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As a public compulsory course for Non-English majors in colleges and universities, College Public English should not only develop students' language and cross-cultural communication skills, but also cultivate their correct outlook on life, values, world and native land emotion, which is consistent with the ideological-political goals of the course. English textbook is the guarantee for the smooth progress of English teaching, and more importantly, it is an important carrier to practice Chinese teaching ideas. This paper mainly focuses on how to integrate ideological-political elements into English teaching from textbook perspective. It discusses the measures of integrating ideological-political education into College English courses from four aspects: teaching objectives, unit themes, and knowledge points, grammatical structure and word explanation. It is finally pointed out that exploring and integrating ideological-political elements in textbooks is the key link to realize ideological-political education in College Public English courses.

Since the 21st century, the cultivation and improvement of college students' English autonomous learning ability have become an important symbol of deepening the reform of College English teaching. The reform of teaching model is the critical to it. With the help of the self-constructed flipped classroom teaching model, this paper designs the corresponding teaching process, aiming at investigating the three dimensions of self-management learning ability, self-learning psychology and self-learning behavior of non-English majors. After the investigation and experiment on the control class and the experimental class for the whole semester, the experimental results show that the self-regulated learning model of College English based on the flipped classroom can greatly improve the comprehensive English level of College students, and the flipped classroom teaching model of College English can effectively improve the students' self-management learning ability, stimulate students 'motivation of autonomous learning and activate students' autonomous learning behavior. Thus, it opens up a new path for the cultivation of College Students 'autonomous learning ability.

In this paper， based on the on-site testing of cathodic protection corrosion coupons buried in 6 cities in China， combined with some indoor corrosion simulation test results， the safety boundary of cathodic protection for buried pipelines under AC interference was preliminarily established through the analysis of the correlation between cathodic protection and interference parameters of the test coupons and corrosion rates.Results showed that corrosion rate of the test coupons under AC interference decreased with the increase of the test coupons area.The AC corrosion safety boundary based on polarization potential was established: control the polarization potential to be in the range of－0.85～－1.20 V(vs CSE) and the AC current density to be less than 30.0 A/m2， or control the polarization potential to be in the range of－0.95～－1.10 V(vs CSE) and the AC current density to be less than 100.0 A/m2.The AC corrosion safety boundary based on DC current density was established: control the DC current density to be in the range of 0.15～20.00 A/m2 and the AC current density to be less than 30.0 A/m2， or control the DC current density to be in the range of 0.15～1.08 A/m2 and the AC current density to be less than 100.0 A/m2.The AC corrosion safety boundary based on pH was established: control the pH to be in the range of 10.0 ～14.0 and AC current density to be less than 30.0 A/m2 or control the pH to be in the range of 11.3～12.5 and AC current density to be less than 100.0 A/m2.

Currently，few studies have been conducted on the AC corrosion behavior of pipeline steel and sacrificial anodes in the marine environment.In order to provide a reference for evaluating the AC corrosion risk of submarine pipeline and the consumption performance of sacrificial anodes under AC interference，the AC corrosion simulation test was employed to study the AC corrosion behavior of X65 pipeline steel，aluminum alloy and zinc alloy sacrificial anodes under different AC current densities in simulated seawater environment.Results showed that the potential of X65 pipeline steel，aluminum alloy sacrificial anode and zinc alloy sacrificial anode samples were negatively shifted after AC interference was applied，and the greater the AC current density，the greater the offset.The corrosion rates of three materials increased with the increase of AC current density，but the corrosion rate of aluminum alloy was much higher than that of zinc alloy and X65 pipeline steel.Moreover，X65 pipeline steel exhibited uniform corrosion under 0～30 A/m2 AC interference，and when the AC current density increased to 100 A/m2，pitting pits appeared on the surface.Aluminum alloy exhibited pitting corrosion on the surface under different AC current densities，while zinc alloy was mainly uniform corrosion.In the marine environment，the service performance of zinc alloy was superior to that of aluminum alloy.

DC stray currents cause great interference to buried metal pipelines.This paper analyzed the corrosion laws of DC stray current on metal materials from the perspectives of the type of DC stray current and the magnitude of the interference current，including the electrochemical behavior and corrosion effects.Additionally，the interference effects of DC stray currents on buried pipelines were investigated from the aspects of metal corrosion and cathodic interference，which were further summarized according to the types of interference sources (HVDC grounding electrode，cathodic protection anode bed and subway).Finally，the deficiencies in the research of the corrosion law of buried pipelines under direct current interference were discussed，and the future research direction was prospected.

Flipped classroom is now one of the most highly valued models in universities. From domestic and foreign research, flipped classroom can provide language input for students' autonomous learning via modern information technology, which creates more opportunities for classroom output activities and eventually can effectively improve the teaching effect of College English. This paper analyzes the concept of flipped classroom, summarizes the advantages and disadvantages of flipped classroom teaching model in College English teaching from the existing problems in English teaching, and focuses on the innovative exploration of flipped classroom for college English teaching ideas based on the characteristics and theoretical basis of flipped classroom teaching model. This paper is expected to provide implications for the implementation of the flipped classroom teaching model in College English teaching in China, so as to promote the reform of College English teaching, perfect the flipped classroom teaching model to adapt to the form of College English teaching in China, and lay the foundation for implementation of flipped classroom on a large scale.

In view of the issue that surface catalysis has a significant influence on aerodynamic heating of hypersonic vehicle heatshield and is difficult to accurately predict, a four-step surface heterogeneous catalytic model including physisorption, chemisorption, Eley-Rideal (ER) recombination, and Langmuir-Hinshelwood (LH) recombination was established by combining theoretical analysis and numerical simulation. Based on the model, the nonequilibrium flow and the aerodynamic heat around a two-dimensional cylinder were simulated. The influence of the fraction of occupied physisorption and chemisorption sites on the catalysis rate and the aerodynamic heat was analyzed. The results show that the established model can improve the prediction accuracy of the aerodynamic heat. The surface adsorption has a nonlinear influence on the aerodynamic heat due to the competing and promoting between different reaction pathways. Based on the real physicochemical process, the model can reflect the catalytic properties of different materials and further provides theoretical support for the lightweight and low redundancy design of the thermal protection system.

ABSTRACT Evaluating the cathodic protection (CP) effectiveness of horizontal directional drilling (HDD) pipe is a significant technical challenge, due to the feasibility of testing only in shallow buried areas at entry/exit extremities, and not in deeply buried areas or the crossing section of the pipe. Numerical simulation provides a method to evaluate the CP effectiveness of HDD pipes. To improve the accuracy of potential distribution along the HDD pipe, it is necessary to adopt appropriate boundary conditions of the HDD pipe and accurate holiday models of coating. A specialized deep well polarization test device was designed and employed in the field to obtain the actual polarization characteristics as the boundary condition of the HDD pipe at buried depths ranging from 2 to 25 m. The result revealed that the polarization characteristics of HDD pipe in various depths were different and the potential distribution of the actual situation was greatly different from the potential distribution of the shallow aerobic soil. The potential distribution along the HDD pipe was analyzed in two types of holiday models. The results could be used as a reference for the CP effectiveness evaluation of HDD pipes. [ABSTRACT FROM AUTHOR]

ABSTRACT Unlike the stable AC interference caused by AC transmission lines to buried pipelines, high‐speed railways cause dynamic AC interference to nearby buried pipelines. The dynamic fluctuation characteristics of AC interference parameters of buried pipelines near high‐speed railways with different traction power supply modes were obtained through the statistical analysis of field test data. The dynamic AC corrosion simulation experiments were conducted with different interference cycles and levels, as well as cathodic protection (CP) levels. The results show that the dynamic AC corrosion rate increases with the extension of the interference time within each interference cycle. After the JAC ≥ 100 A/m2, the dynamic AC corrosion rate shows a three‐stage change with a negative shift of CP potential, that is, first decreasing, then increasing, and then decreasing again. On the basis of the experimental results, the dynamic AC corrosion risk assessment criteria were proposed, which comprehensively considers the CP level and the proportion of interference time with different AC current densities. [ABSTRACT FROM AUTHOR]