Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigati...Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.展开更多
Enhancing the mining speed of a working face has become the primary approach to achieve high production and efficiency in coal mines,thereby further improving the production capacity.However,the problem of rock bursts...Enhancing the mining speed of a working face has become the primary approach to achieve high production and efficiency in coal mines,thereby further improving the production capacity.However,the problem of rock bursts resulting from this approach has become increasingly serious.Therefore,to implement coal mine safety and efficient extraction,the impact of deformation pressure caused by different mining speeds should be considered,and a reasonable mining speed of the working face should be determined.The influence of mining speed on overlying rock breaking in the stope is analyzed by establishing a key layer block rotation and subsidence model.Results show that with the increasing mining speed,the compression amount of gangue in the goaf decreases,and the rotation and subsidence amount of rock block B above goaf decreases,forcing the rotation and subsidence amount of rock block A above roadway to increase.Consequently,the contact mode between rock block A and rock block B changes from line contact to point contact,and the horizontal thrust and shear force between blocks increase.The increase in rotation and subsidence of rock block A intensifies the compression degree of coal and rock mass below the key layer,thereby increasing the stress concentration degree of coal and rock mass as well as the total energy accumulation.In addition,due to the insufficient compression of gangue in the goaf,the bending and subsidence space of the far-field key layer are limited,the length of the suspended roof increases,and the influence range of mining stress and the energy accumulation range expand.Numerical test results and underground microseismic monitoring results verify the correlation between mining speed and stope energy,and high-energy events generally appear 1-2 d after the change in mining speed.On this basis,the statistical principle confirms that the maximum mining speed of the working face at 6 m/d is reasonable.展开更多
In the context of increasing demand for coal mine resources in China’s current socio-economic development,traditional mining methods have been difficult to effectively meet the requirements of safety production and e...In the context of increasing demand for coal mine resources in China’s current socio-economic development,traditional mining methods have been difficult to effectively meet the requirements of safety production and environmental protection.As a result,coal mine filling mining technology has emerged,which can effectively achieve the goal of controlling surface subsidence in practical applications,while also significantly improving the recovery rate of coal resources.Based on this,this study will first elaborate on the characteristics of filling mining technology,and then analyze the key points of the application of supporting technology for mechanical and electrical equipment in the corresponding working face based on actual cases,in order to provide support for improving the efficiency of coal mining.展开更多
Coal mine underground reservoir(CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams.This study develops a novel framework of ...Coal mine underground reservoir(CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams.This study develops a novel framework of steeply inclined coal mine underground reservoirs(SICMUR),which is a paradigm shift from conventional CMUR that the coal seam itself serves as the reservoir floor,challenging conventional designs due to depth-dependent permeability and mechanical constraints.Triaxial mechanical-seepage tests on Xinjiang Wudong coal samples(100,200,300 m depths) revealed a 3.5 MPa triaxial strength increase per 100 m depth and a 58-fold post-peak permeability surge at 300 versus 100 m.Similar model simulations revealed mining-induced stress redistribution and significant deformation effects,particularly subsidence and water-conducting fractures during lower coal seam mining.Results indicate a minimum 40 m safety distance between reservoirs and lower coal seams.Critical construction parameters were investigated for Wudong mine SICMUR as collapse zone heights(9.9–12.31 m) and waterconducting fracture zone heights(31.96–37.40 m).This work systematically bridges SICMUR concepts to field implementation,offering a framework for water preservation in steeply inclined mining while addressing safety concerns,providing a new approach for water reservation in steeply inclined coal mining.展开更多
In the practice of mining shallow buried ultra-close seams,support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf(TLRMG).In this paper,the factors causing supp...In the practice of mining shallow buried ultra-close seams,support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf(TLRMG).In this paper,the factors causing support failure are summarized into geology and mining technology.Combining column lithology and composite beam theory,the key stratum of the rock strata is determined.A finite element numerical simulation is used to analyze the overlying load distribution rule of the main roof for different plane positions of the upper and lower room mining pillars.The tributary area theory(TAT)is adopted to analyze the vertical load distribution of each pillar,and dynamic models of coal pillar instability and main roof fracture are established.Through key block instability analysis,two critical moments are established,of which critical moment A has the greater dynamic load strength.Great economic losses and safety hazards are created by the dynamic load of the fracturing of the main roof.To reduce these negative effects,a method of pulling out supports is developed and two alternative measures for support failure prevention are proposed:reinforcing stope supports in conjunction with reducing mining height,or drilling ground holes to pre-split the main roof.Based on a comprehensive consideration of economic factors and the two categories of support failure causes,the method of reinforcing stope supports while reducing mining height was selected for use on the mining site.展开更多
This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double...This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.展开更多
The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petrolife...The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petroliferous sedimentary basin in China because of its continual annual oil and gas equivalent production of tens of millions of tons(ca.220–440 million barrels per year)since 1959.The SLB was previously thought to have developed on Hercynian basement and accumulated continuous sedimentary deposits during the Late Jurassic and Cretaceous(Wan et al.,2013;Wang et al.,2016).展开更多
Mining-induced surface deformation disrupts ecological balance and impedes economic progress.This study employs SBAS-InSAR with 107-view of ascending and descending SAR data from Sentinel-1,spanning February 2017 to S...Mining-induced surface deformation disrupts ecological balance and impedes economic progress.This study employs SBAS-InSAR with 107-view of ascending and descending SAR data from Sentinel-1,spanning February 2017 to September 2020,to monitor surface deformation in the Fa’er Coal Mine,Guizhou Province.Analysis on the surface deformation time series reveals the relationship between underground mining and surface shifts.Considering geological conditions,mining activities,duration,and ranges,the study determines surface movement parameters for the coal mine.It asserts that mining depth significantly influences surface movement parameters in mountainous mining areas.Increasing mining depth elevates the strike movement angle on the deeper side of the burial depth by 22.84°,while decreasing by 7.74°on the shallower side.Uphill movement angles decrease by 4.06°,while downhill movement angles increase by 15.71°.This emphasizes the technology's suitability for local mining design,which lays the groundwork for resource development,disaster prevention,and ecological protection in analogous contexts.展开更多
The angle α between the fault strike and the axial direction of the roadway produces different damage characteristics. In this paper, the research methodology includes theoretical analyses, numerical simulations and ...The angle α between the fault strike and the axial direction of the roadway produces different damage characteristics. In this paper, the research methodology includes theoretical analyses, numerical simulations and field experiments in the context of the Daqiang coal mine located in Shenyang, China. The stability control countermeasure of "pre-splitting cutting roof + NPR anchor cable"(PSCR-NPR) is simultaneously proposed. According to the different deformation characteristics of the roadway, the faults are innovatively classified into three types, with α of type I being 0°-30°, α of type II being 30°-60°, and α of type III being 60°-90°. The full-cycle stress evolution paths during mining roadway traverses across different types of faults are investigated by numerical simulation. Different pinch angles α lead to high stress concentration areas at different locations in the surrounding rock. The non-uniform stress field formed in the shallow surrounding rock is an important reason for the instability of the roadway. The pre-cracked cut top shifted the high stress region to the deep rock mass and formed a low stress region in the shallow rock mass. The high prestressing NPR anchor cable transforms the non-uniform stress field of the shallow surrounding rock into a uniform stress field. PSCR-NPR is applied in the fault-through roadway of Daqiang mine. The low stress area of the surrounding rock was enlarged by 3-7 times, and the cumulative convergence was reduced by 45%-50%. It provides a reference for the stability control of the deep fault-through mining roadway.展开更多
The high specific capacity and low negative electrochemical potential of lithium metal anodes(LMAs),may allow the energy density threshold of Li metal batteries(LMBs)to be pushed higher.However,the existing detrimenta...The high specific capacity and low negative electrochemical potential of lithium metal anodes(LMAs),may allow the energy density threshold of Li metal batteries(LMBs)to be pushed higher.However,the existing detrimental issues,such as dendritic growth and volume expansion,have hindered the practical implementation of LMBs.Introducing three-dimensional frameworks(e.g.,copper and nickel foam),have been regarded as one of the fundamental strategies to reduce the local current density,aiming to extend the Sand'time.Nevertheless,the local environment far from the skeleton is almost the same as the typical plane Li,due to macroporous space of metal foam.Herein,we built a double-layered 3D current collector of Li alloy anchored on the metal foam,with micropores interconnected macropores,via a viable thermal infiltration and cooling strategy.Due to the excellent electronic and ionic conductivity coupled with favorable lithiophilicity,the Li alloy can effectively reduce the nucleation barrier and enhance the Li^(+)transportation rate,while the metal foam can role as the primary promotor to enlarge the surface area and buffer the dimensional variation.Synergistically,the Li composite anode with hierarchical structure of primary and secondary scaffolds realized the even deposition behavior and minimum volume expansion,outputting preeminent prolonged cycling performances under high rate.展开更多
Metal mineral resources play an indispensable role in the development of the national economy.Dynamic disasters in underground metal mines seriously threaten mining safety,which are major scientific and technological ...Metal mineral resources play an indispensable role in the development of the national economy.Dynamic disasters in underground metal mines seriously threaten mining safety,which are major scientific and technological problems to be solved urgently.In this article,the occurrence status and grand challenges of some typical dynamic disasters involving roof falling,spalling,collapse,large deformation,rockburst,surface subsidence,and water inrush in metal mines in China are systematically presented,the characteristics of mining-induced dynamic disasters are analyzed,the examples of dynamic disasters occurring in some metal mines in China are summarized,the occurrence mechanism,monitoring and early warning methods,and prevention and control techniques of these disasters are highlighted,and some new opinions,suggestions,and solutions are proposed simultaneously.Moreover,some shortcomings in current disaster research are pointed out,and the direction of efforts to improve the prevention and control level of dynamic disasters in China’s metal mines in the future is prospected.The integration of forward-looking key innovative theories and technologies in the abovementioned aspects will greatly enhance the cognitive level of disaster prevention and mitigation in China’s metal mining industry and achieve a significant shift from passive disaster relief to active disaster prevention.展开更多
Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material co...Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.展开更多
This paper primarily concerns the effective coordination of the procedures and methods employed in open pit mining operations under the background of river management.The central objective of this study is to identify...This paper primarily concerns the effective coordination of the procedures and methods employed in open pit mining operations under the background of river management.The central objective of this study is to identify a viable approach for ensuring rational and efficient development of open pit mineral resources while simultaneously protecting and restoring the ecological environment of the river.This approach should facilitate the realization of a harmonious symbiosis between mining and river management.The intricate mutual influence relationship between river management and open pit mining is first analyzed in depth,which provides a solid foundation for the subsequent coordination strategy development.In light of the aforementioned considerations,a set of coordination procedures for open pit mining based on river management conditions is proposed.These procedures emphasize the integration of river protection into the overall layout of mining at the planning stage.The implementation of scientific mining schemes,accompanied by rigorous control of the scope and depth of mining operations,has proven to be an effective means of reducing the impact of mining activities on river environments.This approach has also facilitated the achievement of a balance and coordination between mining and river management.展开更多
Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This proj...Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This project aims to address the extensive impact of coal mining on the environment, infrastructure, and overall safety, focusing on the Shigong River area above the working face. The study employs qualitative and quantitative analyses, along with on-site engineering measurements, to gather data on crucial parameters such as coal seam characteristics, roof rock lithology, thickness, water resistance, and structural damage degree. The research encompasses a multidisciplinary approach, involving mining, geology, hydrogeology, geophysical exploration, rock mechanics, mine surveying, and computational mathematics. The importance of effective safety measures and prevention techniques is emphasized, laying the foundation for research focused on the Xingyun coal mine. The brief concludes by highlighting the potential economic and social benefits of this project and its contribution to valuable experience for future subsea coal mining.展开更多
The mafic-ultramafic intrusion in the XV anomaly area,contains magmatic Fe-Ti oxides±(p)ore,is located in the Bafq mining district in the Central Iran.It consists of cumulate and layered Fe-Ti-bearing gabbros and...The mafic-ultramafic intrusion in the XV anomaly area,contains magmatic Fe-Ti oxides±(p)ore,is located in the Bafq mining district in the Central Iran.It consists of cumulate and layered Fe-Ti-bearing gabbros and pyroxenites.The mineral assemblages include clinopyroxene,Fe-Ti oxides,plagioclase,amphibole,apatite and sulfides(pyrite and chalcopyrite).The Fe-Ti oxides mainly consist of magnetite-titanomagnetite and ilmenite,which occurred as disseminated,intergrowth,lamellae(trellis and sandwich textures)and inclusions.Magnetite in the gabbroic rocks is from the near end-member of Fe_(3)O_(4)(<1 wt.%TiO_(2))to titanomagnetite containing up to 8 wt.%TiO_(2)(about3.73 wt.%to 26.84 wt.%Ulvospinel(X_(Usp))).Magnetite in pyroxenite rocks is characterized with TiO_(2)range from 0.46 wt.%to 3.14 wt.%(X_(Usp)varied from 1.76 wt.%to 10.46 wt.%).The abundances of V_(2)O_(3)range from 0.03 wt.%to 1.29 wt.%and 0.24 wt.%to 1.00 wt.%for gabbro and pyroxenite,respectively.X_(Usp)contents of magnetite show insignificant correlations with Al_(2)O_(3)and MgO.The average XIlmin the ilmenite of gabbro is 92%,whereas it is 90.37%in the pyroxenite rocks.The MgO and V_(2)O_(3)contents show a slightly positive correlation with TiO_(2)in ilmenite.The composition of clinopyroxenes in gabbro and pyroxenite rocks fall in the diopside to augite field with Mg#ranging from 67 to 98 and 74 to 96,respectively.In both rock types,amphiboles are mainly pargasite and rarely actinolite.Plagioclase in pyroxenite rocks is clustered in the labradorite to andesine fields with a compositional ranges of An46-69and in gabboic rocks fall in two fields with compositional ranges of albite with An0.65-5.95and labradorite with An50-63.Theδ34S isotopic values cover a limited range from+3.15‰to+4.10‰V-CDT consistent with magmatic origin.Fe-Ti mineralization is formed in two stages,minor inclusions of Fe-Ti oxide minerals in the pyroxene and plagioclase crystallized in the early magmatic stage,whereas interstitial oxides formed by fractional crystallization processes that accumulated by gravitational settling in the later stage as intercumulus phase.Gravitational settling process is supported by the observation of decreasing the amount of Fe-Ti oxides from Fe-Ti oxide-rich pyroxenite to weak mineralized gabbro(base to top).The high contents of H2O,phosphorate and high initial Ti-Fe in parental magma are the crucial factors controlling the Fe-Ti oxides enrichment and mineralization.展开更多
Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the...Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas,which results in inaccurate gas content measurements.This study introduces a lightweight,in-situ pressure-and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point,effectively preventing gas loss during transfer and significantly improving measurement accuracy.Additionally,a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions.The model offers valuable insights for optimizing coring parameters,demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements.Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection.Furthermore,successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34%higher than that obtained through open sampling methods.展开更多
1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrest...1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrestrial ecosystems.展开更多
Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across...Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across the copper mining,beneficiation,and smelting processes using a life-cycle approach,providing important insights for arsenic pollution prevention and the resource utilization of arsenic-bearing solid waste.The results show that the amount of As in waste rock,tailing and concentrate are 53483 t,86632 t,76162 t,respectively.After smelting treatment,the amount of arsenic in different types of solid waste,wastewater,waste gas and products are 76128 t,1 t,31 t and 2 t,respectively,and the proportion in arsenic sulfide slag is the highest(55%).The amount of emission to the environment is 32 t,accounting for only 0.04%of total amount.In the future,key considerations are to improve the resource utilization rate of arsenic-containing solid waste(tailing,smelting slag),especially arsenic sulfide slag,and to digest its environmental risk.展开更多
Aseptic osteonecrosis of the femoral head is defined as the death of bone cells in the femoral epiphysis due to an interruption of blood supply. Most cases are linked to trauma, but non-traumatic cases also occur and ...Aseptic osteonecrosis of the femoral head is defined as the death of bone cells in the femoral epiphysis due to an interruption of blood supply. Most cases are linked to trauma, but non-traumatic cases also occur and can be associated with several known risk factors. This study aims to describe these risk factors identified in the former Katanga province, a region with significant mining activity. Method and Patients: This is a descriptive cross-sectional study conducted over a seven-year period (2017-2024), including all cases of aseptic osteonecrosis of the femoral head diagnosed in the orthopedic department of Medpark Clinic in Lubumbashi. The investigation of risk factors was based on the analysis of sociodemographic, clinical, radiological, and biological data. Results: Our study included a total of 110 patients with a mean age of 47.5 years. Among them, there were 46 women (41.82%) and 64 men (58.18%). Twenty-five patients (27.5%) reported a family history of osteonecrosis, and 24% were diagnosed with sickle cell disease. Chronic alcoholism was noted in 14 patients (12.73%), while diabetes was present in 8 (7.2%). Four patients (3.64%) were obese, and three were HIV-positive (2.72%). The use of nonsteroidal anti-inflammatory drugs (NSAIDs) was common, and prolonged corticosteroid use was documented in 5 patients (4.5%). Abnormally high cholesterol levels were found in 26 patients (23.6%). One patient had gout, and two suffered from acute rheumatic fever (1.8%). Regarding inflammatory markers, C-reactive protein levels and erythrocyte sedimentation rates were within normal limits for almost all patients. Electrolyte levels and phosphocalcic profiles showed no abnormalities. Furthermore, 33 patients (30%) did not exhibit any of the previously mentioned risk factors. Most of these patients lived in the regions of Kolwezi, Likasi, and Lubumbashi. Among this group, 25 patients reported performing physically demanding labor, particularly in mining operations. Conclusion: Our study highlighted well-known risk factors for osteonecrosis of the femoral head (ONFH). However, it also identified a significant number of cases without any identifiable risk factors, classified as idiopathic. Among these cases, some patients engaged in intense physical labor, often linked to mining exposure.展开更多
The Internet of Things(IoT)has orchestrated various domains in numerous applications,contributing significantly to the growth of the smart world,even in regions with low literacy rates,boosting socio-economic developm...The Internet of Things(IoT)has orchestrated various domains in numerous applications,contributing significantly to the growth of the smart world,even in regions with low literacy rates,boosting socio-economic development.This study provides valuable insights into optimizing wireless communication,paving the way for a more connected and productive future in the mining industry.The IoT revolution is advancing across industries,but harsh geometric environments,including open-pit mines,pose unique challenges for reliable communication.The advent of IoT in the mining industry has significantly improved communication for critical operations through the use of Radio Frequency(RF)protocols such as Bluetooth,Wi-Fi,GSM/GPRS,Narrow Band(NB)-IoT,SigFox,ZigBee,and Long Range Wireless Area Network(LoRaWAN).This study addresses the optimization of network implementations by comparing two leading free-spreading IoT-based RF protocols such as ZigBee and LoRaWAN.Intensive field tests are conducted in various opencast mines to investigate coverage potential and signal attenuation.ZigBee is tested in the Tadicherla open-cast coal mine in India.Similarly,LoRaWAN field tests are conducted at one of the associated cement companies(ACC)in the limestone mine in Bargarh,India,covering both Indoor-toOutdoor(I2O)and Outdoor-to-Outdoor(O2O)environments.A robust framework of path-loss models,referred to as Free space,Egli,Okumura-Hata,Cost231-Hata and Ericsson models,combined with key performance metrics,is employed to evaluate the patterns of signal attenuation.Extensive field testing and careful data analysis revealed that the Egli model is the most consistent path-loss model for the ZigBee protocol in an I2O environment,with a coefficient of determination(R^(2))of 0.907,balanced error metrics such as Normalized Root Mean Square Error(NRMSE)of 0.030,Mean Square Error(MSE)of 4.950,Mean Absolute Percentage Error(MAPE)of 0.249 and Scatter Index(SI)of 2.723.In the O2O scenario,the Ericsson model showed superior performance,with the highest R^(2)value of 0.959,supported by strong correlation metrics:NRMSE of 0.026,MSE of 8.685,MAPE of 0.685,Mean Absolute Deviation(MAD)of 20.839 and SI of 2.194.For the LoRaWAN protocol,the Cost-231 model achieved the highest R^(2)value of 0.921 in the I2O scenario,complemented by the lowest metrics:NRMSE of 0.018,MSE of 1.324,MAPE of 0.217,MAD of 9.218 and SI of 1.238.In the O2O environment,the Okumura-Hata model achieved the highest R^(2)value of 0.978,indicating a strong fit with metrics NRMSE of 0.047,MSE of 27.807,MAPE of 27.494,MAD of 37.287 and SI of 3.927.This advancement in reliable communication networks promises to transform the opencast landscape into networked signal attenuation.These results support decision-making for mining needs and ensure reliable communications even in the face of formidable obstacles.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074213 and 11574108)the National Key R&D Program of China(Grant No.2022YFA1403103)+2 种基金the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province(Grant No.ZR2023MA082)the Project of Introduction and Cultivation for Young Innovative Talents in Colleges and Universities of Shandong Province。
文摘Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.
基金supported by Technology Innovation Fund of China Coal Research Institute(2022CX-I-04)Science and Technology Innovation Venture Capital Project of China Coal Technology Engineering Group(2020-2-TD-CXY005)。
文摘Enhancing the mining speed of a working face has become the primary approach to achieve high production and efficiency in coal mines,thereby further improving the production capacity.However,the problem of rock bursts resulting from this approach has become increasingly serious.Therefore,to implement coal mine safety and efficient extraction,the impact of deformation pressure caused by different mining speeds should be considered,and a reasonable mining speed of the working face should be determined.The influence of mining speed on overlying rock breaking in the stope is analyzed by establishing a key layer block rotation and subsidence model.Results show that with the increasing mining speed,the compression amount of gangue in the goaf decreases,and the rotation and subsidence amount of rock block B above goaf decreases,forcing the rotation and subsidence amount of rock block A above roadway to increase.Consequently,the contact mode between rock block A and rock block B changes from line contact to point contact,and the horizontal thrust and shear force between blocks increase.The increase in rotation and subsidence of rock block A intensifies the compression degree of coal and rock mass below the key layer,thereby increasing the stress concentration degree of coal and rock mass as well as the total energy accumulation.In addition,due to the insufficient compression of gangue in the goaf,the bending and subsidence space of the far-field key layer are limited,the length of the suspended roof increases,and the influence range of mining stress and the energy accumulation range expand.Numerical test results and underground microseismic monitoring results verify the correlation between mining speed and stope energy,and high-energy events generally appear 1-2 d after the change in mining speed.On this basis,the statistical principle confirms that the maximum mining speed of the working face at 6 m/d is reasonable.
文摘In the context of increasing demand for coal mine resources in China’s current socio-economic development,traditional mining methods have been difficult to effectively meet the requirements of safety production and environmental protection.As a result,coal mine filling mining technology has emerged,which can effectively achieve the goal of controlling surface subsidence in practical applications,while also significantly improving the recovery rate of coal resources.Based on this,this study will first elaborate on the characteristics of filling mining technology,and then analyze the key points of the application of supporting technology for mechanical and electrical equipment in the corresponding working face based on actual cases,in order to provide support for improving the efficiency of coal mining.
基金supported by Beijing Natural Science Foundation (No.8254049)the National Natural Science Foundation of China (No.52374139)the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project (No.2024ZD1004505)。
文摘Coal mine underground reservoir(CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams.This study develops a novel framework of steeply inclined coal mine underground reservoirs(SICMUR),which is a paradigm shift from conventional CMUR that the coal seam itself serves as the reservoir floor,challenging conventional designs due to depth-dependent permeability and mechanical constraints.Triaxial mechanical-seepage tests on Xinjiang Wudong coal samples(100,200,300 m depths) revealed a 3.5 MPa triaxial strength increase per 100 m depth and a 58-fold post-peak permeability surge at 300 versus 100 m.Similar model simulations revealed mining-induced stress redistribution and significant deformation effects,particularly subsidence and water-conducting fractures during lower coal seam mining.Results indicate a minimum 40 m safety distance between reservoirs and lower coal seams.Critical construction parameters were investigated for Wudong mine SICMUR as collapse zone heights(9.9–12.31 m) and waterconducting fracture zone heights(31.96–37.40 m).This work systematically bridges SICMUR concepts to field implementation,offering a framework for water preservation in steeply inclined mining while addressing safety concerns,providing a new approach for water reservation in steeply inclined coal mining.
基金supported by the National Natural Science Foundation of China (No. 51374200)
文摘In the practice of mining shallow buried ultra-close seams,support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf(TLRMG).In this paper,the factors causing support failure are summarized into geology and mining technology.Combining column lithology and composite beam theory,the key stratum of the rock strata is determined.A finite element numerical simulation is used to analyze the overlying load distribution rule of the main roof for different plane positions of the upper and lower room mining pillars.The tributary area theory(TAT)is adopted to analyze the vertical load distribution of each pillar,and dynamic models of coal pillar instability and main roof fracture are established.Through key block instability analysis,two critical moments are established,of which critical moment A has the greater dynamic load strength.Great economic losses and safety hazards are created by the dynamic load of the fracturing of the main roof.To reduce these negative effects,a method of pulling out supports is developed and two alternative measures for support failure prevention are proposed:reinforcing stope supports in conjunction with reducing mining height,or drilling ground holes to pre-split the main roof.Based on a comprehensive consideration of economic factors and the two categories of support failure causes,the method of reinforcing stope supports while reducing mining height was selected for use on the mining site.
基金funded by the China Postdoctoral Science Foundation(Grant No.2022M721614)the opening project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(Grant No.KFJJ23-07M)。
文摘This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.
基金supports from the International Continental Scientific Drilling Programfunded by the National Natural Science Foundation of China(Grant Nos.41790453,41472304,42102129,42102135 and 41972313)+2 种基金Natural Science Foundation of Jilin Province(Grant No.20170101001JC)the National Key Research&Development Program of China(Grant No.2019YFC0605402)China Geological Survey(Grant No.DD20189702)。
文摘The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petroliferous sedimentary basin in China because of its continual annual oil and gas equivalent production of tens of millions of tons(ca.220–440 million barrels per year)since 1959.The SLB was previously thought to have developed on Hercynian basement and accumulated continuous sedimentary deposits during the Late Jurassic and Cretaceous(Wan et al.,2013;Wang et al.,2016).
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA28060201)the National Natural Science Foundation of China(Grant No.42067046)the Science and Technology Planning Project of Guiyang City(Grant No.ZKHT[2023]13-10).
文摘Mining-induced surface deformation disrupts ecological balance and impedes economic progress.This study employs SBAS-InSAR with 107-view of ascending and descending SAR data from Sentinel-1,spanning February 2017 to September 2020,to monitor surface deformation in the Fa’er Coal Mine,Guizhou Province.Analysis on the surface deformation time series reveals the relationship between underground mining and surface shifts.Considering geological conditions,mining activities,duration,and ranges,the study determines surface movement parameters for the coal mine.It asserts that mining depth significantly influences surface movement parameters in mountainous mining areas.Increasing mining depth elevates the strike movement angle on the deeper side of the burial depth by 22.84°,while decreasing by 7.74°on the shallower side.Uphill movement angles decrease by 4.06°,while downhill movement angles increase by 15.71°.This emphasizes the technology's suitability for local mining design,which lays the groundwork for resource development,disaster prevention,and ecological protection in analogous contexts.
基金funded by the National Natural Science Foundation of China (52174096, 52304110)the Fundamental Research Funds for the Central Universities (2022YJSSB03)the Scientific and Technological Projects of Henan Province (232102320238)。
文摘The angle α between the fault strike and the axial direction of the roadway produces different damage characteristics. In this paper, the research methodology includes theoretical analyses, numerical simulations and field experiments in the context of the Daqiang coal mine located in Shenyang, China. The stability control countermeasure of "pre-splitting cutting roof + NPR anchor cable"(PSCR-NPR) is simultaneously proposed. According to the different deformation characteristics of the roadway, the faults are innovatively classified into three types, with α of type I being 0°-30°, α of type II being 30°-60°, and α of type III being 60°-90°. The full-cycle stress evolution paths during mining roadway traverses across different types of faults are investigated by numerical simulation. Different pinch angles α lead to high stress concentration areas at different locations in the surrounding rock. The non-uniform stress field formed in the shallow surrounding rock is an important reason for the instability of the roadway. The pre-cracked cut top shifted the high stress region to the deep rock mass and formed a low stress region in the shallow rock mass. The high prestressing NPR anchor cable transforms the non-uniform stress field of the shallow surrounding rock into a uniform stress field. PSCR-NPR is applied in the fault-through roadway of Daqiang mine. The low stress area of the surrounding rock was enlarged by 3-7 times, and the cumulative convergence was reduced by 45%-50%. It provides a reference for the stability control of the deep fault-through mining roadway.
基金supported by Huzhou Natural Science Foundation Project(Nos.2022YZ04 and 2022YZ21)S&T Special Program of Huzhou(No.2023GZ03)National Natural Science Foundation of China(No.52172184)。
文摘The high specific capacity and low negative electrochemical potential of lithium metal anodes(LMAs),may allow the energy density threshold of Li metal batteries(LMBs)to be pushed higher.However,the existing detrimental issues,such as dendritic growth and volume expansion,have hindered the practical implementation of LMBs.Introducing three-dimensional frameworks(e.g.,copper and nickel foam),have been regarded as one of the fundamental strategies to reduce the local current density,aiming to extend the Sand'time.Nevertheless,the local environment far from the skeleton is almost the same as the typical plane Li,due to macroporous space of metal foam.Herein,we built a double-layered 3D current collector of Li alloy anchored on the metal foam,with micropores interconnected macropores,via a viable thermal infiltration and cooling strategy.Due to the excellent electronic and ionic conductivity coupled with favorable lithiophilicity,the Li alloy can effectively reduce the nucleation barrier and enhance the Li^(+)transportation rate,while the metal foam can role as the primary promotor to enlarge the surface area and buffer the dimensional variation.Synergistically,the Li composite anode with hierarchical structure of primary and secondary scaffolds realized the even deposition behavior and minimum volume expansion,outputting preeminent prolonged cycling performances under high rate.
基金Project(52204084)supported by the National Natural Science Foundation of ChinaProject(FRF-IDRY-GD22-002)supported by the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities),China+2 种基金Project(QNXM20220009)supported by the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange and Growth Program,ChinaProjects(2022YFC2905600,2022YFC3004601)supported by the National Key R&D Program of ChinaProject(2023XAGG0061)supported by the Science,Technology&Innovation Project of Xiongan New Area,China。
文摘Metal mineral resources play an indispensable role in the development of the national economy.Dynamic disasters in underground metal mines seriously threaten mining safety,which are major scientific and technological problems to be solved urgently.In this article,the occurrence status and grand challenges of some typical dynamic disasters involving roof falling,spalling,collapse,large deformation,rockburst,surface subsidence,and water inrush in metal mines in China are systematically presented,the characteristics of mining-induced dynamic disasters are analyzed,the examples of dynamic disasters occurring in some metal mines in China are summarized,the occurrence mechanism,monitoring and early warning methods,and prevention and control techniques of these disasters are highlighted,and some new opinions,suggestions,and solutions are proposed simultaneously.Moreover,some shortcomings in current disaster research are pointed out,and the direction of efforts to improve the prevention and control level of dynamic disasters in China’s metal mines in the future is prospected.The integration of forward-looking key innovative theories and technologies in the abovementioned aspects will greatly enhance the cognitive level of disaster prevention and mitigation in China’s metal mining industry and achieve a significant shift from passive disaster relief to active disaster prevention.
基金Fund by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (No.2018YFD1101002-03)。
文摘Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.
文摘This paper primarily concerns the effective coordination of the procedures and methods employed in open pit mining operations under the background of river management.The central objective of this study is to identify a viable approach for ensuring rational and efficient development of open pit mineral resources while simultaneously protecting and restoring the ecological environment of the river.This approach should facilitate the realization of a harmonious symbiosis between mining and river management.The intricate mutual influence relationship between river management and open pit mining is first analyzed in depth,which provides a solid foundation for the subsequent coordination strategy development.In light of the aforementioned considerations,a set of coordination procedures for open pit mining based on river management conditions is proposed.These procedures emphasize the integration of river protection into the overall layout of mining at the planning stage.The implementation of scientific mining schemes,accompanied by rigorous control of the scope and depth of mining operations,has proven to be an effective means of reducing the impact of mining activities on river environments.This approach has also facilitated the achievement of a balance and coordination between mining and river management.
文摘Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This project aims to address the extensive impact of coal mining on the environment, infrastructure, and overall safety, focusing on the Shigong River area above the working face. The study employs qualitative and quantitative analyses, along with on-site engineering measurements, to gather data on crucial parameters such as coal seam characteristics, roof rock lithology, thickness, water resistance, and structural damage degree. The research encompasses a multidisciplinary approach, involving mining, geology, hydrogeology, geophysical exploration, rock mechanics, mine surveying, and computational mathematics. The importance of effective safety measures and prevention techniques is emphasized, laying the foundation for research focused on the Xingyun coal mine. The brief concludes by highlighting the potential economic and social benefits of this project and its contribution to valuable experience for future subsea coal mining.
基金supported by the department of Geoscience,University of Nevada,Las Vegas,NV 89154,USAfinanced by the French Government Laboratory of Excellence Initiative(No.ANR-10-LABX-0006)the Region Auvergne and the European Regional Development Fund。
文摘The mafic-ultramafic intrusion in the XV anomaly area,contains magmatic Fe-Ti oxides±(p)ore,is located in the Bafq mining district in the Central Iran.It consists of cumulate and layered Fe-Ti-bearing gabbros and pyroxenites.The mineral assemblages include clinopyroxene,Fe-Ti oxides,plagioclase,amphibole,apatite and sulfides(pyrite and chalcopyrite).The Fe-Ti oxides mainly consist of magnetite-titanomagnetite and ilmenite,which occurred as disseminated,intergrowth,lamellae(trellis and sandwich textures)and inclusions.Magnetite in the gabbroic rocks is from the near end-member of Fe_(3)O_(4)(<1 wt.%TiO_(2))to titanomagnetite containing up to 8 wt.%TiO_(2)(about3.73 wt.%to 26.84 wt.%Ulvospinel(X_(Usp))).Magnetite in pyroxenite rocks is characterized with TiO_(2)range from 0.46 wt.%to 3.14 wt.%(X_(Usp)varied from 1.76 wt.%to 10.46 wt.%).The abundances of V_(2)O_(3)range from 0.03 wt.%to 1.29 wt.%and 0.24 wt.%to 1.00 wt.%for gabbro and pyroxenite,respectively.X_(Usp)contents of magnetite show insignificant correlations with Al_(2)O_(3)and MgO.The average XIlmin the ilmenite of gabbro is 92%,whereas it is 90.37%in the pyroxenite rocks.The MgO and V_(2)O_(3)contents show a slightly positive correlation with TiO_(2)in ilmenite.The composition of clinopyroxenes in gabbro and pyroxenite rocks fall in the diopside to augite field with Mg#ranging from 67 to 98 and 74 to 96,respectively.In both rock types,amphiboles are mainly pargasite and rarely actinolite.Plagioclase in pyroxenite rocks is clustered in the labradorite to andesine fields with a compositional ranges of An46-69and in gabboic rocks fall in two fields with compositional ranges of albite with An0.65-5.95and labradorite with An50-63.Theδ34S isotopic values cover a limited range from+3.15‰to+4.10‰V-CDT consistent with magmatic origin.Fe-Ti mineralization is formed in two stages,minor inclusions of Fe-Ti oxide minerals in the pyroxene and plagioclase crystallized in the early magmatic stage,whereas interstitial oxides formed by fractional crystallization processes that accumulated by gravitational settling in the later stage as intercumulus phase.Gravitational settling process is supported by the observation of decreasing the amount of Fe-Ti oxides from Fe-Ti oxide-rich pyroxenite to weak mineralized gabbro(base to top).The high contents of H2O,phosphorate and high initial Ti-Fe in parental magma are the crucial factors controlling the Fe-Ti oxides enrichment and mineralization.
基金supported by the National Natural Science Foundation of China(Nos.51827901,42477191,and 52304033)the Fundamental Research Funds for the Central Universities(No.YJ202449)+1 种基金the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(No.SKLGME022009)the China Postdoctoral Science Foundation(No.2023M742446).
文摘Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas,which results in inaccurate gas content measurements.This study introduces a lightweight,in-situ pressure-and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point,effectively preventing gas loss during transfer and significantly improving measurement accuracy.Additionally,a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions.The model offers valuable insights for optimizing coring parameters,demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements.Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection.Furthermore,successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34%higher than that obtained through open sampling methods.
基金supported by the National Natural Science Foun dation of China(52374170 and 51974313)the National Key Research and Development Plan Project(2022YFF1303300).
文摘1.Introduction Changes in land use are key factors promoting global climate change,and the side effects of mining activity that destroy the soil,vegetation,and biodiversity lead to imbalanced carbon cycling in terrestrial ecosystems.
文摘Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across the copper mining,beneficiation,and smelting processes using a life-cycle approach,providing important insights for arsenic pollution prevention and the resource utilization of arsenic-bearing solid waste.The results show that the amount of As in waste rock,tailing and concentrate are 53483 t,86632 t,76162 t,respectively.After smelting treatment,the amount of arsenic in different types of solid waste,wastewater,waste gas and products are 76128 t,1 t,31 t and 2 t,respectively,and the proportion in arsenic sulfide slag is the highest(55%).The amount of emission to the environment is 32 t,accounting for only 0.04%of total amount.In the future,key considerations are to improve the resource utilization rate of arsenic-containing solid waste(tailing,smelting slag),especially arsenic sulfide slag,and to digest its environmental risk.
文摘Aseptic osteonecrosis of the femoral head is defined as the death of bone cells in the femoral epiphysis due to an interruption of blood supply. Most cases are linked to trauma, but non-traumatic cases also occur and can be associated with several known risk factors. This study aims to describe these risk factors identified in the former Katanga province, a region with significant mining activity. Method and Patients: This is a descriptive cross-sectional study conducted over a seven-year period (2017-2024), including all cases of aseptic osteonecrosis of the femoral head diagnosed in the orthopedic department of Medpark Clinic in Lubumbashi. The investigation of risk factors was based on the analysis of sociodemographic, clinical, radiological, and biological data. Results: Our study included a total of 110 patients with a mean age of 47.5 years. Among them, there were 46 women (41.82%) and 64 men (58.18%). Twenty-five patients (27.5%) reported a family history of osteonecrosis, and 24% were diagnosed with sickle cell disease. Chronic alcoholism was noted in 14 patients (12.73%), while diabetes was present in 8 (7.2%). Four patients (3.64%) were obese, and three were HIV-positive (2.72%). The use of nonsteroidal anti-inflammatory drugs (NSAIDs) was common, and prolonged corticosteroid use was documented in 5 patients (4.5%). Abnormally high cholesterol levels were found in 26 patients (23.6%). One patient had gout, and two suffered from acute rheumatic fever (1.8%). Regarding inflammatory markers, C-reactive protein levels and erythrocyte sedimentation rates were within normal limits for almost all patients. Electrolyte levels and phosphocalcic profiles showed no abnormalities. Furthermore, 33 patients (30%) did not exhibit any of the previously mentioned risk factors. Most of these patients lived in the regions of Kolwezi, Likasi, and Lubumbashi. Among this group, 25 patients reported performing physically demanding labor, particularly in mining operations. Conclusion: Our study highlighted well-known risk factors for osteonecrosis of the femoral head (ONFH). However, it also identified a significant number of cases without any identifiable risk factors, classified as idiopathic. Among these cases, some patients engaged in intense physical labor, often linked to mining exposure.
文摘The Internet of Things(IoT)has orchestrated various domains in numerous applications,contributing significantly to the growth of the smart world,even in regions with low literacy rates,boosting socio-economic development.This study provides valuable insights into optimizing wireless communication,paving the way for a more connected and productive future in the mining industry.The IoT revolution is advancing across industries,but harsh geometric environments,including open-pit mines,pose unique challenges for reliable communication.The advent of IoT in the mining industry has significantly improved communication for critical operations through the use of Radio Frequency(RF)protocols such as Bluetooth,Wi-Fi,GSM/GPRS,Narrow Band(NB)-IoT,SigFox,ZigBee,and Long Range Wireless Area Network(LoRaWAN).This study addresses the optimization of network implementations by comparing two leading free-spreading IoT-based RF protocols such as ZigBee and LoRaWAN.Intensive field tests are conducted in various opencast mines to investigate coverage potential and signal attenuation.ZigBee is tested in the Tadicherla open-cast coal mine in India.Similarly,LoRaWAN field tests are conducted at one of the associated cement companies(ACC)in the limestone mine in Bargarh,India,covering both Indoor-toOutdoor(I2O)and Outdoor-to-Outdoor(O2O)environments.A robust framework of path-loss models,referred to as Free space,Egli,Okumura-Hata,Cost231-Hata and Ericsson models,combined with key performance metrics,is employed to evaluate the patterns of signal attenuation.Extensive field testing and careful data analysis revealed that the Egli model is the most consistent path-loss model for the ZigBee protocol in an I2O environment,with a coefficient of determination(R^(2))of 0.907,balanced error metrics such as Normalized Root Mean Square Error(NRMSE)of 0.030,Mean Square Error(MSE)of 4.950,Mean Absolute Percentage Error(MAPE)of 0.249 and Scatter Index(SI)of 2.723.In the O2O scenario,the Ericsson model showed superior performance,with the highest R^(2)value of 0.959,supported by strong correlation metrics:NRMSE of 0.026,MSE of 8.685,MAPE of 0.685,Mean Absolute Deviation(MAD)of 20.839 and SI of 2.194.For the LoRaWAN protocol,the Cost-231 model achieved the highest R^(2)value of 0.921 in the I2O scenario,complemented by the lowest metrics:NRMSE of 0.018,MSE of 1.324,MAPE of 0.217,MAD of 9.218 and SI of 1.238.In the O2O environment,the Okumura-Hata model achieved the highest R^(2)value of 0.978,indicating a strong fit with metrics NRMSE of 0.047,MSE of 27.807,MAPE of 27.494,MAD of 37.287 and SI of 3.927.This advancement in reliable communication networks promises to transform the opencast landscape into networked signal attenuation.These results support decision-making for mining needs and ensure reliable communications even in the face of formidable obstacles.
