Analysis of fields in an air-cored superconducting synchronous motor with an HTS racetrack field winding

High temperature superconducting (HTS) synchronous motors can offer significant weight and size reductions, as well as improved efficiency, over conventional copper-wound machines due to the higher current density of high temperature superconducting (HTS) materials. In order to optimise the design parameters and performance of such a machine, this paper proposes a basic physical model of an air-cored HTS synchronous motor with a copper armature winding and HTS field winding. An analytical method for the field analysis in the synchronous motor is then presented, followed by a numerical finite element analysis (FEA) model to verify the analytical solution. The model is utilised to study the influence of the geometry of the HTS coils on the magnetic field at the armature winding, and geometrical parameter optimisation is carried out using this theoretical model to obtain a more sinusoidal magnetic field at the armature, which has a major influence on the performance of the motor.

Rapid quantification of total microcystins in cyanobacterial samples by periodate-permanganate oxidation and reversed-phase liquid chromatography

Microcystins (MCs) comprise a family of more than 80 related cyclic hepatotoxic heptapeptides. Oxidation of MCs causes cleavage of the chemically unique C-20 beta-amino acid (2S, 3S, 8S, 9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda) amino to form 2-methyl-3-methoxy-4-phenylbutanoic acid (MMPB), which has been exploited to enable analysis of the entire family. In the present study, the reaction conditions (e.g. concentration of the reactants. temperature and pH) used in the production of MMPB by oxidation of cyanobacterial samples with permanganate-periodate were optimized through a series of well-controlled batch experiments. The oxidation product (MMPB) was then directly analyzed by high-performance liquid chromatography with diode array detection. The results of this study provided insight into the influence of reaction conditions on the yield of MMPB. Specifically, the optimal conditions, including a high dose of permanganate (>= 50 mM) in saturated periodate solution at ambient temperature under alkaline conditions (pH similar to 9) over 1-4 h were proposed, as indicated by a MMPB yield of greater than 85%. The technique developed here was applied to determine the total concentration of MCs in cyanobacterial bloom samples, and indicated that the MMPB technique was a highly sensitive and accurate method of quantifying total MCs. Additionally, these results will aid in development of a highly effective analytical method for detection of MMPB as an oxidation product for evaluation of total MCs in a wide range of environmental sample matrices, including natural waters, soils (sediments) and animal tissues. (C) 2009 Elsevier B.V. All rights reserved.

Electronic structure in GaAs/AlxGa1-xAs spherical quantum dots

In this paper, how the dots' radius, At concentration and external electric field affect the single electron energy states in GaAs/AlxGa1-xAs spherical quantum dots are discussed in detail. Furthermore, the modification of the energy states is calculated when the difference in effective electron mass in GaAs and AlxGa1-xAs are considered. In addition, both the analytical method and the plane wave method are used in calculation and the results are compared, showing that they are in good agreement with each other. The results and methods can provide useful information for the future research and potential applications of quantum dots.

Influence of mode symmetry on quality factors of degenerate states in microlasers with an equilateral triangle resonator

Modes in equilateral triangle resonator (ETR) are analyzed and classified according to the irreducible representations of the point group C-3v., Both the analytical method based on the far field emission and the numerical method by FDTD technique are used to calculate the quality factors (Q-factors) of the doubly degenerate states in ETR. Results obtained from the two methods are in reasonable agreement. Considering the different symmetry properties of the doubly degenerate eigenstates, we also discuss the ETR joined with an output waveguide at one of the vertices by FDTD technique and the Pade approximation. The variation of Q-factors versus width of output waveguide is analyzed. The numerical results show that doubly degenerate eigenstates of TM0.36 and TM0.38 whose wavelengths are around 1.5 mu m in the resonator with side-length of 5 mu m have the Q-factors larger than 1000 when the width of the output waveguide is smaller than 0.4 mu m. When the width of the output waveguide is set to 0.3 mu m, the symmetrical states that are more efficiently coupled to output waveguide have Q-factors about 8000, which are over 3 times larger than those of asymmetric state.

Reflection and transmission properties of double submerged rectangular blocks

An analytic method is used to study the reflection and transmission coefficients of the double submerged rectangular blocks (DSRBs) in oblique waves.. The scattering potentials are obtained by means of the eigenfunction expansion method, and expressions for the reflection and transmission coefficients are determined. The boundary element method is employed to verify the correctness of the present analytical method. The DSRBs have better performance than the single submerged rectangular block (SSRB) in certain cases. The reflection and transmission properties of the DSRBs are investigated for some specific cases, and the influences of the geometric parameters are also presented.

Analysis of sulfur-containing compounds in crude oils by comprehensive two-dimensional gas chromatography with sulfur chemiluminescence detection

This paper reports an analytical method for separating, identifying, and quantifying sulfur-containing compounds in crude oil fraction (IBP-360degreesC) samples based on comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. Various sulfur-containing compounds and their groups were analyzed with one direct injection. 3620 peaks were detected including 1722 thiols/thioethers/ disulfides/1-ring thiophenes, 953 benzothiophenes, 704 dibenzothiophenes, and 241 benzonaphthothiophenes. The target sulfur compounds and their groups were identified based on the group separation feature and structured retention of comprehensive two-dimensional gas chromatography as well as standard substances. The quantitative analysis of major sulfur-containing compounds and total sulfur was based on the linear response of the sulfur chemiluminescence detector using the internal standard method. The sulfur contents of target sulfur compounds and their groups in 4 crude oil fractions were also determined. The recoveries for standard sulfur-containing compounds were in the range of 90-102%. The quantitative result of total sulfur in the Oman crude oil fraction sample was compared with those from ASTM D 4294 standard method (total S by X-ray fluorescence spectrometry), the relative deviation (RD%) was 4.2% and the precision of the method satisfactory.

Determination of sulfur-containing compounds in diesel oils by comprehensive two-dimensional gas chromatography with a sulfur chemiluminescence detector

This article reports an analytical method for separating, identifying and quantitating sulfur-containing compounds and their groups in diesel oils (170-400degreesC) using comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. The identification of target compounds and their groups was based on standard substances, the group separation feature and the-effect of comprehensive two-dimensional gas chromatography. The quantitative analysis on major sulfur compounds and total sulfur was carried out based on the linear response of sulfur chemiluminescence detector and the internal standards method. The results of total sulfur determination in the samples were compared with those from ASTM D 4294 standard method, the R.S.D. percentage were <6.02%, correctness of this method can meet the industrial requirement. To the end, the method developed was used to investigate the sulfur-containing compounds in different diesel oils, the result shows that the distribution of sulfur-containing compounds in diesel oils from different process units are apparently different. The sulfur compounds in fluid catalytic cracking (FCC), residuum fluid catalytic cracking (RFCC) diesel oils mainly exist in the form of alkyl-substituted dibenzothiophenes that add up to about 40-50% of the total sulfur, while this number is only 6-8 and 20-28% in visbreaking (VB) and delayed-coking (DC) diesel oils, respectively. (C) 2003 Elsevier B.V. All rights reserved.

Separation of ternary systems of hydrophilic ionic liquid with miscible organic compounds by RPLC with refractive index detection

A rapid and simple analytical method was developed for the simultaneous and quantitative determination and separation of hydrophilic imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl; 1-hexyl-3-methylimidazolium chloride, [C(6)mim]Cl; 1-octyl-3-methylimidazolium chloride, [C(8)mim]Cl; 1-allyl-3-methylimidazolium chloride, [Amim]Cl; or 1-allyl-3-methylimidazolium bromide, [Amim]Br) with miscible ethyl acetate and EtOH and their mixtures using reverse phase liquid chromatography coupled with refractive index detection (RPLC-RI). The influence of 60 to 100% (volume percentage) methanol in the mobile phase on the IL systems ([C(4)mim]Cl, [C(6)mim]Cl, [C(8)mim]Cl, [Amim]Br, or [Amim]Cl)-ethyl acetate-EtOH was investigated.

川乌与贝母配伍禁忌的电喷雾质谱研究

The ESI-MS analytical method was established for studying the alkaloids content in the decoctions of Radix aconiti combined with Bulbus Fritillariae Thunbergii or bulbus fritillariae Cirrhosae.For the co-decoctions of Radix aconiti combined with Thunberg Fritillary Bulb contains more diester-alkaloids than that of co-decoctions of Radix aconiti combined with Bulbus Fritillariae Cirrhosae.When Radix aconiti was combined with Thunberg Fritillary Bulb,diester-alkaloids were mainly dissolved in water.But diester-alkaloids were mainly converted into lipo-alkaloids when Radix aconiti was combined with Bulbus Fritillariae Cirrhosae.

ESI-MS法研究白芍炮制前后化学成分的变化

ESI-MS analytical method was employed to study extracts of unprocessed and processed Radix Paeoniae alba.The results of the experiments prove that different processed methods is making a certain different influence on the contents of chemiacl components in Radix Paeoniae alba.This method is simple and accurate.It can be used for analyse of Traditional Chinese Medicine(TCM).

反水雷UUV的作战效能模型分析

针对UUV的战术技术性能和使用特点,基于WSEIAC方法建立了反水雷UUV的作战效能基本评估模型,系统地论述了反水雷UUV作战效能的定义、量度和反水雷UUV作战效能基本评估模型及效能评定所涉及的UUV可用性、可信性及作战能力的分析方法。该模型能鲜明反映UUV装备的系统效能的物理本质,并在工程应用上具有简便灵活的特点,对于设计反水雷UUV——一种未来海军必要的新型反水雷装备,具有重要的指导意义。

企业间电子商务风险的综合分析方法

互连网上电子商务的蓬勃发展为企业提供了巨大商机，但风险也是巨大的。同时，网上信息爆炸也需要一种使用的方法对信息进行分析、整理、提取，为下一步的决策提供坚实的基础。本文在总结不同风险分析方法的基础上，提出了一种完整的方法，为网上商务的风险分析和决策提供了一种实用的解决方案。

离散型封闭式传送带生产系统的研究——一种通用的分析方法

本文对离散型封闭式传送带生产系统给出了一种通用的分析方法.基于传送带参数和工作站的服务时间,研究了系统中各流量间的相互关系,建立了动态的和稳态的表达式,给出了系统的品质指标,并首次指出了系统中存在一种循环效应及其对系统容量的影响。最后用仿真方法检验了分析结果的正确性.

一种并联激光焊接机器人的机构设计与运动学分析

提出了一种3分支5自由度的并联激光焊接机器人,通过3个分支共同作用,使整机具备了5个自由度的空间加工能力.针对激光焊接,通过分析该机器人的结构特性,建立了其正反解运动学模型,通过解析法求解该模型并进行了计算仿真.最后,对机器人进行激光拼焊实验,仿真数据和实验结果表明,本文研究的并联机器人机构适用于实际的高速、高精度激光焊接。

微量样品钕-锶-铅同位素分析方法在黄河下游悬浮颗粒物及沉积物的应用

Aim in Rb-Sr-REE-Pb isotopic analysis of river material, a single-stage, highly efficient and rapid chemical separation method of Rb-Sr-REE-Pb has been established by a combination of the SR special resin and the RE resin. At the same time, Feasibility of high precision analysis on micro-size Nd samples，which were chemically separated by using the LN resin, were systematicly studied using the NdO+ technique in thermal ionization mass spectrometer (TIMS). Results show that high precision measurement of Nd isotopic ratios can be successfully achieved on micro-sample of 1 ng size lever, by systematic experiments on isobar interferences and optimizing separation and measurement conditions. This method will greatly extend the application prospect of the NdO+ technique. Sr-Nd-Pb isotopic composition of suspending particle material (SPM) and sediment and Sr isotopic composition of river water in the low reaches of the Yellow Rriver have been systematically analysed in this study. Results can indicate followings: (1) relative stable Sr isotopic ratios around 0.7112 of river water suggest great influcence from dissolution of carbonate component of loss material on Sr isotopic composition of river water; (2) Nd isotopic compositions of SPM and sediment of the Yellow river are is similar, mean εNd value of SPM around -11.5 and mean εNd value of sediment -12.7, slightly lower than that of SPM. Nd isotopic composition of the Yellow River material is simarlar to or slightly lower than loss material (-9.5); (3) evidence of Sr and Pb isotopic compositions of both SPM and sediment reveals a mixing trend of two endmembers. Sr isotopic ratios of SPM after leaching are significantly different that those without leaching, possibly suggesting strong alteration of river water. Pb isotopic ratios of SPM remain unchangable after leaching compared with unleached SPM; (4) Pb-contents of SPM are commonly higher than those of sediments, while Pb isotopic ratios of SPM are significantly lower. Pb isotopic composition of the Yellow River is relatively constant, which can be a useful provenance indicator between the Changjiang and Yellow Rivers.