The evaluation of thermal resistance constitution for packaged A1GaN/GaN high electron mobility transistor （HEMT） by structure function method is proposed in this paper. The evaluation is based on the transient heat...The evaluation of thermal resistance constitution for packaged A1GaN/GaN high electron mobility transistor （HEMT） by structure function method is proposed in this paper. The evaluation is based on the transient heating measurement of the A1GaN/GaN HEMT by pulsed electrical temperature sensitive parameter method. The extracted chip-level and package-level thermal resistances of the packaged multi-finger A1GaN/GaN HEMT with 400μm SiC substrate are 22.5 K/W and 7.2 K/W respectively, which provides a non-invasive method to evaluate the chip-level thermal resistance of packaged A1GaN/GaN HEMTs. It is also experimentally proved that the extraction of the chip- level thermal resistance by this proposed method is not influenced by package form of the tested device and temperature boundary condition of measurement stage.展开更多
The worldwide space industry has entered a new space economy era.The question is how to develop in this new era?This paper tries to answer this question from two aspects:highly reliable and low-cost technology for acc...The worldwide space industry has entered a new space economy era.The question is how to develop in this new era?This paper tries to answer this question from two aspects:highly reliable and low-cost technology for access to space,and the cislunar economic zone.Firstly,the development requirement of the future space transportation system is discussed and the development path to enable high-reliability and a low cost of space transportation system is analyzed.Moreover,the concept of a routine space transportation system is proposed,upon which this paper gives some thoughts to the development of the cislunar economic zone thus embracing the new space economy era.展开更多
Newborn hearing screening is an effective strategy for early identification of hearing loss in the newborn which result in early intervention and best outcome.However implementing universal screening strategy is a cha...Newborn hearing screening is an effective strategy for early identification of hearing loss in the newborn which result in early intervention and best outcome.However implementing universal screening strategy is a challenge in many resource constrained settings.There are various limitations towards successful implementation of hearing screening program in the developing countries.The cost effectiveness of the screening program also needs to be considered in a resource constrained settings.We attempt to provide a viewpoint that can be potentially helpful for the successful implementation of hearing screening in a resource constrained settings of the developing countries.展开更多
长期储能(long-duration energy storage,LDES)技术的不断发展成熟为解决新型电力系统季节性供需不平衡问题提供了有效途径。现有研究对LDES技术经济参数的发展情况和不同组合对LDES配置需求和成本效益的影响尚缺乏精细化分析,难以准确...长期储能(long-duration energy storage,LDES)技术的不断发展成熟为解决新型电力系统季节性供需不平衡问题提供了有效途径。现有研究对LDES技术经济参数的发展情况和不同组合对LDES配置需求和成本效益的影响尚缺乏精细化分析,难以准确探究LDES的灵活性潜力。为此,该文分析考虑技术经济性的LDES规划特性,面向新型电力系统建立内嵌年度8760h全景时序运行模拟的多时间尺度储能协调优化规划模型。算例基于我国西北某区域实际数据,评估LDES技术经济参数的不同组合与LDES成本效益水平、优化配置结构和对短期储能替代作用的关系。结果表明,LDES的成本效益受储能容量成本和放电效率的影响最大,在低碳转型发展背景下引入LDES最多可以降低电力系统40%左右的总成本。展开更多
基金supported by the Natural Science Foundation of Beijing,China (Grant No. 4092005)the National High Technology Research and Development Program of China (Grant No. 2009AA032704)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20091103110006)
文摘The evaluation of thermal resistance constitution for packaged A1GaN/GaN high electron mobility transistor （HEMT） by structure function method is proposed in this paper. The evaluation is based on the transient heating measurement of the A1GaN/GaN HEMT by pulsed electrical temperature sensitive parameter method. The extracted chip-level and package-level thermal resistances of the packaged multi-finger A1GaN/GaN HEMT with 400μm SiC substrate are 22.5 K/W and 7.2 K/W respectively, which provides a non-invasive method to evaluate the chip-level thermal resistance of packaged A1GaN/GaN HEMTs. It is also experimentally proved that the extraction of the chip- level thermal resistance by this proposed method is not influenced by package form of the tested device and temperature boundary condition of measurement stage.
文摘The worldwide space industry has entered a new space economy era.The question is how to develop in this new era?This paper tries to answer this question from two aspects:highly reliable and low-cost technology for access to space,and the cislunar economic zone.Firstly,the development requirement of the future space transportation system is discussed and the development path to enable high-reliability and a low cost of space transportation system is analyzed.Moreover,the concept of a routine space transportation system is proposed,upon which this paper gives some thoughts to the development of the cislunar economic zone thus embracing the new space economy era.
文摘Newborn hearing screening is an effective strategy for early identification of hearing loss in the newborn which result in early intervention and best outcome.However implementing universal screening strategy is a challenge in many resource constrained settings.There are various limitations towards successful implementation of hearing screening program in the developing countries.The cost effectiveness of the screening program also needs to be considered in a resource constrained settings.We attempt to provide a viewpoint that can be potentially helpful for the successful implementation of hearing screening in a resource constrained settings of the developing countries.
文摘长期储能(long-duration energy storage,LDES)技术的不断发展成熟为解决新型电力系统季节性供需不平衡问题提供了有效途径。现有研究对LDES技术经济参数的发展情况和不同组合对LDES配置需求和成本效益的影响尚缺乏精细化分析,难以准确探究LDES的灵活性潜力。为此,该文分析考虑技术经济性的LDES规划特性,面向新型电力系统建立内嵌年度8760h全景时序运行模拟的多时间尺度储能协调优化规划模型。算例基于我国西北某区域实际数据,评估LDES技术经济参数的不同组合与LDES成本效益水平、优化配置结构和对短期储能替代作用的关系。结果表明,LDES的成本效益受储能容量成本和放电效率的影响最大,在低碳转型发展背景下引入LDES最多可以降低电力系统40%左右的总成本。
