激光熔覆镍基和钴基自熔合金的研究

本文采用镍基、钴基自熔合金通过激光熔覆获得性能优良的合金覆层,改善了叶片的耐磨性、耐蚀性,达到了提高使用寿命达10倍以上的目的。     

电子束聚焦偏转系统中透镜加工误差效应的数值计算

本文讨论了由于电磁透镜中电极和极靴加工的误差(孔径椭圆度和端面倾斜)造成电子束系统电子光学性质影响的数值计算问题,包括用有限元法计算具有孔径椭圆度和端面倾斜的透镜中电磁场的分布,电子轨迹方程和像差积分式等。最后给出了用所编制的计算机程序计算的若干个加工误差效应的实例。     

光纤预制棒(MCVD法)的工艺理论研究

本文对光纤预制棒(MCVD)的工艺机理进行了理论分析,建立了沉积过程中的微粒沉降模型,该模型的基本原理与实验观察一致。对渐变型折射率分布多模光纤的结构分析表明,MCVD法能精确地控制a参数和数值孔径,为提高沉积速率和生产效率开辟了应用途径。     

Dielectric Properties in the Microwave Range of K<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>NbO<Subscript>3</Subscript> Ceramics

Dielectric properties of a potassium sodium niobate (KNN) system in the microwave range up to GHz have rarely been studied. Since K_0.5Na_0.5NbO₃ is the most common and typical type of KNN materials, non-doped K_0.5Na_0.5 NbO₃ ceramics were synthesized at different temperatures (1080°C, 1090°C, 1100°C, and 1110°C) by a traditional solid reaction method for further characterization and analysis. The ceramics were in perovskite phase with orthorhombic symmetry. A small quantity of second phase was found in the 1110°C sintered specimen, which resulted from the volatilization of alkali oxides as the temperature increased. The complex permittivity was measured for the first time in the microwave range (8.2–12.4 GHz) and in the temperature range from 100°C to 220°C, and the effects of annealing on the dielectric properties were studied. The results indicate that the complex permittivity of KNN ceramics over the microwave range increases mainly due to high bulk density and the additional dielectric contributions of oxygen vacancies at high temperature.     

Novel high PSRR high-order temperature-compensated subthreshold MOS bandgap reference

Novel high power supply rejection ratio (PSRR) high-order temperature-compensated subthreshold metal-oxide-semiconductor (MOS) bandgap reference (BGR) is proposed in Semiconductor Manufacturing International Corporation (SMIC) 0.13 μm complementary MOS (CMOS) process. By adopting subthreshold MOS field-effect transistors (MOSFETs) and the piecewise-curvature temperature-compensated technique, the output reference voltage's temperature performance of the subthreshold MOS BGR is effectively improved. The subthreshold MOS BGR achieves high PSRR performance by adopting the technique of pre-regulator. Simulation results show that the temperature coefficient (TC) of the subthreshold MOS BGR is 1.38×10^?6/°C when temperature is changed from ?40 °C to 125 °C with a power supply voltage of 1.2 V. The subthreshold MOS BGR achieves the PSRR of ?104.54 dB, ?104.54 dB, ?104.5 dB, ?101.82 dB and ?79.92 dB at 10 Hz, 100 Hz, 1 kHz, 10 kHz and 100 kHz respectively.     

10Gb/s突发模式时钟数据恢复电路设计

突发模式的时钟数据恢复是10G EPON系统的关键技术之一。本文介绍了一种基于XNOR/XOR门的振荡器,分析了其工作原理与性能,以此为基础设计了半速率突发时钟恢复电路。设计采用SMIC 0.13?m CMOS工艺进行了流片验证,芯片面积为675?m ? 625?m。测试结果表明,该电路可以即时的实现10Gbit/s的突发数据恢复,恢复出的时钟数据符合IEEE 802.3av标准,锁定时间小于5bit。     

采用尺度不变特征和区域选择的图像配准方法

提出了一种改进的尺度不变特征点的图像配准方法。该方法在SURF算法的基础上使用图像的熵来对匹配图像作特征检测区域选择,建立特征点筛选机制来从初步的特征检测中得到最显著的特征点,以控制特征点的数目来减少后继的计算量和算法性能。同时改进了SURF的特征描述方法的计算过程,提出了一种改进的特征描述方法。实验表明,该方法在提高算法性能的同时,明显改进了特征点的匹配率。     

采用改进词袋模型的空中目标自动分类

为了解决飞机、直升机、导弹等3类空中目标图像的自动分类问题,提出了一种基于改进词袋模型的空中目标识别方法。首先采集3类多个型号的空中目标灰度图像并分割提取出目标,接着利用稠密采样方法进行SIFT特征提取,然后用模糊C均值聚类方法,对空中目标图像的SIFT特征进行聚类,得到大量空中目标图像的视觉单词。最后用视觉单词直方图训练支持向量机分类器,完成空中目标的自动分类。仿真实验表明,文中提出的算法能准确区分空中目标类别,性能优于传统的采用K均值聚类的词袋模型,且优于仿射矩。     

Efficient distributed traffic offloading algorithm based on SDN architecture

For addressing the problem of mobile data traffic offloading,network service cost minimization problem model was proposed,which considered the cost of base stations and the consumption of access points under the SDN architecture.Due to the defects of convergence speed and privacy security in the traffic offloading algorithm based on dual decomposition,the traffic offloading algorithm based on proximal Jacobian ADMM was proposed and an implementation scheme to ensure the privacy and security was designed.Meanwhile,the simulation results show that the algorithm based on the proximal Jacobian ADMM is superior to the dual decomposition algorithm in terms of convergence speed.