大功率光纤放大器分段泵浦方式下的理论分析

利用数值算法计算了掺镱双包层光纤放大器分段泵浦方式下的稳态速率方程组,分析比较了双端泵浦和多段泵浦方式下的最佳光纤长度,最高温度和效率,并采用遗传算法对分布泵浦功率的大小和每段光纤长度同时进行了优化。结果表明,通过优化,大功率分段泵浦光纤放大器获得了较为平坦的温度分布,与双端泵浦相比,大大降低了最高工作温度,斜率效率略有下降。     

叶片式混输泵内气液两相流的数值计算

气液两相流的数值模拟是多相混输技术研究中的一个难点.本文假定混输泵叶轮内为泡状流动,基于雷诺时均N-S方程和气液两相双流体模型,采用SIMPLEC算法,对叶片式混输泵叶轮内部两相三维紊流流场进行了数值计算,分析了水气混合工况下的流场分布特点.对含气率GVF=15%工况下的扬程特性进行了预测并与试验结果进行对比.数值计算结果表明,混输泵叶轮流道采用较小的径向尺寸差能较好地避免离心力所引起的气液分离,防止气堵现象的发生;叶轮进口部分存在的低压旋涡区容易使气体积聚,因此有必要进一步改进叶轮进口区的水力设计.     

Gain characteristics and optimization of dual-pump fiber optical parametric amplifier using two-section highly nonlinear fibers

In this paper the gain characteristics of two-pump fiber optical parametric amplifiers (FOPA) with two-section highly nonlinear fibers are analyzed numerically and the parameters of the fibers are optimized to reach broad and flat gain spectra using genetic algorithm. Different from the previous methods, here the space between two pump wavelengths and the parameter β₄ of the fibers are included as a pivotal factor in the optimization. The numerical simulation shows that using two-section practical high nonlinear fibers, the amplifier may reach 110 nm bandwidth covering 1495–1605 nm with 10.5 dB average gain and gain ripple of 0.17 dB, when the total pump power is 1 W.     

三能级光纤激光器速率方程组的阈值解析解

 在考虑了泵浦损耗及激光损耗的情况下，解析求解了阈值泵浦下的三能级光纤激光器速率方程组，获得了泵浦功率阈值的显函数解析表达式，泵浦功率沿光纤变化的隐函数表达式，以及用功率变化表示的各个能级的粒子数密度随位置变化的显函数表达式。并利用这些表达式对光纤激光器的阈值特性进行了研究，研究表明：泵浦功率阈值随泵浦损耗系数增大而增大；激光上能级粒子数密度随归一化位置呈下降趋势，而下能级粒子数密度的变化与此相反；泵浦功率阈值越大(光纤长度越长),净增益系数随归一位置下降就越快。所获得的结果适用于单包层和双包层光纤激光器。     

Simultaneous estimation of four proton pump inhibitors—lansoprazole,omeprazole, pantoprazole and rabeprazole: development of a novel generic HPLC‐UV method and its application to clinical pharmacokinetic study

A highly selective, sensitive and accurate HPLC method has been developed and validated for the estimation of four proton‐pump inhibitors (PPI), lansoprazole (LPZ), omeprazole (OPZ), pantoprazole (PPZ) and rabeprazole (RPZ), with 500 µL human plasma using zonisamide as an internal standard (IS). The sample preparation involved simple liquid–liquid extraction of LPZ, OPZ, PPZ and RPZ and IS from human plasma with ethyl acetate. The baseline separation of all the peaks was achieved with 0.1% triethylamine (pH 6.0):acetonitrile (72:28, v/v) at a flow rate of 1 mL/min on a Zorbax C₈ column. The total chromatographic run time was 11.0 min and the simultaneous elution of IS, OPZ, RPZ, PPZ and LPZ occurred at approximately 2.42, 4.45, 5.02 and 9.37 min, respectively. The method was proved to be accurate and precise at linearity range of 20.61–1999.79 ng/mL with a correlation coefficient (r) of ≥0.999. The limit of quantitation for each of the PPI studied was 20.61 ng/mL. The intra‐ and inter‐day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers. Copyright © 2009 John Wiley & Sons, Ltd.     

电动流动分析系统测定纯净水中的硝酸根

提出一种电渗驱动，电泳富集和离子选择电极检测相结合的流动分析方法。电渗泵驱动具有流量稳定，流量调节范围大，流向可逆，流动压强较大和驱动电压安全等优点。电泳的电堆积富集法具有设备简单，富集倍数大和可同时分离异种电荷离子等优点。因而该流动分析系统设备简单，电源通用，操作方便，功能多样且检出限低，可用于超低浓度离子的定量分析。文章还进一步探讨了电泳的电堆积原理，以及各种实验条件对富集的影响，并应用此系统     

小流量旋涡泵的理论设计与试验研究

建立了以效率和工作范围为主线的小流量旋涡泵的理论设计方法，并对ＸＷＢ－３／１３０和ＸＷＢ－１／１１０两台旋涡泵进行了试验研究．理论分析和试验结果表明：较大的流道面积Ｆ可以拓宽泵的工作范围，较大的径向间隙△ｐ和轴向单边间隙δα会降低泵的扬程和效率。     

某商用车怠速油底壳异响问题分析研究*

针对产品开发过程中某柴油车型发动机油底壳怠速时“呜呜”异响问题,通过噪声与振动的测试及仿真分析,对油底壳异响原因进行分析。结果表明,怠速时机油泵的工作激励频率与油底壳模态频率耦合,形成“呜呜”声,并通过油底壳表面辐射出来。进一步实验研究表明,随着机油温度的升高,机油泵功率、工作激励幅值会逐步减小,异响逐步减小。同时实验研究表明,机油量对油底壳模态频率有影响,油底壳内机油加注量越多,油底壳模态频率越低,油底壳表面振动幅值及异响均逐步减小。针对该异响问题,明确该发动机机油加注上限及下限时油底壳对应频率范围后,通过优化怠速转速,提高油底壳模态频率等使机油泵激励频率与油底壳模态频率避频,解决了该异响问题。     

A Novel Algorithm for Backward-Pumped Raman Amplifier

In this article, a novel semi-analytical algorithm for calculating backward-pumped Raman amplifier is proposed. The algorithm does not need iteration and can greatly save computational time. Simulation results for Raman amplifiers with 25 km, 50 km, and 100 km fibers show that the accuracy of the method is quite satisfying in comparison with the shooting algorithm and the deviation is within 0.02 dB.     

基于分布参数模型的CO_2蒸发器结构参数研究

在设计工况下,建立了用于跨临界二氧化碳热泵热水器的套管式蒸发器的稳态分布参数模型,对其结构参数进行了敏感性分析,指出了它们的合理变化范围:管内套1根管时,内管外径应至少大于11.00mm,低于13.00mm,外管内径应在20.00mm以上,23.00mm以下;管内套多根管时,以管内套3根管的性能为最优。优化设计结果对开发二氧化碳蒸发器产品具有一定的指导意义。