A quadrature mixer with a shared transconductor stage is analyzed,including voltage conversion gain, linearity, noise figure, and image rejection. The analysis indicates it has better performance than a conventional G...A quadrature mixer with a shared transconductor stage is analyzed,including voltage conversion gain, linearity, noise figure, and image rejection. The analysis indicates it has better performance than a conventional Gilbert mixer pair in commutating mode. A quadrature down-conversion mixer based on this topology is designed and optimized for an ultra high frequency RFID reader. Operating in the 915MHz ISM band, the presented quadrature mixer measures a conversion gain of 12.5dB,an IIP3 of 10dBm, an IIP2 of 58dBm, and an SSB noise figure of 17.6riB. The chip was fabricated in a 0. 18μm 1P6M RF CMOS process and consumes only 3mA of current from a 1.8V power supply.展开更多
An antiship missile with supersonic speed at minimum altitude is an effective weapon to break through a defense line. The former Soviet Union was a leader in this field since it had developed several kinds of antiship...An antiship missile with supersonic speed at minimum altitude is an effective weapon to break through a defense line. The former Soviet Union was a leader in this field since it had developed several kinds of antiship missiles which obtained supersonic speed at minimum altitudes. To counter this kind of missile, many countries have been developing corresponding antimissiles. For the purpose of verifing the antimissile missile′s effectiveness in intercepting antiship missiles, a target-missile is needed. A target-missle is cheaper and can imitate the main characteristics of antiship missiles with supersonic speed at minimum altitude. In this paper, the control scheme of a target missile flying with supersonic speed at minimum altitude is studied. To counter the problem of hedgehopping over the sea, a control scheme utilizing a SINS+altimeter was proposed. In this scheme, both the quick response ability of altitude control and the anti-jamming problem were considered. A simulation experiment shows that when an integrated altitude control system is used, the anti-disturbance ability of the integrated altitude is good and the response speed of altitude control system can be dramatically improved.展开更多
Objective: To build a cell model of LPS-induced hyper- and hypo-responsiveness in macrophage cells . Methods: Macrophage cell line RAW264. 7 was pre-cultured with or without 10 ng/ml LPS for 18 h, then challenged with...Objective: To build a cell model of LPS-induced hyper- and hypo-responsiveness in macrophage cells . Methods: Macrophage cell line RAW264. 7 was pre-cultured with or without 10 ng/ml LPS for 18 h, then challenged with lipopolysaccharide(LPS) , or MDP, Zymosan, PAF, FMLP, PMA for 24 h. The levels of TNF-α , IL-1 , IL-6, IL-10 , NO and O2-, were measured. Results: LI'S pretreatment markedly inhibited TNF-a NO and IL-6 production, but increased IL-1, IL-10 and O2- release to LPS challenge. LPS pretreatment also altered macrophage responsiveness to the other stimuli. Conclusion: LPS can induce hyper- and hypo-responsiveness simultaneously in the macrophage cell lines. Changes in macrophage responsiveness depend on stimuli and effectors which are measured.展开更多
A new flame detector with one ultraviolet and two infrared detectors is designed. The ultraviolet detector is of rapid response(≤10 μs) while the two infrared detectors usually have a response time of more than 5 ms...A new flame detector with one ultraviolet and two infrared detectors is designed. The ultraviolet detector is of rapid response(≤10 μs) while the two infrared detectors usually have a response time of more than 5 ms. The ultraviolet detector is applied to deal with the flame of large scales. When facing the flame of mid or small scales, the three detectors cooperate. Employing the high-order derivatives of the sample data of the infrared circuits to improve the sensitivity, the response speed is greatly improved. The data of the temperature sensor is used to adjust circuit parameters in real time, thus reducing the effect of temperature drift. The flame detectors are tested at different distances and the response time is as rapid as 0.65 ms. The test results show that the new flame detector has the characteristics of high speed and a low rate of false alarms.展开更多
The I-V characteristic of a superconductor is generally described by power-law,in which the superconductor with a high n transfers quickly from superconducting state to the normal conducting state.With a high transpor...The I-V characteristic of a superconductor is generally described by power-law,in which the superconductor with a high n transfers quickly from superconducting state to the normal conducting state.With a high transport current,in the low n value area,flux flow voltage becomes lower than in the high n value area,so that the transient characteristics strongly affect its stability.Based on those properties,we propose a new hybrid conductor which is made of low temperature superconductor(LTS) and high temperature superconductor(HTS) with concentric configuration in which the HTS coat is located outside of the LTS core.According to their power-law models,the modified adiabatic and dynamic stability criteria are qualitatively obtained by taking account into not only their critical currents but also n values.As a result,the new hybrid conductors have potential applications with higher engineering current density and improved stability.展开更多
文摘A quadrature mixer with a shared transconductor stage is analyzed,including voltage conversion gain, linearity, noise figure, and image rejection. The analysis indicates it has better performance than a conventional Gilbert mixer pair in commutating mode. A quadrature down-conversion mixer based on this topology is designed and optimized for an ultra high frequency RFID reader. Operating in the 915MHz ISM band, the presented quadrature mixer measures a conversion gain of 12.5dB,an IIP3 of 10dBm, an IIP2 of 58dBm, and an SSB noise figure of 17.6riB. The chip was fabricated in a 0. 18μm 1P6M RF CMOS process and consumes only 3mA of current from a 1.8V power supply.
文摘An antiship missile with supersonic speed at minimum altitude is an effective weapon to break through a defense line. The former Soviet Union was a leader in this field since it had developed several kinds of antiship missiles which obtained supersonic speed at minimum altitudes. To counter this kind of missile, many countries have been developing corresponding antimissiles. For the purpose of verifing the antimissile missile′s effectiveness in intercepting antiship missiles, a target-missile is needed. A target-missle is cheaper and can imitate the main characteristics of antiship missiles with supersonic speed at minimum altitude. In this paper, the control scheme of a target missile flying with supersonic speed at minimum altitude is studied. To counter the problem of hedgehopping over the sea, a control scheme utilizing a SINS+altimeter was proposed. In this scheme, both the quick response ability of altitude control and the anti-jamming problem were considered. A simulation experiment shows that when an integrated altitude control system is used, the anti-disturbance ability of the integrated altitude is good and the response speed of altitude control system can be dramatically improved.
基金Supported by National Natural Science Foundation of China (No.39730210)
文摘Objective: To build a cell model of LPS-induced hyper- and hypo-responsiveness in macrophage cells . Methods: Macrophage cell line RAW264. 7 was pre-cultured with or without 10 ng/ml LPS for 18 h, then challenged with lipopolysaccharide(LPS) , or MDP, Zymosan, PAF, FMLP, PMA for 24 h. The levels of TNF-α , IL-1 , IL-6, IL-10 , NO and O2-, were measured. Results: LI'S pretreatment markedly inhibited TNF-a NO and IL-6 production, but increased IL-1, IL-10 and O2- release to LPS challenge. LPS pretreatment also altered macrophage responsiveness to the other stimuli. Conclusion: LPS can induce hyper- and hypo-responsiveness simultaneously in the macrophage cell lines. Changes in macrophage responsiveness depend on stimuli and effectors which are measured.
基金Project of Special Zone for National Defense Science and Technology Innovation(No.Y7GW04C001)
文摘A new flame detector with one ultraviolet and two infrared detectors is designed. The ultraviolet detector is of rapid response(≤10 μs) while the two infrared detectors usually have a response time of more than 5 ms. The ultraviolet detector is applied to deal with the flame of large scales. When facing the flame of mid or small scales, the three detectors cooperate. Employing the high-order derivatives of the sample data of the infrared circuits to improve the sensitivity, the response speed is greatly improved. The data of the temperature sensor is used to adjust circuit parameters in real time, thus reducing the effect of temperature drift. The flame detectors are tested at different distances and the response time is as rapid as 0.65 ms. The test results show that the new flame detector has the characteristics of high speed and a low rate of false alarms.
基金supported in part by the National Natural Science Foundation of China (Grant No. 51077051)
文摘The I-V characteristic of a superconductor is generally described by power-law,in which the superconductor with a high n transfers quickly from superconducting state to the normal conducting state.With a high transport current,in the low n value area,flux flow voltage becomes lower than in the high n value area,so that the transient characteristics strongly affect its stability.Based on those properties,we propose a new hybrid conductor which is made of low temperature superconductor(LTS) and high temperature superconductor(HTS) with concentric configuration in which the HTS coat is located outside of the LTS core.According to their power-law models,the modified adiabatic and dynamic stability criteria are qualitatively obtained by taking account into not only their critical currents but also n values.As a result,the new hybrid conductors have potential applications with higher engineering current density and improved stability.
