A distinctive feature of scholarly communities today is exploring topics and concepts in interdisciplinary and international contexts. This observation is increasingly apparent and visible in advancing our thinking an...A distinctive feature of scholarly communities today is exploring topics and concepts in interdisciplinary and international contexts. This observation is increasingly apparent and visible in advancing our thinking and policies related to human/environmental worlds at local, regional, and global scales. Maps are an important part of these innovative and ongoing research approaches. In this context, we consider urban forests a topic meriting more attention of scholars studying the geographic and environmental intersections of the natural sciences with the social sciences and humanities. We construct two innovative knowledge bases, one a conceptual framework based on major themes and concepts related to mapping urban forests using key words of the first 100 results of a Google Scholar query and a second using the number of Google Scholar hyperlinks about mapping urban forests in 244 capital cities. We discovered that the constructed world maps reveal vast global unevenness in our knowledge about urban forests in hyperlink numbers and ratios, results that merit further attention by disciplinary, international and interdisciplinary scholarly communities.展开更多
Non-Darcian flow in rock fractures exhibits significant anisotropic characteristics,which can be affected by mechanical processes,such as cyclic shearing.Understanding the evolution of anisotropic nonDarcian flow is c...Non-Darcian flow in rock fractures exhibits significant anisotropic characteristics,which can be affected by mechanical processes,such as cyclic shearing.Understanding the evolution of anisotropic nonDarcian flow is crucial for characterizing groundwater flow and mass/heat transport in fractured rock masses.In this study,we conducted experiments on non-Darcian flow in single rough fractures under cyclic shearing conditions,aiming to analyze the anisotropic evolution of inertial permeability and viscous permeability.We established quantitative characterization models for the two types of permeability.First,we conducted cyclic shearing experiments on four sets of 24 rough rock fractures,investigating their shear characteristics.Then,we performed 480 non-Darcian flow experiments to analyze the anisotropic evolution of viscous permeability and inertial permeability of these rock fractures.The results showed that viscous permeability exhibited significant differences only in the orthogonal direction,while inertial permeability exhibited differences in both orthogonal and opposite directions.With increase in the shear cycles,the differences in the orthogonal direction gradually increased,while those in opposite direction gradually decreased.Finally,we established characterization equations for the two permeabilities based on the proposed directional geometric parameters and validated the performance of these equations with experimental data.These findings are useful for the quantitative characterization of the evolution of non-Darcian flow in fractures under dynamic loading conditions.展开更多
Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer ...Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer potential of the fracture system in the target reservoir under mining activities remains in suspense.Hence,a coupled thermal-hydraulic-mechanical model was developed for the karst reservoir of Anju coal mine in China,considering non-isothermal convective heat transfer in fractures.This model examined the influence of stress redistribution due to different mining distances(MD)on the effective flow channel length/density and the high/low-aperture fracture distribution.The dynamic heat generation characteristics of the geothermal reservoir were evaluated.Key findings include:Mining-induced stress creates interlaced high-aperture and low-aperture fracture zones below the goaf.Within these interlaced zones,the combined effect of high-and low-aperture fractures restricts the effective flow channel length/density of the fracture network.This contraction of the flow field leads to a significant decline in production flow rate,which consequently reduces both the production flow rate and power as MD increases.This work represents the study of mining disturbances on geothermal production,providing a theoretical foundation for the co-development of coal and geothermal resources.展开更多
The title of the online version of the original article was revised.The title of the original article has been revised to:Hydrochemical characterization of surface waters in Northern Tehran:Integrating cluster-based t...The title of the online version of the original article was revised.The title of the original article has been revised to:Hydrochemical characterization of surface waters in Northern Tehran:Integrating cluster-based techniques with Self-Organizing Maps.展开更多
Water quality is a critical global issue,especially in urban and semi-urban regions where natural and anthropogenic factors significantly influence surface water systems.This study evaluates the hydrochemical characte...Water quality is a critical global issue,especially in urban and semi-urban regions where natural and anthropogenic factors significantly influence surface water systems.This study evaluates the hydrochemical characteristics of surface water in the North of Tehran Rivers(NTRs),an essential water resource in a rapidly urbanizing region,using advanced clustering techniques,including Hierarchical Clustering Analysis(HCA),Fuzzy CMeans(FCM),Genetic Algorithm Fuzzy C-Means(GAFCM),and Self-Organizing Map(SOM).The research aims to address the scientific challenge of understanding spatial and temporal variability in water quality,focusing on physicochemical parameters,hydrochemical facies,and contamination sources.Water samples from six rivers collected over four seasons in 2020 were analyzed and classified into distinct clusters based on their chemical composition,revealing significant seasonal and spatial differences.Results showed that FCM and GAFCM consistently categorized the NTRs into two clusters during winter and spring and three in summer and autumn.These findings were supported by HCA and SOM,which identified clusters corresponding to specific river segments and contamination levels.The primary hydrochemical processes identified were mineral dissolution and weathering,with calcite,dolomite,and aragonite significantly influencing water chemistry.Additionally,human activities,such as wastewater discharge,were shown to contribute to elevated sulfate,nitrate,and phosphate concentrations,further corroborated by microbial analyses.By integrating HCA,FCM,and GAFCM with an artificial neural network(ANN)-based clustering method(SOM),this study provides a robust framework for evaluating surface water quality.The findings,supported by Gibbs diagrams,Hounslow ion ratio,and saturation indices,highlight the dominance of rock weathering and human impacts in shaping the hydrochemical dynamics of the NTRs.These insights contribute to the scientific understanding of water quality dynamics and offer practical guidance for sustainable water resource management and environmental protection in developing urban areas.展开更多
Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective appro...Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.展开更多
In recent years, climate change has emerged as one of the most pressing environmental issues globally. Morocco, like many other countries, has been significantly affected by these changes, particularly over the past d...In recent years, climate change has emerged as one of the most pressing environmental issues globally. Morocco, like many other countries, has been significantly affected by these changes, particularly over the past decade. In this context, we aim to examine the spatial and temporal distribution of rainfall as a hydrological indicator to understand its impact on the hydrological dynamics of the upper Oum Er-Rbia basin. The Oum Er-Rbia basin is one of the largest watersheds in Morocco in terms of water resources, after the Sebou basin. Besides, the studied area covers an area of 6965 km2. The altitudes are between 2410 m and 415 m. Oum Er-Rbia river takes its source from the Middle Atlas at 2400 m altitude and crosses the Middle Atlas range, the Tadla plain. It shows diversity in relief with diverse structural forms. It is fed by several permanent and seasonal tributaries. The present study consists of analyzing the variations of rainfall events through a statistical analysis of rainfall data provided by the reference stations in the Upper Oum Erbia basin for a chronicle of (1934-2023), and spatializing the precipitation at different scales, annual and monthly, through the rainfall data, provided by 33 rainfall stations, with a chronicle of 30 years, inter-station period (1984-2013). From a methodological point of view, this study places us within a palette of concepts of spatialization that are said to be normative or traditional and are part of the set of methods existing in the field of spatialization. The main objective of this paper is to extract all the information that can inform us about the rainfall characteristics of this period, to determine the rainfall trends and to identify the spatial and temporal rainfall distributions. All this is in order to follow, understand and determine the nature of the impact of climate variability on the hydrological functioning in the upper basin of Oum Er-Rbia.展开更多
The impact of normal stress-induced closure on fluid flow and solute transport in a single rock fracture is demonstrated in this study.The fracture is created from a measured surface of a granite rock sample.The Bandi...The impact of normal stress-induced closure on fluid flow and solute transport in a single rock fracture is demonstrated in this study.The fracture is created from a measured surface of a granite rock sample.The Bandis model is used to calculate the fracture closure due to normal stress,and the fluid flow is simulated by solving the Reynold equation.The Lagrangian particle tracking method is applied to modeling the advective transport in the fracture.The results show that the normal stress significantly affects fluid flow and solute transport in rock fractures.It causes fracture closure and creates asperity contact areas,which significantly reduces the effective hydraulic aperture and enhances flow channeling.Consequently,the reduced aperture and enhanced channeling affect travel time distributions.In particular,the enhanced channeling results in enhanced first arriving and tailing behaviors for solute transport.The fracture normal stiffness correlates linearly with the 5th and 95th percentiles of the normalized travel time.The finding from this study may help to better understand the stress-dependent solute transport processes in natural rock fractures.展开更多
Solutions for radial flow of a Bingham fluid are analyzed in this paper.It aims to eliminate confusions in the literature concerning the plug flow region in different solutions for analysis and design of grouting in r...Solutions for radial flow of a Bingham fluid are analyzed in this paper.It aims to eliminate confusions in the literature concerning the plug flow region in different solutions for analysis and design of grouting in rock fractures.The analyses based on the force balance equation reveal that the plug flow region in Bingham radial flow is independent of the fracture radius,and is not a growth function adapted from the solution of one-dimensional(1D)slit flow according to‘similarity’.Based on the shear stress distribution,we analytically proposed that a non-uniform plug flow region cannot exist.The Bingham fluid(grout)penetration and flowrate evolution as functions of grouting time are given using the correct expression for the plug flow region.The radius-independent plug flow region and the presented flowrate evolution equation are also verified numerically.For radial flow,the relative penetration length is equal to the relative width of plug flow region,which is the same as that for 1D channel flow.Discrepancies in analytical solutions for grout penetration and flowrate evolution were also illustrated.The clarification of the plug flow region and evaluation of discrepancies in analytical solutions presented in this work could simplify modeling and design of grouting in rock engineering applications.展开更多
Water inrush is one of the most dangerous disasters in coal mining.Due to the large-scale mining and complicated hydrogeological conditions,thousands of deaths and huge economic losses have been caused by water inrush...Water inrush is one of the most dangerous disasters in coal mining.Due to the large-scale mining and complicated hydrogeological conditions,thousands of deaths and huge economic losses have been caused by water inrush disasters in China.There are two main factors determining the occurrence of water inrush:water source and water-conducting pathway.Research on the formation mechanism of the water-conducting pathway is the main direction to prevent and control the water inrush,and the seepage mechanism of rock mass during the formation of the water-conducting pathway is the key for the research on the water inrush mechanism.This paper provides a state-of-the-art review of seepage mechanisms during water inrush from three aspects,i.e.,mechanisms of stress-seepage coupling,fow regime transformation and rock erosion.Through numerical methods and experimental analysis,the evolution law of stress and seepage felds in the process of water inrush is fully studied;the fuid movement characteristics under diferent fow regimes are clearly summarized;the law of particle initiation and migration in the process of water inrush is explored,and the efect of rock erosion on hydraulic and mechanical properties of the rock media is also studied.Finally,some limitations of current research are analyzed,and the suggestions for future research on water inrush are proposed in this review.展开更多
Recently, drones have found applicability in a variety of study fields, one of these being forestry, where an increasing interest is given to this segment of technology, especially due to the high-resolution data that...Recently, drones have found applicability in a variety of study fields, one of these being forestry, where an increasing interest is given to this segment of technology, especially due to the high-resolution data that can be collected flexibly in a short time and at a relatively low price. Also, drones have an important role in filling the gaps of common data collected using manned aircraft or satellite remote sensing, while having many advantages both in research and in various practical applications particularly in forestry as well as in land use in general. This paper aims to briefly describe the different approaches of applications of UAVs （Unmanned Aircraft Vehicles） in forestry, such as forest mapping, forest management planning, canopy height model creation or mapping forest gaps. These approaches have great potential in the near future applications and their quick implementation in a variety of situations is desirable for the sustainable management of forests.展开更多
Recently,Hoang et al.(2021)discussed our paper Zou et al.(2020).In our paper,we made a statement that Dai and Bird(1981)’s solution for two-dimensional(2 D)radial Bingham fluid flow between parallel plates violates m...Recently,Hoang et al.(2021)discussed our paper Zou et al.(2020).In our paper,we made a statement that Dai and Bird(1981)’s solution for two-dimensional(2 D)radial Bingham fluid flow between parallel plates violates mass balance.Hoang et al.pointed out that Dai and Bird(1981)’s solution does not violate the mass balance because Dai and Bird(1981)’s solution and our analysis are based on different assumptions,i.e.with consideration of the vertical velocity component in the continuity equation or not,which leads to two different approximation models.In this sense,the mass balance of Dai and Bird(1981)’s solution should not be checked using our solution as a reference.In this reply,we add remarks on the two approximation models and their implication for rock grouting analysis.The discussion by Hoang et al.and this reply are helpful to thoroughly eliminate the existing confusion regarding the two solutions in the rock grouting research community.展开更多
Inappropriate management of municipal solid waste dumpsites is a major cause of groundwater contamination in developing countries,but the extent of the problem is not known.This study investigated groundwater quality ...Inappropriate management of municipal solid waste dumpsites is a major cause of groundwater contamination in developing countries,but the extent of the problem is not known.This study investigated groundwater quality in the vicinity of Olusosun dumpsite in Lagos,Nigeria,the most populous city in sub-Saharan Africa.During 2020,monthly groundwater samples were collected in 17 wells and boreholes used as drinking water sources,and analysed for 20 physico-chemical parameters.Differences between sites and seasons were statistically assessed,together with changes in water quality index(WQI).The results indicated that heavy metals(Pb^(2+),Ni^(+),Mn^(2+),Fe^(2+),Cr^(6+)),cations(Ca^(2+),Mg^(2+),K^(+)),total hardness and pH were the main parameters impairing water quality.Drinking water quality standards from both the World Health Organization and Nigeria government were exceeded more often in the wet season than in the dry season.Some groundwater properties were negatively correlated with distance to dumpsite(e.g.,Fe^(2+),Pb^(2+),NO_(3)^(−)).Significant differences between sites were identified,but with no clear spatial trend.WQI varied from excellent(6%-24%of the sites over the study period)to unsuitable for drinking water purposes(12%-18%),with good quality prevailing at most sites(35%-47%).Although groundwater quality declined at 24%of the sites over 2020,the results indicated improvements compared with previous decades.Remediation strategies must be implemented to safeguard public health and the sustainability of water resources.展开更多
Environmental degradation is a burning issue in Bangladesh. The degradation process is extremely acute in the north-western part of Bangladesh due to many environmental and anthropogenic reasons. However, initiative o...Environmental degradation is a burning issue in Bangladesh. The degradation process is extremely acute in the north-western part of Bangladesh due to many environmental and anthropogenic reasons. However, initiative of research work on this issue is very crucial and urgent for regional and local planning and management. In this paper, Nachole and Niamotpur Upazilas were considered as the study area to identify and quantify environmental degradation using an integrated Geographic Information System (GIS) and Remote Sensing (RS) technique. The results of the study reveal that the area is one of the most vulnerable areas in terms of land degradation that already affected local agriculture, biodiversity, water supply and overall socio-economic livelihoods. From the modelling results, about 66,301 hectares (90%) of land are vulnerable to land degradation, of which 24,736, 40,309 and 256 hectares of land were classified as severely, highly, and moderately vulnerable areas respectively. The overall image classification accuracy for all the resultant images was 95.40% while kappa coefficient was 0.94.展开更多
River bank erosion is one of the frequent but the most unpredictable disasters that occur every year in Bangladesh. In this paper, Landsat TM-5 and Landsat-8 imageries from 1989 and 2015 were used to detect changes of...River bank erosion is one of the frequent but the most unpredictable disasters that occur every year in Bangladesh. In this paper, Landsat TM-5 and Landsat-8 imageries from 1989 and 2015 were used to detect changes of present land use, river erosion and bar deposition in Chowhali Upazila, Sirajganj district of Bangladesh. This study reveals that human settlement, forest, seasonal crops and agriculture features decrease, while river coverage increases dramatically. About 1340 hectare areas have been eroded, while 630 hectares are deposited as channel bar in the study area over the last 26 years. Finally, an accuracy assessment is conducted between the test data and each land use feature. The overall classification accuracy was 97% and 98% in 1989 and 2015 respectively. Moreover, 98% accuracy is found in erosion while 97% is found in bar deposition areas.展开更多
The management of municipal solid waste (MSW) has become a matter of great concern. As a result of this, there have been strenuous efforts at all levels geared towards addressing this menace. Although there are severa...The management of municipal solid waste (MSW) has become a matter of great concern. As a result of this, there have been strenuous efforts at all levels geared towards addressing this menace. Although there are several methods of disposing of waste, landfills remain one of the outstanding management systems in dealing with the growing quantum of generated municipal solid waste. This study assessed the consequence of poor landfill management from the perspective of the Gbalahi landfill in the Sagnarigu Municipality in Northern Ghana. The study employed interviews to gather information from 103 households. The acquired data was supported by some secondary data from the site management and the municipal environmental unit. The study revealed that poor management of the facility has led to the breakdown of some major components of the facility. It was also noted that the site poses a threat to the health of the nearby communities owing to the uncontrolled dust, smoke, and activities of vermin as well as scavengers. The study concludes<span style="font-family:;" "=""> </span><span style="font-family:;" "="">the Ghalahi landfill in its current state remains a threat to the health of the inhabitants of the area. Poor management of equipment and failur<span>e to adhere to best practices has exacerbated conditions of their opera</span>tion putting the health of the people in danger. Regular monitoring of the site by the EPA and the local government authorities can help reduce </span><span style="font-family:;" "="">the </span><span style="font-family:;" "="">risk of exposure on the nearby communities.</span>展开更多
In automobile engines,it is commonly known that the proper removal of the excess heat,resulting from internal combustion,is of high significance in the prevention of numerous negative consequences.In this regard,the r...In automobile engines,it is commonly known that the proper removal of the excess heat,resulting from internal combustion,is of high significance in the prevention of numerous negative consequences.In this regard,the radiator has a pivotal role as the main component of the engine’s cooling system.Hence,its design and analysis are highly important,requiring more comprehensive failure and flow investigations.In this work,a Scania radiator is examined under the thermal and mechanical loads,followed by its analysis under the combined thermomechanical loading.Then,the flow characteristics,including the velocity,pressure,and enthalpy,are studied.In this regard,PTC-Creo software is utilized.The results demonstrate that thermal stress causes seven times more displacement than a mechanical one.When they are combined,this value reaches 1.5 mm.Also,the maximum failure index value of the Tresca theory is around 4.58,observed at the inlet side of the radiator.Besides,this paper indicates that the PTC-Creo can be considered a reliable and economical tool for the simulation of industrial applications,such as the considered radiator of a heavy-duty cooling system.展开更多
In this work,a typical vehicle engine is modeled within PTC-Creo software,and its thermal,mechanical,and thermo-mechanical performance are evaluated.This is followed by the vibrational,fatigue,and buckling analy...In this work,a typical vehicle engine is modeled within PTC-Creo software,and its thermal,mechanical,and thermo-mechanical performance are evaluated.This is followed by the vibrational,fatigue,and buckling analysis of the assembly of components,which are the predominant failure causes.The results show that the least temperature gradient occurs in the center of the pin,which connects the piston to the connecting rod,the maximum displacement is seen just below the piston head,and the thermo-mechanical failure is caused mostly(about 85%)by the mechanical load rather than the thermal one.Also,in fatigue analysis,the minimum and maximum values for the safety factor are 0.63 and 5,respectively.The results can prevent the reoccurrence of similar failures and help the enhancement of the components’design and manufacturing process.展开更多
Obtaining a comprehensive understanding of solute transport in fractured rocks is crucial for various geoengineering applications,including waste disposal and construction of geo-energy infrastructure.It was realized ...Obtaining a comprehensive understanding of solute transport in fractured rocks is crucial for various geoengineering applications,including waste disposal and construction of geo-energy infrastructure.It was realized that solute transport in fractured rocks is con-trolled by stochastic discrete fracture-matrix systems.However,the impacts and specific uncertainty caused by fracture network struc-tures on solute transport in discrete fracture-matrix systems have yet not been fully understood.In this article,we aim to investigate the influence of fracture network structure on solute transport in stochastic discrete fracture-matrix systems.The fluid flow and solute trans-port are simulated using a three-dimensional discrete fracture matrix model with considering various values of fracture density and size(i.e.,radius).The obtained results reveal that as the fracture density or minimum fracture radius increases,the corresponding fluid flow and solute transport channels increase,and the solute concentration distribution range expands in the matrix.This phenomenon,attrib-uted to the enhanced connectivity of the fracture network,leads to a rise in the effluent solute concentration mean value from 0.422 to 0.704,or from 0.496 to 0.689.Furthermore,when solute transport reached a steady state,the coefficient of variation of effluent concen-tration decreases with the increasing fracture density or minimum fracture radius in different scenarios,indicating an improvement in the homogeneity of solute transport results.The presented analysis results of solute transport in stochastic discrete fracture-matrix systems can be helpful for uncertainty management in the geological disposal of high-level radioactive waste.展开更多
Safe disposal of high-level radioactive nuclear waste(HLW)is crucial for human health and the environment,as well as for sustainable development.Deep geological disposal in sparsely fractured crystalline rock is consi...Safe disposal of high-level radioactive nuclear waste(HLW)is crucial for human health and the environment,as well as for sustainable development.Deep geological disposal in sparsely fractured crystalline rock is considered one of the most favorable methods for final disposal of HLW.Extensive research has been conducted worldwide and many countries have initiated their own national development programs for deep geological disposal.Significant advancements of national programs for deep geological disposal of HLW in crystalline rock have been achieved in Sweden and Finland,which are currently under site development stage,focusing on detailed site characterization,repository construction,and post-closure safety analysis.Continued research and development remain important in the site development stage to ensure long-term safety of the HLW disposal repository.This work presents an overview and discussion of the progress as well as remaining open scientific issues and possibilities related to site development for safe disposal of HLW in crystalline rock.We emphasize that developing a comprehensive and convergent understanding of the coupled thermal,hydraulic,mechanical,chemical and biological(THMCB)processes in fractured crystalline rock remains the most important yet challenging topic for future studies towards safe disposal of HLW in crystalline rock.Advancements in laboratory facilities/techniques and computational models,as well as available comprehensive field data from site developments,provide new opportunities to enhance our understanding of the coupled processes and thereby repository design for safe geological disposal of HLW in crystalline rock.展开更多
文摘A distinctive feature of scholarly communities today is exploring topics and concepts in interdisciplinary and international contexts. This observation is increasingly apparent and visible in advancing our thinking and policies related to human/environmental worlds at local, regional, and global scales. Maps are an important part of these innovative and ongoing research approaches. In this context, we consider urban forests a topic meriting more attention of scholars studying the geographic and environmental intersections of the natural sciences with the social sciences and humanities. We construct two innovative knowledge bases, one a conceptual framework based on major themes and concepts related to mapping urban forests using key words of the first 100 results of a Google Scholar query and a second using the number of Google Scholar hyperlinks about mapping urban forests in 244 capital cities. We discovered that the constructed world maps reveal vast global unevenness in our knowledge about urban forests in hyperlink numbers and ratios, results that merit further attention by disciplinary, international and interdisciplinary scholarly communities.
基金supported by the National Natural Science Foundation of China(Grant No.42202316)the China Postdoctoral Science Foundation(Grant No.2022M712963)the Open Fund of Badong National Observation and Research Station of Geohazards(Grant No.BNORSG-202309).
文摘Non-Darcian flow in rock fractures exhibits significant anisotropic characteristics,which can be affected by mechanical processes,such as cyclic shearing.Understanding the evolution of anisotropic nonDarcian flow is crucial for characterizing groundwater flow and mass/heat transport in fractured rock masses.In this study,we conducted experiments on non-Darcian flow in single rough fractures under cyclic shearing conditions,aiming to analyze the anisotropic evolution of inertial permeability and viscous permeability.We established quantitative characterization models for the two types of permeability.First,we conducted cyclic shearing experiments on four sets of 24 rough rock fractures,investigating their shear characteristics.Then,we performed 480 non-Darcian flow experiments to analyze the anisotropic evolution of viscous permeability and inertial permeability of these rock fractures.The results showed that viscous permeability exhibited significant differences only in the orthogonal direction,while inertial permeability exhibited differences in both orthogonal and opposite directions.With increase in the shear cycles,the differences in the orthogonal direction gradually increased,while those in opposite direction gradually decreased.Finally,we established characterization equations for the two permeabilities based on the proposed directional geometric parameters and validated the performance of these equations with experimental data.These findings are useful for the quantitative characterization of the evolution of non-Darcian flow in fractures under dynamic loading conditions.
基金supported by the National Natural Science Foundation of China(Nos.U23B2091,52304104,and 52404157)the National Key R&D Program of China(No.2022YFC2905600)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZB20240825).
文摘Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer potential of the fracture system in the target reservoir under mining activities remains in suspense.Hence,a coupled thermal-hydraulic-mechanical model was developed for the karst reservoir of Anju coal mine in China,considering non-isothermal convective heat transfer in fractures.This model examined the influence of stress redistribution due to different mining distances(MD)on the effective flow channel length/density and the high/low-aperture fracture distribution.The dynamic heat generation characteristics of the geothermal reservoir were evaluated.Key findings include:Mining-induced stress creates interlaced high-aperture and low-aperture fracture zones below the goaf.Within these interlaced zones,the combined effect of high-and low-aperture fractures restricts the effective flow channel length/density of the fracture network.This contraction of the flow field leads to a significant decline in production flow rate,which consequently reduces both the production flow rate and power as MD increases.This work represents the study of mining disturbances on geothermal production,providing a theoretical foundation for the co-development of coal and geothermal resources.
文摘The title of the online version of the original article was revised.The title of the original article has been revised to:Hydrochemical characterization of surface waters in Northern Tehran:Integrating cluster-based techniques with Self-Organizing Maps.
文摘Water quality is a critical global issue,especially in urban and semi-urban regions where natural and anthropogenic factors significantly influence surface water systems.This study evaluates the hydrochemical characteristics of surface water in the North of Tehran Rivers(NTRs),an essential water resource in a rapidly urbanizing region,using advanced clustering techniques,including Hierarchical Clustering Analysis(HCA),Fuzzy CMeans(FCM),Genetic Algorithm Fuzzy C-Means(GAFCM),and Self-Organizing Map(SOM).The research aims to address the scientific challenge of understanding spatial and temporal variability in water quality,focusing on physicochemical parameters,hydrochemical facies,and contamination sources.Water samples from six rivers collected over four seasons in 2020 were analyzed and classified into distinct clusters based on their chemical composition,revealing significant seasonal and spatial differences.Results showed that FCM and GAFCM consistently categorized the NTRs into two clusters during winter and spring and three in summer and autumn.These findings were supported by HCA and SOM,which identified clusters corresponding to specific river segments and contamination levels.The primary hydrochemical processes identified were mineral dissolution and weathering,with calcite,dolomite,and aragonite significantly influencing water chemistry.Additionally,human activities,such as wastewater discharge,were shown to contribute to elevated sulfate,nitrate,and phosphate concentrations,further corroborated by microbial analyses.By integrating HCA,FCM,and GAFCM with an artificial neural network(ANN)-based clustering method(SOM),this study provides a robust framework for evaluating surface water quality.The findings,supported by Gibbs diagrams,Hounslow ion ratio,and saturation indices,highlight the dominance of rock weathering and human impacts in shaping the hydrochemical dynamics of the NTRs.These insights contribute to the scientific understanding of water quality dynamics and offer practical guidance for sustainable water resource management and environmental protection in developing urban areas.
基金supported by the National Natural Science Foundation of China(32301453 and 3272675)the China Postdoctoral Science Foundation(2023M730682)。
文摘Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.
文摘In recent years, climate change has emerged as one of the most pressing environmental issues globally. Morocco, like many other countries, has been significantly affected by these changes, particularly over the past decade. In this context, we aim to examine the spatial and temporal distribution of rainfall as a hydrological indicator to understand its impact on the hydrological dynamics of the upper Oum Er-Rbia basin. The Oum Er-Rbia basin is one of the largest watersheds in Morocco in terms of water resources, after the Sebou basin. Besides, the studied area covers an area of 6965 km2. The altitudes are between 2410 m and 415 m. Oum Er-Rbia river takes its source from the Middle Atlas at 2400 m altitude and crosses the Middle Atlas range, the Tadla plain. It shows diversity in relief with diverse structural forms. It is fed by several permanent and seasonal tributaries. The present study consists of analyzing the variations of rainfall events through a statistical analysis of rainfall data provided by the reference stations in the Upper Oum Erbia basin for a chronicle of (1934-2023), and spatializing the precipitation at different scales, annual and monthly, through the rainfall data, provided by 33 rainfall stations, with a chronicle of 30 years, inter-station period (1984-2013). From a methodological point of view, this study places us within a palette of concepts of spatialization that are said to be normative or traditional and are part of the set of methods existing in the field of spatialization. The main objective of this paper is to extract all the information that can inform us about the rainfall characteristics of this period, to determine the rainfall trends and to identify the spatial and temporal rainfall distributions. All this is in order to follow, understand and determine the nature of the impact of climate variability on the hydrological functioning in the upper basin of Oum Er-Rbia.
基金funding provided by the Swedish Nuclear Fuel and Waste Management Co.(SKB)。
文摘The impact of normal stress-induced closure on fluid flow and solute transport in a single rock fracture is demonstrated in this study.The fracture is created from a measured surface of a granite rock sample.The Bandis model is used to calculate the fracture closure due to normal stress,and the fluid flow is simulated by solving the Reynold equation.The Lagrangian particle tracking method is applied to modeling the advective transport in the fracture.The results show that the normal stress significantly affects fluid flow and solute transport in rock fractures.It causes fracture closure and creates asperity contact areas,which significantly reduces the effective hydraulic aperture and enhances flow channeling.Consequently,the reduced aperture and enhanced channeling affect travel time distributions.In particular,the enhanced channeling results in enhanced first arriving and tailing behaviors for solute transport.The fracture normal stiffness correlates linearly with the 5th and 95th percentiles of the normalized travel time.The finding from this study may help to better understand the stress-dependent solute transport processes in natural rock fractures.
基金funding for this study is provided by the BeFo Rock Engineering Research Foundation(Grant No.392)。
文摘Solutions for radial flow of a Bingham fluid are analyzed in this paper.It aims to eliminate confusions in the literature concerning the plug flow region in different solutions for analysis and design of grouting in rock fractures.The analyses based on the force balance equation reveal that the plug flow region in Bingham radial flow is independent of the fracture radius,and is not a growth function adapted from the solution of one-dimensional(1D)slit flow according to‘similarity’.Based on the shear stress distribution,we analytically proposed that a non-uniform plug flow region cannot exist.The Bingham fluid(grout)penetration and flowrate evolution as functions of grouting time are given using the correct expression for the plug flow region.The radius-independent plug flow region and the presented flowrate evolution equation are also verified numerically.For radial flow,the relative penetration length is equal to the relative width of plug flow region,which is the same as that for 1D channel flow.Discrepancies in analytical solutions for grout penetration and flowrate evolution were also illustrated.The clarification of the plug flow region and evaluation of discrepancies in analytical solutions presented in this work could simplify modeling and design of grouting in rock engineering applications.
基金supported by the National Science Foundation for Excellent Young researchers of China(52122404)the National Natural Science Foundation of China(41977238)the Fundamental Research Funds for the Central Universities(2021GJZPY14 and 2021YCPY0101).
文摘Water inrush is one of the most dangerous disasters in coal mining.Due to the large-scale mining and complicated hydrogeological conditions,thousands of deaths and huge economic losses have been caused by water inrush disasters in China.There are two main factors determining the occurrence of water inrush:water source and water-conducting pathway.Research on the formation mechanism of the water-conducting pathway is the main direction to prevent and control the water inrush,and the seepage mechanism of rock mass during the formation of the water-conducting pathway is the key for the research on the water inrush mechanism.This paper provides a state-of-the-art review of seepage mechanisms during water inrush from three aspects,i.e.,mechanisms of stress-seepage coupling,fow regime transformation and rock erosion.Through numerical methods and experimental analysis,the evolution law of stress and seepage felds in the process of water inrush is fully studied;the fuid movement characteristics under diferent fow regimes are clearly summarized;the law of particle initiation and migration in the process of water inrush is explored,and the efect of rock erosion on hydraulic and mechanical properties of the rock media is also studied.Finally,some limitations of current research are analyzed,and the suggestions for future research on water inrush are proposed in this review.
文摘Recently, drones have found applicability in a variety of study fields, one of these being forestry, where an increasing interest is given to this segment of technology, especially due to the high-resolution data that can be collected flexibly in a short time and at a relatively low price. Also, drones have an important role in filling the gaps of common data collected using manned aircraft or satellite remote sensing, while having many advantages both in research and in various practical applications particularly in forestry as well as in land use in general. This paper aims to briefly describe the different approaches of applications of UAVs （Unmanned Aircraft Vehicles） in forestry, such as forest mapping, forest management planning, canopy height model creation or mapping forest gaps. These approaches have great potential in the near future applications and their quick implementation in a variety of situations is desirable for the sustainable management of forests.
文摘Recently,Hoang et al.(2021)discussed our paper Zou et al.(2020).In our paper,we made a statement that Dai and Bird(1981)’s solution for two-dimensional(2 D)radial Bingham fluid flow between parallel plates violates mass balance.Hoang et al.pointed out that Dai and Bird(1981)’s solution does not violate the mass balance because Dai and Bird(1981)’s solution and our analysis are based on different assumptions,i.e.with consideration of the vertical velocity component in the continuity equation or not,which leads to two different approximation models.In this sense,the mass balance of Dai and Bird(1981)’s solution should not be checked using our solution as a reference.In this reply,we add remarks on the two approximation models and their implication for rock grouting analysis.The discussion by Hoang et al.and this reply are helpful to thoroughly eliminate the existing confusion regarding the two solutions in the rock grouting research community.
文摘Inappropriate management of municipal solid waste dumpsites is a major cause of groundwater contamination in developing countries,but the extent of the problem is not known.This study investigated groundwater quality in the vicinity of Olusosun dumpsite in Lagos,Nigeria,the most populous city in sub-Saharan Africa.During 2020,monthly groundwater samples were collected in 17 wells and boreholes used as drinking water sources,and analysed for 20 physico-chemical parameters.Differences between sites and seasons were statistically assessed,together with changes in water quality index(WQI).The results indicated that heavy metals(Pb^(2+),Ni^(+),Mn^(2+),Fe^(2+),Cr^(6+)),cations(Ca^(2+),Mg^(2+),K^(+)),total hardness and pH were the main parameters impairing water quality.Drinking water quality standards from both the World Health Organization and Nigeria government were exceeded more often in the wet season than in the dry season.Some groundwater properties were negatively correlated with distance to dumpsite(e.g.,Fe^(2+),Pb^(2+),NO_(3)^(−)).Significant differences between sites were identified,but with no clear spatial trend.WQI varied from excellent(6%-24%of the sites over the study period)to unsuitable for drinking water purposes(12%-18%),with good quality prevailing at most sites(35%-47%).Although groundwater quality declined at 24%of the sites over 2020,the results indicated improvements compared with previous decades.Remediation strategies must be implemented to safeguard public health and the sustainability of water resources.
文摘Environmental degradation is a burning issue in Bangladesh. The degradation process is extremely acute in the north-western part of Bangladesh due to many environmental and anthropogenic reasons. However, initiative of research work on this issue is very crucial and urgent for regional and local planning and management. In this paper, Nachole and Niamotpur Upazilas were considered as the study area to identify and quantify environmental degradation using an integrated Geographic Information System (GIS) and Remote Sensing (RS) technique. The results of the study reveal that the area is one of the most vulnerable areas in terms of land degradation that already affected local agriculture, biodiversity, water supply and overall socio-economic livelihoods. From the modelling results, about 66,301 hectares (90%) of land are vulnerable to land degradation, of which 24,736, 40,309 and 256 hectares of land were classified as severely, highly, and moderately vulnerable areas respectively. The overall image classification accuracy for all the resultant images was 95.40% while kappa coefficient was 0.94.
文摘River bank erosion is one of the frequent but the most unpredictable disasters that occur every year in Bangladesh. In this paper, Landsat TM-5 and Landsat-8 imageries from 1989 and 2015 were used to detect changes of present land use, river erosion and bar deposition in Chowhali Upazila, Sirajganj district of Bangladesh. This study reveals that human settlement, forest, seasonal crops and agriculture features decrease, while river coverage increases dramatically. About 1340 hectare areas have been eroded, while 630 hectares are deposited as channel bar in the study area over the last 26 years. Finally, an accuracy assessment is conducted between the test data and each land use feature. The overall classification accuracy was 97% and 98% in 1989 and 2015 respectively. Moreover, 98% accuracy is found in erosion while 97% is found in bar deposition areas.
文摘The management of municipal solid waste (MSW) has become a matter of great concern. As a result of this, there have been strenuous efforts at all levels geared towards addressing this menace. Although there are several methods of disposing of waste, landfills remain one of the outstanding management systems in dealing with the growing quantum of generated municipal solid waste. This study assessed the consequence of poor landfill management from the perspective of the Gbalahi landfill in the Sagnarigu Municipality in Northern Ghana. The study employed interviews to gather information from 103 households. The acquired data was supported by some secondary data from the site management and the municipal environmental unit. The study revealed that poor management of the facility has led to the breakdown of some major components of the facility. It was also noted that the site poses a threat to the health of the nearby communities owing to the uncontrolled dust, smoke, and activities of vermin as well as scavengers. The study concludes<span style="font-family:;" "=""> </span><span style="font-family:;" "="">the Ghalahi landfill in its current state remains a threat to the health of the inhabitants of the area. Poor management of equipment and failur<span>e to adhere to best practices has exacerbated conditions of their opera</span>tion putting the health of the people in danger. Regular monitoring of the site by the EPA and the local government authorities can help reduce </span><span style="font-family:;" "="">the </span><span style="font-family:;" "="">risk of exposure on the nearby communities.</span>
文摘In automobile engines,it is commonly known that the proper removal of the excess heat,resulting from internal combustion,is of high significance in the prevention of numerous negative consequences.In this regard,the radiator has a pivotal role as the main component of the engine’s cooling system.Hence,its design and analysis are highly important,requiring more comprehensive failure and flow investigations.In this work,a Scania radiator is examined under the thermal and mechanical loads,followed by its analysis under the combined thermomechanical loading.Then,the flow characteristics,including the velocity,pressure,and enthalpy,are studied.In this regard,PTC-Creo software is utilized.The results demonstrate that thermal stress causes seven times more displacement than a mechanical one.When they are combined,this value reaches 1.5 mm.Also,the maximum failure index value of the Tresca theory is around 4.58,observed at the inlet side of the radiator.Besides,this paper indicates that the PTC-Creo can be considered a reliable and economical tool for the simulation of industrial applications,such as the considered radiator of a heavy-duty cooling system.
文摘In this work,a typical vehicle engine is modeled within PTC-Creo software,and its thermal,mechanical,and thermo-mechanical performance are evaluated.This is followed by the vibrational,fatigue,and buckling analysis of the assembly of components,which are the predominant failure causes.The results show that the least temperature gradient occurs in the center of the pin,which connects the piston to the connecting rod,the maximum displacement is seen just below the piston head,and the thermo-mechanical failure is caused mostly(about 85%)by the mechanical load rather than the thermal one.Also,in fatigue analysis,the minimum and maximum values for the safety factor are 0.63 and 5,respectively.The results can prevent the reoccurrence of similar failures and help the enhancement of the components’design and manufacturing process.
基金support from research grants provided by the National Natural Science Foundation of China(Grant Nos.42302303 and 42277128)the Zhejiang Provincial Natural Science Foundation of China(Grant No.ZCLQ24D0201).
文摘Obtaining a comprehensive understanding of solute transport in fractured rocks is crucial for various geoengineering applications,including waste disposal and construction of geo-energy infrastructure.It was realized that solute transport in fractured rocks is con-trolled by stochastic discrete fracture-matrix systems.However,the impacts and specific uncertainty caused by fracture network struc-tures on solute transport in discrete fracture-matrix systems have yet not been fully understood.In this article,we aim to investigate the influence of fracture network structure on solute transport in stochastic discrete fracture-matrix systems.The fluid flow and solute trans-port are simulated using a three-dimensional discrete fracture matrix model with considering various values of fracture density and size(i.e.,radius).The obtained results reveal that as the fracture density or minimum fracture radius increases,the corresponding fluid flow and solute transport channels increase,and the solute concentration distribution range expands in the matrix.This phenomenon,attrib-uted to the enhanced connectivity of the fracture network,leads to a rise in the effluent solute concentration mean value from 0.422 to 0.704,or from 0.496 to 0.689.Furthermore,when solute transport reached a steady state,the coefficient of variation of effluent concen-tration decreases with the increasing fracture density or minimum fracture radius in different scenarios,indicating an improvement in the homogeneity of solute transport results.The presented analysis results of solute transport in stochastic discrete fracture-matrix systems can be helpful for uncertainty management in the geological disposal of high-level radioactive waste.
文摘Safe disposal of high-level radioactive nuclear waste(HLW)is crucial for human health and the environment,as well as for sustainable development.Deep geological disposal in sparsely fractured crystalline rock is considered one of the most favorable methods for final disposal of HLW.Extensive research has been conducted worldwide and many countries have initiated their own national development programs for deep geological disposal.Significant advancements of national programs for deep geological disposal of HLW in crystalline rock have been achieved in Sweden and Finland,which are currently under site development stage,focusing on detailed site characterization,repository construction,and post-closure safety analysis.Continued research and development remain important in the site development stage to ensure long-term safety of the HLW disposal repository.This work presents an overview and discussion of the progress as well as remaining open scientific issues and possibilities related to site development for safe disposal of HLW in crystalline rock.We emphasize that developing a comprehensive and convergent understanding of the coupled thermal,hydraulic,mechanical,chemical and biological(THMCB)processes in fractured crystalline rock remains the most important yet challenging topic for future studies towards safe disposal of HLW in crystalline rock.Advancements in laboratory facilities/techniques and computational models,as well as available comprehensive field data from site developments,provide new opportunities to enhance our understanding of the coupled processes and thereby repository design for safe geological disposal of HLW in crystalline rock.
