Coastal cities in Vietnam face increasing urban flooding vulnerability due to climate change-induced extreme pre-cipitation.This study evaluates the response capacity of urban drainage systems,using Vung Tau City as a...Coastal cities in Vietnam face increasing urban flooding vulnerability due to climate change-induced extreme pre-cipitation.This study evaluates the response capacity of urban drainage systems,using Vung Tau City as a case study.We employed a comprehensive approach,combining Intensity-Duration-Frequency(IDF)curve analysis with hydrodynamic modeling,to assess drainage performance under current and projected rainfall intensities.A significant rainfall event on June 19,2020(54.4 mm in 3 h,peaking at 42 mm/h),which exceeded the 5-year return period design(TCVN 7957:2008),caused widespread flooding(25-50 cm depths).Design rainfall hyetographs for 2,5,and 10-year return periods(TCVN 7957:2008)were developed.Results show that under more extreme scenarios,flooded areas increase significantly,with depths up to 1.05 m in the 10-year scenario and prolonged durations due to stormwater routing through regulatory lakes.The analysis reveals the current infrastructure meets only 64%of the 5-year return period demands and merely 41% for a 10-year period.This research highlights the urgent need for enhanced flood management in Vung Tau and similar coastal cities,suggesting upgrades to drainage capacity,implementation of sustainable urban drainage systems,and improved early warning.These insights are valuable for developing climate-resilient infrastructure.展开更多
This article focuses on the optimization of water supply and drainage systems,involving theories such as hydraulic models of pipeline systems and multi-objective collaborative optimization.It introduces the system dyn...This article focuses on the optimization of water supply and drainage systems,involving theories such as hydraulic models of pipeline systems and multi-objective collaborative optimization.It introduces the system dynamics model of sewage treatment facility expansion.Elaborating on detection technology,construction of an intelligent operation and maintenance system,and factors to be considered for sewage plant expansion,it emphasizes the importance of collaborative development and verifies benefits through the PSR model.展开更多
This research shows the outcomes of laboratory-scale experiments to enhance the pull-out capacity of geosynthetic reinforced soil via an intelligent drainage system.The intelligent drainage system is designed inside a...This research shows the outcomes of laboratory-scale experiments to enhance the pull-out capacity of geosynthetic reinforced soil via an intelligent drainage system.The intelligent drainage system is designed inside a pull-out machine and is made of gravel and geotextiles.The drained water is collected in a container.The experiments were conducted following ASTM standard D 6706-01.Various test parameters,such as soil moisture levels and the magnitude of external loads,were considered during the experimental procedure.The experiments included temperatures of 20℃,35℃,and 50℃with an initial saturation of about 90%.The results showed that the temperature-aided intelligent drainage system increased the pull-out strength of the geosynthetic reinforced soil.Furthermore,there was also an increase in the interaction coefficient and the interface friction angle.Therefore,the detrimental effects of a saturated geosynthetic reinforced soil,especially during heavy rains which often cause failure,can be diminished by the proposed system.The research findings indicated that the intelligent drainage system enhanced the pull-out capacity and strength-related parameters of the geosynthetic reinforced soil by approximately 25%,thereby augmenting its internal stability.The practical implications of these results are thoroughly examined in the paper.展开更多
In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor...In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor to ensure the invert stability by regulating the external water pressure(EWP). By means of a threedimensional(3D) printing model, this paper experimentally investigates the deformation behavior of the invert for the tunnels with the traditional drainage system(TDS) widely used in China and its optimized drainage system(ODS) with bottom drainage function. Six test groups with a total of 110 test conditions were designed to consider the design factors and environmental factors in engineering practice,including layout of the drainage system, blockage of the drainage system and groundwater level fluctuation. It was found that there are significant differences in the water discharge, EWP and invert stability for the tunnels with the two drainage systems. Even with a dense arrangement of the external blind tubes, TDS was still difficult to eliminate the excessive EWP below the invert, which is the main cause for the invert instability. Blockage of drainage system further increased the invert uplift and aggravated the track irregularity, especially when the blockage degree is more than 50%. However, ODS can prevent these invert anomalies by reasonably controlling the EWP at tunnel bottom. Even when the groundwater level reached 60 m and the blind tubes were fully blocked, the invert stability can still be maintained and the railway track experienced a settlement of only 1.8 mm. Meanwhile, the on-site monitoring under several rainstorms further showed that the average EWP of the invert was controlled within 84 k Pa, while the maximum settlement of the track slab was only 0.92 mm, which also was in good agreement with the results of model test.展开更多
The dissolved oxygen content in water is an important indicator for assessing the quality of the water environment,and maintaining a certain amount of dissolved oxygen is essential for the healthy development of the e...The dissolved oxygen content in water is an important indicator for assessing the quality of the water environment,and maintaining a certain amount of dissolved oxygen is essential for the healthy development of the ecological environment.When a water body is anoxic,the activity of anaerobic microorganisms increases and organic matter is decomposed to produce a large number of blackening and odorizing substances,resulting in black and odorous water bodies,which is a very common and typical phenomenon in China.Presently,there is still a relatively universal occurrence of illicitly connected stormwater and sewage pipes in the urban drainage pipe network in China,which makes oxygen-consuming substances be directly discharged into rivers through stormwater pipes and consume the dissolved oxygen in the water bodies,resulting in an oxygen deficiency of the water.This induces seasonal or year-round black and stink phenomena in urban rivers.Hence,identifying high oxygen-consuming substances,which lays the foundation for the subsequent removal of oxygen-consuming substances,is essential.Through a series of comparisons of water quality indicators and analysis of organic characteristics,it was found that the oxygen consumption capacity of domestic sewage was higher than that of industrial wastewater in the selected area of this study,and the oxygen-consuming substances of domestic sewage were small molecular amino acids.By comparing 20 conventional free amino acids,it was found that seven of them consumed oxygen easily,and compared with chemical oxygen consumption,biological oxygen consumption was in a leading position.展开更多
Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging par...Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was derived.Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression.Studies have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually decreases.The hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased.When the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value.When the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured value.The difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.展开更多
While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted...While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted paradigm) does not permit geomorphologists to satisfactorily explain. A new and fundamentally different paradigm able to explain the drainage system and other erosional landform evidence has recently emerged, but requires what the accepted paradigm considers to be the preglacial (and probably mid-Cenozoic) Bell River drainage system to have formed on a melting continental ice sheet’s floor. The new paradigm’s melting ice sheet had previously eroded bedrock underneath it and caused crustal warping that raised continental regions and mountain ranges so as to create and occupy a deep “hole” while massive and prolonged meltwater floods flowed across rising continental regions and mountain ranges to the south. The new paradigm leads to a completely different middle Cenozoic geologic and glacial history than the accepted paradigm describes and the two paradigms are analyzed according to good science expectations such as using evidence anyone can see, applying common sense logic during each research step, producing consistent results, and simplicity of paradigm generated explanations. The new paradigm uses topographic map evidence anyone can see, appears to use common sense logic during each research step, and produces remarkably consistent results leading to a simpler Cenozoic northern Missouri River drainage basin region geologic and glacial history than what the accepted paradigm describes. Further work is needed to test the new paradigm’s ability to explain drainage system and erosional landform evidence in other geographic regions such as in the Ohio River drainage basin.展开更多
In view of the frequent waterlogging caused by rapid urbanization and the public’s dissatisfaction with the drainage system,the article based on the concept of the green ecological drainage system,constructed the urb...In view of the frequent waterlogging caused by rapid urbanization and the public’s dissatisfaction with the drainage system,the article based on the concept of the green ecological drainage system,constructed the urban green ecological drainage comprehensive simulation research system,and quickly evaluated pipe network operation and surface water of an industrial park under typical rainfall conditions.The results showed that the drainage capacity of the designed green ecological rainwater drainage system reached 100%,and there was no ponding phenomenon,which indicated that the green ecological rainwater drainage system could effectively solve the practical problems of urban drainage.The green ecological rainwater comprehensive simulation research system had good adaptability.The research results provided the scientific theoretical basis and reference significance for planning,designing,constructing,operating,and managing urban rainwater system scientifically and systematically.展开更多
Englacial and subglacial drainage systems of temperate glaciers have a strong influence on glacier dynamics, glacier-induced floods, glacier-weathering processes, and runoff from glacierized drainage basins. Proglacia...Englacial and subglacial drainage systems of temperate glaciers have a strong influence on glacier dynamics, glacier-induced floods, glacier-weathering processes, and runoff from glacierized drainage basins. Proglacial discharge is partly controlled by the geometry of the glacial drainage network and by the process of producing meltwater. The glacial-drainage system of some alpine glaciers has been characterized using a model based on proglacial discharge analysis. In this paper, we apply cross-correlation analysis to hourly hydro-climatic data collected from China＇s Hailuogou Glacier, a typical temperate glacier in Mt. Gongga, to study the seasonal status changes of the englacial and subglacial drainage systems by discharge-temperature （Q-T） time lag analy-sis. During early ablation season （April-May） of 2003, 2004 and 2005, the change of englacial and subglacial drainage system usually leads several outburst flood events, which are also substantiated by observing the leakage of supraglacial pond and cre-vasses pond water during field works in April, 2008. At the end of ablation season （October-December）, the glacial-drainage net-works become less hydro-efficient. Those events are evidenced by hourly hydro-process near the terminus of Hailuogou Glacier, and the analysis of Q-T time lags also can be a good indicator of those changes. However, more detailed observations or experi-ments, e.g. dye-tracing experiment and recording borehole water level variations, are necessary to describe the evolutionary status and processes of englacial and subglacial drainage systems evolution during ablation season.展开更多
The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human health.Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be d...The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human health.Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be discharged with feces into the drainage system.However,a comprehensive understanding of the occurrence,presence,and potential transmission of SARS-CoV-2 in sewers,especially in community sewers,is still lacking.This study investigated the virus occurrence by viral nucleic acid testing in vent stacks,septic tanks,and the main sewer outlets of community where confirmed patients had lived during the early days of the epidemic in Wuhan,China.The results indicated that the risk of long-term emission of SARS-CoV-2 to the environment via vent stacks of buildings was low after confirmed patients were hospitalized.SARS-CoV-2 were mainly detected in the liquid phase,as opposed to being detected in aerosols,and its RNA in the sewage of septic tanks could be detected for only four days after confirmed patients were hospitalized.The surveillance of SARS-CoV-2 in sewage could be a sensitive indicator for the possible presence of asymptomatic patients in the community,though the viral concentration could be diluted more than ten times,depending on the sampling site,as indicated by the Escherichia coli test.The comprehensive investigation of the community sewage drainage system is helpful to understand the occurrence characteristics of SARS-CoV-2 in sewage after excretion with feces and the feasibility of sewage surveillance for COVID-19 pandemic monitoring.展开更多
A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. Th...A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. The fundamental accuracy of the numerical model was first clarified by comparison with the experimental results for a single drainage pipe. Boundary conditions for junctions and bends, which are often encountered in drainage systems, were studied both experimentally and numerically. The numerical model was applied to an actual drainage system. Comparison with a full-scale model experiment indicates that the model can be used to accurately predict flow characteristics in actual drainage networks.展开更多
Based on rural drainage problems, the research analyzed traditional water culture in ancient vil ages in Jiangxi, as wel as flood control theory, and proposed specific theories and measures for drainage system improve...Based on rural drainage problems, the research analyzed traditional water culture in ancient vil ages in Jiangxi, as wel as flood control theory, and proposed specific theories and measures for drainage system improvement and construction in order to seek proper rural drainage system and promote rural sustainable develop-ment.展开更多
The vegetable production in Cambodia has been plagued with poor productivity and broken chain,leaving the comparative advantage to the neighboring countries,namely Vietnam and Thailand.Poor soil condition during wet s...The vegetable production in Cambodia has been plagued with poor productivity and broken chain,leaving the comparative advantage to the neighboring countries,namely Vietnam and Thailand.Poor soil condition during wet season has been significantly impacting the productivity of vegetable production in Cambodia which leads to an introduction of sub-surface drainage system at the root zone of Chinese cabbage under this paper.The aim of the experiment is to determine the possibility in increasing the effectiveness and productivity during wet season of Cambodian vegetable producers.The results of the experiment indicate positive improvement in terms of yield and growth of the Chinese cabbage at a rate of 24%and 34%for T2 and T3,respectively.There are,however,limited practicality and generalization for the research due to the controlling factors during the experiment and the detailed experimental setting which need further analysis,especially economic analysis and following up research work.展开更多
Due to the frequent leakage of pipes and valves in the current water supply and drainage system engineering, water resources are wasted and the overall engineering quality is poor. The design of water supply and drain...Due to the frequent leakage of pipes and valves in the current water supply and drainage system engineering, water resources are wasted and the overall engineering quality is poor. The design of water supply and drainage system for green buildings is studied. Obtain the water supply and drainage volume and design the maximum daily water consumption. Select water supply and drainage mode, and use frequency conversion water supply and shunt system to realize water supply and drainage of buildings. Water supply and drainage equipment and pipes are selected to ensure construction quality. Water supply and drainage design model is built based on BIM, and pipeline space is reserved. Arrange and lay water supply and drainage pipelines to complete the design of water supply and drainage system for engineering buildings. Through the demonstration and analysis of examples, the system effectively reduces the sewage discharge and tap water consumption, has good energy-saving effect, and generally meets the requirements of two stars for green buildings, which proves the reliability of the system.展开更多
Objective: to analyze the CT imaging anatomy of frontal sinus drainage system and its clinical application value. Methods: 50 patients with chronic sinusitis admitted from November 2019 to October 2020 were selected a...Objective: to analyze the CT imaging anatomy of frontal sinus drainage system and its clinical application value. Methods: 50 patients with chronic sinusitis admitted from November 2019 to October 2020 were selected and included in the study. All patients underwent frontal sinus drainage system examination with CT. The patients underwent cross-sectional scanning first, and then underwent coronal and sagittal three-dimensional reconstruction through the workstation. The CT imaging anatomy characteristics of frontal sinus drainage system and its application value in chronic sinusitis were analyzed. Results: in the CT examination results, 100 sides of uncinate process were detected, including the papyraceous lamina, the air chamber of the nasal dome, the middle turbinate, the anterior skull base and the bifurcation accounted for 35.0%, 12.0%, 27.0% and 17.0% respectively, 90 cases of air chamber of the frontal recess were detected, including the terminal air chamber, the air chamber of the nasal dome and the air chamber of the anterior ethmoid, accounted for 55.6%, 22.2% and 22.2% respectively, 92 cases of air chamber of the frontal sinus were detected, including the air chamber of the frontal recess, the air chamber of the supraorbital, the air chamber of the frontal sinus accounted for 32.6% and 43.5%, 23.9% respectively. Conclusion: CT can effectively clarify the anatomical structure of the frontal sinus drainage system and effectively detect various lesions, providing detailed basis for clinical disease diagnosis and surgical treatment.展开更多
The method of utilizing rain water has been well developed in foreign countries to realize the sustainable development of water recourse while the method is still at the initial level in China. When considering the in...The method of utilizing rain water has been well developed in foreign countries to realize the sustainable development of water recourse while the method is still at the initial level in China. When considering the increasing of water shortage and urban flood, the awareness of utilizing rain water, as an inevitable trend, has been applied to various engineering technologies. This article has analyzed the principle of conventional road drainage system and the application of artificial wetland technology, also proposed to combine the road drainage system and artificial wetland, as a complex drainage system, to utilize the urban rain water, decrease urban flood pressure, and improve urban micro environment. The calculation principle and method for the complex drainage system are included as well.展开更多
The building water supply and drainage system has an important impact and even a decisive role on its service function. Reasonable planning and construction and the construction of a complete water supply and drainage...The building water supply and drainage system has an important impact and even a decisive role on its service function. Reasonable planning and construction and the construction of a complete water supply and drainage project can improve the comfort level, avoid problems in the subsequent use of the project, improve the fire safety of the building, reduce losses caused by emergencies such as fire and safeguard the safety of lives and property of residents. This paper analyzes the composition and function of the building water supply and drainage system in our country, and on this basis, makes a detailed analysis of the construction technology of the installation project, hoping to play a reference role.展开更多
Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological...Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological diseases have been widely explored.The glymphatic system is a fluid drainage and waste clearance pathway that utilizes perivascular space and aquaporin-4 protein located in the astrocyte endfeet to provide a space for exchange of cerebrospinal fluid and interstitial fluid.The intramural periarterial drainage pathway drives the flow of interstitial fluid through the capillary basement membrane and the arterial tunica media.Meningeal lymphatic vessels within the dura mater are involved in the removal of cerebral macromolecules and immune responses.After ischemic stroke,impairment of these systems could lead to cerebral edema,accumulation of toxic factors,and activation of neuroinflammation,while restoration of their normal functions can improve neurological outcomes.In this review,we summarize the basic concepts of these drainage systems,including drainage routes,physiological functions,regulatory mechanisms,and detection technologies.We also focus on the roles of lymphatic drainage systems in brain injury after ischemic stroke,as well as recent advances in therapeutic strategies targeting these drainage systems.These findings provide information for potential novel strategies for treatment of stroke.展开更多
The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applie...The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .展开更多
The rain shadow regions requisite a comprehensive watershed development and management plan for sustainable water resources management. The Pambar River Basin （PRB） lies on the rain shadow region of the southern Wes...The rain shadow regions requisite a comprehensive watershed development and management plan for sustainable water resources management. The Pambar River Basin （PRB） lies on the rain shadow region of the southern Western Ghats, India, where climate showed marked intra-basin variation. A morphometric analysis was done to evaluate the drainage characteristics of PRB using topographical maps and digital elevation data. PRB was divided into eighteen 4th order basins （SB1-SB18）, distributed along various climatic gradients. Lower order streams mostly dominate PRB and drainage pattern is a function of relief and structure. The terrain is highly dissected and prone to soil erosion during heavy storms and the elongated shape of PRB enables easier flood management. The influence of climate on drainage characteristics was evidently emphasized in basin morphometry. Four distinctively different classes were identified based on the morphometric similarities. The significance of morphometric analysis on the hydrological characterization is discussed and the relevance of the present study in water harvesting has been explicated.展开更多
基金supported by the Ministry of Natural Resources and Environment project 2024.06.04,“Research on the application of artificial intelligence combined with remote sensing in warning of flood risks due to heavy rain and high tides for coastal cities”,grant number 2024.06.04.
文摘Coastal cities in Vietnam face increasing urban flooding vulnerability due to climate change-induced extreme pre-cipitation.This study evaluates the response capacity of urban drainage systems,using Vung Tau City as a case study.We employed a comprehensive approach,combining Intensity-Duration-Frequency(IDF)curve analysis with hydrodynamic modeling,to assess drainage performance under current and projected rainfall intensities.A significant rainfall event on June 19,2020(54.4 mm in 3 h,peaking at 42 mm/h),which exceeded the 5-year return period design(TCVN 7957:2008),caused widespread flooding(25-50 cm depths).Design rainfall hyetographs for 2,5,and 10-year return periods(TCVN 7957:2008)were developed.Results show that under more extreme scenarios,flooded areas increase significantly,with depths up to 1.05 m in the 10-year scenario and prolonged durations due to stormwater routing through regulatory lakes.The analysis reveals the current infrastructure meets only 64%of the 5-year return period demands and merely 41% for a 10-year period.This research highlights the urgent need for enhanced flood management in Vung Tau and similar coastal cities,suggesting upgrades to drainage capacity,implementation of sustainable urban drainage systems,and improved early warning.These insights are valuable for developing climate-resilient infrastructure.
文摘This article focuses on the optimization of water supply and drainage systems,involving theories such as hydraulic models of pipeline systems and multi-objective collaborative optimization.It introduces the system dynamics model of sewage treatment facility expansion.Elaborating on detection technology,construction of an intelligent operation and maintenance system,and factors to be considered for sewage plant expansion,it emphasizes the importance of collaborative development and verifies benefits through the PSR model.
文摘This research shows the outcomes of laboratory-scale experiments to enhance the pull-out capacity of geosynthetic reinforced soil via an intelligent drainage system.The intelligent drainage system is designed inside a pull-out machine and is made of gravel and geotextiles.The drained water is collected in a container.The experiments were conducted following ASTM standard D 6706-01.Various test parameters,such as soil moisture levels and the magnitude of external loads,were considered during the experimental procedure.The experiments included temperatures of 20℃,35℃,and 50℃with an initial saturation of about 90%.The results showed that the temperature-aided intelligent drainage system increased the pull-out strength of the geosynthetic reinforced soil.Furthermore,there was also an increase in the interaction coefficient and the interface friction angle.Therefore,the detrimental effects of a saturated geosynthetic reinforced soil,especially during heavy rains which often cause failure,can be diminished by the proposed system.The research findings indicated that the intelligent drainage system enhanced the pull-out capacity and strength-related parameters of the geosynthetic reinforced soil by approximately 25%,thereby augmenting its internal stability.The practical implications of these results are thoroughly examined in the paper.
基金supported by the National Natural Science Foundation of China (Grant No. U1934211)the Open Foundation of National Engineering Research Center of High-speed Railway Construction Technology (Grant No. HSR202005)Scientific Research Project of Hunan Education Department (Grant No.20B596)。
文摘In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor to ensure the invert stability by regulating the external water pressure(EWP). By means of a threedimensional(3D) printing model, this paper experimentally investigates the deformation behavior of the invert for the tunnels with the traditional drainage system(TDS) widely used in China and its optimized drainage system(ODS) with bottom drainage function. Six test groups with a total of 110 test conditions were designed to consider the design factors and environmental factors in engineering practice,including layout of the drainage system, blockage of the drainage system and groundwater level fluctuation. It was found that there are significant differences in the water discharge, EWP and invert stability for the tunnels with the two drainage systems. Even with a dense arrangement of the external blind tubes, TDS was still difficult to eliminate the excessive EWP below the invert, which is the main cause for the invert instability. Blockage of drainage system further increased the invert uplift and aggravated the track irregularity, especially when the blockage degree is more than 50%. However, ODS can prevent these invert anomalies by reasonably controlling the EWP at tunnel bottom. Even when the groundwater level reached 60 m and the blind tubes were fully blocked, the invert stability can still be maintained and the railway track experienced a settlement of only 1.8 mm. Meanwhile, the on-site monitoring under several rainstorms further showed that the average EWP of the invert was controlled within 84 k Pa, while the maximum settlement of the track slab was only 0.92 mm, which also was in good agreement with the results of model test.
基金supported by the Key Research and Development Program of Guangdong Province(No.2020B1111350001)the National Key Research and Development Program of China(Nos.2021YFC3200700 and 2021YFC3200702)。
文摘The dissolved oxygen content in water is an important indicator for assessing the quality of the water environment,and maintaining a certain amount of dissolved oxygen is essential for the healthy development of the ecological environment.When a water body is anoxic,the activity of anaerobic microorganisms increases and organic matter is decomposed to produce a large number of blackening and odorizing substances,resulting in black and odorous water bodies,which is a very common and typical phenomenon in China.Presently,there is still a relatively universal occurrence of illicitly connected stormwater and sewage pipes in the urban drainage pipe network in China,which makes oxygen-consuming substances be directly discharged into rivers through stormwater pipes and consume the dissolved oxygen in the water bodies,resulting in an oxygen deficiency of the water.This induces seasonal or year-round black and stink phenomena in urban rivers.Hence,identifying high oxygen-consuming substances,which lays the foundation for the subsequent removal of oxygen-consuming substances,is essential.Through a series of comparisons of water quality indicators and analysis of organic characteristics,it was found that the oxygen consumption capacity of domestic sewage was higher than that of industrial wastewater in the selected area of this study,and the oxygen-consuming substances of domestic sewage were small molecular amino acids.By comparing 20 conventional free amino acids,it was found that seven of them consumed oxygen easily,and compared with chemical oxygen consumption,biological oxygen consumption was in a leading position.
基金sponsored by the Research Project on the Damage Mechanism and Performance Recovery of Carbon Phyllite in the Basement of HighSpeed Railway Tunnels in Cold Regions(51978668)the Key Technology of Green Construction of the Hongtu Extra Tunnel(DFH(201904)ys1-001)。
文摘Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was derived.Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression.Studies have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually decreases.The hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased.When the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value.When the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured value.The difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.
文摘While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted paradigm) does not permit geomorphologists to satisfactorily explain. A new and fundamentally different paradigm able to explain the drainage system and other erosional landform evidence has recently emerged, but requires what the accepted paradigm considers to be the preglacial (and probably mid-Cenozoic) Bell River drainage system to have formed on a melting continental ice sheet’s floor. The new paradigm’s melting ice sheet had previously eroded bedrock underneath it and caused crustal warping that raised continental regions and mountain ranges so as to create and occupy a deep “hole” while massive and prolonged meltwater floods flowed across rising continental regions and mountain ranges to the south. The new paradigm leads to a completely different middle Cenozoic geologic and glacial history than the accepted paradigm describes and the two paradigms are analyzed according to good science expectations such as using evidence anyone can see, applying common sense logic during each research step, producing consistent results, and simplicity of paradigm generated explanations. The new paradigm uses topographic map evidence anyone can see, appears to use common sense logic during each research step, and produces remarkably consistent results leading to a simpler Cenozoic northern Missouri River drainage basin region geologic and glacial history than what the accepted paradigm describes. Further work is needed to test the new paradigm’s ability to explain drainage system and erosional landform evidence in other geographic regions such as in the Ohio River drainage basin.
文摘In view of the frequent waterlogging caused by rapid urbanization and the public’s dissatisfaction with the drainage system,the article based on the concept of the green ecological drainage system,constructed the urban green ecological drainage comprehensive simulation research system,and quickly evaluated pipe network operation and surface water of an industrial park under typical rainfall conditions.The results showed that the drainage capacity of the designed green ecological rainwater drainage system reached 100%,and there was no ponding phenomenon,which indicated that the green ecological rainwater drainage system could effectively solve the practical problems of urban drainage.The green ecological rainwater comprehensive simulation research system had good adaptability.The research results provided the scientific theoretical basis and reference significance for planning,designing,constructing,operating,and managing urban rainwater system scientifically and systematically.
基金supported by the National Natural Science Foundation of China (Grant No. 40801030 and 40801025)the Major State Basic Research Development Program of China (973 Program) (2007CB411506)+1 种基金the Innovation Project of Chinese Academy Sciences (Kzcx2-yw-301)the National Basic Work Program of Chinese MST (Glacier Inventory of China Ⅱ, Grant No. 2006FY110200)
文摘Englacial and subglacial drainage systems of temperate glaciers have a strong influence on glacier dynamics, glacier-induced floods, glacier-weathering processes, and runoff from glacierized drainage basins. Proglacial discharge is partly controlled by the geometry of the glacial drainage network and by the process of producing meltwater. The glacial-drainage system of some alpine glaciers has been characterized using a model based on proglacial discharge analysis. In this paper, we apply cross-correlation analysis to hourly hydro-climatic data collected from China＇s Hailuogou Glacier, a typical temperate glacier in Mt. Gongga, to study the seasonal status changes of the englacial and subglacial drainage systems by discharge-temperature （Q-T） time lag analy-sis. During early ablation season （April-May） of 2003, 2004 and 2005, the change of englacial and subglacial drainage system usually leads several outburst flood events, which are also substantiated by observing the leakage of supraglacial pond and cre-vasses pond water during field works in April, 2008. At the end of ablation season （October-December）, the glacial-drainage net-works become less hydro-efficient. Those events are evidenced by hourly hydro-process near the terminus of Hailuogou Glacier, and the analysis of Q-T time lags also can be a good indicator of those changes. However, more detailed observations or experi-ments, e.g. dye-tracing experiment and recording borehole water level variations, are necessary to describe the evolutionary status and processes of englacial and subglacial drainage systems evolution during ablation season.
基金funded by the projects of the Major Program of National Natural Science Foundation of China(52091543)Tsinghua University Spring Breeze Fund(20213080026)the Chinese Academy of Engineering(2020-ZD-15).
文摘The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human health.Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be discharged with feces into the drainage system.However,a comprehensive understanding of the occurrence,presence,and potential transmission of SARS-CoV-2 in sewers,especially in community sewers,is still lacking.This study investigated the virus occurrence by viral nucleic acid testing in vent stacks,septic tanks,and the main sewer outlets of community where confirmed patients had lived during the early days of the epidemic in Wuhan,China.The results indicated that the risk of long-term emission of SARS-CoV-2 to the environment via vent stacks of buildings was low after confirmed patients were hospitalized.SARS-CoV-2 were mainly detected in the liquid phase,as opposed to being detected in aerosols,and its RNA in the sewage of septic tanks could be detected for only four days after confirmed patients were hospitalized.The surveillance of SARS-CoV-2 in sewage could be a sensitive indicator for the possible presence of asymptomatic patients in the community,though the viral concentration could be diluted more than ten times,depending on the sampling site,as indicated by the Escherichia coli test.The comprehensive investigation of the community sewage drainage system is helpful to understand the occurrence characteristics of SARS-CoV-2 in sewage after excretion with feces and the feasibility of sewage surveillance for COVID-19 pandemic monitoring.
基金supported by the National Natural Science Foundation of China (Grant No. 50879035)
文摘A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. The fundamental accuracy of the numerical model was first clarified by comparison with the experimental results for a single drainage pipe. Boundary conditions for junctions and bends, which are often encountered in drainage systems, were studied both experimentally and numerically. The numerical model was applied to an actual drainage system. Comparison with a full-scale model experiment indicates that the model can be used to accurately predict flow characteristics in actual drainage networks.
基金Supported by"Twelfth Five-year Plan"of Jiangxi Provincial Social Sciences Program(14SH05)~~
文摘Based on rural drainage problems, the research analyzed traditional water culture in ancient vil ages in Jiangxi, as wel as flood control theory, and proposed specific theories and measures for drainage system improvement and construction in order to seek proper rural drainage system and promote rural sustainable develop-ment.
文摘The vegetable production in Cambodia has been plagued with poor productivity and broken chain,leaving the comparative advantage to the neighboring countries,namely Vietnam and Thailand.Poor soil condition during wet season has been significantly impacting the productivity of vegetable production in Cambodia which leads to an introduction of sub-surface drainage system at the root zone of Chinese cabbage under this paper.The aim of the experiment is to determine the possibility in increasing the effectiveness and productivity during wet season of Cambodian vegetable producers.The results of the experiment indicate positive improvement in terms of yield and growth of the Chinese cabbage at a rate of 24%and 34%for T2 and T3,respectively.There are,however,limited practicality and generalization for the research due to the controlling factors during the experiment and the detailed experimental setting which need further analysis,especially economic analysis and following up research work.
文摘Due to the frequent leakage of pipes and valves in the current water supply and drainage system engineering, water resources are wasted and the overall engineering quality is poor. The design of water supply and drainage system for green buildings is studied. Obtain the water supply and drainage volume and design the maximum daily water consumption. Select water supply and drainage mode, and use frequency conversion water supply and shunt system to realize water supply and drainage of buildings. Water supply and drainage equipment and pipes are selected to ensure construction quality. Water supply and drainage design model is built based on BIM, and pipeline space is reserved. Arrange and lay water supply and drainage pipelines to complete the design of water supply and drainage system for engineering buildings. Through the demonstration and analysis of examples, the system effectively reduces the sewage discharge and tap water consumption, has good energy-saving effect, and generally meets the requirements of two stars for green buildings, which proves the reliability of the system.
文摘Objective: to analyze the CT imaging anatomy of frontal sinus drainage system and its clinical application value. Methods: 50 patients with chronic sinusitis admitted from November 2019 to October 2020 were selected and included in the study. All patients underwent frontal sinus drainage system examination with CT. The patients underwent cross-sectional scanning first, and then underwent coronal and sagittal three-dimensional reconstruction through the workstation. The CT imaging anatomy characteristics of frontal sinus drainage system and its application value in chronic sinusitis were analyzed. Results: in the CT examination results, 100 sides of uncinate process were detected, including the papyraceous lamina, the air chamber of the nasal dome, the middle turbinate, the anterior skull base and the bifurcation accounted for 35.0%, 12.0%, 27.0% and 17.0% respectively, 90 cases of air chamber of the frontal recess were detected, including the terminal air chamber, the air chamber of the nasal dome and the air chamber of the anterior ethmoid, accounted for 55.6%, 22.2% and 22.2% respectively, 92 cases of air chamber of the frontal sinus were detected, including the air chamber of the frontal recess, the air chamber of the supraorbital, the air chamber of the frontal sinus accounted for 32.6% and 43.5%, 23.9% respectively. Conclusion: CT can effectively clarify the anatomical structure of the frontal sinus drainage system and effectively detect various lesions, providing detailed basis for clinical disease diagnosis and surgical treatment.
文摘The method of utilizing rain water has been well developed in foreign countries to realize the sustainable development of water recourse while the method is still at the initial level in China. When considering the increasing of water shortage and urban flood, the awareness of utilizing rain water, as an inevitable trend, has been applied to various engineering technologies. This article has analyzed the principle of conventional road drainage system and the application of artificial wetland technology, also proposed to combine the road drainage system and artificial wetland, as a complex drainage system, to utilize the urban rain water, decrease urban flood pressure, and improve urban micro environment. The calculation principle and method for the complex drainage system are included as well.
文摘The building water supply and drainage system has an important impact and even a decisive role on its service function. Reasonable planning and construction and the construction of a complete water supply and drainage project can improve the comfort level, avoid problems in the subsequent use of the project, improve the fire safety of the building, reduce losses caused by emergencies such as fire and safeguard the safety of lives and property of residents. This paper analyzes the composition and function of the building water supply and drainage system in our country, and on this basis, makes a detailed analysis of the construction technology of the installation project, hoping to play a reference role.
基金supported by the Natural Science Foundation of Beijing(Key Program)No.Z200025(to JHY)+1 种基金the National Natural Science Foundation of China,No.81873818(to LHQ)Supporting Platform Construction Project of Peking University Health Science Center,No.BMU2021ZC011(to JHY).
文摘Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological diseases have been widely explored.The glymphatic system is a fluid drainage and waste clearance pathway that utilizes perivascular space and aquaporin-4 protein located in the astrocyte endfeet to provide a space for exchange of cerebrospinal fluid and interstitial fluid.The intramural periarterial drainage pathway drives the flow of interstitial fluid through the capillary basement membrane and the arterial tunica media.Meningeal lymphatic vessels within the dura mater are involved in the removal of cerebral macromolecules and immune responses.After ischemic stroke,impairment of these systems could lead to cerebral edema,accumulation of toxic factors,and activation of neuroinflammation,while restoration of their normal functions can improve neurological outcomes.In this review,we summarize the basic concepts of these drainage systems,including drainage routes,physiological functions,regulatory mechanisms,and detection technologies.We also focus on the roles of lymphatic drainage systems in brain injury after ischemic stroke,as well as recent advances in therapeutic strategies targeting these drainage systems.These findings provide information for potential novel strategies for treatment of stroke.
基金Acknowledgments This work was supported by the National Nat- ural Science Foundation of China （41172147）, the Anhui Province Science and Technology Research Plan （12010402110）, and the Shanxi Province One Hundred Distinguished Professor Plan project.
文摘The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .
文摘The rain shadow regions requisite a comprehensive watershed development and management plan for sustainable water resources management. The Pambar River Basin （PRB） lies on the rain shadow region of the southern Western Ghats, India, where climate showed marked intra-basin variation. A morphometric analysis was done to evaluate the drainage characteristics of PRB using topographical maps and digital elevation data. PRB was divided into eighteen 4th order basins （SB1-SB18）, distributed along various climatic gradients. Lower order streams mostly dominate PRB and drainage pattern is a function of relief and structure. The terrain is highly dissected and prone to soil erosion during heavy storms and the elongated shape of PRB enables easier flood management. The influence of climate on drainage characteristics was evidently emphasized in basin morphometry. Four distinctively different classes were identified based on the morphometric similarities. The significance of morphometric analysis on the hydrological characterization is discussed and the relevance of the present study in water harvesting has been explicated.
