分数阶神经型脉冲振荡器

为了使仿生神经振荡器能比较正确地模仿实际生物神经冲动的波形特征,在分数阶微分R-L定义和三角波函数的基础上构造出分数阶神经振荡器,并用该振荡器仿真各种人体活动的生物神经信号.实验表明该神经振荡器是一种可根据实际生物神经特性调整参数的分数维神经振荡器,其输出波形为非方波或非矩形波;能很好地模拟声带外展肌-环杓后肌神经电脉冲信号、动作电位AP、神经元兴奋和神经元仰制等神经信号,可望为未来神经功能修复提供一种技术支撑.证明了生物神经冲动的内在本质规律不是整数维的,可能和分数维有关.     

Microstructure of retrograded starch: Quantification from lacunarity analysis of SEM micrographs

Three starches from different botanical sources were stored at different temperatures during four days in order to monitor their retrogradation by means of fractal analysis. To this end, digital images were obtained by sample sectioning and scanning electron microscopy (SEM). Fractal dimension estimation and lacunarity analysis were performed over SEM micrographs, showing that (i) as already reported in the recent literature, fractal dimension is directly related to gelatinization temperature, and (ii) the storage temperature and the starch botanical source affect strongly the heterogeneity (quantified in terms of lacunarity) of retrograded starches. Overall, the results in this work yield important insight on retrogradation, providing guidelines for predicting growth models for retrogradation.     

Impact of Aggregate Size and Structure on Biosolids Settleability

Settling is an important solid–liquid separation process in wastewater treatment. While solids concentration is an important factor influencing settling velocity of particles, other solids characteristics including particle size, shape, and structure also play an important role in settling rate. The “compactness” of bacterial aggregates in particular is recognized to exert a great influence on solid phase dynamic behavior since it has a substantial effect on fluid flow through the aggregate, which, in turn, affects the particles buoyancy. With the recognition that biosolids structure can be described by fractal methods, we now have a convenient means of parameterizing aggregate “compactness.” In this article, we examine the fractal nature of bacterial aggregates (which are the main component of the solids in wastewater treatment processes) using small angle light-scattering methods and assess the impact of aggregate compactness (as described by fractal dimension) on settling velocity of both single aggregates and large aggregate clusters. The results indicate that settling velocity is strongly dependent on both size and aggregate structure, with the larger and less compact flocs settling more quickly as a result of the significant extent of flow through the bacterial assemblages.     

Image analysis of structural changes in dough during baking

The bakery market is developing new technologies based on dough partial baking and the study of the changes that dough undergoes through the whole baking process could help in the selection of baking times. The aim of this work was to study the changes of dough structure and their relationship with dough temperature, mass loss and loaf height during baking by applying image analysis techniques. Results showed that during baking, bubble coalescence was presented, observing a maximum at the first stages of baking (<250 s). This phenomenon was associated with an increment in dough height without a significant change in dough centre temperature. Fractal dimension of texture of crumb, fractal dimension of contour of cells and crumb grain features were useful indicators of coalescence as well as to distinguish the baking time needed for crumb features remain invariable.     

Face recognition based on wavelet-curvelet-fractal technique

In this paper, a novel face recognition method, named as wavelet-curvelet-fractal technique, is proposed. Based on the similarities embedded in the images, we propose to utilize the wavelet-curvelet-fractal technique to extract facial features. Thus we have the wavelet’s details in diagonal, vertical, and horizontal directions, and the eight curvelet details at different angles. Then we adopt the Euclidean minimum distance classifier to recognize different faces. Extensive comparison tests on different data sets are carried out, and higher recognition rate is obtained by the proposed technique.     

二维分形相位屏的衍射

本文引入二维分形函数描述媒质折射率的起伏，研究分形相位屏对平面波的衍射问题，运用广义菲涅尔－惠更斯原理，我们获得了通过二维分形相位屏后在Ｆｒｅｓｎａｅｌ区和Ｆｒａｎｈｏｆｅｒ区的衍射场及平均衍射强度分布，结果表明，分维及有关分形描述量控制着衍射强度分布。     

FRACTAL BLOCK CODING IN RESIDUE DOMAIN

A new block-based fractal image coding algorithm called Fractal Block Coding in Residue Domain (FBCRD) is proposed. In basic Fractal Block Coding (FBC) algorithm, each block (called range block) is encoded by an affine mapping from a domain block within the same image to itself. The decoder uses the parameters of these mappings to synthesize the reconstructed image through an iterative procedure. FBCRD is a modification of basic FBC. In FBCRD, range blocks and domain blocks are all residue blocks subtracted from their block means and both the parameters of affine mappings and block means are coded. This modification leads to fewer iterations at the decoder. An optimized decoding strategy is also introduced which reduces total decoding time by more than half of that of basic FBC. This improvement is favorable for real time implementation of fractal image compression. Supported in Part by the Defence Preresearch Foundation, the National Science Foundation of Guangdong Prooince and the National “Chinbing” Project     

硅片缺陷粒径分布的分形特征及动力学模型

本文研究硅片上与光刻工艺相关的尘粒的粒径分布，分析缺陷粒径分布的分形特征，利用缺陷粒径的分布函数得到缺陷粒径体系的分维数，建立缺陷粒径分布的分形模型，同时给出此模型所得参数的物理意义。最后，本文对缺陷粒径变化过程给出了新的动力学模型，并对此进行分析和讨论。揭示光刻缺陷的粒径分布及其动力学成因，为集成电路可制造性设计及功能成品率的精细表征开辟了一条新径。     

一维离散信号的统计及PIFS混合表示

许多系统的输出是一维离散信号，本文一般性地研究了该类信号的特点，给出了一种有效的压缩表示方法，在压缩比为１０－２０倍时，恢复信号的信噪比仍然是较高的。