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1.
Statistical sensitivity measures for gain and phase functions of high Q active networks are studied. Explicit formulas for the sensitivity measures of second-order active RC networks are presented. The formulas obtained are shown to be simple and can be readily calculated for various high Q active RC filters. General formulation of the sensitivity measure for multiple-loop feedback active networks, which use high Q biquadratic active RC networks, is also given.  相似文献   

2.
This paper investigates the fault detectability of Boolean control networks. To deal with different circumstances, passive fault detectability and four types of active fault detectability are proposed for the first time. For passive fault detectability, in line with observed input-output data, several discriminant conditions are put forward. For active fault detectability, by resorting to an auxiliary system, the essence of active fault detectabilty is revealed via reachability. Subsequently, corresponding to different types of active fault detectability, algebraic criteria that facilitate verification are provided. At the same time, the relationships of four types of active fault detectability are discussed as well. In addition, an approach for calculating fault detection time is given by combining passive fault detectability with active fault detectability. Finally, the effectiveness of the results obtained is elaborated by several examples.  相似文献   

3.
In this paper, the problem of active fault tolerant control for a reusable launch vehicle (RLV) with actuator fault using both adaptive and sliding mode techniques is investigated. Firstly, the kinematic equations and dynamic equations of RLV are given, which represent the characteristics of RLV in reentry flight phase. For the dynamic model of RLV in faulty case, a fault detection scheme is proposed by designing a nonlinear fault detection observer. Then, an active fault tolerant tracking strategy for RLV attitude control systems is presented by making use of both adaptive control and sliding mode control techniques, which can guarantee the asymptotic output tracking of the closed-loop attitude control systems in spite of actuator fault. Finally, simulation results are given to demonstrate the effectiveness of the developed fault tolerant control scheme.  相似文献   

4.
谷斌 《情报科学》2002,20(3):320-323
本文论述了当前几种开发Web数据库的主要方案，简明介绍了他们的工作原理，重点介绍了基于ASP技术的Web数据库开发方案，并在此基础上，给出了两种开发动态网页的实例。  相似文献   

5.
王立  封麟先 《科技通报》1992,8(2):78-82
自从Ziegler-Natta催化剂发现以来,人们已对该类催化剂作了许多的研究,以MgCl_2为载体的高效催化剂的巨大成功,引起了人们对载体和过渡金属元素的相互作用的浓厚兴趣,近年来许多文献和专利报道了对复合载体催化剂的大量的研究成果,似有可能出现具有更优特性的高效催化剂. 本文就复合载体催化剂的研究现状作一综述.  相似文献   

6.
This paper addresses an active fault diagnosis problem for a class of discrete-time closed-loop system with stochastic noise. By introducing the theories of system identification, a novel active fault diagnosis method is developed to detect and isolate the faults. An important advantage of the proposed method is that there is no need to cut off the original input signal, which is necessary in most active fault diagnosis methods. Firstly, due to the features of the faults, we transform the problem of fault diagnosis into a problem of model selection by estimating model parameters. Then, the sufficient condition for active fault diagnosability is analysed, and the property that auxiliary input signal can enhance the fault diagnosability is given. Finally, simulation studies are carried out to demonstrate the effectiveness and applicability of the proposed method.  相似文献   

7.
浅析欧盟第七框架计划的新特点   总被引：1，自引：0，他引：1  
欧盟框架计划是西方国家唯一向中国开放的科技计划。从第五框架计划开始,我国的科研机构积极参与其中,开展与欧盟的合作。新启动的第七框架计划具有资金投入规模更大、研究领域更加广泛、资助方式更加灵活、申请程序更加简化等特点。本文详细介绍了这些新特点,并提出了对策和建议。  相似文献   

8.
朱莉 《科教文汇》2011,(29):82-83
在阅读教学中,我十分注重引导学生自主学习、主动探究,为他们动手、动口、动脑提供足够的时间、空间和素材,为他们的个性发展和相互之间的交流提供多种多样的机会,让学生积极地参与学习、主动地进行探究。  相似文献   

9.
Synthesis techniques are given for any one element kind driving point function in two variables, s and x. Conditions for the realization of some two element kind driving point functions in s and x are also developed. Using active elements, any such function is shown to be realizable. Driving point functions in s and x with certain types of fixed (independent of x) and varying (dependent on x) real zeros and poles are shown to be realizable using only F-elements. Applications are presented.  相似文献   

10.
This paper considers vibration control of a single mass flexible rotor on damped flexible supports with active feedback control. Both proportional and derivative feedback control are utilized. Free vibrations and unbalance response of the rotor-control system are determined. The effect of proportional control is to increase the critical speed of rotating machinery while the effect of derivative control is to reduce the amplitude of vibration. Generally larger ratios of support stiffness to shaft stiffness require larger values of control parameters to produce given amplitudes of vibration.  相似文献   

11.
Topological analysis of the signal flow graph associated with the hybrid system of equations for a linear active or passive electrical network for which the element admittance matrix exists and is diagonal is considered. First, the term cancellation which occurs in Mason's topological formulas is investigated. Necessary and sufficient conditions on the signal flow graph topology such that a term in the expansion of the graph determinant and cofactors either cancels out with another term in the expansion or does not cancel are established. Properties of the associated network which result in non-cancelling terms are given and the number of non-cancelling terms is determined. Second, new signal flow graph topological formulas for the graph determinant and cofactors are proven. These formulas are such that no term cancellation occurs and are readily adaptable to computer implementation. In addition, the number of terms in these formulas is independent of the network tree used to formulate the signal flow graph. Examples are given to illustrate the new formulas.  相似文献   

12.
We consider a remote state estimation process under an active eavesdropper for cyber-physical system. A smart sensor transmits its local state estimates to a remote estimator over an unreliable network, which is eavesdropped by an adversary. The intelligent adversary can work in passive eavesdropping mode and active jamming mode. An active jamming mode enables the adversary to interfere the data transmission from sensor to estimator, and meanwhile improve the data reception of itself. To protect the transmission data from being wiretapped, the sensor with two antennas injects noise to the eavesdropping link with different power levels. Aiming at minimizing the estimation error covariance and power cost of themselves while maximizing the estimation error covariance of their opponents, a two-player nonzero-sum game is constructed for sensor and active eavesdropper. For an open-loop case, the mixed Nash equilibrium is obtained by solving an one-stage nonzero-sum game. For a long term consideration, a Markov stochastic game is introduced and a Nash Q-learning method is given to find the Nash equilibrium strategies for two players. Numerical results are provided to show the effectiveness of our theoretical conclusions.  相似文献   

13.
Matrix and operational methods together provide a compact, convenient and systematic solution of transients. This paper illustrates the application of these methods to the solution of active four-terminal networks. First, the matrices are written with the Laplacian operator, s, as the parameter. Second, the vacuum tube as a four-terminal network is reviewed. Third, an example is given which illustrates the use of the method.  相似文献   

14.
核心期刊评价及其负面效应   总被引：20，自引：2，他引：20  
李玉进 《情报科学》2002,20(12):1257-1259
核心期刊评价具有重要的学术意义和积极的社会效应。然而，其评价方法、结果及其采信的过程，也会形成一定的负面效应，对此应当给予客观的认识和重视。  相似文献   

15.
Bond graphs are used to generate the equations of motion of a whirling flywheel. The formulation is shown to be a natural one when control forces and moments are included for active control of the whirling modes. Critical frequencies are interpreted as rotational speeds at which non-zero equilibrium configurations exist for displacements (as opposed to the more familiar momenta) and arise when the system dynamics matrix of the complete whirl motion has two zero eigenvalues. In addition, oscillatory modes corresponding to non-zero eigenvalues are examined. Time simulations and other numerical results are given for an example flywheel system which has been proposed for electric utility energy storage.  相似文献   

16.
手势在人机交互中的应用是非常普遍的。本文给出了一种基于约束模型的主动约束捕捉的数据结构。在此基础上分析研究了用于笔式用户界面几何教学系统中的手势识别技术。进而提出了主动约束捕捉的求解算法,最后阐述了手势在笔式几何系统中的应用。  相似文献   

17.
New active distributed RC-structures utilizing exponential RC-lines and operational amplifiers are proposed for realizing band-pass transfer functions and transfer functions having both a pair of complex poles and a pair of complex zeros. It is shown that the magnitude of the amplifier gain for a given pole Q decreases with increasing taper. In the case of the structures realizing both complex poles and zeros, it is shown that the sensitivity with respect to the gain of the pole-determining amplifier is considerably lower than that of the previously proposed structures.  相似文献   

18.
A general theory is developed for extended bandwidth operation of actively compensated finite gain amplifiers. Designs for three new circuits are given which implement the theory. These circuits employ only operational amplifiers and resistors and their gains depend only on their resistor ratios. Thus they are suitable for IC fabrication. Further in IC technology, the characteristics of the operational amplifiers as well as the resistor ratios track closely with each other with reference to temperature and aging. Thus the extended bandwidth operation of the amplifiers will be available over a wide temperature range as well as under varying aging conditions. Their characteristics can be tuned easily by trimming only two resistors. Applications of the new amplifiers have been considered in RC active filters as well as in inductance simulation schemes. Experimental results are given which closely agree with theoretical predictions. The results also indicate that substantial improvement in the usable bandwidth of the circuits employing the new amplifiers may be expected over those using the conventional design of finite gain amplifiers.  相似文献   

19.
In this paper, the problem of stabilization for a class of switched delay systems with polytopic type uncertainties under asynchronous switching is investigated. When the switching of the controllers has a lag to the switching of subsystems, i.e. the switching signal of the switched controller involves delay, parameter-dependent Lyapunov functionals are constructed, which are allowed to increase during the running time of active subsystems with the mismatched controller. Based on the average dwell time method, sufficient conditions for exponential stability are developed for a class of switching signals. Finally, a river pollution control problem is given to demonstrate the feasibility and effectiveness of the proposed design techniques.  相似文献   

20.
A general matching theory between an arbitrary passive impedance and an active load impedance is presented. It extends the broadband matching theory to include both lossless reciprocal and nonreciprocal networks. Application of the result to the design of nonreciprocal negative-resistance amplifier is given. The significance of the present approach is that the realization of the equalizer is accomplished by means of the driving-point synthesis based on the Darlington theory. The result enlarges the domain of realizable broadband matching networks.An illustrative example is presented to show the design procedure and the conditions under which a lossless nonreciprocal network is realized for an active load.  相似文献   

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