摘要:

A target recognition system based on the concept of fuzzy set theory and homomorphic system is proposed. It involves automatic threshold selection, feature extraction, and classification. An optimal threshold is selected by the fuzzy risk criterion, i.e. to separate a given image into meaningful grey level classes under the assumption that the object and pixel grey level values are normally distributed. An edge measure for evaluating thresholding methods is also presented. When an image is segmented, a set of invariant features called mean, variance, skewness, and kurtosis, which are derived from the spectrum histogram of the target image, is calculated. The classification is then accomplished using the membership function of the feature space of an image and stored patterns. By simulation results, we find that the fuzzy risk thresholding achieves significant performance according to the uniformity and edge measures, and the fuzzy filter with the invariant features has good performance even in low signal-to-noise ratio conditions.

ISSN:0020-7721    

DOI:10.1080/00207729308949607

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A problematic feature in most fermentation processes is that on-line measurement of the most important biological process variables, the concentration of the bio-mass and its specific growth rate, cannot be directly measured. An approach for estimating these biological variables and for controlling the specific growth rate in a continuous flow bioprocess of a stirred tank reactor is presented and analysed. The goal in the control is to get the specific growth rate to track the rate of a given reference model, A dynamic model for the specific growth rate is obtained from the general growth and substrate consumption model. The structure of the rate model is then applied in the reference model structure. The methodology studied is based on two issues, joint state and parameter estimation and direct adaptive control. From the theoretical viewpoint, this forms a combination of indirect and direct adaptive control. The structure of the control law is justified by the structure of the law obtained for known fixed parameters. Convergence of the estimation scheme and of the adaptive control scheme are demonstrated via Lyapunov's method, and separately. The choice of the appropriate Lyapunov function results in a Pl-type controller with the gains as the parameters to be adjusted by the user. A simulation study based on Monod's model and time-varying model parameters and subject to measurement noise shows the feasibility and robustness of the adaptive control methodology developed for this non-linear process.

ISSN:0020-7721    

DOI:10.1080/00207729308949608

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An associative memory with parallel architecture is presented. The neurons are modelled by perceptrons having only binary, rather than continuous valued input. To storemelements each havingnfeatures,mneurons each withnconnections are needed. Thenfeatures are coded as ann-bit binary vector. The weights of thenconnections that store thenfeatures of an element has only two values -1 and 1 corresponding to the absence or presence of a feature. This makes the learning very simple and straightforward. For an input corrupted by binary noise, the associative memory indicates the element that is closest (in terms of Hamming distance) to the noisy input. In the case where the noisy input is equidistant from two or more stored vectors, the associative memory indicates two or more elements simultaneously. From some simple experiments performed on the human memory and also on the associative memory, it can be concluded that the associative memory presented in this paper is in some respect more akin to a human memory than a Hopfield model.

ISSN:0020-7721    

DOI:10.1080/00207729308949609

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Dual problems, which we call output and input variance constrainedH2/H∞controls, are considered. In these problems, we seek control-laws that satisfy mixedH2/H∞performance criteria, under multiple variance constraints on either outputs or inputs of time-invariant multivariable systems. The approach taken is to convert the problems into non-linear programming with both equality and inequality constraints. For both problems, the Kuhn-Tucker optimality condition is employed to obtain a first-order necessary condition for a regular point that minimizes an upper bound on the quadratic performance for the givenH∞constraint. A second-order necessary condition and sufficiency for the strict local minimizer of the upper bound are investigated. Efficient algorithms for synthesizing the desired controllers are proposed.

ISSN:0020-7721    

DOI:10.1080/00207729308949610

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The stabilization problem of general second-order single-input dynamical systems is discussed. This class of linear or non-linear dynamical systems contains some uncertainties. A new robust discontinuous controller is proposed to guarantee asymptotic stability of general dynamical systems with bounded uncertainties. Then, to guarantee the continuity of the control, a quasi-saturation function is introduced into the control law and guaranteed eventual stability-in-the-large (ESL) of the dynamical systems is proved. Some examples and simulations are given to illustrate the effectiveness of the robust continuous controller. The control signals are indeed continuous and smooth while maintaining the desired performance of the system.

ISSN:0020-7721    

DOI:10.1080/00207729308949611

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A method of designing a generalized minimum variance self-tuning controller with a special pole-zero assignment technique for setpoint tracking and disturbance rejection is presented. Both minimum phase and non-minimum phase systems are considered to achieve perfect and imperfect setpoint tracking and disturbance rejection, respectively. The problem of matching unity inH∞-norm space is discussed, and a new method to match unity in another sense is developed. With parameter identification, an on-line self-tuning algorithm with the property of setpoint tracking and disturbance rejection is proposed. The effectiveness of the algorithm is shown by an example.

ISSN:0020-7721    

DOI:10.1080/00207729308949612

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A special class of context-sensitive generative languages (CSGLs) that can be used as an indexation in parallel computing is described. The languages are recursively generated, and the algorithm for interprocesses communication is based on the positive resolution of the post correspondence problem (PCP) within CSGLs. This fact follows from the main result that a constructed CSGL has a complete set of production rules, i.e. no new rule can be added to the set without destroying the integrity of the CSGL.

ISSN:0020-7721    

DOI:10.1080/00207729308949613

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

State estimation for fixed-bed reactors based on reduced bilinear models is presented, with a typical laboratory-scale plant as an example. The reactor is described by a quasi-homogeneous non-linear distributed model. The reduced bilinear model developed in previous works, which can be considered as a singularly perturbed bilinear model, can be approximated by a bilinear model with polynomial inputs. A new bilinear system observer design approach via pole-placement techniques is proposed. The observer is applied to estimate the temperatures of the fixed-bed reactor at the axial orthogonal collocation points using only a few temperature measurements. The temperature and concentration profiles can be obtained by the state of the observer. The efficiency of the suggested model simplification method and bilinear system observer design approach is successfully tested in non-linear simulation studies. It is shown that the observer developed, based on the reduced bilinear model, can give an excellent estimation of the dynamic behaviour of the fixed-bed reactor for the cases considered.

ISSN:0020-7721    

DOI:10.1080/00207729308949614

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A stochastic approach to the security evaluation of a dynamic system is presented. The mean first passage time (MFPT) of a multi-dimensional system from its domain of attraction is defined as a security measure, and a closed form expression for the asymptotic estimate of the MFPT is derived. The proposed method encompasses various multi-dimensional dynamic systems, and the analysis of a power system model is used as a case study. The power system is represented by a multi-bus constant voltage, constant impedence model, and the assumption of low damping is waived to widen the application of the results. In this study, small perturbations in dynamic systems have been modelled as weak wideband gaussian coloured noises. Corresponding sensitivity results for a 19-bus power system are presented.

ISSN:0020-7721    

DOI:10.1080/00207729308949615

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A three stage approach to the development of multi-agent systems is proposed involving functional decomposition, agent representation, and information flow integration. The information flow integration stage is discussed in detail. A rule-based agent integration for construction of autonomous subsystems and systems useful in integrated manufacturing is presented. The approach formalizes the integration process that a system analyst solves in anad hocmanner. The approach presented facilitates the discovery of new integrated manufacturing solutions. It involves generation of a set of autonomous agents for building an overall system. Hierarchically structured subsystems are developed at different levels of abstraction that parallel the approach used by an expert system analyst. The implementation of an integration process in an object-oriented programming environment is also suggested.

ISSN:0020-7721    

DOI:10.1080/00207729308949616

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor