The gliding arc is an important approach to production of non-thermal plasma at atmospheric pressure, it can offer high-energy efficiency and high-electivity for chemical reactions. In this paper, the gliding arc driv...The gliding arc is an important approach to production of non-thermal plasma at atmospheric pressure, it can offer high-energy efficiency and high-electivity for chemical reactions. In this paper, the gliding arc driven by the transverse magnetic field is described and its velocity is measured by using a photo-multiplier. The mean velocity of the gliding arc increases with increasing magnetic induced-intensity, and its value varies from 7.8 m/s to 32 m/s.展开更多
When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fie...When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fields. We investigate the effects of the coherent fields, the dissipation as well as the incoherent coupling on the following dynamical properties of the system： photon transfer, reversible decoherence, and quantum state transfer, etc. We find that the photons in the cavities do not leak completely into the environment due to the collective coupling between the cavities and the enviroment, and the photons are transferred irreversibly from the cavity with more photons to the cavity with less ones due to the incoherent coupling so that they are equally distributed among the two cavities. The coherent field pumping on the two cavities increases the mean photons, complements the revived magnitude of the reversible decoherence, but hinders the quantum state transfer between the two cavities. The above phenomena may find applications in quantum communication and other basic fields.展开更多
We consider two two-level atoms, interacting with two independent dissipative cavities, each of which is driven by an external source. The two cavity fields are both initially prepared in the coherent states, and the ...We consider two two-level atoms, interacting with two independent dissipative cavities, each of which is driven by an external source. The two cavity fields are both initially prepared in the coherent states, and the two two-level atoms are initially prepared in the singlet state ｜ψ^-〉 =（｜eg〉 - ｜ge〉 ） / √2. We investigate the influence of the damping constant n, the intensity of the external sources F, and the relative difference of the atomic couplings r on the entanglement between the two atoms. In the dispersive approximation, we find that the entanglement between the two atoms decreases with the time evolution, and the decreasing rate of entanglement depends on the values of F/k, k/ω, and r. For the given small values of F/k and k/ω, on the one hand, the increasing of r favors entanglement decreasing of the atomic system, on the other hand, when r → 1 the entanglement decreasing becomes slower. With the increasing of the value of k/ω, the influence of r on the decreasing rate of entanglement becomes smaller, and gradually disappears for the big value of k/ω.展开更多
Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter pr...Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter projecting in the direction of arc motion （front-viewed diameter） and the diameter projecting in the perpendicular direction of arc motion （side-viewed diameter） were measured. The effect of both the arc current and the magnetic field was analysed. The front-viewed diameter was compared with the side-viewed one. Simultaneously the electricfield intensity was measured directly and analysed by considering the effect of the external magnetic field and arc current.展开更多
In the present context of increasing social demands for natural science education,increasing people s awareness of environmental biodiversity protection,and ecological civilization lifting to the state strategy,it is ...In the present context of increasing social demands for natural science education,increasing people s awareness of environmental biodiversity protection,and ecological civilization lifting to the state strategy,it is just the time to explore a new botany field practice model.The attempt of a new task-driven model for botany field practice will greatly enhance students thinking about plants and nature,plants and environment,and plant and ecological civilization,and will inevitably enhance students initiative awareness and practical ability to protect and rationally utilize plant resources.展开更多
针对受控高压开关中串联金属-氧化物半导体场效应晶体管(metal-oxide semiconductor field effect transistor,MOSFET)驱动复杂性与动态电压失衡问题,本文提出一种基于非隔离驱动的P沟道增强型MOSFET串联高压开关电路。通过构建二极管...针对受控高压开关中串联金属-氧化物半导体场效应晶体管(metal-oxide semiconductor field effect transistor,MOSFET)驱动复杂性与动态电压失衡问题,本文提出一种基于非隔离驱动的P沟道增强型MOSFET串联高压开关电路。通过构建二极管电位梯度屏障网络,采用单驱动源触发多管开关控制,结合瞬态电压抑制二极管(transient voltage suppression diodes,TVS)动态箝位与容性耦合机制,解决kV级应用中电压失衡问题。将该技术应用于解决碳纳米管(carbon nanotube,CNT)阴极X射线管脉冲拖尾问题的受控放电电路,实验表明:在-12 V单源驱动下可实现5只MOSFET串联电路开通,导通累计时间0.274μs;电路关断耐压达-2 kV;脉冲下降沿缩短至9.8μs。该电路结构简单、开关速度快、可靠性高,为高压快脉冲系统提供了新的解决方案。展开更多
Hybrid-driven underwater glider is a new type of tmmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have...Hybrid-driven underwater glider is a new type of tmmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steady- state operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulations.and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.展开更多
This paper presents the design, fabrication, and preliminary experimental result of an electric field microsensor based on the structure of piezoelectric interdigitated cantilevers with staggered vertical vibration mo...This paper presents the design, fabrication, and preliminary experimental result of an electric field microsensor based on the structure of piezoelectric interdigitated cantilevers with staggered vertical vibration mode. The working principle of this electric field microsensor is demonstrated, and the induced charges and structural parameters of this microsensor are simulated by the finite element method. The electric field microsensor was fabricated by Micro-Electro Mechanical Systems(MEMS) technique. Each cantilever is a multilayer compound structure(Al/Si3N4/ Pt/PZT/Pt/ Ti/SiO 2/Si), and Piezoelectric, PieZ oelectric ceramic Transducer(PZT)(PbZ rxTi(1–x)O3) layer, prepared by sol-gel method, is used as the piezoelectric material to drive the cantilevers vibrating. This electric field microsensor was tested under the DC electric field with the field intensity from 0 to 5×104 V/m. The output voltage signal of the electric field microsensor has a good linear relationship to the intensity of applied electric field. The performance could be improved with the optimized design of structure, and reformative fabrication processes of PZT material.展开更多
The time delay integration charge coupled device(TDI CCD)is the key component in remote sensing systems.The paper analyzes the structure and the working principles of the device according to a customized TDI CCD chip....The time delay integration charge coupled device(TDI CCD)is the key component in remote sensing systems.The paper analyzes the structure and the working principles of the device according to a customized TDI CCD chip.Employing the special clock resources and large-scale phase locked logic(PLL)in field-programmable gate arrays(FPGA),a timing-driven approach is proposed,using which all timing signals including reset gate,horizontal and vertical timing signals,are implemented in one chip.This not only reduces printed circuit board(PCB)space,but also enhances the portability of the system.By studying and calculating CCD parameters thoroughly,load capacity and power consumption,package,etc,are compared between various candidates chips,and detailed comparison results are also listed in table.Experimental results show that clock generator and driving circuit satisfy the requirements of high speed TDI CCD.展开更多
We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic...We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic field with frequencies ω1 and ω2, and Rabi frequencies ？1 and ？2, in which the first coupling field of ？1 acts on the bare atomic levels, and then the resulting singly dressed states are driven by the second coupling field of ？2, thus resulting in the doubly dressed atom.We have measured the probe absorption spectra of a doubly driven two-level atom. The system consists of 52S1/2, F= 2 and 5~2P_（3/2）, F＇= 3 states of ^（87）Rb atoms in a magneto-optical trap（MOT） as well as the cooling/trapping beams and an additional coupling field. As for the spectroscopic properties of the doubly driven two-level atom, theoretical analytical solutions are in general agreement with the experimental spectrum as a whole.展开更多
文摘The gliding arc is an important approach to production of non-thermal plasma at atmospheric pressure, it can offer high-energy efficiency and high-electivity for chemical reactions. In this paper, the gliding arc driven by the transverse magnetic field is described and its velocity is measured by using a photo-multiplier. The mean velocity of the gliding arc increases with increasing magnetic induced-intensity, and its value varies from 7.8 m/s to 32 m/s.
基金The project supported in part by National Natural Science Foundation of China under Grant Nos. 10175029, 10375039, and 10647007, the Doctoral Education Fund of Ministry of Education, the Research Fund of Nuclear Theory Center of HIRFL of China, and the Science and Technology Foundation of Sichuan Province under Grant No. 02GY029-189
文摘When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fields. We investigate the effects of the coherent fields, the dissipation as well as the incoherent coupling on the following dynamical properties of the system： photon transfer, reversible decoherence, and quantum state transfer, etc. We find that the photons in the cavities do not leak completely into the environment due to the collective coupling between the cavities and the enviroment, and the photons are transferred irreversibly from the cavity with more photons to the cavity with less ones due to the incoherent coupling so that they are equally distributed among the two cavities. The coherent field pumping on the two cavities increases the mean photons, complements the revived magnitude of the reversible decoherence, but hinders the quantum state transfer between the two cavities. The above phenomena may find applications in quantum communication and other basic fields.
文摘We consider two two-level atoms, interacting with two independent dissipative cavities, each of which is driven by an external source. The two cavity fields are both initially prepared in the coherent states, and the two two-level atoms are initially prepared in the singlet state ｜ψ^-〉 =（｜eg〉 - ｜ge〉 ） / √2. We investigate the influence of the damping constant n, the intensity of the external sources F, and the relative difference of the atomic couplings r on the entanglement between the two atoms. In the dispersive approximation, we find that the entanglement between the two atoms decreases with the time evolution, and the decreasing rate of entanglement depends on the values of F/k, k/ω, and r. For the given small values of F/k and k/ω, on the one hand, the increasing of r favors entanglement decreasing of the atomic system, on the other hand, when r → 1 the entanglement decreasing becomes slower. With the increasing of the value of k/ω, the influence of r on the decreasing rate of entanglement becomes smaller, and gradually disappears for the big value of k/ω.
基金National Natural Science Foundation of China(No.10375065)Natural Science Foundation of Anhui Province(No.03045102)
文摘Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter projecting in the direction of arc motion （front-viewed diameter） and the diameter projecting in the perpendicular direction of arc motion （side-viewed diameter） were measured. The effect of both the arc current and the magnetic field was analysed. The front-viewed diameter was compared with the side-viewed one. Simultaneously the electricfield intensity was measured directly and analysed by considering the effect of the external magnetic field and arc current.
基金Supported by Special Fund for Reform of Teaching Model of Huanggang Normal University(2016CK06,2018CE42)
文摘In the present context of increasing social demands for natural science education,increasing people s awareness of environmental biodiversity protection,and ecological civilization lifting to the state strategy,it is just the time to explore a new botany field practice model.The attempt of a new task-driven model for botany field practice will greatly enhance students thinking about plants and nature,plants and environment,and plant and ecological civilization,and will inevitably enhance students initiative awareness and practical ability to protect and rationally utilize plant resources.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51475319 and 51722508)the National Key R&D Plan(Grant No.2016YFC0301100)Aoshan Talents Program of Qingdao National Laboratory for Marine Science and Technology
文摘Hybrid-driven underwater glider is a new type of tmmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steady- state operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulations.and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.
文摘This paper presents the design, fabrication, and preliminary experimental result of an electric field microsensor based on the structure of piezoelectric interdigitated cantilevers with staggered vertical vibration mode. The working principle of this electric field microsensor is demonstrated, and the induced charges and structural parameters of this microsensor are simulated by the finite element method. The electric field microsensor was fabricated by Micro-Electro Mechanical Systems(MEMS) technique. Each cantilever is a multilayer compound structure(Al/Si3N4/ Pt/PZT/Pt/ Ti/SiO 2/Si), and Piezoelectric, PieZ oelectric ceramic Transducer(PZT)(PbZ rxTi(1–x)O3) layer, prepared by sol-gel method, is used as the piezoelectric material to drive the cantilevers vibrating. This electric field microsensor was tested under the DC electric field with the field intensity from 0 to 5×104 V/m. The output voltage signal of the electric field microsensor has a good linear relationship to the intensity of applied electric field. The performance could be improved with the optimized design of structure, and reformative fabrication processes of PZT material.
基金National High Technology Research and Development Program of China(863 Program)(No.2009AA7010102)
文摘The time delay integration charge coupled device(TDI CCD)is the key component in remote sensing systems.The paper analyzes the structure and the working principles of the device according to a customized TDI CCD chip.Employing the special clock resources and large-scale phase locked logic(PLL)in field-programmable gate arrays(FPGA),a timing-driven approach is proposed,using which all timing signals including reset gate,horizontal and vertical timing signals,are implemented in one chip.This not only reduces printed circuit board(PCB)space,but also enhances the portability of the system.By studying and calculating CCD parameters thoroughly,load capacity and power consumption,package,etc,are compared between various candidates chips,and detailed comparison results are also listed in table.Experimental results show that clock generator and driving circuit satisfy the requirements of high speed TDI CCD.
基金Project supported by Beijing Natural Science Foundation,China(Grant No.1164016)the National Natural Science Foundation of China(Grant Nos.11604334,61227807,and 61575108)the Tsinghua Initiative Scientific Research Program,China(Grant No.2013THZ02-3)
文摘We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic field with frequencies ω1 and ω2, and Rabi frequencies ？1 and ？2, in which the first coupling field of ？1 acts on the bare atomic levels, and then the resulting singly dressed states are driven by the second coupling field of ？2, thus resulting in the doubly dressed atom.We have measured the probe absorption spectra of a doubly driven two-level atom. The system consists of 52S1/2, F= 2 and 5~2P_（3/2）, F＇= 3 states of ^（87）Rb atoms in a magneto-optical trap（MOT） as well as the cooling/trapping beams and an additional coupling field. As for the spectroscopic properties of the doubly driven two-level atom, theoretical analytical solutions are in general agreement with the experimental spectrum as a whole.
