Rapid land-use change has taken place in many arid and semi-arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. In this paper, land-use change dynamics were investigated by the combined use of satellite remote sensing and geographical information systems (GIS). Our objectives were to determine land-use transition rates among land-use types in Yulin prefecture over 14 years from 1986-2000 and to quantify the changes of various landscape metrics using FRAGSTATS, the spatial pattern analysis program for Categorical Maps. Using 30-m resolution Landsat Thematic Mapper (TM) data from the Institute of Remote Sensing Application (IRSA) in China, we classified images into six land-use types: cropland, forestland, grassland, water, urban and/or built-up land, and barren land. Significant changes in land-use occurred within the area over the study period. The results show the significant decrease in barren land was mainly due to conversion to grassland. Cropland increased by 3.39%, associated with conversions from grassland and barren land. The landscape has become more continuous, clumped and more homogeneous. The study demonstrates that the integration of satellite remote sensing and GIS was an effective approach for analysing the direction, rate and spatial pattern of land-use change.
Supposing the existence of modified Chaplygin gas with the equation of state $p=A\rho-B/\rho^\beta$ as a cosmic background, we obtain a static spherically-symmetric black hole solution to the Einstein-Gauss-Bonnet gravitational equations in 5D spacetime. The spacetime structure of the obtained black hole solution is analyzed, also the related black hole properties are studied by calculating the thermodynamical quantities. During this process, effects of the Gauss-Bonnet coupling constant and the modified Chaplygin gas parameters on black hole solution, as well as on its thermodynamical properties are discussed. At the end, we study the quantum tunneling of scalar particles and the propagating of scalar waves within the background of modified Chaplygin gas. The study shows that the system is stable under scalar perturbations and the Hawking radiation could stop at some point, leaving an extremal black hole as remnant for evaporation.
The dielectric relaxations in six primary and secondary alkoxy alcohols with varying molecular size and different separation between -O- and hydroxyl group are studied at temperatures around glass transition. The analyses of the apparent full width at half maximum of the main relaxations of the alkoxy alcohols reveal minima in the temperature dependence of the relaxation dispersions. The stretching exponents for the main relaxations of the alkoxy alcohols are also found not to follow the empirical correlations with other dynamic quantities established for generic liquids. A comparison of the relaxation dispersions in the alkoxy alcohols with those in Debye and non-Debye (generic) liquids is presented. The impacts of the β-relaxations on the apparent main relaxation widths are reviewed for molecular glass formers.
Supposing the existence of modified Chaplygin gas with the equation of state $p=A\rho-B/\rho^\beta$ as a cosmic background, we obtain a static spherically-symmetric black hole solution to the Einstein-Gauss-Bonnet gravitational equations in 5D spacetime. The spacetime structure of the obtained black hole solution is analyzed, also the related black hole properties are studied by calculating the thermodynamical quantities. During this process, effects of the Gauss-Bonnet coupling constant and the modified Chaplygin gas parameters on black hole solution, as well as on its thermodynamical properties are discussed. At the end, we study the quantum tunneling of scalar particles and the propagating of scalar waves within the background of modified Chaplygin gas. The study shows that the system is stable under scalar perturbations and the Hawking radiation could stop at some point, leaving an extremal black hole as remnant for evaporation.
Scrutinizing critical thermodynamic and kinetic factors for glass formation and the glass stability of materials would benefit the screening of the glass formers for the industry of glassy materials. The present work aims at elucidating the factors that contribute to the glass formation by investigating medium-sized molecules of pharmaceuticals. Glass transition related thermodynamics and kinetics are performed on the pharmaceuticals using calorimetric, dielectric, and viscosity measurements. The characteristic thermodynamic and kinetic parameters of glass transition are found to reproduce the relations established for small-molecule glass formers. The systematic comparison of the thermodynamic and kinetic contributions to glass formation reveals that the melting-point viscosity is the crucial quantity for the glass formation. Of more interest is the finding of a rough correlation between the melting-point viscosity and the entropy of fusion normalized by the number of beads of the pharmaceuticals, suggesting the thermodynamics can partly manifest its contribution to glass formation via kinetics.
Sugarcane is an important sugar and biofuel crop with high socio-economic importance, and its planted area has increased rapidly in recent years. China is the world’s third or fourth sugarcane producer. However, to our knowledge, no study has investigated the mapping of sugarcane cultivation areas across entire China. In this study, we developed a phenology-based method to identify sugarcane plantations in China at 30-m spatial resolution from 2016–2020 using the time-series of Landsat and Sentinel-1/2 images derived from Google Earth Engine (GEE) platform. The method worked by comparing the phenological similarity in normalized difference vegetation index (NDVI) series between unknown pixels and sugarcane samples. The phenological similarity was assessed using the time-weighted dynamic time warping method (TWDTW), which has less sensitivity to training samples than machine learning methods and therefore can be easily applied to large areas with limited samples. More importantly, our method introduced multiple and moving time standard phenological curves of sugarcane to the TWDTW by fully considering the variable crop life-cycle of sugarcane, particularly its long harvest season spanning from December to March of the following year. Validations showed the method performed well in 2019, with overall accuracies of 93.47% and 92.74% for surface reflectance (SR) and top of atmosphere reflectance (TOA) data, respectively. The sugarcane maps agreed well with the agricultural statistical areas from 2016–2020. The mapping accuracies using TOA data were comparable to SR data in 2019–2020, but outperformed SR data in 2016–2018 when SR data had lower availability on GEE. The sugarcane maps produced in this study can be used to monitor growing conditions and production of sugarcane and, therefore, can benefit sugarcane management, sustainable sugarcane production, and national food security.
Spacetime quantization predicts the existence of minimal length and time-interval. Within 5-dimensional Schwarzschild-like black string background, the tunneling of scalar particles, fermions and massive bosons are first studied together in the same generalized uncertainty principle framework. It is found that, the minimal length and time-interval effect weakens the original Hawking radiation. To $\mathcal{O}(\frac{1}{M_f^2})$, the corrected temperatures depend on not only the mass of black string, but also the mass and angular momentum of emitted particles. The temperature correction for massive bosons is four times as big as that for scalar particles and fermions. As a result, the bosons cease to tunnel from the black string before the scalar particles and fermions do. The evaporation remnant is expected in our analysis, however it should be verified by full quantum gravity theory.
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