A broadband GaAs MMIC frequency doubler on left-handed nonlinear transmission lines

A broadband frequency doubler using left-handed nonlinear transmission lines(LH NLTLs) based on MMIC technology is reported for the first time.The second harmonic generation on LH NLTLs was analyzed theoretically. A four-section LH NLTL which has a layout of 5.4×0.8 mm~2 was fabricated on GaAs semi-insulating substrate. With 20-dBm input power,the doubler obtained 6.33 dBm peak output power at 26.8 GHz with 24-43 GHz—6 dBm bandwidth.The experimental results were quite consistent with the simulated results.The compactness and the broad band characteristics of the circuit make it well suit for GaAs RF/MMIC application.     

声表面波传感器阵列识别毒剂研究

以聚环氧氯丙烷(PECH)、硅酮(SE-30)和两种氢键酸性聚硅氧烷(BSP3、PTFP)为敏感膜制备了对毒剂敏感的声表面波(SAW)传感器阵列.基于这种SAW传感器阵列对沙林、芥子气和甲基膦酸二甲酯进行了检测,并结合概率神经网络(PNN)对检测结果进行识别,识别率达90%,对上述3种气体的检出限分别达到0.30 mg/m3、0.30 mg/m3和0.07 mg/m3.     

Design and implementation of a real-time eye tracking system

Driver fatigue severely affects driver's alertness and ability to drive safely. There are vital problems related to drivers fatigue on driving of trains, vehicles and airplanes. Therefore, the driver fatigue research is important. In this paper, we first study the impact of eye locations on face recognition accuracy, with Haar-like feature and AdaBoost classifier, face and eye area can be detected quickly and accurately. In the part of eye tracking, cam-shift based mean-shift algorithm is used to track the eyes. This method could automatically adjust the size of tracking window according to the different posture of driver. The performance of our eye detection method is validated by using image database with more than 6000 pictures. In addition, our real-time eye tracking system has been tested on railway line segment (China). There are 5 train drivers involved in the experiment. The validation shows that our eye detector has an overall 93% eye detection rate.     

波导参数和传播常数对光折变表面波的影响

基于质点振荡的模型和数值模拟的方法,研究了波导参数和传播常数对光折变晶体与线性电介质界面光折变表面波类型和局域表面波模的影响。当波导参数大于传播常数时,在光折变晶体与线性电介质界面可以产生非局域表面波。当波导参数小于传播常数时,在光折变晶体与线性电介质界面可以产生振荡表面波和局域表面波。在局域表面波形成的系统内,正波导参数的光波能量比负波导参数的光波能量在光折变晶体内聚集得多。在给定一个局域表面波形成的物理系统,传播常数越大,表面波在线性电介质和光折变晶体中衰减就越快,对应表面波模的波峰离界面就越近。     

无卷边单分子层WS2纳米片原子结构的高分辨电子显微术研究

本文利用高分辨电子显微术(HRTEM)确定了无卷边的单分子层WS2纳米片的原子结构像.通过对样品不同区域HRTEM像进行傅里叶变换(FFT)分析,得到了各个区域的WS2纳米片的晶体取向,确定了WS2纳米片分子层数分布.根据电子显微像强度与样品层数的线性关系以及WS2纳米片的单分子层数分布模型,确定不同区域WS2纳米片的分子层数.为了进一步定量分析结果的正确性,通过模拟电子显微像在不同碳膜厚度及不同成像条件下WS2纳米片的HRTEM像,也确定了在像衬度上与实验像很好的匹配.     

利用共振隧穿器件制作太赫兹波源

太赫兹波是振荡频率在100GHz～10THz范围的电磁波,利用共振隧穿器件高频高速的特点,适宜制作此波段的振荡源器件。指出与其他类型的太赫兹源器件相比,共振隧穿型太赫兹波源器件具有体积小、重量轻、便于与控制电路集成以及易于进行调制等特点;此外,还适宜用Si透镜进行功率合成,增大其总发射功率。给出几种重要太赫兹共振隧穿器件的结构、制造工艺和器件性能,作为太赫兹技术领域的研究人员选择太赫兹波源器件的参考。     

The stability analysis of rolling motion of hypersonic vehicles and its validations

The stability of the rolling motion of near space hypersonic vehicles with rudder control is studied using method of qualitative analysis of nonlinear differential equations, and the stability criteria of the deflected rolling motions are improved. The outcomes can serve as the basis for further study regarding the influence of pitching and lateral motion on the stability of rolling motion. To validate the theoretical results, numerical simulations were done for the rolling motion of two hypersonic vehicles with typical configurations. Also, wind tunnel experiments for four aircraft models with typical configurations have been done. The results show that: 1) there exist two dynamic patterns of the rolling motion under statically stable condition. The first one is point attractor, for which the motion of aircraft returns to the original state. The second is periodic attractor, for which the aircraft rolls periodically. 2) Under statically unstable condition, there exist three dynamic patterns of rolling motion, namely, the point attractor, periodic attractor around deflected state of rolling motion, and double periodic attractors or chaotic attractors.     

谱曲软件的开发与应用

随着科学技术的飞速发展,以及人民物质精神文化生活质量的逐渐提高,人们对于音乐的追求也越来越高。大型的演唱会和各类综合文艺晚会不仅要求演员艺术水平高超,对音乐效果和音乐表现力也有了较高需求。由此,MID（I乐器数字接口）应运而生。通过MIDI技术可以将不同乐器的优势集中到一起,形成其他乐器无法创作比拟的特殊音乐效果,但是,MIDI技术无法实现对音乐作品乐谱的分析。因此,迫切需要一种能够实现乐谱分析的软件程序对MIDI乐谱文件进行解析,实时翻译成乐谱来满足演奏者的需求。本文基于以上背景,提出了一种解析MIDI文件的谱曲软件分析工具开发方案,可以实现对MIDI乐谱文件的分析,将其翻译成对应的乐谱,使乐谱能够直观展示在演奏者面前。     

介质波导阵列的横向传播特性分析

根据已提出的有关二维周期介质严格分析理论，针对介质波导阵列进行了大量的数值计算。对介质波导阵列中波的横向传播作了详细分析。首先，在给定纵向波矢量(k)的情况下，分析了在不同工作频率时的横向波矢量间布里渊区色散特性，对空间谐波的相互作用情况也进行了研究。其次，在给定工作频率的情况下，分析了不同纵向波矢量和不同调制系数时的横向波矢量间布里渊区色散特性。由于空间谐波的相互作用随纵向波数或调制系数的增大而增强，导致阻带能明显地表现出来，从而使介质波导阵列的横向传播特性能较为全面地得到分析。     

嵌入式在皮肤听声器中的应用

为了提高获取不同环境声音信号的能力,设计了基于嵌入式的皮肤听声器.通过对现今国内外助听器现状的比较,揭示皮肤听声技术的优势在于不依赖于入耳的任何残余听力并能从从根本上解决聋人的听力问题.同时,阐述了将嵌入式技术应用于皮肤听声技术的原因在于内置模拟电子电路不好的信号处理能力,并着重从非线性音量放大、自动音量调节系统、数字带通滤波和多通道输出等四个方面介绍了设计方案.创新在于将数字技术引用到了传统的皮肤听声技术中.