Calculating the shading reduction coefficient of photovoltaic system efficiency using the anisotropic sky scattering model

The front-row shading reduction coefficient is a key parameter used to calculate the system efficiency of a photovoltaic(PV)power station.Based on the Hay anisotropic sky scattering model,the variation rule of solar radiation intensity on the surface of the PV array during the shaded period is simulated,combined with the voltage-current characteristics of the PV modules,and the shadow occlusion operating mode of the PV array is modeled.A method for calculating the loss coefficient of front shadow occlusion based on the division of the PV cell string unit and Hay anisotropic sky scattering model is proposed.This algorithm can accurately evaluate the degree of influence of the PV array layout,wiring mode,array spacing,PV module specifications,and solar radiation on PV power station system efficiency.It provides a basis for optimizing the PV array layout,reducing system loss,and improving PV system efficiency.

Optimum Sizing and Economic Analysis of Standalone PV System with a Small Size Grinding Mill

This work presents the results of the characterization of a standalone photovoltaic system for the electrification of a household located in rural area in the western region of Cameroon: Nziih-Bafou in Dschang (5.35°N, 10.05°E and 1900 m). In order to cope with the maintenance charges and reduce the investment cost, a small mill was added to the appliances of the household for income generation. The assessment of the energy demand was made by taking into account the reactive energy due to the heavy consumption of energy by the mill’s motor, especially during ignition. The sizing of all the system’s components was carried out with the prospect of determining an optimum design in accordance with daily electricity demand, site irradiance profile and climatic conditions. In this context, tilt angles applicable to the PV structure and that allow to receive the maximum irradiance as a function of the periods of the year were determined using the Hay model. This approach provides the system with incident irradiance greater than or at the limit equal to that received by a horizontal surface on the same site compared to the case of a single tilt angle where the irradiance on the inclined plane is often lower than that on the horizontal. The economic analysis of the PV system showed an initial cost of $4448 and the Life Cost Cycle amounted to $24,495. This amount corresponds to a present cost per kilowatt hour of $0.44. The Net Present Value (NPV) of the project ($7793) over its lifetime (20 years) shows a payback period of less than 4 years.

基于CBR,RBR,BBR集成推理在交通事故处理中的应用研究

随着道路交通量的急剧增加,交通拥挤、交通事故也在不断上升.如何能及时准确地处理交通事故并从中总结经验,吸取教训,制定防止类似事故发生的措施,是目前一项十分紧迫的任务.在深入研究了基于案例推理(CBR)、基于规则推理(RBR)、基于Bayes推理(BBR)方法的基础上提出并实现了一种集成这三种方法的智能推理模型,并把它应用到交通事故处理的推理中.它们的集成实现了优势互补,提高了系统求解问题的效率,增强了系统对不良结构问题的适应性,并且能很好地应用于带有不完全信息或矛盾信息的交通事故处理中.

三通法治疗中风病技术在北京市门头沟地区规范化应用推广及管理模式研究

目的研究三通法治疗中风病技术在北京市门头沟地区规范化应用推广及管理模式。方法该研究以三级医院培训二级医院,二级医院培训社区卫生服务中心为基本推广及管理模式,探讨中医适宜技术的优良推广及管理模式。结果独立第三方满意度调查结果:北京市门头沟区中医医院医生及北京市门头沟区九家卫生服务中心医生认为该培训有一定临床指导价值的占100%。结论该推广模式是中医适宜技术推广的优秀推广模式。

基于海耶斯-弗劳尔过程写作模型的英语过程写作核查表的开发与应用

本文基于海耶斯-弗劳尔过程写作模型,开发了英语过程写作核查表,并采用个案研究方法,对一名初三学生进行11次命题写作,通过量化和质性相结合的方法分析英语过程写作核查表对学生写作的实际影响。研究发现,过程写作核查表有助于学生对写作过程进行自我监控,辅以写作评分标准能够优化写作复查过程;过程写作核查表有助于提高学生作文的质量。基于上述发现,为保证教师更为有效地使用本文开发的核查表,作者提出了以下三点建议:(1)关注学生写作过程,灵活使用过程写作核查表;(2)呈现写作评分标准,辅助过程写作核查表优化写作过程;(3)开展写作策略培训,结合过程写作核查表提高写作效率。