s、0.0203'/s2,而扩展卡尔曼滤波方法的视线角、视线角速度及视线角加速度估计精度仅分别为0.6577'、0.6415'/s、0.0979'/s~2。仿真结果证明了该方法可以有效地估计出相对视线角速度等信息,并且在非高斯噪声的条件下,依然可获得较高的估计精度,具有一定的鲁棒性。     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica     

Use specification of multiscale materials for life spanned over macro-, micro-, nano-, and pico-scale

Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say—macro, micro, nano, and pico,—, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions and/or f_j/j+1 are introduced to quantify these characteristics. They are represented, respectively, by , and (f_mi/ma,f_na/mi,f_pi/na). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10⁻¹², 10⁻⁹, 10⁻⁶, 10⁻³ m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales, RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials.