首批证认8个密云射电源为BLLac天体和类星体     

张喜镇  朱文白  魏建彦  胡景耀  马振国 《中国天文和天体物理学报》1998,(4)

为了深入研究密云射电源表分类样本的性质,作为系列工作的第一部分,选出了一个２３２～４８５０ＭＨｚ平谱源样本．１９９８年５月２９至３１日,利用北京天文台２．１６米望远镜和ＯＭＲ摄谱仪,对其中１８个目标进行了观测及光谱认证．结果共证认出１５个ＡＧＮ,其中３个信噪比不小于８的ＢＬＬａｃ天体和５个类星体（最大红移为２．５１９±０．００３）是新发现的．  相似文献   

Accurate Determination of Electron Densities in Active and Quiescent Prominences: the Mid-Infrared Advantage     

Edward S. Chang  Drake Deming 《Solar physics》1998,179(1):89-114

We have analyzed all lines in the MIR (8 to 20 micron) spectra of a quiescent and two time-frames of an active prominence. In the quiescent prominence, in addition to those lines found by Zirker (1985), we have identified a higher excitation hydrogen line and two helium recombination lines. Accounting for instrumental broadening, we can further separate out the Doppler and the Stark contributions to the line width. The former yields maximum temperatures of 6200 K, 34000 K and 12000 K and the latter electric field strengths of 7, 17, and 10 V cm^-1 for the above prominences, respectively. We show that these electric fields when divided by 2.2 are equal to the normal electric field in Holtsmark's quasi-static Stark broadening theory. Hence, we obtain electron densities of N₃=2.4(0.3), 9.1(1.2), and 5.5(0.6) in units of 10¹⁰ cm^-3 respectively. Using the same assumptions as made by Zirker, namely, (1) the strongest line (7-6) is optically thin, (2) the population of the lower level (n=6) is determined by direct radiative recombination and photo-ionization, (3) the equality of proton and electron densities, and (4) the thickness of the prominence is at least 10⁸ cm, we derive a new inequality, N_e 1.83 × 10⁸ T^0.75 e^-2195/T. Substituting our maximum temperatures into the right-hand side, we find upper bound N_e values of 9, 43, and 30 in the same units as above. These upper bound values are comfortably higher than our measurement, unlike those of Zirker's derived from the same set of assumptions. We have also observed the helium recombination spectrum which has been postulated by Tandberg-Hanssen as one of three possible ways of equilibrating the triplet/singlet ratio. Surprisingly, it is present in the quiescent as well as in the active prominence. We show that no meaningful values can be found for the turbulent velocities by combining the helium with the hydrogen line widths.  相似文献   

珠江三角洲城市化进程中耕地面积的变化特征分析   总被引：23，自引：1，他引：22  

黄宁生  朱照宇  乔玉楼  孙大中 《热带地理》1998,18(4):296-301

讨论了１９８０－１９９５年珠江三角洲地区７个主要城市在城市化进程中耕地面积的变化特点;分析了城市化发展的不同阶段以及不同速度与耕地面积减少之间的关系。以耕地面积减少系数为主要指标,总结出珠江三角洲地区基于耕地资源利用特征的４种城市化模式。研究发现,部分城市出现的耕地资源过度消耗现象,不应简单地归因于城市化发展,而主要与当地城市发展规划和管理工作不力有关。  相似文献   

关于数字航测相机像移补偿问题   总被引：3，自引：0，他引：3  

常本义 《测绘学院学报》1998,(2)

航测相机像移补偿有两种方法 :一是在相机的焦平面上 ,使感光平面沿飞行方向 ,在曝光瞬间作一微小位移 ,以改正因摄影平台相对于被摄目标的运动引起的像点位移 ;二是在曝光瞬间 ,使相机作一微小的俯仰角旋转 ,以改正因摄影平台相对于被摄目标的运动引起的像点位移。前者简称为焦平面平移改正法 ,后者可称为俯仰旋转改正法。本文中研究了这两种像移补偿方法的差异和所能达到的精度水平及其适用范围  相似文献   

多光谱遥感数据最佳波段选择方法试验研究   总被引：15，自引：1，他引：15  

李石华  王金亮  陈姚  朱妙园  廖迎芸 《云南地理环境研究》2005,17(6):29-33

分析了多光谱遥感数据最佳波段选择的标准差、熵和联合熵、相关性系数及最佳指数等计算方法的内在联系。通过试验,说明了各种计算方法的有效性和局限性,最后得出OIF指数法为多光谱遥感数据最佳波段选择的最优方法。  相似文献   

东川汤丹铜矿床石英真空击碎及其粉末阶段加热^40Ar—^39Ar年龄谱的含义   总被引：17，自引：5，他引：12  

邱华宁  孙大中 《地球化学》1998,27(4):335-343

采用真空击碎技术提取东川汤丹铜矿床石英流体包裹体进行40Ar-39Ar法年龄测定,获得了逐渐下降的阶梯形年龄谱,表明流体包裹体含有过剩氩;数据点在40Ar／36Ar-39Ar／36Ar图解上构成等时线,等时线年龄为（712±33）Ma,代表了矿床的形成年龄。随后对其粉末进行40Ar-39Ar阶段加热（100—800℃）分析,形成相对比较平坦的年龄谱,坪年龄为（317±6）Ma（39Ar占45％,含真空击碎分析在内）,粉末加热分析全部数据点构成的等时线年龄为（321±13）Ma。电子探针分析和显微镜观察证实了该石英样品中含有粒径大于100μm,K2O含量为8％-10％,形成时间明显晚于石英的白云母类富钾矿物,粉末阶段加热分析结果表明～320Ma应为后期白云母类矿物的年龄。  相似文献   

南极长城湾及邻近水域表水异养细菌的含量估计及相关因子分析(英)     

CHEN Hao-Wen  ZHU Ming-Yuan 《冰川冻土》1998,(4)

A survey was made of the number of the heterotrophic bacteria in surface seawater of Great Wall Bay and its adjacent waters, Antarctica during the period of austral summers from Dec.1993 to Feb. 1994. The result shows that the number of the heterotrophic bacteria in the surface waterof the surveyed area is about 798 CFU. cm-3, ranging from 53 to 4 250 CFU. cm-3. Comparison of thenumbers for three months shows a declining tendency month by month. Comparing with the previous results, this one shows that the heterotrophic bacteria number changes somewhat, but slightly. It is lower than that in nearshore waters but higher than that in the open area. This shows that there is a positive correlative relationship between CFU and NH4- N, which means that heterotrophic bacteria should be an important agent in NH4-N reproduction in the environment surveyed. There is an significant negative correlation both between CFU and NOZ-N, and between CFU and PO4-P. This means that the NOZ-N, PO.-P, which were decomposed and transformed by bacteria, were used rapidly by phytoplankton.  相似文献   

Fractal analysis applied to faults and earthquakes——A case study of China     

王建  朱晓华  徐永辉 《地震学报(英文版)》1998,(3)

Ｆｒａｃｔａｌａｎａｌｙｓｉｓａｐｐｌｉｅｄｔｏｆａｕｌｔｓａｎｄｅａｒｔｈｑｕａｋｅｓ———ＡｃａｓｅｓｔｕｄｙｏｆＣｈｉｎａＪＩＡＮＷＡＮＧ（王建）ＸＩＡＯＨＵＡＺＨＵ（朱晓华）ＹＯＮＧＨＵＩＸＵ（徐永辉）ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏｇ...  相似文献   

Magmatic Network Structure of Volcanic Rocks in the Shengli Oilfield, Eastern China     

HE Ying  ZHU Xingguo Department of Geology  Northwest University  Xi''an  Shaanxi  XU PeicangXi''an Institute of Geology  Chinese Academy of Geological Sciences  Xi''an  Shaanxi 《《地质学报》英文版》1998,72(2):191-197

Types of polymerized molecular network structure and degree of bond breakdown for glass phases of magmatic inclusions and glassy matrix in volcanic rocks from the Shengli oilfield have been defined by the laser Raman spectroscopic investigation. There are significant differences in types of polymerized molecular network structure and degree of bond 'breakdown of the magmatic glass phases between the non-CO2 and COa gas pools: magmatic glass phases of fluid inclusions and matrix in volcanic rocks from the CO2 gas pool contain more sheet network molecules and have a greater degree of bond beakdown than those from the non-CO2 gas pool; and when gas bubbles occur in evolving magma, magma saturated with volatile components has more sheet network molecules. The results suggest the magma-degassing mechanism of the formation of CO2 gas pools in the Shengli oilfield.  相似文献   

西秦岭三叠系一个浊积岩序列金的地球化学特征     

赖旭砻  谢树成  杜远生  章传玲  朱敬宾 《地球学报》1998,19(2):210-214

本文在详细分析沉积韵律、沉积构造、成分及粒度的基础上,论证了四川省若尔盖县阿西乡牙相一带上三叠统卡车组一套浊积岩沉积。通过对牙相浊积岩序列的２３个采自各浊积旋回各层段的系列样品的金分析,发现这一浊积岩序列具有：以泥质粉砂岩、泥质岩为主的鲍玛序列的Ｄ—Ｅ段与其上旋回的以含砾砂岩、粗砂岩为特征的Ａ段含金量呈线性关系,表明这两段之间元Ａｕ元素发生了循环,进一步揭示了浊积岩具有金的可迁移性这一矿源层的重要特征。另外,砂质单元金含量比细粒的粉砂岩和泥岩要高,从浊积岩序列的底部旋回至上部回金的含量降低并由不稳定到稳定  相似文献