孔板流量计在瓦斯抽采计量中的误差来源分析

瓦斯抽采计量为煤矿采掘工作面抽采效果分析和瓦斯抽采达标评判提供基础数据，采用合适的流量计量工具能够起到事半功倍的效果。孔板流量计以操作简易、计量准确的优点被广泛应用于矿井瓦斯抽采计量工作。受瓦斯抽采管路中恶劣的计量环境及其他因素影响，孔板流量计在使用过程会出现数据波动，存在计量误差的问题。结合孔板流量计计量的方法和步骤，对误差来源深入分析研究，得出安装、流体杂质阻塞、附属物选择、人工操作等方面造成的流量计量误差原因，采取有针对性的措施以减少系统、环境和人为误差影响。瓦斯抽采计量误差的减少和消除，有效提高了瓦斯抽采计量的准确性，是提高灾害防治效果和效益的重要手段，是安全生产的重要保证。     

A methodology exploiting geographical information systems to site a photovoltaic park inside a sustainable community

This paper describes a methodology for applying geographical information systems (GIS) tools to site a photovoltaic (PV) park inside a sustainable community, in order, not only to meet all siting restrictions, such as environmental protection, but also to operate a PV park more efficiently reducing the shading effect erection and cabling cost. Additionally, the PV operation impact on the grid is investigated, integrating GIS maps into power systems analysis software, such as the PowerWorld^® Simulator. In other words, this paper also stresses the importance of GIS for the design, installation and monitoring of power systems. A case study considering the Campus of the Technical University of Crete has been performed showing that siting properly a PV installation meeting 20% of the demand can gain significant savings in both peak and regular energy demands, especially on peak summer days.     

Unconventional photon blockade in weakly nonlinear photonic molecules with bilateral drive

In this paper, we study the unconventional photon blockade of symmetric and antisymmetric modes in a photonic molecule system with bilateral drive. We show that the photon blockade effect is controllable by manipulating the tunnelling strength of two cavities and the ratio of driving strengths. Under the weak driving condition, we present the exact optimal conditions for strong antibunching photons. The optimal conditions are in good agreement with the numerical results. It is also found that the optimal value of detuning frequencies is not sensitive to the value of the ratio to achieve the unconventional photon blockade effect. The feasibility of tunable unconventional photon blockade effect also has been studied based on the experimental parameters. Our studies of the photonic molecule system can be used as a single-photon source based on the symmetric and antisymmetric modes in the regime of weak nonlinearity.     

An industrial approach of laser polishing with different laser sources

Surface finishing of dies and molds is one of the most interesting applications of laser polishing process. Because of the variety of materials used in die and mold manufacturing, as well as the different surface topographies, in each case, it is necessary to use appropriate process parameters. The presented work focuses on the study of laser polishing process on three commonly used materials in the manufacture of dies and molds, such as tool steels AISI D2 and AISI P20, ductile cast iron GGG70L and LaserForm ST‐100, a specific material developed for plastic injection mold making. Experimental studies were carried out determining the influence of the energy density on the roughness reduction rate. A key point that has a direct impact on the resulting surface roughness is the initial surface finishing of the material before laser polishing. In order to determine the degree of influence, experimental studies were conducted on two steels, AISI H13 and AISI P20, which are typically used in mold making industry. The experimental tests showed that a random distribution of peaks and valleys allows more homogenous material melting and gives as result a smoother surface after laser polishing.     

钉状ZnO的制备及其光致发光性能的研究

化学气相沉积制备纳/微ZnO的过程中,当采用纯锌粉为锌源时,锌源易凝结成块.为了实现均匀的锌蒸汽蒸发速率,以混合SiO2的Zn粉为锌源,研究了纳/微ZnO产物的形貌和光致发光性的变化规律.采用SEM、XRD和PL光谱对产物进行了表征.SEM结果表明上游产物的形貌变化较为显著,下游产物形貌变化较小.XRD结果说明所有产物沿c轴择优生长.PL表明下游产物绿光发射峰相对强度降低,紫外发射峰强度相对增强.     

Electromagnetic flow meters for open channels: Current state and development prospects

Electromagnetic method to measure water flow has been known for nearly 180 years. This paper presents how the method has undergone development and describes in detail the most common electromagnetic flowmeters used for open channels. It also presents specific methods of signal processing used in this type of flowmeters. The analysis is associated directly with the relevant types of induced magnetic field. Some of the analyzed types of magnetic fields considered are sine waves and bipolar rectangular fields. The concept of low-energy electromagnetic flow meter was introduced as part of deliberations concerning current development trends.