Changes In Temperature Profiles Research Articles

In-situ two-dimensional temperature measurements using x-ray fluorescence spectroscopy in laminar flames with high silica particle concentrations

X-ray fluorescence spectroscopy (XRF) was used to measure temperatures and study mixing, for the first time in silica particle synthesis flames. Hexamethyldisiloxane (HMDSO) and trimethylsilanol (TMSO) were the particle precursors. A multi-element diffusion burner was used to produce a flat methane flame, and the precursors, dilute in inert gas, were injected via a central jet. Krypton was the fluorescent medium at 3.2 % concentration by volume. Scans with Kr in the central flow and not in the main flow were made to assess the mixing effects between the central and main gas flows. When HMDSO or TMSO were added, a secondary diffusion flame formed between the jet and the main methane flame. The results revealed a dramatic change in the centerline temperature profile of the jet gases when HMDSO or TMSO were added. The main methane flame stoichiometry also affected the temperature profiles. The results show HMDSO and TMSO reactions are initiated in a low-temperature and low-oxygen concentration region of the jet where thermal decomposition is not expected to be significant. Reaction of the particle precursors is therefore attributed to radical transport from the main methane flame. In the current work, particle number densities of up to 270 g/m3 locally are estimated. Thus, the study also demonstrates the capability of the XRF technique for high spatial fidelity measurements in flames with high concentrations of condensed-phase particles, leveraging the attribute that the XRF signal is generally not impacted by condensed-phase interferences. The observations and data obtained in this study inform likely reaction pathways for this important class of siloxane compounds.

A numerical study of catalytic combustion of methane-air in excess oxygen and deficient oxygen environments with increasing initial pressure: A molecular dynamic approach

In the low-temperature range, catalytic combustion results in few emissions of nitrogen oxide and happens without a visible flame. This work investigates the effect of initial pressure (IP) on catalytic methane-air combustion (CMAC) in a microchannel using the molecular dynamics (MD) method. Palladium particles with an atomic ratio of 4 % were used as a catalyst. The study also investigates the CMAC in two environments: excess oxygen (EO) and deficient oxygen (DO). The research investigates the changes in density (Den), velocity (Velo), temperature (Temp) profiles, heat flux (HF), thermal conductivity (TC), and combustion efficiency (CE). The results of the MD simulation indicate that the maximum values of Den and velocity decrease as the IP increases to 10 bar. This reduction was more pronounced in the EO medium than in the DO medium. The maximum values of density and velocity decrease to 0.105 atom/Å and 0.17 Å/ps, respectively, in the EO medium. These values decrease to 0.080 atom/Å and 0.20 Å/ps, respectively, in the DO medium. Additionally, the HF and TC values decrease in both mediums, with the EO medium showing values of 1839 W/m2 and 1.01 W/m.K, and the DO medium showing values of 1869 W/m2 and 1.04 W/m.K. If there was a DO medium, the atoms and particles of the system had a greater ability to heat transfer to different parts. Therefore, TC and HF are more in this case.

Significance of nanoparticles shape for enhanced heat transfer over on elastic sheet

This study analyzes the impact that the shape of nanoparticles has on the rate at which heat is transferred over an elastic sheet, which is one of the most important aspects of thermal management. It addresses the pressing demand for effective heat dissipation and insulation in a variety of industries, including energy systems and electronic devices, among others. The importance of this work rests in the fact that it has the potential to make conventional methods of heat transmission obsolete. By gaining an understanding of how the morphologies of nanoparticles affect their thermal properties, we may pave the way for the development of novel materials and applications, which will ultimately result in increased energy efficiency and high-performance technology. The originality by arguing that the study fills a knowledge gap on how different nanoparticle shapes influence heat transport in elastic sheets. The importance of this property for applications such as electronics and materials research should be emphasized. Within the scope of this study, a nanofluid composed of copper and water is utilized to investigate the movement of heat between the stretching sheets. This objective is supported by the utilization of the Hamilton Crosser Model as a tool. Platelets, cylinders, and blocks are some of the shapes and sizes of the nanoparticles that are utilized in this process. A magnetic field is applied, which changes the thermal properties of the nanofluids that are being used in the process of exchanging heat between two objects. This makes the process go more quickly. A similarity transformation is used to convert the governing equations into a collection of ordinary differential equations (ODEs). By using the shooting method, the boundary value problem can be converted into an initial value problem. This is achievable since the shooting technique is a shooting method. After that, a numerical solution is found for this issue using the RK-4 method. We give visual data that demonstrates how the flow pattern and temperature profile change as a result of a variety of different causes. Plots are provided for both the Nusselt number and the skin friction coefficient. As the inquiry goes on and the values of the key parameters are changed, one thing that happens consistently across all forms of nanoparticles is an increase in the velocity profile. This is a pattern. In addition, the nanofluid that is formed of platelet-shaped nanoparticles (which has a bigger value of shape factor) is shown to have the greatest temperature. This finding demonstrates a clear association between temperature and shape factor.

Numerical investigation of flow stratification and heat transfer characteristics in a strongly heated horizontal rod bundles with helium-Xenon gas mixture

The helium-xenon(He-Xe) mixture has good heat transfer characteristics with a low Prandtl number(Pr ≈ 0.2 ∼ 0.3) and is suitable for the advanced compact gas-cooled reactor. The characteristics of horizontal flow stratification in the fuel rod bundles with He-Xe mixture under gravity and buoyancy were numerically simulated. Different wall heat flux q+ suitable for the reactor operating conditions were selected for calculation and analysis. Flow stratification is observed as strongly inhomogeneous in the radial direction. With the semi-local wall coordinates and Van-Driest transformation, laminarization is manifested by velocity and temperature profile and turbulent kinetic energy changes. In the horizontal flow, where the buoyancy is orthogonal to the direction of flow development, unique characteristics appear in the flow and heat transfer, and the growing longitudinal momentum and energy transport are considered the main reasons. The influence of flow acceleration and buoyancy under different bundle structures were compared. The buoyancy effect is evident in the loosely spaced rod bundles. In contrast, the thermally-induced flow acceleration effect in the tight-lattice scheme is noticeable.

Calculated and model profile of reservoir temperature during in-formation oxidation on the example of an oil field

The article describes physical and mathematical models of reservoir oxidation in oil deposits, the development of which is impossible with known technologies. In-formation oxidation is realized in the form of oil oxidation. A laboratory experiment on the core for the formation of combustion is presented, and the problems arising during the initiation of combustion in the rocks of the Bazhenov formation are described. It was revealed that the temperature gradient at the front and the rate of movement of the oxidation front are influenced by the volume of injected oxygen and the amount of kerogen per unit volume of the formation. The well-known Thomas model has been adapted for the analytical solution of the radial problem of in-situ combustion to the conditions of the implementation of oxidation processes in bituminous formations. The results of analytical calculations of the dynamics of changes in the formation temperature profile depending on the content of coking material and the flow rate of the injected air are presented. It was found that the temperature gradient at the front reaches 1,573 K/m, and that the rate of oxidation movement is influenced by the volume of oxygen and the density of kerogen reserves in the formation. Recommendations are made for further study of the advance of the front of intra-layer combustion in order to clarify the dependencies of the influence of other parameters (permeability, water saturation, etc.) on the speed of the front advance.

Non-similar analysis of MHD bioconvective nanofluid flow on a stretching surface with temperature-dependent viscosity

In this research, we explore the potential of magnetohydrodynamic (MHD) bioconvective nanofluids with varying viscosity through non-similarity analysis, aiming to enhance the thermal performance of biological and industrial systems. Recent years have witnessed significant advancements in energy applications, motivating our investigation. To enhance heat transfer, we employ propylene glycol as the base liquid, incorporating silicon dioxide and molybdenum disulfide nanomaterials. This unique configuration enables efficient heat dissipation and accommodates inner heat sources or sinks. Our model relies on partial differentials, and we derive a non-similar dimensionless representation of the governing system using appropriate transformations. We utilize ordinary differential equations (ODEs), approximating local non-similarity (LNS), to estimate transformed non-similar partial differential equations (PDEs). Numerical simulations are performed using the bvp4c algorithm. Throughout our analysis, we present various physical parameters, demonstrating their importance in fluid flow and thermal transport through graphical and tabular representations. Our findings show that alterations in the magnetic parameter lead to changes in fluid velocity and temperature profiles. Similarly, adjustments in the viscosity parameter affect fluid velocity, and variations in the temperature-dependent viscosity parameter influence velocity profiles, with temperature profiles responding to changes in the Brinkman number and heat source parameter. Additionally, we observe concentration profile adjustments with shifts in the Schmidt number and enhanced migration of particles or components within the nanofluid with rising Soret numbers, impacting the concentration profile. Furthermore, an increased Peclet number positively influences microorganism profiles, while the Lewis number exhibits contrasting behavior. To further validate our approach, we present comparative analyses of skin friction coefficients and Nusselt numbers in tabular form. Our primary objective in this study is to formulate non-similar transformations tailored to the specific problem under consideration. These transformations aim to produce accurate and efficient results, providing valuable insights for future research endeavors in the field of nanofluid flows.

Mathematical Model of Heat and Mass Transfer of Coal in a Stack

A mathematical model of coal’s self-heating in the stack is presented, where the heat exchange and gas exchange processes are described by a system of two non-linear differential equations of the second order concerning temperature t of coal’s self-heating and volume fraction C of oxygen in the cavities of the stack with boundary and initial conditions. The differential equations took into account that self-heating of coal in the stack and initiation of self-ignition are observed in a relatively small layer adjacent to the surface of the stack and called the zone of oxygen influence. In this mathematical model authors have taken into account the influence on the process of coal’s self-heating of parameter Ф – specific heat release power, which in addition characterises the preservation of coal during storage. There were also used such physical parameters as thermal conductivity, diffusion coefficient, specific heat capacity of coal in the stack, bulk density, thermal effect of oxidation, stack cavity, temperature coefficient of exponential growth of heat release power when compiling the differential equations. For numerical implementation of this mathematical model, there were introduced dimensionless variables and criteria, which allowed to apply the grid method. Analysis of the final results allowed to obtain: changes in stack temperature profiles in time; changes in stack oxygen concentration profiles in time; influence on stack temperature profile of specific heat release power; influence on stack temperature profile of the parameter characterising exponential growth of heat release intensity with increasing temperature. It has been found that the greatest influence on the dynamics of self-heating of coal in the stack has the Lykov criterion, proportional to the diffusion coefficient, and the Nusselt criterion related to the effective thermal conductivity and the effective thermal diffusivity of coal. The results obtained suggest that self-heating in the stack is due, on the one hand, to intensive penetration of air oxygen and, on the other hand, to impaired heat dissipation. Self-heating and the transition of self-heating into ignition is associated with the occurrence of turbulent diffusion in the stack, arising from increased heat blowing, the effect of which can be enhanced when directed perpendicular to the surface of the stack.

Study on the effect of carbon fiber ply angle on thermal response of CFRP laminate based on the thermal resistance network model

AbstractCarbon fiber reinforced polymer (CFRP) exhibits different heat transfer phenomena along the fiber direction and the transverse direction during the heat transfer process due to its anisotropic thermo‐physical properties, which makes it difficult to quantitatively analyze the overall thermal performance of CFRP with different ply angles. A thermal resistance network model of composite material considering fiber ply angle and heat transfer direction was developed based on the series–parallel resistance computing method, and it was applied to describe the test results measured by the thermal response tests of unidirectional carbon fiber laminates. Thermal resistance Rx along the heat transfer direction and Ry transverse to the heat transfer direction calculated by the proposed model, which are related with the thermal response of the specimen, can be utilized to reflect the temperature values and temperature distribution maps. It was found that as the fiber ply angle θ increases from 0° to 45°, thermal resistance in the x‐axis direction increases from about 0.13 K/W to 2.56 K/W, while thermal resistance in the y‐axis direction decreases about 48.7%. As a result, major axis of quasi‐ellipse temperature profile changes by about +45° relative to the x‐axis.Highlights A CFRP thermal resistance network model considering ply angle was proposed. The series–parallel thermal resistance method is used to calculate Rx and Ry. The ply angle from 0° to 45°, Rx increases several times and Ry decreases by half. Major axis of elliptic temperature curve changes by +45° relative to the x‐axis.

New insights into the dynamics of heat and mass transfer in a hybrid (Ag-TiO[formula omitted]) nanofluid using Modified Buongiorno model: A case of a rotating disk

The activation energy model is used in this work to examine how hybrid nanoparticles affect the flow across a rotating disk. Here, we considered nanoparticles of silver (Ag) and titanium dioxide (TiO2) dissolved in water, a base liquid. These nanoparticles have real applications such as photography, photocatalysis, water purification, and solar energy conversion. The current study investigates the combined effects of a changing magnetic field, Darcy Forchheimer, porosity, thermal radiation, Brownian motion, and thermophoresis on hybrid nanofluid flow across a rotating disk. By applying similarity transformations, the partial differential equations system of the current scheme is converted into an ordinary differential equations system, after which it is calculated with MATLAB using the bvp4c scheme. Graphs are used to assess the investigation of mass and heat transport. Also, the change in concentration, temperature, and velocity profiles for various non-dimensional factors are discussed briefly using corresponding graphs. It has been noted that the velocity gradient of mono and hybrid nanofluids is reduced as the magnetic parameter inputs increase. The velocity profiles decline as the input of the Darcy-Forchheimer parameter increases. The outcome demonstrates that temperature and concentration increase as the thermophoresis parameter rises. The concentration profile is enhanced as an activation energy parameter increases. Moreover, the average Nusselt number is 37.73 % at M=0.8, and when M=2.2, the value of the average number decreased by 29.43 %. The concentration of silver (Ag) and titanium dioxide (TiO2) is (0−6)%.

Day and night: habitability of tidally locked planets with sporadic rotation

ABSTRACT Tidally locked worlds provide a unique opportunity for constraining the probable climates of certain exoplanets. They are unique in that few exoplanet spin and obliquity states are known or will be determined in the near future: both of which are critical in modelling climate. A recent study shows the dynamical conditions present in the TRAPPIST-1 system make rotation and large librations of the substellar point possible for these planets, which are usually assumed to be tidally locked. We independently confirm the tendency for planets in TRAPPIST-1-like systems to sporadically transition from tidally locked libration to slow rotation using N-body simulations. We examine the nature and frequency of these spin states to best inform energy balance models which predict the temperature profile of the planet’s surface. Our findings show that tidally locked planets with sporadic rotation are able to be in both long-term persistent states and states with prolonged transient behaviour: where frequent transitions between behaviours occur. Quasi-stable spin regimes, where the planet exhibits one spin behaviour for up to hundreds of millennia, are likely able to form stable climate systems while the spin behaviour is constant. 1D energy balance models show that tidally locked planets with sporadic rotation around M-dwarfs will experience a relatively small change in substellar temperature due to the lower albedo of ice in an infrared dominant stellar spectrum. The exact effects of large changes in temperature profiles on these planets as they rotate require more robust climate models, like 3D global circulation models, to better examine.

Numerical analysis on the energy efficiency improvement of thermo-injection method of masonry walls drying by applying the variable temperature profiles of drying air

The influence of the drying air temperature profile on the effectiveness of the thermo-injection masonry wall drying method was investigated by applying numerical modeling. The in-house non-equilibrium heat and moisture transfer model was used to perform simulations. A two weeks drying process was simulated. Four drying strategies characterized by constant, jump, stepwise, and periodic drying air temperature profiles were studied and compared. Three different heating intervals (i.e., 12, 24, and 48 h), which referred to drying air temperature profile changes, were examined. The drying air temperature varied between 20 and 60 °C. Moreover, the relative humidity of the drying air corresponded to the three seasons in Poland, i.e., winter, spring, and summer, and ranging between 70 and 90% at ambient conditions. It was found that drying strategies with the jump and stepwise temperature profiles may decrease the energy consumption required for masonry wall drying by up to 5.9% during the season with a low drying air relative humidity (i.e., during winter). However, energy savings were insufficient during the highly humid season (i.e., summer). The heating interval of 48 h was the best for the jump strategy and may be the best for the stepwise approach in a longer than two weeks drying process. The stepwise strategy removed significantly more water from the wall to reach the same level of moisture mass fraction in the drying zone as the constant and jump strategies. The slower wall heating process and the continuous action of capillary water uptake were responsible for this behavior. The same phenomena caused the periodic strategy to be ineffective.

Evaluation of identification methods for heat transfer deterioration of supercritical CO2

Heat transfer deterioration (HTD) identification is essential for establishing heat transfer correlations and HTD criteria. To assess the accuracy of various HTD identification methods, an experimental investigation of the convective heat transfer characteristics of supercritical CO2 in heated tubes with diameters of 8 and 14.5 mm was conducted. In addition, data from published literature were used as supplements for ranges not covered by this experiment. The evaluation of identification methods was conducted for tube diameters ranging from 2 to 22 mm, pressures from 7.5 to 21.1 MPa, mass fluxes from 50 to 1600 kg/m2·s, and heat fluxes from 6 to 375 kW/m2. Based on these datasets, the accuracy and the appropriate application of each method were determined. The results showed that the Nu/Nudb and Gupta et al. methods are not sufficiently accurate and cannot reflect the heat transfer trend reliably. The Kline et al. method may produce illogical results in cases of a large q/G. The Xie et al. method is not effective in heat transfer enhancement (HTE) cases and HTD cases, where the wall temperature profile changes slowly. Both the Lokshin et al. and Zhang et al. methods require prior addition or adjustment of correction factors.

Novel Lyapunov-based rapid and ripple-free MPPT using a robust model reference adaptive controller for solar PV system

The technological, economic, and environmental benefits of photovoltaic (PV) systems have led to their widespread adoption in recent years as a source of electricity generation. However, precisely identifying a PV system's maximum power point (MPP) under normal and shaded weather conditions is crucial to conserving the maximum generated power. One of the biggest concerns with a PV system is the existence of partial shading, which produces multiple peaks in the P–V characteristic curve. In these circumstances, classical maximum power point tracking (MPPT) approaches are prone to getting stuck on local peaks and failing to follow the global maximum power point (GMPP). To overcome such obstacles, a new Lyapunov-based Robust Model Reference Adaptive Controller (LRMRAC) is designed and implemented to reach GMPP rapidly and ripple-free. The proposed controller also achieves MPP accurately under slow, abrupt and rapid changes in radiation, temperature and load profile. Simulation and OPAL-RT real-time simulators in various scenarios are performed to verify the superiority of the proposed approach over the other state-of-the-art methods, i.e., ANFIS, INC, VSPO, and P&O. MPP and GMPP are accomplished in less than 3.8 ms and 10 ms, respectively. Based on the results presented, the LRMRAC controller appears to be a promising technique for MPPT in a PV system.

Effects of mode of heat transfer on puffing quality of rice grain: A modeling and simulation analysis

AbstractCereal grains can be puffed by heating in hot sand bed or domestic microwave oven. The purpose of this study was to explore and compare the reasons of transformational changes in preconditioned rice during its sand bed heating and microwave heating in domestic microwave oven. Mathematical modeling and simulation techniques were used to estimate the changes in microwave power absorption density and temperature of rice with the heating methods. Sand puffing, initiated from the tips of rice, progressed toward the central region of the rice following the change in temperature profile of rice and outcomes were completely puffed rice. The rice grains, placed in the different radial zones on the turntable of oven cavity, experienced nonuniform and inconsistent rate of microwave power absorption within the rice due to its placement and rotation, the oven factors, grain's shape, size, and dielectric properties. Microwave puffing, initiated from the central region of rice, progressed toward the tips of the rice. The slow rate of heating resulted in evaporative cooling of rice and most of the rice were unable to puff completely. However, the rate of microwave heating of rice was comparable with that of sand heating and about 92.0 ± 2.3% puffed was observed when rice was place in radial zone of 5.0 cm. Hence, the exact placement of rice in the oven cavity was required for achieving good puffing quality of rice.Practical applicationsThe present study helps to understand the reasons for uneven puffing of rice in domestic microwave oven. This understanding of puffing process in domestic microwave oven provides an opportunity to develop strategy for microwave puffing of rice or design a specific microwave puffing equipment suitable for achieving quantitative and qualitative puffing of rice.

First experimental characterization of CaCl2 coated heat exchanger for thermochemical heat transformer applications in industrial waste heat recovery

This study aims at evaluating the performance of a heat exchanger coated with CaCl2 (PVA polyvinyl alcohol used as binder) for Thermochemical Heat Transformers (THT) applications in industrial waste heat recovery.For this purpose, an experimental test bench has been built allowing to test operating temperatures up to 160 °C. A model heat exchanger plate is used to test two configurations: a thick layer of CaCl2 to model a packed bed reactor (used as reference) and a CaCl2-PVA deposit to model a coated reactor.For the packed bed configuration, results comparable to that of the literature are obtained with a specific power of 180 W/kg obtained for a temperature lift of 60 K. A high sensitivity to temperature lift is identified with a decrease of the specific power down to 38 W/kg for a lift of 77 K. The coated heat exchanger configuration achieves significantly higher performance with a specific power up to 341 W/kg for a temperature lift of 63 K. However, the analysis of the repeatability tests highlights a rapid change in temperature profiles highlighting a change in properties of the CaCl2/PVA compound material. Next steps will consist in enhanced material formulation and change in deposit protocol and to move to work at small reactor scale to assess system performance.

The dissolution of p-methoxycinnamic acid-β-cyclodextrin inclusion complex produced with microwave irradiation.

p-methoxycinnamic acid (pMCA) is an ethyl pmethoxycinnamic derivative, which is the largest active ingredient in the rhizome of the kencur (Kaempferia galanga L) plant. Several studies reported that the compound has anti-inflammatory activity but has low solubility in water. The formation of a pMCA-β- cyclodextrin (βCD) inclusion complex with a molar ratio of 1:1 can increase its solubility. The formation of inclusion complexes with conventional methods requires a long time and the yield value is not optimal. This study aims to evaluate the dissolution of the pMCA-βCD inclusion complex produced using the microwave irradiation method. The product was manufactured with chloroform solvent and a power of 400 watts (power 80%). It was then evaluated using the Differential Thermal Analysis (DTA) every 2 minutes until the 8th minute. The reaction was complete after 4 minutes of treatment with a yield of 96.5%. The obtained inclusion complexes were evaluated using DTA, FTIR, and PXRD. Subsequently, a dissolution test was carried out using a type 2 apparatus in distilled water medium of pH 6.8±0.05 at 37±0.5°C. The results showed that there was a change in the melting temperature profile, infrared spectra, and crystallinity of the product. An 89.18% dissolution was also obtained within 60 minutes, which was twice that of pMCA compounds. From the results of the study, it can be concluded that the formation of pMCA-βCD inclusion complexes using the microwave irradiation method is capable of providing high-yield values in a short time.

Crustacean zooplankton densities in northern temperate lakes are related to habitat temperature across a wide gradient in lake dissolved organic carbon and nutrient content

Abstract Lake crustacean zooplankton densities often are negatively correlated with terrestrial dissolved organic carbon (DOC) concentrations. These reductions in zooplankton with increased DOC are hypothesised to be linked to diminished resource quantity or lower resource quality as terrestrial material is low in essential nutrients and macromolecules. The impact of DOC on lake physics also potentially reduces available habitat for zooplankton as the warm and well‐oxygenated epilimnion is shallower in lakes with high DOC concentrations. Our goal was to investigate these potential mechanisms to determine the influence of DOC on drivers of zooplankton densities in a survey of north temperate lakes. We sampled crustacean zooplankton densities in 10 lakes that varied in mean DOC concentration from 6 to 27 mg L−1. We also measured resource availability as chlorophyll concentration, resource quality as essential fatty acid (EFA) concentration and the stoichiometric ratio of carbon‐to‐phosphorus (C:P), and habitat availability as integrated habitat temperature and dissolved oxygen to determine the strongest predictor of zooplankton densities across lakes. In addition, we quantified zooplankton habitat use through Schindler trap profiles through the water column. Zooplankton densities were most strongly related to integrated habitat temperature and were not closely related to measures of resource quantity or quality. Depth of the mix layer was negatively correlated with DOC concentration, yet there was no relationship between DOC concentration and zooplankton habitat use. Overall resource quantity and quality increased across the DOC gradient, as chlorophyll and EFA concentration were greatest in lakes with higher DOC. Our results indicate the potential for physics‐mediated responses between lake DOC and zooplankton density. As lakes with greater DOC concentrations have, on average, shallower mixed layers and colder habitats, zooplankton may either be constrained to a relatively smaller proportion of the catchment or experience reduced temperatures that may delay development or feeding rates. Lake DOC concentrations are projected to increase under future climate scenarios, so accompanying changes in lake temperature profiles are likely to follow. These also may reduce food‐web productivity, as shrinking mixed layers or colder total water columns resulting from steeper thermoclines may reduce habitat availability or suitability for zooplankton communities.

Effect of uniform and nonuniform temperature distributions on sound transmission loss of double-walled porous functionally graded magneto-electro-elastic sandwich plates with subsonic external flow

Using the third-order shear deformation theory (TSDT), this research investigates the loss in sound transmission through air-filled rectangular double-walled sandwich smart magneto-electro-elastic (MEE) plates with a porous functionally graded material (PFGM) core layer, in the presence of external mean airflow and subjected to uniform and non-uniform temperature distributions. Multiple temperature profiles are evaluated in order to correctly capture the impact of the temperature rises over the thickness. Based on the power-law model, three different types of uneven porosity distributions are considered for the PFGM core layer. These distributions should change along the in-plane and thickness directions. Hamilton's concept is used to achieve the derivation of vibroacoustic equations as coupled relations. The sound transmission loss (STL) equation is obtained by using a double Fourier series in combination with an analytical method, i.e., the second velocity potential. The produced solution is evaluated in terms of accuracy and precision by comparing it to other accessible data from a previous study. The effects of the initial electric and magnetic potentials, porosity distributions, incidence angles, acoustic cavity depth, and changes in temperature profile on STL are shown by parameter investigations.

Thermal Modeling of Patient-Specific Breast Cancer With Physics-Based Artificial Intelligence

AbstractBreast cancer is a prevalent form of cancer among women. It is associated with increased heat generation due to higher metabolism in the tumor and increased blood vessels resulting from angiogenesis. The thermal alterations result in a change in the breast surface temperature profile. Infrared imaging is an FDA-approved adjunctive to mammography, which employs the surface temperature alterations in detecting cancer. To apply infrared imaging in clinical settings, it is necessary to develop effective techniques to model the relation between the tumor characteristics and the breast surface temperatures. The present work describes the thermal modeling of breast cancer with physics-informed neural networks. Losses are assigned to random points in the domain based on the boundary conditions and governing equations that should be satisfied. The Adam optimizer in TensorFlow minimizes the losses to find the temperature field or thermal conductivity that satisfies the boundary conditions and the bioheat equation. Backpropagation computes the derivatives in the bioheat equation. Analyses of the three patient-specific cases show that the machine-learning model accurately reproduces the thermal behavior given by ansys-fluent simulation. Also, good agreement between the model prediction and the infrared images is observed. Moreover, the neural network accurately recovers the thermal conductivity within 6.5% relative error.

Hyperthermia Using Magnetic Cobalt Ferrite Magnetoelectric Nanoparticles

The focus of this article is to understand the application and the factors influencing magnetic hyperthermia using cobalt ferrite nanoparticles. Intrinsic properties, such as particle size, specific absorption rate, and magnetic saturation, are correlated with the material’s property to generate hyperthermia. External factors, such as the magnitude of applied field frequency, also influence the rate of hyperthermia generated by magnetic nanoparticles. Quantitative analysis of Pennes bioheat equation and finite element analysis (FEA) using COMSOL are used to understand the transient increase in temperature at the tumor site using magnetic nanoparticles. The required temperature for generating hyperthermia using nanoparticles is approximately 315 K or 42 °C. Due to the intrinsic high rate of metabolism in tumor cells, the required magnetic field to induce transient increase at the malignant cell site is less than its surrounding healthier cells. This principle can therefore be applied for inducing selective hyperthermia in tumor cells by the application of a lower threshold external magnetic field. This article focuses on the Pennes bioheat equation to understand the phenomenon of heat transfer as a function of both the time and the applied field magnitude. It compares the difference in the rate of heat transfer for 1) cobalt ferrite and cobalt ferrite–barium titanate and 2) hyperthermia in healthier and tumor sites using magnetic nanoparticles. An FEA is performed in conjunction to understand the rate of temperature profile change occurring at a simulated cell site.