Hausmann H.,Vienna University of Technology |
Hausmann H.,Central Institute for Meteorology and Geodynamics ZAMG |
Krainer K.,University of Innsbruck |
Bruckl E.,Vienna University of Technology |
Ullrich C.,Federal Office of Metrology and Surveying BEV
Austrian Journal of Earth Sciences | Year: 2012
In this study we use a concept based on three geophysical methods (Ground-penetrating radar/GPR, seismic refraction, gravimetry) to provide new insight into the internal structure, ice content and dynamics of the two active rock glaciers Ölgrube and Kaiserberg. Both rock glaciers are located in side valleys of the Kauner Valley (Ötztal Alps, Austria) and consist of debris derived from orthogneiss, paragneiss and mica schist. At both rock glaciers we determined a 4 - 6 m thick debris layer at the surface (active layer), underlain by 20 - 30 m of ice-rich permafrost, and 10 - 15 m of ice-free sediments. The average depth to the bedrock was found in 35 - 50 m. Estimated volumetric ice contents vary between 40 and 60% based on our field measurements. Structural and physical parameters derived from the mentioned surface based geophysical methods are used to explain the dynamics of the rock glaciers. From the two rock glaciers that were investigated in this study and one additional rock glacier, which was investigated by applying the same methodology in an earlier study, we found a parameter that describes their creep behaviour and shows that the three geophysical models are conclusive. Concerning the dynamics of these active rock glaciers, the data indicate that a reduction of the ice content causes an increase of internal friction, lower seismic P-wave velocities, and higher bulk densities. In order to keep a degrading rock glacier in motion a thickening is required. The GPR-reflection patterns of the permafrost layer and their relation to the structural and physical parameters primarily reveal that long reflectors parallel to the surface are found in regions with high P-wave velocity and low density, indicating zones with high ice content.
Jiang Z.,Bureau International des Poids et Mesures BIPM |
Francis O.,University of Luxembourg |
Vitushkin L.,Bureau International des Poids et Mesures BIPM |
Palinkas V.,Research Institute of Geodesy |
And 35 more authors.
Metrologia | Year: 2011
The Bureau International des Poids et Mesures (BIPM), Sèvres, France, hosted the 7th International Comparison of Absolute Gravimeters (ICAG) and the associated Relative Gravity Campaign (RGC) from August to September 2005. ICAG 2005 was prepared and performed as a metrological pilot study, which aimed: To determine the gravity comparison reference values; To determine the offsets of the absolute gravimeters; and As a pilot study to accumulate experience for the CIPM Key Comparisons. This document presents a complete and extensive review of the technical protocol and data processing procedures. The 1st ICAG-RGC comparison was held at the BIPM in 1980-1981 and since then meetings have been organized every 4 years. In this paper, we present an overview of how the meeting was organized, the conditions of BIPM gravimetric sites, technical specifications, data processing strategy and an analysis of the final results. This 7th ICAG final report supersedes all previously published reports. Readings were obtained from participating instruments, 19 absolute gravimeters and 15 relative gravimeters. Precise levelling measurements were carried out and all measurements were performed on the BIPM micro-gravity network which was specifically designed for the comparison. © 2011 BIPM & IOP Publishing Ltd.
Bosco G.C.,INRIM - Istituto Nazionale di Ricerca Metrologica |
Garcocz M.,Federal Office of Metrology and Surveying BEV |
Lind K.,Norwegian Metrology Service |
Pogliano U.,INRIM - Istituto Nazionale di Ricerca Metrologica |
And 4 more authors.
IEEE Transactions on Instrumentation and Measurement | Year: 2011
A comparison of the phase error of existing shunts for currents between 10 and 100 A and frequencies from 500 Hz to 100 kHz has been organized. Measurement processes were performed at Istituto Nationale di Ricerca Metrologica on some shunts using the first prototype of a new type of a phase comparator and a step-up method for data processing. Results of the relative measurement processes have shown good repeatability. The method for evaluation of reference values was based on similar shunts and suitable assumptions and derived by extrapolation. For the type of resistance elements employed in these shunts, the derivation of the reference is not very accurate and still needs to be improved. © 2006 IEEE.
Stanga D.,Horia Hulubei National Institute of Physics and Nuclear Engineering |
Maringer F.J.,Federal Office of Metrology and Surveying BEV |
Ionescu E.,Horia Hulubei National Institute of Physics and Nuclear Engineering
Applied Radiation and Isotopes | Year: 2011
A new method has been developed for determining the efficiency of large-area beta sources in anodized aluminum foils using transmission measurements. The method was applied to the efficiency measurement of a 90Sr-90Y large-area reference source. Measurement results show that the method can provide efficiency values for 90Sr-90Y reference sources with standard uncertainties smaller than 2.9%, which are far below the limit of 10% required by ISO 8769. © 2010 Elsevier Ltd.