含散射闪光照相系统的布局优化

为了提高现有照相系统的图像品质,对使用CCD探测器的法国客体(FTO)照相布局进行了优化,获得最佳图像品质因子下的照相布局。研究结果为:在模糊实验测量结果和高斯分布近似下,系统放大倍率为2.0;后保护器件距离客体50 cm;系统布局总长与探测系统的噪声相关,噪声越大,布局总长越短,最优布局总长的范围为3~5 m;实验验证了这一结果。     

火焰原子吸收光谱法测定砂金中金,银

本文研究了用王水溶解砂金样品，在１％王水介质中，使银生成氯化银沉淀与金定量分离。滤液控制１％王水介质用以测定金。沉淀用５％热硫有脲溶解，控制为１％硫脲介质用以测定银。利用本方法测定了砂金样品中金和银得到了满意结果。金的回收率为９９．６％－１００．８％，银的回收率为９７．２－９９．２％。     

Free energy of segregation at alloy surfaces

The free energy of segregation at semi-infinite solid binary alloy surfaces is calculated using a quasi-chemical approach. The alloy is treated to be a non-regular solution. The concentration is assumed to be different only at the surface layer. The theory is applied to AgAu alloys. The concentration and the short-range-order parameters at the surface are calculated.     

振动盘式粘度计及R403B和R413A气相粘度的实验测量

建立了国内第一台振动盘式粘度计测量气体的粘度，扭丝采用钛镍合金丝．得到了测量的工作方程．在利用测量的ＨＣＦＣ２２的气相粘度进行校核的基础上测量了Ｒ４０３Ｂ在温度３０３－３６３Ｋ，压力０．１～２．１４ＭＰａ 内的气相粘度，及Ｒ４１３Ａ在温度３０５～３６３Ｋ，压力０．１～１．８２ ＭＰａ 内的气相粘度，并回归了其粘度计算方程．     

工作在亚毫米波段的付里叶变换谱仪

本文介绍了我们研制成功的工作在亚毫米波段的付里叶变换谱仪。工作波长为33μm至500μm,分弁率为1cm^-1。本仪器的主要特点是:1,采用微型机控制的数据采集和数据处理;2,动镜采用液压驱动,激光控制取样;3,整个干涉仪置于真空之中,以防水蒸汽的吸收。     

Gauge invariance and the dirac equation

The gauge invariance of the Dirac equation is reviewed and gauge-invariant operators are defined. The Hamiltonian is shown to be gauge dependent, and an energy operator is defined which is gauge invariant. Gauge-invariant operators corresponding to observables are shown to satisfy generalized Ehrenfest theorems. The time rate of change of the expectation value of the energy operator is equal to the expectation value of the power operator. The virial theorem is proved for a relativistic electron in a time-varying electromagnetic field. The conventional approach to probability amplitudes, using the eigenstates of the unperturbed Hamiltonian, is shown in general to be gauge dependent. A gaugeinvariant procedure for probability amplitudes is given, in which eigenstates of the energy operator are used. The two methods are compared by applying them to an electron in a zero electromagnetic field in an arbitrary gauge. Presented at the Dirac Symposium, Loyola University, New Orleans, May 1981.     

基于旋转扫描探头的OCT内窥成像系统设计*

为了同时获取样品的表面和深度信息,研究光学相干层析的成像原理,建立了基于光学相干层析技术的内窥系统,实现了旋转扫描成像,系统的工作波长为1 310 nm,工作带宽为80 nm.理论推导及计算机仿真得到了系统信噪比与干涉仪的分光比、反射率之间的关系并分析了理论分辨率和探测深度.提出外径为5 mm的内窥镜扫描探头,聚焦距离为12 mm,数值孔径NA为0.47,折射率分布常量A=0.218 7.利用微型电机驱动直角棱镜实现扫描,旋转速度为25 rpm,旋转一周得到640个采样点.采用多层盖玻片和洋葱表皮作为样品进行实验分析,得到了盖玻片和洋葱的图像,横向分辨率和纵向分辨率分别为10 μm和15 μm.结果表明,设计的光学相干层析内窥系统能够用于旋转扫描成像,获取更多的组织信息.     

The onset of convection of a poorly conducting fluid in a modulated thermal field

The stability of a poorly conducting fluid in a constant electric field of a horizontal capacitor is investigated under a variable temperature gradient. It is assumed that free charge in the fluid is generated only due to the nonhomogeneous conductivity of the fluid. The Floquet theory is used to determine the convection thresholds. The instability boundaries and the characteristics of critical perturbations are determined. In addition to the synchronous and subharmonic responses to an external action, the instability can be attributed to quasiperiodic perturbations. The low-frequency limit of modulation is considered by an asymptotic method. The critical electric Rayleigh number is represented as a function of inverse frequency and heating level.     

自由空间无衍射光通信模拟系统及其传输性能

无衍射光的中心光斑直径相对于高斯光束较小且发散角为零,在自由空间光通信领域具有良好的应用前景。介绍了一种自由空间无衍射光通信模拟实验系统,它通过串口连接上位机,应用微处理器进行信号的调制与解调,采用双头脉冲间隔调制,无衍射光的发生使用圆锥透镜法,在接收端使用PIN光电二极管将光信号转换为电信号,再经过放大电路、整形电路和微处理器的解调,最后通过串口将数据传输给上位机。上位机通过对发送数据与接收数据的对比计算出误码率,进而给出整个系统的传输性能评价。在无衍射光的最大传输距离内,当比特率为9 600 bps时,该系统的误码率优于610-5。     

Automatic Classification of Healthy Subjects and Patients With Essential Vocal Tremor Using Probabilistic Source-Filter Model Based Noise Robust Pitch Estimation

Essential voice tremor (EVT) is a voice disorder resulting from dyscoordination within the laryngeal musculature. A low-frequency fluctuations of fundamental voice frequency or the strength of excitation amplitude is the main consequence of the disorder. The automatic classification of healthy control and EVT is useful tool for the clinicians. A typical automatic EVT classification involves three steps. The first step is to compute the pitch contour from the speech. The second step is to compute the features from the pitch contour, and the final step is to use a classifier to classify the features into healthy or EVT. It is shown that a high-resolution pitch contour estimated from the glottal closure instants (GCIs) is useful for EVT classification. The HPRC estimation can be very poor in the presence of noise. Hence, a probabilistic source filter model based noise robust GCI detection is used for HPRC estimation. The Empirical mode decomposition based feature extraction is used followed by a support vector machine classifier. The EVT classification performance is evaluated using recordings from 45 subjects. The proposed method is found to perform better than the baseline techniques in eight different additive noise conditions with six SNR levels.     

High-Breakdown-Voltage Submicron InGaAs/InP Double Heterojunction Bipolar Transistor with ft=170GHz and fmax=253GHz

The layer structure of InGaAs/InP double heterojunction bipolar transistor (DHBT) is designed to enhance the frequency performance and breakdown voltage. The composition-graded base structure is used to decrease the base transit time. The InGaAs setback layer and two highly doped InGaAsP layers are used to eliminate the conduction band spike of the collector. The submicron-emitter InGaAs/InP DHBT is fabricated successfully. The base contact resistance is greatly decreased by optimization of contact metals. The breakdown voltage is more than 6V. The current gain cutoff frequency is as high as 170GHz and the maximum oscillation frequency reached 253GHz. The DHBT with such high performances can be used to make W-band power amplifier.     

两个玻色-爱因斯坦凝聚体间相互作用的数值研究

本文采用辛算法数值求解一维含时Gross-Pitaevskii(GP)方程.研究了存在陷俘势和撤掉陷俘势时两个凝聚体间的相互作用.发现当存在陷俘势时两个凝聚体间发生弹性碰撞;在零时刻撤掉陷俘势时两个凝聚体间发生干涉现象;当t=2时撤掉陷俘势两个凝聚体间发生了复杂现象.     

A theoretical study of radiation between two concentric spheres using a modified discrete ordinates method associated with Legendre transform

A modified discrete ordinates method (DOM) is used in spherical participating media. The radiative intensity is broken up into two components. One component is traced back to the enclosure's source. It is called direct intensity. The other component is rather traced back to the contribution of the medium itself. It is called diffuse intensity. Thus, the radiative transfer equation (RTE) is transformed into two simultaneous equations: a direct RTE and a diffuse RTE. The direct RTE is solved analytically. The diffuse RTE is solved numerically using the DOM. The streaming angular derivative term appearing in spherical geometry is modeled by making use of the Finite Legendre Transform. We study a pure radiation transfer problem between two concentric spheres. The medium is assumed to be gray and isotropically scattering. The limiting spheres are considered to be opaque, gray, diffusely emitting and diffusely reflecting with uniform emissivity over each surface. The obtained results are compared with available cases reported in the literature. In particular, relative importance of the direct radiation in optically thin media is studied.     

Entropic Dynamics: Quantum Mechanics from Entropy and Information Geometry

Entropic Dynamics (ED) is a framework in which Quantum Mechanics (QM) is derived as an application of entropic methods of inference. The magnitude of the wave function is manifestly epistemic: its square is a probability distribution. The epistemic nature of the phase of the wave function is also clear: it controls the flow of probability. The dynamics is driven by entropy subject to constraints that capture the relevant physical information. The central concern is to identify those constraints and how they are updated. After reviewing previous work I describe how considerations from information geometry allow us to derive a phase space geometry that combines Riemannian, symplectic, and complex structures. The ED that preserves these structures is QM. The full equivalence between ED and QM is achieved by taking account of how gauge symmetry and charge quantization are intimately related to quantum phases and the single‐valuedness of wave functions.     

激光测距机三轴平行性智能检测校正方法研究

提出了一种激光测距机三轴平行性智能的检测校正方法。建立了光轴平行性偏差与偏心环(框)旋转角度之间的数学模型,利用传感器得到激光发射轴与瞄准轴之间的平行性偏差,根据所建立的数学模型计算出偏心环(框)需要调整的角度值,利用步进电机使偏心环(框)转动相应的角度,从而物镜产生径向移动,实现激光测距机光轴的校正。此方法在检测激光测距机光轴平行性的同时实现了光轴的自动校正,也适用于其它具有双偏心结构的光学仪器。     

Extension of Operational Matrix Technique for the Solution of Nonlinear System of Caputo Fractional Differential Equations Subjected to Integral Type Boundary Constrains

We extend the operational matrices technique to design a spectral solution of nonlinear fractional differential equations (FDEs). The derivative is considered in the Caputo sense. The coupled system of two FDEs is considered, subjected to more generalized integral type conditions. The basis of our approach is the most simple orthogonal polynomials. Several new matrices are derived that have strong applications in the development of computational scheme. The scheme presented in this article is able to convert nonlinear coupled system of FDEs to an equivalent S-lvester type algebraic equation. The solution of the algebraic structure is constructed by converting the system into a complex Schur form. After conversion, the solution of the resultant triangular system is obtained and transformed back to construct the solution of algebraic structure. The solution of the matrix equation is used to construct the solution of the related nonlinear system of FDEs. The convergence of the proposed method is investigated analytically and verified experimentally through a wide variety of test problems.     

基于后推式航空数字相机像移补偿试验及效果评价

分析了航空数字相机像移的产生机理,提出了一种后推式像移补偿方法。搭建了航空数字相机的航拍仿真试验台,通过微米电机控制相机镜头反向运动的补偿速度和补偿量,实现后推式像移补偿。利用图像清晰度评价补偿前后的图像效果,补偿后像移残差值低于1/3像素。最后给出了后推式补偿方法与软件补偿方法的对比,结果表明,后推式补偿方法在补偿精度方面优于软件补偿方法,说明了该方法的可行性。     

The bobylev approach to the nonlinear Boltzmann equation

The Bobylev approach to the nonlinear Boltzmann equation is reviewed. The linearized problem is discussed and it is shown that eigenfunctions decaying like a negative power of the velocity are possible with Maxwell molecules only. The relaxation to equilibrium according to the nonlinear equation is discussed and the Krook-Wu conjecture on the status of the BKW mode is shown to be false in general. The buildup of the high-energy tails is considered and a phenomenon observed by Tjon is given a simple explanation. Finally, the method is illustrated with numerical calculations performed for two sets of initial conditions.     

S-Matrix to potential inversion at fixed energy: (II). Inclusion of spin ; CRC effects in proton scattering

The iterative-perturbative inversion procedure is generalized to spin-half particles leading to an effective and reliable means of pursuing fixed energy S-matrix to potential inversion. The reliability and uniqueness of the inverted potentials is discussed. The method is used to throw light on the contribution of pickup coupling to the nuclear optical potential, and connection is made with previously published phenomenology. It is shown that repulsion induced by coupled channels can have a different origin in different cases. The formalism for extending the IP inversion method to general spin is briefly described.     

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。