A new combined soft switching technique and a novel topology of aeronautical static inverter with high frequency pulse dc link are proposed in this paper, namely an electrical isolated converter can realize soft swi...A new combined soft switching technique and a novel topology of aeronautical static inverter with high frequency pulse dc link are proposed in this paper, namely an electrical isolated converter can realize soft switching of two stage cascade converters. It lays technical foundation for high power density, high efficiency and low cost aeronautical static inverter. The operation and design approach of this topology are carefully analyzed and studied. The validity of this topology is verified by simulation and test.展开更多
Focused upon the dynamic changing regularity and tendency of overburden movement and bed separation developing during the strip mining and stoping under rail- ways were simulated by ANSYS model.The results show that m...Focused upon the dynamic changing regularity and tendency of overburden movement and bed separation developing during the strip mining and stoping under rail- ways were simulated by ANSYS model.The results show that movement and rheology developing of key strata is one of the main reasons to cause surface subsidence and to further induce deformation of surface railways.It provids a basis for taking efficient meas- ures to control the deformation of surface railways.展开更多
The review and numerical analysis had been conducted further understand the deformation and failure beahviour of roadway junctions,associated with the different geometrical characteristics,various depth of cover,diffe...The review and numerical analysis had been conducted further understand the deformation and failure beahviour of roadway junctions,associated with the different geometrical characteristics,various depth of cover,different mechanical properties around the junction and different construction sequences as well as different construction ad- vances during the roadway junction construction.The results confirme that the simple un- derground structure is more stable than complicated structures,and comparing with dif- ferent geometrical shapes of the two-dimensional roadway junctions,the most unstable one is the four way cross junction,which is the most commonly used in coal mines.On the other hand,the stability of the junction is not linearly related to the depth of cover,the sig- nificant effect only occurred when the depth of cover reached to 1 000 m.Also,with grad- ual degradation of rock mass,the deformation and failure around the junction increased significantly and nonlinearly.The modeling also conductes on the construction sequence for the junction,it is suggested that,during the junction construction,all the additional roadway should be constructed with the direction of moving away from,rather than for- ward to the junction.Finally,the construction advance is also considered for the junction development.It is suggested that when the construction is carried out around the junction, a small excavation advance,such as 1 m or 2 m is adopted for keeping small interruption on the existed roadway or junction.展开更多
This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of thi...This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of this phenomenon were used： the pressure profile using the Kiel total pressure probe, the velocity profile using the CTA （constant temperature anemometry） probe and the visualization of the flow field using the hot film and the thermo camera, The experimental results with and without the influence of the synthetic jet were compared, as well the impact of the phase shift of the neighbouring synthetic jets. As a reference case, the flow around the hump without the influence of the synthetic jet was selected. The results of the measurement are presented in figures and compared.展开更多
文摘A new combined soft switching technique and a novel topology of aeronautical static inverter with high frequency pulse dc link are proposed in this paper, namely an electrical isolated converter can realize soft switching of two stage cascade converters. It lays technical foundation for high power density, high efficiency and low cost aeronautical static inverter. The operation and design approach of this topology are carefully analyzed and studied. The validity of this topology is verified by simulation and test.
基金the National Natural Science Funds Committee(50174035)
文摘Focused upon the dynamic changing regularity and tendency of overburden movement and bed separation developing during the strip mining and stoping under rail- ways were simulated by ANSYS model.The results show that movement and rheology developing of key strata is one of the main reasons to cause surface subsidence and to further induce deformation of surface railways.It provids a basis for taking efficient meas- ures to control the deformation of surface railways.
文摘The review and numerical analysis had been conducted further understand the deformation and failure beahviour of roadway junctions,associated with the different geometrical characteristics,various depth of cover,different mechanical properties around the junction and different construction sequences as well as different construction ad- vances during the roadway junction construction.The results confirme that the simple un- derground structure is more stable than complicated structures,and comparing with dif- ferent geometrical shapes of the two-dimensional roadway junctions,the most unstable one is the four way cross junction,which is the most commonly used in coal mines.On the other hand,the stability of the junction is not linearly related to the depth of cover,the sig- nificant effect only occurred when the depth of cover reached to 1 000 m.Also,with grad- ual degradation of rock mass,the deformation and failure around the junction increased significantly and nonlinearly.The modeling also conductes on the construction sequence for the junction,it is suggested that,during the junction construction,all the additional roadway should be constructed with the direction of moving away from,rather than for- ward to the junction.Finally,the construction advance is also considered for the junction development.It is suggested that when the construction is carried out around the junction, a small excavation advance,such as 1 m or 2 m is adopted for keeping small interruption on the existed roadway or junction.
文摘This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of this phenomenon were used： the pressure profile using the Kiel total pressure probe, the velocity profile using the CTA （constant temperature anemometry） probe and the visualization of the flow field using the hot film and the thermo camera, The experimental results with and without the influence of the synthetic jet were compared, as well the impact of the phase shift of the neighbouring synthetic jets. As a reference case, the flow around the hump without the influence of the synthetic jet was selected. The results of the measurement are presented in figures and compared.
