基于Pro/E与ADAMS蜗轮蜗杆传动仿真研究

论述了基于Pro/E与ADAMS的蜗轮蜗杆设计及动态仿真的方法和过程,介绍了Parasolid文件接口的使用以及ADAMS齿轮副中啮合点的创建方法,对仿真结果和理论计算结果进行了对比.     

轮系分析系统化的研究

本文提出了一种轮系分析的系统化方法。这种方法以轮系组成机构符号为基础,直接构造出轮系分析的数学模型,利用现有的计算机程序进行处理。它不仅能处理各种不同轮系的分析问题,还能将同一轮系不同分析问题(如运动学问题,动力学问题和功率问题)的求解一体化、程序化,可作为轮系CAD的基础。     

减速器齿轮硬齿面微量对研的试验研究

通过对减速器齿轮硬齿面微量对研的试验研究，得出了可靠试验数据，为提高齿轮的接触精度提供了依据。     

巴蛸拖网捕捞技术研究

为合理开发利用巴蛸资源，为29．4～58．8kW渔船巴蛸拖网进行了改进设计，改成低口、长袖的结构形式，并配置驱赶铁链。与原拖网对比试验结果表明，新型巴蛸拖网比原底拖网增产巴蛸60％以上，增加产量50％以上，同时对传统经济鱼虾类有一定保护作用。     

A method for calculating numerical estimates of gear selectivity curve

The present paper proposes a method for estimating the numerical curve of gear selectivity without the assumption of function of selectivity curve and estimating confidence intervals, using data of catch per unit effort at length for several nets of different mesh sizes obtained from fishing experiments. The paper assumes such geometric similarity as the selectivity is the same if the rate of fish length to mesh size is the same. The basic idea is due to a technique of numerical integration that uses the derivatives at various points. The natural logarithm of selectivity is expressed by an approximation equation using its cumulated derivatives. The values of derivatives at various lengths are calculated from the data. The confidence intervals are made from the bootstrap samples. The method was applied to the data of catch at length by mesh size of gill net for pink salmon Oncorhynchus gorbuscha . Data collection, modification and issues of the method are discussed.     

Keeping watch on the unwatchable: technological solutions for the problems generated by ecosystem-based management

Ecosystem‐based management is an emerging paradigm influencing the management of commercial fisheries. Increasingly, developed nations are adopting explicit legislation and policy governing the assessment and management of their fisheries against criteria of ecological sustainability. Yet the ability to evaluate ecosystem impacts of fisheries is compromised by a general lack of understanding of marine ecosystem function (beyond the population level) and a lack of robust and practical indicators for ecosystem health and management. Recent technological advances can assist in developing criteria, including structural analyses of seafloor communities potentially impacted by fishing gears (e.g. demersal trawling). Similarly, advances in fishing gear technology, including improved selectivity and the development of gears which have a more benign environmental impact, can mitigate some of the ecological impacts of fishing. Such technological advances are summarized in the context of contemporary fisheries management.     

Comparative analysis of ichthyoplankton sampling gear for early life stages of walleye pollock (Theragra chalcogramma)

Comparative gear tows were conducted during the summers of 1987–1990 in the Gulf of Alaska. Efficiencies of four types of ichthyoplankton sampling gear were compared with respect to total catch and size distribution of larval fish. Fish were sampled using the bongo net (333 and 505 μm mesh), 1 m Tucker net, 3 m Tucker net and the Methot frame net. Results indicate that the bongo and the 1 m Tucker nets caught similar numbers and size distribution of fish. The larger 3 m Tucker and Method frame nets caught a larger size class of fish but a smaller total catch. Although there was a slightly significant diel difference in total catch detected in the smaller nets, no diel differences in size distribution of fish caught were detected for any of the nets.     

环境友好型虾夷扇贝捕捞网具优化设计与试验

目前中国虾夷扇贝网具存在捕捞效果差、海底生境影响严重等问题,该研究基于水下视频监控技术,设计了水压板导流与随动式惊扰相结合的拖曳网架结构。采用FLUENT软件对改造后捕捞网具的水下拖曳水动力特性进行分析得出,在拖曳水深在30~50 m、拖曳速度为1.8 m/s、网口高度为350 mm时,采用22.5°～30°负迎角弧式水压板,可减轻顶部湍流对底栖鱼类的兼捕影响,且随动式惊扰装置满足作业要求,此时拖曳稳定绳长约为156.80～261.34 m、稳定角度为11.03°、稳定拖曳力为2275.83 N。通过海上捕捞对比试验得出,在拖曳速度为1.5、1.8和2.0 m/s时,改造后捕捞网具与生产用捕捞网具在捕捞量方面无显著差异（P>0.5）,在碎贝量和底栖鱼类兼捕量方面显著降低（P<0.5）。单网平均捕捞量的偏差率分别为6.30%、0.59%和5.55%,单网平均碎贝量的偏差率分别为90.63%、84.78%、85.29%,单网底栖鱼类平均兼捕量的偏差率分别为78.57%、81.25%、84.85%。且在拖曳速度为1.8 m/s时,与生产用网具相比,单网平均捕捞量偏差率最低,单网平均碎贝量的偏差率最低,底栖鱼类平均兼捕量显著减少,符合环境友好型捕捞网具设计要求。     

螺旋伞齿轮精锻工艺及发展趋势的研究

当前,代表各国机械制造发展程度的是齿轮精锻工艺的水平,提升锻造工艺水平可以促进中国机械工业更好更快发展,从而减少与世界顶尖技术的距离。并且能够更大程度上减少对资源的消耗和材料的浪费,给机械工业减少成本的消耗。因而文章从我国螺旋齿轮精锻研究概况、及其所面临的问题以及研究方法等几方面入手研究螺旋伞齿轮的精锻工艺,并且展望了该技术的未来趋势。     

双联齿轮的毛坯件制造分析

双联齿轮就是两个齿轮连成一体,这种双联齿轮在轮系中(变速器)被称为滑移齿轮,一般用于变速箱中主要起换档调速作用。双联齿轮本身的制造精度,对整个机器的工作性能、承载能力及使用寿命都有很大的影响。文章研究双联齿轮加工毛坯件的制造形式。