Radiation Energy Research Articles

Enhanced near-field radiative heat transfer between nanostructure emitter and GaSb absorber by surface plasmon polaritons and hyperbolic modes

Near-field radiative heat transfer (NFRHT) can overcome the blackbody radiation limit and holds great promise in radiative energy conversion devices such as near-field thermophotovoltaics (NF-TPV). However, NF-TPV is not yet ready for practical applications at larger scales due to the challenges of maintaining the nanoscale gap and the lack of optimized NFRHT with nanostructure emitters. Here, we measure the enhanced near-field radiative heat flux between GaSb absorbers and nanostructure emitters that can be applied in NF-TPV systems, with a cm2-scale plate–plate structure and a temperature difference of 100 K at a gap down to 200 nm. It is demonstrated that the radiative heat flux between the bulk W emitter and the absorber at a 400 nm gap is about an order of magnitude larger than that in the far field, and the heat flux can be further enhanced by 1.6 times at a 200 nm gap. Moreover, the enhanced NFRHT from the surface plasmon polaritons supported by a indium tin oxide film and the hyperbolic modes supported by a W/SiO2 multilayer is also experimentally verified and theoretically analyzed.

Effect of high energy radiation on electrical properties of synthetic bone materials

AbstractHydroxyapatites have been investigated since past six decades as laser host materials. Because of their important roles in bone and teeth, these have been subjects of recent investigations. Gallium and titanium have great potential for decreasing the depletion of calcium and reducing osteoporosis. The electrical properties and polarity play important roles in regeneration of the bones. We observed growth of grains in selenium‐doped gallium and titanium containing silicate hydroxyapatites. Observed morphology showed non‐facetted microstructures and it helped in achieving larger grains. For the material processed for the period of longer than 70 h, we did not observe any difference in the dielectric constant and resistivity of the selenium‐doped materials. For irradiating the materials, a Cs‐137 γ‐radiation with 5 µm curie dose was used up to 100 h. We observed that the dielectric constant and resistivity at different frequencies ranging from 100 to 100 000 Hz were affected by the high energy radiation. However, bias voltage in the range of 50–1 000 mV did no alter the dielectric constant or resistivity. This indicated that the breakdown of the material did not occur for this bias range.

The shape function method of nonlinear thermal stress of granite fracture tips in a high-temperature environment

Exposed rock masses in tunnel portals are susceptible to thermal deterioration in southern China, where temperatures are relatively high. The thermal stress field of rock masses is affected by fracture shape and distribution as fractures near the surface are channels for solar radiation energy to be converted into rock thermal energy. In this study, a function expression is developed for triangular heat sources of fractured rock masses in a tunnel portal in a high-temperature environment. By the function expression, the temperature field and thermal stress field are calculated, and the influence of fracture shape parameters and multi-fracture interaction is analyzed. The results are as follows: (1) the temperature field and thermal stress field of exposed rocks are redistributed by fractures. The internal temperature of the fractured rocks is higher than that of non-fractured rocks, and thermal stress near the fracture tip increases. (2) For triangular fractures of the same length, thermal stress increases as the apex angle increases. (3) When the spacing between parallel fractures or coplanar fractures is close, the superposition effect of thermal stress becomes significant. (4) In a high-temperature environment, temperature field and thermal stress field of a fractured rock are both nonlinear as temperature and thermal stress around fractures increase significantly. The results provide effective reference for stability evaluation of fractured rock masses in tunnel portals and offer theoretical foundation for thermal diseases analysis and protection measures of tunnel engineering in high-temperature environments of southern China.

Multi-point calorimeter using distributed fiber Bragg gratings for small field dosimetry in radiotherapy.

The interest of using fiber Bragg gratings (FBGs) dosimeters in radiotherapy (RT) lies in their (i) microliter detection volume, (ii) customizable spatial resolution, (iii) multi-point dose measurement, (iv) real-time data acquisition and (v) insensitivity to Cherenkov light. These characteristics could prove very useful for characterizing dose distributions of small and nonstandard fields with high spatialresolution. We developed a multi-point FBGs dosimeter customized for small field RT dosimetry with a spatial resolution of 1mm. The 3cm-long multi-point dosimeter is made by embedding a 80 silica fiber containing an array of thirty (30) co-located 1mm-long fs-written FBGs inside a plastic cylinder with an UV curing optical adhesive. With its higher thermal expansion coefficient, the plastic cylinder increases the sensitivity of the dosimeter by stretching the fiber containing the FBGs when the temperature rises slightly due to radiation energy deposition. Irradiations (2000MU at 600MU/min) were performed with a Varian TrueBeam linearaccelerator. The dose profile of a 2 2cm 6MV beam was measured with a mean relative difference of 1.8% (excluding the penumbra region). The measured output factors for a 6MV beam are in general agreement with the expected values within the experimental uncertainty (except for the 2 2cm field). The detector response to different energy of photon and electron beams is within 5% of the mean response ( pm/Gy). The calorimeter's post-irradiation thermal decay is in agreement with thetheory. An energy-independent small field calorimeter that allows dose profile and output factor measurements for RT using FBGs was developed, which, to our knowledge, has never been done before. This type of detector could prove really useful for small field dosimetry, but also potentially for MRI-LINAC since FBGs are insensitive to magnetic fields and for FLASH since FBGs have been used to measure doses up to100kGy.

Thermal infrared observations of a western United States biomass burning aerosol plume

Abstract. Biomass burning smoke particles, due to their submicron particle size in relation to the average thermal infrared (TIR) wavelength, theoretically have negligible signals at the TIR channels. However, nearly instantaneous longwave (LW) signatures of thick smoke plumes can be frequently observed at the TIR channels from remotely sensed data, including at 10.6 µm (IR window), as well as in water-vapor-sensitive wavelengths at 7.3, 6.8, and 6.3 µm (e.g., lower, middle, and upper troposphere). We systematically evaluated multiple hypotheses as to causal factors of these IR signatures of biomass burning smoke using a combination of data from the Aqua MODerate resolution Imaging Spectroradiometer (MODIS), Aqua Cloud and the Earth Radiant Energy System (CERES), Geostationary Operational Environmental Satellite 16/17 (GOES-16/17) Advanced Baseline Imager, and Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) and Cross-track Infrared Sounder (CrIS). The largely clear transmission of light through wildfire smoke in the near infrared indicates that coarse or giant ash particles are unlikely to be the dominant cause. Rather, clear signals in water vapor and TIR channels suggest that both co-transported water vapor injected to the middle to upper troposphere and surface cooling by the reduction of surface radiation by the plume are more significant, with the surface cooling effect of smoke aloft being the most dominant. Giving consideration of the smoke impacts on TIR and longwave, CERES indicates that large wildfire aerosol plumes are more radiatively neutral. Further, this smoke-induced TIR signal may be used to map very optically thick smoke plumes, where traditional aerosol retrieval methods have difficulties.

Ionic-resolution protoacoustic microscopy: A feasibility study.

Visualizing micro- and nano-scale biological entities requires high-resolution imaging and is conventionally achieved via optical microscopic techniques. Optical diffraction limits their resolution to ∼200 nm. This limit can be overcome by using ions with ∼1 MeV energy. Such ions penetrate through several micrometers in tissues, and their much shorter de Broglie wavelengths indicate that these ion beams can be focused to much shorter scales and hence can potentially facilitate higher resolution as compared to the optical techniques. Proton microscopy with ∼1 MeV protons has been shown to have reasonable inherent contrast between sub-cellular organelles. However, being a transmission-based modality, it is unsuitable for in vivo studies and cannot facilitate three-dimensional imaging from a single raster scan. Here, we propose proton-induced acoustic microscopy (PrAM), a technique based on pulsed proton irradiation and proton-induced acoustic signal collection. This technique is capable of label-free, super-resolution, 3D imaging with a single raster scan. Converting radiation energy into ultrasound enables PrAM with reflection mode detection, making it suitable for in vivo imaging and probing deeper than proton scanning transmission ion microscopy (STIM). Using a proton STIM image of HeLa cells, a coupled Monte Carlo+k-wave simulations-based feasibility study has been performed to demonstrate the capabilities of PrAM. We demonstrate that sub-50 nm lateral (depending upon the beam size and energy) and sub-micron axial resolution (based on acoustic detection bandwidth and proton beam pulse width) can be obtained using the proposed modality. By enabling visualization of biological phenomena at cellular and subcellular levels, this high-resolution microscopic technique enhances understanding of intricate cellular processes.

Comparison Between Perovskite and Silicon for Photovoltaic Cell Applications and Future Industrial Prospects

Environmental concerns have evolved into an essential focal point within contemporary human progress. An increasing number of individuals are recognizing the paramount significance of safeguarding our environment and are actively engaged in crafting a sustainable developmental framework. An integral facet of sustainable progress is the adoption of clean energy, representing a pivotal paradigm shift in the global energy landscape. One remarkable manifestation of this shift is the utilization of photovoltaic (PV) cells, which adeptly transmute radiant light energy into electrical power. This paper delves into an exploration of the prevailing silicon photovoltaic cells widely accessible in the market, while also delving into the realm of perovskite photovoltaic cells, an experimental yet highly promising avenue. It endeavors to juxtapose these two technologies across various dimensions, including energy conversion efficiency, overall cost implications, and environmental repercussions. Evidently, silicon and perovskite technologies manifest distinct advantages and drawbacks in different contexts. It is unequivocally established that both forms of photovoltaic cells hold profound implications for the future trajectory of energy consumption and the overarching ethos of sustainable development.

Effect of dimension size on electromagnetic radiation energy characteristics of lead zirconate titanate under drop weight impact load

This article presents a study on Electromagnetic radiation (EMR) energy harvesting characteristics of lead zirconate titanate (PZT) of soft grade (SP 5 A) samples under drop weight impact load. In the present study, four samples having different diameter to thickness (d/t) ratio were used. A possible EMR energy harvesting mechanism from these samples under impact loading has been discussed. It is found that the EMR parameters viz. EMR voltage, generated EMR energy, and so on, depend on the dimension of the sample and applied mechanical energy. The sample having highest t/d 2 (0.069) produces maximum EMR voltage, that is, 2.31 V. Also for the same sample, EMR parameters increase with the increase in applied mechanical energy. Also an increasing pattern of EMR energy was observed with the increase in the capacitance value of the capacitor. The results obtained suggest the possibility of using PZT as a better option for energy harvesting, sensing, and structural health monitoring applications. Also the results suggest EMR technique as an alternative option for harnessing energy from piezoelectric ceramics.

A Novel Multifunctional Photonic Film for Colored Passive Daytime Radiative Cooling and Energy Harvesting.

Passive daytime radiative cooling (PDRC) materials with sustainable energy harvesting capability is critical to concurrently reduce traditional cooling energy utilized for thermal comfort and transfer natural clean energies into electricity. Herein, a versatile photonic film (Ecoflex@BTO@UAFL) based on a novel fluorescent luminescence color passive radiative cooling with triboelectric and piezoelectric effect is developed by filling the dielectric BaTiO3 (BTO) nanoparticles and ultraviolet absorption fluorescent luminescence (UAFL) powder into the elastic Ecoflex matrix. Test results demonstrate that the Ecoflex@BTO@UAFL photonic film exhibits a maximum passive radiative cooling effect of ∽10.1 °C in the daytime. Meanwhile, its average temperature drop in the daytime is ~4.48 °C, which is 0.91 °C higher than that of the Ecoflex@BTO photonic film (3.56 °C) due to the addition of UAFL material. Owing to the high dielectric constant and piezoelectric effect of BTO nanoparticles, the maximum power density (0.53Wm-2, 1Hz @ 10 N) of the Ecoflex@BTO photonic film-based hybrid nanogenerator is promoted by 70.9% compared to the Ecoflex film-based TENG. This work provides an ingenious strategy for combining PDRC effects with triboelectric and piezoelectric properties, which can spontaneously achieve thermal comfort and energy conservation, offering a new insight into multifunctional energy saving.

A proceeding to numerical study of mathematical model of bioconvective Maxwell nanofluid flow through a porous stretching surface with nield/convective boundary constraints

Nanofluids become significant in the mass and heat transfer models, especially in engineering problems. Current proceedings focused on the bioconvective Maxwell nanofluid flow passing through the permeable stretchable sheet contingent to nield boundary conditions involving effects of activation energy and thermal radiation. Various physical quantities are involved in this mechanism like magnetic field, thermophoresis, and Brownian motion. The main objective of the study is to report the heat and mass transport in the existence of motile microorganisms. In a mathematical perspective, this structured physical model is going to govern with the help of partial differential equations (PDEs). These governing PDEs are then converted into dimensionless ordinary differential equations form by utilizing appropriate similarity transformations. For numerical results, the shooting technique with ‘bvp4c’ built-in package of MATLAB was implemented. Computed results are then visualized graphically and discussed effects of involving physical variables on the nano-fluid flow profiles are comprehensively. From results, it has been concluded that the fluid flow velocity, temperature, concentration, and microorganism density profiles show escalation on increasing the numeric values of porosity, thermophoresis, buoyancy ratio, bioconvection Rayleigh, Peclet number parameters and decrement reported due to increasing the counts of Prandtl number, magnetic field, radiation, Brownian motion, Lewis number as evident from figures. The numerical outcomes observed by fixing the physical parameters as 0.1<λ<3.0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < \\lambda < 3.0$$\\end{document}, 0.1<M<1.5\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < M < 1.5$$\\end{document}, 0.1<Nr<6.0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < Nr < 6.0$$\\end{document}, 0.1<Rb<1.5\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < Rb < 1.5$$\\end{document}, 0.1<Nb<6.0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < Nb < 6.0$$\\end{document}, 0.1<Nt<1.0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < Nt < 1.0$$\\end{document}, 2.0<Pr<2.9\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2.0 < \\Pr < 2.9$$\\end{document}, 0.1<Rd<0.4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.1 < Rd < 0.4$$\\end{document}. Magnetic field and Brownian motion create retardation impact due to the liquid momentum. In tables, the numerical values of Skin friction, Nusselt number, Sherwood number, and microorganisms density number are presented and also comparison table of our computed results and already published results is included for the validation.

Enabling particle transport on CAD-based geometries for radiation simulations with penRed

Geometry construction is a fundamental aspect of any radiation transport simulation, regardless of the Monte Carlo code being used. Typically, this process is tedious, time-consuming, and error-prone. The conventional approach involves defining geometries using mathematical objects or surfaces. However, this method comes with several limitations, especially when dealing with complex models, particularly those with organic shapes. Furthermore, since each code employs its own format and methodology for defining geometries, sharing and reproducing simulations among researchers becomes a challenging task. Consequently, many codes have implemented support for simulating over geometries constructed via Computer-Aided Design (CAD) tools. Unfortunately, this feature is lacking in penRed and other PENELOPE physics-based codes. Therefore, the objective of this work is to implement such support within the penRed framework. New version program summaryProgram Title: Parallel Engine for Radiation Energy Deposition (penRed)CPC Library link to program files:https://doi.org/10.17632/rkw6tvtngy.2Developer's repository link:https://github.com/PenRed/PenRedCode Ocean capsule:https://codeocean.com/capsule/1041417/treeLicensing provisions: GNU Affero General Public License v3Programming language: C++ standard 2011.Journal reference of previous version: V. Giménez-Alventosa, V. Giménez Gómez, S. Oliver, PenRed: An extensible and parallel Monte-Carlo framework for radiation transport based on PENELOPE, Computer Physics Communications 267 (2021) 108065. doi:https://doi.org/10.1016/j.cpc.2021.108065.Does the new version supersede the previous version?: YesReasons for the new version: Implements the capability to simulate on CAD constructed geometries, among many other features and fixes.Summary of revisions: All changes applied through the code versions are summarized in the file CHANGELOG.md in the repository package.Nature of problem: While Monte Carlo codes have proven valuable in simulating complex radiation scenarios, they rely heavily on accurate geometrical representations. In the same way as many other Monte Carlo codes, penRed employs simple geometric quadric surfaces like planes, spheres and cylinders to define geometries. However, since these geometric models offer a certain level of flexibility, these representations have limitations when it comes to simulating highly intricate and irregular shapes. Anatomic structures, for example, require detailed representations of organs, tissues and bones, which are difficult to achieve using basic geometric objects. Similarly, complex devices or intricate mechanical systems may have designs that cannot be accurately represented within the constraints of such geometric models. Moreover, when the complexity of the model increases, geometry construction process becomes more difficult, tedious, time-consuming and error-prone [2]. Also, as each Monte Carlo geometry library uses its own format and construction method, reproducing the same geometry among different codes is a challenging task.Solution method: To face the problems stated above, the objective of this work is to implement the capability to simulate using irregular and adaptable meshed geometries in the penRed framework. This kind of meshes can be constructed using Computer-Aided Design (CAD) tools, the use of which is very widespread and streamline the design process. This feature has been implemented in a new geometry module named “MESH_BODY” specific for this kind of geometries. This one is freely available and usable within the official penRed package1. It can be used since penRed version 1.9.3b and above.

On the thermodynamics of gravitational radiation

This paper deals with the thermodynamics of gravitational radiation arising from the Bondi-Sachs space-time. The equation of state found allows us to conclude that the dependence of the energy density on the temperature is a quadratic power of the latter. Such a conclusion is possible once the consequences of the first law of thermodynamics are analyzed. Then, in analogy to electromagnetic radiation, the same approach used by Planck to obtain the quantum of energy of the gravitational radiation is proposed. An energy for the graviton proportional to the cubic frequency is found. The graviton is here understood as the quantum of gravitational energy.

A Universal Strategy for Tuning Afterglow Color In Situ Via Radiative Energy Transfer

AbstractColorful afterglow materials have promising applications in optoelectronic displays. To effectively fine‐tune the afterglow color, an assembly structure that includes UV lamp, persistent room temperature phosphorescence (pRTP) layer, and fluorescent layer (from the bottom to the top) with superimposition of pRTP and fluorescence, is designed. The fluorescence component is emitted from a PMMA film doped with asymmetric 4‐(7‐methoxy‐5,6‐dinitrobenzo[c][1,2,5,]thiadiazol‐4‐yl)‐N,N‐diphenylaniline (TPA‐TD), which has a broad absorption that covers the entire visible region, facilitating effective radiative energy transfer between various pRTP materials and TPA‐TD. Due to its aggregation‐induced‐emission nature, the fluorescence intensity of TPA‐TD enhances with increased doping concentration in PMMA films. Meanwhile, the transmission of TPA‐TD film reduces as the doping concentration increases, which results in a reduction of pRTP intensity through the TPA‐TD film. Therefore, the afterglow color can be fine‐tuned in situ by regulating the ratio of pRTP and fluorescence.

Sea Ice and Cloud Processes Mediating Compensation between Atmospheric and Oceanic Meridional Heat Transports across the CMIP6 Preindustrial Control Experiment

Abstract Bjerknes compensation (BJC) refers to the anticorrelation observed between atmospheric and oceanic heat transport (AHT/OHT) variability, particularly on decadal to longer time scales that may be important to the predictability of the climate system. This study investigates the spread in BJC across fully coupled simulations of phase 6 of the Coupled Model Intercomparison Project (CMIP6) and critical processes (particularly related to sea ice and clouds) that may contribute to that spread. BJC on decadal to longer time scales is confirmed across all the simulations evaluated, and it is strongest in the Northern Hemisphere (NH) between 60° and 70°N. At these latitudes, BJC appears to be primarily driven by the exchange of turbulent fluxes (sensible and latent) in the Greenland, Iceland, and Barents Seas. Metrics to break down how sea ice and clouds uniquely modify the radiative balance of the polar atmosphere during anomalous OHT events are presented. These metrics quantify the impacts of sea ice and clouds on surface and top of atmosphere (latent, sensible, longwave, and shortwave radiative) energy fluxes. Cloud responses tend to counter the clear sky impacts over the Marginal Ice Zone (MIZ). It is further shown that the degree of BJC present in a simulation at high latitudes is heavily influenced by the sensitivity of the sea ice to OHT, which is most influential over the MIZ. These results are qualitatively robust across models and explain the intermodel spread in NH BJC in the preindustrial control experiment.

Boosted photothermoelectric effect in silver nanoparticles decorated carbon nanotube films for infrared detection and actuation

Photothermoelectric (PTE) effect provides a platform for utilization both photon and thermal energy, giving rise to high-performance photodetector and radiation energy harvester. Carbon nanotube (CNT)/metal heterojunction has been demonstrated to be capable of boosting power generation based on PTE effect, and yet the responsivity and detectivity are inferior to those based on conventional optoelectronic effect. Herein, CNT films decorated by Ag nanoparticles (NPs) forming Ag/CNT heterojunctions have been investigated, showing both excellent photothermal and power conversion capability under infrared (IR) illumination. Ultrahigh ΔT of 196.4 K, maximum output voltage of 15.74 mV and power of 9.94 μW have been achieved under IR laser illumination at power density of 7.65 W/cm2, which are superior to reported photodetectors based on PTE effect. CNT@Ag NPs film possesses competitive photodetection performance as well, with responsivity and detectivity of 107 mV/W and 947.68 MHz1/2/W, respectively. Furthermore, when integrated with polydimethylsiloxane, an IR laser actuated movement function mimicking caterpillar has been realized. Our study thus expands the diverse functions of CNT-based films utilizing PTE effect toward applications in IR detection, radiation energy harvesting and soft actuation.

Thermodynamics of interaction of inulin complex with water

Currently, the key trends in the global food market include the rapidly developing functional nutrition industry, which is of great interest to consumers. Inulin is a natural polysaccharide of plant origin, consisting of residues of E-fructofuranose (fructose). The object of the research is inulin extract from Jerusalem artichoke at different humidity levels. It has been established that to intensify the drying process of inulin extract, it is advisable to increase the mass transfer surface, which can be achieved by spraying the initial product, and using volumetric energy supply methods, in particular, radiation energy supply. The important and most energy-intensive stages of drying are carried out in the hygroscopic area of equilibrium humidity of the object of the research, which determines the intensity and mechanism of the dehumidification operation in order to increase the degree of perfection, select rational operating parameters, adapt to the object of the analysis and solve a mathematical model of removal moisture from it. Based on the sorption isotherms and hygroscopic parameters of the inulin extract obtained in preliminary studies, obtained by dehydrating the inulin extract from Jerusalem artichoke (variety «Skorospelka», grown by JSC «Chaganskoe», the bAstrakhan region), a thermodynamic analysis of the process of sorption and desorption was carried out in different ranges of humidity variation. The total binding energy of moisture with the dry residue of inulin and its thermodynamic components were found. The data obtained do not contradict known literature sources and can be recommended when designing processes for removing moisture from inulin extract and designing drying devices.

Induced effects of a rigid boundary on a pulsating spherical source

This work develops a comprehensive analytical formalism to study the boundary-induced effects on a pulsating spherical radiating source near a rigid planar boundary in an inviscid fluid. Using the modal multipole expansion method, the image method and the translational addition theorem for spherical wave functions, exact closed-form expressions are derived for the dimensionless axial acoustic radiation force function as well as the radiation, amplification and extinction energy efficiency factors. The source-boundary distance and the dimensionless size parameter are especially addressed in the numerical simulations for spherical sources with different vibration modes. It is shown that the axial radiation force is positive or negative, depending on the choice of parameters. Moreover, cases when the extinction acoustic power completely vanishes are predicted theoretically for dipole and quadrupole vibrations, which can be used to achieve acoustic invisibility in acoustic cloaking devices and acoustic stealth technologies. Combination of more than one vibration modes is also investigated to better simulate the acoustic manipulation in practical applications. This work can help us understand the underlying mechanism in manipulating the active spherical radiating sources in a bounded field.

Effects of thermophoresis and Brownian motion on radiative MHD hybrid nanofluid flow over a stretching sheet with convective boundary conditions: A homotopic approach

Energy efficiency is the highest need of present times to meet the challenges of global energy demands. Nanofluids have proved to possess dynamic thermal characteristics in many experimental and theoretical studies during recent years. Nowadays, a variety of nanomaterials are accessible, and among these alloys of aluminum, AA7072 and AA7075 are important due to their unique functional characteristics. These alloys are widely used in the engineering of aircraft, spacecraft, buildings, and so on. Aiming to highlight the importance of nanofluids, this article analyses the heat and mass transfer for magnetohydrodynamic hybrid nanofluid flow on a stretching sheet of gyrotactic microorganisms. Additionally, the impacts of chemical reactions, activation energy, Peclet number, thermophoresis, Lewis number, Brownian motion, and thermal radiation are also studied. The governing equations from Partial differential equations into Ordinary differential equations are transformed with the support of resemblance transformations, and the solution is obtained with HAM techniques. The numerical findings are presented in figures and tabular form with the Mathematica program. The obtained results are explained from a physical point of view in detail. An assessment between the proposed and current model is described under specific flow parameter assumptions to validate the analysis. It is revealed that the outcomes are consistent with previous findings. The numbers of engineering importance like skin friction and heat transfer rate are explained for practical relevance. The impacts of nanoparticle loading show interesting results. It is perceived that an escalating trend is noted in the nanoparticle temperature through thermal radiation and thermophoretic parameters.

Entropy optimization and stability analysis in flow of quadratic radiative Ag−MgO/water hybrid micropolar nanofluid over an exponentially contracting permeable Riga surface

ABSTRACT Driven by the significant thermal relevance of low-conductivity electrically active fluids and their impact on controlling flows across multiple industrial and engineering domains, this study aims to thoroughly investigate the primary behavior of electro-magneto-non-Newtonian micropolar A g − M g O / H 2 O hybridized nanofluid, specifically focusing on its flow dynamics and heat transfer characteristics over an exponentially contracting porous Riga surface. The Riga surface, an exceptional electromagnetic sensor surface, holds potential applications in micro-coolers, submarines, and nuclear reactor heat management systems. These findings hold significant relevance due to the prevalent use of micropolar hybridized nanofluids in cooling minute electronic components such as microchips and associated equipment. Our innovative objective is to emphasize the influence of an electromagnetic Riga plate in conjunction with micropolar characteristics, quadratic thermal radiant energy, convective conditions, and velocity slip at the boundary on various key parameters. These parameters include the coefficient of shear stress, coefficient of couple-stress, heat transfer factor (Nusselt number), entropy generation, velocity distribution, micro-rotation or angular velocity, and temperature profiles. We successfully tackled the highly intricate coupled partial differential equations by employing numerical techniques within the MATLAB programming platform. Specifically, we utilized a fourth-order method known as bvp4c to address the challenging boundary value problem. The outcomes revealed the existence of dual solutions characterized by a stable upper solution branch and an unstable lower solution branch within the region of the contracting sheet. Notably, this observation occurred under specific conditions related to the mass suction parameter. The identification of critical values in cases with dual solutions prompted a subsequent stability analysis to discern the nature and characteristics of these solutions. Two distinct solutions have been identified for λ S < λ , reaching termination at λ = λ S within the contracting region. Notably, the first solution yields a positive minimum eigenvalue ( β 1 > 0 ), indicating its stability, while the second solution results in a nonpositive eigenvalue ( β 1 < 0 ), implying instability. Graphical representations illustrate a substantial enhancement in nanofluid temperature for both solution branches, notably influenced by the quadratic thermal radiating parameter, Eckert number, and Biot number. Moreover, the magnetic interaction number and velocity slip parameter notably affect nanofluid motion within the first solution branch. Interestingly, it has been observed that the shear stress and couple stress coefficients exhibit an upward trend with increasing suction value. However, the heat transfer factor (Nusselt number) might decrease in the case of a stable solution. This research direction aims to optimize nanofluid compositions, aiming to minimize entropy generation while maximizing desired thermal properties. Such endeavors are crucial steps towards fostering more efficient and sustainable industrial practices, aligning with the overarching objectives of enhancing energy utilization and promoting industrial growth.

Implementing the multistep adams-bashforth numerical approach on magnetohydrodynamic radiated casson fluid with darcy forchheimer, dissipation and activation energy

The main goal behind the conduction of this work is to use the Adams-Bashforth method in the field of fluid dynamics to solve the Navier–Stokes equations based on the boundary layer flow of magnetohydrodynamic Casson fluid passing on the upper horizontal parabolic surface with variable fluid characteristics and Darcy-Forchheimer effect. The temperature flow rate and mass rate are also investigated with the help of thermal radiation, viscous dissipation, heat generation and activation energy. The Adams-Bashforth technique is widely used in numerical analysis, scientific computing, fluid dynamics, chemical kinetics, astrophysics and is particularly useful in solving the stiff ODEs, where other methods may fail to converge. It is particularly useful for simulating the flow of fluids around complex geometries, such as aircraft wings or turbine blade. The equations of basic governing laws (Momentum, temperature and concentration) are achieved in the form of PDE’s. These PDEs are then transmuted into ODEs via similarity variables and the numerical behaviors of these ODEs are obtained with Adam-Bashforth (Predictor-Corrector) along with RK-4 technique on the Matlab software. The initial guesses are modified by using secant method. Graphical analyses are used to explain how different parameters affect the temperature, velocity and mass transport rate. The finding of results revealed that the inertia coefficient, Hartmann number and fluid parameter make the decrement in the velocity field. The amplification in temperature of fluid is noted for varying the radiation coefficient, dissipation and thermal generation coefficient. The solutal field drops due to activation energy and reaction coefficient. The findings are useful to observe the flow attributes, behaviors and helpful in the designing of thermal equipment in the thermal industries.