第一届Batchelor奖获得者Howard Stone教授研究工作简评

Batchelor流体力学奖和Hill固体力学奖是国际理论与应用力学联合会(IUTAM)设立的两个奖项,旨在表彰获奖者过去十年内在其力学分支学科研究中所做出的重要贡献.Batchelor流体力学奖和Hill固体力学奖每4年评选一次,在第22届国际理论与应用力学大会(8月24～29日,澳大利亚阿德莱德)上第一次颁奖.Howard Stone教授和Michael Ortiz教授分别是Batchelor奖和Hill奖的获奖人.本刊在《简评》栏目刊登胡国庆研究员和黎波教授对两位获奖者成果的简评,并在《译文》栏目刊登两位教授的代表性论文的译文各一篇,以饷读者.

非定常膨胀波进入圆管后壁面附面层增长的计算

<正> 一、引 言 为了提高管风洞、激波管的运行品质,非定常膨胀波进入圆管后壁面附面层增长问题的研究有着重要意义。尤其在跨音速管风洞,贮气管内附面层随时间的增长情况,直接影响到管风洞的运行时间及流动品质。这一问题的解决是设计管风洞的前提和基础。 贝克尔(E.Becker)首先计算了贮气管道内附面层的增长。他用二元不可压缩的假定和1/7次方速度分布,简化了附面层动量积分方程;然后用勃拉休斯(Blasius)表面摩擦规律求出了解,并得到了等效的有心膨胀波运动速度。虽然在附面层内及表面摩擦系

The effect of strain softening in the matrix material during void growth

Furthermore, the compressed flow driven by the piston is discussed. The consistent solution of gasdynamical equations including solar gravity is obtained for the unsteady and two-dimensional configuration, which is applied to the region between the piston and shock wave. This solution may satisfy the jump conditions of shock wave, which separates the region of compressed flow and quiet corona.

微通道中应用“流动汇聚”形成分散体系

在微流控器件内集成具有流动汇聚功能的几何结构以研究液-液系统中液滴的形成.相图显示液滴的大小为流量以及两种液体流量比的函数,它包括两个区域,在一个区域中液滴大小和孔隙宽度接近,而在另一区域液滴大小则取决于"汇聚"后的细流直径,从而能形成远小于孔隙的液滴.单分散和多分散乳状液均可以被生成.

A planar waveguide Nd : YAG laser using active Q-switching of a hybrid unstable resonator

A planar waveguide laser operating in a negative branch unstable resonator is Q-switched by an acoustooptic mod latorin anew configuration, providing effective, high-speed switching. The laser using a 200-mu m Nd:YAG core, face pumped by 10 laser diode bars, has produced 100-W output in a good beam quality at 100-kHz pulse rate, and 4.5 mJ at lower frequency with 15-ns pulse duration.

Genome 10K: A Proposal to Obtain Whole-Genome Sequence for 10 000 Vertebrate Species

The human genome project has been recently complemented by whole-genome assessment sequence of 32 mammals and 24 nonmammalian vertebrate species suitable for comparative genomic analyses. Here we anticipate a precipitous drop in costs and increase in sequ

鸟类宏观分类和区系地理学研究概述

据Dickinson，E．C．，主编，2003年出版的“m Howard and Moore Gomplete Q蛐ofthe Birds of the World'’一书和2000。2008年的有关文献的记载，在1958～2008年的50年期间，全世界所描述发表鸟类的新种，计 有171种。以每10年中所发表的新种数进行统计比较，以1997～2007年期间所发表的新种为最多；按发现新种所属 目级分类阶元的统计比较，以雀形目发现的新种为最多；按地区进行统计比较，以南美洲发现的新种数为最多，非洲中南部地区和太平洋诸岛为次；在中国境内描记的新种有台湾短翅莺西哟脚嬲旋渤删、峨嵋柳莺场皿瞰灿mzden面、海南柳莺崩砌蚴‰肠砌船、峨嵋鹪莺岛匆船硎豳面、淡尾鹅莺崩锄船．．toror、弄岗穗鹛＆叻帕御赠删、 四川旋木雀眺砌婶删等7种，其中由中国鸟类学者描记的有四川旋木雀和弄岗穗鹛两种。这说明鸟类的宏 观分类研究，时至今日仍有研究的必要和发展空间。种下分类，是探讨同一个物种，随着分布区域的扩大，自然地 理环境条件的变化，而产生地区性分布种群的变异，以致新物种形成的途径，是宏观分类学研究一个物种的演化发 展。所以是当今鸟类分类研究的热点之一。据统计，1958—2008年的50年间，新描述发表的亚种数，约为1 129亚 种。繁殖区域分布较为广泛的种类，所描记的亚种较多。如岛鸫Turd．sp，hbcephaha分化有5l亚种之多。中国鸟类的 分类与区系地理学研究，大致可分为起步时期(1949年以前)、新中国建立之后的考察及宏观分类研究的总结整理 时期(1950—2005)和宏观与微观相结合的发展研究时期(1999年以后)等3个时期。郑作新所出版的《中国鸟类 分布名录》和《中国鸟类区系纲要》等专著，是中国鸟类宏观分类和区系地理学研究较为翔实的阶段性总结，为进 一步研究奠定了坚实的基础。

Magneto-optical properties of diluted magnetic semiconductor quantum dots

The magnetoexciton polaron (MP) is investigated theoretically in a diluted magnetic semiconductor quantum dot (QD), with the Coulomb interaction and the sp-d exchange interaction included. The MP energy decreases rapidly with increasing magnetic field at low magnetic field and saturates at high magnetic field for small QDs, and the dependences of the MP energy on magnetic field are quite different for different QD radii due to the different carrier-induced magnetic fields B-MP. The competition between the sp-d exchange interaction and the band gap shrinkage results in there being a maximum exhibited by the MP energy With increasing temperature. Our numerical results are in good agreement with experiment (Maksimov A A, Bacher G, MacDonald A, Kulakovskii V D, Forchel A, Becker C R, Landwehr G and Molenkamp L W 2000 Phys. Rev. B 62 R7767).

A study of fucoidan from the brown seaweed Chorda filum

Fucoidan fractions from the brown seaweed Chorda filum were studied using solvolytic desulfation.Methylation analysis and NMR spectroscopy were applied for native and desulfated polysaccharides.Homefucan sulfate from C.filum was shown to contain poly-a-(1-3)-fucopyranoside backbone with a high degree of branching,mainly of a-(1-2)-linked single units.Some fucopyranose residues are sulfated at O-4(mainly) and O-2 positions.Some a-(1-3)-linked fucose residues were shown by NMR to be 2-O-acetylated.The 1H and 13C NMR spectra of desulfated,deaceylated fucan were complerely assigned.THe spectral data obtained correspond to a quasiregular polysaccharide structure with a branched hexasaccharide repeating unit.Other fucoidan frations from C.filum have more complex carbohydrate composition and give rather complex methvlation patterns.

Sensitisation identification of stainless steel to intergranular stress corrosion cracking by atomic force microscopy

A new technique was developed for characterisation of stainless steel to intergramilar stress corrosion cracking by atomic force microscopy. The technique proved to be effective in sensitisation identification of AISI 304 stainless steel and might be promising in sensitisation identification of other stainless steels. (c) 2007 Elsevier B.V. All rights reserved.

俯冲带深部流体特征——以西南天山变质俯冲杂岩为例

The subduction zone is an important site of the fluid activity and recycling of chemical elements. The fluid characteristic of deep subduction zones is a top scientific problem attracting the petrologists, geochemists and tectonists. In this dissertation, the characteristics of fluid activity within a deep subduction zone have been explored on the basis of the studies on the petrography, mineral chemistry, fluid inclusions, geochemistry and metamorphic P–T conditions of the omphacite-bearing high-pressure veins and related hosts from the low-temperature/high-pressure metamorphic belt in southwestern Tianshan, China. Multiple high-pressure veins are exposed in host eclogites and blueschists. The veins are composed predominantly of omphacite, garnet, quartz, and other minerals. Some veins contain cm-sized rutiles. In general, the vein can be divided into three types, the ‘in situ dehydration’ vein, the ‘external transport’ vein and the ‘composite’ vein. The omphacites within the veins and related host rocks contain lots of two-phase or three-phase primary fluid inclusions. The final melting temperature (Tfm) of fluid inclusions varies mainly from -0.6 to -4.3 °C, the homogeneous temperature (Th) varies from 185 to 251 °C, the salinity varies from 1.1 to 6.9 wt.% NaCl equivalent and the density varies from 0.81 to 0.9 g/cm3. The fluids were released under the conditions of T = 520–580°C and P = 15–19 kbar at blueschist facies to eclogite facies transition. The fluids include not only Li, Be, LILE, La, Pb-enriched and HFSE- and HREE-depleted aqueous fluids but also HFSE (Ti-Nb-Ta)-rich aqueous fluids. The complex composed of aluminosilicate polymers and F was the catalyst which had caused the Ti-Nb-Ta to be dissolved into the fluids. During the transport of the LILE-rich and HFSE- and HREE-poor fluids, they can exchange some chemical elements with country rocks and leach some trace elements in some extent. The rutile could be precipitated from the HFSE (Ti-Nb-Ta)-rich aqueous fluids when CO2 was added into the fluids. The host rocks could obtain some elements, such as Ca, Cs, Rb, Ba and Th, from the external fluids. The fluids with complex composition had been released within the deep subduction zone (>50 km) in Early Carboniferous during the subduction of the South Tianshan Ocean under the Yili–Central Tianshan Plate. The results obtained in this dissertation have made new progress compared with the published data (e.g. Tatsumi, 1989; Becker et al., 1999; Scambelluri and Philippot, 2001; Manning, 2004; Hermann et al., 2006; Spandler and Hermann, 2006).

中国企业员工组织承诺研究

The research objectives were to investigate the psychological structure of employees' organizational commitments(OCs), and its antecedents, and to examine the relative effects of employees' OCs to their performances. In order to deeply uncover the nature of OCs, some standard methods, such as in-depth interview, focus-group, semi-open questionnaire, standard questionnaire etc., were employed. In data analysis, not only some common statistical methods, such as multivariate analysis of variance, cross-table analysis, factor analysis, but also some forefront ones, such as confirmatory factor analysis and path analysis of SEM, were used. The paper covers six chapters: 1) In the first chapter, Firstly some previous empirical studies, which examined structures, antecedents, correlates, and/or consequences of organizational commitment in China and Western countries, were summarized. This summary covers most of the respectable researchers' works of this field, such as H.S.Becker, B.Buchanan, L.W.Porter, G. Ritzer, H.M.Trice, J.A.Alutto, L.G.Hrebiniak, R.T.Mowday, J.P.Meyer, N.J.Allen, G.W.McGee, R.C.Ford, R.Eisenberger, etc. Then three theoretical hypothesis were put forward as following: ① In China, OCs should be multidimensional psychological structures, which means there should exist more than one type of OCs; ② There should be some different antecedents to different OCs; ③ Employees with different types of OC should perform differently in their works. Finally the theoretical and practical significance were discussed. 2) In the second chapter, great efforts were made to investigate the OC types. Firstly, in-depth interview with managers and employees, semi-open questionnaire, and some other methods were used in the pilot research to gather much qualitative material. Then OC questionnaire was designed to get quantitative data in about 20 enterprises, including state-owned, collective-owned, wholly foreign-funded, and joint-ventures. During revising of this questionnaire, there were about 5000 samples surveyed. after factor analysis, the data shows that there should be 5 types of OCs in China, which were respectively named as Affective Commitment, Normative commitment, Ideal Commitment, Economic Commitment, Choice Commitment. Thirdly, confirmatory factor analysis method was used to successfully confirm this 5-factor model. Finally, Cronbach a and test-retest correlate indicate that this questionnaire is reliable. Since factor analysis result has show its construct validity, a simple criterion-related validity research was conducted. 3) In order to investigate the correlation between different OC and employee performance and different antecedents of OC, 5 other questionnaires, such as Employee Satisfaction Questionnaire, Perceived Organizational Support Questionnaire, Social Exchange Questionnaire, Altruism Scale, and Leader Confidence Scale were revised in the third chapter. 4)In the fourth chapter, a lot of correlates, cross-table analysis were conducted to show the correlation between different OCs and 10 performances, which indicate employees with different OCs will show different performance in 10 variables, such as altruism, etc. 5) In the fifth chapter, correlate analysis, multivariate of analysis, and path analysis of SEM were used to investigate the antecedents of OC. A satisfactory model showing the correlation between OC and their antecedents was confirmed. 6) In the last chapter, all researches about OC, and its limitations were summarized.