基于可控电抗器的单调谐滤波器的两种控制方法比较

可控电抗器作为电力设备中常用的一种非线性装置,其控制方式直接影响设备的整体性能.本文从可控电抗器的控制特性出发,阐述了基于可控电抗器的单调谐滤波器的两种控制方法,即相位跟踪控制法和自寻最优控制法.比较了两种方法在110V工作电压下的控制效果及各自的应用环境.     

Extending Dynamic Range of Phase Diversity

A method for extending dynamic range of phase diversity (PD) is proposed. The estimating of pupil phase is divided into two steps. Low-order Zernike coefficients of the phase are estimated firstly before all of the Zernike coefficients estimated. The method is based on the assumption that the aberrations of the system are dominated by low order Zernike modes, which is true to most practical situations. The algorithm of Broyden-Fletcher-Goldfarb-Shanno(BFGS) is used in the two steps for optimizing process. Computer simulations are conducted after the theoretical analysis. The result shows that this method can effectively avoid the trap in local minimum during iteration process, and the dynamic range that PD can detect extends from about 2λ to about 4λ.     

Study on Echo Time-Delay Estimation of Pulsed Laser Fuze

Pulse laser range detector is to measure the distance by estimating the time delay between the emitting pulse and echo pulse.In this paper,a mathematical model for the target echo signal of laser fuze has been established;in accordance with this model,the formulas for echo time-delay estimation and for amplitude estimation based on least squares criterion have been deduced.It is argued and simulated that the resolution of echo time-delay estimation could be improved through multi-reference correlation appro...     

高密度PCB对CO_2激光吸收率的应用研究

高密度PCB板的微细孔加工普遍采用激光加工微孔,但PCB板中铜箔对CO2激光的反射率高,会造成铜箔突起和裂纹,能量过小时又无法进行加工,若采用保型掩模加工技术,工艺较复杂.通过光致等离子体分析研究了提高铜箔对激光能量吸收的方法,实验表明:该方法不仅可简化加工步骤,还可进一步提高加工效率.     

Phase field simulation of the 180°domain-switching process in PbTiO_3 single crystal under an antiparallel electric field

The process of 180°domain switching in PbTiO_3 single crystal under an antiparallel electric field was investigated by the three-dimensional phase field simulation,especially the effect of electric field on the type and duration of domain switching.It is found that the polarization reversal of domains takes place under an antiparallel electric field in PbTiO_3 single crystal.The results of the phase field simulation indicate that there is only 90°domain switching under a weak electric field.With the rise...     

Monitoring slope deformation using a 3-D laser image scanning system:a case study

An ILRIS-36D 3-D laser image scanning system was used to monitor the Anjialing strip mine slope on Pingshuo in Shanxi province.The basic working principles,performance indexes,features and data collection and processing methods are illustrated.The point cloud results are analyzed in detail.The rescale range analysis method was used to analyze the deformation characteristics of the slope.The results show that the trend of slope displacement is stable and that the degree of landslide danger is low.This work indicates that 3-D laser image scanning can supply multi-parameter,high precision real time data over long distances.These data can be used to study the distortion of the slope quickly and accurately.     

高速公路稳定期桥头跳车治理及其路面改善设计

在判定桥头路基沉降进入稳定期后,采用纵坡拟合并辅以路面改善的设计方法,以永久消除桥头跳车给司乘人员带来的不良感受.此设计方法首次在我省高速公路几处桥头应用并实施,经过三年来的运营,使用效果较好.本文对此类设计经验进行了总结,供有关养护设计参考.     

GaN基LED与Si键合技术的研究

采用金属键合技术结合激光剥离技术将GaN基LED从蓝宝石衬底成功转移到Si衬底上。利用X射线光电子谱(XPS)研究不同阻挡层对Au向GaN扩散所起的阻挡作用,确定键合所需的金属过渡层。利用多层金属过渡层,在真空、温度400℃和加压300 N下实现GaN基LED和Si的键合,通过激光剥离技术将蓝宝石衬底从键合结构上剥离下来,形成GaN基LED/金属层/Si结构。用金相显微镜及原子力显微镜(AFM)观察结构的表面形貌,测得表面粗糙度(RMS)为12.1 nm。X射线衍射(XRD)和Raman测试结果表明,衬底转移后,GaN基LED的结构及其晶体质量没有发生明显变化,而且GaN与蓝宝石衬底间的压应力得到了释放,使得Si衬底上GaN基LED的电致发光(EL)波长发生红移现象。     

基于相位调制器倍频技术产生56GHz毫米波的光载无线通信系统

提出并实验研究了一种基于光相位调制器(PM)倍频技术产生56GHz毫米波的光载无线通信(RoF)系统。在中心站,通过28GHz射频(RF)信号驱动PM产生了56GHz光毫米波,并将下行的2.8Gb/s开关键控(OOK)信号调制到该光载波上,然后经过20km标准单模光纤(SSMF)传输至基站,最后由天线进行发射。用户终端接收后,采用相干解调恢复出基带信号。实验结果表明,56GHz光载毫米波信号经SSMF传输20km后其功率代价小于1dB,通过无线方式传输1.1m后其功率代价小于2.5dB。     

DBR光纤激光器拍频传感及其组网技术研究

研究了基于单纵模分布Bragg反射(DBR)光纤激光器的拍频解调传感技术,并对其组网技术进行了探讨。由于光纤本身的固有双折射,DBR光纤激光器能够产生两种正交偏振模式的激光,而这两种偏振模式的频率差拍会在射频域形成对温度变化极为敏感的拍频(beatfrequency)。实验结果表明:在20～100℃的温度范围内,激光器拍频随温度的增加呈线性减小,其线性拟合度高达0.99981,拍频灵敏度为0.51063MHz/℃。这种偏振式光纤激光器具有高输出功率、高信噪比、低解调成本和窄输出线宽等特点,有助于构建大规模的光纤有源传感网络。参考近年关于光纤传感网络的报道,提出一种有源光纤环形传感网络的构想。