Temperature Hysteresis Effects Research Articles

An In-Run Automatic Demodulation Phase Error Compensation Method for MEMS Gyroscope in Full Temperature Range.

The demodulation phase error will cause the quadrature error to be coupled to the rate output, resulting in performance deterioration of the MEMS gyroscope. To solve this problem, an in-run automatic demodulation phase error compensation method is proposed in this paper. This method applies square wave angular rate input to the gyroscope and automatically identifies the value of the demodulation phase error through the designed automatic identification algorithm. To realize in-run automatic compensation, the demodulation phase error corresponding to the temperature point is measured every 10 °C in the full-temperature environment (-40~60 °C). The relationship between temperature and demodulation phase error is fitted by a third-order polynomial. The temperature is obtained by the temperature sensor and encapsulated in the ceramic packages of the MEMS gyroscope, and the in-run automatic compensation is realized based on the fitting curve. The temperature hysteresis effect on the zero-rate output (ZRO) of the gyroscope is eliminated after compensation. The bias instability (BI) of the three gyroscopes at room temperature (25 °C) is reduced by four to eight times to 0.1°/h, while that at full-temperature environment (-40~60 °C) is reduced by three to four times to 0.1°/h after in-run compensation.

Precursor decomposition mechanism of In2O3 powder for oxide ceramic targets

In this study, precursor decomposition as well as nucleation and growth processes during the preparation of In2O3 powders via chemical precipitation were investigated. This is to provide guidance for the preparation of high-quality In-based oxide target powders. In-situ phase and microstructure evolution during thermal decomposition of precursors were analyzed. In addition, decomposition behavior of precursors at different heating rates was explored. Results show that amorphous In(OH)3 precursor powder gradually decomposes and transforms into crystalline In2O3 powder during heating process. Its degree of crystallinity increases with the increase in temperature. Fine and homogeneous In2O3 powder with average grain size of 54.46 nm was obtained by holding the powder at 770 °C for 3 h. The decomposition of precursors at any given heating rate can be divided into two stages: (i) dehydration and (ii) nucleation and crystallization. However, higher heating rate clearly results in temperature hysteresis effect, the occurrence of decomposition reaction at higher temperature, and an increase in the maximum reaction rate of decomposition reaction. Moreover, activation energy of thermal decomposition was obtained using model-free transformation method. Decomposition reaction model of In(OH)3 precursor was established using model-fitting method. It was deduced that first-stage reaction mechanism is three-dimensional diffusion. Reaction rate in this stage is controlled by product layer diffusion. Furthermore, second-stage reaction mechanism is random nucleation and subsequent growth. Reaction rate in this stage is controlled by nucleation and growth rates.

Preparation of form‐stable silica/polyethylene glycol composites using flash‐drying for large‐scale melt‐spun fibers with thermal management property

AbstractThe combination of phase change materials (PCMs) with fibers can afford smart fibers with thermal management properties. However, the issues of easy leakage and poor thermal stability of PCMs often limit their use in high‐temperature spinning. Herein, we report a form‐stable PCM of spherical SiO2/PEG composite that was prepared through flash‐drying using inorganic dendritic silica (D‐SiO2) as the core skeleton to support organic polyethylene glycol (PEG). The SiO2/PEG composite not only presents high crystallization enthalpy (101.35 J/g), but also maintains a superior phase change stability. Meanwhile, it exhibits a significant temperature hysteresis effect during heating and cooling, and the endothermic and exothermic time are 381.95 and 293.57 s, respectively. Because the degradation temperature of 300°C for SiO2/PEG is higher than the melt processing temperature of 240–270°C for the preparation of polyamide 6 (PA6) fibers, PA6/SiO2/PEG fibers were prepared using melt spinning. The prepared PA6/SiO2/PEG fibers exhibit high latent heat (17.14 J/g), outstanding thermal cycling stability and satisfactory temperature adjustment properties, and the temperature‐adjustment time of 458.97 s and temperature difference of 10.68°C under the thermal environment. Moreover, the tensile strength of PCFs‐20% reached 1.97 cN/dtex after drawing, which make PCFs meet the requirements of uses in textile industries.

Numerical Analysis and Poromechanics Calculation for Saturated Mortar Involved with Sub-Freezing Temperature.

The individual coupling processes of two-phase materials are controlled to some extent by damage theory. However, the existing theory is not sufficient to explain the effect of pore pressure on mortar materials under freeze-thaw action. In order to predict the resistance of saturated mortars during rapid cooling and to describe the physical behavior of the pore structure, the authors derived in detail the governing equations of saturated mortars during freezing in the framework of the pore elasticity theory and analyzed the sensitivity of physical parameters to the influence of temperature stresses by means of stress-strain calculations. In addition, the effects of phase change and latent heat of freezing on the local thermodynamic equilibrium are considered, and a mathematical model is established for quantitatively simulating the temperature distribution of the specimen. This model is reformulated and extended in the current work to intuitively reveal the effect of concrete dimensions on the temperature hysteresis effect. The results of the numerical model calculations show that during the freezing process, for the specimen with dimensions of 50 mm × 50 mm × 50 mm and a water-cement ratio of 0.6, the maximum temperature difference from center to surface is 10 °C, the maximum vertical strain on the surface is 4.27 × 10-4, and the maximum pore water pressure at the center of the specimen is 76 MPa. The model calculation results present a similar pattern to the physical interpretation and reference results, thus effectively evaluating the freezing damage process of saturated mortar.

Investigation of phase change materials (PCMs) on the heat transfer performance of building systems

The energy use of building systems contributes to a large percentage of total energy consumption, which requires consideration. Solutions of improvement to save energy are crucial. Phase change materials have been proved to be good candidates to be used in building envelopes for energy save. In this paper, an extended Explicit Finite Element Method (ex-FEM), which has been previously introduced and improved, is taken for simulation of temperatures and heat transfer in simplified multilayer wall constructions, consisting of PCM and insulation. The method has been validated against experimental data measured in a so-called Hot-Box. Temperature data are measured at different positions in a number of simplified multilayer walls. Our results show a reasonable good agreement between the simulations and the experiments, at both heating and cooling considering the temperature hysteresis effect in the PCM. The temperature stabilization ability of the PCM is clear, in both the simulations and the experiments, and particularly in the data when the transition range of the PCM is fully activated and matching the temperature variation in the wall at that particular PCM position. Our ex-FEM tool has here been proved to be able to predict the thermal performance of simplified wall constructions of multiple layers with PCMs incorporated.

Ultraviolet light-initiated preparation of phase change material microcapsules and its infrared imaging effect on fabric

PurposeThis study aims to explore the infrared imaging effect of fabrics coated with phase change material microcapsules (PCM-MCs), which are prepared by the initiation of ultraviolet (UV) light.Design/methodology/approachPCM-MCs were prepared by UV polymerization using paraffin (PA) as core material, polymethyl methacrylate as wall material and ferric chloride as photoinitiator. The effects of emulsifier dosage and emulsification temperature on the properties of PA emulsion were investigated. Scanning electron microscopy, particle size analysis, infrared spectroscopy, differential scanning calorimetry and infrared imaging test were used to characterize the properties of microcapsules.FindingsThe PCM-MCs with good morphology and particle size were prepared with 25 cm of the distance between light source and the liquid. The average particle size was 1.066 µm and the latent heat of phase transition was 19.96 J/g. After 100 accelerated thermal cycles, the latent heat only decreased by 1.8%. It had good heat storage stability and thermal stability. The fabric coated by the microcapsules exhibited a variable temperature hysteresis effect when placed in the sun, and presented a color close to the infrared images of the human palm under the external environment temperature close to the human body temperature.Research limitations/implicationsThe PCM-MCs prepared based on UV light initiation showed good thermal properties and its coated fabrics had an infrared decoy effect below the temperature of the human body.Practical implicationsThis study explored the application of microcapsules in textiles.Originality/valueThe microcapsules had a certain application potential in infrared decoy effect.

R-DTS With Heat Transfer Functional Model for Perceiving the Surrounding Temperature

In the field of temperature safety monitoring, it is important to quickly locate the position of temperature anomalies and start to alarm. The multimode fiber (MMF) has a certain temperature hysteresis effect when detecting the surrounding temperature along the sensing fiber, it deteriorates the warning-time of Raman distributed temperature sensor (R-DTS). This paper proposed and experimentally demonstrated an R-DTS with heat transfer functional model to perceive the surrounding temperature in advance. The temperature hysteresis effect of MMF cable in different temperature conditions are studied experimentally. The experimental results show that the temperature change rate of MMF and the surrounding temperature difference maintains a linear relationship after fitting. And this fitting relationship is used to perceive the surrounding temperature anomalies along the MMF for R-DTS system. The experimental results indicate that the warning-time of R-DTS can optimize from 23.4 s to 1.3 s at the temperature condition with 60 °C. It proves that this analytical model of the heat transfer function model can quickly perceive the environment temperature anomalies to avoid the temperature hysteresis effect of MMF at the difference temperature conditions. The research content can be applied in the temperature safety monitoring with high requirements for early-warning time, such as fire monitoring, power cable safety monitoring, and gas pipeline leakage detection.

Determination of L-Ascorbic Acid Using MBs-AOX/GO/IGZO/Al by Wireless Sensing System and Microfluidic Framework

In this paper, the L-ascorbic acid (L-AA) biosensor based on magnetic beads-ascorbate oxidase/graphene oxide/indium gallium zinc oxide/aluminum (MBs-AOX/GO/IGZO/Al) membrane was integrated with the potentiometric measurement system with the microfluidic framework in order to investigate the different sensing characteristics under the static condition and the dynamic condition. The L-AA biosensor showed the average sensitivity of 78.9 mV/decade (25 °C) under the static condition, and it showed the average sensitivity of 81.7 mV/decade (25 °C) at the optimal flow rate ( $25~\mu \text{L}$ /min). Besides, the XBee module was used to apply in the remote detection for the L-AA biosensor, and the experimental results were shown the average sensitivity of 78.7 mV/decade (25 °C). Moreover, we also investigated various experiments, such as temperature effect, hysteresis effect, and lifetime. These experimental results would be beneficial to the development of the L-AA biosensor based on electrochemical detection.

Equatorial secondary cosmic ray observatory to study space weather and terrestrial events

Recently, equatorial secondary cosmic ray observatory has been established at Equatorial Geophysical Research Laboratory (EGRL), Tirunelveli, (Geographic Coordinates: 8.71°N, 77.76°E), to study secondary cosmic rays (SCR) produced due to the interaction of primary cosmic rays with the Earth’s atmosphere. EGRL is a regional center of Indian Institute of Geomagnetism (IIG), located near the equator in the Southern part of India. Two NaI(Tl) scintillation detectors are installed inside the temperature controlled environment. One detector is cylindrical in shape of size 7.62 cm × 7.62 cm and another one is rectangular cuboid of 10.16 cm × 10.16 cm × 40.64 cm size. Besides NaI(Tl) detectors, various other research facilities such as the Geomagnetic observatory, Medium Frequency Radar System, Digital Ionosonde, All-sky airglow imager, Atmospheric electricity laboratory to measure the near-Earth atmospheric electric fields are also available at EGRL. With the accessibility of multi- instrument facilities, the objective is set to understand the relationship between SCR and various atmospheric and ionospheric processes, during space weather and terrestrial events.For gamma-ray spectroscopy, it is important to test the performance of the NaI(Tl) scintillation detectors and to calibrate the gamma-ray spectrum in terms of energy. The present article describes the details of the experimental setup installed near the equator to study cosmic rays, along with the performance testing and calibration of the detectors under various conditions. A systematic shift in the gain is observed with varying temperature of the detector system. It is found that the detector’s response to the variations in the temperature is not just linear or non-linear type, but it depends on the history of the variation, indicating temperature hysteresis effects on NaI detector and PMT system. This signifies the importance of isothermal environment while studying SCR flux using NaI(Tl) detectors, especially for the experiments conducted during daytime such as solar eclipses etc.

A Novel GMR-Based Eddy Current Sensing Probe With Extended Sensing Range

A common approach to detect a metal’s proximity or analyze some characteristic of it in applications, such as proximity sensing, non-destructive evaluation, and so on, is to generate eddy currents in it and then extract the desired information from the features of these eddy currents using eddy current sensors (ECSs). Some of the common ECS are Hall-effect sensors and inductive coils. Lately, giant magnetoresistive (GMR) sensors are also used for ECS due to their higher sensitivity and better low-frequency response. Due to these features, a new application has been identified for GMR-based ECS probes, which is real-time detection of metal shrapnel in human body during surgery. Since metal shrapnel cause grievous injuries to victims of bomb blasts, land mines, and so on, and the imaging modalities that doctors use presently to locate them do not provide any real-time information of their location during surgery, this probe will provide immense help to the doctors for tracing these shrapnel during surgery. However, existing GMR-based probes have limited sensing range, and therefore, they are not suitable for this application. Hence, a new probe topology is presented here, which has much longer sensing range than existing probes. The design of this probe, its performance, and the details of a new circuit that minimizes the temperature drift and hysteresis effects of the GMR sensor in the probe simultaneously are presented in this paper.

Strain induced super-paramagnetism in Cr2O3 in the ultra thin film limit

ABSTRACTUltra thin films of chromia (Cr2O3), less than 3 nm thick, grown epitaxial on α-Al2O3 (sapphire), and are thus compressively strained in-plane. The resulting films show evidence of some magnetic ordering above the Néel temperature of chromia (307 K). The observed higher temperature hysteresis effect observed are very likely a strain effect, and not associated with the typical antiferromagnetic ordering expected of chromia.

Water Temperature Modeling and Water Temperature Stratification Pattern of Reservoir Based on the Three-Dimensional Environment Fluid Dynamics Code Model

The three-dimensional flow-temperature numerical coupling model was established based on the Three-Dimensional Environment Fluid Dynamics Code Model. The reservoir water temperature was simulated coupled flow and water temperature and stratification pattern was analyzed attempting to provide scientific reference for water design and operation management on proposed reservoir, which could slow down the influence of low temperature water of proposed reservoir on ecological environment and aquatic biodiversity of the downstream river. Results show that reservoir water temperature stratification pattern distinguishes obviously among low temperature period, rising temperature period, high temperature period and cooling period and the temperature hysteresis effect is remarkable. The drainage of low-temperature water in summer should be prevented from influencing downstream ecological environment and the mechanism of the impact of high-temperature water in winter on ecological environment needs further study.

Peculiarities of thermoelastic martensite transformations under loading in CoNiGa single crystals with different number of variants of the γ′-phase particles

The influence of the number of variants of the dispersed γ′-phase particles on the B2–L10 martensite transformation (MT), temperature hysteresis, and shape memory effect (SME) in [123] single crystals of the Co49Ni21Ga30 (at.%) alloy is investigated. It is shown that the dispersed γ′-phase particles lead to a lowering of the onset temperature of MT, an increase in the temperature hysteresis, and a decrease in the magnitude of SME relative to single-phase crystals. The dependence of the magnitude of SME and of temperature hysteresis on the number of variants of the γ′-phase particles and on the level of external applied stresses is established.

Electro-thermomechanical characterization of Ti-Ni shape memory alloy thin wires

The use of shape memory alloys (SMA) as smart structures and other modern applications require a previous evaluation of its performance under load as well as a training procedure. In general, these requirements lead to the design and assembly of a specific test bench. In this work, an experimental set-up was specially designed to perform the electro-thermomechanical characterization of SMA wires. This apparatus was used to determine the strain-temperature (epsilon - T) and electrical resistance-temperature (R - T) hysteretic characteristics curves of a Ti-Ni shape memory wire (90 mm in length and 150 µm in diameter) under mechanical load. The SMA wire is loaded by means of constant weights and a controlled system for injection of electrical power allows performing the heating-cooling cycles. The obtained hysteretic epsilon - T and R - T characteristics curves for some levels of applied loads are used to determine important shape memory parameters, like martensitic transformation temperatures, temperature hysteresis, temperature slopes and shape memory effect under load. These parameters were in accord with the ones found in literature for the studied SMA wires.

Phase transitions and metastable states in TlGaSe2

The results of measurements of the dielectric constant of TlGaSe2 in temperature range of successive phase transitions are presented. An anomaly in the temperature dependence of the real part of dielectric constant in TlGaSe2 has been observed at about 242 K in addition to anomalies at 115, 108, and also near 65 K as reported in previous publications. The presence of temperature hysteresis effects in temperature interval between 115 and 242 K allowed making a conclusion about possible existence of an incommensurate phase in the mentioned temperature range. A model of succession of the structural phase transitions in TlGaSe2 has been suggested.

Temperature-Hysteresis Effects in CO Oxidation on Cement Catalysts with Various CuO Content

The temperature dependence of the degree of CO oxidation with atmospheric oxygen on coppercement catalysts was studied.

Large hysteresis effect in surface ionization of Cs due to bulk diffusion

The flux from a Cs Rydberg source, with a carbon covered Ir foil as the emitter of Cs∗, is investigated using surface ionization detection. The surface ionization detector has a Re ribbon as the detecting part. The temperature hysteresis is investigated, and a novel high temperature hysteresis effect is observed. The hysteresis at low temperature is not well described by the standard theory. Both effects are explained if diffusion of Cs into the Re surface is taken into account. With the detector at short distance from the source, the hysteresis is large and the threshold temperatures are low, which is at variance with the standard theory. This behaviour is due to the very rapid in-diffusion of Rydberg states, as is demonstrated by using the source at comparable densities without the Ir foil. The desorption energy for Cs from polycrystalline Re is reported to be around 3.3 eV.

Magnetism of a graphite bi-intercalation compound with two types of ferromagnetic layers: double hysteretic transition in CrCl3–NiCl2–C

An atomic-scale multilayer with two types of ferromagnetic layers is achieved by graphite intercalation. It is a bi-intercalation compound with stacking sequence CrCl3NiCl2NiCl2/… where/represents a graphite layer. The two types of chloride layers are much as they occur in the pristine chlorides and have the same lattice parameters and intralayer intertransition–metal ferromagnetic exchange interactions. The transition temperatures for singly intercalated CrCl3 and NiCl2 graphite compounds are, respectively, 11.3, and 20.2 K. The bi-intercalation compound shows a "double transition" with Tc1 and Tc2 being equal to the relevant intercalate-specific temperatures. It is proposed that, as the temperature is lowered, the NiCl2 layers order first at Tc2 into a 3-D antiferromagnetic stacking of ferromagnetic planes, followed by onset of intra-CrCl3-layer ferromagnetic order at Tc1. Below Tc1 the two types of ferromagnetic planes probably assume a 3-D antiferromagnetic stacking that involve both types of layers, requiring that the NiCl2 stacking be different than at Tc1 < T < Tc2. The main interlayer interactions are believed to be dipole–dipole forces and these are seen to give large low-field temperature hysteresis effects. This is in contrast to many layered materials with antiferromagnetic in-plane interactions in which: (i) dipole–dipole forces do not play a significant role, (ii) 3-D order is not intercalate specific but occurs at temperatures that are much lower than the in-plane interaction strengths and that are highly dependent on the interlayer interaction strengths, and (iii) hysteresis effects are not observed.

Specific heat of the high-T c superconductors (Bi 1.66 Pb 0.34 )Ca 2 Sr 2 Cu 3 O 10

The specific heat (C) was measured for H=0 and 7T in the ranges 0.4 to 20K and 65 t0 125K. The coefficient of the low-temperature linear term in C was 0±0.5 mJ/K 2 ·mole. On initial cooling, an anomaly in C was observed at T c , but there were dramatic temperature hysteresis effects.

A new biintercalation compound, FeCl3–NiCl2–graphite, studied by 57Fe Mössbauer effect spectroscopy and superconducting quantum interference device magnetization measurements: an ideally decoupled bimagnetic system

A novel situation in which long-range magnetic order coexists with (super)paramagnetism occurs in a new graphite biintercalation compound: FeCl3–NiCl2–graphite. Several compounds have been prepared by sequential intercalation of the two intercalates and have been characterized by powder diffractometry, X-ray precession photographs, high-precision X-ray single-crystal measurements, chemical analysis, and high-temperature susceptibility measurements. All measurements are consistent with the stacking sequence –C–NiCl2–C–FeCl3–C– and corroborate the crystallographic integrity of separate NiCl2 and FeCl3 sublattices. Since the in-plane magnetic interactions of the NiCl2 and FeCl3 layers are, respectively, ferromagnetic and antiferromagnetic, the two types of chloride layers have been probed independently by combining low-temperature superconducting quantum interference device magnetometry and 57Fe Mössbauer-effect spectroscopy. The NiCl2 layers order magnetically at 20.5 K, whereas the FeCl3 layers do not order down to 4.2 K. The drop of 1.5 K in the NiCl2-related ordering temperature, induced by the intercalation of FeCl3 into stage-2 NiCl2–graphite, is attributed to the increased NiCl2–layer separation, suggesting that the transition in NiCl2–graphite is not two-dimensional. Some of the FeCl3–NiCl2–graphite compounds show NiCl2-related transitions at temperatures lower than 20.5 K, which is explained in terms of lower in-plane NiCl2 concentrations. Partial oxidation and hydrolysis of in-gallery FeCl3 has been demonstrated and is found to depend strongly on the mean host-graphite-flake size. A charge transfer of 0.2 electrons per iron atom in the FeCl3 layers is inferred from the Mössbauer spectra collected at 4.2 K, which is the same as in singly intercalated FeCl3–graphite compounds of all known stages. Time and temperature-hysteresis effects in the magnetization have been measured and show distinct "re-entrant spin-glass" behaviour. Relevant aspects of the magnetism and structure of the related singly intercalated materials, the pristine chlorides, and the new biintercalation compounds are compared in detail. The overall features are consistent with a recent model based on interacting island supermoments.