An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. Th...An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. The thermal analysis of the flat heat pipe radiator for cooling high-power light emitting diode （LED） array was conducted. The thermal characteristics of the flat heat pipe radiator under the different heat loads and incline angles were investigated experimentally in natural convection. An electro-thermal conversion method was used to measure the junction temperature of the LED chips. It is found that the integral temperature distribution of the flat heat pipe radiator is reasonable and uniform. The total thermal resistance of the flat heat pipe radiator varies in the range of 0.38-0.45 K/W. The junction temperatures of LED chips with the flat heat pipe radiator and with the aluminum board at the same forward current of 0.35 A are 52.5 and 75.2 ℃, respectively.展开更多
In this paper, combining the technologies of Computer Supported Cooperative Work （CSCW）, Workflow and Network, the authors aim to organize virtual distributed cooperative work environment （VDCWE） and expound the r...In this paper, combining the technologies of Computer Supported Cooperative Work （CSCW）, Workflow and Network, the authors aim to organize virtual distributed cooperative work environment （VDCWE） and expound the running mechanism of cooperative workflow and design its algorithm for monitoring of urban subway construction. And then a prototype system was built based on the above,capable of supporting user analyzing, dealing with and managing data of monitoring, and real-timely releasing corresponding information, providing interactive virtual and distributed coordination meet-environment, dynami-cally and transparently, in favor of clients＇ interoperaiility and solving practicing problems, and so on.展开更多
We have investigated the distribution of the electric field in p-i-n GaN avalanche photodiodes under different reverse bias values. type and separate absorption and multiplication （SAM） type We have also analyzed th...We have investigated the distribution of the electric field in p-i-n GaN avalanche photodiodes under different reverse bias values. type and separate absorption and multiplication （SAM） type We have also analyzed the influences of the parameters of each layer, including width and concentration, on the distribution of the electric field, especially on the breakdown voltage. It is found that a relatively high concentration of p-GaN （higher than 1×10^18 cm-3） and low cartier concentration of i-GaN （lower than 5×1016 cm-3） are helpful to restrict the electric field and reduce the breakdown voltage. In a SAM （p-i-n-i-n） structure, a suitable choice should be made for the concentration and thickness of the intermediate n-GaN layer in order to decrease breakdown voltage and prevent the device from degenerating into a p-i-n structure. Finally, the optimized material parameters of each layer are proposed.展开更多
基金Project(50876016) support by the National Natural Science Foundation of China
文摘An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. The thermal analysis of the flat heat pipe radiator for cooling high-power light emitting diode （LED） array was conducted. The thermal characteristics of the flat heat pipe radiator under the different heat loads and incline angles were investigated experimentally in natural convection. An electro-thermal conversion method was used to measure the junction temperature of the LED chips. It is found that the integral temperature distribution of the flat heat pipe radiator is reasonable and uniform. The total thermal resistance of the flat heat pipe radiator varies in the range of 0.38-0.45 K/W. The junction temperatures of LED chips with the flat heat pipe radiator and with the aluminum board at the same forward current of 0.35 A are 52.5 and 75.2 ℃, respectively.
基金Supported by the Innovative Project Foundation of Beijing Urban Construction Group Co.Ltd (No.2001129)the Award of Beijing Investigation & Design Institute for Urban Construction (No.2004207)
文摘In this paper, combining the technologies of Computer Supported Cooperative Work （CSCW）, Workflow and Network, the authors aim to organize virtual distributed cooperative work environment （VDCWE） and expound the running mechanism of cooperative workflow and design its algorithm for monitoring of urban subway construction. And then a prototype system was built based on the above,capable of supporting user analyzing, dealing with and managing data of monitoring, and real-timely releasing corresponding information, providing interactive virtual and distributed coordination meet-environment, dynami-cally and transparently, in favor of clients＇ interoperaiility and solving practicing problems, and so on.
基金supported by the National Science Fund for Distinguished Young Scholars (Grant No. 60925017)the National Natural Science Foundation of China (Grant Nos. 10990100,60836003 and 60776047)
文摘We have investigated the distribution of the electric field in p-i-n GaN avalanche photodiodes under different reverse bias values. type and separate absorption and multiplication （SAM） type We have also analyzed the influences of the parameters of each layer, including width and concentration, on the distribution of the electric field, especially on the breakdown voltage. It is found that a relatively high concentration of p-GaN （higher than 1×10^18 cm-3） and low cartier concentration of i-GaN （lower than 5×1016 cm-3） are helpful to restrict the electric field and reduce the breakdown voltage. In a SAM （p-i-n-i-n） structure, a suitable choice should be made for the concentration and thickness of the intermediate n-GaN layer in order to decrease breakdown voltage and prevent the device from degenerating into a p-i-n structure. Finally, the optimized material parameters of each layer are proposed.
