小球藻溶液浓度与吸收系数的同时测量

为得到高准确度的小球藻浓度,利用空芯金属包覆波导作为测量腔对小球藻进行测量.利用自由空间耦合技术激发含有小球藻溶液的空芯金属包覆波导中超高阶导模,通过检测超高阶导模的衰减全反射吸收峰位置和反射极小值Rmin的变化,实现了小球藻溶液浓度和吸收系数的同时测量.该方法不仅可检测10-9 mol量级的小球藻浓度,而且具有测量成本低、操作方便等优点.     

使用相位共轭光精密测量粗糙面物体的振动振幅

提出了一个用于测量粗糙面物体振动振幅的自抽过相位共轭干涉仪,粗糙面反射光的波前失真由相位共轭修复,用这个干涉仪屯一个有粗糙表面的不锈钢片的振动幅分布。     

Fuzzy Modeling and Impulsive Control of a Memristor-Based Chaotic System

We mainly investigate the issues of fuzzy modeling and impulsive control of a memristor-based chaotic system and present a memristor-based chaotic system as the Takagi-Sugeno model-based fuzzy system. Then, based on the impulsive control theory of dynamical systems, a criterion ensuring impulsive stabilization of the memristorbased chaotic system is derived for the first time. An illustrative example is given to verify the effectiveness of the control scheme.     

Computational studies of steady-state sound field and reverberant sound decay in a system of two coupled rooms

The acoustical properties of an irregularly shaped room consisting of two connected rectangular subrooms were studied. An eigenmode method supported by a numerical implementation has been used to predict acoustic characteristics of the coupled system, such as the distribution of the sound pressure in steady-state and the reverberation time. In the theoretical model a low-frequency limit was considered. In this case the eigenmodes are lightly damped, thusthey were approximated by normal acoustic modes of a hard-walled room. The eigenfunctions and eigenfrequencies were computed numerically via application of a forced oscillator method with a finite difference algorithm. The influence of coupling between subrooms on acoustic parameters of the enclosure was demonstrated in numerical simulations where different distributions of absorbing materials on the walls of the subrooms and various positions of the sound source were assumed. Calculation results have shown that for large differences in the absorption coefficient in the subrooms the effect of modal localization contributes to peaks of RMS pressure in steady-state and a large increase in the reverberation time.      

Energy Spectra,g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO3:Cr3+ and SrTiO3:Mn4+ III: R-Line Thermal Shifts of SrTiO3:Mn4+

By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d³ electronic configuration, the values of the parameters in the expressions of thermal shift (TS) from EPI for the ground level, R level and R line of SrTiO₃:Mn⁴⁺ have been evaluated; the R-line TS and various contributions to it have been calculated in the low-temperature region. It is found that all the three terms of R-line TS from EPI relevant to the lattice vibration are red shifts. The Raman term is the largest, the neighbor-level term is the second, and the optical-branch term is very small over the range of T≤80 K. The contribution to R-line TS from thermal expansion has been approximately neglected in this work. The very strong EPI relevant to its lattice vibration for SrTiO₃:Mn⁴⁺ causes its R-line TS to be an unusually large red-shift. Only by taking into account the strong softening of the low-frequency acoustic modes of the lattice vibration at low temperatures, can we successfully explain the variation of R-line TS of SrTiO₃$:Mn⁴⁺ with temperature.     

表面波布拉格声光互作用耦合波方程的研究

定义了压电晶体的增劲声光系数,它反映压电晶体中声光、电光和压电效应共同作用的结果。从参量互作用基本理论出发,同时考虑声光效应、电光效应和压电效应三个因素,用一个压电增劲声光系数来表示三种因素的共同作用,导出表面波声光布拉格互作用的耦合波方程。并求解得出相应衍射效率的计算公式。该式说明在弱声光互作用条件下,衍射导光波强度与超声功率成正比。表面波声光器件具有体积小、工作稳定、能耗小、易于集成等优点。可以用作光偏转器、光调制器、滤光器。在光通信以及各类实时信号处理,如相关、卷积、频谱分析、矩阵光计算等领域具有广泛的应用前景。     

Optically controlled confined potential of a vertically aligned double-dot array system

In a vertically coupled dot, it is expected that generalized Kohn theorem is invalid. Then electron–electron interaction can be observed in far-infrared absorption. This interaction depends on the coupling between dots. We fabricated a vertically aligned double-dot array using a double heterostructure to investigate the coupling. The strength of the coupling depends on the confine potential of the dot. In far-infrared magneto-optical absorption measurements under pulsed photoexcitation, we observed peak shift of asymmetry states and increasing of absorption intensity of symmetry states of the dot. This is a result of the confined potential modulation by light. This indicates the possibility of optical control of the coupling.     

一种含圆柱形谐振散射体的黏弹材料低频吸声机理研究

利用层多重散射法分析了一种含圆柱形谐振散射体黏弹 材料吸声层在钢背衬条件下的低频吸声特性. 该吸声层由包覆软材料的圆柱空腔周期嵌入橡胶材料中构成, 其中, 散射体轴线与吸声层平行. 结果表明, 20 mm厚吸声层在1000–3000 Hz具有良好的吸声性能. 通过综合分析单个散射体的吸收截面、单层周期散射体的声吸收、 结构内部位移场以及耗散功率密度分布, 揭示了该吸声层的低频吸声机理. 关键词： 水声吸声 吸收截面 耗散功率密度     

基于可调谐二极管激光吸收光谱的气池光程可溯源测量

在碳中和的国际大背景下,精确可靠地定量测量大气温室气体浓度对实现碳中和目标具有重要意义,开发测量结果可直接溯源至国际单位制SI的气体分析仪是精确可靠监测温室气体浓度的重要方法。可调谐二极管激光吸收光谱（TDLAS）技术是常用的气体浓度测量方法,根据比尔-朗伯定律,实现仪器的测量浓度直接溯源至SI的必要条件之一是可直接溯源的气池光程,气池光程的不确定度直接影响气体浓度的测量不确定度,对气池光程的可溯源精确测量有利于发展测量结果可直接溯源的气体分析仪。针对光程标称为81 cm的三次反射型气池光程可溯源测量需求,使用校准的米尺测量该气池光程得到的直接测量结果为(81.21±0.80) cm,较大的测量不确定度（0.80 cm）是综合考虑定位误差和三段光路与测量路径可能不重合导致的测量误差估算得到的。为了减小测量不确定度,本文搭建了TDLAS气池光程测量系统,测量系统以1 576 nm分布式反馈激光器为光源,通过在激光控制器上加载斜坡扫描电压来测量待测气池内标准高纯二氧化碳（CO₂,99.999%）在6 344.68 cm-1附近的吸收光谱,使用测量结果可直接溯源的压力传感器和温度传感器分别测量气池内的压强和气体温度,采用美国国家标准技术局最新测量得到的30012-00001跃迁带P 4e支线强（相对标准不确定度为0.15%）反演气池光程,使用二次速度依赖Voigt线型精确拟合不同气压（36~75 Torr）下的光谱吸光度信号获得对应气压的积分吸光度,全面分析各参量的测量不确定度及其传递过程,对不同气压下的积分吸光度进行线性回归分析,计算得到可直接溯源的气池光程为(81.61±0.42) cm,相对标准不确定度为0.51%,测量不确定度范围落在直接测量结果范围内,测量不确定度小于直接测量结果。本文气池的光路结构是多次反射长光程气池的简化,该系统同样适用于多次反射长光程气池光程的可溯源测量。     

可调谐半导体激光吸收光谱技术光信号相关法氨气浓度流速同时测量

利用可调谐半导体激光吸收光谱技术结合光信号相关技术可以实现气体浓度和流速的同时在线测量。文章首先介绍了气体浓度与流速测量的基本原理,然后对在近红外通讯波段附近的NH₃吸收谱线进行分析,并从中选取适合测量的目标谱线,并进行了相应的计算分析。在常温常压下内径为0.016 m长度为1 m的管道内,利用流量计配制出不同浓度以及不同流速的NH₃和N₂混合气体进行相关的试验。利用线宽为15 MHz,可连续调谐范围为1 cm-1的激光二极管对位于6 548.7 cm-1处的NH₃吸收谱线进行快速扫描,采用直接吸收计算的方法测量得到实时气体吸收信号并计算出气体浓度。同时利用非介入式的光信号相关法,通过布置在管道上下游两个探测器探测到的NH₃浓度信号间的相关性,计算得到NH₃气体从上游到下游的渡越时间,进而计算出气体流速。计算得到的NH₃气体浓度值和流速值与流量计标定值之间相比,其相对误差分别在7%和10%之内。测量系统响应迅速,抗干扰能力强,测量结果重复性好,适用于恶劣的现场测量环境,具有很广的工业应用前景。     

二次成形式Coude光学系统的设计、检测与装调

介绍了一台口径为1.23m光电望远镜的Coude光学系统,通过比较国内外地基大口径望远镜Coude光学系统的形式,结合实际情况,设计了以离轴非球面反射镜作为二次成像元件的Coude光学系统,并给出了相应的检测和装调的方法.经实际检测和装调对准后,对Coude光学系统的设计、检测和装调对准过程中的误差进行了分析和比较,证明了检测与装调方法的可靠性和先进性.该Coude光学系统的焦距为125m,视场为1.5′,波段为0.4~5μm,系统波像差优于λ/50(λ=0.632 8μm),实验室内检测波像差为λ/20.装调对准完成后对恒星观测,用Shack-Hartmann波前探测器测量其波前误差,得到整个望远镜Coude光学系统的波像差优于λ/4.     

Measurement of sound absorption by underwater acoustic material using pulse-separation method

An alternative pulse-separation method is presented for measuring the sound absorption at normal incidence of an underwater acoustic material in a water-filled impedance tube. A damped sine pulse was generated in the water-filled impedance tube with a regular waveform and a short duration time of approximately 1 ms. During the generation of the pulse, the inverse filter principle was used to compensate for the transducer response. In addition, the effects of the characteristics of the tube termination can be eliminated during the generation of the pulse to obtain a single plane pulse wave in the impedance tube, which is a necessary condition for this technique. Measurements of the sound absorption coefficient of the rubber material and the reflection coefficient from a water/air interface were used to verify the pulse-separation method.     

Self-localization of whispering-gallery modes in a spherical microcavity filled with a cold electron plasma

We have studied the mechanisms and conditions for self-localization of laser radiation in a cold collisionless electron plasma for a spherical microcavity in the quasistatic approximation, taking into account the appearance of striction nonlinearity and also relativistic effects connected with forced oscillatory motion of the electrons. We have shown that when whispering-gallery modes interact nonlinearly with the electron plasma, a spherical plasmon is excited which is localized within the finite volume of the microsphere. We have established that realization of self-localized spherical structures, in the form of an electromagnetic field and spherical plasmons within a microcavity filled with a cold electron plasma, is primarily due to appearance of relativistic nonlinearity of the medium. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 59–64, January–February, 2006.     

雷达侦察系统参数测量的建模与仿真

在雷达侦察系统工作过程中,对表征敌方雷达信号特征的参数进行测量是后续进行信号分选和辐射源识别的前提条件;首先介绍了相位差测频和相位干涉仪测向的基本原理,然后对常用于表征雷达信号特征的参数的测量过程建立了数学模型,最后对建立的数学模型进行了仿真验证;仿真的结果表明,建立的数学模型能够有效地模拟雷达侦察系统对雷达信号参数的测量。     

First principles study and comparison of vibrational and thermodynamic properties of XBi(X= In,Ga, B,Al)

In the present work, vibrational and thermodynamic properties of XBi(X = B, Al, Ga, In) compounds are compared and investigated. The calculation is carried out using density functional theory(DFT) within the generalized gradient approximation(GGA) in a plane wave basis, with ultrasoft pseudopotentials. The lattice dynamical properties are calculated using density functional perturbation theory(DFPT) as implemented in Quantum ESPRESSO(QE) code. Thermodynamic properties involving phonon density of states(DOS) and specific heat at constant volume are investigated using quasiharmonic approximation(QHA) package within QE. The phonon dispersion diagrams for InBi, GaBi, BBi, and AlBi indicate that there is no imaginary phonon frequency in the entire Brillouin zone, which proves the dynamical stability of these materials. BBi has the highest thermal conductivity and InBi has the lowest thermal conductivity. AlBi has the largest and GaBi has the smallest reststrahlen band which somehow suggests the polar property of XBi materials. The phonon gaps for InBi, GaBi, BBi and AlBi are about 160 cm~(-1), 150 cm~(-1), 300 cm~(-1), and 150 cm~(-1), respectively. For all compounds,the three acoustic modes near the gamma point have a linear behavior. C_V is a function of T~3 at low temperatures while for higher temperatures it asymptotically tends to a constant as expected.     

利用双光子吸收效应测量激光脉冲的相干时间

研究了利用反向泵浦－探测双光子吸收材料的方法来测量脉冲激光的相干时间，并测量量了２３ｐｓ，５３２ｎｍ Ｎｄ：ＹＡＧ激光脉冲的相干时间。实验和理论分析表明，光束相干作用增加了双光子吸收，利用此方法可测量其它脉宽激光的相干时间。     

Orthogonally Linearly Polarized Dual Frequency Nd：YAG Lasers with Tunable Frequency Difference and Its Application in Precision Angle Measurement

The orthogonally linearly polarized dual frequency Nd： YA G lasers with two quarter wave plates in laser resonator are proposed. The intra-cavity variable birefringence, which is caused by relative rotation of these two wave plates in laser inner cavity, results in the frequency difference of the dual frequency laser also changeable. The theory model based on the Jones matrix is presented, as well as experimental results. The potential application of this phenomenon in precision roll-angle measurement is also discussed.     

激光Raman分光计中杂散光的测试、标准及研究方法

本文在文献［１］的基础上，简单综述了激光Ｒａｍａｎ分光计中杂散光的测试方法与技术，介绍了相应的杂散光检测标准，并提出了一种定量研究激光Ｒａｍａｎ分光计中杂散光的实用方法，给出了相应的实验结果。     

Bell Polynomial Approach and N-Soliton Solutions for a Coupled KdV-mKdV System

In fluid dynamics, plasma physics and nonlinear optics, Korteweg-de Vries (KdV)-type equations are used to describe certain phenomena. In this paper, a coupled KdV-modified KdV system is investigated. Based on the Bell polynomials and symbolic computation, the bilinear form of such system is derived, and its analytic N-soliton solutions are constructed through the Hirota method. Two types of multi-soliton interactions are found, one with the reverse of solitonic shapes, and the other, without. Both the two types can be considered elastic. For a pair of solutions to such system, u and v, with the number of solitons N even, the soliton shapes of u stay unvaried while those of v reverse after the interaction; with N odd, the soliton shapes of both u and v keep unchanged after the interaction.     

共心双环外势中两分量偶极玻色-爱因斯坦凝聚体的基态结构研究

利用虚时演化方法研究了共心双环外势中具有偶极-偶极相互作用的两分量玻色-爱因斯坦凝聚体的基态结构, 探索了接触相互作用和长程各向异性的偶极-偶极相互作用对系统基态的影响. 研究发现, 偶极-偶极相互作用作为系统的又一调控参数, 可用于得到系统的不同的基态相, 并用于控制不同基态相间的转化.