Mine waste debris flows continue to occur in China, and the disaster prevention and mitigation of these flows faces severe challenges since the mechanisms determining erosion and transport of mine waste along gullies ...Mine waste debris flows continue to occur in China, and the disaster prevention and mitigation of these flows faces severe challenges since the mechanisms determining erosion and transport of mine waste along gullies are not yet fully understood. The erosion and delivery process of mine waste heaps was reproduced through flume experiments with the method based on field survey data of the Daxicha mine waste debris flow gully in the Xiaoqinling gold mining area. The results showed that the erosion and movement of mine wastes could be divided into three modes: minimal sediment movement, sediment sorting and delivery, and a large amount of sediment transfer. Moreover, there was an obvious amplification effect on peak discharge along with the formation and failure of temporary landslide dams during the erosion process. The correlation between the coefficient of peak discharge amplification and three dimensionless influencing factors, flume gradient, dimensionless volume, and dimensionless particle size, were comprehensively analyzed. An empirical formula for the coefficient of peak discharge amplification was proposed and verified based on 16 sets of experimental data. These preliminary results can provide a scientific reference for future research on disaster prevention and mitigation of mine waste debris flows.展开更多
This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experi...This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).展开更多
The sustainability of a city depends on the effective and efficient management of its solid waste. Waste recycling channels mainly process glass bottles for direct reuse. Some of these sectors carry out the crushing a...The sustainability of a city depends on the effective and efficient management of its solid waste. Waste recycling channels mainly process glass bottles for direct reuse. Some of these sectors carry out the crushing and grinding of end-of-life glass waste for use in civil engineering without the identification in terms of building materials being clearly established. The present study therefore aims to determine the physical and chemical characteristics of glass powders and sands resulting from the crushing and grinding of glass waste from Grand Lomé in Togo in order to consider their granular potential. Samples of sand and glass powder from the crushing and grinding of white, brown and green glass were subjected to characterization tests in the laboratory followed by analysis of the granular parameters and their modeling by Weibull’s law. The results show that the powder and the glass sand contain a high proportion of silica (SiO<sub>2</sub>) ranging from 69.11% to 70.18% and a low proportion of alumina (Al<sub>2</sub>O<sub>3</sub>) (less than 0.07) and iron (Fe<sub>2</sub>O<sub>3</sub>) (lower to 1.09). These three materials have tight and male graded grain sizes (Cu Cc omogeneous (k < 2.89). The absolute density (2 dab < 3) and the fineness modulus (Mf 2.1) make these materials probable aggregates for plaster and coating mortars. Nevertheless, an in-depth study will be made to determine a suitable formula.展开更多
Municipal solid waste generation is strongly linked to rising human population and expanding urban areas, with significant implications on urban metabolism as well as space and place values redefinition. Effective man...Municipal solid waste generation is strongly linked to rising human population and expanding urban areas, with significant implications on urban metabolism as well as space and place values redefinition. Effective management performance of municipal solid waste management underscores the interdisciplinarity strategies. Such knowledge and skills are paramount to uncover the sources of waste generation as well as means of waste storage, collection, recycling, transportation, handling/treatment, disposal, and monitoring. This study was conducted in Dar es Salaam city. Driven by the curiosity model of the solid waste minimization performance at source, study data was collected using focus group discussion techniques to ward-level local government officers, which was triangulated with literature and documentary review. The main themes of the FGD were situational factors (SFA) and local government by-laws (LGBY). In the FGD session, sub-themes of SFA tricked to understand how MSW minimization is related to the presence and effect of services such as land use planning, availability of landfills, solid waste transfer stations, material recovery facilities, incinerators, solid waste collection bins, solid waste trucks, solid waste management budget and solid waste collection agents. Similarly, FGD on LGBY was extended by sub-themes such as contents of the by-law, community awareness of the by-law, and by-law enforcement mechanisms. While data preparation applied an analytical hierarchy process, data analysis applied an ordinary least square (OLS) regression model for sub-criteria that explain SFA and LGBY;and OLS standard residues as variables into geographically weighted regression with a resolution of 241 × 241 meter in ArcMap v10.5. Results showed that situational factors and local government by-laws have a strong relationship with the rate of minimizing solid waste dumping in water bodies (local R square = 0.94).展开更多
<p style="margin-left:10.0pt;"> <span style="font-family:Verdana;">The combustion of MSW contains several species which if liberated into the flue gas w</span><span style="...<p style="margin-left:10.0pt;"> <span style="font-family:Verdana;">The combustion of MSW contains several species which if liberated into the flue gas w</span><span style="font-family:Verdana;">ill</span><span style="font-family:""><span style="font-family:Verdana;"> participate in erosion-corrosion reactions with the alloy surface and with the oxide layers. Actually with the evolution of material science </span><span style="font-family:Verdana;">and the discovery of 2D material</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;">, we can handle that situation as well as </span><span style="font-family:Verdana;">possible. The graphene as 2D material present</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> a lot of advantage due to it physical properties such: melting point, boiling point and thermal conductivity, which </span><span style="font-family:Verdana;">can help to manage the problem of low and middle temperature (100<span style="white-space:nowrap;">°</span>C -</span><span style="font-family:Verdana;"> 300<span style="white-space:nowrap;">°</span>C) erosion-corrosion into the boiler wall of waste to energy. The aim of the study was focused on analyz</span></span><span style="font-family:Verdana;">ing</span><span style="font-family:""><span style="font-family:Verdana;"> the resistance at low and middle temperature (100<span style="white-space:nowrap;">°</span>C - 300<span style="white-space:nowrap;">°</span>C) in the enclosed environment and the corrosion-erosion </span><span style="font-family:Verdana;">resistance abilities of the graphene sheet as the 2D protective coating materi</span><span style="font-family:Verdana;">al. This paper analyzed the possibility of using the graphene in the aggressive environment which is waste to energy boiler. The results obtained from this study after simulation using ANSYS software which is one of the best </span><span style="font-family:Verdana;">software for simulations showed that Graphene protects the furnace walls</span><span style="font-family:Verdana;"> against corrosion-erosion for temperatures lower than 400<span style="white-space:nowrap;">°</span>C and that in the presence of certain impurities such as: sodium (Na), sulfur (S), chloride (Cl) and Phos</span></span><span style="font-family:Verdana;">- </span><span style="font-family:""><span style="font-family:Verdana;">phorous (P), Sodium Chloride (NaCl), Hydrogen Chloride (HCl), Dioxide of Carbone (CO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">) and Dioxide of Sulfur (SO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">).</span></span> </p> <span "=""><span></span><sub><span></span></sub><span></span><sub><span></span></sub><span></span></span>展开更多
An artificially accelerated alternation of aging and seawater erosion test of rubber materials used in lead rubber bearing(LRB)was performed,mainly to study the time-varying laws of rubber materials mechanical propert...An artificially accelerated alternation of aging and seawater erosion test of rubber materials used in lead rubber bearing(LRB)was performed,mainly to study the time-varying laws of rubber materials mechanical properties.Time-varying laws of the Mooney–Rivlin and Neo-Hookean constitutive parameters of rubber materials under the alternation of aging and seawater erosion were also analyzed.Results indicate that the rubber material mechanical properties were significantly affected by alternation of aging and seawater erosion.Hardness and elongation stress increased exponentially with test time.And 120 days after the test,the hardness increased by 14%,the maximum percentage increase in stress of 124.76%occurred at 100%constant elongation and the minimum percentage increase in stress of 68.32%occurred at 300%constant elongation;Tensile strength and elongation at break decreased by 44.96%and 53.09%.Besides,constitutive parameters of Mooney–Rivlin and Neo-Hookean all changed greatly with test duration.Finally,time-varying laws of constitutive parameters were verified by comparing the simulated and experimental results of the lead rubber bearing’s stiffness.Research results are of great significance to the seismic performance research and life-cycle performance analysis of offshore traffic engineering such as cross-sea bridges and bridges in the marine environment.展开更多
This paper is a distillation of thirty-plus years of experience,experimentation,and observations,gleaned while designing,setting up,nunning,refining,and training people to run indoor vemicomposting systems.The objecti...This paper is a distillation of thirty-plus years of experience,experimentation,and observations,gleaned while designing,setting up,nunning,refining,and training people to run indoor vemicomposting systems.The objectives of this study are to reduce thevolume of food waste going into the waste stream;produce ligh quality organic fertilizer,improve soil heath,reduce waste-haulingcosts;encourage community members to move away from using chemical fertilizers,herbicides,and pesticides,in their gardens.Thishas been,essentially,a long-term,crowd-conducted,wide-ranging.and ongoing experiment.The design of a system is important,butthe way it is run is more important.For some people,prison inmates,for example,leaning to nun a vermicomposting system,can belife-and mind-altering.展开更多
基金the financial support from the National Natural Science Foundation of China(Grant Nos.41790441,41877249 and 41402255)Shaanxi Natural Science Foundation Project(Grant No.2017JM4008)
文摘Mine waste debris flows continue to occur in China, and the disaster prevention and mitigation of these flows faces severe challenges since the mechanisms determining erosion and transport of mine waste along gullies are not yet fully understood. The erosion and delivery process of mine waste heaps was reproduced through flume experiments with the method based on field survey data of the Daxicha mine waste debris flow gully in the Xiaoqinling gold mining area. The results showed that the erosion and movement of mine wastes could be divided into three modes: minimal sediment movement, sediment sorting and delivery, and a large amount of sediment transfer. Moreover, there was an obvious amplification effect on peak discharge along with the formation and failure of temporary landslide dams during the erosion process. The correlation between the coefficient of peak discharge amplification and three dimensionless influencing factors, flume gradient, dimensionless volume, and dimensionless particle size, were comprehensively analyzed. An empirical formula for the coefficient of peak discharge amplification was proposed and verified based on 16 sets of experimental data. These preliminary results can provide a scientific reference for future research on disaster prevention and mitigation of mine waste debris flows.
文摘This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).
文摘The sustainability of a city depends on the effective and efficient management of its solid waste. Waste recycling channels mainly process glass bottles for direct reuse. Some of these sectors carry out the crushing and grinding of end-of-life glass waste for use in civil engineering without the identification in terms of building materials being clearly established. The present study therefore aims to determine the physical and chemical characteristics of glass powders and sands resulting from the crushing and grinding of glass waste from Grand Lomé in Togo in order to consider their granular potential. Samples of sand and glass powder from the crushing and grinding of white, brown and green glass were subjected to characterization tests in the laboratory followed by analysis of the granular parameters and their modeling by Weibull’s law. The results show that the powder and the glass sand contain a high proportion of silica (SiO<sub>2</sub>) ranging from 69.11% to 70.18% and a low proportion of alumina (Al<sub>2</sub>O<sub>3</sub>) (less than 0.07) and iron (Fe<sub>2</sub>O<sub>3</sub>) (lower to 1.09). These three materials have tight and male graded grain sizes (Cu Cc omogeneous (k < 2.89). The absolute density (2 dab < 3) and the fineness modulus (Mf 2.1) make these materials probable aggregates for plaster and coating mortars. Nevertheless, an in-depth study will be made to determine a suitable formula.
文摘Municipal solid waste generation is strongly linked to rising human population and expanding urban areas, with significant implications on urban metabolism as well as space and place values redefinition. Effective management performance of municipal solid waste management underscores the interdisciplinarity strategies. Such knowledge and skills are paramount to uncover the sources of waste generation as well as means of waste storage, collection, recycling, transportation, handling/treatment, disposal, and monitoring. This study was conducted in Dar es Salaam city. Driven by the curiosity model of the solid waste minimization performance at source, study data was collected using focus group discussion techniques to ward-level local government officers, which was triangulated with literature and documentary review. The main themes of the FGD were situational factors (SFA) and local government by-laws (LGBY). In the FGD session, sub-themes of SFA tricked to understand how MSW minimization is related to the presence and effect of services such as land use planning, availability of landfills, solid waste transfer stations, material recovery facilities, incinerators, solid waste collection bins, solid waste trucks, solid waste management budget and solid waste collection agents. Similarly, FGD on LGBY was extended by sub-themes such as contents of the by-law, community awareness of the by-law, and by-law enforcement mechanisms. While data preparation applied an analytical hierarchy process, data analysis applied an ordinary least square (OLS) regression model for sub-criteria that explain SFA and LGBY;and OLS standard residues as variables into geographically weighted regression with a resolution of 241 × 241 meter in ArcMap v10.5. Results showed that situational factors and local government by-laws have a strong relationship with the rate of minimizing solid waste dumping in water bodies (local R square = 0.94).
文摘<p style="margin-left:10.0pt;"> <span style="font-family:Verdana;">The combustion of MSW contains several species which if liberated into the flue gas w</span><span style="font-family:Verdana;">ill</span><span style="font-family:""><span style="font-family:Verdana;"> participate in erosion-corrosion reactions with the alloy surface and with the oxide layers. Actually with the evolution of material science </span><span style="font-family:Verdana;">and the discovery of 2D material</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;">, we can handle that situation as well as </span><span style="font-family:Verdana;">possible. The graphene as 2D material present</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> a lot of advantage due to it physical properties such: melting point, boiling point and thermal conductivity, which </span><span style="font-family:Verdana;">can help to manage the problem of low and middle temperature (100<span style="white-space:nowrap;">°</span>C -</span><span style="font-family:Verdana;"> 300<span style="white-space:nowrap;">°</span>C) erosion-corrosion into the boiler wall of waste to energy. The aim of the study was focused on analyz</span></span><span style="font-family:Verdana;">ing</span><span style="font-family:""><span style="font-family:Verdana;"> the resistance at low and middle temperature (100<span style="white-space:nowrap;">°</span>C - 300<span style="white-space:nowrap;">°</span>C) in the enclosed environment and the corrosion-erosion </span><span style="font-family:Verdana;">resistance abilities of the graphene sheet as the 2D protective coating materi</span><span style="font-family:Verdana;">al. This paper analyzed the possibility of using the graphene in the aggressive environment which is waste to energy boiler. The results obtained from this study after simulation using ANSYS software which is one of the best </span><span style="font-family:Verdana;">software for simulations showed that Graphene protects the furnace walls</span><span style="font-family:Verdana;"> against corrosion-erosion for temperatures lower than 400<span style="white-space:nowrap;">°</span>C and that in the presence of certain impurities such as: sodium (Na), sulfur (S), chloride (Cl) and Phos</span></span><span style="font-family:Verdana;">- </span><span style="font-family:""><span style="font-family:Verdana;">phorous (P), Sodium Chloride (NaCl), Hydrogen Chloride (HCl), Dioxide of Carbone (CO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">) and Dioxide of Sulfur (SO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">).</span></span> </p> <span "=""><span></span><sub><span></span></sub><span></span><sub><span></span></sub><span></span></span>
基金This work was supported by the Programme for National Natural Science Foundation of China(52078150,51878196)National Key R&D Program of China(2019YFE0112500)2019 Guangzhou University Full-Time Graduate“Basic Innovation”Project(2019GDJC-D11).
文摘An artificially accelerated alternation of aging and seawater erosion test of rubber materials used in lead rubber bearing(LRB)was performed,mainly to study the time-varying laws of rubber materials mechanical properties.Time-varying laws of the Mooney–Rivlin and Neo-Hookean constitutive parameters of rubber materials under the alternation of aging and seawater erosion were also analyzed.Results indicate that the rubber material mechanical properties were significantly affected by alternation of aging and seawater erosion.Hardness and elongation stress increased exponentially with test time.And 120 days after the test,the hardness increased by 14%,the maximum percentage increase in stress of 124.76%occurred at 100%constant elongation and the minimum percentage increase in stress of 68.32%occurred at 300%constant elongation;Tensile strength and elongation at break decreased by 44.96%and 53.09%.Besides,constitutive parameters of Mooney–Rivlin and Neo-Hookean all changed greatly with test duration.Finally,time-varying laws of constitutive parameters were verified by comparing the simulated and experimental results of the lead rubber bearing’s stiffness.Research results are of great significance to the seismic performance research and life-cycle performance analysis of offshore traffic engineering such as cross-sea bridges and bridges in the marine environment.
文摘This paper is a distillation of thirty-plus years of experience,experimentation,and observations,gleaned while designing,setting up,nunning,refining,and training people to run indoor vemicomposting systems.The objectives of this study are to reduce thevolume of food waste going into the waste stream;produce ligh quality organic fertilizer,improve soil heath,reduce waste-haulingcosts;encourage community members to move away from using chemical fertilizers,herbicides,and pesticides,in their gardens.Thishas been,essentially,a long-term,crowd-conducted,wide-ranging.and ongoing experiment.The design of a system is important,butthe way it is run is more important.For some people,prison inmates,for example,leaning to nun a vermicomposting system,can belife-and mind-altering.
