基于球傅里叶变换的声源三维空间定位

声源的空间方位信息是重建听觉环境重要的因素之一。本文研究了球形麦克风阵列(SMA)在声源空间定位的方法。针对球麦克风的设计,提出了一种等距离分布方法。本文从声学原理出发,利用球傅里叶变换将声场变换到波矢-频率(k-ω)域,推导出基于球傅里叶变换的声源定位算法,从而获取其声源方位信息得到各声源的分布情况。声压经虚拟仪器采集后,进行了数值仿真。结果表明,该算法利用球谐波的正交性,可以减少运算量,能获得多声源的准确定位,并且阵列所需的麦克风数量远远小于其他分布。

基于空间变换技术的脉冲激光声信号检测

针对目前脉冲激光声信号检测方法极易受到环境噪声的影响,导致检测精确度不理想的问题。提出基于空间变换技术的脉冲激光声信号检测方法。首先,采用小波阈值法去除脉冲激光声信号中的噪声;其次,利用球傅里叶空间变换技术对声信号中的声源展开定位,获取声信号的准确位置;最后,分别提取声信号中的比值特征、比重特征、频率特征三种参数,在此基础上通过SVM算法对其展开分类识别,以此实现脉冲激光声信号的有效检测。实验结果表明,所提方法的声信号检测精度超过96%。

Geochemistry of Kasnau-Matasukh lignites, Nagaur Basin, Rajasthan （India）

The distribution and verticals variation of geochemical components in the Kasnau-Matasukh lignites of Nagaur Basin, Rajasthan, were investigated using microscopy, proximate and ultimate analyses, Rock-Eval Pyrolysis, X-ray diffraction and Fourier Transform Infrared analyses, and major/minor/trace element determination. The relationship of elements with ash content and with macerals have also been discussed. These lignites are stratified, black, dominantly composed of huminite group macerals with subordinated amounts of liptinite and inertinite groups. They are classified as type-III kerogen and are mainly gas prone in nature. The concentration （in vol%） of mineral matter is seen to increase towards upper part of seam and so is the concentration （in wt%） of the volatile matter, elemental carbon and sulphur. The common minerals present in these lignitesare mixed clay layer, chlorite, and quartz as identified by X-ray diffraction study. Compared with world average in brown coal, the bulk concentration of Cu is anomalously high in most of the samples while Cd is 2-3 times high and Zn is high in one band. Based on interrelationship, different pyrite forms are noticed to have different preferential enrichment of various elements. The concentration of disseminated pyrite is more than the other pyrite forms and is followed by discrete pyrite grains and massive pyrite.

Alginate-Casein Microspheres as Bioactive Vehicles for Nutrients

The aim of this work was to develop an alginate-casein composite microsphere as a bioaetive vehicle for oral administration of nutrients by a simple extrusion dripping method. Riboflavin was selected as a model drug, and the microencapsulation efficiency was raised to 97.94% after optimizing the preparation conditions by response surface methodology. In vitro release studies showed that riboflavin was released completely from alginate-casein microspheres in simulated intestinal fluids. Meanwhile, the morphology, structure and interaction between alginate and casein were characterized by scanning electron microscopy （SEM） and Fourier transform infrared （FTIR） spectra.

Two Organic Phase Suspension Polymerization for Novel Hypercrosslinked Resin Bead by Polycondensation of CMB

The suspension polymerization with two organic phases was adopted to prepare spherical hyper- crosslinked resin by self-polycondensation of 4,4＇-bis-（chloromethyl）- 1, 1＇-biphenyl （CMB）. The chemical structure,morphology and pore characteristics of the novel spherical resin were characterized with Fourier transform infrared spectroscopy （FTIR）, micrograph and Brunauer-Emmett-Teller （BET）. It is found that the suspension system and stirring speed impose a great influence upon the regularity and size distribution of hypercrosslinked beads. To prepare CMB resin beads with diameter of about 300 μm, the optimal condition is as follows： stirring speed 300 r·min^-1, and the volume ratio of the two organic phases （nitrobenzene/dimethyl silicon oil） 1 ： 5. After the self-polycondensation and sqccedent post-crosslinking of CMB monomer, the spherical adsorbent presents high spec^al surface area （1190 m^2· g^-1） and abundant pore^volume （0.714 cm^3· g^-1）, and could be potentially applied qn the adsorption of various organic molecules and synthesis of porous ion exchanger.

Preparation and Visible-Light Photocatalytic Activity of FeTPP-Cr-TiO2 Microspheres

Tetraphenyl-porphyrin iron （FeTPP） was chosen to sensitize Cr doped TiO2 （Cr-TiO2） nanoparticles, a novel multimodified photocatalyst FeTPP-Cr-TiO2 with excellent visible- light photocatalytic activity was successfully synthesized. The FeTPP-Cr-TiO2 microspheres were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra and N2 adsorption-desorption isotherms. The photocatalytic activity of FeTPP-Cr-TiO2 was evaluated by degradations of methylene blue in aqueous solution under irradiation with Xe lamp （150 W）. The results showed that the FeTPP-Cr-TiO2 multimodified photocatalyst was anatase phase with high specific surface area （74.7 m^2/g）, and exhibited higher photocatalytic degradation efficiency than Cr-TiO2 and FeTPP-TiO2. The photocatalytic degradations of three quinolone antibiotics （lomefioxacin, norfioxacin, and ofioxacin） were further estimated for the feasibility of practical application of catalyst in wastewater treatment. It is desirable that photodegradation of antibiotics with FeTPP-Cr-TiO2 achieved pretty high degradation rates and all followed the pseudo first-order reaction model, and the rate constants k of 3.02×10^-2, 2.81×10^-2, and 3.86×10^-2 min-1 and the half-lifes t1/2 of 22.9, 24.6, and 17.9 min were achieved respectively.

Facile carbonaceous microsphere templated synthesis of Co3O4 hollow spheres and their electrochemical performance in supercapacitors

Co3O4 hollow spheres assembled from nanoparticles have been successfully synthesized by a one-pot hydrothermal carbonization and calcination method. In this method, carbon spheres obtained through hydrothermal carbonization at a low temperature of 140 ℃ are used as sacrificial templates. The carbonization process was monitored by Fourier transform infrared spectroscopy （FT-IR） and Raman spectroscopy. Both the carbon sphere soft templates and the NH3 released from hexamethylenetetramine play key roles in the formation of these novel hollow structures. The formation of the Co3O4 hollow spheres using hydrothermal carbon spheres as templates can be attributed to the synergetic effect of metal ion adsorption and heterogeneous nucleation of Co（OH）2, which is different from the traditional adsorption theory. The as-obtained Co3O4 hollow microspheres exhibit excellent cycling performance and good rate capacity when used as electrode materials in supercapacitors, which can be attributed to the small particle size of Co3O4 and the sufficient space available to interact with the electrolytes. This facile strategy may be extended to synthesize other metal oxide hollow spheres, which may find application in sensors and catalysts due to their unique structural features.

Facile preparation of L-ascorbic acid-stabilized copper-chitosan nanocomposites with high stability and antimicrobial properties

Highly stable dispersions of nanosized copper （Cu） particles with an average size of （2.6 ± 0.5） nm were synthesized by in situ reduction of Cu（II） to immobilize Cu nanoparticles on the amino-enriched surface of chitosan （CTS）. The synthetic process and stability of the L-ascorbic acid-stabilized Cu-CTS nanocomposites were investigated by X-ray photoelectron spectroscopy and Fourier transform Infrared spectroscopy. The antimicrobial efficiency and potency of the Cu-CTS nanocomposites were studied. The Cu-CTS nanocomposites were found to exhibit a broad antimicrobial spectrum and high antimicrobial activity against Gram-positive bacterial pathogen Staphylococcus aureus and fungal pathogen Monilia albican. The minimum inhibitory concentration of the Cu-CTS nanocomposites toward S. aureus was found to be 6.4 μg mL^-1, much lower than those reported in the literature. Furthermore, the Cu-CTS nanocomposites were stable and main- tained good disinfection potential even after 90-day shelf-time under ambient conditions.

Compactness of the commutators of homogeneous singular integral operators

Let TΩ be the singular integral operator with kernel Ω（x）/｜x｜n where is homogeneous of degree zero, integrable and has mean value zero on the unit sphere Sn-1. In this paper, by Fourier transform estimates, Littlewood-Paley theory and approximation, the authors prove that if Ω∈（lnL）2 （Sn- 1）, then the commutator generated by TΩ and CMO（Rn） function, and the corresponding discrete maximal operator, are compact on LP（Rn, ｜s｜γp） for p∈ （1, ∞） and γp ∈ （-1, p-l）