用于吸力式基础离心机模拟的动力加载设备(英文)

吸力式桶形基础广泛地应用于海洋油气开发的海洋平台。在冬季,渤海冰排会对平台产生强烈的冲击,引起振动。本文介绍了一套用于土工离心机实验的动力加载设备,并介绍了该套设备在模拟吸力式桶形基础在受到等效动冰载作用下的响应的实验研究情况及实验结果。结果表明,当载荷幅值超过一个临界值时,地基上部会发生软化甚至液化。超孔隙水压从土体上部到下部,从桶形基础壁面到远处逐渐减小。在动载荷作用下,桶形基础和临近土体会发生大的沉降。桶形基础尺寸越小,动载荷响应越大。

Preliminary guide to the identification of the early life history stages of Priacanthid fishes of the Western Central Atlantic

The family Priacanthidae contains four genera and four species that occur in the western central North Atlantic (Starnes, 1988). Pristigenys alta is distributed in the Caribbean, Gulf of Mexico and along the east coast of North America. Although juveniles have been reported from as far north as southern New England waters, adults are not reported north of Cape Hatteras, NC. Priacanthus arenatus is distributed in tropical and tropically influenced areas of the western central North Atlantic in insular and continental shelf waters. Adult P. arenatus are distributed north to North Carolina and Bermuda, juveniles have been collected as far north as Nova Scotia. Cookeolus japonicus and Heteropriacanthus cruentatus are circumglobally distributed species and are both common in insular habitats. In the western central North Atlantic, C. japonicus ranges from New Jersey to Argentina; H. cruentatus from New Jersey and northern Gulf of Mexico to southern Brazil (Starnes, 1988). (PDF contains 6 pages)

Collecção das Leis da República dos Estados Unidos do Brazil de 1916

Parte 1 - Atos do Poder Legislativo.

Estimates of the rates of shedding of dart tags from yellowfin tuna

ENGLISH: Return data for single-tagged fish and for double-tagged fish which had retained one or both tags were used to estimate the rates of shedding of dart tags from yellowfin tuna. The Type-1 shedding, which occurs immediately after release of the fish, is about 10 percent. The Type-2 shedding is assumed to be constant throughout the life of the fish after tagging; it occurs at an instantaneous rate of about 0.278 per year. SPANISH: Se emplearon los datos de retorno de peces marcados con una sola marca y de peces marcados con doble marca los cuales han retenido una o dos marcas para estimar las tasas de pérdida de las marcas de dardo de atunes aleta amarilla. El Tipo-l de pérdida, que ocurre inmediatamente después de haber liberado el pez, es aproximadamente del 10 por ciento. El Tipo-2 de pérdida se supone que sea constante durante la vida del pez después de marcado; ocurre en una tasa instantánea cerca de 0.278 por año. (PDF contains 24 pages.)

Commercial cage fish culture

With increasing emphasis in Nigeria on aquaculture as an alternative to dwindling artisanal fishing and scarce foreign exchange for fish import, cage fish culture, is a more profitable aquaculture practice than pond culture. It appears to be one of the most viable business ventures with minimum risks. It is a highly recommendable project

Synthesis Of Plastic Zr-Based Bulk Metallic Glass Matrix Composites By The Copper-Mould Suction Casting And The Bridgman Solidification

Zr-based bulk metallic glass matrix composites with the composition of Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6Be12.(5) were synthesized by the copper-mould suction casting and the Bridgman solidification. The composite, containing a well-developed flowery beta-Zr dendritic phase, was obtained by the Bridgman solidification with the withdrawal velocity of 0.8 mm/s and the temperature gradient of 45 K/mm, and the ultimate strength of 2050 MPa and fracture plastic strain of 14.6% of the composite were achieved, which was mainly interpreted by the homogeneous dispersion of bcc beta-Zr phase in the glass matrix. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.

Nonlinear X-wave formation and conical emission at different powers of a femtosecond laser pulse in water

Nonlinear X-wave formation at different pulse powers in water is simulated using the standard model of nonlinear Schrodinger equation (NLSE). It is shown that in near field X-shape originally emerges from the interplay between radial diffraction and optical Kerr effect. At relatively low power group-velocity dispersion (GVD) arrests the collapse and leads to pulse splitting on axis. With high enough power, multi-photon ionization (NIPI) and multi-photon absorption (MPA) play great importance in arresting the collapse. The tailing part of pulse is first defocused by MPI and then refocuses. Pulse splitting on axis is a manifestation of this process. Double X-wave forms when the split sub-pulses are self-focusing. In the far field, the character of the central X structure of conical emission (CE) is directly related to the single or double X-shape in the near field. (c) 2007 Elsevier B.V. All rights reserved.

Fluorescent Ag nanoclusters in glass induced by an infrared femtosecond laser

We report a method for the selective introduction of fluorescent Ag nanoclusters in glass. Extinction and photoluminescence spectra show that a fraction of the Ag atoms are generated through femtosecond laser induced multiphoton reduction and then aggregate to form Ag nanoclusters after heat treatment. Red luminescence from the irradiated region is observed under blue or green laser excitation. The fluorescence can be attributed to interband transitions within Ag nanoclusters. This method provides a novel route to fabricate fluorescent nanomaterials in 3D transparent materials. (c) 2007 Elsevier B.V. All rights reserved.

提高能量密度的超衍射极限激光光束相位补偿技术

定义了激光光束衍射远场光斑压缩前后的能量比以及能量密度比来衡量超衍射极限激光光束的质量。通过利用反向传递算法设计了合适的补偿相位板，不但对准直放大的单一横模激光光束进行小于光学衍射极限的发散度的压缩，同时又保证光束能量集中于压缩后的远场衍射主瓣中，使压缩后的远场衍射光斑的能量密度增加。给出了相应的实例。这一结论不但解决了光学超分辨中光束压缩与能量损失不可避免这一矛盾，而且为发散度小且能量密度高的超衍射极限激光光束的实验工作以及该类光束的实际应用提供了理论基础。

Exámenes resueltos de matemáticas para economistas IV

Matemáticas para Economistas IV es una asignatura cuatrimestral dedicada fundamentalmente a la optimización con convexidad que se ha impartido en los últimos años en el segundo curso de la licenciatura de Economía en la Facultad de Ciencias Económicas y Empresariales de la Universidad del País Vasco. Esta publicación recoge problemas planteados en los exámenes de esta asignatura desde el año 2000 al 2009, en las convocatorias de junio y septiembre.