High-efficiency drift-field thin-film silicon solar cells grown on electronically inactive substrates

A drift-field in the base region of a solar cell can enhance the effective minority-carrier diffusion length, thus increasing the long-wavelength spectral response and energy-conversion efficiency. Silicon thin-films of 20–32 μm thickness as a cell base layer were grown by liquid-phase epitaxy (LPE) on electronically inactive heavily doped p⁺⁺-type CZ silicon substrates. Growth was performed from In/Ga solutions, and in a purified Ar/4%H₂ forming gas ambient, rather than pure H₂. The Ga dopant concentration was tailored throughout the p-type film to create a drift-field in the base layer of the solar cell. An independently confirmed efficiency of 16.4% was achieved on such an LPE drift-field thin-film silicon solar cell with a total cell area of 4.11 cm². Substrate thinning, combined with light trapping which is encouraged by the textured front surface and a highly reflective aluminium rear surface, is demonstrated to improve the long-wavelength response and thus, increase cell efficiency by a factor of up to 23.7% when thinned to a total cell thickness of 30 μm.     

Texture variation in apricot: Intra-fruit heterogeneity, impact of thinning and relation with the texture after cooking

The rapid texture loss of apricot fruit during storage and transformation is a limiting factor for its commercialisation and use. Apricot flesh exhibits different tissue zones which differ in texture. To better understand texture in apricot fruit, we have studied (i) the intra-fruit heterogeneity of texture measured by puncture test (tissue firmness) (ii) the effect of thinning on whole fruit firmness (global firmness), measured by compression, and on tissue firmness and (iii) the evolution of texture upon steam cooking, on apricots of contrasted texture. Nine tissue zones were defined in fresh apricot fruits in order to study differences in texture from the peduncle to the pistil zones and from the external to the internal tissue. In the nine apricot varieties used, tissue firmness decreased gradually from the external to the internal tissue. However, from the peduncle to the pistil zone, the variation of texture seemed to be variety-dependent. Overall the textures measured for the nine tissue zones were highly correlated, indicative of the major differentiation between soft and firm fruits. However distinct heterogeneity patterns could be observed on axes 2 and 3 of a principal component analysis carried out on the textures of the nine zones. The effect of thinning on fruit firmness appeared variety-dependent. Tissue firmness of the raw apricots assessed by penetrometry explained about two-thirds of the variability of firmness of cooked apricots, versus only 40% for the compression test. High correlations between texture after cooking and prior to cooking were found for four (external equatorial, external pistil, median equatorial and median pistil) out of the nine tissue zones.     

截面畸变对小半径热煨弯管性能的影响

小半径热煨弯管在生产过程中会出现截面趋于椭圆、壁厚减薄或增厚等各种截面畸变,上述缺陷有可能会降低管道的承载能力。为了研究截面畸变对小半径热煨弯管性能的影响,以不同组合工艺参数煨制小半径热煨3D(D表示管道直径)弯管,通过截面几何尺寸分析、畸变分析、理化性能试验、微观组织分析等方法综合分析了3D弯管和常规5D弯管截面畸变、组织性能情况及其关联性。研究结果表明:(1)3D弯管增厚率和减薄率约是5D弯管的2倍,3D弯管圆度是5D弯管的2~4倍;(2)3D弯管截面畸变显著,各部位加热温度差异较大,使得组织形态或含量有所不同,导致3D弯管外弧侧、内弧侧及中性区等各部位力学性能数值分布较为离散;(3)多数弯管内弧侧强度都达不到标准的要求,强度大小顺序分别为弯管外弧侧、弯管中性区和弯管内弧侧,夏比冲击韧性大小顺序与强度恰好相反;(4)随着圆度的增加,内、外弧侧强度呈下降趋势,随着增厚率的增加,内弧侧强度呈下降趋势,随着减薄率的增加,外弧侧强度呈上升趋势。     

基于数学形态学的联机手写字符识别去噪方法

手写输入时由于笔尖抖动等原因产生了大量噪声,有效地去除噪声是手写识别的前提和关键。根据联机手写识别中手写体字符形态的特性,分析了手写时由于各种原因而产生的噪声,运用数学形态学中膨胀、腐蚀、细化等基本运算,提出了一种将数学形态学应用于联机手写识别预处理的方法,该方法可以有效地消除大量的冗余信息。测试结果表明,提出的方法可行,具有很好的鲁棒性,可以配合其他方案应用于各种联机手写字符识别中。     

距离变换细化算法的改进及实现

本文以Ｃ．Ｗａｙｎｅ Ｎｉｂｌａｃｋ的距离变换骨架抽取法为基础，讨论了如何改进其基本算法以提高执行效率，由距离变换法得到的骨架能很好地满足连通保持性、重构性，但对于细的程度而言，只能达到两像素宽。本文提出了串行的细化检测算法使骨架达到单像素宽的要求。     

工程扫描图象的骨架提取和识别技术综述

目前有很多工程图纸处理和识别算法,比如基于细化的识别算法,基于结构的识别算法,正交方向搜索（ＯｒｔｈｏｇｏｎａｌＺｉｇ－Ｚａｇ）识别算法,轮廓匹配识别算法等,结合自己的工作对当代典型识别算法进行了分析和探讨并提出了自己的新的观点和方法。     

二值图象处理算法的硬件实现

该文介绍了一种高速多功能工值图象处理系统,该系统用硬件电路实现收缩、膨胀、轮廓跟踪和细化这几种二值图象处理方法。系统采用了全硬件逻辑结构,没有CPU参与运算,采用独立时钟,在每个时钟周期内可并行处理若干字节,大大提高了处理速度。该文给出的二值图象处理算法的硬件实现方法不仅使二值图象处理速度发生质的飞跃,而且为图象处理方法的实用化提供了一种新思路。     

含金属离子的聚硅酸用作MMH－膨润土泥浆稀释剂的室内研究

通过测定泥浆体系的电性能、流变性、抑制性和粒度分布，研究了含金属离子的聚硅酸（ＰＳＡＭ）对混合金属氢氧化物（ＭＭＩＩ）－膨润土泥浆的稀释作用。结果表明，ＰＳＡＭ对ＭＭＩＩ－膨润土泥浆的稀释能力强，能提高该泥浆体系的抑制性。ＰＳＡＭ的稀释机理为：ＰＳＡＭ产生的带正电二氧化硅颗粒通过静电作用吸附到ＭＭＩＩ－粘土网状结构的粘土颗粒表面，破坏网状结构，释放出大量自由水。     

结构光图象的智能细化与补断算法——在人头像三维表面重建中的应用

简要地介绍了三维彩色扫描系统的工作原理；对人的面部特征及其反射特性做了详细地分析；提出了一个细化与补断的智能算法，该算法具有智能性、容错性、扩展性和综合性；文末给出了实验结果及误差分析。     

Image Thinning by Neural Networks

An image thinning technique using a neural network is proposed. Using different activation functions at different layers, the proposed neural network removes the boundary pixels from four directions in such a manner that the general configuration of the input pattern is unaltered and the connectivity is preserved. The resulting object, called a skeleton, provides an abstraction of the global shape of the object. The skeleton is often useful for geometrical and structural analysis of the object. The output skeleton here satisfies the basic properties of a skeleton, namely connectivity and unit thickness. The proposed method is experimentally found to be more efficient in terms of better medial axis representation and robustness to boundary noise over a few existing algorithms. ID="A1" Correspondence and offprint requests to: Dr A. Datta, Indian Statistical Institute, 203 B. T. Road, Calcutta – 700 108, India. Email: amitava@isical.ac.in