电磁波在吸波涂层中的干涉现象

文摘为研究电磁波在吸波涂层中的干涉现象,选取了X型羰基铁粉吸收剂,采用同轴法测试了材料电磁参数,通过多次反射方法求解了X型吸波涂层在厚度为1/4波长时反射系数公式;另外,求解了不同厚度X-1型吸波涂层对频率为9.5 GHz平面电磁波反射系数公式,取公式前6项计算了反射系数Γ_a和反射率R_a。结果表明,多次反射波之间产生了干涉行为,发生了干涉相消现象。Γ_a、R_a分别与传输线方法计算的Γ和R的值非常接近,表明Γ_a和R_a可以近似代表X-1型吸波涂层对9.5 GHz电磁波的反射系数和反射率。当X-1型吸波涂层厚度小于1.9 mm或在3.2～6.6 mm时,第二反射波对第一反射波起到干涉相长作用,降低吸波性能,表明优选的吸波涂层厚度应该介于1.9～3.2 mm。     

机场终端区跑道配置优化及容流调配模型研究

大型繁忙机场交通需求的持续增长导致的飞行流量与保障能力、机场容量之间的矛盾日益突出。为了充分利用跑道系统资源,合理配置跑道运行容量,优化飞行流,建立非线性0-1整数规划模型解决以下两个问题:确定跑道配置优化序列,匹配进离场飞机流。模型综合考虑机场交通流、跑道配置转换容量折损、跑道容量包络线等约束,以优化区间内航班总延误最小为目标,用LINGO建模求解,使用实际运行数据验证模型的有效性。结果表明,模型实现了跑道资源的优化利用,降低了航班延误。     

改性羰基铁粉/ 硅橡胶材料的制备及其力学性能

以微米级改性羰基铁粉为填充剂,甲基乙烯基硅橡胶为基体,制备了高温硫化的羰基铁粉/硅橡胶复合材料.研究了偶联剂种类、用量及羰基铁粉填充量对复合材料力学性能的影响,利用扫描电镜对硫化胶断面的微观结构进行了观察.结果表明,采用硅烷偶联剂KH570、KH151改性羰基铁粉都能提高复合材料的拉伸强度,其中KH151的改性效果要优于KH570;KH151的最佳用量为羰基铁粉质量的1%;在一定范围内随着改性羰基铁粉体积分数的增加,复合材料的拉伸强度增大.羰基铁粉体积分数超过60%后,混炼困难.     

型内球化法成形球铁件中微细夹杂物的分析研究

通过对型内球化成形件的细微夹杂物分析，利用扫描电镜、能谱仪等检测手段，研究了夹杂物形态、成分和对球铁件机械性能的影响。     

高耐蚀锌铁合金电沉积研究

利用电沉积的方法获取含Fe0.4％～0.8％的锌铁耐蚀合金镀层。结果表明:工艺因素对镀层含Fe量影响很大。而镀层中的含Fe量又直接影响镀层的耐蚀性。含Fe0.4％～0.8％的锌铁合金镀层其耐蚀性大大优于普通镀锌层。少量的铁元素可以大大延迟镀层出白锈、出红锈的时间。     

蜂窝平板太阳能集热器研制及闷晒性能实验

研制了一种含有透明绝热结构的太阳能蜂窝平板集热器，从理论上分析了集热器吸热板与蜂窝板间有空气隙的复合蜂窝结构的表面传热损失，并对闷晒实验作了描述和总结。实验发现：蜂窝结构大大提高了集热器吸热板的闷晒平衡温度；理论分析也指出：蜂窝结构显著降低了集热器的表面热损失系数。因此，采用透明绝热蜂窝结构是提高太阳能集热器集热效率的一种有效方法。     

Production of high fidelity lunar agglutinate simulant

As space faring nations consider manned and unmanned missions to the Moon, there is a growing need to develop high fidelity lunar regolith simulants that can accurately reproduce the properties and behavior of lunar regolith. Such simulants will be employed to verify the performance of equipment, mechanisms, structures and processes to be used on the lunar surface. One of the significant limitations of current terrestrial-based simulants, such as the popular mare simulant, JSC-1A, is the lack of agglutinates. This paper investigates the production of a lunar mare agglutinate simulant based on JSC-1A. A modified plasma processing technique was used to expose the JSC-1A regolith simulant to high temperatures and transform it to predominantly a glassy phase. Detailed characterization results are presented to confirm that the agglutinate simulant material produced during this investigation reasonably satisfies the primary requirements of an agglutinate simulant such as amorphous/crystalline content, particle size, morphology, vesicular structure, chemistry, and presence of nanophase elemental Fe.     

缓蚀剂在工业纯铁/盐酸体系中缓蚀能力的快速评价方法

研究了聚丙烯酸（ＰＡＡＣ）、苯扎溴铵（ＤＢＤＡＢ）在工业纯铁／盐酸体系中的缓蚀性能,推导了一种既能快速测出腐蚀缓蚀剂的缓蚀效率又能确定腐蚀缓蚀剂类型的新方法,定义了能够确定腐蚀缓蚀剂类型因子Ｐ。研究结果表明,Ｐ〉１．００的缓蚀剂为阳极型的缓蚀剂,Ｐ〈１．００的缓蚀剂为阴极型缓蚀剂。     

一种新的烧蚀热响应算法在质量估算中的应用

针对预测飞行器再入过程中气动热流引发的烧蚀热响应导致热防护罩表层材料质量损耗的问题,研究了热防护罩的几何模型和烧蚀质量估算的方法,通过建立三自由度再入轨迹动力学方程,应用修正的牛顿流体理论计算气动系数,以及Detra-Kemp-Riddell和Tauber-Sutton理论计算驻点热流密度和热辐射,利用一维非线性热传导方程模拟了碳化材料的烧蚀过程,提出了基于Newton-Raphson和TDMA的烧蚀热响应算法估计飞行器热防护罩质量损耗的方法。通过分析,实现了再入全过程热防护材料烧蚀深度连续动态变化的预测,能够有效替代热平衡积分法,估算的烧蚀质量为优化热防护罩的几何模型和再入轨迹提供了参考依据。     

Elliptical vibration cutting of large-size thin-walled curved surface parts of pure iron by using diamond tool with active cutting edge shift

Large-size thin-walled curved surface parts of pure iron are crucial in aerospace, national defense, energy and precision physical experiments. However, the high machining accuracy and surface quality are difficult to achieve due to the serious tool wear and deformation when machining the parts with conventional cutting tools. In this paper, an elliptical vibration cutting (EVC) with active cutting edge shift (ACES) based on a long arbor vibration device is proposed for ultra-precision machining the pure iron parts by using diamond tool. Compared with cutting at a fixed cutting edge, the influence of ACES on the EVC was analyzed. Experiments in EVC of pure iron with ACES were conducted. The evolutions of the surface roughness, surface topography, and chip morphology with tool wear in EVC with ACES are revealed. The reasonable parameters of ultra-precision machining the pure iron parts by EVC with ACES were determined. It shows that the ACES has a slight influence on the machined surface roughness and surface topography. The diamond tool life can be significantly prolonged in EVC of pure iron with ACES than that with a fixed cutting edge, so that high profile accuracy and surface quality could be obtained even at higher nominal cutting speed. A typical thin-walled curved surface pure iron part with diameter ∅240 mm, height 122 mm, and wall thickness 2 mm was fabricated by the presented method, and its profile error and surface roughness achieved PV 2.2 μm and Ra less than 50 nm, respectively.