评价任意面型微光学元件制作误差的方法

提出一种可用于评价任意面型微光学元件制作误差的方法.利用泽尼克多项式描述微光学元件面型,针对元件检测过程中的旋转对准偏差,给出泽尼克系数随旋转角度的变化关系;以设计面型和实测面型之间的均方根偏差(RMS)为加工误差的评价指标,根据其相对于旋转角度的依赖曲线,最小的RMS即是加工误差.数值模拟结果表明,该方法可以将旋转对准偏差矫正,从而有效地评价了制作误差.该方法可应用于任意面型微光学元件的研制.     

用纳米粉制备线性NTC敏感陶瓷材料

重点研究了由CdO-SnO2-WO3系列(简称Cd-Sn-W)和CdO-Sb2O3-WO3系列(简称Cd-Sb-W)及由它们共同组成的双基体三相(Cd2Sb2O7,CdSnO3,CdWO4)结构线性敏感陶瓷的制备方法。给出了上述半导体陶瓷的电子转移式;分析了半导相Cd2Sb2O7和CdSnO3的导电机理和电阻-温度(R-T)曲线呈线性的机理,并对其他相关特性进行了分析和研究。独立地设计了用化学共沉淀方法制备上述NTC(负温度系数)陶瓷微粉的化学反应方程式,并对聚乙二醇和无水乙醇在制备纳米微粉时所起的防止颗粒发生团聚现象的作用进行了分析。由于大分子量的聚乙二醇几乎是无毒的,对人体基本无毒害作用,因而有广泛的推广价值。     

Speech Accent Profiles: Modeling and Synthesis

This article provides a brief introduction to speech accents and introduces a set of statistical signal processing methods for the modeling, analysis, synthesis, and morphing of English language accents. Accent morphing is the changing of the accent of a speech to a different accent, for example, from British to American.     

Modeling of Copper SIMS Profiles in Thin HgCdTe

Anomalous secondary-ion mass spectroscopy (SIMS) profiles of copper in thin pieces of HgCdTe are explained using the model used for diode formation by ion milling and ion implantation. In this model, the SIMS ion beam injects mercury interstitials into the HgCdTe as it etches the HgCdTe. The interstitials fill metal vacancies and kick copper off the metal lattice sites. The copper interstitials then diffuse either to the surface being etched, where it is removed and detected by the SIMS instrument, or deeper into the HgCdTe, where it annihilates vacancies. Good agreement between model predictions and experimental SIMS profiles are obtained.     

A Novel Technique for Measuring One-Dimensional Permittivity Profiles Using a Simple Non-Commensurate Planar Structure

A novel technique is presented for measuring one-dimensional permittivity profiles based on a simple planar structure. The measuring device consists of a transmission line loaded with open-ended stubs of non-commensurate lengths. The permittivity profile of the material under test is evaluated by simply measuring the attenuation pole frequencies in the transmitted RF signal due to the different loaded stubs. The proposed technique provides reliable results for both continuous and discontinuous permittivity profiles without requiring any a priori information of the unknown profile. Measurements using different materials have been performed resulting in good agreement with data from the literature.     

Development of a Portable Thermogenerator for Uncontrolled Heat Sources

This paper presents the development of a portable thermogenerator designed to work on uncontrolled heat sources. Its thermal behavior regarding both steady-state and transient regimens was analytically described and numerically solved by using a lumped capacity model. The ranges of heating power and power increasing rates have been determined to ensure safe operation, or give users advance warning in case of failure. In addition, this model is a useful tool for designing a controller system based on which a feasible thermogenerator can be developed. Experimental tests performed on a prototype based on a commercial BiTe module have demonstrated this goal.     

基于材料补偿的线性色散组合棱镜研究

作为传统的分光器件,棱镜的非线性色散缺陷限制了其在精密光谱仪器中的应用。从分析棱镜非线性色散产生的本质出发,建立了材料的色散模型,提出了一种线性色散组合棱镜设计方法。使用非线性系数T1和T2相近、线性系数V相异的两种材料,通过控制组合棱镜的参数和光线入射角可获得线性色散。最后通过建立线性色散组合棱镜的评价指标,对设计结果进行了科学、合理的评价,验证了设计理论的正确性。研究发现,组合棱镜能够有效改善棱镜的非线性色散缺陷,其改善程度依赖于两种材料的绝对非线性系数P。当P<0.01时,组合棱镜可获得线性色散,其色散曲线的非线性(Nonlinear, NL)优于5%。     

基于计算电磁学的一维线阵快速近场测量方法北大核心CSCD

研究了三种针对一维线天线阵列的快速近场测量方法,仅需二维近场扫描数据即可外推出线阵的单切面远场方向图。这三种单切面远场方向图测量方法包括平面/柱面波波谱展开法、等效源求解法和多极子平面波展开法。针对单切面方向图测量中二维格林函数存在的幅度误差,提出了一种幅度误差补偿方法,显著降低了原始近场数据外推变换得到的远场方向图的幅度测量误差。通过矩量法仿真得到的一维低副瓣线天线阵近远场数据及其比较结果验证了所提出方法的有效性,并通过仿真算例对比分析了不同外推方法之间的优缺点。其中基于计算电磁学的等效源展开方法及多极子平面波展开方法因其具有显著减少的采样点数、不存在数据截断以及灵活的采样位置等优点,可广泛应用于多种一维线阵单切面方向图测试应用场景中。     

线性光学器件和量子纠缠的产生

研究了奇偶相干态在量子信息领域的应用.以具有特殊非经典性质的奇偶相干态作为无损耗分束器的输入态,来制备量子纠缠.利用无损耗分束器的幺正矩阵表示和三维角动量转动群之间的变换,将分束器的输入和输出态密度算符联系起来,从而得到其输出关联光子数分布.若分别以真空态和奇或偶相干态作为分束器的两个输入态,得到的输出态是具有量子纠缠性质的.若以奇偶相干态分别作为分束器的两个输入态,其输出态将得到更为复杂的量子纠缠.     

Dispersion Characteristics of an Array of Parasitic Linear Elements

In this paper we study the properties of a transmission line consisting of an infinite array of conducting cylinders, placing emphasis on the dispersion characteristics of the lowest order slow wave mode. We present experimental results for the variation of phase velocity with frequency, and then, using a method of parameter estimation, determine the element current (distribution which best explains these observations. Assuming this distribution to be of the form we find that, for a given size of element, there is a value of /spl gamma/ which gives very good agreement for the variation of phase velocity over the frequency range of interest.     

Device-Technological Modeling of Integrated Circuit Elements with Improved Resilience to External Influences

This paper analyzes some features of the process and device simulation tools. The tools are analyzed as applied to the calculation of electrical characteristics for several integrated circuit (IC) devices operating under different external conditions. The model features having the maximum effect on the simulation results are identified.     

Modeling Material Properties of Lead-Free Solder Alloys

A full set of physical and thermophysical properties for lead-free solder (LFS) alloys have been calculated, including liquidus/solidus temperatures, fraction solid, density, coefficient of thermal expansion, thermal conductivity, Young’s modulus, viscosity, and liquid surface tension, all as a function of composition and temperature (extending into the liquid state). The results have been extensively validated against data available in the literature. A detailed comparison of the properties of two LFS alloys Sn-20In-2.8Ag and Sn-5.5Zn-4.5In-3.5Bi with Sn-37Pb has been made to show the utility and need for calculations that cover a wide range of properties, including the need to consider the effect of nonequilibrium cooling. The modeling of many of these properties follows well-established procedures previously used in JMatPro software for a range of structural alloys. This paper describes an additional procedure for the calculation of the liquid surface tension for multicomponent systems, based on the Butler equation. Future software developments are reviewed, including the addition of mechanical properties, but the present calculations can already make a useful contribution to the selection of appropriate new LFS alloys.     

Modeling and Realization of n-Dimensional Linear Discrete Systems

Using a general model for multidimensional linear discrete systems, a new non-minimal real ARMA realization is given for n-dimensional systems in AR forms. A definition of minimality which is compatible with both the underlying theory and its engineering applications, and some necessary conditions for minimality of multidimensional systems are given.     

碳纤维复合材料(CFRP)在直线电机上的应用

为了满足全自动键合机的高速和高定位精度的需求,对应用在直线电机的碳纤维复合材料进行了研究。通过对碳纤维复合材料和玻璃纤维复合材料的性能进行了分析比较,最终确定碳纤维复合材料具有更好的刚度及动态响应特性。     

Investigations of Broad-Band, Linear Phase Shifters Using Optimum Varactor Diode Doping Profiles

The problem of obtaining linear phase shift of microwave signals over a broad frequency range and its dependence on varactor properties is addressed. An important application of the linear phase shifter, the microwave frequency translator, is investigated in detail and various circuit configurations and varactor doping profiles are examined relative to their performance including suppression of undesired frequency components and bandwidth. Hyperabrupt or Read-type varactor diodes are found to be very useful in this application     

Control of Linear Chirps in Waveguide Bragg Gratings by Applying Designed Core Profiles

Chirped gratings can be readily implemented in uniform-period waveguide Bragg gratings (WBGs) by adopting a tapered profile in the core patterning process. Based on our analysis, we have demonstrated that controlled linear chirps can be generated in WBGs with specifically designed core-taper profiles. By virtue of our established design and fabrication techniques, the measured center wavelengths, bandwidths, and dispersion coefficients of our fabricated straight and tapered polymeric WBGs agree very well with the designed values. We also obtained fairly low polarization-dependent wavelength shifts from the straight WBGs owing to the adopted low-birefringence polymeric materials.     

通用企业/集成系统参考体系结构研究

通用集成系统参考体系结构(GEM)是一组用以描述所研究系统的不同方面和不同开发阶段的、结构化的、多层次多视图的模型和方法的集合,体现了对系统的整体描述和认识,为系统的理解、设计、开发和构建提供工具和方法论的指导,是进行企业诊断、经营过程重构及信息系统实施的参考和方法体系.相关的学者已经提出了各自的体系结构框架,目前正在进行综合与标准化的工作.以企业信息化工程实践的需求为目标,从一个新的角度构建了具有广泛指导意义的体系结构框架,较全面地解决了体系结构描述信息的汇聚性、全生命周期的连贯指导性和实用性的问题.     

一种压电材料的新型线性高电压驱动器

提出一种压电材料的新型线性高电压驱动器的研制方案,驱动器包括两大部分,即大功率、可对压电作动器进行正负向电压加载的闭环倍压放大式线性高电压驱动器;基于固态继电器的ON/OFF驱动器,内含压电作动器的电压加载控制模块和快速放电控制模块。该驱动器线性输出电压为直流电压(-220～+220V),输出频率可达3kHz。     

Design Method of Tunable Pixel with Phase‐Change Material for Diffractive Optical Elements

In this paper, we propose a scheme for designing a tunable pixel layer based on a Ge₂Sb₂Te₅ (GST) alloy thin film. We show that the phase change of GST can significantly affect the reflection characteristic when the GST film is embedded into a dielectric encapsulation layer. We investigate the appropriate positions of the GST film within the dielectric layer for high diffraction efficiency, and we prove that they are antinodes of Fabry–Perot resonance inside the dielectric layer. Using the proposed scheme, we can increase the diffraction efficiency by about ten times compared to a bare GST film pixel, and 80 times for the first‐to‐zeroth‐order diffraction power ratio. We show that the proposed scheme can be designed alternatively for a broadband or wavelength‐selective type by tuning the dielectric thickness, and we discuss a multi‐phase example with a double‐stack structure.