微波功率放大器预失真线性化技术分析

给出了两种基本形式的预失真线性化电路,对其工作原理和技术特点进行了分析。     

走向IMS的PS域核心网规划建设方案

在3G牌照正式发放之前，我们仍然需要为新一轮大规模网络建设继续做准备。3G网络和现有2G网络如何互连互通，数据用户如何在3G网络和2G网络之间进行无缝连接，如何使系统网络方便地演进到IMS构架，这些问题都需要大家思考。一个经济有效且易于演进的网络结构，将对运营商顺利开展新一代移动业务，快速抢占发展的制高点，起到相当关键的作用。     

动态模糊随机信息处理的数学方法

本文系统地概述了我们近年来提出的动态模糊随机信息处理的数学方法,内容包括模糊随机变量、模糊随机过程和模糊随机微分方程的基本解法等方面的基本概念、基本定义和某些重要的定理,以及动态系统的模糊随机响应与可靠性分析的方法等。这些方法是为我们研究工程实际问题的需要逐步发展起来的,对于处理某些类型的问题简便实用。     

Surface-enhanced Raman scattering study of polymer on metals. III. Chemisorbed polybenzimidazole and its corrosion-inhibiting properties at high temperature

Chemisorption of polybenzimidazole on silver and copper etched with nitric acid has been observed by surface-enhanced Raman scattering (SERS). The polymer is found to react chemically with silver, forming a complexed film on the surface. The SERS spectra show that polybenzimidazole film inhibits oxidation of the metal at high temperature, unlike chemisorbed benzimidazole, benzotriazole, and poly(4-vinyl pyridine). © 1992 John Wiley & Sons, Inc.     

Cover Picture: Toward Large‐Scale Alignment of Electrohydrodynamic Patterning of Thin Polymer Films (Adv. Funct. Mater. 15/2006)

By integrating lithography and self‐assembly via electrohydrodynamic instabilities, Russel and co‐workers are able to guide initially flat polymer films to evolve into periodic arrays of pillars over regions much greater in extent than their natural domain sizes, as detailed on p. 1992. Novel structures that involve a combination of linear ridges and pillars are also produced, mainly as as result of the dynamic merging among preformed pillars. To pattern thin polymer films via electrohydrodynamic instabilities, we design and utilize two different kinds of mask patterns to guide pillars into alignment over regions much greater in extent than their natural domain sizes. First, narrow protruding ridges that intersect to form regular patterns on the mask trigger the growth of pillars beneath. Later, square and triangular packings of pillars develop in the regions enclosed by those ridges, preserving the registry from one domain to the next over a much larger area than within individual domains in unpatterned portions of the mask. Second, small square protrusions that are prealigned into a large regular array on the mask guide the formation of square packings of pillars in domains that conform to the mask, forming a large array of pillars. Novel structures involving a combination of linear ridges and pillars are also produced mainly due to the dynamic merging among preformed pillars. Finally, we find vertex symmetry of the mask pattern is necessary for generating and preserving ordered patterns on the polymer film.     

Microstructural evolution of lead-free Sn-Bi-Ag-Cu SMT joints during aging

It was reported in a previous study that the Sn-6Bi-2Ag-0.5Cu solder alloy had great potential to replace leaded alloys. This alloy was prepared by mechanical alloying, and had the advantage of providing a high percentage of supersaturate solution of bismuth in tin. In the present paper, the microstructural evolution of surface-mount joints during aging was examined. In the as-soldered joints, small bismuth and Ag₃Sn particles of about 1 mum in size were found to be finely dispersed in a nearly pure tin matrix with a small amount of eta-Cu₆Sn₅ phase in the bulk of solder. During aging, microstructural evolution of solder joints occurred. These include Cu-Sn intermetallic compound (IMC) layer growth at the interface between solder and copper pad on the printed circuit board, as well as bismuth phase and Ag₃Sn phase coarsening. The shear strength of the solder joints decreased parabolically with the increase in IMC layer thickness, such that tau_s=22.22-radic22.05(t-1.88), where tau_s is the shear strength in MPa and t (>1.88) is the total IMC layer thickness in micrometers. The microstructure of solder appeared to be stable under aging at elevated temperatures up to about 160degC. Above this temperature, brittle and porous IMC epsiv-Cu₃Sn appeared at the copper/eta-Cu₆Sn ₅ interface. Fracture was found to occur at the Cu-Sn IMC layer-solder interface and in the bulk of solder     

Caged ATP-fuel for bionanodevices

Micro- and nanodevices require the controlled delivery of energy to power a variety of processes. The current paradigm of connecting a miniaturized device to a set of macroscopic auxiliary devices, such as power supplies or pumps, for the delivery of electrical and mechanical energy needs to be replaced to enable the design of stand-alone integrated bionanodevices with applications in remote biosensing or nanomedicine. Biological nanomachines, such as the motor protein kinesin, can efficiently convert energy stored in chemical compounds, in particular adenosine 5'-triphosphate (ATP), into mechanical work. This ability is an attractive feature of hybrid devices powered by biomolecular motors, since it removes the need for the storage and conversion of electrical energy. The consequences are a simplified fabrication process and packaging, leading to higher yields and lower costs, and the broadening of the applications, which can now include field-deployable nanodevices. Here, the potential of caged ATP as fuel for such engineering applications is discussed. Caged ATP can be stored in the buffer solution of a bionanodevice, "uncaged" by UV light, and utilized as fuel by many enzymes to catalyze chemical changes or power active transport. We demonstrate that DMNPE-caged ATP can be stored in sufficient amounts in a typical device and that the activation can be triggered with a UV lamp or even sunlight.     

灰色Verhulst模型的样条插值函数的残差修正

本用样条函数对灰色Verhulst模型的残差序列进行插值拟合，然后作用于二阶线性微分方程，并以此修正原模型，得到一种新的预测模型的数值解，提高了拟合的精确度。     

Bulk growth of Hg0.8Cd0.2Te single crystals by a combined CVT-seeding technique

The growth of high quality Hg_0.8Cd_0.2Te bulk single crystals by CVT, combined with an in-situ seeding technique, is reported here for the first time. For this purpose, a temperature difference of 590° → 540° C with a gradient of 40°-50° C/cm at the solid-vapor interface, and about 0.1 atm of HgI₂ as a transport agent, were employed. The bulk crystals have the expected stoichiometry and compositional homogeneity. Etch pit densities of 10⁴-10⁵ cm⁻² on the (111) face and hitherto unreported etch pits on the (100) face were observed in this work. Possible origins of the sub-grain structure are discussed.     

一项从CAA到CAD的工作 ～正交优化法与SPICE相结合

电子电路的计算机辅助设计方法是促进电子技术发展的一种有效工具。本文介绍如何将行之有效的正交优化法与国际盛行的模拟电子电路的分析程序ＳＰＩＣＥ相结合，形成了ＡＣＯＤ软件，将ＣＡＡ扩展为ＣＡＤ。