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581.
提出了一种基于限制编程(Constraint programmmg)的信息模型内在一致性检查方法,重点描述了EXPRESS信息模型的一致性及其检查。EXPRESS语言,作为标准制造数据交换的一个重要部分,广泛地应用于制造与信息业。中提到的一致性检查包括三个步骤:EXPRESS模型形式化,限制满足性问题(CSP)从形式化模型中的抽取和CSP的可满足性测试。本同时揭示了限制编程的一个新的应用领域:模型验证。 相似文献
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584.
Luh J. Y. S. Shafran Joel S. Harvey C. Arthur 《IEEE transactions on aerospace and electronic systems》1968,(2):218-233
This paper considers the problem arising from the design of an autopilot for a large booster. The motion-controlling actuators of the booster have both position and rate limits. The problem is formulated as a bounded phase-coordinate problem and analyzed by the ``backing out of the target' procedure. A method of constructing the optimal control is presented. An example of an oscillatory system with two control inputs is given, and the optimal control is expressed as an explicit time function. 相似文献
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586.
Neugebauer M. Steinberg J.T. Tokar R.L. Barraclough B.L. Dors E.E. Wiens R.C. Gingerich D.E. Luckey D. Whiteaker D.B. 《Space Science Reviews》2003,105(3-4):661-679
Some of the objectives of the Genesis mission require the separate collection of solar wind originating in different types
of solar sources. Measurements of the solar wind protons, alpha particles, and electrons are used on-board the spacecraft
to determine whether the solar-wind source is most likely a coronal hole, interstream flow, or a coronal mass ejection. A
simple fuzzy logic scheme operating on measurements of the proton temperature, the alpha-particle abundance, and the presence
of bidirectional streaming of suprathermal electrons was developed for this purpose. Additional requirements on the algorithm
include the ability to identify the passage of forward shocks, reasonable levels of hysteresis and persistence, and the ability
to modify the algorithm by changes in stored constants rather than changes in the software. After a few minor adjustments,
the algorithm performed well during the initial portion of the mission.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
587.
An Exact Trajectory Solution from Doppler Shift Measurements 总被引:2,自引:0,他引:2
Three radar Doppler shift measurements are sufficient to determine the range and velocity, and the angle between them, of a target in uniform rectilinear motion. A solution using derivative approximations has recently appeared. An exact solution in terms of the original measurements is presented here. 相似文献
588.
Efron A.J. Swaszek P.E. Tufts D.W. 《IEEE transactions on aerospace and electronic systems》1992,28(4):932-943
A detector which is designed to operate in a correlated Gaussian-plus-impulsive-noise environment is presented. The detector whitens the data robustly and then uses a two-sided threshold test to determine the presence of impulsive samples. The impulsive samples are discarded, and the remaining samples are used to detect the presence or absence of a signal using a matched filter. An approximate analysis is presented, and simulations are used to demonstrate the effectiveness of this approach 相似文献
589.
The nonstationarity of the low-frequency radar echo envelope observed from an aircraft is shown and a simple model of the echo is suggested. This model, devised specifically for simulation studies using computers, reproduces the characteristics of the observed envelope, demonstrating the correlation between the observed nonstationarity and aircraft motion relative to the receiver. 相似文献
590.
To determine the orbital parameters of a satellite using star occultations, it is necessary to measure the intensity of stars as they occult. The accuracy of the intensity measurements is reduced by interfering sources of light and internal noise, and is expressed in terms of the magnitude of various sources of interference. Subsequently, a specific system is analyzed in detail. Moonlit cloud tops introduce the largest systematic error. Photon noise from the star radiation, airglow, and moonlit cloud tops are the largest sources of random errors. 相似文献