Optical spectroscopy of X-Mega targets – IV. CPD – 59°2636: a new O-type multiple system in the Carina Nebula     

J. F. Albacete Colombo  †‡  N. I. Morrell  §¶  G. Rauw  M. F. Corcoran  &#;  V. S. Niemela †  H. Sana †† 《Monthly notices of the Royal Astronomical Society》2002,336(4):1099-1108

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Modelling of seeing effects in extragalactic astronomy and cosmology     

S. Djorgovski 《Journal of Astrophysics and Astronomy》1983,4(4):271-288

Convolution methods for modelling of astronomical seeing effects have been investigated. The advantages and disadvantages of several techniques are discussed, and particular attention is given to the fast Fourier transform (FFT) method. This method is then applied to two classes of problems, the structure of cores of elliptical galaxies, appearance of distant galaxies and the consequences of seeing effects in some cosmological tests. Estimates are presented for dimming of the central surface brightness and changes in the apparent core radius for elliptical galaxies, as well as seeing-induced changes in ellipticity. Modelling of galaxies with stellar nuclei has also been performed. Some consequences of these effects in investigations of dynamics of elliptical galaxies are addressed briefly. The influence of seeing in observational cosmology is discussed in the context of Hubble diagram (m-z) tests. It is shown that inadequate compensation for seeing effects can seriously distort the conclusions in such tests. Some suggestions for future work in this direction are offered.  相似文献   

High-order Analytical Solutions of Hill’s Equations     

G. Gómez  M. Marcote 《Celestial Mechanics and Dynamical Astronomy》2006,94(2):197-211

The purpose of this paper is the semi-analytical computation of the bounded orbits of Hill’s equations, describing the relative motion of two particles in their Keplerian motion around a central body. We have considered the case in which one of the particles moves along a circular reference orbit. The solutions obtained are the generalisation of the usual periodic orbits obtained for the linearised equations and also of the third-order solution computed by D.L. Richardson and J.W. Mitchell (2003). With the algorithm presented, those orbits can be computed in a fast and efficient way up to a high-order in the in-plane and out-of-plane amplitudes.  相似文献   

Consolidation analysis of a cross-anisotropic homogeneous elastic soil using a finite layer numerical method     

Guo-Xiong Mei  Jian-Hua Yin  Jin-Min Zai  Zong-Ze Yin  Xiao-Li Ding  Guo-Fu Zhu  Lok Man Chu 《国际地质力学数值与分析法杂志》2004,28(2):111-129

This paper presents a finite layer procedure for Biot's consolidation analysis of layered soils using a cross-anisotropic elastic constitutive model. The program is first verified using published results. Then, using this program, the influences of cross-anisotropy on the immediate settlement, the final settlement, and the consolidation behaviour are investigated by changing one model parameter at one time. The results obtained using the cross-anisotropic elastic model are compared with results using an isotropic elastic model. It is found that the cross-anisotropy has very large influences on the immediate settlement, the final settlement, and the consolidation behaviour. Curves or tables of the immediate settlement coefficients, the final settlement coefficients, and the average degree of consolidation are obtained and presented in the paper. These curves or tables can be easily used to estimate the immediate settlement, the final settlement, and the consolidation settlement of a cross-anisotropic soil. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

江西信江流域硅质黄蜡石特征研究          下载免费PDF全文

杨小鹏 《地质找矿论丛》2018,33(3):393-398

江西黄蜡石具有亮丽悦目、光润如蜡的外表,其形态千变万化,具有一定的观赏价值,然而目前对其基础特征及形成研究甚少。文章以信江流域的硅质黄蜡石为研究对象,采用电感耦合等离子体质谱仪及电感耦合等离子体发射光谱仪、高倍率偏光显微镜、X-射线衍射分析仪等测试手段对样品进行了观测和分析。其研究结果表明,鹰潭硅质黄蜡石主要物质组成为玉髓和石英,含有少量黏土矿物、褐铁矿、赤铁矿、氧化锰和绢云母;颜色多为黄色、红色及其混合色;透明度为亚透明、半透明,呈显微隐晶质变晶、显微显晶质变晶结构;硬度6.5~7.0,密度2.53~2.81g/cm~3。折射率1.528~1.553(点测1.53~1.55)。并提出了鹰潭硅质黄蜡石质量评价初步方案。  相似文献   

汶川Ms8.0地震后龙门山断裂带地壳应力场及其构造意义     

丰成君  戚帮申  张鹏  孙东生  孟静  牛琳琳  王苗苗  谭成轩  陈群策 《地质力学学报》2018,24(4):439-451

2008年5月12日在青藏高原东缘龙门山断裂带中段发生汶川8.0级特大地震。大震发生时释放应力并对震源区及外围构造应力场产生影响,受汶川地震断层破裂方式和强度空间差异性的影响,震后龙门山断裂带地壳应力场也应表现差异特征,至今鲜有针对该科学问题深入的分析和讨论。经过系统收集、梳理汶川地震后沿龙门山断裂带水压致裂地应力测量数据与2008年汶川地震中强余震序列震源机制解资料,对汶川地震后龙门山断裂带中上地壳构造应力场进行厘定,通过与震前构造应力场对比,深入探讨了汶川8.0级地震对龙门山断裂带地壳应力场的影响,进而对汶川震后应力调整过程及青藏高原东缘龙门山地区深部构造变形模式进行研究,研究结果表明:受汶川8.0级地震的影响,震后龙门山断裂带地壳构造应力场空间分布具有差异性,近地表至上地壳15 km深度范围,映秀—青川段最大主应力方向为北西西向、地应力状态为逆走滑型,青川东北部最大主应力方向偏转至北东东向、应力状态转变为走滑型;15~25km深度范围,龙门山断裂带最大主应力方向仍为北西—北西西向、应力状态以逆冲型为主。汶川8.0级地震后,龙门山断裂带中地壳北西西向逆冲挤压的构造应力特征进一步支持了青藏高原东缘龙门山地区东西两侧刚性块体碰撞挤压、逆冲推覆的动力学模式。  相似文献   

Spatial distribution of soil shear-wave velocity and the fundamental period of vibration – a case study of the Saguenay region,Canada     

Thomas Foulon  Ali Saeidi  Romain Chesnaux  Miroslav Nastev  Alain Rouleau 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(1):74-86

The spatial distribution of soil shear-wave velocity and the fundamental period of vibration were selected as input parameters for the determination of potential seismic site effects in the Saguenay region, Canada. The methodology used in this study involved three clear steps. First, a 3D geological model of the surficial deposits was built taking into consideration the type, spatial distribution and thickness of the deposits. Second, representative average V_s values were determined for each of the major soil units. Finally, the average shear-wave velocity from the ground surface to bedrock (V_sav), the shear-wave velocity of the upper 30 m (V_s30) and the fundamental site resonance period (T₀) were calculated over a regular grid for the study area. The results include the spatial distribution of the fundamental site resonance period, the average shear-wave velocity in the first 30 m of the ground and the spatial distribution of National Building Code of Canada seismic soil classes for the Saguenay region.  相似文献   

Mapping the popularity of urban restaurants using social media data     

《Applied geography (Sevenoaks, England)》2015

Nowadays, geographers show growing interest in providing location-based services for urban residents. It is of great practical significance to screen and recommend the most popular restaurants to consumers, as dining is important to every urban dweller. Consumer review website (CRW) has emerged as an active social media platform in catering industry. This paper demonstrated how to quantify the popularity of urban restaurants (PUR) by using CRW, namely, Dianping.com. An applied popularity index (PI) was developed to quantify PUR, based on the consumer review scores (food, service, and decoration) and physical data (evaluation frequency and restaurant grade) for 8259 restaurants within the Hangzhou city, China. All the information, together with the geographic location data, was harvested from the corresponding Application Programming Interface (API) platform. PUR was then mapped by using a geographic information system (GIS). Results showed that restaurants of high popularity were generally concentrated in old urban districts, whereas those in new urban districts presented low popularity. The kernel density distribution of PI also highlighted the geography that the PI values declined from the central city toward the outskirts. Locational associations between PUR and urban functional units (bank, shopping mall, school, cinema, hotel, bar, and scenic spot) generally presented a similar tendency. Restaurants with high PI values were in high proximity to urban functional units, whereas those with low PI values were located far away from other functional units. It implied that restaurants with high popularity tended to be located in high mixture with urban functional units. Although we used Dianping.com to perform the analysis, the presented methodology can be extended to other types of CRWs. Our study is believed to provide new insights into applied geographic sciences.  相似文献   

四川省各市州公共服务供给空间的自相关分析     

宋雪茜  刘颖 《地域研究与开发》2015,(4)

通过空间自相关分析模型对2012年四川省各市州公共服务供给效率及空间相关性进行研究,结果表明:偏基本公共服务支出空间差异相对较小,但仍呈现出以成都市为中心向东部溢出的扇形扩散趋势;偏高级公共服务支出聚集程度过高,具有"中心-外围"空间溢出特征;灾后重建支出聚集在"5·12汶川大地震"灾区且对东部城市有一定的外溢;川西山区各类公共服务供给效率均较低,且呈现"低-低"相关的空间特点。公共服务供给效率及空间相关性受经济、政策和地理条件等综合因素影响。基于分析结果,建议针对不同类型公共服务应实施差异化空间供给策略,并针对山区实施特殊的公共服务供给政策。  相似文献   

‘When I think home I think family here and there’: Translocal and social ideas of home in narratives of migrant children and young people     

《Geoforum》2015

This paper offers theoretically informed empirical insights into migrant children’s experiences of mobility and home. Drawing on research into the first-generation children of Polish labour migrants in Scotland, the paper explores the meanings that children attach to home and other specific places. In particular, it focuses on questions of the translocal and social nature of migrant children’s sense of place and construction of home. The spoken narratives, subjective maps and drawings analysed here reflect children’s multiple and intersecting relationships and identifications, with both their country of origin and the host country, in addition to how their notion of home is grounded in social attachments. Emphasising the continuing importance of ‘place’ in migrant children and young people’s everyday experiences, the research concludes that subjective homemaking practices are just as important as objective educational attainment and other traditional social indicators in providing an understanding of the outcomes of migrant settlement. It also suggests that there is an emerging translocal identity among some young Polish migrants, whose changing understanding of home incorporates images and emotions from both their locality of origin and their current place of residence.  相似文献