The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In the past five years the impact of the microprocessor has been felt in the application of on-line analyzers to chemical process control. This impact has made the use of on-line analyzers ideal for advanced control of chemical processes. This paper discusses the types of analyzers available and why they have had such an effect on improving chemical process control. Discussion of the most popular...
The importance of the concept of persistent excitation in adaptive identification and control is currently well recognized. In spite of its extensive use in many specific situations, our understanding of the concept is still limited. This paper deals with the properties of persistently exciting signals and the effect of various transformations on them with a view to providing a general framework to...
The paper addresses an open problem concerned with the boundedness of signals in an adaptive loop when external perturbations are present. A complete solution is provided for the case of a first order plant with an unknown parameter by analyzing a nonlinear differential equation in R2. It is shown that if the persistent excitation of the reference input is larger than the perturbation in some sense,...
The paper is concerned with the problem of decentralized control of interconnected systems subjected to stochastic disturbances. It is proposed that an equivalent reduced order dynamic model be first obtained for the subsystem of interest. For this, a dynamic equivalent of the other subsystems is identified using the interaction measurements. This model is then adjoined with the model of the subsystem...
This paper considers the design of optimal controller to an aircraft performing a lateral maneuver. The closed-loop system has a prescribed set of eigenvalues. Moreover, the closed-loop system is optimal with respect to quadratic performance index and/or its trajectory sensitivity with respect to small variations in the plant parameters from their nominal values. The predicted responses of the resulting...
Presented in [1] is a COVER-algorithm for the simplification (reduction) of LQG-controllers. These reduced controllers generate control signals that are the bext approximations of the optimal control signals produced by the LQG-controllers. This paper extends the COVER-algorithm to yield the best approximations of the optimal outputs (controlled variables) and/or sensor signals, in addition to the...
The design requirements on airborne equipment which controls an aircraft so it arrives at an assigned time are mainly driven by the need for satisfactory control during descent. Assuming open-loop control during a typical descent, the final altitude and arrival time errors due to unforecast winds and temperatures aloft are determined. The fuel required for closed-loop control to reduce these errors...
Some aspects of detecting and tracking narrowband acoustic sources that produce single or multiple sinusoids in the presence of broadband clutter are discussed. Experimental results using field data are included.
This paper discusses an adaptive structure which enables the detection and enhancement of narrow-band signals which have been corrupted by broad-band noise. A parallel configuration of second-order IIR adaptive filters is utilized, thus allowing detection of multiple signals. A gradient search algorithm is derived and the corresponding performance surface is evaluated.
This work presents a slight extension to the vector Melnikov function that measures the presence of Arnold diffusion in perturbed near-integrable Hamiltonian systems. It adopts a differential equations viewpoint and allows one subsystem, the one possessing the homoclinic orbit, to be dissipative. Adding damping to the other subsystems appears very difficult because of the Hamiltonian nature of KAM...
The Maximum principle is used to design an optimal control for a robot based on minimizing the time for a specified motion. With the use of an optimization technique, the optimal control problem is solved numerically using the complete, highly non-linear dynamic model of the manipulator. Robot geometrical and actuator limitations, as well as obstacles inside the work space, are considered in the optimal...
A simple approach to detecting instrument failures in dynamic systems described by nonlinear continuous differential equations is presented and evaluated. The method uses an extended Kalman filter to generate an innovations (or residuals) vector. Threshold crossing checks on the mean and variance of elements in this vector are used to ascertain existence of failure. The approach is demonstrated using...
A comprehensive description is provided of the properties of the matrix Riccati differential equation in which the coefficient matrices are T-periodic for some T ≫ 0. Under very mild assumptions, the asymptotic behavior of every solution is described.
This paper describes a simple model to predict the transient behavior of a condenser when subjected to changes in inlet enthalpy as well as changes in inlet and exit mass flow rates. The model predicts the pressure, fluid temperature, wall temperatures, mass in the condensing region, mass in the subcooled liquid region and the position of the liquid interface, all as a function of time during a transient...
Self-tuning controllers are generally more susceptible to deviations from theory imposed by a practical implementation than most other advanced controllers due primarily to their adaptive nature. The control of moisture content in the papermaking process can create several situations causing parameter divergence or unsuitable estimation or control. Careful consideration of the theory, the process...
The condensing steam heaters dynamically modeled in this work are shell and tube type heat exchangers with the condensing steam on the shell side. Two variations of the model are developed, one for heating a gas stream where the thermal mass of the gas is very small, and one for heating a liquid stream where the thermal mass of the heated fluid is appreciable. Predictions from the gas heater model...
Self-tuning of PID and other simple controllers and design of a special station for that purpose in a digital process automation system are considered. The tuning station is mainly intended to serve as a user's aid when taking use or retuning control loops in the system. Adaptive mode is, however, also available by making the station continuously tune the loop controller.
A computer code (THEDA-2) developed for predicting the thermal and hydraulic performance of nuclear once-through and inverted U-tube steam generators was benchmarked. Data from a full-length laboratory steam generator, representative of Babcock & Wilcox once-through nuclear steam generators, were obtained and compared to THEDA-2 predictions. Two geometrical arrangements of the laboratory steam...
The problem of selecting a feasible model structure for a MIMO self-tuning controller (MIMOSC) is addressed. The dependency of the necessary structure complexity in relation to the specific process operating point is investigated. Experimental results from a fixed-bed chemical reactor are used to illustrate the points.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.