In掩膜层超分辨光盘的读出研究

在超分辨光存储技术中,掩膜层材料是决定其性能优劣的关键。In薄膜可以作为掩膜层用来实现超分辨信息点的动态读出。采用直流磁控溅射法制备不同厚度的In薄膜,用台阶仪测量薄膜厚度随时间的变化关系,用原子力显微镜观察不同厚度薄膜样品的表面形貌。在预刻有尺寸为390nm信息点的光盘盘基上制备In薄膜,从而形成In掩膜超分辨光盘。利用光盘动态测试仪进行动态读出,最高读出载噪比(CNR)达到26dB。为了进一步分析超分辨动态读出的物理机理,采用变温椭圆偏振光谱仪测量In薄膜在不同温度下的光学常数,得到In薄膜在不同温度下的反射率和吸收系数。分析表明In掩膜超分辨光盘的读出机理符合孔径型超分辨读出模型。     

基于LC-SLM的CT图像全息三维重构与实时显示

提出了一种将计算全息技术与液晶空间光调制器相结合的CT图像三维重构与实时显示的方法。用计算全息技术对一系列CT图片进行三维信息融合,并根据CT图片数目的不同,制作了不同的计算全息图,基于CT图片本身是数字化二维图像的特点,采用了快速傅里叶变换算法。用液晶空间光调制器作为全息图显示载体,设计了CT图像三维实时显示系统,利用计算机控制实时输出不同的计算全息图到空间光调制器,通过光学再现获得不断变化的三维再现像,实现CT图像的三维实时显示。     

采用磁集成技术的低压大电流DC/DC变换器的仿真

运用回转器一电容模型可以很好的理解磁性器件，特别是复杂的集成磁件。文章运用磁导电容类比建模法建立了磁件的回转器一电容模型。在回转器一电容模型中，磁路由容性电路来模拟，绕组由双端口的回转器来代替。进行了采用磁集成技术的低压大电流DC／DC变换器的仿真。仿真电路拓扑是原边不对称半桥、副边倍流整流电路。磁集成变压器的结构是Wei Chen提出的原边绕于中柱的只在侧柱开气隙的倍流整流磁集成结构。建立了用SPICE语言描述的回转器仿真模型。仿真软件是MULTISIM2001。     

基于消失点迭代重估的道路边缘检测

传统道路边缘检测算法很少能用于乡村道路。该文提出基于消失点迭代重估的道路边缘检测方法：Gabor滤波器估计像素纹理方向,同时计算对应的置信度;根据纹理方向,由置信度大于阈值的像素投票确定初始消失点;以初始消失点为起点,向下建立一组射线,并计算由颜色差和二倍角正弦函数加权的方向一致率,将最大值对应的射线作为初始道路边缘;交替采样两侧边缘,选取最优消失点,由此得到两条道路边缘。实验测试了不同类型的乡村道路图片,并与经典算法对比。结果表明该方法在乡村道路中具有较高精准度与鲁棒性。     

基于特征级融合和支持向量机的飞机识别

提出一种新的基于组合不变量的飞机识别方法。对不同飞机机型图像,提取Hu矩、仿射矩和归一化傅里叶描述子（NFD）3类不变量进行特征级融合。针对组合不变量取值范围较大问题,提出采用4种归一化方法,结合支持向量机（SVM）以提高飞机识别系统的分类性能。仿真实验表明,提取飞机的组合不变量特征,采用传统神经网络或SVM构建分类器...     

Neural network based MOSFET channel length and width decision method for analogue integrated circuits

The channel length and width of a MOSFET are two important parameters selected by the experience of the integrated circuit designer. Since drain current of a transistor is directly adjusted by the aspect ratio, the wrong selection of these parameters changes the circuit characteristics. In this work neural networks are used to decide the most suitable selection of channel length and width of MOSFET. Both p-channel and n-channel transistors are modelled by multi layer perceptron (MLP) neural network and the channel length and width are predicted by MLP. MOSFET level 3 is modelled by MLP, training and test data are obtained from HSPICE design environment with YITAL 1.5μ parameters. Developed network is tested with the current mirror and the differential amplifier circuits. Estimated aspect ratios for each transistor are compared with the HSPICE simulation results.     

220 GHz阶梯形和斜切形Vlasov辐射器

利用几何光学原理和矢量绕射理论,对工作频率为220G Hz,TE03模的阶梯形和斜切形这2种结构的VlaSov辐射器辐射特性进行数值分析.采用切口面上的功率指标,优化了阶梯形辐射器的切口长度;研究斜切形辐射器中斜切角度对辐射特性的影响,结果表明斜切角接近Brillouin角时可获得最佳转换效率;对于相同半径的Vlasov辐射器,阶梯形辐射器的辐射效率和远场增益优于斜切形辐射器.阶梯型Vlasov辐射器的辐射效率为98.28％.应用CST仿真软件,设计了半径为5 mm阶梯形辐射器,数值求解结果与仿真结果基本一致,验证了理论与计算方法的可靠性.     

Diffraction Efficiencies for Infinite Perfectly Conducting Gratings of Arbitrary Profile

Integral equations are obtained for the currents induced on an infinite perfectly conducting grating by a plane wave. The integral equations are approximated by matrix equations which are readily solved for the currents. Once the currents are known one can obtain the strengths of the grating modes. Numerical results are obtained for specific cases which have been considered previously in some optical experiments by Madden and Strong. The theoretical results are consistent with the conservation of energy. However, there are discrepancies with the experimental results. An equivalent problem of reflections in a terminated waveguide is also considered and good agreement between theory and experiment is obtained. The technique is extendible to dielectric gratings.     

Diffraction of electromagnetic waves by the interface of two isotropic planar waveguides

The problem of excitation of the rectilinear interface of two semiinfinite planar waveguides by an eigenmode of one of these waveguides incident onto the interface at an arbitrary angle is considered. Planar waveguides shaped as a dielectric plate coated by thin isotropic films (e.g., gratings with spacings small as compared to the wavelength) are analyzed. A model of this structure in which films are described by means of two-sided impedance boundary conditions and parameters of the planar waveguide are varied by varying the film impedance is constructed. Solution to the electromagnetic problem by the Wiener-Hopf technique is presented. Closed-form expressions for scattering parameters of the analyzed structure are obtained. Results of the numerical solution are presented. Comparison with available results obtained for particular values of the film impedance is performed.     

多晶硅衬底上的RF MEMS开关

在微机械开关与硅IC工艺设计和兼容方面进行了改进,获得了一种可与IC工艺兼容的RF MEMS微机械开关.采用介质隔离工艺技术把这种RF MEMS微机械开关制作在绝缘的多晶硅衬底上,实现了与IC工艺兼容;采用在金属膜桥的端点附近刻蚀一些孔的优化方法,降低了RF MEMS微机械开关的下拉电压.用TE2819电容测试设备测试开关的电容,测得开关的开态电容、关态电容和致动电压分别为0.32pF、6pF和25V.用HP8753C网络分析仪对RF MEMS微机械开关进行了RF特性测试,得出RF MEMS微机械开关在频率1.5GHz下关态的隔离度为35dB,开态的插入损耗为2dB,用示波器测得该开关的开关速度为3μs.     

Investigation of Intermodulation in a Tuning Varactor

2nd and 3rd order intermodulation distortions of a tuning varactor are analyzed by using nonlinear parameters P2 and ￠3 which are determined by the measured values of the diode capacitance. The calculated values by using ￠agree quite well with the experimental results for actual diodes. In addition, the methods of compensating the distortion by a fixed capacitor or another diode with appropriately divided bias voltage are discussed and it is shown that the nonlinearity is compensated even in the case of n greater than 0.5. These methods are particularly effective for a circuit with greater Q.     

Explicit formulas for the fundamental mode of a linear resonator with elliptic mirrors and construction of higher order modes

A linear resonator bounded by elliptic (hyperbolic) mirrors with noncoinciding principal curvature directions is considered. Explicit analytic formulas describing the fundamental mode of such resonator are derived in the principal approximation. A procedure of constructing higher order modes is developed. The potentialities of the technique are exemplified by considering a resonator with mirrors whose shapes are close to spheres and a resonator with elliptic mirrors whose shapes are close to each other.     

Applications of universal context modeling to lossless compressionof gray-scale images

Inspired by theoretical results on universal modeling, a general framework for sequential modeling of gray-scale images is proposed and applied to lossless compression. The model is based on stochastic complexity considerations and is implemented with a tree structure. It is efficiently estimated by a modification of the universal algorithm context. Several variants of the algorithm are described. The sequential, lossless compression schemes obtained when the context modeler is used with an arithmetic coder are tested with a representative set of gray-scale images. The compression ratios are compared with those obtained with state-of-the-art algorithms available in the literature, with the results of the comparison consistently favoring the proposed approach.     

基于软件仿真验证的含运放电路应用设计

概述了积分器和滤波器的工作原理,对这两种含运放典型电路的应用计算方法进行了说明,推导了输入/输出关系表达式,并采用Proteus仿真软件进行了仿真验证。结果表明,软件仿真与理论计算结果一致。给出了一种电压反馈取样电路的详细设计方法,该电路可以较好地反映输入信号的变化。针对滤波器快速设计方法中相位计算繁琐的不足,指出通过软件仿真可以准确、快捷地得出补偿量。     

解密成本为常数的具有追踪性的密文策略属性加密方案

该文针对单调访问结构提出了一个解密成本为常数的具有追踪性的密文策略属性加密(CP-ABE)方案,该方案基于合数阶双线性群实现了标准模型下的适应安全性。在所有已知的追踪性CP-ABE方案中,都使用线性秘密共享方案(LSSS)来表示单调访问结构,并用LSSS矩阵加密明文数据。因此,其加密成本都随着LSSS矩阵的大小成线性增长,同时解密成本则随着满足要求的属性数量成线性增长。而在该文提出的追踪性CP-ABE方案中,使用最小授权子集集合来表示单调访问结构,并用该子集集合加密明文数据。因此,其加密成本随着最小授权子集的集合大小成线性增长,对于某些单调访问结构,该文方案具有更短的密文长度和更小的加密成本。最重要的是,该文方案进行解密时,只需要3个双线性对操作和2个指数操作,解密成本为常数,实现了更快更高效的数据解密。最后基于合数阶双线性群下的3个静态假设对方案进行了安全性证明,并进行了性能分析与实验验证。     

The Influence of Surface Chemistry and Pore Size on the Adsorption of Proteins on Nanostructured Carbon Materials

Carbon films are synthesized by templating of anodic aluminum oxide films. These carbon materials exhibit nanochannels with controlled diameter and length. Selected chemical treatments are done to tailor the surface chemistry. The adsorption capacities of bovine serum albumin and cytochrome c are measured by temperature‐programmed desorption with mass spectrometry (TPD‐MS) analysis and with conventional biological assays. The first method allows quantification of the proteins that exhibit strong interactions with the surface, while the second one is used to obtain the total adsorption capacity. Moreover, the TPD‐MS profiles, which are related to the structural modifications of the proteins during the adsorption, show that strong interactions take place with hydrophobic surfaces. When oxygenated functions are present, the adsorption capacity increases and the nature of the interactions is modified. The ratio of irreversible to reversible adsorption is significantly different for the two proteins, and is slightly related to the surface chemistry. The influence of nanochannel size is studied: below 50 nm, the coverage ratio shows that access to the porosity is limited by diffusion in the channel and by pore plugging, in agreement with the strong interactions of proteins with the carbon surface.     

基于压缩感知的变尺度目标跟踪技术

为解决变尺度目标的跟踪问题,本文基于压缩感知理论设计了一种具有目标尺度不变性的目标跟踪方法。该方法首先通过插值的方式将初始帧中要跟踪的目标扩展细化至设定的模板图像大小,提取其压缩感知变换后的低维Haar-like特征作为模板特征并初始化分类器,其次利用卡尔曼滤波对待跟踪的图像帧中目标所在位置和尺度变化趋势进行预测,然后在预测目标所在位置周围提取多个不同尺度的待测目标样本并提取其压缩感知变换后的低维Haar-like特征,最后将这些特征送入分类器进行分类得到真实目标并更新分类器。经过实验验证,本文所设计的跟踪方法的平均跟踪成功率为77%,平均中心位置误差为12像素。能够实现对运动过程中发生尺度变化的目标的有效跟踪。     

移动散射体下的V2V信道相关性和多普勒谱特性研究

该文首次提出两种典型的移动散射体存在的车辆对车辆(V2V)的无线传播信道模型,一种是基于一次散射发射(SBT)和一次散射接收(SBR)的信道,另一种是基于两次散射(DB)的信道,并在这两种模型的基础上给出了同时包含一次散射发射,一次散射接收,两次散射和视距(LOS)分量的信道模型。在假设移动散射体的运动速度和方向都随机且运动速度较小和较大的散射体速度分别用指数分布和混合高斯分布来描述的情况下,给出了这些传播信道的复增益,通过计算得到了信道的自相关函数(ACF)和多普勒功率谱密度(PSD)。文中还将理论计算得到的多普勒谱与已有文献的测量结果进行了对比,两者符合得较好。     

Optical Interconnection Networks for Terabit Packet Switches

The challenge of building packet switches with terabit capacity is being met by wavelength division multiplexing (WDM) where the benefits of optical fiber are exploited. Two kinds of WDM-based bufferless optical interconnection networks are proposed in this paper to interconnect multiple electronic packet switch modules. One is based on 3-stage Clos principle and the other is based on broadcast-and-select principle. The proposed optical interconnection networks are implemented with small modular structures to provide capacities in the range of terabit per second. Their architectures, component and interconnection complexity, and power budget analyzes are presented. In addition, the crosstalk caused by the finite ON-OFF ratio of semiconductor optical amplifier is discussed. Bit error rates with respect to different ON-OFF ratios and extinction ratios are also evaluated. It is concluded that it is feasible to implement optical interconnection networks by using state-of-the-art WDM technology, and they are excellent candidates for future terabit packet switching systems.     

The German TV-Sat broadcasting satellite system

The design concept, service and communication modules, and characteristics of the TV-Sat system are described. Also discussed are the solar array, propulsion and antenna modules as well as the high-power amplifier. A dual control system is used for the coarse pointing of the satellite's body (by infrared earth sensors) and the fine pointing of antenna reflectors. Fine pointing is done by an RF-sensor and 2 pointing mechanisms (APM). In the case of TV-Sat, 90% of the power is required by the payload; only the subsystems AOCS (attitude and orbit control system), TTC (telemetry, tracking and command system), and UPS are not dependent on the payload. The power required by these subsystems is supplied by the solar array structure with an output of 68 W/m² and 19.4 W/kg. The methods by which a high mean temperature is achieved and heat dissipation problems are examined. In-orbit tests with TV-Sat 1 are presented