运动表面风力机翼型的气动性能研究

本文通过数值模拟,研究了S809翼型表面沿切向顺时针方向速度运动时的气动性能.从计算结果看出,翼型表面运动能有效抑制或延缓大攻角流动分离,改善翼型的气动性能。在此基础上,为了仅考虑表面的运动效应,消除翼型几何外形对升阻力系数的影响,本文还研究了皮带轮翼型(由大小两个圆柱驱动的皮带轮)的气动特性。计算结果进一步表明,表面运动能有效地抑制翼型吸力面发生大规模流动分离,并可极大地增加翼型升力系数。     

多帧融合处理技术在运动模糊图像复原中的应用

运动模糊图像是电视监控中常见的退化图像 ,也是图像处理和检验工作中的难题。针对电视摄像的特点 ,多帧融合处理技术从图像时间序列中提取景物的运动信息 ,构造复原滤波器 ,通过频率域反转滤波方式复原模糊图像。这项技术能够有效地增强电视监控中存在的运动模糊图像 ,并且适用于数字视频图像处理     

Stability of Motion of a Nonholonomic System

Perturbation differential equations of motion of a general nonholonomic system subjected to the ideal nonholonomic constraints of Chetaev＇s type are established, and the equation of variation of energy is deduced by using the perturbation equations of the system. A criterion of the stability is obtained and an example is given to illustrate the application of the result.     

WDP-500C型平面光栅单色仪应用于实验教学的技术问题

针对WDP-500C型平面光栅单色仪未设有千位数字,致使其报警时不能正确处理的问题,提出了根据滑块的传动距离加长挡光板或将光电报警开关向短波段移动8.0 nm的解决方案,消除了由于单色仪设计问题而产生的故障.     

Research of the planar optical fiber Bragg grating hydrophone probe

This paper presents the planar Fiber Bragg Grating （FBG） hydrophone probe sensing principle, and theoretically and experimentally researches the probe structure sensitivity, the receiving sensitivity frequency response characteristic and the acceleration response property. Planar sheet is made of stainless steel, its thickness is 0.15 mm, its diameter is 15mm, and the length of hollow circular shell is 20 mm. For this size of the structure, the probe structure sensitivity is up to 23 fm/Pa, which is about 7300 times of the value of the bare fiber. The resonance frequency is 6.5 kHz, and the amplitude-frequency curve of the receiving sensitivity response is relatively flat within the frequency range of 100 Hz to 5.5 kHz. The output yielded by one unit acceleration （1m/s2） is equivalent to （2.52 to 3.26 Pa） acoustic pressure acting output. This probe structure is easy to form FBG hydrophone array by multiplexing technique. The research shows that this planar structure not only can form FBG hydrophone probe, but also can constitute optical FBG laser hydrophone probe. The structure can realize different bandwidth, different range acoustic pressure measurement by adjusting the geometrical size of the sheet.     

A planar chiral nanostructure with asymmetric transmission of linearly polarized wave and huge optical activity in near-infrared band

Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength （1.55 μm）. Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism.     

Interplay between out-of-plane magnetic plasmon and lattice resonance for modified resonance lineshape and near-field enhancement in double nanoparticles array

Two-dimensional double nanoparticle （DNP） arrays are demonstrated theoretically, supporting the interaction between out-of-plane magnetic plasmons and in-plane lattice resonances, which can be achieved by tuning the nanoparticle height or the array period due to the height-dependent magnetic resonance and the periodicity-dependent lattice resonance. The interplay between the two plasmon modes can lead to a remarkable change in resonance lineshape and an improvement on magnetic field enhancement. Simultaneous electric field and magnetic field enhancement can be obtained in the gap region between neighboring particles at two resonance frequencies as the interplay occurs, which presents “open” cavities as electromagnetic field hot spots for potential applications on detection and sensing. The results not only offer an attractive way to tune the optical responses of plasmonic nanostructure, but also provide further insight into the plasmon interactions in periodic nanostructure or metamaterials comprising multiple elements.     

研究平抛运动实验方案的改进

目前数字化实验器材尚未普及,对于高中研究平抛运动实验,存在着各学校所用器材不统一,操作步骤繁琐,轨迹点定位效果不理想的缺点,基于这些原因,对教材中的方案二实验装置进行了改进.改进的装置由喷水装置、绘图板和直角坐标测量装置组成,改进后的装置具有操作简便,轨迹点坐标定位准确等特点.     

Beam Parameters for End Diffraction of TE0 Mode of Planar Waveguide

The relation between diffractive beam parameters and normalized frequency is analyzed that leads to two improved Tormulas for two kinds of mode-field halT-widths and several formulas for divergence angle as well as beam propagation factor. The numerical calculation indicates that the maximal relative error is less than 0.5% within a reasonable parameter range.     

如此证明等时性合理吗

人教版高一物理教材《必修2》第五章第二节“质点在平面内的运动”,以蜡块的运动为例,讲述合运动与分运动的概念以及介绍一种处理复杂运动的方法——运动的合成与分解．在讨论合运动与分运动的“等时性”时,有些教师试图给出一个让学生信服的理由．但笔者认为其做法有些不妥,在此提出质疑．