It is a general trend to adopt the geocentric coordinate system as a geodetic datum for the international measurement community. The definition and realization of Chinese geocentric three-dimensional coordinate system (CGCS2000) which has been employed since July 1st, 2008 were introduced in detail. The defining parameters and derived constants of the reference ellipsoid used were given. The comparison between CGCS2000 and WGS84 was carried out. The differences of geodetic coordinates of a point between the two coordinate systems, normal gravity and vertical gradient of normal gravity on the two ellipsoids caused by the change of the flattening of the ellipsoid were analyzed. The results show that these differences could be neglected in view of present measurement accuracies.
Definitions of polar Gauss and stereographic projections are introduced, and the two projections sketches of the Arctic Circle are drawed with the help of Geocart software, according to these two projections formulae. From the angles of real and complex numbers respectively, direct transformations formulae between polar Gauss and stereographic projections are derived through series of derivations. Finally, correctness and reliabilities of the formulae are tested and verified by numerical examples by comparing the calculated coordinates of the projections formulae with the calculated coordinates of the projection transformations formulae. The formulae have universal applicability, and it can provide reference for polar mapping and navigation.
Traditional kinematic baseline resolution usually needs one or more fixed reference station. In some special application, the reference stations could be in motion. In order to determine kinematic baselines in scenarios of moving reference stations and rovers, a KINRTK model is studied by using a baseline length constraint with three antenna configuration. The baseline and integer resolution method are given. A KINRTK experiment is done, using the data collected on ship enroute, the resolved baselines lengths are compared with the predetermined baselines, which show that the KINREK models baseline length errors are within 5cm, which can verify the effectiveness and accuracy of the model proposed and ambiguity resolution method.
It is very dangerous for AUV and other vehicles to traverse through the ocean, where there are many barriers. Some technologies such as active sonar and blue-green lasers can not be used to explore these barriers in some special realm, because signal is sent out during the exploring. In order to solve this problem, a new method by using the character of the submarine topography will engender gravity gradient is proposed. An example of calculate the gravity gradient of a subulate topography is given, from the example can find that the gravity gradient aroused by the barrier is very large and can be observed by the gradiometer easily, the result proved the method of this paper is feasible. This study provided a new method for the underwater carrier to avoidance collision, and the method has passive and all-weather characters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.