提出了一种改进的非线性元件实现线性放大(Linear Amplifier Using Non-linear Components,LINC)理论,将幅度和相位均有变化的射频信号分离成包络信号和恒包络角调信号,将包络信号分两路反相调制到后者的相位中,对两路调制后的恒包络信...提出了一种改进的非线性元件实现线性放大(Linear Amplifier Using Non-linear Components,LINC)理论,将幅度和相位均有变化的射频信号分离成包络信号和恒包络角调信号,将包络信号分两路反相调制到后者的相位中,对两路调制后的恒包络信号进行变频放大,通过减法电路得到放大后的上变频输入射频信号.因为恒幅信号可以在放大器的非线性区放大而不失真,提高了整体效率高.推导出其电压增益为KG/Em,并对不同频率和幅度进行了仿真,仿真结果表明实现了理论分析预期的放大效果.展开更多
In this paper, we conduct research on the novel natural image reconstruction and representation algorithm based on clustenng and modified neural network. Image resolution enhancement is one of the earliest researches ...In this paper, we conduct research on the novel natural image reconstruction and representation algorithm based on clustenng and modified neural network. Image resolution enhancement is one of the earliest researches of single image interpolation. Although the traditional interpolation and method for single image amplification is effect, but did not provide more useful information. Our method combines the neural network and the clustering approach. The experiment shows that our method performs well and satisfactory.展开更多
One of the major challenges for successful gene therapy is improving the transfection efficiency of non-viral vectors. Magnetic nanoparticles (MNPs) have been developed as enhancers of non-viral vehicles. We prepared ...One of the major challenges for successful gene therapy is improving the transfection efficiency of non-viral vectors. Magnetic nanoparticles (MNPs) have been developed as enhancers of non-viral vehicles. We prepared MNPs and modified them with polyethyleneimine (PEI), citric acid (CA) or carboxylmethyl-dextran (CMD). Both positively charged MNPs (MNPs@PEI) and negatively charged MNPs (MNPs@CA, MNPs@CMD) could spontaneously form transfection complexes (magnetofectins) with plasmid DNA and PEI/liposome via electrostatic self-assembly. Our results showed as-prepared magnetofectins apparently enhanced PEI/liposome transfection efficiency and/or gene expression level into COS-7 cells with reduced transfection time from 4 h to 15 min under a magnetic field in vitro. Meanwhile, the effect of magnetofection was cell line-dependant. These results suggest that charged MNPs could improve transfection efficiency for non-viral vectors by simply mixing with them and by exerting a magnetic force. Thus such MNPs provide a convenient platform for further applications of gene delivery.展开更多
The mechanism of heat transfer enhancement by liquid film on the channel walls has been investigated in laminar mixed convective flows. The temperature distribution, velocity and mass fraction distributions, and the e...The mechanism of heat transfer enhancement by liquid film on the channel walls has been investigated in laminar mixed convective flows. The temperature distribution, velocity and mass fraction distributions, and the effects of the wetted wall temperatures and the Reynolds number on the momentum,heat and mass transfer were examined in details. Results show that the liquid film can enhance heat transfer along the wetted walls by 5-10 times.展开更多
This paper describes the improvement of leading edge film cooling effectiveness for a turbine inlet guide vane by using fan-shaped film cooling holes. The modification details are presented in comparison with the base...This paper describes the improvement of leading edge film cooling effectiveness for a turbine inlet guide vane by using fan-shaped film cooling holes. The modification details are presented in comparison with the base-line configuration of cylindrical holes. Numerical simulations were carried out for the base-line and modified configurations by using CFX, in which the k-ε turbulence model and scalable wall function were chosen. Contours of adiabatic film cooling effectiveness on the blade surfaces and span-wise distributions of film cooling effectiveness downstream the rows of cooling holes interested for the different cooling configurations were compared and discussed. It is showed that with the use of fan-shaped cooling holes around the leading edge, the adiabatic film cooling effectiveness can be enhanced considerably. In comparison with the cylindrical film cooling holes, up to 40% coolant mass flow can be saved by using fan-shaped cooling holes to obtain the comparable film cooling effectiveness for the studied inlet guide vane.展开更多
文摘提出了一种改进的非线性元件实现线性放大(Linear Amplifier Using Non-linear Components,LINC)理论,将幅度和相位均有变化的射频信号分离成包络信号和恒包络角调信号,将包络信号分两路反相调制到后者的相位中,对两路调制后的恒包络信号进行变频放大,通过减法电路得到放大后的上变频输入射频信号.因为恒幅信号可以在放大器的非线性区放大而不失真,提高了整体效率高.推导出其电压增益为KG/Em,并对不同频率和幅度进行了仿真,仿真结果表明实现了理论分析预期的放大效果.
文摘In this paper, we conduct research on the novel natural image reconstruction and representation algorithm based on clustenng and modified neural network. Image resolution enhancement is one of the earliest researches of single image interpolation. Although the traditional interpolation and method for single image amplification is effect, but did not provide more useful information. Our method combines the neural network and the clustering approach. The experiment shows that our method performs well and satisfactory.
基金supported by the International Cooperation Project (20080068 and 075207012)the National Natural Science Foundation of China (81000656)
文摘One of the major challenges for successful gene therapy is improving the transfection efficiency of non-viral vectors. Magnetic nanoparticles (MNPs) have been developed as enhancers of non-viral vehicles. We prepared MNPs and modified them with polyethyleneimine (PEI), citric acid (CA) or carboxylmethyl-dextran (CMD). Both positively charged MNPs (MNPs@PEI) and negatively charged MNPs (MNPs@CA, MNPs@CMD) could spontaneously form transfection complexes (magnetofectins) with plasmid DNA and PEI/liposome via electrostatic self-assembly. Our results showed as-prepared magnetofectins apparently enhanced PEI/liposome transfection efficiency and/or gene expression level into COS-7 cells with reduced transfection time from 4 h to 15 min under a magnetic field in vitro. Meanwhile, the effect of magnetofection was cell line-dependant. These results suggest that charged MNPs could improve transfection efficiency for non-viral vectors by simply mixing with them and by exerting a magnetic force. Thus such MNPs provide a convenient platform for further applications of gene delivery.
文摘The mechanism of heat transfer enhancement by liquid film on the channel walls has been investigated in laminar mixed convective flows. The temperature distribution, velocity and mass fraction distributions, and the effects of the wetted wall temperatures and the Reynolds number on the momentum,heat and mass transfer were examined in details. Results show that the liquid film can enhance heat transfer along the wetted walls by 5-10 times.
基金supported by the National 973 Program of China through grant number 2007CB210108
文摘This paper describes the improvement of leading edge film cooling effectiveness for a turbine inlet guide vane by using fan-shaped film cooling holes. The modification details are presented in comparison with the base-line configuration of cylindrical holes. Numerical simulations were carried out for the base-line and modified configurations by using CFX, in which the k-ε turbulence model and scalable wall function were chosen. Contours of adiabatic film cooling effectiveness on the blade surfaces and span-wise distributions of film cooling effectiveness downstream the rows of cooling holes interested for the different cooling configurations were compared and discussed. It is showed that with the use of fan-shaped cooling holes around the leading edge, the adiabatic film cooling effectiveness can be enhanced considerably. In comparison with the cylindrical film cooling holes, up to 40% coolant mass flow can be saved by using fan-shaped cooling holes to obtain the comparable film cooling effectiveness for the studied inlet guide vane.
