In this paper, we propose a heuristic approach for fixing work-in-progress (WIP) projection issues in the semiconductor industry especially for high mix low volume facilities. The considered problem consists of estima...
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In this paper, we propose a heuristic approach for fixing work-in-progress (WIP) projection issues in the semiconductor industry especially for high mix low volume facilities. The considered problem consists of estimating the start and end dates for each remaining process step of the production lots in the WIP and anticipating the fab loading taking into account the constraints of the maximum throughput of machines considered as capacity constraints and customer delivery commitments. The objective being to guarantee on-time delivery, we focus on minimizing the total weighted tardiness. We have formulated the problem into a mixed-integer programming and we have empirically shown its computational intractability. Due to the computational intractability using actual production data, a heuristic algorithm is proposed. It is an iterative finite capacity planning system that considers as inputs lots due dates and equipment capabilities and capacities. The performance of the heuristic is assessed using industrial instances. It turns out that it achieves targeted objectives with satisfactory results in terms of quality of the solution and computation time.
This paper considers the parameter estimation of a multiple-input-output-error system with autoregressive noise. In order to solve the problem of the information vector containing unknown inner variables, an auxiliary...
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This paper considers the parameter estimation of a multiple-input-output-error system with autoregressive noise. In order to solve the problem of the information vector containing unknown inner variables, an auxiliary model-based recursive generalized least squares algorithm and a least squares-based iterative algorithm are proposed according to the auxiliary model identification idea and the iterative search principle. The simulation results indicate that the least squares-based iterative algorithm can generate more accurate parameter estimates than the auxiliary model-based recursive generalized least squares algorithm. Two examples are given to test the proposed algorithms.
The parameter estimation issues of a block-oriented non-linear system that is bilinear in the parameters are studied, i.e. the bilinear-in-parameter system. Using the model decomposition technique, the bilinear-in-par...
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The parameter estimation issues of a block-oriented non-linear system that is bilinear in the parameters are studied, i.e. the bilinear-in-parameter system. Using the model decomposition technique, the bilinear-in-parameter model is decomposed into two fictitious submodels: one containing the unknown parameters in the non-linear block and the other containing the unknown parameters in the linear dynamic one and the noise model. Then a gradient-based iterative algorithm is proposed to estimate all the unknown parameters by formulating and minimising two criterion functions. The stochastic gradient algorithms are provided for comparison. The simulation results indicate that the proposed iterative algorithm can give higher parameter estimation accuracy than the stochastic gradient algorithms.
This paper is concerned with the guaranteed cost control problem for continuous-time periodic piecewise linear systems with time delay. Sufficient delay-dependent conditions of closed-loop asymptotic stability are pre...
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This paper is concerned with the guaranteed cost control problem for continuous-time periodic piecewise linear systems with time delay. Sufficient delay-dependent conditions of closed-loop asymptotic stability are presented based on an improved formulation, which uses a novel Lyapunov-Krasovskii functional with relaxed requirement in positive definiteness of the involved symmetric matrices. The corresponding optimization problems aiming at the mixed performance involving an upper bound of H-2 guaranteed cost and an H-infinity performance index for disturbance attenuation are established. By designing an iterative algorithm subject to the proposed conditions, the periodic guaranteed cost controller gains over each sub-interval are tractable for the resulting closed-loop time-delay system. The effectiveness and reduced conservatism of our proposed criteria are validated and illustrated via numerical simulations. (C) 2018 Elsevier Ltd. All rights reserved.
An automatic tensioner that consists of a torsional spring and friction damping elements is widely used in belt drive system. The relation of the applied torque versus the imposed angle of tensioner during loading and...
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An automatic tensioner that consists of a torsional spring and friction damping elements is widely used in belt drive system. The relation of the applied torque versus the imposed angle of tensioner during loading and unloading processes is described as a hysteretic loop. An analytical model is established for estimating the hysteretic behavior of a tensioner, and measurements for hysteretic loop in quasi-static and dynamic excitation are carried out to validate the analytical model. Taking one engine timing belt drive system as a studying example, the method and the procedure for estimating vibration responses of the nonlinear tensioner are given. An iterative algorithm for predicting the accurate equivalent viscous damping of tensioner is carried out in analyzing a belt drive system. The vibration responses of tensioner are validated by the measurement of timing belt drive system. The developed method presented in this article is useful for predicting the hysteretic behavior of tensioner, vibration responses, and the parameters optimization of a belt drive system.
This paper studies the design problem of periodic piecewise guaranteed cost controllers for a class of continuous-time uncertain periodic piecewise linear systems using a time weighted quadratic cost function. By deve...
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This paper studies the design problem of periodic piecewise guaranteed cost controllers for a class of continuous-time uncertain periodic piecewise linear systems using a time weighted quadratic cost function. By developing Lyapunov functions with quadratic cost matrices to a time-varying form, sufficient conditions are proposed to ensure the exponential stability of the closed-loop system and a guaranteed upper bound of the cost function. To minimize the upper bound in the controller design process, an iterative algorithm is developed to solve the problem via convex optimization. The effectiveness of our proposed algorithm is demonstrated via a numerical example, and the impact of time-weighted cost is illustrated by simulation results. (C) 2018 Elsevier Inc. All rights reserved.
Two iterative algorithms are proposed for the split fixed point *** first algorithm is shown to be weakly convergent and the second one to be strongly *** feature of these algorithms is that the stepsizes are chosen i...
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Two iterative algorithms are proposed for the split fixed point *** first algorithm is shown to be weakly convergent and the second one to be strongly *** feature of these algorithms is that the stepsizes are chosen in such a way that no priori knowledge of the operator norms is required.A new idea is introduced in order to prove strong convergence of the second algorithm.
With the power system harmonic pollution problems becoming more and more serious, how to distinguish the harmonic responsibility accurately and solve the grid harmonics simply and effectively has become the main devel...
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With the power system harmonic pollution problems becoming more and more serious, how to distinguish the harmonic responsibility accurately and solve the grid harmonics simply and effectively has become the main development direction in harmonic control subjects. This paper, based on linear regression analysis of basic equation and improvement equation, deduced the least squares estimation (LSE) iterative algorithm and obtained the real-time estimates of regression coefficients, and then calculated the level of the harmonic impedance and emission estimates in real time. This paper used power system simulation software Matlab/Simulink as analysis tool and analyzed the user side of the harmonic amplitude and phase fluctuations PCC (point of common coupling) at the harmonic emission level, thus the research has a certain theoretical significance. The development of this algorithm combined with the instrument can be used in practical engineering.
The classical principles of Wiener filter design consider only the causality constraint. However, additional constraints are often involved in practice. This paper provides a comprehensive theoretical approach for des...
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The classical principles of Wiener filter design consider only the causality constraint. However, additional constraints are often involved in practice. This paper provides a comprehensive theoretical approach for designing Wiener filters with constraint conditions beyond causality. Using integration, we first derive an extension of the Wiener-Hopf equation with an additional term that captures the effect of the constraint conditions on the resulting Wiener filters. Next, we analytically solve the extended Wiener-Hopf equation and develop a new iterative algorithm to obtain its optimum value. We prove the convergence of our iterative algorithm and provide several simulations to illustrate the applicability of our theoretical approach.
The problem of state observer design for the linear discrete-time periodic (LDP) system and its robust consideration are discussed in this paper. Applying the lifting technique and algebraic operations based on the we...
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The problem of state observer design for the linear discrete-time periodic (LDP) system and its robust consideration are discussed in this paper. Applying the lifting technique and algebraic operations based on the well-known CG-algorithm, an iterative algorithm for periodic observer gain can be generated. By optimizing the free parameter matrix in the proposed algorithm, an algorithm on the minimum norm and robust observer design for the LDP systems is presented. One numerical example is worked out to illustrate the effect of the proposed approaches.
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