利用单缝衍射测金属材料的线膨胀系数

根据单缝衍射原理,利用CCD数据采集系统来测量金属体随温度升高的伸长量,给出测量金属线膨胀系数的一种新方法.此方法采用CCD图象处理技术与计算机技术相结合,实现了数据采集、计算处理自动化.有效降低了测量时人为因素的影响,提高了测量的准确度.它为物理量的转换测量提供了一种可行的参考途径.     

小湾高拱坝上游坝踵人工短缝设置效果的深入分析

在已有研究成果的基础上,对小湾高拱坝坝踵附近人工短缝的设置效果进行全面、深入分析。采用无厚度的接触单元模拟人工短缝的工作性态,坝体混凝土本构模型采用单轴等效拉伸软化模型,分别采用整体模型和子模型对不同人工短缝设置高程、不同的缝内水压力进行了比较分析。从运行期的整体仿真计算结果来看,小湾拱坝设上游人工短缝后,坝踵应力可以得到较大的改善,且对坝体的整体性影响较小。为了更加合理地评价高拱坝人工短缝设置的效果,建议同时考虑施工期和运行期的荷载进行综合分析计算,为小湾拱坝人工短缝的设计提供科学依据。     

关于双缝干涉条纹在几种不同情况下的讨论

本文以杨氏双缝干涉实验为基础，讨论了在实验装置的几种变化情况下干涉条纹的变化。     

Reduction of droplet of tantalum oxide using double slit in pulsed laser deposition

We developed a double slit method in order to reduce droplets that were a problem in pulsed laser deposition (PLD) of tantalum oxide. The tantalum oxide films were deposited using KrF excimer laser ablation of a Ta target in 5 mass% O₃ at a pressure of 10 Pa. Stoichiometric and dense films with few droplets were obtained at a pressure of 10 Pa. Without double slit, as the laser pulses increased, the number of droplets containing rich metal on the film gets increased and its size became larger, and the surface morphology of the target also became more and more rugged. It was found that the number of droplet could be controlled by changing the initial roughness of the target. The number of droplets with a diameter size of under 1 μm was decreased to 1/10 of their sizes. Droplets larger than 3 μm, which mostly affect the corrosion resistance and hardly increase even beyond the laser pulses of 100 000. It is evident from this study that the double slit is a very effective method for reducing the droplets, which are otherwise a problem often seen in film production by PLD.     

切分轧制变形的实验研究

对轧件切分轧制过程中的变形进行了实验研究。较为详细地介绍了连铸板坯切分、窄板坯的立轧、预对中孔型轧制及成品孔型实验的轧制变形的结果及分析     

膜缝沟灌技术要素试验研究

试验选择了膜缝宽度、土壤初始含水率、土壤密度及水深四个因素,通过四因素-三水平的正交试验设计方案,采用极差分析方法,以入渗速率和水平与垂向湿润锋推进距离的比值为评价指标,得出了适宜室内试验条件下膜缝沟灌较为合理的技术要素组合,即当初始含水率为9%、土壤密度为1.45g/cm3时,最优膜缝宽度为5 cm,最佳水深为12 cm。这对提高田间水利用率和灌溉水利用率,有一定的理论和实践意义。     

基于VB与MATLAB编程模拟光栅光谱分析系统

该仿真软件将Matlab的计算优势与Visual Basic图形用户界面开发方面的优势结合起来仿真模拟了单色光单缝衍射和光栅衍射实验,实验结果的图样细致逼真,结合3D动画演示使整个物理过程变得直观,为光学的理论分析和实验教学提供了新的途径。     

Further slot antenna miniaturization and bandwidth enhancement

In this work, antenna miniaturization using slits and metallic strips fed by microstrip line has been demonstrated. It has been noticed that slot antenna fed by microstrip line provides more miniaturization and in some cases enhanced bandwidth in comparison with the slot antenna fed by other feeding mechanism, keeping the same length and width of the radiating slots, slits and metallic strips. We have achieved 51.67% reduction in resonant frequency and 74.72% improvement in ?10 dB bandwidth compared with 37.73% and no bandwidth improvement of either side slits loaded slot antenna topology. Further, it has been shown 63.52% reduction in resonant frequency and 2.23% improvement in ?10 dB bandwidth in comparison with 42.33% reduction in resonant frequency of only one side slits loaded slot antenna topology. The current work highlighted not only greater miniaturization and enhanced bandwidth but also almost unperturbed radiation pattern compared to reference antenna topology and low cross‐pol level even slot antenna loaded by only one side slits, which was not demonstrated in earlier works.     

Broadband planar dipole array Antenna with double C‐shaped slit elements for digital TV broadcasting transmission

This research has proposed a planar rectangular dipole antenna enclosed in double C‐shaped parasitically slit elements (i.e., radiator element) on a double‐cornered reflector for bandwidth enhancement. In the study, simulations were first carried out to determine the optimal parameters of the radiator element and then a radiator element prototype was fabricated and mounted onto a double‐cornered aluminum reflector. The simulated and measured |S₁₁|<–10 dB of the antenna element covered the frequency ranges of 451–901 MHz (66.6%) and 455–886 MHz (64.3%), respectively. The gain was enhanced by the subsequent deployment of multiple radiator elements to fabricate a four‐element vertically array antenna on an elongated double‐cornered reflector. The simulated and measured |S₁₁|20 and 相似文献