The evaluation of speckle contrast with variable speckle generator

Abstract— While laser projection has many advantages, there is a problem with speckle patterns generated as a result of interference of the laser beam and results in bad effects to observers. In 2010, a variable speckle generator, which produces an angular shift of incident light to the screen and generates variable speckle patterns, was suggested. In this study, the performance of a variable speckle generator by using a volume phase holographic beam shaper and scanning mirror was investigated in detail by evaluating both the objective and subjective speckle contrast. The morphology of the speckle pattern was also investigated when the variable speckle generator was activated. With a scanning VPH beam shaper, the objective speckle was effectively reduced because each point of the VPH beam shaper generated different speckle patterns and coherency among each pattern disappeared by using the scan process. On the other hand, subjective speckle was also dramatically reduced by changing the incident angle on the screen, which resulted in generating variable subjective speckle. It was also shown that the speckle reduction rate by using a variable speckle generator did not depend on the coherent length of a laser by evaluating the normalized speckle contrast against the angular shift on the screen.     

动态网站自动生成器关键技术研究

该文对动态网站自动生成器进行了研究与分析。通过对动态网站的系统体系结构进行研究,针对三层软件架构下的动态网站设计出相应的代码生成器,并对其中系统实现的关键技术进行分析。     

纯音听力计中纯音信号发生器的设计与实现

纯音听力计是进行听觉功能测试的基本声学仪器,而纯音信号发生器是其最重要的组成模块,它决定着可控声源的质量,直接影响测试结果的准确性;文章分析了现有纯音信号发生器存在的问题,提出了一种基于微处理器ATMEG128的设计与实现方法;该发生器可生成频率在125Hz~8kHz、听力级为-10~120dB的精密纯音信号;其中,频率按1/3倍频程输出,听力级的最小调节精度可达0.5 dB,符合国家标准。     

基于GA的多路径测试数据生成器适配函数设计

提出了基于GA的多路径测试数据生成的概念和实现方法。讨论了为了实现多路径测试数据生成,设计有效的和高效的适配函数应考虑的因素,用实际案例针对提出的适配函数进行了功能性能验证。结果表明了适配函数设计的有效性。     

高速脉冲信号源的设计与实现

高速脉冲信号源是数据采集系统的重要组成部分,常用于系统的自检与测试中.根据实际要求,提出了高速运放调理和高速电子开关两种方案.分别对高速运放、信号幅值调理、驱动电路和高速电子开关的选择进行了研究,给出了具体的硬件电路设计.并结合相关理论,分析了信号在传输过程中出现的反射现象,提出了符合要求的解决方案.此高速脉冲信号源已成功应用于某采集设备的自检和测试中,效果良好.     

带多比特记忆组合生成器的密码分析

带记忆的组合生成器可以提高生成器的代数次数和相关免疫阶数,是一种重要的密钥流生成器。为此,研究带多比特记忆的组合生成器的概率模型,分析带多比特记忆的组合生成器的k阶相关免疫的充分必要条件,计算其输出序列与输入序列相关系数的平方和,并给出平方和的一般计算公式。分析结果表明,满足一定条件的带多比特记忆的组合生成器可以较好地抵抗相关攻击。     

Control of ignition delay in microfabricated hot-wire igniters: Simulation, fabrication, and experimental results

The presented work studied thermal interactions between laminated, metal-foil, hot-wire igniters and exothermic solid-state, composite chemical systems in order to demonstrate precise timing control of a thermal ignition process. The study includes FEA modeling, device fabrication, and characterization to demonstrate control microthruster ignition delays to within 2 ms. The modeling included studies of total ignition delay as well as the ignition delay variation versus process variations. Microthrusters were then fabricated via printed circuit board lamination, and the ignition performance was characterized. The characterization showed agreement with modeling to within 2-sigma for most cases. And the characterization demonstrated that the ignition delay could be controlled to within 0.36 and 0.84 ms for the best case. Furthermore, this performance was demonstrated with a small battery supply (200-600 mAh) and minimal electronics in the ignition system. This work extends the use of current microthrusters to short-lifetime applications that need high forces delivered in millisecond time intervals.     

发动机嵌入式传感器自主供电装置

通过热电形式,发动机内部的废热可以为嵌入式传感器提供工作所需要的电能。根据温差发电原理设计了一种能够利用发动机内部存在的温度差为嵌入式传感器供电的装置。它由集热板、隔热层、散热装置以及相应的电源管理电路组成。在负载与发电器件内阻匹配和最低温度差为10℃的条件下,电源管理电路能够将发电器件输出的0.52 V电压转化为5.06 V、4.57 mA的稳定输出。建立了实验模型,且通过实验进行了性能验证。     

基于MDA的代码生成器设计与实现

针对如何将业务模型转换为程序代码的问题,提出一种代码生成器设计方案,用以实现模型驱动架构中代码的自动生成。介绍采用XML描述的面向业务对象的平台无关模型,在此基础上设计实现代码生成器,完成从平台无关模型到代码的自动转换,以支持在业务模型变化后系统行为的快速变化和代码的自动生成,通过实例演示该代码生成器的应用。