非编码MPSK-OFDM系统判决指导的相位估计研究

本文论及非编码MPSK-OFDM系统载波跟踪中的重要部件?判决指导的相位估计器(PED)的研究.多载波系统的相位估计可以表示为各子载波相位估计的加权和.文中在分析单载波的基础上考察了符号判决错误对多载波相位估计的影响,并提出了两种改进方案,一是给出一组新的加权系数,改善了PED在较低信噪比的性能;二是由导频子载波相位估计指导其它数据子载波相位估计,获得了(-(/)M (/)M)区间上的线性无偏估计器.文中对两种改进算法进行了分析比较和仿真验证.     

Reduction of optical beat interference using gain-saturated RSOA in upstream WDM/SCM optical links

A new scheme for reducing optical beat interference (OBI) noise in optical network units is proposed for subcarrier multiplexing-based access network applications. The optical spectrum of the transmit lasers is broadened by using a radio frequency (RF) clipping tone with a modulation depth greater than one. This reduces the impact of the OBI noise. The distortions caused by an RF clipping tone are also suppressed by introducing a gain-saturated reflective optical amplifier, which shows the characteristics of high-pass filter. The proposed scheme has been verified by measuring the error vector magnitude of 16QAM signal with 20 Mbps. Error-free transmission has been achieved even when the light of OBI-noise-causing lasers is stronger than that of the signal laser by 7 dB     

聚丙烯纤维混凝土在泰州市联通大厦地下室墙板工程中的应用

本文主要介绍聚丙烯纤维混凝土在泰州市联通大厦地下室墙板工程中实际应用的一些情况,从原材料的选择、配合比的确定到现场混凝土的浇注以及最终结果进行了阐述,供工程施工参考。     

试论普通高校成人高等教育的地位和现状

文章首先分析成人高等教育在构建终身教育体系中的地位和作用,指出成人高等教育是我国高等教育的重要组成部分,在实现大众化教育过程中起着重要且不可或缺的作用.然后,结合我国入世后全面参与全球化的大背景,在向市场经济转轨,经济和社会实现跨越式发展的关键时期,在普通高校不断扩招的形势下,论述我国成人高等教育的发展所面临的一系列挑战.     

Cu—Zn—Al系合金热弹性马氏体相变的热滞

本文通过热处理工艺及添加第四组元研究了Cu－Zn－Al系记忆合金的相变热滞。结果表明，淬火冷却速度影响合金的相变热滞大小，随着母相时效时间的延长，马氏体相变热滞变大．Mn元素的加入可以减小CU－Zn－Al合金相变热滞．     

Hydrogen Permeation and Diffusion in Amorphous Alloy Ni_(68)Cr7_Si_8B_(14)Fe_3 at Elevated Temperature

The behaviour of hydrogen permeation and diffusion in amorphous alloy Ni68Cr7Si8B14Fe3 hasbeen investigated by an ultrahigh vacuum gas permeation technique. A comparison experimentwas carried out between the as-quenched and annealed States (400℃/2h) of the amorphousalloy. The results show that, for both states of the amorphous alloy in the temperature rangeof 200～350℃, the diffusivity and permeability of hydrogen are in agreement with Arrheniusrelationship, there does not exist H-trapping effect, and the activation energies of diffusion andpermeation almost keep the same.     

屏蔽暂堵反排解堵效率的实验分析

在一定实验条件下，屏蔽暂堵的反排解堵效率随压差、温度的增大而增大，反排解堵在很短的时间内就可完成。一般的反排解堵率都在60％以上，但反徘不能完全解堵。     

Structure and Properties of Electroless Ni Deposits

The changes in structure and the hardness of two electroless deposited Ni-P alloy coatings (with P content of 1.5 and 9.5 wt pct) with heat treatment have been studied by XRD and TEM. The deposits containing 1.5 wt pct P can be represented as an fcc NiP supersaturated solid solution of 5~10 nm microcrystallites. whereas the deposits containing 9.5 wt pct P are amorphous. The heat treatment process induces crystallization of amorphous Ni to Ni phosphides and fcc Ni.Both of the deposits reach maximum hardness after annealing at 400℃ for 1 h. All coated steel specimens are inferior in fatigue strength to uncoated steel specimens mainly due to the poor fatigue resistance of the coating itself     

Viterbi译码器的硬件实现

介绍了一种Vkerbi译码器的硬件实现方法。设计的基于硬判决的Viterbi译码器具有约束长度长（9)、译码深度深（64)的特点。为了兼顾硬件资源与电路性能两个方面，在设计中使用了4个ACS单元，并根据Xilinx Virtex系列FPGA的结构特点．利用FPGA内部的BlockRAM保存汉明距离和幸存路径，提高了译码速度。     

Interdiffusion behavior of Hg in HgTe/CdTe superlattices grown on Cd0.96Zn0.04 Te (211)B substrates by molecular beam epitaxy

Double-crystal x-ray rocking curve (DCRC) and secondary-ion mass-spectroscopy (SIMS) measurements have been performed to investigate the effect of rapid thermal annealing on the interdiffusion behavior of Hg in HgTe/CdTe superlattices grown on Cd_0.96Zn_0.04Te (211)B substrates by molecular beam epitaxy. The sharp satellite peaks of the DCRC measurements on a 100-period HgTe/CdTe (100Å/100Å) superlattice show a periodic arrangement of the superlattice with high-quality interfaces. The negative direction of the entropy change obtained from the diffusion coefficients as a function of the reciprocal of the temperature after RTA indicates that the Hg diffusion for the annealed HgTe/CdTe superlattice is caused by an interstitial mechanism. The Cd and the Hg concentration profiles near the annealed HgTe/CdTe superlattice interfaces, as measured by SIMS, show a nonlinear behavior for Hg, originating from the interstitial diffusion mechanism of the Hg composition. These results indicate that a nonlinear interdiffusion behavior is dominant for HgTe/CdTe superlattices annealed at 190°C and that the rectangular shape of HgTe/CdTe superlattices may change to a parabolic shape because of the intermixing of Hg and Cd due to the thermal treatment.