共查询到20条相似文献,搜索用时 15 毫秒
1.
顺轨拦截模式剩余飞行时间估计方法 总被引:1,自引:0,他引:1
匹配顺轨和逆轨拦截模式的估计方法是精确计算剩余飞行时间(TGO)的必要条件,适用于逆轨拦截模式的TGO估计方法并不适于顺轨拦截模式。为此,针对顺轨拦截模式,分别提出了拦截机动/非机动目标的TGO估计方法。通过对线性制导方程的变形求解出了拦截弹的飞行弧长,并根据预测的碰撞点位置求得了TGO估计的解析式。该求解方法通用性强,适用于弹道成型制导律的TGO估计。以负比例(RPN)和扩展RPN(ARPN)为制导框架,与经典方法进行对比,所提出的TGO估计方法精确度高,能够有效提高导弹的制导性能。 相似文献
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Kelly S.W. Noone G.P. Perkins J.E. 《IEEE transactions on aerospace and electronic systems》1996,32(1):213-220
Expressions for the probability of coincidence between pairs of pulse trains are examined. The application to systems of interest in the field of electronic warfare is emphasized. Theoretical results for the limit of uncorrelated pulse trains are reviewed and new theory is developed to cover the case of coincidence between uniform pulse trains where the coincidence phenomena may be highly correlated. Monte Carlo experiments show that increasing the jitter level on one of the pulse trains causes a transition between the correlated and uncorrelated regimes 相似文献
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Brierley S.D. Longchamp R. 《IEEE transactions on aerospace and electronic systems》1990,26(2):306-325
A sliding-mode control (SMC) law is applied to a nonlinear system representing an air-air missile-target interception process. Promising results are obtained for a simple switching surface based on proportional navigation (PN). Partial robustness of the controller is demonstrated, i.e. the control is robust only with respect to uncertainties present in the control dynamics. This is illustrated by a breakdown in the control actuator for which SMC was found to be superior to PN 相似文献
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针对传统火力分配模型容易造成资源浪费的问题,将火力单元以组为单位,以最大化杀伤概率为目标,构建一种具有多次拦截时机的动态火力分配模型;考虑到组内火力单元复合打击的情况,使用Kuhn-Munkres算法,优先将目标分配给复合打击效果大的目标;在此基础之上,设计了一种基于遗传算法(GA)的Anytime算法,引入了元级控制,提出一种任意时刻算法停机时刻的判定方法;仿真实验验证了模型优越性以及算法的合理性,对火力分配任意时刻算法使用元级控制可以有效提高解的效用。 相似文献
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文中介绍了电磁发射拦截系统的组成及工作原理,建立了发射线圈组件的三维模型。对不同匝间距和不同截面高度的发射线圈进行了磁场分析,得到了拦截弹所受电磁力的变化规律。 相似文献
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《COSPAR's Information Bulletin》1986,1986(105):100-101
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Burgos-Garcia M. Sanmartin-Jara J. Perez-Martinez F. Retamosa J.A. 《Aerospace and Electronic Systems Magazine, IEEE》2000,15(4):23-28
One of the best known weakness of radar sensors in defense and security applications is the necessity to radiate a signal, which can be detected by the target, so being possible (easy in fact) that the target is alerted about the presence of a radar before the radar is alerted about the presence of a target. In this context, Low Probability of Interception (LPI) Radars try to use signals that are difficult to intercept and/or identify. Spread spectrum signals are strong candidates for this application, and systems using special frequency or polyphase modulation schemes are being exploited. Frequency hopping, however, has not received much attention. The typical LPI radar at this moment of the technology is a CW-LFM radar. The simplicity of the technology is its best point. Polyphase codes, on the other hand have the inherent advantage of high instantaneous bandwidth regardless of observation time. But the complexity of the hardware is also higher. FH signals have traditionally been considered of lower performance but higher complexity, due to the difficulties to compensate the individual dopplers for the individual range cells in the receiver. One important point is that an FH radar must be clearly distinguished from an agile frequency radar. In the latter, a pulsed signal is transmitted using different frequencies from pulse to pulse. In an FH radar the frequency changes must be during the pulse. In fact, in an LPI FH radar, a CW frequency hopped signal is used. A radar system concept is proposed in which it shows how these problems can be overcome in a tracking application. Also, the signal format is analyzed under the scope of future decade digital interceptors, showing that, in fact, this kind of signal exhibits improvement in some performances and requires a hardware that is only slightly more complex than that needed for CW-LFM systems 相似文献
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G. Kockarts 《Space Science Reviews》1973,14(6):723-757
After a brief historical review of the discovery of helium in the terrestrial atmosphere, the production mechanisms of the isotopes He4 and He3 are discussed. Although the radioactive production of He4 in the Earth is well understood, some uncertainty still exists for the degassing process leading to an atmospheric influx of (2.5 ±1.5) × 106 atoms cm–2 s–1. Different production mechanisms are possible for He3 leading to an influx of (7.5±2.5) atoms cm–2 s–1. Observations of helium in the thermosphere show a great variability of this constituent. The different mechanisms proposed to explain the presence of the winter helium bulge are discussed. Since helium ions are present in the topside ionosphere and in the magnetosphere, ionization mechanisms are analyzed. Owing to possible variations and uncertainties in the solar UV flux, the photoionization coefficient is (8±4) × 10–8 s–1. Finally, the helium balance between production in the earth and loss into the interplanetary space is discussed with respect to the different processes which can play an effective role. 相似文献
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连续下降运行(CDO)是基于航迹运行(TBO)概念的重要组成,对于减少机场终端区燃油消耗和环境影响具有显著效果。简洁、高效和灵活的进场空域,以及高度自动的无冲突节能轨迹规划,是实现高密度终端区连续下降运行的核心要素。设计了一种融合Point Merge理念的新型倒皇冠形进场空域(ICSAA),规范了新型空域内航空器运行程序,建立了以燃油消耗和飞行时间最小为目标的连续下降进近无冲突四维轨迹优化模型,并选用基于精英保留策略的非支配排序遗传算法(NSGA-Ⅱ)进行高效求解。论证了新型柔性空域下连续下降运行轨迹优化具备复杂高密度场景预战术和战术运行性能,对于飞行效率、经济性和空域容量提升具有显著效果,为促进繁忙机场全时段连续下降运行的推广应用提供新视角和新方法。 相似文献
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对高超声速流中带有热防护系统(TPS)的二维壁板进行了热气动弹性的双向耦合建模与分析,采用三阶活塞理论计算气动力,通过参考焓法获得气动热流,在有限差分法的基础上进行结构热传导计算,拟合了结构材料特性随温度退化的曲线,最后将气动热模块、气动弹性模块进行双向耦合以考虑气动热与结构形变之间的相互反馈,并在2种典型弹道状态下进行热气动弹性响应分析。结果表明,在X-34A的设计弹道下,双向耦合分析会引起更加剧烈的热应力与热弯矩的变化与较长的瞬态混沌过程。在FALCON弹道下,双向耦合得到的结果加热更为剧烈,而温度下降的过程也更快。对比2种弹道发现,长时间的高超声速飞行更容易引发颤振,而机动性较强的弹道面临的主要问题则是屈曲,需要考虑材料的应力及强度特性。同时说明了双向耦合策略对于现代飞行器在弹道状态下工作的热气弹响应分析的必要性。 相似文献
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V. I. Moroz 《Space Science Reviews》1981,29(1):3-127
The investigations of Venus take a special position in planetary researches. It was just the atmosphere of Venus where first measurements in situ were carried out by means of the equipment delivered by a space probe (Venera 4, 1967). Venus appeared to be the first neighbor planet whose surface had been seen by us in the direct nearness made possible by means of the phototelevision device (Venera 9 and Venera 10, 1975). The reasons for the high interest in this planet are very simple. This planet is like the Earth by its mass, size and amount of energy obtained from the Sun and at the same time it differs sharply by the character of its atmosphere and climate. We hope that the investigations of Venus will lead us to define more precisely the idea of complex physical and physical-chemical processes which rule the evolution of planetary atmospheres. We hope to learn to forecast this evolution and maybe, in the far future, to control it. The last expeditions to Venus carried out in 1978 — American (Pioneer-Venus) and Soviet (Venera 11 and 12) — brought much news and it is interesting to sum up the results just now. The contents of this review are:
- The planet Venus — basic astronomical data.
- Chemical composition.
- Temperature, pressure, density (from 0 to 100 km).
- Clouds.
- Thermal regime and greenhouse effect.
- Dynamics.
- Chemical processes.
- Upper atmosphere.
- Origin and evolution.
- Problems for future studies
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Andrew P. Ingersoll 《Space Science Reviews》1976,18(5-6):603-639
Current information on the neutral atmosphere of Jupiter is reviewed, with approximately equal emphasis on composition and thermal structure on the one hand, and markings and dynamics on the other. Studies based on Pioneer 10 and 11 data are used to refine the atmospheric model. Data on the interior are reviewed for the information they provide on the deep atmosphere. The markings and dynamics are discussed with emphasis on qualitative relationships and analogies with phenomena in the Earth's atmosphere.Contribution No. 2652 of the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, Calif. 91125, U.S.A. 相似文献
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The problem of bearings-only target localization is to estimate the location of a fixed target from a sequence of noisy bearing measurements. Although, in theory, this process is observable even without an observer maneuver, estimation performance (i.e., accuracy, stability and convergence rate) can be greatly enhanced by properly exploiting observer motion to increase observability. This work addresses the optimization of observer trajectories for bearings-only fixed-target localization. The approach presented herein is based on maximizing the determinant of the Fisher information matrix (FIM), subject to state constraints imposed on the observer trajectory (e.g., by the target defense system). Direct optimal control numerical schemes, including the recently introduced differential inclusion (DI) method, are used to solve the resulting optimal control problem. Computer simulations, utilizing the familiar Stansfield and maximum likelihood (ML) estimators, demonstrate the enhancement to target position estimability using the optimal observer trajectories 相似文献
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A problem of evaluating disturbance significance in the statistic analysis of recovery capsule motion in atmosphere is considered.
We present the results of comparing several methods, namely, iteration method of least squares, statistic linearization method
and statistic test method (independently for each disturbance). The methods are compared using as an example the calculation
of landing point scatter for a spherical recovery capsule that is returned from the orbit by means of a cable system. 相似文献
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《中国航空学报》2023,36(6):201-212
This paper proposes a fast calculation method to solve all mission opportunities for orbital interception and orbital rendezvous under the impulse-magnitude constraint. Different from the existing search methods, the proposed method does not need to solve Lambert’s problem in the whole process. Three cases are considered for either departure time or transfer time being free, or both being free. For fixed departure time, the feasible windows of transfer time are obtained by solving a single-variable nonlinear equation only of terminal true anomaly. Similarly, for fixed interception (or rendezvous) time, the feasible windows of departure time are obtained. For free departure time and free transfer time, all mission opportunities are obtained by using a one-dimensional search strategy. The hyperbolic-transfer and the multiple-revolution cases are also analyzed. Numerical results show that the proposed method is superior to the typical pork-chop plot method and the two-dimensional launch window method in computational time. 相似文献
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空间目标逆轨网捕拦截停泊轨道的优化设计 总被引:1,自引:0,他引:1
为了提高对空间目标的拦截成功率,可采用拦截器从停泊轨道转移进入拦截轨道逆轨网捕拦截的方式。利用椭圆弹道理论,讨论和分析了该拦截方式停泊轨道优化问题的描述、模型的建立及优化的方法。计算结果表明,对该拦截方式所建立的模型和采用的优化方法满足逆轨拦截对轨道设计的要求,可为空间快速拦截应用提供理论借鉴和参考。 相似文献