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关键词： 湿式离合器   油槽   对流换热   热失效   适时四驱  

摘要： 针对汽车适时四驱系统轴间湿式离合器在极限工况易出现过热,从而导致摩擦片失效的现象,论文基于传统油槽的结构,提出了一种新的斜T型油槽以提高摩擦片的散热能力.根据结构特点,基于温度云图、速度云图、迹线图分析其传热特性并与传统径向油槽进行对比分析.研究结果表明,斜T型油槽增加了对流换热面积,加速了摩擦片散热,有效缓解了摩擦片的热失效.

关键词： 防爆场车   离合器   点燃危险评定   防爆设计  

摘要： 爆炸性环境用防爆场车除具备普通场车性能外还必须满足防爆安全的要求,离合器作为防爆场车的重要组成部件在其工作过程中极易产生高温热表面和火花等潜在点燃源。文中根据干式离合器的组成、工作原理及不同运行工况对其进行点燃危险评定,并依据GB 25286.1—2010提出了相应的点燃危险控制措施。

关键词： 机械压力机   离合器   制动器   联锁  

摘要： 叙述了分体离合器制动器工作原理,分析了离合器制动器协调性的测试与控制,并给出了制动器快速制动的方法。

关键词： 摩擦离合器   温控   SMA驱动器  

摘要： 温度改变可以让形状记忆合金(SMA)实现两种不同的宏观形状的转换,这种形状间转变的能力,使得它成为驱动技术的新研究方向。特别是镍钛形状记忆合金在高循环稳定性组合装置中表现出的高驱动力和调节行程能力。形状记忆效应是基于SMA致动器在马氏体和奥氏体相之间的转换。由于相变的转变温度在20~100℃,使镍钛形状记忆合金的工程应用研究中极受欢迎。文章研究的技术是利用镍钛记忆合金作为驱动,使离合器完成啮合分离动作。传动系统的启动加速致使超过额定速度时,则系统就需要一个更高的扭矩。这一要求则可以通过不增加离合器外观的标称尺寸,仅通过镍钛形状记忆合金便可实现。

关键词： 干式离合器   温度模型   线性  

摘要： 影响离合器使用寿命最重要的因素就是离合器工作时的表面温度。通过分析干式离合器压盘热力学环境,研究热量传导过程,提出轴向分层线性计算方法,并建立了温度估算模型,进而设计台架试验方案,通过台架试验获取转速,扭矩和表面温度等测量数据,利用Simulink模型离线仿真的方法对温度模型进行参数标定和估算温度校验,仿真结果表明该方法可较准确估算离合器压盘表面温度。

关键词： OF-THE-LITERATURE   ODONTOID PROCESS   CERVICAL-SPINE   MANAGEMENT   INJURIES   DISLOCATION   TRAUMA   ADULTS   SKULL  

摘要： Recent traumatological and clinical literature still commonly classify fractures of the dens apex according to the system described by Anderson and D'Alonzo (A&A) in 1974. The classification distinguishes between oblique fractures through the upper odontoid process (type I) and two types of fractures involving the body of the dens (type II) or axis (type III). The existing level of evidence is limited because of the low reported incidence of type I fractures (1-3%) among all dens fractures. Collected postmortem data, however, suggest greater non-uniformity than previously assumed; therefore, the aim is to propose a further subclassification of type I into four distinctive subtypes (I-A to IaEuroD). In this study three different type I dens fractures derived from forensic postmortem material involving two fatal accidents and two suicide victims were analyzed focusing on anatomical and mechanical details, described in four case reports and compared with findings in the literature. The type I dens fractures examined exhibited a characteristic non-uniformity inconsistent with the prevailing A&A classification. The proposed subclassification is based on observed trauma mechanisms and fracture patterns: type IaEuroA (type I A&A) describes an oblique lateral fracture through the dens apex caused by unilateral traction, type IaEuroB a horizontal fracture of the dens apex caused by rotation, type IaEuroC complete avulsion of the axis from the dens apex caused by axial traction trauma and type IaEuroD an oblique fracture of the frontal apex resulting from compression trauma. Type I dens fractures should be further classified into four subtypes to reflect the different characteristic injury mechanisms of fractures to the dens apex which do not always correspond to the previous standard of a circumscribed oval bony avulsion.

关键词： Black Brent   Branta bernicla nigricans   Fitness   Lack clutch   Life history   BRANTA-BERNICLA-NIGRICANS   LIFE-HISTORY   ADAPTIVE SIGNIFICANCE   BARNACLE GEESE   CANADA GEESE   SNOW GEESE   SURVIVAL   COSTS   REPRODUCTION   GOSLINGS  

摘要： Lack 18:125-128 (1967) proposed that clutch size in precocial species was regulated by nutrients available to females during breeding. Drent and Daan 68:225-252 (1980) proposed the individual optimization hypothesis, whereby individual state determines the optimal combination of breeding date and clutch size. Neither hypothesis accounts for variation in nutrients among females at the end of egg laying, strong right truncations in clutch size distributions, or the fact that many species with precocial young are determinate layers. One solution is that there is a maximum clutch size, above which the number of fledged young declines. We manipulated brood size in Black Brent geese to decouple brood size from maternal quality and produce broods larger than the natural maximum. We recaptured marked goslings to assess variation in prefledging survival as a function of brood size and we estimated relative prefledging survival of goslings using a Bayesian hierarchical approach. We considered effects of natural clutch size, brood size and their interaction on probability that we captured goslings at about 4 weeks of age. Prefledging survival declined with increasing brood size ( = -0.53; 95% CI -0.91 to -0.16), while laid clutch size had little influence on prefledging survival ( = -0.04; 95% CI -0.42 to 0.32). Despite declining per capita survival with increasing brood size, the most productive brood size was six goslings, which is greater than the typical maximum clutch size of five. Thus, reduced survival in large broods, by itself, is not the sole mechanism that limits maximum clutch size. We suggest elsewhere that incubation limitation and lower residual reproductive value for females tending larger broods may be other mechanisms limiting maximal clutch size in brent.

关键词： Hybrid electric vehicle   Engine clutch   Torque observer   Estimation   DESIGN  

摘要： This paper mainly focuses on the accurate estimation of the torque transferred through the engine clutch installed between the engine and the drive motor in parallel-type hybrid electric vehicles. The estimation of the engine clutch torque primarily relies on the forward-direction observer which uses the nominal engine net torque information. To overcome the limitation of using the nominal engine torque information that it may not be accurate during the transient states or due to the influence of external disturbance such as the road condition and wind, the forward-direction observer is supplemented by the use of reverse-direction observer which uses the driveline model and wheel speed measurements. In addition, the drive motor torque information is used to calibrate the nominal engine torque during the idle charging state, so that the driveline characteristic unique to parallel-type hybrid electric vehicle can be utilized to increase the estimation accuracy. Finally, the estimation performance of the designed observer is tested via simulation and experiments based on a real vehicle.

关键词： automated manual transmission   time-varying launching-intention-aware machine   linear quadratic regulator   clutch engagement strategy   sliding-mode control   AUTOMOTIVE DRY-CLUTCH   TORQUE   DESIGN  

摘要： Engagement control of automated clutch is essential during launching process for a vehicle equipped with an automated manual transmission (AMT), and instantaneous changes in the driver's launching intention make it more complicated to control the clutch. This paper studies the identification of the driver's launching intentions, which may change anytime, and proposes a clutch engagement control method for vehicle launching. First, a launching-intention-aware machine (LIAM) based on artificial neural network (ANN) is designed for real-time tracking and identifying the driver's launching intentions. Second, the optimal engagement strategy for different launching intentions is deduced based on the linear quadratic regulator (LQR), which figures out a compromise between friction loss, vehicle shock, engine speed, clutch speed, and desired vehicle speed. Third, the relationship between transmitted torque and clutch position is obtained by experiments, and a sliding-mode controller (SMC) is designed for clutch engagement. Finally, the clutch engagement control strategy is validated by a joint simulation model and an experiment bench. The results show that the control strategy reflects the driver's launching intentions correctly and improves the performance of vehicle launching.

关键词： Wind tunnel testing   Blade element momentum theory   Horizontal axis wind turbine   Power coefficient   Thrust coefficient   PERFORMANCE   DESIGN  

摘要： The umbrella-type rotor concept for horizontal axis wind turbine is proposed. The rotor allows blades to fold along the hinge which is fixed at the hub. The blade pitching and rotor coning are coupled as the hinge is inclined. This rotor is designed as a new approach to realize power control in high wind speed. The model-scale umbrella-type rotor with three blades was made and a rotor mechanical power testing platform was set up. Wind tunnel testing was conducted to supply data to estimate the rotor power performance. In the field of wind turbine aerodynamics theory, the blade element momentum model was improved for the umbrella type rotor aerodynamics calculation. Comparison between wind tunnel testing data and simulation result has been made. Experiment result showed that umbrella-type rotor was effective in adjusting power output by folding blades. The highest power coefficient was 0.259 in current study. Nevertheless it dropped down to 0.06 when the blades were folded at 20. In wind speed from 5 m/s to 9.54 m/s, a constant power output of 8.87 W was achieved. The calculated rotor power coefficient was found to be in good agreement with the experiment data. The highest average deviation was 11.81%. (C) 2016 Elsevier Ltd. All rights reserved.