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Intelligent Identification of Building Patches and Assessment of Roof Greening Suitability in High-density Urban Areas:A Case Study of Chengdu

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Journal of Resources and Ecology 2022年第2期13卷 247-256页

作者： LUO Luhua CHEN Mingjie DONG Lulu SU Wei LI Xin HU Xiaodong ZHANG Xin LI Chen CHENG Weiming SHI Hanning LUO Jiancheng Faculty of Geomatics Lanzhou Jiaotong UniversityLanzhou 730070China National-Local Joint Engineering Research Center of Technological and Application for National Geographic State Monitoring Lanzhou 730070China Gansu Provincial Engineering Laboratory for National Geographic State Monitoring Lanzhou 730070China College of Geoscience and Surveying Engineering China University of Mining&Technology(Bejing)Beijing 100083China School of Earth Science and Engineering Hebei University of EngineeringHebei 056000China Tianjin University Urban Planning and Design Institute Co.Ltd Tianjin 300072China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China The ImageSky International Co.Ltd SuzhouJiangsu 215000China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100101China School of Architecture Tianjin UniversityTianjin 300072China

With the expansion of a city,the urban green space is occupied and the urban heat island effect is *** the roof surfaces of urban buildings is an effective way to increase the area of urban green space and improve the urban ecological *** provide effective data support for urban green space planning,this paper used high-resolution images to(1)obtain accurate building spots on the map of the study area through deep learning assisted manual correction;and(2)establish an evaluation index system of roof greening including the characteristics of the roof itself,the natural environment and the human society *** weight values of attributes not related to the roof itself were calculated by Analytic Hierarchy Process(AHP).The suitable green roof locations were evaluated by spatial join,weighted superposition and other spatial analysis *** the areas within the Chengdu city’s third ring road as the study area,the results show that an accurate building pattern obtained by deep learning greatly improves the efficiency of the *** roof surfaces unsuitable for greening can be effectively classified by the method of feature extraction,with an accuracy of 86.58%.The roofs suitable for greening account for 48.08%,among which,the high-suitability roofs,medium-suitability roofs and low-suitability roofs represent 45.32%,38.95%and 15.73%.The high-suitability green buildings are mainly distributed in the first ring district and the western area outside the first ring district in *** paper is useful for solving the current problem of the more saturated high-density urban area and allowing the expansion of the urban ecological environment.

关键词： deep learning roof greening suitability assessment spatial join weighted overlay

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A guideline study for optimal machine learning approaches to predict the off-design performance of sCO 2 -PCHEs

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Case Studies in Thermal Engineering 2025年 73卷

作者： Xin Sui Wenqi Wang Chunyang Liu Peixin Dong School of Mechatronic Engineering Henan University of Science and Technology Luoyang 471003 China Henan Key Laboratory for Machinery Design and Transmission System of Henan Province Luoyang 471003 China Longmen Laboratory Luoyang 471000 China Department of Mechanical Engineering The Hong Kong Polytechnic University Hong Kong Special Administrative Region

As research increasingly focuses on predicting the off-design performance of PCHEs using machine learning (ML) approaches, there is a clear need to identify the most cost-effective method that offers optimal accuracy and generalization across a wide range of operating conditions in sCO 2 power cycles. In response, this study establishes highly accurate machine learning proxies, including XGBoost, SVMs, BPNNs, and FCDNs for comparison, aiming to rank and identify the one with the best accuracy and generalization for different operating conditions of PCHEs. First, multiple datasets concerning the geometric parameters and working conditions of PCHEs are consolidated. Two data-driven techniques are introduced to correlate both inputs and outputs, identifying the most pertinent parameter. Then, the sensitivity of ML models to hyperparameter, split ratio, and data distribution is evaluated. Finally, a mutual assessment is conducted to rank their accuracy and generalization when predicting the heat transfer coefficient across three real-world operating scenarios. This study concludes that: 1) BPNN and XGBoost emerge as the best performers with the highest accuracy, achieving a MAPE of 2.938 % and 3.074 %, respectively, among eleven approaches with four ML models and seven Nu correlation-based models included; 2) BPNN and XGBoost exhibit strong generalization ability, demonstrating accuracy losses of less than 0.057 and 0.244, respectively, against unseen data; 3) unlike FCDN, which requires substantial computational time, or SVM, which produces significant errors, BPNN and XGBoost are more reliable and efficient in forecasting sCO 2 -PCHEs’ performance for future power cycle control studies that involve vast operating conditions and numerous rounds of optimization search.

关键词： Machine learning sCO 2 -PCHEs Hyperparameter optimization Generalization ability Off-design performance

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Statistics of velocity gradient and vortex sheet structures in polymeric turbulent von Kármán swirling flow

arXiv

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arXiv 2025年

作者： Wang, Feng Zhang, Yi-Bao Yang, Ping-Fan Xi, Heng-Dong Institute of Extreme Mechanics School of Aeronautics National Key Laboratory of Aircraft Configuration Design Key Laboratory for Extreme Mechanics of Aircraft of Ministry of Industry and Information Technology Northwestern Polytechnical University Shaanxi Xi’an710072 China New Cornerstone Science Laboratory Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing100084 China

Investigations into the effects of polymers on small-scale statistics and flow patterns were conducted in a turbulent von Kármán swirling (VKS) flow. We employed the tomographic particle image velocimetry (Tomo-PIV) technique to obtain full information on three-dimensional velocity data, allowing us to effectively resolve dissipation scales. Under varying Reynolds numbers (Rλ = 168-235) and polymer concentrations ( = 0-25 ppm), we measured the velocity gradient tensor (VGT) and related quantities. Our findings reveal that the ensemble average and probability density function (PDF) of VGT invariants, which represent turbulent dissipation and enstrophy along with their generation terms, are suppressed as polymer concentration increases. Notably, the joint PDFs of the invariants of VGT, which characterize local flow patterns, exhibited significant changes. Specifically, the third-order invariants, especially the local vortex stretching, are greatly suppressed, and strong events of dissipation and enstrophy coexist in space. The local flow pattern tends to be two-dimensional, where the eigenvalues of the rate-of-strain tensor satisfy a ratio 1: 0: −1, and the vorticity aligns with the intermediate eigenvector of the rate-of-strain tensor while is perpendicular to the other two. We find that these statistics observations can be well described by the vortex sheet model. Moreover, we find that these vortex sheet structures align with the symmetry axis of the VKS system and orient randomly in the horizontal plane. Further investigation, including flow visualization and conditional statistics on vorticity, confirms the presence of vortex sheet structures in turbulent flows with polymer additions. Our results establish a link between single-point statistics and small-scale flow topology, shedding light on the previously overlooked small-scale structures in polymeric turbulence. Copyright © 2025, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

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α [email protected] carrier modulated platinum single atoms for high-efficient solar cells

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Applied Surface science 2023年 611卷

作者： Jixin Yao Jie Wang Wen Wang Ying Meng Haibo Wang Shibin Lu Feng Du Li Yang Xueqin Zuo Guang Li Anhui Province Key Laboratory of simulation and design for Electronic information system Universities Joint Key Laboratory of photoelectric detection Science and Technology in Anhui Province Hefei Normal University Hefei 230601 China School of Materials Science and Engineering Anhui Key Laboratory of Information Materials and Devices Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Institute of Physical Science and Information Technology Anhui University Hefei 230601 China Institute of Materials Science and Devices School of Materials Science and Engineering Suzhou University of Science and Technology Suzhou 215011 China

Single-atom electrocatalysts have been proven to be the great promising catalysts for energy-related fields yet their active site structure remains elusive, especially in dye-sensitized solar cell (DSSC). Herein, atomically dispersed Pt is anchored into α [email protected] carrier (Pt/α [email protected] ), which vigorously stimulates the activity of Pt single atoms under the strong metal interaction. As expected, the Pt/α [email protected] as the cathode in DSSC exhibits high power conversion efficiency (PCE) of 9.67%, exceeding Pt electrode (7.61%). X-ray photoelectron spectroscopy combined with density functional theory calculations reveals that the high activity is mainly derived from charge re-distribution of Pt/α [email protected] caused by the interaction between Pt atoms and α-MoC. This interaction not only achieves the optimized adsorption/desorption energy of reactants but also brings synergic advantages to expedite the reaction kinetics of the overall system. This work paves further research prospects for charge re-distribution, stimulating electrocatalysts to effectively enhance their catalytic properties by an atomic-level engineering strategy.

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An iterative method for the solution of equilibrium position in the shaft-hole assembly based on spring contact model

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Procedia CIRP 2021年 97卷 230-234页

作者： Yuanyang Zhang Junkang Guo Xianming Gao Jun Hong School of Mechanical Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 P R China Key Laboratory for Modern Design & Rotor-Bearing System Ministry of Education Xi'an Jiaotong University Xi'an Shaanxi 710049 P R China College of Mechanical and Electrical Engineering Shaanxi University of Science and Technology Xi'an 710021 China

The traditional finite element method has the advantages of strong versatility and high calculation accuracy. Thus it is widely applied in various numerical simulation problems. Although the traditional finite element method for solving the shaft-hole assembly problem can obtain better solution accuracy, the process of modeling and calculation take a long time and thus cannot meet the engineering application requirements when the equilibrium position after the assembly needs to be obtained quickly to guide the subsequent process. In this paper, an iterative method based on the spring contact model is proposed. Firstly, the actual form error of the shaft and hole is characterized by the Fourier series expansion method; Then, in the contact surface, we established a discrete spring contact model and obtained the equivalent stiffness of the coupling spring through the discrete solid model. The balance iterative calculation based on the form errors and contact deformation force can finally determine the equilibrium position after the assembly. Compared with the calculation results of the finite element model, the equilibrium position of the shaft-hole assembly can be quickly solved under the condition of sacrificing certain precision. From this aspect it can be estimated that this method has a good potential for engineering application.

关键词： Assembly design Form error Spring contact model Finite element method

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Impacts of Soil Clay Contents on Plant Growth, Physiology, and Phosphorus Uptake of Rice Under Various Irrigation Regimes

SSRN

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SSRN 2024年

作者： Hamoud, Yousef Alhaj Shaghaleh, Hiba Zhang, Ke Okla, Mohammad K. Alaraidh, Ibrahim A. Sheteiwy, Mohamed S. AbdElgawad, Hamada The National Key Laboratory of Water Disaster Prevention Hohai University Nanjing210098 China College of Hydrology and Water Resources Hohai University Nanjing210098 China College of Environment Hohai University Nanjing210098 China Yangtze Institute for Conservation and Development Hohai University Jiangsu Nanjing210024 China China Meteorological Administration Hydro-Meteorology Key Laboratory Hohai University Jiangsu Nanjing210024 China Key Laboratory of Water Big Data Technology of Ministry of Water Resources Hohai University Nanjing210024 China Key Laboratory of Hydrologic-Cycle and Hydrodynamic-System of Ministry of Water Resources Hohai University Nanjing210024 China Botany and Microbiology Department College of Science King Saud University P.O. Box 2455 Riyadh11451 Saudi Arabia Department of Integrative Agriculture College of Agriculture and Veterinary Medicine United Arab Emirates University P.O. Box 15551 Al Ain Abu Dhabi United Arab Emirates Department of Agronomy Faculty of Agriculture Mansoura University Mansoura35516 Egypt Integrated Molecular Plant Physiology Research Department of Biology University of Antwerp Antwerp2020 Belgium

Rice is threatened by ineffective inputs of water and fertilizers. Therefore, we detected the impact soil clay content and water regime on the plant physiological attributes and their relations to the phosphorus utilization efficiency of rice under various irrigation methods. Therefore, this trail was carried out in a completely randomized block design. The main factor was the irrigation method using three watering options: alternate wetting and critical drying (AWCD), alternate wetting and modest drying (AWSD), and alternative wetting and minor drying (AWMD). The sub-factor was soil clay level, with three contents at 65, 50, and 30%, which were called SHC, SMC, and SLC, respectively. The active absorption area and peroxidase activity of roots were lower in AWCD × SLC than in AWMD × SHC. While the former treatment decreased the P level in the soil, the latter increased their accessibility. The glutamine synthetase (492.5 µmol g-1h-1) was lower in AWCD × SLC than in in AWMD × SHC at 1006.1 µmol g-1h-1, leading to the increase of oxidative cell damage. The optimal P nutrition improved the plant cell ultrastructure under AWMD × SHC. The AWCD × SLC led to the minimum agronomic efficiency of P (PAE, 13.67 g/g), and the apparent recovery efficiency of P (PARE, 1.55%). However, the maximum values of PAE (44.05 g/g), and PARE (21.45%) were detected in AWMD × SHC. This study advocates that AWMD × SHC could stimulate plant physiological traits, warranting optimal P acquisition and utilization of rice grown in high clay soil. © 2024, The Authors. All rights reserved.

关键词： Drying

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Formal verification of 5G-EAP-TLS authentication protocol 4

Formal verification of 5G-EAP-TLS authentication protocol

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4th IEEE International Conference on Data science in Cyberspace, DSC 2019

作者： Zhang, Jingjing Wang, Qiang Yang, Lin Feng, Tao Army Engineering University of PLA Nanjing China National Key Laboratory of Science and Technology on Information System Security Beijing China

ISBN: (纸本)9781728145280

In mobile communication networks, the security of users' data depends on the guarantees provided by the authentication protocols. For the next generation of mobile network (i.e., 5G network), the 5G-EAP-TLS protocol has been proposed for this purpose. However, it is still unknown whether this protocol provides the claimed security guarantees or not. To fill this gap, we provide in this work the first formal model of 5G-EAP-TLS protocol and conduct a thorough analysis based on Scyther model checker. Secondly, we identify several design flaws in the protocol, which may jeopardize the security goals and result in severe security vulnerabilities when implemented in real systems. To our knowledge, this is the first study on the formal verification of 5G-EAP-TLS protocol. © 2019 IEEE.

关键词： Model checking

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Observation of Dimension-Crossover of a Tunable 1D Dirac Fermion in Topological Semimetal NbSixTe2

arXiv

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arXiv 2022年

作者： Zhang, Jing Lv, Yangyang Feng, Xiaolong Liang, Aiji Xia, Wei Mo, Sung-Kwan Chen, Cheng Xue, Jiamin Yang, Shengyuan A. Yang, Lexian Guo, Yanfeng Chen, Yanbin Chen, Yulin Liu, Zhongkai School of Physical Science and Technology ShanghaiTech University Shanghai201210 China University of Chinese Academy of Sciences Beijing100049 China National Laboratory of Solid-State Microstructures School of Physics Collaborative Innovation Centre of Advanced Microstructures Nanjing University Nanjing210093 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore487372 Singapore ShanghaiTech Laboratory for Topological Physics Shanghai201210 China Advanced Light Source Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Physics University of Oxford OxfordOX1 3PU United Kingdom State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China

Condensed matter systems in low dimensions exhibit emergent physics that does not exist in three dimensions. When electrons are confined to one dimension (1D), some significant electronic states appear, such as charge density wave, spin-charge separations and Su-Schrieffer-Heeger (SSH) topological state. However, a clear understanding of how the 1D electronic properties connects with topology is currently lacking. Here we systematically investigated the characteristic 1D Dirac fermion electronic structure originated from the metallic NbTe2chains on the surface of the composition-tunable layered compound NbSixTe2(x = 0.40 and 0.43) using angle-resolved photoemission spectroscopy. We found the Dirac fermion forms a Dirac nodal line structure protected by the combined Myand time-reversal symmetry T and proves the NbSixTe2system as a topological semimetal, in consistent with the ab-initio calculations. As x decreases, the interaction between adjacent NbTe2chains increases and Dirac fermion goes through a dimension-crossover from 1D to 2D, as evidenced by the variation of its Fermi surface and Fermi velocity across the Brillouin zone in consistence with a Dirac SSH model. Our findings demonstrate a tunable 1D Dirac electron system, which offers a versatile platform for the exploration of intriguing 1D physics and device applications. Copyright © 2022, The Authors. All rights reserved.

关键词： Charge density waves

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Interfacial area correlation for annular flow in vertical pipes 27

Interfacial area correlation for annular flow in vertical pi...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Liu, Hang Huang, Haojie Lai, Jianyong Pan, Liangming Li, Yi Zhou, Wenxiong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Nanjing Research Institute of El ectronics Technology Nanjing210000 China Department of Nuclear Engineering Chongqing University Chongqing400044 China

ISBN: (纸本)9784888983051

Interfacial area concentration is one of the most critical parameters in two-phase flow and reflects the interfacial area of mass, momentum and energy transfer. The prediction of interfacial area concentration is also essential to close the interfacial transfer terms in the two-fluid model. The calculation of interfacial area concentration has been well developed from bubbly flow to churn flow, including interfacial area correlations and two-group interfacial area transport equation. While seldom researchers focus on that for annular flow or annular mist flow. This paper proposed the one-dimensional interfacial area correlation for annular flow in vertical pipes based on the averaged liquid film thickness model for annular flow. The effects of the droplets in pipes were also considered in the model. The new model has been evaluated against the existing experimental data. The results indicate that the new model can provide the excellent prediction of the interfacial area concentration for annular flow in vertical pipes. Copyright © 2018-2019 by JSME

关键词： Two phase flow

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Aerodynamic interactions of staggered counter-rotating rotor system

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Chinese Journal of Aeronautics 2025年

作者： He ZHU Yuhao DU Hong NIE Shaoxiong WEI Xiaohui WEI National Key Laboratory of Helicopter Aeromechanics Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

With the widespread application of Staggered Counter-rotating Rotor (SCR) systems in eVTOL and UAV configurations, a comprehensive understanding of SCR performance under Out-of-Ground Effect (OGE) and In-Ground Effect (IGE) conditions is crucial for aircraft design and landing safety. This study experimentally measured the changes in thrust and torque of the upper and lower rotors in an SCR system under varying axial and radial distances. It focuses on the interaction mechanisms between the upper and lower rotors and conducts specific IGE state experiments for certain SCR configurations. The findings reveal that changes in the lower rotor predominantly influence the overall performance of the SCR system, regardless of OGE or IGE conditions. Under OGE conditions, radial distance has a more significant impact than axial distance. Conversely, under IGE conditions, the axial distance plays a critical role in improving SCR system performance. These results provide a broad parameter range to assess SCR system performance variations, offering guidance for the design of new concept rotorcraft configurations and the development of aerodynamic prediction models under IGE conditions.

关键词： eVTOL Staggered counter-rotating rotors Aerodynamic interaction Ground effect Flow visualization Rotorcraft design

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