Jérémie Courtois

Sorption of plutonium on geological materials associated with a Chinese radioactive waste repository: influence of pH

The aim of this study is to characterize plutonium sorption particularly 239Pu distribution coefficients and the influence of pH on sorption processes in saturated geological materials used as a radioactive waste repository in China. The examined geological media is from a southwestern Chinese repository and consists of soil and slates. The backfill material consists of Na-bentonite from Inner Mongolia Gaomiaozi, and will be used at the Beishan high-level waste (HLW) repository, Gansu Province. The results show that the sorption capacity of Pu by geological medium in an acidic environment is low, but significantly increases with increasing pH.

pH-Induced fragmentation of colloids based on responsive self-assembled copper(II) metallopolymers

Colloidal particles based on self-assembled Cu2+ coordination polymers were fabricated following a one-step process. These particles were shown to be stimuli-responsive. In particular they can be readily disassembled in acidic conditions. This effect originates from a pH-induced fragmentation of the polymer chains into dinuclear Cu2+ complexes.

A New First Break Picking for Three-Component VSP Data Using Gesture Sensor and Polarization Analysis

A new first break picking for three-component (3C) vertical seismic profiling (VSP) data is proposed to improve the estimation accuracy of first arrivals, which adopts gesture detection calibration and polarization analysis based on the eigenvalue of the covariance matrix. This study aims at addressing the problem that calibration is required for VSP data using the azimuth and dip angle of geophones, due to the direction of geophones being random when applied in a borehole, which will further lead to the first break picking possibly being unreliable. Initially, a gesture-measuring module is integrated in the seismometer to rapidly obtain high-precision gesture data (including azimuth and dip angle information). Using re-rotating and re-projecting using earlier gesture data, the seismic dataset of each component will be calibrated to the direction that is consistent with the vibrator shot orientation. It will promote the reliability of the original data when making each component waveform calibrated to the same virtual reference component, and the corresponding first break will also be properly adjusted. After achieving 3C data calibration, an automatic first break picking algorithm based on the autoregressive-Akaike information criterion (AR-AIC) is adopted to evaluate the first break. Furthermore, in order to enhance the accuracy of the first break picking, the polarization attributes of 3C VSP recordings is applied to constrain the scanning segment of AR-AIC picker, which uses the maximum eigenvalue calculation of the covariance matrix. The contrast results between pre-calibration and post-calibration using field data show that it can further improve the quality of the 3C VSP waveform, which is favorable to subsequent picking. Compared to the obtained short-term average to long-term average (STA/LTA) and the AR-AIC algorithm, the proposed method, combined with polarization analysis, can significantly reduce the picking error. Applications of actual field experiments have also confirmed that the proposed method may be more suitable for the first break picking of 3C VSP. Test using synthesized 3C seismic data with low SNR indicates that the first break is picked with an error between 0.75 ms and 1.5 ms. Accordingly, the proposed method can reduce the picking error for 3C VSP data.

A RAPID SEISMIC DATA CALIBRATION TECHNIQUE USING INTEGRATED MEMS INERTIAL SENSOR GROUPS FOR A THREE-COMPONENT VSP

Calibration of 3C VSP data is an exciting challenge because the orientation of the tool is random when only seismic data is considered. In this work we augment the sensor package on the VSP tool with MEMS inertial sensors and apply a gesture measuring method to determine the tool orientation and calibration. This technique can quickly produce high-precision, orientation and angle information when integrated with the seismometer. The augmented sensor package consists of a low-cost triaxial MEMS gyroscope, an electronic compass and an accelerometer. The technique to process the gesture information is based on the OpenGL software for 3D modeling. We have tested this approach on a large number of field datasets and it appears to be faster and more reliable than other approaches.

A rapid seismic data calibration technique using integrated micro-electro-mechanical system inertial sensor groups for a 3C vertical seismic profileRapid data calibration for 3C VSP

Calibration of 3C VSP data is an exciting challenge because the orientation of the tool is random when only seismic data is considered. In this work we augment the sensor package on the VSP tool with MEMS inertial sensors and apply a gesture measuring method to determine the tool orientation and calibration. This technique can quickly produce high-precision, orientation and angle information when integrated with the seismometer. The augmented sensor package consists of a low-cost triaxial MEMS gyroscope, an electronic compass and an accelerometer. The technique to process the gesture information is based on the OpenGL software for 3D modeling. We have tested this approach on a large number of field datasets and it appears to be faster and more reliable than other approaches.

A rapid seismic data calibration technique using integrated micro-electro-mechanical system inertial sensor groups for a 3C vertical seismic profile

Calibration of 3C VSP data is an exciting challenge because the orientation of the tool is random when only seismic data is considered. In this work we augment the sensor package on the VSP tool with MEMS inertial sensors and apply a gesture measuring method to determine the tool orientation and calibration. This technique can quickly produce high-precision, orientation and angle information when integrated with the seismometer. The augmented sensor package consists of a low-cost triaxial MEMS gyroscope, an electronic compass and an accelerometer. The technique to process the gesture information is based on the OpenGL software for 3D modeling. We have tested this approach on a large number of field datasets and it appears to be faster and more reliable than other approaches.

An improved lossless group compression algorithm for seismic data in SEG-Y and MiniSEED file formats

An improved lossless group compression algorithm is proposed for decreasing the size of SEG-Y files to relieve the enormous burden associated with the transmission and storage of large amounts of seismic exploration data. Because each data point is represented by 4 bytes in SEG-Y files, the file is broken down into 4 subgroups, and the Gini coefficient is employed to analyze the distribution of the overall data and each of the 4 data subgroups within the range [0,255]. The results show that each subgroup comprises characteristic frequency distributions suited to distinct compression algorithms. Therefore, the data of each subgroup was compressed using its best suited algorithm. After comparing the compression ratios obtained for each data subgroup using different algorithms, the Lempel-Ziv-Markov chain algorithm (LZMA) was selected for the compression of the first two subgroups and the Deflate algorithm for the latter two subgroups. The compression ratios and decompression times obtained with the improved algorithm were compared with those obtained with commonly employed compression algorithms for SEG-Y files with different sizes. The experimental results show that the improved algorithm provides a compression ratio of 7580%, which is more effective than compression algorithms presently applied to SEG-Y files. In addition, the proposed algorithm is applied to the miniSEED format used in natural earthquake monitoring, and the results compared with those obtained using the Steim2 compression algorithm, the results again show that the proposed algorithm provides better data compression. An algorithm was proposed to compress losslessly the SEG-Y and miniSEED Files.It describes the distribution of SEG-Y and miniSEED files using Gini coefficient.Different data sub-groups should use different compression algorithms.The improved algorithm can achieve a better compression ratio of 7580%.It provides a better compression ratio than the Steim2 to miniSEED Files.