The increasing severity of ground subsidence,ground fissure and other disasters caused by the excessive exploitation of deep underground resources has highlighted the pressing need for effective management.A significa...The increasing severity of ground subsidence,ground fissure and other disasters caused by the excessive exploitation of deep underground resources has highlighted the pressing need for effective management.A significant contributing factor to the challenges faced is the inadequacy of existing soil mechanics experimental instruments in providing effective indicators,creating a bottleneck in comprehensively understanding the mechanisms of land subsidence.It is urgent to develop a multi-field and multi-functional soil mechanics experimental system to address this issue.Based soil mechanics theories,the existing manufacturing capabilities of triaxial apparatus and the practical demands of the test system,a set of multi-field coupled high-pressure triaxial system is developed tailored for testing deep soils(at depths of approximately 3000 m)and soft rock.This system incorporates specialized design elements such as high-pressure chamber and horizontal deformation testing devices.In addition to the conventional triaxial tester functions,its distinctive feature encompass a horizontal deformation tracking measuring device,a water release testing device and temperature control device for the sample.This ensemble facilitates testing of horizontal and vertical deformation water release and other parameters of samples under a specified stress conditions,at constant or varying temperature ranging from-40℃–90℃.The accuracy of the tested parameters meets the requirements of relevant current specifications.The test system not only provides scientifically robust data for revealing the deformation and failure mechanism of soil subjected to extreme temperature,but also offers critical data support for major engineering projects,deep exploration and mitigation efforts related to soil deformation-induced disaster.展开更多
Diode clamped multi-level inverter （DCMLI） has a wide application prospect in high-voltage and adjustable speed drive systems due to its low stress on switching devices, low harmonic output, and simple structure. Ho...Diode clamped multi-level inverter （DCMLI） has a wide application prospect in high-voltage and adjustable speed drive systems due to its low stress on switching devices, low harmonic output, and simple structure. However, the problem of complexity of selecting vectors and capacitor voltage unbalance needs to be solved when the algorithm of direct torque control （DTC） is implemented on DCMLI. In this paper, a fuzzy DTC system of an induction machine fed by a three-level neutral-point-clamped （NPC） inverter is proposed. After introducing fuzzy logic, optimal selecting switching state is realized by applying various strategies which can distinguish the grade of the errors of stator flux linkage, torque, the neutral-point potential, and the position of stator flux linkage. Consequently, the neutral-point potential unbalance, the dr/dr of output voltage and the switching loss are restrained effectively, and desirable dynamic and steady-state performances of induction machines can be obtained for the DTC scheme. A design method of the fuzzy controller is introduced in detail, and the relevant simulation and experimental results have verified the feasibility of the proposed control algorithm.展开更多
Discrete fracture models are used for investigating precise processes of groundwater flow in fractured rocks,while a disc-shaped parallel-plates model for a single fracture is more reasonable and efficient for computa...Discrete fracture models are used for investigating precise processes of groundwater flow in fractured rocks,while a disc-shaped parallel-plates model for a single fracture is more reasonable and efficient for computational treatments.The flow velocity has a large spatial differentiation which is more likely to produce non-linear flow and additional head losses on and nearby intersections in such shaped fractures,therefore it is necessary to understand and quantify them.In this study,both laboratory experiments and numerical simulations were performed to investigate the total head loss on and nearby the intersections as well as the local head loss exactly on the intersections,which were not usually paid sufficient attention or even ignored.The investigation results show that these two losses account for 29.17%-84.97%and 0-73.57%of the entire total head loss in a fracture,respectively.As a result,they should be necessarily considered for groundwater modeling in fractured rocks.Furthermore,both head losses become larger when aperture and flow rate increase and intersection length decreases.Particularly,the ratios of these two head losses to the entire total head loss in a fracture could be well statistically explained by power regression equations with variables of aperture,intersection length,and flow rates,both of which achieved high coefficients of determination.It could be feasible through this type of study to provide a way on how to adjust the groundwater head from those obtained by numerical simulations based on the traditional linear flow model.Finally,it is practicable and effective to implement the investigation approach combining laboratory experiments with numerical simulations for quantifying the head losses on and nearby the intersections between disc-shaped fractures.展开更多
The release characteristics of CH_(4),H_(2),CO and CO_(2) from iron coke hot briquette(ICHB)during carbonization were studied.The results show that compared with briquette without iron ore,Fe_(3)O_(4) can inhibit the ...The release characteristics of CH_(4),H_(2),CO and CO_(2) from iron coke hot briquette(ICHB)during carbonization were studied.The results show that compared with briquette without iron ore,Fe_(3)O_(4) can inhibit the release rate of H2 and promote the production of CO and CO_(2).In addition,when the heating rate increases from 3 to 7℃/min,the release rates of CH4 and H2 increase,while the release rates of CO and CO_(2) first increase and then decrease.The carbonization process of ICHB was segmented,and corresponding kinetic analysis was carried out.The results show that the activation energy of StageⅡand StageⅣis higher in the carbonization process of ICHB,and the active pyrolysis of coal and the reduction of iron ore occur in these two stages.In addition,the effect of heating rate on the kinetic parameters of ICHB carbonization process was investigated.It was found that when the heating rate increased,the reaction activation energy of StageⅣdecreased first and then increased,which was consistent with the release law of CO and CO_(2).The analysis showed that the increase in heating rate leads to more reactions at higher temperatures,resulting in an increase in the release rate of some gases.In addition,thermal hysteresis can also cause some processes to fail to fully react at the end of heating.It is also found that the apparent activation energy and preexponential factor have kinetic compensation effect during the car-bonization of ICHB.展开更多
A P204 （D2EHPA） diluted with sulfonated kerosene was used for the selective extraction of molybdenum from an acidic Ni-Mo ore leach solution that was reduced using sodium thiosulfate. The results indicate that P204 ...A P204 （D2EHPA） diluted with sulfonated kerosene was used for the selective extraction of molybdenum from an acidic Ni-Mo ore leach solution that was reduced using sodium thiosulfate. The results indicate that P204 （D2EHPA） is an effective extractant for the extraction of molybdenum. The extraction of Mo is more than 90 % at pH of 0.5, contact time of 10 min, and organic-to- aqueous phase （O/A） ratio of 1：1 with 10 vol% P204 （D2EHPA）. Molybdenum in the loaded organic phase can be effectively stripped with ammonium acid carbonate solution, and the stripping of molybdenum with 60 g.L-1 ammonium acid carbonate solution is 94.67 % at O/A ratio of 2：1 and contact time of 10 min.展开更多
Objective:The objective of this study was to observe the effect of Yangxinshi tablets on the phenotype and function of peripheral blood monocytes in patients with unstable angina of coronary heart disease(CHD)and to e...Objective:The objective of this study was to observe the effect of Yangxinshi tablets on the phenotype and function of peripheral blood monocytes in patients with unstable angina of coronary heart disease(CHD)and to explore the possible mechanism of Yangxinshi tablets in the treatment of CHD.Methods:A total of 100 patients with unstable angina of CHD were randomly divided into two groups:Group A–treatment group and Group B–control group.The phenotypic and functional changes in blood monocytes and the changes in serum inflammatory factors before and after treatment were compared in the two groups.Results:The expression of CD14^+CD163^+interleukin(IL)-10^+was significantly higher in the control group than in the patients with unstable angina of CHD,whereas the expression of CD14^+CD163-IL-12^+was lower.The concentration of IL-10 was higher in the control group than in the patients with unstable angina,whereas the concentration of tumor necrosis factor-α(TNF-α)and IL-12 was significantly lower.In Group A,the expression of CD14^+CD163^+,CD14^+CD206^+,and CD14^+CD163^+CD206^+in peripheral blood monocytes increased after treatment than before treatment,whereas the expression of CD14^+CD163-CD206-decreased.The expression of CD14^+CD163-IL-12^+decreased after treatment than before,whereas CD14^+CD163^+IL-10^+expression increased.The serum concentration of IL-10 in Group A was higher after treatment than before,whereas that of IL-12 and TNF-αwas lower.In Group B,the phenotype and function of the peripheral blood monocytes remained unchanged.Conclusion:Yangxinshi tablet therapy can change the phenotype of the peripheral blood monocytes in patients with unstable angina of CHD.Yangxinshi tablet therapy changes the inflammatory state in patients with an increase in the expression of anti-inflammatory factors and a decrease in the expression of inflammatory factors.展开更多
The existing form of molybdenum in acidic sulfate solution was studied by means of ion exchange, infrared （IR） spectra and X-ray photoelectron spectroscopy （XPS）. The results indicate that the anionic molybdenum s...The existing form of molybdenum in acidic sulfate solution was studied by means of ion exchange, infrared （IR） spectra and X-ray photoelectron spectroscopy （XPS）. The results indicate that the anionic molybdenum species are predominant in acidic sulfate solution, and Mo（VI） can combine with sulfate radical to form heteropoly acid anions [Mo205（804）2]2- and [MoO2（HSO4）4]2-. With the decrease in solution pH from 1.92 to 0.06, the existing form of Mo（VI） changes from MovO21（OH）3^3- to [Mo205（S04）2]2- and then becomes [MoOz（HSO4）4]2-, which results in the decrease in the resin adsorption capacity for molybdenum.展开更多
基金the financial support from the National Natural Science Foundation of China(No.52104354)the Joint Fund for Nuclear Technology Innovation Sponsored by the National Natural Science Foundation of China and the China National Nuclear Corporation(No.U2067201)。
基金supported by National Natural Science Foundation(No.41272301 and No.42007171)Nature Fund of Hebei(No.D2021504034)Chinese Academy of Geological Sciences(No.YYWF201628).
文摘The increasing severity of ground subsidence,ground fissure and other disasters caused by the excessive exploitation of deep underground resources has highlighted the pressing need for effective management.A significant contributing factor to the challenges faced is the inadequacy of existing soil mechanics experimental instruments in providing effective indicators,creating a bottleneck in comprehensively understanding the mechanisms of land subsidence.It is urgent to develop a multi-field and multi-functional soil mechanics experimental system to address this issue.Based soil mechanics theories,the existing manufacturing capabilities of triaxial apparatus and the practical demands of the test system,a set of multi-field coupled high-pressure triaxial system is developed tailored for testing deep soils(at depths of approximately 3000 m)and soft rock.This system incorporates specialized design elements such as high-pressure chamber and horizontal deformation testing devices.In addition to the conventional triaxial tester functions,its distinctive feature encompass a horizontal deformation tracking measuring device,a water release testing device and temperature control device for the sample.This ensemble facilitates testing of horizontal and vertical deformation water release and other parameters of samples under a specified stress conditions,at constant or varying temperature ranging from-40℃–90℃.The accuracy of the tested parameters meets the requirements of relevant current specifications.The test system not only provides scientifically robust data for revealing the deformation and failure mechanism of soil subjected to extreme temperature,but also offers critical data support for major engineering projects,deep exploration and mitigation efforts related to soil deformation-induced disaster.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51974369)the Postgraduate Research Innovation Project of Central South University,China(2019zzts244).
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51974369)NSFC-STINT(No.52111530192)+1 种基金Postgraduate Research Innovation Project of Central South University,China(No.2019zzts244)the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University,China(No.CSUZC202029).
基金Project(51104186)supported by the National Natural Science Foundation of ChinaProject(2016JJ2142)supported by the Natural Science Foundation of Hunan Province,ChinaProject supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘Diode clamped multi-level inverter （DCMLI） has a wide application prospect in high-voltage and adjustable speed drive systems due to its low stress on switching devices, low harmonic output, and simple structure. However, the problem of complexity of selecting vectors and capacitor voltage unbalance needs to be solved when the algorithm of direct torque control （DTC） is implemented on DCMLI. In this paper, a fuzzy DTC system of an induction machine fed by a three-level neutral-point-clamped （NPC） inverter is proposed. After introducing fuzzy logic, optimal selecting switching state is realized by applying various strategies which can distinguish the grade of the errors of stator flux linkage, torque, the neutral-point potential, and the position of stator flux linkage. Consequently, the neutral-point potential unbalance, the dr/dr of output voltage and the switching loss are restrained effectively, and desirable dynamic and steady-state performances of induction machines can be obtained for the DTC scheme. A design method of the fuzzy controller is introduced in detail, and the relevant simulation and experimental results have verified the feasibility of the proposed control algorithm.
基金supported by National Key Research and Development Program of China(No.2020 YFC1807100,No.2019YFC1806205)National Natural Science Foundation of China(No.41572240)。
文摘Discrete fracture models are used for investigating precise processes of groundwater flow in fractured rocks,while a disc-shaped parallel-plates model for a single fracture is more reasonable and efficient for computational treatments.The flow velocity has a large spatial differentiation which is more likely to produce non-linear flow and additional head losses on and nearby intersections in such shaped fractures,therefore it is necessary to understand and quantify them.In this study,both laboratory experiments and numerical simulations were performed to investigate the total head loss on and nearby the intersections as well as the local head loss exactly on the intersections,which were not usually paid sufficient attention or even ignored.The investigation results show that these two losses account for 29.17%-84.97%and 0-73.57%of the entire total head loss in a fracture,respectively.As a result,they should be necessarily considered for groundwater modeling in fractured rocks.Furthermore,both head losses become larger when aperture and flow rate increase and intersection length decreases.Particularly,the ratios of these two head losses to the entire total head loss in a fracture could be well statistically explained by power regression equations with variables of aperture,intersection length,and flow rates,both of which achieved high coefficients of determination.It could be feasible through this type of study to provide a way on how to adjust the groundwater head from those obtained by numerical simulations based on the traditional linear flow model.Finally,it is practicable and effective to implement the investigation approach combining laboratory experiments with numerical simulations for quantifying the head losses on and nearby the intersections between disc-shaped fractures.
文摘The release characteristics of CH_(4),H_(2),CO and CO_(2) from iron coke hot briquette(ICHB)during carbonization were studied.The results show that compared with briquette without iron ore,Fe_(3)O_(4) can inhibit the release rate of H2 and promote the production of CO and CO_(2).In addition,when the heating rate increases from 3 to 7℃/min,the release rates of CH4 and H2 increase,while the release rates of CO and CO_(2) first increase and then decrease.The carbonization process of ICHB was segmented,and corresponding kinetic analysis was carried out.The results show that the activation energy of StageⅡand StageⅣis higher in the carbonization process of ICHB,and the active pyrolysis of coal and the reduction of iron ore occur in these two stages.In addition,the effect of heating rate on the kinetic parameters of ICHB carbonization process was investigated.It was found that when the heating rate increased,the reaction activation energy of StageⅣdecreased first and then increased,which was consistent with the release law of CO and CO_(2).The analysis showed that the increase in heating rate leads to more reactions at higher temperatures,resulting in an increase in the release rate of some gases.In addition,thermal hysteresis can also cause some processes to fail to fully react at the end of heating.It is also found that the apparent activation energy and preexponential factor have kinetic compensation effect during the car-bonization of ICHB.
基金financially supported by the National Natural Science Foundation of China(No.51104186)
文摘A P204 （D2EHPA） diluted with sulfonated kerosene was used for the selective extraction of molybdenum from an acidic Ni-Mo ore leach solution that was reduced using sodium thiosulfate. The results indicate that P204 （D2EHPA） is an effective extractant for the extraction of molybdenum. The extraction of Mo is more than 90 % at pH of 0.5, contact time of 10 min, and organic-to- aqueous phase （O/A） ratio of 1：1 with 10 vol% P204 （D2EHPA）. Molybdenum in the loaded organic phase can be effectively stripped with ammonium acid carbonate solution, and the stripping of molybdenum with 60 g.L-1 ammonium acid carbonate solution is 94.67 % at O/A ratio of 2：1 and contact time of 10 min.
文摘Objective:The objective of this study was to observe the effect of Yangxinshi tablets on the phenotype and function of peripheral blood monocytes in patients with unstable angina of coronary heart disease(CHD)and to explore the possible mechanism of Yangxinshi tablets in the treatment of CHD.Methods:A total of 100 patients with unstable angina of CHD were randomly divided into two groups:Group A–treatment group and Group B–control group.The phenotypic and functional changes in blood monocytes and the changes in serum inflammatory factors before and after treatment were compared in the two groups.Results:The expression of CD14^+CD163^+interleukin(IL)-10^+was significantly higher in the control group than in the patients with unstable angina of CHD,whereas the expression of CD14^+CD163-IL-12^+was lower.The concentration of IL-10 was higher in the control group than in the patients with unstable angina,whereas the concentration of tumor necrosis factor-α(TNF-α)and IL-12 was significantly lower.In Group A,the expression of CD14^+CD163^+,CD14^+CD206^+,and CD14^+CD163^+CD206^+in peripheral blood monocytes increased after treatment than before treatment,whereas the expression of CD14^+CD163-CD206-decreased.The expression of CD14^+CD163-IL-12^+decreased after treatment than before,whereas CD14^+CD163^+IL-10^+expression increased.The serum concentration of IL-10 in Group A was higher after treatment than before,whereas that of IL-12 and TNF-αwas lower.In Group B,the phenotype and function of the peripheral blood monocytes remained unchanged.Conclusion:Yangxinshi tablet therapy can change the phenotype of the peripheral blood monocytes in patients with unstable angina of CHD.Yangxinshi tablet therapy changes the inflammatory state in patients with an increase in the expression of anti-inflammatory factors and a decrease in the expression of inflammatory factors.
基金supported by the National Natural Science Foundation of China(No.51104186)
文摘The existing form of molybdenum in acidic sulfate solution was studied by means of ion exchange, infrared （IR） spectra and X-ray photoelectron spectroscopy （XPS）. The results indicate that the anionic molybdenum species are predominant in acidic sulfate solution, and Mo（VI） can combine with sulfate radical to form heteropoly acid anions [Mo205（804）2]2- and [MoO2（HSO4）4]2-. With the decrease in solution pH from 1.92 to 0.06, the existing form of Mo（VI） changes from MovO21（OH）3^3- to [Mo205（S04）2]2- and then becomes [MoOz（HSO4）4]2-, which results in the decrease in the resin adsorption capacity for molybdenum.
