快速凝固/粉末冶金高阻尼铝合金挤压成形过程的数值模拟

采用有限元分析软件ANSYS,分析了快速凝固/粉末冶金(Rapidly Solidified/Powder Metallurgy,RS/PM)高阻尼铝合金FMS0714/10(Zn-30Al)的挤压成形过程,研究了模具与坯料间的摩擦条件和挤压比对阻尼铝合金成形过程的影响,探讨了挤压过程材料表面产生裂纹的机理,进行了成形工艺优化.研究结果表明:挤压过程中FMS0714/10(Zn-30Al)阻尼铝合金材料的流动与变形不均匀,导致了应力应变分布的不均匀:材料表面应力应变较大,芯部应力应变较小;表面过大的应变和轴向拉应力是表面裂纹的诱因;减小模具和坯料间的摩擦,增大挤压比,可以减小材料表面应力,使应变分布趋于均匀,从而减少材料表面损伤,优化材料表面质量,提高成品合格率.数值模拟的研究结果将为FMS0714/10(Zn-30Al)阻尼铝合金材料挤压工艺的制订以及新材料的设计和研制提供有益的参考.

用Fourier变换莫尔法测量流体自由表面微幅波的振幅

采用一种非接触的光学方法——傅立叶变换莫尔法（Fourier transform method），结合数字图像处理技术，对微幅振荡的水表面波的振幅进行测量。它是对全场中每一个像素点进行测量，比接触测量法具有更高的灵敏度。它为微幅水表面波振幅的测量提供了一种手段。通过将计算机生成的周期性光栅图像经投影机直接投影到被测物体的参考平面，经CCD摄像头、图像板捕捉存储形成数字化的光栅图像，利用傅立叶变换莫尔法处理光栅图像，从而获得包含有水表面波的振幅的相位信息，再经适当的几何变换获得振幅信息。我们在生趣振荡装置上进行了不同激励频率和不同振幅的表面波的振幅测量。

第11届国际快淬和亚稳材料会议简介

第11届国际快淬和亚稳材料会议于2002年8月24~30日在英国牛津大学召开，本次会议由牛津大学材料系承办． 200多名来自欧洲、美国、加拿大、日本、韩国、印度、巴西、澳大利亚、新西兰、中国等29个国家的代表参加了本次大会．会议宣读口头报告244篇，张贴论文117篇，其中包括大会报告11篇，邀请报告31篇．会议论文经严格评审后由Materials Science and Engineering A杂志选择收录．下届会议将于2005年在韩国举行．

第十四届国际近海与极地工程学术会议简介

国际近海与极地工程学术会议(International Offshore and Polar Engineering Conference)是每年一度由国际近海与极地工程学会主办的旨在促进近海工程、极地工程等领域的科技进步以及国际间学术交流与合作的大型国际学术会议.

流动层析成像技术在多相流流型识别与计量中的应用研究

多相流流型识别一直是多相流研究领域难度最大的课题之一 ,流动层析成像技术是进行多相流流型识别、显示及计量的一种新型检测手段。文中概述了国内外主要流动层析成像技术在应用研究方面的进展情况 ,并重点阐述了中国海洋石油总公司与中国科学院力学研究所在电阻流动层析成像技术方面和多相计量方面所开展的研究工作及取得的初步研究成果。虽然流动层析成像技术目前还未应用于工业现场 ,但相关研究工作的开展无疑为流动层析成像技术的深入研究及其在多相流可视化与计量技术方面的应用奠定了基础。

Collecção das Leis do Imperio do Brazil de 1874

Parte 1 - Atos do Poder Legislativo

An algorithm for coarse particle sedimentation simulation by Stokesian dynamics

Coarse Particle sedimentation is studied by using an algorithm with no adjustable parameters based on stokesian dynamics. Only inter-particle interactions of hydrodynamic force and gravity are considered. The sedimentation of a simple cubic array of spheres is used to verify the computational results. The scaling and parallelism with OpenMP of the method are presented. Random suspension sedimentation is investigated with Mont Carlo simulation. The computational results are shown in good agreement with experimental fitting at the lower computational cost of O(N In N).

A temporal and spatial study of invertebrate communities associated with hard-bottom habitats in the South Atlantic Bight

Species composition, biomass, density, and diversity of benthic invertebrates from six bard-bottom areas were evaluated. Seasonal collections using a dredge, trawl, and suction and grab samplers yielded 432, 525, and 845 taxa, respectively. Based on collections wltb the different gear types, species composition of invertebrates was found to change bathymetrically. Inner- and mlddle-shelf sites were more similar to each other in terms of invertebrate species composition than they were to outer-shelf sites, regardless of season. Sites on the inner and outer shelf were grouped according to latitude; however, results suggest that depth is apparently a more important determinant of invertebrate species composition than either season or latitude. Sponges generally dominated dredge and trawl collections in terms of biomass. Generally, cnidarians, bryozoans, and sponges dominated at sites In terms of number of taxa collected. The most abundant smaller macrofauna collected in suction and grab samples were polychaetes, amphipods, and mollusks. Densities of the numerically dominant species changed botb seasonally and bathymetrically, with very few of these species restricted to a specific bathymetrlc zone. The high diversity of invertebrates from hard-bottom sites is attributed to the large number of rare species. No consistent seasonal changes in diversity or number of species were noted for individual stations or depth zones. In addition, H and its components showed no definite patterns related to depth or latitude. However, more species were collected at middle-shelf sites than at inner- or outer-shelf sites, which may be related to more stable bottom temperature or greater habitat complexity in that area. (PDF file contains 110 pages.)

Growth, mortality, and exploitation of the Engraulidae, with special reference to the anchoveta, Cetengraulis mysticetus, and the colorado, Anchoa naso, in the Eastern Pacific Ocean

ENGLISH: Growth and mortality data for Cetengraulis mysticetus, Anchoa naso, Engraulis mordax, E. ring ens, E. anchoita, E. encraslcbolus, E. japonicus, and E. australis were assembled and compared. Estimates of the coefficients of natural mortality, M, of E. anchoita and Ancboa naso were made from the maximum age of the former and from data for the other species. The relative yields per recruit at different fishing mortality rates and lengths at entry into the fishery were calculated for each species, using what are considered to be the best estimates and other likely values of K, a constant of growth, and M. The maximum yields per recruit are theoretically obtainable at very high fishing mortality rates, except when the length at entry is low relative to the asymptotic length. K and M may be positively related to the temperature and to each other, and if such is the case at higher temperatures greater fishing effort would be needed to attain the maximum yield per recruit. The applicability of the yield-per-recruit approach to the data is discussed, and suggestions for further research are made. SPANISH: Se reunieron y compararon los datos sobre el crecimiento y mortalidad correspondientes a Cetengraulis mysticetus, Anchoa naso, Engraulis mordax, E. ringens, E. anchoíta, E. encrasicbolus, E. japonicus y E. australls. Los estimativos de los coeficientes de la mortalidad natural, M, de E. anchoita y Anchoa naso se obtuvieron según la edad máxima de E. anchoita y según los datos de las otras especies. Se calculó para cada especie el rendimiento relativo por recluta a diferentes tasas de mortalidad por la pesca y a diferentes longitudes de entrada a la pesquería, empleándose lo que se considera que son los mejores estimativos y otros valores probables de K, una constante de crecímíento, y M. El rendimiento máximo por recluta se obtiene teóricamente a tasas muy altas de la mortalidad por la pesca con excepción de cuando la longitud a la entrada es baja en relación a la longitud asintótica. K y M pueden estar relacionadas positivamente a la temperatura y mutuamente, y si este es el caso a temperaturas más altas se necesitará un esfuerzo superior de pesca para obtener el rendimiento máximo por recluta. La aplicabilidad del enfoque a los datos rendimiento-por-recluta es discutido y se hacen sugerencias para otras investigaciones. (PDF contains 66 pages.)

Synopse dos trabalhos da Camara dos Srs. Deputados : relativos ao anno de 1920 : acompanhados de differentes documentos : organizada na Secretaria da mesma Camara

Sinopse dos trabalhos da Câmara dos Deputados, em 1920.

Diseño de nodos iniciales en cibermedios : un estudio comparativo

432 p.