超低密度早强水泥浆在天然气井固井中的应用

在天然气井固井中,上部固井质量一直存在问题。为了提高固井质量,达到保护套管的目的,研制了新型水泥浆体系。经室内研究,选择了减轻剂的种类与粒级配比;根据低密度水泥浆的性能要求,确定了配方,并对该配方进行了触变防漏特性及稳定性分析,形成了具有体系稳定、水泥浆密度波动对水泥浆体系产生影响较小、抗漏失能力强、早期强度发展快等特点的超低密度水泥浆体系。经现场试验,获得了较好的效果。     

高速遥传系统配接DTB总线仪器的接口设计

FPGA（field programmable gate array）技术已经成为当今实现电子线路集成化的重要方法之一。通过应用PFGA和单片机技术，设计一种接口电路，用于将CSU和SKC数控系统中DTB总线的井下仪器挂接到高速 遥传系统上，从而大大提高高速电缆遥传系统的兼容性，使其应用范围更广，市场前景更好。     

Iterative receivers for space-time block-coded OFDM systems indispersive fading channels

We consider the design of iterative receivers for space-time block-coded orthogonal frequency-division multiplexing (STBC-OFDM) systems in unknown wireless dispersive fading channels, with or without outer channel coding. First, we propose a maximum-likelihood (ML) receiver for STBC-OFDM systems based on the expectation-maximization (EM) algorithm. By assuming that the fading processes remain constant over the duration of one STBC code word and by exploiting the orthogonality property of the STBC as well as the OFDM modulation, we show that the EM-based receiver has a very low computational complexity and that the initialization of the EM receiver is based on the linear minimum mean square error (MMSE) channel estimate for both the pilot and the data transmission. Since the actual fading processes may vary within one STBC code word, we also analyze the effect of a modeling mismatch on the receiver performance and show both analytically and through simulations that the performance degradation due to such a mismatch is negligible for practical Doppler frequencies. We further propose a turbo receiver based on the maximum a posteriori-EM algorithm for STBC-OFDM systems with outer channel coding. Compared with the previous noniterative receiver employing a decision-directed linear channel estimator, the iterative receivers proposed here significantly improve the receiver performance and can approach the ML performance in typical wireless channels with very fast fading, at a reasonable computational complexity well suited for real-time implementations     

我国核工业废放射源安全管理

废放射源易于在管理上失去控制，从而酿成事故，对人类和环境造成危害。本文分析了我国废放射源产生的原因，介绍了我国核工业废放射源的现状与安全管理的技术路线和策略，提出了当前所面临的主要问题。     

欢喜岭SBS改性沥青的性能

采用适当的生产工艺，选择不同牌号的欢喜岭重交通道路沥青对几种SBS改性剂的配伍性进行考察，从中优选出配伍性好的改性剂，生产两种类型的改性沥青，一种是基于现场改性不添加稳定剂的改性沥青；另一和中是稳定性较好能长期储存的改性沥青。两种改性沥青经使用性能评定具有优良的使用性能。     

一种确定高窄带滤光片峰值波长的方法

本文介绍一种主动式高窄带滤光片峰值波长的测量方法。该方法可以有效的测量出窄带滤光片的敏感波长，而不需要太复杂的设备。通过染料激光谐振腔的模式竞争，可以测量出滤光片的透射或反射波的波长。     

喷墨打印机的使用与维护

介绍使用喷墨打印机应注意的事项，探讨打印机墨水消耗过快的问题。     

应用实时全息术和散斑照相术测量岩石的弹性参数

本文介绍用激光实时全息术测量岩石的泊松比μ,用散斑照相放大术测量岩石的杨氏模量E,进而由弹性理论中的关系式G=E/(2(1+μ))算出岩石的切变模量G。由此可以获得所测岩石的弹性参数。     

填充料细度对水工沥青混凝土性能的影响

近年来沥青混凝土作为防渗材料，在我国水工建筑中得到了广泛应用。与道路工程的沥青混凝土不同的是，水工沥青混凝土具有良好的粘弹性及抗渗性。目前，国家规范对填充料的细度尚无明确规定，通过调整沥青混凝土的填充料细工，对沥青混凝土的各项性能进行了系统的试验和分析，研究表明：适宜的填充料细度及掺量，能有效地改善沥青混凝土性能，提高其抗渗性。