Showing papers on "Temperature control published in 2009"

Design of a Data-Driven PID Controller

Abstract: Since most processes have nonlinearities, controller design schemes to deal with such systems are required. On the other hand, proportional-integral-derivative (PID) controllers have been widely used for process systems. Therefore, in this paper, a new design scheme of PID controllers based on a data-driven (DD) technique is proposed for nonlinear systems. According to the DD technique, a suitable set of PID parameters is automatically generated based on input/output data pairs of the controlled object stored in the database. This scheme can adjust the PID parameters in an online manner even if the system has nonlinear properties and/or time-variant system parameters. Finally, the effectiveness of the newly proposed control scheme is evaluated on some simulation examples, and a pilot-scale temperature control system.

Three-dimensional spatial and temporal temperature control with MR thermometry-guided focused ultrasound (MRgHIFU)

Abstract: High-intensity focused ultrasound (HIFU) is an efficient noninvasive technique for local heating. Using MRI thermal maps, a proportional, integral, and derivative (PID) automatic temperature control was previously applied at the focal point, or at several points within a plane perpendicular to the beam axis using a multispiral focal point trajectory. This study presents a flexible and rapid method to extend the spatial PID temperature control to three dimensions during each MR dynamic. The temperature in the complete volume is regulated by taking into account the overlap effect of nearby sonication points, which tends to enlarge the heated area along the beam axis. Volumetric temperature control in vitro in gel and in vivo in rabbit leg muscle was shown to provide temperature control with a precision close to that of the temperature MRI measurements. The proposed temperature control ensures heating throughout the volume of interest of up to 1 ml composed of 287 voxels with 95% of the energy deposited within its boundaries and reducing the typical average temperature overshoot to 1 degrees C.

Smart temperature measuring device

Abstract: A temperature measuring device having a smart chip, or electronic circuit, integrated therein is provided. The smart chip, or electronic circuit, includes at least a unique identification number or data specific to the particular temperature measuring device stored thereon. The electronic circuit further includes calibration data of the temperature measuring device stored thereon. A module controller of a temperature control system is configured to verify the unique identification number of the thermocouple assembly prior to allowing data to be transferred between the temperature measuring device and a temperature controller. A graphical user interface allows an operator to enter the unique identification number or data to verify the temperature measuring device and display an error message if the number or data entered is not equivalent, or does not match, the unique identification number or data stored on the electronic circuit.

Development of temperature-control system for liquid droplet using surface Acoustic wave devices

Abstract: In this paper, we present a liquid-droplet-heating system using a surface acoustic wave (SAW) device. When liquid is placed on a Rayleigh-SAW-propagating surface, a longitudinal wave is radiated into the liquid. If the SAW amplitude increases, the liquid shows non-linear dynamics, such as vibrating, streaming, small droplet flying, and atomizing. This phenomenon is well known as SAW streaming. The liquid temperature is measured during the longitudinal wave radiation and found to increase. First, the mechanism of the liquid-heating effect is discussed on the basis of experimental results. The surface electrical condition is changed to investigate the effect of dielectric heating. The obtained results indicate that the radiated longitudinal wave causes liquid heating and the dielectric heating effect does not. Second, the fundamental properties of the liquid temperature are measured by varying the applied voltage, duty factor, and liquid viscosity. The liquid temperature is found to be proportional to the duty factor and the square of the applied voltage. Therefore, the liquid temperature can be controlled by these applied signals. Also, by using highly viscous solutions, the liquid temperature is increased to more than 100 °C. Moreover, for chemical applications, the possibility of periodic temperature control is tested by varying the duty factor. The obtained results strongly suggest that an efficient thermal cycler is realized. A novel application of the SAW device is proposed on the basis of SAW streaming.

Multicore thermal management with model predictive control

Abstract: The goal of thermal management is to meet maximum operating temperature constraints, while at the same time tracking time-varying performance requirements. Current approaches avoid thermal violations by forcing abrupt operating points changes (e.g. processor shutdown), which cause sharp performance degradation. In this paper we aim at achieving a smooth thermal control action, that minimizes the variance of performance tracking error. We formulate this problem as a discrete-time optimal control problem, which can be solved using the theory and computational tools developed in the field of model-predictive control. Our optimization process considers the thermal profile of the system, its evolution over time, and time-varying workload requirements. Experimental results show that the proposed approach offers significant thermal balancing improvements over previous methods.

Predicting of fan speed for energy saving in HVAC system based on adaptive network based fuzzy inference system

Abstract: In this paper, a HVAC (heating, ventilating and air-conditioning) system has two different zones was designed and fan motor speed to minimize energy consumption of the HVAC system was controlled by a conventional (proportional-integral-derivative) PID controller. The desired temperatures were realized by variable flow-rate by considering the ambient temperature for each zone. The control algorithm was transformed for a programmable logic controller (PLC). The realized system has been controlled by PLC used PID control algorithm. The input-output data set of the HVAC system were first stored and than these data sets were used to predict the fan motor speed based on adaptive network based fuzzy inference system (ANFIS). In simulations, root-mean-square (RMS) and the coefficient of multiple determinations (R2) as two performance measures were obtained to compare the predicted and actual values for model validation. All simulations have shown that the proposed method is more effective and controls the systems quite well.

Linearization Circuit of the Thermistor Connection

Abstract: Thermistors have found wide application in temperature measurement and control in different fields, but they exhibit a strong nonlinearity of the characteristic, which is of an exponential type. This paper investigates the possibility of creating a thermistor-based temperature sensor with frequency and analog outputs and a linearized characteristic on the basis of a 7555 timer. It is shown through simulations that the linearization of the characteristic can be achieved without connecting additional elements to the circuit but only through a choice of the parameters of the thermistor and of the frequency-determining circuit elements. The investigations conducted show a good match between the theoretically and experimentally obtained characteristics. The proposed circuit is characterized by nonlinearity of plusmn1% in a specific temperature range, as well as high temperature stability.

Microgyroscope Temperature Effects and Compensation-Control Methods

Abstract: In the analysis of the effects of temperature on the performance of microgyroscopes, it is found that the resonant frequency of the microgyroscope decreases linearly as the temperature increases, and the quality factor changes drastically at low temperatures. Moreover, the zero bias changes greatly with temperature variations. To reduce the temperature effects on the microgyroscope, temperature compensation-control methods are proposed. In the first place, a BP (Back Propagation) neural network and polynomial fitting are utilized for building the temperature model of the microgyroscope. Considering the simplicity and real-time requirements, piecewise polynomial fitting is applied in the temperature compensation system. Then, an integral-separated PID (Proportion Integration Differentiation) control algorithm is adopted in the temperature control system, which can stabilize the temperature inside the microgyrocope in pursuing its optimal performance. Experimental results reveal that the combination of microgyroscope temperature compensation and control methods is both realizable and effective in a miniaturized microgyroscope prototype.

Optical tweezers with millikelvin precision of temperature-controlled objectives and base-pair resolution

Abstract: In optical tweezers, thermal drift is detrimental for high-resolution measurements In particular, absorption of the trapping laser light by the microscope objective that focuses the beam leads to heating of the objective and subsequent drift This entails long equilibration times which may limit sensitive biophysical assays Here, we introduce an objective temperature feedback system for minimizing thermal drift We measured that the infrared laser heated the objective by 07K per watt of laser power and that the laser focus moved relative to the sample by ≈1 nm/mK due to thermal expansion of the objective The feedback stabilized the temperature of the trapping objective with millikelvin precision This enhanced the long-term temperature stability and significantly reduced the settling time of the instrument to about 100 s after a temperature disturbance while preserving single DNA base-pair resolution of surface-coupled assays Minimizing systematic temperature changes of the objective and concurrent drift is of interest for other high-resolution microscopy techniques Furthermore, temperature control is often a desirable parameter in biophysical experiments

Integrated Hybrid-PSO and Fuzzy-NN Decoupling Control for Temperature of Reheating Furnace

Abstract: This paper presents an integrated method of intelligent decoupling control as a solution to the problem of adjusting the zone temperatures in a regenerative pusher-type reheating furnace. First, a recurrent neural network (NN) for estimating the zone temperatures and a heat transfer model for predicting billet temperatures are built based on data from actual furnace operations. Next, a decoupling strategy in combination with a fuzzy NN is used to control the zone temperatures. The architecture of the controller is based on a fuzzy c-means clustering approach; and the weights are optimized by a hybrid particle swarm optimization (HPSO) algorithm, which integrates the global optimization of density-based selection and the precise search of clonal expansion in an immune system with the fast local search of particle swarm optimization. HPSO is also used to optimize the zone temperature settings to minimize three items: fuel consumption, the temperature gradient within a billet, and the error between the mean and target temperatures of a billet at the furnace exit. The results of actual runs demonstrate the validity of this method.

Wind turbine, a method for controlling the temperature of fluid flowing in a first temperature control system of a wind turbine and use thereof

Abstract: A wind turbine includes a first temperature control system including fluid transporting heat to or from one or more components of the wind turbine. The wind turbine further includes a mechanism for exchanging heat between the first temperature control system and at least one further temperature control system of the wind turbine, wherein a temperature controlled mechanism enables the heat exchange between the first temperature control system and the at least one further temperature control system. A method for controlling or regulating the temperature of fluid flowing in a first temperature control system of a wind turbine and a use hereof is also contemplated.

Local temperature control of photonic crystal devices via micron-scale electrical heaters

Abstract: We demonstrate a method to locally control the temperature of photonic crystal devices via micron-scale electrical heaters. The method is used to control the resonant frequency of InAs quantum dots strongly coupled to GaAs photonic crystal resonators. This technique enables independent control of large ensembles of photonic devices located on the same chip at tuning speed as high as hundreds of kilohertz.

Terminal Iterative Learning Control design with singular value decomposition decoupling for thermoforming ovens

Abstract: Terminal Iterative Learning Control (TILC) is a cycle-to-cycle control approach that can be used on thermoforming oven. TILC automatically tune the heater temperature setpoints such that the temperature at the surface of the plastic sheet tracks a desired temperature profile. Industrial thermoforming ovens can have a large number of temperature sensor (inputs) and heaters (outputs) which makes the design of TILC difficult. This paper presents the design of a TILC using the singular value decomposition decoupling technique. With this tool, the TILC design is facilitated for industrial thermoforming oven.

Local temperature control of photonic crystal devices via micron-scale electrical heaters

Abstract: We demonstrate a method to locally control the temperature of photonic crystal devices via micron-scale electrical heaters. The method is used to control the resonant frequency of InAs quantum dots strongly coupled to GaAs photonic crystal resonators. This technique enables independent control of large ensembles of photonic devices located on the same chip at tuning speed as high as hundreds of kHz.

Mass spectrometer and mass spectrometry method

Abstract: A mass spectrometer includes an ionization chamber, a temperature control unit which controls the temperature in the ionization chamber to vaporize a sample in at least one of solid and liquid state in the ionization chamber, an introduction unit which introduces the sample into the ionization chamber, an ion supply unit which supplies ions to the ionization chamber to ionize, in the ionization chamber, the sample vaporized in the ionization chamber, and a mass analyzer which measures the mass of the molecules of the ionized sample.

Identification and Autotuning of Temperature-Control System With Application to Injection Molding

Abstract: Motivated by the practical barrel-temperature control of injection molding, this paper proposes two identification methods and a united control scheme for general temperature control design. Based on the unity step response, corresponding to the full heating response in a temperature-control system, an identification method is developed to obtain an integrating model for heating-up control design. By using a relay test around the set-point temperature, another identification method is proposed to obtain a model of stable or integrating type for control-system design to reject load disturbances during system operation. To ensure identification robustness, denoising strategies have also been presented for practical applications with measurement noise. For simplicity of implementation, a united control scheme based on the internal-model-control structure is proposed for both heating-up and steady operations against load disturbance. Analytical controller-design formulas and tuning rules are correspondingly developed for quantitative regulation of the heating-up response and the load-disturbance response for operation. Examples from the recent literature and a practical application to injection molding are performed to demonstrate the effectiveness and merit of the proposed identification methods and control scheme.

Fractional-order integral and derivative controller for temperature profile tracking

Abstract: This paper establishes a new strategy to tune a fractional order integral and derivative (ID) controller satisfying gain and phase margins based on Bode’s ideal transfer function as a reference model, for a temperature profile tracking. A systematic analysis resulting in a non-linear equation relating user-defined gain and phase margins to the fractional order controller is derived. The closed-loop system designed has a feature of robustness to gain variations with step responses exhibiting a nearly iso-damping property. This paper aims to apply the analytical tuning procedure to control the heat flow systems at selected points in Quanser experimental platform. Thus, the main purpose of this paper is to examine performances of two different fractional order controllers in temperature profile tracking. From experimental comparisons with the traditional PI/PID controller based on Ziegler-Nichols’ tuning method, it will be shown that the proposed methodologies are specifically beneficial in controlling temperature in time-delay heat flow systems.

Temperature controlled showerhead for high temperature operations

Abstract: A temperature controlled showerhead assembly for chemical vapor deposition (CVD) chambers enhances heat dissipation to provide accurate temperature control of the showerhead face plate and maintain temperatures substantially lower than surrounding components. Heat dissipates by conduction through a showerhead stem and removed by the heat exchanger mounted outside of the vacuum environment. Heat is supplied by a heating element inserted into the steam of the showerhead. Temperature is controlled using feedback supplied by a temperature sensor installed in the stem and in thermal contact with the face plate.

Design of self-tuning fuzzy logic controller for the control of an unknown industrial process

Abstract: An improvement over the existing conventional fuzzy logic approach, based on a self-tuning fuzzy logic controller (FLC), for the design of a temperature control process, capable of providing optimal performance over the entire operating range of the process, was proposed. Since an optimum response of the FLC can be expected only for a limited range of inputs, tuning the input and output gains is done here for various range of inputs. The proposed control system has the advantages of self-tuning FLC schemes. To evaluate the performance of the proposed control system methods, the results from the simulation of the process are presented.

Nonlinear Observer-Based Feedback Dissipation Load-Following Control for Nuclear Reactors

Abstract: Nuclear fission reaction provides more and more energy required for generating electrical power in the world, and therefore load-following control has become an important technique for nuclear reactor regulation. A novel nonlinear controller called observer-based feedback dissipation controller for single-output-single-input (SISO) generalized Hamiltonian systems is presented in this paper. The observer has a dissipative Hamiltonian structure, and sufficient condition for closed-loop asymptotical stability is also derived. This novel control strategy is then applied to the load following control for nuclear reactors. Simulation results show that the control performance is high, and parameters of the controller have direct and close relationship with the rod speed and transient response of the nuclear power and coolant temperature.

Methods and systems for communicating using variable temperature control

Abstract: Information can be communicated by a temperature change of a communication device equipped with one or more temperature modifying elements. A processor configured by software determines when a temperature change should be generated and accomplishes such a change by controlling the application of power to the temperature modifying element(s). The temperature modifying elements may be electric resistance heating elements, thermoelectric elements, or other elements. Users perceive the temperature change produced by the temperature modifying element(s) when they touch the device. Depending on user settings, the temperature change may communicate specific information to the user. For example, a temperature change may convey information regarding the importance of an incoming telephone call, e- mail message or SMS message, or the importance of an impending calendar event. Using temperature as a communication medium allows the communication device to convey information to a user being notice by others.