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1.
In this report, a free space frequency‐time‐domain technique is presented for characterizing the electrical properties and thickness of the sample using multiple reflections and fabry‐perot resonance phenomenon. The retrieval of constitutive electromagnetic parameters of the sample has been carried out by comparing the measured reflection coefficient data from the sample at two different incident angles. The relative permittivity as well as relative permeability along with the thickness of different samples viz., beryllia, silicon, and plexiglass have been evaluated with high accuracy in the frequency range 1 to 15 GHz. The method is also experimentally validated by successfully reconstructing the unknown material properties of two different samples. The unique advantage of this method lies in non‐requirement of any prior knowledge of the sample's thickness for measuring the complex relative dielectric constant as well as relative permeability of the sample. To determine the electromagnetic properties of the sample, the sole knowledge of reflection coefficient data are needed. Moreover, the method does not involve any additional measurement for the reference calibration. The simple, cost‐effective proposed scheme is quite useful in many applications like accurate determination of signal strength in indoor wireless communication, through wall imaging, food industry, and so on. 相似文献
2.
针对矩形暗室内多径反射对天线测量精度的影响,引入了间接时域加门的方法;该方法利用逆傅里叶变换对宽带扫频数据进行处理获得天线的时域响应,然后采用时间门去除多径信号,变换到频域后可获得较准确的天线电参数,如方向图等;同时为了减少时域响应的泄漏,进一步提高测量精度,采用了基于频域加窗的逆傅里叶变换;对该方法进行仿真分析和实验验证,结果表明采用该方法得到的方向图与标准方向图基本吻合,具有一定的有效性和实用性。 相似文献
3.
全面介绍了长江科学院2012年对长江和澜沧江源区的河道形态、水文、泥沙、水资源变化及开发利用情况、水土流失现状及成因、水环境水生态状况及地质地貌等开展科学考察的全过程;着重论述了此次科学考察的目的、意义、任务和内容、组织形式;总结了高原上开展大型科学考察在专业及人员遴选、考察方案及技术准备、考察路线选择、身体条件准备、后勤保障等方面以及考察实施过程中的成功经验与存在的不足,提出的诸多建议可为今后开展类似科学考察借鉴。 相似文献
4.
《Measurement》2016
The most used pavement for paved roads in the world is asphalt. It is therefore important that the asphalt is as durable as possible to avoid expensive repairs of the roads. One important factor of the durability of the road is the adherence between the stones and the bitumen that holds the stones together. The affinity is tested by the so called rolling bottle test, where one put stones covered in bitumen in a bottle with water and let it roll on a bottle rolling machine. After a while the degree of bitumen coverage is estimated. In this paper, a method to estimate the degree of bitumen coverage using image analysis has been developed instead of the manual estimation that is used today. The presented method works for all colors of the stones and is based on the fact that bitumen reflects light much better than raw stones. A turntable that is rotated somewhat between images is used together with a light source in shape of a quarter of a circle to get as much specular reflections as possible. Then the amount of detected reflections is used to estimate the degree of bitumen coverage. To be able to compare the result with something close to ground truth, the method has been evaluated on lighter stones and compared with a second image analysis method that works well for lighter stones, and the results are promising. 相似文献
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6.
A simple scaling law for penetration depth in laser welding is proposed considering heat flow characteristics and multiple reflections. First, a process parameter is identified that is proportional to the surface temperature during laser processing, and the parameter is modified by accounting for the effect of multiple reflections. As a result, the normalized penetration depth is expressed as a function of a single parameter that is a combination of laser intensity, interaction time and an indicator of the strength of multiple reflections. The obtained scaling law is applicable not only to conduction mode welding but also to keyhole mode welding, and provides insight into why and how penetration depth changes in a particular way. Systematic and extensive welding experiments were conducted using a 2 kW multi-mode fiber laser and two types of steels. The experimental results were in good agreement with the proposed scaling law. 相似文献
7.
陈金树 《石油化工管理干部学院学报》2013,(4):25-27,39
针对企业组建时期员工存在的心理问题,福林气体公司通过实施员工心理健康评估、加强宣传培训、建立EAP专业队伍、拓展服务渠道、创造舒适环境等手段,有效地提高了员工对EAP的认同、对企业的满意度,企业整体环境更加和谐,员工对企业发展更有信心。 相似文献
8.
温克勤 《徐州建筑职业技术学院学报》2005,5(1):1-6
对儒家伦理的基本价值与基本特点以及局限性进行了疏理和分析,对于国内外学者对儒家伦理的肯定性评价和提出的有关儒学研究的理论方法作出了评介,在此基础上提出了研究儒家伦理的几点认识和启示. 相似文献
9.
高校开展心理健康教育的过程中,各校纷纷在课程教育方面做了探索,并取得了良好的效果,但是在课程体系的建设上还有许多理论与实践的问题需要进一步研究。本课题组通过实践和调查,对心理健康教育课程的基本地位、基本原则、教学目标和内容、基本模式和教学手段等等做了初步的研究,提出了几点思考,以利于心理健康课程教育的规范建设,从而发挥心理健康教育的积极功能。 相似文献
10.