A Fixed-Point Iterative Method for Discrete Tomography Reconstruction Based on Intelligent Optimization

Discrete Tomography(DT)is a technology that uses image projection to reconstruct images.Its reconstruction problem,especially the binary image(0–1matrix)has attracted strong attention.In this study,a fixed point iterative method of integer programming based on intelligent optimization is proposed to optimize the reconstructedmodel.The solution process can be divided into two procedures.First,the DT problem is reformulated into a polyhedron judgment problembased on lattice basis reduction.Second,the fixed-point iterativemethod of Dang and Ye is used to judge whether an integer point exists in the polyhedron of the previous program.All the programs involved in this study are written in MATLAB.The final experimental data show that this method is obviously better than the branch and bound method in terms of computational efficiency,especially in the case of high dimension.The branch and bound method requires more branch operations and takes a long time.It also needs to store a large number of leaf node boundaries and the corresponding consumptionmatrix,which occupies a largememory space.

Spatio-temporal Evolution of Landscape Pattern and Habitat Quality in Yunnan Province

[Objectives]The paper was to explore the spatio-temporal evolution of habitat quality in inland ecosystem.[Methods]Using landscape pattern analysis and InVEST habitat quality model,the land use change,landscape pattern and habitat quality change in Yunnan Province from 1980 to 2020 were studied.[Results]The land use change in Yunnan Province was relatively stable,and the forest land area accounted for 57.2%of the total area.The landscape fragmentation index caused by artificial surface encroachment on ecological land was increased by 6.33%,and the landscape heterogeneity was enhanced to varying degrees.The mean patch area was decreased by 5.83%,the number of patches was increased by 6.29%,and the degree of fragmentation was deepened.The habitat quality in Yunnan Province showed a"high-low-high"distribution from northwest to southeast,and the overall habitat quality was above the average.It is necessary to formulate optimization strategies to improve the regional ecological environment and realize the ecological system protection and rational land use in Yunnan Province.[Conclusions]The results will provide a scientific reference for regional ecological protection construction and land use planning in Yunnan Province.

Chemoselective reduction of α,β-unsaturated ketones to allylic alcohols under catalyst-free conditions

Chemoselective reductions ofα,β-unsaturated ketones to afford the corresponding allylic alcohols have always been challenging.Precious metals and ligands have always been employed in these transform-ations.