Исследование этапов превращения кремния в карбид кремния в процессе атомного замещения методами полного внешнего отражения рентгеновских лучей и рентгеновской дифрактомерии

X-ray diffraction and total external reflection of X-rays (X-ray reflectometry) methods were used to study the successive stages of synthesis of epitaxial SiC films on Si (100) X-ray diffraction and total external X-ray reflection (XRD) methods were used to study successive stages of synthesis of epitaxial SiC films on Si (100) surfaces, (110) and (111) surfaces by the atom substitution method. The data on the transformation evolution of (100) surfaces were studied, (110) and (111) Si, into SiC surfaces. A comparative analysis of the X-ray structural quality of the SiC layers grown on Si by the atom substitution method with the quality of SiC layers grown by Advanced Epi by the standard CVD method. A modified technique for the total outer X-ray reflection method, based on measurements of the intensity of the reflected X-rays using a special parabolic mirror. It is shown that the method of total external reflection method makes it possible to obtain important information about the degree of surface roughness of SiC layers, the evolution of their crystal structure and plasmon energy in the process of Si to SiC conversion.

Research on the Effect of an Environmental Protection Tax Policy on Haze Control in China—Empirical Analysis Based on Provincial Panel Data

This paper describes the construction of a model to explore the effectiveness of environmental protection taxes on haze emission reduction in China. The model is based on panel data from 30 provinces and cities in China, from 2003–2019. It is found that the current environmental protection tax has a significant inhibitory effect on haze. In addition, an upfront pollutant discharge fee can guide enterprises to significantly reduce the emission of haze-causing pollutants. A robustness test is conducted, using the variable substitution method of taking sulfur dioxide (SO2) as haze, and the research conclusions are consistent. We then put forward three specific suggestions: (1) Expand the scope of the environmental protection tax, gradually increase the tax rate, or adopt an excessive progressive tax rate. For example, China could consider including mobile pollution sources into the scope of taxation. (2) Increase the supervision and collection of the environmental protection tax. (3) Strengthen the multiple linkages between regional taxation departments and environmental protection departments, in order to form a collaboration between the departments in an effort to control haze and promote the sustainable development of the Chinese economy and the environment.

Globally Optimizing QAOA Circuit Depth for Constrained Optimization Problems

We develop a global variable substitution method that reduces n-variable monomials in combinatorial optimization problems to equivalent instances with monomials in fewer variables. We apply this technique to 3-SAT and analyze the optimal quantum unitary circuit depth needed to solve the reduced problem using the quantum approximate optimization algorithm. For benchmark 3-SAT problems, we find that the upper bound of the unitary circuit depth is smaller when the problem is formulated as a product and uses the substitution method to decompose gates than when the problem is written in the linear formulation, which requires no decomposition.