Al_xGa_(0.51-x)In_(0.49)P光学性质的研究

用MOCVD方法在GaAs衬底上生长了AlGaInP的本征及掺Si或掺Mg三个样品。用椭偏光谱法测量了样品在室温下可见光区的光学常数 ,并求其介电函数的三级微商谱。用三点比例内插法分析介电函数的三级微商谱 ,精确地得到样品的带隙Eg、Eg+Δ0 以及Eg 以上成对结构跃迁的能量位置 ,并对其结果加以分析。同时与沟道分析等方法相结合对材料的性能进行了鉴定。     

A Backside-Illuminated Image Sensor With 200 000 Pixels Operating at 250 000 Frames per Second

In this paper, a high-speed image sensor with very high sensitivity is developed. The high sensitivity is achieved by introduction of backside illumination and charge-carrier multiplication (CCM). The high frame rate is guaranteed by installing the in situ storage image sensor (ISIS) structure on the front side. A test sensor of the BSI-ISIS has been developed and evaluated. It is shown that an image with a very low signal level embedded under the noise floor is recognizable by activating the CCM.     

ACE框架在网络游戏服务器中的设计与应用

由于操作系统及通信平台的多样性,通信软件开发者往往要面对诸多问题,而利用软件设计模式能够帮助开发者成功完成任务并开发出高性能的通信软件。介绍ACE框架在通信领域中的面向对象的设计模式以及使用ACE框架构建通信系统软件所带来的优势,并提出了一种网络服务器架构以及基于模块设计服务器系统软件的思想。最后结合具体应用,详细讲述如何利用ACE中的若干设计模式及组件框架进行网络服务器通信底层模块的设计和实现。     

Electroluminescence and Laser Emission of Soluble Pure Red Fluorescent Molecular Glasses Based on Dithienylbenzothiadiazole

Soluble molecular red emitters 1a / 1b are synthesized by Stille coupling from 2‐(3,5‐di(1‐naphthyl)phenyl)thiophene precursors. The compounds show emission maxima at ca. 610 nm in CH₂Cl₂ solution and 620 nm in solid films. Replacing the n‐hexyl substituent by 4‐sec‐butoxyphenyl produces a marked increase of glass transition temperature (T_g) from 82 °C to 137 °C and increases the solubility in toluene and p‐xylene, thus improving the film‐forming properties. Cyclic voltammetry shows that the compounds can be reversibly oxidized and reduced around +1.10 and ?1.20 V, respectively. A two‐layered electroluminescent device based on 1b produces a pure red light emission with CIE coordinates (0.646, 0.350) and a maximal luminous efficiency of 2.1 cd A^?1. Furthermore, when used as a solution‐processed red emitter in optically pumped laser devices, compound 1b successfully produces a lasing emission at ca. 650 nm.     

A Coded Modulation Scheme for Deep-Space Optical Communications

A coded modulation scheme for deep-space optical communications is studied, which is a serial concatenation of an outer low-density parity-check (LDPC) code, an interleaver, a bit-accumulator, and pulse-position modulation (PPM). It is referred as LDPC-APPM. It is decoded with an iterative demodulator-decoder using standard turbo-decoding techniques. Simulation results show that the LDPC-APPM with an outer LDPC code of medium code length suffers a loss of about 0.7 dB at a bit-error rate of relative to the serially concatenated PPM (SCPPM) of similar parameters, which consists of the serial concatenation of an outer convolutional code, an interleaver, a bit-accumulator, and PPM; however, it has better code rate flexibility especially for high rates and simpler implementation structure than SCPPM. Further, it can achieve better performance than the LDPC-PPM of the same rate and length, which consists of the serial concatenation of an LDPC code and PPM.     

Reliable broadcasting in wormhole-routed hypercube-connected networks using local safety information

This paper presents a method to cope with reliable broadcasting in faulty hypercubes using local safety information. A new definition, broadcast subcube, is introduced, with which various techniques are proposed to improve performance of the broadcast algorithm. Local safety information is well used in the fault-tolerant broadcast algorithm by considering only safety of the broadcast subcube. An unsafe hypercube can be split into a set of maximal safe subcubes. If these maximal safe subcubes meet certain requirements (listed in this paper), then broadcasting can still be done successfully and, in some cases, optimal broadcast is still possible. The sufficient condition for optimal broadcast of a message is presented in an unsafe hypercube. Extensive simulation results show that the proposed method outperforms previous methods, in all cases.     

半导体激光对蝗虫与其寄主植物组织热效应的分析比较

为比较半导体激光对蝗虫与其寄主植物组织的生物热效应差异,为激光杀灭蝗虫提供理论依据.选取808nm连续激光对东亚飞蝗幼虫与营养期狗尾草植物进行辐照效应理论研究,建立了激光照射下生物组织热作用的二维数学模型,采用Matlab有限元数值分析方法求解了Pennes生物传热方程,得到了组织内部温度随激光辐照时间和组织空间位置的分布规律.数值分析结果表明,对于蝗虫与植物组织,温度分布有着同样的规律,但温度沿着径向比轴向扩散范围广.在相同的激光辐照条件下,植物组织的温升不明显,保持在初始温度水平;蝗虫组织的温升则远远高于植物组织.     

Improved Hydrogen Capping Effect in n-Type Crystalline Silicon Solar Cells by SiN(Si-Rich)/SiN(N-Rich) Stacked Passivation

The effect of hydrogen capping of SiN(Si-rich)/SiN(N-rich) stacks for n-type c-Si solar cells was investigated. Use of a passivation layer consisting of Si-rich SiN with a refractive index (n) of 2.7 and N-rich SiN with a refractive index of 2.1 improved the thermal stability. A single SiN passivation layer with a refractive index of 2.05 resulted in an initial lifetime of 200 μs whereas the layer with a refractive index of 2.7 resulted in a high initial lifetime of 2 ms, but the layer degraded rapidly after firing. A stacked passivation layer with refractive indices of 2.1 and 2.7 had a stable lifetime of 1.5 ms with an implied open-circuit voltage (iV _oc) of 720 mV after firing. The thermally stable passivation mechanism with changing amounts of Si–N and Si–H bonding was analyzed by Fourier-transform infrared (FTIR) spectroscopy. Incorporation of the SiN _x stack layer (2.7 + 2.1) into the passivated rear of n-type Cz silicon screen-printed solar cells resulted in energy conversion efficiency of 19.69%. Improved internal quantum efficiency in the long-wavelength range above 900 nm, with V _oc of 630 mV, is mainly because of superior passivation of the rear surface compared with conventional solar cells.     

iPTT: peer‐to‐peer push‐to‐talk for VoIP

This paper proposes iPTT, a peer‐to‐peer (P2P) Push‐to‐Talk (PTT) service for Voice over IP (VoIP). In iPTT, a distributed and mobile‐operator independent network architecture is presented to accelerate the deployment of the PTT service. Based on the serverless architecture, we develop two mechanisms, that is, flooding‐based floor control mechanism (FFC) and tree‐based floor control mechanism (TFC), for real‐time talk‐burst determination. The determination algorithms and the corresponding message flows for these two mechanisms are designed to show the feasibility of FFC and TFC. The performance of FFC and TFC is investigated through our analytical and simulation models in terms of the determination latency and the number of floor‐control message exchanges. Copyright © 2008 John Wiley & Sons, Ltd.     

物联网在国土资源管理中的研究与应用

随着信息技术的不断发展,物联网逐渐成为各行各业实现智慧管理的重要手段之一.以物联网概念以及国土资源管理的内容为基础,深入分析了物联网技术在国土资源管理领域的应用方法和重要内容,给出了智慧国土信息决策平台的总体设计思路、体系架构和建设内容,旨在为智慧国土的发展提供方向,提升国土资源科学化管理水平与监管效能.