Multi-Stage Fluid System Responsible for Ore Deposition in the Ossa-Morena Zone (Portugal): Constraints in Cu-Ore Deposits Formation     

Maia  M.  Moreira  N.  Vicente  S.  Mirão  J.  Noronha  F.  Nogueira  P. 《Geology of Ore Deposits》2020,62(6):508-534

Geology of Ore Deposits - The Mociços Cu-deposit is part of a cluster of ancient copper mines in the Sousel-Barrancos metallogenic belt in the Ossa-Morena Zone at the SW Iberia. The orebodies...  相似文献   

Advantages and Disadvantages of the MERIT Campaigns     

R. O. Vicente 《Astronomische Nachrichten》1984,305(1):31-32

The campaigns of the programme of international cooperation, called MERIT, for the determination of the earth rotation parameters are reviewed, especially about the difficulties to infer results about polar motion from such short intervals of observations. It is pointed out the need to employ the same models and standards in order to facilitate the comparison of data obtained by classical and modern techniques.  相似文献   

Polar motion estimates from linear combinations of independent series     

R. O. Vicente  C. R. Wilson 《Astronomische Nachrichten》1986,307(2):137-147

This paper describes methods for combining independent observations of polar motion into a single time series, and applies these methods to satellite laser ranging, Doppler, and astrometric polar motion data taken over the period 1981--1983. The polar motion data are treated as complex valued time series, yielding one estimate of the noise level for each series, rather than a separate estimate for X and Y components. Estimates of the noise level which take advantage of the existence of simultaneous observations are preferred. Linear combination of the data may be performed in both the time and the frequency domain, and examples of each are present. The results of analyzing three years of observations show little difference between the Allan and conventional variance. Present day Doppler determinations do not show marked improvement compared to classical astrometric results. Thus, the astrometric observations are still useful.  相似文献   

Estimates of Chandler's Component of Polar Motion as Derived from Various Data Sets     

C. R. Wilson  R. O. Vicente 《Astronomische Nachrichten》1981,302(5):227-232

Data sets consisting of several combinations of classical and modern techniques (Doppler and laser ranging to artificial sattellites) have been analysed by autoregressive (AR), sinusoidal and autoregressive moving averag (ARMA) methods in order to obtain estimates of the frequency and quality factor of the Chandler component of polar motion. The ARMA method shows advantages over the other methods and the results obtained do not furnish evidence of temporal variation in these polar motion parameters. The disadvantages associated with smoothing the data sets and the difficulties as sociated with short time intervals for the data are cleary demonstrated. There is a great need for regular and long observational series obtained by the modern techniques.  相似文献