虚拟激光柔性加工的完整过程仿真模型研究——覆盖件模具的激光硬化

提出了虚拟激光柔性加工系统的体系结构，运用IGRIP建立包括虚拟场景和虚拟加工设备的虚拟激光柔性加工平台；以覆盖件模具表面激光硬化加工为例，综合分析其过程中各影响因素（几何、激光、材料等方面的因素），建立了基于神经网络的工艺力学模型，并嵌入到虚拟加工平台中，以实现包括几何仿真与物理仿真的完整仿真过程，预测加工效果，为真实加工提供有效依据。

炸药装药的发射起爆概率与质量限定条件初探

讨论火炮发射时炮弹炸药装药的发射起爆概率、寻找制订炮弹炸药装药质量限定条件的方法。

深水平台动力分析问题

<正> 世界上第一座采油平台建造于1947年,在美国的墨西哥湾,水深只有六公尺。25年来海上平台的建设得到了迅猛的发展,当前世界上已经建成了近一万座,水深也不断增加,突破了三百公尺大关。随着水深的增加,动力分析的重要性越来越突出了。平台承受的最主要的波浪载荷通常在5—15秒周期范围内为高能带,三百公尺水深的钢导管架(图1)平台的自然周期在5秒附近,正好靠近这个范围,因而造成动力放大。低于三百公尺的平台,只要它的自然周期离5秒不太远,也会有一定的动力放大,而每年数百万次的循环应力就会造成结构局部疲劳,土壤在长期循环应力作用下也有疲劳问题,会发生刚度退化导致平台的自然周期向波谱高能带漂移,使动响应进一步放大,造成恶性循环。所以平台结构动力分析的目

Numerical study on heavy rigid particle motion in a plane wake flow by spectral element method

Experimental particle dispersion patterns in a plane wake flow at a high Reynolds number have been predicted numerically by discrete vortex method (Phys. Fluids A 1992; 4:2244-2251; Int. J. Multiphase Flow 2000; 26:1583-1607). To address the particle motion at a moderate Reynolds number, spectral element method is employed to provide an instantaneous wake flow field for particle dynamics equations, which are solved to make a detail classification of the patterns in relation to the Stokes and Froude numbers. It is found that particle motion features only depend on the Stokes number at a high Froude number and depend on both numbers at a low Froude number. A ratio of the Stokes number to squared Froude number is introduced and threshold values of this parameter are evaluated that delineate the different regions of particle behavior. The parameter describes approximately the gravitational settling velocity divided by the characteristic velocity of wake flow. In order to present effects of particle density but preserve rigid sphere, hollow sphere particle dynamics in the plane wake flow is investigated. The evolution of hollow particle motion patterns for the increase of equivalent particle density corresponds to that of solid particle motion patterns for the decrease of particle size. Although the thresholds change a little, the parameter can still make a good qualitative classification of particle motion patterns as the inner diameter changes.

Fabrication and spectral properties of Nd3+-doped yttrium lanthanum oxide transparent ceramics

Transparent 1 at% Nd3+:Y1.9La0.1O3 ceramics were fabricated with nanopowders prepared by carbonate coprecipitation method. The powder compacts were sintered in H-2 atmosphere at 1550 degrees C for 30 h. The Nd3+:Y1.9La0.1O3 ceramics display uniform grains of about 50 mu m and high transparency. The highest transmittance of the ceramics reaches 67%. The strongest absorption peak is in the wavelength of 820 nm with absorption cross section of 2.48 x 10(-20) cm(2). The absorption is still high at LD wavelength 806 nm with absorption cross section of 1.78 x 10(-20) cm(2) and broad full width at half maximum (FWHM) of about 6.3 nm. The strongest emission peak was centered at 1078 nm with large stimulated emission cross section of 9.63 x 10(-20) cm(2) and broad FWHM of about 7.8 nm. The broad absorption and emission bandwidth of Nd3+:y(1.9)La(0.1)O(3) transparent ceramics are favorable to achieve the miniaturized LD pumping apparatus and ultrashort modelocked pulse laser output, respectively. (c) 2007 Elsevier B.V. All rights reserved.

中国西北地区蜜源植物花粉

我们采用光学显微镜和扫描电子显微镜观察了68种我国西北地区蜜源植物的花粉，并用透射电子显微镜观察了其中的5种。在文中，每种花粉的形态都有比较详细的描述。此外，作者还总结了蜜源植物花粉的形态特征，编制了这些花粉的形态检索表。 我们比较了虫媒植物和风媒植物的花粉。在形态上，它们有明显的不同之处。一般来说，虫媒植物的花粉粒较大，较重，表面纹饰较粗、具粘液;它们还常集结成块状。 紫草科花粉的异萌发孔、柳叶菜科柳兰花粉、伞形科芫荽花粉的极帽等形态均较特殊，文中作了详细的讨论。 花粉的大小和形状在醋酸酐分解前后多有变化。一般变化规律是：花粉粒大的，形态变化大;花粉粒小的，形态变化小。球形，具散孔花粉变化很小。 我们还对花粉形态研究中光镜、扫描电镜、透射电镜的使用进行了比较。

杉科植物的系统发育、 分类和地理分布

本文对杉科植物的分类系统作了回顾。以形态学为依据，参考其他学科的研究成果，用分支分析和表征分析两种方法探讨了杉科植物的系统演化关系．提出了新的分类系统。对杉科植物的系统分类作了修订．通过对各属现代分布和地史分布的研究，结合古地理和古气候资料，讨论了杉科植物的分布中心、起源时间、起源地、散布途径及现代分布格局的成因．主要结论如下： 1．属间关系：柳杉属是现存杉科植物中最原始的类群．水松属和落羽杉属关系密切，二者与柳杉属近缘．巨杉属和北美红杉属关系密切，是中级进化水平的类群．水杉属的系统位置比较孤立，与巨杉属和北美红杉属的关缘关系相对较近．杉木属、密叶杉属和台湾杉属关系密切，是杉科植物中的高级进化类群，其中台湾杉属最为进化． 2．系统排列：支持金松科的成立．将杉科分成5族，即柳杉族（仅含柳杉属）、落羽杉族（含水松属、落羽杉属）、北美红杉族（含巨杉属、北美红杉属）、水杉族（仅含水杉属）和杉木族（含杉木属、密叶杉属及台湾杉属）． 3．分类：经修订，杉科植物共9属12种4变种．将德昌杉木、米德杉木和厚皮杉木归并，作为杉木的变种，支持柳杉作为日本柳杉的变种、台湾杉木作为杉木的变种、秃杉和台湾杉归并的观点。 4．地理分布：我国长江、秦岭以南至华南一带是杉科的现代分布中心，我国华北北部及东北、朝鲜、日本和前苏联西伯利亚东南部等地可能为起源中心和早期分化中心，起源时间可追溯至早侏罗纪或晚三叠纪．杉科的现存各属均为古老的孑遗类群．

云南鹅线粒体DNA多态及酶切图谱分析

用１８种限制性内切酶对７只云南鹅的线粒体ＤＮＡ（ｍｔＤＮＡ）进行了限制性片段长度多态（ＲＦＬＰ）分析。１７种酶在所有受试个体表现为一致的限制性态型（ｍｏｒｐｈ），一只灰羽鹅用ＰｖｕＩ消化时出现变异。用１４种限制性内切酶构建了云南鹅ｍｔＤＮＡ的酶切图谱。

宁夏二代防护林网结构抗虫性评价与判别

应用数量化理论 、聚类分析和逐步判别分析法将二代林网林分受光肩星天牛、木蠹蛾和枝梢害虫危害各分为 4类 (即林分抗虫性分类 ) ,并建立了相应类别的判别函数 ,经检验所分类别和所建判别函数均达到显著水平。综合分析得出 :类别的前 2类为相应害虫的抗性林分 ;抗虫林分是指在三类害虫危害分类时均被分在前两类中的林分 ,也是二代林网进一步发展所应采取的林分配制形式 ;林分结构合理化是害虫不成灾最有效的手段之一 ;新建林网有效控制了光肩星天牛的发生 ;各类防护林以城市林网的综合抗虫性最强 ;二代林网中对各害虫都具有较高抗性林分的比例为 2 0 % ;光肩星天牛、木蠹蛾、枝梢害虫的倾性林分在林网中所占比例分别为 1 5 %、1 2 %、8%。

Independent Transport and Sorting of Functionally Distinct Protein Families in Tetrahymena thermophila Dense Core Secretory Granules

Dense core granules (DCGs) in Tetrahymena thermophila contain two protein classes. Proteins in the first class, called granule lattice (Grl), coassemble to form a crystalline lattice within the granule lumen. Lattice expansion acts as a propulsive mechanism during DCG release, and Grl proteins are essential for efficient exocytosis. The second protein class, defined by a C-terminal beta/gamma-crystallin domain, is poorly understood. Here, we have analyzed the function and sorting of Grt1p (granule tip), which was previously identified as an abundant protein in this family. Cells lacking all copies of GRT1, together with the closely related GRT2, accumulate wild-type levels of docked DCGs. Unlike cells disrupted in any of the major GRL genes, Delta GRT1 Delta GRT2 cells show no defect in secretion, indicating that neither exocytic fusion nor core expansion depends on GRT1. These results suggest that Grl protein sorting to DCGs is independent of Grt proteins. Consistent with this, the granule core lattice in Delta GRT1 Delta GRT2 cells appears identical to that in wild-type cells by electron microscopy, and the only biochemical component visibly absent is Grt1p itself. Moreover, gel filtration showed that Grl and Grt proteins in cell homogenates exist in nonoverlapping complexes, and affinity-isolated Grt1p complexes do not contain Grl proteins. These data demonstrate that two major classes of proteins in Tetrahymena DCGs are likely to be independently transported during DCG biosynthesis and play distinct roles in granule function. The role of Grt1p may primarily be postexocytic; consistent with this idea, DCG contents from Delta GRT1 Delta GRT2 cells appear less adhesive than those from the wild type.

Revision of the genus Niwaella in China (Pisces, Cobitidae), with description of two new species

Loaches of the genus Niwaella, family Cobitidae, are distributed only in East Asia. At present only in Japan and South Korea have fishes of the genus Niwaella been found. Herein we revise the genus Niwaella in China. Son and He ( 2001) transferred the species Cobitis laterimaculata to the genus Niwaella, but their specimens were not N. laterimaculata, but a new species, N. longibarba sp. n., collected from Cao'ejiang River, Huangzezhen, Chengxian County, Zhejiang Province. The new species is distinguished from N. laterimaculata by its colour pattern of a row of slightly large, and long, scattered dark brown vertical bars on the dorsolateral surface, two or three striations on the caudal fin, and long barbels and undeveloped mental lobes. In this paper we also describe another new species, N. xinjiangensis sp. n., collected from Xinjiang River, Guangfeng County, Jiangxi Province, May 1990, with diagnostic colour pattern of 17 - 20 large and long, dark brown vertical bars on the dorsolateral surface, a dark stripe or rounded black spots along the lateral midline and some blotches below the lateral midline; it is a large-sized species, with shorter barbels, and longer caudal peduncle. Thus five species of the genus Niwaella are known, three are endemic to eastern China and two are endemic to either Japan or South Korea.