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关键词： 电控机械式自动变速器   驾驶品质   干式离合器   滑磨控制   抗扰控制  

摘要： 电控机械式自动变速器(Automated manual transmission, AMT)换档品质难以控制,其主要原因是干式离合器没有油膜缓冲,且存在摩擦因数变化、膜片弹簧衰退等不确定因素。为了提高换档过程的驾驶品质,提出对离合器滑磨与驱动力矩恢复进行并行控制的动力换档模式,并为此过程设计"抗扰最优控制+模型误差观测"的换档控制策略。通过扰动观测器得到离合器与车辆动力传动系统的建模误差及外界扰动,进而将其视为系统扰动,设计可处理快变扰动的最优换档控制器,实现任意工况下滑磨功和冲击度的综合优化。联合仿真与实车试验结果表明,提出的方法不仅提升换档过程的驾驶品质,而且对不同工况有自适应能力,从而解决AMT车辆难以保证驾驶品质控制效果一致性的行业难题。

关键词： 竞争失效   间歇期   飞机连杆式舱门收放机构  

摘要： 建立了考虑间歇期的适用于飞机连杆式舱门收放机构的竞争失效模型。使用泊松过程、Archard磨损模型和功能失效函数对飞机机构的突发型失效和退化型失效进行建模;充分考虑飞机存在不同工作状态的实际特点,引入间歇期因素建立了新的竞争失效模型;以某型飞机连杆式舱门收放机构作为案例,在深入分析机构工作原理和失效特点的基础之上,对所建模型进行应用研究,结果表明间歇期的引入使得各模式失效概率和系统可靠度呈现不同的演化特征,且考虑间歇期的竞争失效模型具有良好的工程实用性。

关键词： Chronic stress   Lateral septum   Glucocorticoids   Type-2 CRF receptor   Norepinephrine   Anxiety-like behavior  

摘要： The stress response is multifactorial and enrolls circuitries to build a coordinated reaction, leading to behavioral, endocrine, and autonomic changes. These changes are mainly related to the hypothalamus-pituitary-adrenal (HPA) axis activation and the organism's integrity. However, when self-regulation is ineffective, stress becomes harmful and predisposes the organism to pathologies. The chronic unpredictable stress (CUS) is a widely used experimental model since it induces physiological and behavioral changes and better mimics the stressors variability encountered in daily life. Corticotropin-releasing factor (CRF) and glucocorticoids (GCs) are deeply implicated in the CUS-induced physiological and behavioral changes. Nonetheless, the CUS modulation of CRF receptors and GR and the norepinephrine role in extra-hypothalamic brain areas were not well explored. Here, we show that 14 days of CUS induced a long-lasting HPA axis hyperactivity evidenced by plasmatic corticosterone increase and adrenal gland hypertrophy, which was dependent on both GCs and NE release induced by each stress session. CUS also increased CRF2 mRNA expression and GR protein levels in fundamental brain structures related to HPA regulation and behavior, such as the lateral septal nucleus intermedia part (LSI), ventromedial hypothalamic nucleus (VMH), and central nucleus of the amygdala (CeA). We also showed that NE participates in the CUS-induced increase in CRF2 and GR levels in the LSI, reinforcing the locus coeruleus (LC) involvement in the HPA axis modulation. Despite the CUS-induced molecular changes in essential areas related to anxiety-like behavior, this phenotype was not observed in CUS animals 24 h after the last stress session.

关键词： Egg covering   Ficedula   Nest site preferences   Parus   Social learning   Tutor  

摘要： Among species that use similar resources, an individual may benefit by observing and copying the behavioural decision of a heterospecific. We tested the hypothesis of heterospecific social learning in passerine birds, namely that a migrant species, the Pied Flycatcher Ficedula hypoleuca, uses external markings on the nest cavities of a resident species, the Great Tit Parus major, as cues when choosing a nest site. Others have suggested that prospecting flycatchers assess the clutch size of tit "demonstrators" by entering their nest boxes and, assuming that a large clutch indicates a high-quality individual, will copy the nest appearance of tits with large, but not small clutches. During a 4-year period in Norway, we designed a similar study but did not find that flycatchers based their nest choice on the clutch size of tits. Neither were there any relationships between clutch size of the tit and its laying date, incubation behaviour, or the number of eggs visible through nest material during egg-laying so Pied Flycatchers did not use these indirect cues to assess quality of the tutor. Filming of tit nests showed that prospecting flycatchers did not enter tit nest boxes to assess the content. Indeed, incubating female tits only left their nest boxes for short bouts of unpredictable duration so there was little opportunity for flycatchers to inspect the nest contents unnoticed. Our study calls into question the mechanism of using the content of tit nests as public information for choosing traits of nest sites based on external characteristics. We suggest that similar studies of nest site choice in relation to possible social information transfer be replicated more widely.

关键词： Wet clutch   Experimental study   Torque characteristics   Friction coefficient  

摘要： The purpose of this study is to determine the influencing factors and changing laws of the friction behavior of a wet clutch under actual working conditions. A qualitative analysis is conducted on the torque characteristics of a wet clutch and influence laws such as the relative and absolute speeds of the driving and driven ends of the clutch, lubricant flow, engagement force and its change rate, lubricant temperature, and friction surface temperature. The identified influence mechanisms and friction behavior can be used for the design and production of a precise controller for the transmission torque of a wet clutch.

关键词： Dual-clutch transmission   Combustion engine dynamic model   Neural network engine model   Inertia phase  

摘要： The paper presents an engine control algorithm, based on an artificial neural network (ANN), which ensures a quick and smooth inertia phase of an upshift in a dual-clutch transmission (DCT). The main emphasis is placed on 3D characteristics, which can be directly implemented in the ECU, to control the inertia phase, when the engine speed decreases to reach the target clutch speed. They are developed based on an ANN model which approximates data obtained during engine test bed measurements in dynamic states. Moreover, to provide an overall gear change algorithm, the dual-clutch assembly activation mechanism was also analysed.

摘要： Mechanical properties of the extracellular environment modulate axon outgrowth. Growth cones at the tip of extending axons generate traction force for axon outgrowth by transmitting the force of actin filament retrograde flow, produced by actomyosin contraction and F-actin polymerization, to adhesive substrates through clutch and cell adhesion molecules. A molecular clutch between the actin filament flow and substrate is proposed to contribute to cellular mechanosensing. However, the molecular identity of the clutch interface responsible for mechanosensitive growth cone advance is unknown. We previously reported that mechanical coupling between actin filament retrograde flow and adhesive substrates through the clutch molecule shootin1a and the cell adhesion molecule L1 generates traction force for axon outgrowth and guidance. Here, we show that cultured mouse hippocampal neurons extend longer axons on stiffer substrates under elastic conditions that correspond to the soft brain environments. We demonstrate that this stiffness-dependent axon outgrowth requires actin-adhesion coupling mediated by shootin1a, L1, and laminin on the substrate. Speckle imaging analyses showed that L1 at the growth cone membrane switches between two adhesive states: L1 that is immobilized and that undergoes retrograde movement on the substrate. The duration of the immobilized phase was longer on stiffer substrates;this was accompanied by increases in actin-adhesion coupling and in the traction force exerted on the substrate. These data suggest that the interaction between L1 and laminin is enhanced on stiffer substrates, thereby promoting force generation for axon outgrowth.

关键词： clutches   fluid friction   rheology   surfaces   tribological systems   viscosity  

摘要： In this research paper, an attempt has been made to investigate the torque transmission characteristics in a radial magnetorheological (MR) clutch disc with different groove profiles. To estimate the transmitted torque, a numerical procedure is initiated by the implementation of the Bingham constitutive model into a magnetic field analysis followed by computational fluid dynamic (CFD) analysis. CFD results are presented for the analysis of transmitted torque between a plane driving disc and three different driven discs, i.e., plane, radial groove, and circular groove disc, under the conditions of different working radii, magnetic fields, and rotational speeds. The MR fluid (MRF) domain is modeled using a technique which can be applied for any wall texture of driving and driven disc. To verify the numerical findings, an MR clutch with three different discs and a MR transmission test bed have been built, and the influence of groove profile on the transmission torque of MRFs has been investigated on the test bed. The results are presented to obtain the relationships among torque performance, disc radius, rotational speed, and magnetic field. Numerical results show good agreement of torque transmission for different groove profiles with experiments. Finally, temperature distribution patterns in different three MR clutches and an optimization of the radial groove profile have been analyzed numerically.

关键词： 旋翼无人机   稳定云台   有限元分析   结构设计  

摘要： 传统的多旋翼无人机云台载重量小,无法搭载较大质量的光电设备去执行更复杂的任务,而现有的大负载云台大多数都是手持式或者只能搭载在直升机上,不适用于多旋翼无人机搭载,针对此问题设计了一款适用于多旋翼无人机的较大负载两轴云台。根据设计的两轴云台介绍了云台平衡原理,通过Solidworks软件建立其三维模型,装配完成后检验云台模型是否会发生干涉情况,然后对云台各个零件的材料进行选择,并使用ANSYS Workbench软件对云台模型进行有限元静力学及动力学仿真分析。结果表明:两轴云台结构刚度、强度符合要求,且具有较好的稳定性和可靠性,为以后较大负载的机载云台结构设计研究提供了参考。

关键词： 交通堵塞   失明症   斑马线   人行横道   信号灯   紧张状态   离合器  

摘要： 黄灯亮了。前面两辆汽车抢在变成红灯以前加速冲了过去。人行横道边出现了绿色的人像。正在等候的人们开始踩着画在黑色沥青上的白线穿过马路,没有比它更不像斑马的了,人们却称之为斑马线。司机们个个急不可耐,脚踩离合器,使汽车保持紧张状态,进一进,退一退,像一匹匹感到鞭子即将从空中抽下来的马一样躁动不安。行人刚刚过去,给汽车放行的信号还要迟几秒钟,有人说被拖延的这点时间表面看来微不足道,但如果我们用它乘以全城数以千计的信号灯,再乘以三种颜色不断变化的次数,那么它便成为交通堵塞,现在常用的说法是塞车,最为重要的原因了。