Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape not...Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape notch on the spool, such as mass flow rates, flow coefficients, effiux angles and steady state flow forces under different operating conditions. At last, the reliability of the mathematical model of the flow area for the sloping U-shape notch orifice on the spool was demonstrated by the comparison between the orifice area curve derived and the corresponding experimental data provided by the test. It is presented that the bottom arc of sloping U-shape notch （ABU） should not be omitted when it is required to accurately calculate the orifice area of ABU. Although the theoretical flow area of plain bottom sloping U-shape notch （PBU） is larger than that of ABU at the same opening, the simulated mass flow and experimental flow area of ABU are both larger than these of PBU at the same opening, while the simulated flow force of PBU is larger than that of ABU at the same opening. Therefore, it should be prior to adapt the ABU when designing the spool with proportional character.展开更多
It is well known that, in most cases, soil water doesn't move in the form of laminar flow as described by Darcy law. Only when Reynolds number ( Re ) is no more than 10, does water movement follow Darcy law. A s...It is well known that, in most cases, soil water doesn't move in the form of laminar flow as described by Darcy law. Only when Reynolds number ( Re ) is no more than 10, does water movement follow Darcy law. A soil profile with 2 9 m long and 2 13 2 60 m deep was excavated on a lower slope located at Zigui County, Hubei Province, China. Field observation found that soil pipes were mainly distributed in the transient layer between horizon B with higher degree of granite weathering and horizon C with lower degree of granite weathering. At the foot of the slope, about 5 7 soil pipes per meter were observed along the vertical direction of the slope. The observed results, obtained by continuous observation of soil pipes and pipe flow processes at granite slope for many rainfall events, indicate that the relationship between velocity of pipe flow and hydraulic gradient along the pipe is parabolic rather than linear. Based on the investigated data of soil, landform, and land use etc., combined with observed data of pipe flow derived from many rainfall events, a pipe flow model was developed. For velocity V p, discharge Q p of pipe flow and radius r of soil pipe, great similarity was found between simulated and observed values. Particularly, the simulated length of soil pipes reflects the great difference among soil pipes as a result of its different position in the soil profile. The length values of 4 soil pipes were estimated to be 98 1%, 27 6%, 11 0% and 3 0% of the longest distance of the catchment, respectively. As a special case of water movement, soil pipe flow follows Darcy Weisbach law. Discharge of pipe flow is much greater than infiltration discharge in common. Only when the depth of groundwater is more than the diameter of soil pipe and water layer submerges soil pipes during rainfall, may pipe flow occur. Under these circumstances, discharge of pipe flow is directly proportional to the depth of groundwater.展开更多
Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynami...Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynamic balance theory of local flow field in multilayer gob area was built based on the realistic requirement that the serious threat on current mining coal layer by large-scale spontaneous combustion fire on close spontaneous combustion coal layer group of Datong Coal mining area at the ＇di-hard＇ conditions was caused by small coal pit mining. The kernel was in dynamic balance between flow field pressures of working face and local flow field in multilayer gob area was kept by transformation. Corresponding technology and set of devices were developed.展开更多
Highways in mountainous areas are easy to be damaged by such natural disasters as debris flows and landslides and disaster reduction decision support system (DRDSS) is one of the important means to mitigate these disa...Highways in mountainous areas are easy to be damaged by such natural disasters as debris flows and landslides and disaster reduction decision support system (DRDSS) is one of the important means to mitigate these disasters. Guided by the theories and technologies of debris flow and landslide reduction and supported by geographical information system (GIS), remote sensing and database techniques, a DRDSS against debris flow and landslide along highways in mountainous areas has been established on the basis of such principles as pertinence, systematicness, effectiveness, easy to use, open and expandability. The system consists of database, disaster analysis models and decisions on reduction of debris flows and landslides, mainly functioning to zone disaster dangerous degree, analyze debris flow activity, simulate debris flow deposition and diffusion, analyze landslide stability, select optimal highway renovation scheme and plan disaster prevention and control engineering. This system has been applied successfully to the debris flow and landslide treatment works along Palongzangbu Section of Sichuan-Tibet Highway.展开更多
Debris flows are the one type of natural disaster that is most closely associated with hu- man activities. Debris flows are characterized as being widely distributed and frequently activated. Rainfall is an important ...Debris flows are the one type of natural disaster that is most closely associated with hu- man activities. Debris flows are characterized as being widely distributed and frequently activated. Rainfall is an important component of debris flows and is the most active factor when debris flows oc- cur. Rainfall also determines the temporal and spatial distribution characteristics of the hazards. A reasonable rainfall threshold target is essential to ensuring the accuracy of debris flow pre-warning. Such a threshold is important for the study of the mechanisms of debris flow formation, predicting the characteristics of future activities and the design of prevention and engineering control measures. Most mountainous areas have little data regarding rainfall and hazards, especially in debris flow forming re- gions. Therefore, both the traditional demonstration method and frequency calculated method cannot satisfy the debris flow pre-warning requirements. This study presents the characteristics of pre-warning regions, included the rainfall, hydrologic and topographic conditions. An analogous area with abundant data and the same conditions as the pre-warning region was selected, and the rainfall threshold was calculated by proxy. This method resolved the problem of debris flow pre-warning in ar- eas lacking data and provided a new approach for debris flow pre-warning in mountainous areas.展开更多
Using the broadband seismic data of the regional stations in the Sichuan Digital Seismic Network and the mobile seismic stations in this region,the receiver function inversion method was adopted to study the character...Using the broadband seismic data of the regional stations in the Sichuan Digital Seismic Network and the mobile seismic stations in this region,the receiver function inversion method was adopted to study the characteristics of crustal flow and dynamic effects in Sichuan and adjacent areas. The results show that: Velocity in the crust and upper mantle of the Sichuan basin is significantly higher than that beneath the eastern margin of the Qinghai-Tibetan plateau. The velocity v_S is from 3. 6 to 3. 8km / s in the crust and4. 5- 4. 8km / s in the upper mantle beneath the basin,and there is no low-velocity layer in the crust. The lithology shows a hard block. The v_S velocity in the eastern margin of the Qinghai-Tibetan plateau is lower,with average v_Sof 3. 0- 3. 4km / s in the mid crust and4. 0- 4. 5km / s in the upper mantle. Low-velocity layers are distributed widely in the crust,most of which are in the mid crust at a depth of 20km- 40 km,and there are also a few low-velocity layers appearing in the upper crust at depths of 10km- 20 km and the lower crust at depths of 40km- 60 km. Affected by the northward pushing of the Indian plate,the eastward movement of the eastern margin of the Qinghai-Tibetan plateau is blocked by the hard Sichuan basin,producing a southward and southeastward component.Such movement process is produced by the complicated forces acting in this area. Just under the action of these forces, the eastern margin of the Qinghai-Tibetan plateau becomes a region with complicated geology and intensive earthquake activity. Obstructed by the hard Sichuan basin,the low-velocity crustal flow is delaminated and split into two or three upward and downward tributaries. The upward flow intruded into the upper crust,causing uplift of the earths urface,forming mountain crests; the downward flow intruded into the lower crust and upper mantle,resulting in thickening of the crust and depression of the Moho. The crustal flow in the eastern margin of the Qinghai-Tibetan plateau is mainly distributed along the active faults. The crustal flow flows out from the Qiangtang block in the middle part of the eastern margin of the Qinghai-Tibetan plateau,the mainstream flows along the NW-SE trending Xianshuihe fault zone,then turns NS and flows to the south along the Anninghe and Xiaojiang faults. There is another crustal flow in the north of the study area,flowing in the NE and E-W directions to the Longmenshan faults.展开更多
[Objective] The research aimed to study winter operation process of the surface flow constructed wetland in ＂rianjin area. [Method] In view of climate characteristics in Tianjin, by the way of running under the ice, ...[Objective] The research aimed to study winter operation process of the surface flow constructed wetland in ＂rianjin area. [Method] In view of climate characteristics in Tianjin, by the way of running under the ice, winter operation experiment of the surface flow constructed wetland in Tianjin was conducted, with the expectation to get some useful process parameters to run such systems in North China in winter. [ Result] Although purification effect of the sewage by surface flow constructed wetland in winter was worse than that in other seasons （ average reduction of about 20%）, surface flow constructed wetland running under the ice was feasible in Tianjin area. When surface flow constructed wetland in North China ran under ice in winter, it was suggested that the outlet must be located in a low position to prevent to be completely frozen, and running water depth should not be less than 50 -60 cm. The hydraulic load could be raised on the basis of reflux, and hydraulic retention time should maintain less than 4 d to keep water-soil interface not freezing. Inlet water depth should be increased as much as possible to improve temperature in the system. V Conclusion1 The research could provide reference for promotion and application of the surface flow constructed wetland in North China.展开更多
Using Picard's theorem and the Leray-Schauder fixed point theorem to reinvestigate the area-preserving convex curve flow in the plane which is considered as a coupled system and thus different from the setting han...Using Picard's theorem and the Leray-Schauder fixed point theorem to reinvestigate the area-preserving convex curve flow in the plane which is considered as a coupled system and thus different from the setting handled by Gage.展开更多
This paper models the giraffe’s jugular veins as a uniform collapsible tube from a rigid skull. The equations governing one-dimensional steady flow through such a tube for various conditions have been developed. The ...This paper models the giraffe’s jugular veins as a uniform collapsible tube from a rigid skull. The equations governing one-dimensional steady flow through such a tube for various conditions have been developed. The effects of inertial and inclination angles that have not been discussed previously have been included. It has been shown that different flows for a uniform tube (vein) are possible. However, this flow matches that of a jugular vein which is supercritical, and the steady solution has been given by the balance between the driving forces of gravity and the viscous resistance to the flow at the right atrium of the heart must be sub-critical for a fixed right-atrium pressure which means that an elastic jump is required to return the flow to sub-critical from the supercritical flow upstream this type of relationship gives rise to flow limitation at the same time given any right atrium fixed pressure there exists a maximum flow rate which when exceeded the boundary conditions of the flow do not hold boundary conditions at the right atrium are not satisfied hence making the steady flow impossible this mechanism of flow limitation is slightly different from the other one in that causes airways through forced expiration from the observation made it is clearly shown that there is an intravascular pressure difference with a change in height.展开更多
基于钻井、测井、实验分析及生产等资料,以磨溪气田嘉二气藏主力产层嘉二^(2)亚段B层(T_(1)j_(2)^(2B))白云岩储层为研究对象,利用流动单元来表征气藏白云岩储层非均质性,通过对比流动层带指数、孔喉半径(R_(35))及聚类分析的流动单元...基于钻井、测井、实验分析及生产等资料,以磨溪气田嘉二气藏主力产层嘉二^(2)亚段B层(T_(1)j_(2)^(2B))白云岩储层为研究对象,利用流动单元来表征气藏白云岩储层非均质性,通过对比流动层带指数、孔喉半径(R_(35))及聚类分析的流动单元划分方法,在取心井流动单元的研究基础上,利用多元回归的方式定量评价FZI(Flow Zone Index)值,未取心井通过fisher判别分析函数精细划分.从压汞参数与生产动态资料验证其流动单元划分合理性.研究结果表明:对于薄层的白云岩储层,采用流动层带指数法划分的流动单元为一组具有较好孔渗关系的岩石类型,R_(35)所划分的流动单元为一组具有相似孔喉半径(不同孔隙度有着相近的渗透率)的岩石类型,通过聚类方法,能将具有相似的孔隙结构的储层归位一类流动单元;流动层带指数的测井识别是流动单元划分的难点,机器学习、神经网络等算法对于精度具有较大提升,但需要大量数据,对于研究区,常规的线性回归方式成为了最佳的选择;流动单元预测结果与压汞参数、初期产能存在较强相关性,流动单元划分结果可靠,可为后续气藏的开发提供参考.展开更多
基金Project(51004085)supported by the National Natural Science Foundation of China
文摘Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape notch on the spool, such as mass flow rates, flow coefficients, effiux angles and steady state flow forces under different operating conditions. At last, the reliability of the mathematical model of the flow area for the sloping U-shape notch orifice on the spool was demonstrated by the comparison between the orifice area curve derived and the corresponding experimental data provided by the test. It is presented that the bottom arc of sloping U-shape notch （ABU） should not be omitted when it is required to accurately calculate the orifice area of ABU. Although the theoretical flow area of plain bottom sloping U-shape notch （PBU） is larger than that of ABU at the same opening, the simulated mass flow and experimental flow area of ABU are both larger than these of PBU at the same opening, while the simulated flow force of PBU is larger than that of ABU at the same opening. Therefore, it should be prior to adapt the ABU when designing the spool with proportional character.
文摘It is well known that, in most cases, soil water doesn't move in the form of laminar flow as described by Darcy law. Only when Reynolds number ( Re ) is no more than 10, does water movement follow Darcy law. A soil profile with 2 9 m long and 2 13 2 60 m deep was excavated on a lower slope located at Zigui County, Hubei Province, China. Field observation found that soil pipes were mainly distributed in the transient layer between horizon B with higher degree of granite weathering and horizon C with lower degree of granite weathering. At the foot of the slope, about 5 7 soil pipes per meter were observed along the vertical direction of the slope. The observed results, obtained by continuous observation of soil pipes and pipe flow processes at granite slope for many rainfall events, indicate that the relationship between velocity of pipe flow and hydraulic gradient along the pipe is parabolic rather than linear. Based on the investigated data of soil, landform, and land use etc., combined with observed data of pipe flow derived from many rainfall events, a pipe flow model was developed. For velocity V p, discharge Q p of pipe flow and radius r of soil pipe, great similarity was found between simulated and observed values. Particularly, the simulated length of soil pipes reflects the great difference among soil pipes as a result of its different position in the soil profile. The length values of 4 soil pipes were estimated to be 98 1%, 27 6%, 11 0% and 3 0% of the longest distance of the catchment, respectively. As a special case of water movement, soil pipe flow follows Darcy Weisbach law. Discharge of pipe flow is much greater than infiltration discharge in common. Only when the depth of groundwater is more than the diameter of soil pipe and water layer submerges soil pipes during rainfall, may pipe flow occur. Under these circumstances, discharge of pipe flow is directly proportional to the depth of groundwater.
基金Supported by the Key Projects of the National Natural Science Foundation of China （50834002）
文摘Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynamic balance theory of local flow field in multilayer gob area was built based on the realistic requirement that the serious threat on current mining coal layer by large-scale spontaneous combustion fire on close spontaneous combustion coal layer group of Datong Coal mining area at the ＇di-hard＇ conditions was caused by small coal pit mining. The kernel was in dynamic balance between flow field pressures of working face and local flow field in multilayer gob area was kept by transformation. Corresponding technology and set of devices were developed.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences(KZCX2-306)the National Natural Science Foundation of China(90202007)
文摘Highways in mountainous areas are easy to be damaged by such natural disasters as debris flows and landslides and disaster reduction decision support system (DRDSS) is one of the important means to mitigate these disasters. Guided by the theories and technologies of debris flow and landslide reduction and supported by geographical information system (GIS), remote sensing and database techniques, a DRDSS against debris flow and landslide along highways in mountainous areas has been established on the basis of such principles as pertinence, systematicness, effectiveness, easy to use, open and expandability. The system consists of database, disaster analysis models and decisions on reduction of debris flows and landslides, mainly functioning to zone disaster dangerous degree, analyze debris flow activity, simulate debris flow deposition and diffusion, analyze landslide stability, select optimal highway renovation scheme and plan disaster prevention and control engineering. This system has been applied successfully to the debris flow and landslide treatment works along Palongzangbu Section of Sichuan-Tibet Highway.
基金supported by the National Natural Science Foundation of China(Nos.40830742 and 40901007)
文摘Debris flows are the one type of natural disaster that is most closely associated with hu- man activities. Debris flows are characterized as being widely distributed and frequently activated. Rainfall is an important component of debris flows and is the most active factor when debris flows oc- cur. Rainfall also determines the temporal and spatial distribution characteristics of the hazards. A reasonable rainfall threshold target is essential to ensuring the accuracy of debris flow pre-warning. Such a threshold is important for the study of the mechanisms of debris flow formation, predicting the characteristics of future activities and the design of prevention and engineering control measures. Most mountainous areas have little data regarding rainfall and hazards, especially in debris flow forming re- gions. Therefore, both the traditional demonstration method and frequency calculated method cannot satisfy the debris flow pre-warning requirements. This study presents the characteristics of pre-warning regions, included the rainfall, hydrologic and topographic conditions. An analogous area with abundant data and the same conditions as the pre-warning region was selected, and the rainfall threshold was calculated by proxy. This method resolved the problem of debris flow pre-warning in ar- eas lacking data and provided a new approach for debris flow pre-warning in mountainous areas.
基金funded by the key project of National Natural Science Foundation of China(Grant No.40839909 and 41074062)
文摘Using the broadband seismic data of the regional stations in the Sichuan Digital Seismic Network and the mobile seismic stations in this region,the receiver function inversion method was adopted to study the characteristics of crustal flow and dynamic effects in Sichuan and adjacent areas. The results show that: Velocity in the crust and upper mantle of the Sichuan basin is significantly higher than that beneath the eastern margin of the Qinghai-Tibetan plateau. The velocity v_S is from 3. 6 to 3. 8km / s in the crust and4. 5- 4. 8km / s in the upper mantle beneath the basin,and there is no low-velocity layer in the crust. The lithology shows a hard block. The v_S velocity in the eastern margin of the Qinghai-Tibetan plateau is lower,with average v_Sof 3. 0- 3. 4km / s in the mid crust and4. 0- 4. 5km / s in the upper mantle. Low-velocity layers are distributed widely in the crust,most of which are in the mid crust at a depth of 20km- 40 km,and there are also a few low-velocity layers appearing in the upper crust at depths of 10km- 20 km and the lower crust at depths of 40km- 60 km. Affected by the northward pushing of the Indian plate,the eastward movement of the eastern margin of the Qinghai-Tibetan plateau is blocked by the hard Sichuan basin,producing a southward and southeastward component.Such movement process is produced by the complicated forces acting in this area. Just under the action of these forces, the eastern margin of the Qinghai-Tibetan plateau becomes a region with complicated geology and intensive earthquake activity. Obstructed by the hard Sichuan basin,the low-velocity crustal flow is delaminated and split into two or three upward and downward tributaries. The upward flow intruded into the upper crust,causing uplift of the earths urface,forming mountain crests; the downward flow intruded into the lower crust and upper mantle,resulting in thickening of the crust and depression of the Moho. The crustal flow in the eastern margin of the Qinghai-Tibetan plateau is mainly distributed along the active faults. The crustal flow flows out from the Qiangtang block in the middle part of the eastern margin of the Qinghai-Tibetan plateau,the mainstream flows along the NW-SE trending Xianshuihe fault zone,then turns NS and flows to the south along the Anninghe and Xiaojiang faults. There is another crustal flow in the north of the study area,flowing in the NE and E-W directions to the Longmenshan faults.
基金Supported by Special Project of the Science Research in Public Service Industry,Ministry of Water Resources,China(2011-BH140002)
文摘[Objective] The research aimed to study winter operation process of the surface flow constructed wetland in ＂rianjin area. [Method] In view of climate characteristics in Tianjin, by the way of running under the ice, winter operation experiment of the surface flow constructed wetland in Tianjin was conducted, with the expectation to get some useful process parameters to run such systems in North China in winter. [ Result] Although purification effect of the sewage by surface flow constructed wetland in winter was worse than that in other seasons （ average reduction of about 20%）, surface flow constructed wetland running under the ice was feasible in Tianjin area. When surface flow constructed wetland in North China ran under ice in winter, it was suggested that the outlet must be located in a low position to prevent to be completely frozen, and running water depth should not be less than 50 -60 cm. The hydraulic load could be raised on the basis of reflux, and hydraulic retention time should maintain less than 4 d to keep water-soil interface not freezing. Inlet water depth should be increased as much as possible to improve temperature in the system. V Conclusion1 The research could provide reference for promotion and application of the surface flow constructed wetland in North China.
文摘Using Picard's theorem and the Leray-Schauder fixed point theorem to reinvestigate the area-preserving convex curve flow in the plane which is considered as a coupled system and thus different from the setting handled by Gage.
文摘This paper models the giraffe’s jugular veins as a uniform collapsible tube from a rigid skull. The equations governing one-dimensional steady flow through such a tube for various conditions have been developed. The effects of inertial and inclination angles that have not been discussed previously have been included. It has been shown that different flows for a uniform tube (vein) are possible. However, this flow matches that of a jugular vein which is supercritical, and the steady solution has been given by the balance between the driving forces of gravity and the viscous resistance to the flow at the right atrium of the heart must be sub-critical for a fixed right-atrium pressure which means that an elastic jump is required to return the flow to sub-critical from the supercritical flow upstream this type of relationship gives rise to flow limitation at the same time given any right atrium fixed pressure there exists a maximum flow rate which when exceeded the boundary conditions of the flow do not hold boundary conditions at the right atrium are not satisfied hence making the steady flow impossible this mechanism of flow limitation is slightly different from the other one in that causes airways through forced expiration from the observation made it is clearly shown that there is an intravascular pressure difference with a change in height.
文摘基于钻井、测井、实验分析及生产等资料,以磨溪气田嘉二气藏主力产层嘉二^(2)亚段B层(T_(1)j_(2)^(2B))白云岩储层为研究对象,利用流动单元来表征气藏白云岩储层非均质性,通过对比流动层带指数、孔喉半径(R_(35))及聚类分析的流动单元划分方法,在取心井流动单元的研究基础上,利用多元回归的方式定量评价FZI(Flow Zone Index)值,未取心井通过fisher判别分析函数精细划分.从压汞参数与生产动态资料验证其流动单元划分合理性.研究结果表明:对于薄层的白云岩储层,采用流动层带指数法划分的流动单元为一组具有较好孔渗关系的岩石类型,R_(35)所划分的流动单元为一组具有相似孔喉半径(不同孔隙度有着相近的渗透率)的岩石类型,通过聚类方法,能将具有相似的孔隙结构的储层归位一类流动单元;流动层带指数的测井识别是流动单元划分的难点,机器学习、神经网络等算法对于精度具有较大提升,但需要大量数据,对于研究区,常规的线性回归方式成为了最佳的选择;流动单元预测结果与压汞参数、初期产能存在较强相关性,流动单元划分结果可靠,可为后续气藏的开发提供参考.
