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Dynamic modeling of thermal conditions for hot-water district-heating networks

Journal of Hydrodynamics 2014年第4期26卷 531-537页

作者：周守军田茂诚赵有恩郭敏 School of thermal Energy Engineering Shandong Jianzhu University School of Energy and Power Engineering Shandong University Department of Computer Science and Technology Shandong University of Finance and Economics

To investigate the dynamic characteristics of the thermal conditions of hot-water district-heating networks, a dynamic modeling method is proposed with consideration of the heat dissipations in pipes and the characteristic line method is adopted to solve it. Besides, the influences of different errors, space steps and initial values on the convergence of the dynamic model results are analyzed for a model network. Finally, a part of a certain city district-heating system is simulated and the results are compared with the actual operation data in half an hour from 6 secondary heat stations. The results indicate that the relative errors for the supply pressure and temperature in 5 stations are all within 2%, except in one station, where the relative error approaches 4%. So the proposed model and algorithm are validated.

关键词： district-heating network thermal conditions dynamic modeling characteristic line method

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Temporal and Spatial Distribution Characteristics of Lightning Activity over the Pacific Ocean and Adjacent Land and Its Relationship with AOD and CAPE

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Journal of Tropical Meteorology 2022年第4期28卷 473-488页

作者：初雨郭凤霞张志伟邹迪可吴泽怡刘舟鲁鲜 Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)/Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological AdministrationNanjing University of Information Science and TechnologyNanjing 210044 China

Based on LIS/OTD gridded lightning climatology data,ERA5 reanalysis data,and MODIS atmosphere monthly global products,we examined latitudinal and daily variations of lightning activity over land,offshore areas,open sea,and all marine areas(i.e.,the aggregate of open sea and offshore areas)for different seasons over the Pacific Ocean and the adjacent land areas at 65°N-50°S,99°E-78°W,and analysed the relationships of lightning activity with CAPE(Convective Available Potential Energy)and AOD(Aerosol Optical Depth).At any given latitude,the lightning density is the highest over land,followed by offshore areas,all marine areas and the open sea in sequence.The lightning density over land is approximately an order of magnitude greater than that over all marine areas.Lightning activity over land,offshore areas,open sea,and all marine areas varies with season.The diurnal variation of lightning density over land has a single-peak pattern.Over the offshore area,open sea,and all marine areas,lightning densities have two maxima per day.The magnitude of the daily variation in mean lightning density is the largest over land and the smallest over the open sea.The lightning density over the Pacific Ocean and adjacent land areas is significantly and positively correlated with CAPE.The correlation is the strongest over land and the weakest over the open sea.Cloud Base Height(CBH)may affect the efficiency of CAPE conversion to updraft.CAPE has a positive effect on lightning activity and has a greater impact on land than on the ocean.Over the sea,both CAPE and AOD can contribute to lightning activity,but the magnitudes of the influence of CAPE and AOD on lightning activity remain to be determined.Lightning activity over land and sea is a result of the combined action of AOD and CAPE.

关键词： Pacific lightning land-sea contrast thermal conditions aerosol

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Finite Element Structural Analysis of Buried Pipelines

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Modern Mechanical Engineering 2022年第2期12卷 27-44页

作者： Casanova-del-Angel Francisco Córdova-Castillo Alejandra Escuela Superior de Ingeniería y Arquitectura UP ALM SEPI of the Instituto Politécnico Nacional Mexico City Mexico

This document uses previous results (which we call the first stage), for the development of a computer model based on finite elements under the FEAP programmer, to carry out a structural analysis of a pipeline. For this purpose, we used environmental variables that we believe influence the failure of buried pipelines such as the internal pressure of fluid, the type of support used, the temperature at which the pipelines work, the type of soil and the stiffness of the soil acting on it. Once the model was finalized, analyses were made with each of the variables separately and combined to observe the behavior of the pipeline, finding the most unfavorable case that indicates the main causes that led to its failure.

关键词： Duct Finite Element Buried Pipeline Material Creep thermal conditions Soil Springs

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Analysis on the Rainstorm Process from June 14 to 15 in 2011

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Meteorological and Environmental Research 2012年第11期3卷 15-21页

作者： DAI Jin LV Xiao-hua XIE Mei-lan LU Tao Shaoyang Meteorological Bureau in Hunan Province Shaoyang County Meteorological Bureau in Hunan Province

Based on the conventional observational data, NCEP, satellite and radar data, the weather diagnosis and mesoscale analysis of the first rainstorm appearing in Shaoyang City since the flood season from June 14 to 15 in 2011 were carried out. The results showed that this rainstorm occurring in the whole Shaoyang City was an typical rainstorm during the first rainy season, and resulted from the strong development of the mesoscale system generated under extremely favorable weather situation. Guided by the cold advection behind the East Asia trough at 500 hPa, cold air moved southward and met southwest airflow in the northwest of strong subtropical high, so that the junction zone of clod and warm airflow was kept in the middle of Hunan Province. In addition, the stable junction zone of clod and warm airflow as well as extremely vigorous southwest warm and wet airflow made the rainstorm have adequate water vapor, dynamic and thermal conditions, which was extremely beneficial to the stong development of small and medium-scale convection systems. In a word, due to stong water vapor and convergence upward movement, reinforcement of low-level southwest jet, activity of low-level weak cold air, exacerbation of convective unstable stratification, superposition of strong divergence at high levels, and obvious development of vertical vorticity caused by vertical shear of horizontal wind or increase of moist baroclinicity, the rainstorm happened in Shaoyang City.

关键词： Rainstorm Mesoscale system Dynamic conditions thermal conditions China

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