Through thermal test, cold state experiment, analysis and simulation of thermal process, the gas flow distribution in pelletizing shaft furnace （PSF） was discussed. The results show that there are five flowing trend...Through thermal test, cold state experiment, analysis and simulation of thermal process, the gas flow distribution in pelletizing shaft furnace （PSF） was discussed. The results show that there are five flowing trends among them, the downward roasting gas and the upward cooling gas are the most unsteady, which influence flow distribution greatly. Among the operating parameters, the ratio of inflow is a key factor affecting the flow distribution. The roasting and cooling gases will entirely flow into the roasting zone and internal vertical air channels （IVAC）, respectively, if the ratio of inflow is critical. From such a critical operating condition increasing roasting gas flow or decreasing cooling gas flow, the roasting gas starts flowing downwards so as to enter the inside of IVAC the greater the ratio of inflow, the larger the downward flowrate. Among constructional parameters, the width of roasting zone b1, width of IVAC b2 and width of cooling zone b3, and the height of roasting zone h1, height of soaking zone h2 and height of cooling zone hs are the main factors affecting flow distribution. In case the ratio of b2/b3, or h3/h2, or h1/h2 is increased, the upward cooling gas tends to decrease while the downward roasting gas tends to increase with a gradual decrease in the ratio of inflow.展开更多
GaN ultraviolet(UV)p-i-n photodetectors(PDs)with a 40 nm thin p-GaN contact layer are fabricated on sapphire substrates,which exhibit enhanced quantum efficiency especially in a deep-UV wavelength range.The PDs show g...GaN ultraviolet(UV)p-i-n photodetectors(PDs)with a 40 nm thin p-GaN contact layer are fabricated on sapphire substrates,which exhibit enhanced quantum efficiency especially in a deep-UV wavelength range.The PDs show good rectification behavior and low dark current in pA level for reverse bias up to-10 V.Under zero bias,the maximum quantum efficiency of the PD at 360 nm is close to 59.4%with a UV/visible rejection ratio more than 4 orders of magnitude.Even at a short wavelength of 280 nm,the quantum efficiency of the PD is still around 47.5%,which is considerably higher than that of a control device with a thicker p-GaN contact layer.The room temperature thermal noise limited detectivity of the PD is calculated to be~4.96×10^(14) cm·Hz^(1/2)W^(-1).展开更多
基金ItemSponsored by National Natural Science Foundation of China (50334020) National Key Fundamental Research andDevelopment Project of China (2000026300)
文摘Through thermal test, cold state experiment, analysis and simulation of thermal process, the gas flow distribution in pelletizing shaft furnace （PSF） was discussed. The results show that there are five flowing trends among them, the downward roasting gas and the upward cooling gas are the most unsteady, which influence flow distribution greatly. Among the operating parameters, the ratio of inflow is a key factor affecting the flow distribution. The roasting and cooling gases will entirely flow into the roasting zone and internal vertical air channels （IVAC）, respectively, if the ratio of inflow is critical. From such a critical operating condition increasing roasting gas flow or decreasing cooling gas flow, the roasting gas starts flowing downwards so as to enter the inside of IVAC the greater the ratio of inflow, the larger the downward flowrate. Among constructional parameters, the width of roasting zone b1, width of IVAC b2 and width of cooling zone b3, and the height of roasting zone h1, height of soaking zone h2 and height of cooling zone hs are the main factors affecting flow distribution. In case the ratio of b2/b3, or h3/h2, or h1/h2 is increased, the upward cooling gas tends to decrease while the downward roasting gas tends to increase with a gradual decrease in the ratio of inflow.
基金Supported by the National Basic Research Program of China under Grant Nos 2010CB327504,2011CB922100 and 2011CB301900the National Natural Science Foundation of China under Grant Nos 60825401,60936004,11104130 and 60990311.
文摘GaN ultraviolet(UV)p-i-n photodetectors(PDs)with a 40 nm thin p-GaN contact layer are fabricated on sapphire substrates,which exhibit enhanced quantum efficiency especially in a deep-UV wavelength range.The PDs show good rectification behavior and low dark current in pA level for reverse bias up to-10 V.Under zero bias,the maximum quantum efficiency of the PD at 360 nm is close to 59.4%with a UV/visible rejection ratio more than 4 orders of magnitude.Even at a short wavelength of 280 nm,the quantum efficiency of the PD is still around 47.5%,which is considerably higher than that of a control device with a thicker p-GaN contact layer.The room temperature thermal noise limited detectivity of the PD is calculated to be~4.96×10^(14) cm·Hz^(1/2)W^(-1).
