Compact SOI arrayed waveguide grating demultiplexer with broad spectral response

A compact eight-channel flat spectral response arrayed waveguide grating (AWG) multiplexer based on siliconon-insulator (SOI) materials has been fabricated on the planar lightwave circuit (PLC). The 1-dB bandwidth of 48 GHz and 3-dB bandwidth of 69 GHz are obtained for the 100 GHz channel spacing. Not only non-adjacent crosstalk but also adjacent crosstalk are less than -25 dB. The on-chip propagation loss range is from 3.5 to 3.9 dB, and the 2 total device size is 1.5 x 1.0 cm(2). (c) 2005 Elsevier B.V. All rights reserved.

Energy band and acceptor binding energy of GaN and AlxGa1-xN

The hole effective-mass Hamiltonian for the semiconductors of wurtzite structure is established, and the effective-mass parameters of GaN and AlxGa1-xN are given. Besides the asymmetry in the z and x, y directions, the linear term of the momentum operator in the Hamiltonian is essential in determining the valence band structure, which is different from that of the zinc-blende structure. The binding energies of acceptor states are calculated by solving strictly the effective-mass equations. The binding energies of donor and acceptor for wurtzite GaN are 20 and 131, 97 meV, respectively, which are inconsistent with the recent experimental results. It is proposed that there are two kinds of acceptors in wurtzite GaN. One kind is the general acceptor such as C, substituting N, which satisfies the effective-mass theory, and the other includes Mg, Zn, Cd etc., the binding energy of which deviates from that given by the effective-mass theory. Experimentally, wurtzite GaN was grown by the MBE method, and the PL spectra were measured. Three main peaks are assigned to the DA transitions from the two kinds of acceptor. Some of the transitions were identified as coming from the cubic phase of GaN, which appears randomly within the predominantly hexagonal material. The binding energy of acceptor in ALN is about 239, 158 meV, that in AlxGa1-xN alloys (x approximate to 0.2) is 147, 111 meV, close to that in GaN. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

Photoluminescence mechanism of Si nanocrystals embedded in SiO2 matrix

The interface state recombination effect from the quantum confinement effect in PL signals from the SRO material system was studied. The results show that the larger the size of Si NCs, the more beneficial for the interface state recombination process to surpass the quantum confinement process, in support of Qin's model.

Study on text-dependent speaker recognition based on Biomimetic Pattern Recognition

We studied the application of Biomimetic Pattern Recognition to speaker recognition. A speaker recognition neural network using network matching degree as criterion is proposed. It has been used in the system of text-dependent speaker recognition. Experimental results show that good effect could be obtained even with lesser samples. Furthermore, the misrecognition caused by untrained speakers occurring in testing could be controlled effectively. In addition, the basic idea "cognition" of Biomimetic Pattern Recognition results in no requirement of retraining the old system for enrolling new speakers.

an intuitive formal proof for deadline driven scheduler

United Nations University, Int. Inst. for Softw. Technol., China; Vietnam National University, Hanoi, Vietnam; Vietnam Academy of Science and Technology, Vietnam

基于可用性架构的嵌入式关键任务操作系统设计

可用性技术是提高计算机系统在发生故障情况下持续运转能力的有效手段。操作系统作为计算机的管理者，其可用性是整个系统的核心。运行在复杂环境中的嵌入式系统对可靠性、实时性以及系统持续运行能力有很高的要求。在操作系统中提供可用性服务是提高系统生存能力的一个重要研究领域。 针对目标硬件构架，本文提出了所需具备的支撑技术，并说明了各部分之间的联系。这些技术包括：内核可靠性技术、心跳技术、热插拔技术、系统组件动态更新技术以及负载均衡技术。内核可靠性技术为操作系统内核增加可靠性功能，同时保证系统的实时性，可靠的内核是高可用系统的基础；心跳技术监测整个系统的运行情况，避免系统发生单点失效的问题；热插拔技术和系统组件动态更新技术允许在运行时动态更新系统软件和硬件，降低平均恢复时间；负载均衡动态调配系统中任务，提高系统整体性能。在这些技术中，内核可靠性和心跳技术是其他部分的基础，也本文的研究重点。 最后，针对不同问题设计了多种测试用例。测试结果说明本文的设计与实现的有效性。

基于OpenType的复杂文本语言处理的研究与实现

某些书写系统的文字(如蒙古文、维文、藏文等)具有比拉丁文字复杂的特性,当计算机在处理这类文字时,运用传统的字体技术(如TrueType)几乎不可能在显现出规范的书写形式的同时,实现对Unicode标准编码的支持.就这个问题介绍一种基于OpenType字体的处理模型.事实证明,这是一种可行的方案.

手持移动设备中多通道交互的通用开发框架

提出的多通道交互通用开发框架可以快速地开发出支持多通道交互的应用,也可以将已经存在的应用快速更改为多通道交互应用;基于此理论,设计和实现了一种支持手写笔和语音输入的多通道家电开关控制系统。具体地阐明了实际开发中应该重点注意的环节,希望能够对当前手持移动设备的多通道交互化有所借鉴。