The STAR experiment at the top RHIC energy has observed that the directed flow(v_(1))of inclusive light hadrons is independent of the collision system size at a given centrality[1].However,recent STAR measurements ind...The STAR experiment at the top RHIC energy has observed that the directed flow(v_(1))of inclusive light hadrons is independent of the collision system size at a given centrality[1].However,recent STAR measurements indicate a system-size dependence in the v_(1)(y)-slope(dv_(1)/dy)of protons,antiprotons,and their differences(Δdv_(1)/dy)at a given centrality,suggesting a potential influence of baryon production and transport mechanisms[2].In this study,we analyzed pseudorapidity(dN/dy)distributions and directed flow(v_(1)and dv_(1)/dy)for pions,kaons,and protons in Au+Au and Cu+Cu collisions at√S_(NN)=19.6 GeV using A Multi-Phase Transport(AMPT)model.Specifically,we investigated the influence of string junction parameters in the AMPT model via the PYTHIA/JET-SET routines,focusing on the popcorn mechanism and string-splitting parameters,on d N/dy,dv_(1)/dy,and their charge-dependent splittings(Δd N/dy andΔdv_(1)/dy).We observed that string junction parameters can affect d N/dy,dv_(1)/dy,Δd N/dy,andΔdv_(1)/dy forπ,K,and p,and influence their system-size dependence.The effect is most prominent on the v_(1)value of protons and non-trivial for kaons;the v_(1)value of pions remains largely unchanged.These findings provide insights into the interplay among particle production mechanisms,baryon transport,and directed flow in heavy-ion collisions.展开更多
The influence of the density-dependent symmetry energy on the balance energy （Ebal） of directed flow from heavy ion collisions （HICs） at incident energies covered by INDRA and MSU experiments is studied, using the...The influence of the density-dependent symmetry energy on the balance energy （Ebal） of directed flow from heavy ion collisions （HICs） at incident energies covered by INDRA and MSU experiments is studied, using the updated version of the ultra- relativistic quantum molecular dynamics （UrQMD） model, especially adapted to low-energy heavy ion collisions （HICs）. Four mass-symmetric reactions with total mass numbers between 192 and 394 are chosen for investigating the influence of the symmetry energy on the system-mass dependence of Eual. The results show that the uncertainty in the density dependence of the symmetry potential causes changes of Ebal of the order of several MeV, depending on the type of particle considered. The Ebal of neutrons from HICs is particularly sensitive to the density dependence of the symmetry potential energy, while the system-mass dependence of EbaI of Z = 1 particles is not.展开更多
Using a(3+1)-D hydrodynamic model,CLVisc,we study the directed flow(vi)of light hadrons pro-duced in Au+Au,Ru+Ru,and Zr+Zr collisions at √SNN=200 GeV.The evolution of tilted energy density,pres-sure gradient,and radi...Using a(3+1)-D hydrodynamic model,CLVisc,we study the directed flow(vi)of light hadrons pro-duced in Au+Au,Ru+Ru,and Zr+Zr collisions at √SNN=200 GeV.The evolution of tilted energy density,pres-sure gradient,and radial flow along the x-direction is systematically investigated.The counter-clockwise tilt of the initial fireball is shown to be a vital source of directed flow for final light hadrons.A good description of directed flow is provided for light hadrons in central and mid-central Au+Au and isobar collisions at the RHIC.Our numeric-al results show a clear system size dependence for light hadron Vi across different collision systems.We further study the effect of nuclear structure on the directed flow and find that v1 for light hadrons is insensitive to nuclei with quadrupole deformation.展开更多
The yield ratios of neutron/proton and ^3H/^3He and the directed flow per nucleon for these projectile-like fragments at large impact parameters are studied for ^50Ca ＋ ^40Ca and ^50Cr ＋ ^40Ca for comparison at 50 M...The yield ratios of neutron/proton and ^3H/^3He and the directed flow per nucleon for these projectile-like fragments at large impact parameters are studied for ^50Ca ＋ ^40Ca and ^50Cr ＋ ^40Ca for comparison at 50 MeV/u using the isospin-dependent quantum molecular dynamics（IQMD model.It is found that the yield ratios and the directed flows per nucleon are different for reactions induced by the neutron-rich nucleus ^50Ca and the stable isobaric nucleus ^50Cr,and depend on the hardness of the EOS.The ratios of neutron/proton and ^3H/^3He and the difference of directed flow per nucleon of neutron-proton are suggested to be possible observables to investigate the isospin effects.展开更多
Suffusion is the process defined as the migration of relatively small soil particles through the pores of a soil matrix composed of relatively large particles,driven by substantial hydrodynamic forces and weak attract...Suffusion is the process defined as the migration of relatively small soil particles through the pores of a soil matrix composed of relatively large particles,driven by substantial hydrodynamic forces and weak attraction energies.This study investigates the influence of flow direction(upward and downward)on suffusion induced by interaction energies in sand-clay mixtures under both saturated and unsaturated conditions.The impact of clay mineralogy(kaolinite,illite,and montmorillonite),sand-grain size,and ionic concentration(IC)gradient were discussed based on the observed breakthrough curves(BTCs)and relative saturation rate(Sr)during injection(particularly for unsaturated conditions).Under saturated conditions,higher susceptibility to suffusion was observed in sand-kaolinite and sand-illite mixtures under downward flow compared to upward flow,whereas the suffusion of montmorillonite was more significant under upward flow than under downward flow.In contrast,for unsaturated conditions,more substantial suffusion of kaolinite and illite particles occurred under upward flow compared to downward flow,whereas the opposite trend was observed in sand-montmorillonite mixtures.In addition,the impact of sand-grain size(or the size ratio between sand and clay)on the suffusion of kaolinite and illite under unsaturated conditions suggests a reduced size ratio that leads to relatively significant suffusion under downward flow compared to upward flow.The findings presented in this study contribute to a comprehensive understanding of the influence of flow direction on suffusion in sand-clay mixtures under both saturated and unsaturated conditions.展开更多
The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-m...The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-middle Miocene deformed rocks of the inter-Andean valley between the Western and Central Cordilleras of Colombia.However,uncertainty remains about the age of the latest accretionary phases of the Panama-ChocóBlock.Poorly studied late Miocene volcanic rocks within the northern inter-Andean valley may provide key information to constrain the temporality of that final collision.Here,we study the deformational features of the~12-6 Ma extrusive rocks of the Combia Volcanic Province located in the northwestern Andes(Colombia).We present anisotropy of magnetic susceptibility(AMS)data for pyroclastic and volcanic rocks within the AmagáBasin,an inter-Andean depression with Oligocene-middle Miocene sedimentary rocks that recorded NW-SE compression and NE-SW simple shear caused by the Panama-ChocóBlock collision.We identified that the magnetic fabrics of the extrusive rocks of the Combia Volcanic Province reveal flow directions that indicate the occurrence of ancient volcanoes in the central axis of the AmagáBasin.Some of these fabrics do not contain any deformational features,whereas others record the same structural regime as the Oligocene-middle Miocene sedimentary rocks.We infer that variations in the intensity of the deformation promoted late Miocene local fault reactivations that,in contrast to the Oligocene-middle Miocene deformational events,did not affect the entire AmagáBasin.Age differences among the studied sections can also explain the different deformational patterns identified in the basin.Both interpretations suggest that the most significant collisional events of the Panama-ChocóBlock occurred in the Oligocene-middle Miocene,whereas the formation of the Combia Volcanic Province may have either followed or coincided with the latest stages of the accretion.展开更多
The piezoelectric pump with nozzle/diffuser-elements, which oscillating formdiffering from regular volumetric reciprocating or rotating pumps because there arenozzle/diffuser-elements substituted for regular valves, i...The piezoelectric pump with nozzle/diffuser-elements, which oscillating formdiffering from regular volumetric reciprocating or rotating pumps because there arenozzle/diffuser-elements substituted for regular valves, is a new type pump whose actuator is apiezoelectric ceramal part with verse piezoelectric effect In recent year, piezoelectric pump ispaid increasing attention to because it is an ideal candidate in application in such area as medicalhealth, mechanical tools and micro-mechanism. The fundamental research on it, however, is still notmade through. Focuses on the phenomenon of different directions of flow among Germany pump, Chinesepump and Swiss pump, which are all fitted with nozzle/diffuser-elements, and analyzes the coneangle of nozzle/diffuser-elements based on the flow equation of valve-less piezoelectric pump withnozzle/diffuser-elements. As a result, the concepts of diffuser toss coefficient and losscoefficient are introduced to explain these phenomena, from which a discussion is given on theoptimization of the cone angle of nozzle/diffuser-element aiming at the maximum of pump flow.展开更多
An experimental analysis on the subsequent yield-surfaces evolution using multiple specimens is presented for a 45 steel after a prescribed pre-strain loading in three different directions respectively, and the yieldi...An experimental analysis on the subsequent yield-surfaces evolution using multiple specimens is presented for a 45 steel after a prescribed pre-strain loading in three different directions respectively, and the yielding is defined by a designated offsetting strain. The size of the subsequent yield surface is found smaller than the initial yield surface; the negative cross effects are observed in the normal loading direction, its shape is not a Mises circle but has a rather blunt nose in loading direction and flat in the opposite. These results strongly depend on the loading path and the prescribed offset plastic strain. The plastic flow direction to the subsequent yield surface is investigated, and it is found that the plastic flow direction deviates from the normal flow rule. The deviation differs from preloading case to preloading case. And the plastic flow direction would have a larger deviation from the normal of the yield surface, if the subsequent yield was defined by a smaller offset strain. Furthermore, the experiments are simulated using the Chaboche model, and the results show that it can rationally predict yield-surface only when yield is defined by a fairly large offset strain.展开更多
Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing concern.Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment.However,e...Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing concern.Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment.However,ephemeral gully mapping remains a challenge.In this study,we proposed a flow-directional detection for identifying ephemeral gullies from high-resolution images and digital elevation models(DEMs).Ephemeral gullies exhibit clear linear features in high-resolution images.An edge detection operator was initially used to identify linear features from high-resolution images.Then,according to gully erosion mechanism,the flow-directional detection was designed.Edge images obtained from edge detection and flow directions obtained from DEMs were used to implement the flow-directional detection that detects ephemeral gullies along the flow direction.Results from ten study areas in the Loess Plateau of China showed that ranges of precision,recall,and Fmeasure are 6 o.66%-90.47%,65.74%-94.98%,and63.10%-91.93%,respectively.The proposed method is flexible and can be used with various images and DEMs.However,analysis of the effect of DEM resolution and accuracy showed that DEM resolution only demonstrates a minor effect on the detection results.Conversely,DEM accuracy influences the detection result and is more important than the DEM resolution.The worse the vertical accuracy of DEM,the lower the performance of the flow-directional detection will be.This work is beneficial to research related to monitoring gully erosion and assessing soil loss.展开更多
BACKGROUND：Neuro-rehabilitative training has been shown to promote motor function recovery in stroke patients,although the underlying mechanisms have not been fully clarified.OBJECTIVE：To investigate the effects of ...BACKGROUND：Neuro-rehabilitative training has been shown to promote motor function recovery in stroke patients,although the underlying mechanisms have not been fully clarified.OBJECTIVE：To investigate the effects of finger movement training on functional connectivity and information flow direction in cerebral motor areas of healthy people using electroencephalogram （EEG）.DESIGN,TIME AND SETTING：A self-controlled,observational study was performed at the College of Life Science and Bioengineering,Beijing University of Technology between December 2008 and April 2009.PARTICIPANTS：Nineteen healthy adults,who seldom played musical instruments or keyboards,were included in the present study.METHODS：Specific finger movement training was performed,and all subjects were asked to separately press keys with their left or right hand fingers,according to instructions.The task comprised five sessions of test train test train-test.Thirty-six channel EEG signals were recorded in different test sessions prior to and after training.Data were statistically analyzed using one-way analysis of variance.MAIN OUTCOME MEASURES：The number of effective performances,correct ratio,average response time,average movement time,correlation coefficient between pairs of EEG channels,and information flow direction in motor regions were analyzed and compared between different training sessions.RESULTS：Motor function of all subjects was significantly improved in the third test comparedwith the first test （P〈 0.01）.More than 80% of connections were strengthened in the motor-related areas following two training sessions,in particular the primary motor regions under the C4 electrode.Compared to the first test,a greater amount of information flowed from the Cz and Fcz electrodes （corresponding to supplementary motor area） to the C4 electrode in the third test.CONCLUSION：Finger task training increased motor ability in subjects by strengthening connections and changing information flow in the motor areas.These results provided a greater understanding of the mechanisms involved in motor rehabilitation.展开更多
Digital elevation models （DEMs） are widely used to define the flow direction in distributed hydrological models for simulation of streamflow. In recent decades, numerous methods for flow direction determination have...Digital elevation models （DEMs） are widely used to define the flow direction in distributed hydrological models for simulation of streamflow. In recent decades, numerous methods for flow direction determination have been applied successfully to mountainous regions. Nevertheless, some problems still exist when those methods are used for flat or gently sloped areas The present study reviews the conventional methods of determining flow direction for such landscapes and analyzes the problems of these methods. Two different methods of determining flow direction are discussed and were applied to the Xitiaoxi Catchment, located in the Taihu Basin in southern China, which has both mountainous and flat terrain. Both the agree method and the shortest path method use drainage networks derived from a remote sensing image to determine the correct location of the stream. The results indicate that the agree method provides a better fit with the DEM for the hilly region than the shortest path method. For the flat region where the flow has been diverted and rerouted by land managers, both methods require observation of the drainage network to determine the flow direction. In order to clarify the applicability of the two methods, both are employed in catchment hydrological models conceptually based on the Xinanjiang model and implemented with PCRaster. The simulation results show that both methods can be successfully applied in hydrological modeling. There are no evident differences in the modeled discharge when using the two methods at different spatial scales.展开更多
Traffic flow prediction plays an important role in intelligent transportation systems and is of great significance in the applications of traffic control and urban planning.Due to the complexity of road traffic flow d...Traffic flow prediction plays an important role in intelligent transportation systems and is of great significance in the applications of traffic control and urban planning.Due to the complexity of road traffic flow data,traffic flow prediction has been one of the challenging tasks to fully exploit the spatiotemporal characteristics of roads to improve prediction accuracy.In this study,a combined flow direction level traffic flow prediction graph convolutional network(GCN)and long short-term memory(LSTM)model based on spatiotemporal characteristics is proposed.First,a GCN model is employed to capture the topological structure of the data graph and extract the spatial features of road networks.Additionally,due to the capability to handle long-term dependencies,the longterm memory is used to predict the time series of traffic flow and extract the time features.The proposed model is evaluated using real-world data,which are obtained from the intersection of Liuquan Road and Zhongrun Avenue in the Zibo High-Tech Zone of China.The results show that the developed combined GCNLSTM flow direction level traffic flow prediction model can perform better than the single models of the LSTM model and GCN model,and the combined ARIMA-LSTM model in traffic flow has a strong spatiotemporal correlation.展开更多
Differential and integrated directed flow and elliptic flow of light charged particles （z ≤ 2） are studied systematically for semi-central （b = 5 fm） 197Au＋197Au collisions at incident energies from 25 to 250 Me...Differential and integrated directed flow and elliptic flow of light charged particles （z ≤ 2） are studied systematically for semi-central （b = 5 fm） 197Au＋197Au collisions at incident energies from 25 to 250 MeV/nucleon by the isospin-dependent quantum molecular dynamics model. The changes of directed and elliptic flow with incident energy reflect the dynamic competition between mean field and nucleon-nucleon collisions and also between collective rotation and expansion.展开更多
In order to decrease the anisotropy of mechanical properties, the rigid-plastic mechanical model for the forging method with horizontal V-shaped anvil is presented. The forging method, through the change of anvils sha...In order to decrease the anisotropy of mechanical properties, the rigid-plastic mechanical model for the forging method with horizontal V-shaped anvil is presented. The forging method, through the change of anvils shape, is able to control fibrous tissue direction, to improve the anisotropy of mechanical properties of axial forgings, to realize uniform forging. Therefore, the forging method can overcome the defect that conventional forging methods produce. The mechanism of the forging method with horizontal V-shaped anvil and the process of metal deformation are analyzed. The agreement of theoretical analysis with experimental study verifies the fact that the forging method with horizontal V-shaped anvil can control effectively the mechanical properties of axial forgings.展开更多
A new algorithm to automatically extract drainage networks and catchments based on triangulation irregular networks(TINs) digital elevation model(DEM) was developed. The flow direction in this approach is determined b...A new algorithm to automatically extract drainage networks and catchments based on triangulation irregular networks(TINs) digital elevation model(DEM) was developed. The flow direction in this approach is determined by computing the spatial gradient of triangle and triangle edges. Outflow edge was defined by comparing the contribution area that is separated by the steepest descent of the triangle. Local channels were then tracked to build drainage networks. Both triangle edges and facets were considered to construct flow path. The algorithm has been tested in the site for Hawaiian Island of Kaho'olawe, and the results were compared with those calculated by ARCGIS as well as terrain map. The reported algorithm has been proved to be a reliable approach with high efficiency to generate well-connected and coherent drainage networks.展开更多
There are many motors in operation or on standby in nuclear power plants,and the startup of group motors will have a great impact on the voltage of the emergency bus.At present,there is no special or inexpensive softw...There are many motors in operation or on standby in nuclear power plants,and the startup of group motors will have a great impact on the voltage of the emergency bus.At present,there is no special or inexpensive software to solve this problem,and the experience of engineers is not accurate enough.Therefore,this paper developed a method and system for the startup calculation of group motors in nuclear power plants and proposed an automatic generation method of circuit topology in nuclear power plants.Each component in the topology was given its unique number,and the component class could be constructed according to its type and upper and lower connections.The subordination and topology relationship of switches,buses,and motors could be quickly generated by the program according to the component class,and the simplified direct power flow algorithm was used to calculate the power flow for the startup of group motors according to the above relationship.Then,whether the bus voltage is in the safe range and whether the voltage exceeds the limit during the startup of the group motor could be judged.The practical example was used to verify the effectiveness of the method.Compared with other professional software,the method has high efficiency and low cost.展开更多
Although several studies have assessed the effects of thinning on water quality,including nitrogen(N)exports,few have examined N-saturated plantations.This study assessed the short-term effect of thinning on N exports...Although several studies have assessed the effects of thinning on water quality,including nitrogen(N)exports,few have examined N-saturated plantations.This study assessed the short-term effect of thinning on N exports from a N-saturated plantation forest in northern Kyushu,western Japan,that was thinned(43%of basal area)during January-March 2012.Water levels at the gauging station were continually measured,and streamwater baseflow and stormflow samples were collected before(2011)and after(2013)forest thinning.Annual precipitation before(2469 mm)and after(2418 mm)forest thinning differed little,and annual water discharge after thinning(1641 mm)was similar to that before thinning(1609 mm).However,direct flow during stormflow periods was higher after thinning(260 mm)than before(153 mm).The concentrations of major ions in stream water did not differ before and after thinning.As a result,the high annual dissolved inorganic N(DIN)exports differed little before(35.8 kg N ha^-1 a^-1)and after(36.5 kg N ha^-1 a^-1)forest thinning.DIN exports during stormflow periods were slightly higher after(12.2 kg N ha^-1 a^-1)than before thinning(10.5 kg N ha^-1 a^-1)and were proportional to the increased direct flow after thinning(561 mm after vs.470 mm before thinning).We concluded that thinning does not affect annual N exports from the N-saturated plantation forest,but it can increase the proportion of N exported during stormflow periods in proportion to increased water volume of direct flow after thinning.展开更多
The wind turbine has the advantage of operating uninterruptedly, which ensures a constant source of electricity. This investigation includes a clear overview of the wind velocity, the flow direction;the amount of ener...The wind turbine has the advantage of operating uninterruptedly, which ensures a constant source of electricity. This investigation includes a clear overview of the wind velocity, the flow direction;the amount of energy reserved, suitable regions for wind turbine installation, etc. The feasibility and possibility of installing a wind energy conversion system for several locations in Bangladesh are analyzed. A brief study of wind characteristics in different locations in Bangladesh is reported. Wind data obtained from the Bangladesh Meteorological Department (BMD) for Mongla, Patuakhali, Kutubdia, and Bhola stations are analyzed through wind rose, frequency distribution, and average wind velocity. The performance of suitable small-scale wind turbines will be assessed in order to confirm the prospect of wind turbines in Bangladesh.展开更多
Direct numerical simulations（DNSs） of purely elastic turbulence in rectilinear shear flows in a three-dimensional（3D） parallel plate channel were carried out,by which numerical databases were established.Based on ...Direct numerical simulations（DNSs） of purely elastic turbulence in rectilinear shear flows in a three-dimensional（3D） parallel plate channel were carried out,by which numerical databases were established.Based on the numerical databases,the present paper analyzed the structural and statistical characteristics of the elastic turbulence including flow patterns,the wall effect on the turbulent kinetic energy spectrum,and the local relationship between the flow motion and the microstructures＇ behavior.Moreover,to address the underlying physical mechanism of elastic turbulence,its generation was presented in terms of the global energy budget.The results showed that the flow structures in elastic turbulence were 3D with spatial scales on the order of the geometrical characteristic length,and vortex tubes were more likely to be embedded in the regions where the polymers were strongly stretched.In addition,the patterns of microstructures＇ elongation behave like a filament.From the results of the turbulent kinetic energy budget,it was found that the continuous energy releasing from the polymers into the main flow was the main source of the generation and maintenance of the elastic turbulent status.展开更多
The Nkoup watershed(10°35’-10°47’E and 5°27’-5°42’N)is a volcanic zone situated in Nun Plain West Cameroon.The high fertility of the soils makes it a strategic agropastoral area where wat...The Nkoup watershed(10°35’-10°47’E and 5°27’-5°42’N)is a volcanic zone situated in Nun Plain West Cameroon.The high fertility of the soils makes it a strategic agropastoral area where water resources are heavily exploited and used for several purposes.Due to human activities,soils and water resources are deteriorating,giving birth to water pollution and hydromorphological hazards.This work aims to determine the hydromorphometric parameters of the Nkoup watershed so that the data obtained help in the sustainable management of water resources and conservation of soil.To achieve this aim,various data were collected from DEM dataset derived from SRTM and processed in specialized software(QGIS and ArGIS).The simplified hydrological balance was calculated using the upstream approach.The Nkoup watershed has:Axial length L_(ax)=25.8 km,Axial Width W_(ax)=11.1 km,Perimeter P=132.6 km,Area A=173.7 km^(2),Average Altitude Ha=1726.3 m,Compactness Index Icomp=2.8,Relief ratio Rr=3.9 m/km,Circularity ratio Rc=0.1,Elongation ratio R=0.1,Drainage texture ratio Rt=0.6,Drainage density Dd=0.5 km/km^(2).Stream Frequency Fs=0.4,Channel Sinuosity Index CSI=0.8,Stream gradient Sg=0.6 and global slope Index Ig=6.8 m/km.The specific height Difference Ds=89.4 m shows moderate relief.The precipitation and evapotranspiration are unevenly distributed.With P=187.7 mm/an,ETP=953.4 mm/an,Q=4.2 m3/s,R=762.5 mm/an,ETR=832.3 mm/an and I=282.9 mm/an.The Nkoup,36.9 km long,has a sinuous aspect due to the low slope and the high CSI.The piezometric levels vary according to the seasons and the groundwater flow follows the N-S direction as surface flow.展开更多
基金Financial assistance from Chinese Academy of Sciences(Grant No.XDB34000000)support from ANSO Scholarship for Young Talents。
文摘The STAR experiment at the top RHIC energy has observed that the directed flow(v_(1))of inclusive light hadrons is independent of the collision system size at a given centrality[1].However,recent STAR measurements indicate a system-size dependence in the v_(1)(y)-slope(dv_(1)/dy)of protons,antiprotons,and their differences(Δdv_(1)/dy)at a given centrality,suggesting a potential influence of baryon production and transport mechanisms[2].In this study,we analyzed pseudorapidity(dN/dy)distributions and directed flow(v_(1)and dv_(1)/dy)for pions,kaons,and protons in Au+Au and Cu+Cu collisions at√S_(NN)=19.6 GeV using A Multi-Phase Transport(AMPT)model.Specifically,we investigated the influence of string junction parameters in the AMPT model via the PYTHIA/JET-SET routines,focusing on the popcorn mechanism and string-splitting parameters,on d N/dy,dv_(1)/dy,and their charge-dependent splittings(Δd N/dy andΔdv_(1)/dy).We observed that string junction parameters can affect d N/dy,dv_(1)/dy,Δd N/dy,andΔdv_(1)/dy forπ,K,and p,and influence their system-size dependence.The effect is most prominent on the v_(1)value of protons and non-trivial for kaons;the v_(1)value of pions remains largely unchanged.These findings provide insights into the interplay among particle production mechanisms,baryon transport,and directed flow in heavy-ion collisions.
基金supported in part by the Key Project of the Ministry of Education of China (Grant No.209053)the National Natural Science Foundation of China (Grant Nos.10905021 and 10979023)+2 种基金the Zhejiang Provincial Natural Science Foundation of China (Grant No.Y6090210)the Qianjiang Talents Project of Zhejiang Province (Grant No.2010R10102)the Department of Education of Liaoning Province (Grant No.L2010521)
文摘The influence of the density-dependent symmetry energy on the balance energy （Ebal） of directed flow from heavy ion collisions （HICs） at incident energies covered by INDRA and MSU experiments is studied, using the updated version of the ultra- relativistic quantum molecular dynamics （UrQMD） model, especially adapted to low-energy heavy ion collisions （HICs）. Four mass-symmetric reactions with total mass numbers between 192 and 394 are chosen for investigating the influence of the symmetry energy on the system-mass dependence of Eual. The results show that the uncertainty in the density dependence of the symmetry potential causes changes of Ebal of the order of several MeV, depending on the type of particle considered. The Ebal of neutrons from HICs is particularly sensitive to the density dependence of the symmetry potential energy, while the system-mass dependence of EbaI of Z = 1 particles is not.
基金Supported by the National Natural Science Foundation of China(NSFC)(11935007)Guangdong Major Project of Basic and Applied Basic Research(2020B0301030008)+2 种基金the Natural Science Foundation of Hubei Province(2021CFB272),the Education Department of Hubei Province of China with Young Talents Project(Q20212703)the Open Foundation of Key Laboratory of Quark and Lepton Physics(MOE)(QLPL202104)the Xiaogan Natural Science Foundation(XGKJ2021010016)。
文摘Using a(3+1)-D hydrodynamic model,CLVisc,we study the directed flow(vi)of light hadrons pro-duced in Au+Au,Ru+Ru,and Zr+Zr collisions at √SNN=200 GeV.The evolution of tilted energy density,pres-sure gradient,and radial flow along the x-direction is systematically investigated.The counter-clockwise tilt of the initial fireball is shown to be a vital source of directed flow for final light hadrons.A good description of directed flow is provided for light hadrons in central and mid-central Au+Au and isobar collisions at the RHIC.Our numeric-al results show a clear system size dependence for light hadron Vi across different collision systems.We further study the effect of nuclear structure on the directed flow and find that v1 for light hadrons is insensitive to nuclei with quadrupole deformation.
基金Supported by National Natural Science Foundation of China(11405025)
文摘The yield ratios of neutron/proton and ^3H/^3He and the directed flow per nucleon for these projectile-like fragments at large impact parameters are studied for ^50Ca ＋ ^40Ca and ^50Cr ＋ ^40Ca for comparison at 50 MeV/u using the isospin-dependent quantum molecular dynamics（IQMD model.It is found that the yield ratios and the directed flows per nucleon are different for reactions induced by the neutron-rich nucleus ^50Ca and the stable isobaric nucleus ^50Cr,and depend on the hardness of the EOS.The ratios of neutron/proton and ^3H/^3He and the difference of directed flow per nucleon of neutron-proton are suggested to be possible observables to investigate the isospin effects.
基金supported by the Korea Agency for Infrastructure Technology Advancement under the Ministry of Land,Infrastructure and Transport (Grant No.RS-2024-00410248)by National Research Foundation of Korea (NRF)grants funded by the Korean government (MSIT) (Grant No.RS-2022R1C1C1007296).
文摘Suffusion is the process defined as the migration of relatively small soil particles through the pores of a soil matrix composed of relatively large particles,driven by substantial hydrodynamic forces and weak attraction energies.This study investigates the influence of flow direction(upward and downward)on suffusion induced by interaction energies in sand-clay mixtures under both saturated and unsaturated conditions.The impact of clay mineralogy(kaolinite,illite,and montmorillonite),sand-grain size,and ionic concentration(IC)gradient were discussed based on the observed breakthrough curves(BTCs)and relative saturation rate(Sr)during injection(particularly for unsaturated conditions).Under saturated conditions,higher susceptibility to suffusion was observed in sand-kaolinite and sand-illite mixtures under downward flow compared to upward flow,whereas the suffusion of montmorillonite was more significant under upward flow than under downward flow.In contrast,for unsaturated conditions,more substantial suffusion of kaolinite and illite particles occurred under upward flow compared to downward flow,whereas the opposite trend was observed in sand-montmorillonite mixtures.In addition,the impact of sand-grain size(or the size ratio between sand and clay)on the suffusion of kaolinite and illite under unsaturated conditions suggests a reduced size ratio that leads to relatively significant suffusion under downward flow compared to upward flow.The findings presented in this study contribute to a comprehensive understanding of the influence of flow direction on suffusion in sand-clay mixtures under both saturated and unsaturated conditions.
基金supported financially by the National Natural Science Foundation of China(Grants W2433104 to V.A.P.and 42225402 to J.L.)the China Postdoctoral Science Foundation(Grant 2024M753205 to V.A.P.)+2 种基金the Institute of Geology and Geophysics of the Chinese Academy of Sciences(International Fellowship for Postdoctoral Researchers,Grant 2025PD02 to V.A.P.)an association between ECOS-NORD(France)and Colciencias/Icetex(Colombia)(Grant C12U01 to M.I.M.)Part of this project was developed under a junior fellowship scheme of Colciencias(Colombia)(Grant 706-2015 to V.A.P.),which also supported the undergraduate final project of A.T.
文摘The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-middle Miocene deformed rocks of the inter-Andean valley between the Western and Central Cordilleras of Colombia.However,uncertainty remains about the age of the latest accretionary phases of the Panama-ChocóBlock.Poorly studied late Miocene volcanic rocks within the northern inter-Andean valley may provide key information to constrain the temporality of that final collision.Here,we study the deformational features of the~12-6 Ma extrusive rocks of the Combia Volcanic Province located in the northwestern Andes(Colombia).We present anisotropy of magnetic susceptibility(AMS)data for pyroclastic and volcanic rocks within the AmagáBasin,an inter-Andean depression with Oligocene-middle Miocene sedimentary rocks that recorded NW-SE compression and NE-SW simple shear caused by the Panama-ChocóBlock collision.We identified that the magnetic fabrics of the extrusive rocks of the Combia Volcanic Province reveal flow directions that indicate the occurrence of ancient volcanoes in the central axis of the AmagáBasin.Some of these fabrics do not contain any deformational features,whereas others record the same structural regime as the Oligocene-middle Miocene sedimentary rocks.We infer that variations in the intensity of the deformation promoted late Miocene local fault reactivations that,in contrast to the Oligocene-middle Miocene deformational events,did not affect the entire AmagáBasin.Age differences among the studied sections can also explain the different deformational patterns identified in the basin.Both interpretations suggest that the most significant collisional events of the Panama-ChocóBlock occurred in the Oligocene-middle Miocene,whereas the formation of the Combia Volcanic Province may have either followed or coincided with the latest stages of the accretion.
基金This project is supported by Municipal Natural Science Foundation of Beiiing , China (No.3032005).
文摘The piezoelectric pump with nozzle/diffuser-elements, which oscillating formdiffering from regular volumetric reciprocating or rotating pumps because there arenozzle/diffuser-elements substituted for regular valves, is a new type pump whose actuator is apiezoelectric ceramal part with verse piezoelectric effect In recent year, piezoelectric pump ispaid increasing attention to because it is an ideal candidate in application in such area as medicalhealth, mechanical tools and micro-mechanism. The fundamental research on it, however, is still notmade through. Focuses on the phenomenon of different directions of flow among Germany pump, Chinesepump and Swiss pump, which are all fitted with nozzle/diffuser-elements, and analyzes the coneangle of nozzle/diffuser-elements based on the flow equation of valve-less piezoelectric pump withnozzle/diffuser-elements. As a result, the concepts of diffuser toss coefficient and losscoefficient are introduced to explain these phenomena, from which a discussion is given on theoptimization of the cone angle of nozzle/diffuser-element aiming at the maximum of pump flow.
基金Project supported by the National Natural Science Foundation of China(Nos.90815001and11072064)Key Project of Guangxi Science and Technology Lab Center(No.LGZX201101)
文摘An experimental analysis on the subsequent yield-surfaces evolution using multiple specimens is presented for a 45 steel after a prescribed pre-strain loading in three different directions respectively, and the yielding is defined by a designated offsetting strain. The size of the subsequent yield surface is found smaller than the initial yield surface; the negative cross effects are observed in the normal loading direction, its shape is not a Mises circle but has a rather blunt nose in loading direction and flat in the opposite. These results strongly depend on the loading path and the prescribed offset plastic strain. The plastic flow direction to the subsequent yield surface is investigated, and it is found that the plastic flow direction deviates from the normal flow rule. The deviation differs from preloading case to preloading case. And the plastic flow direction would have a larger deviation from the normal of the yield surface, if the subsequent yield was defined by a smaller offset strain. Furthermore, the experiments are simulated using the Chaboche model, and the results show that it can rationally predict yield-surface only when yield is defined by a fairly large offset strain.
基金funded by the National Natural Science Foundation of China (Grant No. 41930102, 41971333, 41771415, and 41701449)the Priority Academic Program Development of Jiangsu Higher Education Institutions (Grant No. 164320H116)the Open Fund of Key Laboratory for Synergistic Prevention of Water and Soil Environmental Pollution (Grant No. KLSPWSEPA04)。
文摘Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing concern.Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment.However,ephemeral gully mapping remains a challenge.In this study,we proposed a flow-directional detection for identifying ephemeral gullies from high-resolution images and digital elevation models(DEMs).Ephemeral gullies exhibit clear linear features in high-resolution images.An edge detection operator was initially used to identify linear features from high-resolution images.Then,according to gully erosion mechanism,the flow-directional detection was designed.Edge images obtained from edge detection and flow directions obtained from DEMs were used to implement the flow-directional detection that detects ephemeral gullies along the flow direction.Results from ten study areas in the Loess Plateau of China showed that ranges of precision,recall,and Fmeasure are 6 o.66%-90.47%,65.74%-94.98%,and63.10%-91.93%,respectively.The proposed method is flexible and can be used with various images and DEMs.However,analysis of the effect of DEM resolution and accuracy showed that DEM resolution only demonstrates a minor effect on the detection results.Conversely,DEM accuracy influences the detection result and is more important than the DEM resolution.The worse the vertical accuracy of DEM,the lower the performance of the flow-directional detection will be.This work is beneficial to research related to monitoring gully erosion and assessing soil loss.
基金the National Natural Science Foundation of China,No. 30670543
文摘BACKGROUND：Neuro-rehabilitative training has been shown to promote motor function recovery in stroke patients,although the underlying mechanisms have not been fully clarified.OBJECTIVE：To investigate the effects of finger movement training on functional connectivity and information flow direction in cerebral motor areas of healthy people using electroencephalogram （EEG）.DESIGN,TIME AND SETTING：A self-controlled,observational study was performed at the College of Life Science and Bioengineering,Beijing University of Technology between December 2008 and April 2009.PARTICIPANTS：Nineteen healthy adults,who seldom played musical instruments or keyboards,were included in the present study.METHODS：Specific finger movement training was performed,and all subjects were asked to separately press keys with their left or right hand fingers,according to instructions.The task comprised five sessions of test train test train-test.Thirty-six channel EEG signals were recorded in different test sessions prior to and after training.Data were statistically analyzed using one-way analysis of variance.MAIN OUTCOME MEASURES：The number of effective performances,correct ratio,average response time,average movement time,correlation coefficient between pairs of EEG channels,and information flow direction in motor regions were analyzed and compared between different training sessions.RESULTS：Motor function of all subjects was significantly improved in the third test comparedwith the first test （P〈 0.01）.More than 80% of connections were strengthened in the motor-related areas following two training sessions,in particular the primary motor regions under the C4 electrode.Compared to the first test,a greater amount of information flowed from the Cz and Fcz electrodes （corresponding to supplementary motor area） to the C4 electrode in the third test.CONCLUSION：Finger task training increased motor ability in subjects by strengthening connections and changing information flow in the motor areas.These results provided a greater understanding of the mechanisms involved in motor rehabilitation.
基金supported by the Studies and Research in Sustainability Program (Deutscher Akademischer Austausch Dienst, DAAD)
文摘Digital elevation models （DEMs） are widely used to define the flow direction in distributed hydrological models for simulation of streamflow. In recent decades, numerous methods for flow direction determination have been applied successfully to mountainous regions. Nevertheless, some problems still exist when those methods are used for flat or gently sloped areas The present study reviews the conventional methods of determining flow direction for such landscapes and analyzes the problems of these methods. Two different methods of determining flow direction are discussed and were applied to the Xitiaoxi Catchment, located in the Taihu Basin in southern China, which has both mountainous and flat terrain. Both the agree method and the shortest path method use drainage networks derived from a remote sensing image to determine the correct location of the stream. The results indicate that the agree method provides a better fit with the DEM for the hilly region than the shortest path method. For the flat region where the flow has been diverted and rerouted by land managers, both methods require observation of the drainage network to determine the flow direction. In order to clarify the applicability of the two methods, both are employed in catchment hydrological models conceptually based on the Xinanjiang model and implemented with PCRaster. The simulation results show that both methods can be successfully applied in hydrological modeling. There are no evident differences in the modeled discharge when using the two methods at different spatial scales.
基金supported by the National Natural Science Foundation of China (Grant Nos.71901134&51878165)the National Science Foundation for Distinguished Young Scholars (Grant No.51925801).
文摘Traffic flow prediction plays an important role in intelligent transportation systems and is of great significance in the applications of traffic control and urban planning.Due to the complexity of road traffic flow data,traffic flow prediction has been one of the challenging tasks to fully exploit the spatiotemporal characteristics of roads to improve prediction accuracy.In this study,a combined flow direction level traffic flow prediction graph convolutional network(GCN)and long short-term memory(LSTM)model based on spatiotemporal characteristics is proposed.First,a GCN model is employed to capture the topological structure of the data graph and extract the spatial features of road networks.Additionally,due to the capability to handle long-term dependencies,the longterm memory is used to predict the time series of traffic flow and extract the time features.The proposed model is evaluated using real-world data,which are obtained from the intersection of Liuquan Road and Zhongrun Avenue in the Zibo High-Tech Zone of China.The results show that the developed combined GCNLSTM flow direction level traffic flow prediction model can perform better than the single models of the LSTM model and GCN model,and the combined ARIMA-LSTM model in traffic flow has a strong spatiotemporal correlation.
基金Supported by Doctoral Research Foundation of Northeast Dianli University(BSJXM-200807)
文摘Differential and integrated directed flow and elliptic flow of light charged particles （z ≤ 2） are studied systematically for semi-central （b = 5 fm） 197Au＋197Au collisions at incident energies from 25 to 250 MeV/nucleon by the isospin-dependent quantum molecular dynamics model. The changes of directed and elliptic flow with incident energy reflect the dynamic competition between mean field and nucleon-nucleon collisions and also between collective rotation and expansion.
基金This project is supported by National Natural Science Foundation of China (No.59235101).
文摘In order to decrease the anisotropy of mechanical properties, the rigid-plastic mechanical model for the forging method with horizontal V-shaped anvil is presented. The forging method, through the change of anvils shape, is able to control fibrous tissue direction, to improve the anisotropy of mechanical properties of axial forgings, to realize uniform forging. Therefore, the forging method can overcome the defect that conventional forging methods produce. The mechanism of the forging method with horizontal V-shaped anvil and the process of metal deformation are analyzed. The agreement of theoretical analysis with experimental study verifies the fact that the forging method with horizontal V-shaped anvil can control effectively the mechanical properties of axial forgings.
基金the National Basic Research Program(973)of China(No.2007CB714103)
文摘A new algorithm to automatically extract drainage networks and catchments based on triangulation irregular networks(TINs) digital elevation model(DEM) was developed. The flow direction in this approach is determined by computing the spatial gradient of triangle and triangle edges. Outflow edge was defined by comparing the contribution area that is separated by the steepest descent of the triangle. Local channels were then tracked to build drainage networks. Both triangle edges and facets were considered to construct flow path. The algorithm has been tested in the site for Hawaiian Island of Kaho'olawe, and the results were compared with those calculated by ARCGIS as well as terrain map. The reported algorithm has been proved to be a reliable approach with high efficiency to generate well-connected and coherent drainage networks.
基金Key Project of National Natural Science Foundation of China(52237008)Beijing Municipal Education Commission Research Program Funding Project(KM202111232022)。
文摘There are many motors in operation or on standby in nuclear power plants,and the startup of group motors will have a great impact on the voltage of the emergency bus.At present,there is no special or inexpensive software to solve this problem,and the experience of engineers is not accurate enough.Therefore,this paper developed a method and system for the startup calculation of group motors in nuclear power plants and proposed an automatic generation method of circuit topology in nuclear power plants.Each component in the topology was given its unique number,and the component class could be constructed according to its type and upper and lower connections.The subordination and topology relationship of switches,buses,and motors could be quickly generated by the program according to the component class,and the simplified direct power flow algorithm was used to calculate the power flow for the startup of group motors according to the above relationship.Then,whether the bus voltage is in the safe range and whether the voltage exceeds the limit during the startup of the group motor could be judged.The practical example was used to verify the effectiveness of the method.Compared with other professional software,the method has high efficiency and low cost.
文摘Although several studies have assessed the effects of thinning on water quality,including nitrogen(N)exports,few have examined N-saturated plantations.This study assessed the short-term effect of thinning on N exports from a N-saturated plantation forest in northern Kyushu,western Japan,that was thinned(43%of basal area)during January-March 2012.Water levels at the gauging station were continually measured,and streamwater baseflow and stormflow samples were collected before(2011)and after(2013)forest thinning.Annual precipitation before(2469 mm)and after(2418 mm)forest thinning differed little,and annual water discharge after thinning(1641 mm)was similar to that before thinning(1609 mm).However,direct flow during stormflow periods was higher after thinning(260 mm)than before(153 mm).The concentrations of major ions in stream water did not differ before and after thinning.As a result,the high annual dissolved inorganic N(DIN)exports differed little before(35.8 kg N ha^-1 a^-1)and after(36.5 kg N ha^-1 a^-1)forest thinning.DIN exports during stormflow periods were slightly higher after(12.2 kg N ha^-1 a^-1)than before thinning(10.5 kg N ha^-1 a^-1)and were proportional to the increased direct flow after thinning(561 mm after vs.470 mm before thinning).We concluded that thinning does not affect annual N exports from the N-saturated plantation forest,but it can increase the proportion of N exported during stormflow periods in proportion to increased water volume of direct flow after thinning.
文摘The wind turbine has the advantage of operating uninterruptedly, which ensures a constant source of electricity. This investigation includes a clear overview of the wind velocity, the flow direction;the amount of energy reserved, suitable regions for wind turbine installation, etc. The feasibility and possibility of installing a wind energy conversion system for several locations in Bangladesh are analyzed. A brief study of wind characteristics in different locations in Bangladesh is reported. Wind data obtained from the Bangladesh Meteorological Department (BMD) for Mongla, Patuakhali, Kutubdia, and Bhola stations are analyzed through wind rose, frequency distribution, and average wind velocity. The performance of suitable small-scale wind turbines will be assessed in order to confirm the prospect of wind turbines in Bangladesh.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51276046 and 51506037)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51421063)+2 种基金the China Postdoctoral Science Foundation(Grant No.2016M591526)the Heilongjiang Postdoctoral Fund,China(Grant No.LBH-Z15063)the China Postdoctoral International Exchange Program
文摘Direct numerical simulations（DNSs） of purely elastic turbulence in rectilinear shear flows in a three-dimensional（3D） parallel plate channel were carried out,by which numerical databases were established.Based on the numerical databases,the present paper analyzed the structural and statistical characteristics of the elastic turbulence including flow patterns,the wall effect on the turbulent kinetic energy spectrum,and the local relationship between the flow motion and the microstructures＇ behavior.Moreover,to address the underlying physical mechanism of elastic turbulence,its generation was presented in terms of the global energy budget.The results showed that the flow structures in elastic turbulence were 3D with spatial scales on the order of the geometrical characteristic length,and vortex tubes were more likely to be embedded in the regions where the polymers were strongly stretched.In addition,the patterns of microstructures＇ elongation behave like a filament.From the results of the turbulent kinetic energy budget,it was found that the continuous energy releasing from the polymers into the main flow was the main source of the generation and maintenance of the elastic turbulent status.
文摘The Nkoup watershed(10°35’-10°47’E and 5°27’-5°42’N)is a volcanic zone situated in Nun Plain West Cameroon.The high fertility of the soils makes it a strategic agropastoral area where water resources are heavily exploited and used for several purposes.Due to human activities,soils and water resources are deteriorating,giving birth to water pollution and hydromorphological hazards.This work aims to determine the hydromorphometric parameters of the Nkoup watershed so that the data obtained help in the sustainable management of water resources and conservation of soil.To achieve this aim,various data were collected from DEM dataset derived from SRTM and processed in specialized software(QGIS and ArGIS).The simplified hydrological balance was calculated using the upstream approach.The Nkoup watershed has:Axial length L_(ax)=25.8 km,Axial Width W_(ax)=11.1 km,Perimeter P=132.6 km,Area A=173.7 km^(2),Average Altitude Ha=1726.3 m,Compactness Index Icomp=2.8,Relief ratio Rr=3.9 m/km,Circularity ratio Rc=0.1,Elongation ratio R=0.1,Drainage texture ratio Rt=0.6,Drainage density Dd=0.5 km/km^(2).Stream Frequency Fs=0.4,Channel Sinuosity Index CSI=0.8,Stream gradient Sg=0.6 and global slope Index Ig=6.8 m/km.The specific height Difference Ds=89.4 m shows moderate relief.The precipitation and evapotranspiration are unevenly distributed.With P=187.7 mm/an,ETP=953.4 mm/an,Q=4.2 m3/s,R=762.5 mm/an,ETR=832.3 mm/an and I=282.9 mm/an.The Nkoup,36.9 km long,has a sinuous aspect due to the low slope and the high CSI.The piezometric levels vary according to the seasons and the groundwater flow follows the N-S direction as surface flow.
