Estimation Of Temperature Rise Research Articles

Global tropical and extra-tropical tropospheric ozone trends and radiative forcing deduced from satellite and ozonesonde measurements for the period 2005-2020.

Tropospheric ozone (TPO) is considered as a "near-term climate forcer", whose impact on climate depends on its radiative forcing (RF), which is a change in the Earth's energy flux. Here, we use the ground-based and satellite measurements during the period 2005-2020 to deduce the trends of TPO, which is significantly positive in the tropical and extra-tropical northern hemisphere (0.2-0.5 DU/yr) and southern extra-tropics (0.1-0.2 DU/yr). Furthermore, the trends derived using a multiple linear regression model (MLR) also confirm these estimates, which are about 0.05-0.1 /DU/yr and the regions with higher trends (> 0.06 /DU/yr) are statistically significant. We also use a standalone Rapid Radiative Transfer Model coupled with a convective model (Radiative-Convective Model; RCM) to assess the climate forcing of ozone using its vertical profiles from the Modern Era Retrospective Reanalysis (MERRA)-2 reanalysis. The estimated temperature rise due to the radiative forcing of ozone in the tropical troposphere (1000-100 hPa) is about 0.2-0.3 °C for the study period. In brief, there is a positive trend in the tropospheric ozone in the tropics and extra-tropics, which is a great concern for regional warming, public health and ecosystem dynamics.

Joining of Copper and Aluminum Alloy A6061 Plates at Edges by High-Speed Sliding with Compression

By using the joined or welded materials of dissimilar metals, the characteristics and performance of products and parts can be improved. The combination of copper and aluminum is difficult to weld. In this study, the impact joining of copper C1100 and aluminum alloy A6061-T6 plates at the edges was investigated to explore the appropriate joining conditions. The plates are joined with newly created surfaces generated by the high-speed compressive deformation with sliding motion. The shape near the interface was a tapered trapezoid with a flat top. The joining length in the plate thickness direction was shorter than the plate thickness, and notches were observed near both plate surfaces. The length became slightly longer by setting a larger top width of the C1100 plate than that of A6061-T6. The joint efficiency increased by approximately 10%. Applying the emery paper finish to the surface of the plate eliminated the non-joining result in multiple experiments. The finishing direction is effective only in the longitudinal direction of the plate. In the tensile test on the dumbbell-type specimen with reduced thickness to eliminate notches, most results showed a fracture at the C1100 portion. The estimated temperature rise of the C1100 is more than about 250 K during the impact deformation. Hence, the strength of the A6061-T6 becomes lower than that of C1100 during the process, and the softened layer of aluminum comes out under pressure, resulting in good joining performance.

Influence of strain rate on the work hardening, strain induced martensite formation, strain partitioning, and variant selection in a medium-Mn steel

In this study, we investigated the effect of strain rate on the work hardening, strain-induced martensite transformation, strain partitioning, and crystallographic variant selection in a medium-Mn steel. Uniaxial compression tests were performed under quasi-static and dynamic loading conditions at the strain rates of 10−3, 1 and 103s−1. Besides, to determine the contribution of temperature rise due to adiabatic heating at a higher strain rate, compression tests were carried out at 409 K (estimated temperature rise) under quasi-static conditions. The work hardening rate was higher at high strain rates and it rapidly decreased at all strain rates up to a true plastic strain of ∼0.05. Beyond the true plastic strain of ∼0.05, the work hardening rate increased at a low strain rate up to a true plastic strain of ∼0.15 while at a high strain rate, it remained relatively constant and gradually decreased beyond a true plastic strain of ∼0.15. From the analysis of microstructures obtained from electron backscatter diffraction, it was observed that the strain-induced transformation of retained austenite to α′-martensite is significantly impeded at higher strain rates and in the sample tested at 409 K at low strain rates. The higher stability of retained austenite is attributed to the adiabatic heating which decreases the chemical driving force for retained austenite to martensite phase transformation and increases the stacking fault energy. Analysis of the misorientation axis and angle evolution revealed that while the Kurdjumov–Sachs relationship was followed under quasi-static conditions, it deviated at higher strain rates. Analysis of crystallographic variants related to strain-induced martensitic transformation at a true plastic strain of ∼0.15 revealed that the samples deformed at a lower strain rate did not show any noticeable variant selection. However, in samples deformed at a higher strain rate, a significant variant selection was observed. It is reasoned that the martensitic transformation nucleates initially on favorably oriented habit planes of retained austenite grains at all strain rates and other variants get activated with an increase in strain. As the transformation is impeded beyond a critical strain at a higher strain rate, the variants activated at lower strains remains predominant.

Symmetrical recovery time course between impedance and intramyocardial temperature after bipolar radiofrequency ablation; Role of impedance monitoring to estimate temperature rise

IntroductionDuring radiofrequency (RF) ablation, impedance monitoring has been used to avoid steam-pop caused by excessive intramyocardial temperature (IMT) rise. However, it is uncertain why the impedance decline is related to steam-pop and whether the impedance decline is correlated to IMT. MethodsTwenty-one bipolar ablations (40 W, 30-g contact, 120 s) were attempted for seven perfused porcine myocardium. Immediately after ablation, a temperature electrode was inserted into the mid-myocardial portion, and the recovery process of impedance and its correlation to IMT were assessed. ResultsTransmural lesion was created in all 21 applications but steam-pop occurred in 5/21 applications with large impedance decline. In the 16 applications without steam-pop, impedance and IMT soon after ablation were 97.2 ± 4.0 Ω and 66.1 ± 4.8 °C, respectively. Reasonably high linear correlation was demonstrated between the maximum IMT after ablation and impedance differences before and after ablation. Recovery processes of the decreased impedance and the elevated IMT fit well to each equation of the single exponential decay function and showed symmetric shapes with no statistical difference of time constant (100.1 ± 34.5 s in impedance vs. 108.7 ± 27.3 s in IMT) and half-time of recovery (144.5 ± 49.8 s in impedance vs. 156.9 ± 39.4 s in IMT). Recovered impedance after ablation (104.8 ± 3.9 Ω) was 5.1 ± 2.0 Ω smaller than that before ablation (109.9 ± 2.7 Ω), suggesting several factors other than IMT rise participate in impedance decline in RF ablation. ConclusionsRecovery of impedance and IMT after ablation well correlated, which supports the usefulness of impedance monitoring for safe RF ablation.

Predicting the occurrence and decline of Astragalus verus Olivier under climate change scenarios in Central Iran

Modeling species distribution and predicting the effects of climate change on plant species decline are necessary in restoration programs. This study aimed to predict the occurrence and decline of Astragalus verus under climate change in Central Iran with an area of about 123,167 km2. We recorded 12 and 71 sites for the dead and alive species using the stratified sampling method, respectively. The general circulation model of CCSM4 was applied at two timeframes of present and 2050 under two climate change scenarios of RCP2.6 and RCP8.5. Four environmental variables of annual mean temperature, the maximum temperature of the warmest month, the precipitation of the coldest quarter, and elevation were selected as the inputs of the nine statistical models. Results indicated that Random Forest model had the best performance in predicting climatic niche and decline of A. verus (AUC and TSS of 0.99) compared to the other models. The suitable habitat and decline for this species are 12.4% and 19.87% of the study area, respectively. With the estimated temperature rise of 3 °C under the CCSM4-RCP2.6 scenario, A. verus habitat will shrink by about 3.4% of the study area and will move toward higher elevations with colder temperatures in the future. Most changes in the suitability of the species will occur in the altitude range of 1800 to 2200 meters because the most temperature and precipitation variations will happen in this elevation stratum. The results can be used to prevent its rapid dieback or even restore vegetation cover in regions with similar conditions.

Real-Time Temperature Rise Estimation during Irreversible Electroporation Treatment through State-Space Modeling

To evaluate the feasibility of real-time temperature monitoring during an electroporation-based therapy procedure, a data-driven state-space model was developed. Agar phantoms mimicking low conductivity (LC) and high conductivity (HC) tissues were tested under the influences of high (HV) and low (LV) applied voltages. Real-time changes in impedance, measured by Fourier Analysis SpecTroscopy (FAST) along with the known tissue conductivity and applied voltages, were used to train the model. A theoretical finite element model was used for external validation of the model, producing model fits of 95.8, 88.4, 90.7, and 93.7% at 4 mm and 93.2, 58.9, 90.0, and 90.1% at 10 mm for the HV-HC, LV-LC, HV-LC, and LV-HC groups, respectively. The proposed model suggests that real-time temperature monitoring may be achieved with good accuracy through the use of real-time impedance monitoring.

Fast Prediction of RF-induced Heating for Sacral Neuromodulation System Exposed to Multi-Channel 2 RF Field at 3T MRI.

This paper presents a fast method to predict the radiofrequency (RF) induced heating for Sacral Neuromodulation System (SNM) under multi-channel 2 (MC-2) RF field of 3 Tesla (T) magnetic resonance imaging (MRI) system by using the artificial neural network (ANN). The raw computational model for the SNM was based on the transfer function approach. The MC-2 parallel transmission RF field at 3T MRI exposure was considered for 2 independent channels, which have an exposure space of -15 dB to 15 dB magnitude difference and -180 degrees to 170 degrees phase difference. A total number of 535,680 study cases that cover all possible shimming conditions and the corresponding temperature rises are collected from raw calculation data. The ANN was used as the surrogate model to predict the temperature rises against the incident electromagnetic field distributions. 40320 cases were used for training while the rest data sets were used for testing. The ANN can estimate the temperature rises for each human model in a small exposure sampling space. The testing performance of the ANN has a correlation coefficient higher than 0.99 and the mean absolute error was less than 0.12°C. It is demonstrated that the ANN can be used as an efficient tool for quick temperature rise estimation under MRI 3T shimming.

The Laboratory Analysis of the Thermal Processes Occurring in Low-Voltage Asynchronous Electric Motors

The exact nature of thermal processes occurring in an electric motor is often unknown. Thus, the estimation of temperature rise using mathematical models and computational experiments is becoming increasingly important. Thermal analysis is the key design aspect, which has become significant in the design process for electric motors. The thermal analysis of electric motors can be helpful in developing effective thermal monitoring methods. This analysis is crucial for a better understanding of the overall performance and failure prevention for these electrical motors. In this paper, laboratory investigations of thermal processes in low-voltage asynchronous motors are described. The analysis of the results leads to the conclusion that the classic single-exponential models do not match the dynamically changing thermal processes in electric motors especially in the case of intermittent motor operation.

Direct Quantification of Heat Generation Due to Inelastic Scattering of Electrons Using a Nanocalorimeter.

Transmission electron microscopy (TEM) is arguably the most important tool for atomic‐scale material characterization. A significant portion of the energy of transmitted electrons is transferred to the material under study through inelastic scattering, causing inadvertent damage via ionization, radiolysis, and heating. In particular, heat generation complicates TEM observations as the local temperature can affect material properties. Here, the heat generation due to electron irradiation is quantified using both top‐down and bottom‐up approaches: direct temperature measurements using nanowatt calorimeters as well as the quantification of energy loss due to inelastic scattering events using electron energy loss spectroscopy. Combining both techniques, a microscopic model is developed for beam‐induced heating and to identify the primary electron‐to‐heat conversion mechanism to be associated with valence electrons. Building on these results, the model provides guidelines to estimate temperature rise for general materials with reasonable accuracy. This study extends the ability to quantify thermal impact on materials down to the atomic scale.

Modeling radio-frequency energy-induced heating due to the presence of transcranial electric stimulation setup at 3T

PurposeThe purpose of the present study was to develop a numerical workflow for simulating temperature increase in a high-resolution human head and torso model positioned in a whole-body magnetic resonance imaging (MRI) radio-frequency (RF) coil in the presence of a transcranial electric stimulation (tES) setup.MethodsA customized human head and torso model was developed from medical image data. Power deposition and temperature rise (ΔT) were evaluated with the model positioned in a whole-body birdcage RF coil in the presence of a tES setup. Multiphysics modeling at 3T (123.2 MHz) on unstructured meshes was based on RF circuit, 3D electromagnetic, and thermal co-simulations. ΔT was obtained for (1) a set of electrical and thermal properties assigned to the scalp region, (2) a set of electrical properties of the gel used to ensure proper electrical contact between the tES electrodes and the scalp, (3) a set of electrical conductivity values of skin tissue, (4) four gel patch shapes, and (5) three electrode shapes.ResultsSignificant dependence of power deposition and ΔT on the skin’s electrical properties and electrode and gel patch geometries was observed. Differences in maximum ΔT (> 100%) and its location were observed when comparing the results from a model using realistic human tissue properties and one with an external container made of acrylic material. The electrical and thermal properties of the phantom container material also significantly (> 250%) impacted the ΔT results.ConclusionSimulation results predicted that the electrode and gel geometries, skin electrical conductivity, and position of the temperature sensors have a significant impact on the estimated temperature rise. Therefore, these factors must be considered for reliable assessment of ΔT in subjects undergoing an MRI examination in the presence of a tES setup.

ROUTINE, EXTREME AND ENGINEERING METEOROLOGY ANALYSIS FOR KARACHI COASTAL AREA

Pakistan’s largest city, Karachi, which is industrial centre and economic hub needs focus in research and development of every field of Engineering, Science and Technology. Urbanization and industrialization is resulting bad weather conditions which prolongs until a climate change. Since, Meteorology serves as interdisciplinary field of study, an analytical study of real and region-specific meteorological data is conducted which focuses on routine, extreme and engineering meteorology of metropolitan city Karachi. Results of study endorse the meteorological parameters relationship and establish the variability of those parameters for Karachi Coastal Area. The rise of temperature, decreasing trend of atmospheric pressure, increment in precipitation and fall in relative humidity depict the effects of urbanization and industrialization. The recorded extreme maximum temperature of 45.50C (on June 11, 1988) and the extreme minimum temperature of 4.5 0C(on January 1, 2007) is observed at Karachi south meteorological station. The estimated temperature rise in 32 years is 0.9 0C, which is crossing the Intergovernmental Panel on Climate Change (IPCC) predicted/estimated limit of 2oC rise per century. The maximum annual precipitation of 487.0mm appearing in 1994 and the minimum annual precipitation of 2.5mm appearing in 1987 is observed at same station which is representative meteorological station for Karachi Coast. Further Engineering meteorological parameters for heating ventilation air condition (HVAC) system design for industrial purpose are deduced as supporting data for coastal area site study for industrial as well as any follow-up engineering work in the specified region.

Temperature Rise in Sliding Solids: Influence of Contact Pressure and Temperature on Thermal Conduction

Accurate estimation of temperature rise for sliding solids is still challenging. Part of the challenge is accounting for the actual thermal behavior of the solids while sliding (i.e., the nonlinear effects taking place because of sliding conditions and their evolutionary path). Conventionally, only temperature-induced influence on transport properties has been considered. However, thermal properties of the solids also depend on contact stress, the rate of strain, and the rate of heat generation. The contact stress within the mechanically affected zone, even considering the hardness of the softest of the sliding pair, can reach several thousand times the value of atmospheric pressure. Under such a condition, thermal conductivity of many materials show a different behavior than that manifested under standard conditions. This work considers such an influence and its effect on the evolution of temperature. The results show that conventional estimates can considerably under-estimate the actual temperature rise. It is also shown that initial loading, may result in the contacting materials behaving as a layered structure, with each layer having a different capacity of thermal load dissipation. Depending on the distribution of that capacity, dissipation of friction heat may be constrained which may accelerate wear.

How to Interpret the Ultrasound Output Display Standard for Diagnostic Ultrasound Devices: Version 3.

How to Interpret the Ultrasound Output Display Standard for Diagnostic Ultrasound Devices: Version 3.

Experimental investigations on dating the last earthquake event using OSL signals of quartz from fault gouges

Obtaining a reliable age of the latest seismic slip event along an active fault is important for seismic hazard assessment. Here, we observe changes in the optically stimulated luminescence (OSL) signal of quartz crystals due to frictional heating in artificial fault gouges (comprising a mixture of quartz grains and Ca-bentonite powder). The fault gouge was deformed using a high-velocity rotary-shear apparatus at room temperature and room humidity. At a seismic slip rate of 1.31 m·s−1, intense slip localization occurred along a very thin layer (~300 μm thick) within the simulated fault zones (1 mm thick). The estimated temperature of the slip-localized layer (SLL) increased by ~475 °C from frictional heating. The quartz OSL signals of the gouges were fully reset, most noticeably for the SLL. In contrast, there was rare slip-localization at subseismic slip rates (0.06–0.001 m·s−1), for which the estimated temperature rise in the SLL was ~120 °C; hence, the quartz OSL signal was not reset under this condition. The results suggest that quartz OSL dating can be used to constrain the age of the latest seismic event in natural quartz-bearing fault zones where a SLL occurs.

Determination of physiotherapy ultrasound beam quality parameters from images derived using thermochromic material

The evaluation of the performance of nine physiotherapy ultrasound transducers used clinically was performed in the hospital environment using an acoustically absorbing thermocromic tile developed at the National Physical Laboratory (UK). The method consists of exposing an acoustic absorber tile, part of which contains a thermochromic pigment, to the ultrasonic beam, thereby forming an image of the intensity profile of the transducer. Images acquired using thermochromic materials were postprocessed in order to estimate effective radiating area (ERA) and beam nonuniformity ratio (BNR) for ultrasound transducers operating within the frequency range from 1.0 to 3.3 MHz, and nominal applied intensities in the range of 1–2W/cm2. Results of our measurements have shown that thermocromic tile can be used for quality control of ultrasound transducers in the hospital environment. Experimental results show that proposed method can be used to distinguish highly non - uniform ultrasound beams with high value of BNR.Influence of exposure duration on obtained ERA and BNR values was also analysed. Our results show that values for ERA increase with insonation time, while BNR values decrease. In order to compare our results with theory we have estimated temperature rise in thermochromic material experimentally and compare it with theoretical prediction.

Computational analysis of the temperature improvement of electric asynchronal motors

In the development of electric machines as a whole, as well as asynchronous motors, in particular, the limit values of temperature are the key factors that affect the efficiency of the overall design. Since the usual load of asynchronous motors often occurs, hence, the estimation of temperature rise with the help of mathematical modeling tools and computational experiments becomes more and more important. In this paper, we develop and test experimentally the model of loss accounting and the description of thermal phenomena in asynchronous motors. The developed model was introduced at FEMLAB, and was used to predict the temperature rise in the fully closed fan cooling of asynchronous motors. Comparison with experimental results obtained according to the standard of 1.5 kW. The motor model shows the effectiveness of the developed model in predicting the temperature increase for a number of operating conditions, in particular for different frequencies and voltages. Finally, the SIMULINK control loop was developed using the thermal model as input.An electric machine is a complex engineering system consisting of different materials of different thermal properties and distribution of heat source. Although we observe successes in many aspects of the design of an electric machine, we generally agree that the development of thermal design methods for electric machines is lagging.One of the most commonly used AC machines applied for industrial purposes is an asynchronous electric air-cooled electric motor (TEFC). These motors are often driven by alternating voltage and variable frequency. As a result, we can achieve variable speed and torque control for specific loads, but the charge for this will be an increase in the operation of the engine temperature. In addition, it is well known that one of the high source temperatures is an increase in voltage on asynchronous motors and insulation systems. Recognizing the importance of the thermal factor in the overall efficiency of motor design, there are different methods have been proposed for thermal control, in particular, related to the temperature of the rotor and stator. Most of these methods are based on some intermediate estimates, such as rotor resistance and identification, but with the application of such methods, there is little to be said about the temperature distribution and the detection of thermally critical parts of the engine under this operating condition.

Kranion, an open-source environment for planning transcranial focused ultrasound surgery: technical note.

Transcranial focused ultrasound (FUS) ablation is an emerging incision-less treatment for neurological disorders. The factors affecting FUS treatment efficiency are not well understood. Kranion is open-source software that allows the user to simulate the planning stages of FUS treatment and to "replay" previous treatments for off-line analysis. This study aimed to investigate the relationship between skull parameters and treatment efficiency and to create a metric to estimate temperature rise during FUS. CT images from 28 patients were analyzed to validate the use of Kranion. For stereotactic targets within each patient, individual transducer element incident angles, skull density ratio, and skull thickness measurements were recorded. A penetration metric (the "beam index") was calculated by combining the energy loss from incident angles and the skull thickness. Kranion accurately estimated the patient's skull and treatment parameters. The authors observed significant changes in incident angles with different targets in the brain. Using the beam index as a predictor of temperature rise in a linear-mixed-effects model, they were able to predict the average temperature rise at the focal point during ablation with < 21% error (55°C ± 3.8°C) in 75% of sonications, and with < 44% (55°C ± 7.9°C) in 97% of sonications. This research suggests that the beam index can improve the prediction of temperature rise during FUS. Additional work is required to study the relationship between temperature rise and lesion shape and clinical outcomes.

Hot on the trail: Coseismic heating on a localized structure along the Muddy Mountain fault, Nevada

Recent advances in the use of thermal proxies to identify past earthquake slip in exhumed faults have created an extraordinary opportunity to map the geometry of past ruptures in unprecedented detail. This approach can reveal along-strike differences in the structure and speed of earthquake slip. Here, we present organic thermal maturity data collected along the Muddy Mountain thrust in Nevada to investigate where it was within the fault that earthquake slip occurred and whether this is consistent along strike. We observe large changes in thermal maturity, which represent temperature-rise variations along the fault. Modeling of thermal maturity measurements yield peak temperatures of 760–1090 °C where the principal slip zone (PSZ) is narrowest (0.8 mm). Nearby where the PSZ is thicker (1.5 mm) these temperatures did not exceed 500 °C. Based upon estimates of temperature rise within a submillimeter PSZ, mean frictional work during earthquake slip was 6.3–7.1 MJm−2. These results show that thickness of the active slipping zone can vary at small spatial scales and development of a continuously narrow (<1 mm) slip layer is not required for earthquake propagation. Therefore, even for an earthquake with spatially uniform slip, we may observe large variations in heating and the effectiveness of thermally-activated dynamic-weakening mechanisms.

Capacitor loss analysis method for power electronics converters

A capacitor is a major component that contributes to reducing the reliability of high-power density power electronics converters. The lifetime and reliability of capacitors are strongly influenced by temperature. An accurate loss measurement method is necessary to estimate temperature rise. However, practical capacitor loss measurement systems used in power electronics converters have not yet been developed because capacitor loss data provided by the manufacturer is usually measured under sinusoidal excitation, which is different from actual excitations of electronics converters. In this study, a capacitor loss measurement system for power electronics converters is proposed. The proposed measurement system can be used for fast capacitor loss measurement with high accuracy in a real circuit and capacitor loss analysis for each switching period of power electronics converters. To verify the accuracy of the loss measurement, the measured loss value of a filter capacitor used in a pulse width modulated inverter is compared with the calculated value. The experimental results show good agreement with the calculated capacitor loss.

Thermal analysis of hydraulic system of landing gear

Landing gear of any aircraft is an important system which aids in takeoff, landing and supports the aircraft on runway. Landing gear system employs a hydraulic actuation system for its operation. Hydraulic system provides pressurized hydraulic fluid for actuation of main and nose landing gear in deployment/retraction mode and brake pressure for braking. Advantage of Hydraulics is small sized actuators due to its high power density, easy control and transmission of power. Hence hydraulics always had been a preferred choice for compact high power systems. During the energy conversion, fluid transmission losses and inherent friction, heat energy is generated in the system which rises the fluid temperature. This heat has to be dissipated by proper means to maintain the system temperature within safe limits. This paper attempts to study the thermal aspects of hydraulic system, heat generation and dissipation to estimate temperature rise profile and steady state temperature.