Foreign Ownership and International Trade Performance in China

We investigate the causal relationship between foreign ownership and international trade performance by comparing foreign-acquired firms with similar domestic-acquired firms in China with regard to changes in their post-acquisition international trade performance.Our findings indicate that foreign ownership significantly enhanced the probability of both exporting and importing,and strongly increased trade value.Foreign ownership took effect from the year of the acquisition and persisted for at least 2 years.It stimulated both processing trade and ordinary trade,and expanded products and trading partners.Post-acquisition trade performance also exhibited heterogeneity based on the different pre-acquisition and post-acquisition ownership.As for the underlying mechanisms,we show that firms experienced significant output expansion,increased export dependence,and eased financial constraints after foreign acquisition.

Vehicle Active Steering Control Research Based on Two-DOF Robust Internal Model Control

Because of vehicle＇s external disturbances and model uncertainties,robust control algorithms have obtained popularity in vehicle stability control.The robust control usually gives up performance in order to guarantee the robustness of the control algorithm,therefore an improved robust internal model control（IMC） algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness.The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties.In order to separate the design process of model tracking from the robustness design process,the improved 2 degree of freedom（DOF） robust internal model controller structure is given from the standard Youla parameterization.Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm,on the basis of a nonlinear vehicle simulation model with a magic tyre model.Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance,which can enhance the vehicle stability and handling,regardless of variations of the vehicle model parameters and the external crosswind interferences.Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.

INTERNAL FLOW IN CROSS-FLOW FAN FOR AIR CONDITIONER

A numerical analytic process is suggested combining direct boundary element methodwith discrete vortex method and internal flow in cross-flow fan calculated. The process considersnot only function of impeller, but also effect of volute casing. Internal flow field of cross-flow fan ispractically measured, and results compared with that from calculation. It shows that the process isexpected to be used in predicting performances of fluid machinery.