减少波束指向抖动的捷变频方法

采用裂缝波导阵列天线的雷达在频率捷变时将引起雷达波束指向的抖动，严重时抖动可超出波束宽度范围，影响目标检测，甚至造成目标丢失。本文对此进行了分析，提出了解决方法，并简述为此而设计的一种小型、实用的频率捷变系统。     

优质氧化沥青及其油毡的老化研究

优质氧化沥青及其油毡的老化研究吴少鹏（武汉工业大学）中图分类号ＴＥ６２６．８１导言沥青在贮运、加工、施工及使用过程中，由于长时间地暴露在空气中，在风雨、温度变化等自然条件的作用下，会发生一系列的物理及化学变化，如蒸发、脱氢、缩合、氧化等等。此时，沥青...     

Effect of fiber types on relevant properties of porous asphalt

The research was conducted to evaluate the effects of cellulose and polyester fibers on the properties of porous asphalt mixes, using the tests of draindown, abrasion, volumetric properties, rutting, and moisture damage. Images of scanning electron microscopy and X-ray computerized tomography were adopted to identify the microstructure of the fiber and inner stone skeleton of porous asphalt. The influence of rutting parameter （G＊/sin δ） of asphalt modified by different fibers on the rutting resistance of the mixes was investigated. Based upon MOHR-COULOMB theory, the cohesion and the angle of internal friction of the mixes were derived from both indirect tension and unconfined compression strength. The experimental results indicate that fibers mainly stabilize asphalt binder and thicken asphalt film around aggregates. Furthermore, they result in the improved mechanical strength of porous asphalt mixes at high temperature slightly. From comparison analysis, cellulose fibers appear to perform better than polyester fibers in porous asphalt mixes.     

Effect of ageing on fatigue properties of asphalt

The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing,by dynamic shear rheometer(DSR) time sweep fatigue test in constant strain model and a new type of specimen which was introduced to avoid the problem of adhesion failure between rotor and asphalt binder.The results show that outdoor natural exposure ageing(NEA) causes the decrease of retained fatigue life distinctly,and photodegradation caused by outdoor NEA of 1 250 μm thin films asphalt for three months,is found to be severer than pressure ageing vessel(PAV) with respects to retained fatigue life.The effect of photodegradation increases as the time of outdoor NEA increases.DSR time sweep fatigue test in constant strain indicates that the aged styrene-butadiene-styrene(SBS) modified asphalt still displays better fatigue properties than the corresponding base asphalt after ageing.     

Investigation of rheological properties of TPS modified bitumen

Rheological properties of the virgin bitumen and TPS modified bitumen binders with several percentages of TPS additives were studied.All TPS modified bituminous binders were prepared on a laboratory scale.Dynamic shear rheometer(DSR) strain sweep test was made to measure the linear viscoelasticity areas of various bitumen binders at -20-70 ℃,then temperature sweep test and frequency sweep test were made in the linear viscoelasticity areas.Complex modulus master curves were drawn to analyze and compare various bitumen binders’ rheological properties.Based on the test results,the ideal percentage of TPS additive was brought forward.The results show that TPS modified bitumen binders have more excellent properties at high,medium and low temperatures compared with original bitumen.The dosages of TPS additive are vital to their properties.     

湿塑性水泥土增强研究

从水泥在水泥-水-粘土系统中水化的特点出发，阐述了湿塑性水泥土的强度形成过程，主要是依赖于水泥石的强度骨架与粘土之间的结构连接。通过实验，研究了几种外加剂对湿塑性水泥土的增强作用及其增强机理，结果表明，外加剂能改善水泥土的水化介质环境和结构粘接，可改善水泥土的稠度和强度。     

4.75mm最大公称粒径沥青马蹄脂碎石混合料

由于在预防性维护项目中有很好的前景 ,4 .75 mm最大公称粒径 (NMAS)热拌沥青混合料在高速公路的工程中越来越受欢迎。基于试验结果与分析 ,可成功的设计出粉尘含量小于 12 %的级配的 4 .75 m m NMAS的 SMA混合料 ,而且只要满足其它各方面的要求 ,可以用 0 .0 75 mm筛的通过率为 9%的级配。用 2 .36 mm网孔的金属网篮进行的析漏试验结果比用 6 .3mm网孔的金属网篮的析漏结果要小。集料通过不同的网孔掉出的量的不同造成了用两种网篮的析漏的试验结果不同     

废食用油用于沥青再生的应用前景分析

我国废食用油已成为环境污染物,并冲击食品安全,如近年来地沟油事件频发,严重危害着人们身心健康。废食用油中含有大量不饱和脂肪酸,类似于沥青中的油分,而沥青老化后其油分会减少。根据沥青再生理论与相关研究,废食用油可作为低粘度油分用于沥青再生,有望通过以废治废的方式,实现废食用油与废旧沥青路面材料的同时利用,有利于环境保护,具有广阔的应用前景。为了实现废食用油在沥青再生领域的应用,应该重点开展废食用油的分类与处理技术、废食用油对老化沥青的再生效果、再生机理以及应用技术等方面的研究。     

海工混凝土防护用有机硅防水剂的研究

有机硅防水剂用于海工混凝土防护,可提高其耐久性。本文介绍了有机硅防水剂的结构、组成及性能,重点研究了该材料与混凝土的粘结性及其对混凝土抗渗性的影响,探讨了有机硅防水剂的防水作用机理,并总结了该材料在海工混凝土防护中的施工工艺及注意事项。     

基于域层化的雷达指标体系结构及规范方法探讨

针对雷达指标体系现状和现代战争中雷达实际使用效能需求,提出了适应未来战场复杂条件的雷达多域分层指标结构,并探讨了指标体系规范与确定的方法途径,以期能够客观地反映雷达的先进性、针对性、有效性和实际可用性能,促进雷达装备的开发、研制和应用效能的提高。本文研究内容可为进一步深入研究和细化各类雷达的具体指标,以及为雷达实际效能的评估与验证可提供技术支撑。