How Does Temperature Affect the Charge Transfer Process in Flow Electrode Capacitive Deionization?

In this study, we investigate how temperature variations, a key environmental factor, affect the charge transfer process in FCDI systems across seasonal variation and geographical distributions, which is crucial for optimizing FCDI performance but has not received adequate attention. Therefore, thermal-assisted FCDI systems were proposed by controlling the temperatures of the flow electrode and saline water to simulate the environmental conditions, and the temperature effects on the charge transport and desalting ability of FCDI were investigated. First, the isothermal mode was performed, where the flow electrode and saline water were controlled at the same temperatures (0-50 °C) to simulate the natural atmospheric temperature fluctuations and industrial circulating cooling water system. Experimental results showed a strong positive correlation between temperature and electrosorption dynamics. Elevated temperatures significantly improved ion electromigration and diffusion, thereby enhancing the electrosorption capacity of the FCDI device. On this basis, the nonisothermal mode was designed via maintaining the temperature of the flow electrode at 50 °C to improve the desalination performance of FCDI for saline water at different temperatures (0-50 °C). Finally, the East China seawater and industrial circulating cooling water were both desalted successfully to confirm the feasibility of the temperature field in the practical application of FCDI.

Simultaneous Reconstruction of Gas Concentration and Temperature Using Acoustic Tomography.

Acoustic tomography utilizes sensor arrays to collect sound wave signals, enabling non-contact measurement of physical parameters within an area of interest. Compared to optical technologies, acoustic tomography offers the advantages of low cost, low maintenance, and easy installation. Current research in acoustic tomography mainly focuses on reconstruction algorithms for temperature fields, while monitoring the composition and concentration of gases is significant for ensuring safety and improving efficiency, such as in scenarios like boiler furnaces and aviation engine nozzles. In excitable gases, the speed of sound exhibits an S-shaped curve that changes with frequency, a characteristic that could be potentially useful for acoustic tomography. Therefore, this study primarily discusses the quantitative calculation of gas concentration and temperature based on the dispersion of the speed of sound. By employing graphic processing and pattern matching methods, a coupled relationship of the dispersion of the speed of sound with gas concentration and temperature is established. The projection intersection method is used to calculate the concentration and temperature of binary and ternary gas mixtures. Combined with the inversion method, a joint reconstruction method for gas concentration fields and temperature fields based on the dispersion of the speed of sound is developed. The feasibility of the proposed simultaneous reconstruction method for temperature and concentration fields is validated using numerical simulations. Additionally, an acoustic tomography experimental system was set up to conduct reconstruction experiments for binary gas concentration fields and temperature fields, confirming the effectiveness of the proposed method.

Simulating Error Due to Acquired Thermoelectric Inhomogeneity.

The best method to prevent error due to inhomogeneity is to use a new thermocouple design-the thermocouple with controlled temperature field (TCTF). It uses the auxiliary furnace to control the temperature field along its legs. Such a design allows setting and maintaining the temperature field along the thermocouple (TC) legs for the sensor. Error due to inhomogeneity of TCs cannot appear in a stable temperature field. However, the auxiliary furnace and TCs, to control the temperature field, have errors, so the temperature field along the main TC is maintained with some error. This leads to residual error due to acquired inhomogeneity of the TCTF. We constructed the mathematical models to fit the experimental data of error due to drift for the type K TC. The authors used the constructed models to study error due to inhomogeneity of the TCTF and the conventional type K TC under considerable changes in temperature field. The main results of modelling are as follows: (i) if the changes in temperature field exceed 7 °C, error due to inhomogeneity of the TCTF is lesser than that of the conventional TC; (ii) the maximum error due to inhomogeneity of the conventional type K TC is 10.75 °C; (iii) the maximum error due to inhomogeneity of the TCTF is below 0.2 °C.

Study on Temperature Response of Rubberized Concrete Pavement Based on Fiber Bragg Grating Testing Technology.

The temperature response of pavement is not only crucial for assessing the internal stresses within pavement structures but is also an essential parameter in pavement design. Investigating the temperature response of rubberized concrete pavements (RCP) can support the construction of large-scale rubber concrete pavements. This study constructed a pavement monitoring system based on fiber Bragg grating technology to investigate the temperature distribution, temperature strain, temperature effects, and temperature stress of RCP. The results show that the daily temperature-time history curves of concrete pavement exhibit a significant asymmetry, with the heating phase accounting for only one-third of the curve. The temperature at the middle of RCP is 1.8 °C higher than that of ordinary concrete pavement (OCP). The temperature distribution along the thickness of the pavement follows a "spindle-shaped" pattern, with higher temperatures in the center and lower temperatures at the ends. Additionally, the addition of rubber aggregates increases the temperature strain in the pavements, makes the temperature-strain hysteresis effect more pronounced, and increases the curvature of the pavement slab. However, the daily stress range at the bottom of RCP is approximately 0.7 times that of OCP.

The Simulation Analysis and Experimental Study on the Temperature Field of Four Row Rolling Bearings of Rolling Mill under Non-Uniform Load Conditions.

As a key component of the rolling mill, the four-row cylindrical roller bearing (FCRB) operates under complex working conditions of high speed, high temperature, and heavy load. Due to the lack of an effective temperature test scheme for rolling mill bearings, a too high temperature can easily lead to bearing failure or damage under unsteady conditions. To reveal the internal temperature distribution law of four-row roller bearings of rolling mills and solve the common problem of difficult temperature monitoring of rolling mill bearings, in this paper, a four-row cylindrical roller bearing of 1140 mm cold rolling six-high mill is taken as the research object, and the temperature field calculation model for four-row cylindrical roller bearings is established. Firstly, the mechanical analysis model of FCRB is established on the basis of single row bearing by slice method. Secondly, the mechanical calculation model of FCRB is established by the Newton-Raphson method (NRM) and the finite element method (FEM). Thirdly, based on the mechanical calculation model, the finite element method is used to establish the temperature field model of FCRB under uniform load distribution and non-uniform load distribution. Finally, the temperature test experiment is carried out with the FCRB in the rolling mill fault diagnosis test bench. The results show that the error between the FCRB temperature calculation model and the experimental results is less than 10%. It can be seen that the uneven temperature distribution of FCRB is mainly caused by the uneven load distribution. The temperature distribution along the axial direction of the bearing is related to the load distribution of each column, while the circumferential temperature distribution is related to the azimuth angle.

Safety Evaluation for Fabricated Small Box Girder Bridges Based on Fuzzy Analytic Hierarchy Process and Monitoring Data.

During the operation of fabricated small box girder bridges, which face safety issues such as structural degradation and failure, there is an urgent need to propose a safety evaluation method to cope with the possible risks. This article quantitatively evaluates the safety state of a fabricated small box girder bridge in Wuhan City based on Fuzzy Analytic Hierarchy Process (FAHP) and structural health monitoring (SHM) data. Firstly, the FAHP model is established, and stress, deformation, and temperature are selected as evaluation factors. The safety thresholds of stress and deformation are determined by combining the industry specifications and the historical statistical patterns of the massive SHM data. The temperature field of the bridge is simulated and analyzed by combining ANSYS, HYPERMESH, and TAITHREM, and the most unfavorable temperature gradient is determined as a threshold for the safety evaluation. Finally, the scores of indexes of the bridge are determined based on the measured SHM data, which in turn provides a quantitative description of the safety state. The results show that the thresholds determined by the joint industry specifications and the massive SHM data are reasonable; the temperature field simulation model established in this article is consistent with the measured results, and can accurately determine the temperature gradient of the bridge. The safety evaluation result from the FAHP model is the same as the field test results, which verifies the effectiveness and applicability of the proposed method to actual bridge projects.

Phase transitions and the birth of early universe particle physics.

This paper provides a conceptual history of the development of early universe particle physics in the 1970s, focusing on the development of more sophisticated tools for constructing gauge-theories at finite-temperature. I start with a focus on early investigations into spontaneous symmetry restoration, and continue through the development of functional methods up to equilibrium finite-temperature field theory. I argue that the early universe provides an ideal setting for integrated modelling of thermal, gravitational, and particle physics effects due to its relative simplicity. I further argue that the development of finite-temperature field theory played an important secondary role in the rise of the effective field theory worldview, and investigate the status of the analogies between phase transitions in particle physics and condensed matter physics. I find that the division into "formal" versus "physical" analogies is too coarse-grained to understand the important physical developments at play.

Understanding of Co-boiling between Organic Contaminants and Water during Thermal Remediation: Effects of Nonequilibrium Heat and Mass Transport.

In situ thermal desorption (ISTD) provides an efficient solution to remediation of soil and groundwater contaminated with nonaqueous phase liquids (NAPLs). Establishing a relationship between the subsurface temperature rise and NAPL removal is significant to reduce energy consumption of ISTD. However, the co-boiling phenomenon between NAPL and water poses a great challenge in developing this relationship due to the nonequilibrium heat and mass transport effects. We performed a systematic experimental investigation into the local temperature rise patterns at different distances from a NAPL pool and under different degrees of superheat by selecting four representative NAPLs (i.e., trichloroethylene, tetrachlorethylene, n-hexane, and n-octane) according to their density and boiling point relative to water. The patterns of temperature rise indicated that the underground temperature field can be divided into three zones: the zone of local thermal equilibrium, the nonequilibrium zone affected by co-boiling, and the zone unaffected by co-boiling. We developed a pattern-recognition-based approach, which considers the effects of local heat and mass transport to establish a qualitative correlation between the temperature rise and NAPL removal. Our results give deeper insights into the understanding of subsurface temperatures in ISTD practice, which can serve as the guideline for more accurate and sustainable remediation.

Preliminary Test for 3D Surface Strain Measurement in the Tower and Foundation of Offshore Wind Turbines Using DOFS.

Subjected to the relentless impacts of typhoons and rough seas, offshore wind turbines' structures, particularly the tower, foundation, and blade, are at constant risk of damage. Full-field strain monitoring helps to discover potential structural defects, thereby reducing disasters caused by overall structural failure. This study introduces a novel method for assessing strain and temperature fields on these kinds of 3D surfaces of cylindrical structures. The method harnesses the capabilities of a high spatial resolution (0.65 mm) Optical Frequency Domain Reflectometer (OFDR)-based Distributed Optical Fiber Sensor (DOFS) in conjunction with a unique helical wiring layout. The core process begins with mapping the fiber optic path onto a plane corresponding to the unfolded cylinder. Fiber optic signals are then differentiated on this plane, deriving a two-dimensional strain distribution. The plane strain field is subsequently projected onto the 3D side of the cylinder. An experiment was carried out in which a 3.5 m long optical fiber was helically wound with a 10 mm pitch on the surface of a cantilever beam of a cylinder shell with a diameter of 36 mm and a length of 300 mm. The experiment collected about 5400 measurement points on the cylindrical surface of 340 cm2, approximately 15.9 measurement points per square centimeter. The reconstructed results successfully reveal the strain field of the pipe cantilever beam under bending and torsional loads, as well as the palm-shaped temperature field. This experimental validation of the method's efficacy lays the theoretical groundwork for its application to real wind turbines.

Investigation of the Temperature Actions of Bridge Cables Based on Long-Term Measurement and the Gradient Boosted Regression Trees Method.

Cable-stayed bridges have been commonly used on high-speed railways. The design, construction, and maintenance of cable-stayed bridges necessitate an accurate assessment of the cable temperature field. However, the temperature fields of cables have not been well established. Therefore, this research aims to investigate the distribution of the temperature field, the time variability of temperatures, and the representative value of temperature actions in stayed cables. A cable segment experiment, spanning over one year, is conducted near the bridge site. Based on the monitoring temperatures and meteorological data, the distribution of the temperature field is studied, and the time variability of cable temperatures is investigated. The findings show that the temperature distribution is generally uniform along the cross-section without a significant temperature gradient, while the amplitudes of the annual cycle variation and daily cycle variation in temperatures are significant. To accurately determine the temperature deformation of a cable, it is necessary to consider both the daily temperature fluctuations and the annual cycle of uniform temperatures. Then, using the gradient boosted regression trees method, the relationship between the cable temperature and multiple environmental variables is explored, and representative cable uniform temperatures for design are obtained by the extreme value analysis. The presented data and results provide a good basis for the operation and maintenance of in-service long-span cable-stayed bridges.

Optical and thermal fields induced in the bone marrow by external laser irradiation.

In regenerative medicine, the problem of growing mesenchymal stem cells from the bone marrow often arises. In such cases is important that the number of initial cells was large enough and their proliferative activity was high. We believe that this problem can be solved by short-term heating of local areas of the bone marrow in vivo with laser radiation. In this regard, it is of interest to study the optical and temperature fields induced inside the tubular bone under external laser irradiation. In this work, we obtained experimental data on the spatial distribution of temperature in the bone marrow of the rat femur in vitro under external exposure to laser radiation with wavelengths of 970 and 1940 nm. Radiation delivery was carried out using an optical fiber which tip contacted the surface of the femur bone. A thin thermocouple was used to measure the temperature in a local area of the bone marrow. By moving the optical fiber tip discretely along the longitudinal axis of the bone, and the thermocouple in the perpendicular direction, the spatial temperature distributions in dynamics were measured. Similarly, the spatial distributions of the laser radiation intensity were measured by replacing thermocouple with optical fiber probe. A thermal camera was used to control the temperature of the bone surface near the tip of the fiber. It was shown that the marrow could be heated from the outside by about 5-10 °C during 10 s without significant overheating of the bone tissue. The data obtained make it possible to estimate the volume of the bone marrow heated by the laser to a predetermined temperature and to make a reasonable choice of laser exposure modes to stimulate the proliferative activity of bone marrow mesenchymal stem cells in vivo.

Thermal Characterization of a Gas Foil Bearing-A Novel Method of Experimental Identification of the Temperature Field Based on Integrated Thermocouples Measurements.

Maintenance of adequate thermal properties is critical for correct operation of a gas foil bearing. In this work, the authors present the results of the experimentally conducted thermal characterization of a prototype installation of the bearing. A novel method of temperature identification, based on integrated thermocouples readings, has been employed to determine the thermal properties of the specialized sensing top foil mounted in the tested bearing. Two measurement campaigns have been subsequently completed, applying freely-suspended and two-node support configurations, to gather complementary knowledge regarding the bearing's operation. Apart from the rotational speed and temperature field measurements, the authors have also studied the friction torque and the shaft's journal trajectories based on its radial displacements. The temporal courses for the above-mentioned quantities have enabled inference on the effects present during run-up, run-out and stable state operation at a constant speed. As confirmed, the applied distribution of the integrated sensors allows for temperature readings on the entire outer surface of the foil, and therefore, provides useful data for the bearing characterization. The work is concluded with presentation of the recommended directions regarding future improvements of the proposed measurement technique and more comprehensive study of the bearing's characteristics.

Simulation and Experiment Analysis of Temperature Field of Magnetic Suspension Support Based on FBG.

Temperature rise is an important factor limiting the development of magnetic suspension support technology. Traditional temperature sensors such as thermocouples are complicated and vulnerable to electromagnetic interference due to their point contact temperature measurement methods. In this paper, the equivalent model of magnetic suspension support is established, and the temperature field is simulated and analyzed by magnetic thermal coupling calculation in ANSYS software. Then, a quasi-distributed temperature measurement system is designed, and the FBG temperature sensor is introduced to measure the temperature of the magnetic suspension support system by "one-line and multi-point". By comparing the analysis experiments and simulations, the equivalent accuracy of the simulation model and the FBG temperature sensor can accurately measure the temperature of the magnetic suspension support.

Temperature Field Reconstruction Method for Acoustic Tomography Based on Multi-Dictionary Learning.

A reconstruction algorithm is proposed, based on multi-dictionary learning (MDL), to improve the reconstruction quality of acoustic tomography for complex temperature fields. Its aim is to improve the under-determination of the inverse problem by the sparse representation of the sound slowness signal (i.e., reciprocal of sound velocity). In the MDL algorithm, the K-SVD dictionary learning algorithm is used to construct corresponding sparse dictionaries for sound slowness signals of different types of temperature fields; the KNN peak-type classifier is employed for the joint use of multiple dictionaries; the orthogonal matching pursuit (OMP) algorithm is used to obtain the sparse representation of sound slowness signal in the sparse domain; then, the temperature distribution is obtained by using the relationship between sound slowness and temperature. Simulation and actual temperature distribution reconstruction experiments show that the MDL algorithm has smaller reconstruction errors and provides more accurate information about the temperature field, compared with the compressed sensing and improved orthogonal matching pursuit (CS-IMOMP) algorithm, which is an algorithm based on compressed sensing and improved orthogonal matching pursuit (in the CS-IMOMP, DFT dictionary is used), the least square algorithm (LSA) and the simultaneous iterative reconstruction technique (SIRT).

Amalgamation of Geometry Structure, Meteorological and Thermophysical Parameters for Intelligent Prediction of Temperature Fields in 3D Scenes.

Temperature field calculation is an important step in infrared image simulation. However, the existing solutions, such as heat conduction modelling and pre-generated lookup tables based on temperature calculation tools, are difficult to meet the requirements of high-performance simulation of infrared images based on three-dimensional scenes under multi-environmental conditions in terms of accuracy, timeliness, and flexibility. In recent years, machine learning-based temperature field prediction methods have been proposed, but these methods only consider the influence of meteorological parameters on the temperature value, while not considering the geometric structure and the thermophysical parameters of the object, which results in the low accuracy. In this paper, a multivariate temperature field prediction network based on heterogeneous data (MTPHNet) is proposed. The network fuses geometry structure, meteorological, and thermophysical parameters to predict temperature. First, a Point Cloud Feature Extraction Module and Environmental Data Mapping Module are used to extract geometric information, thermophysical, and meteorological features. The extracted features are fused by the Data Fusion Module for temperature field prediction. Experiment results show that MTPHNet significantly improves the prediction accuracy of the temperature field. Compared with the v-Support Vector Regression and the combined back-propagation neural network, the mean absolute error and root mean square error of MTPHNet are reduced by at least 23.4% and 27.7%, respectively, while the R-square is increased by at least 5.85%. MTPHNet also achieves good results in multi-target and complex target temperature field prediction tasks. These results validate the effectiveness of the proposed method.

[Material design and temperature field simulation analysis of tumor radiofrequency ablation needle].

To solve the problems of small one-time ablation range and easy charring of the tissue around the electrode associated with the tumor radiofrequency ablation needle, based on the multiphysical field coupling analysis software COMSOL, the effects of needle material, the number of sub needles and the bending angle of sub needles on the ablation effect of radiofrequency ablation electrode needle were studied. The results show that compared with titanium alloy and stainless steel, nickel titanium alloy has better radiofrequency energy transmission efficiency and it is the best material for electrode needle. The number of sub needles has a great influence on the average necrosis depth and the maximum necrosis diameter. Under the same conditions, the more the number of sub needles, the larger the volume of coagulation necrosis area. The bending angle of the needle has a great effect on the maximum diameter of the coagulated necrotic area, but has little effect on the average necrotic depth. Under the same other conditions, the coagulation necrosis area formed by ablation increased with the increase of the bending angle of the sub needle. For the three needles with bending angles of 60 °, 90 ° and 120 ° analyzed in this paper, the one with bending angle of 120 ° can obtain the largest coagulation necrosis area. In general, the design of nickel titanium alloy with 120 ° bending 8-pin is the optimal. The average depth of radiofrequency ablation necrosis area is 32.40 mm, and the maximum necrosis diameter is 52.65 mm. The above optimized design parameters can provide guidance for the structure and material design of tumor radiofrequency ablation needle.

[Finite element modeling of postmortem hyperthermia in the absence of internal heat sources]. / Konechno-elementnoe modelirovanie posmertnoi gipertermii pri otsutstvii vnutrennikh istochnikov teplovydeleniya.

The objective of the study is to develop a finite element model (FEM) of postmortem hyperthermia in the absence of internal and external heat sources and to clarify the conditions necessary for the occurrence of this phenomenon. ELCUT 6.5 software was used. We have developed a two-dimensional FEM of the postmortem temperature field of the head under convective heat exchange with the ambient air, taking into account the intensity of convective heat transfer and thermophysical parameters of anatomical layers of this body area. The possibility of postmortem heating of the surface and subsurface tissues of the corpse in the absence of internal and external heat sources was demonstrated. It was found that the occurrence of postmortem hyperthermia requires cooling the cadaver under low convective heat transfer with a small initial temperature gradient between the body surface and the ambient environment. It is recommended to take into account the possibility of postmortem hyperthermia and the conditions necessary for it in forensic medical practice when determining the time of death (TOD).

Infrared thermal imaging controls freezing and warming in skin cryoablation.

The purpose of this study was to assess the possibilities of intraoperative control of the current parameters of frozen biological tissues in the cryoablation area, including the instant location of primary necrosis isotherm, based on the dynamics of thermal fields on skin surface. Cryoablation of skin was performed in 30 rats with exposure durations of 0.5, 1 and 2 min. The contact cryoprobe actively cooled with liquid nitrogen was used. The dynamics of animal's skin thermal field during freeze/thaw cycle was quantitatively controlled by the original infrared camera with an extended range of measurable temperatures. The obtained by us ratio of the maximal diameters of primary necrosis and ice spots was 0.64 ± 0.03 for cryoexposure durations of 0.5 and 1 min. During thawing, a quasi-stable stage was observed both in the dynamics of ice spot diameters and their temperature distribution. The effect is presumably associated with structural rearrangements of ice in the frozen tissue volume. The results indicate that thermal imaging can be effectively used for quantitative control of freezing and warming of biological tissues in vivo, including current control of the position of necrotic and cryoscopic isotherms, distortion of their thermal symmetry, thermal response of other skin areas, etc.

All-Weather Thermal Simulation Methods for Concrete Maglev Bridge Based on Structural and Meteorological Monitoring Data.

Thermal energy exchange induces non-uniform temperature distribution on the concrete bridge structures, leading to variation of static and dynamic properties of structural systems. The finite element method can facilitate thermal simulation and predict the structural temperature distribution based on heat flow theories. Previous studies mainly focused on the daytime with sunny weather, and the effects of solar shadow distribution were not fully considered or even ignored. In this paper, a systematic all-weather thermal simulation method was proposed to investigate the temperature distributions of concrete maglev bridges. The solar shadow distribution on the bridge surface could be accurately simulated to determine the solar radiation-imposed range. A meteorological station and some thermocouples were installed on a real concrete maglev bridge to obtain the real-time structural temperatures and environmental conditions. Its temperature distribution is also simulated using the proposed method within the 27 monitoring days in Summer. Results show that the simulated structural temperature matches well with the measured results under various weather conditions, except that of the east structural surface. Moreover, the simulation method acquired a higher accuracy under overcast or rainy weather due to weaker solar radiation effects. Both the numerical results and experimental records illustrated that direct solar radiation dominates the thermal energy exchange under sunny or cloudy conditions. The proposed methodology for temperature field simulation is oriented by all-weather prediction of structural temperature, which is reliable for concrete bridge structures with the help of accurate measurement of real-time solar radiation.

Inquiry into the Temperature Changes of Rock Massif Used in Energy Production in Relation to Season.

This research was undertaken to perform and evaluate the temperature measurement in the ground utilized as an energy source with the goal to determine whether significant temperature variations occur in the subsurface during the heating season. The research infrastructure situated on our University campus was used to assess any variations. The observations were made at the so called "Small Research Polygon" that consists of 8 monitoring boreholes (Borehole Heat Exchangers) situated around a borehole used as an energy source. During the heating season, a series of monthly measurements are made in the monitoring boreholes using a distributed temperature system (DTS). Raman back-scattered light is analysed using Optical Frequency Time Domain Reflectometry (OTDR). Our results indicate that no noticeable changes in temperature occur during the heating season. We have observed an influence of long-term variations of the atmospheric conditions up to the depth of a conventional BHE (≈100 m). The resulting uncertainty in related design input parameters (ground thermal conductivity) was evaluated by using a heat production simulation. Production data during one heating season at our research facilities were evaluated against the design of the system. It is possible to construct smaller geothermal installations with appropriate BHE design that will have a minimal impact on the temperature of the surrounding rock mass and the system performance.