A regional ocean reanalysis system for the coastal waters of China and adjacent seas has been developed by the National Marine Data and Information Service（NMDIS）.It produces a dataset package called CORA （China oc...A regional ocean reanalysis system for the coastal waters of China and adjacent seas has been developed by the National Marine Data and Information Service（NMDIS）.It produces a dataset package called CORA （China ocean reanalysis）.The regional ocean model used is based on the Princeton Ocean Model with a generalized coordinate system（POMgcs）.The model is parallelized by NMDIS with the addition of the wave breaking and tidal mixing processes into model parameterizations.Data assimilation is a sequential three-dimensional variational（3D-Var） scheme implemented within a multigrid framework.Observations include satellite remote sensing sea surface temperature（SST）,altimetry sea level anomaly（SLA）,and temperature/salinity profiles.The reanalysis fields of sea surface height,temperature,salinity,and currents begin with January 1986 and are currently updated every year. Error statistics and error distributions of temperature,salinity and currents are presented as a primary evaluation of the reanalysis fields using sea level data from tidal gauges,temperature profiles,as well as the trajectories of Argo floats.Some case studies offer the opportunity to verify the evolution of certain local circulations.These evaluations show that the reanalysis data produced provide a good representation of the ocean processes and phenomena in the coastal waters of China and adjacent seas.展开更多
Previously, mouse bone marrow-derived stem cells （MSC） treated with the unspecific DNA methyltransferase inhibitor 5-azacytidine were reported to differentiate into cardiomyocytes. The aim of the present study was t...Previously, mouse bone marrow-derived stem cells （MSC） treated with the unspecific DNA methyltransferase inhibitor 5-azacytidine were reported to differentiate into cardiomyocytes. The aim of the present study was to investigate the efficiency of a similar differentiation strategy in human mononuclear cells obtained from healthy bone marrow donors. After 1-3 passages, cultures were exposed for 24 h to 5-azacytidine （3 μM） followed by 6 weeks of further culture. Drug treatment did not induce expression of myogenic marker MyoD or cardiac markers Nkx2.5 and GATA-4 and did not yield beating cells during follow-up. In patch clamp experiments, approximately 10-15% of treated and untreated cells exhibited L-type Ca^2＋ currents. Almost all cells showed outwardly rectifying K^＋ currents of rapid or slow activation kinetics. Mean current amplitude at ＋60 mV doubled after 6 weeks of treatment compared with time-matched controls. Membrane capacitance of treated cells was significantly larger than in controls 2 weeks after treatment and remained high after 6 weeks, Expression levels of mRNAs for the K^＋ channels Kv 1,1, Kv 1,5, Kv2,1, Kv4,3 and KCNMA 1 and for the Ca^2＋ channel Cav 1.2 were not affected by 5-azacytidine. Treatment with potassium channel blockers tetraethylammonium and clofilium at concentrations shown previously to inhibit rapid or slowly activating K^＋ currents of hMSC inhibited proliferation of these cells. Our results suggest that despite the absence of differentiation ofhMSC into cardiomyocytes, treatme.nt with 5-azacytidine caused profound changes in current density.展开更多
To clarify the modulation of dragon's blood on the tetrodotoxin-resistant (TTX-R) sodium currents in dorsal root ganglion (DRG) neurons and explore its corresponding material basis for the efficacy, using whole-ce...To clarify the modulation of dragon's blood on the tetrodotoxin-resistant (TTX-R) sodium currents in dorsal root ganglion (DRG) neurons and explore its corresponding material basis for the efficacy, using whole-cell patch clamp technique, the effects of dragon's blood and the combined effects of three components (cochinchinenin A, cochinchinenin B, and loureirin B) extracted from dragon's blood on the TTX-R sodium currents in acute-isolated DRG neurons of rats were observed. According to the operational definition of material basis for the efficacy of TCM established, the material basis of the modulation on the TTX-R sodium currents in DRG neurons of dragon's blood was judged from the experimental results. The drug interaction equation of Greco et al. was used to assess the interaction of the three components extracted from dragon's blood. This investigation demonstrated that dragon's blood suppressed the peak TTX-R sodium currents in a dose-dependent way and affected the activations of TTX-R sodium currents. The effects of the combination of cochinchinenin A, cochinchinenin B, and loureirin B were in good agreement with those of dragon's blood. Although the three components used alone could modulate TTX-R sodium currents, the concentrations of the three components used alone were respectively higher than those used in combination when the inhibition rates on the TTX-R sodium currents of them used alone and in combination were the same. The combined effects of the three components were synergistic. These results suggested that the interference with pain messages caused by the modulation of dragon's blood on TTX-R sodium currents in DRG neurons may explain some of the analgesic effect of dragon's blood and the corresponding material basis for the efficacy is the combination of cochinchinenin A, cochinchinenin B, and loureirin B.展开更多
An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities a...An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities and transports of the mean circulation agree well. Transports of the North Equatorial Current (NEC), Mindanao Current (MC), North Equatorial Countercurrent (NECC) west of 140°E and Kuroshio origin estimated with the assimilation data display the seasonal cycles, roughly strong in boreal spring and weak in autumn, with a little phase difference. The NECC transport also has a semi-annual fluctuation resulting from the phase lag between seasonal cycles of two tropical gyres’ recirculations. Strong in summer during the southeast monsoon period, the seasonal cycle of the Indonesian throughflow (ITF) is somewhat different from those of its upstreams, the MC and New Guinea Coastal Current (NGCC), implying the monsoon’s impact on it.展开更多
Abstract Based on computational fluid dynamics （CFD） method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerody- namic/stealth has been estab...Abstract Based on computational fluid dynamics （CFD） method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerody- namic/stealth has been established for helicopter rotor. The developed integration design method is composed of three modules： integrated grids generation （the moving-embedded grids for CFD sol- ver and the blade grids for radar cross section （RCS） solver are generated by solving Poisson equa- tions and folding approach）, aerodynamic/stealth solver （the aerodynamic characteristics are simulated by CFD method based upon NavieStokes equations and Spalart-Allmaras （S-A） tur- bulence model）, and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics （PO）, equivalent currents （MEC） and quasi-stationary （MQS）, and integrated optimization analysis （based upon the surrogate model optimization technique with full factorial design （FFD） and radial basis function （RBF）, an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted. Firstly, the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out, then timfrequency domain grayscale with strong scattering regions of rotor have been given. Meanwhile, the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed. Furthermore, by choosing suitable object function and constraint condition, the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.展开更多
Water waves, wave-induced long-shore currents and movement of pollutants in waves and currents have been numerically studied based on the hyperbolic mild-slope equation, the shallow water equation , as well as the pol...Water waves, wave-induced long-shore currents and movement of pollutants in waves and currents have been numerically studied based on the hyperbolic mild-slope equation, the shallow water equation , as well as the pollutant movement equation, and the numerical results have also been validated by experimental data. It is shown that the long-shore current velocity and wave set-up increase with the increasing incident wave amplitude and slope steepness of the shore plane ; the wave set-up increases with the in- creasing incident wave period;and the pollutant morement proceeds more quiekly with the increasing incident wave amplitude and slope steepness of the shore palane. In surf zones, the long-shore currents induced by the inclined incident waves have effectively affected the pollutant movement.展开更多
Daihai Lake, a modern lacustrine rift basin, located in Inner Mongolia, North China, serves as an important modern analog for understanding deltaic depositional processes in an active rift setting. Two of the deltas ...Daihai Lake, a modern lacustrine rift basin, located in Inner Mongolia, North China, serves as an important modern analog for understanding deltaic depositional processes in an active rift setting. Two of the deltas （Yuanzigou delta and Bulianghe delta） on the margins of Daihai Lake were surveyed to compare and contrast stacking patterns using aerial photographs, field trenching and sediment sampling. Shallow cores and trench data collected from the margins of Daihai Lake indicate that a variety of depositional processes have been active since Daihai Lake formed. Two 3-D sedimentation models which employ chronostratigraphic correlation technique were generated. The chronostratigraphic sedimentation models predict and represent the architectures and sand-body continuity of sediments. Stratigraphical coincidence of the broad sheeted drifts and channel erosion suggests a coupling between downslope and alongslope processes. Distributary mouth bars are prevalent in the front of deltas on steeper slopes due to the dominance of down-slope flows. On the contrary, the along-slope currents favor the development of distal bar deposits with sheeted sandbodies on gentle depositional slopes. This study provides an insight into the architecture of complex sedimentary facies associated with highlighting key differences between downslope flows and alongslope currents. The distribution of sand within these deltas is of particular interests, with applications in understanding the architecture of hydrocarbon reservoirs formed in lacustrine rift basin.展开更多
Sediment transport in the Hangzhou Bay is extremely complicated due to its bathymetry and hydrodynamic conditions. The ECOMSED model is employed to simulate three-dimensional （3-D） cohesive sediment transport in Han...Sediment transport in the Hangzhou Bay is extremely complicated due to its bathymetry and hydrodynamic conditions. The ECOMSED model is employed to simulate three-dimensional （3-D） cohesive sediment transport in Hangzhou Bay. Dynamical factors such as Coriolis force, tides, salinity, river discharges, and waves are considered in the model. The wave parameters, including the significant wave height, period, and direction, are calculated with the SWAN model. The Grant-Madsen model is introduced for the bed shear stress due to the combined effect of waves and currents. The formulation of bed shear stress used to calculate the sink/source terms is modified based on previous research that sufficiently validated the formulation with measurement data. The integrated model of the above-mentioned models is applied to simulate sediment transport in Hangzhou Bay. The results of the simulation agree well with field observations concerning the distribution of suspended sediment, indicating that the sediments are remarkably suspended in Hangzhou Bay under the action of waves and currents.展开更多
This article discusses the transverse distributions of the depth averaged velocity and the Reynolds stress in a steady uniform flow in partially vegetated rectangular channels.The momentum equation is expressed in dim...This article discusses the transverse distributions of the depth averaged velocity and the Reynolds stress in a steady uniform flow in partially vegetated rectangular channels.The momentum equation is expressed in dimensionless form and solved to obtain the depth averaged velocity.The analytical solution of the velocity in dimensionless form shows that the depth-averaged velocity is determined by gravity and its distribution is mainly determined by the frictions due to water or vegetations.The analytical solution of the Reynolds stress is also obtained.A relationship between the second flow and the inertia is established and it is assumed that the former is proportional to the square of the depth averaged velocity.The Acoustic Doppler Velocimeter（Micro ADV） was used to measure the steady uniform flow with emergent artificial rigid vegetation.Comparisons between the measured data and the computed results show that our method does well in predicting the transverse distributions of the stream-wise velocity and the Reynolds stress in rectangular channels with partially vegetations.展开更多
The global project of the Array for Real-time Geostrophic Oceanography （ARGO） provides a unique opportunity to observe the absolute velocity in mid-depths of the world oceans. A total of 1597 velocity vectors at 10...The global project of the Array for Real-time Geostrophic Oceanography （ARGO） provides a unique opportunity to observe the absolute velocity in mid-depths of the world oceans. A total of 1597 velocity vectors at 1000 （2000） db in the tropical Pacific derived from the ARGO float position information during the period November 2001 to October 2004 are used to evaluate the intermediate currents of the National Centers for Environmental Prediction reanalysis. To derive reliable velocity information from ARGO float trajectory points, a rigorous quality control scheme is applied, and by virtue of a correction method for reducing the drift error on the surface in obtaining the velocity vectors, their relative errors are less than 25%. Based on the comparisons from the quantitative velocity vectors and from the space-time average currents, some substantial discrepancies are revealed. The first is that the velocities of the reanalysis at mid-depths except near the equator are underestimated relative to the observed velocities by the floats. The average speed difference between NCEP and ARGO values ranges from about -2.3cm s^-1 to -1.8 cm s^-1. The second is that the velocity difference between the ocean model and the observations at 2000 dB seems smaller than that at 1000 dB. The third is that the zonal flow in the reanalysis is too dominant so that some eddies could not be simulated, such as the cyclonic eddy to the east of 160°E between 20°N and 30°N at 2000 dB. In addition, it is noticeable that many floats parking at 1000 dB cannot acquire credible mid-depth velocities due to the time information of their end of ascent （start of descent） on the surface in the trajectory files. Thus, relying on default times of parking, descent and ascent in the metadata files gravely confines their application to measuring mid-depth currents.展开更多
Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surfa...Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surface, and the relation between two currents is also considered. These expressions are degenerated into the common forms for some simple cases. This effort will provide the theoretical preparation for the approximate calculation of electromagnetic scattering from a conducting object coated by an anisotropic material.展开更多
Background Although flunarizine has been widely used for migraine prophylaxis with clear success, the mechanisms of its actions in migraine prophylaxis are not completely understood. The aim of this study was to inves...Background Although flunarizine has been widely used for migraine prophylaxis with clear success, the mechanisms of its actions in migraine prophylaxis are not completely understood. The aim of this study was to investigate the effects of flunarizine on tetrodotoxin-resistant Na＋ channels and high-voltage activated Ca2＋ channels of acutely isolated mouse trigeminal ganglion neurons. Methods Sodium currents and calcium currents in trigeminal ganglion neurons were monitored using whole-cell patch-clamp recordings. Paired Student＇s t test was used as appropriate to evaluate the statistical significance of differences between two group means. Results Both tetrodotoxin-resistant sodium currents and high-voltage activated calcium currents were blocked by flunarizine in a concentration-dependent manner with the concentration producing half-maximal current block values of 2.89 μmol/L and 2.73 μmol/L, respectively. The steady-state inactivation curves of tetrodotoxin-resistant sodium currents and high-voltage activated calcium currents were shifted towards more hyperpolarizing potentials after exposure to flunarizine. Furthermore, the actions of flunarizine in blocking tetrodotoxin-resistant sodium currents and high-voltage activated calcium currents were use-dependent, with effects enhanced at higher rates of channel activation. Conclusion Blockades of these currents might help explain the peripheral mechanism underlying the preventive effect of flunarizine on migraine attacks.展开更多
The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress ...The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress and the work-hardening rate of wires were significantly reduced by applying current pulses in drawing process. The work-hardening behavior of the multi-courses drawing deformation can be well described by Hollomon formula σ=κΕn. With the application of current pulses in drawing deformation, the work-hardening exponents of H0Cr17Ni6Mn3 steel wires and 1Cr18Ni9 stainless steel wires were reduced by 33% and 45%, respectively, and their work-hardening coefficients were reduced by 41% and 47%, respectively. It was also found that the work-hardening coefficient of wires was reduced with the increment of the frequency of current pulses, while the work-hardening exponents of both steels were insensitive to the pulsing frequency.展开更多
A micropolar model for blood simulating magnetohydrodynamic flow through a horizontally nonsymmetric but vertically symmetric artery with a mild stenosis is presented. To estimate the effect of the stenosis shape, a s...A micropolar model for blood simulating magnetohydrodynamic flow through a horizontally nonsymmetric but vertically symmetric artery with a mild stenosis is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the horizontal shape of the stenosis can easily be changed just by varying a parameter referred to as the shape parameter. Flow parameters, such as velocity, the resistance to flow （the resistance impedance）, the wall shear stress distribution in the stenotic region, and its magnitude at the maximum height of the stenosis （stenosis throat）, have been computed for different shape parameters, the Hartmann number and the Hall parameter. This shows that the resistance to flow decreases with the increasing values of the parameter determining the stenosis shape and the Hail parameter, while it increases with the increasing Hartmann number. The wall shear stress and the shearing stress on the wall at the maximum height of the stenosis possess an inverse characteristic to the resistance to flow with respect to any given value of the Hartmann number and the Hall parameter. Finally, the effect of the Hartmann number and the Hall parameter on the horizontal velocity is examined.展开更多
The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quit...The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quite close to the depth of 20 ℃ isotherm in the tropical Pacific. The EOF1 mode of the 25σθ isopycnal surface accounts for 26. 4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10oS over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO. The wavelet analysis of detrended EOF1 time coefficient reveals that there are two dominant time scales of about 3～7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2～7 and 10～15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10oS; there is consistent polarity in the tropics along 165oE, but reverse polarity between around equator and other tropical region along 120oW. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.展开更多
文摘A regional ocean reanalysis system for the coastal waters of China and adjacent seas has been developed by the National Marine Data and Information Service（NMDIS）.It produces a dataset package called CORA （China ocean reanalysis）.The regional ocean model used is based on the Princeton Ocean Model with a generalized coordinate system（POMgcs）.The model is parallelized by NMDIS with the addition of the wave breaking and tidal mixing processes into model parameterizations.Data assimilation is a sequential three-dimensional variational（3D-Var） scheme implemented within a multigrid framework.Observations include satellite remote sensing sea surface temperature（SST）,altimetry sea level anomaly（SLA）,and temperature/salinity profiles.The reanalysis fields of sea surface height,temperature,salinity,and currents begin with January 1986 and are currently updated every year. Error statistics and error distributions of temperature,salinity and currents are presented as a primary evaluation of the reanalysis fields using sea level data from tidal gauges,temperature profiles,as well as the trajectories of Argo floats.Some case studies offer the opportunity to verify the evolution of certain local circulations.These evaluations show that the reanalysis data produced provide a good representation of the ocean processes and phenomena in the coastal waters of China and adjacent seas.
文摘Previously, mouse bone marrow-derived stem cells （MSC） treated with the unspecific DNA methyltransferase inhibitor 5-azacytidine were reported to differentiate into cardiomyocytes. The aim of the present study was to investigate the efficiency of a similar differentiation strategy in human mononuclear cells obtained from healthy bone marrow donors. After 1-3 passages, cultures were exposed for 24 h to 5-azacytidine （3 μM） followed by 6 weeks of further culture. Drug treatment did not induce expression of myogenic marker MyoD or cardiac markers Nkx2.5 and GATA-4 and did not yield beating cells during follow-up. In patch clamp experiments, approximately 10-15% of treated and untreated cells exhibited L-type Ca^2＋ currents. Almost all cells showed outwardly rectifying K^＋ currents of rapid or slow activation kinetics. Mean current amplitude at ＋60 mV doubled after 6 weeks of treatment compared with time-matched controls. Membrane capacitance of treated cells was significantly larger than in controls 2 weeks after treatment and remained high after 6 weeks, Expression levels of mRNAs for the K^＋ channels Kv 1,1, Kv 1,5, Kv2,1, Kv4,3 and KCNMA 1 and for the Ca^2＋ channel Cav 1.2 were not affected by 5-azacytidine. Treatment with potassium channel blockers tetraethylammonium and clofilium at concentrations shown previously to inhibit rapid or slowly activating K^＋ currents of hMSC inhibited proliferation of these cells. Our results suggest that despite the absence of differentiation ofhMSC into cardiomyocytes, treatme.nt with 5-azacytidine caused profound changes in current density.
文摘To clarify the modulation of dragon's blood on the tetrodotoxin-resistant (TTX-R) sodium currents in dorsal root ganglion (DRG) neurons and explore its corresponding material basis for the efficacy, using whole-cell patch clamp technique, the effects of dragon's blood and the combined effects of three components (cochinchinenin A, cochinchinenin B, and loureirin B) extracted from dragon's blood on the TTX-R sodium currents in acute-isolated DRG neurons of rats were observed. According to the operational definition of material basis for the efficacy of TCM established, the material basis of the modulation on the TTX-R sodium currents in DRG neurons of dragon's blood was judged from the experimental results. The drug interaction equation of Greco et al. was used to assess the interaction of the three components extracted from dragon's blood. This investigation demonstrated that dragon's blood suppressed the peak TTX-R sodium currents in a dose-dependent way and affected the activations of TTX-R sodium currents. The effects of the combination of cochinchinenin A, cochinchinenin B, and loureirin B were in good agreement with those of dragon's blood. Although the three components used alone could modulate TTX-R sodium currents, the concentrations of the three components used alone were respectively higher than those used in combination when the inhibition rates on the TTX-R sodium currents of them used alone and in combination were the same. The combined effects of the three components were synergistic. These results suggested that the interference with pain messages caused by the modulation of dragon's blood on TTX-R sodium currents in DRG neurons may explain some of the analgesic effect of dragon's blood and the corresponding material basis for the efficacy is the combination of cochinchinenin A, cochinchinenin B, and loureirin B.
基金supported by National Natural Science Foundation of China(61533013,61273144)Scientific Technology Research and Development Plan Project of Tangshan(13130298B)Scientific Technology Research and Development Plan Project of Hebei(z2014070)
基金This work was supported by the State Key Basic Research Development Project (Grant No. G1999043808)the Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2-205)the National Natural Science Foundation of China (Grant Nos. 4
文摘An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities and transports of the mean circulation agree well. Transports of the North Equatorial Current (NEC), Mindanao Current (MC), North Equatorial Countercurrent (NECC) west of 140°E and Kuroshio origin estimated with the assimilation data display the seasonal cycles, roughly strong in boreal spring and weak in autumn, with a little phase difference. The NECC transport also has a semi-annual fluctuation resulting from the phase lag between seasonal cycles of two tropical gyres’ recirculations. Strong in summer during the southeast monsoon period, the seasonal cycle of the Indonesian throughflow (ITF) is somewhat different from those of its upstreams, the MC and New Guinea Coastal Current (NGCC), implying the monsoon’s impact on it.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘Abstract Based on computational fluid dynamics （CFD） method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerody- namic/stealth has been established for helicopter rotor. The developed integration design method is composed of three modules： integrated grids generation （the moving-embedded grids for CFD sol- ver and the blade grids for radar cross section （RCS） solver are generated by solving Poisson equa- tions and folding approach）, aerodynamic/stealth solver （the aerodynamic characteristics are simulated by CFD method based upon NavieStokes equations and Spalart-Allmaras （S-A） tur- bulence model）, and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics （PO）, equivalent currents （MEC） and quasi-stationary （MQS）, and integrated optimization analysis （based upon the surrogate model optimization technique with full factorial design （FFD） and radial basis function （RBF）, an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted. Firstly, the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out, then timfrequency domain grayscale with strong scattering regions of rotor have been given. Meanwhile, the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed. Furthermore, by choosing suitable object function and constraint condition, the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.
基金The National Basic Research ("973") Program of China under contract No.2005CB724202the National Natural Science Foundation of China under contract Nos.50709004 and 50779006.
文摘Water waves, wave-induced long-shore currents and movement of pollutants in waves and currents have been numerically studied based on the hyperbolic mild-slope equation, the shallow water equation , as well as the pollutant movement equation, and the numerical results have also been validated by experimental data. It is shown that the long-shore current velocity and wave set-up increase with the increasing incident wave amplitude and slope steepness of the shore plane ; the wave set-up increases with the in- creasing incident wave period;and the pollutant morement proceeds more quiekly with the increasing incident wave amplitude and slope steepness of the shore palane. In surf zones, the long-shore currents induced by the inclined incident waves have effectively affected the pollutant movement.
基金supported by the Chinese National Natural Science Fund Project(41072084)National Program on Key Basic Research Project(973 Program)(No. 2009CB219502-3)Prof.Qiu Yinan at RIPED(Research Institute for Petroleum Exploration and Development) of CNPC(China National Petroleum Corporation) for his belief in this work and financial support of the research
文摘Daihai Lake, a modern lacustrine rift basin, located in Inner Mongolia, North China, serves as an important modern analog for understanding deltaic depositional processes in an active rift setting. Two of the deltas （Yuanzigou delta and Bulianghe delta） on the margins of Daihai Lake were surveyed to compare and contrast stacking patterns using aerial photographs, field trenching and sediment sampling. Shallow cores and trench data collected from the margins of Daihai Lake indicate that a variety of depositional processes have been active since Daihai Lake formed. Two 3-D sedimentation models which employ chronostratigraphic correlation technique were generated. The chronostratigraphic sedimentation models predict and represent the architectures and sand-body continuity of sediments. Stratigraphical coincidence of the broad sheeted drifts and channel erosion suggests a coupling between downslope and alongslope processes. Distributary mouth bars are prevalent in the front of deltas on steeper slopes due to the dominance of down-slope flows. On the contrary, the along-slope currents favor the development of distal bar deposits with sheeted sandbodies on gentle depositional slopes. This study provides an insight into the architecture of complex sedimentary facies associated with highlighting key differences between downslope flows and alongslope currents. The distribution of sand within these deltas is of particular interests, with applications in understanding the architecture of hydrocarbon reservoirs formed in lacustrine rift basin.
基金the Funds for Creative Research Groups of China under contract No. 40721004the Sino-Dutch Program for Strategic Scientific Alliance Project under contract No. 2008DFB90240
文摘Sediment transport in the Hangzhou Bay is extremely complicated due to its bathymetry and hydrodynamic conditions. The ECOMSED model is employed to simulate three-dimensional （3-D） cohesive sediment transport in Hangzhou Bay. Dynamical factors such as Coriolis force, tides, salinity, river discharges, and waves are considered in the model. The wave parameters, including the significant wave height, period, and direction, are calculated with the SWAN model. The Grant-Madsen model is introduced for the bed shear stress due to the combined effect of waves and currents. The formulation of bed shear stress used to calculate the sink/source terms is modified based on previous research that sufficiently validated the formulation with measurement data. The integrated model of the above-mentioned models is applied to simulate sediment transport in Hangzhou Bay. The results of the simulation agree well with field observations concerning the distribution of suspended sediment, indicating that the sediments are remarkably suspended in Hangzhou Bay under the action of waves and currents.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50679061, 10972163)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20070486021)
文摘This article discusses the transverse distributions of the depth averaged velocity and the Reynolds stress in a steady uniform flow in partially vegetated rectangular channels.The momentum equation is expressed in dimensionless form and solved to obtain the depth averaged velocity.The analytical solution of the velocity in dimensionless form shows that the depth-averaged velocity is determined by gravity and its distribution is mainly determined by the frictions due to water or vegetations.The analytical solution of the Reynolds stress is also obtained.A relationship between the second flow and the inertia is established and it is assumed that the former is proportional to the square of the depth averaged velocity.The Acoustic Doppler Velocimeter（Micro ADV） was used to measure the steady uniform flow with emergent artificial rigid vegetation.Comparisons between the measured data and the computed results show that our method does well in predicting the transverse distributions of the stream-wise velocity and the Reynolds stress in rectangular channels with partially vegetations.
基金This research is supported by Natural Science Foundation of China(Contract No.40437017 and 40225015).
文摘The global project of the Array for Real-time Geostrophic Oceanography （ARGO） provides a unique opportunity to observe the absolute velocity in mid-depths of the world oceans. A total of 1597 velocity vectors at 1000 （2000） db in the tropical Pacific derived from the ARGO float position information during the period November 2001 to October 2004 are used to evaluate the intermediate currents of the National Centers for Environmental Prediction reanalysis. To derive reliable velocity information from ARGO float trajectory points, a rigorous quality control scheme is applied, and by virtue of a correction method for reducing the drift error on the surface in obtaining the velocity vectors, their relative errors are less than 25%. Based on the comparisons from the quantitative velocity vectors and from the space-time average currents, some substantial discrepancies are revealed. The first is that the velocities of the reanalysis at mid-depths except near the equator are underestimated relative to the observed velocities by the floats. The average speed difference between NCEP and ARGO values ranges from about -2.3cm s^-1 to -1.8 cm s^-1. The second is that the velocity difference between the ocean model and the observations at 2000 dB seems smaller than that at 1000 dB. The third is that the zonal flow in the reanalysis is too dominant so that some eddies could not be simulated, such as the cyclonic eddy to the east of 160°E between 20°N and 30°N at 2000 dB. In addition, it is noticeable that many floats parking at 1000 dB cannot acquire credible mid-depth velocities due to the time information of their end of ascent （start of descent） on the surface in the trajectory files. Thus, relying on default times of parking, descent and ascent in the metadata files gravely confines their application to measuring mid-depth currents.
文摘Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surface, and the relation between two currents is also considered. These expressions are degenerated into the common forms for some simple cases. This effort will provide the theoretical preparation for the approximate calculation of electromagnetic scattering from a conducting object coated by an anisotropic material.
基金This work was supported by grants from the National Natural Science Foundation of China （No. 81070896） and a Yangsen Scienence Grant.
文摘Background Although flunarizine has been widely used for migraine prophylaxis with clear success, the mechanisms of its actions in migraine prophylaxis are not completely understood. The aim of this study was to investigate the effects of flunarizine on tetrodotoxin-resistant Na＋ channels and high-voltage activated Ca2＋ channels of acutely isolated mouse trigeminal ganglion neurons. Methods Sodium currents and calcium currents in trigeminal ganglion neurons were monitored using whole-cell patch-clamp recordings. Paired Student＇s t test was used as appropriate to evaluate the statistical significance of differences between two group means. Results Both tetrodotoxin-resistant sodium currents and high-voltage activated calcium currents were blocked by flunarizine in a concentration-dependent manner with the concentration producing half-maximal current block values of 2.89 μmol/L and 2.73 μmol/L, respectively. The steady-state inactivation curves of tetrodotoxin-resistant sodium currents and high-voltage activated calcium currents were shifted towards more hyperpolarizing potentials after exposure to flunarizine. Furthermore, the actions of flunarizine in blocking tetrodotoxin-resistant sodium currents and high-voltage activated calcium currents were use-dependent, with effects enhanced at higher rates of channel activation. Conclusion Blockades of these currents might help explain the peripheral mechanism underlying the preventive effect of flunarizine on migraine attacks.
基金supported by the laboratory foundation of Tsinghua Universitythe'985'research foundation of Tsinghua University
文摘The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress and the work-hardening rate of wires were significantly reduced by applying current pulses in drawing process. The work-hardening behavior of the multi-courses drawing deformation can be well described by Hollomon formula σ=κΕn. With the application of current pulses in drawing deformation, the work-hardening exponents of H0Cr17Ni6Mn3 steel wires and 1Cr18Ni9 stainless steel wires were reduced by 33% and 45%, respectively, and their work-hardening coefficients were reduced by 41% and 47%, respectively. It was also found that the work-hardening coefficient of wires was reduced with the increment of the frequency of current pulses, while the work-hardening exponents of both steels were insensitive to the pulsing frequency.
文摘A micropolar model for blood simulating magnetohydrodynamic flow through a horizontally nonsymmetric but vertically symmetric artery with a mild stenosis is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the horizontal shape of the stenosis can easily be changed just by varying a parameter referred to as the shape parameter. Flow parameters, such as velocity, the resistance to flow （the resistance impedance）, the wall shear stress distribution in the stenotic region, and its magnitude at the maximum height of the stenosis （stenosis throat）, have been computed for different shape parameters, the Hartmann number and the Hall parameter. This shows that the resistance to flow decreases with the increasing values of the parameter determining the stenosis shape and the Hail parameter, while it increases with the increasing Hartmann number. The wall shear stress and the shearing stress on the wall at the maximum height of the stenosis possess an inverse characteristic to the resistance to flow with respect to any given value of the Hartmann number and the Hall parameter. Finally, the effect of the Hartmann number and the Hall parameter on the horizontal velocity is examined.
基金This study was supported by the National Science Foundation of China under contract No.40136010the Chinese Academy of Sciences under contract No.ZKCX2-SW-210.
文摘The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quite close to the depth of 20 ℃ isotherm in the tropical Pacific. The EOF1 mode of the 25σθ isopycnal surface accounts for 26. 4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10oS over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO. The wavelet analysis of detrended EOF1 time coefficient reveals that there are two dominant time scales of about 3～7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2～7 and 10～15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10oS; there is consistent polarity in the tropics along 165oE, but reverse polarity between around equator and other tropical region along 120oW. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.
