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411.
Yifeng Zhou Leung H. Blanchette M. 《IEEE transactions on aerospace and electronic systems》1999,35(2):410-418
In this work, we formulate the multiple sensor alignment problem in an Earth-centered Earth-fixed (ECEF) coordinate system. The alignment algorithm maps the sensor measurements to the ECEF coordinates using a geodetic transformation, and attributes the discrepancies in the Earth-referenced system reported by each sensor to the sensor biases. Sensor biases are then estimated using the least squares (LS) technique. Simulated and real-life radar data are used to evaluate the performance of the proposed algorithm. Comparisons are made to those algorithms based on the standard stereographic projection 相似文献
412.
J. B. Blake B. H. Mauk D. N. Baker P. Carranza J. H. Clemmons J. Craft W. R. Crain A. Crew Y. Dotan J. F. Fennell R. H. Friedel L. M. Friesen F. Fuentes R. Galvan C. Ibscher A. Jaynes N. Katz M. Lalic A. Y. Lin D. M. Mabry T. Nguyen C. Pancratz M. Redding G. D. Reeves S. Smith H. E. Spence J. Westlake 《Space Science Reviews》2016,199(1-4):309-329
413.
We investigate the behavior of mean values of the solar wind’s and interplanetary magnetic field’s (IMF) parameters and their
absolute and relative variations during the magnetic storms generated by various types of the solar wind. In this paper, which
is a continuation of paper [1], we, on the basis of the OMNI data archive for the period of 1976–2000, have analyzed 798 geomagnetic
storms with D
st
≤ −50 nT and their interplanetary sources: corotating interaction regions CIR, compression regions Sheath before the interplanetary
CMEs; magnetic clouds MC; “Pistons” Ejecta, and an uncertain type of a source. For the analysis the double superposed epoch
analysis method was used, in which the instants of the magnetic storm onset and the minimum of the D
st
index were taken as reference times. It is shown that the set of interplanetary sources of magnetic storms can be sub-divided
into two basic groups according to their slowly and fast varying characteristics: (1) ICME (MC and Ejecta) and (2) CIR and
Sheath. The mean values, the absolute and relative variations in MC and Ejecta for all parameters appeared to be either mean
or lower than the mean value (the mean values of the electric field E
y
and of the B
z
component of IMF are higher in absolute value), while in CIR and Sheath they are higher than the mean value. High values
of the relative density variation sN/〈N〉 are observed in MC. At the same time, the high values for relative variations of the velocity, B
z
component, and IMF magnitude are observed in Sheath and CIR. No noticeable distinctions in the relationships between considered
parameters for moderate and strong magnetic storms were observed. 相似文献
414.
F. Dalla Vedova H. Henrion M. Leipold Th. Girot R. Vaudemont Th. Belmonte K. Fleury O. Le Couls 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
SSM (Solar Sail Materials) is an on-going project for the European Space Agency (ESA) relying on past and recent European solar sail design projects. It aims at developing and testing future technologies suitable for large, operational solar sailcrafts. 相似文献
415.
With the arrival of private entrepreneurs and the appearance of such things as prizes to stimulate space initiatives, the space economy is changing rapidly from its initial government-driven character. A number of countries and territories, such as the Isle of Man, have understood the growing role of this new space economy and are preparing the appropriate boundary conditions to support its further development. This article shows why the Isle of Man may be uniquely placed to take advantage of recent developments in the space economy, thanks to its business-friendly tax and regulatory regime, and discusses the island’s strategy to attract space businesses. The establishment of the International Institute of Space Commerce, a recently formed think-tank, is an integral part of this strategy. 相似文献
416.
In this paper, the results of calculating the processes of two fuel mixture combustion in different proportions are presented.
The values of temperature, thermal capacity, specific gas constant and isentropic expansion ratio of combustion products are
given. Also shown is the distinction of thermodynamic properties from the additivity law. 相似文献
417.
A finite element statement of solving problems on stability of reinforced elliptic cylindrical shells taking into account
momentness and nonlinearity of their subcritical stress strain state is presented. The explicit expressions for displacements
of noncircular cylindrical shell elements as rigid bodies are determined by integrating the equations obtained by equating
the components of linear strains to zero. These expressions were used to construct the form functions for an efficient quadrilateral
finite element of natural curvature. An efficient numerical algorithm of nonlinear deformation and stability of shells was
developed. The stability of reinforced elliptic cylindrical shells under combined loading by bending moment, transverse boundary
force and internal pressure is analyzed. We also examine how the critical loads are affected by the strain nonlinearity and
ellipticity of shell deformation at the subcritical stage. 相似文献
418.
I. S. Akhmed’yanov 《Russian Aeronautics (Iz VUZ)》2010,53(2):230-234
To complete study [1], the procedure of applying the numerical quadrature method to analyzing the shells of revolution under
axisymmetrical loading is presented. 相似文献
419.
A. N. Markushin V. K. Merkushin V. M. Byshin A. V. Baklanov 《Russian Aeronautics (Iz VUZ)》2010,53(1):63-68
The test results of a conventional combustion chamber with the improved structure are presented. The concentration of toxic
substance emissions is reduced as compared with combustion chambers of the similar type. 相似文献
420.
To calculate the unsteady helicopter motion, we propose a simplifying approach consisting in the fact that the numerical solution
of equations of nonlinear nonstationary aerodynamics and flight dynamics are made successively in time intervals. As an example,
the results of calculating the helicopter motion in descent are presented. The mathematical model and algorithm can be used
for calculating the unsteady motion of different helicopters. 相似文献