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关键词： 推土机   主离合器   摩擦力矩   转矩储备系数   工作原理  

摘要： SD16T推土机主离合器为杠杆机构压紧式离合器,采用粉末冶金多片湿式摩擦片,其作用是控制发动机与传动系统之间的动力传递与切断来实现整机换挡功能;本文针对主离合器的主要参数:摩擦力矩Mm、摩擦片直径和转矩储备系数b对该离合器进行了计算与校核,并对其结构及工作原理进行论述。

关键词： 离合器分离   离合器踏板   汽车发动机   故障   发动机熄火   怠速运转   变速器   撞击声  

摘要： 离合器分离不彻底的现象 汽车发动机在怠速运转中．当离合器踏板被踩到底时，此时变速器挂挡感到非常困难，并且产生齿轮撞击声．挂不上挡或挂上挡后不抬起离合器踏板汽车就自动行驶，或发动机熄火等。

关键词： SALIVARY CORTISOL-LEVELS   CUSHINGS-SYNDROME   INSULIN-RESISTANCE   DIAGNOSIS   ASSOCIATION   ATHEROSCLEROSIS   UPDATE  

关键词： p-Type tin monoxide (SnO)   high c-axis orientation   thermal stability   TFT APPLICATION   TIN MONOXIDE   TRANSISTORS   PHASE   EVOLUTION   MOBILITY  

摘要： p-Type tin monoxide (SnO) thin films with high c-axis preferred orientation have been fabricated on quartz substrate via electron-beam evaporation at 280A degrees C. Subsequently, rapid thermal annealing (RTA) was performed in N-2 atmosphere at 400A degrees C to 800A degrees C. Their structural, chemical, optical, and electrical properties were investigated by x-ray diffraction analysis, ultraviolet-visible spectroscopy, scanning electron microscopy, x-ray photoelectron spectroscopy, and Hall-effect measurements. The c-axis-oriented films of Sn-rich SnO presented excellent thermal stability up to RTA at 700A degrees C. Both the crystallization and the hole Hall mobility were enhanced with increasing RTA temperature, with Hall mobility of 16 cm(2) V-1 s(-1) being obtained after RTA at 700A degrees C. It was considered that the presence of defects and low scattering from grain boundaries contributed to this high Hall mobility. RTA annealing temperature above 700A degrees C induced chemical reaction between SnO and the quartz substrate, with a change of the film to amorphous state with Sn4+ formation.

关键词： Absent posterior element of axis   Anomalous vertebral artery   Atlantoaxial dislocation   Axis   Congenital spondylolisthesis   POSTERIOR ELEMENTS   ABSENCE   AXIS  

摘要： BACKGROUND: Congenital spondylolytic spondylolisthesis of C2 vertebra resulting from deficient posterior element of the axis is rarely described in the literature. CASE DESCRIPTION: We describe a unique case of agenesis of posterior elements of C2 with craniovertebral junction anomalies consisting of osseous, vascular, and soft tissue anomalies. A 26-year-old man presented with symptoms of upper cervical myelopathy of 12 months' duration. A computed tomography scan of the cervical spine including the craniovertebral junction revealed spondylolisthesis of C2 over C3, atlantoaxial dislocation, occipitalization of the atlas, hypoplasia of the odontoid, and cleft posterior C1 arch. Additionally, the axis vertebra was found devoid of its posterior elements except bilaterally rudimentary pedicles. Magnetic resonance imaging revealed tonsilar herniation, suggesting associated Chiari type I malformation. CT angiogram of the vertebral arteries displayed persistent bilateral first intersegmental arteries crossing the posterior aspect of the C1/2 facet joint. This patient underwent foramen magnum decompression, C3 laminectomy with occipito-C3/C4 posterior fusion using screw and rod to maintain the cervical alignment and stability. CONCLUSION: We report this rare constellation of congenital craniovertebral junction anomaly and review the relevant literature.

关键词： Wear prediction   Wet clutch   Model validation   Uncertainty quantification   HOT-SPOTS  

摘要： An uncertainty quantification analysis is performed to further investigate the nature of the "two-stage" wear process of the paper-based friction lining in a wet clutch. In this approach, the results of a computerized wear prediction model are examined through sensitivity analysis and a model validation that utilizes the Monte Carlo (MC) method. Extensive computational results that take into account the uncertainty and variability in the input data are presented to gain insight into the evolution of temperature and wear during the engagement process. (C) 2016 Elsevier B.V. All rights reserved.

关键词： 传动片   静强度分析   疲劳分析  

摘要： 文中针对应用离合器中的传动片进行静强度和疲劳强度分析。首先建立了离合器传动片的力学模型,通过有限元分析得到了传动片的应力分布和疲劳寿命,最后通过试验验证传动片分析的正确性。在对传动片有限元分析中,首先采用Hypermesh软件针对三维模型进行网格划分,把划分好网格后把网格导入到abaqus软件中,根据建立好的力学模型,对模型施加边界条件,并求解得到传动片应力分布云图。然后根据线性疲劳累积损伤理论,采用应变-寿命法对模型进行疲劳分析,得到传动片的疲劳寿命。

关键词： 前进挡离合器  

摘要： 故障现象：一辆2008年产一汽一大众奥迪A6L轿车，该车搭载2．4L发动机和01T型链传动无级变速器（CVT）。据用户介绍．该车因前进挡起步及低速范围加速时严重耸车而报修，特别是反复松开再踩下加速踏板时耸车特别明显。有时车辆无法加速，同时仪表挡位指示灯一片全红，此时耸车现象加剧。据客户反映，这种耸车现象很早就有了，因为早期故障不明显．只是给变速器换油保养，情况有所好转。

关键词： 压盘   铸造缺陷   数值模拟   工艺优化  

摘要： 在DISA线生产汽车离合器压盘铸件时,铸件出现了严重的缩孔缺陷,导致了产品报废。运用铸造模拟软件ProCAST对铸件充型和凝固过程进行模拟,分析缺陷产生的原因。根据模拟结果优化原始工艺,将原底注式浇注工艺改为阶梯式浇注,缩短补缩浇道的长度、加大补缩浇道截面和冒口的尺寸,同时在冒口颈附近设置补贴。对改进后的工艺再进行模拟,发现中间层浇道提前进浇,出现了严重的冲刷和裹气。对工艺再次进行优化,将中间层浇道向上倾斜并减小其截面,同时增大底层浇道的截面;将浇注温度降低至1350℃。采用二次改进后的工艺生产的铸件缩孔缺陷消除,铸件质量完好,成品率大幅度提升。

关键词： Vertical axis wind turbine  

摘要： The effect of blade number on performance of drag type vertical axis wind turbine (VAWT) is studied by Ansys numerical simulation, it involves 3-blade, 5-blade and 6-blade VAWTs. The optimized width of blade for each VAWT at maximum power efficiency is obtained, and simulation for the wind turbine with different number of blade is conducted for the VAWTs with turbine radius of 2 m at the inlet wind speed 8 m/s. By simulations, it gets the evolution curve of torque with respect to time, and the cyclical characteristics for these wind turbines. The results show that the maximum power efficiency and the stability of the wind turbine increase with the number of blade of the wind turbine, however the optimal d/D decreases with the number of blade of the wind turbine. The maximum power efficiencies are 20.44, 24.30 and 26.82% for 3-blade, 5-blade and 6-blade wind turbines, and the correspondingly optimal d/D are 0.66, 0.40 and 0.35, respectively. While the optimal rotational rate of turbine decreases with blade number. © 2016, Allerton Press, Inc.