Y.T. Zhou

Strain-induced preferential dissolution at the dislocation emergences in MnS: an atomic scale study

The long-standing problem of dislocation-preferential dissolution in a crystal has been generally ascribed to the distortion energy stored in the vicinity of the dislocation core. However, due to lack of experimental means, the relationship between the local distortion state and the electrochemical behaviour of a single dislocation has not been established so far. via in situ ex-environment transmission electron microscopy (TEM), we demonstrate that the emergences of both edge and screw dislocations on MnS surfaces are the preferential sites for dissolution of the MnS inclusions within a stainless steel. In addition, we map the strain-induced variation of the standard electrode potential around the edge dislocation by a combination of the aberration-corrected high-resolution TEM and strain-analysis-based mechanochemistry theory. Significantly, our report provides a new approach to investigate the strain–corrosion correlation at an atomic scale.

Research on Eco-environmental Data Visualization for Three Gorges Project

Data visualization can represent clearly the data difference and data change trend. It can help scientific researchers find the rules and trends behind the data quickly. In the process of monitoring eco-environment in Three Gorges reservoir area, a large database (≫ TB) of data has been acquired. How to fully utilize these data to analyze the trend and evaluate the eco-environmental impact of Three Gorges Project (TGP) is the problem that governments and research scientists urge to solve. It is necessary to attach importance to data visualization and data mining. In order to manage and use these data, Eco-environmental Monitoring Information System of Three Gorges Project is developed. The development platform of the information system is VC.net and ArcIMS (WebGIS development platform). The data in magnitude are stored in the large database of Oracle 10g. The management and use of spatial data are through ArcSDE and Oracle 10g. Due to that the monitoring network is cross-region, cross-department, multi-subject, multi-hierarchy, it results in the data visualization and analysis is very difficult. The paper introduces the method of data process and storage. It illustrates theme-oriented data visualization and its implementation in the information system. Multi-style innovative theme-objected data representation in eco-environmental data visualization is put forward. The techniques of WebGIS and office web component (OWC) provide support to the fast development of data visualization modules. The data visualization in the information system has enhanced the efficiency of data analysis and data mining in great degree. Moreover, it provides great help to governments and scientific researchers.

Wavelet-SVM classifier based on texture features for land cover classification

Texture features are recognized to be a special hint in images, which represent the spatial relations of the gray pixels. Nowadays, the applications of the texture analysis in image classification spread abroad. Combined with wavelet multi-resolution analysis or support vector machine statistical learning theory, texture analysis could improve the quality of classification increasingly. In this paper, we focus on the land cover for the Three Gorges reservoir using remote sensing data SPOT-5, a new classification method, wavelet-SVM classifier based on texture features, is employed for this study. Compare to the traditional maximum likelihood classifier and SVM classifier only use spectrum feature, this method produces more accurate classification results. According to the real environment of the Three Gorges reservoir land cover, a best texture group is selected from several texture features. Decompose the image at different levels, which is one of the main advantage of wavelet, and then compute the texture features in every sub-image, and the next step is eliminating the redundant, every texture features are centralized on the first principal components using principal component analysis. Finally, with the first principal components inputted, we can get the classification result using SVM in every decomposition scale, but what the problem we couldnt overlook is how to select the best SVM parameters. So an iterative rule based on the classification accuracy is induced, the more accuracy, the proper parameters.

Atomic structure of the Fe/Fe3C interface with the Isaichev orientation in pearlite

Abstract The pronounced mechanical property of pearlitic steels highly correlates with the ferrite (bcc-Fe)/cementite (Fe3C) boundaries inside. Unraveling the interface structure at an atomic level is essential for interpreting the material’s property. In the present study, using aberration-corrected scanning/transmission electron microscopy combined with density functional theory calculations, we reveal the atomic configuration as well as the electronic structure of the Fe/Fe3C interfaces with the Isaichev orientation in pearlite. The interface with terminating layer Fe–C–Fe in cementite has the lowest energy due to the formation of interfacial Fe–C bonds. Terrace steps which are frequently observed at the interfaces would not break the lattice match between the two phases.

Unravelling the local ring-like atomic pattern of twin boundary in an Mg-Zn-Y alloy

ABSTRACT Understanding the interactions between deformation twins and plate-like phases in magnesium alloys is one of the key issues to tailor the microstructure of magnesium alloys for better mechanical properties. The {102} twin boundary with the local ring-like atomic pattern in magnesium alloy, accompanied by the interaction between deformation twin and solute atoms, has been investigated using aberration-corrected scanning transmission electron microscopy. We found that these boundaries featured local overlapping morphology near the intersection between deformation twins and stacking faults (SFs) enriched with solute atoms. The overlapping morphology is proposed to be induced by the asynchronous shuffling of the SFs and matrix during the twinning. The local ring-like atomic patterns shown here imply that the shearable specific SFs in magnesium alloys will increase twinning energy and resultantly hinder twinning propagation.