High Precision Temperature Research Articles

A residual compensation method for the calibration equation of negative temperature coefficient thermistors

We propose a calibration equation for negative temperature coefficient thermistors. This equation is modified from the basic thermistor equation by a residual compensation method. The residual compensated equation includes a 2nd order error correction term. This equation is convenient for converting temperature to resistance and vice versa. Calibrations of various thermistors were performed in a high precision temperature bath to test the resistance–temperature relation. The thermistors were calibrated in glass tubes using a reference thermometer. Most calibrations are performed in a temperature span (15–35°C). From the resistance–temperature curves, the fitting function of the basic thermistor equation and the residual compensated equation were evaluated and their fitting errors were compared. Standard fitting errors (1σ) in temperature of the basic equation and the residual compensated basic equation were 8.131mK and 0.151mK respectively. The residual compensated equation showed about 1/54 smaller fitting errors than the basic thermistor equation.

Calibration and self-validation of thermistors for high-precision temperature measurements

In this paper we discuss influencing variables affecting the uncertainty of high-precision temperature measurements (u<1mK) by means of NTC thermistors. These are proper instrument settings, a suitable choice (distribution) of calibration temperatures in due consideration of uncertainties, self heating and the number of parameters in the calibration equation. Within this work we used 4 wire measurements to eliminate the influence of lead resistances, switched dc current to reduce errors by thermoelectric effects and amplifier offsets, a reference resistor with a nominal value close to the thermometer resistance to maximize the resolution and a maximum current consistent with the input voltage range and self heating of the thermistor.We present results of high-precision calibrations of a so called super-stable thermistor and demonstrate the influence of changes of the calibration equation on the interpolation error. Our results confirm previous findings that the number of parameters in the interpolation equation can have a considerable influence on the interpolation error. It was confirmed that the Steinhart–Hart equation shows a poor performance and should be replaced by the more suitable models recommended in White et al. (2014). For the quantification of the long term stability of a calibration we recommend repeated single-point validations at the triple-point of water. If these are supplemented by measurements at the gallium fixed-point possible changes of the curvature of the characteristics can be detected.

High‐Precision Measurements of Lower Atmospheric Temperature Based on Pure Rotational Raman Lidar

AbstractA pure rotational Raman (PRR) lidar system was built for high precision temperature measurements in the atmosphere from 10 km to 40 km height over Wuhan, China (30.5°N, 114.4°E). State of the art interference filters for light splitting and filtering were designed to extract the required PRR signals and suppress elastically backscattered light. Observational results reveal that the maximum deviation of temperatures measured by the PRR lidar and the local radiosonde below 30 km is about 3.0 K, showing good consistency and reliability of the lidar. Obvious deviations may occur because of the balloon drifts, regional differences and special phenomena like the thermal inversion layer. Temperature profiles at different temporal scales are conductive to analysis of the wave properties and microstructures. For the 30 min integrated lidar temperature profile, the statistical error is about 0.3 K for altitudes of 10∼20 km with 300 m spatial resolution; ∼0.8 K for 20∼30 km with 600 m resolution; and 3.0 K for 30∼40 km with 900 m resolution, respectively. Besides, one‐night temperature profiles are given for the long‐term observation of the atmospheric thermal structure. Temperature measurement up to 40 km by the PRR lidar shows great potential for the further combination with the Rayleigh lidar of 30∼80 km detection capacity, which provides an effective means for the study of the lower atmosphere to the upper stratosphere.

Experimental study of internal wave generation by convection in water

We experimentally investigate the dynamics of water cooled from below at and heated from above. Taking advantage of the unusual property that water’s density maximum is at about , this set-up allows us to simulate in the laboratory a turbulent convective layer adjacent to a stably stratified layer, which is representative of atmospheric and stellar conditions. High precision temperature and velocity measurements are described, with a special focus on the convectively excited internal waves propagating in the stratified zone. Most of the convective energy is at low frequency, and corresponding waves are localized to the vicinity of the interface. However, we show that some energy radiates far from the interface, carried by shorter horizontal wavelength, higher frequency waves. Our data suggest that the internal wave field is passively excited by the convective fluctuations, and the wave propagation is correctly described by the dissipative linear wave theory.

Research on High Precision Temperature Control System of Strap-Down North-Seeking

In order to make the dynamically tuned gyroscope of Strap-down North-seeking working on the best temperature environment, reduce errors caused by temperature changes, a high-precision temperature control system is built up on the base of control theory and engineering. This system is a two-stage temperature control system. In order to realize high precision temperature control at a predetermined temperature range, temperature measurement circuit is analyzed and calculated on a two-stage temperature control had different measurement circuit match. Experimental results show that the accuracy of can achieve ± 0.1 °Cwhen the environment temperature within the range of-40 °C ~ + 60 °C. It can meet the temperature requirements of Strap-down North-seeking system.

Design of High Precision Temperature Measurement System based on Labview

Using the LabVIEW software platform, a high precision temperature measuring device is designed based on the principle of the thermocouple. The system uses the STM32 MCU as the main control chip, using AD7076 analog digital converter. The converter has 8 channel, synchronous sampling, and bipolar input. Improving the precision of temperature measurement by cold end compensation, fitting and other measures. The test results show that, the device temperature measurement precision can reach ±0.1 °C, has the advantages of small size, high precision, and reliable performance, this high precision temperature measurement can be widely used in industrial production.

Group-Delay-Based Temperature Sensing in Linearly-Chirped Fiber Bragg Gratings Using a Kerr Phase-Interrogator

We present a novel temperature sensor based on temperature dependence of reflection group-delay in a linearly chirped fiber Bragg grating. The reflection group-delay of a chirped grating changes with temperature leading to a variation in the phase of a sinusoidal optical signal reflected from the grating. A Kerr phase-interrogator converts the phase variation into power variation allowing for high-precision temperature sensing. A temperature sensor with a resolution of 0.0089°C and a sensitivity of 1.122 rad/°C is experimentally demonstrated.

Meteorological insights from planetary heat flow measurements

Planetary heat flow measurements are made with a series of high-precision temperature sensors deployed in a column of regolith to determine the geothermal gradient. Such sensors may, however, be susceptible to other influences, especially on worlds with atmospheres. First, pressure fluctuations at the surface may pump air in and out of pore space leading to observable, and otherwise unexpected, temperature fluctuations at depth. Such pumping is important in subsurface radon and methane transport on Earth: evidence of such pumping may inform understanding of methane or water vapor transport on Mars. Second, the subsurface profile contains a muted record of surface temperature history, and such measurements on other worlds may help constrain the extent to which Earth’s Little Ice Age was directly solar-forced, versus volcanic-driven and/or amplified by climate feedbacks.

High-precision temperature determination of evaporating light-absorbing and non-light-absorbing droplets.

Models describing evaporation or condensation of a droplet have existed for over a century, and the temporal evolutions of droplet radius and temperature could be predicted. However, the accuracy of results was questionable, since the models contain free parameters and the means of accurate calibration were not available. In previous work (Hołyst et al. Soft Matter 2013, 9, 7766), a model with an efficacious parametrization in terms of the mean free path was proposed and calibrated with molecular dynamics numerical experiment. It was shown that it is essentially possible to determine reliably the temperature of a steadily evaporating/condensing homogeneous droplet relative to ambient temperature when the evolution of the droplet radius is known. The accuracy of such measurement can reach fractions of mK. In the case of an evaporating droplet of pure liquid, the (droplet) temperature is constant during the stationary stage of evaporation. In this paper, we show that, in many cases, it is also possible to determine the temporal evolution of droplet temperature from the evolution of the droplet radius if the droplet (initial) composition is known. We found the droplet radius evolution with high accuracy and obtained the evolution of droplet temperature (and composition) for droplets of (i) a two-component mixture of pure liquids; (ii) solutions of solid in liquid, one that is non-surface-active and another that is; and (iii) suspensions of non-light-absorbing and light-absorbing particles.

Adaptive iterative learning control based on unfalsified strategy for Chylla-Haase reactor

An adaptive iterative learning control based on unfalsified strategy is proposed to solve high precision temperature tracking of the Chylla-Haase reactor, in which iterative learning is the main control method and the unfalsified strategy is adapted to adjust the learning rate adaptively. It is encouraged that the unfalsified control strategy is extended from time domain to iterative domain, and the basic definition and mathematics description of unfalsified control in iterative domain are given. The proposed algorithm is a kind of data-driven method, which does not need an accurate system model. Process data are used to construct fictitious reference signal and switch function in order to handle different process conditions. In addition, the plant data are also used to build the iterative learning control law. Here the learning rate in a different error level is adjusted to ensure the convergent speed and stability, rather than keeping constant in traditional iterative learning control. Furthermore, two important problems in iterative learning control, i.e., the initial control law and convergence analysis, are discussed in detail. The initial input of first iteration is arranged according to a mechanism model, which can assure a good produce quality in the first iteration and a fast convergence speed of tracking error. The convergence condition is given which is obviously relaxed compared with the tradition iterative learning control. Simulation results show that the proposed control algorithm is effective for the Chylla-Haase problem with good performance in both convergent speed and stability.

Effect of postglacial warming seen in high precision temperature log deep into the granites in NE Alberta

The method how to reconstruct surface temperature history from inversions of precise temperature logs done in wells was pioneered earlier by Cermak (1971) and by Lachenbruch and Marshall (1986); (see: Bodri and Cermak 2007 for review and list of references on the subject). The method is based on the inversion of stabilized, high precision deep borehole temperature logs, which are in thermal equilibrium with surrounding rock. Deep down to some 2-km depth perturbation of the heat flow could be caused by warming since recent glaciations ending some 12–13 kyr ago in Canada (Ritchie 1983). Surface temperatures peaked in the Holocene Optimum 6–7 kyr ago known to be some 1–2 °C warmer than recent centuries temperature level (Kerwin et al. 1999). Perturbations observed down to 0.1–0.3 km are mainly related to the climate changes of the last 1–2 centuries (Pollack et al. 1998; Bodri and Cermak 2007; Rath et al. 2012) on large regional and continental scale. All these surface temperature changes influence the subsurface heat flow. The method has been applied to reconstruct timing and amplitude of surface temperature change from latest glacial to postglacial climatic history through many areas in Eurasia and North America (Hotchkiss and Ingersoll 1934; Cermak 1971; Kukkonen 1993; Kukkonen and Safanda 1996; Kukkonen et al. 1998; Mareschal et al.1999; Rolandon et al. 2003; Kukkonen and Joeleht 2003; Demezhko et al. 2007; Demezhko and Golovanova 2007; Majorowicz

Research on Temperature Control System for Vacuum Annealing Furnace Based on Neural Network-PID

Vacuum annealing is an important part in rare metal tube production, accurate control of the annea ling temperature has enormous influence on the quality of tubes.According to the technological characteristics and temperature control requirements of the vacuum annealing furnace ,a high precision temperature control system was built based on IPC, intelligent temperature controller and thyratron transistor power-regulator.The neural network-PID strategy was proposed to control temperature online through OPC interface, which realized accurate control and automatic detection of the whole process of annealing temperature. Field data indicates that this system has realized the accurate control of the vacuum annealing temperature, effectively improves the quality of rare metal tubes and has extensive application value.

Design and Implementation of the Insert Temperature Measuring and Control System

In recent years, along with the speeding up of the wide application of computer technology and information technology in our country, computer measurement control system has been widely used in more and more occasions. The temperature is an important parameter in many monitoring and control system. In some strictly requiring temperature monitoring, more real-time and high precision temperature measurement are needed. The traditional temperature measurement method is dependent on measuring the analog quantities of electronic components, and then converts it into visual measurement results. From the aspects of hardware circuit design, it is of great trouble to develop and takes much work, at the same time; the problem anti-interference is more outstanding. Modern temperature sensor is evolving from analog to digital, from integration to the direction of the intelligent in rapid development, making it convenient for this topic to measure temperature in the application field.

Design of High Precision Temperature Sensor Based on Platinum Resistance

for Pt100 platinum resistance temperature measurement system has low accuracy, duplicate hardware circuit design and other issues, the articles design a high-precision temperature measurement system with Pt100 platinum resistance. With Pt100 temperature sensor, article takes STM32F103 as the control center through filtering, amplification and other signal conditioning circuit and a method of combining software look-up table to compensate the nonlinear compensation, thus achieving high-precision temperature measurement. Research results show that the system has a measurement accuracy high stability, scalability, and other characteristics.

Evaporative cooling of speleothem drip water.

This study describes the first use of concurrent high-precision temperature and drip rate monitoring to explore what controls the temperature of speleothem forming drip water. Two contrasting sites, one with fast transient and one with slow constant dripping, in a temperate semi-arid location (Wellington, NSW, Australia), exhibit drip water temperatures which deviate significantly from the cave air temperature. We confirm the hypothesis that evaporative cooling is the dominant, but so far unattributed, control causing significant disequilibrium between drip water and host rock/air temperatures. The amount of cooling is dependent on the drip rate, relative humidity and ventilation. Our results have implications for the interpretation of temperature-sensitive, speleothem climate proxies such as δ18O, cave microecology and the use of heat as a tracer in karst. Understanding the processes controlling the temperature of speleothem-forming cave drip waters is vital for assessing the reliability of such deposits as archives of climate change.

Thermal conditions of the central Sinai Microplate inferred from new surface heat-flow values and continuous borehole temperature logging in central and southern Israel

This paper reports ten new surface heat-flow density (qs) values for central and southern Israel (central Sinai Microplate), whose crystalline crust and lithosphere formed as part of the Neoproterozoic Arabian-Nubian Shield. Heat flow was calculated in Mesozoic sediments using the classical approach of heat-flow determination by implementing in the analysis high-precision continuous temperature logs obtained in air- and/or water-filled boreholes. Thermal conductivity (TC) measured for a large suite of rock samples of lithotypes making up the sequence was assigned to temperature gradients in intervals for which the lithology was known. The heat-flow values obtained for different depth intervals in a borehole as well as the average values for the individual borehole locations cover a narrow range, attesting heat-conduction conditions. A steady-state thermal model along an E–W crustal cross section through the area shows that the observed systematic spatial distribution of the qs values, which range between 50 and 62mWm−2, can primarily be explained by variations in the thickness of the upper crust and in the ratio between sedimentary and crystalline rocks therein. Given the time lapse of thermal heat transfer through the lithosphere, the qs data monitor the crustal thermal conditions prior to rift- and plume-related lithospheric thermal perturbations that have started in the larger area ca. 30Ma ago. Observed and modeled qs display the best fit for a pre-Oligocene lithosphere–asthenosphere boundary (LAB) at ∼150km, which would be at the upper end of LAB depths determined from stable areas of the Arabian Shield (150–120km) not affected by the young, deep-seated thermal processes that have caused a further uprise of the LAB. Our data imply or predict that the surface heat flow of the Sinai Microplate generally tends to increase along N–S and W–E traverses, from ∼45–50mWm−2 to ∼55–60mWm−2. Surface heat flows on the order of 55–60mWm−2 may be common in the northern Arabian Shield, where it exhibits typical lithosphere structure and composition and is unaffected by young heating processes, compared to values of ≤45mWm−2 recently determined in the southern Arabian Plate for the Arabian Platform.

Research and development of a new low cost and high precise thermal resistance temperature measurement module

Research and development of a new low cost and high precise thermal resistance temperature measurement module

Active Disturbance Rejection-Based High-Precision Temperature Control of a Semibatch Emulsion Polymerization Reactor

A mathematical model can be used to mimic a real chemical, physical, or biological system. However, the process of idealizing the complicated real world into a relatively simple form requires making a set of assumptions and ignoring model variation, parameter changes, external disturbances, and noise. Therefore, no model can completely represent a real situation or process. On the other hand, if model uncertainties, parameter changes, and external disturbances are treated collectively as a “total disturbance” that is then estimated and canceled, extensive knowledge of the controlled object will no longer be required. In other words, good control performance is able to be achieved without a precise mathematical model. With this as the aim, active disturbance rejection control (ADRC), a modelfree control, presented in this paper is used to estimate and actively reject the inherent dynamic and external disturbances. In particular, it is shown in this paper that ADRC works well in the face of a nonlinear, time-varying process such as the Chylla–Haase semibatch polymerization reactor. This is because the problem of precise temperature regulation in the polymerization process can be reformulated as the problem of total disturbance rejection. The numerical results show the stability and robustness of the proposed method and better overall performance.

High Precision Low Power Quartz Temperature Transducer

This paper presents the design, fabrication and characterization of quartz tuning fork temperature sensor which is based on new ZY-cut-quartz crystal bulk acoustic wave resonator vibrating in a flexural mode. Design and performance analysis of the quartz tuning fork temperature sensor has been conducted and the thermal sensing characteristics were examined by measuring the resonance frequency shift of this sensor cause by an external temperature. The sensor prototype was successfully fabricated and calibrated from operating from 0°C to 100°C with sensitivity of 70ppm/°C. Experimental results show the sensor has high thermal sensitivity, good stability and well reproducibility. This work represents high precision and low power temperature sensor using the comprehensive thermal characterization of ZY-cut-quartz tuning fork resonator.

Analysis of Quartz Resonator Array Based on Data Fusion Technology for High Performance Thermal Sensors

In order to improve the accuracy and reliability of temperature measurements, put forward a kind of high precision non-contact temperature measuring system, which is composed of the quartz temperature sensor array and microprocessors. The sensor used by the system is the quartz tuning fork non-contact temperature sensor based on polymer line, and the polymer line that is highly sensitive to temperature is as the sensitive element, in combination with quartz tuning fork resonator that is not sensitive to the temperature , and they form the high precision temperature sensor together. Compared with the traditional thermometry, set up a new temperature sensor array to measure temperature, which uses the Bayes estimation to fuse the data measured by the temperature sensor array, and calculate the accurate temperature measurements. The experimental results shown that the measurement precision of sensing system is 0.02℃, and the sensitivity is 71.5×10 -6 /℃within temperature range from 0°C to 100°C.The system has advantages of the high precision, and the good stability, and reliable performance, etc.