Narrow Results

This paper shows the effects of optimal control techniques on pattern formation in a three-dimensional Rayleigh–Bénard problem with nonhomogeneous heating from below. In particular, we consider a cylindrical domain with a heating profile at the bottom localized around the origin. An axisymmetric basic state appears as soon a nonzero horizontal temperature gradient is imposed. The basic state may bifurcate to different solutions as spiral waves, stationary patterns, etc., depending on the vertical and lateral temperature gradients and on the shape of the heating function. An optimal control problem that determines the thermal boundary condition minimizing the enstrophy is proposed. The control boundary condition obtained changes the leading mode in the bifurcation and allows to eliminate the instabilities for some values of the parameters.

An artificial anal sphincter utilizing shape memory alloy (SMA) is one of the implant devices for the patients using artificial anus. The device requires an adequate rise in temperature for its actuation, although overheating should be avoided. A suitable configuration for contact-less power supply to the artificial sphincter and a new method of temperature control were proposed in this work. A small inductor with thermosensitive magnetic ferrite core has been developed for a key device for temperature control as well as power supply. The Curie temperature of the ferrite was set around the SMA's phase transformation temperature, so that at the temperature the inductor restrains electric power to the heater attached to a SMA plate in order to prevent the overheating. Therefore, it is possible to control the temperature of SMA plate.

Temperature control of the cooling tower (CT) system based on fuzzyprogrammable logic controller (PLC) control technology is developed and implemented in this research to increase electric static precipitator (ESP) performance, output, and quality and minimize losses within the CT in the cement plant. This approach exploits the fuzzy logic controller and implements it in the PLC. The valve system is controlled to avoid the occasional wet bottom phenomenon in the CT. A fuzzy valve controller is designed to solve the problem of opening and closing the valve at the appropriate time in the return line to regulate the temperature of the CT. The program is written using MATLAB and converted to structured text language (STL) by SIMULINK PLC coder. STL is a functional expression that increases the efficiency of the work system PLC − 1200. Results show a substantial increase in ESP quality after the implementation of fuzzy control temperature for the CT to reduce dust emissions from the cement plant compared with the traditional operator.

In this thesis, adaptive pole-zero collocation controller is designed aiming at the electroanalysis trough temperature character being big cubage-lag and badly asymmetry to the temperature change. At the same time, with both servo and adjustment performances taken into account, corresponding control arithmetic is put forward. The control result indicates that the electroanalysis trough temperature control has the advantages such as fast, steady, high precision etc. This system is characterized by simple structure, convenient design, good robust etc. So it provides a powerful control approach for engineering application.

In this paper a temperature control method for laser was proposed. The genetic algorithm was used to calculate parameters of PID control to get constant operating temperature by controlling thermoelectric cooler. The long-term experiment showed the variation of laser temperature was smaller than 0.1 degree and the variation of output laser wavelength was limited in 0.01nm, which met the practical requirement well.

A fuzzy PID control strategy is brought forward for typical temperature control system, which can save the investment on equipment and achieve the least set time on condition that it does not overshoot. To adapt to the mentioned instance, it improves the traditional fuzzy control strategy and the tuning of PID controllers. Simulation results show that the solution of the controller design is simple, practical and effective.

This chapter presents a new practical control system that can apply conventional PID controllers to nonlinear field by using fuzzy reasoning. The proposed system is a hierarchical one consisting of two components: (a) a Fuzzy-PID controller, and (b) a supervisor for setting the control target of this controller. The fuzzy controller in the Fuzzy-PID controller compensates the output error of the conventional PID controller. The supervisor calculates the control target by fuzzy reasoning. This hierarchical control system is applied to the temperature control in a petroleum plant. The parameters in fuzzy controller are tuned on-line in the actual plant and the system can control the temperature effectively in the transient state, such as feed property changing or operation mode changing, as well as in the steady state

Fourier temperature finite element is very efficient on nonlinear analysis of transient temperature fields of thin-walled tubes absorbing space heat flux and emitting thermal energy by radiation. Controlled temperature of thin-walled tubes can supress the thermally-induced responses of space structures. Based on fourier-temperature finite element, this paper develops a heat flux identification method for given temperature on thin-walled tubes and the identification result can be used to actively control the temperature of thin-walled tubes. A numerical example illustrate that the heat flux value, acting position and acting area can be reliably identified by this method.

In order to meet different requirements of experimental temperature inside ultrasonic machines, a new outboard device have been developed and able to make the inner liquid environment of an ultrasonic cleaner maintain a constant temperature. This device can not only maintain a constant temperature range of the target liquid environment, but also be convenient for moving, dismounting and installing on machines of different sizes. In order to realize effects of a constant temperature, a temperature control system is used in this device to analyze temperature data and conduct logic design on them so that heating or refrigerating are under control. A semiconductor chilling plate is applied to be the refrigeration core of the refrigeration system, assisting with a cooling system against the heating surface of the semiconductor cooler. According to test results, this device can maintain liquid within 10L in a constant temperature range of 10-60°C, error within 0.5°C.

At present, solar collectors thermal performance testing system based on PID control algorithm was defective. In order to improve the system, a fuzzy predictive control algorithm was proposed. Firstly, the fuzzy control and predictive control were combined to adjust the actual system. Secondly, SIMULINK software was applied to establish a PID algorithm for the simulation model which was based on control algorithm and fuzzy prediction. The simulation showed that the fuzzy predictive control method was a feasible and effective approach that can improve the stability of the temperature and speed up the response speed. In the end, this novel method can improve the detection efficiency of the system.

Ceramic kiln with large heat capacity, big lag and nonlinear characteristic, this paper proposes a combining fuzzy control and predictive control of the control algorithm, to enhance the tracking and anti-interference ability of the algorithm. The simulation results show, this method compared with the control of PID has the high steady precision and dynamic characteristic.