Optical study of twin‐tanked ICS solar heaters combined with asymmetrical CPC‐type reflectors

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.     

理论分析光偏振对导光管光传输效率的影响

光传输效率(LTE)是衡量导光管采光性能的最重要参数。在导光管LTE计算中，常常忽略了光线在管中若干次镜面反射引起的光偏振的累积效应。因此，为厘清连续镜面反射引起光偏振的累积效应，通过光学理论分析与公式推导，在确定光偏振对镜面反射材质反射率的影响之后，首次揭示了导光管内壁反射率随反射次数的变化规律，以及反射率的变化对导光管LTE的影响。结果表明：单束自然光线每投射到管内壁一次，就会产生一次光偏振，并在两个正交分量上产生不同的反射率，即ρ_⊥和ρ_‖,且ρ_⊥≥ρ_‖;历次反射中ρ_⊥和ρ_‖数值保持不变，但整体反射率会随反射次数增多而逐渐变大，故导光管内光损速率会不断减缓；由此提出了导光管中单束光线的LTE表达式，为建立复杂光源下LTE数学计算模型，奠定了理论基础。     

Measuring and evaluating bitumen coverage of stones using two different digital image analysis methods

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.     

生态导向的城市空间规划问题反思及案例研究——以绍兴袍江新区两湖区域空间发展规划为例

回顾了生态导向的空间规划历程,对生态导向的空间规划存在问题的进行反思,提出针对性的规划对策,并以绍兴袍江新区两湖区域空间发展规划为例,探讨了两湖区域空间发展规划方案的规划技术框架、规划构思、空间布局及生态规划技术手法,并对方案进行规划效益评价,以期检验规划效果.     

加强企业党校建设的思考

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”。     

Scaling law for penetration depth in laser welding

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.     

英语委婉语的心理映射

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.     

Emissivity of substrate supported films

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.     

高可视性服装的分类和检测评价

介绍了反光型、荧光型、夜光型和电致发光型高可视性服装的应用、分类以及检测评价,分析了各类高可视性服装的发光原理和优缺点,比较了国内外高可视性服装相关标准的检测方法和评价指标。其中电致发光型服装作为一种新型的高可视性服装,需要尽快建立相应的检测标准和评价指标。