Heat and mass transfer of a circular-shaped porous moist object inside a two-dimensional triangle cavity is investigated by using finite element method.The porous object is considered to be a moist food sample,located...Heat and mass transfer of a circular-shaped porous moist object inside a two-dimensional triangle cavity is investigated by using finite element method.The porous object is considered to be a moist food sample,located in the middle of the cavity with inlet and outlet ports with different configurations of inlet/outlet ports.Convective drying performance is numerically assessed for different values of Reynolds numbers(between 50 and 250),dry air inlet temperature(between 40 and 80℃)and different locations of the port.It is observed that changing the port locations has significant impacts on the flow recirculaitons inside the triangular chamber while convective drying performance is highly affected.The moisture content reduces with longer time and for higher Reynolds number(Re)values.Case P4 where inlet and outlet ports are in the middle of the walls provides the most effective configuration in terms of convective drying performance while the worst case is seen for P1 case where inlet and outlet are closer to the corners of the chamber.There is a 192% difference between the moisture reduction of these two cases at Re=250,T=80℃ and t=120 min.展开更多
Abstract: With a determinate danger zone and evacuation demand caused by an emergency, an optimization method for the evacuation zone with network reconfiguration based on dynamic simulation is proposed. The method c...Abstract: With a determinate danger zone and evacuation demand caused by an emergency, an optimization method for the evacuation zone with network reconfiguration based on dynamic simulation is proposed. The method contains three modules. First, the network in the evacuation zone is optimized by a model with the integrated strategy of lane reversal and intersection conflict elimination. Secondly, the dynamic evacuation simulation model based on the cell transmission model is applied to simulate the dynamic propagation process of evacuated vehicles in the network in the evacuation zone. The evacuation time for all evacuated vehicles leaving the danger zone is obtained and the setting of the current evacuation zone is fed back. Thirdly, the arrival distributions of evacuated vehicles at critical intersections of the evacuation zone are also obtained to estimate the delay at critical intersection to determine whether the intersection should be taken as the critical intersection in the next iteration. The evacuation zone is expanded gradually through iteration, and the reasonable evacuation zone and the optimal evacuation network is confirmed. Based on the survey of the parking lot and urban street network around Nanjing Olympic Sports Center, the models and the iterative algorithm were applied to obtain the optimal plan of the evacuation zone with network reconfiguration in an evacuation situation to verify the validity of the proposed method.展开更多
Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflo...Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflora composed of diverse prokaryotic and possible eukaryotic microbes. Macroscopic algae have also been found. This Formation provides important paleobiological information from which to assess status of Mesoproterozoic life, and to evaluate paleoenvironmental conditions and pre-Phanerozoic biostratigraphy. The Gaoyuzhuang Formation has yielded over 100 taxa described by over 10 investigators. Most of the microbial taxa can be divided into three different assemblages according to their paleobiological and paleoenvironmental characteristics. I. The oscillatoriacean/chroococcacean assemblage which occurs in the first member of the Formation and this is interpreted to represent an assemblage from shallow water mat-building and mat-dwelling taxa with some possible planktonic taxa; 2. the nostocacean assemblage found only in the second member, and includes benthic mat-building or mat-dwelling taxa; and 3. the chroococcacean assemblage of the fourth member, which represents intertidal to supratidal mat-building and allochthonous taxa. Proterozoic microfossils found in chert, especially cyanobacteria, are possibly more valuable as paleoenvironmental indicators than as chronostratigraphic tools because of their morphological conservation, although trends in diversity appear to exist for cyanobacteria in the Proterozoic. The general characteristics of Gaoyuzhuang microfossils, and the fact that most nostocacean chains occur and are. preserved with the chain perpendicular to bedding indicate that: (1) the individual size of Gaoyuzhuang microfossils are part of a general trend of increase with time; (2) Gaoyuzhuang deposits are possibly in a fresh water environment and the rate of sedimentation might be equal to or less than the microbial growth rate; (3) the sedimentary model of Gaoyuzhuang might be from intertidal to subtidal or deep sea, and then to intertidal or supratidal; and (4) the eukaryotic organisms had densely occurred when Gaoyuzhuang Formation deposited.展开更多
Floating zone method with optical radiation heating was applied to growing a class of R2PdSi3(R=Pr,Tb and Gd) single crystals due to its containerless melting and high stability of the floating zone.One serious prob...Floating zone method with optical radiation heating was applied to growing a class of R2PdSi3(R=Pr,Tb and Gd) single crystals due to its containerless melting and high stability of the floating zone.One serious problem during the single crystal growth,precipitates of secondary phases,was discussed from the following four parts:precipitates from the raw materials and preparation process,precipitates formed during the growing process,precipitates in the melts and precipitates in the grown crystals.Annealing treatment and composition shift can effectively reduce the precipitates which are not formed during the crystallization but precipitated on post-solidification cooling from the as-grown crystal matrix because of the retrograde solubility of Si.展开更多
A remote antenna unit (RAU) selection model is presented, and two kinds of handoffs, intra-cell handoff (HO) and inter-cell HO, are defined in distributed mobile communications systems (DAS). After that, an inte...A remote antenna unit (RAU) selection model is presented, and two kinds of handoffs, intra-cell handoff (HO) and inter-cell HO, are defined in distributed mobile communications systems (DAS). After that, an inter-cell HO model is proposed, in which the average power of the active set (AS) is used to predict the position of the mobile station (MS). The total power of the AS and the handoff set (HOS) are utilized to determine whether an inter-cell HO is necessary. Furthermore, the relationship between HO parameters and performance metrics is studied in detail based on RAU selection. Simulation results show that both the intra-cell HO and the inter-cell HO can achieve oerfect performance by aoprooriate settings of HO parameters.展开更多
X-ray microanalysis was used to study the elemental composition of the shell of the freshwater testate amoeba Difflugia tuberspinifera Hu et al.,1997 collected from Mulan Lake,Hubei province,China in July 2003.The res...X-ray microanalysis was used to study the elemental composition of the shell of the freshwater testate amoeba Difflugia tuberspinifera Hu et al.,1997 collected from Mulan Lake,Hubei province,China in July 2003.The results show that the shell is composed of ten elements:Si in greater quantity;then Ca and Al;and traces of K,Na,Cl,Fe,Mg,S and P.The analysis of results suggests that D.tuberspinifera in elemental composition appears to occupy a middle position between marine and soil testate amoebae.展开更多
The oxidation behavior of Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys at 800 °C for exposure time up to 100 h was examined. It is shown that oxidation rate of experimental alloys obeys the parabolic kinetics. Ti?22Al...The oxidation behavior of Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys at 800 °C for exposure time up to 100 h was examined. It is shown that oxidation rate of experimental alloys obeys the parabolic kinetics. Ti?22Al?26Nb?1Zr alloy demonstrates more excellent oxidation resistance than the other two alloys. The main oxidation products are TiO2, Al2O3 and AlNbO4 phases for all these alloys. For the Ti?22Al?26Nb?1Zr alloy, Zr addition can modify the growth mechanism of oxide scale, which can effectively hinder the diffusion of oxygen. Whereas, reaction of Zr with oxygen leads to the formation of ZrO2 precipitates for the Ti?22Al?21Nb?6Zr alloy, which promotes the oxygen ingress into the substrate. Meanwhile, oxidation affected zones, including internal-oxidation layer and oxygen-enriched zone, are present beneath the outmost oxide scale. The difference in these zones is derived from the phase constitution in the starting Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys.展开更多
The effect of the local hard zone (LHZ) distributed in the coarse grained HAZ (CGHAZ) has been analyzed by 2-dimensional FEM on a mechanical model of the weld CGHAZ. The existence of the LHZ elevates considerably the ...The effect of the local hard zone (LHZ) distributed in the coarse grained HAZ (CGHAZ) has been analyzed by 2-dimensional FEM on a mechanical model of the weld CGHAZ. The existence of the LHZ elevates considerably the stress in LHZ and causes the discontinuity of strain at the boundary between the LHZ and the matrix. The stress distribution in the LHZ is strongly affected by the shape of the LHZ. In a slender LHZ almost the whole region in the LHZ is exposed to elevated stress, whereas in the massive LHZ only the edge region sustains high stress. The longer the LHZ becomes, the more the highly stressed area, and the peak stress in the LHZ grows even under the same volume fraction of the LHZ. These results indicate that the slender LHZ brings about unstable fracture at a lower load level than the blocky LHZ. This tendency was confirmed by CTOD test results on the weld CGHAZ of a high-strength steel. The CGHAZ with elongated M-A constituents fractures at apparently lower critical CTOD than the CGHAZ with massive M-A constituents. In conclusion, the control of the shape of the M-A constituent has a striking effect on the toughness improvement of CGHAZ.展开更多
Psychophysical studies suggest that lateral extrastriate visual cortical areas in cats may mediate the sparing of vision largely by network reorganization following lesions of early visual cortical areas. To date, how...Psychophysical studies suggest that lateral extrastriate visual cortical areas in cats may mediate the sparing of vision largely by network reorganization following lesions of early visual cortical areas. To date, however, there is little direct physiological evidence to support this hypothesis. Using in vivo single-anit recording techniques, we examined the response of neurons in areas 19, 21, and 20 to different types of visual stimulation in cats with or without acute bilateral lesions in areas 17 and 18. Our results showed that, relative to the controls, acute lesions inactivated the response of 99.3% of neurons to moving gratings and 93% of neurons to flickering square stimuli'in areas 19, 21, and 20. These results indicated that acute lesions of primary visual areas in adult eats may impair most visual abilities. Sparing of vision in cats with neonatal lesions in early visual cortical areas may result largely from a postoperative reorganization of visual pathways from subcortical nucleus to extrastriate visual cortical areas.展开更多
This paper discusses a fictitious domain method for the linear Dirichlet problem and its applications to the generalized Stokes problem. This method treats Dirichlet boundary condit ion via a Lagrange multiplier tec...This paper discusses a fictitious domain method for the linear Dirichlet problem and its applications to the generalized Stokes problem. This method treats Dirichlet boundary condit ion via a Lagrange multiplier technique and is well suited to the no-slip bound ary condition in viscous flow problems. In order to improve the accuracy of solu tions, meshes are refined according to the a posteriori error estimate. The mini -element discretization is applied to solve the generalized Stokes problem. Fin ally, some numerical results to validate this method are presented for partial d ifferential equations with Dirichlet boundary condition.展开更多
Trace element(TE) and rare earth element(REE) contents in red soils from the Dongting Lake area of China were determined to understanding the provenance and weathering characteristics of the red soils.The results show...Trace element(TE) and rare earth element(REE) contents in red soils from the Dongting Lake area of China were determined to understanding the provenance and weathering characteristics of the red soils.The results showed similar REE distribution patterns among red soils from the Dongting Lake area,Xiashu loess from Zhenjiang,loess and Pliocene red soil from the Loess Plateau.These patterns implied a similar provenance from dust-storms,except for red soil R5 which formed by bedrock weathering and had significant light REE(LREE) enrichment and heavy REE(HREE) depletion due to longer weathering periods and higher intensity of weathering.Trace element,especially the Rb/Sr and Li/Ba ratios,and REE,especially the LREE/HREE ratio and δEu could trace weathering intensity.Higher Rb/Sr,Li/Ba,and LREE/HREE ratios and negative Eu anomalies were present in the red soils from the Dongting Lake area.The weathering intensity was in the decreasing order of R5 in the Dongting Lake area > red soils from the Dongting Lake area(including reticulate red soil,weak reticulate red soil,and homogeneous red soil formed by dust storms) > Xiashu loess from Zhenjiang > loess-paleosol and Pliocene red soil from the Loess Plateau.Variations in the TE and REE contents of soil could be effectively used to study the provenance and the weathering intensity.展开更多
Taking Adaohai Coal Mine as the example, underground pressure appearance laws of fully mechanized top coal slice caving on high-dipping and thick coal seams. Through site visit, theoretical analysis and discrete eleme...Taking Adaohai Coal Mine as the example, underground pressure appearance laws of fully mechanized top coal slice caving on high-dipping and thick coal seams. Through site visit, theoretical analysis and discrete element calculation, the research shows that, as the mining deepens, underground stress of lower sublevels is more obvious and higher than that of upper sublevels and is higher in the air return roadway than that in the air intake roadway in the area that is near to the top coal. Because the top coal is thick and gangue is caved above the support, underground pressure to the working face is relatively gentle. Immediate roof will mainly fall down along the floor. Main roof and the rock bed above the main roof will move to the mined out area along the fault in the early stage and then fall down with the mined out area later. In addition, roof pressure mainly periodically appears in two directions along the trend and the dip.展开更多
According to the characteristics of ecosystem and concept of the ecosystem in mining area, the index system of the ecosystem health in mining area was set up, and the evaluation standard was established. Aiming at the...According to the characteristics of ecosystem and concept of the ecosystem in mining area, the index system of the ecosystem health in mining area was set up, and the evaluation standard was established. Aiming at the complexion in which the information lost in index ration, the matter element method was put forward to evaluate the ecosystem health in mining area. Making use of the model set up, the weight was built up by the method of index number heavy, the matter element, clas- sical field, and limit field were set up. The rating hierarchy was calculated by relating function. As a case study in the mining area of Pingyangsi Town, the results show that the ecosystem is good and sustainable from 2003 to 2006, but the healthy degree is not high, and some indexes have depravation.展开更多
Global value chains(GVCs)have entered a new stage of restructuring characterized by trends towards localization,regionalization and diversification.These trends can be attributed to the evolution of the international ...Global value chains(GVCs)have entered a new stage of restructuring characterized by trends towards localization,regionalization and diversification.These trends can be attributed to the evolution of the international division,irrational responses to crisis shocks,and trade protectionism.In this context,China’s industrial and supply chain upgrades face both opportunities and challenges which require navigating the adverse effects of industrial re-shoring,unfair technology competition,and changes in the global industrial layout.Yet,such challenges may create pressures for China to accelerate innovation,overcome the low-end lock-up effect by creating regional value chains,and broaden international cooperation.China needs to explore an effective strategy to defuse risks and seize opportunities.On one hand,China should influence the restructuring of GVCs evolution and strengthen its supply chains by playing an active role in economic globalization and the international division.On the other hand,China should proactively respond to GVCs restructuring amid rising trade protectionism,defuse risks from trade protectionism by opening wider to the outside world,and strive to upgrade industrial and supply chains while enhancing the security and stability of their nation.展开更多
Soil depth generally varies in mountainous regions in rather complex ways.Conventional soil survey methods for evaluating the soil depth in mountainous and hilly regions require a lot of time,effort and consequently r...Soil depth generally varies in mountainous regions in rather complex ways.Conventional soil survey methods for evaluating the soil depth in mountainous and hilly regions require a lot of time,effort and consequently relatively large budget to perform.This study was conducted to explore the relationships between soil depth and topographic attributes in a hilly region in western Iran.For this,one hundred sampling points were selected using randomly stratified methodology,and considering all geomorphic surfaces including summit,shoulder,backslope,footslope and toeslope;and soil depth was actually measured.Eleven primary and secondary topographic attributes were derived from the digital elevation model(DEM) at the study area.The result of multiple linear regression indicated that slope,wetness index,catchment area and sediment transport index,which were included in the model,could explain about 76 % of total variability in soil depth at the selected site.This proposed approach may be applicable to other hilly regions in the semi-arid areas at a larger scale.展开更多
The subsidence of the mining area was monitored by analyzing the phase of permanent scatters (PS) which maintained high coherence in magnitude of SAR images.A hew method of spatial unwrapping was presented which use...The subsidence of the mining area was monitored by analyzing the phase of permanent scatters (PS) which maintained high coherence in magnitude of SAR images.A hew method of spatial unwrapping was presented which used the subsidence rates calculated on comer reflector (CR) points as constraints for PS network to perform the spatial unwrapping using the parametric adjustment method.The algorithm achieved the integration of CR data and PSInSAR algorithm.The colliery dense distributed area around Baisha reservoir was chosen as the study area in the experiment.The time series of subsidence from February in 2007 to February in 2010 is successfully inversed by using the periodic function to simulate the linear and nonlinear components of the deformation.The simulation results show that the accuracy can be ± 2.1 mm with the leveling data being used as the external validation data.展开更多
文摘Heat and mass transfer of a circular-shaped porous moist object inside a two-dimensional triangle cavity is investigated by using finite element method.The porous object is considered to be a moist food sample,located in the middle of the cavity with inlet and outlet ports with different configurations of inlet/outlet ports.Convective drying performance is numerically assessed for different values of Reynolds numbers(between 50 and 250),dry air inlet temperature(between 40 and 80℃)and different locations of the port.It is observed that changing the port locations has significant impacts on the flow recirculaitons inside the triangular chamber while convective drying performance is highly affected.The moisture content reduces with longer time and for higher Reynolds number(Re)values.Case P4 where inlet and outlet ports are in the middle of the walls provides the most effective configuration in terms of convective drying performance while the worst case is seen for P1 case where inlet and outlet are closer to the corners of the chamber.There is a 192% difference between the moisture reduction of these two cases at Re=250,T=80℃ and t=120 min.
基金The National Natural Science Foundation of China(No.51408190)
文摘Abstract: With a determinate danger zone and evacuation demand caused by an emergency, an optimization method for the evacuation zone with network reconfiguration based on dynamic simulation is proposed. The method contains three modules. First, the network in the evacuation zone is optimized by a model with the integrated strategy of lane reversal and intersection conflict elimination. Secondly, the dynamic evacuation simulation model based on the cell transmission model is applied to simulate the dynamic propagation process of evacuated vehicles in the network in the evacuation zone. The evacuation time for all evacuated vehicles leaving the danger zone is obtained and the setting of the current evacuation zone is fed back. Thirdly, the arrival distributions of evacuated vehicles at critical intersections of the evacuation zone are also obtained to estimate the delay at critical intersection to determine whether the intersection should be taken as the critical intersection in the next iteration. The evacuation zone is expanded gradually through iteration, and the reasonable evacuation zone and the optimal evacuation network is confirmed. Based on the survey of the parking lot and urban street network around Nanjing Olympic Sports Center, the models and the iterative algorithm were applied to obtain the optimal plan of the evacuation zone with network reconfiguration in an evacuation situation to verify the validity of the proposed method.
文摘Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflora composed of diverse prokaryotic and possible eukaryotic microbes. Macroscopic algae have also been found. This Formation provides important paleobiological information from which to assess status of Mesoproterozoic life, and to evaluate paleoenvironmental conditions and pre-Phanerozoic biostratigraphy. The Gaoyuzhuang Formation has yielded over 100 taxa described by over 10 investigators. Most of the microbial taxa can be divided into three different assemblages according to their paleobiological and paleoenvironmental characteristics. I. The oscillatoriacean/chroococcacean assemblage which occurs in the first member of the Formation and this is interpreted to represent an assemblage from shallow water mat-building and mat-dwelling taxa with some possible planktonic taxa; 2. the nostocacean assemblage found only in the second member, and includes benthic mat-building or mat-dwelling taxa; and 3. the chroococcacean assemblage of the fourth member, which represents intertidal to supratidal mat-building and allochthonous taxa. Proterozoic microfossils found in chert, especially cyanobacteria, are possibly more valuable as paleoenvironmental indicators than as chronostratigraphic tools because of their morphological conservation, although trends in diversity appear to exist for cyanobacteria in the Proterozoic. The general characteristics of Gaoyuzhuang microfossils, and the fact that most nostocacean chains occur and are. preserved with the chain perpendicular to bedding indicate that: (1) the individual size of Gaoyuzhuang microfossils are part of a general trend of increase with time; (2) Gaoyuzhuang deposits are possibly in a fresh water environment and the rate of sedimentation might be equal to or less than the microbial growth rate; (3) the sedimentary model of Gaoyuzhuang might be from intertidal to subtidal or deep sea, and then to intertidal or supratidal; and (4) the eukaryotic organisms had densely occurred when Gaoyuzhuang Formation deposited.
基金Project (2008629045) supported by the China Scholarship Council (Constructing High-Level University Project)
文摘Floating zone method with optical radiation heating was applied to growing a class of R2PdSi3(R=Pr,Tb and Gd) single crystals due to its containerless melting and high stability of the floating zone.One serious problem during the single crystal growth,precipitates of secondary phases,was discussed from the following four parts:precipitates from the raw materials and preparation process,precipitates formed during the growing process,precipitates in the melts and precipitates in the grown crystals.Annealing treatment and composition shift can effectively reduce the precipitates which are not formed during the crystallization but precipitated on post-solidification cooling from the as-grown crystal matrix because of the retrograde solubility of Si.
基金The National Natural Science Foundation of China(No60496311)
文摘A remote antenna unit (RAU) selection model is presented, and two kinds of handoffs, intra-cell handoff (HO) and inter-cell HO, are defined in distributed mobile communications systems (DAS). After that, an inter-cell HO model is proposed, in which the average power of the active set (AS) is used to predict the position of the mobile station (MS). The total power of the AS and the handoff set (HOS) are utilized to determine whether an inter-cell HO is necessary. Furthermore, the relationship between HO parameters and performance metrics is studied in detail based on RAU selection. Simulation results show that both the intra-cell HO and the inter-cell HO can achieve oerfect performance by aoprooriate settings of HO parameters.
文摘X-ray microanalysis was used to study the elemental composition of the shell of the freshwater testate amoeba Difflugia tuberspinifera Hu et al.,1997 collected from Mulan Lake,Hubei province,China in July 2003.The results show that the shell is composed of ten elements:Si in greater quantity;then Ca and Al;and traces of K,Na,Cl,Fe,Mg,S and P.The analysis of results suggests that D.tuberspinifera in elemental composition appears to occupy a middle position between marine and soil testate amoebae.
基金Project(2011CB605503)supported by the National Basic Research Program of China
文摘The oxidation behavior of Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys at 800 °C for exposure time up to 100 h was examined. It is shown that oxidation rate of experimental alloys obeys the parabolic kinetics. Ti?22Al?26Nb?1Zr alloy demonstrates more excellent oxidation resistance than the other two alloys. The main oxidation products are TiO2, Al2O3 and AlNbO4 phases for all these alloys. For the Ti?22Al?26Nb?1Zr alloy, Zr addition can modify the growth mechanism of oxide scale, which can effectively hinder the diffusion of oxygen. Whereas, reaction of Zr with oxygen leads to the formation of ZrO2 precipitates for the Ti?22Al?21Nb?6Zr alloy, which promotes the oxygen ingress into the substrate. Meanwhile, oxidation affected zones, including internal-oxidation layer and oxygen-enriched zone, are present beneath the outmost oxide scale. The difference in these zones is derived from the phase constitution in the starting Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys.
文摘The effect of the local hard zone (LHZ) distributed in the coarse grained HAZ (CGHAZ) has been analyzed by 2-dimensional FEM on a mechanical model of the weld CGHAZ. The existence of the LHZ elevates considerably the stress in LHZ and causes the discontinuity of strain at the boundary between the LHZ and the matrix. The stress distribution in the LHZ is strongly affected by the shape of the LHZ. In a slender LHZ almost the whole region in the LHZ is exposed to elevated stress, whereas in the massive LHZ only the edge region sustains high stress. The longer the LHZ becomes, the more the highly stressed area, and the peak stress in the LHZ grows even under the same volume fraction of the LHZ. These results indicate that the slender LHZ brings about unstable fracture at a lower load level than the blocky LHZ. This tendency was confirmed by CTOD test results on the weld CGHAZ of a high-strength steel. The CGHAZ with elongated M-A constituents fractures at apparently lower critical CTOD than the CGHAZ with massive M-A constituents. In conclusion, the control of the shape of the M-A constituent has a striking effect on the toughness improvement of CGHAZ.
基金National Natural Science Foundation of China (31171082)Natural Science Foundation of Anhui Province (070413138)Key Research Foundation of Anhui Province Education Department (KJ2009A167)
文摘Psychophysical studies suggest that lateral extrastriate visual cortical areas in cats may mediate the sparing of vision largely by network reorganization following lesions of early visual cortical areas. To date, however, there is little direct physiological evidence to support this hypothesis. Using in vivo single-anit recording techniques, we examined the response of neurons in areas 19, 21, and 20 to different types of visual stimulation in cats with or without acute bilateral lesions in areas 17 and 18. Our results showed that, relative to the controls, acute lesions inactivated the response of 99.3% of neurons to moving gratings and 93% of neurons to flickering square stimuli'in areas 19, 21, and 20. These results indicated that acute lesions of primary visual areas in adult eats may impair most visual abilities. Sparing of vision in cats with neonatal lesions in early visual cortical areas may result largely from a postoperative reorganization of visual pathways from subcortical nucleus to extrastriate visual cortical areas.
文摘This paper discusses a fictitious domain method for the linear Dirichlet problem and its applications to the generalized Stokes problem. This method treats Dirichlet boundary condit ion via a Lagrange multiplier technique and is well suited to the no-slip bound ary condition in viscous flow problems. In order to improve the accuracy of solu tions, meshes are refined according to the a posteriori error estimate. The mini -element discretization is applied to solve the generalized Stokes problem. Fin ally, some numerical results to validate this method are presented for partial d ifferential equations with Dirichlet boundary condition.
基金supported by the Science Foundation of Nanjing University of Information Science and Technology,China(No.20080328)the National Key Technology R&D Program (No.2006BAK21B02)+1 种基金the National Key Basic Research Program (973 Program) of China (No.2003CB415201)the National Natural Science Foundation of China (No.40671016)
文摘Trace element(TE) and rare earth element(REE) contents in red soils from the Dongting Lake area of China were determined to understanding the provenance and weathering characteristics of the red soils.The results showed similar REE distribution patterns among red soils from the Dongting Lake area,Xiashu loess from Zhenjiang,loess and Pliocene red soil from the Loess Plateau.These patterns implied a similar provenance from dust-storms,except for red soil R5 which formed by bedrock weathering and had significant light REE(LREE) enrichment and heavy REE(HREE) depletion due to longer weathering periods and higher intensity of weathering.Trace element,especially the Rb/Sr and Li/Ba ratios,and REE,especially the LREE/HREE ratio and δEu could trace weathering intensity.Higher Rb/Sr,Li/Ba,and LREE/HREE ratios and negative Eu anomalies were present in the red soils from the Dongting Lake area.The weathering intensity was in the decreasing order of R5 in the Dongting Lake area > red soils from the Dongting Lake area(including reticulate red soil,weak reticulate red soil,and homogeneous red soil formed by dust storms) > Xiashu loess from Zhenjiang > loess-paleosol and Pliocene red soil from the Loess Plateau.Variations in the TE and REE contents of soil could be effectively used to study the provenance and the weathering intensity.
基金Supported by the Scientific Research Business of China University of Mining & Technology (Beijing) (2009QZ04) the National Natural Science Foundation of China (50974123)
文摘Taking Adaohai Coal Mine as the example, underground pressure appearance laws of fully mechanized top coal slice caving on high-dipping and thick coal seams. Through site visit, theoretical analysis and discrete element calculation, the research shows that, as the mining deepens, underground stress of lower sublevels is more obvious and higher than that of upper sublevels and is higher in the air return roadway than that in the air intake roadway in the area that is near to the top coal. Because the top coal is thick and gangue is caved above the support, underground pressure to the working face is relatively gentle. Immediate roof will mainly fall down along the floor. Main roof and the rock bed above the main roof will move to the mined out area along the fault in the early stage and then fall down with the mined out area later. In addition, roof pressure mainly periodically appears in two directions along the trend and the dip.
文摘According to the characteristics of ecosystem and concept of the ecosystem in mining area, the index system of the ecosystem health in mining area was set up, and the evaluation standard was established. Aiming at the complexion in which the information lost in index ration, the matter element method was put forward to evaluate the ecosystem health in mining area. Making use of the model set up, the weight was built up by the method of index number heavy, the matter element, clas- sical field, and limit field were set up. The rating hierarchy was calculated by relating function. As a case study in the mining area of Pingyangsi Town, the results show that the ecosystem is good and sustainable from 2003 to 2006, but the healthy degree is not high, and some indexes have depravation.
文摘Global value chains(GVCs)have entered a new stage of restructuring characterized by trends towards localization,regionalization and diversification.These trends can be attributed to the evolution of the international division,irrational responses to crisis shocks,and trade protectionism.In this context,China’s industrial and supply chain upgrades face both opportunities and challenges which require navigating the adverse effects of industrial re-shoring,unfair technology competition,and changes in the global industrial layout.Yet,such challenges may create pressures for China to accelerate innovation,overcome the low-end lock-up effect by creating regional value chains,and broaden international cooperation.China needs to explore an effective strategy to defuse risks and seize opportunities.On one hand,China should influence the restructuring of GVCs evolution and strengthen its supply chains by playing an active role in economic globalization and the international division.On the other hand,China should proactively respond to GVCs restructuring amid rising trade protectionism,defuse risks from trade protectionism by opening wider to the outside world,and strive to upgrade industrial and supply chains while enhancing the security and stability of their nation.
文摘Soil depth generally varies in mountainous regions in rather complex ways.Conventional soil survey methods for evaluating the soil depth in mountainous and hilly regions require a lot of time,effort and consequently relatively large budget to perform.This study was conducted to explore the relationships between soil depth and topographic attributes in a hilly region in western Iran.For this,one hundred sampling points were selected using randomly stratified methodology,and considering all geomorphic surfaces including summit,shoulder,backslope,footslope and toeslope;and soil depth was actually measured.Eleven primary and secondary topographic attributes were derived from the digital elevation model(DEM) at the study area.The result of multiple linear regression indicated that slope,wetness index,catchment area and sediment transport index,which were included in the model,could explain about 76 % of total variability in soil depth at the selected site.This proposed approach may be applicable to other hilly regions in the semi-arid areas at a larger scale.
基金Project(2006AA12Z156)supported by the National High Technology Research and Development Program of ChinaProjects(40974006,40774003)supported by the National Natural Science Foundation of China+1 种基金Project supported by Construct Program of the Key Discipline in Hunan Province,ChinaProjects(2011GK3106,2011SK3077)supported by Science and Technology Department of Hunan Province,China
文摘The subsidence of the mining area was monitored by analyzing the phase of permanent scatters (PS) which maintained high coherence in magnitude of SAR images.A hew method of spatial unwrapping was presented which used the subsidence rates calculated on comer reflector (CR) points as constraints for PS network to perform the spatial unwrapping using the parametric adjustment method.The algorithm achieved the integration of CR data and PSInSAR algorithm.The colliery dense distributed area around Baisha reservoir was chosen as the study area in the experiment.The time series of subsidence from February in 2007 to February in 2010 is successfully inversed by using the periodic function to simulate the linear and nonlinear components of the deformation.The simulation results show that the accuracy can be ± 2.1 mm with the leveling data being used as the external validation data.