No abstract

Regional gravity anomaly provides important information for the study of regional geologic structure and the division of tectonic units. The major concern of the geophysicists is how to obtain the detailed data of regional gravity using reliable methods. In this study, curvelet transform was used for the first time in the multi-scale analysis of data of regional gravity. As one method for multi-scale geometric analysis, curvelet transform overcomes the limitations of wavelet transform in representing the high-dimensional singularities such as edges and contours. When processing of the data of regional gravity, the curvelet transform can more effectively present the detailed information. In this study, the data of synthetic model was respectively used for the experiments based on the wrapping algorithm of second-generation curvelet transform in combination with translation of cycle, iterative operation and Monte Carlo strategy for threshold adjustment. The experimental results show that the curvelet transform is efficient in multiscale separation for the data of regional gravity. This technique provides reference to the application of relevant multiscale and multi-orientational transform methods in the processing of data of gravity.

Within the large scale fusion experimental device ITER, Ion Cyclotron Resonance Heating (ICRH) system is one of the three heating systems which will supply total heating power of 20 MW (40-55 MHz) up to one hour operation. Radio-Frequency (RF) contacts are integrated within the antennas for assembly and operation considerations, which will face extremely harsh service conditions, including neutron irradiation, heavy electrical loads (RF current reaches up to 2 kA with a linear current density of 4.8 kA/m), high thermal loads and also long-duration vacuum baking at 250°C before each experimental plasma campaign. CuCrZr and 316L steel have been shown to be proper base candidate materials for ITER RF contact louvers and conductors respectively. However, in order to limit the wear and the diffusion phenomena at the RF contact as well as to reduce the contact resistance, functional protective layers should be developed. The aim of this work is to investigate Au-Ni and Rh functional layers, electroplated on CuCrZr and 316L respectively. The efficiency of the Au-Ni/Rh coated pairs was evaluated through thermal ageing diffusion tests, using EDS cross-section mapping and XRD techniques. Wear and electrical contact performances of the Au-Ni/Rh original and thermally aged pairs have also been deeply studied on a dedicated tribometer operated at ITER relevant conditions.