Cascaded U-Net with Training Wheel Attention Module for Change Detection in Satellite Images

Change detection is an important application of remote sensing image interpretation, which identifies changed areas of interest from a pair of bi-temporal remote sensing images. Various deep-learning-based approaches have demonstrated promising results and most of these models used an encoder–decoder shape such as U-Net for segmentation of changed areas. In order to obtain more refined features, this paper introduces a change detection model with cascaded U-Net. The proposed network architecture contains four cascaded U-Nets with ConvNeXT blocks. With a patch embedding layer, the cascaded structure can improve detection results with acceptable computational overhead. To facilitate the training of the cascaded N-Nets, we proposed a novel attention mechanism called the Training whEel Attention Module (TEAM). During the training phase, TEAM aggregates outputs from different stages of cascaded structures and shifts attention from outputs from shallow stages to outputs from deeper stages. The experimental results show that our cascaded U-Net architecture with TEAM achieves state-of-the-art performance in two change detection datasets without extra training data

Chemical and structural studies of coexisting 1M-and 2M(1)-polytypes in synthetic fluorophlogopites and influence of Al on the polytype formation

Polytyism of micas is ubiquitous in natural rocks and can be used as an indicator of physical and chemical conditions in related diagenetic processes. To reveal the formation mechanisms of different polytypes, 1M- and 2M(1)-fluorophlogopite were synthesized using the melting method, and experiments with different Al concentration in the initial reactants were also performed. The structure refinement indicates that the space group of the 1M-fluorophlogopite is C2/m, and the lattice parameters are a=5.2941(4)angstrom, b=9.1773(6)angstrom, c=10.1061(7)angstrom, =100.141(7)degrees. The space group of the 2M(1)-fluorophlogopite is C2/c, and the lattice parameters are a=5.3094(16)angstrom, b=9.1973(28)angstrom, c=20.0442(60)angstrom, =95.141(7)degrees. The isomorphous substitution of Al3+ for Si4+ in tetrahedral sites of fluorophlogopite causes distortion in the layer structure, and results in a larger tetrahedral rotation angle , longer tetrahedral bond distance, smaller tetrahedral flattening angle , larger bond length difference between inner and outer potassium-oxygen ((mean)), and relative higher value of octahedral flattening angle . Our experimental results suggest that the content of structural Al has no correlation with the polytype formation, whereas the Al concentration in reactants influences the formation of 1M- and 2M(1)-fluorophlogopite

Six-DOF CFD Simulations of Underwater Vehicle Operating Underwater Turning Maneuvers

Maneuverability, which is closely related to operational performance and safety, is one of the important hydrodynamic properties of an underwater vehicle (UV), and its accurate prediction is essential for preliminary design. The purpose of this study is to analyze the turning ability of a UV while rising or submerging; the computational fluid dynamics (CFD) method was used to numerically predict the six-DOF self-propelled maneuvers of submarine model BB2, including steady turning maneuvers and space spiral maneuvers. In this study, the overset mesh method was used to deal with multi-body motion, the body force method was used to describe the thrust distribution of the propeller at the model scale, and the numerical prediction also included the dynamic deflection of the control planes, where the command was issued by the autopilot. Then, this study used the published model test results of the tank to verify the effectiveness of the CFD prediction of steady turning maneuvers, and the prediction of space spiral maneuvers was carried out on this basis. The numerical results show that the turning motion has a great influence on the depth and pitch attitude of the submarine, and a “stern heavier” phenomenon occurs to a submarine after steering. The underwater turning of a submarine can not only reduce the speed to brake but also limit the dangerous depth. The conclusion is of certain reference significance for submarine emergency maneuvers