钢板弹簧抓取机械手运动仿真

以钢板弹簧抓取机械手为例,介绍了利用Solidworks下的插件An imator实现机械手运动仿真的有效方法,重点分析了An imator下精确位置控制的实现,为设计和控制机械手提供了参数依据,并使机械手的性能演示更加直观。     

Epidemiological and genetical studies in Norwegian pig herds. IV. Breed effects, recurrence of disease, and relationship between disease and some performance traits

Individual health records collected from 1984 to 1986 in 70 swine-herds in the south-eastern part of Norway were analysed by epidemiological methods. The incidence rate for most of the reported diseases was less than 1% per farrowing, and a majority of disease recordings concerned 6 frequently-occurring conditions. The incidence of several diseases was lower in crossbred sows compared to purebred Norwegian landrace sows. The risk of most diseases increased in sows that had been ill previously, and also in litters from sows that had previously had diseased litters. Disease risk in piglets also increased if the sow became ill during the first few days after farrowing. The reduced performance associated with most of the common diseases impacts adversely on economic returns.     

基于SolidWorks的浮动仿形机构设计与试验

针对牧草收获过程中集拢成条时花叶损失多、对土地破坏大的问题,设计研制出一种左右对称布置浮动仿形机构的牧草捡拾集条机。利用SolidWorks软件建立了浮动仿形机构的三维模型,通过Motion插件对浮动仿形机构进行运动学模拟仿真,以浮动仿形机构上的浮动弹簧为主要研究对象,获取了浮动弹簧作用力、浮动弹簧位移的变化规律。为考察样机的作业性能指标,对样机进行了田间试验,将样机的相关技术指标进行测定。运动学模拟仿真与田间试验结果表明:浮动仿形机构满足设计要求,可保证整机具备良好的田间通过性,牧草捡拾集条机相关技术指标达到标准及设计任务书要求,工作性能稳定可靠。     

A method for estimating the extent of standing fresh waters of different trophic states in Great Britain

1. The total area of standing fresh water in Great Britain has been estimated at approximately 2400 km². The aim of the work described in this paper was to estimate the extent of the dystrophic, oligotrophic, mesotrophic and eutrophic habitat types making up this total. 2. Botanical survey data collected by the statutory nature conservation agencies provided habitat type and surface area for 3500 water bodies, mostly in Scotland. Because survey in England and Wales had been less thorough than in Scotland, it was not possible to estimate the areas of habitat types simply by direct extrapolation from the survey sample to the total resource of standing water in Great Britain. 3. A system of Trophic Ranking Scores (TRS) has been developed for aquatic plant species. Using plant records from the Biological Records Centre, a mean TRS for each 10×10 km square was produced, and Great Britain was divided into TRS bands. For each of these bands, the percentage by surveyed area of each freshwater habitat type was calculated. These percentages were applied to the total area of standing water in each TRS band, obtained from Ordnance Survey summary statistics, in order to predict the proportions of the different habitat types likely to occur in each band. The extent of these habitats in Great Britain as a whole could then be calculated. 4. Estimates produced by this method of the extent of the four standing freshwater habitat types in Great Britain are: dystrophic — 11 km² (0.5%); oligotrophic — 1445 km² (60%); mesotrophic — 267 km² (11%); eutrophic — 679 km² (28%). 5. The application of this work to nature conservation is discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

四轮驱动拖拉机牵引效率问题的探讨

对四轮驱动拖拉机的牵引效率计算进行了推导,分析了四轮驱动拖拉机牵引效率的影响因素,讨论了驱动力矩的控制原则及其方法。     

AN ANALYSIS OF AND APPROACH TO THE METHOD FOR TESTING THE PARALLELISM OF SAW GUIDE MOTION LOCUS AGAINST THE BLADE

UNDERSTANDINGoFTHESTANDARDSIntheWoodworkingBandSawing--MachineandCarriagePrecision(GBlo956-89),thetechnicaldemandsoftheparallelismofsawguidemotion1ocusagainstthebladeareasfollows:usingthetestingsteelbandandindicatortotestandmeasure,itsparallelismtoleranceiso.lommatalengthof3oomm.ltstestingmethod,referto"Theindicatorisfixedtothemotioncomponent,andmovestogetherwithitaccordingtotheregularrange,itsmeasuringheadtouchestheplanetested,andslidesalongit;themaximumdifferencevalueoftheindic-…     

Bradycardia-Associated Syncope in 7 Boxers with Ventricular Tachycardia (2002–2005)

Background: Syncope is a recognized problem in Boxers and often is the result of rapid ventricular tachycardia (VT). Affected dogs may have echocardiographic evidence of dilated cardiomyopathy, but frequently have normal echocardiograms. Although VT is probably the most common cause of syncope in Boxers, neurocardiogenic bradycardia can also occur.
Objective: We describe 7 Boxers with comorbid VT and neurocardiogenic bradycardia, wherein the syncope was secondary to bradycardia rather than VT.
Animals: Seven Boxers were selected from a larger population of Boxers with Holter-documented VT because these dogs had documented bradycardia at the time of syncope.
Methods: Retrospective study.
Results: Although all dogs had Holter-documented VT, the etiology of the syncopal episodes was consistent with neurocardiogenic bradycardia.
Clinical Importance: Neurocardiogenic bradycardia or VT can occur as isolated problems in Boxers. In some Boxers, VT and potential or manifest neurocardiogenic bradycardia coexist. The administration of a β-blocker or sotalol to such dogs can aggravate or precipitate neurocardiogenic bradycardia-related syncope.     

水稻插秧机分插机构的轨迹规划和运动仿真

根据分插机构的结构特点,对其进行了模型简化,应用速度瞬心法,求解出插秧机插杆末端的位移、速度方程;运用ADAMS软件,建立了水稻插秧机分插机构虚拟样机模型,仿真得出了模型的末端轨迹以及插杆末端的位移和速度,并与应用方程求解出的理论值进行对比,一方面验证了理论计算的的准确性与可靠性,另一方面验证了仿真方法的正确性与可行性,为后续水稻插秧机分插机构的设计和制造提供了理论依据。     

猪精液冷冻保存程序的优化

研究共4个试验:①按入氮温度分为-5、-30、-60、-90、-120℃5个组;②按鲜精液预处理方式分为未预稀释和预稀释2个组;③按解冻温度设37、50、70℃3个组;④按稀释后精子密度分为1.25×108、2.50×108、5.00×108spz/mL 3个组.结果表明:①不同入氮温度下精子冻后活力差异不显著,但随着入氮温度的降低,精子冻后活力呈升高趋势;②预稀释不能显著提高平衡后精子活力,但可以显著或极显著提高精于稀释后活力、冻后活力、VAP、VSL及VCL等运动指标;③3种解冻温度在精子冻后活力、VAP、VSL、VCL等4个冻后运动指标上没有显著差异,但是,随着解冻温度的上升,冻后活力呈上升趋势;④3种稀释后精子密度在猪精子冻后活力、VAP、VSL上没有显著差异,但随着密度的上升,冻后精子活力及VAP呈下降趋势,而且最高密度组精子的VCL显著慢子其它两组.总之,5种入氮温度中,以-120℃组精子的冻后活力最高;预稀释对于新鲜猪精液的冷冻保存很有必要;3种解冻温度中,70℃组精子冻后活力最高;而高密度不利于猪精子的冷冻保存.     

中华绒螯蟹平面运动三维观测和步态分析

为了研究中华绒螯蟹在平面行走的步态,使用高速摄像机和三维运动分析软件建立了运动图像采集和分析系统.结果表明:中华绒螯蟹在行走时采用交替四角步态;相邻的两腿之间异步,相隔和对角线两条腿之间同步;各腿的负荷因数为(55.60±7.53)％,说明中华绒螯蟹通过增加支撑相使其身体在行走时更加稳定.