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排序方式: 共有146条查询结果,搜索用时 31 毫秒
1.
Manolis Souliotis Christos S. Garoufalis Andreas P. Vouros Angeliki Kavga 《国际能源研究杂志》2019,43(2):884-895
The distribution of solar irradiance on the absorbing surface of a typical integrated collector storage (ICS) system combined with reflector troughs is commonly studied by means of ray tracing techniques. A conceptually different alternative is offered by the method of the average number of reflections (ANR). In the present work, the latter is employed for the systematic optical study of realistic ICS models. In all cases, the solar devices consist of twin cylindrical storage tanks which are mounted on top of stationary asymmetrical CPC‐type reflectors. The emphasis of the current research is mainly placed on the evaluation of the ANR reliability for the calculation of the optical efficiency of the related twin‐tanked devices. Additionally, useful operational parameters, such as the optical performance of the proposed geometries, are also determined. The behavior of the tested ICS systems reveals that the optical efficiency may vary in the range of 0.75 to 0.91, exhibiting a strong dependence on the geometric parameters of the solar devices. The highest efficiency is achieved by the systems which combine large reflecting area and storage tanks in close proximity. 相似文献
2.
《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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4.
曹文颖 《石油化工管理干部学院学报》2013,(1):14-16
以中国石化济南分公司党校办校实践为例,阐述企业党校的任务和性质,分析其现状与问题,并提出在新形势下办好企业党校必须正确处理的“六个关系”。 相似文献
5.
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
6.
孙净丽 《安徽电子信息职业技术学院学报》2007,6(2):28-29
英语委婉语作为英语语言词汇中极为活跃的一分子是社会交际活动的产物,它反映了英语国家人们的风俗习惯、审美情趣、文化素养.在实际应用中,人们为了避讳、礼貌、欺骗、美化等交际目的而频频使用委婉语,从而增强表达效果,完成漂亮的交际活动. 相似文献
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8.
Results of experimental measurements of emissivity carried out on cobalt oxide and nickel sulphide films deposited on aluminum substrates are reported in this paper. Experimental results supported the general behaviour of variation of emissivity with film thickness as reported theoretically. The theoretical model is based on the interaction and attenuation of the emitted wavelengths from the substrate and film materials. 相似文献
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10.
A. E. Isaev 《Measurement Techniques》2005,48(12):1227-1234
The sensitivity of a hydrophone in the frequency band when there is a source of reflections which increases the characteristic
size of the hydrophone is considered. The effect of the width of the frequency band on the change in the characteristic size
is investigated. It is shown that the characteristic size of the hydrophone may be reduced considerably and that far-field
conditions can be ensured for measurements in a hydroacoustic basin when it is calibrated in 1/3-octave frequency bands.
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Translated from Izmeritel’naya Tekhnika, No. 12, pp. 53–57, December 2005. 相似文献