Following the first‐time ionospheric imaging of a seismic fault, here we perform a case study on retrieval of parameters of the extended seismic source ruptured during the great M9.0 Tohoku‐oki ...earthquake. Using 1 Hz ionospheric GPS data from the Japanese network of GPS receivers (GEONET) and several GPS satellites, we analyze spatiotemporal characteristics of coseismic ionospheric perturbations and we obtain information on the dimensions and location of the sea surface uplift (seismic source). We further assess the criterion for the successful determination of seismic parameters from the ionosphere: the detection is possible when the line of sights from satellites to receivers cross the ionosphere above the seismic fault region. Besides, we demonstrate that the multisegment structure of the seismic fault of the Tohoku‐oki earthquake can be seen in high‐rate ionospheric GPS data. Overall, our results show that, under certain conditions, ionospheric GPS‐derived TEC measurements could complement the currently working systems, or independent ionospherically based system might be developed in the future.
Key Points
Parameters of seismic source can be deduced from 1Hz ionospheric GPS data
Ionosphere can visualize a multi‐segment structure of a seismic fault
CID velocity ~1.4 km/s points on either shock waves, or acoustic waves in water
Following the first-time ionospheric imaging of a seismic fault, here we perform a case study on retrieval of parameters of the extended seismic source ruptured during the great M9.0 Tohoku-oki ...earthquake. Using 1Hz ionospheric GPS data from the Japanese network of GPS receivers (GEONET) and several GPS satellites, we analyze spatiotemporal characteristics of coseismic ionospheric perturbations and we obtain information on the dimensions and location of the sea surface uplift (seismic source). We further assess the criterion for the successful determination of seismic parameters from the ionosphere: the detection is possible when the line of sights from satellites to receivers cross the ionosphere above the seismic fault region. Besides, we demonstrate that the multisegment structure of the seismic fault of the Tohoku-oki earthquake can be seen in high-rate ionospheric GPS data. Overall, our results show that, under certain conditions, ionospheric GPS-derived TEC measurements could complement the currently working systems, or independent ionospherically based system might be developed in the future. Key Points Parameters of seismic source can be deduced from 1Hz ionospheric GPS data Ionosphere can visualize a multi-segment structure of a seismic fault CID velocity ~1.4 km/s points on either shock waves, or acoustic waves in water
•Full 3D numerical model is applied to simulate the solidification of Sn-Pb alloy.•The effect of an alternative electromagnetic stirring was examined in this study.•All numerical results are compared ...to those of AFRODITE Benchmark setup experiences.•A focus is made on the segregated channel development and morphology.
3D numerical simulation of solidification was carried out for a benchmark experiment on a binary Sn-Pb alloy with rigorous controlled thermal boundary conditions. The experiment consists of solidifying a parallelepiped ingot of Sn-10wt.%Pb composition. The main objective is to give both details of 3D numerical simulation and experimental analysis of the effect of forced convection driven by an alternative traveling magnetic field on the solidification process of Sn-10wt.%Pb alloy. The experiment was carried out under an average experimental temperature difference (DT) equal to 40 K and a cooling rate of (-0.03 K/s). This slow-cooling condition has been used in order to promote segregation formation. A periodically reversed electromagnetic stirring (EM) case with a modulation frequency equal to 0.125 Hz has been investigated in this both numerical and experimental studies. During the solidification process, the time evolution of the temperature field is recorded by more than 68 thermocouples and analyzed. This enables us to determine the temperature evolution over time owing to forced convection. The patterns of the of solute (lead) concentration distribution obtained by numerical results are compared to the experimental X-ray radiographies. A post-mortem analysis is performed allowing us to determine the grain’s form and size in the final macrostructure. Results illustrate clearly that the EM stirring modifies the macrostructure in terms of columnar-equiaxed transition (CET), namely the grain refinement and, on the other hand, it significantly affects the segregation pattern, especially the segregated channel morphology and distribution. Indeed, it shows that this periodicity in the reversal electromagnetic stirring reduces significantly the macrosegregation corresponding to the last liquid solidified, while remaining inactive for reducing the development of segregated channels.
This paper presents a robust and reliable offline method for induction machine's rotor fault diagnosis, under low load conditions. This method is based on the analysis in frequency domain of the ...stator current envelope extracted by Hilbert transform. The proposed method, which is one of various demodulation techniques, is theoretically presented then experimentally validated by testing three different induction motors: one in a healthy condition, the second with one broken bar and the third with two broken bars. Each motor is subjected to three load conditions and supplied by voltage inverter which operates at different frequencies. The main results obtained by spectrum analysis of the stator current envelope are compared with these of the traditional MCSA method. The proposed method can successfully detect the fault under various operational situations, even for the lightly load, which makes it more suitable for induction motor fault diagnosis.
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