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Unravel the spatio-temporal patterns and their nonlinear relationship with correlates of dockless shared bikes near metro stations

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Geo-Spatial Information Science 2023年第3期26卷 577-598页

作者： Zhaomin Tong Yi Zhu Ziyi Zhang Rui An yaolin Liu Meng Zheng School of Resource and Environmental Science Wuhan UniversityWuhanChina Natural Resources Investigation and Monitoring Section Chengdu Land Planning and Cadastral Affairs CenterChengduChina Faculty of Geomatics East China University of TechnologyNanchangChina Traffic Simulation Center Wuhan Transportation Development Strategy InstituteWuhanChina

The dockless bike-sharing system has rapidly expanded worldwide and has been widely used as an intermodal transport to connect with public ***,higher flexibility may cause an imbalance between supply and demand during daily operation,especially around the metro stations.A stable and efficient rebalancing model requires spatio-temporal usage patterns as fundamental ***,understanding the spatio-temporal patterns and correlates is important for optimizing and rescheduling bike-sharing *** study proposed a dynamic time warping distance-based two-dimensional clustering method to quantify spatio-temporal patterns of dockless shared bikes in Wuhan and further applied the multiclass explainable boosting machine to explore the main related factors of these *** results found six patterns on weekdays and four patterns on *** patterns show the imbalance of arrival and departure flow in the morning and evening peak hours,while these phenomena become less intensive on *** density,living service facility density and residential density are the top influencing factors on both weekdays and weekends,which means that the comprehensive impact of built-up environment attraction,facility suitability and riding demand leads to the different usage *** nonlinear influence universally exists,and the probability of a certain pattern varies in different value ranges of *** the densities of living facilities and roads are moderate and the relationship between job and housing is relatively balanced,it can effectively promote the balanced usage of dockless shared bikes while maintaining high riding *** spatio-temporal patterns can identify the associated problems such as imbalance or lack of users,which could be mitigated by corresponding *** relative importance and nonlinear effects help planners prioritize strategies and identify effective ranges on different patterns to promote the usage a

关键词： Dockless shared bikes spatio-temporal patterns machine learning transit oriented development

Numerical analysis of wave hazards in a harbor

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Science China Earth Sciences 2012年第9期55卷 1554-1564页

作者： JING HuiMin ZHANG Huai YUEN David A SHI yaolin College of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Key Laboratory of Computational Geodynamics Chinese Academy of SciencesBeijing 100049China Department of Geology and Geophysics University of MinnesotaTwin CitiesMN 55455-0219USA Minnesota Supercomputing Institute University of MinnesotaMinneapolisMN 55455USA

Resonance may occur when the periods of incoming waves are close to the eigen-periods of harbor *** amplified waves by resonance in harbor will induce serious wave hazards to harbor structures and vehicles in *** traditional theoretical approaches,the eigen-periods of harbor basin with regular shapes can be *** our study,we proposed a numerical model to simulate the behavior characteristics of the harbor waves.A finite difference numerical model based on the shallow water equations(SWE) is developed to simulate incoming tsunami and tidal *** analyzing the time series data of water surface wave amplitude variations at selected synthetic observation locations,we estimate the wave height and arrival time in coastal ***,we use frequency spectrum analysis to investigate the natural frequencies from the data recorded at the synthetic observation stations.

关键词： numerical simulation harbor wave hazard frequency spectrum analysis

Present-day Upper-crustal Strain Rate Field in Southeastern Tibet and its Geodynamic Implications:Constraints from GPS Measurements with ABIC Method

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 265-275页

作者： YANG Shaohua PAN Jiawei LI Haibing SHI yaolin Key Laboratory of Continental Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Hole Crustal Activity National Observation and Research Station DonghaiJiangsu 222300China Key Laboratory of Computational Geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

The Earth’s surface kinematics and deformation are fundamental to understanding crustal *** effective research approach is to estimate regional motion field and deformation fields based on modern geodetic *** the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical *** study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPS observations in the southeast Tibetan *** with results derived from other three methods revealed that our ABIC-derived strain rate fields were more *** maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed ***,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were *** northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational *** indicates compression in the former and extension in the *** with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of *** presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.

关键词： strain rate differential escape ABIC GPS southeastern Tibet

Effects of upper mantle wind on mantle plume morphology and hotspot track:Numerical modeling

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Science China Earth Sciences 2024年第12期67卷 3881-3899页

作者： Jie XIN Huai ZHANG yaolin SHI Felipe ORELLANA-ROVIROSA College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Ocean Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China Beijing Yanshan Earth Critical Zone National Research Station University of Chinese Academy of SciencesBeijing 101408China

A mantle thermal plume may be tilted,deflected,or even split-up by mantle lateral flows(mantle wind)during its ascent,which in turn changes the spatial distribution of various geological-magmatic responses,such as magmatic activity in the overriding plate and hotspot tracks on the surface,affecting the reliability of the constraints on absolute plate motion *** research on tilted mantle plumes has focused mainly on the lower/whole mantle *** mantle plumes formed in whole/layered mantle convection suffer lateral tilt in the upper mantle,and how this affects the magmatic activity along the surface hotspot track as well as the plume-related tectonic processes,are important scientific issues in mantle thermalplume dynamics and plate tectonics *** study introduces a thermal Stokes-fluid-dynamics numerical model(in ASPECT software)and pyrolite parameters constrained by mineral physics data,and quantitatively analyzes the tilted/deflected morphology of upper-mantle plumes and the concomitant surface-hotspot location-evolution characteristics under the combined effects of overriding-plate-motion driven flow(Couette)and upper mantle counter-flow(Poiseuille).We find that this composite upper-mantle wind can lead to(1)Plume head-and-upper-conduit horizontal motion in the opposite direction of the overriding plate motion and also with respect to the conduit roots,such that the magmatic spacing is increased;(2)Near-periodic split-up and ascent of a laterally-moving plume conduit,whose split-up/ascent period depends mainly on the thermo-chemical buoyancy of the plume itself;and(3)Under specific conditions of thermo-chemical buoyancy of a main“parent”plume interacting with upper mantle winds,two secondary“child”plumes hundreds of kilometers apart can sprout and ascend sequentially/subsimultaneously through the upper mantle in a very short period of time(2–4 Myr).The resulting oscillating/jumping behavior of hotspot locations along the overriding pl

关键词： Hotspot track Mantle plume Upper mantle wind Absolute plate motion Plume-derived magmatism Numerical modeling

A Framework of Massively Parallel Analysis of Regional Earthquake Activities

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Acta Geologica Sinica(English Edition) 2009年第4期83卷 786-800页

作者： ZHANG Huai SHI yaolin WU Zhongliang Graduate University of Chinese Academy of Sciences Beijing 100049 China Institute of Geophysics China Earthquake Administration Beijing 100080 China

Recent rapid progress in cyberinfrastructure in geosciences is providing seismologists an enormous boost for addressing multi-physical phenomena of regional seismic activities. The inherent nature of their multi-scale properties, from temporal to spatial spaces, makes it inevitably to be solved using large-scale computations and distributed parallel data processing schemes. Under such circumstance, using the advanced numerical algorithms and unstructured mesh generation technologies become the obstacles for modern seismologists. The main objective of this paper is to present a framework, which includes a parallel finite element simulation and distributed data infrastructure, to address the novel algorithms, state-of-the-art modeling and their implementation in regional seismicgenic systems. We also discuss and implement this framework to analyze the strong earthquake evolution processes in the Sichuan-Yunnan region. This study is the key to long-term seismic risk by estimates, providing a platform for predictive large-scale numerical simulation modeling of regional earthquake activities.

关键词： regional earthquake activities parallel numerical modeling initial stress field Sichuan- Yunnan area

Numerical simulation of tectonic stress and strain rate fields in the northeastern margin of the Tibetan Plateau in association with major fault zones

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Science China Earth Sciences 2023年第10期66卷 2353-2367页

作者： Shuhong ZHOU Huai ZHANG Yunqiang SUN Caibo HU yaolin SHI Key Laboratory of Computational Geodynamics University of Chinese Academy of SciencesBeijing100049China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519080China Beijing Yanshan Earth Critical Zone National Research Station University of Chinese Academy of SciencesBeijing101408China College of Transportation and Civil Engineering Fujian Agriculture and Forestry UniversityFuzhou350002China

A series of large strike-slip and thrust faults have developed in the northeastern margin of the Tibetan Plateau since the Late Cenozoic,with strong and active tectonic activity and frequent occurrences of large *** of regional tectonic stress distribution,strain fields,and seismic hazards has not been well *** study introduces a three-dimensional viscoelastic finite element numerical model to calculate crustal stress and strain rate fields under current tectonic *** preliminary results show that the direction of the horizontal principal compressive stress rate and compressive horizontal principal strain rate in the northeastern margin of the Tibetan Plateau rotate clockwise as a whole,and this rotation is more significant in the southeast direction because of the block of the Alxa and the Ordos *** NE-SW horizontal principal compressive stress rate and SE horizontal tensile stress rate dominate the entire study *** maximum value of the horizontal principal compressive strain rate at a depth of 0 km in the model is approximately 4×10^(-8)yr^(-1)near the East Kunlun fault and is smaller in the stable Alxa and Ordos blocks at approximately 1×10^(-8)yr^(-1).The calculated regional stress state is in good agreement with the actual focal mechanism solution,indicating that strike-slip and thrust stress fields dominate the northeastern margin of the Tibetan *** Altyn Tagh,East Kunlun,and Haiyuan faults demonstrate that the maximum shear strain rate gradually decreases eastward,and the decrease in the maximum shear strain rate value is absorbed by orogenic uplift and crustal shortening at its *** western section of the Altyn Tagh fault,west-to-middle sections of the East Kunlun fault,and west-to-middle sections of the Haiyuan fault will have high seismic hazards in the future.

关键词： Northeastern margin of the Tibetan Plateau Finite element model Stress and strain fields Seismic hazard

Land-surface temperature retrieval at high spatial and temporal resolutions based on multi-sensor fusion

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International Journal of Digital Earth 2013年第S01期6卷 113-133页

作者： Penghai Wu Huanfeng Shen Tinghua Ai yaolin Liu School of Resource and Environmental Science Wuhan UniversityWuhanChina

Land-surface temperature(LST)is of great significance for the estimation of radiation and energy budgets associated with land-surface ***,the available satellite LST products have either low spatial resolution or low temporal resolution,which constrains their potential *** paper proposes a spatiotemporal fusion method for retrieving LST at high spatial and temporal *** important characteristic of the proposed method is the consideration of the sensor observation differences between different land-cover *** other main contribution is that the spatial correlations between different pixels are effectively considered by the use of a variation-based *** method was tested and assessed quantitatively using the different sensors of Landsat TM/ETM,moderate resolution imaging spectroradiometer and the geostationary operational environmental satellite *** validation results indicate that the proposed multisensor fusion method is accurate to about 2.5 K.

关键词： land-surface temperature image fusion remote sensing resolution

Urban Sprawl and Related Problems: Bibliometric Analysis and Refined Analysis from 1991 to 2011

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Chinese Geographical Science 2014年第2期24卷 245-257页

作者： ZENG Chen LIU yaolin LIU Yanfang QIU Liquan School of Resource and Environment Science Wuhan University Key Laboratory of Geographical Information System Ministry of EducationWuhan University

To shed light on the general patterns and trends in urban sprawl research,and to provide reference for future study,bibliometric analysis and refined analysis are conducted for publications in this area from 1991 to *** general publication output,the global geographical distribution of the authors,the funding and institutions involved,the research areas,and the source titles are analyzed and *** in the United States and China have produced most of the documents in urban sprawl and these two countries are also the largest contributors in terms of funding and institutions.′Environmental Sciences&Ecology′,′Urban Studies′,and′Geography′are the most common research areas,and the journal titled Urban Studies has contributed the most ***,the refined analyses on the 500 top-cited and most relevant publications have revealed that research on urban sprawl is closely associated with the categories of′Urban form and development′,′Land use/land development′and′environment/ecology/biology′.Conclusions are made with respect to the basic paradigm of research on urban *** multi-disciplinary research into urban sprawl are expected to be more diversified and integrated.

关键词： urban sprawl bibliometrics scientific output multi-discipline

Spectral element analysis on the characteristics of seismic wave propagation triggered by Wenchuan M_s8.0 earthquake

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Science China Earth Sciences 2009年第6期52卷 764-773页

作者： YAN ZhenZhen ZHANG Huai YANG ChangChun SHI yaolin Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Laboratory of Computational Geodynamics Graduate University of Chinese Academy of SciencesBeijing 100049China

The 2008 Wenchuan earthquake occurred in an active earthquake zone, i.e., Longmenshan tectonic zone. Seismic waves triggered by this earthquake can be used to explore the characteristics of the fault rupture process and the hierarchical structure of the Earth's interior. We employ spectral element method incorporated with large-scale parallel computing technology, to investigate the characteristics of seismic wave propagation excited by Wenchuan earthquake. We calculate synthetic seismograms with one-point source model and three-point source model respectively. The AK135 model is employed as a prototype of our numerical global Earth model. The Earth's ellipticity, Earth’s medium attenuation, and topography data are taken into consideration. These wave propagation processes are simulated by solving three-dimensional elastic wave governing equations. Three-dimensional visualization of our numerical results displays the profile of the seismic wave propagation. The three-point source, which is proposed from the latest investigations through field observation and reverse estimation, can better demonstrate the spatial and temporal characteristics of the source rupture process than the one-point source. We take comparison of synthetic seismograms with observational data recorded at 16 observatory stations. Primary results show that the synthetic seismograms calculated from three-point source agree well with the observations. This can further reveal that the source rupture process of Wenchuan earthquake is a multi-rupture process, which is composed by at least three or more stages of rupture processes.

关键词： Wenchuan earthquake spectral element method numerical simulation global seismic wave parallel computing