改善闭环光纤陀螺标度因数线性度的方法

当光纤陀螺的输入角速率较小时,其测量误差比较大,很难满足卫星等对测量精度要求较高的应用领域要求。文中主要从闭环反馈主回路探测器误差分析开始,分别从电子串扰、Y波导的非线性及D/A转换器的非线性等几方面,论述了在小角速率输入的情况下,分别对光纤陀螺标度因数非线性的影响,并且给出了改善的方法。试验结果显示,采取相应措施后,光纤陀螺的标度因数线性度有明显的提高。     

电感电流伪连续模式下Boost变换器的分数阶建模与分析

基于电感和电容本质上是分数阶的事实,采用分数阶微积分理论建立了电感电流伪连续模式下Boost变换器的区间分数阶数学模型.依据状态平均建模方法,建立了Boost变换器工作于电感电流伪连续模式下的分数阶状态平均模型.通过所建的分数阶数学模型对其电感电流和输出电压进行了理论分析以及传递函数的推导,并比较了与整数阶数学模型的区别.根据改进的Oustaloup分数阶微积分滤波器近似算法,采用电感和电容的等效分数阶电路模型,在Matlab/Simulink的仿真环境下,对其数学模型和电路模型进行了仿真对比,分析了模型误差产生的原因,验证了所建的分数阶数学模型以及对其理论分析的正确性.最后,指出了分数阶Boost变换器工作于电感电流伪连续模式与连续模式、断续模式的区别与联系.     

圆波导TM_(01)-TE_(11)模式变换器

提出了一种在圆波导中添加金属分割片及半边金属管壳的结构以实现圆波导TM01-TE11模式转换。通过金属分割片将圆波导分成两个半圆区域:其中一个半圆区域为空波导,另一半圆区域为填充一定厚度金属管壳的空波导。在S波段对设计的中心频率为2.8GHz的物理模型进行数值模拟与实验研究,模拟结果表明:在中心频率2.8GHz转换效率为99.56%,反射率低于0.01;在2.716～2.946GHz频带内转换效率大于90%,S11小于-10dB。实验中测试到的S11参数与模拟结果基本一致,证明了该变换器技术方案的可行性和模拟结果的正确性。     

矩形波导TM_(11)-TE_(10)模式转换器的初步设计

设计了一种矩形波导隔断插板式TM11-TE10模式转换器。其结构是在矩形波导横截面窄边的中部,平行于横截面宽边插入一块金属平板,将其等分为上下两个矩形波导,将TM11模式转换为分别位于上下两个矩形波导内相位相反的TE10模式。然后分别在上下两个矩形波导内,平行于窄边等间距地插入一组金属薄板。TE10模式微波经过轴向长度差为合适值的上下两组插板后,相移差变为180°,使原本相位相反的TE10模式转为同向,最后通过阻抗渐变合成单个波导的TE10模式。该模式转换器可与带状电子束高功率微波源共轴,其横向最大尺寸可与带状电子束高功率微波源矩形输出口保持一致,轴向长度较短,结构简单、紧凑。利用有限元算法仿真软件,对该设计方案进行了验证和初步优化设计。初步的设计结果表明:当相对带宽为10%时,TM11至TE10模式的转换效率大于-0.45 dB,可满足带状电子束高功率微波源对输出结构的设计要求。     

94GHz的TE_(11)-HE_(11)模式变换器设计

基于模式匹配技术的迭代综合方法优化设计了94 GHz的TE11-HE11模式转换器。采用商用电磁仿真软件对设计的模式变换器的性能进行了验证,两者结果基本一致。在88~102 GHz的频带范围内,模式输出纯度超过98%,其中最大模式纯度为99.1%。设计的基于半径微扰的光滑壁圆波导结构的模式变换器结构简单,易于加工,同时避免了波纹模式变换器波纹间隔易发生击穿的弊端。     

Detection and quantification of plasma amyloid-β by selected reaction monitoring mass spectrometry

Amyloid-β (Aβ) in human plasma was detected and quantified by an antibody-free method, selected reaction monitoring mass spectrometry (SRM-MS) in the current study. Due to its low abundance, SRM-based quantification in 10 μL plasma was a challenge. Prior to SRM analysis, human plasma proteins as a whole were digested by trypsin and high pH reversed-phase liquid chromatography (RPLC) was used to fractionate the tryptic digests and to collect peptides, Aβ_1–5, Aβ_6–16, Aβ_17–28 and Aβ_29–40(42) of either Aβ_1–40 or Aβ_1–42. Among those peptides, Aβ_17–28 was selected as a surrogate to measure the total Aβ level. Human plasma samples obtained from triplicate sample preparations were analyzed, obtaining 4.20 ng mL⁻¹ with a CV of 25.3%. Triplicate measurements for each sample preparation showed CV of <5%. Limit of quantification was obtained as 132 pM, which corresponded to 570 pg mL⁻¹ of Aβ_1–40. Until now, most quantitative measurements of Aβ in plasma or cerebrospinal fluid have required antibody-based immunoassays. Since quantification of Aβ by immunoassays is highly dependent on the extent of epitope exposure due to aggregation or plasma protein binding, it is difficult to accurately measure the actual concentration of Aβ in plasma. Our diagnostic method based on SRM using a surrogate peptide of Aβ is promising in that actual amounts of total Aβ can be measured regardless of the conformational status of the biomarker.     

飞行时间质谱仪数据采集系统设计

针对飞行时间质谱仪高分辨率、宽质量范围的特点,设计了一种高精度、大量程的数据采集系统。系统对前端信号进行放大、幅度甄别和电平转换,使用专用时间间隔测量芯片TDC-GPX测量脉冲时间间隔,应用现场可编程门阵列(FPGA)进行时序控制,通过通用串行总线(USB 2.0)接口与计算机连接,采用时分复用技术实现上位机对采集系统的控制及高速数据传输。测试结果表明,单通道测量精度小于100 ps,测量范围大于500μs,可进行8个通道测量。     

High quality drug screening by capillary electrophoresis: A review

High quality assays are needed in drug discovery to reduce the high attrition rate of lead compounds during primary screening. Capillary electrophoresis (CE) represents a versatile micro-separation technique for resolution of enzyme-catalyzed reactions, including substrate(s), product(s), cofactor(s) and their stereoisomers, which is needed for reliable characterization of biomolecular interactions in free solution. This review article provides a critical overview of new advances in CE for drug screening over the past five years involving biologically relevant enzymes of therapeutic interest, including transferases, hydrolases, oxidoreductases, and isomerases. The basic principles and major configurations in CE, as well as data processing methods needed for rigorous characterization of enzyme inhibition are described. New developments in functional screening of small molecules that modulate the activity of disease-related enzymes are also discussed. Although inhibition is a widely measured response in most enzyme assays, other important outcomes of ligand interactions on protein structure/function that impact the therapeutic potential of a drug will also be highlighted, such as enzyme stabilization, activation and/or catalytic uncoupling. CE offers a selective platform for drug screening that reduces false-positives while also enabling the analysis of low amounts of complex sample mixtures with minimal sample handling.     

X射线皮秒变象管分幅相机研究

本文介绍了我们提出的一种新的实现皮秒分幅摄影的技术方案,其优点是对控制线路要求不高,给出了用计算机对此方案进行数值模拟的结果和新设计的用于这种分幅方案的变象管特性,用直流X射线源测出该变象管的静态空间分辨率为20lp/mm。用激光打靶产生的脉冲X射线测量了相机动态特性,已得到了四幅动态像,每幅曝光时间150ps,空间分辨率3lp/mm。     

高阶贝塞耳光束及其传输特性的研究

本文首次提出了高阶贝塞耳(Bassel)光束的概念,并详细研究了高阶贝塞耳光束通过变换矩阵为光学系统的传输特性.