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Stability analysis of longwall top-coal caving face in extra-thick coal seams based on an innovative numerical hydraulic support model 被引量:1
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作者 Jun Guo Wenbo Huang +7 位作者 Guorui Feng Jinwen Bai Lirong Li Zi Wang Luyang Yu Xiaoze Wen Jie Zhang Wenming Feng 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第4期491-505,共15页
The relationship between support and surrounding rock is of great significance to the control of surrounding rock in mining process.In view of the fact that most of the existing numerical simulation methods construct ... The relationship between support and surrounding rock is of great significance to the control of surrounding rock in mining process.In view of the fact that most of the existing numerical simulation methods construct virtual elements and stress servo control to approximately replace the hydraulic support problem,this paper establishes a new numerical model of hydraulic support with the same working characteristics as the actual hydraulic support by integrating numerical simulation software Rhino,Griddle and FLAC3D,which can realize the simulation of different working conditions.Based on this model,the influence mechanism of the supporting strength of hydraulic support on surrounding rock stress regulation and coal stability in front of the top coal caving face in extra thick coal seam were researched.Firstly,under different support intensity,the abutment pressure of the bearing coal and the coal in front of it presents the “three-stage”evolution characteristics.The influence range of support intensity is 15%–30%.Secondly,1.5 MPa is the upper limit of impact that the support strength can have on the front coal failure area.Thirdly,within a displacement range of 2.76 m from the coal wall,a support strength of1.5 MPa provides optimal control of the horizontal displacement of the coal. 展开更多
关键词 Extremely thick coal seam Fully mechanized top coal caving Support strength Support-surrounding rock interaction
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Theoretical analysis and engineering application of controllable shock wave technology for enhancing coalbed methane in soft and low‑permeability coal seams
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作者 Guodong Qiao Zegong Liu +4 位作者 Yongmin Zhang Changping Yi Kui Gao Shigui Fu Youzhi Zhao 《International Journal of Coal Science & Technology》 EI CAS CSCD 2024年第2期123-142,共20页
Coalbed methane(CBM)is a significant factor in triggering coal and gas outburst disaster,while also serving as a clean fuel.With the increasing depth of mining operations,coal seams that exhibit high levels of gas con... Coalbed methane(CBM)is a significant factor in triggering coal and gas outburst disaster,while also serving as a clean fuel.With the increasing depth of mining operations,coal seams that exhibit high levels of gas content and low permeability have become increasingly prevalent.While controllable shockwave(CSW)technology has proven effective in enhancing CBM in laboratory settings,there is a lack of reports on its field applications in soft and low-permeability coal seams.This study establishes the governing equations for stress waves induced by CSW.Laplace numerical inversion was employed to analyse the dynamic response of the coal seam during CSW antireflection.Additionally,quantitative calculations were performed for the crushed zone,fracture zone,and effective CSW influence range,which guided the selection of field test parameters.The results of the field test unveiled a substantial improvement in the gas permeability coefficient,the average rate of pure methane flowrate,and the mean gas flowrate within a 10 m radius of the antireflection borehole.These enhancements were notable,showing increases of 3 times,13.72 times,and 11.48 times,respectively.Furthermore,the field test performed on the CSW antireflection gas extraction hole cluster demonstrated a noticeable improvement in CBM extraction.After antireflection,the maximum peak gas concentration and maximum peak pure methane flow reached 71.2%and 2.59 m^(3)/min,respectively.These findings will offer valuable guidance for the application of CSW antireflection technology in soft and low-permeability coal seams. 展开更多
关键词 CSW antireflection in coal seams CBM extraction enhancement Soft and low-permeability coal seams Field test
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Insights into carbon dioxide sequestration into coal seams through coupled gas flow-adsorption-deformation modelling
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作者 Hywel Thomas Min Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第1期26-40,共15页
Injecting carbon dioxide(CO_(2))into coal seams may unlock substantial carbon sequestration potential.Since the coal acts like a carbon filter,it can preferentially absorb significant amounts of CO_(2).To explore this... Injecting carbon dioxide(CO_(2))into coal seams may unlock substantial carbon sequestration potential.Since the coal acts like a carbon filter,it can preferentially absorb significant amounts of CO_(2).To explore this further,desorption of the adsorbed gas due to pressure drop is investigated in this paper,to achieve an improved understanding of the long-term fate of injected CO_(2) during post-injection period.This paper presents a dual porosity model coupling gas flow,adsorption and geomechanics for studying coupled processes and effectiveness of CO_(2) sequestration in coals.A new adsorption?desorption model derived based on thermodynamics is incorporated,particularly,the desorption hysteresis is considered.The reliability of the proposed adsorption-desorption isotherm is examined via validation tests.It is indicated that occurrence of desorption hysteresis is attributed to the adsorption-induced pore deformation.After injection ceases,the injected gas continues to propagate further from the injection well,while the pressure in the vicinity of the injection well experiences a significant drop.Although the adsorbed gas near the well also decreases,this decrease is less compared to that in pressure because of desorption hysteresis.The unceasing spread of CO_(2) and drops of pressure and adsorbed gas depend on the degree of desorption hysteresis and heterogeneity of coals,which should be considered when designing CO_(2) sequestration into coal seams. 展开更多
关键词 CO_(2)geological storage Coal seam ADSORPTION Desorption hysteresis
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Disasters of gas-coal spontaneous combustion in goaf of steeply inclined extra-thick coal seams
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作者 Qiming Zhang Enyuan Wang +2 位作者 Xiaojun Feng Shuxin Liu Dong Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第10期4141-4153,共13页
In light of the escalating global energy imperatives,mining of challenging-to-access resources,such as steeply inclined extra-thick coal seams(SIEC),has emerged as one of the future trends within the domain of energy ... In light of the escalating global energy imperatives,mining of challenging-to-access resources,such as steeply inclined extra-thick coal seams(SIEC),has emerged as one of the future trends within the domain of energy advancement.However,there is a risk of gas and coal spontaneous combustion coupling disasters(GCC)within the goaf of SIEC due to the complex goaf structure engendered by the unique mining methodologies of SIEC.To ensure that SIEC is mined safely and efficiently,this study conducts research on the GCC within the goaf of SIEC using field observation,theoretical analysis,and numerical modeling.The results demonstrate that the dip angle,the structural dimensions in terms of width-to-length ratio,and compressive strength of the overlying rock are the key factors contributing to the goaf instability of SIEC.The gangue was asymmetrically filled,primarily accumulating within the central and lower portions of the goaf,and the filling height increased proportionally with the advancing caving height,the expansion coefficient,and the thickness of the surrounding rock formation.The GCC occurs in the goaf of SIEC,with an air-return side range of 41 m and an air-intake side range of 14 m,at the intersection area of the“<”-shaped oxygen concentration distribution(coal spontaneous combustion)and the“>”-shaped gas concentration distribution(gas explosion).The optimal nitrogen flow rate is 1000 m3/h with an injection port situated 25 m away from the working face for the highest nitrogen diffusion efficacy and lowest risk of gas explosion,coal spontaneous combustion,and GCC.It has significant engineering applications for ensuring the safe mining of SIEC threatened by the GCC. 展开更多
关键词 Steeply inclined extra-thick coal seams Gas explosion Coal spontaneous combustion Coupling disaster Numerical simulation
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Research on the mechanism of rockburst induced by mined coal-rock linkage of sharply inclined coal seams
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作者 Xingping Lai Huicong Xu +4 位作者 Pengfei Shan Qinxin Hu Weixi Ding Shangtong Yang Zhongming Yan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第5期929-942,共14页
In recent years,the mining depth of steeply inclined coal seams in the Urumqi mining area has gradually increased.Local deformation of mining coal-rock results in frequent rockbursts.This has become a critical issue t... In recent years,the mining depth of steeply inclined coal seams in the Urumqi mining area has gradually increased.Local deformation of mining coal-rock results in frequent rockbursts.This has become a critical issue that affects the safe mining of deep,steeply inclined coal seams.In this work,we adopt a perspective centered on localized deformation in coal-rock mining and systematically combine theoretical analyses and extensive data mining of voluminous microseismic data.We describe a mechanical model for the urgently inclined mining of both the sandwiched rock pillar and the roof,explaining the mechanical response behavior of key disaster-prone zones within the deep working face,affected by the dynamics of deep mining.By exploring the spatial correlation inherent in extensive microseismic data,we delineate the“time-space”response relationship that governs the dynamic failure of coal-rock during the progression of the sharply inclined working face.The results disclose that(1)the distinctive coal-rock occurrence structure characterized by a“sandwiched rock pillar-B6 roof”constitutes the origin of rockburst in the southern mining area of the Wudong Coal Mine,with both elements presenting different degrees of deformation localization with increasing mining depth.(2)As mining depth increases,the bending deformation and energy accumulation within the rock pillar and roof show nonlinear acceleration.The localized deformation of deep,steeply inclined coal-rock engenders the spatial superposition of squeezing and prying effects in both the strike and dip directions,increasing the energy distribution disparity and stress asymmetry of the“sandwiched rock pillar-B3+6 coal seam-B6 roof”configuration.This makes worse the propensity for frequent dynamic disasters in the working face.(3)The developed high-energy distortion zone“inner-outer”control technology effectively reduces high stress concentration and energy distortion in the surrounding rock.After implementation,the average apparent resistivity in the rock pillar and B6 roof substantially increased by 430%and 300%,respectively,thus guaranteeing the safe and efficient development of steeply inclined coal seams. 展开更多
关键词 steeply inclined coal seam localized deformation mechanism of induced rockburst prevention and control of rockburst
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Fracture propagation and evolution law of indirect fracturing in the roof of broken soft coal seams
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作者 Haifeng Zhao Pengyue Li +1 位作者 Xuejiao Li Wenjie Yao 《International Journal of Coal Science & Technology》 EI CAS CSCD 2024年第1期78-102,共25页
Indirect fracturing in the roof of broken soft coal seams has been demonstrated to be a feasible technology.In this work,the No.5 coal seam in the Hancheng block was taken as the research object.Based on the findings ... Indirect fracturing in the roof of broken soft coal seams has been demonstrated to be a feasible technology.In this work,the No.5 coal seam in the Hancheng block was taken as the research object.Based on the findings of true triaxial hydraulic fracturing experiments and field pilot under this technology and the cohesive element method,a 3D numerical model of indirect fracturing in the roof of broken soft coal seams was established,the fracture morphology propagation and evolution law under different conditions was investigated,and analysis of main controlling factors of fracture parameters was conducted with the combination weight method,which was based on grey incidence,analytic hierarchy process and entropy weight method.The results show that“士”-shaped fractures,T-shaped fractures,cross fractures,H-shaped fractures,and“干”-shaped fractures dominated by horizontal fractures were formed.Different parameter combinations can form different fracture morphologies.When the coal seam permeability is lower and the minimum horizontal principal stress difference between layers and fracturing fluid injection rate are both larger,it tends to form“士”-shaped fractures.When the coal seam permeability and minimum horizontal principal stress between layers and perforation position are moderate,cross fractures are easily generated.Different fracture parameters have different main controlling factors.Engineering factors of perforation location,fracturing fluid injection rate and viscosity are the dominant factors of hydraulic fracture shape parameters.This study can provide a reference for the design of indirect fracturing in the roof of broken soft coal seams. 展开更多
关键词 Indirect fracturing Roof of coal seam Fracture propagation and evolution Coalbed methane Cohesive element method Combination weight method
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基于SEAMS评估的针对性护理干预在老年高血压患者的血压控制及用药依从性的影响
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作者 吴秀琴 钱彐晴 龚林 《黑龙江医药科学》 2024年第2期84-85,89,共3页
目的:探讨基于用药自我效能量表(SEAMS)评估的针对性护理对老年高血压的应用效果。方法:纳入2021年1月至2023年8月于上饶市人民医院门诊收治的65例老年高血压患者,根据抛掷法分为SEAMS组(基于SEAMS评估的针对性护理)33例、常规组(一般护... 目的:探讨基于用药自我效能量表(SEAMS)评估的针对性护理对老年高血压的应用效果。方法:纳入2021年1月至2023年8月于上饶市人民医院门诊收治的65例老年高血压患者,根据抛掷法分为SEAMS组(基于SEAMS评估的针对性护理)33例、常规组(一般护理)32例,干预3个月。比较两组血压控制、用药依从性、自我管理能力、健康状况。结果:SEAMS组干预后血压值较常规组低(P<0.05),SEAMS组血压控制率高于常规组(P<0.05),SEAMS组高血压患者服药依从性自我效能量表(MASES-R)评分、SEAMS评分、高血压病人自我管理量表评分、自测健康评定量表评分较常规组高(P<0.05)。结论:对老年高血压患者行基于SEAMS评估的针对性护理干预可控制血压水平,提升用药依从性、自我管理能力,改善健康状况。 展开更多
关键词 seams 针对性护理 老年高血压
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Analysis of the Risk of Water Breakout in the Bottom Plate of High-Intensity Mining of Extra-Thick Coal Seams
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作者 Shuo Wang Hongdong Kang Xinchen Wang 《Journal of Geoscience and Environment Protection》 2024年第5期81-91,共11页
In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site moni... In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site monitoring means combining borehole peeping and microseismic monitoring, combined with the theoretical analysis to analyze the danger of water breakout in the bottom plate. The results show that: 1) the theoretically calculated maximum damage depth of the bottom plate is 27.5 m, and its layer is located above the Austrian ash aquifer, which has the danger of water breakout;2) the drill hole peeping at the bottom plate of the working face shows that the depth of the bottom plate fissure development reaches 26 m, and the integrity of the water barrier layer has been damaged, so there is the risk of water breakout;3) for the microseismic monitoring of the anomalous area, the bottom plate of the return air downstream channel occurs in the field with a one-week lag, which shows that microseismic monitoring events may reflect the water breakout of the underground. This shows that the microseismic monitoring events can reflect the changes of the underground flow field, which can provide a reference basis for the early warning of water breakout. The research results can provide reference for the prediction of sudden water hazard. 展开更多
关键词 Extra-Thick Coal seam High-Intensity Mining Microseismic Monitoring Water-Surge Hazard Borehole Peeping
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Geotechnical considerations for concurrent pillar recovery in close-distance multiple seams 被引量:1
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作者 Peter Zhang Berk Tulu +1 位作者 Morgan Sears Jack Trackemas 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2018年第1期21-27,共7页
Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground fall fatalities in underground coal mines in the United States.The risk of ground falls during pillar recov... Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground fall fatalities in underground coal mines in the United States.The risk of ground falls during pillar recovery increases in multiple-seam mining conditions.The hazards associated with pillar recovery in multiple-seam mining include roof cutters, roof falls, rib rolls, coal outbursts, and floor heave.When pillar recovery is planned in multiple seams, it is critical to properly design the mining sequence and panel layout to minimize potential seam interaction.This paper addresses geotechnical considerations for concurrent pillar recovery in two coal seams with 21 m of interburden under about 305 m of depth of cover.The study finds that, for interburden thickness of 21 m, the multiple-seam mining influence zone in the lower seam is directly under the barrier pillar within about 30 m from the gob edge of the upper seam.The peak stress in the interburden transfers down at an angle of approximately 20°away from the gob, and the entries and crosscuts in the influence zone are subjected to elevated stress during development and retreat.The study also suggests that, for full pillar recovery in close-distance multiple-seam scenarios,it is optimal to superimpose the gobs in both seams, but it is not necessary to superimpose the pillars.If the entries and/or crosscuts in the lower seam are developed outside the gob line of the upper seam,additional roof and rib support needs to be considered to account for the elevated stress in the multiple-seam influence zone. 展开更多
关键词 PILLAR recovery Room-and-pillar RETREAT MINING MULTIPLE seam MINING sequence PILLAR design
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GMAS、MMAS-8和SEAMS评估慢性病病人用药依从性效能的比较 被引量:21
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作者 兰琨熠 张清 沈悦好 《护理研究》 北大核心 2023年第13期2322-2328,共7页
目的:比较普适性药物依从性量表(GMAS)、Morisky服药依从性测量量表(MMAS-8)、合理用药自我效能量表(SEAMS)在慢性病病人中的应用效果,为临床选择有价值的慢性病用药依从性评估工具提供参考。方法:于2021年10月—2022年2月选取在天津市... 目的:比较普适性药物依从性量表(GMAS)、Morisky服药依从性测量量表(MMAS-8)、合理用药自我效能量表(SEAMS)在慢性病病人中的应用效果,为临床选择有价值的慢性病用药依从性评估工具提供参考。方法:于2021年10月—2022年2月选取在天津市3所医疗机构就诊的270例成年慢性病病人为研究对象,采用一般资料调查表、GMAS、MMAS-8、SEAMS进行用药依从性评估,并以MAQ作为效度评价标准,采用受试者工作特征(ROC)曲线、Bayes判别分析、Kappa一致性检验和阳性似然比对3种慢性病用药依从性评估工具进行比较。结果:以MAQ为评价标准,270例病人中用药依从性差者122例(45.2%)。GMAS、MMAS-8、SEAMS评分的ROC曲线下面积(AUC)分别为0.981,0.984,0.917,灵敏度分别为0.987,0.993,0.676,特异度分别为0.926,0.943,0.951,约登指数分别为0.913,0.936,0.627(P<0.001)。GMAS、MMAS-8和SEAMS对评估慢性病病人用药依从性的交叉检验准确率分别为89.6%、97.0%和80.7%,与MAQ评估结果的一致性检验Kappa值分别为0.917,0.940,0.608(P<0.001),阳性似然比分别为13.367,17.303,13.734。结论:3种量表在评估慢性病病人是否存在用药依从性不佳风险时均有较高价值,其中MMAS-8评估慢性病病人用药依从性的效能最高,GMAS量表次之,最后是SEAMS,提示研究人员可根据研究对象个性化特点和研究目的针对性地选择评估工具,有助于准确识别用药依从性不佳的慢性病病人并早期开展干预。 展开更多
关键词 慢性病 用药依从性 普适性药物依从性量表(GMAS) Morisky服药依从性测量量表(MMAS-8) 合理用药自我效能量表(seams)
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Mechanical mechanism of overlying strata breaking and development of fractured zone during close-distance coal seam group mining 被引量:25
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作者 Jianguo Ning Jun Wang +1 位作者 Yunliang Tan Qiang Xu 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2020年第2期207-215,共9页
This study mainly investigates the mechanical mechanism of overlying strata breaking and the development of fractured zones during close-distance coal seam group mining in the Gaojialiang coal mine.First,a mechanical ... This study mainly investigates the mechanical mechanism of overlying strata breaking and the development of fractured zones during close-distance coal seam group mining in the Gaojialiang coal mine.First,a mechanical model for the second"activation"of broken overlying strata is established,and the related mechanical"activation"conditions are obtained.A recursive formula for calculating the separation distance of overlying strata is deduced.Second,a height determining method for predicting the height of fractured zones during close-distance coal seam group mining is proposed based on two values,namely,the separation distance and ultimate subsidence value of overlying strata.This method is applied to calculate the fractured zone heights in nos.20107 and 20307 mining faces.The calculated results are almost equal to the field observation results.Third,a modified formula for calculating the height of a waterflowing fractured zone is proposed.A comparison of the calculated and observed results shows that the errors are small.The height determining method and modified formula not only build a theoretical foundation for water conservation mining at the Gaojialiang coal mine,but also provide a reference for estimating the height of water-flowing fractured zones in other coal mines with similar conditions. 展开更多
关键词 Coal seam group Activation mechanism Separation Water-flowing fractured ZONE Modified FORMULA
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Correction to:Application of long-reach directional drilling boreholes for gas drainage of adjacent seams in coal mines with severe geological conditions
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作者 Grzegorz Lesniak Daniel J.Brunner +7 位作者 Tomasz Topor Matgorzata Stota-Valim Renata Cicha-Szot Bartomiej Jura Jacek Skiba Arnold Przystolik Ben Lyddall Grzegorz Plonka 《International Journal of Coal Science & Technology》 EI CAS CSCD 2023年第3期225-225,共1页
Correction:International Journal of Coal Science&Technology(2022)9:88 https:/doi.org/10.1007/s40789-022-00553-6 In this article,the author would like to change the Ethics Declaration as below:EthicsDeclarations Sc... Correction:International Journal of Coal Science&Technology(2022)9:88 https:/doi.org/10.1007/s40789-022-00553-6 In this article,the author would like to change the Ethics Declaration as below:EthicsDeclarations Scientific work published within the framework of an international project DD-MET co-financed by the Research Fund for Coal and Steel(RFCS),(Grant Agreement:847338)and by the Polish Ministry of Science and Higher Education(Contract no.5073/FBWiS/19/2020/2 and 5038/FBWiS/2019/2). 展开更多
关键词 directional FINANCE seam
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Geopolymer-based modification of blasting sealing materials and optimization of blasting block size in coal seams of open pit mines
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作者 Xiaohua Ding Zhongchen Ao +5 位作者 Wei Zhou Hao Qin Zhongao Yang Wen An Xiaoshuang Li Honglin Liu 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第12期1551-1562,共12页
This research proposes the utilization of a geopolymer-based blasting sealing material to improve the profitability of coal sales and reduce the rate of coal fragmentation during blasting in open pit mines.The study f... This research proposes the utilization of a geopolymer-based blasting sealing material to improve the profitability of coal sales and reduce the rate of coal fragmentation during blasting in open pit mines.The study first focused on optimizing the strength of the sealant material and reducing curing time.This was achieved by regulating the slag doping and sodium silicate solution modulus.The findings demonstrated that increasing slag content and improving the material resulted in an early rise in strength while increasing the modulus of the sodium silicate solution extended the curing time.The slag doping level was fixed at 80 g,and the sodium silicate solution modulus was set at 1.5.To achieve a strength of 3.12 MPa,the water/gel ratio was set at 0.5.The initial setting time was determined to be 33 min,meeting the required field test duration.Secondly,the strength requirements for field implementation were assessed by simulating the action time and force destruction process of the sealing material during blasting using ANSYS/LS-DYNA software.The results indicated that the modified material meets these requirements.Finally,the Shengli Open Pit Coal Mine served as the site for the field test.It was observed that the hole-sealing material’s hydration reaction created a laminated and flocculated gel inside it.This enhanced the density of the modified material.Additionally,the pregelatinized starch,functioning as an organic binder,filled the gaps between the gels,enhancing the cohesion and bonding coefficient of the material.Upon analyzing the post-blasting shooting effect diagram using the Split-Desktop software,it was determined that the utilization of the modified blast hole plugging material resulted in a decrease in the rate of coal fragmentation from 33.2%to 21.1%.This reduction exhibited a minimal error of 1.63%when compared to the field measurement,thereby providing further confirmation of the exceptional plugging capabilities of the modified material.This study significantly contributes to establishing a solid theoretical basis for enhancing the blasting efficiency of open pit mines and,in turn,enhancing their economic advantages. 展开更多
关键词 Open pit coal mine Coal seam blasting Sealing materials Block size optimization Numerical simulation
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融入混合注意力的低缩放因子SeamCarving篡改检测算法
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作者 赵洁 常皓婵 武斌 《智能科学与技术学报》 CSCD 2024年第2期244-252,共9页
针对现有的Seam Carving篡改检测算法对于低缩放因子情况存在检测精度不高、鲁棒性不强的问题,提出一种融入混合注意力机制的Seam Carving篡改检测算法。首先,利用BayarConv2D约束卷积对图像进行预处理,充分学习图像的噪声特征,并通过... 针对现有的Seam Carving篡改检测算法对于低缩放因子情况存在检测精度不高、鲁棒性不强的问题,提出一种融入混合注意力机制的Seam Carving篡改检测算法。首先,利用BayarConv2D约束卷积对图像进行预处理,充分学习图像的噪声特征,并通过矩阵乘法与RGB图像进行特征融合;然后,采用ResNet作为骨干网络进行特征学习,引入残差传播和残差反馈机制,凸显Seam Carving的操作痕迹;最后,利用混合注意力机制同时提取相邻位置和通道之间的特征,更好地捕捉全局特征,进而将其输入全连接层进行分类。实验结果表明,在BOSSbase1.01数据集上,当缩放因子为1%和9%时,检测精度分别达到了89.48%和97.94%,优于现有主流方法,同时具有较低的计算复杂度和较好的鲁棒性,能够抵抗JPEG压缩攻击。 展开更多
关键词 混合注意力机制 图像取证 seam Carving检测 低缩放因子
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基于动态规划的Seam Carving裁剪算法
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作者 杨科林 杨斌 +3 位作者 秦崇良 雷荣军 张永超 屈睿涛 《软件工程与应用》 2024年第3期439-445,共7页
随着科技的发展,图像应用和分享越来越普遍。图像尺寸调整在不同设备和屏幕上的显示非常重要。传统的方法只是简单地复制或计算像素值,而不考虑图像内容的重要性。然而,基于动态规划的Seam Carving裁剪算法提出了一种更优化的方法。该... 随着科技的发展,图像应用和分享越来越普遍。图像尺寸调整在不同设备和屏幕上的显示非常重要。传统的方法只是简单地复制或计算像素值,而不考虑图像内容的重要性。然而,基于动态规划的Seam Carving裁剪算法提出了一种更优化的方法。该算法采用多尺度处理,对不同尺度的图像进行Seam Carving操作,并将处理结果整合起来,以实现更全面、更精细的图像调整。 展开更多
关键词 动态规划 多尺度处理 梯度能量函数 seam Carving裁剪算法
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Astronomical influence of the development of Paleogene thin coal seam groups in offshore Lacustrine basins:A case study of the ZhuⅠDepression's Enping Formation located in the northern South China Sea
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作者 Yan Liu Shengbing Huang +4 位作者 Dongdong Wang Nan Li Yuting Yin Ying Chen Zengxue Li 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第4期136-150,共15页
The development of the Paleogene coal seams in China's offshore basin areas generally had the characteristics of coal measures with large thicknesses,large numbers of coal seams,thin single coal seams,poor stabili... The development of the Paleogene coal seams in China's offshore basin areas generally had the characteristics of coal measures with large thicknesses,large numbers of coal seams,thin single coal seams,poor stability,scattered vertical distribution,and a wide distribution range.This study selected the Enping Formation of the ZhuⅠDepression in the northern section of the South China Sea as an example to determine the macro-control factors of the development of the Paleogene coal seam groups.An analysis was carried out on the influencing effects and patterns of the astronomical cycles related to the development of the thin coal seam groups in the region.A floating astronomical time scale of the Enping Formation was established,and the sedimentary time limit of the Enping Formation was determined to be approximately 6.15 Ma±.In addition,the cyclostratigraphy analysis results of the natural gamma-ray data of Well XJ in the Enping Formation of the Xijiang Sag revealed that the development of the thin coal seams had probably been affected by short eccentricity and precession factors.The formation process of coal seams was determined to have been affected by high seasonal contrast,precipitation,and insolation.During the periods with high values of short eccentricity,the seasonal contrasts tended to be high.During those periods,fluctuations in the precession controls resulted in periodic volume changes in precipitation and insolation of the region,resulting in the development of thin coal seams.It was also found that the periods with low precession were the most conducive to coal seam development.On that basis,combined with such factors as sedimentary environmental conditions conducive to the development of thin coal seam groups,this study established a theoretical model of the comprehensive influences of short eccentricity and precession on the development and distribution of Paleogene thin coal seam groups in offshore lacustrine basins.The patterns of the Paleogene astronomical periods and paleoclimate evolution,along with the control factors which impacted the development of thin coal seam groups in offshore lacustrine basins,were revealed. 展开更多
关键词 PALEOGENE Pearl(Zhujiang)River Mouth Basin coal seam development astronomical cycles
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Prediction of rock fragmentation in a fiery seam of an open-pit coal mine in India
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作者 Mukul Sharma Bhanwar Singh Choudhary +2 位作者 Autar K.Raina Manoj Khandelwal Saurav Rukhiyar 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期2879-2893,共15页
Spontaneous combustion of coal increases the temperature in adjoining overburden strata of coal seams and poses a challenge when loading blastholes.This condition,known as hot-hole blasting,is dangerous due to the inc... Spontaneous combustion of coal increases the temperature in adjoining overburden strata of coal seams and poses a challenge when loading blastholes.This condition,known as hot-hole blasting,is dangerous due to the increased possibility of premature explosions in loaded blastholes.Thus,it is crucial to load the blastholes with an appropriate amount of explosives within a short period to avoid premature detonation caused by high temperatures of blastholes.Additionally,it will help achieve the desired fragment size.This study tried to ascertain the most influencial variables of mean fragment size and their optimum values adopted for blasting in a fiery seam.Data on blast design,rock mass,and fragmentation of 100 blasts in fiery seams of a coal mine were collected and used to develop mean fragmentation prediction models using soft computational techniques.The coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute error(MAE),mean square error(MSE),variance account for(VAF)and coefficient of efficiency in percentage(CE)were calculated to validate the results.It indicates that the random forest algorithm(RFA)outperforms the artificial neural network(ANN),response surface method(RSM),and decision tree(DT).The values of R^(2),RMSE,MAE,MSE,VAF,and CE for RFA are 0.94,0.034,0.027,0.001,93.58,and 93.01,respectively.Multiple parametric sensitivity analyses(MPSAs)of the input variables showed that the Schmidt hammer rebound number and spacing-to-burden ratio are the most influencial variables for the blast fragment size.The analysis was finally used to define the best blast design variables to achieve optimum fragment size from blasting.The optimum factor values for RFA of S/B,ld/B and ls/ld are 1.03,1.85 and 0.7,respectively. 展开更多
关键词 Fiery seam Rock fragmentation Response Surface Method(RSM) Artificial Neural Network(ANN) Random Forest Algorithm(RFA) Multiple Parametric Sensitivity Analysis (MPSA)
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Investigation on the test method of rupture forces of thermal bonding seams in nonwovens shopping bags
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作者 王来力 吴雄英 丁雪梅 《产业用纺织品》 北大核心 2009年第11期41-44,共4页
超声波热黏合的非织造布接缝不同于普通机织物和针织物等的车缝接缝。运用正交试验设计方法,对纺粘法PP非织造布购物袋热黏合接缝断裂强力测试中的试样宽度、拉伸速率和隔距三个因素进行优化。试验结果表明,试样宽度对纺粘法PP非织造... 超声波热黏合的非织造布接缝不同于普通机织物和针织物等的车缝接缝。运用正交试验设计方法,对纺粘法PP非织造布购物袋热黏合接缝断裂强力测试中的试样宽度、拉伸速率和隔距三个因素进行优化。试验结果表明,试样宽度对纺粘法PP非织造布热黏合接缝断裂强力的测试结果影响最大,并且接缝的断裂强力随着试样宽度的增加而增加。选用试样宽度为200mm、拉伸速率为50mm/min、隔距为100mm的组合所得出的测试结果能比较真实地反映实际的接缝断裂强力。 展开更多
关键词 非织造布 热黏合接缝 测试方法 正交试验
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The impact of cleats on hydraulic fracture initiation and propagation in coal seams 被引量:17
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作者 Fan Tiegang Zhang Guangqing Cui Jinbang 《Petroleum Science》 SCIE CAS CSCD 2014年第4期532-539,共8页
Cleats are systematic, natural fractures in coal seams. They account for most of the permeability and much of the porosity of coalbed methane reservoirs and can have a significant effect on the success of hydraulic fr... Cleats are systematic, natural fractures in coal seams. They account for most of the permeability and much of the porosity of coalbed methane reservoirs and can have a significant effect on the success of hydraulic fracturing stimulation. Laboratory hydraulic fracturing experiments were conducted on coal blocks under true tri-axial stress to simulate fracturing stimulation of coal seams. Fractures were initiated by injecting a water gel with luminous yellow fluorescent dye into an open hole section of a wellbore. The impact of cleats on initiation and propagation of hydraulic fractures in coal seams is discussed. Three types of hydraulic fracture initiation and propagation pattern were observed in this study: 1) The hydraulic fracture initiated and then grew along the cleat. 2) The hydraulic fracture initiated along a butt cleat or a fracture (natural or induced by drilling) oriented roughly in the minimum horizontal stress direction, then turned to propagate along the first face cleat that it encountered or gradually turned towards the maximum horizontal stress direction. 3) The hydraulic fracture initiated perpendicular to the minimum stress and, when it encountered a face cleat, tended to propagate along the cleats if the extension direction does not deviate greatly (〈20° as determined in this paper) from the maximum horizontal stress direction. When a coal seam is hydraulically fractured, the resulting fracture network is controlled by the combined effect of several factors: cleats determine the initiation and extension path of the fracture, the in-situ stress state dominates the main direction of the fracture zone and bedding planes impede fracture height growth. 展开更多
关键词 Cleats coalbed methane hydraulic fracturing coal seam simulation experiment
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Control mechanism of a cable truss system for stability of roadways within thick coal seams 被引量:6
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作者 YAN Hong HE Fu-lian +2 位作者 LI Lin-yue FENG Rui-min XING Peng-fei 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第5期1098-1110,共13页
Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extreme... Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extremely thick coal seams because the control mechanism of the system for the deformation of the roof and the separation between coal rock segments is not completely understood. By using the relationship between the support system and the roof strata, a mechanical model was established to calculate the deformation of the roof in a thick coal seam with bedding separation under different support conditions: with an anchor truss support and without support. On this basis, the research was used to deduce a method for computing the minimum pre-tightening forces in the anchor truss, the maximum amounts of subsidence and separation with, and without, anchor truss support under the roof, and the maximum subsidence and the decreasing amounts of the separation before and after adopting the anchor truss. Additionally, mechanical relationships between the minimum pre-tightening force and the anchoring force in the anchor were analyzed. By taking a typical roadway with thick coal roof as an example, the theoretical results mentioned above were applied in the analysis and testing of a roof supporting project in a roadway field to verify the accuracy of the theory: favorable experimental results were achieved. In addition, the relationships among other parameters were analyzed, including the minimum pre-tightening forces applied by the anchor truss, the angle of inclination of the anchor cable, and the array pitch. Meanwhile, the changing characteristics of the amounts of roof separation and subsidence with key parameters of the support system(such as array pitch, pre-tightening force, and inclination angle) were also analyzed. The research results revealed the acting mechanism of the anchor truss in control of roadway stability with a thick coal seam, providing a theoretical basis of its application in coal mining. 展开更多
关键词 cable TRUSS system THICK COAL seam ROOF separation pre-tightening force
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