In ground vehicles, the brake is an essential system to ensure the safety of movement. Multiple braking mechanisms have been introduced for use in vehicles. This study explores the potential of using magneto-rheologic...In ground vehicles, the brake is an essential system to ensure the safety of movement. Multiple braking mechanisms have been introduced for use in vehicles. This study explores the potential of using magneto-rheological fluid (MRF) brakes in automotive applications. MRF brakes offer controllable braking force due to a magnetic field, but their use is limited by simulation challenges. In this study, a 7-tooth MRF brake model is proposed. The brake model is simulated in Altair Flux software to analyze magnetic field distribution, braking torque, and its variation under different currents and disc speeds. The simulation conditions also consider both viscous and electromagnetic torque components. Then, the results are analyzed across different brake regions, including rotor, stator, and fluid gap. These results provide valuable insights for designing, manufacturing, installing, and testing MRF brakes for automotive use.展开更多
This study provides a systematic analysis of the bilateral trade relationships between China and the Mekong River Basin （ MRB ） countries and the new phenomenon where China＇s foreign direct investment（FDI） flows ...This study provides a systematic analysis of the bilateral trade relationships between China and the Mekong River Basin （ MRB ） countries and the new phenomenon where China＇s foreign direct investment（FDI） flows to these countries in the past few years. The paper highlights the new development of China＇s trade with the MIKB countries and reviews the bilateral trade that has been substantially increasing from US S3.35 billion in 2000 to US $18.39 billion in 2007. The paper also explores the features of trade composition between the two sides. China＇s exports have largely concentrated on the manufactured goods while the exports of M1KB countries to China have been natural resources and agricultural goods, which reflects the relative comparative advantages for China and MRB countries and further reinforces the important strategy for the MRB countries to develop their industrialization further and increase their manufacturing capacity. Lastly, the overall results suggest that the impact of China＇s trades to the MRB countries is positive, but not as strong as currently expected.展开更多
Time-delay of magnetorheological elastomer bearing(MRB) can bring structural response menace to bridges. This paper investigates a bridge pier-bearing semi-active-coupling control method based on model predictive cont...Time-delay of magnetorheological elastomer bearing(MRB) can bring structural response menace to bridges. This paper investigates a bridge pier-bearing semi-active-coupling control method based on model predictive control(MPC). The presented strategy takes the structure prediction model to predict the state responses of the controlled plant in a period of future time. Then, the control law can be determined by solving a finite horizon optimization problem. The peak shearing force of pier top, the displacement and the acceleration of beam are chosen as control goals, and the vibration isolation rate is applied to characterize the vibration isolation effect.It is noted that MPC method naturally takes the time-delay and uncertain interference into consideration, and significantly improves the control performance of the system. Finally, the numerical example is described and the seismic response of isolated bridge based on MRB is analyzed. The simulation results show that predictive control can be used to control the time-delay of bridge system in different degrees. The best control performance is at0.4 s. Even if the time-delay reaches 2 s, it is still good. Therefore, the control method significantly reduces the adverse effects of time-delay on the system, and has a good vibration isolation performance.展开更多
The glacier mass balance(GMB)is an important link between climate and water resources and has remarkable regulatory functions in river runoff.To simulate changes of the GMB and to analyze the recharge rates of glacier...The glacier mass balance(GMB)is an important link between climate and water resources and has remarkable regulatory functions in river runoff.To simulate changes of the GMB and to analyze the recharge rates of glacier meltwater to runoff in the Manas River Basin(MRB)during 2000-2016,MOD11C3,TRMM 3B43 and other multi-source remote sensing data were used to drive the degree-day model.The results showed that:(1)the accuracy of the remote sensing meteorological data can be corrected effectively by constructing the temperature and precipitation inversion models,and the characteristics of glacial climate can be finely described through downscaling.The average annual temperature was-7.57°C and the annual precipitation was 410.71 mm in the glacier area of the MRB.The zone at an altitude of about 4200 m was a severe climate change zone,and above and below that zone,the temperature drop rates were-0.03°C/100 m and-0.57°C/100 m,respectively,while precipitation gradients were-2.66 mm/100 m and 4.89 mm/100 m,respectively.(2)The overall GMB was negative with a cumulative GMB of up to-9811.19 mm w.e.and the average annual GMB fluctuated between-464.85 and-632.19 mm w.e.Besides,the glacier melted slowly during 2000-2002 and 2008-2010,but rapidly for 2002-2008 and 2010-2016,while the most serious loss of the glacier occurred in 2005-2009.Moreover,the vertical changes of the GMB increased at 244.83 mm w.e./100 m in the ablation zone but only at 18.77 mm w.e./100 m in the accumulation zone.(3)The intraannual runoff strongly responded to the change of the GMB especially in July and August when the loss of the GMB accounted for 75.4%of the annual loss,and when runoff accounted for 55.1%of the annual total.Due to differences in the annual precipitation and snow meltwater outside the glacier,the interannual glacier meltwater recharge rates fluctuated between 19%and 31%.The recharge rate of glacier meltwater to runoff in the MRB was close to that for other basins in the Tianshan Mountains,which may be used as a basis to confirm the reliability of the estimated GMB results.Furthermore,based on the present findings,it is recommended that the research community pursue studies on the GMB in other alpine river basins.展开更多
文摘In ground vehicles, the brake is an essential system to ensure the safety of movement. Multiple braking mechanisms have been introduced for use in vehicles. This study explores the potential of using magneto-rheological fluid (MRF) brakes in automotive applications. MRF brakes offer controllable braking force due to a magnetic field, but their use is limited by simulation challenges. In this study, a 7-tooth MRF brake model is proposed. The brake model is simulated in Altair Flux software to analyze magnetic field distribution, braking torque, and its variation under different currents and disc speeds. The simulation conditions also consider both viscous and electromagnetic torque components. Then, the results are analyzed across different brake regions, including rotor, stator, and fluid gap. These results provide valuable insights for designing, manufacturing, installing, and testing MRF brakes for automotive use.
文摘This study provides a systematic analysis of the bilateral trade relationships between China and the Mekong River Basin （ MRB ） countries and the new phenomenon where China＇s foreign direct investment（FDI） flows to these countries in the past few years. The paper highlights the new development of China＇s trade with the MIKB countries and reviews the bilateral trade that has been substantially increasing from US S3.35 billion in 2000 to US $18.39 billion in 2007. The paper also explores the features of trade composition between the two sides. China＇s exports have largely concentrated on the manufactured goods while the exports of M1KB countries to China have been natural resources and agricultural goods, which reflects the relative comparative advantages for China and MRB countries and further reinforces the important strategy for the MRB countries to develop their industrialization further and increase their manufacturing capacity. Lastly, the overall results suggest that the impact of China＇s trades to the MRB countries is positive, but not as strong as currently expected.
基金the Chongqing Outstanding Youth Found(No.cstc2014jcyjjq40004)the Science and Technology Research Project of the Chongqing Municipal Education Committee(No.KJ1600416)+2 种基金the National Natural Science Foundation of China(No.11372366)the Chongqing Postgraduate Research and Innovation Project(No.CYS17123)the Research Project of Chongqing Science and Technology Commission(No.cstc2018jcyjAX0691)
文摘Time-delay of magnetorheological elastomer bearing(MRB) can bring structural response menace to bridges. This paper investigates a bridge pier-bearing semi-active-coupling control method based on model predictive control(MPC). The presented strategy takes the structure prediction model to predict the state responses of the controlled plant in a period of future time. Then, the control law can be determined by solving a finite horizon optimization problem. The peak shearing force of pier top, the displacement and the acceleration of beam are chosen as control goals, and the vibration isolation rate is applied to characterize the vibration isolation effect.It is noted that MPC method naturally takes the time-delay and uncertain interference into consideration, and significantly improves the control performance of the system. Finally, the numerical example is described and the seismic response of isolated bridge based on MRB is analyzed. The simulation results show that predictive control can be used to control the time-delay of bridge system in different degrees. The best control performance is at0.4 s. Even if the time-delay reaches 2 s, it is still good. Therefore, the control method significantly reduces the adverse effects of time-delay on the system, and has a good vibration isolation performance.
基金National Natural Science Foundation of China,No.41761108,No.41771077。
文摘The glacier mass balance(GMB)is an important link between climate and water resources and has remarkable regulatory functions in river runoff.To simulate changes of the GMB and to analyze the recharge rates of glacier meltwater to runoff in the Manas River Basin(MRB)during 2000-2016,MOD11C3,TRMM 3B43 and other multi-source remote sensing data were used to drive the degree-day model.The results showed that:(1)the accuracy of the remote sensing meteorological data can be corrected effectively by constructing the temperature and precipitation inversion models,and the characteristics of glacial climate can be finely described through downscaling.The average annual temperature was-7.57°C and the annual precipitation was 410.71 mm in the glacier area of the MRB.The zone at an altitude of about 4200 m was a severe climate change zone,and above and below that zone,the temperature drop rates were-0.03°C/100 m and-0.57°C/100 m,respectively,while precipitation gradients were-2.66 mm/100 m and 4.89 mm/100 m,respectively.(2)The overall GMB was negative with a cumulative GMB of up to-9811.19 mm w.e.and the average annual GMB fluctuated between-464.85 and-632.19 mm w.e.Besides,the glacier melted slowly during 2000-2002 and 2008-2010,but rapidly for 2002-2008 and 2010-2016,while the most serious loss of the glacier occurred in 2005-2009.Moreover,the vertical changes of the GMB increased at 244.83 mm w.e./100 m in the ablation zone but only at 18.77 mm w.e./100 m in the accumulation zone.(3)The intraannual runoff strongly responded to the change of the GMB especially in July and August when the loss of the GMB accounted for 75.4%of the annual loss,and when runoff accounted for 55.1%of the annual total.Due to differences in the annual precipitation and snow meltwater outside the glacier,the interannual glacier meltwater recharge rates fluctuated between 19%and 31%.The recharge rate of glacier meltwater to runoff in the MRB was close to that for other basins in the Tianshan Mountains,which may be used as a basis to confirm the reliability of the estimated GMB results.Furthermore,based on the present findings,it is recommended that the research community pursue studies on the GMB in other alpine river basins.
