979 resultados para 109-648
Resumo:
An empirical study is made on the fatigue crack growth rate in ferrite-martensite dual-phase (FMDP) steel. Particular attention is given to the effect of ferrite content in the range of 24.2% to 41.5% where good fatigue resistance was found at 33.8%. Variations in ferrite content did not affect the crack growth rate when plotted against the effective stress intensity factor range which was assumed to follow a linear relation with the crack tip stress intensity factor range ΔK. A high corresponds to uniformly distributed small size ferrite and martensite. No other appreciable correlation could be ralated to the microstructure morphology of the FMDP steel. The closure stress intensity factor , however, is affected by the ferrite content with reaching a maximum value of 0.7. In general, crack growth followed the interphase between the martensite and ferrite.
Dividing the fatigue crack growth process into Stage I and II where the former would be highly sensitive to changes in ΔK and the latter would increase with ΔK depending on the ratio. The same data when correlated with the strain energy density factor range ΔS showed negligible dependence on mean stress or R ratio for Stage I crack growth. A parameter α involving the ratio of ultimate stress to yield stress, percent reduction of area and R is introduced for Stage II crack growth so that the data for different R would collapse onto a single curve with a narrow scatter band when plotted against αΔS.
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In this paper we explore techniques to identify sources of electric current systems and their channels of flow in solar active regions. Measured photospheric vector magnetic fields (VMF) together with high-resolution white-light and H filtergrams provide the data base to derive the current systems in the photosphere and chromosphere. Simple mathematical constructions of fields and currents are also adopted to understand these data. As an example, the techniques are then applied to infer current systems in AR 2372 in early April 1980. The main results are: (i) In unipolar sunspots the current density may reach values of 103 CGSE, and the Lorentz force on it can accelerate the Evershed flow, (ii) Spots exhibiting significant spiral pattrn in the penumbral filaments are the sources of vertical major currents at the photospheric surface, (iii) Magnetic neutral lines where the transverse field was strongly sheared were channels along which strong current system flows, (iv) The inferred current systems produced oppositely-flowing currents in the area of the delta configuration that was the site of flaring in AR 2372.
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Based on a general background we have developed a mechanical model of the catastrophic change of steady flow in collapsible tubes and got the critical conditions for the catastrophic change analyzing the effects of viscosity, gravity and the longitudinal gradient of external pressure. Several simple flows have been discussed. Furthermore, we conducted three types of model experiments, Results agree with the theoretical critical conditions qualitatively.
Resumo:
Descreve o atual panorama normativo para as cotas raciais no Brasil. Os resultados indicaram que a ausência de uma norma federal implicou na baixa adesão ao sistema de cotas, o que é ratificado pelo insignificante número de Instituições Públicas de Ensino Superior - IPES que adotaram norma de cota racial - apenas 17,79%. Verificou-se, ainda, que essa ausência cria lacunas na adoção de diretrizes nacionais para a interpretação e a compreensão das ações afirmativas. Tais lacunas refletem diretamente no ciclo da política pública, comprometendo a avaliação e o acompanhamento da efetividade e do sucesso da política, o que é extremamente perigoso para a segurança jurídica na área de direitos humanos e para a garantia da equidade de fato nos espaços político, econômico e sociais.
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从小波分解出发,利用多尺度分解对控地雷达波进行分析,并基于MATLAB的小波分析对深圳市公安局某工地强夯土石墩地基的检测结果进行处理,提出了具体的处理方法。
Resumo:
[Es] La teoría creacionista, universalmente en vigor antes de Darwin (y aún hoy sostenida por más de uno) sostenía que había habido una mente (divina), encargada de diseñar al hombre; que le puso ojos para que viera, oídos, mente para que pensara...Desde Darwin, por el contrario, se opina que la necesidad de enfrentarse a problemas diversos hizo que la mente fuera diversificándose, a través de sucesivas selecciones de las mentes más adaptativas. Según esto: 1.-¿Existen maquinarias biológicas “especializadas” en nuestro cerebro?. Y si existieran, 2.-¿Se desarrollan de forma espontánea?; es decir, sin esfuerzo ni instrucción formal? 3.-¿Se despliegan de forma inconsciente, autónoma y similar en todos los seres humanos? En definitiva: ¿Existe algo (facultad psicológica, órgano mental, sistema neurológico, módulo computacional…) que permita decir que las personas saben esto… o aquello… en el mismo sentido que las arañas saben tejer o los pájaros construir sus nidos?
Resumo:
I. Scientific Issues Posed by OECOS II. Participant Contributions to the OECOS Workshop A. ASPECTS OF PHYTOPLANKTON ECOLOGY IN THE SUBARCTIC PACIFIC Microbial community compositions by Karen E. Selph Subarctic Pacific lower trophic interactions: Production-based grazing rates and grazing-corrected production rates by Nicholas Welschmeyer Phytoplankton bloom dynamics and their physiological status in the western subarctic Pacific by Ken Furuya Temporal and spatial variability of phytoplankton biomass and productivity in the northwestern Pacific by Sei-ichi Saitoh, Suguru Okamoto, Hiroki Takemura and Kosei Sasaoka The use of molecular indicators of phytoplankton iron limitation by Deana Erdner B. IRON CONCENTRATION AND CHEMICAL SPECIATION Iron measurements during OECOS by Zanna Chase and Jay Cullen 25 The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma C. PHYSICAL OCEANOGRAPHY, FINE-SCALE DISTRIBUTION PATTERNS AND AUTONOMOUS DRIFTERS The use of drifters in Lagrangian experiments: Positives, negatives and what can really be measured by Peter Strutton The interaction between plankton distribution patterns and vertical and horizontal physical processes in the eastern subarctic North Pacific by Timothy J. Cowles D. MICROZOOPLANKTON Microzooplankton processes in oceanic waters of the eastern subarctic Pacific: Project OECOS by Suzanne Strom Functional role of microzooplankton in the pelagic marine ecosystem during phytoplankton blooms in the western subarctic Pacific by Takashi Ota and Akiyoshi Shinada E. MESOZOOPLANKTON Vertical zonation of mesozooplankton, and its variability in response to food availability, density stratification, and turbulence by David L. Mackas and Moira Galbraith Marine ecosystem characteristics and seasonal abundance of dominant calanoid copepods in the Oyashio region by Atsushi Yamaguchi, Tsutomu Ikeda and Naonobu Shiga OECOS: Proposed mesozooplankton research in the Oyashio region, western subarctic Pacific by Tsutomu Ikeda Some background on Neocalanus feeding by Michael Dagg Size and growth of interzonally migrating copepods by Charles B. Miller Growth of large interzonal migrating copepods by Toru Kobari F. MODELING Ecosystem and population dynamics modeling by Harold P. Batchelder III. Reports from Workshop Breakout Groups A. PHYSICAL AND CHEMICAL ASPECTS WITH EMPHASIS ON IRON AND IRON SPECIATION B. PHYTOPLANKTON/MICROZOOPLANKTON STUDIES C. MESOZOOPLANKTON STUDIES IV. Issues arising during the workshop A. PHYTOPLANKTON STOCK VARIATIONS IN HNLC SYSTEMS AND TROPHIC CASCADES IN THE NANO AND MICRO REGIMES B. DIFFERENCES BETWEEN EAST AND WEST IN SITE SELECTION FOR OECOS TIME SERIES C. TIMING OF OECOS EXPEDITIONS D. CHARACTERIZATION OF PHYSICAL OCEANOGRAPHY V. Concluding Remarks VI. References (109 page document)
Resumo:
在线性压电本构方程框架下,用复势函数方法对椭圆切口模型进行了精确的数值计算。完整地考虑了各向异性力电耦合效应以及切口内不同电介质的介电性质。给出了切口内部不同介电性质对压电材料内部应力的影响。指出了Sosa文章里的一些计算错误。由于现在文献中很小有关于电导通边界条件政府解的数值结果,所以本文同时提供了不同电边界条件下的理论解的数值结果。最后通过最小势能原理建立了8结点有限元模型,对椭圆切口问题进行了计算并与理论解进行了仔细比较。
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O Diario..., como observa Borba de Moraes, "apresenta um roteiro muito resumido, mas muito exato" e, como diz Sacramento Blake, "atendendo ao que é escrito em viagem, e viagem de 648 léguas de terras invias e inexploradas. É, entretanto, trabalho de grande valor para a geografia dos lugares percorridos." O Diario... foi reeditado pelo Instituto Nacional do Livro em 1944.