Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geolog...Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters.展开更多
Left main coronary compression syndrome(LMCS)may complicate pulmonary artery aneurysms(PAA),usually developed in the context of pulmonary arterial hypertension(PAH).We report the case of a 51-year-old female patient w...Left main coronary compression syndrome(LMCS)may complicate pulmonary artery aneurysms(PAA),usually developed in the context of pulmonary arterial hypertension(PAH).We report the case of a 51-year-old female patient with an atrial septal defect(unsuitable for device closure)complicated by a PAA generating a 90%left main stenosis.The significant PAH held us back from immediate surgery.After specific dual PAH-targeted therapy(sildenafil and bosentan),the atrial septal defect could be closed with a unidirectional valved patch;the PAAinduced LMCS was treated by reductive arterioplasty.The postoperative course was uneventful.Follow-up showed clinical improvement,but PAH treatment was still needed.After three months,coronary angiography showed only an insignificant residual left main stenosis,proving that reductive pulmonary arterioplasty was effective in treating LMCS.Any PAA requires further evaluation for LMCS,a dangerous but treatable complication.The“treat-repair-treat”strategy and shunt-closure with a unidirectional valved patch can both improve surgical prospects of LMCS with shunt-related PAH.展开更多
Left main (LM) stenting is considered by many to be one of the last frontiers of interventional cardiology. Beginning with the VA cooperative study published in 1976 demonstrating a mortality benefit for patients ... Left main (LM) stenting is considered by many to be one of the last frontiers of interventional cardiology. Beginning with the VA cooperative study published in 1976 demonstrating a mortality benefit for patients undergoing coronary artery bypass grafting (CABG), i the standard of care for treatment of left main coronary artery disease has been surgical.The most recent 2005 update of the ACC/AHA/SCAI Practice Guidelines on PCI 2 again notes that "CABG using IMA grafting is the 'gold standard' for treatment of unprotected left main disease and has proven benefit on long-term outcomes."……展开更多
Based on comprehensive analysis of core, well logging, seismic and production data, the multi-scale reservoir space, reservoir types, spatial shape and distribution of fractures and caves, and the configuration relati...Based on comprehensive analysis of core, well logging, seismic and production data, the multi-scale reservoir space, reservoir types, spatial shape and distribution of fractures and caves, and the configuration relationship with production wells in fracture-cavity carbonate reservoirs were studied systematically, the influence of them on the distribution of residual oil was analyzed, and the main controlling factors mode of residual oil distribution after water flooding was established. Enhanced oil recovery methods were studied considering the development practice of Tahe oilfield. Research shows that the main controlling factors of residual oil distribution after water flooding in fracture-cavity carbonate reservoirs can be classified into four categories: local high point, insufficient well control, flow channel shielding and weak hydrodynamic. It is a systematic project to improve oil recovery in fracture-cavity carbonate reservoirs. In the stage of natural depletion, production should be well regulated to prevent bottom water channeling. In the early stage of waterflooding, injection-production relationship should be constructed according to reservoir type, connectivity and spatial location to enhance control and producing degree of waterflooding and minimize remaining oil. In the middle and late stage, according to the main controlling factors and distribution characteristics of remaining oil after water flooding, remaining oil should be tapped precisely by making use of gravity differentiation and capillary force imbibition, enhancing well control, disturbing the flow field and so on. Meanwhile, backup technologies of reservoir stimulation, new injection media, intelligent optimization etc. should be developed, smooth shift from water injection to gas injection should be ensured to maximize oil recovery.展开更多
With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint o...With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.展开更多
"Days of the Butterfly"was one of Alice Munro's short stories written in 1950 s, when she was still a new hand. This paper will mainly focus on the development of the main characters in the story, includ..."Days of the Butterfly"was one of Alice Munro's short stories written in 1950 s, when she was still a new hand. This paper will mainly focus on the development of the main characters in the story, including Myra, the black girl who was the heroine, the teacher Miss Darling, and the Narrator"I". In portraying these characters, Munro adopted several writing techniques including conversation, detailed description, psychological description and so on. She vividly transferred those characters into paper.展开更多
Hemodynamically significant left main coronary artery stenosis(LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left cir-cumflex a...Hemodynamically significant left main coronary artery stenosis(LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left cir-cumflex artery has no previous patent grafts.Previous randomized studies have demonstrated a significant re-duction in mortality when revascularization by coronary artery bypass graft(CABG) surgery was undertaken compared with medical treatment.Therefore,current practice guidelines do not recommend percutaneous coronary intervention(PCI) for such a lesion because of the proven benefit of surgery and high rates of reste-nosis with the use of bare metal stents.However,with the advent of drug-eluting stents(DES),the long term outcomes of PCI with DES to treat unprotected LMCA stenoses have been acceptable.Therefore,apart from the current guidelines,PCI for treatment of unprotected LMCA stenosis is often undertaken in individuals who are at a very high risk of CABG or refuse to undergo a sternotomy.Future randomized studies comparing CABG vs PCI using DES for treatment of unprotected LMCA stenosis would be a great advance in clinical knowledge for the adoption of appropriate treatment.展开更多
The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and en...The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy saving.To effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are proposed.In the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined.The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis.Thereafter,the performance atlases,which can present all possible design solutions,are depicted.As a result,the feasible solution of the mechanism with good motion/force transmission performance is obtained.And the solution can be flexibly adjusted by designer according to the practical design requirements.The proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.展开更多
In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme...In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme. On the basis of revealing and analyzing the coal seam as the main aquifer in western coal mine of Xiao Jihan coal mine, the simulation software of PHASE-2D was applied to analyze the water inflow under different influencing factors. The results showed that water inflow increases logarithmically with the coal seam thickness, increases as a power function with the permeability coefficient of the coal seam, and increases linearly with the coal seam burial depth and the head pressure; The evaluation model for the factors of coal seam water inrush was gained by using nonlinear regression analysis with SPSS. The mine water inrush risk evaluation partition within the scope of the mining field was obtained,through the engineering application in Xiao Jihan coal mine. To ensure the safe and efficient production of the mine, we studied the coal mine water disaster prevention and control measures of a main aquifer coal seam in aspects of roadway driving and coal seam mining.展开更多
AIM To evaluate the efficacy of main portal vein stents combined with iodine-125(^(125)Ⅰ) to treat main portal vein tumor thrombus.METHODS From January 1, 2010 to January 1, 2015, 111 patients were diagnosed with liv...AIM To evaluate the efficacy of main portal vein stents combined with iodine-125(^(125)Ⅰ) to treat main portal vein tumor thrombus.METHODS From January 1, 2010 to January 1, 2015, 111 patients were diagnosed with liver cancer combined with main portal vein tumor thrombus. They were non-randomly assigned to undergo treatment with transarterial chemoembolization(TACE)/transarterial embolization(TAE) + portal vein stents combined with ^(125)Ⅰ implantation(Group A) and TACE/TAE + portal vein stents only(Group B). After the operation, scheduled follow-up was performed at 6, 12 and 24 mo. The recorded information included clinical manifestations, survival rate, and stent restenosis rate. Kaplan–Meier curves, log-rank test and Cox regression were used for data analyses. RESULTS From January 1, 2010 to January 1, 2015, 54 and 57 patients were allocated to Groups A and B, respectively. The survival rates at 6, 12 and 24 mo were 85.2%, 42.6% and 22.2% in Group A and 50.9%, 10.5% and 0% in Group B. The differences were significant [log rank P < 0.05, hazard ratio(HR): 0.37, 95%CI: 0.24-0.56]. The rates of stent restenosis were 18.5%, 55.6% and 83.3% in Group A and 43.9%, 82.5% and 96.5% in Group B. The differences were significant(log rank P < 0.05, HR: 0.42, 95%CI: 0.27-0.63). Cox regression identified that treatment was the only factor affecting survival rate in this study.CONCLUSION Main portal vein stents combined with ^(125)Ⅰ can significantly improve survival rate and reduce the rate of stent restenosis.展开更多
BACKGROUND Main portal vein tumor thrombus(MPVTT), which has a high incidence, is the major complication of terminal liver cancer. The occurrence of MPVTT is always a negative prognostic factor for patients with hepat...BACKGROUND Main portal vein tumor thrombus(MPVTT), which has a high incidence, is the major complication of terminal liver cancer. The occurrence of MPVTT is always a negative prognostic factor for patients with hepatocellular carcinoma(HCC).Therefore, attention should be paid to the treatment of MPVTT and its complications.AIM To evaluate the efficacy of transarterial chemoembolization/transarterial embolization(TACE/TAE)+^(125)I seeds implantation with transjugular intrahepatic portosystemic shunt(TIPS) in treating MPVTT and its complications.METHODS From January 2007 to March 2015, 85 consecutive patients with MPVTT were nonrandomly assigned to undergo treatment with TACE/TAE + TIPS and ^(125)I implantation(TIPS-^(125)I group) or TACE/TAE + TIPS only(TIPS only group) in Beijing Shijitan Hospital, and all clinical data were collected. During 24 mo follow-up, the incidence of overall survival, stent stenosis and symptom recurrence was analyzed to evaluate the efficacy of TIPS-^(125)I.RESULTS During 24 mo follow-up of all patients, we collected data at 6, 12 and 24 mo. The rates of survival were 80%, 45%, and 20%, respectively, in the TIPS-^(125)I group,whereas those in the TIPS only group were 64.4%, 24.4%, and 4.4%, respectively(P < 0.05). The rates of symptom recurrence were 7.5%, 22.5%, and 35%,respectively, in the TIPS-^(125)I group, whereas those in the TIPS only group were31.1%, 62.2%, and 82.2%(P < 0.05). The rates of stent restenosis were 12.5%,27.5%, and 42.5%, respectively, in the TIPS-^(125)I group, and 42.2%, 68.9%, and84.4%, respectively, in the TIPS only group(P < 0.05). TIPS-^(125)I was found to be significantly favorable in treating MPVTT and its complications in patients with HCC.CONCLUSION TACE/TAE+^(125)I combined with TIPS is effective in treating MPVTT and its complications, improving quality of life of patients and reducing mortality.展开更多
To consider the infl uence of aftershocks in engineering design, the correlations between main shocks and aftershocks should be examined, and an aftershock simulation method with main shock ground motions needs to be ...To consider the infl uence of aftershocks in engineering design, the correlations between main shocks and aftershocks should be examined, and an aftershock simulation method with main shock ground motions needs to be developed. In this study, the data on the sequences of main shock–aftershock ground motions and other related parameters were collected. Using these data, correlations between the magnitude, frequency, duration and energy of the main shock–aftershock ground motions were investigated. The results showed that the magnitude of the aftershock can be larger than that of the main shock. The shapes of the Fourier amplitude spectra of main shocks and aftershocks were similar;however, the predominant frequency and high-frequency components of the aftershock tended to be larger. Considering the magnitude diff erence between the main shock and the aftershock, the correlation of durations was explored. Additionally, a new concept, the duration ratio, was defi ned to describe the concentration of seismic energy release, and main shock energy was strongly positively correlated with the energy attenuated during the main shock–aftershock sequence. Finally, based on these results regarding correlation, an aftershock synthesis using recorded main shock ground motions was constructed with the trigonometric series method for seismic design, and some examples are given to analyze the rationality of this synthetic method.展开更多
Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affecte...Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affected by leaching from the gangue. This can has an impact on the application of the water for agricul- tural irrigation or use as drinking water. Therefore, it is of great significance to understand the effect coal gangue has on the shallow groundwater of a reclaimed area. We studied the effect of coal gangue on fluo- rine, arsenic, mercury, and lead levels in the shallow groundwater of a reclamation area by testing the water and the coal gangue. One well near the reclamation area was used as a control well and element levels in water from this well and from the soil next to the well were also measured. The results show that the levels of these elements are increasing in the reclamation area over time. The increase in fluorine, arsenic, mercury, and lead in monitor wells varies from 7.42% to 8.26%, from 7.13% to 7.90%, from 4.85% to 6.48%, and from 4.69% to 6.42%, respectively. Fluorine and arsenic levels are lower in monitor wells than in the control water. The other elements are found in greater concentration than in the control. The Nemerow index also indicates that the shallow groundwater in the reclamation area I is moderately affected by the back-filling coal gangue, while the shallow groundwater in the reclamation area II and III are slightly affected by the back-filling coal gangue. This shallow groundwater could be used for agri- cultural irrigation or for drinking.展开更多
A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken cha...A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.展开更多
基金supported by the National Natural Science Foundation of China(41977258)the National Key Research and Development Program of China(2017YFC1501005 and 2018YFC1504704)。
文摘Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters.
文摘Left main coronary compression syndrome(LMCS)may complicate pulmonary artery aneurysms(PAA),usually developed in the context of pulmonary arterial hypertension(PAH).We report the case of a 51-year-old female patient with an atrial septal defect(unsuitable for device closure)complicated by a PAA generating a 90%left main stenosis.The significant PAH held us back from immediate surgery.After specific dual PAH-targeted therapy(sildenafil and bosentan),the atrial septal defect could be closed with a unidirectional valved patch;the PAAinduced LMCS was treated by reductive arterioplasty.The postoperative course was uneventful.Follow-up showed clinical improvement,but PAH treatment was still needed.After three months,coronary angiography showed only an insignificant residual left main stenosis,proving that reductive pulmonary arterioplasty was effective in treating LMCS.Any PAA requires further evaluation for LMCS,a dangerous but treatable complication.The“treat-repair-treat”strategy and shunt-closure with a unidirectional valved patch can both improve surgical prospects of LMCS with shunt-related PAH.
文摘 Left main (LM) stenting is considered by many to be one of the last frontiers of interventional cardiology. Beginning with the VA cooperative study published in 1976 demonstrating a mortality benefit for patients undergoing coronary artery bypass grafting (CABG), i the standard of care for treatment of left main coronary artery disease has been surgical.The most recent 2005 update of the ACC/AHA/SCAI Practice Guidelines on PCI 2 again notes that "CABG using IMA grafting is the 'gold standard' for treatment of unprotected left main disease and has proven benefit on long-term outcomes."……
基金Supported by the China National Science and Technology Major Project(2016ZX05014)
文摘Based on comprehensive analysis of core, well logging, seismic and production data, the multi-scale reservoir space, reservoir types, spatial shape and distribution of fractures and caves, and the configuration relationship with production wells in fracture-cavity carbonate reservoirs were studied systematically, the influence of them on the distribution of residual oil was analyzed, and the main controlling factors mode of residual oil distribution after water flooding was established. Enhanced oil recovery methods were studied considering the development practice of Tahe oilfield. Research shows that the main controlling factors of residual oil distribution after water flooding in fracture-cavity carbonate reservoirs can be classified into four categories: local high point, insufficient well control, flow channel shielding and weak hydrodynamic. It is a systematic project to improve oil recovery in fracture-cavity carbonate reservoirs. In the stage of natural depletion, production should be well regulated to prevent bottom water channeling. In the early stage of waterflooding, injection-production relationship should be constructed according to reservoir type, connectivity and spatial location to enhance control and producing degree of waterflooding and minimize remaining oil. In the middle and late stage, according to the main controlling factors and distribution characteristics of remaining oil after water flooding, remaining oil should be tapped precisely by making use of gravity differentiation and capillary force imbibition, enhancing well control, disturbing the flow field and so on. Meanwhile, backup technologies of reservoir stimulation, new injection media, intelligent optimization etc. should be developed, smooth shift from water injection to gas injection should be ensured to maximize oil recovery.
文摘With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.
文摘"Days of the Butterfly"was one of Alice Munro's short stories written in 1950 s, when she was still a new hand. This paper will mainly focus on the development of the main characters in the story, including Myra, the black girl who was the heroine, the teacher Miss Darling, and the Narrator"I". In portraying these characters, Munro adopted several writing techniques including conversation, detailed description, psychological description and so on. She vividly transferred those characters into paper.
文摘Hemodynamically significant left main coronary artery stenosis(LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left cir-cumflex artery has no previous patent grafts.Previous randomized studies have demonstrated a significant re-duction in mortality when revascularization by coronary artery bypass graft(CABG) surgery was undertaken compared with medical treatment.Therefore,current practice guidelines do not recommend percutaneous coronary intervention(PCI) for such a lesion because of the proven benefit of surgery and high rates of reste-nosis with the use of bare metal stents.However,with the advent of drug-eluting stents(DES),the long term outcomes of PCI with DES to treat unprotected LMCA stenoses have been acceptable.Therefore,apart from the current guidelines,PCI for treatment of unprotected LMCA stenosis is often undertaken in individuals who are at a very high risk of CABG or refuse to undergo a sternotomy.Future randomized studies comparing CABG vs PCI using DES for treatment of unprotected LMCA stenosis would be a great advance in clinical knowledge for the adoption of appropriate treatment.
基金supported by National Natural Science Foundation of China(Grant No.51021064)National Key Scientific and Technological Program of China(Grant No.2010ZX04004-116)
文摘The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy saving.To effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are proposed.In the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined.The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis.Thereafter,the performance atlases,which can present all possible design solutions,are depicted.As a result,the feasible solution of the mechanism with good motion/force transmission performance is obtained.And the solution can be flexibly adjusted by designer according to the practical design requirements.The proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.
基金provided by the National Key Basic Research Program of China (No. 2013CB227905)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (No. 51421003)the Jiangsu Province Ordinary University Graduate Student Scientific Research Innovation Projects (No. KYLX16_0564)
文摘In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme. On the basis of revealing and analyzing the coal seam as the main aquifer in western coal mine of Xiao Jihan coal mine, the simulation software of PHASE-2D was applied to analyze the water inflow under different influencing factors. The results showed that water inflow increases logarithmically with the coal seam thickness, increases as a power function with the permeability coefficient of the coal seam, and increases linearly with the coal seam burial depth and the head pressure; The evaluation model for the factors of coal seam water inrush was gained by using nonlinear regression analysis with SPSS. The mine water inrush risk evaluation partition within the scope of the mining field was obtained,through the engineering application in Xiao Jihan coal mine. To ensure the safe and efficient production of the mine, we studied the coal mine water disaster prevention and control measures of a main aquifer coal seam in aspects of roadway driving and coal seam mining.
基金Supported by the Beijing Municipal Science and Technology Commission projectthe Capital of the Public Health Cultivation-Transcatheter active particles implantation combined with TACE/TAE in the treatment of portal vein tumor thrombus in clinical research,No.Z171100000417031
文摘AIM To evaluate the efficacy of main portal vein stents combined with iodine-125(^(125)Ⅰ) to treat main portal vein tumor thrombus.METHODS From January 1, 2010 to January 1, 2015, 111 patients were diagnosed with liver cancer combined with main portal vein tumor thrombus. They were non-randomly assigned to undergo treatment with transarterial chemoembolization(TACE)/transarterial embolization(TAE) + portal vein stents combined with ^(125)Ⅰ implantation(Group A) and TACE/TAE + portal vein stents only(Group B). After the operation, scheduled follow-up was performed at 6, 12 and 24 mo. The recorded information included clinical manifestations, survival rate, and stent restenosis rate. Kaplan–Meier curves, log-rank test and Cox regression were used for data analyses. RESULTS From January 1, 2010 to January 1, 2015, 54 and 57 patients were allocated to Groups A and B, respectively. The survival rates at 6, 12 and 24 mo were 85.2%, 42.6% and 22.2% in Group A and 50.9%, 10.5% and 0% in Group B. The differences were significant [log rank P < 0.05, hazard ratio(HR): 0.37, 95%CI: 0.24-0.56]. The rates of stent restenosis were 18.5%, 55.6% and 83.3% in Group A and 43.9%, 82.5% and 96.5% in Group B. The differences were significant(log rank P < 0.05, HR: 0.42, 95%CI: 0.27-0.63). Cox regression identified that treatment was the only factor affecting survival rate in this study.CONCLUSION Main portal vein stents combined with ^(125)Ⅰ can significantly improve survival rate and reduce the rate of stent restenosis.
基金the Beijing Municipal Science and Technology Commission project,the Capital of the Public Health Cultivation-Transcatheter Implantation combined with TACE/TAE in the treatment of portal vein tumor thrombus in clinical research,No.Z171100000417031
文摘BACKGROUND Main portal vein tumor thrombus(MPVTT), which has a high incidence, is the major complication of terminal liver cancer. The occurrence of MPVTT is always a negative prognostic factor for patients with hepatocellular carcinoma(HCC).Therefore, attention should be paid to the treatment of MPVTT and its complications.AIM To evaluate the efficacy of transarterial chemoembolization/transarterial embolization(TACE/TAE)+^(125)I seeds implantation with transjugular intrahepatic portosystemic shunt(TIPS) in treating MPVTT and its complications.METHODS From January 2007 to March 2015, 85 consecutive patients with MPVTT were nonrandomly assigned to undergo treatment with TACE/TAE + TIPS and ^(125)I implantation(TIPS-^(125)I group) or TACE/TAE + TIPS only(TIPS only group) in Beijing Shijitan Hospital, and all clinical data were collected. During 24 mo follow-up, the incidence of overall survival, stent stenosis and symptom recurrence was analyzed to evaluate the efficacy of TIPS-^(125)I.RESULTS During 24 mo follow-up of all patients, we collected data at 6, 12 and 24 mo. The rates of survival were 80%, 45%, and 20%, respectively, in the TIPS-^(125)I group,whereas those in the TIPS only group were 64.4%, 24.4%, and 4.4%, respectively(P < 0.05). The rates of symptom recurrence were 7.5%, 22.5%, and 35%,respectively, in the TIPS-^(125)I group, whereas those in the TIPS only group were31.1%, 62.2%, and 82.2%(P < 0.05). The rates of stent restenosis were 12.5%,27.5%, and 42.5%, respectively, in the TIPS-^(125)I group, and 42.2%, 68.9%, and84.4%, respectively, in the TIPS only group(P < 0.05). TIPS-^(125)I was found to be significantly favorable in treating MPVTT and its complications in patients with HCC.CONCLUSION TACE/TAE+^(125)I combined with TIPS is effective in treating MPVTT and its complications, improving quality of life of patients and reducing mortality.
基金National Nature Science Foundation of China under Grant No.51778183the National Science Foundation for Distinguished Young Scholars of China under Grant No.51525802
文摘To consider the infl uence of aftershocks in engineering design, the correlations between main shocks and aftershocks should be examined, and an aftershock simulation method with main shock ground motions needs to be developed. In this study, the data on the sequences of main shock–aftershock ground motions and other related parameters were collected. Using these data, correlations between the magnitude, frequency, duration and energy of the main shock–aftershock ground motions were investigated. The results showed that the magnitude of the aftershock can be larger than that of the main shock. The shapes of the Fourier amplitude spectra of main shocks and aftershocks were similar;however, the predominant frequency and high-frequency components of the aftershock tended to be larger. Considering the magnitude diff erence between the main shock and the aftershock, the correlation of durations was explored. Additionally, a new concept, the duration ratio, was defi ned to describe the concentration of seismic energy release, and main shock energy was strongly positively correlated with the energy attenuated during the main shock–aftershock sequence. Finally, based on these results regarding correlation, an aftershock synthesis using recorded main shock ground motions was constructed with the trigonometric series method for seismic design, and some examples are given to analyze the rationality of this synthetic method.
基金The project was funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affected by leaching from the gangue. This can has an impact on the application of the water for agricul- tural irrigation or use as drinking water. Therefore, it is of great significance to understand the effect coal gangue has on the shallow groundwater of a reclaimed area. We studied the effect of coal gangue on fluo- rine, arsenic, mercury, and lead levels in the shallow groundwater of a reclamation area by testing the water and the coal gangue. One well near the reclamation area was used as a control well and element levels in water from this well and from the soil next to the well were also measured. The results show that the levels of these elements are increasing in the reclamation area over time. The increase in fluorine, arsenic, mercury, and lead in monitor wells varies from 7.42% to 8.26%, from 7.13% to 7.90%, from 4.85% to 6.48%, and from 4.69% to 6.42%, respectively. Fluorine and arsenic levels are lower in monitor wells than in the control water. The other elements are found in greater concentration than in the control. The Nemerow index also indicates that the shallow groundwater in the reclamation area I is moderately affected by the back-filling coal gangue, while the shallow groundwater in the reclamation area II and III are slightly affected by the back-filling coal gangue. This shallow groundwater could be used for agri- cultural irrigation or for drinking.
基金supported by the National Natural Science Foundation of China (Nos. 51404013 and 51674008)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining at the China University of Mining and Technology (No. 13KF01)the Natural Science Foundation of Anhui Province (Nos. 1508085ME77 and 1508085QE89)
文摘A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.
