Optimization of the CIGS based thin film solar cells: Numerical simulation and analysis

Chalcopyrite Cu(In,Ga)Se (CIGS) is a very promising material for thin film photovoltaics and offers a number of interesting advantages compared to the bulk silicon devices. CIGS absorbers today have a typical thickness of about 1–2 μm. However, on the way toward mass production, it will be necessary to reduce the thickness even further. This paper indicates a numerical study to optimization of CIGS based thin film solar cells. An optimum value of the thickness of this structure has been calculated and it is shown that by optimizing the thickness of the cell efficiency has been increases and cost of production can be reduces. Numerical optimizations have been done by adjusting parameters such as the combination of band gap and mismatch as well as the specific structure of the cell. It is shown that by optimization of the considered structure, open circuit voltage increases and an improvement of conversion efficiency has been observed in comparison to the conventional CIGS system. Capacitance–voltage characteristics and depletion region width versus applied voltage for optimized cell and typical cell has been calculated which simulation results predict that by reducing cell layers in the optimized cell structure, there is no drastically changes in depletion layer profile versus applied voltage. From the simulation results it was found that by optimization of the considered structure, optimized value of CIGS and transparent conductive oxide thickness are 0.3 μm and 20 nm and also an improvement of conversion efficiency has been observed in comparison to the conventional CIGS which cell efficiency increases from 17.65 % to 20.34%, respectively.     

Chaotic biogeography-based optimization approach to target detection in UAV surveillance

This paper describes a novel chaotic biogeography-based optimization (CBBO) algorithm for target detection by means of template matching to meet the request of unmanned aerial vehicle (UAV) surveillance. Template matching has been widely applied in movement tracking and other fields and makes excellent performances in visual navigation. Biogeography-based optimization (BBO) algorithm emerges as a new kind of optimization method on the basis of biogeography concept. The idea of migration and mutation strategy of species in BBO contributes to solving optimization problems. Our work adds chaotic searching strategy into BBO and applies CBBO in template matching. By utilizing chaotic strategy, the population ergodicity and global searching ability are improved, thus avoiding local optimal solutions during evolution. Applying the algorithm to resolving template matching problem overcomes the defects of common image matching. Series of experimental results demonstrate the feasibility and effectiveness of our modified approach over other algorithms in solving template matching problems. Our modified BBO algorithm performs better in terms of convergence property and robustness when compared with basic BBO.     

Maps and inverse maps in open quantum dynamics

Two kinds of maps that describe evolution of states of a subsystem coming from dynamics described by a unitary operator for a larger system, maps defined for fixed mean values and maps defined for fixed correlations, are found to be quite different for the same unitary dynamics in the same situation in the larger system. An affine form is used for both kinds of maps to find necessary and sufficient conditions for inverse maps. All the different maps with the same homogeneous part in their affine forms have inverses if and only if the homogeneous part does. Some of these maps are completely positive; others are not, but the homogeneous part is always completely positive. The conditions for an inverse are the same for maps that are not completely positive as for maps that are. For maps defined for fixed mean values, the homogeneous part depends only on the unitary operator for the dynamics of the larger system, not on any state or mean values or correlations. Necessary and sufficient conditions for an inverse are stated several different ways: in terms of the maps of matrices, basis matrices, density matrices, or mean values. The inverse maps are generally not tied to the dynamics the way the maps forward are. A trace-preserving completely positive map that is unital cannot have an inverse that is obtained from any dynamics described by any unitary operator for any states of a larger system.     

无线传感器网络中继节点布居算法的研究

本文表述的是在该应用背景下引入多约束条件, 并采用枚举法与贪婪寻优算法相结合的方法, 解决了在可以作为中继节点设置位置的预设中继节点位置集合内, 合理选择中继节点设置位置以及既存网络因添加新传感器节点所引起的中继节点追加的问题. 仿真实验表明, 本文提出的中继节点布居与追加优化算法能够保证多约束条件下网络的容错性. 同时提出的基于最小网络距离因子评价标准, 有效提高了中继节点布居算法的能效性.     

考虑最佳入口温度的多股流换热器网络循环优化

针对于多股流换热器网络的应用优势,本文在衍生网络优化方法基础上,提出了考虑最佳入口温度的多股流换热器循环优化方法,即利用多股流换热器网络小面积换热器合并而不产生固定投资费用这一特点,将优化结果中存在公用工程的流体返回到另一种流体的入口并与其入口流体进行循环优化。结果表明,这种优化方法能够进一步发挥多股流换热器网络的优点,得到年综合费用更小、运行费用更低的网络结构。     

基于遗传LM算法的涂层目标光谱偏振BRDF建模分析

通过比较测量方法测量得到绿漆涂层木板探测目标在400～720 nm的光谱偏振二向反射分布函数值,从获得的户外试验测量数据入手,分析与探测角、波长之间的关系,通过有限探测条件得到的光谱偏振二向反射分布函数值(BRDF)建立光谱偏振BRDF模型,来描述探测目标的偏振二向反射特性。其中利用基于小面元的模型建立光谱偏振BRDF模型,利用遗传算法和Levenberg-Marquardt(LM)算法相结合的优化算法来获得非线性模型参数。仿真实验结果表明采用的遗传LM优化算法具有较好的性能,能较快较准确得到非线性的模型参数。真实实验数据证明了基于小面元模型的正确性,表明光谱偏振二向反射分布函数建模方法结果的可靠性。最后与绿漆涂层铁板目标的模型反演参数进行比较得出：2种不同材质、相同颜色涂层的目标,具有较为接近的折射率,其较小差别可以理解为由涂层的厚度、均匀程度的不同导致,而非不同的材质所引起。     

压缩空气蓄能(CAES)系统集成及性能计算

压缩空气蓄能(CAES)系统是一种新型电能存储系统,具有动态响应快、经济性能高、环境污染小等优点,可起到负荷平衡、战略规划、提高供电质量的作用。CAES系统包括空气压缩机、电动机/发电机、地下贮气室、换热器、燃烧室、燃气轮机等常用设备,可分为两个子系统,分别是蓄能子系统和发电子系统,通过对设备采取不同组态,可得到不同方案系统。本文将结合当前CAES发展的新技术,提出CAES系统的集成方案并进行相应的计算与优化。     

The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ∝△(T -1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and w...     

基于双向偏振态激光诱导荧光方法的离子速度分布函数测量

为了评估利用发散磁场构型双电层效应的紧凑式螺旋波等离子体推力器的离子加速效果,探索了一种双向偏振态激光诱导荧光测量方法来对螺旋波等离子体源近出口端的离子速度分布函数进行测量。实验中采用Ar作为螺旋波等离子体源工质,中心波长为611.662 nm的激光以轴向方式注入等离子体,以激励一价Ar离子获得波长为461.086 nm的诱导荧光光谱。为了消除磁化等离子体中逆塞曼效应对激光诱导荧光光谱带来的分裂影响,通过四分之一波片将入射激光分别调制为左旋和右旋圆偏振态,并对其诱导光谱进行了分别测量,结果发现不同磁场强度下两次测量结果的偏移值与理论高度吻合,证明了双向偏振态激光诱导荧光测量方法的理论可行性。进一步,采用高斯型滤波器反卷积算法从测量光谱中去除自然展宽和能量饱和效应,再通过对两次相反偏振态测量结果进行平移处理消除逆塞曼效应,从而分离得到实际的多普勒效应。测量了射频能量600 W,不同轴向位置、磁场大小以及气体压力下的螺旋波Ar等离子体激光诱导荧光光谱,结果表明在该实验条件下离子并没有因双电层效应而达到期望值的加速效果,离子速度的形成可能只是一种磁约束作用下的双极电场所导致,并不能产生好的推力性能。     

频率自适应最优权重阵列干涉条纹处理技术

考虑长基线水平阵列波束形成对声场模态呈现的滤波特征,建立了一种随频率改变滤波通带的阵列权矢量设计方法。基于简正波理论,结合声场波束形成特点,在分析了常规波束形成信号LOFAR谱图干涉条纹的清晰度和条纹结构不同于单水听器输出信号条纹现象基础上,采用线性等式约束的二次优化模型,给出了一种频率自适应的最优权重估计。数值仿真验证和试验数据分析表明,利用该方法设计的最优权重阵列波束处理,可以滤波出SRBR(Surface-Reflected Bottom-Reflected)或N-SRBR(Non-Surface-Reflected Bottom-Reflected)模态组成的波束形成信号,信号谱图干涉条纹斜率与理论分析基本一致。