The FAST/SKA site selection in Guizhou province   总被引：1，自引：0，他引：1  

B. Zhu  Y. Nie  R. Nan  B. Peng 《Astrophysics and Space Science》2001,278(1-2):213-218

Many karst depressions with diameters of 300 m to 500 m, suitable for constructing Arecibo-style radio telescopes, were identified in the south of Guizhou Province by Remote Sensing (RS) and Geographic Information System (GIS) technologies together with field investigations. Fundamental topography and landform databases were established for 391candidate depressions, and using GIS the3-dimensional images of depressions, at a scale of 1:10000, were then simulated to fit a spherical antenna. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

无规取向、无吸收非球形粒子光散射的T-矩阵方法     

丁继烈  许丽生 《成都信息工程学院学报》2001,16(3):159-168

较详细地研究了无规取向、无吸收椭球体粒子的T－矩阵收敛问题。首先，简要概括了nmax的3种收敛方案和它们的基本特性。然后，应用1993年提出的数学收敛方法（M－方法）和1998年提出和物理收敛方法（P－方法）研究收敛问题。结果表明椭球粒子收敛精度对粒子的尺度参数，纵横比以及椭球体的种类（例如，长／扁椭球）有很强的依赖性。当粒子的尺度参数不太大时，甚至在极端纵横比的条件下，P－收敛方案优于M－收敛方案。  相似文献   

河西走廊东部地区早二叠世地层研究的新认识     

罗桂昌  汪明洲 《地球科学与环境学报》1992,(2)

本文讨论了河西走廊东部地区早二叠世地层研究的有关问题,认为甘肃山丹青羊泉下二叠统剖面是北祁连山—河西走廊地区的重要代表剖面之一。以该剖面研究为依据,提出走廊东部地区下二叠统的进一步划分方案,分析该区早二叠世地层岩性特征差异的原因,并与走廊西部地区同期地层进行对比,进一步明确了大黄沟组的含意。  相似文献   

Protostar formation under two current carrying gas filaments collision     

Bidzina Chargeishvili  Jun-Ichi Sakai 《Astrophysics and Space Science》1995,227(1-2):199-215

A model of protostar formation under two current carrying gas filaments collision is presented. The model implies MHD approach involving self-gravity and radiative cooling effects. We suppose that through the current carrying gas filament collision a magnetic field reconnection takes place. Using an appropriate self-consistent presentation for time and special dependences of physical quantities in MHD equations, we derive the full set of equations that describes time evolution of the physical quantities just after an occurrence of magnetic field reconnection. Numerical simulations reveal that the process consists of three main phases of evolution. The first is an appearance of preceding peaks in time profiles of density and temperature following by the next phase of depression of both temperature and density and the final fast condensation phase with either cooling or heating of matter depending on initial parameters of problem. Effects of initial conditions like as magnetic field strength, current strength, initial gravity energy, cooling time and a geometry of collision are investigated. Main conclusion is that protostar formation takes place within the time interval less than one free fall time and it is preceded by the appearance of dense and hot matter with lifetime much less than free fall time. The final temperature of the protostar depends on the physical conditions and mainly on the ratio between free fall time and cooling time in the colliding current carrying gas filaments.  相似文献   

瞬变电磁法在断层含水性评价中的应用          下载免费PDF全文

郁万彩 《山东国土资源》2001,17(1):52-55

本文介绍了瞬变电磁法在煤矿水文地质勘探中的具体应用效果.采用瞬变电磁法对落差较大断层的含(导)水性进行测量,不仅可有效地控制断层的空间位置,而且可定性地判断断层的富水性,其测量结果与已知水文地质资料吻合较好.  相似文献   

The carbohydrates in relation to mineralogic and granulometric composition of surface sediments in the karst estuary (River Krka estuary,Yugoslavia)     

Olga Hadz̆ija  Mladen Jurac̆ić  Marija Luić  Maja Tonković  Biserka Jeric̆ević 《Estuarine, Coastal and Shelf Science》1985,21(5):701-709

The investigation of mineral, granulometric and chemical composition of sediments of the River Krka estuary (Yugoslavia) were performed in order to elucidate the origin of the sediments and the pattern of sedimentation. Estuarine surface sediments were found to be fine-grained with a bimodal distribution. Environmental conditions in estuarine sediments favour conservation of the organic matter (anoxic conditions). The carbohydrates in the sediments were investigated to determine whether they are of terrigenous or authigenous origin. Glucose, galactose, mannose, xylose, rhamnose, glucosamine and glucuronic acid were detected in the sediments. Their mutual relationship indicates a preferentially terrigenous source of sedimented organic material in estuarine sediments.  相似文献   

Sedimentary characteristics of tide-dominated estuary in Donghetang Formation（Upper Devonian）, central Tarim Basin     

WANG Li-ping LI Chuang TANG Bing-yong 《东北亚地学研究》2005,8(1):78-93

The Donghetang Formation （Upper Devonian） in central Tarim Basin has been thought an important oil and gas reservoir since the abundant oil and gas resources were found in the wells W16, W20, W34, and other fields. However, the sedimentary environment of the Donghetang Formation has been disputed because it suffered from both tidal and fluvial actions and there were not rich fossils in the sandstone. After the authors analyzed sedimentary features by means of drill cores, well logging data, paleosols, and with SEM obseruations, three kinds of sedimentary environments were distinguished： alluvial fan, tide-dominated estuary, and shelf. Particularly, the sedimentary features of tide-dominated estuary were studied in detail. Besides, the authors discussed sedimentary characteristics of the Donghetang Formation which was divided into two fourth-order sequences and five system tracts. At the same time, according to the forming process of five system tracts, the whole vertical evolution and lateral transition of tide-dominated estuary were illustrated clearly. Finally, the reservoir quality was evaluated based on porosity and permeability.  相似文献   

SHORT COMMUNICATION TARGET FACTOR ANALYSIS:UV SPECTROPHOTOMETRY FOR THE SIMULTANEOUS DETERMINATION OF SIX AMINO ACIDS     

PANZHONGXIAO  XIASIQING  SISHENGZHU  ZHANGMAOSEN  SHILEMING  LIUXINAN 《地理学报(英文版)》1990,(4)

The UV spectra of mixture solutions consisting of tyrosine,tryptophane,phenylalanine,cystine,histidineand 3,4-dihydroxyl phenylalanine have been measured.The numbers,identities and concentrations of theamino acids in the mixtures have been determined successfully using target factor analysis.The effectsof the wavelength range and the selected sampling interval on the results are discussed.Twenty-fivesynthetic mixture samples have been analysed successfully.The average recoveries are 98·9 for Tyr,96·5for Trp,105·6 for Phe,98·1 for Cys,98·9 for His and 106·4 for Di-phe.The results obtained are ingood agreement with those obtained by the Kalman filter method.  相似文献   

构造因素与滑坡     

李新生 《地球科学与环境学报》1993,(Z2)

本文首先简述了斜坡演化过程与构造运动的关系,然后阐明了滑坡的空间分布、活动周期及活动规模与构造因素的联系。在此基础上指出:构造因素是滑坡产生的基础,对滑坡分布具宏观控制作用,并与滑坡的活动周期和活动规模密切相关,是滑坡研究及其灾害预测、预防研究工作中值得重视的重要因素。  相似文献   

Formation Pressure Evaluation Method for Single Well     

WANG Yachun 《东北亚地学研究》2002,(1)

The paper deals with the methods of formation pressure evaluation for a single well by using the very common ac-cepted parameters, such as drilling exponent , and flowline temperature , etc. which is part of compiling the end well report.  相似文献