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关键词： 力学性能   疲劳寿命   接触应力   弯曲应力  

摘要： 根据齿轮传动中轮齿折断和齿面点烛疲劳破坏现象,基于齿轮啮合原理,对斜齿轮啮合过程的力学性能及疲劳寿命预测进行研究,结合实例分析计算齿轮传动过程中齿面接触应力变化规律和齿根弯曲应力变化规律;利用ANSYS建立斜齿轮副有限元模型,分析齿面接触应力和齿根弯曲应力,将其与理论计算结果比较,验证有限元分析方法的正确性,利用FE-SAFE中的名义应力分析法对斜齿轮副的危险部位进行疲劳寿命预测。

关键词： Clutch size   Prolactin   Luteinizing hormone   Avian reproduction   Egg removal   INCUBATION BEHAVIOR   ZEBRA FINCH   INDIVIDUAL VARIATION   REPRODUCTIVE EFFORT   LH   SECRETION   BIRD   STARLINGS   QUALITY   COSTS  

摘要： Clutch size is a key avian fitness and life history trait. A physiological model for clutch size determination (CSD), involving an anti-gonadal effect of prolactin (PRL) via suppression of luteinizing hormone (LH), was proposed over 20 years ago, but has received scant experimental attention since. The few studies looking at a PRL-based mechanistic hypothesis for CSD have been equivocal, but recent experiments utilizing a pharmacological agent to manipulate PRL in the zebra finch (Taeniopygia guttata) found no support for a role of this hormone in clutch size determination. Here, we take a complementary approach by manipulating clutch size through egg removal, examining co-variation in PRL and LH between two breeding attempts, as well as through experimentally-extended laying. Clutch size increased for egg removal females, but not controls, but this was not correlated with changes in PRL. or LH. There were also no differences in PRL between egg removal females and controls, nor did PRL levels during early, mid- or late-laying of supra-normal clutches predict clutch size. By uncoupling PRL, LH and clutch size in our study, several key predictions of the PRL-based mechanistic model for CSD were not supported. However, a positive correlation between PRL levels late in laying and days relative to the last egg (clutch completion) provides an alternative explanation for the equivocal results surrounding the conventional PRL-based physiological model for CSD. We suggest that females coordinate PRL-mediated incubation onset with clutch completion to minimize hatching asynchrony and sibling hierarchy, a behavior that is amplified in females laying larger clutches. (C) 2015 Elsevier Inc. All rights reserved.

关键词： 离合器故障   平衡活塞   自动变速器   换挡控制   离合器打滑   离合器片   故障根源   摩擦片  

摘要： 如果遇到K3／C3离合器故障，比如离合器片烧毁，我们应该按照怎样的思路来查找故障根源呢？对此，我们不应该止步于更换摩擦片的操作，因为摩擦片烧毁仅是故障的表现，而非故障的根源。我们首先应该查看K3／C3离合器本身，包括上述平衡活塞的油封、铜套及作用活塞的状态，离合器鼓上的焊点等等，这些地方的油压泄漏会引起离合器打滑、烧毁。

关键词： 张紧绞车   拆解   检测  

摘要： 目前,随着科技不断发展,世界煤炭工业正在向高度集中、集约化、高产高效综合机械化方向发展,工作面的生产能力大幅度提高,采区走向长度一般都达到2000～6000m,这就必然要求工作面运输巷带式输送机朝着高可靠性、高效性、输送能力大、带速高、运距大、驱动功率大、输送带宽增加的方向发展,随着设备不断更新,对于设备的检修也带来巨大的挑战,故设计矿用顺槽胶带机张紧绞车离合器、制动器、液压马达拆装与检测装置。

关键词： 有限元模型   摩擦材料   湿式离合器   数学模型  

摘要： 已经开发了一个有限元模型,研究表面粗糙和带槽纸质可渗透的湿式离合器的接合特性。采用有限元方法(Galerkin)离散修正雷诺和力平衡方程式,采用等参量方程式解所描述的有关内何学。通过Patir和Cheng(1978)的通用流量模型模拟表面粗糙度的影响。在表面粗糙状况下,采用Greenwond和William son(1966)方法计算负荷分配,采用开发的有限元模型研究所加负荷的影响,以及湿式离合器摩擦材料的渗透率和槽出入口尺寸的接合特性(即转矩、油压、接合时间和油膜厚度)。研究结果表明,所加负荷、摩擦材料渗透率和槽宽度对接合特性的影响显著。高的配合面压力增大了峰值和减少了接合时间但显著增大了峰值转矩,宽油槽减少峰值转矩和增加了接合时间。对于本模型油槽深度对接合特性的影响不太明显。

关键词： 离合器   检查调整   东方红802  

摘要： 离合器长期使用后必将发生磨损，使离合器在工作中出现故障，影响车辆的正常使用。本文对几种常见车型上使用的离合器的检查调整技术进行了详细的介绍。

关键词： SSS离合器   设计特点   应用  

摘要： 文章介绍了SSS离合器的设计特点及工作原理,详细分析了离合器的启动、运行和停机过程的工作情况及其应用。

关键词： African Black Oystercatcher   avian reproduction   clutch size   geographic variation   Haematopus moquini  

摘要： African Black Oystercatchers Haematopus moquini produce a modal clutch size of two eggs and only rarely lay three eggs. A review of over 4 000 nest records from across their breeding range (dating back to the early 1960s) revealed that three-egg clutches have become more frequent, rising from 2% of recorded clutches before 1975 to >5% since 2000. Three-egg clutches are found predominantly in the south-western Cape and are clustered at specific sites in the region. They are produced earlier in the season compared to smaller clutch sizes and rarely occur after January. As this increase in three-egg clutch frequency is site specific, it might result from either a phenotypically plastic response to local resource availability, or a localised change in breeding system potentially resulting in more than one female laying in the same nest. While increased food availability might be the cause of changes in three-egg clutch frequencies, this is unlikely linked to the spread of the invasive mussel Mytilus galloprovincialis. Further research is needed to identify the cause of this phenomenon and evaluate how this change may affect the breeding success of this species.

关键词： 自调式离合器   力感应碟形弹簧   力学特性   有限元分析  

摘要： 自调式离合器依靠安装在自调机构中的力感应碟形弹簧,使膜片弹簧离合器的摩擦片产生磨损后能够自动补偿并保持分离力不变。在自调式离合器开发过程中,利用有限元方法对自调式离合器力感应碟形弹簧受力情况进行模拟,得到载荷—位移曲线,并将结果与A-L理论公式计算的结果以及试验结果进行比对分析。结果表明:相比于理论计算结果,有限元计算结果与试验数据误差较小,能比较准确地反映出碟形弹簧的力学特性。

关键词： 离合器   摩托车   典型故障   检修   摩擦副   动力传动   电气线路   相互作用  

摘要： 摩托车离合器（见图1）在摩托车运行中起到平稳起步、传递动力、换挡平顺的作用,由此,离合器是集摩托车的安全性、使用性、舒适性于一体的零部件。离合器是起步或变速时切断和连接发动机到变速器动力传动的装置,相当于电气线路中的开关,分为干式单片型和湿式多片型2种,摩托车多采用湿式多片型离合器（见图2）。在摩托车湿式多片型离合器中,叠装在离合器大毂内的摩擦片和花键套上的摩擦铁片组成摩擦副,转矩通过摩擦副的相互作用来传递。离合器在使用中主要失效方式为打滑、异响、烧片和发冲。遇到上述现象应予以及时检修,以确保摩托车的正常使用。