Compensation Of Temperature Effects Research Articles

Preparation of low remanence temperature coefficient (RT – 300 °C) SmDy (Co, Fe, Cu, Zr)z magnets and molecular field analysis

Dy doped SmCo magnets with the nominal composition of Sm1−xDyx (Co, Fe, Cu, Zr)z were prepared by powder metallurgy method. The influence of Dy content on the remanence temperature coefficient and microstructure of magnets was investigated. XRD and TEM analysis showed that the magnets with different Dy content consisted of 2:17R cell phase and 1:5H cell boundary. Magnetic performance characterization showed that the remanence of the magnets decreased but the remanence temperature coefficient reduced as well with the increase of Dy content. When x was increased to 0.5, a comprehensive magnetic performance was obtained of which the remanence temperature coefficient (α) was 0.015%/°C in the temperature range of 20–300 °C and the maximum energy product descended tardily from 10.8 MGOe to 9.3 MGOe as the temperature rose from 20 °C to 300 °C. The two sub-lattice molecular field theory was used to calculate the temperature dependence of magnets remanence and to explain the temperature compensation effect of Dy content, the calculated results was in well correspondence with experimental results. Such method could also be used for the exploration of new thermal stability of magnets.

Note: Temperature-frequency calibration method based on spectral analysis for QCR dew point sensor.

Each quartz crystal resonator (QCR) shows different frequency behavior as a function of temperature. To get the curve of the temperature effect compensation during the dew-deposition process, we use the active controlled temperature type of the QCR dew point sensor. In this note, a QCR temperature-frequency calibration method based on spectral analysis is described. It combines FFT and spectral refinement and the parameter table method to achieve high precision frequency extraction. Frequency identification accuracy is 10-6. The results showed that the method has a good performance in frequency extraction of the QCR sensors.

A low power, temperature compensated, robust design of CS amplifier in nanoscale regime

A low power, temperature compensated, robust design of CS amplifier is proposed in this paper. A new voltage reference is introduced to enhance reliability of the design and decrease sensitivity of design metrics to temperature changes. The temperature compensation effect is explained and analytically modeled. Further, the amplifier consumes 1.34× less power than the other topologies available in literature due to subthreshold operation of devices in the biasing circuit and is suitable for extremely high temperature applications. All theoretical results are validated with simulation results obtained by simulating the circuit using Virtuoso Analog Design Environment of Cadence @ 45-nm technology node using metal gate/high-K/strained silicon BSIM4 model.

An effective temperature compensation approach for ultrasonic hydrogen sensors

Hydrogen is a kind of promising clean energy resource with a wide application prospect, which will, however, cause a serious security issue upon the leakage of hydrogen gas. The measurement of its concentration is of great significance. In a traditional approach of ultrasonic hydrogen sensing, a temperature drift of 0.1 °C results in a concentration error of about 250 ppm, which is intolerable for trace amount of gas sensing. In order to eliminate the influence brought by temperature drift, we propose a feasible approach named as linear compensation algorithm, which utilizes the linear relationship between the pulse count and temperature to compensate for the pulse count error (ΔN) caused by temperature drift. Experimental results demonstrate that our proposed approach is capable of improving the measurement accuracy and can easily detect sub-100 ppm of hydrogen concentration under variable temperature conditions.

Effect of Temperature Compensation on Measurement of Pressure Distribution for Inner Flow Fields using Pressure Sensitive Paint

Effect of Temperature Compensation on Measurement of Pressure Distribution for Inner Flow Fields using Pressure Sensitive Paint

A fiber bragg grating pressure sensor with temperature compensation based on diaphragm-cantilever structure

Pressure sensors are essential devices for pressure measurement and safety evaluation in modern industrial production and engineering application. According to the FBG sensing technology, this paper presents and studies a FBG pressure sensor that uses a diaphragm and a cantilever as a sensing unit. Two FBGs of this sensor are bonded on the top and bottom surfaces of the cantilever, respectively, and the center wavelength shift difference between the two FBGs is used as a measuring signal, thus improving the pressure measuring sensitivity and avoiding any effect of temperature cross-sensitivity. The measuring principle of this sensor is introduced, and the diaphragm structure of the sensor is analyzed through theoretical calculation and finite element analysis. Experimental results indicate that this sensor has a sensitivity of 339.956pm/MPa and a linear fitting coefficient of 99.997% in the pressure range from 0 to 10MPa, and the maximum pressure measuring error caused in the temperature range from 5 to 70°C is 0.93%, so the temperature compensation effects are remarkable. Such a FBG pressure sensor can be extensively used for quasi-distributed long-term online monitoring of the static or dynamic pressure of liquid or gas in industrial production.

Compensation of temperature effects for in-situ soil moisture measurement by DPHP sensors

Dual probe heat pulse (DPHP) sensors are economical solutions for soil moisture measurements. However, in agriculture fields the temperature significantly changes from time to time during 24h, which affects response of the soil moisture sensor. This paper, analyzes and models the error produced in the response of the DPHP sensors due to variation of the soil temperature. For this purpose, first effect of the soil temperature on the response of the sensor is studied using eight different soil samples. Accordingly, the existing soil moisture model, used for DPHP devices, is modified and used for the temperature compensation. A low power DPHP sensor comprising one heater probe and one temperature sensor probe, placed 0.003m apart, is fabricated. A low power, automated system, dissipating average power of 30mW, is also developed for the field measurements to validate the proposed model. The developed system is deployed in the field and soil moisture is measured for 38h at every 1h interval. Field measurements indicates that volumetric moisture content measured without temperature compensation leads to error of about 3% and with temperature compensation the error is reduced to 0.5%.

Long-term monitoring of ground anchor tensile forces by FBG sensors embedded tendon

Recently, there has been significant interest in structural health monitoring for civil engineering applications. In this research, a specially designed tendon, proposed by embedding FBG sensors into the center king cable of a 7-wire strand tendon, was applied for long-term health monitoring of tensile forces on a ground anchor. To make temperature independent sensors, the effective temperature compensation of FBG sensors must be considered. The temperature sensitivity coefficient

A 0.7-V, 8.9- $$\upmu \hbox {A}$$ μ A compact temperature-compensated CMOS subthreshold voltage reference with high reliability

This paper focuses on the study of a compact tem-perature-compensated CMOS voltage reference (VR) with high reliability. The temperature coefficient (TC) of the gate-source voltage for a subthreshold NMOSFET has been derived and utilized to perform effective temperature compensation with a proportional to absolute temperature (PTAT) drain current. The desirable PTAT current is provided with reliable power supply rejection ratio (PSRR) based on low-voltage self-biased cascode subthrehold operation with enhanced negative feedback. The resulting reference voltage is less sensitive to the process variations of on-chip resistors and absolute currents as well as the TC and PSRR. In addition, the impact of the gate-source voltage variation is alleviated, thus ensuring high reliability of the proposed VR. The measurement results without trimming in 40-nm CMOS process demonstrate that the average of TC is 5.1 and 19.1 $$\hbox {ppm}/^\circ \hbox {C}$$ppm/?C in the temperature range of ?20 to ?80 $$^\circ \hbox {C}$$?C and ?40 to ?120 $$^\circ \hbox {C}$$?C, respectively, and the worst PSRR of ?55.0 dB at 300 kHz is achieved, while the line regulation is better than 0.32 mV/V in the supply range of 0.9---1.6 V. The average current consumption is 8.9 $$\upmu \hbox {A}$$μA at 0.7-V supply, with a die area of only 0.006 $$\hbox {mm}^2$$mm2.

Compensation of Temperature Effects in Long-Term Monitoring of a Highway Bridge located in the Austrian Alps

This contribution addresses the compensation of temperature effects on a natural frequency of a highway bridge located in the Austrian Alps with seasonal ambient temperature fluctuation above and below freezing. This frequency identified from the ambient acceleration response recorded in a five-year monitoring campaign shows a pronounced temperature dependency. Two different methods are proposed and effectively applied to compensate this undesired temperature effect. In the first approach a direct correlation between natural frequency and ambient temperature is established, whereas the more sophisticated approach is based on a dynamic time-series model of Box-Jenkins type.

Effect of water chemistry upsets on the dynamics of corrective reagent dosing systems at thermal power stations

Typical disturbances in the dynamics of a corrective reagent dosing system under unsteady-state conditions during the unsatisfactory operation of a chemical control system with some water chemistry upsets at thermal and nuclear power stations are considered. An experimental setup representing a physical model for the water chemistry control system is described. The two disturbances, which are most frequently encountered in water chemistry control practice, such as a breakdown or shutdown of temperature compensation during pH measurement and an increase in the heat-transfer fluid flow rate, have been modeled in the process of study. The study of the effect produced by the response characteristics of chemical control analyzers on the operation of a reagent dosing system under unsteady-state conditions is important for the operative control of a water chemistry regime state. The effect of temperature compensation during pH measurement on the dynamics of an ammonia-dosing system in the manual and automatic cycle chemistry control modes has been studied. It has been demonstrated that the reading settling time of a pH meter in the manual ammonia- dosing mode grows with a breakdown in temperature compensation and a simultaneous increase in the temperature of a heat-transfer fluid sample. To improve the efficiency of water chemistry control, some systems for the quality control of a heat-transfer fluid by a chemical parameter with the obligatory compensation of a disturbance in its flow rate have been proposed for use. Experimental results will possibly differ from industrial data due to a great length of sampling lines. For this reason, corrective reagent dosing systems must be adapted to the conditions of a certain power-generating unit in the process of their implementation.

Compensation of temperature effect on impedance responses of PZT interface for prestress-loss monitoring in PSC girders

In this study, a method to compensate the effect of temperature variation on impedance responses which are used for prestress-loss monitoring in prestressed concrete (PSC) girders is presented. Firstly, an impedance-based technique using a mountable lead-zirconate-titanate (PZT) interface is presented for prestress-loss monitoring in the local tendon-anchorage member. Secondly, a cross-correlation-based algorithm to compensate the effect of temperature variation in the impedance signatures is outlined. Thirdly, lab-scale experiments are performed on a PSC girder instrumented with a mountable PZT interface at the tendon-anchorage. A series of temperature variation and prestress-loss events are simulated for the lab-scale PSC girder. Finally, the feasibility of the proposed method is experimentally verified for prestress-loss monitoring in the PSC girder under temperature-varying conditions and prestress-loss events.

Tuning the temperature coefficient of resonant frequency for 8-layer twinned hexagonal perovskite Ba8ZnTa6O24 ceramics

High-Q dielectric materials ilmenite MgTiO3, columbite MgNb2O6 and cubic perovskite Ba3NiTa2O9 with negative temperature coefficient of resonant frequency (τf) were selected as candidates for compensating the τf of hexagonal perovskite Ba8ZnTa6O24. X-ray diffraction data shows that Ba8ZnTa6O24 coexists with Ba3NiTa2O9 but is not compatible with MgTiO3 and MgNb2O6 at high temperature. The τf for the mixed hexagonal/cubic perovskite Ba8ZnTa6O24–Ba3NiTa2O9 system is tunable via the temperature compensation effect and its quality factor may be improved via annealing the ceramics at high temperature to enhance the cation ordering in the cubic component. Permittivity er ~ 22–25, Q×f > 30,000 GHz and tunable τf within ±10 ppm/°C were achieved in the range of about 50–80 wt% Ba3NiTa2O9 for the hexagonal/cubic perovskite composite Ba8ZnTa6O24–Ba3NiTa2O9 ceramics, which is suitable for the application as dielectric resonators and filters.

Similar metabolic rate-temperature relationships after acclimation at constant and fluctuating temperatures in caterpillars of a sub-Antarctic moth

Temperature compensation in whole-animal metabolic rate is one of the responses thought, controversially, to characterize insects from low temperature environments. Temperature compensation may either involve a change in absolute values of metabolic rates or a change in the slope of the metabolic rate – temperature relationship. Moreover, assessments of compensation may be complicated by animal responses to fluctuating temperatures. Here we examined whole animal metabolic rates, at 0°C, 5°C, 10°C and 15°C, in caterpillars of the sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae), following one week acclimations to 5°C, 10°C and 15°C, and fluctuating temperatures of 0–10°C, 5–15°C, and 10–20°C. Over the short term, temperature compensation was found following acclimation to 5°C, but the effect size was small (3–14%). By comparison with caterpillars of 13 other lepidopteran species, no effect of temperature compensation was present, with the relationship between metabolic rate and temperature having a Q10 of 2 among species, and no effect of latitude on temperature-corrected metabolic rate. Fluctuating temperature acclimations for the most part had little effect compared with constant temperatures of the same mean value. Nonetheless, fluctuating temperatures of 5–15°C resulted in lower metabolic rates at all test temperatures compared with constant 10°C acclimation, in keeping with expectations from the literature. Absence of significant responses, or those of large effect, in metabolic rates in response to acclimation, may be a consequence of the unpredictable temperature variation over the short-term on sub-Antarctic Marion Island, to which P. marioni is endemic.

A 32 ppm/°C temperature-compensated operational amplifier for application in medical device tracking

This paper presents a low-power, low-noise and high precision operational amplifier for a tracking system containing the intelligent medical device, and is an extended version of paper previously published by Nenadovic et al. in proc. of ICECS 2014. The accuracy of the tracking system strongly depends on the accurate amplitude acquisition of the received signal. Therefore, an operational amplifier with precise gain control and effective temperature compensation has been designed and fabricated. The operational amplifier provides linear and temperature independent signal amplification at frequencies between 0.2 and 20 kHz at a body temperature. The amplifier shows measured gain over temperature sensitivity as low as 32 ppm/°C in temperature range from 20 to 40 °C and consumes 300 μA from a supply voltage of 2.5 V. Furthermore, the measured gain over temperature sensitivity in the range from ?40 to 130 °C is only 60 ppm/°C. Simulated linearity for signal amplitudes up to 10 mV is 0.4 % and the input-referred noise at 1 kHz is 32 nV/?Hz. An open-loop gain of 46 dB at 1 kHz and bandwidth-gain product of 4.8 MHz is measured. The operational amplifier was designed in IHPs 250 nm SiGe BiCMOS technology and occupies an area of 0.2 mm2.

Passive temperature compensation in hydraulic dashpot used for the shut-off rod drive mechanism of a nuclear reactor

Passive temperature compensating hydraulic dashpot has been studied numerically as well as experimentally in this paper. Study is focused on reducing the clearances of the hydraulic dashpot at elevated temperature which intern compensates for the reduction in viscosity of damping oil and the dashpot gives uniform performance for wide range of temperature variation. Temperature compensation effects are mainly due to difference in the thermal expansion of materials. Different combinations of materials are used to reduce the dashpot clearances at elevated temperature. Finite element commercial code COMSOL Multiphysics 5.1 has been used for numerical analysis. Fluid-structure analysis has been carried-out to study the thermal expansion and pressure generated in the hydraulic dashpot. Multiphysics study with solid mechanics, laminar flow and moving mesh interfaces has been carried-out. Thermal expansion results of study-1 (solid mechanics) are further extended in to study-2 (laminar flow and moving mesh) and dashpot pressure is estimated. These results show that bimetallic strip improves the dashpot performance at 55°C but do not fully compensate beyond that and less severe impacts occurs. Specific combinations of design and materials have been presented in this paper for obtaining maximum temperature compensation. A novel passive temperature compensating hydraulic dashpot design has been presented, which is suggested for use over wide range of temperature change without much variation in the damping performance.

Does temperature affect the accuracy of vented pressure transducer in fine-scale water level measurement?

Abstract. Submersible pressure transducers have been utilized for collecting water level data since the early 1960s. Together with a digital data logger, it is a convenient way to record water level fluctuations for long-term monitoring. Despite the wide use of pressure transducers for water level monitoring, little has been reported regarding their accuracy and performance under field conditions. The effects of temperature fluctuations on the output of vented pressure transducers were considered in this study. The pressure transducers were tested under both laboratory and field conditions. The results of this study indicate that temperature fluctuation has a strong effect on the transducer output. Rapid changes in temperature introduce noise and fluctuations in the water level readings under a constant hydraulic head while the absolute temperature is also related to sensor errors. The former is attributed to venting and the latter is attributed to temperature compensation effects in the strain gauges. Individual pressure transducers responded differently to the thermal fluctuations in the same testing environment. In the field of surface hydrology, especially when monitoring fine-scale water level fluctuations, ignoring or failing to compensate for the temperature effect can introduce considerable error into pressure transducer readings. It is recommended that a performance test for the pressure transducer is conducted before field deployment.

Signal-based nonlinear modelling for damage assessment under variable temperature conditions by means of acousto-ultrasonics

Damage assessment can be considered as the main task within the context of structural health monitoring (SHM) systems. This task is not only confined to the detection of damages in its basic algorithms but also in the generation of early warnings to prevent possible catastrophes in the daily use of the structures ensuring their proper functioning. Changes in environmental and operational conditions (EOC), in particularly temperature, affect the performance of SHM systems that constitutes a great limitation for their implementation in real world applications. This paper describes a health monitoring methodology combining the advantages of guided ultrasonic waves together with the compensation for temperature effects and the extraction of defect-sensitive features for the purpose of carrying out a nonlinear multivariate diagnosis of damage. Two well-known methods to compensate the temperature effects, namely optimal baseline selection and optimal signal stretch, are investigated within the proposed methodology where the performance is assessed using receiver operating characteristic curves. The methodology is experimentally tested in a pipeline. Results show that the methodology is a robust practical solution to compensate the temperature effects for the damage detection task. Copyright © 2015 John Wiley & Sons, Ltd.

The circadian rhythms of photosynthesis, ATP content and cell division in Microcystis aeruginosa PCC7820

Microcystis aeruginosa is one of the most common blue-green algae species that forms harmful water bloom, which frequently causes serious ecological pollution and poses a health hazard to animals and humans. To understand the progression of algal blooms and to provide a theoretical basis for predicting and preventing the occurrence of algal blooms and reducing the harm of algal bloom to environment, we investigated the diurnal variation of photosynthesis, ATP content and cell division in M. aeruginosa PCC7820. The results showed that the photosynthesis and ATP content of M. aeruginosa PCC7820 exhibited clear circadian rhythm with a period of approximately 24 h and that the periodic rhythms continued for at least three cycles under continuous light conditions. Furthermore, the period length showed that a temperature compensation effect and changes in light cycle or temperature could reset the phase of circadian rhythm. These results indicate that the circadian rhythms of physiological process in M. aeruginosa PCC7820 are controlled by the endogenous circadian clock. Examinations of the number, size and cytokinin content of cells also reveal that the cell division of M. aeruginosa PCC7820 with the generation time of 38.4 h exhibits robust circadian rhythms with a period close to 24 h. The circadian rhythms of cell division may be generated by a biological clock through regulation of the cell division phase of M. aeruginosa PCC7820 via a gating mechanism. The phases in which cell division slows or stop recur with a circadian periodicity of about 24 h.

Temperature effect compensation for fast differential pressure decay testing

To avoid the long temperature recovery period with differential pressure decay for leak detection, a novel method with temperature effect compensation is proposed to improve the testing efficiency without full stabilization of temperature. The mathematical model of conventional differential pressure decay testing is established to analyze the changes of temperature and pressure during the measuring period. Then the differential pressure is divided into two parts: the exponential part caused by temperature recovery and the linear part caused by leak. With prior information obtained from samples, parameters of the exponential part can be identified precisely, and the temperature effect will be compensated before it fully recovers. To verify the effect of the temperature compensated method, chambers with different volumes are tested under various pressures and the experiments show that the improved method is faster with satisfactory precision, and an accuracy less than 0.25 cc min−1 can be achieved when the compensation time is proportional to four times the theoretical thermal-time constant.