某型导弹控制系统的鲁棒稳定性分析

研究了导弹控制系统的鲁棒稳定性。首先建立了导弹的广义状态空间模型， 针对这类难以转化为标准一阶状态空间模型或转化后少数不确定参数将以复杂的非线性函数方式扰动整个参数矩阵系统的特点， 建立了由广义模型描述不确定系统的鲁棒稳定性判据， 将其化为线性矩阵不等式（ Ｌ Ｍ Ｉ） 的形式， 从而用凸优化算法来判定。最后将所得到的结果应用于某型导弹控制系统的鲁棒稳定性分析。结果表明在所设计的控制律下， 在攻击过程中为鲁棒稳定。     

Detection of random signals via spectrum matching

Using a priori knowledge of the signal power spectral density (PSD), a spectrum matching approach which effectively utilizes the available signal spectral shape is developed for random signal detection. Two spectrum matching detector (SMD) structures, which are implemented by correlogram and periodogram, respectively, are examined. Theoretical calculation of their false alarm rates is derived and confirmed by simulations. It is also demonstrated that the proposed detectors outperform the standard periodogram, Bartlett method, and energy detector under constant false alarm rate (CFAR) condition for two different random signals.     

THE ELECTRON DRIFT INSTRUMENT FOR CLUSTER

The Electron Drift Instrument (EDI) measures the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one or more gyrations. This drift is related to the electric field and the gradient in the magnetic field, and these quantities can, by use of different electron energies, be determined separately. As a by-product, the magnetic field strength is also measured. The present paper describes the scientific objectives, the experimental method, and the technical realization of the various elements of the instrument.     

Modelling of Solar Wind, CME Initiation and CME Propagation

Simulations of coronal mass ejections (CMEs) evolving in the interplanetary (IP) space from the Sun up to 1 AU are performed in the framework of ideal magnetohydrodynamics (MHD) by the means of a finite-volume, explicit solver. The aim is to quantify the effect of the background solar wind and of the CME initiation parameters, such as the initial magnetic polarity, on the evolution and on the geo-effectiveness of CMEs. First, three different solar wind models are reconstructed using the same numerical grid and the same numerical scheme. Then, different CME initiation models are considered: Magnetic foot point shearing and magnetic flux emergence. For the fast CME evolution studies, a very simple CME model is considered: A high-density and high-pressure magnetized plasma blob is superposed on a background steady state solar wind model with an initial velocity and launch direction. The simulations show that the initial magnetic polarity substantially affects the IP evolution of the CMEs influencing the propagation velocity, the shape, the trajectory (and thus, the geo-effectiveness).     

Mapping Magnetospheric Equatorial Regions at Saturn from Cassini Prime Mission Observations

Saturn??s rich magnetospheric environment is unique in the solar system, with a large number of active magnetospheric processes and phenomena. Observations of this environment from the Cassini spacecraft has enabled the study of a magnetospheric system which strongly interacts with other components of the saturnian system: the planet, its rings, numerous satellites (icy moons and Titan) and various dust, neutral and plasma populations. Understanding these regions, their dynamics and equilibria, and how they interact with the rest of the system via the exchange of mass, momentum and energy is important in understanding the system as a whole. Such an understanding represents a challenge to theorists, modellers and observers. Studies of Saturn??s magnetosphere based on Cassini data have revealed a system which is highly variable which has made understanding the physics of Saturn??s magnetosphere all the more difficult. Cassini??s combination of a comprehensive suite of magnetospheric fields and particles instruments with excellent orbital coverage of the saturnian system offers a unique opportunity for an in-depth study of the saturnian plasma and fields environment. In this paper knowledge of Saturn??s equatorial magnetosphere will be presented and synthesised into a global picture. Data from the Cassini magnetometer, low-energy plasma spectrometers, energetic particle detectors, radio and plasma wave instrumentation, cosmic dust detectors, and the results of theory and modelling are combined to provide a multi-instrumental identification and characterisation of equatorial magnetospheric regions at Saturn. This work emphasises the physical processes at work in each region and at their boundaries. The result of this study is a map of Saturn??s near equatorial magnetosphere, which represents a synthesis of our current understanding at the end of the Cassini Prime Mission of the global configuration of the equatorial magnetosphere.     

Nonlinear robust observer design for strapdown INS in-flight alignment

A nonlinear observer is proposed for a strapdown inertial navigation system (SDINS) in-flight alignment problem using an H/sub /spl infin// filter Riccati equation and a freedom parameter. The proposed observer improves the filtering stability, convergence, and performance. The characteristics of the observer are analyzed using a Lyapunov function. Simulation results demonstrate a significant reduction in alignment errors by employing the proposed nonlinear observer. The observer is developed in general such that it can be applied to estimating nonlinear systems other than the SDINS in-flight alignment.     

综合质量管理系统的一种方法(英文)

ＩＳＯ９０００认证已被制造业视为一种有效的竞争优势。在香港，ＩＳＯ９０００认证已获得广泛采纳，并已伸延至服务行业，藉以提高公司形象。不过，不少取得认证的公司因抱怨原因而将文件工作、非直接生产员工及过多资源转投在非核心业务方面。本文旨在推荐一套既能专注于主要业务，又能灵活地结合其他管理标准，如ＩＳＯ９０００、ＩＳＯ１４０００及将来ＩＳＯ１８０００要求的“综合管理系统”。本文最后阐述了如何实施建议的综合管理系统，以达到理想的业务表现。     

香港制造业追求质量文化的高峰(英文)

竭力提高产品质量是现今香港企业之首要目标之一。有效的质量管理，可以使企业在这竞争激烈的国际市场中赢得顾客的信任，并不断提高市场占有率，此为企业竞争之重要策略。因此香港企业需要建立品质管理文化，将企业中所有员工团结一致，尽量提高产品质量，以达到国际级数。本文引用麦坚士（Ｍｃｋｉｎｓｅｙ）之７－Ｓ模式（ｆｒａｍｅ－ｗｏｒｋ）：策略（Ｓｔｒａｔｅｇｙ）、架构（ｓｔｒｕｃｔｕｒｅ）、系统（ｓｙｓｔｅｍ）、员工（ｓｔａｆ）、性格（ｓｔｙｌｅ）、技术（ｓｋｉｌ）、目标（ｓｕｐｅｒｏｒｄｉｎａｔｅｇｏａｌｓ），藉以探索香港优秀企业之品质文化。最后结论为卓越领导人才是推行企业文化之重要因素。     

Variable structure and adaptive control of a synchronous generator

Damping of synchronous generator oscillations has been investigated by using three types of controllers, i.e., the PI (proportional-integral) controller, the model reference adaptive controller (MRAC) and the variable-structure model-following controller (VSMFC). It was found that the PI controller fails to accommodate itself to the situation where there is a significant change in generator loading conditions. The MRAC greatly improves the dynamic responses of the generator over a wide range of operating conditions by minimizing the error in the responses obtained from the plant with a specified reference model. The damping of the generator is further improved by the VSMFC, which reduces the sensitivity of generator responses relative to plant parameter variations by providing sliding-mode operations     

Sequential localization of a radiating source by Doppler-shiftedfrequency measurements

For a single omnidirectional sensor in contact with a constant velocity source that radiates a constant frequency tone, the measurements of the Doppler-shifted frequencies over time do not provide sufficient information to localize the source. Instead, only the parameters of source rest frequency, speed, and range relative to a sensor can be determined. However, if over time three or more sensors sequentially come in contact with the source, the source trajectory can then be specified. This is termed sequential localization. A two-dimensional grid search technique to find the Doppler parameters from measurements taken by a single sensor alone is presented. From these parameters, it is next shown how sequential localization is accomplished. Two simulation examples are provided to verify the development. The localization root mean squared errors (RMSEs) are found to be very close to the Cramer-Rao bound