航天遥感立体测绘小卫星目标跟踪与角度测量     

李世忠  王仁礼 《测绘学院学报》2001,18(1):29-32

随着现代小卫星技术的不断发展成熟，利用该技术为地球观测服务将成为一件远景可观，意义深元的事情，文中针对舆型航天遥感立体测绘微小卫星的需求，结合单脉冲测角原理给出了航天遥感测绘小卫星地面站面线系统的整体分析与设计。  相似文献   

Changes to the Surface Level Solar Ultraviolet-B Radiation Due to Haze Perturbation     

Mohammed Ilyas  Arunsala Pandy  Mohd. Suhaimi Jaafar 《Journal of Atmospheric Chemistry》2001,40(2):111-121

The South-East Asian region experienced a haze episode in 1994 which was widely believed to be due to widespread forest fires in Sumatra and Kalimantan (Indonesia). Broadband measurements of the surface level solar ultraviolet-B, UV-A and Global radiation at Penang (Malaysia) are used to study the effect of the 1994 haze on effective UV-B irradiance. We find that during the haze episode, there is enhanced absorption of surface level UV-B radiation. The effect of haze on UV-A and Global radiation is much less. The reduction in absolute noon time UV-B irradiance (mostly cloud free) during the 1994 haze period was 23% relative to the UV-B irradiance during thecorresponding haze-free period in 1995. Even though the noon time radiation data minimizes the cloud effect in the results presented some cloud effect is still present.  相似文献   

脉冲电镀金刚石钻头试验研究     

段隆臣  杨凯华 《现代地质》1996,10(3):423-426

介绍脉冲电镀在人造金刚石孕镶钻头上的应用研究，探讨脉冲电镀机理，采用正交试验法优化脉冲电镀工艺参数；研制了脉冲电镀钻头，生产钻头周期缩短了３０％。在室内和野外生产试验中，发现脉冲电镀钻头较直流电镀钻头有如下优点：钻进地层适用范围广、钻进时效高。  相似文献   

单片机电话计时计费器的设计     

唐志宽 《武汉大学学报(信息科学版)》1992,(4)

本文介绍了一个以单片机为核心的电话单机计时计费器的设计。提出了一种识别脉冲拨号和双音多频拨号的方法,同时在设计中充分利用了单片机的资源,注意发挥软件功能。因此使该设计具有结构合理,使用方便,性能价格比高的特点。  相似文献   

Yielding oscillator subjected to simple pulse waveforms: numerical analysis & closed‐form solutions     

George Mylonakis  Elia Voyagaki 《地震工程与结构动力学》2006,35(15):1949-1974

Numerical and analytical solutions are presented for the elastic and inelastic response of single‐degree‐of‐freedom yielding oscillators to idealized ground acceleration pulses. These motions are typical of near‐fault earthquake recordings generated by forward rupture directivity and may inflict damage in the absence of substantial structural strength and ductility capacity. Four basic pulse waveforms are examined: (1) triangular; (2) sinusoidal; (3) exponential; and (4) rectangular. In the first part of the article, a numerical study is presented of the effect of oscillator period, strength, damping, post‐yielding stiffness and number of excitation cycles, on inelastic response. Results are presented in the form of dimensionless graphs and regression formulas that elucidate the salient features of the problem. It is shown that conventional R–µ relations may significantly underestimate ductility demand imposed by near‐fault motions. The second part of the article concentrates on elastic‐perfectly plastic oscillators. Closed‐form solutions are derived for post‐yielding response and associated ductility demand. It is shown that all three ground motion histories (i.e. acceleration, velocity, and displacement) control oscillator response—contrary to the widespread view that ground velocity alone is of leading importance. The derived solutions provide insight on the physics of inelastic response, which is often obscured by the complexity of numerical algorithms and actual earthquake motions. The model is evaluated against numerical results from near‐field recordings. A case study is presented. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

星载紫外遥感辐射计积分球定标新方法的研究   总被引：1，自引：0，他引：1  

邢进  李福田  顾行发 《遥感学报》2006,10(5):644-650

在紫外波段，使用常规手段实现高精度的辐射定标是比较困难的，这主要是由于标准灯的定标不确定度约4％和漫反射板双向反射分布函数（BRDF）的测量不确定度4％-6％所致。为了提高定标精度，本文应用积分球辐亮度定标方法，获得了接近理想的大面积辐亮度光源（约2％），标定了在研的星载紫外遥感光谱辐射计的亮度响应度。文中将标准灯考虑为均匀亮度的点光源，对辐射计的投影视场进行了照明因子修正。同时进行了常规的灯-板定标方法与积分球定标新方法的比较，得到了采用两种方法标定的辐射计亮度响应度有较好的一致性（3％）的结论。初步的定标数据分析比对显示，漫反射板BRDF的测量不确定度和仪器投影视场内辐亮度的计算不确定度是比对中不一致主要的来源。  相似文献   

Characteristics of near-fault ground motion containing velocity pulses   总被引：1，自引：0，他引：1  

韦韬赵凤新  张郁山 《地震学报(英文版)》2006,19(6):677-686

There are many reports about the research on near-fault velocity pulses, which focus on the generation of velocity pulse and simplify the velocity pulse so as to be used in the seismic design of structure, However few researches have put emphasis on the characteristics of near-fault ground motions containing velocity pulses, especially the characteristics relevant with the design response spectrum prescribed by the code. Through collection of a large number of near-fault records containing velocity pulses, the response spectra and the characteristic periods of records containing no pulses are compared with those of records containing pulses. Response spectra of near-fault records are compared with standard spectra given by code; furthermore, the response spectra and the characteristic periods of each earthquake are compared with that given by code. The result shows that at long periods （longer than 1.5 s）, the response spectrum of pulse-containing records is bigger than the response spectrum of no-pulse-containing records; when the characteristic period of near-fault records is calculated, the method that does not fix frequency is more reasonable because the T1 and T2 have a lagging tendency; regardless of the site Ⅰ and site Ⅱ, the characteristic period of pulse-containing records is over twice bigger than the characteristic period given by the code,  相似文献   

云顶以下臭氧对TOMS反演臭氧总量的影响及反演方法的理论研究   总被引：4，自引：2，他引：4       下载免费PDF全文

江芳  王英鉴  刘振兴  王咏梅  张晓庆 《地球物理学报》2007,50(2):364-369

目前紫外后向散射反演臭氧总量的所有算法，都将云考虑成不透明的Lambertian反射体，并假定云顶有效反照率不随波长的变化而变化.然而本文通过模拟计算发现，由于云散射、瑞利散射、臭氧吸收三种作用的综合结果，云顶的有效反照率是与波长相关的，即使光学厚度比较大的云，辐射也可由云顶继续向下传输，因而会受到云顶以下臭氧吸收的影响.用V7方法进行反演，模拟计算结果表明：云的出现使得云顶以下，特别是云内光程增强，导致紫外波段的臭氧吸收衰减增大，所以反演出的臭氧总量值比真实值偏大，本文称这种现象为“云吸收效应”，并讨论了该效应的影响因子.最后，在辐射传输模拟的基础上建立一套反演算法，大大减弱了“云吸收效应”的影响.  相似文献   

HST UV measurements of wind structure and velocities in Local Group OB stars     

Raman K. Prinja  & Paul A. Crowther 《Monthly notices of the Royal Astronomical Society》1998,300(3):828-836

Archival HST FOS and GHRS data sets have been used to collect ultraviolet evidence for large- and small-scale stellar wind structure in extragalactic Local Group OB stars (i.e. SMC, LMC including R136, M31, M33 and NGC 6822). By comparison with previous studies of Galactic OB stars, wind activity is principally diagnosed in individual spectrograms via the presence of 'narrow absorption components' and saturated 'black' absorption troughs in the resonance line doublets. Their characteristics broadly suggest that these stars share the same physical mechanisms for perturbing the winds as those that act in Galactic stars. Both of these spectral indicators are also used to provide reliable measures of wind terminal velocities. These velocities are directly compared with previously published Galactic values, without reliance on model profile fitting. Relative to Galactic OB stars, the most discrepant terminal velocities (and wind line profiles) result from main-sequence early O-type stars in the SMC.  相似文献   

714C气象雷达电磁干扰的分析及解决方法     

孙贵文  毛成忠 《成都信息工程学院学报》1998,(2)

雷达设备电磁干扰的解决方法,依赖于对干扰的准确分析。通过昆明机场７１４Ｃ气象雷达受空军警戒雷达干扰的实例,介绍了一种高功率脉冲对雷达发射机干扰的分析过程,并提出解决方法。  相似文献