The Triple Ionosphere Photo Meter (TRIPM) is a far ultraviolet nadir-view photometer that is onboard the secondgeneration,polar-orbiting Chinese meteorological satellite Feng-Yun 3E (FY-3E),which was launched on J...
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The Triple Ionosphere Photo Meter (TRIPM) is a far ultraviolet nadir-view photometer that is onboard the secondgeneration,polar-orbiting Chinese meteorological satellite Feng-Yun 3E (FY-3E),which was launched on July 5,*** has three channels,and each is used to measure different types of emissions:(1) 135.6 nm airglow produced by the recombination of the O+ions and electrons in the absence of sunlight (nighttime channel);(2) 135.6 nm airglow from the OI when sunlight is present (daytime/dusk-dawn 135.6 nm channel);and (3) Airglow in the N2LBH of the TRIPM (daytime/dusk-dawn N2LBH channel).FY-3E is a satellite operating in the early morning ***,the data are mostly distributed on the dawndusk side or at times when the solar zenith angle is relatively *** this study,combined with simulation calculations,the data are *** further explore the application value of the data products,a model is used to separate the ionospheric radiative recombination contribution from the thermosphere photoelectron impact excitation contribution in the data from the daytime/dusk-dawn 135.6 nm *** approach not only improves the accuracy of O/N2derived from the 135.6 nm channel and N2LBH channel but also provides the ionospheric 135.6 nm radiance at the same time as the *** results show that the 135.6 nm radiance originating from the combination of O+and electrons extracted from the measurement data exhibits similar equatorial anomaly peak structure characteristics and seasonal variations as the corresponding GPS total electron content (TEC) *** the other hand,the separated 135.6 nm radiance generated from the thermosphere photoelectron collision excitation does not contain radiative recombination contributions;thus,the ionosphere influence is greatly avoided when the O/N2is obtained.
The flow field in a rectangular channel with a transversely placed spiral coil insert is investigated by Particle Image Velocimetry (PIV) measurements in both transverse and longitudinal sections. The experimental r...
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The flow field in a rectangular channel with a transversely placed spiral coil insert is investigated by Particle Image Velocimetry (PIV) measurements in both transverse and longitudinal sections. The experimental results show that multi-longitudinal vortices are induced downstream of the spiral coil and are distributed as a symmetrical vortex array along the horizontal central line of the transverse section. Along the mainstream, due to the spiral motion of the longitudinal vortices, the velocity fluctuates in a manner of the damped sinusoidal curve and the velocity component in the wall normal direction is improved in the channel. Com- pared with the flow field in a smooth channel it is found that the movement of the longitudinal vortices can cause a continuous dis- turbance near the channel walls and thus enhances the fluid velocity in the near wall region, which consequently leads to the redu- ction of the velocity gradient and a more uniform velocity distribution. With the increase of the Reynolds number, the induced longitudinal vortices gain strength and become straighter and closer to the channel walls, thus the turbulence intensity is further enha- nced in this area.
Using numerical methodology, the flow fields between two corrugated plates with different values of the corrugation inclination angle β were simulated. The simulation results directly indicate that β affects the flo...
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Using numerical methodology, the flow fields between two corrugated plates with different values of the corrugation inclination angle β were simulated. The simulation results directly indicate that β affects the flow pattern between corrugated plates, and the results are in good agreement with the experimental results reported by interrelated literature. The results show that the flow pattern between the two plates changes from "double cross-flow" to "zigzag flow" with the increase in β. The reason for the effect on the flow pattern between the two corrugated plates was discussed from the view of the variation of momentum in the direction of corrugation with the variation in β.
For a large-scale high voltage direct current (HVDC)asynchronous interconnected power grid, the frequency issue atthe power sending side under DC faults is a crucial *** solve this problem, based on rotor motion equat...
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For a large-scale high voltage direct current (HVDC)asynchronous interconnected power grid, the frequency issue atthe power sending side under DC faults is a crucial *** solve this problem, based on rotor motion equations, theeffect of unbalanced power on the system frequency under DCfaults is analyzed. The characteristics and dynamic developmentprocess of frequencies after the injection of disturbances areanalyzed. In addition, the actions and coordinated strategies ofvarious frequency control measures are also investigated. Basedon the testing projects of an asynchronous interconnection in theChina Southern Power Grid (CSG), the frequency features arestudied according to the measured PMU data. The outcome showsthat the frequency problem of the Yunnan Power Grid after anasynchronous interconnection can be solved and controlled. Italso shows that the frequency limit control (FLC) is importantfor the frequency regulation of large scale HVDC asynchronousinterconnected DC power grids. As demonstrated, DC FLC caneffectively suppress the deviation of the transient ***, reasonable frequency regulation parameters shouldbe set and other area frequency control measures should becoordinated to maintain the frequency stability of the system.
An interplanetary shock and a magnetic cloud(MC) reached the Earth on 2012 July 14 and 15 one after *** shock sheath and the MC triggered an intense geomagnetic *** find that only small part of the MC from06:45 UT to ...
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An interplanetary shock and a magnetic cloud(MC) reached the Earth on 2012 July 14 and 15 one after *** shock sheath and the MC triggered an intense geomagnetic *** find that only small part of the MC from06:45 UT to 10:05 UT on 2012 July 15 made contribution to the intense geomagnetic storm,while the rest part of the MC made no contribution to the intense geomagnetic *** averaged southward component of interplanetary magnetic field(Bs) and duskward-electric fields(Ey) within the MC from 10:05 UT,2012 July 15 to09:08 UT,2012 July 16(hereafter MC2),are 15.11 nT and 8.01 my m-1,*** to the empirical formula established by Burton et al.(hereafter Burton equation),the geoeffectiveness of MC2 should be-655.42 nT,while the geoeffectiveness of MC2 is-324.68 nT according to the empirical formula established by O’Brien & McPherron(hereafter OM equation).However,the real geoeffectiveness of MC2 is 39.74 *** results indicate that the Burton equation and the OM equation cannot work *** geoeffectiveness of MC2 shows that large and long duration of Bs or Ey cannot guarantee the occurrence of an intense geomagnetic storm if the solar wind dynamic pressure is very *** we use 0.52 as γ,the geoeffectiveness of MC2 is 40.36 nT according to the empirical formula established by Wang et al.,which is very close to the observed value,indicating that the empirical formula established by Wang et *** much better than the Burton equation and the OM equation.
Three-dimensional numerical simulations and experiments were carried out to study the heat transfer characteristics and the pressure drop of air flow in a circular tube with Edgefold-Twisted Tape (ETT) inserts and w...
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Three-dimensional numerical simulations and experiments were carried out to study the heat transfer characteristics and the pressure drop of air flow in a circular tube with Edgefold-Twisted Tape (ETT) inserts and with classic Spiral-Twisted-Tape (STT) inserts of the same twist ratio. The RNG turbulence model for mildly swirling flows, the enhanced wall treatment for low Reynolds numbers, and the SIMPLE pressure-velocity method were adopted to simulate the flow and heat transfer characteristics. Within the range of Reynolds number from 2 500 to 9 500 and the twist ratio y from 5.4 to 11.4, the Nusselt number of the tube with ETT inserts is found to be 3.9% - 9.2% higher than that with STT inserts, and the friction factor of the tube with ETT inserts is 8.7% - 74% higher than that of STT inserts. The heat enhancement is due to higher tangential velocity and asymmetrical velocity profile with the increase and decrease of the periodic velocity within an edgefold length. It is found that main factors affecting the heat transfer of ETT inserts are the twist angle and the gap width between the tube and inserts. A larger twist angle leads to a higher tangential velocity, and larger Nusselt number and friction factor. The thermal-hydraulic performance slowly decreases as the twist angle increases. The gap width between tube and inserts has a significant influence on the heat transfer, while little influence on pressure drops. The thermal-hydraulic performance increases in average by 124% and 140% when the gap width reduces from 1.5 mm to 1.0 mm and 0.5 mm. The larger the gap width, the higher velocity through the gap will be, which would reduce the main flow velocity and tangential velocity. So a small gap is desirable. Comparing experimental and numerical results at variable air flow and tube wall temperature, the numerical results are found to be in a reasonable agreement with the experiment results, with difference of the Nusselt number in a range of 1.6% - 3.6%, and tha
A new-type corrugation Plate Heat Exchanger (PHE) was designed. Results from both numerical simulations and experiments showed that the flow resistance of the working fluid in this new corrugation PHE, compared with...
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A new-type corrugation Plate Heat Exchanger (PHE) was designed. Results from both numerical simulations and experiments showed that the flow resistance of the working fluid in this new corrugation PHE, compared with the traditional chevron-type one, was decreased by more than 50%, and corresponding heat transfer performance was decreased by about 25%. The flow field of the working fluid in the corrugation PHE was transformed and hence performance difference in both flow resistance and heat transfer was generated. Such a novel plate, consisting of longitudinal and transverse corrugations, can effectively avoid the problem of flow path blockage, which will help to extend the application of PHEs to the situation with unclean working fluids.
Ship bow wave breaking contains complex flow mechanism,which is very important for ship *** this study,a practical numerical simulation scheme for bow wave breaking is proposed and the scheme is applied to the simulat...
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Ship bow wave breaking contains complex flow mechanism,which is very important for ship *** this study,a practical numerical simulation scheme for bow wave breaking is proposed and the scheme is applied to the simulation of bow wave breaking of KCS ship model with Fr=0.26,0.30,0.35,0.40,analyzing the impact of speed on the bow wave *** results indicate that an increase in speed leads to a significant rise in viscous pressure resistance and more pronounced bow wave ***,it is found that the traditional wave height function in OpenFOAM is not suitable for detailed studies of bow wave *** study extracts different free surfaces through top and bottom views to further analyze the free surface overturning,droplet splashing,and cavity entrainment in bow wave ***,the spatial and temporal distribution of cavities at Fr=0.40 is analyzed,revealing that cavity distribution is closely related to vortex structures and exhibits a periodic pulsation characteristic of approximately 12 s.
Using an international reference ionosphere(IRI)model as a background ionosphere and applying the Kalman filter to update the state with observations,we develop an ionosphere data assimilation analysis system(IDAAS)to...
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Using an international reference ionosphere(IRI)model as a background ionosphere and applying the Kalman filter to update the state with observations,we develop an ionosphere data assimilation analysis system(IDAAS)to reconstruct a three-dimensional(3D)ionosphere with the GPS slant TEC and ionosonde data over east-south *** preliminary results with the GPS data collected over east-south Asia on 30 June 2005 showed that inversed slant TEC has very good correlation with the observations both for the GPS sites being and not being involved in *** inversed NmF2 and vertical TEC both demonstrate great improvement of agreement with those observed from ionosondes and TOPEX satellite independently.
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