📝 Publications

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Energy Economics

Environmental Quality
Toward enhancing environmental quality in OECD countries: Role of municipal waste, renewable energy, environmental innovation, and environmental policy
Mengying Su,   Zhongyu Yang*,   Shujaat Abbas,   Yuriy Bilan,   Agnieszka Majewska
The considerable increase in municipal waste has become a primary global concern due to the contamination of the environment through the emission of greenhouse gases. Therefore, many OECD countries have adopted municipal waste management practices. This study is a baseline attempt to explore the long-term effect of municipal waste management along with the energy transition, environmental innovation, and environmental policy stringency on GHG emissions in ten OECD countries from 1994 to 2020. This objective is realized by using non-parametric panel quantile regression. The estimated result reveals the asymmetric effect of selected explanatory variables on GHG emissions at various quantiles. The findings show that an increase in municipal waste can increase GHGs emissions at lower quantiles, while an insignificant effect is observed at higher quantiles. Similarly, energy transition, environmental innovation, and environmental policy stringency reveal asymmetric effects across the quantiles. The findings urge OECD countries to adopt more efficient municipal waste management practices and encourage renewable energy transition and environmental innovation. Environmental policy stringency can also be instrumental in enhancing environmental sustainability.
Green Effect
Green effect of energy transition policy: A quasi-natural Experiment Based on New Energy Demonstration Cities
Zhichao Yu,   Wenlan Xie,   Junjie Guo,   Zhongyu Yang*,  
In the context of China's rapid urbanization and pressing environmental challenges, this study evaluates the effectiveness of the New Energy Demonstration Cities initiative in fostering sustainable urban development. Employing a quasi-experimental design, the study specifically analyzed the impact of this initiative on urban green development, quantified through the metric of Green Total Factor Productivity (GTFP). Our findings reveal significant improvements in GTFP, indicating enhanced air pollution control and energy use efficiency through targeted government intervention and industrial upgrading, moderated by financial development. These results not only challenge the efficacy of broad, non-specific policies but also underscore the importance of precision in policy targeting. The study highlights how well-crafted, localized energy policies can drive substantial gains in sustainable urban growth, offering crucial insights for global policymakers and urban planners. This research extends the discourse on policy effectiveness in environmental management, suggesting pivotal areas for future investigation.

Computer Vision

ReChar
ReChar: Revitalising Characters with Structure-Preserved and User-Specified Aesthetic Enhancements
Zhongyu Yang,   Zuhao Yang,   Zhang Luo,   Yonghan Zhang,   Yang Xu,   Wei Pang,   Jingfen Lan,   Yingfang Yuan*
AI-Generated Content (AIGC) has recently surged in popularity, driven by its efficiency, consistent output quality, and versatile customization capabilities. While applications of image generation extend across numerous domains, research into stylized language writing system generation remains limited, particularly within the context of aesthetic enhancement. Inspired by the pictogram subset of Chinese characters, we propose ReChar, which aims to create visually appealing and culturally rich artworks that seamlessly integrate text-guided decorative elements and stylistic preferences within character structures. Additionally, we introduce ImageNet-ReChar, the first benchmark dataset designed to assess stylized character generation, with a focus on the generalization of user-defined elements. Our evaluation across multiple languages (Chinese, Japanese, English, and Latin) demonstrates ReChar’s ability to preserve original character structures while embedding decorative elements into the strokes and incorporating user-defined styles to achieve aesthetic enhancement. Our qualitative and quantitative analyses reveal that ReChar consistently outperforms existing methods.

Algebra and Representation Theory

Tropical Representations
Tropical Representations of Chinese Monoids with and without Involution
Zhongyu Yang,   Hao Wu

The Chinese monoid, denoted as \(Ch_{n}\), is a monoid generated by a totally ordered alphabet \(\mathcal{A}_{n} = \{a_{1} < a_{2} < \cdots < a_{n}\}\) with specific relations \(a_{r}a_{q}a_{p} = a_{r}a_{p}a_{q} = a_{q}a_{r}a_{p}\) for all \(p \leq q \leq r\). This monoid has been studied in the context of growth properties and tropical representations.

This work focuses on tropical representations of \(Ch_{n}\) with and without involution. For each finite \(n \geq 2\), a faithful tropical representation of \(Ch_{n}\) is constructed as a submonoid of the monoid \(UT_{n(n-1)}(\mathbb{T})\) of upper triangular matrices over \(\mathbb{T}\). This representation achieves a smaller dimension compared to previous constructions by Izhakian and Merlet for \(n \geq 4\).

Additionally, a tropical representation of the Chinese monoid with involution is explored. A faithful representation of \((Ch_{n}, \dagger)\) under Schützenberger's involution is provided for each finite \(n \geq 2\), realized as a submonoid of \((UT_{2n(n-1)}(\mathbb{T}),^{D})\), the monoid of upper triangular matrices over \(\mathbb{T}\) under skew transposition.