基于双波长技术的有线电视补偿系统的研究

色散和自相位效应是制约1550 nm有线电视(CATV)系统无中继传输距离的主要因素。针对传统补偿方法在模拟CATV系统应用上的缺点,提出了双波长波出复用(WDM)技术,通过合理的频道划分,实现对色散和自相位的有效补偿。     

基于槽波透射法CT成像的工作面煤厚预测

槽波勘探法是探测煤矿井下工作面中煤层结构和其他异常体的一种有效井下勘探方法。本文回顾了槽波勘探法的发展历史、形成原理,介绍了槽波透射法。根据槽波在煤层中的传播规律和特点,重点研究了煤厚对槽波的影响。在理论基础上,利用槽波地震勘探技术对黄陵一号煤矿1001工作面进行了透射法进行探测。     

Characterization of wall dispersive and attenuative effects on UWB radar signals

This paper addresses the potentials of ultra-wideband (UWB) through-wall imaging radars compared with conventional narrowband systems. The challenges that limit the utilization of high precision UWB systems are examined with the aim of mitigating them. These challenges include multi-path, pulse dispersion, and antenna effects on the pulse shape due to angles of transmission and arrival. The propagation of UWB signals through walls is a crucial factor in determining the success of UWB radar technology. UWB signals, when propagating through walls, not only suffer attenuation but also distortion due to dispersive properties of the walls. This paper examines time- and frequency-domain techniques for measuring the electromagnetic properties of construction materials in the UWB frequency range. The measured parameters provide valuable insights in appreciating the capabilities and limitations of the UWB technology. Special attention is paid to time gating as a mean to extract the direct-path signal from the multi-path components. Both single-pass and multi-pass models are discussed. Multi-pass models account for the multiple reflections within the wall while the single-pass model assumes the possibility of gating out a single transmission. The partition-dependent narrowband propagation model is modified to account for the ultra-wide bandwidth of the signal. The paper illustrates the application of the modified model in indoor environments. The modified model is helpful in estimating the link power budget. It is also useful in studying the performance of UWB systems for indoor communication and positioning applications.     

一种简单的交通疏导算法

本文提出了一种简单的交通疏导算法,可以动态调整交通网络中的车流量,还可以得到两个或两个以上的交通疏导方案。本算法具有容易理解、形式规范的特点,无论用于教学还是解决实际问题,都有较大的实用价值。     

用正电子寿命谱研究氧化镍在Al2O3上的分散

用正电子湮没谱研究了用浸渍法制备的Al2O3担载NiO催化剂在不同烘烤温度、不同烘烤时间下NiO的分散情况。结果显示:在300℃左右烘烤2小时,NiO的分散情况最理想。     

基于GPS数据的电离层模型和电离层延迟改正新方法研究(英)

根据大地测量、地球物理、空间物理和导航等领域的若干重要GPS科研项目的需要,系统研究了电离层延迟的高精度模拟和改正方法。报告的内容主要涉及GPS系统的电离层延迟的高精度改正,如何通过修正静、动态单、双频用户的电离层延迟影响,进一步改善GPS测量的精度和可靠性,改进增强型GPS广域差分系统的电离层模拟及利用GPS监测电离层的理论和方法等。     

An open task to promote students to create statistical concepts through modelling

This article reports on the solutions of a group of 22 students, aged 15/16 years old, when facing a statistical modelling activity. They were given the salary lists of 5 companies and were asked what could be said about their salary structure; no hint was given. The results show that students not only used a wide range of data concepts and procedures but also developed their own criteria to measure dispersion.     

多道瞬态瑞雷面波在工程勘察中的应用

在面波勘探中,随着软件和硬件的发展及面波勘探技术理论的进一步完善,瞬态瑞雷波法越来越引起人们的重视.由于面波勘探与常规的地震勘探相比具有现场场地要求不高、快速经济、易于激发和识别、有效信号能量强、不受各地层速度的影响、对浅部地层分辨率高等特点,使得面波勘探技术被广泛地应用于探查地下介质结构并进行地层划分、海堤中软弱夹层的探测、天然地基剪切波速度测试、判定场地类别和评估软弱地基处理等无损检测工程领域中.本文叙述了瑞雷面波的勘探原理以及资料整理解释方法,并通过应用实例说明其在工程中的应用效果.     

十运会对苏北城市群众体育开展的影响研究

运用文献资料法、问卷调查法等方法,研究第十届全运会的顺利召开对江苏北部城市群众体育开展产生的影响。结果发现:十运会对苏北地区的群众体育开展起到到了积极带动作用。产生这种现象的主要原因有全运会分散办赛模式、省专业队市管等。提出充分开发十运会比赛场馆为群众体育服务等建议。     

Influence of water saturation on propagation of elastic waves in transversely isotropic nearly saturated soil

INTRODUCTIONIthaslongbeenrecognizedthatcompression alwavespropagationinsaturatedsoilsisstronglyaffectedbythewaterfillingtheintersticesofthesoilgrains.HardinandRichart(1 963 )appliedthetwo phasetheoryofBiot(1 956)andstudiedtheinfluenceoftheconfiningpressur…