Cu-Pd/MCM-22催化剂上二甲醚低温水解反应

 考察了分子筛的类型、硅铝比及Cu和Pd改性对分子筛催化剂上二甲醚低温水解活性的影响. 结果表明,酸性的MCM-22和HZSM-5分子筛催化剂具有较高的二甲醚水解活性,且其活性随着分子筛硅铝比的增加而降低. 这表明分子筛的类型及酸性对催化剂性能有重要影响,具有超笼结构的MCM-22分子筛上B酸中心的良好可接近性,使得该分子筛催化剂的水解活性较相同硅铝比的HZSM-5分子筛高. 与改性前相比, Cu和Pd改性后的MCM-22催化剂显示出更高的二甲醚水解活性.     

角锥棱镜腔激光二极管抽运被动调Q激光器

为了提高传导冷却条件下激光二极管(LD)侧向抽运被动调Q激光器的光束质量和输出稳定性,采用了两组半圆柱面激光二极管阵列侧向交错抽运两根串接的激光棒,实现了均匀抽运和散热。通过实验分析了横模结构对被动调Q稳定性的影响,设计了角锥棱镜-高斯输出镜非稳腔,在显著提高器件光束质量的同时,明显改善了被动调Q的稳定性,并保证了谐振腔的机械稳定性。在此基础上研制了一台重复频率20 Hz、单脉冲能量64 mJ、脉冲宽度7 ns、稳定性优于±5%、光束发散角0.6 mrad、光-光效率9.1%,且光轴指向稳定的工程实用器件。     

Analysis of scattering wave for a conducting cylinder coated with eccentric plasma

Object coated with plasma has stimulated great interests of many people because of its stealth capability. The study on a conducting cylinder coated with coaxial plasma is very much, but there are little works on a conducting cylinder coated with eccentric plasma. In this article, a model for a conducting cylinder coated with eccentric unmagnetized plasma is set up, the scattering cross section of the object cylinder is studied by adopting the superposition of cylindrical wave functions and the coordinate transformation, where these wave functions are the solutions of Maxwell's equations with boundary conditions in cylindrical coordinates. The results show that the radar cross section for a conducting cylinder coated with eccentric plasma in every direction decrease obviously with an increase of the distance between two eccentric axes, but is almost not impacted by electron–neutral collision frequency of plasma, and the backscattering cross section of the target reduce with the increase of electron density. Comparing with the coaxial model, the backscattering cross section of the eccentric model has a smaller value in a wide frequency band. This is of significance for the target plasma stealth technology in practice.     

On the rate of convergence of weak Euler approximation for nondegenerate SDEs driven by Lévy processes

The paper studies the rate of convergence of the weak Euler approximation for solutions to SDEs driven by Lévy processes, with Hölder-continuous coefficients. It investigates the dependence of the rate on the regularity of coefficients and driving processes. The equation considered has a nondegenerate main part driven by a spherically symmetric stable process.     

High-resolution Reflection Spectroscopy of Cs D2 Line Studied by High-order-harmonic Detection

In this paper, by numerical analysis the relationship of the modulation broaden index with modulation index using high-order-harmonic detection is investigated. Using the voltage modulation the 2f,4f and 6f harmonic signals about the reflection spectroscopy of 6S1/2(F=4)→6P3/2 transition of the cesium D2 line are also be measured. The experimental results are in good agreement with the theoretical predictions. It is found that narrower line-width can be achieved by higher-harmonic detection than the line-width detected by direct absorption when the modulation index is smaller than 1.81, 2.98 and 4.14 for 2f, 4f, and 6f signals, respectively.     

靶材料BRDF现场模拟测量

介绍一种利用频率调制光谱技术,在自然环境光下进行材料双向反射分布函数(BRDF)的测量方法.用该方法对若干墙面靶材料的反向散射双向反射分布函数进行了测量,并给出了被测材料的BRDF拟合函数参量.测量环境模拟了以墙面材料为反射靶的激光现场遥感探测气体测量环境,其结果对此类探测仪器的设计具有指导意义.     

双参数形变谐振子湮没算符高次幂的本征态

构造了双参数形变谐振子湮没算符高次幂aqsk(k≥3)的本征态,并利用qs积分给出了其完备性的证明.     

Reconfigurable Assembly of Active Liquid Metal Colloidal Cluster

We report the reconfigurable assembly of rod-shaped eutectic gallium–indium alloy (EGaIn) liquid metal colloidal motors by mimicking the growth behavior of a dandelion. EGaIn nanorods with a diameter of 210 nm and a length of 850 nm were synthesized via an ultrasound-assisted physical dispersion method. The nanorods possess a core–shell structure with a 30 nm GaOOH shell and zero-valent liquid core. The EGaIn motors move autonomously at a speed of 41.2 μm s⁻¹ under an acoustic field. By modulating the frequency of the applied acoustic field, the EGaIn colloidal motors self-organize into various striped and circular patterns, followed by a flower-like cluster. The dandelion-like EGaIn colloidal motor clusters move collectively and redisperse when the applied acoustic frequency is changed. Numerical simulations reveal that the flower-like clusters are created by the acoustic propulsion in combination with steric repulsion and hydrodynamics.     

Algebraic Properties of Generalized Toeplitz Operators

§ 1.Introduction　 Let D be the unit disk of the complex plane C,T the unit circle,and H2 the Hardyspace of the unit circle.For operators on H2 ,all matrices in the sequel will be formedwith respect to the basis { e0 ,e1 ,… } defined by en(z) =zn,n=0 ,1 ,2 ,… . Ifφ∈ L∞ (T) ,write Tφfor the corresponding Toeplitz operator defined on H2 by Tφf=P(φf) (where Pis the projection from L2 (T) onto H2 ) .The Toeplitz operator Te1,the so called unilat-eral shift,will be denoted by U thr…     

消除波长调制光谱中激光能量起伏对谐波信号干扰的新技术

利用扫描外腔二极管激光器(ECDL）后镜压电陶瓷(PZT）电压时频率变化和背景能量起伏之间存在相位差的特性,通过矢量锁相放大器将一个探测器探测到的信号成份和背景起伏噪声分开,获得标准的1f~4f信号.如果不存在这个相位差,则无法消除谐波信号背景干扰.这种技术简单、实用,对理论分析谐波信号以及实现高灵敏探测污染气体传感器的小型化都有重要的指导意义.