Hydromechanical continuously variable transmission is capable of bearing large torque and has wide transmission range, which is suitable for high-power tractors. Dynamic characteristics could influence the tractor life, especially in a high-power tractor. Wet clutch is the crucial component in the HMCVT, which could smooth and soft power transmission. Therefore, it is important to study the dynamic characteristics and implement the wet clutch test of HMCVT. In this paper, AMESim is used to establish virtual models of gearbox, pump-controlled hydraulic motor (...) system, and shifting hydraulic system. Then, a simulation study of tractor operation under working condition is carried out. The internal and external meshing forces of the planetary row are analyzed. Finally, the wet clutch engagement process of HMCVT in the high-power tractor is tested to verify the oil pressure. The simulation results show that the values of internal and external meshing force become larger as the throttle opening increases. At the moment of shifting change, the meshing forces of the planetary gear have great impact. The clutch test shows that the trend of the oil filling curve obtained from the bench test is similar to that obtained from the theoretical curve, which verifies the simulation results. (shrink)

We examined whether and how managerial ability affects the relationship between customer concentration and corporate performance. Based on a novel measure of managerial ability, we found that customer concentration has a significant negative effect on corporate performance, while managerial ability can mitigate this effect. The negative effect of customer concentration is only significant in the subsample of low ability and lower efficiency in asset utilization, while the moderating effect of managerial ability is significant for all levels of asset utilization efficiency (...) and more significant for firms with a lower gross margin. The results are robust to numerous robustness tests and endogeneity concerns. Additional analysis of mechanisms shows that in addition to superior operating ability, competent managers select major customers who are more beneficial to their company and decrease the sensitivity of their research and development investment to customers. These findings indicate that the heterogeneity of managerial ability plays an important role in the supplier–customer context when the supplier firm generally faces one or more concentrated customers. (shrink)

本书对痕迹鉴定、文书鉴定、法医鉴定、司法精神病鉴定、司法物理学和化学鉴定、司法会计鉴定及其它与司法有关的鉴定领域进行介绍。.

本书从中国是一个超稳定结构假说出发,讨论中国历代政治文化的特点及其演化机制。通过比较魏晋南北朝时期佛教传入与近代西方文明扩张这两次重大的外来文化冲击,探讨中国文化融合消化外来文化所具有的共同模式,并进 而揭示二十世纪中国现代思想的起源.

Co-speech gestures are closely connected to speech, but little attention has been paid to the associations between gesture and L2 speech performance. This study explored the associations between four types of co-speech gestures and the meaning, form, and discourse dimensions of L2 speech performance. Gesture and speech data were collected by asking 61 lower-intermediate English learners whose first language is Chinese to retell a cartoon clip. Results showed that all the four types of co-speech gestures had positive associations with meaning (...) and discourse L2 speech measures but no association with form-related speech measures, except the positive association between metaphorics and the percentage of error-free clauses. The findings suggest that co-speech gestures may have a tighter connection with meaning construction in producing L2 speech. (shrink)

This article discusses the introduction of the Western concept of democracy to China from the late nineteenth century to the first two decades of the twentieth century and the formation of the Chinese concept of democracy. It suggests that the modern Chinese concept of democracy underwent two formational phases. At the beginning, the traditional elite tended to interpret Western democracy in terms of republicanism. During the New Culture Movement, the new generation of intellectuals began a selective reconstruction of the notion (...) of democracy, which resulted in the modern Chinese view of democracy characterized by popular participation and elections. With funding from several research grants, we have created a database of texts related to modern Chinese political thought. By carrying out a frequency count and meaning analysis of the terms gonghe and minzhu, this article examines the roots of the replacement of the concept of republicanism by democracy from the perspective of intellectual history. (shrink)