Maintaining the structural integrity of parallel natural gas pipelines during leakage-induced jet fires remains a critical engineering challenge.Existing methods often fail to account for the complex interactions amon...Maintaining the structural integrity of parallel natural gas pipelines during leakage-induced jet fires remains a critical engineering challenge.Existing methods often fail to account for the complex interactions among heat transfer,material behavior,and pipeline geometry,which can lead to overly simplified and potentially unsafe assessments.To address these limitations,this study develops a multiphysics approach that integrates small-orifice leakage theory with detailed thermo-fluid-structural simulations.The proposed framework contributes to a more accurate failure analysis through three main components:(1)coupled modeling that tracks transient heat flow and stress development as fire conditions evolve;(2)risk assessment incorporating spatial layout,material property changes with temperature,and operational limits;and(3)sensitivity analysis to identify key design factors that influence structural performance under high thermal loads.Simulation results demonstrate that thermal radiation from neighboring jet fires significantly accelerates material degradation,with inter-pipeline spacing emerging as a critical determinant of structural response.Notably,increasing the spacing between pipelines reduces thermal interaction and mechanical stress transfer.As a result,systems with optimized spacing exhibit markedly lower deformation than conventional configurations.These findings provide a foundation for re-evaluating pipeline layout strategies and strengthening safety protocols,particularly in high-risk environments where fire exposure can severely compromise structural reliability.The proposed approach offers actionable guidance for engineers and policymakers seeking to enhance the resilience of pipeline infrastructure under extreme thermal conditions.展开更多
Persistent severe rainfall(PSR)events,defined as regional-scale rainfall processes with daily precipitation no less than 50 mm for at least three consecutive days,frequently occur over South China(SC)and the middle-to...Persistent severe rainfall(PSR)events,defined as regional-scale rainfall processes with daily precipitation no less than 50 mm for at least three consecutive days,frequently occur over South China(SC)and the middle-to-lower Yangtze River Basin(MLYRB),with distinct dynamic mechanisms and moisture conditions in the two regions.Based on daily precipitation observations from China’s national meteorological stations and ERA5 reanalysis during 2012-21,this study investigates the spatiotemporal distribution of PSR events in SC and MLYRB and their associated three-dimensional circulation dynamics.The analysis integrates diagnostics of 200 hPa wave activity flux,perturbation streamfunction,500 hPa geopotential height,850 hPa wind fields,and integrated water vapor transport.Results show that PSR events in SC mainly occur during May-June,with rainfall centers over coastal and central Guangdong and Guangxi.In contrast,MLYRB events peak during June-July,with a banded rainfall pattern along the middle-to-lower Yangtze River.Dynamical diagnostics indicate that,in SC,sustained northwest-southeast propagation of 200 hPa disturbances,the southward shift of the 500 hPa trough,and steady subtropical high maintenance provide continuous dynamical support.Concurrently,strong and persistent 850 hPa southwesterlies and long-lasting moisture transport form favorable moisture conditions.In contrast,MLYRB events are marked by rapid phase transitions of 200 hPa streamfunction anomalies and northward-westward expansion of the 500 hPa subtropical high,triggering intense rainfall development.Simultaneously,abrupt enhancement of 850 hPa southwesterlies and rapid formation of a southwest moisture corridor ensure abundant and timely moisture supply,facilitating PSR onset.展开更多
Tea is considered to be a well-known and widely consumed beverage and Hunan province is rich in tea plant germplasm.In order to better conserve and utilize Hunan tea plant resources,110 tea accessions from seven geogr...Tea is considered to be a well-known and widely consumed beverage and Hunan province is rich in tea plant germplasm.In order to better conserve and utilize Hunan tea plant resources,110 tea accessions from seven geographical origins were used to assess genetic diversity of Hunan tea plant germplasm through genotyping by sequencing(GBS)technology.As a result,a total of 311,044 high-quality single nucleotide polymorphism(SNP)markers were obtained.Population structure,phylogenetic relationships and principal component analysis(PCA)divided the entire accessions into three groups.The genetic diversity and population differentiation analysis showed that the mean observed heterozygosity(Ho)ranged from 0.16 to 0.24,while the mean polymorphic information content(PIC)ranged from 0.14 to 0.17,and mean minor allele frequency(MAF)ranged from 0.11 to 0.14.Analysis of molecular variance(AMOVA)indicated that 81.38%of the total variance was derived from within populations,which suggested a rich genetic diversity in Hunan tea germplasms.Furthermore,a core tea germplasm set was developed,which was comprised of 22 tea plant accessions and maintained the whole genetic diversity of the entire collection.This work should be valuable for conservation and utilization of tea germplasm in Hunan。展开更多
文摘Maintaining the structural integrity of parallel natural gas pipelines during leakage-induced jet fires remains a critical engineering challenge.Existing methods often fail to account for the complex interactions among heat transfer,material behavior,and pipeline geometry,which can lead to overly simplified and potentially unsafe assessments.To address these limitations,this study develops a multiphysics approach that integrates small-orifice leakage theory with detailed thermo-fluid-structural simulations.The proposed framework contributes to a more accurate failure analysis through three main components:(1)coupled modeling that tracks transient heat flow and stress development as fire conditions evolve;(2)risk assessment incorporating spatial layout,material property changes with temperature,and operational limits;and(3)sensitivity analysis to identify key design factors that influence structural performance under high thermal loads.Simulation results demonstrate that thermal radiation from neighboring jet fires significantly accelerates material degradation,with inter-pipeline spacing emerging as a critical determinant of structural response.Notably,increasing the spacing between pipelines reduces thermal interaction and mechanical stress transfer.As a result,systems with optimized spacing exhibit markedly lower deformation than conventional configurations.These findings provide a foundation for re-evaluating pipeline layout strategies and strengthening safety protocols,particularly in high-risk environments where fire exposure can severely compromise structural reliability.The proposed approach offers actionable guidance for engineers and policymakers seeking to enhance the resilience of pipeline infrastructure under extreme thermal conditions.
基金funded by the Science and Technology Development Fund of Macao Special Administrative Region(Grant No.0009/2024/RIB1)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030004).
文摘Persistent severe rainfall(PSR)events,defined as regional-scale rainfall processes with daily precipitation no less than 50 mm for at least three consecutive days,frequently occur over South China(SC)and the middle-to-lower Yangtze River Basin(MLYRB),with distinct dynamic mechanisms and moisture conditions in the two regions.Based on daily precipitation observations from China’s national meteorological stations and ERA5 reanalysis during 2012-21,this study investigates the spatiotemporal distribution of PSR events in SC and MLYRB and their associated three-dimensional circulation dynamics.The analysis integrates diagnostics of 200 hPa wave activity flux,perturbation streamfunction,500 hPa geopotential height,850 hPa wind fields,and integrated water vapor transport.Results show that PSR events in SC mainly occur during May-June,with rainfall centers over coastal and central Guangdong and Guangxi.In contrast,MLYRB events peak during June-July,with a banded rainfall pattern along the middle-to-lower Yangtze River.Dynamical diagnostics indicate that,in SC,sustained northwest-southeast propagation of 200 hPa disturbances,the southward shift of the 500 hPa trough,and steady subtropical high maintenance provide continuous dynamical support.Concurrently,strong and persistent 850 hPa southwesterlies and long-lasting moisture transport form favorable moisture conditions.In contrast,MLYRB events are marked by rapid phase transitions of 200 hPa streamfunction anomalies and northward-westward expansion of the 500 hPa subtropical high,triggering intense rainfall development.Simultaneously,abrupt enhancement of 850 hPa southwesterlies and rapid formation of a southwest moisture corridor ensure abundant and timely moisture supply,facilitating PSR onset.
基金The Central Government Guides Local Funds(2019XF5041)Hunan Agricultural Science and Technology Innovation Fund(2020CX035)+2 种基金the National Natural Science Foundation of China(32172629,U19A2030,31670689)Provincial Natural Science Foundation of Hunan(2020JJ4358)Hunan Provincial Seed Industry Innovation Project(2021NK1008).
文摘Tea is considered to be a well-known and widely consumed beverage and Hunan province is rich in tea plant germplasm.In order to better conserve and utilize Hunan tea plant resources,110 tea accessions from seven geographical origins were used to assess genetic diversity of Hunan tea plant germplasm through genotyping by sequencing(GBS)technology.As a result,a total of 311,044 high-quality single nucleotide polymorphism(SNP)markers were obtained.Population structure,phylogenetic relationships and principal component analysis(PCA)divided the entire accessions into three groups.The genetic diversity and population differentiation analysis showed that the mean observed heterozygosity(Ho)ranged from 0.16 to 0.24,while the mean polymorphic information content(PIC)ranged from 0.14 to 0.17,and mean minor allele frequency(MAF)ranged from 0.11 to 0.14.Analysis of molecular variance(AMOVA)indicated that 81.38%of the total variance was derived from within populations,which suggested a rich genetic diversity in Hunan tea germplasms.Furthermore,a core tea germplasm set was developed,which was comprised of 22 tea plant accessions and maintained the whole genetic diversity of the entire collection.This work should be valuable for conservation and utilization of tea germplasm in Hunan。
