Spectra of Comet Hale-Bopp (C/1995 O1) Obtained with 6-M BTA Reflector at Mount Pastukhov     

Churyumov  K. I.  Kleshchonok  V. V.  Vlassyuk  V. V. 《Earth, Moon, and Planets》1997,78(1-3):111-117

Between July 1996 and April 1997, 92 spectra of comet Hale-Bopp were obtained with the 6-meter BTA telescope of the SAO of the RAS at Mount Pastukhov. The spectra are two-dimensional, which allows one to determine the energy distribution for each emission along the slit and the energy distribution in wavelength for each individual position in the slit. From the 92 two-dimensional spectra covering the inner coma, detailed spectral maps of the total near-nuclear region of the comet are available for July 10, 11 and 12, 1996 and April 15, 1997. We propose an hypothesis about an unknown cometary species near λ = 620 nm in the spectrum obtained July 10, 1996. We also find an effect which may be caused by fluorescence of cometary dust. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Representation of near-fault pulse-type ground motions   总被引：7，自引：3，他引：4  

谢礼立  徐龙军Adrian Rodriguez-Marek 《地震工程与工程振动(英文版)》2005,4(2):191-199

Near-fault ground motions with long-period pulses have been identified as critical in the design of structures. To aid in the representation of this special type of motion, eight simple pulses that characterize the effects of either the fling-step or forward-directivity are considered. Relationships between pulse amplitudes and velocity pulse period for different pulses are discussed. Representative ratios and peak acceleration amplification can exhibit distinctive features depending on variations in pulse duration, amplitude and the selected acceleration pulse shape. Additionally, response spectral characteristics for the equivalent pulses are identified and compared in terms of fixed PGA and PGV, respectively. Response spectra are strongly affected by the duration of pulses and the shape of the basic pulses. Finally, dynamic time history response features of a damped SDOF system subjected to pulse excitations are examined. These special aspects of pulse waveforms and their response spectra should be taken into account in the estimation of ground motions for a project site close to a fault.  相似文献   

Averaging Intervals For Spectral Analysis Of Nonstationary Turbulence     

George Treviño  Edgar L. Andreas 《Boundary-Layer Meteorology》2000,95(2):231-247

We formulate a method for determining the smallest time interval Tover which a turbulence time series can be averaged to decompose it intoinstantaneous mean and random components. From the random part the method defines the optimal interval (or averaging window) AW over which this part should be averaged to obtain the instantaneous spectrum. Both T and AW vary randomly with time and depend on physical properties of the turbulence. T also depends on the accuracy of the measurements and is thus independent of AW. Interesting features of the method are its real-time capability and the non-equality between AW and T.  相似文献   

The focus parameters and their correlation from small earthquakes before and after the 1995 Douhe earthquake     

张天中  马云生  黄蓉良  刘庆芳  刘元壮 《地震学报(英文版)》2000,13(3):249-256

IntroductionTheseismoIogymethodofearthquakepredictionissometimessimplycalled"predictingearthquakebyearthquake",thatis,animpendinglargeearthquakeispredictedonbasisofsomefeaturesofsmaIlearthquakesoccurredbeforeit.Forthispurpose,thecharactersoftemporaryspatiaIandmagnitudedistributionofsmalIearthquakesareintensiveIyinvestigated,whichareusuallycalIedasseismicitymethod.ThesuccessfuIpredictionofHaichengearthquakeinl975wasitSremarkabIeappIication.Besides,thepossibIechangesincharactersofseismicsou…  相似文献   

Directional measurements of wave growth in a short and narrow fetch geometry     

H. Pettersson  K. K. Kahma 《Journal of Atmospheric & Ocean Science》2005,10(1):15-29

The growth of young waves along a narrow bay and their directional spectra were studied. The fetch geometry was found to affect the shape of the spectrum already when the waves were young. When compared to the growth from a straight shoreline, the dimensionless energy was reduced, but the change in dimensionless peak frequency was smaller. The behaviour of the young waves was similar to that of the mature waves but the differences between narrow and broad fetch geometries were smaller, which suggests that due to a stronger nonlinear transfer the young waves are less sensitive to the fetch geometry. The directional spectrum of the young waves in the narrow fetch geometry was narrower at all energy containing frequencies than the spectra from broad fetch geometry, which further supports the conclusion that the shape of the spectrum is not independent of the fetch geometry.  相似文献   

A Primary Study of Interaction Between Monsoon and Sea Surface Temperature in the Neighborhood Sea Area in South Aisa          下载免费PDF全文

LIU Lihong  ZHENG Zuguang  XIA Youlong  WU Hong 《Acta Meteorologica Sinica》2005,19(3):366-374

1. Introduction South Asian monson is an important weather and climate phenomenon, and it is also an important con- stituent of the global atmospheric circulation, thus people pay more attention to it (Hahn and Manabe, 1975; Zhu and Zhao, 1987; Zhu et al., 1991; Zhou and Yang, 1994; Wu and Huang, 2001; Li et al., 1999). For example, Zhu and Zhao (1987) studied the effects of terrain on South Asian monsoon by the equato- rial atmospheric balance model, indicating that ter- rain effect is …  相似文献   

胡敏酸在高岭土上的吸附行为   总被引：11，自引：3，他引：11       下载免费PDF全文

李爱民朱燕  代静玉 《岩石矿物学杂志》2005,24(2):145-150

研究了胡敏酸在高岭土上的吸附行为 ,并运用X衍射、红外光谱和热重等分析方法 ,对复合前后的高岭土进行分析。结果表明 ,连续洗涤 6次后 ,可获得稳定的胡敏酸高岭土复合体 ;胡敏酸在高岭土上的吸附符合Fruendlich吸附模式 ,Kf 为 0 .85 7;高岭土胡敏酸复合体的红外光谱出现了明显的C—H振动吸收峰 ;吸附行为主要表现为化学吸附 ,发生在铝的表面羟基吸附位上  相似文献   

TM影像的居民地信息提取方法研究   总被引：102，自引：5，他引：97  

杨存建  周成虎 《遥感学报》2000,4(2):146-150166

从对居民地的遥感信息机理分析入手,分析了居民地在Ｌａｎｄｓａｔ ＴＭ２、ＴＭ３、ＴＭ４、ＴＭ５、ＴＭ７等各个波段上与其它地类的可分性。并探讨了增强居民地与其它地类的方法。同时进一步对各地物的谱间结构特征进行了分析,通过分析发现,以水泥顶和瓦项房屋为主的居民地,其ＴＭ２、ＴＭ４、ＴＭ７的光谱值比较接近,而其它地物除新修道路外,都不具备这一特征。这一特征可以用如下表达式来表达,ＴＭ２－ＴＭ４〈Ｔ１;Ｔ  相似文献   

海面微波散射与风生波短波谱   总被引：2，自引：0，他引：2  

徐丰  贾复  马丽娟 《遥感学报》2000,4(4):251-255

从海面微波散射的物理机制出发 ,在短波平衡范围条件下 ,讨论了风生波短波谱形式 ,通过对不同波段的微波散射数据分析 ,建立起能适应相当宽微波波段 ( 0 .42 8— 34.4GHz)的海面微波散射模型。文中对若干个波段的微波散射系数进行了试算 ,并与实测资料进行了比较 ,结果是令人满意的  相似文献   

钢筋混凝土结构基于改进能力谱法的地震损伤性能设计   总被引：23，自引：8，他引：15  

何政  欧进萍 《地震工程与工程振动》2000,20(2):31-38

本文基于国内外非线性静力分析方法,阐述了最近由Ｃｈｏｐｒａ和Ｇｏｅｌ提供的改进能力谱法的基本概念和实施步骤;其次,结合文献「１８」中提出的钢筋沸凝土结构地震损伤“三水准”性能目标和改进能力谱法,提出了基于能力谱法的结构地震损伤性能简化设计及验算方法;最后,通过设计例题说明了本文方法的可行性,并将计算结果与时程分析进行了比较,显示了此法的有效性。  相似文献