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51.
介绍了一种对2台步进电机相互间采取等差角同步旋转的控制方案.根据这个方案设计和制作的机电控制电路实现了同步旋转快门功能,最终的同步精度控制在步进电机的性能1.8度/步的范围内,应用在激光测距系统中起到了安全保护单光子探测器的作用. 相似文献
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Zhi-Fu Gao Ci-Xing Chen Na Wang Xin-Jun Zhao Zhao-Jun Wang 《Astronomische Nachrichten》2024,345(2-3):e240012
There are many rotating spheroids in the universe, and many astronomers and physicists have used theoretical methods to study the characteristics of stellar gravity since Newton's time. This paper derives the solutions of eight scattering states , , and for the Dirac equation with positive-energy , and establishes the relationship between the differential scattering cross section and the stellar density . It is found that: (1) For the eight scattering states, their average scattering cross-sections are proportional to , and depend on the star's radius, and the higher the stellar density , the greater the sensitivity of to the change of ; (2) For the four scattering states , their average scattering amplitudes and depend on the mass of the particles; while for the other four scattering states , , then and are independent of . This study links the gravitational characteristics of stars with the scattering cross section, creating a new method for studying the gravitational characteristics, which helps to reveal the mystery of the gravity of rotating ellipsoidal stars. 相似文献
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准确反演气溶胶光学厚度(AOD)在气溶胶气候效应和环境效应研究中至关重要,仪器定标是目前AOD反演过程中最大的不确定性来源。Langley法作为应用最广泛的光度计定标方法,其对天气条件和大气洁净度要求苛刻,这在大气污染较重的地区难以实现,并可能导致AOD反演误差偏大。为了降低由不恰当的Langley定标所引起的AOD反演误差,本文提出一个利用辐射传输模式结合地面太阳直接辐射观测数据检验Langley定标结果合理性的方法,并利用西安2013年6月至2015年12月多滤波旋转遮光带辐射计(MFRSR)和直接辐射表(NIP)观测资料,探讨了方法的可行性。结果表明,该方法能够将Langley定标结果限定在较小的波动范围内,有效降低由定标不确定性引起的AOD反演误差,有助于提高单站点AOD观测精度。 相似文献
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本文仅研究无粘、无地形和绝热运动假定下的大气动力学问题,用分析力学的方法求得了固定在地球上的移极旋转坐标系, 如直角坐标系, 球坐标系和柱坐标系中的第二类 Lagrange方程。从而求得普遍的大气动力学方程。所谓的视示力 —— Coriolis力和离心力 —— 与其它各种力统一处理。当地球自转轴不为坐标系的z轴时,不存在大气运动的对称和反对称性。特别值得提出的是以往很多学者利用柱坐标系来数值模拟台风(飓风)的轴对称和非轴对称性时所使用的基本方程是含糊的, 本文给出了准确的基本方程。 相似文献
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黄靖贤 《水文地质工程地质》2002,29(6):57-59
介绍了某建筑物利用高压旋喷清水切割纠偏及利用高压旋喷注浆 压力灌浆组合的联合注浆进行地基加固的设计及施工,取得了良好效果。 相似文献
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We present new analytical three-dimensional solutions of the magnetohydrostatic equations, which are applicable to the co-rotating frame of reference outside a rigidly rotating cylindrical body, and have potential applications to planetary magnetospheres and stellar coronae. We consider the case with centrifugal force only, and use a transformation method in which the governing equation for the “pseudo-potential” (from which the magnetic field can be calculated) becomes the Laplace partial differential equation. The new solutions extend the set of previously found solutions to those of a “fractional multipole” nature, and offer wider possibilities for modelling than before. We consider some special cases, and present example solutions. 相似文献
60.
The differentially heated rotating annulus is a laboratory experiment historically designed for modelling large-scale features of the mid-latitude atmosphere. In the present study, we investigate a modified version of the classic baroclinic experiment in which a juxtaposition of convective and motionless stratified layers is created by introducing a vertical salt stratification. The thermal convective motions are suppressed in a central region at mid-depth of the rotating tank, therefore double-diffusive convection rolls can develop only in thin layers located at top and bottom, where the salt stratification is weakest. For high enough rotation rates, the baroclinic instability destabilises the flow in the top and the bottom shallow convective layers, generating cyclonic and anticyclonic eddies separated by the stable stratified layer. Thanks to this alternation of layers resembling the convective and radiative layers of stars, the planetary’s atmospheric troposphere and stratosphere or turbulent layers at the sea surface above stratified waters, this new laboratory setup is of interest for both astrophysics and geophysical sciences. More specifically, it allows to study the exchange of momentum and energy between the layers, primarily by the propagation of internal gravity waves (IGW). PIV velocity maps are used to describe the wavy flow pattern at different heights. Using a co-rotating laser and camera, the wave field is well resolved and different wave types can be found: baroclinic waves, Kelvin and Poincaré type waves. The signature of small-scale IGW can also be observed attached to the baroclinic jet. The baroclinic waves occur at the thin convectively active layer at the surface and the bottom of the tank, though decoupled they show different manifestation of nonlinear interactions. The inertial Kelvin and Poincaré waves seem to be mechanically forced. The small-scale wave trains attached to the meandering jet point to an imbalance of the large-scale flow. For the first time, the simultaneous occurrence of different wave types is reported in detail for a differentially heated rotating annulus experiment. 相似文献