机舱底层大型单元的吊装工艺优化

本文主要分析传统机舱底层单元吊装存在的不足,并由此探讨VLCC、VLOC舱机舱底层大型单元的吊装工艺优化方法,以解决单元吊装的变形问题。     

激光拼焊板制复杂件的成型模拟及拉深筋优化研究

分析了拉深筋的设置对激光拼焊板成型时焊缝移动的影响。针对某轿车前纵梁加强板的拉深成型进行了数值模拟分析,并根据模拟分析结果预测了拼焊板在成型过程中材料的流动趋势,对该零件成型时的拉深筋高度及其布置进行了优化。结果表明,拉深筋优化后有效地控制了拼焊板焊缝两侧材料的流动,进而提高了冲压件质量。     

On the performance of rheological shock absorber models in full vehicle simulation

A comparative study of the performance of three rheological automotive shock absorber models as well as of an extended force-velocity relation in full vehicle simulation is performed. Simulation results for both the shock absorber test rig and a full vehicle crossing a single obstacle are compared with measured data. While the gain of accuracy by the extended force-velocity relation is marginal, the rheological models in general yield a noticeable improvement, which, however, in full vehicle simulation is less significant than in test rig simulation. Among the rheological models studied here, the one consisting of a nonlinear spring-dashpot element with an element modelling friction by a continuous transition from the compression to the extension range in parallel and a quadratic approximation of the static gas force exhibits the best global performance.     

非对称小净距隧道施工力学特性研究及方案优化

非对称小净距隧道合理的开挖顺序对隧道围岩稳定和支护措施优化有很大的影响。文章结合净距2.0 m非对称公路隧道工程实践,通过二维弹塑性有限元数值仿真模拟,研究分析了隧道开挖顺序对支护力学行为特性及围岩稳定性的影响,得出了先开挖较小断面隧道优于先开挖较大断面隧道的结论,为非对称小净距隧道优化设计和施工提供了科学依据。     

Numerical modelling of fish eggs dispersion at the Patos Lagoon estuary — Brazil

The Patos Lagoon estuary is the most important nursery ground for commercially relevant species of fish and crustaceans in the South of Brazil, maintaining fisheries that sustain 3500 fisher families throughout the Rio Grande do Sul State coastline. Around 80% of the interior estuarine area is very shallow (< 2 m), and recruitment of fish eggs and larvae to the inner parts of the Patos Lagoon estuary is directly related to the circulation pattern in the area, which is controlled by local and non-local wind effects and freshwater discharge. The objective of this study is to investigate the processes controlling the transport of estuarine dependent fish eggs between the Atlantic Ocean and the Patos Lagoon estuary.An integrated numerical system based on a bi-dimensional hydrodynamic model and a Lagrangean transport model of passive particles is applied to a selection of scenarios representing the passage of weather fronts over the area. At this stage, fish eggs are represented as buoyant passive particles. Modelling results are compared against field data for the period under investigation (September/October 1999) and historical records. Short term results are analysed in terms of the meteorological conditions (wind direction, intensity and duration) controlling the transport of eggs to the inner parts of the estuary and the extension of their excursion. This experiment is the first attempt to couple biological and physical information to study fish eggs transport, and to enhance the current knowledge about recruitment of important fisheries resources in southern Brazil.     

基于遗传算法的机车二系支承载荷调整优化方法

为了改善机车轮轴重量分配的均匀性,从分析机车二系支承结构出发,建立二系载荷分布弹簧高度调整模型,提出应用遗传算法实现机车二系支承点加垫高度值的快速优化计算。针对机车二系支承载荷分布多维参数优化问题的特点,给出基于实数编码的改进遗传算法模型。对国产SS9,SS3b型机车实际应用,可使二系支承载荷分布最大误差进一步减小8%～15%,平均计算过程时间减少约20%。结果表明这种方法克服了基于误差梯度信息迭代搜索求解支承点加垫最佳值算法的不足,在获得一致的全局优化(近似)解,以及在减小运算时间、提高调簧算法的可靠性和实时性等方面具有明显的效果。     

空间多万向节传动布置的优化设计

本文从控制振源降低万向节传动引起的传动系与整车振动噪声出发,提出了空间多万向节传动最优布置的数学模型,选择了适用的优化算法,编出了相应的程序。实例计算表明,所提优化设计方法实用、可行,具有足够精度,所编程序计算速度快,使用方便,便于推广。     

CA4DC1柴油机配气机构设计

CA4DC1型柴油机是在CA498柴油机基础上开发的能够满足欧Ⅲ排放法规要求的柴油机.介绍了该柴油机在配气机构总体布置、气门组零件设计、气门传动机构设计、凸轮型线设计等方面所作的改进.     

船舶抗沉计算与决策模型研究

船舶抗沉计算和决策是及时、准确地进行损管行动的基础。依据不沉性理论、数值分析、专家系统和多目标决策理论,建立了船舶的抗沉计算模型和抗沉方案优选决策模型,并以某型船舶为实例进行了数值仿真,结果表明了模型的可行性和有效性。     

The analysis of travel and emission impacts of travel demand management strategies using activity-based models

This paper demonstrates, tests and shows the value of activity-based travel demand models and household sample enumeration forecasting techniques in evaluating the transportation and air quality impacts of travel demand management strategies. Using data from the Portland, Oregon metropolitan area, three transportation policies were evaluated both individually and in combination: transit improvements, pricing, and telecommunications. The activity-based models used in this testing represents a significant improvement to today's "four-step" sequential model systems by providing a deeper insight into the individual decision making process in response to transportation policies. A wider range of impacts is predicted, and indirect effects as well as synergistic effects of such policies are taken into consideration. These models are capable of providing the information needed to improve the linkage of transportation models with emissions and air quality analysis methodologies by improving the prediction of variables that are important to accurately estimating emissions and air quality impacts of transportation actions.