Uniaxial stress is a powerful tool for tuning exciton emitting wavelength, polarization, fine-structure splitting (FSS), and the symmetry of quantum dots (QDs). Here, we present a technique for applying uniaxial stres...Uniaxial stress is a powerful tool for tuning exciton emitting wavelength, polarization, fine-structure splitting (FSS), and the symmetry of quantum dots (QDs). Here, we present a technique for applying uniaxial stress, which enables us in situ to tune exciton optical properties at low temperature down to 15 K with high tuning precision. The design and operation of the device are described in detail. This technique provides a simple and convenient approach to tune QD structural symmetry, exciton energy and biexciton binding energy. It can be utilized for generating entangled and indistinguishable photons. Moreover, this device can be employed for tuning optical properties of thin film materials at low temperature.展开更多
MEMS Safety-and-Arming(S&A)device is the new generation of S&A device which integrates the mechanism of actuation and barrier.The features of minimized structure and easy integration make it to be the indispen...MEMS Safety-and-Arming(S&A)device is the new generation of S&A device which integrates the mechanism of actuation and barrier.The features of minimized structure and easy integration make it to be the indispensable support to the development of weapon miniaturization,integration and intelligence.As a key component in the new generation weapon system,the sound development of MEMS S&A devices will have a significant impact on the future national defense system.Herein,the research status and development trend of MEMS S&A devices are introduced in this paper.From literature review on various MEMS S&A devices,it can be seen that the researches have evolved from individual components to system integration,and many prototypes have the potential for live-fire testing.Different driven principles and structures of the MEMS S&A devices are compared and summarized.At present,the MEMS S&A device can realize the mutual integration of the driving mechanism and the blocking mechanism on the micron level.In the future,with the establishment of new design criteria,MEMS S&A devices will develop from prototypes to practical applications,which will further promote the integration and intelligent of weapon systems.展开更多
船舶坞修作为维护和修复船舶结构的关键环节,在船舶行业中扮演着重要的角色。然而,目前船舶坞修时表面打磨过程依赖于传统的人工作业,存在着效率低、工时长、危险性高等问题。为此,提出了一种新型绳驱动式打磨机构,该机构采用四根绳索...船舶坞修作为维护和修复船舶结构的关键环节,在船舶行业中扮演着重要的角色。然而,目前船舶坞修时表面打磨过程依赖于传统的人工作业,存在着效率低、工时长、危险性高等问题。为此,提出了一种新型绳驱动式打磨机构,该机构采用四根绳索驱动打磨装置实现三自由度的运动。首先,通过拉格朗日法建立系统的动力学模型;然后在动力学模型的基础上提出了一种带有绳索张力优化项的Fuzzy-PID(proportional integral derivative)控制策略,该控制策略可以实现精确的轨迹跟踪并保证绳索处于张紧状态;最后,通过数值仿真验证所提控制策略的有效性。结果表明,和绳牵引并联机器人上常用的PID控制相比,所提控制策略控制精度提高25%,具有较高的控制精度和稳定性。本文提出的绳驱动式打磨机构及其控制策略可为大型结构件表面处理和精密制造等应用提供一定理论支持。展开更多
With the advances of electronic information technology and computer network, especially the embedded technology, smart home is no more just a vision but being practical. The interoperability of heterogeneous devices a...With the advances of electronic information technology and computer network, especially the embedded technology, smart home is no more just a vision but being practical. The interoperability of heterogeneous devices and flexibility of devices＇ usage are two key problems that challenge the implementation of smart home. To deal with these two issues, this paper proposes an event-driven service oriented architecture using device profile for web services （DPWS）. DPWS inherits the advantages of the traditional web services in achieving interoperability without dependence on platform, while improving service discovery and security as well as being optimized for deploying on resource constrained devices. By providing a visual interface for describing a service workflow （SW）, the user can easily customize the actions of devices by services composition. Devices automatically cooperate without user＇s intervention to complete required business logic. This is achieved by fully exploiting the eventing capabilities on DPWS enabled home devices. Finally, a home theater scenario is given to illustrate the event driven mechanism for the SW in the proposed smart home framework.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
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0301202)the National Natural Science Foundation of China(Grant No.61674135)
文摘Uniaxial stress is a powerful tool for tuning exciton emitting wavelength, polarization, fine-structure splitting (FSS), and the symmetry of quantum dots (QDs). Here, we present a technique for applying uniaxial stress, which enables us in situ to tune exciton optical properties at low temperature down to 15 K with high tuning precision. The design and operation of the device are described in detail. This technique provides a simple and convenient approach to tune QD structural symmetry, exciton energy and biexciton binding energy. It can be utilized for generating entangled and indistinguishable photons. Moreover, this device can be employed for tuning optical properties of thin film materials at low temperature.
基金The work is supported by China Postdoctoral Science Foundation(2018M640977)the Fundamental Research Funds for the Central Universities(xzy012019004).
文摘MEMS Safety-and-Arming(S&A)device is the new generation of S&A device which integrates the mechanism of actuation and barrier.The features of minimized structure and easy integration make it to be the indispensable support to the development of weapon miniaturization,integration and intelligence.As a key component in the new generation weapon system,the sound development of MEMS S&A devices will have a significant impact on the future national defense system.Herein,the research status and development trend of MEMS S&A devices are introduced in this paper.From literature review on various MEMS S&A devices,it can be seen that the researches have evolved from individual components to system integration,and many prototypes have the potential for live-fire testing.Different driven principles and structures of the MEMS S&A devices are compared and summarized.At present,the MEMS S&A device can realize the mutual integration of the driving mechanism and the blocking mechanism on the micron level.In the future,with the establishment of new design criteria,MEMS S&A devices will develop from prototypes to practical applications,which will further promote the integration and intelligent of weapon systems.
文摘船舶坞修作为维护和修复船舶结构的关键环节,在船舶行业中扮演着重要的角色。然而,目前船舶坞修时表面打磨过程依赖于传统的人工作业,存在着效率低、工时长、危险性高等问题。为此,提出了一种新型绳驱动式打磨机构,该机构采用四根绳索驱动打磨装置实现三自由度的运动。首先,通过拉格朗日法建立系统的动力学模型;然后在动力学模型的基础上提出了一种带有绳索张力优化项的Fuzzy-PID(proportional integral derivative)控制策略,该控制策略可以实现精确的轨迹跟踪并保证绳索处于张紧状态;最后,通过数值仿真验证所提控制策略的有效性。结果表明,和绳牵引并联机器人上常用的PID控制相比,所提控制策略控制精度提高25%,具有较高的控制精度和稳定性。本文提出的绳驱动式打磨机构及其控制策略可为大型结构件表面处理和精密制造等应用提供一定理论支持。
文摘With the advances of electronic information technology and computer network, especially the embedded technology, smart home is no more just a vision but being practical. The interoperability of heterogeneous devices and flexibility of devices＇ usage are two key problems that challenge the implementation of smart home. To deal with these two issues, this paper proposes an event-driven service oriented architecture using device profile for web services （DPWS）. DPWS inherits the advantages of the traditional web services in achieving interoperability without dependence on platform, while improving service discovery and security as well as being optimized for deploying on resource constrained devices. By providing a visual interface for describing a service workflow （SW）, the user can easily customize the actions of devices by services composition. Devices automatically cooperate without user＇s intervention to complete required business logic. This is achieved by fully exploiting the eventing capabilities on DPWS enabled home devices. Finally, a home theater scenario is given to illustrate the event driven mechanism for the SW in the proposed smart home framework.
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.
