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This study purposes to study the influence of artificial freezing on the liquefaction characteristics of Nanjing sand, as well as its mechanism.

was studied through dynamic triaxial tests by means of the GDS dynamic triaxial system on Nanjing sand extensively discovered in the middle and lower reaches of the Yangtze River under seismic load and metro train vibration load, respectively, and potential hazards of the two loads to the freezing construction of Nanjing sand were also identified in the tests.

The results show that under both seismic load and metro train vibration load, freeze-thaw cycles will significantly reduce the stiffness and liquefaction resistance of Nanjing sand, especially in the first freeze-thaw cycle; the more freeze-thaw cycles, the worse structural behaviors of silty-fine sand, and the easier to liquefy; freeze-thaw cycles will increase the sensitivity of Nanjing sand's dynamic pore pressure to dynamic load response; the lower the freezing temperature and the effective confining pressure, the worse the liquefaction resistance of Nanjing sand after freeze-thaw cycles; compared to the metro train vibration load, the seismic load in Nanjing is potentially less dangerous to freezing construction of Nanjing sand.

The research results are helpful to the construction of the artificial ground freezing of the subway crossing passage in the lower reaches of the Yangtze River and to ensure the construction safety of the subway tunnel and its crossing passage.

This paper aims to investigate the influence of sinusoidal texture (ST) with different morphology parameters on the corresponding tribological effects.

The STs with different amplitudes, ranging from 0.05 to 0.3 mm, and frequencies, ranging from 5 to 17.5, are fabricated using nanosecond pulsed laser equipment. The friction experiments and the finite element analysis method are combined to investigate the tribological properties, under dry friction conditions.

Test results show that when the amplitude is 0.15 mm and frequency is 10, ST surface has the lowest friction coefficient of 0.373, and exhibits great anti-friction effect. It also possesses a complete texture edge after friction. The friction reduction effect of ST with larger or smaller amplitude and frequency is worse.

The results of this study can provide a guidance for the design optimization of ST of reciprocating sliding contact surfaces, under dry friction conditions.

This paper aims to report the influence of hexamethylenetetramine (HMTA) on phosphate coatings formed on AZ31 magnesium alloys.

These phosphate coatings were obtained by immersing magnesium alloys in phosphate baths with HMTA. The morphology and composition of the phosphate coatings were investigated via scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction.

The phosphate coatings were mainly composed of CaHPO₄·2H₂O. The HMTA concentration in the phosphate bath influenced the crystallization and corrosion resistance of the phosphate coating.

The polarization curve shows that the anti-corrosion qualities of the phosphate coating were optimal when the HMTA concentration was 1.0 g/L in the phosphate bath. Electrochemical impedance spectroscopy (EIS) shows that the electrochemical impedances increased gradually when the HMTA concentration varied from 1.0 to 3.0 g/L.

In order not to affect the highway and railway traffic under the bridge during the construction process, bridges adopting swivel construction method are increasingly used at areas where the traffic is heavy. Previous studies are mostly conducted by assuming that the bridge is under its own stability conditions, without considering the impact of construction error, changes of external condition and wind-induced vibration on the stability of the bridge, which poses serious challenges to the bridge construction process. This paper aims to analyze the extent to which static load and fluctuating wind effect influence structural stability and to test the credibility of the structure.

A finite element calculation method is used to analyze a T-shaped rigid frame swivel bridge. A full bridge model was built, and a local model of the turntable structure established; the two are then combined means of node coupling. Subsequently, the three sensitivity indexes – deflection rate, stress change rate and the change rate of spherical hinges – are used to evaluate in what way the bridge stability is influenced under various factors.

It is found that the stability of the swivel bridge is quite sensitive to unilateral overweight, steel beam tension and wind-induced vibration effects but less sensitive to the change of bulk density. Also found is that the change of elastic modulus exerts some effects on deflection but has negligible effects on other stability indexes. Furthermore, the transverse unbalanced torque on the bridge generated by wind-induced vibration is an important factor in determining the size of the turntable, indicating that it is not just controlled by the weight of the bridge.

All factors affecting the stability of swivel construction are analyzed, and solutions to reduce the influence are proposed. The influence of wind-induced vibration effects on swivel construction is analyzed for the first time. It is pointed out that wind-induced vibration effects have great influence on the structure, and its influence could not be neglected.

The purpose of this study is to investigate the impact of board secretaries’ characteristics on annual report readability using an original method that evaluates the readability of Chinese characters.

The authors manually collect board secretaries’ characteristics from the China Securities Market and Accounting Research database and obtain annual reports from the China Information website. Ordinary least square regression is applied to evaluate the impact, and then robustness tests and additional regression analyses are conducted.

Board secretaries’ legal-professional expertise, international expertise and role duality improve annual report readability. However, their political connections are negatively associated with it. The effect of expertise (role duality) is more pronounced for firms with lower ex ante litigation risk (board secretaries with equity holdings). Furthermore, higher readability increases the compensation of board secretaries, whereas lower readability increases their turnover. Finally, annual report readability is positively related to firm performance.

The authors only investigate listed firms in China from 2007 to 2017 because of the difficulties of obtaining data and text mining.

The authors provide managerial insights for regulators aiming to establish an effective governance mechanism with Chinese characteristics. First, certain requirements for board secretaries’ expertise can improve annual report readability. Further, firms can consider appointing board members or senior executives as board secretaries to enhance disclosure quality.

To the best of the authors’ knowledge, this study is the first to verify the effect of board secretaries’ characteristics on disclosure quality, especially annual report readability. Moreover, this study proposes a novel measure of annual report readability for Chinese texts.

In order to reduce the impact of bridge construction on traffic under the bridge, the construction of bridges for some important traffic nodes usually adopts the swivel construction method. The spherical hinge is a rotating mechanism located between the bottom of the pier and the bridge cap, and is subjected to tremendous vertical pressure. According to the mechanical characteristics of the spherical hinges, this paper applies the ultra-high performance concrete (UHPC) material to the spherical hinge. The spherical hinge is subjected to a compression test to test its mechanical behavior. This paper aims to discuss this issue.

In order to test the mechanical behavior of the UHPC spherical hinge, multiple sets of 100 mm UHPC spherical hinge specimens were prefabricated. Through the universal testing machine to measure the compressive strength of specimens, draw the force-displacement curve to analyze the failure mechanism and establish the stress calculation formula of the spherical hinge at each point along the radial direction.

Through the test, the compressive strength of UHPC spherical hinge is obtained, and the influencing factors of UHPC spherical hinge strength are found: reducing water–cement ratio, increasing steel fiber content and length and changing steel fiber arrangement direction can effectively improve the compression strength of UHPC spherical hinge.

For the first time, UHPC materials were applied to the spherical hinge structure, the UHPC spherical hinge diameter is 1/3 of the diameter of the reinforced concrete spherical hinge, which is equivalent to the diameter of the steel spherical hinge. By applying the UHPC spherical hinge, the manufacturing cost is reduced, the process is simple, and the construction difficulty is reduced.

Swivel construction is a new bridge construction method, which can minimize the impact on railway and highway traffic. Previous studies were based on single factor and static analysis, which cannot reflect the real state of structures. The purpose of this paper is to establish a dynamic model of the structure and to analyze the situation under multi-variable coupling effects to accurately simulate the real state of the structure.

Finite element software ANSYS was used to establish dynamic model of turntable structure and then to analyze the effects of multiple factors on total stress, friction stress and slipping distance of the turntable structure.

It is concluded that the unbalanced weight and radius of spherical hinges have great influence on the turntable structure, so the design should be strictly considered. Friction stress and angular acceleration have little effect on the turntable structure.

This paper provides simulation of the whole process of swivel construction method. Whereas previous studies focused on static analysis, this paper focuses on the dynamic analysis of swivel construction method. The mechanics of the swivel structure under multiple factors was analyzed. According to the analysis results, the design parameters of the turntable structure are optimized.

As a common form of failure in industry, corrosion causes huge economic losses. At present, with the development of computational techniques, artificial intelligence (AI) is playing a more and more important role in the field of scientific research. This paper aims to review the application of AI in corrosion protection research.

In this paper, the role of AI in corrosion protection is systematically described in terms of anticorrosion materials and methods, corrosion image recognition and corrosion life prediction.

With efficient and in-depth data processing methods, AI can rapidly advance the research process in terms of anticorrosion materials and methods, corrosion image recognition and corrosion life prediction and save on costs.

This paper summarizes the application of AI in corrosion protection research and provides the basis for corrosion engineers to quickly and comprehensively understand the role of AI and improve production processes.

Assembly errors of aeroengine rotor must be controlled to improve the aeroengine efficiency. However, current method cannot truly reflect assembly errors of the rotor in working state owing to difficulties in error analysis. Therefore, the purpose of this study is to establish an optimization method for aeroengine rotor stacking assembly.

The assembly structure of aeroengine rotor is featured. Rotor eccentricity is optimized based on Jacobian–Torsor model. Then, an optimization method for assembly work is proposed. The assembly process of the high-pressure compressor rotor and the high-pressure turbine rotor as the rotor core assembly is mainly considered.

An aeroengine rotor is assembled to verify the method. The results show that the predicted eccentricity differed from the measured eccentricity by 6.1%, with a comprehensive error of 8.1%. Thus, the optimization method has certain significance for rotor assembly error analysis and assembly process optimization.

In view of the error analysis in the stacking assembly of aeroengine rotor, an innovative optimization method is proposed. The method provides a novel approach for the aeroengine rotor assembly optimization and is applicable for the assembly of high-pressure compressor rotor and high-pressure turbine rotor as the rotor core assembly.

In the freeze-thaw zone, the pre-stressed concrete of bridge structure will be damaged by freezing-thawing, the bearing capacity of structure will decrease and the safety will be affected. The purpose of this paper is to establish the time-dependent resistance degradation model of structure in the freeze-thaw zone, and analysis the structural reliability and remaining service life in different freeze-thaw zones.

First, according to the theory of structural design, a calculation model of the resistance of pre-stressed concrete structures in f freeze-thaw zone is established. Second, the time-dependent resistance model was verified by the test beam bending failure test results done by the research group, which has been in service for 20 years in freeze-thaw zone. Third, using JC algorithm in MATLAB to calculate the index on the reliability of pre-stressed concrete structure in frozen thawed zones, forecasting the s remaining service life of structure.

First, the calculation model of the resistance of pre-stressed concrete structures in freeze-thaw zone is accurate and it has excellent applicability. Second, the structural resistance deterioration time in Wet-Warm-Frozen Zone is the earliest. Third, once the pre-stressed reinforcement rusts, the structural reliability index will reach limit value quickly. Finally, the remaining service life of structure meets the designed expectation value only in a few of freeze-thaw zones in China.

The research will provide a reference for the design on the durability of a pre-stressed concrete structure in the freeze-thaw zone. In order to verify the security of pre-stressed concrete structures in the freeze-thaw zone, engineers can use the model presented in this paper for durability checking, it has an important significance.