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This paper investigates the impact of government subsidies on the firm-level markups and its mechanism of action by measuring the firm-level markups based on a micro dataset of Chinese manufacturing firms from 2000 to 2007. The findings suggest that government subsidies significantly reduce the markups of Chinese firms. Moreover, there is significant heterogeneity in the negative impact of government subsidies among different types of firms. Furthermore, analysis of the impact mechanism based on the mediation effect model shows that the increase in rent-seeking cost is an important way for government subsidies to reduce the firm-level markups. Finally, based on the dynamic decomposition of the aggregate markup of the Chinese manufacturing industry, it is found that government subsidies significantly reduce the industry-level aggregate markup through within-firm and cross-firm effects. This study enriches the literature on government subsidies and markups, and provides a new perspective for understanding the micro-performance of government subsidies.

Demographic factors are crucial to the sustainable development of one country. China’s population is aging at an accelerating rate and, together with the increasing mobility between cities, some special demographic issues have formed, which is quite related to the urban real estate market. The paper aims to investigate how the population aging and mobility affect housing prices at the city level, by using a set of two-period panel data of 294 prefecture-level cities in China. The results show that an increase in elderly dependency ratio by 1% leads to a rise in housing prices by 0.368%. Meanwhile, an increase in urbanization level by 1% drives up housing prices by about 0.139%, and a rise in the ratio of inter-regional migration by 1% will increase housing prices by about 1.038%. Furthermore, the policy of purchase limits could weaken the positive impacts of elderly dependency ratio and inter-regional migration on housing prices and, thus, plays a moderating role on the relationship between demographic structure and housing prices.

The development of Belt and Road has seen a boom of imported fresh agri-products in China. This stimulates the growth of refrigerated transport, which accounts for much more carbon emissions than traditional transport. Designing a sustainable cold chain network is of vital importance from both financial and environmental perspectives. In this research, a multi-objective linear programming model is proposed for green cold chain design for multiple imported fresh agri-products in China to balance between the two competing goals—the total cost and carbon emissions. The effect of the outdoor air temperature on the carbon emissions of transportation and maintaining distribution centers is considered. By applying the ε-constraint method, the multi-objective model is solved. Numerical examples derived from the scenario of imported fresh-agri products in China are conducted to shed light on green cold chain design under Belt and Road development.

Microplastics are persistent and complex contaminants and have been recognized as a global concern. Recently, increasing efforts have been devoted to studying the influence of microplastics on soils. However, the complexity of microplastics and the diversity of extraction methods result in a lack of systematic analysis and comprehensive review in this field. In this paper, we used CiteSpace software to summarize the development of this field. Then, we visualized and analyzed the knowledge structure, research hotspots, and trend directions of this field. We found that the number of publications escalated dramatically, and 281 institutions in 69 countries have published articles in this field. Among them, China was the most productive contributor. However, according to the scientific collaboration analysis, we found that more than 90% of the authors who contributed to the field had no close connection. In co-occurrence analysis for subject categories, we found that the research in this field covered environmental science, engineering, ecology, and agriculture. Additionally, the effect of soil microplastics on agriculture was the most important problem in scientific research. The keyword co-occurrence cluster analysis revealed a total of 6 clusters, including “Identification” (#0), “Microbial community” (#1), “Oxidative stress” (#2), “Adsorption” (#3), “Porous media” (#4), and “Abundance” (#5). We discussed several aspects in detail, including detection methods, characteristics, environmental effects, adsorption capacity, removal and degradation, and toxicity. According to these results, we summarized the current research hotspots and evaluated future research trends in soil microplastics. This study is the first to specifically visualize the research field, and these results provide a reference for future research in the field of soil microplastics.

Pump as turbine (PAT) is a factual alternative for electricity generation in rural and remote areas where insufficient or inconsistent water flows pose a threat to local energy demand satisfaction. Recent studies on PAT hydrodynamics have shown that its continuous operations lead to a progressive deterioration of inner surface smoothness, serving the source of near-wall turbulence build-up, which itself depends on the level of roughness. The associated boundary layer flow incites significant friction losses that eventually deteriorate the performance. In order to study the influence of wall roughness on PAT hydraulic performance under different working conditions, CFD simulation of the water flow through an axial-flow PAT has been performed with a RNG k-ε turbulence model. Study results have shown that wall roughness gradually decreases PAT’s head, efficiency, and shaft power. Nevertheless, the least wall roughness effect on PAT hydraulic performance was experienced under best efficiency point conditions. Wall roughness increase resulted in the decrease of axial velocity distribution uniformity and the increase of velocity-weighted average swirl angle. This led to a disorderly distribution of streamlines and backflow zones formation at the conduit outlet. Furthermore, the wall roughness impact on energy losses is due to the static pressure drop on the blade pressure surface and the increase of turbulent kinetic energy near the blade. Further studies on the roughness influence over wider range of PAT operating conditions are recommended, as they will lead to quicker equipment refurbishment.

Connected and Autonomous Vehicles are predicted to drive in a platoon with the aid of communication technologies to increase traffic flow efficiency while improving driving comfort, safety, fuel consumption, and exhaust emissions. However, some vehicles in a group may face communication failures. Such potential risks may even worsen the efficiency and safety of traffic flow and increase fuel consumption and exhaust emissions. Therefore, there is a need to propose an alternative scheme to control traffic flow effectively through vehicle-based information without the aid of communication technologies. In this paper, a deterministic acceleration model was developed considering the sensor’s detection range to capture the underlying process of a car following the dynamics of autonomous vehicles. A delayed-feedback control was proposed based on the current and previous states of throttle angle to increase traffic flow stability and improve fuel consumption and exhaust emissions without the aid of communication technologies. Numerical simulations were carried out to study the impact of sensor detection range on micro-driving behavior and explore the effect of the proposed delayed-feedback control on the fuel consumption and exhaust emissions of autonomous vehicles in large-scale traffic flow. The numerical results certified that using delayed feedback with proper gains and delay time improved the total fuel consumption and exhaust emissions of autonomous vehicles.

The lack of sufficient charging infrastructure for long-haul transportation is a significant barrier preventing the widespread adoption of electric vehicles (EVs). Planning EV charging facilities in this context requires considerations distinct from those in urban environments, accounting for factors such as traffic patterns and charging behaviors. This research paper presents a multi-agent simulation model designed to assess travel and charging activities, specifically on highways. By utilizing this model, the effectiveness of EV charging facility planning is evaluated. Empirical data from a real highway section in China are employed for analysis purposes. The findings reveal that the concentration of charging facilities significantly impacts both travel time and queue time for vehicles, demonstrating the potential for optimization through the proposed model. These established models hold practical value for both greenfield development and the expansion of existing charging networks, with the goal of minimizing total social costs.

Urban public services can significantly promote the improvement and capacity of urban innovation, yet there are differences. Although some studies have analyzed the impact of public services on technological innovation, few studies have taken Chinese cities at the prefecture level and above as samples to build an urban public service evaluation index system and focus on analyzing the differences and impact mechanisms. Based on panel data of 277 cities at the prefecture level and above from 2005 to 2019, this paper empirically studies the differences and mechanisms of the impact of urban public services on urban innovation. The results show that urban public services can significantly promote the improvement of urban innovation ability. After endogenous treatment and robustness testing, the empirical results remain robust. There are differences in the impact of urban public services on urban innovation: the positive effect of basic public services on urban innovation is greater than that livelihood public services. The innovation effect of public services in small and large cities is significant, but not in medium-sized cities. The effect of urban public services in eastern and central regions on improving innovation capability is higher than that in the western and northeastern regions. In cities with different levels of administration, the technological innovation effect of public services in key cities is not significant, while in generalized cities, it is significant. The study also found that public services can positively affect urban innovation through the talent agglomeration effect, industrial structure effect, and income scale effect.