With the increase in mining depth, the danger of coal and gas outbursts increases.In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration bo...With the increase in mining depth, the danger of coal and gas outbursts increases.In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas.Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained.The practice in the Panyi coal mine has shown that, after mining the C11coal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated.The result was that we achieved a safe and highly efficient mining operation of the C13 coal seam.展开更多
In the multi-radar networking system,aiming at the problem of locating long-distance targets synergistically with difficulty and low accuracy,a dual-station joint positioning method based on the target measurement err...In the multi-radar networking system,aiming at the problem of locating long-distance targets synergistically with difficulty and low accuracy,a dual-station joint positioning method based on the target measurement error feature complementarity is proposed.For dual-station joint positioning,by constructing the target positioning error distribution model and using the complementarity of spatial measurement errors of the same long-distance target,the area with high probability of target existence can be obtained.Then,based on the target distance information,the midpoint of the intersection between the target positioning sphere and the positioning tangent plane can be solved to acquire the target's optimal positioning result.The simulation demonstrates that this method greatly improves the positioning accuracy of target in azimuth direction.Compared with the traditional the dynamic weighted fusion(DWF)algorithm and the filter-based dynamic weighted fusion(FBDWF)algorithm,it not only effectively eliminates the influence of systematic error in the azimuth direction,but also has low computational complexity.Furthermore,for the application scenarios of multi-radar collaborative positioning and multi-sensor data compression filtering in centralized information fusion,it is recommended that using radar with higher ranging accuracy and the lengths of baseline between radars are 20–100 km.展开更多
Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquef...Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquefaction induced by sudden pressure release of the over-pressured sand body,and formation collapse due to gasification of pore fillings from pressure reduction,this study first systematically analyzes the progress of theoretical understanding,experimental methods,and mathematical representation,then discusses the engineering application scenarios corresponding to the three phenomena and reveals the mechanical principles and application effectiveness.Based on these research efforts,the study further discusses the significant challenges,potential developmental trends,and research approaches that require urgent exploration.The findings disclose that various phase-related rock mechanics phenomena require specific experimental and mathematical methods that can produce multi-field coupling mechanical mechanisms,which will eventually instruct the control on resource exploitation,evaluation on disaster level,and analysis of formation stability.To meet the development needs of the principle,future research efforts should focus on mining more phase-change related rock mechanics phenomena during oil and gas resources exploitation,developing novel experimental equipment,and using techniques of artificial intelligence and digital twins to implement real-time simulation and dynamic visualization of phase-change related rock mechanics.展开更多
In this study, we propose the use of the Degree of Alignment(DOA) in engineering applications for evaluating the precision of and identifying the transfer alignment on a moving base. First, we derive the statistical f...In this study, we propose the use of the Degree of Alignment(DOA) in engineering applications for evaluating the precision of and identifying the transfer alignment on a moving base. First, we derive the statistical formula on the basis of estimations. Next, we design a scheme for evaluating the transfer alignment on a moving base, for which the attitude error cannot be directly measured. Then, we build a mathematic estimation model and discuss Fixed Point Smoothing(FPS), Returns to Scale(RTS), Inverted Sequence Recursive Estimation(ISRE), and Kalman filter estimation methods, which can be used when evaluating alignment accuracy. Our theoretical calculations and simulated analyses show that the DOA reflects not only the alignment time and accuracy but also differences in the maneuver schemes, and is suitable for use as an integrated evaluation index. Furthermore, all four of these algorithms can be used to identify the transfer alignment and evaluate its accuracy. We recommend RTS in particular for engineering applications. Generalized DOAs should be calculated according to the tactical requirements.展开更多
The cleanup of carbon tetrachloride(CCl4)in groundwater is challenging due to its high volatility and tendency to form a dense nonaqueous liquid phase.From the engineering applications perspective,the pump-and-treat(P...The cleanup of carbon tetrachloride(CCl4)in groundwater is challenging due to its high volatility and tendency to form a dense nonaqueous liquid phase.From the engineering applications perspective,the pump-and-treat(PAT)technology has substantial advantages owing to its large-scale implementation ability to solve groundwater contamination.However,few studies focused on the variation in chloride contaminants in remediation sites after the contaminated groundwater was pumped and treated.Herein,we monitored the changes in chlorinated contamination in groundwater from 12 aquifers at the field level for 6 months.Considering that the natural attenuation of chlorinated contamination is inseparable from the action of microorganisms,the major environmental factors influencing biodegradation were also evaluated.A redundancy analysis(RDA)showed that inorganic salts(DS,DN,and DF)were the most important factor(>60%)affecting the concentration of chloride contaminants,including the negative correlation between DN and the degradation of contaminants in shallow aquifers.In deep aquifers,DS,DF,and pH explained most of the degradation of chloride contaminants.For bedrock layers,DCl was positively relevant to the chloride contaminants in wells PTJ2 and PTJ10.In addition,EC and DS accounted for 73.2%and 92.4%of the contaminant’s variance in wells PTJ4 and PTJ8,respectively.Moreover,the concentrations of the corresponding contaminations and physicochemical variation in three different depths of aquifers were compared;the shallower aquifers showed a higher biodegradation.The in situ monitoring and analysis of contaminated groundwater in remediation sites under PAT will promote practical wastewater treatment technologies in engineering applications.展开更多
基金Projects 2005CB221503 supported by the National Basic Research Program of China70533050 and 50674089 by the National Natural Science Foundationof China
文摘With the increase in mining depth, the danger of coal and gas outbursts increases.In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas.Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained.The practice in the Panyi coal mine has shown that, after mining the C11coal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated.The result was that we achieved a safe and highly efficient mining operation of the C13 coal seam.
文摘In the multi-radar networking system,aiming at the problem of locating long-distance targets synergistically with difficulty and low accuracy,a dual-station joint positioning method based on the target measurement error feature complementarity is proposed.For dual-station joint positioning,by constructing the target positioning error distribution model and using the complementarity of spatial measurement errors of the same long-distance target,the area with high probability of target existence can be obtained.Then,based on the target distance information,the midpoint of the intersection between the target positioning sphere and the positioning tangent plane can be solved to acquire the target's optimal positioning result.The simulation demonstrates that this method greatly improves the positioning accuracy of target in azimuth direction.Compared with the traditional the dynamic weighted fusion(DWF)algorithm and the filter-based dynamic weighted fusion(FBDWF)algorithm,it not only effectively eliminates the influence of systematic error in the azimuth direction,but also has low computational complexity.Furthermore,for the application scenarios of multi-radar collaborative positioning and multi-sensor data compression filtering in centralized information fusion,it is recommended that using radar with higher ranging accuracy and the lengths of baseline between radars are 20–100 km.
基金Supported by the National Natural Science Foundation of China(NSFC)Major Project(51991362).
文摘Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquefaction induced by sudden pressure release of the over-pressured sand body,and formation collapse due to gasification of pore fillings from pressure reduction,this study first systematically analyzes the progress of theoretical understanding,experimental methods,and mathematical representation,then discusses the engineering application scenarios corresponding to the three phenomena and reveals the mechanical principles and application effectiveness.Based on these research efforts,the study further discusses the significant challenges,potential developmental trends,and research approaches that require urgent exploration.The findings disclose that various phase-related rock mechanics phenomena require specific experimental and mathematical methods that can produce multi-field coupling mechanical mechanisms,which will eventually instruct the control on resource exploitation,evaluation on disaster level,and analysis of formation stability.To meet the development needs of the principle,future research efforts should focus on mining more phase-change related rock mechanics phenomena during oil and gas resources exploitation,developing novel experimental equipment,and using techniques of artificial intelligence and digital twins to implement real-time simulation and dynamic visualization of phase-change related rock mechanics.
基金Supported by the National Natural Science Foundation of China （61633008）, the National Natural Science Foundation of China （61203225）, the Natural Science Foundation of Heilongjiang Province of China（QC2014C069）, the Special fund for the Central Universities （HEUCF160401）, and Provincial Postdoctoral Scientific Research Foundation （LBH-Q 15032）.
文摘In this study, we propose the use of the Degree of Alignment(DOA) in engineering applications for evaluating the precision of and identifying the transfer alignment on a moving base. First, we derive the statistical formula on the basis of estimations. Next, we design a scheme for evaluating the transfer alignment on a moving base, for which the attitude error cannot be directly measured. Then, we build a mathematic estimation model and discuss Fixed Point Smoothing(FPS), Returns to Scale(RTS), Inverted Sequence Recursive Estimation(ISRE), and Kalman filter estimation methods, which can be used when evaluating alignment accuracy. Our theoretical calculations and simulated analyses show that the DOA reflects not only the alignment time and accuracy but also differences in the maneuver schemes, and is suitable for use as an integrated evaluation index. Furthermore, all four of these algorithms can be used to identify the transfer alignment and evaluate its accuracy. We recommend RTS in particular for engineering applications. Generalized DOAs should be calculated according to the tactical requirements.
基金National Natural Science Foundation of China(grant numbers 52070123)Natural Science Foundation of Shandong Province(ZR2020ME224,ZR2021QE160,ZR2021QB016)Project of Shandong Province Higher Educational Young Innovative Talent Introduction and Cultivation Team.
文摘The cleanup of carbon tetrachloride(CCl4)in groundwater is challenging due to its high volatility and tendency to form a dense nonaqueous liquid phase.From the engineering applications perspective,the pump-and-treat(PAT)technology has substantial advantages owing to its large-scale implementation ability to solve groundwater contamination.However,few studies focused on the variation in chloride contaminants in remediation sites after the contaminated groundwater was pumped and treated.Herein,we monitored the changes in chlorinated contamination in groundwater from 12 aquifers at the field level for 6 months.Considering that the natural attenuation of chlorinated contamination is inseparable from the action of microorganisms,the major environmental factors influencing biodegradation were also evaluated.A redundancy analysis(RDA)showed that inorganic salts(DS,DN,and DF)were the most important factor(>60%)affecting the concentration of chloride contaminants,including the negative correlation between DN and the degradation of contaminants in shallow aquifers.In deep aquifers,DS,DF,and pH explained most of the degradation of chloride contaminants.For bedrock layers,DCl was positively relevant to the chloride contaminants in wells PTJ2 and PTJ10.In addition,EC and DS accounted for 73.2%and 92.4%of the contaminant’s variance in wells PTJ4 and PTJ8,respectively.Moreover,the concentrations of the corresponding contaminations and physicochemical variation in three different depths of aquifers were compared;the shallower aquifers showed a higher biodegradation.The in situ monitoring and analysis of contaminated groundwater in remediation sites under PAT will promote practical wastewater treatment technologies in engineering applications.
