System identification based on physical laws often involves parameter estimation. Even if parameters are theoretically identifiable, they may be poorly estimable for a given experiment. Thus a significant increase in ...
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System identification based on physical laws often involves parameter estimation. Even if parameters are theoretically identifiable, they may be poorly estimable for a given experiment. Thus a significant increase in accuracy of the parameter estimation may be obtained by a suitable choice of experimental conditions. The original idea of this paper is the combination of a dynamical programming method with a gradient algorithm in the solution of the optimal design. After getting an optimal input, the parameter estimation is performed by minimizing a weighted least square criterion. Weights are either based on the known measurement noise or given by the solution of a linear matrix inequality problem.
A method is presented for modeling the behavior of fish in a water tank. The motion of fish is described mathematically by nonlinear state equations, in which the main causes for the motion are expressed as the compon...
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A method is presented for modeling the behavior of fish in a water tank. The motion of fish is described mathematically by nonlinear state equations, in which the main causes for the motion are expressed as the components of the external force. A water tank experiment is carried out for obtaining the observation records of fish behavior. The time series data of the position for each fish is calculated from the image data recorded by a video tape. With regard to the situation of fish behavior records, a robust parameter estimation algorithm is proposed by applying the probabilistic data association approach to the least squares algorithm and the usual robust algorithm. As a case study, the parameters included in the model are identified by using the proposed algorithm as well as the least squares algorithm.
The presented method for nonlinear system identification is based on the LOLIMOT algorithm introduced by Nelles and Isermann [1996]. The LOLIMOT algorithm divides the input space by a tree-construction algorithm and i...
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The presented method for nonlinear system identification is based on the LOLIMOT algorithm introduced by Nelles and Isermann [1996]. The LOLIMOT algorithm divides the input space by a tree-construction algorithm and interpolates the local linear models by local membership functions. Instead of assuming local linear models, the presented algorithm utilizes general local nonlinear functions, which make the algorithm more flexible. These are approximated by a multidimensional Taylor series. Since the amount of regressors grows fast with the number of inputs and the expansion order, a subset selection procedure is introduced. It reveals significant regressors and gives information about the local functional behavior. The local subset selection is implemented as a stepwise regression with replacement of regressors. Mallows’ C p -statistic is used for the subset selection algorithm and is also implemented for final model selection. The benefit of the extended algorithm lies in the higher flexibility in the local models, which results in less partitions of the input space by a similar approximation quality.
During the operation of air separation units(ASU), planned short-term shutdowns are often required to ensure a balance between supply and demand of downstream air separation products, and maintain equipment performanc...
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During the operation of air separation units(ASU), planned short-term shutdowns are often required to ensure a balance between supply and demand of downstream air separation products, and maintain equipment performance and ensure production safety. Making the device shut down smoothly and safely is a key measure in air separation production. However, this process highly relies on manual participation and carries risks and uncertainties. In response to this practical demand, we propose an ASU Shutdown operation flow assistance system(SOFAS). We firstly build a standard logical model based on the actual shutdown process and develop algorithms to assist in executing standardized and safe shutdown operations. Then, we propose an operation flow identification algorithm to identify the shutdown operation flow, and an evaluation algorithm to quantitatively analyze the efficiency and safety of the operation flow using two performance indicators. Finally, the effectiveness of the method was verified through experimental analysis using the actual operational data of ASU.
A sequential state estimation routine was developed to allow for the incorporation of constraints into their estimates. In this effort, the application of this powerful state estimator to the problem where parameters ...
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ISBN:
(纸本)9781627481199
A sequential state estimation routine was developed to allow for the incorporation of constraints into their estimates. In this effort, the application of this powerful state estimator to the problem where parameters of the system model are incorporated into the state vector is examined. The research has looked at the issues that arise in both the open-loop implementation, such as occurs in the target tracking application, and the closed-loop implementation that occurs in the feedback control problem. This effort is aimed toward system identification of parameters that have hard limits on their values. This type of parameter estimation can provide the foundation for a training paradigm for elliptical basis functions in neural networks.
In this paper, a recursive stochastic gradient algorithm based on two-step update estimation and an iterative stochastic gradient algorithm based on two-step update estimation are established for the Wiener system by ...
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ISBN:
(纸本)9781509015740;9781509015733
In this paper, a recursive stochastic gradient algorithm based on two-step update estimation and an iterative stochastic gradient algorithm based on two-step update estimation are established for the Wiener system by introducing a relaxation factor, which controls the relative importance of the two estimation parts. In addition, the convergence performance of the proposed SG-TSU and ISG-TSU algorithms are then analyzed. It is shown by a numerical example that if the relaxation factor is appropriately chosen, the proposed SG-TSU and ISG-TSU algorithms converge more quickly and have higher convergence precision than the standard SG and ISG algorithms, respectively.
The spontaneous internal short circuit is a very important way for the thermal runaway of lithium-ion battery. identification of the internal short circuit accurately and in time during the working process is critical...
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The spontaneous internal short circuit is a very important way for the thermal runaway of lithium-ion battery. identification of the internal short circuit accurately and in time during the working process is critical for the safety of lithium-ion battery. In this study, a modified algorithm for the early-stage internal short circuit identification is investigated. This method is based on the mean-difference model and the recursive least square algorithm. An equivalent experiment is setup to validate the feasibility of this method for the identification of early-stage internal short circuit. The results indicate that this method can identify the internal short circuit only when the SOC is very low. For ordinary operation conditions of the power battery pack, this method is not suitable for early-stage internal short circuit identification.
Recently, a new finite-sample system identification algorithm, called Sign-Perturbed Sums (SPS), was introduced in [2]. SPS constructs finite-sample confidence regions that are centered around the least squares estima...
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ISBN:
(纸本)9781467357159
Recently, a new finite-sample system identification algorithm, called Sign-Perturbed Sums (SPS), was introduced in [2]. SPS constructs finite-sample confidence regions that are centered around the least squares estimate, and are guaranteed to contain the true system parameters with a user-chosen exact probability for any finite number of data points. The main assumption of SPS is that the noise terms are independent and symmetrically distributed about zero, but they do not have to be stationary, nor do their variances and distributions have to be known. Although it is easy to determine if a particular parameter belongs to the confidence region, it is not easy to describe the boundary of the region, and hence to compactly represent the exact confidence region. In this paper we show that an ellipsoidal outer-approximation of the SPS confidence region can be found by solving a convex optimization problem, and we illustrate the properties of the SPS region and the ellipsoidal outer-approximation in simulation examples.
Abstract. An innovation state space modelling approach is presented in which the structures and parameters of a model are determined by an identification algorithm proposed by Tse and Weinert (IEEE Trans. Automat. Con...
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