997 resultados para 145-883F
Resumo:
纳米技术的出现,使我们有必要更好地了解,在原子水平上材料微结构的变化是如何影响和控制着材料的宏观性能。这一挑战涉及到许多以前不曾考虑和不曾了解的现象.其中,位错理论的基础现在知道是有问题的.宏观尺度下采用的简化假设,也许不能用于微观和纳米尺度。尺度效应的含义,涉及到物理系统的非均质和非平衡特性。宏观尺度下的均匀与平衡特性,在材料的物理尺度减少到微米量级时就不再保持了。这些基本观点不能够为了方便而随意到处使用,因为这会改变预测的结果。更令人不满的是在建立物理模型时缺乏一致性。由此产生的问题是在确定制造过程中的有关参数时无能为力,导致由于成本过高而不切实际的终端产品。先进的复合材料和陶瓷材料就存在这样的问题,本文将要讨论的是在原子尺度与连续介质尺度下应用理论模型时存在的潜在问题,而不是去揭示自然的真相。主要讨论微粒,均匀连续介质或者两者的结合,尺度效应问题当前的发展趋势,趋向于在有或者没有时间效应的情况下寻找材料微结构的不同特征尺寸,从原子模拟模型中将了解到许多情况,原子模拟计算将揭示计算结果如何随着边界条件和尺度变化而不同。量子力学,连续介质力学和宇宙模型证明,没有普遍适用的方法,当前的主要兴趣也许是针对多尺度物理问题在技术上建
Resumo:
[ES] En este investigación se analiza el rico mundo de las supersticiones, de la magia, de la hechicería y de la brujería vasca medieval, centrándose especialmente en el foco de brujería que afectó a la comarca del Duranguesado y que ha pasado a la historiografía y a la tradición popular bajo el sobre nombre de brujas del Amboto.
Resumo:
Presentado en la Jornada de Teatro Griego "Teatro, poesía y pensamiento en la Atenas del siglo V a. C.", Valencia, 19-20 de noviembre de 2007.
Resumo:
A las costas bonaerenses llega en en verano ese típico representante de la fauna sudbrasileña, cuyo estudio consideramos de interés por ser el único bagre que en cierta cantidad suele ser capturado en Mar del Plata y Necochea cuando se realiza la pesca de especies de interés comercial. Damos la sinonimia, descripción y distribución de la especie y, como contribución a su conocimiento, el estudio anatómico del aparato digestivo.
Resumo:
Documento com duas páginas-de-rosto, em português e francês. Título em francês : Rapport présenté a Son Ex. M. le Ministre de l'Industrie, de la Voirie et des Travaux Publics
Resumo:
Coleção formada por três volumes, datados de 1735-1746, que contém, respectivamente, 141, 145 e 196 cartas escritas pelo Padre Vieira, que refletem a mais pura prosa da língua portuguesa. Segundo Francisco Freire de Carvalho, no seu Ensaio da história literária de Portugal, "estas cartas têm merecido ser emparelhadas em virtudes de estilo e na pureza de linguagem às de Cícero, ou pouco menos: e, como tais, elogiadas por todos quantos se prezam de bom gosto literário".
Resumo:
Davidson Seamount is one of the largest seamounts in U.S. waters and the first to be characterized as a “seamount.” In 2002 and 2006, the Monterey Bay National Marine Sanctuary (MBNMS) led two multi-institutional expeditions to characterize the geology and natural history of Davidson Seamount. Results from these expeditions to Davidson Seamount are adding to the scientific knowledge of seamounts, including the discovery of new species. In November 2008, the MBNMS boundary was expanded to include the Davidson Seamount. In addition, a management plan for Davidson Seamount was created to develop resource protection, education, and research strategies for the area. The purpose of this taxonomic guide is to create an inventory of benthic and mid-water organisms observed at the Davidson Seamount to provide a baseline taxonomic characterization. At least 237 taxa were observed and are presented in this guide; including 15 new or undescribed species (8 sponges, 3 corals, 1 ctenophore, 1 nudibranch, 1 polychaete, 1 tunicate) recently or currently being described by taxonomic experts. This is the first taxonomic guide to Davidson Seamount, and is intended to be revised in the future as we learn more about the seamount and the organisms that live there. (PDF has 145 pages.)
Resumo:
Trata-se do "Relatório Cruls", referente à 1ª Missão Cruls (1892-1893), durante o governo Floriano Peixoto
Resumo:
Raquel Merino Álvarez, José Miguel Santamaría, Eterio Pajares (eds.)
Resumo:
本书阐明了板壳断裂理论的基础。论证了Reissner型板壳断裂理论的科学性、经典板壳断裂理论的缺陷及在一定范围内仍具有的实用价值;介绍了作者所创意的研究Reissner型板壳断裂纹尖端场的方法等。
目录
- §1.1 板壳弯曲断裂问题
- §1.2 Kirchhoff经典板壳弯曲断裂理论
- §1.3 Reissner型板壳弯曲断裂理论
- §1.4 Kirchhoff与Reissner型板壳弯曲断裂理论的比较
- §1.5 含裂纹有限尺寸板壳断裂分析的局部-整体法
- §1.6 含表面裂纹板壳
- §2.1 Kirchhoff板的基本概念和基本假定
- §2.2 基本公式与弹性曲面微分方程
- §2.3 边界条件
- §2.4 弹性薄板的应变能
- §2.5 极坐标下的挠曲面微分方程与内力公式
- §2.6 裂纹尖端场特征展开式通项公式
- §2.7 Kirchhoff板弯曲应力强度因子
- §3.1 基本方程和公式的复变函数表示
- §3.2 所引入函数的确定程度与一般形式
- §3.3 坐标变换与边界条件
- §3.4 运用保角变换方法求解孔口问题
- §3.5 应力强度因子与函数Φ(z)的关系
- §3.6 复变-主部分析法之应用简例
- §3.7 共直线裂纹问题的一般解答
- §3.8 典型弯曲裂纹问题的解答及弯曲应力强度因子公式
- §3.9 共圆曲线裂纹问题的解答及弯曲应力强度因子公式
- §4.1 裂纹尖端奇异元的位移模式与弯曲应力强度因子
- §4.2 裂纹尖端奇异元的刚度矩阵
- §4.3 裂纹尖端奇异元与常规单元的连接
- §4.4 解析法与数值法的结果比较与讨论
- §4.5 两共线半无限裂纹问题的定解条件及解的实用价值
- §5.1 Reissner型板的基本假定
- §5.2 Reissner型板的基本公式与平衡微分方程
- §5.3 基本方程的简化
- §5.4 边界条件
- §5.5 极坐标下的基本公式与平衡微分方程
- §5.6 两种平板理论用于无裂纹板时的比较
- §5.7 两种乎板理论用于含裂纹板时的比较
- §6.1 基本方程和一般求解方法
- §9.1 局部-整体法与其它解析和数值法的结果比较
- §9.2 边界对应力强度因子的影响
- §9.3 板的支承条件及长宽比的影响
- §9.5 计算Reissner型板应力强度因子的一组近似方程与近似解法
- §9.4 Reissner型板理论与Kirchhoff板理论所得应力强度因子的比较
- §9.6 关于数值计算的几点讨论
Resumo:
This atlas presents information on fish eggs and temperature data collected from broadscale ichthyoplankton surveys conducted off the U.S. northeast coast from ]977 to 1987. Distribution and abundance information is provided for 33 taxa in the form of graphs and contoured egg-density maps by month and survey. Comments are included on interannual and interseasonal trends in spawning intensity. Data on 14 additional but less numerous taxa are provided in tabular form. (PDF file contains 316 pages.)
Resumo:
In order to study the colonization and development of moss mites (Oribatida) communities in a Scots pine forest of a reclaimed limestone mine dump in Northern Poland, 3 plots from the dump were chosen. The selected plots differed in age, 5 years old, 35 and 50 years old. From a total of 30 samples 499 mites (Acari) were extracted in Tullgren funnel from which 262 were Oribatida. Abundance (N) was analyzed in all mites and after determining the species of both, juvenile and adult stages of oribatids, the following indices were analyzed: Abundance (N), Dominance (D), Species diversity (S), Species richness (s) and Shannon’s diversity index (H). Regarding to the results obtained; oribatid mites were dominant with the highest abundance in all assemblages (Plot 1: 139 Oribatida /299 Acari. Plot 2: 40/55 and Plot 3: 83/145). Tectocepheus velatus showed a very high dominance (45,99%) in plot 1; the highest value for Shannon’s diversity index belonged to plot 3. On the other hand, juvenile’s percentage was significantly higher than adult’s percentage, especially at plot 2 (95,02%). These results made us to conclude that the high abundance of oribatids in the youngest forest is due to T. velatus’s high abundance and that plot 3 is the best habitat for mites. Finally, the high occurrence of juvenile stages requires keeping on studying the area.
Resumo:
Este artículo explica que la comarca natural del Bajo Deba constituye un espacio socio-económico integrado que ha padecido un fuerte proceso de desestructuración económica, cuyas consecuencias más visibles son la pérdida de empleo industrial, la caída de la población, y el elevado grado relativo de desempleo y pobreza. Sobre este escenario, se configura un nuevo sistema institucional operante en el territorio vasco, fruto de los cambios jurídico-políticos y de la nueva percepción del papel de los agentes públicos en actividades de promoción económica. Y en este contexto, analizan la actuación de la agencia de desarrollo comarcal DEBEGESA y su capacidad de adaptación a las transformaciones experimentales a lo largo de su existencia.