GPS高程拟合在地籍测量中的应用

在一般的地形测量中,GPS测量已成为获得点的平面坐标的最主要的方法。但是,GPS 3维坐标中测得的大地高未能在生产实际中发挥应有的作用。因此,需将GPS大地高转换成正常高。本文在实地的地形测量中,根据已有点的高程数据和联测的GPS高程数据,采用等值线图示法和平面拟合法对测区内进行GPS高程拟合,并对两种方法的拟合精度进行比较。最终认为在平坦地区等值线图示法要比平面拟合法更好些。     

激光跟踪仪用于大型预埋板形位误差的检测

根据激光跟踪测量系统的特点,结合工程实例,用跟踪仪自由设站测得预埋板所要检测的数据;用平面拟合、直线拟合、坐标转换等数据处理方法,得出偏差数据,很好地对预埋板的形位误差进行了检测,以便设计、施工的需要。     

南方单基站CORS技术在工程放样中的应用

简要介绍了单基站CORS定位技术原理以及CORS的基本算法和发布方式。比较了单基站CORS和常规RTK定位技术,体现了CORS系统的优势。着重介绍了使用单基站CORS放样的具体步骤,包括点位放样、直线放样和曲线放样。为今后工程提供参考。     

输电线路状态监测的GIS平台设计与实现

本文分析了电力工业输电线路状态监测工作中对GIS的需求,结合输电线路状态监测的特点,提出了基于SOA架构的二三维一体化输电线路状态监测GIS平台建设思路,开发了原型系统,实现了输电线路及其状态在三维环境下的展示、分析、模拟和实时信息查询,对实现输电线路状态空间监测具有参考意义。     

Utilizing the Audio-Tutorial Approach

Abstract

Construction of raised-relief maps by students in middle school to high school is a rewarding “hands-on” experience. A major feature of this project is that materials are readily available, inexpensive and manageable by students themselves. Tracing from topographic maps on to inexpensive, easily-carved materials like cardboard or foam-core board involves the student in map interpretation techniques. Concepts such as interpreting elevations from contour lines, recognizing symbolization on a map, seeing raised-relief as representing “the lay of the land,” understanding map scale, and recognition of color in representation of elevations are part of this experience. Carving and construction of the raised-relief map give the student an appreciation of topographic features in 3-D. The finished model can serve as a display and learning tool for the future.     

GPS在高精度基准线精密测量中的应用

针对高精度火箭橇实验滑轨基准线基准点间距短、密度大、测量精度要求高的特点,分析了GPS短基线定位误差的影响,对高精度基准线GPS网的测量精度、坐标基准、网形、观测及数据处理方法进行了设计,并对测量成果进行了精度分析。结果表明,GPS相对定位技术是高精度基准线精密测量的一种有效方法。     

Gravitationally distorted P Cygni profiles from outflows near compact objects

We consider resonant absorption in a spectral line in the outflowing plasma within several tens of Schwarzschild radii from a compact object. We take into account both Doppler and gravitational shifting effects and reformulate the theory of P Cygni profiles in these new circumstances. It is found that a spectral line may have multiple absorption and emission components depending on how far the region of interaction is from the compact object and what the distribution of velocity and opacity is. Profiles of spectral lines produced near a neutron star or a black hole can be strongly distorted by Doppler blue- or redshifting and gravitational redshifting. These profiles may have both red- and blueshifted absorption troughs. The result should be contrasted with classical P Cygni profiles, which consist of redshifted emission and blueshifted absorption features.
We suggest that this property of line profiles to have complicated narrow absorption and emission components in the presence of strong gravity may help researchers to study spectroscopically the innermost parts of an outflow.     

A relativistically smeared spectrum in the neutron star X-ray binary 4U 1705−44: looking at the inner accretion disc with X-ray spectroscopy

Iron emission lines at 6.4–6.97 keV, identified with fluorescent Kα transitions, are among the strongest discrete features in the X-ray band. These are therefore one of the most powerful probes to infer the properties of the plasma in the innermost part of the accretion disc around a compact object. In this paper, we present a recent XMM–Newton observation of the X-ray burster 4U 1705−44, where we clearly detect a relativistically smeared iron line at about 6.7 keV, testifying with high statistical significance that the line profile is distorted by high-velocity motion in the accretion disc. As expected from disc reflection models, we also find a significant absorption edge at about 8.3 keV; this feature appears to be smeared, and is compatible with being produced in the same region where the iron line is produced. From the line profile, we derive the physical parameters of the inner accretion disc with large precision. The line is identified with the Kα transition of highly ionized iron, Fe  xxv , the inner disc radius is   R _in= 14 ± 2  R _g  (where R _g is the Gravitational radius,   GM / c ²  ), the emissivity dependence from the disc radius is   r ^{−2.27±0.08}  , the inclination angle with respect to the line of sight is   i = 39°± 1°  . Finally, the XMM–Newton spectrum shows evidences of other low-energy emission lines, which again appear broad and their profiles are compatible with being produced in the same region where the iron line is produced.