连续小波变换VLSI实现综述

小波变换是信号处理、图像压缩和模式识别等诸多领域中一个非常有效的数学分析工具。然而，实时小波变换计算量大，需要专用硬件来实现。连续小波变换的VLSI实现在处理速度、功耗及适用频率范围方面部具有较明显的优势，且实现方法灵活。本文对近年来有关该领域的研究情况作了综合评述，讨论了其中存在的问题，并指出了今后的若干发展方向，特别是瞬时缩展电路技术是实现低电压低功耗小波变换芯片的重要途经之一。     

一种空间自适应小波门限去噪算法

提出了一种空间自适应小波门限去噪算法,该算法在小波域对含噪小波系数做两次自适应去噪,两次自适应门限分别基于最大似然(ML)方差估计和最大后验概率(MAP)方差估计.仿真结果表明,该算法与其它自适应门限去噪算法相比,去噪后的图象具有更高的峰值信噪比(PSNR).     

Linked influence of pH and cations on fatty-acid monolayer integrity related to high-quality Langmuir-Blodgett films

This study shows the connection between the morphological structure of transferred films and the chemical composition of the monolayer before transfer. The stability of a behenic acid monolayer depends on the linked influence of the type of cation and of the pH value in the aqueous subphase. The stability of the monolayer is assessed by the expansion of the solid-packed state and by the relaxation time. Its integrity is characterized by the number of crystal defects which appear in transferred Langmuir-Blodgett (LB) films as seen through Nomarski microscope observations. Both stability and integrity are greatly improved when Cd²⁺ or Mn²⁺are added to the subphase at pH 5.75 and 6 respectively. In these conditions, the transfer is very efficient and the LB films thus obtained are of very high quality. The pH values of the subphase at which the molecules of behenic acid are transformed into bivalent salts differ significantly according to the nature of the cation involved. Comparing infrared spectra of the LB films, it appeared that the relative amount of acid/salt found in the monolayer was practically the same with a subphase containing either Cd²⁺ at pH 5.75 or Mn²⁺ at pH 6. This suggests that the ratio of acidic and salt forms would be a key parameter for obtaining high-quality LB films.     

Perceptual primitives from an extended 4D Hough transform

Directional features extracted from Gabor wavelets responses were used to train a structure of self-organising maps, thus classifying each pixel in the image within a neuron-map. Resulting directional primitives were grouped into perceptual primitives introducing an extended 4D Hough transform to group pixels with similar directional features. These can then be used as perceptual primitives to detect salient structures. The proposed method has independently fixed parameters that do not need to be tuned for different kind or quality of images. We present results in application to noisy FLIR images and show that line primitives for complex structures, such as bridges, or simple structures, such as runways, can be found by this approach. We compare and demonstrate the quality of our results with those obtained through a parameter-dependent traditional Canny edge detector and Hough line finding process.     

Use of pyrogenic silicas for petroleum oil polar fraction characterisation. Fourier transform infrared spectroscopy and microelectrophoresis studies

In the power transformer, the presence of polar or charged species in the insulating oil can cause failure and electric discharges. Solid substrates such as silica can be used to extract the polar species and to refine the oil in order to prevent future failure in the power transformer. However, the use of silica for petroleum oil separation and refining will depend on the silica characteristics such as surface charge, surface composition, specific surface area and particle size.Various pyrogenic silicas having various specific surface areas (49-200 m² g⁻¹) and particle sizes (207-500 nm) were used to extract the polar fractions from the neat transformer insulating oils (a new, NO, and used, UO2, oils). The oil covered silica samples were investigated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy in the range 4000-600 cm⁻¹. The bare silica surfaces present two main hydroxyl components, a sharper peak at 3745 cm⁻¹, I₃₇₄₅, due to isolated silanols and a second broad, which spreads over 3745-3000 cm⁻¹, I_3745-3000, due to H-bonded silanols. The relative intensities of the two components, I₃₇₄₅/I_3745-3000, varied for the bare and the oil covered silicas depending on the solid surface characteristics. The adsorption of the NO polar fraction onto silica leads to strong reduction in intensity of the sharper peak in favour of the broad one. However, the adsorption of the UO2 polar fraction onto silica leads in all cases to the decrease in the intensity of the both silica OH components. Further, the UO2 adsorption on the silica leads to the apparition of a broad peak at low frequency in the region 3250-3300 cm⁻¹ which, is due to the associated phenolic groups of UO2 oil polar fraction. The analysis of the DRIFT spectra for various samples indicates that the oil polar fraction resembles to asphaltenes compounds.The microelectrophoresis method used to investigate the surface charge at the water/oil polar fraction covered silica interface, indicates negatively charged particles. Further, the negative charge increased with the pH, as resulting from the increase of the ionisation and/or the amount of the oil polar carboxylic and phenolic groups. The oil polar fraction, i.e. the asphaltene components, in contact with both the silica surface and water at high pH values rearrange, due to their amphiphilic character.Finally, the use of the silica substrates seems to be suited to extract and analyse polar species present in petroleum oil. A correlation is found between the nature of the oil, its functionalities, and the magnitude of its zeta potential value at the water/oil covered silica interface.     

Autolisp在开发V画面体视图自生成系统中的应用

介绍了近年来体视投影技术的应用及发展，并提出了用AutoCAD的内嵌开发工具Autolisp语言结合Visualisp中的对话框控制语言DCL来开发体视图自动生成系统的新思路．根据V画面体视投影原理，推导出了V画面体视变换矩阵．给出了该系统的程序流程框图及相应的功能模块．并将该系统的界面和基本功能进行了展示，从而为体视自生成技术的研究开辟了新的道路．     

基于小波的彩色序列图象压缩编码

此文提出了一种基于小波变换的运动估计算法，时间复杂度比常规算法降低了一个数量级，同时在估值精度上可与常规算法媲美。利用更佳频率分辨率小波分解处理运动补偿余量误差善了复现图象质量。实验结果表明，该算法在高压缩比情况下图象复现质量显著优于ＭＰＥＧ－２，具有广阔的应用前景。     

Instability of zeolite Y supported cobalt sulfide hydrotreating catalysts in the absence of H2S

Ion exchanged CoNaY was sulfided at 473 and 673 K and subsequently heated in He at 673 and 773 K. The resulting samples were characterized by means of overall sulfur analysis, temperature programmed Ar treatment and Fourier transform infrared spectroscopy. It was shown that during He flushing at sufficiently high temperature a protolysis reaction occurs resulting in the decomposition of Co sulfide into Co²⁺ ions and H₂S.     

叠后记录Radon变换压制干扰方法

在叠加剖面中,下伏反射界面的反射信号同相轴呈连续的或带有限个间断点的连续层状图像,各种干扰则呈无规则的图像。对此剖面的振幅数据进行 Radon 变换,即分别向各方向进行投影,层状图像将产生一定形状的光滑曲线,而干扰数据将相互抵消,其剩余数据呈高斯分布。在Radon 域中通过平滑等方法消除这些呈高斯分布的噪声数据,再经 Radon 逆变换,便可获得信噪比较高的叠加剖面。其结果不改变原叠加剖面的分辨率和信号波形特征。理论与实际剖面的处理结果表明,这是一种良好的压制干扰方法。