Influence of shelf-break fronts on shellfish and fish stocks off Argentina [Contribution to ICES Annual Science Conference, Reykjavik, Iceland, 27 Sep- 04 Oct 1996]

The general circulation pattern in the western boundary of the SW Atlantic is dominated by the opposite flows of Malvinas (-Falkland)and Brazil Current. In the Confluence region both currents separate from the continental slope and flow offshore creating an area of strong contracts and complex dynamics. The shelf-break fronts off Argentina mark the transition between shelf waters of mixed origin and nutrient rich Malvinas waters. Two areas deserve special attention due to the steep gradients introduced by the outflow of important sources of continental waters: the Rio de la Plata and the Magellan Strait to the north and south of the study area. Characteristics of the front is the high primary and secondary production, and the presence of important invertebrate and fish stocks that concentrate along the front to feed or spawn. The area comprises nearly 30 o/o (333 million U$S in 1995)of all Argentine catches of fish and squid. Resources in the area, beyond the EEZ limits, support international fisheries mainly of Russia, Poland and Spain. (Document contains 15 pages & figs)

等效动冰载下桶形基础的响应

对饱和砂土地基上等效动冰载下桶形基础的响应进行了实验研究。考察了均匀土层情况下的变形和影响区域,对承载特性进行了分析。结果表明,由于动冰载的作用,桶基周围土体逐渐软化甚至液化,土体强度降低,桶逐渐下沉,桶周围影响逐渐扩大,但是变形和影响区的发展逐渐达到一个稳定状态。该稳定状态可以作为工程设计时的一个重要参考。

深海平台分析和设计中的关键力学问题

深海采油平台与传统的导管架平台有很大不同,主要体现在动力响应、主要结构件形式、主要结构块之间的连接方法和分析方法方面.文章对深海平台的上述特点作了评述.,并根据初步的数值分析结果指出:现有的商业软件并不能完全解决深海平台设计中的问题,其中还有很多需要深入研究的内容.

重庆西山坪西园建材厂滑坡应急抢险治理工程设计与研究

以西山坪西园建材厂滑坡体工程地质勘察资料为依据,分析了滑坡体的岩土组成和物理力学性质以及造成滑坡的原因.认为影响山体滑坡的因素除与边坡地层岩性、微地貌特征、气象及水文条件有关外,修建厂房开挖与切割边坡坡脚则是重要的诱发原因.定性得出该滑坡的形成机制和类型为牵引式、浅层、小型土质新型滑坡.在此基础上,应用规范所推荐的极限平衡法,对该滑坡体的3个主要地质剖面(A-A'、B-B'、C-C')进行了稳定性计算与分析,得到不同工况下滑坡体稳定系数值.其中,在最不利组合工况(自重+暴雨+地震)下,滑坡体稳定系数仅为0.99～1.03,处于不稳定状态.根据计算结果,按照<长江三峡库区滑坡灾害防治规范>要求及"技术可行、安全可靠、经济合理、简单易实施"的设计原则,对该滑坡的应急抢险方案进行了设计,提出以抗滑桩拦挡工程为主、坡顶修筑截排水沟、地表裂缝回填夯实等综合治理方案.抗滑桩设置1排,分3段,根据每段不同的剩余下滑力设计抗滑桩的断面尺寸和埋设深度,使该滑坡体治理后,其安全系数分别满足不同工况下的规范要求.该方案已通过了三峡库区滑坡灾害防治专家组的审核,目前,正处于实施阶段.

柱形容器开口泄爆过程中的火焰传播特性

泄爆过程中流动与燃烧的相互作用机制是研究开口泄爆问题的关键.对柱形容器泄爆过程中压力与火焰发展传播过程的观测与分析表明,不同泄爆条件下压力与火焰的发展传播具有明显特点.泄爆诱导流动通过加速火焰传播、加剧火焰变形、增大火焰面积对容器内燃烧产生增强作用,泄爆流动大小主要由泄爆面积决定.小口中低压泄爆过程压力与火焰的发展过程与封闭燃烧中类似;小口高压以及大口泄爆过程中,火焰变形剧烈,传播速度明显上升,并导致压力的回升.

亚微米氮化钛膜的纳米压痕和划痕测定

采用等离子电弧沉积的方法，分别在GT35和40CrNiMo钢上沉积厚约为0.5μm的氮化钛(TiN)膜。为了筛选基材，采用纳米压痕和划痕技术，评价膜基界面结合和固体润滑效果。纳米压痕结果，GT35，40CrNiMo和TiN的纳米硬度/弹性模量的典型值分别约为11.5 GPa/330GPa, 6.0 GPa/210GPa, 30GPa/450GPa。纳米划痕结果，GT35有较理想的膜基结合能力；GT35，40CrNiMo，TiN及其有机膜的磨擦系数分别约为0.25，0.45，0.15, 0.10。同40CrNiMo相比，GT35是较为理想的基体材料。纳米压痕和划痕技术能提供丰富的近表面的弹塑性变形、断裂和磨擦等的信息，是评价亚微米薄膜力学性能的有效手段。

稠油输送新工艺方法探索及现场试验

本文介绍一种可应用于高粘度稠油管输的新工艺。即用自行研制的蒸汽引射器采用无界引射方式，将蒸汽直接注入到输油管道中，利用蒸汽释放的热量提高稠油温度降低粘度，从而达到降低稠油输送压降的目的，它比间接加热输送工艺所用的蒸汽量或耗煤量大大减少。本方法在辽河油田输油管线上进行了工业现场试验，取得了很好的效果。

油水分离技术研究之一——直管和螺旋管的数值模拟

　本文采用数值模拟的方法研究油水混合物在直管和螺旋管中的流动状况。计算采用Euler Euler法和Euler模型:支配油水分离两相流动的基本方程包括连续方程和动量方程,湍流模型采用多相流中混合型k ε模式,基本方程的离散和求解采用SIMPLE算法。利用Fluent软件,以直管和螺旋管为例进行了计算,获得了初步计算结果。计算表明,本文所用方法可以较好地模拟直管中油水在重力作用下的分离,以及螺旋分离器中油水在重力和离心力共同作用下的分离现象。并可为实验研究提供参考。

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。

圆柱振荡绕流的三维不稳定性研究

通过数值求解三维不可压缩Navier-Stokes方程，研究了振荡圆柱绕流的旋涡不稳定性。研究表明，在一定的参数范围内，由于旋涡不稳定性，振荡流出由二维演化成三维流动，并沿圆柱轴向形成交错排列的三维涡结构。数值计算合理地预测了三维涡结构的空间失稳波长，并与实验测试值相符很好。文中还进一步研究了圆柱的受力特性，通过求解Morison方程，计算了圆柱的阻力和惯性力特性，其计算结果与已有的实验数据相吻合。

Relatório apresentado a S. Ex. o Sr. Ministro da Industria, Viação e Obras Públicas =Rapport présenté a Son Ex. M. le Ministre de l'Industrie, de la Voirie et des Travaux Publics /por L. Cruls. --Relatório da Comissão Exploradora do Planalto Central do Brazil = Rapport de la Commission d'Exploration du Plateau Central du Brésil

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

Contact pressure of porous Al2O3 probed by nanoindentations

Contact pressure of porous Al2O3 probed by nanoindentation was investigated by dimensional analysis with special attention paid to scaling effects in the mechanical behavior. It was found that, for sample containing small grains and interconnected pores, the contact pressure is manifest dominated by bonding strength of the porous alumina. Whereas the samples with coarse grain and various porous structures exhibit higher contact pressures and smaller residual deformations, which can be attributed to the mechanical response of the solid-phase under current limited peak loads.

Failure process analysis of cement under explosive loading with a generalized driven nonlinear threshold model

The microstructural heterogeneity and stress fluctuation play important roles in the failure process of brittle materials. In this paper, a generalized driven nonlinear threshold model with stress fluctuation is presented to study the effects of microstructural heterogeneity on continuum damage evolution. As an illustration, the failure process of cement material under explosive loading is analyzed using the model. The result agrees well with the experimental one, which proves the efficiency of the model.

Elastic and statistically brittle (ESB) model, damage localization and catastrophic rupture

In this paper, an elastic and statistically brittle (ESB) model is applied to the process of damage evolution induced catastrophic rupture and the influence of localization and softening on catastrophic rupture is discussed. According to the analysis, the uncertainty of catastrophic rupture should be attributed to the unknown scale of localized zone. Based on the elastic and statistically brittle model but local mean field approximation, the relation between the scale of localized zone and catastrophic rupture is obtained and then justified with experiments. These results can not only give a deeper understanding of the mechanism governing catastrophic rupture, but also provide a possible tool to foresee the occurrence of catastrophic rupture.