Experimental and Simulation Research on Femtosecond Laser Induced Controllable Morphology of Monocrystalline SiC.

Silicon carbide (SiC) is utilized in the automotive, semiconductor, and aerospace industries because of its desirable characteristics. Nevertheless, the traditional machining method induces surface microcracks, low geometrical precision, and severe tool wear due to the intrinsic high brittleness and hardness of SiC. Femtosecond laser processing as a high-precision machining method offers a new approach to SiC processing. However, during the process of femtosecond laser ablation, temperature redistribution and changes in geometrical morphology features are caused by alterations in carrier density. Therefore, the current study presented a multi-physics model that took carrier density alterations into account to more accurately predict the geometrical morphology for femtosecond laser ablating SiC. The transient nonlinear evolutions of the optical and physical characteristics of SiC irradiated by femtosecond laser were analyzed and the influence of laser parameters on the ablation morphology was studied. The femtosecond laser ablation experiments were performed, and the ablated surfaces were subsequently analyzed. The experimental results demonstrate that the proposed model can effectively predict the geometrical morphology. The predicted error of the ablation diameter is within the range from 0.15% to 7.44%. The predicted error of the ablation depth is within the range from 1.72% to 6.94%. This work can offer a new way to control the desired geometrical morphology of SiC in the automotive, semiconductor, and aerospace industries.

A Review of Femtosecond Laser Processing of Silicon Carbide.

Silicon carbide (SiC) is a promising semiconductor material as well as a challenging material to machine, owing to its unique characteristics including high hardness, superior thermal conductivity, and chemical inertness. The ultrafast nature of femtosecond lasers enables precise and controlled material removal and modification, making them ideal for SiC processing. In this review, we aim to provide an overview of the process properties, progress, and applications by discussing the various methodologies involved in femtosecond laser processing of SiC. These methodologies encompass direct processing, composite processing, modification of the processing environment, beam shaping, etc. In addition, we have explored the myriad applications that arise from applying femtosecond laser processing to SiC. Furthermore, we highlight recent advancements, challenges, and future prospects in the field. This review provides as an important direction for exploring the progress of femtosecond laser micro/nano processing, in order to discuss the diversity of processes used for manufacturing SiC devices.

Economic Policy Uncertainty, Social Development, Political Regimes and Environmental Quality.

This paper aims to examine the influence of Economic Policy Uncertainty (EPU) on environmental performance, as well as the moderating effect of social development and the political regimes in EPU's influence on environmental performance. To investigate such essential issues, we conducted Generalized Method of Moments (GMM) estimations by utilizing cross-country data covering 137 countries during the period of 2001-2018, according to the Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) model. Our empirical estimations support that EPU negatively affects environmental performance; this idea was still supported when we conducted an empirical analysis by changing the measurements, employing alternative estimations and constructing new samples. Furthermore, not only would the absolute level of EPU bring worse environmental performance, but so would an increase in EPU. Moreover, higher economic performance, globalization and a high quality of governance can help countries to alleviate the adverse environmental effect of EPU. Additionally, EPU's negative effect on environmental performance is stronger in right-wing countries, autocracies and non-OECD countries, compared to their counterparts. Our study provides substantial policy implications for governments participating in the international treaties of environmental protection, to mitigate environmental degradation.

Does Overseas Investment Raise Corporate Environmental Protection? Evidence from Chinese A-List Companies.

This paper uses the relevant data of China's listed companies from 2010 to 2018 to test the impact of overseas investment on corporate environmental protection and further examines whether the heterogeneity of the company and the heterogeneity of the host country changes this effect. The research results show that the environmental protection of overseas investment companies is significantly higher than that of other companies. The impact of overseas investment on corporate environmental protection is dynamic, and it only helps improve corporate environmental protection after three years of investment. This article is conducive to causally identifying the logical relationship between overseas investment and corporate environmental protection. The policy significance is that the government can rationally guide companies to invest abroad, and oversea investment will help enhance corporate environmental protection.

Heterogeneous public preferences for controlling agricultural non-point source pollution based on a choice experiment.

The public's stated value and heterogeneous preferences are crucial for formulating policies and financing approaches to promote the control of agricultural non-point-source pollution (ANSP). This study aims to investigate urban residents' willingness to pay (WTP) for ANSP control and analyse the source of preference heterogeneity using a choice experiment method. Survey data were obtained from face-to-face interviews with 595 respondents in south Shaanxi Province, China. We found that respondents' average WTP for the attributes of ANSP control schemes were 2.34 yuan ($0.36) and 5.42 yuan ($0.83) per year per household for a 1% reduction in fertiliser and pesticide use, respectively. We also found significant impacts of WTP from individuals' socio-economic characteristics (i.e., gender, age, education, and income) and cognitive factors (i.e., policy understanding, and government trust). Thus, to improve the efficiency and universality of ANSP control policy, the public's willingness and preference heterogeneity should be thoroughly taken into policy formulation.

The Impact of Globalization on Forest Growth: Evidence from Multinational Panel Data.

Even though some existing literature has studied the impact of globalization on forest growth, this research remains inconclusive; moreover, little clarification has emerged as to whether the influence of globalization on forest growth is consistent among different countries. To fill this research gap, we investigated the impact of globalization on forest growth and considered what factors could change the influence of the former upon the latter. To empirically investigate these essential issues, we utilized cross-country data covering 108 countries during the period 1991-2018 to conduct a system generalized method of moment (GMM) estimation. The baseline results confirm the positive impact of globalization on forest growth, which is also supported by several robustness tests, such as changing the measurements and setting new samples. Furthermore, an increase in globalization would bring about higher forest growth. Aside from this, two specific dimensions of globalization, namely economics and trade, can also protect forest growth. Additionally, a higher FDI strengthens the positive impact of globalization on forest growth, while aging, industrial share, and CO2 emissions weaken it. Finally, the impact of globalization on forests is weaker in democracies, emerging markets, and countries with higher fiscal freedoms, while it is stronger in countries with higher political stability. Our study provides substantial policy implications for governments participating in international treaties related to forest growth. The structure of this paper is organized as follows.

Revisited Globalization's Impact on Total Environment: Evidence Based on Overall Environmental Performance Index.

This study aims to examine the impact of globalization on environmental performance by employing panel data for 148 countries from 2001 to 2018, via the indicator of Environmental Performance Index to capture the overall environmental quality and KOF index to measure the multi dimensions of globalization. The empirical results suggest that globalization is critical to environmental performance, which is reliable while we conduct several robustness tests. Furthermore, if globalization increases, it would be beneficial for the environmental performance; moreover, among specific dimensions of globalization, economic globalization, social globalization and political globalization would bring about better environmental performance. Besides, the improvement of globalization, social globalization and political globalization would bring about better environmental performance, while that of economic globalization cannot change the overall environmental performance. Our study offers more insight into the relationship between globalization and environmental performance.

Impact of Economic Policy Uncertainty on Carbon Emissions: Evidence from 137 Multinational Countries.

With growing economic policy uncertainty (EPU) and the importance of protecting the natural environment worldwide, the relationship between EPU and carbon emissions should be investigated further. However, conclusions in the existing literature on the relationship between EPU and carbon emission are inconclusive. This paper aims to examine the influence of EPU on carbon emissions according to the Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) model. To investigate such essential issues, we conduct GMM estimations by utilizing cross-country data covering 137 countries during the period 1970-2018, obtained from World Bank and OECD statistics. Our empirical estimations support that EPU would bring about more carbon emissions, while we conduct empirical analysis by changing the system of measurement, employing alternative estimation and constructing new samples. Our study provides substantial policy implications for government participation in international treaties on environmental protection to mitigate environmental degradation.