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3 results on '"Yayuan Lei"'

1. Dynamical analysis of a COVID-19 model with human-to-human and environment-to-human transmissions and distributed delays

Author

Jie Xu, Yayuan Lei, Tariq Abdullah, and Gang Huang

Subjects
Epidemic model, distributed delay, COVID-19, global stability, Applied mathematics. Quantitative methods, T57-57.97
Abstract

SARS-CoV-2 can survive in different environments and remain infectious for several days, which presents challenges to eliminating infectious diseases. It encourages researchers to study the effects of SARS CoV-2 on the environment. In this paper, we formulate an epidemic model for SARS-CoV-2, which focuses on the transmission of the virus under environmental conditions. Two distributed delays are introduced to describe the probability of the exposed and infected individuals in different infection periods based on the transmission of the virus in the environment. Th positivity and boundedness of solutions of model are derived. The basic reproduction number threshold theory is established and the results demonstrate that the persistence of COVID-19 depends on the basic reproduction number. Numerical simulations are presented to verify the theoretical results. Some measures are proposed to control and eliminate COVID-19 infectious diseases.

Published
2023
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2. DYNAMICAL ANALYSIS OF A COVID-19 MODEL WITH HUMAN-TO-HUMAN AND ENVIRONMENT-TO-HUMAN TRANSMISSIONS AND DISTRIBUTED DELAYS.

Author

JIE XU, YAYUAN LEI, ABDULLAH, TARIQ Q. S., and GANG HUANG

Subjects
COVID-19, INFECTIOUS disease transmission, HUMAN-to-human transmission, VIRAL transmission, COMPUTER simulation
Abstract

ARS-CoV-2 can survive in different environments and remain infectious for several days, which presents challenges to eliminating infectious diseases. It encourages researchers to study the effects of SARS-CoV-2 on the environment. In this paper, we formulate an epidemic model for SARS-CoV-2, which focuses on the transmission of the virus under environmental conditions. Two distributed delays are introduced to describe the probability of the exposed and infected individuals in different infection periods based on the transmission of the virus in the environment. The positivity and boundness of solutions of model are derived. The basic reproduction number threshold theory is established and the results demonstrate that the persistence of COVID-19 depends on the basic reproduction number. Numerical simulations are presented to verify the theoretical results. Some measures are proposed to control and eliminate COVID-19 infectious diseases. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Does Urban planning affect urban growth pattern? A case study of Shenzhen, China

Author

Nina Schwarz, Yayuan Lei, Johannes Flacke, Department of Urban and Regional Planning and Geo-Information Management, UT-I-ITC-PLUS, and Faculty of Geo-Information Science and Earth Observation

Subjects
Geography, Planning and Development, 0211 other engineering and technologies, UT-Hybrid-D, Urbanisation, 02 engineering and technology, 010501 environmental sciences, Management, Monitoring, Policy and Law, 01 natural sciences, ITC-HYBRID, Urban planning, Urbanization, China, Neighbourhood (mathematics), Environmental planning, 0105 earth and related environmental sciences, Nature and Landscape Conservation, Multinomial logistic regression, Driving factors, Shenzhen, 021107 urban & regional planning, Forestry, Urban growth pattern, Megacity, Geography, ITC-ISI-JOURNAL-ARTICLE, Management system
Abstract

It is essential to understand how urban plans affect urban growth patterns in order to improve current urban planning and management systems. Few studies have been conducted to analyse urban growth patterns of Shenzhen, an international megacity located in southern China, but none of them revealed the relationships between urban planning and urban growth patterns. This study explores the effects of urban master plans on urban growth patterns in different plan periods in Shenzhen. We first quantified the urban growth patterns comparing pixel- and patch-based methods. Three methods resulted in different quantities and spatial characteristics of urban growth. We then explored the relationships between urban growth patterns and urban planning in Shenzhen through multinomial logistic regression models. Across two planning periods, the master plans together with other socio-economic, physical, proximity, accessibility and neighbourhood factors shaped the urban growth patterns of Shenzhen. Out of the master plan elements, planned main roads in the Master Plan of Shenzhen 1996–2010 and the planned built-up zone in the Master Plan of Shenzhen 2010–2020 ha d stronger effects on urban growth patterns but contributed less than most other factors, e.g. distance to ocean. The importance of the other influence factors also varied over time. This changing effect suggests that we need to consider carefully whether driving factors might change in their importance over time when investigating future scenarios of urban land use change. Overall, this approach could also be applied to monitor progress in the paradigm shift towards an integrated urban-rural development in China.

Published
2021

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