Showing papers on "Temperature control published in 1998"

Method and apparatus for temperature control of a semiconductor electrical-test contractor assembly

Abstract: A semiconductor device handler with a temperature controlled test area. Temperature control is provided in part through the use of temperature controlled air forced across the test area. For heating the test area, electrical resistance heaters are uniformly distributed through the test area and are controlled to provide the desired temperature. The handler has a close pitch between adjacent sockets such that it is not possible to distribute refrigeration elements over the test area. Instead, a refrigeration element is placed on one side of the test area. To prevent formation of an undesirable temperature gradient, heat is injected at a specific location in the test area.

Temperature control for a bed

Abstract: A temperature control apparatus for a bed includes at least one heating element, mounted in a resting surface on a mattress of the bed for warming at least a first are(a of the resting area. A temperature sensor is located to detect the temperature of the first area of the resting area, and transmits the information to a central control unit. The central control unit includes a central processing unit which is interconnected with both the heating element and the temperature sensor to adjust the temperature in the first, area of the resting area as desired. The central control unit is also connected to a timer to permit programming of temperature changes as desired. An occupant sensor in the resting surface of the mattress will detect the presence and absence of an occupant, and transmit this information to the central control unit for processing.

Temperature control system for a workpiece chuck

Abstract: A system for and method of controlling the temperature of a flat workpiece such as a semiconductor wafer are disclosed. The workpiece is mounted on a workpiece chuck which is mounted over a base between the chuck and a host machine such as a wafer prober used to test integrated circuits on a wafer. The chuck includes an upper portion on which the workpiece is mounted. The temperature of the upper portion of the chuck is controlled to control the temperature of the workpiece. The temperature of the base is controlled to reduce the amount of heat flow between the chuck and the host machine. A power and control system includes a switching power supply which provides power to system components including heaters in the chuck used to heat the workpiece. A series of filters removes electrical noise generated by the switching power supply such that low-noise operation is realized.

Heat treatment apparatus

Abstract: PROBLEM TO BE SOLVED: To obtain a heat treatment apparatus which can realize quick temperature control and improved in uniformity of heat treatment surface by providing a protection pipe accommodation part of a projection-shaped section in a processing container to enable a small diameter of the container and direct detection of heat emitted from an object to be treated. SOLUTION: In the heat treatment apparatus, a plurality of objects W to be processed mounted in an object port 30 at a predetermined pitch are accommodated within a vertical heat treatment container 28 having a heating means 54 arranged therearound, a processing gas is made to flow through the interior of the container 28, a power to be supplied to the heating means 54 is controlled based on detected values of temperature measuring means 74A to 74D provided in the container 28 to subject the objects W to predetermined heat treatment. In order to accommodate the measuring means 74A to 74D within the protection pipe 76 and to accommodate the container 28 within the pipe 76, a protection-pipe accommodation part 72 projected radially outwards is provided along its height direction. As a result, the protection pipe 76 can be accommodated within the protection-pipe accommodation part 72, the diameter of the container 28 can be made small, heat issued from the objects W can be directly detected, thus realizing quick temperature control and improved in-plane uniformity of heat treatment.

Method and apparatus for pressure infusion and temperature control of infused liquids

Abstract: A method and apparatus for pressure infusion and temperature control of infused liquids includes a receptacle for receiving a liquid-filled bag containing intravenous solution or other liquid and an inflatable pressure device. The inflatable pressure device is disposed within a pressure device bag and is positioned proximate the liquid-filled bag in the receptacle. The inflatable pressure device expands within the pressure device bag upon inflation and exerts pressure on the liquid-filled bag. A heating element may be disposed on the inflatable pressure device bag to heat the liquid-filled bag to a desired temperature. The liquid may alternatively be maintained at a desired temperature, while flowing to a patient via a heating assembly disposed along a tube. The heating assembly includes a sleeve having a slot for receiving the tube and a plurality of individually controlled heaters. An infrared sensing device is mounted proximate a drip chamber to ascertain a drip count, while a temperature sensor is disposed within a holder that is positioned toward the entry site on a patient. A heat controller controls the heaters based on a drip count, while a safety controller disables heater operation in response to liquid temperature exceeding the desired temperature. Thus, the safety controller and heat controller, in combination, control the heating assembly heaters based on liquid temperature and flow rate, respectively. Alternatively, the liquid-filled bag may be heated to a desired temperature whereby the heating assembly includes a single heater controlled by a controller to maintain the liquid at the desired temperature during infusion of the liquid into a patient.

Temperature control apparatus with recirculated coolant

Abstract: A temperature control and process for adjusting the temperature of a workstation and a work medium at a workstation to a predetermined temperature. The temperature control comprises a cooling vehicle such as a heat exchanger, a coolant temperature sensor and control, a source of fluid coolant such as a manifold, a recirculating pump, a flow line to circulate the coolant to the workstation with the flow line containing a flow regulator and a heater, a bypass valve for bypassing the flow regulator and heater, and a workstation temperature sensor and control. The workstation temperature control controls the operation of the heater and bypass valve so that the temperature of the coolant is below the desired temperature for the workstation, thus achieving a rapid transient response while avoiding overcooling. The coolant temperature control and workstation temperature control may be in a temperature control computer, thus providing a large number of different operating sequences. A number of embodiments of workstations are also described.

A neural net model-based multivariable long-range predictive control strategy applied in thermal power plant control

Abstract: A constrained multivariable control strategy along with its application in more efficient thermal power plant control is presented in this paper. A neural network model-based nonlinear long-range predictive control algorithm is derived, which provides offset-free closed-loop behavior with a proper and consistent treatment of modeling errors and other disturbances. A multivariable controller is designed and implemented using this algorithm. The system constraints are taken into account by including them in the control algorithm using real-time optimization. By running a simulation of a 200 MW oil-fired drum-boiler thermal power plant over a load-profile along with suitable PRBS signals superimposed on controls, the operating data is generated. Neural network (NN) modeling techniques have been used for identifying global dynamic models (NNARX models) of the plant variables off-line from the data. To demonstrate the superiority of the strategy in a MIMO case, the controller has been used in the simulation to control main steam pressure and temperature, and reheat steam temperature during load-cycling and other severe plant operating conditions.

Optimal Control of Thermally Convected Fluid Flows

Abstract: We examine the optimal control of stationary thermally convected fluid flows from the theoretical and numerical point of view. We use thermal convection as control mechanism; that is, control is effected through the temperature on part of the boundary. Control problems are formulated as constrained minimization problems. Existence of optimal control is given and a first-order necessary condition of optimality from which optimal solutions can be obtained is established. We develop numerical methods to solve the necessary condition of optimality and present computational results for control of cavity- and channel-type flows showing the feasibility of the proposed approach.

Room temperature control apparatus having feedforward and feedback control and method

Abstract: A controller for heating, ventilating and air-conditioning distribution systems,which includes a feedforward and feedback control strategies. The controller has a feedforward control strategy that generates a control signal based on control set points and identified characteristics of the system, and which adaptively adjusts such set points based on changes that are measured with respect to the identified characteristics. The controller is particularly adapted for controlling the temperature during a heating or cooling operation in a controlled space.

Operation and Control of Dividing Wall Distillation Columns: Part 2: Simulation and Pilot Plant Studies Using Temperature Control

Abstract: This paper follows on from preliminary work to investigate the theoretical aspects of control of dividing wall columns in Part 1 of this paper. Two different control arrangements have been investigated using temperature control. Dynamic simulation was first used to test the control configurations. These were then investigated in a large-scale pilot plant. The simulation and pilot plant runs show the same basic trends from the control arrangements. In all cases, the control arrangements investigated proved to give a stable response to fluctuations in the feed to the column. Temperature control resulted in an off-set in one of the product purities. This was demonstrated in both simulation and practical runs. A procedure has been suggested to overcome this off-set by over-refluxing the column. The procedure allows the column to be designed for minimum over-refluxing.

Model-based control of strip temperature for the heating furnace in continuous annealing

Abstract: Presents the model of the heating furnace in continuous annealing processes for use in design of self-tuning control systems. A simplified mathematical model is derived from first principles. The model parameters are recursively estimated with an algorithm called recursive parameter estimation with a vector-type variable forgetting factor (REVVF). The REVVF algorithm was developed for such cases where some knowledge on parameter variability can be obtained beforehand. The control system of strip temperature presented here is hierarchical. The upper level is called "optimal preview control", which performs preset control. It previews the approaching setup change, which is the change of strip size or reference temperature, and optimizes the line speed and the strip temperature trajectory. Next, the lower level is called "temperature tracking control", which performs closed-loop control using the above trajectory as the control target. At this level, the generalized pole-placement self-tuning control was first employed; and later, the generalized predictive self-tuning control was introduced. These control methods were applied with some practical modifications and with the above mentioned REVVF. The control has been working successfully in several real plants.

Phase change system for temperature control

Abstract: A system and method for maintaining a temperature sensitive payload within a target temperature range, between a minimum temperature and a maximum temperature. Heat transfer devices are provided, having reservoirs for separately containing a first material and a second material, the materials having distinct and separate phase change temperatures which approximately bracket the target temperature range. The latent heats of transformation related to the respective phase changes of the first and second materials resist heating or cooling of the payload above or below the target temperature range.

Two-color corrugated quantum-well infrared photodetector for remote temperature sensing

Abstract: A quantum-well infrared photodetector (QWIP) based on the corrugated light-coupling scheme has been fabricated and tested for remote temperature sensing. The QWIP consists of two stacks of multiple quantum wells (MQWs), each sensitive in one of the atmospheric infrared transmission windows and each with a separate readout circuit. High optical coupling efficiency is obtained in both wavelength ranges, demonstrating the use of the corrugated structure for two-color detection. By monitoring the ratio of the photocurrent generated simultaneously in each MQW stack, the temperature of the object emitting the radiation can be determined, regardless of its emissivity and the geometrical factors. This temperature sensing ability is tested by using a blackbody radiator with precision temperature control as the target. The agreement between the measured and the preset temperatures indicates that the corrugated QWIP is capable of precision thermometric measurements.

Multivariable self-tuning temperature control for plastic injection molding process

Abstract: This paper develops a multivariable self-tuning predictive control for improving set-point tracking performance, disturbance rejection, and robustness of a temperature control system for an extruder barrel in a plastic injection molding process. The stochastic discrete-time multivariable mathematical model is built and its unknown system parameters are identified by using the recursive least-squares estimation method. The multivariable predictive control is derived based on the minimization of a generalized predictive performance criterion. A real-time self-tuning control algorithm is proposed and then implemented by using a digital signal processor (DSP) TMS320C31 from Texas Instruments. Experimental results are used to show the feasibility and effectiveness of the proposed method.

Temperature control of exhaust gas catalytic converters in vehicles

Abstract: A vehicle powertrain comprises an internal combustion engine 10 and an electric motor 14 capable of producing driving or braking torque for the vehicle. The exhaust system for the engine 10 includes a catalytic converter 22. A control unit 18 monitors the temperature of the catalytic converter 22 using a sensor 32 and controls the driving or braking torque produced by the electric motor 14 so that the load on the engine produces exhaust gases of a suitable temperature to keep the catalytic converter within its optimum operating temperature range while maintaining the desired total output of torque from the powertrain.

Temperature control in a ceramic membrane reactor

Abstract: A method for maintaining the temperature of an oxygen-selective ion transport membrane within a desired temperature range includes providing an ion transport reactor with the oxygen-selective ion transport membrane. An oxygen-donating feed gas is delivered to a cathode side at a first temperature, at a first rate, and at a first oxygen partial pressure and a reactant gas is supplied to an anode side at a second temperature and a second rate. A physical condition is then established within the ion transport reactor that favors the transport of elemental oxygen through the oxygen selective ion transport membrane as oxygen ions. One or more process variables are then regulated to maintain the temperature of the oxygen selective ion transport membrane within the desired range.

Design and experimental evaluation of a multivariable self-tuning PID controller

Abstract: In this paper, a new multivariable self-tuning PID controller design scheme is proposed. The proposed control scheme has a static matrix pre-compensator in order to reduce the interaction terms of the process transfer function matrix. The static matrix pre-compensator is adjusted by an online estimator. The p/spl times/p pre-compensated multivariate system is then controlled via 'p' univariate self-tuning PID controllers, whose parameters are adjusted by a second identifier placed around the pre-compensated plant. The PID parameters are calculated online based on the relationship between the PID and generalized minimum variance control laws. The proposed scheme is experimentally evaluated on a 2/spl times/2 level plus temperature control system. Experimental results illustrate the effectiveness of this new scheme.

Mold temperature control

Abstract: A method and system for controlling the temperature of a fluid cooled high temperature injection mold having fluid channels formed therein A high temperature injection mold has an operating temperature above the boiling point of water A flow of either elevated pressure or low pressure cooling water is passed through the fluid channels in the high temperature injection mold for a limited duration during the molding cycle to thereby reduce the temperature of the injection mold to a desired level Elevated pressure cooling water is elevated to a pressure level such that the cooling water will remain in a liquid state while passing through the fluid channels Low pressure cooling water is at a pressure level such that the cooling water enters the fluid channels in a liquid state and transitions to a vapor state within the fluid channels The cooling water may be provided to the high temperature injection mold in a closed loop system, wherein cooling water which is treated to remove contaminants therefrom is stored in a cooling water supply tank Used high temperature cooling water emerging from the fluid channels of the high temperature injection mold is preferably mixed with lower temperature cooling water from the cooling water supply tank before being returned to the cooling water supply tank Elevated or low pressure cooling water may be passed through some fluid channels in an injection mold while high temperature heating water is passed simultaneously through other fluid channels in the same mold

Adaptive control for the steam temperature of thermal power plants

Abstract: An adaptive control system was applied to control the steam temperature of utility boilers. In the control system, an adaptive control strategy is embedded on the DCS controllers in parallel with each conventional PID controllers for the boiler. The authors have successfully implemented the proposed system at Chubu Electric Power's Nishi-Nagoya No.3 unit and Owase-Mita No.l unit for controlling the main and reheat steam temperatures. The control improvement takes the form of reduced magnitude of temperature excursions caused by load changes, especially in the reheated steam temperature.

A laser module allowing simultaneous wavelength and power control

Abstract: An apparatus for simultaneously stabilising the output power and wavelength of a semiconductor laser is disclosed. A wavelength discriminating scheme is used to provide a wavelength error signal and an output power detection scheme is used to provide an output power level signal. The wavelength error signal is used to adjust the behaviour of a temperature sensor such that an automatic temperature control (ATC) module configured to maintain a pre-determined output from the temperature sensor, adjusts the actual laser temperature to minimize said signal. The output power level signal is directly delivered to an automatic power control (APC) module, which adjusts the drive current fed into the laser to minimize said signal using known control circuitry means. Adjusting the properties of the temperature sensor makes it possible for the apparatus to manipulate laser temperature and current to achieve simultaneous power, wavelength and temperature control, using the constant-temperature and constant-power external control modules used by semiconductor lasers that do not stabilize wavelength.

Methods and apparatus for monitoring water process equipment

Abstract: Methods and apparatus are provided for detection of leaks in boilers (10) containing a temperature control liquid (12) which is supplemented with feedwater and removed as blowdown. The methods include measuring rates associated with the feedwater supplementation and blowdown (18), adding a tracer to the temperature control liquid, determining the change in rate of the feedwater supplementation, determining the mass of the temperature control liquid, deriving the change in concentration of the chemical tracer in the temperature control liquid, calculating the unaccounted for water rate and comparing this rate with zero to determine if a leak condition is present.

Dynamically controlled crystal growth system

Abstract: Crystal growth can be initiated and controlled by dynamically controlled vapor diffusion or temperature change. In one aspect, the present invention uses a precisely controlled vapor diffusion approach to monitor and control protein crystal growth. The system utilizes a humidity sensor and various interfaces under computer control to effect virtually any evaporation rate from a number of different growth solutions simultaneously by means of an evaporative gas flow. A static laser light scattering sensor can be used to detect aggregation events and trigger a change in the evaporation rate for a growth solution. A control/follower configuration can be used to actively monitor one chamber and accurately control replicate chambers relative to the control chamber. In a second aspect, the invention exploits the varying solubility of proteins versus temperature to control the growth of protein crystals. This system contains miniature thermoelectric devices under microcomputer control that change temperature as needed to grow crystals of a given protein. Complex temperature ramps are possible using this approach. A static laser light scattering probe also can be used in this system as a non-invasive probe for detection of aggregation events. The automated dynamic control system provides systematic and predictable responses with regard to crystal size. These systems can be used for microgravity crystallization projects, for example in a space shuttle, and for crystallization work under terrestial conditions. The present invention is particularly useful for macromolecular crystallization, e.g. for proteins, polypeptides, nucleic acids, viruses and virus particles.

Generalized predictive control of optimal temperature profiles in a polystyrene polymerization reactor

Abstract: The performance of generalized predictive control (GPC) was examined when it was applied to the temperature of a free radical solution polymerization of styrene in a jacketed batch reactor. The optimal temperature policies were obtained at different initiator concentrations by applying the optimal control theory to the relevant polymerization reactor. The use of polynomial ARIMAX model related with reactor temperature and heat input was emphasised. Model parameters were determined by using Kalman, Bierman and Levenberg Marquardt algorithms. A pseudo random binary sequence (PRBS) signal was employed to operate the system. The GPC control method was based on ARIMAX model. The performance of the GPC method was compared with that of the PID controller.

Method and apparatus for improved temperature control in rapid thermal processing (rtp) systems

Abstract: A method for Rapid Thermal Processing (RTP) is presented, wherein the broadband reflectivity of an object is measured, and the results of the measurement used by the RTP system to adjust the RTP system parameters used in processing the object.

Evaluation of capacitors at cryogenic temperatures for space applications

Abstract: Advanced electronic systems designed for use in planetary exploration missions must operate efficiently and reliably under the extreme low temperatures of deep space environment. In addition, spacecraft power electronics capable of low temperature operation will greatly simplify the thermal management system by eliminating the need for heating units and associated equipment and thereby reduce the size and weight of the overall power system. In this study, film, mica, solid tantalum and electric double layer capacitors were evaluated as a function of temperature in terms of their dielectric properties. These properties included capacitance stability and dielectric loss in the frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also performed on the capacitors. The results obtained are discussed and conclusions are made concerning the suitability of the capacitors investigated for low temperature applications.

Temperature control system with thermoelectric and rechargeable energy sources

Abstract: A temperature control system for a gas-fired appliance which uses a thermoelectric device to develop power for recharging a primary energy source, such as a rechargeable battery. The present invention provides a reliable and efficient system for controlling and powering a temperature control system.