Stochastic resonance system is subject to the restriction of small frequency parameter in weak signal detection,in order to solve this problem,a frequency modulated weak signal detection method based on stochastic res...Stochastic resonance system is subject to the restriction of small frequency parameter in weak signal detection,in order to solve this problem,a frequency modulated weak signal detection method based on stochastic resonance and genetic algorithm is presented in this paper. The frequency limit of stochastic resonance is eliminated by introducing carrier signal,which is multiplied with the measured signal to be injected in the stochastic resonance system,meanwhile,using genetic algorithm to optimize the carrier signal frequency,which determine the generated difference-frequency signal in the lowfrequency range,so as to achieve the stochastic resonance weak signal detection. Results showthat the proposed method is feasible and effective,which can significantly improve the output SNR of stochastic resonance,in addition,the system has the better self-adaptability,according to the operation result and output phenomenon,the unknown frequency of the signal to be measured can be obtained,so as to realize the weak signal detection of arbitrary frequency.展开更多
In this paper, a simple and effective method is presented to solve the two-dimensionalnonlinear steady inverse heat conduction problem. From the finite difference equation of heatconduction, the convective heat transf...In this paper, a simple and effective method is presented to solve the two-dimensionalnonlinear steady inverse heat conduction problem. From the finite difference equation of heatconduction, the convective heat transfer coefficient, which is the unknown boundary, can benumerially obtained with this method. By taking the electrically heated helically coiled tubeas an experimental case, this method is successfully applied. It is proved by numerical teststhat this method takes the advantages of fast coverging, high precision and good stability.It can also be extended to the complex geometrics problems.展开更多
Photogating is an effective strategy to modulate the channel conductance of the device with light-induced gate field or voltage,thereby improving the performance of optoelectronic devices.In this work,to overcome the ...Photogating is an effective strategy to modulate the channel conductance of the device with light-induced gate field or voltage,thereby improving the performance of optoelectronic devices.In this work,to overcome the long response time and low photoresponse of one-dimensional ZnO,a MoS_(2)-on-ZnO photogating vertical heterojunction photodetector is design and constructed.Herein,the ZnO nanowire with high carrier mobility can response ultraviolet light and supply a highspeed carrier transport channel,while the MoS_(2) flake as a photogating layer can response with visible light and transfer photogenerated electrons into the ZnO nanowire to adjust its conductivity.Thus,the irradiation of visible light is equivalent to applying a photo-induced gate voltage on the ZnO nanowire.In addition,the photogenerated electrons will not transmit through the MoS_(2) with low carrier mobility,so that not only the visible light response of the photodetector can be realized,but also its ultraviolet light response is able to be improved.Under ultraviolet light irradiation,the photoresponsivity of the photodetector can be reached to 273 A W-1and the response speed is less than 24 ms.More important,based on this unique heterojunction structure,MoS_(2)-on-ZnO photodetector also illustrates an excellent visible light response with a high photoresponsivity(74 A W-1) and fast response speed(<24 ms) due to the photogating effect.This work not only paves the way to design high-performance photodetectors with high photoresponsivity and fast response speed,but also provide a promising approach to improve the performance of optoelectronic devices using photogating effect.展开更多
A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influ...A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 61072133)the Production,Learning and Research Joint Innovation Program of Jiangsu Province,China (Grant Nos. BY2013007-02,SBY201120033)+2 种基金the Industrialization of Research Findings Promotion Program of Institution of Higher Education of Jiangsu Province,China (Grant No. JHB2011-15)the advantage discipline platform "information and Communication Engineering" of Jiangsu Province,Chinathe "Summit of the Six Top Talents" Program of Jiangsu Province,China
文摘Stochastic resonance system is subject to the restriction of small frequency parameter in weak signal detection,in order to solve this problem,a frequency modulated weak signal detection method based on stochastic resonance and genetic algorithm is presented in this paper. The frequency limit of stochastic resonance is eliminated by introducing carrier signal,which is multiplied with the measured signal to be injected in the stochastic resonance system,meanwhile,using genetic algorithm to optimize the carrier signal frequency,which determine the generated difference-frequency signal in the lowfrequency range,so as to achieve the stochastic resonance weak signal detection. Results showthat the proposed method is feasible and effective,which can significantly improve the output SNR of stochastic resonance,in addition,the system has the better self-adaptability,according to the operation result and output phenomenon,the unknown frequency of the signal to be measured can be obtained,so as to realize the weak signal detection of arbitrary frequency.
文摘In this paper, a simple and effective method is presented to solve the two-dimensionalnonlinear steady inverse heat conduction problem. From the finite difference equation of heatconduction, the convective heat transfer coefficient, which is the unknown boundary, can benumerially obtained with this method. By taking the electrically heated helically coiled tubeas an experimental case, this method is successfully applied. It is proved by numerical teststhat this method takes the advantages of fast coverging, high precision and good stability.It can also be extended to the complex geometrics problems.
基金partially supported by the Liaoning Province Natural Science Fund Program (2019-MS-333)the Youth Innovation Promotion Association,Chinese Academy of Sciences (2019197)the National Natural Science Foundation of China (51702326, 51872296)。
文摘Photogating is an effective strategy to modulate the channel conductance of the device with light-induced gate field or voltage,thereby improving the performance of optoelectronic devices.In this work,to overcome the long response time and low photoresponse of one-dimensional ZnO,a MoS_(2)-on-ZnO photogating vertical heterojunction photodetector is design and constructed.Herein,the ZnO nanowire with high carrier mobility can response ultraviolet light and supply a highspeed carrier transport channel,while the MoS_(2) flake as a photogating layer can response with visible light and transfer photogenerated electrons into the ZnO nanowire to adjust its conductivity.Thus,the irradiation of visible light is equivalent to applying a photo-induced gate voltage on the ZnO nanowire.In addition,the photogenerated electrons will not transmit through the MoS_(2) with low carrier mobility,so that not only the visible light response of the photodetector can be realized,but also its ultraviolet light response is able to be improved.Under ultraviolet light irradiation,the photoresponsivity of the photodetector can be reached to 273 A W-1and the response speed is less than 24 ms.More important,based on this unique heterojunction structure,MoS_(2)-on-ZnO photodetector also illustrates an excellent visible light response with a high photoresponsivity(74 A W-1) and fast response speed(<24 ms) due to the photogating effect.This work not only paves the way to design high-performance photodetectors with high photoresponsivity and fast response speed,but also provide a promising approach to improve the performance of optoelectronic devices using photogating effect.
基金Supported by the National Key Basic R&D Program ("973" Program, No. 2009CB219905 and 2009CB219907)the Program for Changjiang Scholars and Innovative Research Teams in Universities (No. IRT0936)
文摘A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area.
