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151.
Hsien Shang Frank H. Shu Typhoon Lee Alfred E. Glassgold 《Space Science Reviews》2000,92(1-2):153-176
We discuss the interaction between the magnetosphere of a young star and its surrounding accretion disk. We consider how an
X-wind can be driven magnetocentrifugally from the inner edge of the disk where accreting gas is diverted onto stellar field
lines either to flow onto the Sun or to be flung outwards with the wind. The X-wind satisfies many observational tests concerning
optical jets, Herbig-Haro objects, and molecular outflows. Connections may exist between primitive solar system materials
and X-winds. Chondrules and calcium-aluminum-rich inclusions (CAIs) experienced short melting events uncharacteristic of the
asteroid belt where meteorites originate. The inner edge of the solar nebula has the shortest orbital timescale available
to the system, a few days. Protosolar flares introduce another timescale, tens of minutes to hours. CAIs may form when solids
are lifted from shaded portions of the disk close to the Sun and are exposed to its intense light for a day or so before they
are flung by the X-wind to much larger distances. Chondrules were melted, perhaps many times, by flares at larger distances
from the Sun before being launched and annealed, but not remelted, in the X-wind. Aerodynamic sorting explains the narrow
range of sizes with which CAIs and chondrules are found in chondritic meteorites. Flare-generated cosmic-rays may induce spallation
reactions that produce some of the short-lived radioactivities associated with primitive solar system rocks.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
152.
B.K. Choi J.H. Cho S.J. Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The total electron content (TEC) estimation by the Global Positioning System (GPS) can be seriously affected by the differential code biases (DCB), referred to as inter-frequency biases (IFB), of the satellite and receiver so that an accuracy of GPS–TEC value is dependent on the error of DCBs estimation. In this paper, we proposed the singular value decomposition (SVD) method to estimate the DCB of GPS satellites and receivers using the Korean GPS network (KGN) in South Korea. The receiver DCBs of about 49 GPS reference stations in KGN were determined for the accurate estimation of the regional ionospheric TEC. They obtained from the daily solution have large biases ranging from +5 to +27 ns for geomagnetic quiet days. The receiver DCB of SUWN reference station was compared with the estimates of IGS and JPL global ionosphere map (GIM). The results have shown comparatively good agreement at the level within 0.2 ns. After correction of receiver DCBs and knowing the satellite DCBs, the comparison between the behavior of the estimated TEC and that of GIMs was performed for consecutive three days. We showed that there is a good agreement between KASI model and GIMs. 相似文献
153.
Taek Lyul Song Dong Gwan Lee 《IEEE transactions on aerospace and electronic systems》2000,36(1):234-240
An effective filter structure is suggested for filtering of target glint in active homing engagements of a ship-to-ship missile. The proposed filter has decoupled range and angle channels so that it has a sound mathematical basis as well as computational efficiency as applied to the interacting multiple model algorithm. The proposed algorithm in conjunction with an impact angle control law is tested by a series of simulation runs and it is shown to have superior performance compared with the other filter structures 相似文献
154.
Kun-Chou Lee 《IEEE transactions on aerospace and electronic systems》2007,43(3):1065-1070
In this paper, a technique of neural network based integration is proposed to calculate the self-and mutual-impedances within arrays of sonar transducers. The multi-dimensional integrals appearing in self-and mutual-impedance formulations are transformed into neural-network-based integration and the final results can be found from look-up tables in mathematical handbooks. Initially, the integrand is modeled by a trained neural network. Integration on the integrand then becomes integration on the linear combination of weights and basis functions within the neural network. The results will become the linear combination of error functions which can be looked up in mathematical handbooks. Numerical simulation shows that the results calculated by the proposed method are consistent with those given in other existing studies. The proposed technique requires neither numerical nor artificial integration procedure. Due to the inherent learning and predicting property of neural network, only a small number of sampling points for the integrand are required in the proposed integration technique. 相似文献
155.
156.
F. F. Verduijn T. Algra G. J. Close C. Lee B. J. Denore J. B. Williams 《Acta Astronautica》2003,52(9-12):829-832
157.
尽管航空公司的客座收益率增加了,但降低维修成本的压力仍在继续,发动机维修市场反弹最为强劲。TeamSAI公司今年继续为本刊提供了未来10年的航空维修市场预测数据,预计今年的全球航空维修市值会达 相似文献
158.
H Aiginger V Andersen F Ballarini G Battistoni M Campanella M Carboni F Cerutti A Empl W Enghardt A Fassò A Ferrari E Gadioli M V Garzelli K Lee A Ottolenghi K Parodi M Pelliccioni L Pinsky J Ranft S Roesler P R Sala D Scannicchio G Smirnov F Sommerer T Wilson N Zapp 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(2):214-222
159.
Jeongwoo Lee 《Space Science Reviews》2007,133(1-4):73-102
Solar active region coronae are known for strong magnetic fields permeating tenuous plasma, which makes them an ideal astronomical
laboratory for magnetohydrodynamics research. It is, however, relatively less known that this physical condition also permits
a very efficient radiation mechanism, gyro-resonant emission, produced by hot electrons gyrating in the coronal magnetic field.
As a resonant mechanism, gyro-emission produces high enough opacity to fully reveal the coronal temperature, and is concentrated
at a few harmonics of the local gyrofrequency to serve as an excellent indicator of the magnetic field. In addition, the polarization
of the ubiquitous free–free emission and a phenomenon of depolarization due to mode coupling extend the magnetic field diagnostic
to a wide range of coronal heights. The ability to measure the coronal temperature and magnetic field without the complications
that arise in other radiative inversion problems is a particular advantage for the active region radio emissions available
only at these wavelengths. This article reviews the efforts to understand these radiative processes, and use them as diagnostic
tools to address a number of critical issues involved with active regions. 相似文献
160.
Equivalent ARMA model representation for RLG random errors 总被引:2,自引:0,他引:2
Sang Man Seong Jang Gyu Lee Chan Gook Park 《IEEE transactions on aerospace and electronic systems》2000,36(1):286-290
It is shown that a mixture of random noises can be represented by a single equivalent ARMA (autoregressive moving average) model that is simple to implement. We applied the scheme to model RLG (ring laser gyroscope) random errors. An identification result from real test data confirms the validity of this approach 相似文献