几种傅里叶子的深入比较研究

用于模式识别的傅里叶子主要有基于极半径函数、转角函数和曲率函数等三种方法 ,通过比较研究 ,找出一种运算简便且精度高的傅里叶子。对不同的图形用三种方法分别计算出原函数和傅里叶频谱 ,然后从大到小依次选取k个 (k =1,2 ,… ,N)傅里叶系数进行反变换 ,计算出反变换函数与原函数之间存在的误差 ,根据误差随k变化的曲线判断三种方法的优劣。实验结果表明 ,基于极半径函数的傅里叶子最为理想。将它用于孢子的识别和计数 ,正确识别率达 99%。

光学滤波与频谱分析

O438.2 200303 1901有矩形脉冲内热源的平板中非傅里叶导热研究=Study ofnon-Fourier heat conduction subjected to a rectangular pulseheat sourcein a slab[刊,中]/胡学功(中科院工程热物理研究所.北京(100080)),刘登瀛…∥强激光与粒子束.—2002,14(2).—218-222对矩形激光短脉冲能量以内热源形式在有限厚绝热平板内释放所导致的非傅里叶导热过程进行了理论研究,利用格林函数与有限积分变换方法求得了绝热平板内温度分布的解析解,分析了平板内热波传播与反射行为以及温度场的特征。研究结果表明,温度波动频率取决于平板厚度和材料的热弛豫时间。

Fe-Mn/Al_2O_3 catalysts for low temperature selective catalytic reduction of NO with NH_3

A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction （SCR） of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactivation of the catalysts were studied. N2 adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, H2 temperature‐programmed reduction, NH3 temperature‐programmed desorption, X‐ray photoelectron spectroscopy （XPS）, thermal gravimetric analysis and Fourier transform infrared spectroscopy were used to character‐ize the catalysts. The 8Fe‐8Mn/Al2O3 catalyst gave 99%of NO conversion at 150？？ and more than 92.6%NO conversion was obtained in a wide low temperature range of 90–210？？. XPS analysis demonstrated that the Fe3＋was the main iron valence state on the catalyst surface and the addition of Mn increased the accumulation of Fe on the surface. The higher specific surface area, enhanced dispersion of amorphous Fe and Mn, improved reduction properties and surface acidity, lower binding energy, higher Mn4＋/Mn3＋ratio and more adsorbed oxygen species resulted in higher NO conversion for the 8Fe‐8Mn/Al2O3 catalyst. In addition, the SCR activity of the 8Fe‐8Mn/Al2O3 cata‐lyst was only slightly decreased in the presence of H2O and SO2, which indicated that the catalyst had better tolerance to H2O and SO2. The reaction temperature was crucial for the SO2 resistance of catalyst and the decrease of catalytic activity caused by SO2 was mainly due to the sulfate salts formed on the catalyst.

Shape retrieval using multi-level included angle functions-based Fourier descriptor

An effective shape signature namely multi-level included angle functions MIAFs is proposed to describe the hierarchy information ranging from global information to local variations of shape.Invariance to rotation translation and scaling are the intrinsic properties of the MIAFs.For each contour point the multi-level included angles are obtained based on the paired line segments derived from unequal-arc-length partitions of contour.And a Fourier descriptor derived from multi-level included angle functions MIAFD is presented for efficient shape retrieval.The proposed descriptor is evaluated with the standard performance evaluation method on three shape image databases the MPEG-7 database the Kimia-99 database and the Swedish leaf database. The experimental results of shape retrieval indicate that the MIAFD outperforms the existing Fourier descriptors and has low computational complexity.And the comparison of the MIAFD with other shape description methods also shows that the proposed descriptor has the highest precision at the same recall value which verifies its effectiveness.

Quantum Fourier Transform and Phase Estimation in Qudit System

The quantum Fourier transform and quantum phase estimation are the key components for many quantum algorithms, such as order-finding, factoring, and etc. In this article, the general procedure of quantum Fourier transform and phase estimation are investigated for high dimensional case run in a qudit quantum computer, and the quantum circuits are They can be seen as subroutines in a main program given.

Evaluation of removal of the size effect using data scaling and elliptic Fourier descriptors in otolith shape analysis, exemplified by the discrimination of two yellow croaker stocks along the Chinese coast

Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.

Fractional Fourier Transformation for Quantum Mechanical Wave Functions Studied by Virtue of IWOP Technique

Starting from the optical fractional Fourier transform (FFT) and using the technique of integration withinan ordered product of operators we establish a formalism of FFT for quantum mechanical wave functions. In doing so, theessence of FFT can be seen more clearly, and the FFT of some wave functions can be derived more directly and concisely.We also point out that different FFT integral kernels correspond to different quantum mechanical representations. Theyare generalized FFT. The relationship between the FFT and the rotated Wigner operator is studied by virtue of theWeyl ordered form of the Wigner operator.

Immobilization of Penicillin G Acylase on Magnetic Nanoparticles Modified by Ionic Liquids

Functionalized ionic liquids containing ethyoxyl groups were synthesized and immobilized on magnetic silica nanoparticles （MSNP） prepared by two steps, i.e., Fe304 synthesis and silica shell growth on the surface. This magnetic nanoparticle supported ionic liquid （MNP-IL） were applied in the immobilization of penicillin G acylase （PGA）. The MSNPs and MNP-ILs were characterized by themeans of Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and vibrating sample magnetometer （VSM）. The results showed that the average size of magnetic Fe304 nanoparticles and MSNPs were -10 and -90 nm, respectively. The saturation magnetizations of magnetic Fe304 nanoparticles and MNP-ILs were 63.7 and 26.9 A＇m2·kg^-1, respectively. The MNP-IL was successfully applied in the immobilization of PGA. The maximum amount of loaded enzyme-was about 209 mg·g^-1 （based on carder）, and the highest enzyme activity of immobilized PGA （based on ImPGA） was 261 U·g^-1. Both the amount of loaded enzyme and the activity of ImPGA are at the same leyel of or higher than that in previous reports. After 10 consecutive operat!ons, ImPGA still mainrained 62% of its initial activity, indicating the＇good recovery property of ImPGA activity. The ionic liquid modified magnetic particles integrate the magnetic properties of Fe304 and the structure-tunable properties of ionic liquids, and have extensive potential uses in protein immobilization and magnetic bioseparation. This work may open up a novel strategy to immobilize proteins by ionic liquids.

Convolution Theorem of Fractional Fourier Transformation Derived by Representation Transformation in Quantum Mechancis

Based on our previous paper (Commun.Theor.Phys.39 (2003) 417) we derive the convolution theoremof fractional Fourier transformation in the context of quantum mechanics,which seems a convenient and neat way.Generalization of this method to the complex fractional Fourier transformation case is also possible.

Linkage of Aromatic Ring Structures in Saturates, Aromatics, Resins and Asphaltenes Fractions of Vacuum Residues Determined by Collision-Induced Dissociation Technology

The linkage of aromatic ring structures in vacuum residues was important for the refining process. The Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) combined with collision-induced dissociation(CID) is a powerful method to characterize the molecular structure of petroleum fractions. In this work, model compounds with different aromatic ring structures were measured by CID FT-ICR MS. The cracking of the parent ions and the generated fragment ions were able to distinguish different linkage of the model compounds. Then, vacuum residues were separated into saturates, aromatics, resins and asphaltenes fractions(SARA), and each fraction was characterized by CID technology. According to the experimental results, the aromatic rings in saturates and aromatics fractions were mainly of the island-type structures, while the aromatic rings in resins and asphaltenes fractions had a significant amount of archipelago-type structures.

Recycling and Reuse of Ionic Liquid in Homogeneous Cellulose Acetylation

Molecular distillation was used to recover ionic liquid(IL) 1-allyl-3-methylimidazolium chloride(AmimCl) in homogeneous cellulose acetylation.The five factors that affect the separation efficiency of molecular distillation,namely,feed flow rate,distillation temperature,feed temperature,wiper rotating speed,and distillation pressure,are discussed.The optimal recovery condition was determined via orthogonal experiments using an OA9(34) design.The IL was recycled and reused 5 times in the homogeneous cellulose acetylation system under optimal conditions.The purity of recycled IL the 5th time reached 99.56%.FT-IR(Fourier transform infrared spectroscopy) and 1H NMR(nuclear magnetic resonance) spectroscopy showed that the structure of the recovered IL is not changed.This work proves that AmimCl has excellent reusability,and that molecular distillation is an effective method for recovering IL in homogeneous cellulose acetylation.

Quantitative Analysis Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Correlation between Mass Spectrometry Data and Sulfur Content of Crude Oils

Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) has become a powerful tool for analyzing the detailed composition of petroleum samples. However, the correlation between the numerous peaks obtained by FT-ICR MS and bulk properties of petroleum samples is still a challenge. In this study, the internal standard method was applied for the quantitative analysis of four straight-run vacuum gas oils(VGO) by atmospheric pressure photoionization(APPI) FT-ICR MS. The heteroatom class distribution of these VGO samples turned to be different when the concentration changed. Linear relationship between the normalized abundance and the concentration of VGO samples was identified for the total aromatic compounds, aromatic hydrocarbons, S1 and N1 species. The differences of the response factors were also discussed. The sulfur contents of a series of crude oils were proved to be linear with the FT-ICR MS data calibrated by the response factor of S1 species. This study demonstrated the feasibility of the internal standard method in quantitative analysis with APPI FT-ICR MS, and the bulk properties of petroleum samples could be correlated directly with the FT-ICR MS data.

On the Evaluation Overlap Integrals with the Same and Different Screening Parameters Over Slater Type Orbitals via the Fourier-Transform Method

In this paper, derivation of analytical expressions for overlap integrals with the same and different screening parameters of Slater type orbitals (STOs) via the Fourier-transform method is presented. Consequently, it is relatively easy to express the Fourier integral representations of the overlap integrals with same and different screening parameters mentioned as finite sums of Gegenbauer, Gaunt, binomial coefficients, and STOs.

Quantum Optical Squeezing Transform for Generalizing Fractional Fourier Transform

By establishing the relation between the optical scaled fractional Fourier transform （FFT） and quantum mechanical squeezing-rotating operator transform, we employ the bipartite entangled state representation of two-mode squeezing operator to extend the scaled FFT to more general cases, such as scaled complex FFT and entangled scaled FFT. The additiyity and eigenmodes are presented in quantum version. The relation between the scaled FFT and squeezing-rotating Wigner operator is studied.

Fast Image Retrieval of Textile Industrial Accessory Based on Multi-Feature Fusion

A hierarchical retrieval scheme of the accessory image database is proposed based on textile industrial accessory contour feature and region feature. At first smallest enclosed rectangle[1] feature (degree of accessory coordination) is used to filter the image database to decouple the image search scope. After the accessory contour information and region information are extracted, the fusion multi-feature of the centroid distance Fourier descriptor and distance distribution histogram is adopted to finish image retrieval accurately. All the features above are invariable under translation, scaling and rotation. Results from the test on the image database including 1,000 accessory images demonstrate that the method is effective and practical with high accuracy and fast speed.

Microstructure and microwave dielectric properties of CaO-B_2O_3-SiO_2 glass ceramics with various B_2O_3 contents

The effects of B2O3 addition on both the sintering behavior and microwave dielectric properties of CaO-B2O3-SiO2 （CBS） glass ceramics were investigated by Fourier transform infrared spectroscopy （FTIR）, X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that the increasing amount of B203 causes the increase of the contents of [BO3], [BO4] and [SiO4], which deduces the increase of CaB204 and a-SiO2 and the decrease of CaSiO3 correspondingly. No new phase is observed throughout the entire experiments. A bulk density of 2.54 g/cm3, a thermal expansion coefficient value of 11.95× 10-6 ℃-1 （20-500℃）, a dielectric constant er value of 6.42 and a dielectric loss tanδ value of 0.000 9 （measured at 9.7 GHz） are obtained for CBS glass ceramics containing 35%-B203 （mass fraction） sintered at 850 ℃ for 15 min.

Polyhydroxyl-aluminum pillaring improved adsorption capacities of Pb^(2+) and Cd^(2+) onto diatomite

In order to greatly improve adsorption capacity, the diatomite was pillared by polyhydroxyl-aluminum.A series of adsorption tests were conducted to obtain the optimum condition for pillared diatomite synthesis. The scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, surface area and porosity analyzer and micro-electrophoresis were used to determine pore structure and surface property.The pillared diatomite attaining the optimal adsorption densities （qe） of Pb^2＋ and Cd^2＋ was synthesized with the following conditions： Addition of pillaring solution containing Al3＋-oligomers with a concentration range of 0.1-0.2 mol/L to a suspension containing Na＋-diatomite to obtain the required Al/diatomite ratio of 10 mmol/g; synthesis temperature of 80 ℃ for 120 min; aging at a temperature of 105 ℃ for 16 h. The adsorption capacities of Pb^2＋ and Cd^2＋ on pillared diatomite increase by 23.79% and 27.36% compared with natural diatomite, respectively. The surface property of pillared diatomite is more favorable for ion adsorption than natural diatomite. The result suggests that diatomite can be modified by pillaring with polyhydroxyl-aluminum to improve its adsorption properties greatly.

Facile Preparation of Danazol Nanoparticles by High-Gravity Anti-solvent Precipitation （HGAP） Method

The nanoparticles of the hydrophobic drug of danazol with narrow size distribution are facilely prepared by controlled high-gravity anti-solvent precipitation （HGAP） process. Intensified micromixing and uniform nucleation environment are created by the high-gravity equipment （rotating packed bed） in carrying out the anti-solvent precipitation process to produce nanoparticles. The average particle size decreases from 55 μm of the raw danazol to 190 nm of the nanoparticles. The Brunauer-Emmett-Teller （BET） surface area sharply increases from 0.66 m^2·g^-1 to 15.08 m^2·g^-l. Accordingly, the dissolution rate is greatly improved. The molecular state, chemical composition, and crystal form of the danazol nanoparticles remains unchanged after processing according to Fourier transform infrared （FTIR） and X-ray diffraction （XRD）, The high recovery ratio and continuous production capacity are highly appreciated in industry. Therefore, the HGAP method might offer a general and facile platform for mass production of hydrophobic pharmaceutical danazol particles in nanometer range.

A novel synthesis of LiFePO_4/C from Fe_2O_3 without extra carbon or carbon-containing reductant

A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced： Fe2O3 （＋NH4H2PO4）→Fe2P2O7（＋Li2CO3＋glucose）→LiFePO4/C. X-ray diffractometry （XRD）, Fourier transform infrared spectroscopy （FTIR） and scanning electron microscopy （SEM） were utilized to characterize relevant products obtained in the synthetic procedure. The reaction of Fe2P2O7 and Li2CO3 was investigated by thermo-gravimetric and differential thermal analysis （TGA-DTA）. Fe2O3 is completely reduced to Fe2P2O7 by NH4H2PO4 at 700 ℃ and Fe2P2O7 fully reacts with Li2CO3 to form LiFePO4 in the temperature range of 663.4-890 ℃. The primary particles of LiFePO4/C samples prepared at 670, 700 and 750 ℃ respectively exhibit uniform morphology and narrow size distribution, 0.5-3 μm for those obtained at 670 and 700 ℃ and 0.5-5 μm for those obtained at 750 ℃. LiFePO4/C （carbon content of 5.49%, mass fraction） made at 670 ℃ shows an appreciable average capacity of 153.2 mA·h/g at 0.1C in the first 50 cycles.

Characterization of calcium deposition induced by Synechocystis sp. PCC6803 in BG11 culture medium

Calcium carbonate （CaCO3） crystals in their preferred orientation were obtained in BG11 culture media inoculated with Synechocystis sp. PCC6803 （inoculated BG11）. In this study, the features of calcium carbonate deposition were investigated. Inoculated BGll in different calcium ion concentrations was used for the experimental group, while the BGll culture medium was used for the control group. The surface morphologies of the calcium carbonate deposits in the experimental and control groups were determined by scanning and transmission electron microscopy. The deposits were analyzed by electronic probe micro-analysis, Fourier transform infrared spectrum, X-ray diffraction, thermal gravimetric analysis and differential scanning calorimetry. The results show that the surfaces of the crystals in the experimental group were hexahedral in a scaly pattern. The particle sizes were micrometer-sized and larger than those in the control group. The deposits of the control group contained calcium （Ca）, carbon （C）, oxygen （O）, phosphorus （P）, iron （Fe）, copper （Cu）, zinc （Zn）, and other elements. The deposits in the experimental group contained Ca, C, and O only. The deposits of both groups contained calcite. The thermal decomposition temperature of the deposits in the control group was lower than those in the experimental group. It showed that the CaCO3 deposits of the experimental group had higher thermal stability than those of the control group. This may be due to the secondary metabolites produced by the algae cells, which affect the carbonate crystal structure and result in a close-packed structure. The algae cells that remained after thermal weight loss were heavier in higher calcium concentrations in BGll culture media. There may be more calcium- containing crystals inside and outside of these cells. These results shall be beneficial for understanding the formation mechanism of carbonate minerals.