一种基于小波变换结合反向迭代修正的VQ图象压缩编码方法

将反向迭代法引入对ＶＱ（矢量量化）编码误差进行修正，从而使建立在小波变换基础上的ＶＱ编码方法的重建图象质量得到改善，使信噪比（ＳＮＲ）提高了３～８ｄＢ。对于与训练集内样本相差较大的图象在压缩比相同的条件下，改善重建图象的效果尤为明显。     

Fractal model to predict the crack roughness effect on the local bending compliance of circular shafts

In this paper the local compliance due to a transverse fractal crack in a shaft under pure bending is investigated. In a fractal crack, the surface is considered irregular and it is characterized by the presence of nonuniformities at different scales. Therefore, the crack surface can be modeled as a fractal surface with fractal dimension D. An analytical model for the compliance coefficient is presented with and without the effect of the surface roughness. The results obtained shows that as the dimension of the fractal surface increases the compliance increases as well. It is shown that this behavior conforms well with existing experimental results.     

a-Si:H簿膜的晶化与分形结构的形成

利用透射电子显微镜(TEM)观测a-Si:H 薄膜在不同温度下生长的分形结构。实验方法为原位动态技术。对分形结构的TEM形貌像用Sandbox方法计算了其分形维数。450℃时,形成具有类似分叉状的分形结构,分形线数d_f=1.69;800℃时,形成岛状分形结构,分形维数d_f=1.76。实验结果表明,分形结构的形成与薄膜物性的变化相联系。文中还对分形结构与a =Si:H 薄膜晶化的关系进行了讨论。     

Floc rupture and turbulence: a framework for analysis

The paper focuses on the physical character of flocs. This is developed through analysis of the impact of hydrodynamic stress on floc size. Theory is developed on the basis of an energy criterion which balances the turbulent kinetic energy against the energy expenditure associated with rupture. For turbulence, the kinetic energy per unit volume is moulded by the velocity scale (νε)^1/4 and the d/η ratio in which ν, ε, η refer to the kinematic viscosity, the rate of energy dissipation per unit mass and the Kolmogorov length, respectively. The distance scale, d, is equivalent to the maximum floc size. In its most rudimentary form, floc structure is based on the model S∝k?/d³ in which k is the number of bonds broken and ? the potential energy expenditure per bond broken. With appropriate development, this transforms to S=S₀(d/d₀)^D−3 in which d₀ is the primary particle size, D the fractal dimension, and S₀ is a scaling factor controlling the mechanical strength. From the energy criterion, analytical expressions are derived for d in the form d=γε^−m/2 in which γ and m are constants. Beside the proposal of models for S, a valuable advance is the development of rupture theory for the whole domain of d/η. Theory is examined using a number of published data sets in which there exists knowledge of parameters γ, m and D. The paper demonstrates how the model can be used as an analytical tool for dissecting the factors which control S₀. The theory establishes a framework which can be developed further, and applies to flows containing fractal aggregates in both industry and the natural environment.     

Strkuctured-light Image Compression Based on Fractal Theory

The method of fractal image compression is introduced which is applied to compress the line structured-light image.Based on the self-similarity of the structured-light image, we attain satisfactory compression ratio and higher peak signal-to-noise ratio (PSNR).The experimental results indicate that this method can achieve high performance.     

快速覆盖式分形压缩算法

提出了一种覆盖式分形压缩方法,并给出了相应快速搜索算法.该方法采用四连通扩充的方式,在给定误 差范围内,尽可能地合并规则Range分区,从而减少所需迭代变换的数目.为减少存储Range分区信息所需的字 节,在存储压缩映射时,根据Range分区多边形的边数调整存储顺序,对于那些复杂的Range分区,只记录其外接 矩形框信息.在解码时,采用一种覆盖式绘制方法,可以完全恢复原Range分区情形.通过对Lenna,图象的实验表 明,在恢复图象的信噪比为29.63dB时,可以达到41倍的压缩倍数.     

分形层次及码尺与分辨率的关系

提出了在分形研究中，用计算机进行图像分析时，分形层次和码尺与图像采样分辨率之间的关系。码尺的改变只能通过改变输入的分辨率，同时输入分辨率的选择要综合考虑分形自身的层次要求、输入方法以及测量的要求。给出了实验验证。     

富钴结壳截割粒度分布分形规律的研究

应用分形理论研究螺旋切削采集法截割富钴结壳粒度分布规律，结果表明，其粒度分布具有很好的分形结构，可以用分形维数定量描述。通过大量试验，初步测定截割破碎富钴结壳及其模拟料粒度分布的分形维数在2．4236～2．6112之间，提出了切削深度与粒度分布关系的回归模型，用于预测截割破碎富钴结壳的情况，对于深海采矿系统的设计具有重要意义。     

混沌理论在建筑设计中的应用

首先明确了混沌理论的含义,然后分析其理论来源及历史,之后从混沌理论内在随机性和初值的敏感性等的本质特征出发,简述在建筑与城市中的体现应用,最后简要指出其在建筑设计方面的意义。     

分形Packing算法与建筑设计

Packing是一定数量的单元体以叠 合规则聚集在一起的一种算法。Packing算法 与分形迭代结合不仅在空间优化中具有重要 作用,在建筑设计中也具有一定的运用潜力。 本文分析了箱型Packing、圆形Packing等不同 种类的分形Packing算法的特性,并结合设计 案例探讨了分形Packing算法在建筑设计中的 运用方式。