Showing papers on "Temperature control published in 2000"

RF ablation system and method having automatic temperature control

Abstract: A plurality of electrodes are positioned at the distal end of a catheter such that the electrodes may be positioned proximal biological tissue. A select number of the electrodes have a temperature sensing device associated with them for providing a temperature signal indicative of the temperature at the interface between the electrode and the tissue. A generator operates under the control of a processor to apply power to each of the electrodes. The power has an associated phase angle and, within a time duration, a plurality of alternating on periods and off periods, one set of adjacent on and off periods defining a duty cycle. The processor is programmed to determine the temperature at the electrode/tissue interface based on the temperature signals, compare the temperature to a target temperature and to adjust the power to the electrode accordingly. Such adjustments may comprise an increase or decrease in the duty cycle, a setting of the duty cycle to zero followed by an incremental increase in the duty cycle or a power interrupt.

A framework for dynamic energy efficiency and temperature management

Abstract: While technology is delivering increasingly sophisticated and powerful chip designs, it is also imposing alarmingly high energy requirements on the chips. One way to address this problem is to manage the energy dynamically. Unfortunately, current dynamic schemes for energy management are relatively limited. In addition, they manage energy either for energy efficiency or for temperature control, but not for both simultaneously. In this paper, we design and evaluate for the first time an energy-management framework that tackles both energy efficiency and temperature control in a unified manner. We call this general approach Dynamic Energy Efficiency and Temperature Management (DEETM). Our framework combines many energy-management techniques and can activate them individually or in groups in a fine-grained manner according to a given policy. The goal of the framework is two-fold: maximize energy savings without extending application execution time beyond a given tolerable limit, and guarantee that the temperature remains below a given limit while minimizing any resulting slowdown. The framework successfully meets these goals. For example, it delivers a 40% energy reduction with only a 10% application slowdown.

Hyperthermia by MR-guided focused ultrasound: accurate temperature control based on fast MRI and a physical model of local energy deposition and heat conduction.

Abstract: Temperature regulation in MR-guided focused ultrasound requires rapid MR temperature mapping and automatic feedback control of the ultrasound output. Here, a regulation method is proposed based on a physical model of local energy deposition and heat conduction. The real-time evaluation of local temperature gradients from temperature maps is an essential element of the control system. Each time a new image is available, ultrasound power is adjusted on-the-fly in order to obtain the desired evolution of the focal point temperature. In vitro and in vivo performance indicated fast and accurate control of temperature and a large tolerance of errors in initial estimates of ultrasound absorption and heat conduction. When using correct estimates for the physical parameters of the model, focal point temperature was controlled within the measurement noise limit. Initial errors in absorption and diffusion parameters are compensated for exponentially with a user-defined response time, which is suggested to be on the order of 10 sec.

Temperature control for multi-vessel reaction apparatus

Abstract: Temperature control in a rectangular array of reaction vessels such as a thermal cycler such as is used for PCR procedures is achieved by use of a temperature block that is in contact with a combination of Peltier effect thermoelectric modules and wire heating elements embedded along the edges of the block. The elements can be energized in such a manner as to achieve a constant temperature throughout the array or a temperature gradient. Further control over the temperature and prevention of condensation in the individual reaction vessels is achieved by the use of a glass (or other transparent material) plate positioned above the vessels, with an electrically conductive coating on the upper surface of the glass plate to provide resistance heating.

Thermoelectric-cooling temperature control apparatus for semiconductor device fabrication facility

Abstract: A thermoelectric-cooling temperature control apparatus for a semiconductor device fabrication facility maintains a temperature condition, such as the temperature of a wafer, stable during the fabrication process. The apparatus includes a heat exchanger having a thermoelectric cooling element which produces a Peltier Effect to cause the element to absorb and radiate heat according to current flowing through the element

Precise temperature control of microfluidic chamber for gas and liquid phase reactions

Abstract: A silicon-based micromachined fluidic chamber with integrated platinum heaters and sensors has been developed and thermally well characterized. This device is highly applicable to both gas and liquid phase reactions that require excellent thermal control. The chamber is thermally isolated from the bulk silicon by a thin silicon nitride membrane resulting in low power consumption. The digitally feedback controlled device demonstrates the ability of precise temperature control, excellent temperature uniformity, rapid heating and cooling. These thermal characteristics are ascribable to the success of miniaturized reaction chamber and Micro Total Analysis Systems (μTAS). In addition, gain scheduling control algorithm in conjunction with normal feedback proportional and integral (PI) scheme was implemented to provide better thermal cycling performance. 3D numerical simulation was also conducted to map the spatial temperature distribution within the miniaturized fluidic device. Simulation results and experimental data show good agreements.

System dynamic model and temperature control of a thermoelectric cooler

Abstract: A linear dynamic model of the thermoelectric cooler including the heat sink and the cooling-load heat exchanger was derived using small-signal linearization method. It shows that the dynamic model of a thermoelectric cooler has two poles and one zero. The linear dynamic model is shown to vary with operating conditions. A linear feedback system is designed for the cold-end temperature control of a thermoelectric cooler using the average linear dynamic model of the thermoelectric cooler and a PDF controller structure. The step response tests show that the controller has a very satisfactory performance. Some tests under variable cooling load and ambient temperature are also performed to examine the disturbance-rejection property of the controller. Experimental results show that the cold-end temperature can be maintained at the fixed value within ±0.1°C irrespective of the variations of the cooling load and the ambient conditions.

A stable self-tuning fuzzy logic control system for industrial temperature regulation

Abstract: A closed loop control system incorporating fuzzy logic has been developed for a class of industrial temperature control problems. A unique fuzzy logic controller (FLC) structure with an efficient realization and a small rule base that can be easily implemented in existing industrial controllers was proposed. It was demonstrated in both software simulation and hardware test in an industrial setting that the fuzzy logic control is much more capable than the current temperature controllers. This includes compensating for thermo mass changes in the system, dealing with unknown and variable delays, operating at very different temperature setpoints without retuning, etc. It is achieved by implementing, in FLC, a classical control strategy and an adaptation mechanism to compensate for the dynamic changes in the system. The proposed FLC was applied to two different temperature processes and significant improvements in the system performance is observed in both cases. Furthermore, the stability of the FLC is investigated and a safeguard is established.

PID controller tuning by frequency loop-shaping: application to diffusion furnace temperature control

Abstract: A frequency loop-shaping technique for tuning proportional-integral-derivative controllers is applied to temperature control of a three-zone industrial diffusion furnace used in semiconductor manufacturing. In this tuning method the controller parameters are tuned so as to minimize the difference between the actual and a target loop transfer function, in an /spl Lscr//sub /spl infin// sense. The problem is formulated in the frequency domain as a convex optimization which can be solved numerically in a reliable way. This method, combined with a system identification step, has produced very satisfactory controllers for the furnace temperature control application.

PID gain scheduling using fuzzy logic.

Abstract: A simple, yet robust and stable alternative to proportional, integral, derivative (PID) gain scheduling is developed using fuzzy logic. This fuzzy gain scheduling allows simple online duplication of PID control and the online improvement of PID control performance. The method is demonstrated with a physical model where PID control performance is improved to levels comparable to model predictive control. The fuzzy formulation is uniquely characterized by; (i) one fuzzy input variable involving the PID manipulated variable, (ii) two parameters to be tuned, while previously tuned PID parameters are retained, and (iii) a gain scheduling differential equation which relates the fuzzy and conventional PID manipulated variables and enables fuzzy gain scheduling.

Phase change formulation

Abstract: A thermal packaging system using a single phase change material (PCM) part in liquid and part in solid form to confine the temperature of the product within a predetermined range. The temperature ranges are determined by the selection of PCM formulation. The phase change materials selected have high latent heats of fusion and maintain relatively constant temperatures as they change phase. This permits light weight packaging with the maintenance of temperatures in narrow, preselected ranges over extended periods of time. A phase change formulation that can be adjusted to freeze at temperatures from +40° C. to below −30° C. is disclosed, comprising butanediol, selected percentages of distilled water, and nucleating agents. The phase change occurs over a narrow temperature range making this an ideal temperature control media. Nucleating or other agents are included to narrow the temperature range over which the phase change occurs.

Temperature control of an integrated circuit

Abstract: An apparatus and method for controlling temperature during pre-delivery testing of microprocessors and integrated circuits wherein a testing package, including a thermally conductive lid overlying and in thermal contact with the microprocessor or integrated circuit, is covered by a block of thermally conductive material of predetermined thickness T, where T is a function of a desired temperature profile and, optionally, the current drawn by the microprocessor undergoing testing.

Id tag with sensor, and container, clinical thermometer, temperature control system and position control system attached with the same

Abstract: PROBLEM TO BE SOLVED: To measure the physical quantity of an object in an ID tag to be communicated with an external device through the electric wave. SOLUTION: This ID tag 1 is provided with a sensor unit 3 provided with a temperature sensor 13. A CPU 12 of this sensor unit 3 writes the temperature measured by the temperature sensor 13 every predetermined time into an EEPROM 15. The temperature data written in the EEPROM 15 can be read out by an external reader writer. For example, if such an ID tag 1 with sensor is provided in a beer cask, temperature change of the beer cask over the time from delivery from a beer brewery until served to a customer in a restaurant or the like can be detected, and temperature control of the beer can be sufficiently performed.

Remote controller for air-conditioning apparatus

Abstract: The present invention is provided with a remote controller case having an opening for air intake. The remote controller case includes a circuit board provided with a temperature detection circuit. The circuit board has a temperature sensor 26 corresponding to the opening for air intake. When the air-conditioning apparatus is installed, the output data of the temperature sensor 26 are corrected according to the installing environment. After the air-conditioning apparatus is installed, the output data of the temperature sensor 26 are corrected to have a temperature lowered by a predetermined degree to make the remote controller perform a temperature control operation.

Energy saving water heater control

Abstract: A water heater of the invention includes a water container; an element located to heat water in the water container; a sensor located to sense temperature; and a controller, the controller monitors the sensed temperature and compares the sensed temperature against a control temperature, with the controller further adjusting the control temperature a defined amount when the sensed temperature varies a desired amount from the control temperature.

Apparatus and method for temperature control of ic device during test

Abstract: An apparatus for controlling the temperature, during testing, of IC devices formed on a wafer includes a chuck for locating the devices during testing and multiple temperature control devices arranged on the chuck to correspond with the arrangement of the devices being tested on the wafer. The chuck itself can be cooled or heated, such as by the flow of a temperature-controlled fluid, and a temperature control device such as a heating element can be associated with each IC device being tested. Alternatively, a separate heat sink can be associated with each temperature control device and its corresponding IC device.

Implementation of an Inverse-Model-Based Control Strategy Using Neural Networks on a Partially Simulated Exothermic Reactor

Abstract: Recently, the use of control strategies based upon inverse process models for non-linear systems has been found promising. The requirement of a true analytical inverse can be avoided when neural network models are used; they have the ability to approximate both the forward and the inverse system dynamics. Although many simulation studies have illustrated the use of neural network inverse models for control, very few on-line applications have been reported. This paper describes a novel implementation of a neural network inverse-model based control method on a experimental system—a partially simulated reactor, designed to test the use of such non-linear algorithms. The implementation involved the control of the reactor temperature in the face of set point changes and load disturbances despite the existence of significant plant/model mismatch. Comparison was also made with conventional PID cascade control in several cases. The results obtained show the capability of these neural-network-based controllers and, incidentally, point out the differences between simulation studies and on-line experimental tests. Since the system in this study was only mildly non-linear, in some cases, the performance was comparable to that achieved by classical controllers while in other cases an improved control was achieved.

Integrated temperature and humidity controller with priority for humidity temperature control

Abstract: A controller for a climate control system has a humidity temperature sensor as well as a dry-bulb temperature sensor. A humidity temperature value is used in connection with a dry-bulb temperature value to generate an error signal that is a function of either the dry-bulb or the humidity temperature values. This permits control of both enclosure temperature and enclosure humidity without abnormal cycling of the climate control system. The humidity temperature can synthesized from the relative humidity and dry-bulb temperature within the enclosure.

Temperature control circuit for central processing unit

Abstract: A CPU temperature control circuit is provided that can vary the clock frequency and the power source voltage of a central processing unit (CPU) while the CPU meets the operational specifications. The comparison circuit 8 compares the temperature of the CPU 1 measured by the CPU temperature sensor 2 with temperature information previously stored in the ROM 6. The CLK and power-source control circuit 9 switches the clock frequency from a high frequency to a low frequency when the temperature of the CPU 1 becomes high. Then, the CKL and power-source control circuit 9 switches the power source voltage from a high voltage to a low voltage at the time the timer 12 counts up. When the temperature of the CPU 1 becomes low, the CLK and power-source control circuit 9 switches the power source voltage from a low voltage to a high voltage. Then, the CLK and power-source control circuit 9 switches the clock frequency from a low frequency to a high frequency at the time the timer 13 counts up.

Dynamic modelling of a combined cycle plant for power system stability studies

Abstract: This paper presents a mathematical representation of a combined cycle plant that is suitable for use in power system stability studies. The model incorporates gas turbine, heat recovery steam generator and steam turbine and includes speed control, temperature control and inlet guide vane control. A PID controller is designed for the governor-gas turbine system to improve system dynamic performance. The proposed combined cycle plant model and its controls are tested on a simple two-area power system. The performance of the combined cycle plant is investigated following system disturbances.

Motor drive-control device

Abstract: A motor drive-control device drive-controls a plurality of auxiliary devices with a single motor while securing a necessary capacity of the auxiliary devices side in correspondence with usage conditions. As such, in an air-conditioning system, necessary speeds of auxiliary devices such as a compressor and a warm water pump are calculated based on a necessary cooling capacity and a necessary heating capacity. The higher of these two necessary speeds is set as the motor speed for driving the auxiliary devices. The motor is thus controlled to this speed. Therefore, even if the air-conditioning heat load varies greatly due to changes in the usage environment, cooling and heating capacities necessary for air-conditioning temperature control can be obtained at all times.

Air conditioner for automobile

Abstract: PROBLEM TO BE SOLVED: To discriminate temperature control learning from other learning by adding area data for traveling of own vehicle to learning factors SOLUTION: This device is provided with a temperature sensor 1 for detecting a temperature inside or outside a compartment, an insolation quantity sensor 2 for detecting the quantity of incident solar light, an own vehicle position detecting means 4 for detecting the current position of own vehicle, a date and time information providing means 5 for outputting a current date and time, a comfort degree calculating means 3 and a learning means 6 The comfort degree calculating means 3 calculates the comfort degree of an in-room air conditioning environment based on an in-room temperature, a room outside temperature, the quantity of solar radiation, and a temperature set value when any air conditioner setting switch 7 is turned on by a manual operation The learning means 6 recognizes the manual operation performed for temperature control if the comfort degree is equal to a specified value or higher, and recognizes the manual operation performed for the purpose other than temperature control if the comfort degree is lower than the specified value Also, the position of own vehicle, data and time and the setting conditions of various actuators are stored in correlation with one another and, when the same condition appears more frequently than specified, the setting condition thereof is registered as learning correction data

Disk drive unit

Abstract: A disk drive unit carrier (1) is adapted to carry a single disk drive unit (2). The carrier (1) includes a temperature control device (4) for controlling the temperature of the disk drive unit (2). The temperature control device (4) is preferably in the form of an air flow control device (5, 6) for controlling the flow of air across the disk drive unit (2) appropriately according to the required temperature for the disk drive unit (2).

Modeling and predictive control of a reheating furnace

Abstract: Reheating furnaces in iron and steel industry are main facilities of hot charge rolling processes. The main objective of such a reheating furnace is to control billet temperature uniformly, thereby resulting in successful rolling process performance and high productivity. In this paper, a dynamic model of the reheating furnace is derived using material and energy balances. A multivariable controller design procedure is then presented on the basis of a system identification technique and a predictive control algorithm. Simulations show the effectiveness of the proposed scheme.

Low temperature co-fired ceramic-metal packaging technology

Abstract: Integrated packages incorporating multilayer ceramic circuit boards mounted on a metal support substrate can be used for temperature control by the metal support substrate. Various electronic components, as well as additional temperature control devices, can be connected to the circuit boards and to the metal support substrate to control or regulate the temperature of operation of the components. The integrated package can be hermetically sealed with a lid.