植物声频振动特性检测仪的原理及其设计

本文介绍了一种利用激光多普勒干涉量度学原理实现的植物声频振动特性检测仪。文章详述了仪器的工作原理、光路和电路设计、测量数据处理过程，以及仪器的实际使用效果。测量结果表明，该仪器能够实现对植物振动特性的非接触式测量，具有较高的测量精度和空间分辨率，能够测量植物受激振动和自发振动的功率谱和自相关函数。     

Depolarization of an Uncollimated Laser Beam in a Turbulent Medium

The depolarization of a beam wave, with Gaussian intensity distribution and arbitrary divergence, propagating in a turbulent medium is considered. The correlation function of the depolarized component of the beam is determined. The mean-square depolarization fluctuation is then determined for a medium characterized by a Kolmogorov spectrum. If the beam is assumed to be collimated, this expression reduces to that of Collett and Alferness; if the plane-wave limiting case of the Gaussian beam is taken, the results in this paper agree with those of Strohbehn. The results show that off the beam axis the depolarization can be greater than for the plane wave, and that near the beam focal point the depolarization may decrease by orders of magnitude.     

微车FR型动力传动系扭振特性及其控制方法评述

阐述动力传动系扭振分析的三种方法（理论分析、试验测试以及 CAE 仿真）,并分析微车 FR 型动力传动系扭振特性。在此基础上,从动力学参数优化和附加减、隔振装置两方面总结动力传动系扭振控制方法,具体包括动力学参数对传动系固有特性和扭振响应的影响分析和TVD、CTD、DMF、STD的优缺点对比以及工程应用现状讨论。     

Cascade optical chromatography for sample fractionation

Optical chromatography involves the elegant combination of opposing optical and fluid drag forces on colloidal samples within microfluidic environments to both measure analytical differences and fractionate injected samples. Particles that encounter the focused laser beam are trapped axially along the beam and are pushed upstream from the laser focal point to rest at a point where the optical and fluid forces on the particle balance. In our recent devices particles are pushed into a region of lower microfluidic flow, where they can be retained and fractionated. Because optical and fluid forces on a particle are sensitive to differences in the physical and chemical properties of a sample, separations are possible. An optical chromatography beam focused to completely fill a fluid channel is operated as an optically tunable filter for the separation of inorganic, polymeric, and biological particle samples. We demonstrate this technique coupled with an advanced microfluidic platform and show how it can be used as an effective method to fractionate particles from an injected multicomponent sample. Our advanced three-stage microfluidic design accommodates three lasers simultaneously to effectively create a sequential cascade optical chromatographic separation system.     

Interval observer filtering-based fault diagnosis method for linear discrete-time systems with dual uncertainties

A novel interval observer filtering-based fault diagnosis method for linear discrete-time systems with dual uncertainties is proposed to detect actuator faults. The idea of minimization is adopted to design a fault-free state estimator by merging unknown but bounded and Gaussian disturbances and noises according to the signal average power principle. Using a fault-free state interval and measurement residual of the system, a fault detection indicator is designed based on the residual probability ratio, to achieve dynamic fault detection, isolation and identification. Finally, various simulation examples are provided to demonstrate the accuracy and effectiveness of the proposed method.     

Beam-stabilized optical switch using a voice-coil motor actuator

This paper presents the design, analysis, and implementation of a beam-stabilized optical switch using a voice-coil motor actuator. A closed-loop control system using a proportional-integral-derivative (PID) controller is developed to stabilize the beam at the desired angle to maximize the optical power detected by a photodiode. Experimental results show a good performance with 17 ms switching speed and a maximum overshoot of only 3%.     

Characterization of the near-field and convectional transport behavior of micro and nanoparticles in nanoscale plasmonic optical lattices

Here, we report the characterization of the transport of micro- and nanospheres in a simple two-dimensional square nanoscale plasmonic optical lattice. The optical potential was created by exciting plasmon resonance by way of illuminating an array of gold nanodiscs with a loosely focused Gaussian beam. This optical potential produced both in-lattice particle transport behavior, which was due to near-field optical gradient forces, and high-velocity (∼μm/s) out-of-lattice particle transport. As a comparison, the natural convection velocity field from a delocalized temperature profile produced by the photothermal heating of the nanoplasmonic array was computed in numerical simulations. This work elucidates the role of photothermal effects on micro- and nanoparticle transport in plasmonic optical lattices.     

波导DCN激光器输出特性的理论和实验分析

介绍了波导DCN激光器的原理和结构,重点研究了波导DCN激光本征模(EH11模)在远场和近场的多阶高斯耦合效应,分析了DCN激光器的输出特性.理论计算的结果与实验数据基本吻合,并为EAST托卡马克远红外激光干涉仪系统的光学设计提供了必要条件     

Three-dimensional vibration suppression for an Euler–Bernoulli beam with asymmetric output constraint

A vibration control strategy is addressed for the three-dimensional vibration suppression of an Euler-Bernoulli beam (EBB) subject to asymmetric output constraints in this paper. A special piecewise barrier Lyapunov function candidate is provided to prevent the asymmetric output constraint violation, and a model-based boundary control (MBC) is developed subsequently to ensure the coupled vibration reduction. Moreover, considering the parameter uncertainties, an adaptive law is designed to estimate the uncertain parameter and to update the vibration controller. The main challenge of this work is to consider the asymmetric output constraint in a nonlinear and coupled infinite-dimensional system. Finally, numerical simulations are made to present the system performance under the proposed vibration controllers which maintain the output being restrained in the predefined scope.     

PN codes versus chaotic codes: Performance comparison in a Gaussian approximated wideband CDMA system over Weibull fading channels

The performance of a Wideband Code Division Multiple Access (W-CDMA) system using Pseudo Noise (PN) codes and chaotic codes in the presence of a Weibull fading channel is studied in this paper. The W-CDMA system modeled using Gaussian Approximation is analyzed on a Weibull fading channel which fades the amplitude of the transmitted signal randomly according to the Weibull distribution. Closed-form expressions for Bit Error Rate (BER) are derived and expressed in terms of Meijer?s-G function. Performance measures in terms of BER are plotted versus Signal-to-Noise Ratio (SNR) for various values of fading severity, average fading power, and channel memory using PN and chaotic codes. Performance comparison between PN codes and chaotic codes are also analyzed.     

A novel hybrid filter-based fault diagnosis algorithm for switched systems with a dual noise term

This study considers state and fault estimation for a switched system with a dual noise term. A zonotopic and Gaussian Kalman filter for state estimation is designed to obtain state estimation interval in the presence of both stochastic and unknown but bounded (UBB) uncertainties. The switching state and fault state of the system are distinguished by detecting whether the system measurement date is within the bounds of its predicted output. Once the switched time is detected in the system, the filter zonotopic and Gaussian Kalman functions are initialized. Once the fault time is detected, a zonotopic and Gaussian Kalman filter-based fault estimator is constructed to estimate the corresponding faults. Finally, a numerical simulation is presented to demonstrate the accuracy and effectiveness of the proposed algorithm.     

Switching Gaussian-heavy-tailed distribution based robust Gaussian approximate filter for INS/GNSS integration

In inertial navigation system and global navigation satellite system (INS/GNSS) integration, the practical stochastic measurement noise may be non-stationary heavy-tailed distribution due to outlier measurements induced by multipath and/or non-line-of-sight receptions of the original GNSS signals. To address the problem, a new switching Gaussian-heavy-tailed (SGHT) distribution is presented, which models the measurement noise with the help of switching between the Gaussian and the an existing heavy-tailed distribution. Then, utilizing two auxiliary parameters satisfying categorical and Bernoulli distributions respectively, we construct the SGHT distribution as a hierarchical Gaussian presentation. Furthermore, applying variational Bayesian inference, a novel SGHT distribution based robust Gaussian approximate filter is derived. Meanwhile, to reduce the computational complexity of the filtering process, an improved fixed-point iteration method is designed. Finally, the simulation of integrated navigation for an aircraft illustrates effectiveness and superiority of the proposed filter as compared the existing robust filters.     

Adaptive actuator fault-tolerant control for a three-dimensional Euler–Bernoulli beam with output constraints and uncertain end load

This paper studied an adaptive actuator fault-tolerant control scheme for the flexible Euler–Bernoulli beam in the three-dimensional space with output constraints and uncertain end load. The dynamic models are represented by partial differential equations (PDEs) and ordinary differential equations (ODEs). When part of the actuator fails, an adaptive control scheme is designed to regulate the vibration and stabilize the flexible three-dimensional Euler–Bernoulli beam. Barrier Lyapunov Function (BLF) is adopted to realize output constraints of the system. Adaptive control law with projection mapping operator is designed to compensate for the end load which is uncertain and bounded. The goal of this paper is to suppress the displacement of the flexible three-dimensional Euler–Bernoulli beam which can be constrained in given bounds under actuator fault and uncertain, bounded end load. It is confirmed that the proposed control scheme can deal with the vibration, adaptive actuator fault-tolerant control, uncertain and bounded end load and output constraints of the system simultaneously. Finally, numerical simulations illustrate the effectiveness and feasibility of the method.     

Enhanced fluorescence emitted by microdroplets containing organic dye emulsions

In this paper, laser beam resonant interaction with pendant microdroplets that are seeded with a laser dye (Rhodamine 6G (Rh6G)) water solution or oily Vitamin A emulsion with Rhodamine 6G solution in water is investigated through fluorescence spectra analysis. The excitation is made with the second harmonic generated beam emitted by a pulsed Nd:YAG laser system at 532 nm. The pendant microdroplets containing emulsion exhibit an enhanced fluorescence signal. This effect can be explained as being due to the scattering of light by the sub-micrometric drops of oily Vitamin A in emulsion and by the spherical geometry of the pendant droplet. The droplet acts as an optical resonator amplifying the fluorescence signal with the possibility of producing lasing effect. Here, we also investigate how Rhodamine 6G concentration, pumping laser beam energies and number of pumping laser pulses influence the fluorescence behavior. The results can be useful in optical imaging, since they can lead to the use of smaller quantities of fluorescent dyes to obtain results with the same quality.     

Probability of error in digital fiber optic systems with inter-symbol interference and signal dependent additive noise

Data transmission via optical fiber is a new discipline of communication theory. The principal difference from conventional baseband data transmission, which is characterized by a signal independent additive Gaussian noise, is the existence of a signal dependent shot noise.This paper presents a technique for estimating the error probability performance of digital systems with inter-symbol interference and signal dependent additive noise. For binary antipodal (±1) systems, the approximate upper bound to the error probability is twice the lower bound. Hence either can be taken as a good approximation to the actual error probability. The technique is then applied to a model of some promising optical data communication systems and a good approximation to the error probability is obtained. Some observations about the effect of various system parameters on the error probability and some numerical examples are presented.     

基于液晶光阀的可编程光学二值逻辑系统

基于液晶光阀的可编程光学二值逻辑系统张子北，刘立人（中国科学院上海光学精密机械研究所）秦伟芳（中国科学院上海技术物理研究所）摘要基于双轨编码和分束合束，本文提出一种能够实现两个二值输入变量的逻辑系统。通过控制偏振片的偏振方向，该系统能够实现所有十六种...     

Robust least mean logarithmic square adaptive filtering algorithms

The conventional logarithm cost-based adaptive filters, e.g., the least mean logarithmic square (LMLS) algorithm, cannot combat impulsive noises at the filtering process. To address this issue, we present a novel robust least mean logarithmic square (RLMLS) algorithm by using a generalized logarithmic cost function. The proposed RLMLS algorithm can provide robustness against impulsive noises with the improvement of filtering accuracy. For theoretical analysis, the mean square analysis of RLMLS is provided in terms of the mean square deviation (MSD) and excess mean-square error (EMSE) with a white Gaussian reference. For further performance improvement in different noises, the variable step-size RLMLS (VSSRLMLS) based on the statistics of error is proposed to improve the convergence rate and steady-state mean square error, simultaneously. Analytical results and superiorities of RLMLS and VSSRLMLS in the context of system identification are supported by simulations from the aspects of filtering accuracy and robustness in Gaussian and impulse noises.     

Passive optical separation and enrichment of cells by size difference

A size-selective cell sorting microfluidic device that utilizes optical force is developed. The device consists of a three-dimensional polydimethylsiloxane microstructure comprised of two crossed microchannels in a three-dimensional configuration. A line shaped focused laser beam is used for automatic size-selective cell sorting in a continuous flow environment. As yeast cells in an aqueous medium are fed continuously into a lower channel, the line shaped focused laser beam is applied (perpendicular to the direction of flow) at the junction of the two crossed channels. The scattering force of the laser beam was employed to push cells matching specific criteria upward from one channel to another. The force depends on the size of the cells, the laser power, and the fluid flow speed. The variation in size of yeast cells causes them to follow different routes at the intersection. For flow speeds below 30 μm∕s, all yeast cells larger than 3 μm were removed from the main stream. As a result, a high purity sample of small cells can be collected at the outlet of bottom channel.     

公用数据平台下基于小干扰稳定的多机系统PSS参数校核软件模块的开发

电力系统稳定器是抑制电力系统低频振荡的有效工具,但是其工作效果如何需要从全网稳定角度给出评价依据。本文采用小干扰稳定分析理论,基于电力系统公用数据平台,尝试开发了多级系统PSS参数校核软件模块。可为电力系统调度部门方便地提供校验审核PSS整定值的辅助方案。     

高能电子直线加速器束流轨道校正的优化研究

为在高能直线加速器出口获得尽可能好的束流品质,严格控制束流在加速器中的轨道是至关重要的。首先定量研究了束流的初始偏轴和加速器部件的安装误差对束流轨道偏轴的影响,并以北京正负电子对撞机二期工程(BEPCII)的直线加速器为例,给出了上述各种误差导致轨道偏轴的模拟计算结果及其分析。进而讨论了BEPCII直线加速器轨道校正系统的设计研究,给出了轨道校正系统的优化布局和对加速器部件的安装公差要求。