A Lamb wave device for a communication system with ternary logic

A new type of Lamb wave device for signal processing with ternary logic is presented. The transducer consists of a group of three electrodes deposited on two surfaces of a thin piezoelectric substrate. One is on the bottom surface as a common earth electrode. The other two are interdigital electrodes on the top surface. By using the device having two transducers, a communication system with ternary logic is demonstrated.     

Ray analysis of mutual coupling between point scatterers in RCS diagram

When scattering on a complex radar target modelled by point scatterers is calculated, interference functions between the signals issuing from these points taken two by two are made to intervene, yet, when these functions are experimentally measured on two reducible objects with two point scatterers, considerable difference from theoretical expectations can be seen. We will show that these differences result chiefly from the mutual dependence between the objects and, by a calculation based solely on the laws of geometric optics, we propose a correction of the fundamental interference functions. The results obtained with the help of this correction are in excellent agreement with the experimental measurements, even in the case where the scattering objects are in contact.     

Passive time delay estimation in non-Gaussian noise

This article deals with the structure of the maximum-likelihood (ML) estimator for time delay with arbitrary signal and noise statistics. At high signal-to-noise ratios (SNRs), the ML estimation performs a nonlinear operation on the delayed difference of the two received waveshapes. The required nonlinearity depends only on the noise statistics. At low SNR, a closed-form simple expression for the ML, which depends only on the noise statistics and on the second-order statistics of the signal, is provided. With statistically independent noise processes, the estimator correlates two vectors generated by separate nonlinear operations on the two received waveshapes     

新型波导缝隙天线反射特性的研究

本文根据等效源原理的分析了一种新型裂缝天线的反射特性，一个或两个横缝位于馈电矩形波导终端的短路面上。     

基于圆光栅莫尔条纹的CGH元件对准

在双计算全息（CGH）检测非球面的方法中,两片CGH元件位置的精确对准是确保高精度测量的必要前提,针对一凸双曲面检测系统,提出了在主CGH的外围刻制四组圆光栅付的方法来实现该系统中CGH元件的精确对准,其原理基于两个栅线频率相近的同心圆光栅重叠能产生莫尔条纹,通过观察条纹的变化来判断两光栅（一组光栅付）的相对偏移,各组光栅付若同时达到同心,两元件亦便对准。通过对圆光栅进行建模,分析了莫尔条纹产生的原理,仿真模拟了Ф5mm口径内分别包含49个和50个同心圆（周期50μn）的两圆光栅在不同偏移时的条纹图,且实际制作了这样的两个圆光栅,并采集了两光栅重叠后的条纹图,其结果表明,眼睛很容易分辨出1／20周期即2．5μm的偏移。     

线性二端网络的等效电路的另一分析方法

主要从求解线性二端网络端口电流电压关系方面,介绍了一种直接求解含源和不含源线性二端网络的等效电路的通用分析方法,而不必根据戴维南定理或诺顿定理分两步来求等效电路。同时对线性二端网络内部可能含独立源和不含独立源,以及含受控源和不含受控源的几种情况作了详细的讨论,对线性二端网络端口电流电压关系的数学表达式中的物理量也作了详细的说明,并根据这些表达式画出了相应的等效电路图。     

Assignment of inter-die signals in a simplified wiring model for die-stacking SiP designs

Compared with traditional flow in IC designs, the assignment of the inter-die signals between different dies is an important stage in a die-stacking SiP design. In this paper, given a tolerant spacing rule between two inter-die signals, the crossing constraint between two inter-die signals can be firstly defined for the bonding wires in a die-stacking SiP design with a simplified wiring model [7]. Furthermore, based on the connection constraint on any inter-die signal, the capacity constraint on any assigned pad on dies and the crossing constraint between two inter-die signals, an integer linear programming-based (ILP-based) approach is proposed to assign all the inter-die signals to minimize the total wirelength in a die-stacking SiP design. Compared with Lin’s two-stage approach [4] for some tested examples without a tolerant spacing distance between two inter-die signals in an Euclidean wiring model, the experimental results show that our proposed ILP-based approach increases 4.5% of CPU time and reduces 6.2% of total wirelength to assign all the inter-die signals on the average. Besides that, compared with Yan’s iterative approach [6] for some tested examples without a tolerant spacing distance between two inter-die signals in an Euclidean wiring model, the experimental results show that our proposed ILP-based approach uses reasonable CPU time to reduce 5.3% of total wirelength to assign all the inter-die signals on the average. Compared with Lin’s modified two-stage approach and Yan’s modified iterative approach for some dense tested examples with a tolerant spacing distance between two inter-die signals in a simplified wiring model [7], the experimental results show that Lin’s modified two-stage approach only achieves 95.9% of the assignment ratio on the average, Yan’s modified iterative approach only achieves 96.6% of the assignment ratio on the average and our proposed ILP-based approach uses reasonable CPU time to achieve 100% of the assignment ratio.     

基于RSA的多重数字签名

基于RSA和哈希函数求逆的困难性给出了两种多重数字签名方案，一种是可验证的按序数字多重签名，另一种是广播数字签名。在该两种方案中签名的长度不随签名者的人数线性增长，并且能够抵制各种勾结，具有计算量少、通信量低等特点。     

一种基于方差融合的双均匀线阵阵列测向算法

本文提出了一种基于双均匀线阵的快速高精度测向算法。针对双均匀线阵不同轴上的接收噪声互不相关的特点,可以得到理论上不含噪声的互相关矩阵。并且由于在两个轴上的阵列流型均具有移不变特性,因此本文所提的快速算法首先利用x轴上最大不重叠的两个子阵列对y轴上最大不重叠的子阵列做互相关,利用y轴上最大不重叠的两个子阵列对x轴上最大不重叠的子阵列做互相关,接着对上述两个相关矩阵采用旋转不变子空间算法,分别计算出目标的角度,再利用方差融合的方法,将两次求得的角度信息进行融合,最后得到较高精度的角度信息,理论分析表明该算法是无偏的,并且在较高信噪比下趋近于克拉莫罗界。最后利用蒙特卡洛仿真验证了本算法的有效性。      

一种借助单基中点测向所实现的双机时差定位方法

设双机同向同速沿直线飞行,利用单基中点测向法,通过两次测量目标的时差,即可在两个不同位置处得到目标的方位角,在此基础上,基于三角定位原理即可获得目标距离的线性解析解。与平面三机时差或双机测向交叉定位法相比,借助单基中点测向法所得到双机时差定位法具有更好的定位精度。     

Phase-insensitive all-optical transistors based on second-ordernonlinearities

We demonstrate and compare two phase-insensitive all-optical transistors (AOT's) based on frequency-degenerate quadratic three-wave interactions. In particular, we demonstrate gain using KTP in a type II geometry. Both AOT's exploit the phase insensitivity inherent to three-wave parametric processes when only two fields are input, providing amplification of a small signal at the operating frequency via the interaction with a second-harmonic wave. The first scheme is based on successive up- and down-conversion (i.e., cascading) while the second relies on parametric down-conversion. We obtain gains of 5 and 160 in the two configurations, respectively, with a significant background and output coherent to the pump in the first case, no background and coherence between output and signal in the second     

Monolithic 2-D scanning mirror using self-aligned angular vertical comb drives

We have demonstrated microfabricated, monolithic two degrees of freedom (two-dimensional) electrostatic torsional mirrors using a three-mask process on silicon-on-insulator wafer with a single plastic deformation step. The mirror operated independently in two orthogonal directions as controlled by two sets of self-aligned angular vertical combs. The measured dynamic performance showed resonant frequencies of 10.56 and 1.54 kHz with optical scanning angles up to 27/spl deg/ and 20/spl deg/ in the two orthogonal axes, respectively, under driving voltages of 20 V/sub dc/ plus 15 V/sub pp/. A 90-day continuous mirror operation at peak resonance, in equivalent to 80 and 12.1 billion cycles on the two orthogonal axes, showed negligible performance variations.     

基于外差探测的双金属片结构FBG温度传感系统

提出了一种基于外差探测的双金属片结构光纤布拉格光栅(FBG)温度传感系统方案.将两个相同的FBG粘贴在膨胀系数不同的两个金属片上,利用两个金属片膨胀系数的不同,使两个FBG产生不同的中心波长的漂移,通过一个光电二极管探测其光强,再利用外差技术解调出温度的变化.与传统的双光纤布拉格光栅的系统不同的是,该系统中的参考FBG也能感测温度的变化,通过两个FBG反射波产生不同的相位差来获得温度的变化.数值仿真和理论分析表明该系统解决了传统M-Z干涉仪在测量温度时,应变与温度交叉敏感的问题.但是由于该系统的探测精度高,会导致量程范围的降低.因此该系统适用于温度变化不大,但精度要求比较高的情况.

Abstract：

Proposed is a double-sheet-metal structure FBG temperature sensor system based on heterodyne detection. Two same FBGs are affixed on two sheet metals with different coefficient of linear thermal expansion, because of which the changes of the two FBG's reflected wavelength are different, the two reflected signals are detected by a photoelectric detector, and the change of temperature can he obtained by detecting phase difference between the two reflected signals, which is different from that of traditional double FBG system. The two sheet metals make the two FBG in the same surrounding, and the two FBGs are affected by the same phase noises, which will not introduce phase difference between the two FBGs. Numerical simulation and analysis show that this system can solve the cross-sensitivity problem, but the high detection accuracy results in a narrow detection range. So the system applies to the situations which need high detection accuracy but narrow detection range.     

Millimeter-Wave Frequency Tripling Based on Four-Wave Mixing in a Semiconductor Optical Amplifier

An approach to generating a frequency-tripled millimeter-wave (mm-wave) signal based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) is experimentally demonstrated. In the proposed system, two phase-correlated optical wavelengths generated by an optical phase-locked loop (OPLL) are used as two pumps to generate the FWM process in the SOA. Two idlers with a wavelength spacing three times that of the two pump wavelengths are obtained. The two pump wavelengths are then removed by two cascaded fiber Bragg gratings serving as an optical notch filter. By beating the two idlers at a photodetector, an mm-wave with a frequency that is three times that of the OPLL reference source is generated     

An innovative drive for wheeled mobile robots

Introduced In this work is an innovative drive for wheeled mobile robots, that is based on two identical, coaxial wheels, independently driven by two identical motors. The common axis is capable of rotating about a vertical axis. The drive, termed dual-wheel transmission (DWT), is composed of two identical epicyclic gear trains, lying at two different levels and coupled by a common planet carrier. The latter can turn freely with respect to the robot platform carrying the motors, the transmission having as a stand-alone unit, three degrees of freedom and only two motors, which makes it underactuated. Upon coupling this drive with two other wheel units, which is the minimum required for static support, a robot with mobility of three is produced with the underactuation thereby disappearing. Finally, the dimensioning of the DWT is reported for robustness against manufacturing, actuation, and sensing errors.     

正态型指标的Bayes可靠性验证试验设计

可靠性统计验证试验设计是基于给定的风险要求,对产品的试验方案进行规划,给出试验实施中产品的抽样方案。根据Bayes理论,在复杂假设的情况下,对性能参数服从正态分布的产品可靠性进行了统计验证试验设计。综合考虑试验风险和两类风险的约束要求,建立了求解最小样本量的非线性约束规划模型;利用0-1损失函数,按照验后损失最小的原则,推导了基于样本均值的决策临界值,建立了两类风险与样本量之间的函数关系;依据样本量的取值与两类风险的关系,给出了基于MATLAB的最小样本量计算步骤;最后用示例展示了求解的具体过程。     

矢量的线上投影表示法

本文提出一种矢量压缩编码新方法—线上投影法.它将输入矢量用它在某条空间直线上的投影近似表示,而用决定这条直线的两个参考点的序号和一个反映该投影点相对于两参考点位置的比例因子作为编码.由于一个大小为N的矢量量化码书中的码字可以确定N(N-1)/2条直线,因此这种方法可用较小的码书获得很高的编码精度.理论分析和实验结果表明:码书大小为N的线上投影法的编码精度与码书大小为N²的矢量量化法相当,并且明显优于用两个大小为N的码书构成的两级矢量量化法,而其码书生成和编码过程的计算复杂度均远远低于后者.它将是矢量信号高精度压缩编码的一种强有力的手段.     

Substrate integrated waveguide (SIW) asymmetric dual-mode filter and diplexer

Substrate integrated waveguide (SIW) can be used to implement high Q waveguide components with the same easy and low-cost fabrication process as planar circuits. In this paper two inline three-pole dual-mode filters with asymmetric transmission response based on SIW are presented. These two filters, consisting of a TE₁₀₂-TE₃₀₁ dual-mode SIW cavity and a TE₁₀₁ mode SIW cavity, are centred at around 10?GHz with a transmission zero on the left of the passband and the right of the passband, respectively. Based on the two kinds of three-pole deal-mode filters, a diplexer with isolation better than 35?dB is developed. A linear microstrip taper is used to implement the transition between microstrip and SIW. The measured results agree with simulated results.     

SIMPS: Using Sociology for Personal Mobility

Assessing mobility in a thorough fashion is a crucial step toward more efficient mobile network design. Recent research on mobility has focused on two main points: analyzing models and studying their impact on data transport. These works investigate the consequences of mobility. In this paper, instead, we focus on the causes of mobility. Starting from established research in sociology, we propose SIMPS, a mobility model of human crowds with pedestrian motion. This model defines a process called sociostation, rendered by two complimentary behaviors, namely socialize and isolate, that regulate an individual with regard to her/his own sociability level. SIMPS leads to results that agree with scaling laws observed both in small-scale and large-scale human motion. Although our model defines only two simple individual behaviors, we observe many emerging collective behaviors (group formation/splitting, path formation, and evolution).     

一种新型矩形波导裂缝天线的分析与设计

针对任意两个横缝位于馈电矩形波导终端的短路圆盘上的情况.本文运用伽略金方法分析了一种新型双裂缝天线的反射与辐射特性:分析中考虑了缝隙间的内部互耦与外部互耦:根据分析结果,首次设计并研制了这种工作于C波段的新型天线,实验结果和设计指标吻合较好.它适合高速飞行器载体的特殊应用.