A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing Mg O as a feedstock. The electrolysis of various Mg O resources was conducted u...A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing Mg O as a feedstock. The electrolysis of various Mg O resources was conducted using a Cu cathode in MgF2– LiF – KCl molten salt at 1043 K by applying an average current of 1.44 A for 12.5 h. The electrolysis of calcined North Korean magnesite and seawater Mg O clinker yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 89.6–92.4%. The electrolysis of oxidized Mg O-C refractory brick, aged ferronickel slag, and ferronickel slag yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 59.3–92.3%. The vacuum distillation of Mg alloys obtained was conducted at 1300 K for 10 h to produce high-purity Mg metal. After vacuum distillation, Mg metal with a purity of above 99.994% was obtained. Therefore, this study demonstrates the feasibility of the production of high-purity Mg metal from various Mg O resources using a novel electrolytic process with a Cu cathode, followed by vacuum distillation.展开更多
Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process ca...Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.展开更多
The impact on these water bodies of the surrounding coal production activities and the power plant through research the content and characteristics of harmful trace elements in coal contained in these water bodies.F,H...The impact on these water bodies of the surrounding coal production activities and the power plant through research the content and characteristics of harmful trace elements in coal contained in these water bodies.F,Hg,Se and As these four trace ele- ments increased 0.92%,0.78%,0.70% and 0.81% respectively in Datong mining subsi- dence pool from November 2004 to November 2006;the four elements increased 1.58%, 1.23%,1.08% and 0.92% respectively in Xie'er mining subsidence pool;the four ele- ments increased 1.16%,1.06%,1.02% and 1.01% respectively in Pansan mining sub- sidence pool.The conclusions show that the absolute values of F,Hg,Se and As in mining subsidence pool are relate with their background value,while the increase in their concen- tration and their environment of mine and electricity plant surrounded are closely linked.展开更多
Mining subsidence pools are water bodies formed by soil subsidence near mines. We studied the impact the surrounding coal production activities and power plants have on these waters by measuring the concentrations of ...Mining subsidence pools are water bodies formed by soil subsidence near mines. We studied the impact the surrounding coal production activities and power plants have on these waters by measuring the concentrations of harmful trace elements in these waters. The concentration of the four elements F, Hg, Se and As increased by 0.92%, 0.78%, 0.70% and 0.81%, respectively, in the Datong mining subsidence pool from November 2004 to November 2006. The four elements increased by 1.58%, 1.23%, 1.08% and 0.92%, respectively, in the Xie’er mining subsidence pool and 1.16%, 1.06%, 1.02% and 1.01%, respectively, in the Pansan mining subsidence pool over the same time period. The absolute levels of F, Hg, Se and As in the pool are related to the background levels of the elements. A close relationship between nearby coal mines and power plants and increasing levels of the measured elements is noted.展开更多
In this study,a novel Mg production process for producing high-purity Mg metal from dolomite was developed.When the electrolysis of calcined dolomite was conducted using Cu cathode and C anode in MgF_(2)–LiF molten s...In this study,a novel Mg production process for producing high-purity Mg metal from dolomite was developed.When the electrolysis of calcined dolomite was conducted using Cu cathode and C anode in MgF_(2)–LiF molten salt at 1083–1173 K by applying an average current of 1.42–1.46 A for 9.50–21.0 h,the current efficiency of 66.4–88.6%was obtained.The produced Mg alloys consisted of MgCu_(2)and Cu(Mg)or MgCu_(2)and CuMg_(2)phases,depending on the Mg concentration in the Mg alloy.When the electrolysis of calcined dolomite was conducted in MgF_(2)–LiF–CaF_(2)molten salt at 1083 K,the current efficiency was 40.9–71.4%,owing to undesired reactions such as electroreduction of Ca^(2+)or/and CO_(3)^(2−)ions.Meanwhile,the current efficiency increased from 40.9%to 63.2%by utilizing a Pt anode,because the occurrence of CO_(3)^(2−)ions in the molten salt was prevented.After vacuum distillation of the obtained Mg alloys at 1300 K for 10 h,Mg metal with a purity of 99.9996–99.9998%was produced.Therefore,the feasibility of this novel process for the production of high-purity Mg metal from dolomite was demonstrated.展开更多
Experiments using electrical resistivity tomography(ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements ...Experiments using electrical resistivity tomography(ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements only.To explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes,namely the classical smoothness-constrained inversion and a geostatistically based approach,we performed two-dimensional synthetic experiments.Simplifying assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions,including the number of boreholes,measurement schemes,contrast between the plume and background electrical conductivity,use of a priori knowledge,and point conditioning.The results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality,which can be further improved when point measurements are incorporated and advantageous measurement schemes are chosen.As expected,an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics,while in this case the benefits of point conditioning and advantageous measurement schemes diminish.Both ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity,and robust with regard to biased input parameters,such as mean concentration,variance,and correlation length of the plume.Although sophisticated inversion schemes have recently become available,in which flow and transport as well as electrical forward models are coupled,these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological model.Therefore,we believe that standard uncoupled ERT inverse approaches,like the ones discussed and assessed in this paper,will continue to be important to the imaging and characterization of solute plumes in many real-world applications.展开更多
This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers,considering the long-term climate.The paper suggests a method to predict th...This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers,considering the long-term climate.The paper suggests a method to predict the low-cycle fatigue life by demonstrating a thermal-fluid-structural analysis of bridge pier concrete according to long-term climate such as temperature,velocity and pressure of air and water in the process of freezing and thawing in winter.In addition,it proposes a reinforcing method to increase the life of damaged piers and proves the feasibility of the proposed method with numerical comparison experiment.展开更多
Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field,one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone.Re-Os isotope dati...Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field,one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone.Re-Os isotope dating was used on three molybdenite samples from Hejiangkou deposit to determine the ore forming period.The result is(224.9±2.6)Ma-(225±3.1)Ma and isochron age is(225.5±3.6)Ma.The field geological observations,geochronological data and optical petrography indicated that Hejiangkou deposit underwent multi-period of superimposed mineralization.It can be differentiated into three periods composed of six mineralization stages.The first period is the initial period for hydrothermal metasomatism and metal element enrichment during Indosinian Epoch.Further enrichment,strong brittle fracturing and hydrothermal metasomatism,remobilization and superimposition happened in the second period,during early Yanshanian.It is the major mineralization period of Hejiangkou deposit and can be subdivided into four mineralization stages,namely the skarn stage,oxide stage,high-temperature sulfide stage and low-temperature sulfide stage.And the third period is the mineralization period of a porphyry-skarn system related to the emplacement of the granite porphyry dyke.As minerogenic epoch of Hejiangkou deposit is similar with Hehuaping deposit,they show the possibility of Indosinian mineralization event in Nanling metallogenic zone.It can be an important perspective in any future mineral exploration in the same metallogenic zone.展开更多
Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites （Pingtung City, Chao-Chou Town, and Kenting Town） in Pingtung County in southern Taiwan during 2003 and 200...Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites （Pingtung City, Chao-Chou Town, and Kenting Town） in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds （VOC）-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators （H202, HNO3, and NOy） were conducted, and simulated three transition ranges of H202/HNO3 （0.5-0.8）, O3/HNO3 （10.3-16.2） and O3/NOy （5.7-10.8） were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.展开更多
Temporal changes in site effects are obtained using the HVSR(horizontal-to-vertical spectral ratio) method and strong motion records after the M w 7.6 Chi-Chi earthquake, Taiwan. Seismic data recorded between 1995 and...Temporal changes in site effects are obtained using the HVSR(horizontal-to-vertical spectral ratio) method and strong motion records after the M w 7.6 Chi-Chi earthquake, Taiwan. Seismic data recorded between 1995 and 2010 are used, comprising 3,708 data from 15 stations adjacent to the Chelungpu fault. Temporal fl uctuations are determined by analyzing the site effect variation using a time–frequency variation(TFV) diagram based on these seismic data. Stations adjacent to the fault show signifi cant disturbances in the resonance frequency at 16–26 Hz. Station TCU129 shows a 40% drop in fundamental frequency after the main shock, and a gradual return to the original state over nine years. For stations located farther from the fault zone, sudden changes in tectonic stress play a dominant role in temporal changes to the HVSR. An impact analysis of the directional factor confi rms our fi nding that the proximity of the fault to seismic stations has the most infl uence on data.展开更多
A numerical method is put forward in this paper, using the boundary element method （BEM） to model 3D terrain effects on magnetotelluric （MT） surveys, Using vector integral theory and electromagnetic field boundary...A numerical method is put forward in this paper, using the boundary element method （BEM） to model 3D terrain effects on magnetotelluric （MT） surveys, Using vector integral theory and electromagnetic field boundary conditions, the boundary problem of two electromagnetic fields in the upper half space （air） and lower half space （earth medium） was transformed into two vector integral equations just related to the topography ： one magnetic equation for computing the magnetic field and the other electrical equation for computing the electrical field. The topography integral is decomposed into a series of integrals in a triangle element. For the integral in a triangle element, we suppose that the electromagnetic field in it is the stack of the electromagnetic field in the homogeneous earth and the topography response which is a constant; so the computation becomes simple, convenient and highly accurate. By decomposition and computation, each vector integral equation can be calculated by solving three linear equations that are related to the three Cartesian directions. The matrix of these linear equations is diagonally dominant and can be solved using the Symmetric Successive Over-Relaxation （SSOR） method. The apparent resistivity curve of MT on two 3D terrains calculated by BEM is shown in this paper.展开更多
This paper first visits uniqueness, scale, and resolution issues in groundwater flow forward modeling problems. It then makes the point that non-unique solutions to groundwater flow inverse problems arise from a lack ...This paper first visits uniqueness, scale, and resolution issues in groundwater flow forward modeling problems. It then makes the point that non-unique solutions to groundwater flow inverse problems arise from a lack of information necessary to make the problems well defined. Subsequently, it presents the necessary conditions for a well-defined inverse problem. They are full specifications of （1） flux boundaries and sources/sinks, and （2） heads everywhere in the domain at at least three times （one of which is t = 0）, with head change everywhere at those times being nonzero for transient flow. Numerical experiments are presented to corroborate the fact that, once the necessary conditions are met, the inverse problem has a unique solution. We also demonstrate that measurement noise, instability, and sensitivity are issues related to solution techniques rather than the inverse problems themselves. In addition, we show that a mathematically well-defined inverse problem, based on an equivalent homogeneous or a layered conceptual model, may yield physically incorrect and scenario-dependent parameter values. These issues are attributed to inconsistency between the scale of the head observed and that implied by these models. Such issues can be reduced only if a sufficiently large number of observation wells are used in the equivalent homogeneous domain or each layer. With a large number of wells, we then show that increase in parameterization can lead to a higher-resolution depiction of heterogeneity if an appropriate inverse methodology is used. Furthermore, we illustrate that, using the same number of wells, a highly parameterized model in conjunction with hydraulic tomography can yield better characterization of the aquifer and minimize the scale and scenario-dependent problems. Lastly, benefits of the highly parameterized model and hydraulic tomography are tested according to their ability to improve predictions of aquifer responses induced by independent stresses not used in the inverse modeling efforts.展开更多
The Dabie-Sulu orogenic belt in central-eastern China is considered as a high-pressure and ultrahighpressure metamorphic belt that demensions are comparatively large,and formed as a result of the collision of Sino-Kor...The Dabie-Sulu orogenic belt in central-eastern China is considered as a high-pressure and ultrahighpressure metamorphic belt that demensions are comparatively large,and formed as a result of the collision of Sino-Korean and Yangtze cratons in eastern China. After continuous discoveries of high-pressure and ultra-high pressure metamorphic assemblages in the Dabie-Sulu area,the issue of the Dabie-Sulu orogenic belt extending eastward to the Korean Peninsula has been paid attentions widely. The discoveries of eclogites in the Hongsoeng area,the middle-western Korean Peninsula gives rise to the debate on the tectonic affiliations of the southern massifs. Although the Rimjingang belt in the Korean peninsula has been well investigated,the relation and comparative study to the Dabie-Sulu orogenic belt are lacking of detail work. In this paper,on the basis of informations and results of our previous works,some new contrastive considerations on the correlation between the Dabie-Sulu orogenic belt in central-eastern China and Rimjingang belt in the Korean Peninsula have are provided.展开更多
There are many results of single mineral enrichment characteristic, such as oil, gas, coal and uranium, but little is known about the synergistic research of these important minerals and the study of uranium enrichmen...There are many results of single mineral enrichment characteristic, such as oil, gas, coal and uranium, but little is known about the synergistic research of these important minerals and the study of uranium enrichment features in the deep basin. So, the study on the paragenesis regularity and coexisting relation of many minerals in the basin will promote the integrated forecast and cooperative exploitation of the basin. Based on the plentiful logging data and geological data, this paper studies the distributing feature of higher Gamma abnormality. The analysis on 33 core samples' test results indicates that the increasing of Gamma abnormality is due to the increasing of the uranium element, and the enrichment of uranium is a result of the activation and conglomeration of uranium. On the basis of the recognization of radioactive abnormality and the study about the reality of oil,gas,coal or uranium coexisting in a basin and its mechanism, the paper shows that there is a certain mutual promotion in oil, gas, coal and uranium in the basin, which provides an important theory basis for cooperative exploitation of energy resources.展开更多
The effects of the Ca0.7Nd0.2Ti O3 ceramic addition on the crystallization,densification,and dielectric properties of CaO–B2O3–SiO2–(Al2O3)glass(C1:CaO–B2O3–SiO2 glass and C1A03:CaO–B2O3–SiO2–Al2O3 glass)for l...The effects of the Ca0.7Nd0.2Ti O3 ceramic addition on the crystallization,densification,and dielectric properties of CaO–B2O3–SiO2–(Al2O3)glass(C1:CaO–B2O3–SiO2 glass and C1A03:CaO–B2O3–SiO2–Al2O3 glass)for low-temperature co-fired ceramic(LTCC)applications are investigated.The cristobalite phase crystallized from C1 glass was inhibited by adding Al2O3.During sintering,Ca0.7Nd0.2TiO3 ceramic reacted with CaO–B2O3–SiO2–(Al2O3)glass to form the sphene(CaTiSiO5)phase.The amount of sphene phase increases with increasing sintering temperature.By adding 50–60 wt%C1 or C1A03 glass,Ca0.7Nd0.2TiO3 can be densified at 850–900℃.The relative dielectric constants for Ca0.7Nd0.2TiO3 added with C1 and C1A03 glasses were all 20–23.Ca0.7Nd0.2TiO3 added with C1 glass exhibited a lower dielectric constant than C1A03 glass due to cristobalite phase formation.For Ca0.7Nd0.2TiO3 ceramics added with 50 wt%glass,the variation in Q×f value presented the same trend as the sphene formation amount variation.The best Q×f value of 2380 GHz was achieved for Ca0.7Nd0.2TiO3 ceramics added with 50 wt%C1A03 glass sintered at 900℃due to the dense structure and greater amount of sphene.Ca0.7Nd0.2TiO3 ceramics added with50 wt%C1A03 glass sintered at 900℃exhibited a dielectric constant of 22.8 and Q×f value of2380 GHz,which are suitable for microwave LTCC applications.展开更多
The Chinese coastal regions are the high risk areas of natural disasters for their lowland and weak and sensitive eco-evironment. The relative sea-level rising (RSLR), resulting from the piling of global sea-level ris...The Chinese coastal regions are the high risk areas of natural disasters for their lowland and weak and sensitive eco-evironment. The relative sea-level rising (RSLR), resulting from the piling of global sea-level rising and regional land subsidence, is to speed up in the 21st century. Certainly the RSLR will exacerbate the land submerging, the disaster from storm-tide and flood-waterlogging and the water shortage, and then affect urban withstanding function, construction safety and eco-resources. According to sustainable development theory, the sustainable utilization of resources and environment and sustainable development of economy and society can both be effectively achieved in coastal regions of China in the 21st century only by the implementation of controlling discharge of greenhouse gas, optimal exploitation of and artificial recharge of ground-water, systematic control of land subsidence, higher design standards for tide and flood controlengineering, improving urban anti-disaster ability, a study on strategy and policy for RSLR and establishment of forecast and pre-warning institution.展开更多
Floods are natural hazards that lead to devastating financial losses and large displacements of people.Flood susceptibility maps can improve mitigation measures according to the specific conditions of a study area.The...Floods are natural hazards that lead to devastating financial losses and large displacements of people.Flood susceptibility maps can improve mitigation measures according to the specific conditions of a study area.The design of flood susceptibility maps has been enhanced through use of hybrid machine learning and deep learning models.Although these models have achieved better accuracy than traditional models,they are not widely used by stakeholders due to their black-box nature.In this study,we propose the application of an explainable artificial intelligence(XAI)model that incorporates the Shapley additive explanation(SHAP)model to interpret the outcomes of convolutional neural network(CNN)deep learning models,and analyze the impact of variables on flood susceptibility mapping.This study was conducted in Jinju Province,South Korea,which has a long history of flood events.Model performance was evaluated using the area under the receiver operating characteristic curve(AUROC),which showed a prediction accuracy of 88.4%.SHAP plots showed that land use and various soil attributes significantly affected flood susceptibility in the study area.In light of these findings,we recommend the use of XAIbased models in future flood susceptibility mapping studies to improve interpretations of model outcomes,and build trust among stakeholders during the flood-related decision-making process.展开更多
基金supported by the Korea Evaluation Institute of Industrial Technology funded by the Korean Ministry of Industry in Korea (Project No.:20000970, 20–9805)Basic Research Project (22–3803) of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Science and ICT of Korea。
文摘A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing Mg O as a feedstock. The electrolysis of various Mg O resources was conducted using a Cu cathode in MgF2– LiF – KCl molten salt at 1043 K by applying an average current of 1.44 A for 12.5 h. The electrolysis of calcined North Korean magnesite and seawater Mg O clinker yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 89.6–92.4%. The electrolysis of oxidized Mg O-C refractory brick, aged ferronickel slag, and ferronickel slag yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 59.3–92.3%. The vacuum distillation of Mg alloys obtained was conducted at 1300 K for 10 h to produce high-purity Mg metal. After vacuum distillation, Mg metal with a purity of above 99.994% was obtained. Therefore, this study demonstrates the feasibility of the production of high-purity Mg metal from various Mg O resources using a novel electrolytic process with a Cu cathode, followed by vacuum distillation.
基金Project(SKLCRSM13KFB05)supported by State Key Laboratory for Coal Resources and Safe Mining(China University of Mining&Technology)
文摘Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.
基金key National Natural Science Foundation of Anhui University(2006KJ009A)
文摘The impact on these water bodies of the surrounding coal production activities and the power plant through research the content and characteristics of harmful trace elements in coal contained in these water bodies.F,Hg,Se and As these four trace ele- ments increased 0.92%,0.78%,0.70% and 0.81% respectively in Datong mining subsi- dence pool from November 2004 to November 2006;the four elements increased 1.58%, 1.23%,1.08% and 0.92% respectively in Xie'er mining subsidence pool;the four ele- ments increased 1.16%,1.06%,1.02% and 1.01% respectively in Pansan mining sub- sidence pool.The conclusions show that the absolute values of F,Hg,Se and As in mining subsidence pool are relate with their background value,while the increase in their concen- tration and their environment of mine and electricity plant surrounded are closely linked.
基金Projects 070414168 supported by the Provincial University National Natural Science Foundation of Anhui2006KJ009A by the Key National Science Foundation of Anhui Province
文摘Mining subsidence pools are water bodies formed by soil subsidence near mines. We studied the impact the surrounding coal production activities and power plants have on these waters by measuring the concentrations of harmful trace elements in these waters. The concentration of the four elements F, Hg, Se and As increased by 0.92%, 0.78%, 0.70% and 0.81%, respectively, in the Datong mining subsidence pool from November 2004 to November 2006. The four elements increased by 1.58%, 1.23%, 1.08% and 0.92%, respectively, in the Xie’er mining subsidence pool and 1.16%, 1.06%, 1.02% and 1.01%, respectively, in the Pansan mining subsidence pool over the same time period. The absolute levels of F, Hg, Se and As in the pool are related to the background levels of the elements. A close relationship between nearby coal mines and power plants and increasing levels of the measured elements is noted.
基金supported by the National Research Councile of Science and Technology funded by the Korean Ministry of Industry in Korea(Project Nos.:1711173260,22-3803)the Korea Evaluation Institute of Industrial Technology funded by the Korean Ministry of Industry in Korea(Project Nos.:1415179713,20011157).
文摘In this study,a novel Mg production process for producing high-purity Mg metal from dolomite was developed.When the electrolysis of calcined dolomite was conducted using Cu cathode and C anode in MgF_(2)–LiF molten salt at 1083–1173 K by applying an average current of 1.42–1.46 A for 9.50–21.0 h,the current efficiency of 66.4–88.6%was obtained.The produced Mg alloys consisted of MgCu_(2)and Cu(Mg)or MgCu_(2)and CuMg_(2)phases,depending on the Mg concentration in the Mg alloy.When the electrolysis of calcined dolomite was conducted in MgF_(2)–LiF–CaF_(2)molten salt at 1083 K,the current efficiency was 40.9–71.4%,owing to undesired reactions such as electroreduction of Ca^(2+)or/and CO_(3)^(2−)ions.Meanwhile,the current efficiency increased from 40.9%to 63.2%by utilizing a Pt anode,because the occurrence of CO_(3)^(2−)ions in the molten salt was prevented.After vacuum distillation of the obtained Mg alloys at 1300 K for 10 h,Mg metal with a purity of 99.9996–99.9998%was produced.Therefore,the feasibility of this novel process for the production of high-purity Mg metal from dolomite was demonstrated.
文摘Experiments using electrical resistivity tomography(ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements only.To explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes,namely the classical smoothness-constrained inversion and a geostatistically based approach,we performed two-dimensional synthetic experiments.Simplifying assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions,including the number of boreholes,measurement schemes,contrast between the plume and background electrical conductivity,use of a priori knowledge,and point conditioning.The results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality,which can be further improved when point measurements are incorporated and advantageous measurement schemes are chosen.As expected,an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics,while in this case the benefits of point conditioning and advantageous measurement schemes diminish.Both ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity,and robust with regard to biased input parameters,such as mean concentration,variance,and correlation length of the plume.Although sophisticated inversion schemes have recently become available,in which flow and transport as well as electrical forward models are coupled,these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological model.Therefore,we believe that standard uncoupled ERT inverse approaches,like the ones discussed and assessed in this paper,will continue to be important to the imaging and characterization of solute plumes in many real-world applications.
基金the National Program on Key Science Research of the DPR of Korea.(Grant No.0305014-01)。
文摘This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers,considering the long-term climate.The paper suggests a method to predict the low-cycle fatigue life by demonstrating a thermal-fluid-structural analysis of bridge pier concrete according to long-term climate such as temperature,velocity and pressure of air and water in the process of freezing and thawing in winter.In addition,it proposes a reinforcing method to increase the life of damaged piers and proves the feasibility of the proposed method with numerical comparison experiment.
基金Project(41403035)supported by the National Natural Science Foundation of ChinaProject(13JJ4041)supported by Hunan Provincial National Natural Science Foundation,China
文摘Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field,one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone.Re-Os isotope dating was used on three molybdenite samples from Hejiangkou deposit to determine the ore forming period.The result is(224.9±2.6)Ma-(225±3.1)Ma and isochron age is(225.5±3.6)Ma.The field geological observations,geochronological data and optical petrography indicated that Hejiangkou deposit underwent multi-period of superimposed mineralization.It can be differentiated into three periods composed of six mineralization stages.The first period is the initial period for hydrothermal metasomatism and metal element enrichment during Indosinian Epoch.Further enrichment,strong brittle fracturing and hydrothermal metasomatism,remobilization and superimposition happened in the second period,during early Yanshanian.It is the major mineralization period of Hejiangkou deposit and can be subdivided into four mineralization stages,namely the skarn stage,oxide stage,high-temperature sulfide stage and low-temperature sulfide stage.And the third period is the mineralization period of a porphyry-skarn system related to the emplacement of the granite porphyry dyke.As minerogenic epoch of Hejiangkou deposit is similar with Hehuaping deposit,they show the possibility of Indosinian mineralization event in Nanling metallogenic zone.It can be an important perspective in any future mineral exploration in the same metallogenic zone.
基金supported by the Environmental Protection Bureau,Government of Pingtung County,Taiwan,China
文摘Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites （Pingtung City, Chao-Chou Town, and Kenting Town） in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds （VOC）-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators （H202, HNO3, and NOy） were conducted, and simulated three transition ranges of H202/HNO3 （0.5-0.8）, O3/HNO3 （10.3-16.2） and O3/NOy （5.7-10.8） were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.
文摘Temporal changes in site effects are obtained using the HVSR(horizontal-to-vertical spectral ratio) method and strong motion records after the M w 7.6 Chi-Chi earthquake, Taiwan. Seismic data recorded between 1995 and 2010 are used, comprising 3,708 data from 15 stations adjacent to the Chelungpu fault. Temporal fl uctuations are determined by analyzing the site effect variation using a time–frequency variation(TFV) diagram based on these seismic data. Stations adjacent to the fault show signifi cant disturbances in the resonance frequency at 16–26 Hz. Station TCU129 shows a 40% drop in fundamental frequency after the main shock, and a gradual return to the original state over nine years. For stations located farther from the fault zone, sudden changes in tectonic stress play a dominant role in temporal changes to the HVSR. An impact analysis of the directional factor confi rms our fi nding that the proximity of the fault to seismic stations has the most infl uence on data.
基金This paper is supported by the National Natural Science Foundation ofChina (No .40344002) .
文摘A numerical method is put forward in this paper, using the boundary element method （BEM） to model 3D terrain effects on magnetotelluric （MT） surveys, Using vector integral theory and electromagnetic field boundary conditions, the boundary problem of two electromagnetic fields in the upper half space （air） and lower half space （earth medium） was transformed into two vector integral equations just related to the topography ： one magnetic equation for computing the magnetic field and the other electrical equation for computing the electrical field. The topography integral is decomposed into a series of integrals in a triangle element. For the integral in a triangle element, we suppose that the electromagnetic field in it is the stack of the electromagnetic field in the homogeneous earth and the topography response which is a constant; so the computation becomes simple, convenient and highly accurate. By decomposition and computation, each vector integral equation can be calculated by solving three linear equations that are related to the three Cartesian directions. The matrix of these linear equations is diagonally dominant and can be solved using the Symmetric Successive Over-Relaxation （SSOR） method. The apparent resistivity curve of MT on two 3D terrains calculated by BEM is shown in this paper.
基金supported by the Strategic Environmental Research and Development Program(Grant No.ER-1365)the Environmental Security and Technology Certification Program(Grant No.ER201212)the Earth Sciences of the National Science Foundation(Grant No.1014594)
文摘This paper first visits uniqueness, scale, and resolution issues in groundwater flow forward modeling problems. It then makes the point that non-unique solutions to groundwater flow inverse problems arise from a lack of information necessary to make the problems well defined. Subsequently, it presents the necessary conditions for a well-defined inverse problem. They are full specifications of （1） flux boundaries and sources/sinks, and （2） heads everywhere in the domain at at least three times （one of which is t = 0）, with head change everywhere at those times being nonzero for transient flow. Numerical experiments are presented to corroborate the fact that, once the necessary conditions are met, the inverse problem has a unique solution. We also demonstrate that measurement noise, instability, and sensitivity are issues related to solution techniques rather than the inverse problems themselves. In addition, we show that a mathematically well-defined inverse problem, based on an equivalent homogeneous or a layered conceptual model, may yield physically incorrect and scenario-dependent parameter values. These issues are attributed to inconsistency between the scale of the head observed and that implied by these models. Such issues can be reduced only if a sufficiently large number of observation wells are used in the equivalent homogeneous domain or each layer. With a large number of wells, we then show that increase in parameterization can lead to a higher-resolution depiction of heterogeneity if an appropriate inverse methodology is used. Furthermore, we illustrate that, using the same number of wells, a highly parameterized model in conjunction with hydraulic tomography can yield better characterization of the aquifer and minimize the scale and scenario-dependent problems. Lastly, benefits of the highly parameterized model and hydraulic tomography are tested according to their ability to improve predictions of aquifer responses induced by independent stresses not used in the inverse modeling efforts.
文摘The Dabie-Sulu orogenic belt in central-eastern China is considered as a high-pressure and ultrahighpressure metamorphic belt that demensions are comparatively large,and formed as a result of the collision of Sino-Korean and Yangtze cratons in eastern China. After continuous discoveries of high-pressure and ultra-high pressure metamorphic assemblages in the Dabie-Sulu area,the issue of the Dabie-Sulu orogenic belt extending eastward to the Korean Peninsula has been paid attentions widely. The discoveries of eclogites in the Hongsoeng area,the middle-western Korean Peninsula gives rise to the debate on the tectonic affiliations of the southern massifs. Although the Rimjingang belt in the Korean peninsula has been well investigated,the relation and comparative study to the Dabie-Sulu orogenic belt are lacking of detail work. In this paper,on the basis of informations and results of our previous works,some new contrastive considerations on the correlation between the Dabie-Sulu orogenic belt in central-eastern China and Rimjingang belt in the Korean Peninsula have are provided.
文摘There are many results of single mineral enrichment characteristic, such as oil, gas, coal and uranium, but little is known about the synergistic research of these important minerals and the study of uranium enrichment features in the deep basin. So, the study on the paragenesis regularity and coexisting relation of many minerals in the basin will promote the integrated forecast and cooperative exploitation of the basin. Based on the plentiful logging data and geological data, this paper studies the distributing feature of higher Gamma abnormality. The analysis on 33 core samples' test results indicates that the increasing of Gamma abnormality is due to the increasing of the uranium element, and the enrichment of uranium is a result of the activation and conglomeration of uranium. On the basis of the recognization of radioactive abnormality and the study about the reality of oil,gas,coal or uranium coexisting in a basin and its mechanism, the paper shows that there is a certain mutual promotion in oil, gas, coal and uranium in the basin, which provides an important theory basis for cooperative exploitation of energy resources.
基金financially supported by “the Ministry of Science and Technology” (106-2923-E-006-009-MY3)
文摘The effects of the Ca0.7Nd0.2Ti O3 ceramic addition on the crystallization,densification,and dielectric properties of CaO–B2O3–SiO2–(Al2O3)glass(C1:CaO–B2O3–SiO2 glass and C1A03:CaO–B2O3–SiO2–Al2O3 glass)for low-temperature co-fired ceramic(LTCC)applications are investigated.The cristobalite phase crystallized from C1 glass was inhibited by adding Al2O3.During sintering,Ca0.7Nd0.2TiO3 ceramic reacted with CaO–B2O3–SiO2–(Al2O3)glass to form the sphene(CaTiSiO5)phase.The amount of sphene phase increases with increasing sintering temperature.By adding 50–60 wt%C1 or C1A03 glass,Ca0.7Nd0.2TiO3 can be densified at 850–900℃.The relative dielectric constants for Ca0.7Nd0.2TiO3 added with C1 and C1A03 glasses were all 20–23.Ca0.7Nd0.2TiO3 added with C1 glass exhibited a lower dielectric constant than C1A03 glass due to cristobalite phase formation.For Ca0.7Nd0.2TiO3 ceramics added with 50 wt%glass,the variation in Q×f value presented the same trend as the sphene formation amount variation.The best Q×f value of 2380 GHz was achieved for Ca0.7Nd0.2TiO3 ceramics added with 50 wt%C1A03 glass sintered at 900℃due to the dense structure and greater amount of sphene.Ca0.7Nd0.2TiO3 ceramics added with50 wt%C1A03 glass sintered at 900℃exhibited a dielectric constant of 22.8 and Q×f value of2380 GHz,which are suitable for microwave LTCC applications.
文摘The Chinese coastal regions are the high risk areas of natural disasters for their lowland and weak and sensitive eco-evironment. The relative sea-level rising (RSLR), resulting from the piling of global sea-level rising and regional land subsidence, is to speed up in the 21st century. Certainly the RSLR will exacerbate the land submerging, the disaster from storm-tide and flood-waterlogging and the water shortage, and then affect urban withstanding function, construction safety and eco-resources. According to sustainable development theory, the sustainable utilization of resources and environment and sustainable development of economy and society can both be effectively achieved in coastal regions of China in the 21st century only by the implementation of controlling discharge of greenhouse gas, optimal exploitation of and artificial recharge of ground-water, systematic control of land subsidence, higher design standards for tide and flood controlengineering, improving urban anti-disaster ability, a study on strategy and policy for RSLR and establishment of forecast and pre-warning institution.
基金supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources(KIGAM)and the National Research Foundation of Korea(NRF)grant funded by Korea government(MSIT)(No.2023R1A2C1003095).
文摘Floods are natural hazards that lead to devastating financial losses and large displacements of people.Flood susceptibility maps can improve mitigation measures according to the specific conditions of a study area.The design of flood susceptibility maps has been enhanced through use of hybrid machine learning and deep learning models.Although these models have achieved better accuracy than traditional models,they are not widely used by stakeholders due to their black-box nature.In this study,we propose the application of an explainable artificial intelligence(XAI)model that incorporates the Shapley additive explanation(SHAP)model to interpret the outcomes of convolutional neural network(CNN)deep learning models,and analyze the impact of variables on flood susceptibility mapping.This study was conducted in Jinju Province,South Korea,which has a long history of flood events.Model performance was evaluated using the area under the receiver operating characteristic curve(AUROC),which showed a prediction accuracy of 88.4%.SHAP plots showed that land use and various soil attributes significantly affected flood susceptibility in the study area.In light of these findings,we recommend the use of XAIbased models in future flood susceptibility mapping studies to improve interpretations of model outcomes,and build trust among stakeholders during the flood-related decision-making process.
