Studies of lithium and sodium complexation by silicon podand solvents

The complex formation of lithium and sodium ions with silicon podand solvents: phenyl-tris(1,4-dioxapentyl) silane (PhSi23) and ethyl-tris(1,4-dioxapentyl) silane (EtSi23) has been studied by FTIR, ¹H-, ¹³C-, ⁷Li- and ²³Na NMR. The far FTIR spectra show that the Li⁺ cations fluctuate very fast whereas Na⁺ cations are still localised between the oxygen atoms of the oxaalkyl chains. The ⁷Li NMR spectra prove that one Li⁺ cation can be coordinated not only by one but also two silicon podand molecules. The concentration dependence of the molar conductivity of LiClO₄ in the podand solvents indicates charge transfer between ion clusters.     

Microwave-assisted extraction of high-molecular-weight hemicelluloses from spruce wood

Microwave-assisted extraction (MAE) at atmospheric pressure has been demonstrated as an efficient technology for the extraction of polymeric hemicelluloses from spruce sawdust. This technology was shown to be more efficient than conventional extraction. MAE leads to a high solubilization of wood and a selective extraction of hemicellulose polymers with high molecular weights. To optimize MAE, different treatment powers (125–573 W) of presoaked spruce sawdust in water and 1 M sodium hydroxide solution for a period of 60 min were tested. The yield of hemicellulose extraction increased with the microwave power in both mediums, but with a clear advantage for presoaked samples in basic medium. The characterization of extracted hemicelluloses has shown high extraction selectivity depending on the medium of impregnation of sawdust before MAE: High-molecular-mass acetylated galactoglucomannans (M_w ∼ 41 kDa) were isolated after presoaking in water and higher molecular mass arabinoglucoronoxylans (M_w ∼ 66 kDa) in basic medium.     

Surface composition of alloys

The practical importance of alloy surfaces in catalysis, corrosion andother aspects of materials performance is widely recognized. What is needed now is sufficient knowledge of the relationship between externally controllable factors — alloy composition, temperature, environment — and surface properties — composition, structure, chemical activity — to control materials performance in these applications. Our purpose here is to review progress in determining and predicting the relationship between one surface property, composition, and certain externally controllable variables: overall composition, temperature, environment and physical form.We find that theoretical treatments of metal alloy surface composition now include essentially all significant physical effects and can predict values for most parameters of interest. Though improvements are still possible, the accuracy of predictions is more often limited by uncertainties or absence of the basic data for the calculations (e.g., thermochemical values) than by the models themselves.Alloy surface composition can now be measured well. The first monolayercomposition of large alloy slabs can be determined quantitatively over a wide temperature range in ultra-high vacuum. Difficulties with specimens of practical interest still challenge experimentalists. Among these are supported catalysts, surfaces under chemisorbed layers and composition of layers below the first. Significant progress is being made and we expect the next few years will see success.     

Comparison of 2D S-Transform Profilometry and 2D Windowed Fourier Transform Profilometry

Both two-dimensional (2D) Windowed Fourier Transform and 2D S Transform are popular time–frequency analysis tools for processing signals. But fewer articles reported the application of 2D S Transform in Fringe pattern analysis. This paper studies the 2D S Transform and compares it with 2D Windowed Fourier Transform. The phase calculation formula based on the 2D Windowed Fourier Transform “ridge” coefficients and 2D S Transform “ridge” coefficients are deduced respectively. A comparison between them is carried out to show their own characteristic in fringe patterns analysis based on the structured-light illumination. It verifies that the 3D reconstruction result of 2D ST is better than that of 2D WFT because of the employment of the adjusted windows by frequency parameters.     

Girsanov变换下的Malliavin计算与算子关系

本文讨论了Ｇｉｒｓａｎｏｖ 变换下两个Ｇａｕｓｓ概率空间中Ｍａｌｌｉａｖｉｎ 计算及算子之间的关系     

Determination of an acceptable level of spectral data compression by Discrete Wavelet Transforms

Today, due to the ever increasing amount of data generated by analytical instruments, good compression methods are desired to keep computation time acceptable. The lower the volume and noise content of data, the easier it becomes to investigate and interpret the modeling results. Discrete Wavelet Transform (DWT) is an effective data compression and noise suppression tool. Compression can be performed at different levels, in each, the size of signal part of the data reduces to half the size. This work includes an approach for determining an acceptable level of compression of data where the aim is to achieve minimal loss of information and no significant change in the structure of data, which could mean, e.g. no loss in predictive ability or the effective rank of the data-set. The method is based on estimation of the Singular Values (SVs) from a data matrix and the Singular Values at each level of compression followed by the application of Median Absolute Deviation (MAD) of the correlation between original SVs and compression SVs as a simple statistical test for the determination of the optimum level of compression. We illustrate the method using FT-Raman data from aqueous solutions of three sugars (glucose, trehalose and sucrose) and NMR data from mixtures of three alcohols. A sudden change in prediction error sum of square plots from Partial Least Squares (PLS) modeling confirms the results from MAD statistics.     

A (C o)-group generated by the lévy laplacian

In this paper, we discuss a (C _o)-group generated by the Lévy Laplacian acting on a domain in the space of Hida distributions. We also give a relationship between the analytic extension of this (C _o)-group and the adjoint operator of an infinite dimensional Fourier-Mehler transform introduced by H.- H. Kuo     

Walsh变换对鱼类特征识别的研究*

鱼种的快速识别是渔业资源评估乃至海洋生态系统监测重要组成部分。与传统的拖网捕捞等方法相比,声学方法具有快速有效、调查区域广、不损坏生物资源、可持续观察等优点。鱼类的声学识别方法主要是基于鱼类回波信号特征的识别, 鱼体形状及组成结构的复杂多样导致其回波信号非常复杂,因此利用简单的回波包络或能量特征识别鱼类效果往往不能令人满意。本文提出一种基于Walsh 变换的鱼类回波识别方法。试验获取鲫鱼、 嘎鱼、武昌鱼的回波信号,处理过程中分别提取三种鱼类回波包络信号的Walsh谱作为识别特征量,并利用BP神经网络分类器对其进行了分类。结果表明利用回波的Walsh谱可以成功识别不同形状的鱼类,其中对武昌鱼的识别正确率达90%以上。     

Transforms of pseudo-Boolean random variables

As in earlier works, we consider {0,1}ⁿ as a sample space with a probability measure on it, thus making pseudo-Boolean functions into random variables. Under the assumption that the coordinate random variables are independent, we show it is very easy to give an orthonormal basis for the space of pseudo-Boolean random variables of degree at most k. We use this orthonormal basis to find the transform of a given pseudo-Boolean random variable and to answer various least squares minimization questions.     

Valence band XPS and FT-IR evaluation of thermal degradation of HVAF thermally sprayed PEEK coatings

Coatings of PEEK (poly-ether-ether-ketone) have been produced on stainless steel 304 using the High Velocity Air Fuel (HVAF) thermal spray technique. These coatings were produced using 50 and 100 mm nozzle lengths with 200, 300 and 400 mm gun to substrate distances. The thermal degradation of the PEEK during the production of the coatings was assessed with valence band X-ray Photoelectron Spectroscopy (XPS) and attenuated total reflectance Fourier Transform Infrared Spectroscopy (ATR FT-IR). Valence band XPS shows that in general there is minimal degradation of the PEEK during the HVAF thermal spraying process. The FT-IR results show that at the 200 mm gun to substrate (standoff) distance for both nozzle lengths there is more surface degradation of the PEEK coating than at the longer gun to substrate distances. Specifically absorption bands appeared at 2918 and 2850 cm⁻¹, which correspond to alkane -CH₂- asymmetric stretching modes. The reduction of the 1250 cm⁻¹ band as compared with the 1220 cm⁻¹ band, both representing the stretching modes of the ether bonds in PEEK suggests that the degradation occurs at only one of the ether bonds. The phenyl C-H vibration at 673 cm⁻¹ was split for coatings produced at gun-substrate distance of 200 and 300 mm. This indicates a structural change in the phenyl ring possibly indicating a change in the extent of crystallinity of the PEEK polymer.