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Journal of Geographical Systems - Auckland, the largest city of New Zealand, is one of the most diverse cities in the world, with more than 40% of its population born abroad, more than 200... 相似文献
315.
简述了原国家重力基本网(57网)的历史和技术要点,详细地分析了57网的各类误差和产生原因,提出了新、旧系统转换的方法。本文研究表明,57网基本点相对观测的实际精度约为±0.06mgal,仪器平均值误差为1.6×10~(-4)。基本点重力值含-13.56mgal的基准误差和1.9×10~(-4)的尺度差,并含有±0.1~0.2mgal的非线性系统误差。对基本点实行新、旧系统转换误差为±0.05mgal,基本不损失其观测精度。 相似文献
316.
The resolution of a nonlinear parametric adjustment model is addressed through an isomorphic geometrical setup with tensor
structure and notation, represented by a u-dimensional “model surface” embedded in a flat n-dimensional “observational space”.
Then observations correspond to the observational-space coordinates of the pointQ, theu initial parameters correspond to the model-surface coordinates of the “initial” pointP, and theu adjusted parameters correspond to the model-surface coordinates of the “least-squares” point
. The least-squares criterion results in a minimum-distance property implying that the vector
Q must be orthogonal to the model surface. The geometrical setup leads to the solution of modified normal equations, characterized
by a positive-definite matrix. The latter contains second-order and, optionally, thirdorder partial derivatives of the observables
with respect to the parameters. This approach significantly shortens the convergence process as compared to the standard (linearized)
method. 相似文献
317.
Accurate geocentric three dimensional positioning is of great importance for various geodetic and oceanographic applications.
While relative positioning accuracy of a few centimeters has become a reality using Very Long Baseline Interferometry (VLBI), the uncertainty in the offset of the adopted coordinate system origin from the geocenter is still believed to be of the
order of one meter. Satellite Laser Ranging (SLR) is capable of determining this offset to better than10 cm, though, because of the limited number of satellites, this requires a long arc of data. The Global Positioning System (GPS) measurements provide a powerful alternative for an accurate determination of this origin offset in relatively short period
of time. Two strategies are discussed, the first utilizes the precise relative positions predetermined byVLBI, where as the second establishes a reference frame by holding only one of the tracking sites longitude fixed. Covariance
analysis studies indicate that geocentric positioning to an accuracy of a few centimeters can be achieved with just one day
of preciseGPS pseudorange and carrier phase data. 相似文献
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319.
V. M. Zobin E. I. Gordeev V. F. Bakhtiarov E. I. Ivanova Yu. M. Khatkevich V. N. Khodenko V. E. Levin V. P. Mityakin 《Natural Hazards》1992,6(1):51-70
The earthquake of 6 October 1987 (M = 6.6), which occurred near the Shipunsky Cape, Kamchatka, was the largest crustal event in the vicinity of the main city of Kamchatka — Petropavlovsk-Kamchatsky — during the last three decades. It was followed by numerous aftershocks. This earthquake allowed us to test the effectiveness of the seismic hazard monitoring in Kamchatka, including the seismological, geodetic and hydrogeochemical surveys. The seismic survey provided the location and source nature of the main shock and aftershocks and the seismic environment of the main shock. The geodetic and hydrogeochemical surveys have yielded data on the response to earthquakes of the Earth's surface deformations, water level, and chemical elements concentration in the underground water. As a result, the following data were obtained: The earthquake of 6 October had a seismic moment 4–10 E18 Nm, thrust type of faulting and the source volume of 20 × 20 × 10 km3. The maximum intensity was VI–VII (MSK-64 scale) and maximum acceleration 88 cm/s2. Before this event, a relative increase in the number of the upper mantle (depth more than 100 km) moderate magnitude earthquakes during 5 years and a one-year period of seismic quiescence for small shallow earthquakes, were recognized. Significant anomalies in HCO3 and H3BO3 concentrations in the underground waters were observed in the wells a week before the main shock. 相似文献
u
320.
Palaeomagnetism of Holocene lake sediments from north Poland 总被引:1,自引:0,他引:1
K. M. Creer E. Hogg Z. Malkowski J. E. Mojski E. Niedziolka-Krol P. W. Readman P. Tucholka 《Geophysical Journal International》1979,59(2):287-313
Summary. Detailed palaeomagnetic investigations of 17 cores of Holocene lake sediments from four lakes in Poland show a pattern of declination variations similar to those found in Lake Windermere, England and in addition a well defined pattern of inclination variations. A total of nine inclination swings are observed compared to five declination swings and their phase relationships are such that both sets of swings cannot be periodic. Exact dating of the palaeomagnetic record is not possible as radiocarbon ages are over 1000 yr older than those deduced from palynological studies. Thermomagnetic and X-ray studies on magnetic concentrates confirm the results of studies of remanence cooling, IRM acquisition and coercivity experiments which are consistent with fine grained magnetite as the main magnetic mineral in the sediments. 相似文献