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This paper intends to explore the impact and mechanism of digital infrastructure development on enterprises vertical specialization. The following questions are discussed: (1) What is the impact of digital infrastructure on enterprise vertical specialization? (2) If the digital infrastructure serves to raise the level of vertical specialization of enterprises, does the impact differ depending on the level of city, industry and enterprise?

The research employs the “Broadband China” strategy as a quasi-natural experiment for digital infrastructure development, with a multi-period difference-in-difference model constructed to test the research hypothesis. The study examined data from Chinese A-share enterprises listed between 2007 and 2019.

The study’s findings indicate that the construction of digital infrastructure significantly increases firms' vertical specialization. According to the mechanism analysis, digital infrastructure can increase vertical specialization by lowering market transaction costs. This study employs group regressions in terms of cities, industries and companies to gain a better understanding of the heterogeneity of this effect. The results indicate that digital infrastructure contributes more significantly to higher levels of vertical specialization among enterprises in areas with higher levels of innovation and entrepreneurship as well as in eastern and central cities, service industries, and mature firms.

There are two shortcomings to this study that warrant investigating further. The first limitation is the mechanism. This study simply looked at the mechanism between variables in terms of transaction costs, using existing theories. As the level of technology continues to improve, the process of digital infrastructure’s impact on vertical specialization requires greater investigation. Another weakness of this study is its country-specific focus. The effect of digital infrastructure on vertical specialization differs by country, reflecting disparities in economic growth. Further discussion of cross-national comparative studies is required.

The study’s marginal contributions are largely represented in the two aspects listed below: (1) This paper includes a comprehensive theoretical study of the influence of digital infrastructure development on vertical specialization, focusing on transaction costs. This provides a theoretical foundation for the empirical study presented in this paper; (2) this study fills the gap in earlier research in this field, and the findings broaden research findings in areas such as digital infrastructure development and vertical specialization.

The purpose of this paper was to solve the shortage of carrying energy in probing robot and make full use of wind resources in the Antarctic expedition by designing a four-wheel land-yacht. Land-yacht is a new kind of mobile robot powered by the wind using a sail. The mathematical model and trajectory of the land-yacht are presented in this paper.

The mechanism analysis method and experimental modeling method are used to establish a dual-input and dual-output mathematical model for the motion of land-yacht. First, the land-yacht’s model structure is obtained by using mechanism analysis. Then, the models of steering gear, servomotors and force of wing sail are analyzed and validated. Finally, the motion of land-yacht is simulated according to the mathematical model.

The mathematical model is used to analyze linear motion and steering motion. Compared with the simulation results and the actual experimental tests, the feasibility and reliability of the proposed land-yacht modeling are verified. It can travel according to the given signal.

This land-yacht can be used in the Antarctic, outer planet or for harsh environment exploration.

A land-yacht is designed, and the contribution of this research is the development of a mathematical model for land-yacht robot. It provides a theoretical basis for analysis of the land-yacht’s motion.

The purpose of this paper is to investigate a cylindrical flow insert for a parabolic trough solar collector. Centrally placed and eccentric placed inserts are investigated in a systematic way to determine which configuration leads to the maximum thermal enhancement.

The analysis is performed in SolidWorks Flow Simulation with a validated computational fluid dynamics model. Moreover, the useful heat production and the pumping work demand increase are evaluated using the exergy and the overall efficiency criteria. The different scenarios are compared for inlet temperature of 600 K, flow rate of 100 L/min and Syltherm 800 as the working fluid. Moreover, the inlet temperature is examined from 450 to 650 K, and the diameter of the insert is investigated up to 50 mm.

According to the final results, the use of a cylindrical insert of 30 mm diameter is the most sustainable choice which leads to 0.56 per cent thermal efficiency enhancement. This insert was examined in various eccentric positions, and it is found that the optimum location is 10 mm over the initial position in the vertical direction. The thermal enhancement, in this case, is about 0.69 per cent. The pumping work demand was increased about three times with the insert of 30 mm, but the absolute values of this parameter are too low compared to the useful heat production. So, it is proved that the increase in the pumping work is not able to eliminate the useful heat production increase. Moreover, the thermal enhancement is found to be greater at higher temperature levels and can reach up to 1 per cent for an inlet temperature of r650 K.

The present work is a systematic investigation of the cylindrical flow insert in a parabolic trough collector. Different diameters of this insert, as well as different positions in two dimensions, are examined using a parametrization of angle-radius. To the authors’ knowledge, there is no other study in the literature that investigates the presented many cases systematically with the followed methodology on parabolic trough collectors. Moreover, the results of this work are evaluated with various criteria (thermal, exergy and overall efficiency), something which is not found in the literature.

The purpose of this paper is to reduce the crop losses at two ends and both sides of a plate in the rolling process, to produce a rectangular plan view pattern plate and to enhance the total product yield of the plates.

Based on sample data and the unchangeable principle of the slab volume in the rolling process, the predictive MAS control models were set‐up. They are width broad MAS predictive model, width broad MAS control model, gaugemeter automatic gauge control (GM‐AGC) model, and plates tracking model. After the models were tuned, the rolling test was implemented at LinFen Iron & Steel Co., Ltd.

It is found that by accurately predictive online modeling of MAS methods, the plan view pattern control can be applied in plate mills.

As the rolling process is in high temperature, the plan view pattern is difficult to be detected. Normally, the real‐time abnormity distortion cannot be obtained.

The test results showed that the crop losses are reduced and the product yield is greatly increased.

This paper presents an accurately predictive online modeling of MAS method.