High-steep waste dumps in open-pit mines frequently demonstrate complex particle-size distributions and fractal characteristics along their slopes,which have a significant impact on slope stability.This study takes th...High-steep waste dumps in open-pit mines frequently demonstrate complex particle-size distributions and fractal characteristics along their slopes,which have a significant impact on slope stability.This study takes the Dasuji South waste dump in Inner Mongolia as a case to quantify the fractal dimensions of soil-rock mixtures at various slope heights,and to clarify how these fractal properties govern shear strength and deformation behavior under overlying stress,thereby affecting the overall stability of the waste dump slope.Field sampling and laboratory tests were conducted to determine the particle-size composition and fractal dimensions while direct shear tests were conducted and revealed that lower fractal dimensions indicating coarser particle assemblages significantly enhance shear resistance.Complementary PFC_(2)D discrete element simulations demonstrate that slopes composed of lower-fractaldimension materials deform less and contain localized deformation zones,whereas higher-fractal-dimension slopes experience more extensive displacement and a heightened risk of landslides.These findings refine our understanding of the relationship between fractal grain-size distribution and slope stability,providing a robust theoretical basis for improved stability assessment and optimized support strategies in deep open-pit mining waste dumps,and ultimately aiding in more effective disaster prevention within geotechnical engineering.展开更多
BACKGROUND Endoscopic bariatric therapies(EBT)have been developed as an adjunctive therapy to treat persistent obesity and recurrent weight gain and dumping symptoms after metabolic and bariatric surgery(MBS).While th...BACKGROUND Endoscopic bariatric therapies(EBT)have been developed as an adjunctive therapy to treat persistent obesity and recurrent weight gain and dumping symptoms after metabolic and bariatric surgery(MBS).While the efficacy of revisional EBTs has been documented,no studies to date have examined how these procedures impact quality of life(QOL)and internalized weight bias(IWB).AIM To understand how endoscopic revisional therapies impact QOL,IWB,and dumping syndrome.METHODS Analysis included 19 participants treated for post-MBS recurrent weight gain and/or dumping syndrome.The short-form 36 survey,weight bias internalization scale,and the Sigstad scoring system were used to measure QOL,IWB,and dumping syndrome pre-and≥4 weeks post-EBT.RESULTS At 6-months,total body weight loss was 8.6%±7.15%(n=16),at 12-months was 13.4%±7.46%(n=16).Short-form 36 scores for all 8 scales significantly increased from pre-to post-procedure with the greatest improvement in the scales related to emotional(mean improvement=59.6,P<0.05)and physical health(mean improvement=31.1,P<0.05).Both total Sigstad score(mean difference=4.947,P<0.05)and total weight bias internalization score(mean difference=0.761,P<0.05)significantly decreased from pre-to post-procedure.CONCLUSION Findings suggest that revisional EBT may improve post-MBS QOL across a broad spectrum of outcomes beyond optimizing body weight.As early EBT results indicate positive mental and physical health outcomes,further research is needed to evaluate the relationship between these improvements,body weight and interdisciplinary post-MBS care.展开更多
Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump mate...Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes.In this study,pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an insitu field investigation.Spatial heterogeneity is simulated through use of the random finite element method(RFEM)and the random limit equilibrium method(RLEM)and a comparative study is presented.Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope.Seismic performances of the slope have been reported through the probability of failure and reliability index.It was observed that the RLEM approach overestimates failure probability(P_(f))by considering seismic stability with spatial heterogeneity.The P_(f)was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials.Further,it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.展开更多
With the rapid growth of China's economic strength,the demand and market share are also constantly increasing.The number ofcars is rapidly increasing,and a large amount of fuel is consumed as a result.The massive ...With the rapid growth of China's economic strength,the demand and market share are also constantly increasing.The number ofcars is rapidly increasing,and a large amount of fuel is consumed as a result.The massive release of vehicle exhaust seriously damages the natural environment,and the environmental crisis is becoming increasingly serious.This article follows the principles of improving fuel efficiency,reducing emissions,andenhancing vehicle performance.Using NX 12.0 software,a three-dimensional model of a certain type of dump truck frame is constructed based on actual parameters.ANSYS Workbench is used to simplify the geometric model,mesh division,and material definition,and a finite element model is constructed.Obtain the structural performance and natural vibration characteristics of the original chassis under four typical working conditions:bending,torsion,lifting,and unloading,through static analysis and modal analysis.On this basis,the dimensions of the components that bear less load on the original frame were optimized,and the topology of the second crossbeam and rear end corner of the subframe that bear less load on the original frame was optimized to obtain a new frame.The new frame of the dump truck underwent secondary static analysis and modal analysis,and it was found that the weight of the new frame decreased by 41.03 kg,successfully reducing the weight of the frame by 4.38%,improving the vehicle's handling and stability,and extending its service life.展开更多
Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated prim...Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated primarily by human activities and urbanization.The problem of waste littering and dumping in developing countries like Nigeria is increasingly affecting environmental resources such as air and water.Several studies have revealed alarming levels of heavy metals that exceed the World Health Organization(WHO)standards.Plastic waste represents a substantial portion of litter,affecting water quality.Pollution results in the depletion of aquatic ecosystems and an increase in water-related diseases.This review aims to assess the impact of waste littering and dumping on surface water quality in Nigeria.In this review,the findings of various studies on surface water bodies in Nigeria,particularly those under the influence of urbanization and waste disposal,were compiled.This review compared numerous physical and chemical parameters like pH,dissolved oxygen,and heavy metals,and microbiological properties such as total coliforms.The water quality index(WQI)was also computed in these studies to ascertain the suitability of the water samples for human consumption.Review results showed that numerous water bodies in Nigeria have significantly diverse water quality levels,with some samples meeting or exceeding the WHO guidelines for microbiological,chemical,and physical characteristics.Notably,levels of heavy metals,turbidity,and pH frequently exceeded permissible limits,pointing to contamination from agricultural and industrial sources.The WQI results for multiple locations revealed that the majority of surface water sources were classified as“bad”to“very bad”,meaning they were unfit for human consumption.The results emphasized the critical need for immediate action to prevent further harm and deterioration of surface water bodies in Nigeria.Recommendations include strengthening waste management policies,promoting recycling initiatives,fostering collaborations among stakeholders,developing littering penalties and enforcing fines to curb the challenge,and raising educational awareness from the primary level.This review emphasizes the need for proactive measures to protect the environment and surface water quality in Nigeria.展开更多
Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often ...Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often involves tedious and risky field work.To this end,this study demonstrated the use of periodically acquired unmanned aerial vehicle(UAV)-based images over a coal mine spoil dump in New South Wales,Australia.A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers.Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved.The two-dimensional classification outcome was then transformed into three-dimensional(3D)block models using a point-based interpolation approach for stability analysis.The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches,which treat the entire dump as a uniform category.This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments,thereby enhancing the safety and efficiency of mining operations.展开更多
The dump diffuser is an important component in advanced annular combustor, and its performance affects greatly the fluid field and pressure loss of the combustor. This paper presents the characteristics of the total p...The dump diffuser is an important component in advanced annular combustor, and its performance affects greatly the fluid field and pressure loss of the combustor. This paper presents the characteristics of the total pressure loss. Experiments and numerical simulations, keeping the inlet March number of prediffuser constant ( Ma =0 20), are carried out to obtain the regularity of the total pressure loss. It varies with the relative dump gap ( δ =1 2～3 0)by changing the position of prediffuser and combustor liner, respectively. Research shows that there exists the minimum total pressure loss ( σ *=1 6%～1 75%) when relative dump gap δ is about 1 8.展开更多
In recent decades, international trade has evolved into a complex system of trade barriers to ensure the protection of domestic industry and its workers interests. However as tariffs have fallen and international trad...In recent decades, international trade has evolved into a complex system of trade barriers to ensure the protection of domestic industry and its workers interests. However as tariffs have fallen and international trade tends to be free trade, countries have found another way of protecting domestic industries from foreign competition—non-tariff protection. Among them anti-dumping is the most controversial subject that is involved in the foreign trade. This theme will analyze the reason and effect of growing use anti-dumping measures by countries in recent decades and try to give some possible solutions.展开更多
This paper designs a novel controller to improve the path-tracking performance of articulated dump truck(ADT). By combining linear quadratic regulator(LQR) with genetic algorithm(GA), the designed controller is used t...This paper designs a novel controller to improve the path-tracking performance of articulated dump truck(ADT). By combining linear quadratic regulator(LQR) with genetic algorithm(GA), the designed controller is used to control linear and angular velocities on the midpoint of the front frame. The novel controller based on the error dynamics model is eventually realized to track the path high-precisely with constant speed. The results of simulation and experiment show that the LQR-GA controller has a better tracking performance than the existing methods under a low speed of 3 m/s. In this paper, kinematics model and simulation control models based on co-simulation of ADAMS and Matlab/Simulink are established to verify the proposed strategy. In addition, a real vehicle experiment is designed to further more correctness of the conclusion. With the proposed controller and considering the steering model in the simulation, the control performance is improved and matches the actual situation better. The research results contribute to the development of automation of ADT.展开更多
基金supported by the National Key Research and Development Program of China(2024YFC2909500)State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering(SDGZ2505)National Natural Science Foundation of China(42377148)。
文摘High-steep waste dumps in open-pit mines frequently demonstrate complex particle-size distributions and fractal characteristics along their slopes,which have a significant impact on slope stability.This study takes the Dasuji South waste dump in Inner Mongolia as a case to quantify the fractal dimensions of soil-rock mixtures at various slope heights,and to clarify how these fractal properties govern shear strength and deformation behavior under overlying stress,thereby affecting the overall stability of the waste dump slope.Field sampling and laboratory tests were conducted to determine the particle-size composition and fractal dimensions while direct shear tests were conducted and revealed that lower fractal dimensions indicating coarser particle assemblages significantly enhance shear resistance.Complementary PFC_(2)D discrete element simulations demonstrate that slopes composed of lower-fractaldimension materials deform less and contain localized deformation zones,whereas higher-fractal-dimension slopes experience more extensive displacement and a heightened risk of landslides.These findings refine our understanding of the relationship between fractal grain-size distribution and slope stability,providing a robust theoretical basis for improved stability assessment and optimized support strategies in deep open-pit mining waste dumps,and ultimately aiding in more effective disaster prevention within geotechnical engineering.
文摘BACKGROUND Endoscopic bariatric therapies(EBT)have been developed as an adjunctive therapy to treat persistent obesity and recurrent weight gain and dumping symptoms after metabolic and bariatric surgery(MBS).While the efficacy of revisional EBTs has been documented,no studies to date have examined how these procedures impact quality of life(QOL)and internalized weight bias(IWB).AIM To understand how endoscopic revisional therapies impact QOL,IWB,and dumping syndrome.METHODS Analysis included 19 participants treated for post-MBS recurrent weight gain and/or dumping syndrome.The short-form 36 survey,weight bias internalization scale,and the Sigstad scoring system were used to measure QOL,IWB,and dumping syndrome pre-and≥4 weeks post-EBT.RESULTS At 6-months,total body weight loss was 8.6%±7.15%(n=16),at 12-months was 13.4%±7.46%(n=16).Short-form 36 scores for all 8 scales significantly increased from pre-to post-procedure with the greatest improvement in the scales related to emotional(mean improvement=59.6,P<0.05)and physical health(mean improvement=31.1,P<0.05).Both total Sigstad score(mean difference=4.947,P<0.05)and total weight bias internalization score(mean difference=0.761,P<0.05)significantly decreased from pre-to post-procedure.CONCLUSION Findings suggest that revisional EBT may improve post-MBS QOL across a broad spectrum of outcomes beyond optimizing body weight.As early EBT results indicate positive mental and physical health outcomes,further research is needed to evaluate the relationship between these improvements,body weight and interdisciplinary post-MBS care.
基金the financial support provided by MHRD,Govt.of IndiaCoal India Limited for providing financial assistance for the research(Project No.CIL/R&D/01/73/2021)the partial financial support provided by the Ministry of Education,Government of India,under SPARC project(Project No.P1207)。
文摘Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes.In this study,pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an insitu field investigation.Spatial heterogeneity is simulated through use of the random finite element method(RFEM)and the random limit equilibrium method(RLEM)and a comparative study is presented.Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope.Seismic performances of the slope have been reported through the probability of failure and reliability index.It was observed that the RLEM approach overestimates failure probability(P_(f))by considering seismic stability with spatial heterogeneity.The P_(f)was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials.Further,it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.
文摘With the rapid growth of China's economic strength,the demand and market share are also constantly increasing.The number ofcars is rapidly increasing,and a large amount of fuel is consumed as a result.The massive release of vehicle exhaust seriously damages the natural environment,and the environmental crisis is becoming increasingly serious.This article follows the principles of improving fuel efficiency,reducing emissions,andenhancing vehicle performance.Using NX 12.0 software,a three-dimensional model of a certain type of dump truck frame is constructed based on actual parameters.ANSYS Workbench is used to simplify the geometric model,mesh division,and material definition,and a finite element model is constructed.Obtain the structural performance and natural vibration characteristics of the original chassis under four typical working conditions:bending,torsion,lifting,and unloading,through static analysis and modal analysis.On this basis,the dimensions of the components that bear less load on the original frame were optimized,and the topology of the second crossbeam and rear end corner of the subframe that bear less load on the original frame was optimized to obtain a new frame.The new frame of the dump truck underwent secondary static analysis and modal analysis,and it was found that the weight of the new frame decreased by 41.03 kg,successfully reducing the weight of the frame by 4.38%,improving the vehicle's handling and stability,and extending its service life.
基金support received by the University of South Africa for a conducive research environment。
文摘Water resources are vital for all living beings and should be managed properly to ensure the safety and well-being of humankind.Surface water bodies are constantly faced with serious contamination risks generated primarily by human activities and urbanization.The problem of waste littering and dumping in developing countries like Nigeria is increasingly affecting environmental resources such as air and water.Several studies have revealed alarming levels of heavy metals that exceed the World Health Organization(WHO)standards.Plastic waste represents a substantial portion of litter,affecting water quality.Pollution results in the depletion of aquatic ecosystems and an increase in water-related diseases.This review aims to assess the impact of waste littering and dumping on surface water quality in Nigeria.In this review,the findings of various studies on surface water bodies in Nigeria,particularly those under the influence of urbanization and waste disposal,were compiled.This review compared numerous physical and chemical parameters like pH,dissolved oxygen,and heavy metals,and microbiological properties such as total coliforms.The water quality index(WQI)was also computed in these studies to ascertain the suitability of the water samples for human consumption.Review results showed that numerous water bodies in Nigeria have significantly diverse water quality levels,with some samples meeting or exceeding the WHO guidelines for microbiological,chemical,and physical characteristics.Notably,levels of heavy metals,turbidity,and pH frequently exceeded permissible limits,pointing to contamination from agricultural and industrial sources.The WQI results for multiple locations revealed that the majority of surface water sources were classified as“bad”to“very bad”,meaning they were unfit for human consumption.The results emphasized the critical need for immediate action to prevent further harm and deterioration of surface water bodies in Nigeria.Recommendations include strengthening waste management policies,promoting recycling initiatives,fostering collaborations among stakeholders,developing littering penalties and enforcing fines to curb the challenge,and raising educational awareness from the primary level.This review emphasizes the need for proactive measures to protect the environment and surface water quality in Nigeria.
基金supported by the Australian coal industry's research(Grant No.C29048).
文摘Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often involves tedious and risky field work.To this end,this study demonstrated the use of periodically acquired unmanned aerial vehicle(UAV)-based images over a coal mine spoil dump in New South Wales,Australia.A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers.Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved.The two-dimensional classification outcome was then transformed into three-dimensional(3D)block models using a point-based interpolation approach for stability analysis.The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches,which treat the entire dump as a uniform category.This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments,thereby enhancing the safety and efficiency of mining operations.
文摘The dump diffuser is an important component in advanced annular combustor, and its performance affects greatly the fluid field and pressure loss of the combustor. This paper presents the characteristics of the total pressure loss. Experiments and numerical simulations, keeping the inlet March number of prediffuser constant ( Ma =0 20), are carried out to obtain the regularity of the total pressure loss. It varies with the relative dump gap ( δ =1 2～3 0)by changing the position of prediffuser and combustor liner, respectively. Research shows that there exists the minimum total pressure loss ( σ *=1 6%～1 75%) when relative dump gap δ is about 1 8.
文摘In recent decades, international trade has evolved into a complex system of trade barriers to ensure the protection of domestic industry and its workers interests. However as tariffs have fallen and international trade tends to be free trade, countries have found another way of protecting domestic industries from foreign competition—non-tariff protection. Among them anti-dumping is the most controversial subject that is involved in the foreign trade. This theme will analyze the reason and effect of growing use anti-dumping measures by countries in recent decades and try to give some possible solutions.
基金the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-15-023A1)the National Key R&D Program Project(Nos.2016YFC0802905 and 2018YFC0604403)
文摘This paper designs a novel controller to improve the path-tracking performance of articulated dump truck(ADT). By combining linear quadratic regulator(LQR) with genetic algorithm(GA), the designed controller is used to control linear and angular velocities on the midpoint of the front frame. The novel controller based on the error dynamics model is eventually realized to track the path high-precisely with constant speed. The results of simulation and experiment show that the LQR-GA controller has a better tracking performance than the existing methods under a low speed of 3 m/s. In this paper, kinematics model and simulation control models based on co-simulation of ADAMS and Matlab/Simulink are established to verify the proposed strategy. In addition, a real vehicle experiment is designed to further more correctness of the conclusion. With the proposed controller and considering the steering model in the simulation, the control performance is improved and matches the actual situation better. The research results contribute to the development of automation of ADT.
