PSA平均光孤子系统传输性能的研究

本采用计算机系统仿真的方法，研究了应用相敏光放大器(PSA)作为在线放大器的采用平均孤子传输方案的光孤子通信系统中，泵浦光与信号光之间的相位漂移、光纤色散对光孤子通信系统传输性能的影响。仿真的结果表明：泵浦光与信号光之间的相位漂移将导致孤子幅度的下降；由于PSA增益的相敏特性，光纤色散导致孤子脉冲主瓣幅度下降，脉宽展宽，出现旁瓣。     

Solid dispersion particles of tolbutamide prepared with fine silica particles by the spray-drying method

Solid dispersion particles of tolbutamide (TBM) were prepared by formulating nonporous (Aerosil 200 (hydrophilic), Aerosil R972 (hydrophobic)) or porous (Sylysia 350 (hydrophilic), Sylophobic 200 (hydrophobic)) silica as a carrier and applying the spray-drying (SD) or evaporation (Eva) method. In the solid dispersion particles prepared by the SD method, TBM existed in a meta-stable form (Form II) irrespective of the type of silica. On the other hand, when the Eva method was used, various crystalline forms of TBM were observed in the solid dispersion particles according to the type of silica. Polymorphs of Forms III and IV were prepared with Aerosil 200 and Aerosil R972, respectively, while crystalline Form II was obtained when either of the forms of porous silica, Sylysia 350 or Sylophobic 200, was formulated. The dissolution property of TBM in the solid dispersion particles prepared with hydrophilic silica was remarkably improved compared with those of the original TBM crystals (Form I) or spray-dried TBM without silica (Form II). In the case of hydrophobic silica, the release rate of TBM from the solid dispersion particles was much slower than that of original TBM. The meta-stable form of TBM in the solid dispersion particles was stable for at least 4 weeks when stored at 60 °C and 0% RH, while the spray-dried TBM without silica (Form II) was gradually converted to the stable form (Form I) under the same storage conditions. Under the humid storage conditions (60 °C, 75% RH), the spray-dried TBM without silica (Form II) immediately converted into the stable form (Form I) within 1 day, while TBM (Form II) in the solid dispersions in a matrix of silica was stable for at least 1 week.     

Polyurethane ionomer dispersions from a blocked aromatic‐diisocyanate prepolymer

Aqueous anionic blocked aromatic polyurethane prepolymers were synthesized by a prepolymer mixing process and their dispersions were obtained by adding water to the blocked prepolymer solutions. A series of prepolymers were prepared by using toluene 2,4‐diisocyanate, 4,4′‐diphenylmethane diisocyanate, polytetramethylene glycol, dimethylol propionic acid, methyl ethyl ketoxime and ε‐caprolactam. The aqueous dispersions were characterized by Fourier‐transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. The particle sizes, viscosities, pH and storage stabilities of the dispersions were studied and compared. Some mechanical properties of the cast films obtained from the aqueous dispersions and the adhesive properties of the dispersions were also evaluated. Copyright © 2004 Society of Chemical Industry     

高速光纤通信系统中偏振模色散的研究方法分析

目前偏振模色散(PMD)已成为长距离高速率数据和模拟系统的主要限制因素。主要分析讨论了PMD的几种研究方法:琼斯矩阵法、斯托克斯空间法和耦合非线性薛定谔方程。耦合非线性薛定谔方程多用于PMD对光纤传输系统性能的影响分析,文中对分步傅里叶法数值解非线性方程进行了详细的分析。     

A new FDTD scheme analysis for the characteristics of the magnetic‐anisotropic EBG structure

In this article, the new grid finite‐difference time‐domain (NG‐FDTD) method is applied to calculate the dispersion curves of electromagnetic band‐gap structures, and the dispersion characteristics of three magnetic‐anisotropic medium EBG structure are obtained using the NG‐FDTD method. According to these results, we can conclude that the EBG structure of a magnetic‐anisotropic medium, in which the permeability of nondiagonal elements is real, has a much larger band‐stop than that of isotropic EBG. Other magnetic‐anisotropic EBG structures can also increase the first band‐stop. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

基于C8051F的电量测量与传输系统

介绍一种利用高速51系列单片机C8051F020组成的电量测量及数据传输系统,系统能比较实时准确地监测三相电压、电流、功率、电能和功率因数等。详细介绍了频率、相位差的测量原理和A/D转换,以及系统所需电源的电路设计。并且讨论了几种数据传输的方式:RS 485通信、CAN通信及GPRS通信。此系统可以用于电力系统中家庭用户以及变压器的远程电量监测。     

透明液晶薄膜旋光色散特性研究

以透明塑料为基板,将液晶薄膜均匀涂于其上制成透明的具有旋光性的薄片,并用自行研制的旋光色散装置,对所制薄片的旋光色散特性进行了研究,测试结果显示其具有很大的旋光性.同时,用玻尔兹曼方程进行了理论拟合,发现拟合结果与实验结果有着极好的符合。     

偏移中地震波粘滞效应的补偿研究

探讨了在地震资料偏移时对地震波粘滞效应进行补偿的方法。给出了方法的基本原理,即将地震波的吸收和频散考虑到偏移延拓算子中去,在进行波场延拓的同时,补偿地震波的吸收和频散。偏移延拓算子通过求解线性最优化和非线性最优化问题来获得,因此保证了算子的稳定性和精度。偏移时,通过延拓算子查表法,利用McClellan变换实现三维波场的向下延拓。数值模拟表明,与传统偏移方法相比,在偏移中考虑粘滞性吸收和衰减能够获得更真实、更精确的地下成像。     

The application of flow dispersion models to the FM01-LC laboratory filter-press reactor

The flow distribution in the rectangular channel of a laboratory filter-press electrochemical reactor was evaluated using three flow models namely: (a) axial dispersion, (b) sum of two phases and (c) fast and stagnant zones. In the case of the axial-dispersion model, several methods have been used to calculate the Peclet number; the moment method, the non-linear least-squares and the Laplace transform technique. Several boundary conditions, involving different physical and experimental assumptions of the flow were used to solve the partial differential equation that describes the flow behaviour. A total of nine expressions to examine flow dispersion has been used. The comparison of experimental and predicted response signals was made by evaluating the root mean squared error. A data fit in real time has been found to be a better choice as solutions based on the evaluation of moments are prone to error due the overweight of the signal at long times. Data fitting in the Laplace plane is very accurate but it does not guarantee a good fit in real time. Models based on the sum of a fast and a slow or stagnant phase resulted in solutions having very low values of the extension of the slow and stagnant phases, the assumption of a single phase with some degree of dispersion was considered more appropriate.     

Calculation of the Figure of Merit of Linearly Chirped Fiber Gratings for Dispersion Compensation

1IntroductionBecauseoftheadventoferbium-dopedamplifiers,thelengthoftheophcalfiberlinksisnolongerlicitedbytheabsorphon,butratherbythechromaticdispersionofthefiber.Especially'theophcalsignalshapeissoseriouslydestroyedthatthebit-error-rate(BER)isratherhigherinthelonghaulhigh-bit-rateophcalcommunicationsystem.Sothedispersionoffibermustbecompensatedbyvariouskindsofdevices.Amongthem,thecompensatorusingthelinearlychirpedfibergratingshascausedagreatinterestindispersioncompensatingdeVices11-5].Onemus…