With the long-term support by the National Natural Science Foundation of China,Ministry of Agriculture,and Science and Technology Department of Zhejiang Province,the research team led by Prof.Zhang Mingfang(张明方)at ...With the long-term support by the National Natural Science Foundation of China,Ministry of Agriculture,and Science and Technology Department of Zhejiang Province,the research team led by Prof.Zhang Mingfang(张明方)at Zhejiang University,assembled an allopolyploid B.juncea genome and uncovered differential homoeolog gene expression influencing selection,which was published in Nature展开更多
Dr Emily Thompson decided it was time to set sail on her first major maritime research expedition.She had always been fascinated by the mysteries of the ocean and wanted to uncover the secrets hidden beneath the waves...Dr Emily Thompson decided it was time to set sail on her first major maritime research expedition.She had always been fascinated by the mysteries of the ocean and wanted to uncover the secrets hidden beneath the waves.Her team boarded the research vessel early in the morning,excited at the adventure that awaited them.展开更多
Deep mining is imperative,and the consequent coal and gas outburst disasters triggered during coal uncovering are becoming increasingly severe.Therefore,this study investigated the mechanical mechanisms of outburst in...Deep mining is imperative,and the consequent coal and gas outburst disasters triggered during coal uncovering are becoming increasingly severe.Therefore,this study investigated the mechanical mechanisms of outburst instability from three dimensions:experiment,numerical simulation,and field application.Based on physical simulation tests with different outburst pore diameter,it was found that the gas pressure relief rate,gas emission volume,and outburst dynamic phenomena increase with outburst pore diameter.The migration patterns of the gas-solid two-phase flow evolved over time approximately into suspension flow,plug flow,dune flow,and stratified flow.The dominant influence of gas-driven tensile failure was amplified by uncovering coal area.The employment of the“fluid-solid-damage”coupling model revealed that coal damage,gas emission volume,deflection angle of outburst hole,roof displacement,maximum horizontal tensile stress,the horizontal tensile stress zone,the peak seepage force,and the damage zone all increased with uncovering coal areas.At the gas pressure of 0.74 MPa,when the uncovering coal areas were 3.189,4.754 and 6.225 m,the total gas emission volumes were 4.72×10^(-4),16.83×10^(-4),and 17.67 m^(2)/s,deflection angles of outburst hole were 150.79°,152.89°and 158.66°,the maximum roof displacements were 0.044,0.046,and 0.325 m,and the peak seepage force were 0.85,1.27,and 1.46 MPa/m,respectively.The regions of coal failure calculated by tensile failure criterion largely coincided with those calculated by the mixed failure criterion,far greater than those calculated by the shear failure criterion.As the increase of uncovering coal area,tensile weights of 80.72%,89.78%,and 93.01%,respectively.Comparisons with field outburst cases showed that both gas emission volume and outburst hole deflection angle reflected the tensile failure of coal.The mechanical instability process of outbursts under the influence of uncovering coal area and gas pressure was analyzed,developing the progressive cyclical method of coal uncovering,which provided a novel approach for the achievement of safe coal mining.展开更多
This paper proposes a new methodology to optimize trajectory of the path for multi-robots using improved gravitational search algorithm(IGSA) in clutter environment. Classical GSA has been improved in this paper based...This paper proposes a new methodology to optimize trajectory of the path for multi-robots using improved gravitational search algorithm(IGSA) in clutter environment. Classical GSA has been improved in this paper based on the communication and memory characteristics of particle swarm optimization(PSO). IGSA technique is incorporated into the multi-robot system in a dynamic framework, which will provide robust performance, self-deterministic cooperation, and coping with an inhospitable environment. The robots in the team make independent decisions, coordinate, and cooperate with each other to accomplish a common goal using the developed IGSA. A path planning scheme has been developed using IGSA to optimally obtain the succeeding positions of the robots from the existing position in the proposed environment. Finally, the analytical and experimental results of the multi-robot path planning were compared with those obtained by IGSA, GSA and differential evolution(DE) in a similar environment. The simulation and the Khepera environment result show outperforms of IGSA as compared to GSA and DE with respect to the average total trajectory path deviation, average uncovered trajectory target distance and energy optimization in terms of rotation.展开更多
BACKGROUND Given most patients with distal malignant biliary obstruction present in the nonresectable stage,palliative endoscopic biliary drainage with fully covered metal stent(FCMS)or uncovered metal stent(UCMS)is t...BACKGROUND Given most patients with distal malignant biliary obstruction present in the nonresectable stage,palliative endoscopic biliary drainage with fully covered metal stent(FCMS)or uncovered metal stent(UCMS)is the only available measure to improve patients’quality of life.Half covered metal stent(HCMS)has been recently introduced commercially.The adverse effects and stent function between FCMS and UCMS have been extensively discussed.AIM To study the duration of stent patency of HCMS and compare it with FCMS and UCMS to optimize biliary drainage in inoperable patients with distal malignant obstruction.Secondary aims in our study included evaluation of patients’survival and the rates of adverse events for each type of stent.METHODS We studied 210 patients and randomized them into three equal groups;HCMS,FCMS and UCMS were inserted endoscopically.RESULTS Stent occlusion occurred in(18.6%,17.1%and 15.7%in HCMS,FCMS and UCMS groups,respectively,P=0.9).Stent migration occurred only in patients with FCMS(8.6%of patients).Cholangitis and cholecystitis occurred in 11.4%and 5.7%of patients,respectively,in FCMS.Tumor growth occurred only in 10 cases among patients with UCMS after a median of 140 d,sludge occurred in nine,seven and one patients in HCMS,FCMS and UCMS,respectively(P=0.04).CONCLUSION Given the prolonged stent functioning time,the use of HCMS is preferred over the use of UCMS and FCMS for optimizing biliary drainage in patients with distal malignant biliary obstruction.展开更多
Background Different stems implantation in ST-segmem elevation myocardial infarction （STEMI） patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to e...Background Different stems implantation in ST-segmem elevation myocardial infarction （STEMI） patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to evaluate the vessel healings after implantation of drug elming stems （DES） with biodegradable or durable polymer or of bare-metal stems （BMS） in patients with ache STEMI. Methods This study included 50 patients, who underwem follow up angiogram and optical coherence tomography （OCT） assessment about one year after percutaneous coronary intervemion （PCI） for STEMI. According to the initial stems types, these patients were classified to durable （n = 19） or biodegradable polymer sirolimus-eluting stems （n = 15）, or BMS （n = 16） groups. The conditions of stem struts coverage and malapposi- tion were analyzed with OCT technique. Results A total of 9003 struts were analyzed： 3299, 3202 and 2502 from durable or biodegradable polymer DES, or BMS, respectively. Strut coverage rate （89.0%, 94.9% and 99.3%, respectively）, malapposition presence （1.7%, 0.03% and 0 of struts, respectively） and average intimal thickness over struts （76 ± 12 μm, 161 ± 30 μm and 292 ± 29 μm, respectively） were significantly differem among different stent groups （all P 〈 0.001）. Conclusions Vessel healing status in STEMI patients is superior after implantation of biodegradable polymer DES than durable polymer DES, while both are inferior to BMS.展开更多
BACKGROUND Endoscopic biliary drainage using a self-expandable metallic stent(SEMS)has been widely performed to treat distal malignant biliary obstruction(DMBO).However,the optimal position of the stent remains unclea...BACKGROUND Endoscopic biliary drainage using a self-expandable metallic stent(SEMS)has been widely performed to treat distal malignant biliary obstruction(DMBO).However,the optimal position of the stent remains unclear.AIM To determine the ideal position for SEMS placement.METHODS In total,135 DMBO patients underwent SEMS(uncovered or covered)placement over a ten-year period.A total of 127 patients with biliary obstruction between the junction of the cystic duct and Vater’s papilla were enrolled.An SEMS was placed through the upper common bile duct 2 cm from the biliary hilar duct in 83 patients(Hilar group)or near the top of the biliary obstruction in 44 patients(Lower group).Technical and functional success,adverse events,and risk factors for SEMS dysfunction were evaluated.RESULTS The stent patency period was significantly longer in the Hilar group than in the Lower group(P value<0.01).In multivariate analysis,the only statistically significant risk factor for SEMS dysfunction was being in the Lower group(hazard ratio:9.94,95%confidence interval:2.25–44.0,P<0.01).CONCLUSION A longer patency period was achieved by positioning the SEMS near the biliary hilar duct.展开更多
To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the ...To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the equations of elastic potential of coal and gas dilatation energy theory were set up to process a contrast calculation of the sizes of two kinds of energy. The results show that gas dilatation energy is the uppermost energy source causing outburst occurrence. Furthermore, the mathematical model of spherical flow field gas dilatation energy release was established and MATLAB software was applied to make a numerical calculation analysis on the law of gas dilatation energy release. The results indicate that the gas dilatation energy is closely related to gas parameters and its energy index does reflect the possibility of coal seam outburst.展开更多
文摘With the long-term support by the National Natural Science Foundation of China,Ministry of Agriculture,and Science and Technology Department of Zhejiang Province,the research team led by Prof.Zhang Mingfang(张明方)at Zhejiang University,assembled an allopolyploid B.juncea genome and uncovered differential homoeolog gene expression influencing selection,which was published in Nature
文摘Dr Emily Thompson decided it was time to set sail on her first major maritime research expedition.She had always been fascinated by the mysteries of the ocean and wanted to uncover the secrets hidden beneath the waves.Her team boarded the research vessel early in the morning,excited at the adventure that awaited them.
基金supported by the National Natural Science Foundation of China(Nos.52274242 and 51904293)the National Key R&D Program of China(No.2022YFC3004701)+2 种基金the Fundamental Research Funds for the Central Universities(No.2025QN1030)the Youth Science and Technology Talent Support Project of Jiangsu Province(No.JSTJ-2024-063)the Special Fund for Science and Technology of Jiangsu Province(No.BM2022013)。
文摘Deep mining is imperative,and the consequent coal and gas outburst disasters triggered during coal uncovering are becoming increasingly severe.Therefore,this study investigated the mechanical mechanisms of outburst instability from three dimensions:experiment,numerical simulation,and field application.Based on physical simulation tests with different outburst pore diameter,it was found that the gas pressure relief rate,gas emission volume,and outburst dynamic phenomena increase with outburst pore diameter.The migration patterns of the gas-solid two-phase flow evolved over time approximately into suspension flow,plug flow,dune flow,and stratified flow.The dominant influence of gas-driven tensile failure was amplified by uncovering coal area.The employment of the“fluid-solid-damage”coupling model revealed that coal damage,gas emission volume,deflection angle of outburst hole,roof displacement,maximum horizontal tensile stress,the horizontal tensile stress zone,the peak seepage force,and the damage zone all increased with uncovering coal areas.At the gas pressure of 0.74 MPa,when the uncovering coal areas were 3.189,4.754 and 6.225 m,the total gas emission volumes were 4.72×10^(-4),16.83×10^(-4),and 17.67 m^(2)/s,deflection angles of outburst hole were 150.79°,152.89°and 158.66°,the maximum roof displacements were 0.044,0.046,and 0.325 m,and the peak seepage force were 0.85,1.27,and 1.46 MPa/m,respectively.The regions of coal failure calculated by tensile failure criterion largely coincided with those calculated by the mixed failure criterion,far greater than those calculated by the shear failure criterion.As the increase of uncovering coal area,tensile weights of 80.72%,89.78%,and 93.01%,respectively.Comparisons with field outburst cases showed that both gas emission volume and outburst hole deflection angle reflected the tensile failure of coal.The mechanical instability process of outbursts under the influence of uncovering coal area and gas pressure was analyzed,developing the progressive cyclical method of coal uncovering,which provided a novel approach for the achievement of safe coal mining.
文摘This paper proposes a new methodology to optimize trajectory of the path for multi-robots using improved gravitational search algorithm(IGSA) in clutter environment. Classical GSA has been improved in this paper based on the communication and memory characteristics of particle swarm optimization(PSO). IGSA technique is incorporated into the multi-robot system in a dynamic framework, which will provide robust performance, self-deterministic cooperation, and coping with an inhospitable environment. The robots in the team make independent decisions, coordinate, and cooperate with each other to accomplish a common goal using the developed IGSA. A path planning scheme has been developed using IGSA to optimally obtain the succeeding positions of the robots from the existing position in the proposed environment. Finally, the analytical and experimental results of the multi-robot path planning were compared with those obtained by IGSA, GSA and differential evolution(DE) in a similar environment. The simulation and the Khepera environment result show outperforms of IGSA as compared to GSA and DE with respect to the average total trajectory path deviation, average uncovered trajectory target distance and energy optimization in terms of rotation.
文摘BACKGROUND Given most patients with distal malignant biliary obstruction present in the nonresectable stage,palliative endoscopic biliary drainage with fully covered metal stent(FCMS)or uncovered metal stent(UCMS)is the only available measure to improve patients’quality of life.Half covered metal stent(HCMS)has been recently introduced commercially.The adverse effects and stent function between FCMS and UCMS have been extensively discussed.AIM To study the duration of stent patency of HCMS and compare it with FCMS and UCMS to optimize biliary drainage in inoperable patients with distal malignant obstruction.Secondary aims in our study included evaluation of patients’survival and the rates of adverse events for each type of stent.METHODS We studied 210 patients and randomized them into three equal groups;HCMS,FCMS and UCMS were inserted endoscopically.RESULTS Stent occlusion occurred in(18.6%,17.1%and 15.7%in HCMS,FCMS and UCMS groups,respectively,P=0.9).Stent migration occurred only in patients with FCMS(8.6%of patients).Cholangitis and cholecystitis occurred in 11.4%and 5.7%of patients,respectively,in FCMS.Tumor growth occurred only in 10 cases among patients with UCMS after a median of 140 d,sludge occurred in nine,seven and one patients in HCMS,FCMS and UCMS,respectively(P=0.04).CONCLUSION Given the prolonged stent functioning time,the use of HCMS is preferred over the use of UCMS and FCMS for optimizing biliary drainage in patients with distal malignant biliary obstruction.
文摘Background Different stems implantation in ST-segmem elevation myocardial infarction （STEMI） patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to evaluate the vessel healings after implantation of drug elming stems （DES） with biodegradable or durable polymer or of bare-metal stems （BMS） in patients with ache STEMI. Methods This study included 50 patients, who underwem follow up angiogram and optical coherence tomography （OCT） assessment about one year after percutaneous coronary intervemion （PCI） for STEMI. According to the initial stems types, these patients were classified to durable （n = 19） or biodegradable polymer sirolimus-eluting stems （n = 15）, or BMS （n = 16） groups. The conditions of stem struts coverage and malapposi- tion were analyzed with OCT technique. Results A total of 9003 struts were analyzed： 3299, 3202 and 2502 from durable or biodegradable polymer DES, or BMS, respectively. Strut coverage rate （89.0%, 94.9% and 99.3%, respectively）, malapposition presence （1.7%, 0.03% and 0 of struts, respectively） and average intimal thickness over struts （76 ± 12 μm, 161 ± 30 μm and 292 ± 29 μm, respectively） were significantly differem among different stent groups （all P 〈 0.001）. Conclusions Vessel healing status in STEMI patients is superior after implantation of biodegradable polymer DES than durable polymer DES, while both are inferior to BMS.
文摘BACKGROUND Endoscopic biliary drainage using a self-expandable metallic stent(SEMS)has been widely performed to treat distal malignant biliary obstruction(DMBO).However,the optimal position of the stent remains unclear.AIM To determine the ideal position for SEMS placement.METHODS In total,135 DMBO patients underwent SEMS(uncovered or covered)placement over a ten-year period.A total of 127 patients with biliary obstruction between the junction of the cystic duct and Vater’s papilla were enrolled.An SEMS was placed through the upper common bile duct 2 cm from the biliary hilar duct in 83 patients(Hilar group)or near the top of the biliary obstruction in 44 patients(Lower group).Technical and functional success,adverse events,and risk factors for SEMS dysfunction were evaluated.RESULTS The stent patency period was significantly longer in the Hilar group than in the Lower group(P value<0.01).In multivariate analysis,the only statistically significant risk factor for SEMS dysfunction was being in the Lower group(hazard ratio:9.94,95%confidence interval:2.25–44.0,P<0.01).CONCLUSION A longer patency period was achieved by positioning the SEMS near the biliary hilar duct.
文摘To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the equations of elastic potential of coal and gas dilatation energy theory were set up to process a contrast calculation of the sizes of two kinds of energy. The results show that gas dilatation energy is the uppermost energy source causing outburst occurrence. Furthermore, the mathematical model of spherical flow field gas dilatation energy release was established and MATLAB software was applied to make a numerical calculation analysis on the law of gas dilatation energy release. The results indicate that the gas dilatation energy is closely related to gas parameters and its energy index does reflect the possibility of coal seam outburst.
