红外图像的各向异性分段高斯滤波

提出了一种各向异性分段高斯滤波,这种方法除了考虑图像的尺度和方向特性外,还根据边缘区域可分特性,使用了分段滤波的方法来进一步解决边缘保持的问题.该方法通过本文所提出的一种图像噪音方差估计模型来确定图像的基准尺度,并由Hermite变换得到其方向角,然后再通过确定高斯模型的轴向比和自适应尺度,使对选择区域的滤波转变为对分段高斯模型的滤波,从而使计算的可靠性得到增强.从仿真结果可以看出,各向异性分段高斯滤波器在噪音去除和边缘保持的综合性能上要优于其他常用的滤波算法.     

Spatial Temporal Analysis of Electrically-Addressable Phase-Only Spatial Light Modulator

An optically addressed parallel-aligned nematic-liquid-crystal spatial light modulator (PAL-SLM) has been studied as a dynamic phase-only modulation device. A computer control feature of the spatial light modulator is strongly desired for practical applications. For those demands, an electrically-addressable phase-only spatial light modulator has been developed to combine a liquid crystal display (LCD) with a PAL-SLM (LCD-coupled PAL-SLM) and its performance has been reported. However, a temporal characteristic especially two-dimensional (2D) response has not been discussed before. In this paper, 2D response analysis system has been constructed by using a high-speed complementary Metal-Oxide-Semiconductor (CMOS) camera (1000 frames/sec) and the 2D-modulation characteristic of the LCD-coupled PAL-SLM has been observed. As a result, the LCD has a spatially non-uniform modulation characteristic due to a scanning addressing. It has the potential to cause problems in high speed switching for a computer generated hologram. On the other hand, the spatial non-uniformity has not been observed with the LCD-coupled PAL-SLM.     

A kinetic model of the reaction of dispersed aluminum with water under exposure to hydrocavitation and stabilization of the final product

The reaction of dispersed aluminum with water under the exposure of an A-IX-2 aluminum-containing explosive compound to hydrocavitation has been discussed. A kinetic model of the process has been developed; the chemical reaction rate constant has been determined under experimental conditions. It has been shown that the reaction occurs in an autocatalytic mode and can lead to the complete conversion of aluminum to aluminum hydroxide. A method to stabilize dispersed aluminum during the hydrocavitational extraction of a conversion explosive by using a phosphate buffer has been developed. Experiments have shown that the phosphate buffer has a stabilizing effect and leads to an improvement of the characteristics of the resulting industrial explosive composition.     

Magnetic structure of the compensated ferromagnet-multiferroic interface

The magnetic structure of the compensated ferromagnet-multiferroic interface has been considered. The law governing the decrease of distortions of magnetic order parameters with increasing distance from the interface has been found. An expression for the energy of interlayer interaction of magnetic order parameters has been derived, and it has been shown that its magnitude is determined by the exchange interaction. The condition for magnetization switching of the ferromagnetic layer by an electric field applied to the multiferroic layer has been formulated. It has been demonstrated that the magnetoelectric effect and weak ferromagnetism are not prerequisites to the development of electric field-switchable magnetoresistive memory.     

The phase transition in annealed mechanically alloyed Fe - Cu

Using M?ssbauer spectra and x-ray diffraction patterns, annealed mechanically alloyed Fe - Cu has been investigated in this paper. It is found that in [Formula: see text], after it has been milled, fcc-Cu has transformed into bcc-Cu, and some Cu atoms have diffused into the Fe. After the alloy has subsequently been annealed, it is found that bcc-Cu has transformed back into fcc-Cu, while the Cu atoms in the Fe have been separated. In [Formula: see text], after being milled, an fcc-Fe-rich phase has been formed, and after the alloy has subsequently been annealed, this has transformed back to bcc-Fe. The shorter the milling time and the higher the annealing temperature, the faster the transformation. In [Formula: see text], after it has been annealed, the fcc-Fe-rich phase has transformed to bcc-Fe also, and the fcc-Cu-rich phase remains when the annealing temperature increases. All of these results show that the fcc-Fe-rich phase in the milled samples is a metastable phase - it will transform to stable bcc-Fe when it is annealed - while the long-milling-product fcc-Cu-rich phase is a stable phase.     

Dual Superconductivity in Abelian Higgs Model of QCD

The study of generalized field associated with Abelian dyons has been undertaken and it has been demonstrated that topologically, a non-Abelian gauge theory is equivalent to a set of Abelian gauge theories supplemented by dyons which undergo condensation leading to confinement and consequently to superconducting model of QCD vacuum, where the Higgs field plays the role of a regulator only. Constructing the effective action for dyonic field in Abelian projection of QCD, it has been demonstrated that any charge (electrical or magnetic) of dyon screens its own direct potential to which it minimally couples and anti-screens the dual potential leading to dual superconductivity in accordance with generalized Meissner effect. In this Abelian projection of QCD an Abelian Higgs model (AHM) has been successfully constructed and it has been shown to incorporate dual superconductivity and confinement as the consequence of dyonic condensation. It has been demonstrated that in AHM t’ Hooft loop creates the string (AHM-string) around which the monopole current under London limit leads to vanishing coherence length in the chromo-magnetic superconductor. It has also been shown that in London limit the squared density of monopole current around AHM-string has a maximum at the distance of the order of penetration length.     

基于LabVIEW和声卡的音频信号采集与分析系统设计

详细介绍了系统的开发背景,软件结构和特点,系统地分析了数据采集硬件和软件设计技术,在此基础上以声卡为数据采集卡,以LabVIEW为开发平台设计了音频信号采集与分析系统。这种系统具有界面友好,维护简单等优点。系统不但可以实现对音频信号进行采集,还可以对采集的信号进行分析和保存。可以根据需要改变系统的功能,具有很好的教学实...     

Thermoluminescence of x-irradiated CaSO4:Dy phosphors and role of Na2SO4 as a charge compensator

The thermoluminescence of x-irradiated CaSO₄: Dy phosphors has been studied for diverse activator concentrations. The concentration-dependence of these phosphors on the increase of glow peak intensities has been found to be remarkable. For higher concentration of dysprosium the concentration quenching effect has been observed. This has been attributed to the resonant transfer of energy from one activator atom to another, bringing the possible migration of energy in a solid, which is likely to get dissipated without luminescence, at the quenching site itself. The effect of irradiation time on the glow peak intensities reveals the initial linearity and a subsequent decrease indicating the possible radiation damage. The role of Na₂SO₄ as a charge compensator has been studied in detail. An attempt has been made to unravel the type of kinetics involved in the process, by calculating the activation energies by different methods. It has been concluded that the type of kinetics involved in the process is bimolecular.     

单、双转子轴流风扇的内流特性与性能实验研究

本文针对某大型空调室外风扇系统采用双转子风扇时存在的体积大、风量不足和噪声大的缺陷,提出了采用单 转子风扇改进的措施,利用相似理论和CFD内流模拟方法,进行了内部流动的细节分析,并进行了性能、噪声实验,为 产品的更新和性能的改善提供了依据,投入使用取得了良好的经济效益。     

Laser Doppler velocimetry analysis of transitional pipe flow

The objective of this study has been to experimentally analyze the correlation structure of the strong temporal intermittency which characterizes pipe flow close to the transition to turbulence. In doing so transitional pipe flow has been analyzed by Laser Doppler velocimetry and the Reynolds number dependence of the covariance function has been studied. The range which has been analyzed covers the transition to turbulence and moderately developed turbulence (Reynolds number from 1 500 to 5 000). The correlation structure which has been evidenced is generally in agreement with the deterministic, dynamical, interpretation of temporal intermittency which explains the intermittent behavior as a result of a saddle node bifurcation. However, the analysis has evidenced fluctuations even before the onset of turbulence. The structure of these fluctuations is perfectly autoregressive which leads us to conclude that the transition to turbulence can be viewed as a transition from linear randomness to (non-linear) homogeneity. Received 29 March 1999 and Received in final form 6 September 1999     

Workshop Nanoscience B: Self-Assembly-from molecules to materials

In recent years, there has been growing interest in the design of electron accelerators in order to reduce beam emittance and to increase photon brilliance (from third-generation synchrotron sources to free electron lasers). This has increased the coherent properties of the beam and has opened up new branches of microscopy and spectroscopy at nanometer-length scales. The X-ray nano probe is going to be an important tool for future research, hence there has been substantial research carried out in order to develop nano focusing optics of diffraction-limited performance.     

The tube peeper: a new concept in endoscopy

In conventional endoscopy the imaging device has to rotated to produce a full 360° image. A new ‘tube peeper’ has been devised that can view the whole panoramic field simultaneously. The image produced has flat cylinder perspective rather than the familiar central convergence perspective.The device is simpler to manufacture than conventional ones, and has the potential for miniaturization     

稀土和锕系化合物中重费密子行为

本文采用周期Anderson哈密顿量研究了稀土和锕系化合物中的重费密子行为。对f电子间库仑关联项做了平均场近似并引入自能项反映多体作用的效应。对自能项采用了单格位近似,在准粒子表象中讨论了系统的性质,通过对f电子平均占据数的自洽计算,得到了准粒子有效质量,讨论了形成重费密子的条件,以及相应的磁性的变化,并做了数值计算。所得结果与最近的实验进行了比较。 关键词：     

Charge stripping accumulation of light heavy ions in HIRFL-CSR main ring

The charge stripping injection method has been adopted for the accumulation of light heavy ions in HIRFL-CSR. This method has some special requirements for the accelerating particles, and at the same time the structure of the injection orbit has to be changed. In this paper, the design of the orbit has been presented, as well as the calculation of the beam line matching. According to the result of commissioning, stripping injection can accumulate the beam to a higher current.     

Quasi-phase-matched modulation instability in birefringent fibers

The phase-sensitive nature of polarization modulation instability has been demonstrated in optical fibers whose birefringence has been manipulated to generate phase mismatches. Quasi-phase-matched modulation instability has been demonstrated, and the gain of the quasi-phase-matched sidebands has been investigated. The results are in good agreement with experiment.     

A COAXIAL MAGNETRON INJECTION GUN (CMIG) FOR A 2 MW, 170 GHz COAXIAL CAVITY GYROTRON

An electron gun (80 kV / 75 A) for a 170 GHz coaxial cavity gyrotron has been designed, fabricated and tested. Special care has been devoted to the design of the technical part of the electron gun in order to avoid trapping of electrons, which may result in a limitation of the high voltage performance due to built-up of a Penning discharge which may limit the high voltage performance. The performance of the electron gun and electron beam has been found to be well in agreement with the design objective. A stable operation up to I_b = 80 A and U_c = 80 kV has been obtained without any observable beam instabilities. No limitations in high voltage performance due to built-up of a Penning discharge occurred. The influence of the type of electron flow on gyrotron performance has been studied experimentally. The maximum output power has been obtained for an intermediate type of flow.     

力调制显微术在台阶边缘附近的边界效应

力调制显微术被用于观测铜基碳化硅样品，实验中发现在样品表面台阶边缘处出现一些异常信息。为此，文章作者通过测试一种表面同样有台阶但却是由同一种材料组成的样品来通信验证这些异常主要是由台阶的边界引起的，并对引起的异常作了半定量的估算。     

The study of anharmonic properties and s-p-d hybridization in barium at extreme environment

Theory of pseudopotential has been used in the present study to carry out computation of various thermodynamic parameters of barium. The role of anharmonic effect due to vibrations of lattice ions has been accounted by coupling local pseudopotential with mean field potential which has been computed using second-order perturbation theory. Contribution due to thermally excited electrons has been accounted by Mermin functional. The excellent agreement of presently computed pressure with experimental result has also been observed at which body centered cubic to hexagonal close packed structure phase transition occurs. Such success leads to conclude that the s-p-d hybridization and anharmonic effects are included properly in the presently used conjunction scheme with additional advantage of its computational simplicity.     

Extremely short vector solitons under the conditions of conical refraction

Propagation of extremely short electromagnetic pulses in a biaxial crystal under the conditions of conical refraction has been considered. The system of wave equations taking into account the dispersion contribution of the crystal lattice ions to the polarization response of the medium and a nonlinearity of the polarization response of electrons has been derived. It has been shown that under certain conditions this system can be reduced to an equation which is integrable by means of the inverse scattering transformation method. The proper Lax pair has been found. Physical analysis of the steady-state pulse solution of the system of wave equations has been performed.     

Hole drilling studies with a variable pulse length CO2 laser

A transversely excited CO₂ laser has been used to investigate the interaction between laser pulses of duration ≈ 40 μs, and metallic targets. The dependence of machining efficiency on power density has been studied, and high speed photography has been used to compare interactions with different pulse durations. Metallurgical analysis has revealed important structural effects in both mild steel and aluminum samples.