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.

基于Shape-from-Shading的月球表面三维形状恢复算法研究

提出了一种基于Shape-from-Shading的月球表面三维形状恢复算法。首先分析了在太阳光照射下月球表面成像模型,建立了使用Lommel-Seeliger反射模型描述的反射图方程。然后用有限差分近似微分运算,将反射图方程所示的一阶变系数线性偏微分方程进行离散化处理,得到关于表面高度函数的代数方程。进而采用超松弛迭代法进行求解,获得月球表面三维高度函数值。最后使用合成图像和实际月球图像进行三维形状恢复仿真实验。实验结果表明提出的算法可以有效地恢复月球表面三维形状。

一种基于混合反射模型的Shape-From-Shading直接算法

提出了一种基于混合反射模型的Shape-From-Shading直接算法。使用接近实际的混合反射模型描述的反射图方程作为求解对象,用有限差分近似微分运算,将反射图方程离散化,得到所求高度函数满足的代数方程,进而用迭代算法计算出表面高度。最后,用以合成图像和实际图像的三维形状恢复实验说明提出算法的有效性。

RECONSTRUCTION OF WELD POOL SURFACE BASED ON SHAPE FROM SHADING

A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading （SFS） in computer vision is presented. The weld pool surface information is related to the backside weld width, which is crucial to the quality of weld joint. The image of weld pool is recorded with an optical sensing method. Firstly, the reflectance map model, which specifies the imaging process, is estimated. Then, the algorithm of weld pool surface reconstruction based on SFS is implemented by iteration scheme and speeded by hierarchical structure. The results indicate the accuracy and effectiveness of the approach.

Electrical Power Losses in a Photovoltaic Solar Cell Operating under Partial Shading Conditions

The aim of this paper is to determine the power losses recorded by a PV generator operating under partial shading conditions. These losses are evaluated through two distinct methods. The first method is based on mathematical modeling, while the second is based on Simulink’s physical model. The losses recorded are considerable and increase as a function of the increase in the percentage of shading up to a limit value where they become constant in the case where an ideal by-pass diode is connected in parallel with the modules. This limit value is non-existent in the case where the bypass diode is not ideal, which in fact corresponds to the real model. However, it emerges that the power losses are minimized in a PV system comprising bypass diodes, in particular in the case where the partial shading is considerable.

Curve interpolation model for visualising disjointed neural elements

Neuron cell are built from a myriad of axon and denddte structures. It transmits electrochemical signals between the brain and the nervous system. Three-dimensional visualization of neuron structure could help to facilitate deeper understanding of neuron and its models. An accurate neuron model could aid understanding of brain＇s functionalities, diagnosis and knowledge of entire nervous system. Existing neuron models have been found to be defective in the aspect of realism. Whereas in the actual biological neuron, there is continuous growth as the soma extending to the axon and the dendrite; but, the current neuron visualization models present it as disjointed segments that has greatly mediated effective realism. In this research, a new reconstruction model comprising of the Bounding Cylinder, Curve Interpolation and Gouraud Shading is proposed to visualize neuron model in order to improve realism. The reconstructed model is used to design algorithms for generating neuron branching from neuron SWC data. The Bounding Cylinder and Curve Interpolation methods are used to improve the connected segments of the neuron model using a series of cascaded cylinders along the neuron＇s connection path. Three control points are proposed between two adjacent neuron segments. Finally, the model is rendered with Gouraud Shading for smoothening of the model surface. This produce a near-perfection model of the natural neurons with attended realism. The model is validated by a group of bioinformatics analysts＇ responses to a predefined survey. The result shows about 82% acceptance and satisfaction rate.

A Matlab/Simulink-Based Photovoltaic Array Model Employing SimPowerSystems Toolbox

The modeling of PV （photovoltaic） systems is very crucial for embedded power system applications and maximum power point tracking. This paper presents a PV array model using Matlab/Simulink with the assistance of SimPowerSystem toolbox. The PV cell is considered as the main building block for simulating and monitoring the PV array performance. The PV model has been developed and used as Simulink subsystems where the effect of solar insolation and PV array temperature on commercial PV modules have been studied throughout the simulated I-V and P-V output characteristics. The proposed model facilitates simulating the dynamic performance of PV-based power systems. The effect of different partial shading patterns of PV arrays under different configurations has been studied.

Research into Freedom Surface Modeling System of Double Beta Spline in Space

In this paper, we present the double Beta spline curved surface which is controlled by double parameters including the algorithm principles, the treatment of boundary conditions, the alternation of projection, the algorithms of elimination hiddle line, the process to display and the primiples to produce the shaded curved surface. Based on all the above, a freedom surface modeling system (FSMS) is designed and some examples developed on FSMS are verified and analyzed.

Partial Shading of PV System Simulation with Experimental Results

In a solar photovoltaic array, it is possible that shadow may fall over some of its cells. Under partial shading conditions the PV characteristic gets more complex with multiple peaks. The purpose of this paper is to illustrate, by analyzing different shading situations, the effects that partial shading can cause in a PV array. First this is done by simulation using Matlab/Simulink, then the impact of shading is illustrated experimentally by measurements on a two commercial 140 W PV panels series connected.

Using Gaussian Mixture Model to Fix Errors in SFS Approach Based on Propagation

A new Gaussian mixture model is used to improve the quality of propagation method for SFS in this paper. The improved algorithm can overcome most difficulties of propagation SFS method including slow convergence, interdependence of propagation nodes and error accumulation. To slow convergence and interdependence of propagation nodes, stable propagation source and integration path are used to make sure that the reconstruction work of each pixel in the image is independent. A Gaussian mixture model based on prior conditions is proposed to fix the error of integration. Good result has been achieved in the experiment for Lambert composite image of the front illumination.

智能遮阳百叶眩光预测模型控制变量有效性分析

基于预测模型的智能遮阳百叶调控系统具有降低建筑室内眩光性能的能力,其智能性取决于调控方法。而调控方法的设计取决于对室内采光性能相关影响信息的思考。不同影响信息是调控反馈的依据,也是智能预测模型建构的基础。本研究利用机器学习技术,对不同百叶控制变量展开眩光关联性分析,以及不同控制变量在眩光影响上的交互效应。利用XGBoost构建预测模型与展开特征选择,同时采用SHAP可解释方法进一步解析变量与眩光关联大小。研究结果表明,室内使用者所在区域与遮阳百叶之间距离、遮阳形变与眩光发生最为紧密,且互动性影响明显,同时太阳高度角也是遮阳百叶重要的响应信息。结论可为智能遮阳百叶调控系统设计和预测模型建构提供参考依据。

开放办公空间智能遮阳百叶天然采光眩光预测模型建构研究

在多窗户、多区域的开放办公空间中,利用智能遮阳百叶对天然采光引发的眩光进行调控具有挑战性,既需协同不同区域视觉舒适性最佳,又需考虑不同百叶遮阳形式下的复合影响效应。受惠人工智能技术浪潮,采用机器学习算法建构有效的眩光预测模型成为解决开放办公空间智能遮阳百叶眩光调控的有力手段。基于此,本研究通过相关实验,对不同机器学习算法的眩光预测模型建构性能进行综合对比,得出最佳机器学习算法,以实现有效开放办公空间智能遮阳百叶天然采光眩光预测模型的建构。

基于图像几何信息的遮荫条件下茄衣烟叶形态特征分析与叶面积生长模型构建

【目的】筛选遮荫影响茄衣烟叶的关键形态特征指标,建立茄衣烟叶叶面积生长模型,明确遮荫条件下茄衣烟叶动态发育规律,以期为国产茄衣烟叶精准栽培提供理论依据。【方法】以雪茄烟品种CX81为试验材料,设3个遮荫处理,分别为透光率60%(T1)、透光率70%(T2)和透光率100%不遮荫对照(CK)。基于图像几何信息提取烟叶形态特征,测定上、中、下3个叶位叶片的动态生长指标,对不同透光率下茄衣烟叶的形态特征进行正交偏最小二乘判别分析(OPLS-DA),并建立叶面积生长模型。【结果】OPLS-DA结果表明,上、中、下部烟叶在不同透光率处理下的形态特征参数存在明显差异,随着叶位提高,受遮荫影响的形态指标逐渐减少,3个部位的共同指标有叶面积生长速率、叶面积、叶周长和茎叶夹角。遮荫条件下,叶面积与遮荫时间的关系符合Richards模型,其方程为y=a/(1+e^(b-cx))^(1/d),模型稳定性好,拟合程度高,具备生物学意义。随着透光率增加,叶面积先增大后减小,T2处理叶面积最大,遮荫45 d时,T2处理的叶面积较CK增加4.7%~17.4%;同一部位烟叶平均生长速率呈慢—快—慢的变化规律,T2处理叶面积平均生长速率最大,较CK提高5.5%~13.4%。【结论】叶面积生长速率、叶面积、叶周长和茎叶夹角是影响遮荫条件下茄衣烟叶叶片形态的关键指标,Richards模型可有效预测遮荫条件下茄衣烟叶叶面积生长,70%透光率可加快叶面积生长速率,有效提高叶面积。

基于全球海域多波束测深数据构建DBM与Web服务

为解决全球海域多波束测深数据查询使用不便的问题,通过数据分块实现海量数据处理,使用逐点插值算法构建数字水深模型,将晕渲图与数字水深模型组合构建可视化查询服务,实现基于浏览器查看水深数据和查询水深值等功能。对已有的全球海域多波束测深数据进行了处理,结果表明该方法对海量数据有着很好的承载能力,构建的数字水深模型能够反映测深点分布情况,Web查询服务响应迅速;同时该方法基于常用GIS软件处理数据,可操作性强,可用于海量多波束测深数据管理。

基于Blender制作地貌晕渲图的研究与实践

详细探讨了利用Blender这一强大的三维创作软件制作地貌晕渲图的方法,通过对软件功能的深入研究以及对数据处理与建模、材质与纹理设置、光照与渲染等方面的阐述,展示了Blender在地貌晕渲图制作中的独特优势和可行性,为相关领域的研究和实践提供了有价值的参考。

局部阴影条件下光伏阵列的建模与分析

阴影的存在使光伏阵列的输出伏安特性曲线呈阶梯状,相应的功率电压曲线含有多个局域峰值,现有的常规电池模型不再适用,因此需要建立适用于阴影条件下光伏阵列的数学模型。以太阳能电池的工程用模型为基础,结合电路的串并联理论,对局部阴影条件下光伏阵列进行了详细的分析,从理论上推导出部分遮挡情况下光伏阵列的数学模型可以用分段函数表述,并对其进行实验验证,证明所建模型能较好地描述阴影条件下光伏阵列的输出特性。利用所建模型对阴影条件下具体光伏阵列在不同阴影数量、遮挡模式、光照、温度下的工作情况进行仿真分析及计算,结果表明:局部阴影对阵列输出特性的影响因阵列的格局、阴影的数量和分布以及温度、光照、遮挡模型的不同而有所差异。

局部阴影条件下光伏阵列仿真模型的研究

阴影的存在使光伏阵列的输出伏安特性曲线呈阶梯状,相应的功率电压曲线含有多个局域峰值,常规的电池模型不再适用。研究适用于局部阴影条件下光伏阵列的数学模型,并对其进行实验验证,证明所建模型能较好的描述局部阴影条件下阵列的输出特性,同时利用MATLAB建立光伏阵列的仿真模型。利用所建仿真模型对阵列的输出特性进行仿真分析,提出适用性较广的光伏阵列优化设计方法,为光伏系统的工程设计提供有力支持。

适用不同尺度光伏阵列的数值建模方法

把光伏电池电路模型的离散计算结果作为基准数据源,利用数值计算方法实现对光伏阵列及各光伏单元的建模,详细阐述了该建模方法的实现机理及数学模型表达。针对光伏阵列运行中常遇到的阴影遮挡工况,建立了不同规模(单体光伏电池、组件、组串、阵列)的遮挡模型,并给出仿真结果。结果表明:在不同遮挡率下,单体光伏电池、组件的I-V输出特性曲线只有一个阶梯,P-V输出特性曲线仅有一个功率峰值;组串I-V输出特性曲线阶梯个数等于组件不同遮挡率个数,P-V输出特性曲线功率峰值个数不大于阶梯个数,并验证了两者之间的确切关系;光伏阵列的功率峰值个数与各组串的峰值个数关系复杂。该模型可适用于不同规模光伏阵列,仿真灵活,也容易与电力电子回路集成实现系统级仿真。

敦煌石窟彩塑漫游技术

以敦煌莫高窟洞窟漫游系统为应用背景 ,介绍了系统中彩塑漫游部分的相关技术、操作方法 ,以及实验结果。根据敦煌彩塑的自身形态、位置、尺寸等特征 ,以及当前计算机的运算能力 ,我们把彩塑漫游的方法归结为 3D建模和IBR漫游两大类 ;利用三维扫描和数字摄影获得的彩塑信息 ,经过模型简化、纹理生成、计算IBR中间图像等处理步骤 ,得到漫游时使用的模型数据 ;将模型数据直接应用在漫游系统中 ,并增强了阴影等真实感效果 ,获得最终的漫游结果。

可照时间受地形的影响及其精细的空间分布

设计了起伏地形下可照时间分布式计算模型,讨论了不同纬度的坡度、坡向、遮蔽等地形因子对可照时间的影响。结果表明:可照时间的纬向分布特征明显;同一纬度,同一坡向的可照时间随着坡度的增加而减小;坡向对可照时间的影响复杂,不同坡向上的可照时间随季节和坡度变化;在太阳高度角较低的冬季,地形遮蔽对可照时间的影响显著,可明显地影响可照时间的空间分布,清楚表现出可照时间的非地带性。同时绘制了 1: 100万我国实际地形下精细的可照时间空间分布。