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。     

C化学位移特点研究

由诺卜醇和丙酸酐合成了丙酸诺卜酯，用MS，IR，^1HNMR及^13CNMR分析进行了结构表征，利用^13C化学位移分析出其构象是：C-1-C-2-C-3-C-4-C-5部分处于同一平面，整个6，6-二甲基双环[3.1.1]庚-2-烯部分呈“Y”形。丙酸诺卜酯可以看成是阿朴蒎烯在C-2发生取代的衍生物，取代基对^13C化学位移的影响主要集中在C-2，C-1和C-3，对其它碳原子的影响比较小。     

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。     

基于充油流量与曝气程度的拖拉机动力换向性能研究

围绕拖拉机动力换向离合器充油流量易受温度、回位弹簧刚度和预紧力等因素影响,液压油在加注及工作过程中易受空气污染,导致液压油空气含量增加的工程应用问题,探究了不同充油流量及曝气程度对动力换向性能的影响。以换向时间、冲击度、滑摩功和磨损量为评价指标对换向性能进行了评估,以期提高拖拉机动力换向品质、工作效率和传动系使用寿命。以东方红LF2204型拖拉机TX4A传动系为研究对象,建立了考虑充油流量和曝气程度的动力换向过程数学模型,基于ADAMS、Matlab/Simulink和AMESim平台分别建立了换向离合器机械模型、控制模型和液压模型,对拖拉机Ⅰ挡作业时前进挡切换为倒退挡的工况进行了仿真分析与台架试验验证。仿真结果表明：当液压油曝气程度为0.1%,充油流量分别为16、14 L/min时,与20 L/min流量相比,换向时间分别增长20%和43%,变速器最小输出转矩分别下降26%和52%,滑摩功分别上升33%和78%,最大冲击度分别下降11%和18%,最大磨损量分别上升24%和44%。当充油流量为20 L/min,曝气程度分别为1%和5%时,与0.1%曝气程度相比,换向时间分别增长26%和...     

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。     

国内外拖网减少副渔获物的研究进展

拖网渔业的兼捕是一个世界性难题,每年因兼捕而产生的渔获物抛弃对渔业资源的持续发展产生较大影响。目前世界各国针对本国拖网渔业的特点、主捕对象开展了卓有成效的选择性研究,并取得了较为理想的效果。但在推广及应用过程中反映出较多的实际问题,有待进一步完善、提高。笔者综合了国内外在开展拖网渔具选择性研究中具有代表性的成功经验,表明单纯的网囊网目很难对副渔获复杂的拖网产生理想的选择效果;选择性装置及其与网片的组合是解决拖网渔具兼捕的有效手段之一。     

海南“石斑鱼苗网”渔具属性辨析

对在2004年7~8月间南海区小型海洋渔具渔法调查中发现的“石斑鱼苗网”的渔具结构、属性、性能和管理进行了分析讨论,研究认为“石斑鱼苗网”属于敷网类,网团型,延绳式。对石斑鱼苗有良好的诱捕效果,从保护资源的角度出发,应对其实施规范管理。     

From small-scale habitat loopholes to decadal cycles: a habitat-based hypothesis explaining fluctuation in pelagic fish populations off Peru

The Peru‐Humboldt Current system (HCS) supports the world's largest pelagic fisheries. Among the world's eastern boundary current systems, it is the most exposed to high climatic stress and is directly affected by El Niño and La Niña events. In this volatile ecosystem, fish have been led to develop adaptive strategies in space and time. In this paper, we attempt to understand the mechanisms underlying such strategies, focusing on the El Niño 1997–98 in Peru from which an extensive set of hydrographic, capture and acoustic survey data are available. An integrated analysis of the data is crucial, as each has substantial shortcomings individually; for example, both catch data and acoustic surveys may easily lead to wrong conclusions. Existing hypotheses on anchovy and sardine alternations lead us to a ‘habitat‐based’ synthetic hypothesis. Using our data, an integrated approach evaluated how fish responded to habitat variation, and determined the consequences in terms of fish‐population variability. Various factors occurring at a range of different spatio‐temporal scales were considered: interdecadal regime (warm ‘El Viejo’/cool ‘La Vieja’ decadal scale); strength and the duration of the El Niño Southern Oscillation event (interannual scale); population condition before the event (interannual scale); fishing pressure and other predation (annual scale); changes in reproductive behaviour (intra‐annual scale); presence of local upwelling (local scale). During El Niño 1997–98, anchovy was able to exploit a small‐scale temporal and spatial ‘loophole’ inside the general unfavourable conditions. Moreover, sardine did not do better than anchovy during this El Niño and was not able to take advantage of the ‘loophole’ opened by this short‐term event. Our results question the traditional view that El Niño is bad for anchovy and good for sardine.     

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.