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关键词： 直廓环面蜗杆   圆柱斜齿轮   齿面修形   有限元分析  

摘要： 提出了一种直廓环面蜗杆-圆柱斜齿轮啮合传动形式。根据蜗杆几何参数,计算出与蜗杆配合的圆柱斜齿轮几何参数,建立了直廓环面蜗杆与圆柱斜齿轮的三维模型;运用有限元软件Workbench进行静力学分析,得出齿面接触应力、等效应力及位移量;对斜齿轮进行齿廓及螺旋线双向内凹修形,结果显示内凹修形可以适当减小齿面接触应力及位移量,从而提高齿轮副的承载能力,其中齿廓修形对接触性能影响更为显著。通过加工与滚检试验,验证了所提出的直廓环面蜗杆与斜齿轮传动方式的可行性。

关键词： captive populations   conservation   demography   extinction   Mollusca   Oceania   LAND SNAILS   BIOLOGICAL-CONTROL   FRENCH-POLYNESIA   MASS EXTINCTION   POPULATIONS   ISLANDS   CONSERVATION   EVOLUTION   PROGRAM   PERSISTENCE  

摘要： Endemic Pacific Island land snails are among the planet's most endangered taxonomic groups and many have fallen victim to misguided biological control programmes involving the rosy wolf snail, Euglandina rosea. The family Partulidae has been heavily impacted but a recent study of Tahitian species found that survivors had differentially higher clutch sizes. Here, we further tested the inference that higher fecundities may promote survival of Partula species by incorporating historical field demographic data from additional island populations (Guam, Saipan and Moorea) that collectively span the range of the family, as well as complementary demographic data from captive populations sourced from these islands and from Tahiti. Our primary result broadly corroborated the earlier study: species with higher reproductive output, whether measured by historical field clutch sizes or by reproductive rates in captivity, are more likely to have survived. However, this generality does not apply to all island populations and it is unlikely to be the sole determining factor in any of these cases. Detailed ecological and behavioural studies of extant wild P. radiolata (Guam), P. gibba (Guam and Saipan), P. taeniata (Moorea), P. hyalina and P. clara (Tahiti) populations, and of their co-occurring introduced predators, are urgently required.

关键词： Barrett's esophagus   clutch cutter   endoscopic submucosal dissection   esophageal neoplasia   MUCOSAL ADENOCARCINOMA   RESECTION   EFFICACY   MANAGEMENT   CARCINOMA   DIAGNOSIS   THERAPY  

摘要： Although the endoscopic submucosal dissection (ESD) has been established to be more efficacious in the treatment of superficial gastrointestinal neoplasia than the piecemeal resection, its use is still limited due to the concern about serious adverse events particularly in the west. Newer ESD knives have been developed that have been said to be safer than the first-generation devices. We aimed to report a Western single center experience regarding the initial safety and performance of ESD for superficial esophageal neoplasia treated with the Clutch Cutter (DP2618DT; Fujifilm Corporation, Tokyo, Japan). Our main outcome was safety in terms of bleeding or perforation. Secondary outcomes included en bloc resection and the R0 resection. Fourteen patients with superficial esophageal neoplasia underwent 15 ESDs using the Clutch Cutter. The mean age was 65 +/- 16.7 years and 10 (71.4%) males. Eight (57%) patients had esophageal adenocarcinoma, 3 (21.4%) had high-grade dysplasia, 1 (7%) had nodular low-grade dysplasia, and 2 (14.3%) had squamous cell carcinoma. Mild anticipated intraprocedural bleeding was present with most procedures. However, no significant postoperative bleeding or perforation was encountered. One patient had mild chest pain postprocedure. En bloc resection was achieved in all lesions 100%. Histological R0 was achieved in 5/12 lesions (41.6%). The mean length of the resected area was 24.8 +/- 13 mm (IQR: 17-30 mm). All patients were safely discharged home after overnight observation. In conclusion, this is the largest series of esophageal ESD using the multimodal Clutch Cutter in the United States; we found that the device effectively achieved en bloc resection of superficial esophageal neoplasia without significant adverse events. The use of the Clutch Cutter should be considered as one option to minimize adverse events during ESD in the Western population.

关键词： 插电式混合动力公交车   离合器   校核   匹配计算  

摘要： 该文针对某新开发的插电式混合动力公交车车型所选配的离合器系统的传递扭矩、起步温升、滑磨功、执行机构推力和行程等进行校核匹配计算。

关键词： 离合器   分离力-分离位移特性   踏板力-位移特性   膜片弹簧   波形片  

摘要： 分析了离合器分离力-分离位移曲线与踏板力-位移特性曲线的关系。建立了离合器分离力-分离位移特性计算的有限元模型。在建立的有限元模型中,包含离合器压盘总成和从动盘总成的有限元模型。建模中,考虑了膜片弹簧和波形片的轴向非线性特性。利用建立的模型,计算得到了离合器的分离力-分离位移曲线,通过台架测试了离合器的分离力-分离位移特性,计算结果与实测结果的对比分析,验证了模型的正确性。分析了膜片弹簧工作点位置和波形片轴向刚度对分离力-分离位移曲线的影响,并依据分析结果进行离合器踏板力-位移特性的改进。利用离合器操纵系统试验台进行了离合器踏板力-位移特性测试,验证了计算结果的正确性。该研究结果建立了膜片弹簧的工作位置和波形片的轴向刚度与离合器分离力-分离位移特性的关系,可为改善离合器踏板操纵舒适性提供计算分析方法。

关键词： 检查   检修   调整   故障分析  

摘要： 离合器是汽车机械传动的重要部件,位于发动机和变速器之间,操纵离合器可实现汽车传动系统的分离或结合。阐述现代离合器的结构特点,在离合器的检查、调整、检修等方面进行分析,并总结了离合器常见故障。

关键词： 汽车离合器   成形工艺   冷锻成形   轴套   减震   闭式   模具结构设计   工艺方案  

摘要： 本文在分析汽车离合器减震轴套结构的基础上,提出了一种汽车离合器减震轴套闭式冷锻成形工艺方案,并完成了模具结构设计。基于数值模拟技术,应用DEFORM-3D软件对零件成形过程中应力场、应变场及金属流动速度场进行了模拟分析,模拟结果表明,零件成形过程中材料流动、应力、应变情况良好。根据设计的工艺方案进行了成形试验,并获得了质量合格的制件,验证了成形工艺方案的合理性。

关键词： 离合器故障   汽车   离合器异响   维修   异常响声   离合器分离   离合器踏板   行驶途中  

摘要： 离合器作为汽车动能系统之中重要的一部分,其承担着车辆动力的传送和停止,对于路面条件十分困难的路程行驶途中,离合器成了我们使用率最高的部件之一,所以保障离合器的正常运行是十分有必要的.在使用离合器的时候,通常发生的故障一般有离合器异响、离合器分离不彻底（挂档困难）、打滑和发抖等问题.故障现象：发动机在怠速运转时,司机用脚踩下离合器踏板时,离合器发出异常的响声,然后放松脚踏板异常响声消逝;有时不论踩下还是放松都会有异响.

关键词： 汽车底盘   故障诊断   维修方法   离合器  

摘要： 文章基于当前形势,从中医式分析、经验式分析、观察式分析三个方面对汽车底盘常见故障诊断分析进行了简单介绍,并从离合器、变速器、转向器和制动器的故障和维修四个方面入手,探讨了汽车底盘常见故障维修方法,希望为广大读者提供有价值的意见。