时空混合调制型偏振干涉成像光谱仪数据处理研究     

简小华  张淳民  祝宝辉  任文艺 《海洋学报》2010,32(9):6131-6137

研究了基于Savart偏光镜的偏振干涉成像光谱仪在时空混合调制模式下图像形成、数据分布的特点,论证了视场补偿型偏振干涉成像光谱仪更适用于单色光条件下的时空混合调制工作模式,并提出了时空混合调制模式下数据采集与处理的基本原理及其需要注意的问题与解决方法.最后,应用这种方法对实验获取的干涉图进行了数据处理,并成功复原出了光谱.  相似文献   

高效多路直流开关电源     

赵淑杰  尤权民 《东北地震研究》1998,14(2):75-77

本文介绍一种新型的直流开关电源,该电源是一种直流电压输入,三种直流电压输出,并能够达到相当高的效率。这种电源适用于数字化设备的无人职守台站。本文也论述了实现的技术思路和达到的技术要求。  相似文献   

ENSO事件对中高纬大气低频振荡的调频作用   总被引：7，自引：2，他引：5  

邱明宇  陆维松  陶丽 《南京气象学院学报》2004,27(3):365-373

采用诊断方法研究了El Nino和La Nina事件对中高纬大气低频振荡的调频作用。应用1950—1996年北半球中高纬逐日500 hPa高度场资料进行功率谱分析得出：夏季低频振荡较弱,冬季低频振荡较强;El Nino事件有使低频振荡周期缩短的趋势,La Nina事件有使低频振荡周期延长的趋势。  相似文献   

Insights into oxygen-cation bonding in fresnoite-type structures from O <Emphasis Type="Italic">K</Emphasis>- and Ti <Emphasis Type="Italic">L</Emphasis><Subscript>23</Subscript>-electron energy-loss spectra and ab initio calculations of the electronic structure     

P. A.?van AkenEmail author  T.?H?che  F.?Heyroth  R.?Keding  R.?Uecker 《Physics and Chemistry of Minerals》2004,31(8):543-552

O K- and Ti L₂₃-core-loss spectra of fresnoite Ba₂TiSi₂O₈ (BTS) and Sr₂TiSi₂O₈ (STS), which is isotypic to BTS, have been measured by electron energy-loss spectroscopy (EELS). The energy-loss near-edge structures (ELNES) of the O K edge have been identified on the basis of theoretical simulations and interpretations of the X-ray absorption near-edge structures (XANES), which have been modelled in the framework of self-consistent full multiple-scattering (FMS) theory using FEFF8. Herewith, the K-absorption spectra of oxygen (E) and the local partial electron density of states (DOS) of all atoms have been calculated. For BTS, the observed spectral features in the O K-edge spectra are interpreted in terms of mixing between the central O p and neighbouring Ba 5d and 4f, Si 3p and 3d, and Ti 3d orbitals. The observed differences in the O K-edge spectra for STS and BTS can mainly be attributed to three properties: (1) The lack of high local partial Sr unoccupied DOS with 4f symmetry near the Fermi level compared to the high Ba 4f unoccupied DOS results in differences of overlapping O 2p – cation orbitals. (2) The differences in the ionic radii of Sr and Ba result in a larger unit cell for BTS and, thus, in larger oxygen-cation bonding distances. (3) In comparison to STS, the strength of the incommensurate 2-D structural modulation is significantly weaker in BTS, i.e. distortions of coordination polyhedra occur to a much lesser extent. All these effects alter the oxygen-cation hybridization and, hence, result in a variation of the O 1s p transition and consequently of the O K-edge spectral shape. The observed peak broadening in Ti L₂₃ ELNES of STS compared to BTS is correlated with strong displacive modulations hosted in STS.  相似文献   

步进电机控制系统     

侯永海 《中国海洋大学学报(自然科学版)》1995,(Z1)

介绍步进电机控制系统的硬、软件设计及在潮汐模拟系统中的应用．以８０３１－ＣＰＵ为主控器，详述了其结构、分时控制、电源共享，异步运行和调速的实现方法．潮汐模拟结果表明以上方法简单、稳定、易于实现．  相似文献   

Altimeter Measurements of Wind and Wave Modulation by the Kuroshio in the Yellow and East China Seas   总被引：1，自引：0，他引：1  

Paul?A.?HwangEmail author 《Journal of Oceanography》2005,61(5):987-993

The Kuroshio is the major ocean current conveying heat and water mass in the Pacific Ocean. The impact of the Kuroshio on regional wind and wave distributions has been studied with spaceborne-altimeter measurements in the Yellow and East China Seas. In this region the Kuroshio trajectory is relatively stationary and the monsoon patterns dominate, making it an ideal natural laboratory for large scale air-sea-current interaction research. Major findings from this study include: (a) The Kuroshio exerts significant influence on the wind and wave distributions over a swath about 800-km wide along its path. (b) Seasonal average wind speeds reach a maximum near the Kuroshio axis. The magnitude of enhancement ranges between 20 and 50 percent. (c) The distribution of the surface wave heights displays similar spatial patterns to the wind-speed distribution. The Kuroshio effects on wave heights are further complicated by the hydrodynamic modulation of wave-current interaction and the influence of thermal stratification on wind-wave generation. (d) Kuroshio effects are most prominent in the first and last quarters of the year, and least prominent in the third quarter.  相似文献   

基于网格编码调制(TCM)技术的水声通信系统及DSP实现          下载免费PDF全文

许茹  程恩  刘慧  陈淑武  梁春丽  郭华伟 《海洋科学》2005,29(4):17-22

阐述了网格编码调制(TCM)的原理及其在水声通信中的应用。采用TI公司的高性能DSP芯片TMS320C542实现了一个可以进行字符传输的水下无线通信系统。试验结果表明，网格编码调制技术能够使水下无线通信系统的性能得到明显改善。  相似文献   

太阳活动对NAO与冬季中东急流轴线位置之间关系的调制作用          下载免费PDF全文

吴玲玲  张建伟  邓伟涛  赵鹤  陈宇杨 《大气科学学报》2018,41(1):93-102

利用NCEP/NCAR大气环流再分析资料和NOAA提供的太阳黑子资料,讨论了冬季中东急流年际变化特征,并探讨了太阳活动对北大西洋涛动(North Atlantic Oscillation,NAO)与冬季中东急流轴线位置之间关系的调制作用。结果表明:冬季中东急流的轴线位置表现出显著的年际变化特征,在空间上主要表现了中东急流东西两侧轴线南北移动呈反向变化(Middle East Jet Axis shift east-west Out-phase,MEJAO)型和中东急流轴线南北移动呈整体一致的变化特征(Middle East Jet Axis shift In-phase,MEJAI)型。另外,在太阳活动强时期,NAO(North Atlantic Oscillation,北大西洋涛动)的空间结构更靠近北大西洋东侧的大陆上,欧洲大陆北侧与地中海地区出现相反的SLP(Sea Level Pressure,海平面气压)异常,通过Ekman抽吸作用形成次级环流,在对流层高层地中海地区易出现辐合异常,并激发Rossby波波列,在伊朗高原上空会形成位势高度异常,从而中东急流东部轴线南北侧西风呈相反的变化。同时,在对流层高层欧洲大陆南侧形成的位势高度异常,也会使得中东急流西部轴线北侧西风出现异常。中东急流东、西部西风异常的空间结构呈反相变化,即出现了MEJAO型。而在太阳活动弱时期,NAO的空间结构主要局限在北大西洋地区,不易形成地中海辐合异常,NAO与MEJAO型的关系不密切。因此,太阳活动对NAO与MEJAO型之间的关系存在着调制作用。  相似文献   

一种矢量线状要素数据零水印算法     

李文德  闫浩文  王中辉  张黎明 《测绘科学技术学报》2016,(1):94-98

提出一种针对矢量线状要素数据的零水印算法。首先,利用Arnold技术置乱原始水印图像;然后,采用Douglas-Peucker压缩算法提取矢量线状要素数据的特征点;最后,将置乱后的水印图像与由相邻特征点所构成直线的斜率调制所得的二值矩阵进行异或运算,从而构造出零水印图像。实验结果表明,该算法能够抵抗常见的平移、旋转、缩放等几何攻击,并且对Douglas-Peucker压缩和裁剪攻击具有较好的鲁棒性。  相似文献   

Properties of nonlinear dynamo waves     

S. M. Tobias 《地球物理与天体物理流体动力学》2013,107(1-4):287-343

Abstract

Dynamo theory offers the most promising explanation of the generation of the sun's magnetic cycle. Mean field electrodynamics has provided the platform for linear and nonlinear models of solar dynamos. However the nonlinearities included arc (necessarily) arbitrarily imposed in these models. This paper conducts a systematic survey of the role of nonlinearities in the dynamo process, by cousidering the behaviour of dynamo waves in the nonlinear regime. It is demonstrated that only by considering realistic nonlinearities that are non-local in space and time can modulation of the basic dynamo wave be achieved. Moreover this modulation is greatest when there is a large separation of timescales provided by including a low magnetic Prandtl number in the equation for the velocity perturbations.  相似文献