High Precision Temperature Control Research Articles

SCM Based High Precision Temperature Controller Design

t is designed by adopting SUNPLUS SPCE061A version 16-bits Single Chip Microcomputer; it has realized functions as manual setting temperature, automatic temperature control, showing the real-time temperature of water. The testing mode of water temperature adopts AD590 version integrated analog temperature sensor to perceive the temperature of water in vessels and uses operational amplifier to amplify minute analog voltage signal outputted by sensor. It employs keyboard scan mode to set target temperature (40°C~90°C) and displays dynamically the real-time temperature of water with digestion. The system controls the guide circuit and closing of the heating device by using relay circuit, achieving the aim of keeping design temperature constant essentially. PID algorithm is adopted in water temperature control method. The proportion, integration and differential constant in PID algorithm are debugged with experiments in order to control the proportion of heating time and reduce the adjusting time of the system. The system boasts the advantages of high controlling precision, stability and reliability, flexible operation, strong currency.

高精度温控可调光栅滤波器的设计

高精度温控可调光栅滤波器的设计

Influence of digital averaging on the signal-to-noise improvement ratio of temperature control system used in single-photon detector at infrared wavelength

According to performance requirement of high precision temperature control system used in single-photon detector, the signal-to-noise improvement ratio (SNIR) achieved by digital averaging used in it is analyzed, and the functional relation between SNIR and average times, sampling period, length of sampling time and bandwidth of band limited white noise is given. Aiming at practical application, on condition that the total sampling time is limited, the influences of average time and sampling period on the SNIR of the system are calculated respectively, the expression of SNIR is given and the optimal sampling time is defined.

基于增量式PID算法的高精度温控系统的设计

温度传感器被广泛用于工农业生产、科学研究和生活等领域，在温控系统中发挥着重要的作用。而高精度的温控系统在测控仪器开发以及工业深加工过程中占有相当重要的地位，因此设计开发高精度的温控系统具有很强的应用价值和现实意义。本文在温控系统硬件设计的基础上，通过增量式PID算法，设计完成了一套控温范围在±0.1℃的高精度温控系统，相比现有同类温控系统，精度提高近10倍。 Temperature sensors are widely used in industrial and agricultural production, scientific research and other areas of life, and play an important role in the temperature control system. The high precision temperature control sys-tem has a very important place in measurement and control instrument development and deep processing industry. So, it has very strong application value and practical significance to design and develop a high precision temperature control system. In this paper, based on the hardware design of temperature control system, through incremental PID algorithm, a design of a temperature control in the range of ±0.1°C high precision temperature control system is completed, when compared with the existing similar temperature control systems, precision increases nearly 10 times.

臨床現場における高精度体温制御装置を用いた全身加温の検討

臨床現場における高精度体温制御装置を用いた全身加温の検討

The Technology of Mould Steel for Online Pre-hardening

Abstract This article describes a production method of mould steel pre-hardening, and focus on the advantage of this method, The technical core of method is the variable frequency and variable amplitude pulse uniform high-precision temperature control, which achieved by using strong-medium-weak water cooling, gas-water cooling and gas mist cooling composite cooling control technology. Optimizing the cooling rate path is a good method of optimizing quenched organization and structure.

Influence of poly(acrylic acid) on apatite formation studied byin situX-ray diffraction using an X-ray scattering reaction cell with high-precision temperature control

Organic additives influence crystallization processes in a multitude of ways. In biomineralization,e.g.bone or shell, such additives play a crucial role in morphology, and in polymorph and size control. However, the specific interactions between the additives and the growing mineral are in general unknown. Here, a model of bone mineralization, namely the formation of apatite nanocrystals under the influence of poly(acrylic acid), is studied usingin situX-ray diffraction. Since the kinetics of these reactions are very temperature dependent, a new X-ray scattering reaction cell has been developed that allows very high temperature precision, with an r.m.s. variation during operation of ∼0.05 K. The performance of the cell and its use in studying the apatite/poly(acrylic acid) system are discussed. The apatite formation process proceedsviathe formation of an amorphous precursor which then crystallizes. It is found that poly(acrylic acid) retards crystallization and reduces the growth rate of the forming crystallites.

The Design of High Precision Temperature Control Circuit for DFB Laser Diode

A circuit using the singlechip as key component for temperature control for DFB laser diode is designed in this article. An imbalance electrical bridge for measuring the temperature of laser diode is used in this circuit, and the result of measurement is converted to digital quantity by ADC. After that, the error signal is gotten through the digital PID calculation. At last, the DAC chip make error signal be voltage to drive power amplifier for TEC. The function of set point and display of real time temperature is also added. After the test for a long time, we confirm the precision of temperature is better than ±0.001°C.

Integrated Control for Crystal Growth Furnace in Space

空间晶体生长炉控制对象复杂, 具有纯滞后、强耦合、非线性等不利于控制的特性. 为实现炉温的精确控制, 提出了一个空间晶体生长炉综合控制方法并通过软件来实现. 将相关系数法和增广递推最小二乘法相结合, 辨识系统模型, 使用Hooke-Jeeves模式搜索法进行PID参数的自整定, 采用PID加前馈控制的算法对系统进行仿真, 使用同样的算法和控制参数对空间晶体生长炉进行实时控制, 并在控制的过程中实时调整控制参数, 以达到最佳的控制结果. 实验结果表明, 当三个温区的温度均达到700ºC时, 温度稳定度小于±0.3ºC, 满足系统设计要求. 同时介绍了实现综合控制软件的基本原理、功能、特点及在实际中的应用. 实际工程的应用结果表明, 该软件可满足空间晶体生长炉对控制系统的要求.

High-precision temperature control and stabilization using a cryocooler

We describe a method for precisely controlling temperature using a Gifford-McMahon (GM) cryocooler that involves inserting fiber-reinforced-plastic dampers into a conventional cryosystem. Temperature fluctuations in a GM cryocooler without a large heat bath or a stainless-steel damper at 4.2 K are typically of the order of 200 mK. It is particularly difficult to control the temperature of a GM cryocooler at low temperatures. The fiber-reinforced-plastic dampers enabled us to dramatically reduce temperature fluctuations at low temperatures. A standard deviation of the temperature fluctuations of 0.21 mK could be achieved when the temperature was controlled at 4.200 0 K using a feedback temperature control system with two heaters. Adding the dampers increased the minimum achievable temperature from 3.2 to 3.3 K. Precise temperature control between 4.200 0 and 300.000 K was attained using the GM cryocooler, and the standard deviation of the temperature fluctuations was less than 1.2 mK even at 300 K. This technique makes it possible to control and stabilize the temperature using a GM cryocooler.

A Study on High Precision Temperature Control of an Oil Cooler for Machine Tools Using Hot-gas Bypass Method

This study aims at precise control of oil outlet temperature in the oil cooler system of machine tools for enhancement of working speed and processing accuracy. PID control logic is adopted to obtain desired oil outlet temperature of the oil cooler system with hot-gas bypass method. We showed that the gains of PID controller could be easily determined by using gain tuning methods to get the gain of PID controller without any mathematical model. We also investigated various gain tuning methods to design the gains of PID and compared each control performance for selecting the optimal tuning method on the hot gas bypass method through experiments. Moreover, we confirmed excellent control performance with proposed PI controller gain even though disturbances were abruptly added to the experimental system.

The Development of a Separated Mini-Environment

This paper develops a new separated mini-environment to provide a constant temperature chamber for the placement of Micro/Nano-metrology instrument. In this paper, the rule of temperature change with time under natural convection and coercive convection is presented. The measurement and control system is composed of TEC, programmable power source and precise temperature measurement system. The mathematic model of the constant temperature chamber is identified making use of system identification theory and system identification toolkit of MATLAB. The temperature stability is improved by applying auto-adaptive PID method. Experiments show that the temperature fluctuation of a single-point is less than 0.02°C and the whole field is within 0.05°C. The goal of high-precision temperature control is achieved.

Thermal control of micro reverse transcription-polymerase chain reaction systems

Being beneficial from dramatic progress in biochemical and micro-electromechanical technologies, traditional DNA manipulation devices tend to be miniaturized to speed up detection processing. Polymerase chain reaction (PCR) and reverse transcription-polymerase chain reaction (RT-PCR) are two typical examples of them. In this report, micro RT-PCR (μRT-PCR) is designed to quantitatively detect viruses. Test samples reservoirs, RT-PCR, and capillary electrophoresis are integrated on a SU-8 based monolithic chip. A high-precision temperature control unit is well developed by embedding amplification circuits and an Intel 8051 microprocessor. The integrated system exhibits high efficacy of heat transfer, exemption of fluid flow clogging and adequate sensitivity to, by feedback, control the cycle of detection for the infected malignant tissues via intensive simulations.

Thermal trajectory control for micro RT-PCR biochips

Being beneficial from dramatic progress in bio-chemical and micro-electro-mechanical technologies, traditional DNA manipulation devices tend to be miniaturized to speed up detection processing. Polymerase chain reaction (PCR) and reverse transcription polymerase chain reaction (RT-PCR) are two typical examples of them. In this report, micro RT-PCR (μRT-PCR) is designed to quantitatively detect viruses. Test sample reservoirs, RT-PCR, and capillary electrophoresis are integrated on a SU-8 based monolithic chip. A high-precision temperature control unit is well developed by embedding amplification circuits and an Intel 8051 microprocessor. The integrated system exhibits high efficacy of heat transfer, exemption of fluid flow clogging and adequate sensitivity to, by feedback, control the cycle of detection for the infected malignant tissues via intensive simulations.

A high precision temperature control system for CMOS integrated wide range resistive gas sensors

In this work we present an integrated interface for wide range resistive gas sensors able to heat the sensor resistance through a constant power heater block at 0°C---350°C operating temperatures. The proposed temperature control system is formed by a sensor heater (which fixes the sensor temperature at about 200°C), a R/f (or R/T) converter, which converts the resistive value into a period (or frequency), and can be able to reveal about 6 decades variation (from 10 K? up to 10 G?), and a digital subsystem that control the whole systems loop. This interface allows high sensibility and precision and performs good stability in temperature and power supply drift and low power characteristics so it can be used also in portable applications. Test measurements, performed on the fabricated chip, have shown an excellent agreement between theoretical expectations and simulation results.

SU-8 based continuous-flow RT-PCR bio-chips under high-precision temperature control

Being beneficial from dramatic progress in bio-chemical and micro-electro-mechanical technologies, DNA manipulation devices can be miniaturized to expedite amplification processing for virus detection. Polymerase chain reaction (PCR) and reverse transcription polymerase chain reaction (RT-PCR) are two typical examples of them. In this report, a micro-RT-PCR (microRT-PCR) chip is designed to quantitatively detect tumor viruses. Test sample reservoirs, RT-PCR meanders, and capillary electrophoresis are integrated on a SU-8 based monolithic chip. A high-precision temperature control module is well developed by embedding signal amplification circuits and an Intel 8051 microprocessor. The integrated system exhibits high efficacy for heat transfer, exemption of fluid flow clogging and superior sensitivity to precisely control the required reaction temperatures in all heated zones of microRT-PCR unit. Intensive simulations and experiments are presented to verify the validity of the fabricated bio-chip.

Cryogenic precision digital temperature control with peaked frequency response

A high precision temperature control system capable of maintaining the temperature of superconducting quantum interference devices (SQUIDs) constant to within 1.0 μK root-mean square over a narrow frequency band was designed and built for use with the superconducting readout system of the Gravity Probe B experiment. The system utilizes an analog ac temperature bridge with a digital proportional-integral control loop which incorporates a peaking filter. A disturbance attenuation factor of 86 or greater over the required frequency band was demonstrated in system tests with the cryogenic hardware, allowing the SQUID system to achieve the required stability. The control system was robust against variations in the thermal characteristics of the cryogenic hardware.

Distributed strain sensing using frequency-modulated continuous-wave reflectometric optical technique

This paper presents an analysis describing the feasibility of a distributed optical fiber strain sensor whose principle of operation is based on the frequency-modulated continuous-wave (FMCW) reflectometry technique. The system consists of a frequency-swept laser diode and an unbalanced two-beam interferometer. In this system, the test arm comprises a number of single-mode fibers, which act as the sensing fibers, with a mirror at the far end and mechanical splices as the connectors, as well as the reflectors. Theoretical analysis shows that the measuring resolution of the strain is inversely proportional to the length of the sensing fiber. The strain variation of the sensing fiber is measured by demodulating the phase shift of the beat signal using a heterodyne signal processing system, and therefore the requirement of a high precision temperature control of the light source can be eliminated in this way. The comparison between the theoretical and experimental values of the strain resolution showed excellent agreement.

Quasi-distributed frequency-modulated continuous-wave reflectometric optical fiber strain sensor

We describe a quasi-distributed optical fiber strain sensor, whose principle of operation is based on the coherent frequency- modulated continuous-wave (FMCW) reflectometry technique. The sensing system is basically composed of a laser diode, which is frequency swept by a triangle waveform injection current and an unbalanced two- beam interferometer. Its test arm consists of a number of single-mode fibers, which act as sensing fibers, with a mirror at the far end and mechanical splices as the connectors as well as the reflectors. Theoretical analysis shows that the measuring resolution of the strain is inversely proportional to the length of the sensing fiber. To measure the strain variation of each sensing fiber, the phase shifts of the beat signals are demodulated by a heterodyne signal processing system. The requirement of a high precision temperature control of light source can be eliminated in this way, since temperature effect is insignificant to the phase demodulation technique. To calibrate and verify the linearity, feasibility, and accuracy of this system, tensile and bending tests were carried out and strain gauge was employed as the benchmarking tool over the experimental results. It was observed that this system is feasible and its accuracy is excellent.

Growth rate of high-quality large diamond crystals

In the diamond growth by temperature gradient method under high pressure and high temperature, the growth of a high-quality diamond crystal without metal inclusions has been investigated. Large high-quality type IIa diamond crystals without impurities of 7–8 ct (about 10 mm across) can be grown at a high growth rate of 6–7 mg/h by prolonged maintenance of a high-precision temperature control with an adequate selection of solvent metal and additives. Type Ib diamond crystals containing nitrogen impurities can be grown at higher growth rates up to 15 mg/h by using large seed crystals and adjusting the morphology with temperature control. This large seed method is not applicable for growing a type IIa diamond crystal because it is hard to control the crystal morphology of it.