The application of hydrogen gas in the pre-reduction of manganese ore may replace fossil carbon consumption and reduce CO_(2) emissions in manganese ferroalloy production.The pre-reduction behavior of Nchwaning mangan...The application of hydrogen gas in the pre-reduction of manganese ore may replace fossil carbon consumption and reduce CO_(2) emissions in manganese ferroalloy production.The pre-reduction behavior of Nchwaning manganese ore was investigated using a fixed-bed reactor.The reduction rates at different temperatures and temperature programs were investigated,and the particles were sieved after reduction to measure the decrepitation.The reduction rate was measured by adding a tracer gas to the reducing gas and quantifying the off-gas.Samples with different particle-size distributions of the input material were reduced to investigate the effect of particle size on the reduction rate.Chemical analyses and X-ray diffraction were used to characterize the raw and reduced materials.The effects of particle size distribution and temperature on the oxygen removal rate were investigated.Manganese oxides were mostly reduced to MnO in the samples,whereas some iron oxides and carbonates remained.The degree of reduction was improved by using smaller particles and in-creasing the temperature.展开更多
During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a nu...During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a numerical model is developed to simulate the effects of repeated loading on rock fatigue and failure.The simulation is based on an elasto-plastic constitutive model coupled with a damage mechanics approach,which allows us to examine the wellbore instability due to drill string vibrations.The model is verified with the existing data in the literature related to experiments on impact of a steel ball against a curved wall.The findings indicate that cyclic loading increases the development of plastic strain around the wellbore significantly compared to static conditions,promoting rock fatigue.Furthermore,the cyclic loading expands the radius of the yielded zone substantially,a critical factor for maintaining wellbore integrity.The proposed model can be used to evaluate the wellbore stability under repetitive loading caused by the drill string action.展开更多
The authors(Cai et al.,2022)claim that their proposed machine learning(ML)models,which are based on three typical ML algorithms and are trained to predict the burst capacity of pitting corroded pipelines,perform bette...The authors(Cai et al.,2022)claim that their proposed machine learning(ML)models,which are based on three typical ML algorithms and are trained to predict the burst capacity of pitting corroded pipelines,perform better than the existing semi-empirical formulas recommended by the international engineering code developers,DNV and ASME.The authors’assessments of the semi-empiri‐cal burst capacity formulas in Figure 10(a)and Table 8(Cai et al.,2022)incorrectly indicate that DNVGL-RP F101,ASME B31G,and modified ASME B31G are dan‐gerously unsafe due to significantly overestimating burst pressures in several cases.In contrast to the results and conclusions in Cai et al.展开更多
Due to global warming and diminishing ice cover in Arctic regions,the northern sea route(NSR)has attracted increasing attention in recent years.Extreme cold temperatures and high wind speeds in Arctic regions present ...Due to global warming and diminishing ice cover in Arctic regions,the northern sea route(NSR)has attracted increasing attention in recent years.Extreme cold temperatures and high wind speeds in Arctic regions present substantial risks to vessels operating along the NSR.Consequently,analyzing extreme temperature and wind speed values along the NSR is essential for ensuring maritime operational safety in the region.This study analyzes wind and temperature data spanning 40 years,from 1981 to 2020,at four representative sites along the NSR for extreme value analysis.The average conditional exceedance rate(ACER)method and the Gumbel method are employed to estimate extreme wind speed and air temperature at these sites.Comparative analysis reveals that the ACER method provides higher accuracy and lower uncertainty in estimations.The predicted extreme wind speed for a 100-year return period is 30.36 m/s,with a minimum temperature of-56.66°C,varying across the four sites.Furthermore,the study presents extreme values corresponding to each return period,providing temperature extremes as a basis for guiding steel thickness specifications.These findings provide valuable reference for designing polar vessels and offshore structures,contributing to enhanced engineering standards for Arctic conditions.展开更多
In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the format...In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the formation of the planar defects in the high pressure torsion （HPT） alloys was conducted using high-resolution transmission electron microscopy （HRTEM）. The results show that high density defects in the HRTEM images disappear completely when these images are exposed under the electron beam for some duration of time. At the same time, lattice defects are never observed within no-defect areas even when the beam-exposure increases to the degree that holes appear in the areas. Therefore, it is confirmed that the planar defects observed in the HPT alloys mainly result from the significant plastic deformation and are not due to the radiation effect during HRTEM observation.展开更多
1、能否简单谈下您的职业教育经历？学生时期,对您影响最大的教师是谁？对您影响最大的一门课是什么？为什么？Could you briefly talk about your professional education backgrounds？Who was your most memorable professor？Which ...1、能否简单谈下您的职业教育经历？学生时期,对您影响最大的教师是谁？对您影响最大的一门课是什么？为什么？Could you briefly talk about your professional education backgrounds？Who was your most memorable professor？Which course influenced you most when you were a college student and why？我是1984年本科毕业,本来在那个时候（中国改革开放初期）,是希望直接下到市场上做设计,但是被学校强制性留校,当时非常郁闷。留校以后其实就是所有的工作都变得比较常规,教书、做设计,开始实际上没有什么设计。展开更多
1、学生时期,对您影响最大的教师是谁？对您影响最大的一门课是什么？为什么？作为教师,您最喜欢的一门课是什么？为什么？Who was your most memorable professor？Which course influenced you most when you were a college student ...1、学生时期,对您影响最大的教师是谁？对您影响最大的一门课是什么？为什么？作为教师,您最喜欢的一门课是什么？为什么？Who was your most memorable professor？Which course influenced you most when you were a college student and why？As a teacher,which is your most preferred course and why？因为我从小喜欢画画,总觉得建筑和造型、艺术有关,但后来学了建筑学专业以后,发现并不完全像自己想象的那样,因为建筑毕竟不是纯粹的一种艺术造型,其中还蕴含着人的使用行为。展开更多
With the global warming of concern,the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits.In this work,re...With the global warming of concern,the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits.In this work,recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling,use of aluminum alloys in automotive applications,automotive recycling process,and new technologies in aluminum scrap process.Literature survey shows that newly developed techniques such as laser induced breakdown spectroscopy(LIBS) and solid state recycling provide promising alternatives in aluminum scrap process.Compared with conventional remelting and subsequent refinement,solid state recycling utilizing compression and extrusion at room or moderate temperature can result in significant energy savings and higher metal yield.展开更多
This paper presents the principles of rock support for rockburst control and three rockburst support systems used in deep metal mines.Before the principles of rock support are presented,rock fracture related to strain...This paper presents the principles of rock support for rockburst control and three rockburst support systems used in deep metal mines.Before the principles of rock support are presented,rock fracture related to strain burst is first discussed with the help of photos taken on site,and the energy sources and transformations during bursting are illustrated through conceptual models.Surface parallel extension fracture usually occurs in the ejected and surrounding rocks in a strain burst event,while the ejected rock in a fault-slip rockburst is often already pre-fractured before the event.There must be excessive release energy available for rock ejection.The excessive release energy comes from both the ejected rock itself and the surrounding rock.To prevent rock ejection in a rockburst,the support system must be able to dissipate the excessive release energy.All support devices in a support system for rockburst control must be able to dissipate energy,be firmly linked,and be compatible in deformability.A support system for rockburst control comprises surface-retaining devices and yield rockbolts as well as yield cablebolts when needed.Laying mesh on the top of shotcrete liner is a good practice to enhance the surfaceretaining capacity of the support system.Energy-absorbing yield rockbolts dissipate energy either by stretching of the bolt shank or by sliding of the inner anchor in the borehole.Mesh,mesh strap and shotcrete are the surface-retaining devices widely used in the current rock support systems.The three types of rock support used for rockburst control at present are soft support system using Split Set bolts,hybrid support system using rebar and two-point anchored yield bolts,and entirely yieldable support system using strong yield bolts.展开更多
Recent new technology developments were presented in the field of industrial bending operations,including flexible stretch forming and 3D rotary stretch forming.Attempts were made to give an overview of different mech...Recent new technology developments were presented in the field of industrial bending operations,including flexible stretch forming and 3D rotary stretch forming.Attempts were made to give an overview of different mechanisms that influence dimensional accuracy,including local cross-sectional deformations such as suck-in and volume conservation effects,along with global deformations such as springback.An analytical model was developed to determine the particular influence of different material,geometry and process parameters on dimensional variability of bent components.The results were discussed in terms of overall process capability(Cp) and associated process windows.The results show that different governing mechanisms prevail in various bending operations,meaning that attention has to be placed on controlling those process parameters that really are important to part quality in each specific case.Several strategies may be defined for reducing variability.One alternative may be to design more robust process and tool technology that reduce the effect of upstream parameters on dimensional variability of the formed part.The results show that optimal tool design and technology may in specific cases improve the dimensional accuracy of a formed part.Based on the findings discussed herein,it is concluded that advances in industrial bending operations require focus on improving the understanding of mechanical mechanisms,including models and parameter development,new technology developments,including process,tool,measurement and control capabilities,and process discipline at the shop floor,combined with a basic philosophy of controlling process parameters rather than part attributes.展开更多
基金supported by the European Union’s Horizon Europe program HAlMan project under the grant number of 101091936.
文摘The application of hydrogen gas in the pre-reduction of manganese ore may replace fossil carbon consumption and reduce CO_(2) emissions in manganese ferroalloy production.The pre-reduction behavior of Nchwaning manganese ore was investigated using a fixed-bed reactor.The reduction rates at different temperatures and temperature programs were investigated,and the particles were sieved after reduction to measure the decrepitation.The reduction rate was measured by adding a tracer gas to the reducing gas and quantifying the off-gas.Samples with different particle-size distributions of the input material were reduced to investigate the effect of particle size on the reduction rate.Chemical analyses and X-ray diffraction were used to characterize the raw and reduced materials.The effects of particle size distribution and temperature on the oxygen removal rate were investigated.Manganese oxides were mostly reduced to MnO in the samples,whereas some iron oxides and carbonates remained.The degree of reduction was improved by using smaller particles and in-creasing the temperature.
基金funded by the Research council of Norway,Equinor and Sekal with NFR(Grant No.308826).
文摘During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a numerical model is developed to simulate the effects of repeated loading on rock fatigue and failure.The simulation is based on an elasto-plastic constitutive model coupled with a damage mechanics approach,which allows us to examine the wellbore instability due to drill string vibrations.The model is verified with the existing data in the literature related to experiments on impact of a steel ball against a curved wall.The findings indicate that cyclic loading increases the development of plastic strain around the wellbore significantly compared to static conditions,promoting rock fatigue.Furthermore,the cyclic loading expands the radius of the yielded zone substantially,a critical factor for maintaining wellbore integrity.The proposed model can be used to evaluate the wellbore stability under repetitive loading caused by the drill string action.
文摘The authors(Cai et al.,2022)claim that their proposed machine learning(ML)models,which are based on three typical ML algorithms and are trained to predict the burst capacity of pitting corroded pipelines,perform better than the existing semi-empirical formulas recommended by the international engineering code developers,DNV and ASME.The authors’assessments of the semi-empiri‐cal burst capacity formulas in Figure 10(a)and Table 8(Cai et al.,2022)incorrectly indicate that DNVGL-RP F101,ASME B31G,and modified ASME B31G are dan‐gerously unsafe due to significantly overestimating burst pressures in several cases.In contrast to the results and conclusions in Cai et al.
基金supported by the National Natural Science Foundation of China(Grant No.52201379)the Fundamental Research Funds for the Central Universities(Grant No.WUT:3120622898)+2 种基金State Key Laboratory of Structural Analysis,Optimization and CAE Software for Industrial Equipment,Dalian University of Technology(Grant No.GZ 231088)Shanghai Key Laboratory of Naval Architecture Engineering(Grant No.SE202305)funded by European Research Council project under the European Union’s Horizon 2020 research and innovation program(Grant No.TRUST CoG 2019864724).
文摘Due to global warming and diminishing ice cover in Arctic regions,the northern sea route(NSR)has attracted increasing attention in recent years.Extreme cold temperatures and high wind speeds in Arctic regions present substantial risks to vessels operating along the NSR.Consequently,analyzing extreme temperature and wind speed values along the NSR is essential for ensuring maritime operational safety in the region.This study analyzes wind and temperature data spanning 40 years,from 1981 to 2020,at four representative sites along the NSR for extreme value analysis.The average conditional exceedance rate(ACER)method and the Gumbel method are employed to estimate extreme wind speed and air temperature at these sites.Comparative analysis reveals that the ACER method provides higher accuracy and lower uncertainty in estimations.The predicted extreme wind speed for a 100-year return period is 30.36 m/s,with a minimum temperature of-56.66°C,varying across the four sites.Furthermore,the study presents extreme values corresponding to each return period,providing temperature extremes as a basis for guiding steel thickness specifications.These findings provide valuable reference for designing polar vessels and offshore structures,contributing to enhanced engineering standards for Arctic conditions.
基金Project (50971087) supported by the National Natural Science Foundation of ChinaProject (BK2012715) supported by the Basic Research Program (Natural Science Foundation) of Jiangsu Province, China+1 种基金Project (10371800) supported by the Research Council of Norway under the NEW Light (NEWLIGHT) Metals of the Strategic Area (SA) MaterialsProject (11JDG070) supported by the Senior Talent Research Foundation of Jiangsu University, China
文摘In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the formation of the planar defects in the high pressure torsion （HPT） alloys was conducted using high-resolution transmission electron microscopy （HRTEM）. The results show that high density defects in the HRTEM images disappear completely when these images are exposed under the electron beam for some duration of time. At the same time, lattice defects are never observed within no-defect areas even when the beam-exposure increases to the degree that holes appear in the areas. Therefore, it is confirmed that the planar defects observed in the HPT alloys mainly result from the significant plastic deformation and are not due to the radiation effect during HRTEM observation.
文摘1、能否简单谈下您的职业教育经历？学生时期,对您影响最大的教师是谁？对您影响最大的一门课是什么？为什么？Could you briefly talk about your professional education backgrounds？Who was your most memorable professor？Which course influenced you most when you were a college student and why？我是1984年本科毕业,本来在那个时候（中国改革开放初期）,是希望直接下到市场上做设计,但是被学校强制性留校,当时非常郁闷。留校以后其实就是所有的工作都变得比较常规,教书、做设计,开始实际上没有什么设计。
文摘1、学生时期,对您影响最大的教师是谁？对您影响最大的一门课是什么？为什么？作为教师,您最喜欢的一门课是什么？为什么？Who was your most memorable professor？Which course influenced you most when you were a college student and why？As a teacher,which is your most preferred course and why？因为我从小喜欢画画,总觉得建筑和造型、艺术有关,但后来学了建筑学专业以后,发现并不完全像自己想象的那样,因为建筑毕竟不是纯粹的一种艺术造型,其中还蕴含着人的使用行为。
基金Project(FRINAT) supported by the Research Council of Norway (RCN)
文摘With the global warming of concern,the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits.In this work,recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling,use of aluminum alloys in automotive applications,automotive recycling process,and new technologies in aluminum scrap process.Literature survey shows that newly developed techniques such as laser induced breakdown spectroscopy(LIBS) and solid state recycling provide promising alternatives in aluminum scrap process.Compared with conventional remelting and subsequent refinement,solid state recycling utilizing compression and extrusion at room or moderate temperature can result in significant energy savings and higher metal yield.
文摘This paper presents the principles of rock support for rockburst control and three rockburst support systems used in deep metal mines.Before the principles of rock support are presented,rock fracture related to strain burst is first discussed with the help of photos taken on site,and the energy sources and transformations during bursting are illustrated through conceptual models.Surface parallel extension fracture usually occurs in the ejected and surrounding rocks in a strain burst event,while the ejected rock in a fault-slip rockburst is often already pre-fractured before the event.There must be excessive release energy available for rock ejection.The excessive release energy comes from both the ejected rock itself and the surrounding rock.To prevent rock ejection in a rockburst,the support system must be able to dissipate the excessive release energy.All support devices in a support system for rockburst control must be able to dissipate energy,be firmly linked,and be compatible in deformability.A support system for rockburst control comprises surface-retaining devices and yield rockbolts as well as yield cablebolts when needed.Laying mesh on the top of shotcrete liner is a good practice to enhance the surfaceretaining capacity of the support system.Energy-absorbing yield rockbolts dissipate energy either by stretching of the bolt shank or by sliding of the inner anchor in the borehole.Mesh,mesh strap and shotcrete are the surface-retaining devices widely used in the current rock support systems.The three types of rock support used for rockburst control at present are soft support system using Split Set bolts,hybrid support system using rebar and two-point anchored yield bolts,and entirely yieldable support system using strong yield bolts.
文摘Recent new technology developments were presented in the field of industrial bending operations,including flexible stretch forming and 3D rotary stretch forming.Attempts were made to give an overview of different mechanisms that influence dimensional accuracy,including local cross-sectional deformations such as suck-in and volume conservation effects,along with global deformations such as springback.An analytical model was developed to determine the particular influence of different material,geometry and process parameters on dimensional variability of bent components.The results were discussed in terms of overall process capability(Cp) and associated process windows.The results show that different governing mechanisms prevail in various bending operations,meaning that attention has to be placed on controlling those process parameters that really are important to part quality in each specific case.Several strategies may be defined for reducing variability.One alternative may be to design more robust process and tool technology that reduce the effect of upstream parameters on dimensional variability of the formed part.The results show that optimal tool design and technology may in specific cases improve the dimensional accuracy of a formed part.Based on the findings discussed herein,it is concluded that advances in industrial bending operations require focus on improving the understanding of mechanical mechanisms,including models and parameter development,new technology developments,including process,tool,measurement and control capabilities,and process discipline at the shop floor,combined with a basic philosophy of controlling process parameters rather than part attributes.
