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关键词： Clutchless geared smart transmission (CGST)   Dynamic model   Gear shifting   Planetary gear system   Hybrid transmissions  

摘要： Conventional geared transmissions use some kinds of clutches to control the power flow from an internal combustion engine to the driveline while shifting gears. However, the shifting performance is seriously affected by the clutch engagement and an unavoidable drop in the torque may occur when the clutch is disconnected. Moreover, wear of the clutch, the need for hydraulic equipment, and the load limit may together aggravate the limits of the clutch system. For this reason, as a novel transmission without a clutch, the clutchless geared smart transmission (henceforth COST) is proposed by our research team. The CGST controls the power flow in a multiple-input gear-train by controlling the electric motor attached to the planetary gear system. However, no COST has been realized in an actual vehicle thus far, and the performance has been predicted only theoretically. In this research, we analyzed the achievable performance based on a developed CGST dynamic model with a typical CGST structure. In addition, a CGST gear-shifting algorithm is proposed for use with the dynamic model. From the simulation results, the CGST does not show an abrupt drop in its torque or oscillation while shifting gears due to the absence of a discontinuous power flow. The developed dynamic model can serve as a performance reference for the COST. Moreover, it can be used as a simulation tool for developing a gear-shifting control logic scheme.

关键词： Spondylarthritis   Spondylitis   Diffusion weighted imaging   Apparent diffusion coefficient   Modic change   WEIGHTED MRI   BACK-PAIN   MARROW   SPONDYLOARTHRITIS   FRANCE  

摘要： Objective: The goal of this study was to evaluate whether the values of ADC in spondylarthritis axial active inflammatory lesions are different from ADC values in type 1 Modic changes. Subjects and methods: 95 patients with recent lumbar pain, including 46 patients with diagnosed or suspected spondylarthritis and 49 patients with purely degenerative history, underwent spine MRI. T1w, STIR, and diffusion-weighted images (DWI) were obtained. Two musculoskeletal radiologists interpreted the images. Axial active inflammatory lesions from the SpA group and type 1 Modic changes from the degenerative group were identified on T1w and STIR sequences. ADC values from these lesions and from healthy subchondral bone were compared. Results: All axial active inflammatory lesions (n = 27) and type 1 Modic changes (n = 22) identified in T1w and STIR images were visible on DWI. ADC values were significantly higher (p < 0.05) for axial active inflammatory lesions (median = 0.788 x 10(-3) mm(2)/s, IQR 25-75 [0.7 x 10(-3) mm(2)/s; 0.9 x 10(-3) mm(2)/s]) than for type 1 Modic changes (median = 0.585 x 10(-3) mm(2)/s, IQR 25-75 [0.55 x 10(-3) mm(2)/s; 0.60 x 10(-3) mm(2)/s]) and normal subchondral bone (median = 0.443 x 10(-3) mm(2)/s, IQR 25-75 [0.40 x 10(-3) mm(2)/s; 0.50 x 10(-3) mm(2)/s]). Intra-class correlation coefficients for intra-and inter-reader ADC values comparison were excellent (0.89 and 0.98 respectively). Conclusion: DWI is a sensitive and fast sequence that offer the possibility of quantifying diffusion coefficients of the lesions, which could help to discriminate between spondylarthritis axial active inflammatory and type 1 Modic changes. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

关键词： Timed Up and Go   Accelerometer   Parkinson's disease   Postural instability gait difficulty   Falls   BALANCE CONFIDENCE   EXECUTIVE FUNCTION   OLDER-ADULTS   PEOPLE   GAIT   ACCELEROMETER   DETERMINANTS   PERFORMANCE   IMPAIRMENT   MOBILITY  

摘要： Parkinson's disease (PD) is clinically highly heterogeneous, often divided into tremor dominant (TD) and postural instability gait difficulty (PIGD). To better understand these subtypes and to help stratify patients, we applied an objective marker, i.e., an instrumented version of the traditional "Timed Up and Go" test (iTUG). It is not known whether the iTUG is sensitive to PD motor phenotypes or what are its behavioral and cognitive correlates. Subjects performed the iTUG wearing a body-fixed sensor. Subcomponents were studied including walking, transitions and turning. Gait, balance and cognitive function and the associations between iTUG, behavioral and cognitive domains were assessed. We also compared two representative subtypes, with minimal symptom overlap, referred to here as predominant PIGD (p-PIGD) and predominant TD (p-TD). One hundred and six patients with PD performed the iTUG. Significant correlations were found between iTUG measures and the PIGD score, but not with TD score. Thirty p-PIGD and 31 p-TD patients were identified. Both groups were similar with respect to age and disease duration (p > 0.75). The p-PIGD patients took significantly longer to complete the iTUG (p = 0.026), used more steps (p = 0.031), albeit with similar step duration (p = 0.936). In the sit-to-stand transition, the p-PIGD patients exhibited lower anterior-posterior jerk (p = 0.04) and lower pitch range (p = 0.012). During the turn, the p-PIGD patients had a lower yaw amplitude (p < 0.038). Cognitive domains were correlated with iTUG measures in the p-PIGD patients, but not in the p-TD. These findings demonstrate that a single sensor can identify axial and cognitive correlates using subcomponents of the iTUG and reveals subtle alterations between the PD motor subtypes.

关键词： Flywheel and electrical clutch   FES-cycling   Fuzzy logic control   Assist mechanism   Functional electrical stimulation-based rehabilitation   Muscle force-drop indicator   NEURAL-NETWORK CONTROL   SPINAL-CORD-INJURY   NEUROMUSCULAR STIMULATION   EXERCISE   PARAPLEGICS   MUSCLE   LEG   ERGOMETER   RESPONSES   BENEFITS  

摘要： A new assist mechanism, represented by a flywheel and an electrical clutch, is developed and evaluated, in simulation studies, to assist paralysed legs during functional electrical stimulation (FES)-based cycling exercise in a closed-loop control configuration. The flywheel is engaged and disengaged, by the clutch, to assist or retard the cycling when necessary. The flywheel engages with the crank to absorb the surplus energy, produced by stimulating the leg, store it as kinetic energy and slow down the movement. Also, it engages again to use the same stored energy to assist the leg and speed up the cycling. A comparative assessment of FES-cycling, using fuzzy logic control, is carried out with and without the new assist mechanism. Clinically recorded data is used to derive a force-drop indicator for assessment purposes. Although the stimulation intensity is slightly increased, the indicator showed 14%-17% muscle fatigue delay with the new mechanism as compared with cycling without assistance. This mechanism is promoting prolonged FES-cycling and increased work rate for paraplegics by delaying the occurrence of muscle fatigue. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Cyclooxygenase   Up(4)A   Thromboxane   Type 2 diabetes   Vasoconstriction   VASCULAR SMOOTH-MUSCLE   MESENTERIC-ARTERIES   ENDOTHELIAL DYSFUNCTION   KINASE   MECHANISMS   RELAXATION   EXPRESSION   PROTEIN   MODEL   TONE  

摘要： The dinucleotide uridine adenosine tetraphosphate (Up(4)A), which has both purine and pyrimidine moieties, was reported as a novel endothelium-derived contracting factor. Recently, growing evidence has suggested that Up(4)A plays an important role in regulation of the cardiovascular function. We previously demonstrated that Up(4)A-induced vasoconstrictions are altered in arteries from DOCA-salt hypertensive rats. We have assessed responses to Up(4)A shown by renal arteries from type 2 diabetic Goto-Kakizaki (GK) rats (42-46 weeks old) and identified the molecular mechanisms involved. Concentration-dependent contractions to Up(4)A were greater in renal arterial rings from the GK than age-matched control Wistar group. In both groups, the inhibition of nitric oxide synthase (with N-G-nitro-L-arginine) increased the response to Up(4)A, whereas the inhibition of cyclooxygenase (COX) (with indomethacin) decreased the response. Specific inhibitors of COX-1 (valeroyl salicylate) and COX-2 (NS398), a thromboxane (TX) receptor (TP) antagonist (SQ29548), and P2 receptor antagonist (suramin) also decreased the response to Up(4)A. Protein expressions of COXs in renal arteries were greater in the GK than Wistar group. The production of TXB2 (a metabolite of TXA(2)) by Up(4)A did not differ between these groups. Concentration-dependent contractions to U46619, an agonist of the TP receptor, were greater in renal arteries from the GK than Wistar group. The expression of P2X(1) and P2Y(2) receptors did not differ between these groups. These results suggest that enhancement of the Up(4)A-induced contraction in renal arteries from GK rats may be attributable to the increased activation of COXs/TP receptor signaling.

关键词： Anodised aluminium   PTFE transfer   Lip seal   Silicone grease   Wear   TRANSFER FILMS   COMPOSITES  

摘要： Pneumatic clutch actuators in trucks transform the force applied on the clutch pedal into the force acting on the clutch. The actuator consists of an anodised aluminium cylinder in which a piston, with a rubber lip seal and a PTFE guiding ring mounted on it, slides. The system is lubricated with silicone-grease before assembly. Wear of the lip seal will lead to a deteriorated sealing capacity, and ultimately failure. A test setup is used to evaluate the effect of silicone grease amount on friction performance, PTFE transfer and rubber lip seal wear. Reciprocating sliding and vibration tests were performed. The surfaces of cylinders, guiding rings and lip seals were studied by SEM and ESCA. The friction level is highly dependent on the amount of grease in the contact area. During sliding, grease is pushed out from or dragged into the contact area, resulting in a fluctuating friction. Furthermore, even with grease lubrication, PTFE transfer to the aluminium surface occurs. A triple transfer from guiding ring, to aluminium surface, to lip seal, to another part of the aluminium surface was observed. Finally, although the unstable lubricating effect, it was found that the grease protects the lip seal from wear. (C) 2013 Elsevier B.V. All rights reserved.

关键词： brood parasitism   cuckoo   egg coloration   egg mimicry   great reed warbler   CUCKOO CUCULUS-CANORUS   GREAT REED WARBLERS   COMMON CUCKOO   ACROCEPHALUS-SCIRPACEUS   VISUAL PIGMENTS   COLOR PATTERNS   OIL DROPLETS   REJECTION   MIMICRY   VISION  

摘要： Interspecific brood parasitism represents a prime example of the coevolutionary arms race where each party has evolved strategies in response to the other. Here, we investigated whether common cuckoos (Cuculus canorus) actively select nests within a host population to match the egg appearance of a particular host clutch. To achieve this goal, we quantified the degree of egg matching using the avian vision modelling approach. Randomization tests revealed that cuckoo eggs in naturally parasitized nests showed lower chromatic contrast to host eggs than those assigned randomly to other nests with egg-laying date similar to naturally parasitized clutches. Moreover, egg matching in terms of chromaticity was better in naturally parasitized nests than it would be in the nests of the nearest active non-parasitized neighbour. However, there was no indication of matching in achromatic spectral characteristics whatsoever. Thus, our results clearly indicate that cuckoos select certain host nests to increase matching of their own eggs with host clutches, but only in chromatic characteristics. Our results suggest that the ability of cuckoos to actively choose host nests based on the eggshell appearance imposes a strong selection pressure on host egg recognition.

关键词： 汽车行业   离合器位置传感器   商业计划书   风险管理  

摘要： 本商业计划书着重从战略和商业计划角度来阐述DH公司如何根据市场的现状与趋势，结合自身的优势与环境的机会，使用蓝海战略和差异化战略迅速地切入离合器位置传感器市场。DH是一家初创性公司，DH公司是一家专注于汽车电子电器产品研发、生产和技术服务的高新科技公司。DH公司研发的离合器位置传感器具有独立知识产权，符合ISO26262 ASILD安全标准，成本低、寿命长。以SWOT的分析方法对DH公司的优势和劣势进行了分析。论文采用SLEPT方法对宏观环境进行了分析，又根据波特五力模型对DH公司所在汽车行业环境进行了分析。\n 论文对DH公司客户进行多角度分析，根据市场规模和客户分类，提出了不同的客户关系管理方式。论文对DH公司细分市场竞争对手从市场定位、产品性能比较、定价策略和渠道策略四个方面进行了分析，并基于SWOT矩阵，选择S-O增长战略--最优成本供应商战略。论文阐述了DH公司三年内的经营目标，为了支持目标达成，所制定的人力资源战略和经营管理战略。同时介绍了离合器位置传感器项目进展状况。论文采用4P理论对DH公司产品市场开发策略进行了阐述，并对销售模式、销售团队建设与激励措施进行了介绍。论文对DH融资方案、资金使用计划及离合器位置传感器投资收益进行了阐述。对DH公司目前面临的各种风险进行了分析，并提出了相应的对策。

关键词： 传动机构   变位斜齿轮   温度场分析   有限元模型   热变形  

摘要： 齿轮传动机构通常处于高速重载的工作状态，在正常工作过程中，由于齿轮啮合运动产生的摩擦热以及轴承转动产生的摩擦热，传动机构温度会变得很高;同时由于润滑油的冷却作用，其温度会保持平衡状态。齿轮传动机构在工作过程中工作环境和工作参数不可能保持一成不变，这些变化会对齿轮的温度产生明显的影响，造成润滑油膜的破裂，使齿面磨损加剧，引起胶合;过高的温度还会使齿轮、轴承和轴产生热变形，造成齿轮传动机构承载能力的下降。使用传统的方法进行齿轮传动机构的温度场计算只能得到各机构的平均温度，而且计算所使用的部分参数是估算的，计算结果并不精确，因此采用有限元方法进行齿轮传动机构的温度场分析是十分必要的。\n 对变位斜齿轮副进行稳态温度场分析，采用ANSYS建立变位斜齿轮副的有限元模型，通过齿轮的材料参数和工况参数计算出进行温度场分析所需要的热载荷，分别在不同的环境温度、齿轮转速、齿轮转矩下分析得出相应工况参数下变位斜齿轮副的温度场分布以及齿轮副的最高、最低、平均温度，为变位斜齿轮副的工况参数设计提供依据。\n 对变位斜齿轮副进行瞬态温度场分析研究，分别针对齿轮副三种变化的工作状态:环境温度、齿轮转速、转矩随时间历程变化时齿轮副的温度场变化情况进行模拟，得到齿轮副温度场的变化和分布规律以及最有可能使齿轮因胶合而失效的部位，为齿轮传动机构的设计优化提供了可靠保证。\n 通过对角接触球轴承进行受力分析得到轴承的摩擦热源大小以及传热的边界条件，采用ANSYS建立了轴承的有限元模型，针对轴承在工作时的摩擦生热以及与齿轮的热传导过程进行有限元分析，得到轴承的三维稳态温度分布。\n 对齿轮传动机构整体进行温度场分析，通过APDL语言对传动机构中齿轮、轴进行加载，模拟出齿轮啮合以及轴承与轴、齿轮与轴的热交换关系，得到齿轮传动机构整体的稳态温度场分布，为研究齿轮传动机构的热变形提供温度依据。

关键词： 离合器   摩擦片   汽车起步   热负荷特性   传动系统  

摘要： 离合器是汽车传动系统重要的组成部件，其主要功用就是在车辆转矩传递过程中，保证汽车顺利起步、传递发动机输出转矩、防止相关部件出现过载;因此，其重要性不言而喻。在行驶工况下，在驾驶员每一次进行换挡时，离合器主、从动盘间都会产生滑转，由此产生的热量如果无法有效并及时的散发，会对离合器甚至整个汽车传动系统的稳定性和可靠性产生影响。所以，在离合器接合过程当中摩擦副的温升以及因约束产生的变形和应力进行分析具有重要意义。\n 本文通过对离合器在汽车起步时接合特性的分析，利用MATLAB/Simulink建立起传动系统的动力学模型。仿真计算出急起步、正常起步、坡道起步三种工况下离合器接合产生的滑磨功以及滑磨功率，并结合理论计算确定了压盘和摩擦片表面的热流密度边界条件。\n 对SACH MF215型离合器盖总成进行测绘，忽略铆钉，传动片，支撑环等零件，利用CATIA建立压盘和摩擦片的三维模型。将简化后的模型导入CFX，建立离合器摩擦副的CFD模型，利用ICEM进行网格划分，仿真计8种转速下，压盘和摩擦片各个部分的空气流动情况，并以此为依据计算瞬态热分析的边界条件。\n 根据前文计算出的边界条件对压盘和摩擦片进行瞬态温度场分析，分析计算出三种起步条件下的温度变化。将温度载荷导入到结构分析中，对压盘和摩擦片进行热结构耦合分析，仿真计算出离合器接合过程中的应力分布以及变形情况。\n 最后，针对压盘在起步过程中应力集中现象明显，翘曲变形严重的情况，有针对性的对其进行结构的改进，改进后最大应力值降低超过12％，翘曲变形量也降低了7.5％，改进效果明显，提高了离合器工作的可靠性。