Hanging roofs or high hang-ups.a common problem in sublevel caving mining,usually result in a large ore loss and undermine mining safety.This paper analyzed the formation of a hanging roof and showed that increased co...Hanging roofs or high hang-ups.a common problem in sublevel caving mining,usually result in a large ore loss and undermine mining safety.This paper analyzed the formation of a hanging roof and showed that increased confining pressure and reduced free surface were its main characteristics.In order to break down a hanging roof,a new method based on shock wave collision and stress superposition was developed.In this method,two blastholes containing multi-primer at different positions are simultaneously initiated at first.By doing this,a new free surface and a swell room can be created.After these holes are fired,a long delay time is given to the next blasthole so that the fragments from the first twohole blasting have enough time to fall down.This new method was applied to three hanging roofs in one production area,and all of them were successfully broken down.Field inspection indicated that almost no damage was caused in the nearby drifts/tunnels due to the new method.In addition,the far field vibrations were found to be smaller than the maximum vibrations induced by some other blasts.展开更多
Reduction of energy consumption in comminution is of significant importance in mining industry. To reduce such energy consumption the energy efficiency in an individual operation such as blasting must be increased. By...Reduction of energy consumption in comminution is of significant importance in mining industry. To reduce such energy consumption the energy efficiency in an individual operation such as blasting must be increased. By using both new investigations and previous experimental results, this paper demonstrates that (1) kinetic energy carried by moving fragments in rock fracture is notable and it increases with an increasing loading rate;(2) this kinetic energy can be well used in secondary fragmentation in crushing and blasting. Accordingly, part of the muck pile from previous blast should be left in front of new(bench) face in either open pit or underground blasting. If so, when new blast occurs, the fragments from the new blast will collide with the muck pile left from the previous blast, and the kinetic energy carried by the moving fragments will be partly used in their secondary fragmentation.展开更多
Measurements of the thermal deformations of frozen soil samples were performed in the cold laboratory in temperature range from 0°C to-12°C.Fiber Bragg Gratings strain and temperature sensors were used to me...Measurements of the thermal deformations of frozen soil samples were performed in the cold laboratory in temperature range from 0°C to-12°C.Fiber Bragg Gratings strain and temperature sensors were used to measure the deformation and temperature inside the samples.A number of tests with the samples prepared from Kaolin and Cambrian clay saturated with fresh water,and prepared from fine and silt sand saturated with fresh or saline water,are performed.Thermal deformations of the samples are analyzed depending on the cyclic changes of their temperature.展开更多
The Arctic,though remote,is exceptionally vulnerable to chemical contaminants that threaten its fragile ecosystems.Bisphenols(BPs),a class of endocrine-disrupting chemicals used in plastics and resins,are now detected...The Arctic,though remote,is exceptionally vulnerable to chemical contaminants that threaten its fragile ecosystems.Bisphenols(BPs),a class of endocrine-disrupting chemicals used in plastics and resins,are now detected across the Arctic,but the risks posed by their many analogues are poorly understood.Most studies have focused on documenting their presence,leaving a critical gap in our understanding of whether these compounds bioaccumulate in Arctic food webs and to what extent local,within-Arctic pollution contributes to the overall burden.Here we show,through a comprehensive analysis of 32 BPs in 134 samples from a Norwegian Arctic food web,that multiple BP analogues not only bioaccumulate but also biomagnify from plankton up to polar bears.We found that 5,5′-(1-methylethylidene)bis[(1,1′-biphenyl)-2-ol](BPPH)exhibited the highest trophic magnification factor(a value of 2.3),and we documented total BP concentrations in polar bear tissues up to 1396 ng g^(-1)wet weight,orders of magnitude higher than in lower-trophic-level species.Furthermore,our analysis identified distinct local pollution sources,such as a firefighting training site releasing 2,4,6-trichlorophenol(2,4,6-TBP)and landfill leachate contributing other BPs to the local environment.These findings provide the first evidence of trophic magnification for multiple BPs in a polar food chain and underscore the urgent need to incorporate food-web dynamics and local source management into ecological risk assessments for the Arctic.展开更多
A Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)model is built to investigate the hydrodynamic response of a circular ice floe under the influence of a passing ship in calm waters.The ship,mirr...A Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)model is built to investigate the hydrodynamic response of a circular ice floe under the influence of a passing ship in calm waters.The ship,mirroring the KRISO Container Ship’s hull design,progresses near an ice floe whose diameter is 30%of the ship’s length and its thickness is 3 m.The ship advances at a constant speed,which is handled by using the overset mesh technique.This study focuses on the ice floe’s motions and the hydrodynamic forces induced by three speeds and three transverse distances of the passing ship.Findings reveal that ship-generated wakes notably influence the ice floe’s motions,with a greater influence on sway than surge.Additionally,the ship’s speed and proximity distinctly affect the ice floe’s motions.展开更多
Objective:To evaluate the potential local benthic biomonitor organism,Orchomenella pinguis(O.pinguis),for mining contamination by addressing accumulation and toxicity of mining related metals in this arctic marine amp...Objective:To evaluate the potential local benthic biomonitor organism,Orchomenella pinguis(O.pinguis),for mining contamination by addressing accumulation and toxicity of mining related metals in this arctic marine amphipod.Methods:A toxicity study exposed O.pinguis to four commonly occurring heavy metals(Cd,Cu,Zn and Pb)associated to the mining industry in Greenland using:1)a 5-day water-only bioassay;2)a water-only bioassay evaluating the response between metal accumulation in O.pinguis and metal concentrations in water during a 5-day period;and finally 3)a sediment bioassay evaluating the response between metal accumulation in O.pinguis and metal concentrations in sediment as a function of time during a 20-day period using different mixtures of mining-contaminated sediments.Results:LC_(50)values for the four metals were 2.8,5.4,10.4 and 21.4μmol/L,for Cu,Cd,Pb and Zn,respectively,with corresponding modelled metal concentrations of 3.4,1.0,11.1 and 6.1μmol/g dry weight.During the sediment exposure experiments,a similar concentration of Zn did not induce lethal effects at the same level.Conclusions:This study demonstrates that the appliance of metal organism concentrations as an estimate of effects is not a sufficient biomonitor of environmental effects.The organism may sequester metals into cellular compartments thus rendering the metals inert for toxic effects.More studies are needed to investigate effects of metal bioavailability.Additional biomarkers such as effects on functional responses e.g.feeding and burial behavior or effects on reproductive success are suggested in order enhance to the ecological significance.展开更多
文摘Hanging roofs or high hang-ups.a common problem in sublevel caving mining,usually result in a large ore loss and undermine mining safety.This paper analyzed the formation of a hanging roof and showed that increased confining pressure and reduced free surface were its main characteristics.In order to break down a hanging roof,a new method based on shock wave collision and stress superposition was developed.In this method,two blastholes containing multi-primer at different positions are simultaneously initiated at first.By doing this,a new free surface and a swell room can be created.After these holes are fired,a long delay time is given to the next blasthole so that the fragments from the first twohole blasting have enough time to fall down.This new method was applied to three hanging roofs in one production area,and all of them were successfully broken down.Field inspection indicated that almost no damage was caused in the nearby drifts/tunnels due to the new method.In addition,the far field vibrations were found to be smaller than the maximum vibrations induced by some other blasts.
文摘Reduction of energy consumption in comminution is of significant importance in mining industry. To reduce such energy consumption the energy efficiency in an individual operation such as blasting must be increased. By using both new investigations and previous experimental results, this paper demonstrates that (1) kinetic energy carried by moving fragments in rock fracture is notable and it increases with an increasing loading rate;(2) this kinetic energy can be well used in secondary fragmentation in crushing and blasting. Accordingly, part of the muck pile from previous blast should be left in front of new(bench) face in either open pit or underground blasting. If so, when new blast occurs, the fragments from the new blast will collide with the muck pile left from the previous blast, and the kinetic energy carried by the moving fragments will be partly used in their secondary fragmentation.
基金support of the Innovation Centre SAMCoT (Sustainable Arctic Marine and Coastal Technology), a project of the Norwegian scientific fund
文摘Measurements of the thermal deformations of frozen soil samples were performed in the cold laboratory in temperature range from 0°C to-12°C.Fiber Bragg Gratings strain and temperature sensors were used to measure the deformation and temperature inside the samples.A number of tests with the samples prepared from Kaolin and Cambrian clay saturated with fresh water,and prepared from fine and silt sand saturated with fresh or saline water,are performed.Thermal deformations of the samples are analyzed depending on the cyclic changes of their temperature.
基金supported by the National Natural Science Foundation of China (No.52321005)Provincial Key Research and Development Program of Heilongjiang (No. 2023ZX02C04)+4 种基金supported by the open project of the National Engineering Research Center for Safe Disposal and Resources Recovery of Sludge (No. Z2024B003)the Research Council of Norway (RCN) for funding the project No. 268258 “Reducing the impact of fluorinated compounds on the environment and human health – PFOslo”The support of the University Center in Svalbard (UNIS)the Norwegian University of Life Sciences (NMBU)the Norwegian Geotechnical Institute (NGI) for field work and logistical support is greatly appreciated
文摘The Arctic,though remote,is exceptionally vulnerable to chemical contaminants that threaten its fragile ecosystems.Bisphenols(BPs),a class of endocrine-disrupting chemicals used in plastics and resins,are now detected across the Arctic,but the risks posed by their many analogues are poorly understood.Most studies have focused on documenting their presence,leaving a critical gap in our understanding of whether these compounds bioaccumulate in Arctic food webs and to what extent local,within-Arctic pollution contributes to the overall burden.Here we show,through a comprehensive analysis of 32 BPs in 134 samples from a Norwegian Arctic food web,that multiple BP analogues not only bioaccumulate but also biomagnify from plankton up to polar bears.We found that 5,5′-(1-methylethylidene)bis[(1,1′-biphenyl)-2-ol](BPPH)exhibited the highest trophic magnification factor(a value of 2.3),and we documented total BP concentrations in polar bear tissues up to 1396 ng g^(-1)wet weight,orders of magnitude higher than in lower-trophic-level species.Furthermore,our analysis identified distinct local pollution sources,such as a firefighting training site releasing 2,4,6-trichlorophenol(2,4,6-TBP)and landfill leachate contributing other BPs to the local environment.These findings provide the first evidence of trophic magnification for multiple BPs in a polar food chain and underscore the urgent need to incorporate food-web dynamics and local source management into ecological risk assessments for the Arctic.
文摘A Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)model is built to investigate the hydrodynamic response of a circular ice floe under the influence of a passing ship in calm waters.The ship,mirroring the KRISO Container Ship’s hull design,progresses near an ice floe whose diameter is 30%of the ship’s length and its thickness is 3 m.The ship advances at a constant speed,which is handled by using the overset mesh technique.This study focuses on the ice floe’s motions and the hydrodynamic forces induced by three speeds and three transverse distances of the passing ship.Findings reveal that ship-generated wakes notably influence the ice floe’s motions,with a greater influence on sway than surge.Additionally,the ship’s speed and proximity distinctly affect the ice floe’s motions.
基金Supported by Aarhus University(Grant No.14772-21301).
文摘Objective:To evaluate the potential local benthic biomonitor organism,Orchomenella pinguis(O.pinguis),for mining contamination by addressing accumulation and toxicity of mining related metals in this arctic marine amphipod.Methods:A toxicity study exposed O.pinguis to four commonly occurring heavy metals(Cd,Cu,Zn and Pb)associated to the mining industry in Greenland using:1)a 5-day water-only bioassay;2)a water-only bioassay evaluating the response between metal accumulation in O.pinguis and metal concentrations in water during a 5-day period;and finally 3)a sediment bioassay evaluating the response between metal accumulation in O.pinguis and metal concentrations in sediment as a function of time during a 20-day period using different mixtures of mining-contaminated sediments.Results:LC_(50)values for the four metals were 2.8,5.4,10.4 and 21.4μmol/L,for Cu,Cd,Pb and Zn,respectively,with corresponding modelled metal concentrations of 3.4,1.0,11.1 and 6.1μmol/g dry weight.During the sediment exposure experiments,a similar concentration of Zn did not induce lethal effects at the same level.Conclusions:This study demonstrates that the appliance of metal organism concentrations as an estimate of effects is not a sufficient biomonitor of environmental effects.The organism may sequester metals into cellular compartments thus rendering the metals inert for toxic effects.More studies are needed to investigate effects of metal bioavailability.Additional biomarkers such as effects on functional responses e.g.feeding and burial behavior or effects on reproductive success are suggested in order enhance to the ecological significance.
