Construction of Hydrogen Safety Evaluation Model Based on Analytic Hierarchy Process (AHP)

With the large consumption of traditional primary energy, hydrogen as a clean and renewable energy has been widely studied by scholars around the world. Hydrogen is mainly used in hydrogen internal combustion engine and hydrogen fuel cell. Hydrogen internal combustion engine is the direct combustion of hydrogen as fuel, with the advantages of easy use. Alternatively, hydrogen fuel cell converts the chemical energy of hydrogen into electrical energy by electrochemical reaction, which has the advantages of high efficiency and zero pollution. Regardless of the use method, the safety of hydrogen use needs to be considered. However, in the whole life cycle of hydrogen, the process from hydrogen production to the use of hydrogen in automobiles is extremely complex. There are many factors affecting the safety of hydrogen use, and a single factor cannot be used as an evaluation. In order to make the evaluation of hydrogen safety more complete and accurate, the weight of four primary evaluation indexes and eight secondary evaluation indexes affecting hydrogen safety is determined by analytic hierarchy process, and a reliable hydrogen safety evaluation model is established.Citation: Xu, J., Wang, M., and Guo, P. (2022). Construction of Hydrogen Safety Evaluation Model Based on Analytic Hierarchy Process (AHP). Trends in Renewable Energy, 8(2), 84-95. DOI: http://dx.doi.org/10.17737/tre.2022.8.2.0014

Quantum Algorithm for Solving Quadratic Nonlinear System of Equations

High-dimensional nonlinear system of equations that appears in all kinds of fields is difficult to be solved on a classical computer, we present an efficient quantum algorithm for solving $n$-dimensional quadratic nonlinear system of equations. Our algorithm embeds the equations into a finite-dimensional system of linear equations with homotopy perturbation method and a linearization technique, then we solve the linear equations with quantum linear system solver and obtain a state which is $\epsilon$-close to the normalized exact solution of the original nonlinear equations with success probability $\Omega(1)$. The complexity of our algorithm is $O(\rm{poly}(\rm{log}(n/\epsilon)))$, which provides an exponential improvement over the optimal classical algorithm in dimension $n$.Comment: 9 pages; Modify the format error of tex source fil

Substrate screening approach for quasiparticle energies of two-dimensional interfaces with lattice mismatch

Two-dimensional (2D) materials are outstanding platforms for exotic physics and emerging applications by forming interfaces. In order to efficiently take into account the substrate screening in the quasiparticle energies of 2D materials, several theoretical methods have been proposed previously, but only applicable to interfaces of two systems' lattice constants with certain integer proportion. In this work, we analytically showed the equivalence and distinction among different approximate methods for substrate dielectric matrices. We evaluated the accuracy of these methods, by applying them to calculate quasi-particle energies of hexagonal boron nitride interface systems (heterojunctions and bilayers), and compared with explicit interface calculations. Most importantly, we developed an efficient and accurate interpolation technique for dielectric matrices that made quasiparticle energy calculations possible for arbitrarily mismatched interfaces, which is extremely important for practical applications.Comment: 9 pages, 7 figures, one tabl

Study of hydrogen internal combustion engine vehicles based on the whole life cycle evaluation method

In order to better achieve the goal of low carbon emissions from vehicles, a whole life cycle assessment of hydrogen-fueled internal combustion engine vehicles has been conducted in recent years. Based on the study of hydrogen use around the world, we studied the emission and economic performance of hydrogen-fueled internal combustion engine vehicles from the beginning of hydrogen production to the end of use (Well-to-Wheel, WTW) based on the whole life cycle evaluation method. The results show that the overall environmental impact of hydrogen production by steam reforming of natural gas is the smallest, and that the rational use of "abandoned electricity" for hydrogen production from electrolytic water in the western part of China significantly reduces the overall environmental impact and the cost of hydrogen production. In the use phase, the emissions are less, which not only can meet the National 6 emission standard, but also can reach higher emission standard after adding exhaust gas recirculation (EGR). From the whole life cycle point of view, hydrogen-fueled internal combustion engine has a very good development prospect.Citation: Guo, P., Xu, J., Zhao, C., and Zhang, B. (2022). Study of hydrogen internal combustion engine vehicles based on the whole life cycle evaluation method. Trends in Renewable Energy, 8, 27-37. DOI: 10.17737/tre.2022.8.1.0013

Dynamics in direct two-photon transition by frequency combs

Two-photon resonance transition technology has been proven to have a wide range of applications,it's limited by the available wavelength of commercial lasers.The application of optical comb technology with direct two-photon transition (DTPT) will not be restricted by cw lasers.This article will further theoretically analyze the dynamics effects of the DTPT process driven by optical frequency combs. In a three-level atomic system, the population of particles and the amount of momentum transfer on atoms are increased compared to that of the DTPT-free process. The 17% of population increasement in 6-level system of cesium atoms has verified that DTPT process has a robust enhancement on the effect of momentum transfer. It can be used to excite the DTPTs of rubidium and cesium simultaneously with the same mode-locked laser. And this technology has potential applications in cooling different atoms to obtain polar cold molecules, as well as high-precision spectroscopy measurement.Comment: 7 pages, 7 figure