Role of Ordering Energy in Formation of Grain Structure and Special Boundaries Spectrum in Ordered Alloys with L12 Superstructure

It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special boundaries in coincidence sites of ordered alloys. It was determined that the more energy of special boundaries in ordered alloys, the more energy of complex stacking fault. There is a correlation between the distribution of special boundaries as a function its relative energy and ordering energy: the more ordering energy, the more degree of washed away of distribution. The correlation between average relative energy of special boundaries and ordering energy was detected: the more ordering energy, the more average energy of special boundaries. The reverse dependence between ordering energy and average number of special boundaries in grains limited by boundaries of general type was discovered.

Deep-detection of formation boundary using transient multicomponent electromagnetic logging measurements

The maximum distance at which an electromagnetic(EM)logging while drilling(LWD)tool detects an approaching boundary is defined as the depth of detection(DOD).Ultra-deep detection capability of the transient multicomponent EM logging measurement is investigated here.First,we adopt sine and cosine transform to calculate the transient multicomponent responses.Compared to the cosine transform,sine transform is more accurate in solving late-time responses.Then,a time-domain geosignal is introduced to sense the boundary.Results show that DOD of this transient EM measurement can be up to tens of meters,including directionally sensitivity.Additionally,by studying the decay characteristics of different components with time,cross component is confirmed to decay much faster than the coaxial/coplanar components in the formation coordinate system.A pseudo-inversion is thereby proposed to determine the dip angle of anisotropic stratified formation.Theoretical simulation results indicate that this algebraic method can determine the true dip at some particular moments.It is still stable and valid even when considering random measurement errors.Moreover,we establish the linear relationship between the time at which the half-point of geosignal curve appears and the distance to boundary(DTB),which would assist in the quick determination of DTB.

Elemental Geochemical Anomaly in the Sinian Doushantuo Formation-Dengying FormationBoundary in Miaohe, Hubei

No research has been made on such a lower rank boundary as the Sinian Doushantuo Formation-Dengying Formation boundary in the eastern region of the Yangtze Gorges. Elemental geochemical determination has revealed anomalies of REE and other trace elements around the boundary, which have relatively high contents than those in its overlying and underlying beds. The authors therefore think that a catastrophic event once occurred in the Miaohe area at the end of the Doushantuoan Period, which caused the mass extinction of the Miaohe biota.