Deep Neural Networks for Determining the Parameters of Buildings from Single-Shot Satellite Imagery

Journal of Computer and Systems Sciences International - The height of a building is a basic characteristic needed for analytical services. It can be used to evaluate the population and functional...     

Structural and optical characterization of CuInSe2 films deposited by hot wall vacuum evaporation method

Copper indium diselenide (CuInSe₂) compound was prepared by direct reaction of high-purity elemental copper, indium and selenium. CuInSe₂ thin films were deposited onto well-cleaned glass substrates by a hot wall deposition technique using quartz tubes of different lengths (0.05, 0.07, 0.09, 0.11 and 0.13 m). X-ray diffraction studies revealed that all the deposited films are polycrystalline in nature and exhibit chalcopyrite structure. The crystallites were found to have a preferred orientation along the (1 1 2) direction. Micro-structural parameters of the films such as grain size, dislocation density, tetragonal distortion and strain have been determined. The grain sizes in the films were in the range of 65-250 nm. As the tube length increases up to 0.11 m the grain size in the deposited films increases, but the strain decreases. The film deposited using the 0.13 m long tube has smaller grain size and more strain. CuInSe₂ thin films coated using a tube length of 0.11 m were found to be highly crystalline when compared to the films coated using other tube lengths; it has also been found that films possess the same composition (Cu/In=1.015) as that of the bulk. Scanning electron microscope analysis indicates that the films are polycrystalline in nature. Structural parameters of CuInSe₂ thin films deposited under higher substrate temperatures were also studied and the results are discussed. The optical absorption coefficient of CuInSe₂ thin films has been estimated as 10⁴ cm⁻¹ (around 1050 nm). The direct band gap of CuInSe₂ thin films was also determined to be between 1.018 and 0.998 eV.     

The energy structure of quantum dots induced in quantum wells by a nonuniform electric field

The study is focused on a theoretical treatment of electrons in quantum dots produced by a nonuniform electric field in a heterostructure with a single quantum well. A nonuniform electric field can be formed with the use of a mosaic electrode with a regular system of nanometer-sized apertures. A structure involving a one-aperture electrode deposited onto the surface is considered. The potential in the entire region between the electrode plates is calculated numerically. The analytical expression for the depth of the potential well is derived, and the potential profile in the vicinity of the bottom of the well is determined. The energy level structure in the vicinity of the bottom of the potential well is calculated. The geometric characteristics of the mosaic electrode most favorable for conservation of electron spin in the quantum dots of this type are determined. It is shown that in the quantum dots of this type the spin lifetime can be expected to lie within the microsecond region at a liquid-helium temperature.     

澳大利亚植物园中的城市生物多样性设计与保护策略

由于景观起源、物理环境条件和社会经济发展的差异,在南北半球,学术界对城市生物多样性及其与生态设计方法的相互作用有着不同的理解。数千年来,澳大利亚本土植物群落在这片大陆繁衍生息,形成了生物多样性极高的独特景观。植物园融合自然和人造元素,具有科研和保育功能,其设计与规划反映了科学知识随时间变化的动态特征,也为研究不同社会群体在过去如何利用和重视植物提供了的独特视角,植物园的生态设计方法反映了重视和保护生物多样性的新愿景。以澳大利亚为例,研究并回顾了植物园在保护生物多样性方面的益处,讨论了为展示生物多样性植物园设计重点的变化,分析了澳大利亚植物园的设计历史、澳大利亚本土生物多样性以及以生物多样性为重点的设计解决方案。为了解澳大利亚当地生物多样性和制定植物园示范保护与策略提供研究框架,为重新思考和加强植物园设计中的"生物多样性"提供新视角。     

Quantum Model of Hysteresis in a Single-Domain Magnetically Soft Ferromagnet

A quantum model of a magnetically soft ferromagnet constructed based on a single domain of an α-Fe crystal magnetized to saturation and placed in an alternating magnetic field is suggested. Based on the method of an effective Hamiltonian, the model takes into account the Zeeman energy, the spin-orbital interaction, and the interaction with the crystal field. In order to take into account the magnetic anisotropy, an expansion of a trial single-electron wave function into a series in terms of a small parameter of the spin-orbital interaction is suggested. The nonlinear equations of motion for the magnetization and orbital moment of the domain have been determined within the Heisenberg representation. The parameters of the nonlinear equations have been determined by comparing with the experimental data on the magnetic anisotropy of iron. The equations were solved numerically using the Runge–Kutta method with taking into account the magnetic friction introduced phenomenologically. The dependence of the magnetization of a single domain on the strength of the applied magnetic field has been characterized by hysteresis. The main parameters of the hysteresis loop are in quantitative agreement with the experimentally measured magnetic properties of nanoparticles of iron and iron oxide. A method of simulating the magnetization dynamics of a multidomain ferromagnet in the approximation of a strong crystal field has been suggested.