双通道数字红外辐射计的研究

 针对目前所使用的红外辐射强度测试系统的不足,提出双通道数字红外辐射计的方案,即在同一红外辐射计中设计两套相互独立的红外辐射强度测试通道,在红外辐射产品点火试验测试中,双通道测试同时工作,同时进行数据采集。用研制的双通道数字红外辐射计分别在室温（25℃）和低温（-15℃）条件下进行6次对比试验,结果表明：两系统测试的误差小于5%,双通道数字红外线辐射计两通道之间误差小于5％,原1905A测试系统出现2次漏测,双通道数字红外辐射计无漏测。     

Stochastic resonance in an ion channel following the non-Arrhenius gating rate

Stochastic resonance (SR) is a novel cooperative phenomenon occurring in nonlinear systems due to coupling of an ambient noise and an external signal. Biological systems may use SR mechanism to detect the signal efficiently from an external environment. A number of studies have addressed the SR in artificial ion channels considering external voltages as noises. More important than these external noises is the internal, thermal noise which changes the channel conformations essential for biological functions. In this work, we consider that the channel gating rates follow a non-Arrhenius temperature dependence derived from experimental data of a real biological channel. Using the Monte-Carlo simulations, we find that in this channel SR occurs near a physiological temperature in a very distinctive manner compared with that for the Arrhenius gating model.     

Probabilistic models for stochastic elliptic partial differential equations

Mathematical requirements that the random coefficients of stochastic elliptical partial differential equations must satisfy such that they have unique solutions have been studied extensively. Yet, additional constraints that these coefficients must satisfy to provide realistic representations for physical quantities, referred to as physical requirements, have not been examined systematically.     

Design of Hamming Code Checker Using Titanium-Diffused Lithium Niobate-Based Waveguide

ABSTRACT

This work presents an electro-optic effect-based design for the widely used Hamming code for checking single bit errors in the received data. The structure is based on Mach-Zehnder Interferometer, designed using Titanium-diffused Lithium Niobate-based waveguides. The proposed device has been successfully tested using the beam propagation method. For a received 7-bit code, the three simultaneously generated check bits are combined to check the error position. Critical performance parameters like extinction ratio (24.39dB), contrast ratio (25.711dB), insertion loss (0.041dB), and amplitude modulation (0.079dB) calculated for the overall device are within acceptable limits for the feasibility of the device.     

利用调整技术补偿离轴抛物面反射镜面形误差

为了提高光学系统的成像质量,对离轴抛物面反射镜的面形准确度要求越来越高,这大大增加了反射镜的加工难度.本文基于波像差理论,分析了在离轴抛物面反射镜中调整量引入的波像差,提出通过适当调整离轴抛物面反射镜的位置补偿反射镜的面形误差,可以降低离轴反射镜的加工难度、缩短其加工周期、减少加工成本.并借助于ZEMAX软件对一块面形准确度低于λ/40 RMS (λ=632.8 nm)离轴抛物面反射镜进行仿真实验,根据理论计算的调整量调整反射镜的位置,得到了补偿后的离轴抛物面反射镜的面形误差小于λ/60 RMS,仿真结果表明在离轴抛物面反射镜中引入适当的调整量可以有效地补偿反射镜的面形误差.     

反射式光学电压互感器光路建模及偏振误差分析

光路系统的偏振误差极大地制约着准互易反射式光学电压互感器的准确度.借助琼斯矩阵,建立了分立光学器件及光纤熔接点的传输模型,推导出完整的电压互感器光路系统的数学模型.以此模型为基础,对电压互感器中的偏振误差进行了仿真分析.结果表明：光源偏振度、起偏器消光比及起偏器与相位调制器的对轴角度主要影响系统的检测灵敏度|法拉第准直旋光器的旋光角度、法拉第准直旋光器与BGO晶体的对轴角度误差是主要的偏振误差源,影响系统的测量准确度及稳定性|根据电子式电压互感器IEC60044-7 0.2S级标准,法拉第旋光角度误差应该小于1.6°,旋光器与BGO晶体对轴角度误差小于1.85°.该研究对准互易反射式光学电压互感器光路设计和误差抑制具有一定的参考价值和指导意义.     

Adiabatic approximation in PT-symmetric quantum mechanics

In this paper, we present a quantitative sufficient condition for adiabatic approximation in PT-symmetric quantum mechanics, which yields that a state of the PT-symmetric quantum system at any time will remain approximately in the m-th eigenstate up to a multiplicative phase factor whenever it is initially in the m-th eigenstate of the Hamiltonian. In addition, we estimate the approximation errors by the distance and the fidelity between the exact solution and the adiabatic approximate solution to the time evolution equation, respectively.     

An Error Analysis for the Finite Element Approximation to the Steady-State Poisson-Nernst-Planck Equations

Poisson-Nernst-Planck equations are a coupled system of nonlinear partial differential equations consisting of the Nernst-Planck equation and the electrostatic Poisson equation with delta distribution sources, which describe the electrodiffusion of ions in a solvated biomolecular system. In this paper, some error bounds for a piecewise finite element approximation to this problem are derived. Several numerical examples including biomolecular problems are shown to support our analysis.