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21.
In a previous paper we presented a low-resolution (2°×2°) survey of radio recombination lines (RRLs) at 327 MHz in the longitude rangel=330° to 0° to 89°. In this paper, we present the results of a higher resolution (2°×6′) survey of RRLs from seven 2°-wide fields and two 6°-wide fields in the same longitude range. Observations were made using the Ooty Radio Telescope (ORT). A total of 252 spectra that were obtained are presented. RRLs were detected in almost all the individual positions within the fields withl<35° and at several individual positions within the fields in the longitude rangel=35° to 85°. Detailed analysis of the data towards the field centered at G45.5+0.0, shows that the line emission consists of discrete zones of ionized gas. The angular extent of these zones are likely to be one degree or more corresponding to a linear size of >110 pc at the kinematic distance.  相似文献   
22.
具有悠久历史的石结构是砌体结构的重要组成部分,本文作者经广泛调研和试验分析:(1)提出以石粉为集料对石砌体进行抗震加固,寓环保与防灾于一体;(2)给出新型浆体配比和复合砂浆的强度等级,阐述加固技术和方法,建立灌浆石砌体抗震抗剪强度公式;(3)阐明抗震验算方法,提出基于模糊随机可靠理论的可靠性分析方法。  相似文献   
23.
The Daba Mountains define the southern margin of the East Qinling orogenic belt, and form the boundary of the Sichuan basin in the north and northeast. The Daba Mountains can be divided into two structural belts by the NW-striking Chengkou fault, namely the northern Dabashan thrust-nappe belt and the southern Dabashan foreland fold-and-thrust belt. The southern Dabashan fold-and-thrust belt is a southwestward extruding thin-skinned thrust wedge, showing obvious belted change in deformation style and deformation intensity along the dip direction, and can be divided further into three sub-belts, i.e. the imbricate thrust sub-belt characterized by imbricate stepped-thrust sheets, the thrust-fold sub-belt characterized by the combination of the equally-developed thrusts and related folds, and the detachment-fold sub-belt characterized by box folds and closed overturned-isoclinal folds on the outcrops. Several kinds of structures have been recognized or inferred, including imbricate thrust system, passive-roof duplex (triangle zone), fault-related folds, back-thrust system and pop-up structure. The NE-SW compressive stress from the Qinling orogenic belt and detachment layers in the covering strata are the two most important determinants of deformation style. After the collision between the North China block and Yangtze block at the end of the Middle Triassic, the northward intracontinental subduction along the southern edge of the Qinling orogenic belt was initiated, which led to the corresponding southward thrusting in the upper crust. The thrusting propagated towards the foreland through the Jurassic and extended to the southernmost part of the southern Daba Mountains around the end of the Early Cretaceous, with thrusting deformation to be preferentially developed along major detachment layers and progressing upwards from the Lower Sinian through the Lower Cambrian and Silurian to Middle-Lower Triassic. Translated from Geotectonica et Metallogenia, 2006, 30(3): 294–304 [译自: 大地构造与成矿学]  相似文献   
24.
过对鲁西东部中下寒武统研究表明:利用δ13C和δ18O以及Sr,Ni,V,Ba,B元素地球化学特征,不仅可以判断沉积古气候、古盐度、古水温、氧化-还原条件,而且还能提供海平面变化旋回及暴露-间断面确立的依据。研究证明此方法是非常有效的。  相似文献   
25.
Throughout history, dry-stone masonry structures have been strengthened with different types of metal connectors in order to increase their resistance which enabled their survival, especially in the seismically active area. One such example is the ancient Protiron monument placed in the Peristyle square of the Diocletian's Palace in Split, Croatia. The Protiron was built at the turn of the 3rd century as a stone masonry structure with dowels embedded between its base, columns, capitals and broad gable. The stone blocks in the broad gable were connected by metal clamps during restoration at the beginning of the 20th century. In order to study the seismic performance of the strengthened stone masonry structures, an experimental investigation of seismic behaviour of a physical model of the Protiron was performed on the shaking table. The model was designed as a true replica model in a length scale of 1:4 and exposed to representative earthquake with increasing intensities up to collapse. The tests provided a clear insight into system behaviour, damage mechanism and failure under intensive seismic load, especially into the efficiency of connecting elements, which had a special role in increasing seismic resistance and protection of the structure from collapse. Additionally, this experiment provided valuable data for verification and calibration of numerical models for strengthened stone masonry structures.  相似文献   
26.
北京城市边缘区非农产业活动特征与形成机制*   总被引:1,自引:1,他引:1  
曹广忠  刘涛  缪杨兵 《地理研究》2009,28(5):1352-1364
考察了北京主城边缘区的非农产业结构与空间特征,揭示了二者的交互演进过程:非农产业的发展是城市边缘区形成的重要标志,产业结构的升级促进了边缘区的圈层扩展和空间演进;边缘区的外移过程中,制造业具有稳定的优势,交运仓储、生产资料租赁等传统生产者服务业的优势也随之强化,但空间黏滞性较强的旅游、体育等行业则促进了边缘区产业结构的时相差异性。文章对城市边缘区"年轮式"的圈层扩展进行了定量实证分析,并将其实现的微观路径归纳为飞地式、轴向、填充式和外推式等四种扩展模式。城市规划、城郊高速公路和开发区建设、地价和综合环境的改善是城市边缘区产业空间演变的重要动力。城市空间优化和产业结构调整的结合是解决边缘区产业、空间和社会问题的有效途径。  相似文献   
27.
分析了气象部门思想政治工作的若干方法和艺术,即以理服人与以情感人相结合,抓两头带中间与抓中间促两头相结合,运用心理学原理,突出针对性,创造良好的环境,采取多样化的教育形式,评比竞赛,回忆对比及参观访问  相似文献   
28.
Northwest China is known for its Majiayao-style Neolithic painted pottery which has received much praise for its high level of craftsmanship, yet its chain of production, in particular the step of raw material selection, is still poorly understood. To fill this lacuna, the present study explores the raw materials used in producing these wares from a geological and technological perspective. At its core stands the first geoarchaeological survey conducted around the eponymous site of Majiayao which collected 47 samples of raw materials suitable for ceramic production including clay, loess and rocks, which were all analysed macroscopically. A selection was analysed using thin-section petrography, and a subset of the clay and loess samples were subjected to firing experiments. Additionally, three clay samples were analysed by scanning electron microscope with energy-dispersive X-ray spectrometer to understand their composition and behaviour in ceramic production. These were then compared to archaeological ceramics, thus providing insights into raw-material availability and selection that will be of importance not only for research on Majiayao-style pottery but also for later-period ceramics produced in the area. This research shows how an archaeologically informed geological survey can contribute insights into human–environment interaction in early pottery production, especially the interplay between raw-material availability, technological know-how and potters' choices.  相似文献   
29.
A pushover-based seismic risk assessment and loss estimation methodology for masonry buildings is introduced. It enables estimation of loss by various performance measures such as the probability of exceeding a designated economic loss, the expected annual loss, and the expected loss given a seismic intensity. The methodology enables the estimation of the economic loss directly from the results of structural analysis, which combines pushover analysis and incremental dynamic analysis of an equivalent SDOF model. The use of the methodology is demonstrated by means of two variants of a three-storey masonry building both of which have the same geometry, but they are built, respectively, from hollow clay masonry (model H) and solid brick masonry (model S). The probability of collapse given the selected design earthquake corresponding to a return period of 475 years was found to be negligible for model H, which indicates the proper behaviour of such a structure when designed according to the current building codes. However, the corresponding probability of collapse of model S was very high (46%). The expected total loss given the design earthquake was estimated to amount to 28 000 € and 290 000 €, respectively, for models H and S. The expected annual loss per 100 m2 of gross floor area was estimated to amount to 75 € and 191 €, respectively, for models H and S. For the presented examples, it was also observed that nonstructural elements contributed more than 50% of the total loss.  相似文献   
30.
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