提出了一种基于基极电流补偿的具有低温度系数和高电源抑制比的带隙基准电压源结构,通过消除三极管基极电流对基准输出电压温度系数的影响,有效降低了基准的温漂系数,同时通过自偏置电流镜结构和滤波电容提高了基准在全频段的电源抑制比...提出了一种基于基极电流补偿的具有低温度系数和高电源抑制比的带隙基准电压源结构,通过消除三极管基极电流对基准输出电压温度系数的影响,有效降低了基准的温漂系数,同时通过自偏置电流镜结构和滤波电容提高了基准在全频段的电源抑制比(PSRR)。Cadence中利用TSMC 0.18μm工艺进行的仿真结果表明,在-55~125℃的温度范围内,得到9.1×10^(-6)/℃的温漂系数,低频时的电源抑制比达到-80 d B。展开更多
在对传统带隙基准电压源进行理论分析的基础上,结合当前IC设计中对基准电压源低温漂、高电源抑制比的要求,设计了一种超低温漂的带隙基准电压源电路。该电路带有启动电路和高阶温度补偿电路。仿真结果表明,在-55~125℃的温度范围内获得...在对传统带隙基准电压源进行理论分析的基础上,结合当前IC设计中对基准电压源低温漂、高电源抑制比的要求,设计了一种超低温漂的带隙基准电压源电路。该电路带有启动电路和高阶温度补偿电路。仿真结果表明,在-55~125℃的温度范围内获得了1.65×10-6/℃的温漂系数,低频时的电源抑制比达到-62 d B。展开更多
According to the ＂jacking-up＂ theory, which relates the cause of earthquakes to outer core convection ascension bodies, the crust will gradually recover after an earthquake. In such cases, the crust is stretched, th...According to the ＂jacking-up＂ theory, which relates the cause of earthquakes to outer core convection ascension bodies, the crust will gradually recover after an earthquake. In such cases, the crust is stretched, the underground temperature is reduced, precipitation decreases, and drought occurs. In this paper, precipitation is compared with ground temperature and seismic data to determine the spatial and temporal relationship between earthquakes and subsequent droughts. Our objective is to develop a new method of drought prediction. With a few exceptions in location, the analysis of the first drought to occur after the Ms 〉 7 earthquakes in China's Mainland and the adjacent areas since 1950 shows that droughts tended to occur in regions near earthquake epicenters and in the eastern regions of the epicenters at the same latitude within six months after the earthquakes. In addition, and the differences between the starting time of the earthquakes and the droughts nearly share the same probability of 0 to 6 months. After careful analysis of 34 Ms 〉 6.5 earthquakes occurring in western China from 1980 to 2011, we determined that a second drought tends to occur approximately six months following the first drought, indicating a quasi-half-year period. Moreover, the duration of the quasi-half-year fluctuation increases with the magnitude of earthquake, at approximately 2.5 years for Ms 6.5 earthquake and approximately 5 years for Ms 8 earthquake.展开更多
High resistance thin film chip resistors(0603 type) were studied,and the specifications are as follows:1 k? with tolerance about ±0.1% after laser trimming and temperature coefficient of resistance(TCR) less than...High resistance thin film chip resistors(0603 type) were studied,and the specifications are as follows:1 k? with tolerance about ±0.1% after laser trimming and temperature coefficient of resistance(TCR) less than ±15×10-6/℃.Cr-Si-Ta-Al films were prepared with Ar flow rate and sputtering power fixed at 20 standard-state cubic centimeter per minute(sccm) and 100 W,respectively.The experiment shows that the electrical properties of Cr-SiTa-Al deposition films can meet the specification requirements of 0603 ty...展开更多
As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for...As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for ISW identification based on freezing point at the sea surface, and we study spatial distribution of ISW in front of the Amery Ice Shelf (AIS) and its flow path in Prydz Bay by analyzing hydrographic data from Australian cruises in 2001 and 2002, as well as Chinese cruises in 2003, 2005, 2006, and 2008, all being made in the austral summer. The relatively cold and fresh ISW occurred as several discrete water blocks with cold cores in front of the AIS, within the depth range of 100?600 m, under the seasonal thermocline. ISW had obvious temporal and spatial variations and the spatial distribution pattern changed greatly after 2005. Most of ISW was concentrated west of 73°E during 2001 to 2003 and 2006, but it was widespread to east in 2005 and 2008. In all observation years, a small amount of cold ISW always occurs at the west end of the AIS front section, where the coldest ISW in the whole section also occurred in 2001, 2003 and 2006. Considering general cyclonic circulation pattern under the AIS, the ISW flowing out from west end of the AIS front might have experienced the longest cooling period under ice shelf, so it would have the lowest temperature. Analysis of data from meridian sections in Prydz Bay in 2003 implied that ISW in the west could spread north to the continental break along the east flank of the Fram Bank near 70.5°E, mix with the upwelling Circumpolar Deep Water and possibly contribute to the formation of AABW.展开更多
The low resistance PTC ceramic thermistor material with excellent eleectricalproperties are successfully fabricated by raw materials at industrial range made in our country onthe study of its composition expression an...The low resistance PTC ceramic thermistor material with excellent eleectricalproperties are successfully fabricated by raw materials at industrial range made in our country onthe study of its composition expression and fabrication process by using the addition of Nb, La, Y,Ta , microstructure regulator BN and ASTL phase . The composition and its fabrication method arestudied. The relation of electrical properties of the PTC ceramic material to its compositionexpression and its related electrical properties are discussed展开更多
The present work is focused on the relationship between effective segregation coefficient keff and tem- perature of melting zone for purification of phosphorus by zone melting method. Values of keff at four temperatur...The present work is focused on the relationship between effective segregation coefficient keff and tem- perature of melting zone for purification of phosphorus by zone melting method. Values of keff at four temperatures of melting zone are obtained for zone pass n = 1 at travel velocity of molten zone v = 5x 10^-3 m. h^-1 and initial impu- rity concentration C0〈10 μg.g-1, lnkeff is a linear function of 1/T. The keff values of A1, Ca, Cr, Fe, Cd and Sb in- crease with temperatures while that of Mg is almost constant. The purification is acceptable at lower temperature of melting zone such as 323 K. The variations of enthalpy and entropy between impurities and phosphorus in the liq- uid and solid ohases are also 19resented.展开更多
In this paper, by combining a stochastic optimization method with a refrigeration shaft work targeting method,an approach for the synthesis of a heat integrated complex distillation system in a low-temperature process...In this paper, by combining a stochastic optimization method with a refrigeration shaft work targeting method,an approach for the synthesis of a heat integrated complex distillation system in a low-temperature process is presented. The synthesis problem is formulated as a mixed-integer nonlinear programming(MINLP) problem,which is solved by simulated annealing algorithm under a random procedure to explore the optimal operating parameters and the distillation sequence structure. The shaft work targeting method is used to evaluate the minimum energy cost of the corresponding separation system during the optimization without any need for a detailed design for the heat exchanger network(HEN) and the refrigeration system(RS). The method presented in the paper can dramatically reduce the scale and complexity of the problem. A case study of ethylene cold-end separation is used to illustrate the application of the approach. Compared with the original industrial scheme, the result is encouraging.展开更多
文摘提出了一种基于基极电流补偿的具有低温度系数和高电源抑制比的带隙基准电压源结构,通过消除三极管基极电流对基准输出电压温度系数的影响,有效降低了基准的温漂系数,同时通过自偏置电流镜结构和滤波电容提高了基准在全频段的电源抑制比(PSRR)。Cadence中利用TSMC 0.18μm工艺进行的仿真结果表明,在-55~125℃的温度范围内,得到9.1×10^(-6)/℃的温漂系数,低频时的电源抑制比达到-80 d B。
文摘在对传统带隙基准电压源进行理论分析的基础上,结合当前IC设计中对基准电压源低温漂、高电源抑制比的要求,设计了一种超低温漂的带隙基准电压源电路。该电路带有启动电路和高阶温度补偿电路。仿真结果表明,在-55~125℃的温度范围内获得了1.65×10-6/℃的温漂系数,低频时的电源抑制比达到-62 d B。
基金supported by the National 973 Program(Grant No.2008CB425704)the National Natural Science Foundation of China(Grant No.40975049)
文摘According to the ＂jacking-up＂ theory, which relates the cause of earthquakes to outer core convection ascension bodies, the crust will gradually recover after an earthquake. In such cases, the crust is stretched, the underground temperature is reduced, precipitation decreases, and drought occurs. In this paper, precipitation is compared with ground temperature and seismic data to determine the spatial and temporal relationship between earthquakes and subsequent droughts. Our objective is to develop a new method of drought prediction. With a few exceptions in location, the analysis of the first drought to occur after the Ms 〉 7 earthquakes in China's Mainland and the adjacent areas since 1950 shows that droughts tended to occur in regions near earthquake epicenters and in the eastern regions of the epicenters at the same latitude within six months after the earthquakes. In addition, and the differences between the starting time of the earthquakes and the droughts nearly share the same probability of 0 to 6 months. After careful analysis of 34 Ms 〉 6.5 earthquakes occurring in western China from 1980 to 2011, we determined that a second drought tends to occur approximately six months following the first drought, indicating a quasi-half-year period. Moreover, the duration of the quasi-half-year fluctuation increases with the magnitude of earthquake, at approximately 2.5 years for Ms 6.5 earthquake and approximately 5 years for Ms 8 earthquake.
基金Supported by Science and Technology Committee of Tianjin (No.06YFGPGX08400)Ministry of Science and Technology of China (No.2009GJF20022)Innovation Fund of Tianjin University
文摘High resistance thin film chip resistors(0603 type) were studied,and the specifications are as follows:1 k? with tolerance about ±0.1% after laser trimming and temperature coefficient of resistance(TCR) less than ±15×10-6/℃.Cr-Si-Ta-Al films were prepared with Ar flow rate and sputtering power fixed at 20 standard-state cubic centimeter per minute(sccm) and 100 W,respectively.The experiment shows that the electrical properties of Cr-SiTa-Al deposition films can meet the specification requirements of 0603 ty...
基金Supported by the National Natural Science Foundation of China(No.40676011)the Key Technology Research and Development Program of China(No.2006BAB18B02)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20100132110016)
文摘As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for ISW identification based on freezing point at the sea surface, and we study spatial distribution of ISW in front of the Amery Ice Shelf (AIS) and its flow path in Prydz Bay by analyzing hydrographic data from Australian cruises in 2001 and 2002, as well as Chinese cruises in 2003, 2005, 2006, and 2008, all being made in the austral summer. The relatively cold and fresh ISW occurred as several discrete water blocks with cold cores in front of the AIS, within the depth range of 100?600 m, under the seasonal thermocline. ISW had obvious temporal and spatial variations and the spatial distribution pattern changed greatly after 2005. Most of ISW was concentrated west of 73°E during 2001 to 2003 and 2006, but it was widespread to east in 2005 and 2008. In all observation years, a small amount of cold ISW always occurs at the west end of the AIS front section, where the coldest ISW in the whole section also occurred in 2001, 2003 and 2006. Considering general cyclonic circulation pattern under the AIS, the ISW flowing out from west end of the AIS front might have experienced the longest cooling period under ice shelf, so it would have the lowest temperature. Analysis of data from meridian sections in Prydz Bay in 2003 implied that ISW in the west could spread north to the continental break along the east flank of the Fram Bank near 70.5°E, mix with the upwelling Circumpolar Deep Water and possibly contribute to the formation of AABW.
文摘The low resistance PTC ceramic thermistor material with excellent eleectricalproperties are successfully fabricated by raw materials at industrial range made in our country onthe study of its composition expression and fabrication process by using the addition of Nb, La, Y,Ta , microstructure regulator BN and ASTL phase . The composition and its fabrication method arestudied. The relation of electrical properties of the PTC ceramic material to its compositionexpression and its related electrical properties are discussed
文摘The present work is focused on the relationship between effective segregation coefficient keff and tem- perature of melting zone for purification of phosphorus by zone melting method. Values of keff at four temperatures of melting zone are obtained for zone pass n = 1 at travel velocity of molten zone v = 5x 10^-3 m. h^-1 and initial impu- rity concentration C0〈10 μg.g-1, lnkeff is a linear function of 1/T. The keff values of A1, Ca, Cr, Fe, Cd and Sb in- crease with temperatures while that of Mg is almost constant. The purification is acceptable at lower temperature of melting zone such as 323 K. The variations of enthalpy and entropy between impurities and phosphorus in the liq- uid and solid ohases are also 19resented.
基金the National Basic Research Program of China(2010CB720500)the National Natural Science Foundation of China(21176178)
文摘In this paper, by combining a stochastic optimization method with a refrigeration shaft work targeting method,an approach for the synthesis of a heat integrated complex distillation system in a low-temperature process is presented. The synthesis problem is formulated as a mixed-integer nonlinear programming(MINLP) problem,which is solved by simulated annealing algorithm under a random procedure to explore the optimal operating parameters and the distillation sequence structure. The shaft work targeting method is used to evaluate the minimum energy cost of the corresponding separation system during the optimization without any need for a detailed design for the heat exchanger network(HEN) and the refrigeration system(RS). The method presented in the paper can dramatically reduce the scale and complexity of the problem. A case study of ethylene cold-end separation is used to illustrate the application of the approach. Compared with the original industrial scheme, the result is encouraging.
