Abstract Grade changes in polyethylene reactors, i.e., changes of operating conditions, are performed on a regular basis to adapt to market demands. In this paper, a dynamic optimization procedure is presented built u...
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Abstract Grade changes in polyethylene reactors, i.e., changes of operating conditions, are performed on a regular basis to adapt to market demands. In this paper, a dynamic optimization procedure is presented built upon the Modelica language extended with Optimica constructs for formulation of optimization problems. A Modelica library for the Borstar® multistage polyethylene reactors at Borealis AB, consisting of two slurry and one gas phase reactor, has been constructed. Using http://*** , a framework to translate dynamic optimization problems to NLP problems, optimal grade transitions between grades currently used at Borealis AB, can be calculated. Optimal inflows and grade key variables are shown.
Abstract A fundamental quantity of the solution of an optimal control problem is the value function, i.e., the optimal cost-to-go function. In the general case, the function is not known exactly, but need to be approx...
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Abstract A fundamental quantity of the solution of an optimal control problem is the value function, i.e., the optimal cost-to-go function. In the general case, the function is not known exactly, but need to be approximated numerically. Most approaches to numerical approximation of the value function follow a procedure of three steps: first, the original continuous problem formulation is fully discretized; second, the discretized finite optimal control problem is solved by a shortest-path algorithm, and as third step, the solution is projected back from the finite space onto the continuous state space by using an interpolating function. This paper investigates the differences of discretization schemes and interpolating functions in this context. The performance of the computed approximations is evaluated in terms of an a-posteriori error, which is obtained from the approximating value functions. The convergence of the approximations to the true value function is proved for all considered schemes for the case that the discretization parameters are decreased to zero.
This paper presents theoretical and experimental results of a newly developed automaticcontroller tuning algorithm called Robust Estimation for automaticcontroller Tuning (REACT) to tune a linear feedback controller...
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Researches on robotic manipulation mainly focus on rigid objects. Whereas, manipulating deformable linear objects (DLOs) such as hoses, wires, cables is common in daily life and many domains such as manufacture, medic...
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This paper describes the different communication patterns followed in industrial communications and maps them into DDS (Data Distribution Service) which is a recent middleware specification. This specification follows...
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JFE engineering has developed a new combustion controlsystem that is capable of achieving the stable combustion for various multi-waste-fuels in the circulating fluidized bed boiler (CFB). This system has advanced co...
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We present a closed-form method for the self-calibration of a camera (intrinsic and extrinsic parameters) from at least three images acquired with parallel screw axis motion, i.e. the camera rotates about parallel axe...
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In the last two decades, Chaos theory has received a great deal of attention from the cryptographic community. This paper presents two ideas. First idea is using chaotic functions to overcome the weaknesses of the cla...
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In the last two decades, Chaos theory has received a great deal of attention from the cryptographic community. This paper presents two ideas. First idea is using chaotic functions to overcome the weaknesses of the classical Hill cipher. The second idea is proposing a new encoder-decoder architecture, called ChaoEncoDeco, for securing JPEG images. An extra stage of encryption is embedded within the traditional JPEG codec to improve security level of such system. This security stage uses one of the chaotic functions called Logistic Map. This map is used to enhance the Hill cipher and achieve more secure encryption key. The properties of both chaotic system and of the Hill cipher encryption key are all utilized to obtain ultimate secure systems. The proposed encryption algorithm is crypto-analyzed and compared to the standard Hill cipher algorithm. Complete evaluation for the proposed architecture is also performed which indicates the effectiveness of the proposed system.
Abstract This paper presents theoretical and experimental results of a newly developed automaticcontroller tuning algorithm called Robust Estimation for automaticcontroller Tuning (REACT) to tune a linear feedback c...
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Abstract This paper presents theoretical and experimental results of a newly developed automaticcontroller tuning algorithm called Robust Estimation for automaticcontroller Tuning (REACT) to tune a linear feedback controller to the unknown spectrum of disturbances present in a feedback loop. With model uncertainty and controller perturbations described in (dual) Youla parametrizations, the REACT algorithm allows recursive least squares based tuning of a feedback controller in the presence of model uncertainty to minimize the variance of control performance related signal. It is shown how stability of the feedback can be maintained during adaptive regulation, while simulation and experimental results on a mechanical test bed of an active suspension system illustrate the effectiveness of the algorithm for vibration isolation of periodic disturbances with unknown and varying frequencies.
Abstract A distributed constrained supervisory strategy for large-scale spatially distributed systems is presented and applied to a networked water distribution system. The aim is at reconfiguring, whenever necessary ...
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Abstract A distributed constrained supervisory strategy for large-scale spatially distributed systems is presented and applied to a networked water distribution system. The aim is at reconfiguring, whenever necessary in response to different supply downstream demands, the nominal set-points to the tank water levels so that all prescribed coordination and operational constraints are enforced during the system evolutions and sustainable equilibria are reached. The presented supervision strategy follows a coordination-by-constraint approach and is based on Feed-Forward Command Governor (FF-CG) ideas. The effectiveness of the strategy is shown in the final example where the supervision of an eight-tank interconnected system is considered.
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