Flotation is the most common method to recover valuable minerals by selective adsorption of collectors on target mineral surfaces.However,in subsequent hydrometallurgy of mineral flotation concentrates,the adsorbed co...Flotation is the most common method to recover valuable minerals by selective adsorption of collectors on target mineral surfaces.However,in subsequent hydrometallurgy of mineral flotation concentrates,the adsorbed collectors must be desorbed since it can adversely affect the efficiency of metallurgical process and produce wastewater.ZL,as a fatty acid mixture,is a typical industrially used collector for scheelite flotation in China.Sodium oleate(NaOL)has similar fatty acid group as ZL.In this study,the desorption behavior of NaOL/ZL from scheelite surface by a physical method of stirring at a low temperature was investigated.NaOL desorption tests of single mineral showed that a desorption rate of 77.75% for NaOL from scheelite surface into pulp was achieved in a stirring speed of2500 r/min at 5℃in a neutral environment.Under the above desorption condition,in the pulp containing desorbed collector by adding extra 30% normal NaOL dosage,the scheelite recovery reached about 95% in the single mineral flotation test.Desorption and reuse of ZL collector for the flotation of real scheelite ore showed only a 75%normal dosage of ZL could produce a qualified rough concentrate.The atomic force microscope(AFM)tests showed that after desorption treatment of low temperature and strong stirring,the dense strip-like structure of NaOL on the scheelite surface was destroyed to be speck-like.Molecular dynamics simulations(MDS)demonstrated that the adsorption energy between NaOL and scheelite surface was more negative at 25℃(-13.39 kcal/mol)than at 5℃(-11.50 kcal/mol)in a neutral pH,indicating that a low temperature was beneficial for the desorption of collector from mineral surface.Due to its simplicity and economy,the method we proposed of desorption of collector from mineral surface and its reuse for flotation has a great potential for industrial application.展开更多
The Nome nickel laterite deposit is located in the North East of Albania. The ore deposit, developed between ultramafic rocks and limestones during Early Cretaceous to Eocene, represents part of the Albanian Mirdita o...The Nome nickel laterite deposit is located in the North East of Albania. The ore deposit, developed between ultramafic rocks and limestones during Early Cretaceous to Eocene, represents part of the Albanian Mirdita ophiolite zone. The lateritization of the deposit was observed mainly in three separate areas, the Has-Kukes-Lure in the North, Pogradec-Librazhd in the center and Devoll in the South. The main mineralogical components of the ore are goethite, hematite and quartz, while the secondary ones are chlorite (clinochlore, Ni-chlorite), kaolinite and lizardite. Nickel is mainly found in chlorite. The ore is characterized by the presence of spheroid particles, such as oval, pisoid, peloid and composite spheroid. According to the microscopical examination the ore is characterized in general as allotriomorphic, inequigranular and the texture is oolitic-pisolitic. For the mineral processing gravimetric and magnetic separation are used in the size fractions NJ + 4 mm, dž + 1 mm, ǃ + 0.250 mm and ǂ.250 + 0.063 mm. The chemical and mineralogical analyses, as well as the microscopic examination have shown that mineral processing by magnetic separation gives the most satisfactory results for the size fractions ǃ + 0.250 mm and ǂ.250 + 0.063 mm.展开更多
Process engineering has been seen as one of the vital tools for improving surface coating phenomena for advance application. In an attempt to improve the mechanical, physical and chemical performance of the steel stru...Process engineering has been seen as one of the vital tools for improving surface coating phenomena for advance application. In an attempt to improve the mechanical, physical and chemical performance of the steel structure for ex-tended application, Zn-CeO2/ZnCeO2-Al2SiO5 thin film composite was fabri-cated on mild steel using direct electrolytic route. Process variation of Al2SiO5 particulate ranges from 5 to 15 g per litre. The embedded coating was charac-terized using Scanning electron microscope (SEM). The chemical effect of the developed alloy was characterized through linear potentiodynamic polarization experiment and the performances of samples were examined in simulated 3.5% sodium chloride. The microhardness verification study proves that there is sig-nificant improvement in hardness trend. The tribological assessment indicated that there is less plastic deformation as a result of the counter body. In all, Zn-CeO2/Zn-CeO2-Al2SiO5 exhibits good stability, with agglomeration and great built up of crystal at the interface.展开更多
Hurricanes are one of the most destructive natural disasters that can cause catastrophic losses to both communities and infrastructure.Assessment of hurricane risk furnishes a spatial depiction of the interplay among ...Hurricanes are one of the most destructive natural disasters that can cause catastrophic losses to both communities and infrastructure.Assessment of hurricane risk furnishes a spatial depiction of the interplay among hazard,vulnerability,exposure,and mitigation capacity,crucial for understanding and managing the risks hurricanes pose to communities.These assessments aid in gauging the efficacy of existing hurricane mitigation strategies and gauging their resilience across diverse climate change scenarios.A systematic review was conducted,encompassing 94 articles,to scrutinize the structure,data inputs,assumptions,methodologies,perils modelled,and key predictors of hurricane risk.This review identified key research gaps essential for enhancing future risk assessments.The complex interaction between hurricane perils may be disastrous and underestimated in the majority of risk assessments which focus on a single peril,commonly storm surge and flood,resulting in inadequacies in disaster resilience planning.Most risk assessments were based on hurricane frequency rather than hurricane damage,which is more insightful for policymakers.Furthermore,considering secondary indirect impacts stemming from hurricanes,including real estate market and business interruption,could enrich economic impact assessments.Hurricane mitigation measures were the most under-utilised category of predictors leveraged in only 5%of studies.The top six predictive factors for hurricane risk were land use,slope,precipitation,elevation,population density,and soil texture/drainage.Another notable research gap identified was the potential of machine learning techniques in risk assessments,offering advantages over traditional MCDM and numerical models due to their ability to capture complex nonlinear relationships and adaptability to different study regions.Existing machine learning based risk assessments leverage random forest models(42%of studies)followed by neural network models(19%of studies),with further research required to investigate diverse machine learning algorithms such as ensemble models.A further research gap is model validation,in particular assessing transferability to a new study region.Additionally,harnessing simulated data and refining projections related to demographic and built environment dynamics can bolster the sophistication of climate change scenario assessments.By addressing these research gaps,hurricane risk assessments can furnish invaluable insights for national policymakers,facilitating the development of robust hurricane mitigation strategies and the construction of hurricane-resilient communities.To the authors’knowledge,this represents the first literature review specifically dedicated to quantitative hurricane risk assessments,encompassing a comparison of Multi-criteria Decision Making(MCDM),numerical models,and machine learning models.Ultimately,advancements in hurricane risk assessments and modelling stand poised to mitigate potential losses to communities and infrastructure both in the immediate and long-term future.展开更多
Phosphorus(P)poses a global challenge to the environment and human health due to its natural association with heavy metals.Sustainable use of P is crucial to ensure food security for future generations.An analysis of ...Phosphorus(P)poses a global challenge to the environment and human health due to its natural association with heavy metals.Sustainable use of P is crucial to ensure food security for future generations.An analysis of the 150 phosphate fertilizers stored at the Institute for Crop and Soil Science in Germany has been conducted,supplemented by previously published data.The elements Cd,Bi,U,Cr,Zn,Tl,As,B,Sb,Ni,and Se are found in higher concentrations in sedimentary derived phosphates compared to igneous derived phosphates.Mineral fertilizers contain more than ten times the amount of U,Cd,B,and As compared to farmyard manure.Principal component analyses(PCA)indicate that U,Cd,Be,and Cr are primarily present in sedimentary derived phosphates and their concentrations are 2 to 10 times higher than those in igneous derived phosphates.Regarding heavy metal contamination,over 1000 potential combinations were identified;36% of these were significant but weak(>0.1).It is estimated that approximately 707 t of uranium enter farmland annually through the application of mineral phosphate fertilizers in European countries.This contribution addresses environmental issues related to the utilization of rock phosphate as well as alternative production methods for cleaner and safer phosphate fertilizers while presenting a roadmap with measures for mitigation.展开更多
It is of great importance to explore sustainable and eco-friendly recycling strategies for spent Li-ion batteries(LIBs).As such,the closed-loop resynthesis of LiNi_(x)CoyMn_(z)O_(2)(NCM)becomes recently popular as exe...It is of great importance to explore sustainable and eco-friendly recycling strategies for spent Li-ion batteries(LIBs).As such,the closed-loop resynthesis of LiNi_(x)CoyMn_(z)O_(2)(NCM)becomes recently popular as exemplified by the commercialization of low-and mid-Ni content NCM(33%-60%).However,there has been suspicion as to the successful deployment of Ni-rich NCM resynthesis process.Therefore,we systematically increase the Ni content of NCM from 60%to 90%from the industrial leachate of spent LIBs containing various metallic and nonmetallic impurities.The utilization rate of the leachate decreases from 71.8 mol%for NCM622 to 18.0 mol%for NCM955 as the Ni content in the NCM composition increases with the Co recycling rate being 100%in all resynthesized NCM(RNCM).The physicochemical and electrochemical properties of RNCM are systematically compared with its pristine NCM counterparts.As a result,various physicochemical properties of RNCM including impurity content,crystallographic information,morphology,particle size,porosity,specific surface area,elemental distribution,residual lithium compounds,and thermal stability are correlated with its electrochemical properties.It is found out that Al is the most critical impurity that determines the physicochemical and electrochemical properties of RNCM.It is noteworthy that RNCM955 prepared from spent LIBs without any purification step surpasses NCM955 in terms of rate and cycle performance.Further,this resynthesis approach toward Nirich NCM could meet the forthcoming 2031 EU's legislative target on the mandatory minimum recycling usage of valuable metals from spent LIBs.The anode active material was resynthesized using industrial leachate as the maximum.The amount of leachate used and the amount of impurities were proportional.展开更多
The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment.This study presented a rapid and cost-effec...The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment.This study presented a rapid and cost-effective direct heating method for synthesizing MnO_(2) nanoflowers on coil substrates for the removal of organic pollutants.Traditional methods often require high power,expensive equipment,and long synthesis times.In contrast,the direct heating approach successfully synthesized MnO_(2) nanoflowers in just 10 min with a heating power of approximately 40 W·h after the heating power and duration were optimized.These nanoflowers effectively degraded 99%Rhodamine B in 60 min with consistent repeatability.The catalytic mechanisms are attributed to crystal defects in MnO_(2),which generate electrons to produce H_(2)O_(2).Mn6(2+)ions in the acidic solution further dissociate H_(2)O_(2) molecules into hydroxyl radicals(·OH).The high efficiency of this synthesis method and the excellent reusability of MnO_(2) nanoflowers highlight their potential as a promising solution for the development of supporting MnO_(2) catalysts for organic dye removal applications.展开更多
Carbon capture and storage(CCS)remains one of the most feasible techniques for the control of Greenhouse gas emission levels.However,there will always be risks attached to the subsurface injection of CO_(2).These coul...Carbon capture and storage(CCS)remains one of the most feasible techniques for the control of Greenhouse gas emission levels.However,there will always be risks attached to the subsurface injection of CO_(2).These could be in the form of leakages from the injection wellbore due to completion failure;escape of the injected CO_(2)to neighboring aquifers due to the heterogeneous or fractured nature of the storage site;or seepage at the surface due to inadequacy of the sealing cap rock.While all these may occur,the most cost-effective and timely way to reduce the risk of leakages is by plugging the pathways.This is done using either traditional Cementous materials or more augmented sealants like organic gels and resins.A lot of studies in the literature have described this collection of materials within the context of CO_(2)conformance control.So also,there are reviews on the classification and description of these chemicals.This review provides a more systemic evaluation of these classes of chemicals.This is by providing critical analyses of how external factors like CO_(2),pH,brine salinity and hardness,rock mineralogy,pressure,temperature,and injectivity could affect the performance of different sealants that can be utilized.Based on these assessments,best practices for the application of the sealants,both at the testing stage in the laboratory and the pilot stage and field deployment,are suggested.展开更多
Objective This study aimed to evaluate the potential of a collagen-coated,3D-printed tracheal scaffold(3D-TechTra)integrated with human umbilical cord mesenchymal stem cells(hUC-MSCs)for tracheal tissue regeneration.M...Objective This study aimed to evaluate the potential of a collagen-coated,3D-printed tracheal scaffold(3D-TechTra)integrated with human umbilical cord mesenchymal stem cells(hUC-MSCs)for tracheal tissue regeneration.Methods The thermoplastic polyurethane/polylactic acid(TPU/PLA)scaffold was engineered to optimize mechanical properties and biocompatibility,with the goal of mimicking the structural and tensile characteristics of native tracheal tissue.Subsequently,preclinical experiments were conducted using rabbit models:the performance of the collagen-coated TPU/PLA scaffold with hUC-MSCs was compared with that of uncoated scaffolds and collagen-only scaffolds.In vitro tests were also performed to assess the adhesion,proliferation,and differentiation of hUC-MSCs on the scaffold.For in vivo evaluation,multiple analytical methods were employed,including immunohistological analysis(to detect glycosaminoglycan deposition and extracellular matrix remodeling),radiographic and endoscopic evaluations(to assess tracheal contour and airway obstruction),and survival analysis(to monitor animal outcomes and systemic toxicity).Results In vitro,hUC-MSCs successfully adhered to and proliferated on the TPU/PLA scaffold,and differentiated into adipogenic,osteogenic,and chondrogenic lineages,which supported the potential for tissue-specific regeneration;in vivo,compared with uncoated or collagen-only scaffolds,the collagen-coated TPU/PLA scaffold integrated with hUC-MSCs exhibited enhanced integration with host tissues,superior biocompatibility,and reduced tracheal stenosis,while also preserving airway patency,alleviating inflammation,and facilitating epithelial regeneration,smooth muscle formation,and vascularization.Immunohistological analysis further revealed significant glycosaminoglycan deposition and extracellular matrix remodeling in the hUC-MSC-treated group,and radiographic and endoscopic evaluations confirmed preserved tracheal contour and reduced airway obstruction;additionally,survival analysis showed significantly improved outcomes in animals treated with the collagen-coated TPU/PLA scaffold containing hUC-MSCs,with no systemic toxicity observed.Conclusions This study demonstrated the synergistic potential of TPU/PLA scaffolds,collagen coatings,and hUC-MSCs,providing valuable evidence for advancing the application of these components in tracheal tissue engineering.展开更多
Digitalisation in mining refers to the use of computerised or digital devices or systems and digitised data that are to reduce costs,improve business productivity,and transform mining practices.However,it remains incr...Digitalisation in mining refers to the use of computerised or digital devices or systems and digitised data that are to reduce costs,improve business productivity,and transform mining practices.However,it remains increasingly difficult for mining companies to decide which digital technologies are most relevant to their needs and individual mines.This paper provides an overview of digital technologies currently relevant to mining companies as presented and discussed by mining journals,the media and insight reports of leading consultancy agencies.Relevant technologies were systematically identified using text-mining techniques,and network analyses established the relations between significant technologies.Results demonstrated that currently 107 different digital technologies are pursued in the mining sector.Also,an analysis of the actual implementation of digital technologies in 158 active surface and underground mines reveals a limited uptake of digital technologies in general and that the uptake increases with the run-of-mine production.Large-scale mining operations appear to select and apply digital technologies suitable to their needs,whereas operations with lower production rates do not implement the currently available digital technologies to the same extent.These minor producers may require other digital transformation solutions tailored to their capabilities and needs and applicable to their scale of operations.展开更多
In this study, a novel approach of the landslide numerical risk factor(LNRF) bivariate model was used in ensemble with linear multivariate regression(LMR) and boosted regression tree(BRT) models, coupled with radar re...In this study, a novel approach of the landslide numerical risk factor(LNRF) bivariate model was used in ensemble with linear multivariate regression(LMR) and boosted regression tree(BRT) models, coupled with radar remote sensing data and geographic information system(GIS), for landslide susceptibility mapping(LSM) in the Gorganroud watershed, Iran. Fifteen topographic, hydrological, geological and environmental conditioning factors and a landslide inventory(70%, or 298 landslides) were used in mapping. Phased array-type L-band synthetic aperture radar data were used to extract topographic parameters. Coefficients of tolerance and variance inflation factor were used to determine the coherence among conditioning factors. Data for the landslide inventory map were obtained from various resources, such as Iranian Landslide Working Party(ILWP), Forestry, Rangeland and Watershed Organisation(FRWO), extensive field surveys, interpretation of aerial photos and satellite images, and radar data. Of the total data, 30% were used to validate LSMs, using area under the curve(AUC), frequency ratio(FR) and seed cell area index(SCAI).Normalised difference vegetation index, land use/land cover and slope degree in BRT model elevation, rainfall and distance from stream were found to be important factors and were given the highest weightage in modelling. Validation results using AUC showed that the ensemble LNRF-BRT and LNRFLMR models(AUC = 0.912(91.2%) and 0.907(90.7%), respectively) had high predictive accuracy than the LNRF model alone(AUC = 0.855(85.5%)). The FR and SCAI analyses showed that all models divided the parameter classes with high precision. Overall, our novel approach of combining multivariate and machine learning methods with bivariate models, radar remote sensing data and GIS proved to be a powerful tool for landslide susceptibility mapping.展开更多
Titanium and its alloys have long been used as implant materials due to their outstanding mechanical properties and apparent biocompatibility.Despite this,the search for better alloys has continued to be active by res...Titanium and its alloys have long been used as implant materials due to their outstanding mechanical properties and apparent biocompatibility.Despite this,the search for better alloys has continued to be active by researchers and industries alike,as there are still pressing issues that require attention.These include(1)a large mismatch in the elastic modulus of the implant material,which causes a stress shielding problem;(2)the release of harmful ions from Ti alloys after long-term use;(3)a low bioactivity of the Ti alloy surface,which prolongs the healing process.More research has been directed toward finding new generation Ti alloys composed of more biocompatible phases and modifying the surface of Ti alloys from naturally bio-inert to bioactive in order to circumvent the problems.This review examines recent work reported on the fabrication of Ti alloys,and based on the survey,major characteristics highlighted the importance of elastic modulus and the use of non-toxic metal elements to improve biocompatibility.In terms of surface modification of Ti alloys,numerous studies have found that a nano-scaled surface oxide layer grown on the surface is always beneficial to improving the bioactivity of Ti alloys for rapid recovery after implantation.This comprehensive review focuses on the appropriate phase and composition for new Ti alloys intended for use as biomedical implants,emphasizing both fabrication and surface modification methods.展开更多
This paper provides an overview of coal waste management practices with two case studies and an estimate of management cost in 2010 US dollars.Processing of as-mined coal typically results in considerable amount of co...This paper provides an overview of coal waste management practices with two case studies and an estimate of management cost in 2010 US dollars.Processing of as-mined coal typically results in considerable amount of coarse and fine coal processing wastes because of in-seam and out-of-seam dilution mining.Processing plant clean coal recovery values run typically 50%-80%.Trace metals and sulfur may be present in waste materials that may result in leachate water with corrosive characteristics.Water discharges may require special measures such as liner and collection systems,and treatment to neutralize acid drainage and/or water quality for trace elements.The potential for variations in coal waste production and quality depends upon mining or processing,plus the long-term methods of waste placement.The changes in waste generation rates and engineering properties of the coal waste during the life of the facility must be considered.Safe,economical and environmentally acceptable management of coal waste involves consideration of geology,soil and rock mechanics,hydrology,hydraulics,geochemistry,soil science,agronomy and environmental sciences.These support all aspects of the regulatory environment including the design and construction of earth and rock embankments and dams,as well as a wide variety of waste disposal structures.Development of impoundments is critical and require considerations of typical water-impounding dams and additional requirements of coal waste disposal impoundments.The primary purpose of a coal waste disposal facility is to dispose of unusable waste materials from mining.However,at some sites coal waste impoundments serve to provide water storage capacity for processing and flood attenuation.展开更多
Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aero...Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aerospace industry.The microstructure and mechanical properties of the weldments were also investigated.Relationships between the parameters and weld bead geometry were found.High quality weld joints without solidification crack that met AWS D17.1 requirements were obtained at(I)high pulse energy(25 J)and high average peak power(4.2 kW)and(II)low pulse energy(17.6 J)and low average peak power(2.8 kW).The weld joint formed at lower heat energy input exhibited finer dendritic grain structure.Mg vapourisation and hard phase compound(Al0.5Fe3Si0.5)formation decreased in the weld joint formed at lower heat energy input.Consequently,the tensile strength of the weldment formed at lower heat energy input(168 MPa)is by a factor of 1.15 higher but showed^29%decrease in hardness(111 HV0.1)at the joint when being compared with the weldment formed at higher heat energy input.Appropriate parameters selection is critical to obtaining 0.6 mm-thick AA5052-H32 pulse laser weld joints that meet AWS D17.1 requirements for aircraft structures.展开更多
Selective laser melting(SLM)is an emerging layer-wise additive manufacturing technique that can generate complex components with high performance.Particulate-reinforced aluminum matrix composites(PAMCs)are important m...Selective laser melting(SLM)is an emerging layer-wise additive manufacturing technique that can generate complex components with high performance.Particulate-reinforced aluminum matrix composites(PAMCs)are important materials for various applications due to the combined properties of Al matrix and reinforcements.Considering the advantages of SLM technology and PAMCs,the novel SLM PAMCs have been developed and researched in recent years.Therefore,the current research progress about the SLM PAMCs is reviewed.Firstly,special attention is paid to the solidification behavior of SLM PAMCs.Secondly,the important issues about the design and fabrication of high-performance SLM PAMCs,including the selection of reinforcement,the influence of parameters on the processing and microstructure,the defect evolution and phase control,are highlighted and discussed comprehensively.Thirdly,the performance and strengthening mechanism of SLM PAMCs are systematically figured out.Finally,future directions are pointed out on the advancement of high-performance SLM PAMCs.展开更多
Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extreme...Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extremely thick coal seams because the control mechanism of the system for the deformation of the roof and the separation between coal rock segments is not completely understood. By using the relationship between the support system and the roof strata, a mechanical model was established to calculate the deformation of the roof in a thick coal seam with bedding separation under different support conditions: with an anchor truss support and without support. On this basis, the research was used to deduce a method for computing the minimum pre-tightening forces in the anchor truss, the maximum amounts of subsidence and separation with, and without, anchor truss support under the roof, and the maximum subsidence and the decreasing amounts of the separation before and after adopting the anchor truss. Additionally, mechanical relationships between the minimum pre-tightening force and the anchoring force in the anchor were analyzed. By taking a typical roadway with thick coal roof as an example, the theoretical results mentioned above were applied in the analysis and testing of a roof supporting project in a roadway field to verify the accuracy of the theory: favorable experimental results were achieved. In addition, the relationships among other parameters were analyzed, including the minimum pre-tightening forces applied by the anchor truss, the angle of inclination of the anchor cable, and the array pitch. Meanwhile, the changing characteristics of the amounts of roof separation and subsidence with key parameters of the support system(such as array pitch, pre-tightening force, and inclination angle) were also analyzed. The research results revealed the acting mechanism of the anchor truss in control of roadway stability with a thick coal seam, providing a theoretical basis of its application in coal mining.展开更多
Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the inciden...Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the incident bar of an SHPB apparatus is used to absorb some of the shock energy. This can generate loading rates of 20.2-4627.3 GPa/s, enabling dynamic peak stresses/strengths and associated failure patterns of the specimens to be investigated. The effects of the loading rate and angle of load applied on the dynamic peak stresses/strengths of the specimens are examined. Relevant experimental results demonstrate that the failure pattern of each specimen can be classified as four types： Type A, integrated with or without tiny flake-off; Type B, slide failure; Type C, fracture failure; and Type D, crushing failure. The dynamic peak stresses/strengths of the specimens that have similar failure patterns increase linearly with the loading rate, yielding high correlations that are evident on semi-logarithmic plots. The slope of the failure envelope is the smallest for slide failure, followed by crushing failure, and that of fracture failure is the largest. The magnitude of the plot slope of the dynamic peak stress against the loading rate for the specimens that are still integrated after testing is between that of slide failure and crushing failure. The angle of application has a limited effect on the dynamic peak stresses/strengths of the specimens regardless of the failure pattern, but it affects the bounds of the loading rates that yield each failure pattern, and thus influences the dynamic responses of the single jointed specimen. Slide failure occurs at the lowest loading rate of any failure, but can only occur in single jointed specimen that allows sliding.Crushing failure is typically associated with the largest loading rate, and fracture failure may occur when the loading rate is between the boundaries for slide failure and crushing failure.展开更多
The installation of a back-wall guard-board is the key to successfully supporting underground retreating roadways in coal mines. Based on the coordinate support principle, and using an I-shaped steel support for the s...The installation of a back-wall guard-board is the key to successfully supporting underground retreating roadways in coal mines. Based on the coordinate support principle, and using an I-shaped steel support for the surrounding rock, a mechanical model was developed for the stability of the roadway support and surrounding rock. Analysis of the bearing capacity of the roof back-wall guard-board and modelling of the equations for the maximum deflection and the maximum compressive stress of the top and side beams of the I-shaped steel support were undertaken. Simultaneously, the model was used to calculate and analyse the stability of the top and side beams of the I-shaped steel support structure and analyse the criteria for their stability. The results provide a reliable theoretical basis for the judgment of the stability of the surrounding rock and support structure. The theoretical evaluation results are consistent with field data. Finally, the key support parameters of the top and side beams of the I-shaped steel support structure and the variation of the maximum deflection and the maximum compressive stress as affected by the influence of the guard-board length were investigated. It is concluded that, as the back-board length increases, the maximum compressive stress in the top beam of the I-shaped steel support increases while the compressive stress in the side beam decreases. The results show that the accuracy of judgment of the stability of a supported retreating roadway is improved, providing guidance for the design of such typical I-shaped steel support and back-board structures.展开更多
In recent years,landslide susceptibility mapping has substantially improved with advances in machine learning.However,there are still challenges remain in landslide mapping due to the availability of limited inventory...In recent years,landslide susceptibility mapping has substantially improved with advances in machine learning.However,there are still challenges remain in landslide mapping due to the availability of limited inventory data.In this paper,a novel method that improves the performance of machine learning techniques is presented.The proposed method creates synthetic inventory data using Generative Adversarial Networks(GANs)for improving the prediction of landslides.In this research,landslide inventory data of 156 landslide locations were identified in Cameron Highlands,Malaysia,taken from previous projects the authors worked on.Elevation,slope,aspect,plan curvature,profile curvature,total curvature,lithology,land use and land cover(LULC),distance to the road,distance to the river,stream power index(SPI),sediment transport index(STI),terrain roughness index(TRI),topographic wetness index(TWI)and vegetation density are geo-environmental factors considered in this study based on suggestions from previous works on Cameron Highlands.To show the capability of GANs in improving landslide prediction models,this study tests the proposed GAN model with benchmark models namely Artificial Neural Network(ANN),Support Vector Machine(SVM),Decision Trees(DT),Random Forest(RF)and Bagging ensemble models with ANN and SVM models.These models were validated using the area under the receiver operating characteristic curve(AUROC).The DT,RF,SVM,ANN and Bagging ensemble could achieve the AUROC values of(0.90,0.94,0.86,0.69 and 0.82)for the training;and the AUROC of(0.76,0.81,0.85,0.72 and 0.75)for the test,subsequently.When using additional samples,the same models achieved the AUROC values of(0.92,0.94,0.88,0.75 and 0.84)for the training and(0.78,0.82,0.82,0.78 and 0.80)for the test,respectively.Using the additional samples improved the test accuracy of all the models except SVM.As a result,in data-scarce environments,this research showed that utilizing GANs to generate supplementary samples is promising because it can improve the predictive capability of common landslide prediction models.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52304314 and U23A20602)the Open Fund of the Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,Ministry of Ecology and Environment+3 种基金China(No.HB202406)the Fundamental Research Funds for the Central Universities of Central South University,China(Nos.CX20240021 and 2024ZZTS0008)the Innovation and Entrepreneurship Funding Project for College Students of Central South UniversityChina(No.S202410533166)。
文摘Flotation is the most common method to recover valuable minerals by selective adsorption of collectors on target mineral surfaces.However,in subsequent hydrometallurgy of mineral flotation concentrates,the adsorbed collectors must be desorbed since it can adversely affect the efficiency of metallurgical process and produce wastewater.ZL,as a fatty acid mixture,is a typical industrially used collector for scheelite flotation in China.Sodium oleate(NaOL)has similar fatty acid group as ZL.In this study,the desorption behavior of NaOL/ZL from scheelite surface by a physical method of stirring at a low temperature was investigated.NaOL desorption tests of single mineral showed that a desorption rate of 77.75% for NaOL from scheelite surface into pulp was achieved in a stirring speed of2500 r/min at 5℃in a neutral environment.Under the above desorption condition,in the pulp containing desorbed collector by adding extra 30% normal NaOL dosage,the scheelite recovery reached about 95% in the single mineral flotation test.Desorption and reuse of ZL collector for the flotation of real scheelite ore showed only a 75%normal dosage of ZL could produce a qualified rough concentrate.The atomic force microscope(AFM)tests showed that after desorption treatment of low temperature and strong stirring,the dense strip-like structure of NaOL on the scheelite surface was destroyed to be speck-like.Molecular dynamics simulations(MDS)demonstrated that the adsorption energy between NaOL and scheelite surface was more negative at 25℃(-13.39 kcal/mol)than at 5℃(-11.50 kcal/mol)in a neutral pH,indicating that a low temperature was beneficial for the desorption of collector from mineral surface.Due to its simplicity and economy,the method we proposed of desorption of collector from mineral surface and its reuse for flotation has a great potential for industrial application.
文摘The Nome nickel laterite deposit is located in the North East of Albania. The ore deposit, developed between ultramafic rocks and limestones during Early Cretaceous to Eocene, represents part of the Albanian Mirdita ophiolite zone. The lateritization of the deposit was observed mainly in three separate areas, the Has-Kukes-Lure in the North, Pogradec-Librazhd in the center and Devoll in the South. The main mineralogical components of the ore are goethite, hematite and quartz, while the secondary ones are chlorite (clinochlore, Ni-chlorite), kaolinite and lizardite. Nickel is mainly found in chlorite. The ore is characterized by the presence of spheroid particles, such as oval, pisoid, peloid and composite spheroid. According to the microscopical examination the ore is characterized in general as allotriomorphic, inequigranular and the texture is oolitic-pisolitic. For the mineral processing gravimetric and magnetic separation are used in the size fractions NJ + 4 mm, dž + 1 mm, ǃ + 0.250 mm and ǂ.250 + 0.063 mm. The chemical and mineralogical analyses, as well as the microscopic examination have shown that mineral processing by magnetic separation gives the most satisfactory results for the size fractions ǃ + 0.250 mm and ǂ.250 + 0.063 mm.
文摘Process engineering has been seen as one of the vital tools for improving surface coating phenomena for advance application. In an attempt to improve the mechanical, physical and chemical performance of the steel structure for ex-tended application, Zn-CeO2/ZnCeO2-Al2SiO5 thin film composite was fabri-cated on mild steel using direct electrolytic route. Process variation of Al2SiO5 particulate ranges from 5 to 15 g per litre. The embedded coating was charac-terized using Scanning electron microscope (SEM). The chemical effect of the developed alloy was characterized through linear potentiodynamic polarization experiment and the performances of samples were examined in simulated 3.5% sodium chloride. The microhardness verification study proves that there is sig-nificant improvement in hardness trend. The tribological assessment indicated that there is less plastic deformation as a result of the counter body. In all, Zn-CeO2/Zn-CeO2-Al2SiO5 exhibits good stability, with agglomeration and great built up of crystal at the interface.
基金supported by the Centre for Advanced Modelling and Geospatial Information Systems(CAMGIS),University of Technology Sydney(UTS),Australia and was supported by the Research Training Program(RTP)of the Australian Government.
文摘Hurricanes are one of the most destructive natural disasters that can cause catastrophic losses to both communities and infrastructure.Assessment of hurricane risk furnishes a spatial depiction of the interplay among hazard,vulnerability,exposure,and mitigation capacity,crucial for understanding and managing the risks hurricanes pose to communities.These assessments aid in gauging the efficacy of existing hurricane mitigation strategies and gauging their resilience across diverse climate change scenarios.A systematic review was conducted,encompassing 94 articles,to scrutinize the structure,data inputs,assumptions,methodologies,perils modelled,and key predictors of hurricane risk.This review identified key research gaps essential for enhancing future risk assessments.The complex interaction between hurricane perils may be disastrous and underestimated in the majority of risk assessments which focus on a single peril,commonly storm surge and flood,resulting in inadequacies in disaster resilience planning.Most risk assessments were based on hurricane frequency rather than hurricane damage,which is more insightful for policymakers.Furthermore,considering secondary indirect impacts stemming from hurricanes,including real estate market and business interruption,could enrich economic impact assessments.Hurricane mitigation measures were the most under-utilised category of predictors leveraged in only 5%of studies.The top six predictive factors for hurricane risk were land use,slope,precipitation,elevation,population density,and soil texture/drainage.Another notable research gap identified was the potential of machine learning techniques in risk assessments,offering advantages over traditional MCDM and numerical models due to their ability to capture complex nonlinear relationships and adaptability to different study regions.Existing machine learning based risk assessments leverage random forest models(42%of studies)followed by neural network models(19%of studies),with further research required to investigate diverse machine learning algorithms such as ensemble models.A further research gap is model validation,in particular assessing transferability to a new study region.Additionally,harnessing simulated data and refining projections related to demographic and built environment dynamics can bolster the sophistication of climate change scenario assessments.By addressing these research gaps,hurricane risk assessments can furnish invaluable insights for national policymakers,facilitating the development of robust hurricane mitigation strategies and the construction of hurricane-resilient communities.To the authors’knowledge,this represents the first literature review specifically dedicated to quantitative hurricane risk assessments,encompassing a comparison of Multi-criteria Decision Making(MCDM),numerical models,and machine learning models.Ultimately,advancements in hurricane risk assessments and modelling stand poised to mitigate potential losses to communities and infrastructure both in the immediate and long-term future.
基金funded by the Project of Yunnan Province’s Xingdian Talents Support Program(yfgrc202437)the Project of the International Cooperation Science Program of National Natural Science Foundation of China(42361144885).
文摘Phosphorus(P)poses a global challenge to the environment and human health due to its natural association with heavy metals.Sustainable use of P is crucial to ensure food security for future generations.An analysis of the 150 phosphate fertilizers stored at the Institute for Crop and Soil Science in Germany has been conducted,supplemented by previously published data.The elements Cd,Bi,U,Cr,Zn,Tl,As,B,Sb,Ni,and Se are found in higher concentrations in sedimentary derived phosphates compared to igneous derived phosphates.Mineral fertilizers contain more than ten times the amount of U,Cd,B,and As compared to farmyard manure.Principal component analyses(PCA)indicate that U,Cd,Be,and Cr are primarily present in sedimentary derived phosphates and their concentrations are 2 to 10 times higher than those in igneous derived phosphates.Regarding heavy metal contamination,over 1000 potential combinations were identified;36% of these were significant but weak(>0.1).It is estimated that approximately 707 t of uranium enter farmland annually through the application of mineral phosphate fertilizers in European countries.This contribution addresses environmental issues related to the utilization of rock phosphate as well as alternative production methods for cleaner and safer phosphate fertilizers while presenting a roadmap with measures for mitigation.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2023-00254424)by the ITRC(Information Technology Research Center)support program(IITP-2024-RS-2024-00437494)supervised by the IITP(Institute for Information&Communications Technology Planning&Evaluation)funded by the MSIT(Ministry of Science and ICT),Korea。
文摘It is of great importance to explore sustainable and eco-friendly recycling strategies for spent Li-ion batteries(LIBs).As such,the closed-loop resynthesis of LiNi_(x)CoyMn_(z)O_(2)(NCM)becomes recently popular as exemplified by the commercialization of low-and mid-Ni content NCM(33%-60%).However,there has been suspicion as to the successful deployment of Ni-rich NCM resynthesis process.Therefore,we systematically increase the Ni content of NCM from 60%to 90%from the industrial leachate of spent LIBs containing various metallic and nonmetallic impurities.The utilization rate of the leachate decreases from 71.8 mol%for NCM622 to 18.0 mol%for NCM955 as the Ni content in the NCM composition increases with the Co recycling rate being 100%in all resynthesized NCM(RNCM).The physicochemical and electrochemical properties of RNCM are systematically compared with its pristine NCM counterparts.As a result,various physicochemical properties of RNCM including impurity content,crystallographic information,morphology,particle size,porosity,specific surface area,elemental distribution,residual lithium compounds,and thermal stability are correlated with its electrochemical properties.It is found out that Al is the most critical impurity that determines the physicochemical and electrochemical properties of RNCM.It is noteworthy that RNCM955 prepared from spent LIBs without any purification step surpasses NCM955 in terms of rate and cycle performance.Further,this resynthesis approach toward Nirich NCM could meet the forthcoming 2031 EU's legislative target on the mandatory minimum recycling usage of valuable metals from spent LIBs.The anode active material was resynthesized using industrial leachate as the maximum.The amount of leachate used and the amount of impurities were proportional.
基金supported by Ministry of Higher Education,Malaysia,through the Fundamental Research Grant Scheme(FRGS)(Grant No.FRGS/1/2020/TK0/USM/02/27)。
文摘The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment.This study presented a rapid and cost-effective direct heating method for synthesizing MnO_(2) nanoflowers on coil substrates for the removal of organic pollutants.Traditional methods often require high power,expensive equipment,and long synthesis times.In contrast,the direct heating approach successfully synthesized MnO_(2) nanoflowers in just 10 min with a heating power of approximately 40 W·h after the heating power and duration were optimized.These nanoflowers effectively degraded 99%Rhodamine B in 60 min with consistent repeatability.The catalytic mechanisms are attributed to crystal defects in MnO_(2),which generate electrons to produce H_(2)O_(2).Mn6(2+)ions in the acidic solution further dissociate H_(2)O_(2) molecules into hydroxyl radicals(·OH).The high efficiency of this synthesis method and the excellent reusability of MnO_(2) nanoflowers highlight their potential as a promising solution for the development of supporting MnO_(2) catalysts for organic dye removal applications.
基金Ministry of Science and Higher Education of the Russian Federation,Grant/Award Number:FSNM-2024-0005Korea Institute of Energy Technology Evaluation and Planning,Grant/Award Number:20225B10300080Yayasan UTP,Grant/Award Number:015LC0-526。
文摘Carbon capture and storage(CCS)remains one of the most feasible techniques for the control of Greenhouse gas emission levels.However,there will always be risks attached to the subsurface injection of CO_(2).These could be in the form of leakages from the injection wellbore due to completion failure;escape of the injected CO_(2)to neighboring aquifers due to the heterogeneous or fractured nature of the storage site;or seepage at the surface due to inadequacy of the sealing cap rock.While all these may occur,the most cost-effective and timely way to reduce the risk of leakages is by plugging the pathways.This is done using either traditional Cementous materials or more augmented sealants like organic gels and resins.A lot of studies in the literature have described this collection of materials within the context of CO_(2)conformance control.So also,there are reviews on the classification and description of these chemicals.This review provides a more systemic evaluation of these classes of chemicals.This is by providing critical analyses of how external factors like CO_(2),pH,brine salinity and hardness,rock mineralogy,pressure,temperature,and injectivity could affect the performance of different sealants that can be utilized.Based on these assessments,best practices for the application of the sealants,both at the testing stage in the laboratory and the pilot stage and field deployment,are suggested.
基金funded by the Ministry of Higher Education Malaysia for the Prototype Research Grant Scheme(PRGS)with Project Code PRGS/1/2021/SKK07/USM/02/1.
文摘Objective This study aimed to evaluate the potential of a collagen-coated,3D-printed tracheal scaffold(3D-TechTra)integrated with human umbilical cord mesenchymal stem cells(hUC-MSCs)for tracheal tissue regeneration.Methods The thermoplastic polyurethane/polylactic acid(TPU/PLA)scaffold was engineered to optimize mechanical properties and biocompatibility,with the goal of mimicking the structural and tensile characteristics of native tracheal tissue.Subsequently,preclinical experiments were conducted using rabbit models:the performance of the collagen-coated TPU/PLA scaffold with hUC-MSCs was compared with that of uncoated scaffolds and collagen-only scaffolds.In vitro tests were also performed to assess the adhesion,proliferation,and differentiation of hUC-MSCs on the scaffold.For in vivo evaluation,multiple analytical methods were employed,including immunohistological analysis(to detect glycosaminoglycan deposition and extracellular matrix remodeling),radiographic and endoscopic evaluations(to assess tracheal contour and airway obstruction),and survival analysis(to monitor animal outcomes and systemic toxicity).Results In vitro,hUC-MSCs successfully adhered to and proliferated on the TPU/PLA scaffold,and differentiated into adipogenic,osteogenic,and chondrogenic lineages,which supported the potential for tissue-specific regeneration;in vivo,compared with uncoated or collagen-only scaffolds,the collagen-coated TPU/PLA scaffold integrated with hUC-MSCs exhibited enhanced integration with host tissues,superior biocompatibility,and reduced tracheal stenosis,while also preserving airway patency,alleviating inflammation,and facilitating epithelial regeneration,smooth muscle formation,and vascularization.Immunohistological analysis further revealed significant glycosaminoglycan deposition and extracellular matrix remodeling in the hUC-MSC-treated group,and radiographic and endoscopic evaluations confirmed preserved tracheal contour and reduced airway obstruction;additionally,survival analysis showed significantly improved outcomes in animals treated with the collagen-coated TPU/PLA scaffold containing hUC-MSCs,with no systemic toxicity observed.Conclusions This study demonstrated the synergistic potential of TPU/PLA scaffolds,collagen coatings,and hUC-MSCs,providing valuable evidence for advancing the application of these components in tracheal tissue engineering.
文摘Digitalisation in mining refers to the use of computerised or digital devices or systems and digitised data that are to reduce costs,improve business productivity,and transform mining practices.However,it remains increasingly difficult for mining companies to decide which digital technologies are most relevant to their needs and individual mines.This paper provides an overview of digital technologies currently relevant to mining companies as presented and discussed by mining journals,the media and insight reports of leading consultancy agencies.Relevant technologies were systematically identified using text-mining techniques,and network analyses established the relations between significant technologies.Results demonstrated that currently 107 different digital technologies are pursued in the mining sector.Also,an analysis of the actual implementation of digital technologies in 158 active surface and underground mines reveals a limited uptake of digital technologies in general and that the uptake increases with the run-of-mine production.Large-scale mining operations appear to select and apply digital technologies suitable to their needs,whereas operations with lower production rates do not implement the currently available digital technologies to the same extent.These minor producers may require other digital transformation solutions tailored to their capabilities and needs and applicable to their scale of operations.
基金supported by the Centre for Advanced Modelling and Geospatial Information Systems(CAMGIS),UTS under grant numbers 321740.2232335,323930,and 321740.2232357
文摘In this study, a novel approach of the landslide numerical risk factor(LNRF) bivariate model was used in ensemble with linear multivariate regression(LMR) and boosted regression tree(BRT) models, coupled with radar remote sensing data and geographic information system(GIS), for landslide susceptibility mapping(LSM) in the Gorganroud watershed, Iran. Fifteen topographic, hydrological, geological and environmental conditioning factors and a landslide inventory(70%, or 298 landslides) were used in mapping. Phased array-type L-band synthetic aperture radar data were used to extract topographic parameters. Coefficients of tolerance and variance inflation factor were used to determine the coherence among conditioning factors. Data for the landslide inventory map were obtained from various resources, such as Iranian Landslide Working Party(ILWP), Forestry, Rangeland and Watershed Organisation(FRWO), extensive field surveys, interpretation of aerial photos and satellite images, and radar data. Of the total data, 30% were used to validate LSMs, using area under the curve(AUC), frequency ratio(FR) and seed cell area index(SCAI).Normalised difference vegetation index, land use/land cover and slope degree in BRT model elevation, rainfall and distance from stream were found to be important factors and were given the highest weightage in modelling. Validation results using AUC showed that the ensemble LNRF-BRT and LNRFLMR models(AUC = 0.912(91.2%) and 0.907(90.7%), respectively) had high predictive accuracy than the LNRF model alone(AUC = 0.855(85.5%)). The FR and SCAI analyses showed that all models divided the parameter classes with high precision. Overall, our novel approach of combining multivariate and machine learning methods with bivariate models, radar remote sensing data and GIS proved to be a powerful tool for landslide susceptibility mapping.
基金funded by the Malaysian Ministry of Higher Education under the Fundamental Research Grant Scheme(Project Code FRGS/1/2018/TK05/USM/01/5)the first author is supported financially by a scholarship from Universiti Sains Malaysia(USM Fellowship)。
文摘Titanium and its alloys have long been used as implant materials due to their outstanding mechanical properties and apparent biocompatibility.Despite this,the search for better alloys has continued to be active by researchers and industries alike,as there are still pressing issues that require attention.These include(1)a large mismatch in the elastic modulus of the implant material,which causes a stress shielding problem;(2)the release of harmful ions from Ti alloys after long-term use;(3)a low bioactivity of the Ti alloy surface,which prolongs the healing process.More research has been directed toward finding new generation Ti alloys composed of more biocompatible phases and modifying the surface of Ti alloys from naturally bio-inert to bioactive in order to circumvent the problems.This review examines recent work reported on the fabrication of Ti alloys,and based on the survey,major characteristics highlighted the importance of elastic modulus and the use of non-toxic metal elements to improve biocompatibility.In terms of surface modification of Ti alloys,numerous studies have found that a nano-scaled surface oxide layer grown on the surface is always beneficial to improving the bioactivity of Ti alloys for rapid recovery after implantation.This comprehensive review focuses on the appropriate phase and composition for new Ti alloys intended for use as biomedical implants,emphasizing both fabrication and surface modification methods.
基金authors sincere acknowledge the funding support by the Illinois Clean Coal Institute and the Department of Commerce and Economic Opportunitythe support at the coop-erating mines for providing high quality data included in this paper
文摘This paper provides an overview of coal waste management practices with two case studies and an estimate of management cost in 2010 US dollars.Processing of as-mined coal typically results in considerable amount of coarse and fine coal processing wastes because of in-seam and out-of-seam dilution mining.Processing plant clean coal recovery values run typically 50%-80%.Trace metals and sulfur may be present in waste materials that may result in leachate water with corrosive characteristics.Water discharges may require special measures such as liner and collection systems,and treatment to neutralize acid drainage and/or water quality for trace elements.The potential for variations in coal waste production and quality depends upon mining or processing,plus the long-term methods of waste placement.The changes in waste generation rates and engineering properties of the coal waste during the life of the facility must be considered.Safe,economical and environmentally acceptable management of coal waste involves consideration of geology,soil and rock mechanics,hydrology,hydraulics,geochemistry,soil science,agronomy and environmental sciences.These support all aspects of the regulatory environment including the design and construction of earth and rock embankments and dams,as well as a wide variety of waste disposal structures.Development of impoundments is critical and require considerations of typical water-impounding dams and additional requirements of coal waste disposal impoundments.The primary purpose of a coal waste disposal facility is to dispose of unusable waste materials from mining.However,at some sites coal waste impoundments serve to provide water storage capacity for processing and flood attenuation.
基金the funding (UniversityIndustry Engagement Grant)support provided by the Universiti Sains Malaysia under the Teaching Fellowship Scheme
文摘Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aerospace industry.The microstructure and mechanical properties of the weldments were also investigated.Relationships between the parameters and weld bead geometry were found.High quality weld joints without solidification crack that met AWS D17.1 requirements were obtained at(I)high pulse energy(25 J)and high average peak power(4.2 kW)and(II)low pulse energy(17.6 J)and low average peak power(2.8 kW).The weld joint formed at lower heat energy input exhibited finer dendritic grain structure.Mg vapourisation and hard phase compound(Al0.5Fe3Si0.5)formation decreased in the weld joint formed at lower heat energy input.Consequently,the tensile strength of the weldment formed at lower heat energy input(168 MPa)is by a factor of 1.15 higher but showed^29%decrease in hardness(111 HV0.1)at the joint when being compared with the weldment formed at higher heat energy input.Appropriate parameters selection is critical to obtaining 0.6 mm-thick AA5052-H32 pulse laser weld joints that meet AWS D17.1 requirements for aircraft structures.
基金Project(GJHZ20190822095418365)supported by Shenzhen International Cooperation Research,ChinaProject(2019011)supported by NTUT-SZU Joint Research Program,China+2 种基金Project(2019040)supported by Natural Science Foundation of Shenzhen University,ChinaProject(JCYJ20190808144009478)supported by Shenzhen Fundamental Research Fund,ChinaProject(ZDYBH201900000008)supported by Shenzhen Bureau of Industry and Information Technology,China。
文摘Selective laser melting(SLM)is an emerging layer-wise additive manufacturing technique that can generate complex components with high performance.Particulate-reinforced aluminum matrix composites(PAMCs)are important materials for various applications due to the combined properties of Al matrix and reinforcements.Considering the advantages of SLM technology and PAMCs,the novel SLM PAMCs have been developed and researched in recent years.Therefore,the current research progress about the SLM PAMCs is reviewed.Firstly,special attention is paid to the solidification behavior of SLM PAMCs.Secondly,the important issues about the design and fabrication of high-performance SLM PAMCs,including the selection of reinforcement,the influence of parameters on the processing and microstructure,the defect evolution and phase control,are highlighted and discussed comprehensively.Thirdly,the performance and strengthening mechanism of SLM PAMCs are systematically figured out.Finally,future directions are pointed out on the advancement of high-performance SLM PAMCs.
基金Project(51404248)supported by the National Natural Science Foundation of the Youth Science Foundation of ChinaProject(2017XKQY012)supported by Fundamental Research Funds for the Central Universities of ChinaProject(2014M551702)supported by the China Postdoctoral Science Foundation
文摘Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extremely thick coal seams because the control mechanism of the system for the deformation of the roof and the separation between coal rock segments is not completely understood. By using the relationship between the support system and the roof strata, a mechanical model was established to calculate the deformation of the roof in a thick coal seam with bedding separation under different support conditions: with an anchor truss support and without support. On this basis, the research was used to deduce a method for computing the minimum pre-tightening forces in the anchor truss, the maximum amounts of subsidence and separation with, and without, anchor truss support under the roof, and the maximum subsidence and the decreasing amounts of the separation before and after adopting the anchor truss. Additionally, mechanical relationships between the minimum pre-tightening force and the anchoring force in the anchor were analyzed. By taking a typical roadway with thick coal roof as an example, the theoretical results mentioned above were applied in the analysis and testing of a roof supporting project in a roadway field to verify the accuracy of the theory: favorable experimental results were achieved. In addition, the relationships among other parameters were analyzed, including the minimum pre-tightening forces applied by the anchor truss, the angle of inclination of the anchor cable, and the array pitch. Meanwhile, the changing characteristics of the amounts of roof separation and subsidence with key parameters of the support system(such as array pitch, pre-tightening force, and inclination angle) were also analyzed. The research results revealed the acting mechanism of the anchor truss in control of roadway stability with a thick coal seam, providing a theoretical basis of its application in coal mining.
基金the Science and Technology authority of Taiwan, China, for financially supporting this research under Grant No.NSC 102-2221-E-027-071-MY3
文摘Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the incident bar of an SHPB apparatus is used to absorb some of the shock energy. This can generate loading rates of 20.2-4627.3 GPa/s, enabling dynamic peak stresses/strengths and associated failure patterns of the specimens to be investigated. The effects of the loading rate and angle of load applied on the dynamic peak stresses/strengths of the specimens are examined. Relevant experimental results demonstrate that the failure pattern of each specimen can be classified as four types： Type A, integrated with or without tiny flake-off; Type B, slide failure; Type C, fracture failure; and Type D, crushing failure. The dynamic peak stresses/strengths of the specimens that have similar failure patterns increase linearly with the loading rate, yielding high correlations that are evident on semi-logarithmic plots. The slope of the failure envelope is the smallest for slide failure, followed by crushing failure, and that of fracture failure is the largest. The magnitude of the plot slope of the dynamic peak stress against the loading rate for the specimens that are still integrated after testing is between that of slide failure and crushing failure. The angle of application has a limited effect on the dynamic peak stresses/strengths of the specimens regardless of the failure pattern, but it affects the bounds of the loading rates that yield each failure pattern, and thus influences the dynamic responses of the single jointed specimen. Slide failure occurs at the lowest loading rate of any failure, but can only occur in single jointed specimen that allows sliding.Crushing failure is typically associated with the largest loading rate, and fracture failure may occur when the loading rate is between the boundaries for slide failure and crushing failure.
基金Project(2014QNA50) supported by Fundamental Research Funds for the Central Universities,ChinaProject(51404248) supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development(PAPD) of Jiangsu Higher Education Institutions,China
文摘The installation of a back-wall guard-board is the key to successfully supporting underground retreating roadways in coal mines. Based on the coordinate support principle, and using an I-shaped steel support for the surrounding rock, a mechanical model was developed for the stability of the roadway support and surrounding rock. Analysis of the bearing capacity of the roof back-wall guard-board and modelling of the equations for the maximum deflection and the maximum compressive stress of the top and side beams of the I-shaped steel support were undertaken. Simultaneously, the model was used to calculate and analyse the stability of the top and side beams of the I-shaped steel support structure and analyse the criteria for their stability. The results provide a reliable theoretical basis for the judgment of the stability of the surrounding rock and support structure. The theoretical evaluation results are consistent with field data. Finally, the key support parameters of the top and side beams of the I-shaped steel support structure and the variation of the maximum deflection and the maximum compressive stress as affected by the influence of the guard-board length were investigated. It is concluded that, as the back-board length increases, the maximum compressive stress in the top beam of the I-shaped steel support increases while the compressive stress in the side beam decreases. The results show that the accuracy of judgment of the stability of a supported retreating roadway is improved, providing guidance for the design of such typical I-shaped steel support and back-board structures.
基金This research is funded by the Centre for Advanced Modeling and Geospatial Information Systems(CAMGIS),Faculty of Engineering and Information Technology,the University of Technology Sydney,Australia.
文摘In recent years,landslide susceptibility mapping has substantially improved with advances in machine learning.However,there are still challenges remain in landslide mapping due to the availability of limited inventory data.In this paper,a novel method that improves the performance of machine learning techniques is presented.The proposed method creates synthetic inventory data using Generative Adversarial Networks(GANs)for improving the prediction of landslides.In this research,landslide inventory data of 156 landslide locations were identified in Cameron Highlands,Malaysia,taken from previous projects the authors worked on.Elevation,slope,aspect,plan curvature,profile curvature,total curvature,lithology,land use and land cover(LULC),distance to the road,distance to the river,stream power index(SPI),sediment transport index(STI),terrain roughness index(TRI),topographic wetness index(TWI)and vegetation density are geo-environmental factors considered in this study based on suggestions from previous works on Cameron Highlands.To show the capability of GANs in improving landslide prediction models,this study tests the proposed GAN model with benchmark models namely Artificial Neural Network(ANN),Support Vector Machine(SVM),Decision Trees(DT),Random Forest(RF)and Bagging ensemble models with ANN and SVM models.These models were validated using the area under the receiver operating characteristic curve(AUROC).The DT,RF,SVM,ANN and Bagging ensemble could achieve the AUROC values of(0.90,0.94,0.86,0.69 and 0.82)for the training;and the AUROC of(0.76,0.81,0.85,0.72 and 0.75)for the test,subsequently.When using additional samples,the same models achieved the AUROC values of(0.92,0.94,0.88,0.75 and 0.84)for the training and(0.78,0.82,0.82,0.78 and 0.80)for the test,respectively.Using the additional samples improved the test accuracy of all the models except SVM.As a result,in data-scarce environments,this research showed that utilizing GANs to generate supplementary samples is promising because it can improve the predictive capability of common landslide prediction models.
