共查询到20条相似文献,搜索用时 31 毫秒
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详细介绍了新产品扩散Bass模型及其各种参数估计方法.模型的参数估计是影响模型准确性的一个重要方面,不同的参数估计方法,会使模型拟含结果相差很大,本文在对以往Bass模型参数估计方法进行分析评述的基础上,介绍了一种新的模型参数估计方法一蚁群算法,通过比较分析,认为蚁群算法将是一种更好的Bass模型参数估计方法. 相似文献
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Semkova JV Dachev TsP Matviichuk YuN Koleva RT Baynov PT Tomov BT Botolier-Depois JF Nguen VD Lebaron-Jacobs L Siegrist M Duvivier E Almarcha B Petrov VM Shurshakov VA Makhmutov VS 《Acta Astronautica》1995,36(8-12):629-638
Radiation risk on a future long-duration manned space mission appears to be one of the basic factors in planning and designing the mission. Since 1988 different active dosimetric investigations has been performed on board the MIR space station by the Bulgarian-Russian dosimeter-radiometer LIULIN and French tissue-equivalent proportional counters CIRCE and NAUSICAA. A joint French-Bulgarian-Russian dosimetry experiment and the dosimetry-radiometry system RADIUS-MD have been developed for the future MARS-96 mission. On the base of the results and experience of these investigations a conception for a new radiation dose control system for the future orbital stations, lunar bases and interplanetary space ships is proposed. The proposed system which consists of different instruments will allow personal radiation control for crew members, radiation monitoring inside and outside each habitat, analysis and forecasting of the situation and will suggest procedures to minimize the radiation risk. 相似文献
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在FD-14A激波风洞中Ma=10流场对前向空腔构型开展试验研究,应用高速阴影技术捕捉弓形激波的平均位置及振荡幅值,利用压力传感器测量空腔底部的脉动压力。在现有无空腔钝头体激波脱体距离预测方法的基础上发展了前向空腔构型的激波脱体距离预测方法,结合国外的试验测量结果与Organ-pipe理论,验证了这种方法的有效性和适用性,且该方法对激波脱体距离的预测结果与FD-14A风洞试验结果一致。此外,基于这种方法讨论了空腔振荡频率预测方法存在的争议。最后,研究了Ma=10流场下球锥体-前向空腔构型的脱体激波振荡幅值与平均速度的规律。 相似文献
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基于先验信息调用成像侦察卫星监控陆地或海洋移动目标动态信息是卫星成像侦察面临的新 课题。在已知移动目标位置等先验信息基础上,动态构造目标可变潜在区域及其运动预测模 型,利用STK辅助构造其候选成像观测活动集合;在此集合及目标运动预测模型基础上 对动态可变区域成像卫星调度问题进行建模,并设计了一种基于模拟退火算法及遗传算法的 改进遗传算法对问题进行求解,得到近最优的移动目标成像侦测方案。最后通过实例及算法 对比验证了规划模型及算法对解决该类问题的合理性和有效性。
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《中国航天(英文版)》2017,(2)
Lightning is a typical example of an instantaneous random point source target. It has close connection with severe convective phenomena such as a thunderstorm, whose distribution, variation, position and forecasting can be acquired through lightning observation. In this paper, we discuss the way to achieve instantaneous lightning signal intensification and detection from geostationary orbit by using the differences between the lightning signal and the slowly changing background noise such as that of cloud, land and ocean, combining three methods, spectral filtering, spatial filtering and background noise, enabling removal between frames. After six months of operation in orbit, lightning within the coverage of the Geostationary Lightning Imager was effectively detected, strongly supporting the case for shorttime and real-time early warning, forecasting and tracking of severe convective phenomena in China. 相似文献
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遗忘因子最小二乘支持向量机及在陀螺仪漂移预测中的应用研究 总被引:4,自引:0,他引:4
以陀螺仪漂移误差系数时间序列预测为对象,研究并提出了遗忘因子最小二乘支持向量机算法。构造了以多项式、径向基、小波函数为核函数的支持向量机(SVM)、最小二乘支持向量机(LSSVM)、遗忘因子最小二乘支持向量机(FFLSSVM),比较了它们用于强非线性测试集的泛化性能。实验结果表明:FFLSSVM比由相应核函数构成的SVM、LSSVM自适应性强、预测精度高;三种核函数生成L2(R)子空间上完备基的能力不同,导致三个FFLSSVM逼近任意目标函数的精度有差异;遗忘因子最小二乘小波核支持向量机可有效地用于陀螺漂移误差动态补偿、可靠性辅助决策、故障预测。 相似文献
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Steven Robert Walk 《Acta Astronautica》2011,68(7-8):853-861
Projecting technology performance evolution has been improving over the years. Reliable quantitative forecasting methods have been developed that project the growth, diffusion, and performance of technology in time, including projecting technology substitutions, saturation levels, and performance improvements. These forecasts can be applied at the early stages of space technology planning to better predict available future technology performance, assure the successful selection of technology, and improve technology systems management strategy.Often what is published as a technology forecast is simply scenario planning, usually made by extrapolating current trends into the future, with perhaps some subjective insight added. Typically, the accuracy of such predictions falls rapidly with distance in time. Quantitative technology forecasting (QTF), on the other hand, includes the study of historic data to identify one of or a combination of several recognized universal technology diffusion or substitution patterns. In the same manner that quantitative models of physical phenomena provide excellent predictions of system behavior, so do QTF models provide reliable technological performance trajectories.In practice, a quantitative technology forecast is completed to ascertain with confidence when the projected performance of a technology or system of technologies will occur. Such projections provide reliable time-referenced information when considering cost and performance trade-offs in maintaining, replacing, or migrating a technology, component, or system.This paper introduces various quantitative technology forecasting techniques and illustrates their practical application in space technology and technology systems management. 相似文献
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空间环境与效应监测数据集成化管理与快速处理是保证航天器在轨安全的重要依据。文章基于航天器空间环境与效应监测数据管理与处理系统的功能要求,给出了系统的组成、架构和数据处理流程。该系统集成了航天器空间环境与效应监测数据的管理、处理、综合分析、参数标定和可视化显示功能,能够实现电子、质子、总剂量、原子氧、温度、表面电位、污染等环境与效应在轨数据的瞬时参数(通量、剂量率、温度变化率、表面电位变化率、污染沉积率)和累积参数(注量、电离总剂量、温度、表面电位、总污染量)的监显,为航天器的在轨健康实时监测、风险快速预报预警提供重要支撑。 相似文献
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无动量干扰的高效率数控扫描系统是环境和灾害监测与预报小卫星红外相机的重要组成部分。文章介绍了这种扫描系统的硬件设计和软件设计。 相似文献
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静止轨道卫星在轨温度参数变化规律研究 总被引:1,自引:0,他引:1
分析了静止轨道在轨三轴稳定卫星各面上温度参数的变化规律,并通过理论计算得到卫星各面上光强的变化曲线,研究了温度参数变化与对应面上光强的关系,建立了温度参数与光线的线性模型,结果表明模型与实际数据能较好地吻合,对温度参数的预测以及故障的判断具有一定的参考价值. 相似文献
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水文遥测系统的多媒体通信网络化体系结构 总被引:1,自引:0,他引:1
由于近年来多媒体通信网络技术的发展,水文自动测报系统还应从‘多媒体’和‘网络化’两个方面作深入的研究。首先讨论遥测系统的‘大环境’,即90年代遥测系统的特点及发展趋势,然后分析和研究水文测报系统的层次划分,网络互连;在此基础上,依照“物理构成”和“逻辑构成”分开的原则,首次建立了多媒体通信网络化的水文测报系统的“逻辑构成”体系结构,即建立了多媒体通信网络化的水文测报系统的体系结构参考模式:HDAS-RM。最后,指出了要做的工作。 相似文献
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动态测量系统的抗扰性预报算法 总被引:8,自引:0,他引:8
为了克服采样数据可能包含的野值对状态预报的不利影响,本文在动态测量系统的有界影响滤波技术的基础上提出了状态预报的两组抗扰性算法,并进行了仿真计算。 相似文献
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In the 25 years since the launch of the first weather satellite, meteorological observations from space have become an essential part of weather forecasting and global environmental monitoring. Beginning in the 1970s, constrained national budgets and the need for a coordinated approach to global satellite observing have caused satellite operators to pursue international cooperation to assure the continuity and compatibility of these systems. This article reviews current bilateral and multilateral cooperation and technical coordination in environmental satellite activities. It also explores the potential for alternative institutional arrangements for maintaining the continuity of environmental satellite data in the decades to come. 相似文献
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This paper reports a first application of contingent valuation method to measure the value of information generated by earth science data from an environmental geostationary satellite payload called Geostationary Environmental Monitoring Satellite. The purpose of the space project is to improve the accuracy of air pollution information by enhancing air pollution monitoring and forecasting system coupled with conventional ground level monitoring stations located throughout South Korea. 相似文献
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The autocovariance prediction method previously used for the forecast of VI derived ionospheric characteristics has been used for forecast of one of the most important ionospheric—the total electron content (TEC)—at single locations. Quiet and disturbed conditions at different European stations were studied in regard to clarify the forecasting capabilities of the method for determination of the TEC. The accuracies of the method achieved in dependence on the time range of the forecast are demonstrated. 相似文献