Thermal Effects Research Articles

Study on the Thermal Effect of Spontaneous Combustion of Coal-Based Activated Carbon By-Products Oxidized and Carbonized Powders

ABSTRACT To investigate the spontaneous combustion thermal effect of the by-products oxidized powder (OP) and carbonized powder (CP) produced during the preparation of coal-based activated carbon (CBAC). First, the changes in composition and pore structure of OP and CP compared with raw coal (RC) were measured by coal quality analysis and nitrogen adsorption experiments. The ability of OP and CP to physically adsorb oxygen was determined. Then, differential scanning calorimetry (DSC) was used to study the whole process thermal effect of the spontaneous combustion of OP and CP. Finally, the thermal effect of OP and CP during low-temperature oxidation process was further explored by the C80 micro-calorimeter, and the thermodynamic characteristics were also probed. The results show that the content of fixed carbon and carbon elements in OP and CP are significantly greater than that in RC, which makes the pore structure of both complicated. In addition, the total pore volume, average pore size, and specific surface area of OP and CP are greater than that of RC, which is more conducive to the physical adsorption of oxygen by both. No transition platform is caused by the decomposition of intermediate products on the DSC curve of CP. The characteristic temperatures of CP (except T D10) are lower than that of OP, indicating that the spontaneous combustion reaction of CP started earlier than that of OP. However, part of the combustible substance of CP was consumed in the dry distillation process, leading to the thermal release and maximum thermal release rate being smaller than that of OP. The apparent activation energy (E a) of stages H2 and H3 in the low-temperature oxidation process of OP is 75.04 and 11.42 kJ mol−1, while that of CP is 83.11 and 30.91 kJ mol−1. The threshold of CP entering stages H2 and H3 is higher than that of OP. Nevertheless, from the pre-exponential factor (A), the low-temperature oxidation process of CP is more rapid.

Thermal calibration for triaxial gyroscope of MEMS-IMU based on segmented systematic method

With the progress of micro electromechanical system (MEMS) technology, the performance of MEMS inertial measurement unit (IMU) composed of gyroscopes and accelerometers has been improved. Among the inertial sensors, MEMS triaxial gyroscope plays an important role in attitude estimation, navigation and positioning of intelligent mobile terminals such as unmanned aerial vehicles and unmanned vehicles. However, the measured values of low and medium cost MEMS triaxial gyroscopes are mainly affected by temperature (or thermal effect) and random errors. As results, the drift errors correlated with temperature will reduce application accuracy of MEMS triaxial gyroscope. The traditional calibration method for thermal drift errors relies on the expensive equipment, such as turntable and the temperature control system, which increases the cost of calibration. Therefore, an effective thermal calibration method that is available when using low- or high-cost tools for MEMS triaxial gyroscope will be meaningful for majority users. Hence, this paper analyzed and established the thermal drift model of MEMS triaxial gyroscope, and proposed a segmented systematic calibration method based on 24 states according to this model. Simulation shows that the proposed method can obtain the results approaching the real parameter thermal drift curves. Calibration experiments and parameters test show that the max errors of attitude calculation are reduced to 10% of the results using the original parameters, which indicates that the effectiveness of the proposed method.

On the thermal performance of a three-dimensional cross-ternary hybrid nanofluid over a wedge using a Bayesian regularization neural network approach

Abstract Significance Studying the flow of ternary nanofluids [Ag, Cu, MoS2] holds significant importance in both science and engineering. Ternary nanofluids are vital in advancing thermal management systems, heat exchangers, aerospace, and materials processing applications. Purpose This study investigates the ternary hybrid Carreau nanofluid numerically for thermal proficiency in the inclined magnetized environment. In this study, three distinct nanoparticles of [Ag, Cu, MoS2] and base fluid water over the wedge are used. The velocity of nanofluids is judged under the influence of an inclined magnetic field, and the thermal performance is scrutinized by incorporating the thermal radiation effect. Methodology The physical problem generates partial differential equations, which are transformed into ordinary differential equations (ODEs) through similarity variables. These ODEs are linearized into a system of ODEs and then passed under the bvp4c Matlab program to get the solution. This solution is again trained by an artificial neural network, and further results are obtained with both schemes and compared. Findings The most rapid heat transport analysis is found for ternary hybrid nanofluids compared to bi-hybrid nanofluids. The thermal radiation parameters and the magnetic environment augment the rate of heat transport.

Photothermal nano-confinement reactor with bimetallic sites for enhanced peroxymonosulfate activation in antibiotic degradation

In recent years, photothermal-assisted Fenton-like degradation of organic pollutants has become a prominent green method in environmental pollution control. Nevertheless, the design of suitable catalysts remains a significant challenge for this approach. Herein, zeolite-imidazolate framework-derived CoMn bimetallic nanoparticles embedded in hollow carbon nanofibers (CoMnHCF) have been developed as a photothermal nano-confinement reactor with multiple active sites to enhance reaction performance and promote peroxymonosulfate (PMS) activation. Under light irradiation, the local temperature within the porous spaces of CoMnHCF was significantly higher than the liquid temperature. The confined space concentrated heat, minimized thermal loss, and effectively utilizes this feature to activate PMS for antibiotic degradation. The results demonstrated that this system efficiently degraded various antibiotics, including tetracycline hydrochloride, levofloxacin, sulfamethoxazole, norfloxacin and chlorotetracycline. Photothermal contribution analysis revealed that thermal effects predominate in this system. Further DFT simulations explored the coordination environment of metal elements and the properties of related pollutants, predicting potential structures and reaction sites. A series of water quality experiments and cyclic tests demonstrated the system's significant application potential. This study offered new insights into advancing the integrated use of photothermal conversion and nano-confinement reactor activation of PMS in sewage purification.

Numerical Modeling of the Fluids Petroleum Flow Through the Supersonic Separator

In the context of increasing concerns regarding the amplification of the thermal effects of climate change, the Council of the European Union has proposed the reduction (up to the elimination) of the use of fossil fuels. For this purpose, the implementation of new ecological (renewable) fuels is being analyzed to reduce the carbon dioxide footprint, natural gas being the transition fuel. Also, in the next period, an increase in the demand for methane, the exploitation of condensate deposits, those with natural gas mixed with acid gases (containing hydrogen sulfide, carbon dioxide, and nitrogen), as well as oil deposits with associated natural gas, which will require their treatment (to eliminate saline or non-saline water, mechanical impurities, of condensate and acid gases). At the same time, the exploitation of offshore deposits in deep waters will be emphasized, which will lead to the location of treatment equipment on the seabed. The present work discusses the simulation of natural gas treatment processes, focusing on the separation from methane (in the supersonic field) of water, condensate, and acid gases.

Polarization self-modulation in a coaxially end-pumped orthogonally polarized laser

A scheme of orthogonally polarized laser (OPL) with polarization self-modulation (PSM) in the coaxial end-pumping configuration is proposed in this work. The gain medium consisted of two Nd:YVO4 crystals with orthogonal optical axes, and a quarter-wave plate served as a polarization-switching device. By rotating the electric vector during each cavity round trip, frequency degeneration and correlated operation of two polarization components were achieved. The polarization eigenstates in two orthogonal directions were analyzed using the Jones matrix and eigenequation. The spectral distribution was also briefly discussed based on thermal effects. The results showed that two eigenmodes located at 45° and 135° to the crystal axis, respectively, with a frequency difference equaled to half the free spectral range of the resonator. In the experiments, it was found for the first time that the modulation of eigenstates can be realized by adjusting pump parameters (including pump power, beam size, focusing position, and pump wavelength) and cavity anisotropy, which enables the manipulation of degree of polarization (DOP) and monitoring the resonator properties. Overall, tuning the laser polarization eigenstate offers a flexible method to switch the operational states of the OPL, including the longitudinal mode frequency difference, DOP, polarization angle, etc. It is believed this scheme provides a valuable reference to realize compact, high-beam-quality, and robust OPLs for applications such as dual-frequency light source development, precision measurement and polarization control.

The XRISM first-light observation: Velocity structure and thermal properties of the supernova remnant N 132D

Abstract We present an initial analysis of the X-Ray Imaging and Spectroscopy Mission (XRISM) first-light observation of the supernova remnant (SNR) N 132D in the Large Magellanic Cloud. The Resolve microcalorimeter has obtained the first high-resolution spectrum in the 1.6–10 keV band, which contains K-shell emission lines of Si, S, Ar, Ca, and Fe. We find that the Si and S lines are relatively narrow, with a broadening represented by a Gaussian-like velocity dispersion of $\sigma _v \sim 450$ km s$^{-1}$. However, the Fe He$\alpha$ lines are substantially broadened with $\sigma _v \sim 1670$ km s$^{-1}$. This broadening can be explained by a combination of the thermal Doppler effect due to the high ion temperature and the kinematic Doppler effect due to the SNR expansion. Assuming that the Fe He$\alpha$ emission originates predominantly from the supernova ejecta, we estimate the reverse shock velocity at the time when the bulk of the Fe ejecta were shock heated to be $-1000 \lesssim V_{\rm rs}$ (km s$^{-1}$) $\lesssim 3300$ (in the observer frame). We also find that Fe Ly$\alpha$ emission is redshifted with a bulk velocity of $\sim 890$ km s$^{-1}$, substantially larger than the radial velocity of the local interstellar medium surrounding N 132D. These results demonstrate that high-resolution X-ray spectroscopy is capable of providing constraints on the evolutionary stage, geometry, and velocity distribution of SNRs.

US/PA/MR multimodal imaging-guided multifunctional genetically engineered bio-targeted synergistic agent for tumor therapy

Focused ultrasound ablation surgery (FUAS) is a minimally invasive treatment option that has been utilized in various tumors. However, its clinical advancement has been hindered by issues such as low safety and efficiency, single image guidance mode, and postoperative tumor residue. To address these limitations, this study aimed to develop a novel multi-functional gas-producing engineering bacteria biological targeting cooperative system. Pulse-focused ultrasound (PFUS) could adjust the ratio of thermal effect to non-thermal effect by adjusting the duty cycle, and improve the safety and effectiveness of treatment.The genetic modification of Escherichia coli (E.coli) involved the insertion of an acoustic reporter gene to encode gas vesicles (GVs), resulting in gas-producing E.coli (GVs-E.coli) capable of targeting tumor anoxia. GVs-E.coli colonized and proliferated within the tumor while the GVs facilitated ultrasound imaging and cooperative PFUS. Additionally, multifunctional cationic polyethyleneimine (PEI)-poly (lactic-co-glycolic acid) (PLGA) nanoparticles (PEI-PLGA/EPI/PFH@Fe3O4) containing superparamagnetic iron oxide (SPIO, Fe3O4), perfluorohexane (PFH), and epirubicin (EPI) were developed. These nanoparticles offered synergistic PFUS, supplementary chemotherapy, and multimodal imaging capabilities.GVs-E.coli effectively directed the PEI-PLGA/EPI/PFH@Fe3O4 to accumulate within the tumor target area by means of electrostatic adsorption, resulting in a synergistic therapeutic impact on tumor eradication.In conclusion, GVs-E.coli-mediated multi-functional nanoparticles can synergize with PFUS and chemotherapy to effectively treat tumors, overcoming the limitations of current FUAS therapy and improving safety and efficacy. This approach presents a promising new strategy for tumor therapy.Graphical

THERMAL TREATMENT OF AGRICULTURAL WASTE AS AN ALTERNATIVE FOR PRODUCING SOLID BIOFUELS

Brazil stands out in terms of the composition of its energy matrix, with biofuels playing an important role, with many different raw materials requiring study. This article seeks to evaluate thermal treatment's effect on different biomass species to improve their energy characteristics, through an analysis of immediate chemical composition (as standardized by the American Society for Testing and Materials), spectroscopy in the infrared region, and thermogravimetry. This paper details the energy potential for each biomass, establishing the torrefaction processes with the best yield from agricultural residue of peanuts (Arachis hypogaea L.), cacao (Theobroma cacao L.), sugarcane (Saccharum spp.), coconut (Cocos nucifera L.), palm oil (Elaeis guineensis Jacq.), and papaya (Carica papaya L.). The thermal treatment of biomass proved effective in obtaining a solid biofuel with a higher heating value, as diagnosed through immediate chemical analyses.

AI Analysis of the Thermal Effects on Reinforced Concrete Buildings with Floating Columns

AI Analysis of the Thermal Effects on Reinforced Concrete Buildings with Floating Columns

Entropic uncertainty and quantum non-classicality of Unruh-Dewitt detectors in relativity

An object moving with the acceleration will change the temperature of environment around it, because of the presence of the Unruh thermal effect. In this work, we investigate the impact of Unruh thermal noise on the quantum-memory-assisted entropic uncertainty and quantum correlation regarding a pair of Unruh-Dewitt detectors. Specifically, we examine how the acceleration, the coupling strength between the external field and the detector, and the initial state affect the uncertainty and the system's quantum discord. It turns out that the Unruh effect will result in the loss of the systemic quantumness and inflation of the uncertainty. Moreover, it is revealed that the uncertainty is reversely correlated with the system's quantum discord. Thereby, it is believed that our investigations provide new insights into understanding the behavior of objects in the relativistic background.

Molten-salt-chemistry-assisted synthesis of heterostructured g-C3N4/BiOI nanocomposites with enhanced sunlight absorption properties for efficient solar-to-chemical energy conversion

The g-C3N4 nanosheets coupled BiOI (g-C3N4/BiOI) nanocomposites with unique heterojunction structure and excellent wide-spectrum sunlight absorption properties have been developed via molten-salt-chemistry-assisted strategy. The heterostructured g-C3N4/BiOI shows enhanced solar to the thermal effect, improved electron mobility and carrier lifetime for efficient photocatalytic dye degradation. The engineered g-C3N4/BiOI catalyst exhibits outstanding photocatalytic activity for methyl orange (MO) removal with 100 % degradation conversion and excellent stability under solar light irradiation, which is respectively 2.69 and 1.27 times higher than those of g-C3N4 and BiOI counterparts. The broad scope toward other dyes degraded by g-C3N4/BiOI and the generality of the molten-salt-chemistry-assisted strategy for synthesizing g-C3N4/BiOCl and g-C3N4/BiOBr with considerable photodegradation efficiency are proved. The analysis of kinetic behaviors, electron spin resonance, and nanosecond transient absorption spectra for structure-activity relationship, key intermediate of •O2− species, and excited state lifetime of g-C3N4/BiOI heterojunction material in the photocatalytic MO degradation processes are also demonstrated.

First-principle modeling of parallel-flow regenerative kilns and their optimization with genetic algorithm and gradient-based method

We present a one-dimensional first-principle model for parallel-flow regenerative kilns that accounts for the most important effects. These include the kinetics and thermal effects of the limestone decomposition as well as the heat transfer between the gaseous and solid phases. The model consists of two coupled equation systems for the upper and lower part of the kiln. The results of the model are validated qualitatively and are used to train an artificial neural network that predicts the conversion and the temperature in the crossover channel. The artificial neural network performs very well with values of the root mean squared error that are two to three orders of magnitudes lower than the range covered within the data. Finally, we use a genetic algorithm to optimize the feed mass flows such that the conversion and the fuel efficiency are improved in a Pareto-optimal manner. The results are compared to those of a gradient-based optimization method, which shows the usefulness and validity of the approach with the genetic algorithm.

Effects of thermal cycles and time-dependent behavior of the deck on steel network arch bridges

Network arches are a type of arch bridges with inclined hangers, in which some hangers cross each other at least twice. This paper aims to evaluate the effects of thermal fluctuations and volumetric changes of the concrete deck on steel network arches. Fifty-nine variants of a reference network arch bridge were developed, assuming identical arch geometries but varying hanger arrangements. Each bridge was modeled using the finite element method and subjected to heat flux due to solar radiation and changes in ambient temperature in addition to heat transfer via conduction, convection, and radiation. The time-dependent deformations of the concrete deck were implemented using a rate-type formulation. Results obtained during a one-year period after the assumed end of construction showed that stress changes in the arch bridge due to ambient and time-dependent effects were not very sensitive to the hanger layout. Neglecting concrete creep and shrinkage was found to cause a 15-20% underestimation of maximum stresses in the concrete deck, whereas a 40-60% error was observed in both the deck and rib when thermal effects were ignored. The radial arrangement of hangers, already known to perform favorably under live loads, was also found to provide the smallest bending moments and the fewest number of relaxed hangers due to thermal and time-dependent effects.

Effective thermodynamic potentials and internal variables: Particulate thermoviscoelastic composites

The problem addressed in this study is the full coupling between three different contributions to the strain in thermoviscoelastic composites, elasticity, viscosity and temperature changes. It shows that even in simple situations, the coupling with temperature may lead to counter-intuitive effects which are not accounted for through the sole overall stress–strain relations. The correspondence principle permits to express the macroscopic strain–stress relation and the macroscopic entropy as a set of ordinary differential equations for two types of effective internal variables, mechanical variables on the one hand and thermal variables on the other hand. Interpreting the macroscopic response as a rheological generalized Maxwell model allows us to compute the macroscopic free energy and the dissipated energy of the composite in terms of these internal variables. Coupled with Hashin–Shtrikman estimates, these thermodynamic functions provide additional information on the statistics of the stress field when the composite is subjected to a mixed loading combining mechanical and thermal effects.

МОДЕЛЮВАННЯ ТА ОПТИМІЗАЦІЯ РЕЖИМУ ТЕРМООБРОБКИ ТРУБЧАСТИХ ЕЛЕМЕНТІВ ФЕРМЕННИХ КОНСТРУКЦІЙ ЛІТАЛЬНИХ АПАРАТІВ З ВУГЛЕПЛАСТИКУ

The article analyzes the current state of development of dimensionally stable tubular elements (TE) and technological problems arising during their production. It is shown that along with empirical methods of studying the influence of various technological schemes on the dimensional stability of tubular elements, it is useful to use the optimal temperature-time mode for heat treatment and, based on it, select the optimal technological scheme. Modeling and determination of the optimal mode of heat treatment of tubular elements were performed. The study of the TE heat treatment mode was carried out in two stages, first by methods of mathematical modeling and optimization, and then by empirical enumeration of various technological schemes. At the first stage, the material properties, which are parameters of the mathematical model, were studied, and the optimal curing modes were calculated. At the second stage, the calculated optimal curing modes were supplemented with various technological methods that cannot be mathematically modeled, and a study was carried out on the influence of the resulting combined heat treatment mode on the geometric characteristics and dimensional stability of carbon fiber TE. The mathematical model of the process of heat treatment and curing of TE in a heat chamber, when heated by a heating air flow, is a system of differential equations: thermal conductivity and curing kinetics. A mathematical model of the process of heat treatment of tubular elements manufactured by the winding method is proposed, the ways of optimizing the curing mode of carbon fiber TE are shown. A numerical calculation of temperature-conversion fields during curing and calculation of optimal curing modes of tubular elements are performed taking into account various process schemes. The values of heat capacity C and thermal conductivity l are calculated depending on the temperature T, the degree of curing b and the filling coefficient g, Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику the power of heat release W and the thermal effect of the curing reaction Q of carbon fiber. Optimum curing modes for a plate made of composite polymer material are obtained, calculated from the data obtained as a result of studying material samples. Temperature-time curing modes are obtained, which are optimized for different thicknesses of the studied material. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the wall thickness of a tubular element and its compressive strength was proved by the dispersion analysis method. The influence of process flow charts and heat treatment modes on the geometric and mechanical characteristics of carbon fiber tubular elements of aircraft truss structures was studied. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the deviation of the wall thickness of tubular elements and their strength characteristics was tested. The significance of the influence of process flow charts with different heat treatment modes on the average wall thickness of a carbon fiber tubular element was statistically proven.

Building Energy Savings and Power Output Augmentation of Roof Mounted PV Using Co-Located Rooftop Reflectors

Abstract Photovoltaic panels (PVs) installed on building rooftops yield a positive influence on the thermal performance of the building due to the shading of the PV panels, decreasing cooling loads while causing a smaller increase in heating loads. Additionally, the electrical power output of PV panels has been shown to be increased by including reflectors between PV rows, concentrating the solar flux onto the active portion of the panels. When implemented into the spaces between the rows of a roof-mounted PV array, reflectors might further improve the positive thermal effects of rooftop installed PV arrays. This work focuses on predicting rooftop heat flux and temperature for a building rooftop equipped with PV panels and reflectors. The Saved Energy Load (SEL), Additional Energy Load (AEL), PV power output, rooftop heat flux and the utility factor (ratio of positive building energy impacts to negative building energy impacts) are reported parametrically for variations in the rooftop absorptivity and reflector area for three United States locations. Utility factors of 375, 140 and 160 are found for Phoenix, Boise and Dayton, respectively, for a reflector covering the full area between panels with a roof having a minimal absorptivity. A building in Phoenix exhibits a 15% increase in the utility factor of the PV-building system when reflectors are incorporated compared against a PV-building system without reflectors, while a building in Dayton showed a 22% increase in utility factor when reflectors are included between the rows of a roof-mounted PV array.

Temperature effects on interspecific eavesdropping in the wild

Abstract Mating signals are targets of conspecific signal recognition and sexual selection, but are also subject to abiotic temperature effects and to biotic interspecific eavesdroppers. In crickets, the male calling song becomes faster at warmer temperatures, and female crickets’ recognition of male song tracks temperature in a coordinated manner, termed ‘temperature coupling.’ But female crickets are not the only ecologically relevant listeners: some cricket species are parasitized by Ormia ochracea, a parasitoid fly which finds its cricket hosts by eavesdropping on male cricket song. How temperature affects parasitoid fly phonotaxis to song is largely unexplored, with only one previous study conducted under field conditions. Here we explore six possible patterns of thermal effects on fly responses to cricket song, including temperature coupling, using field playbacks of synthetic Gryllus lineaticeps songs designed to be species-typical at various temperatures. We find that temperature does affect fly response, but that the temperature deviation of songs from ambient does not impact numbers of flies caught. We extend this finding by comparing the temperatures of the air (where flies search for their hosts) and the ground (where their host crickets signal) to show that temperature coupling is unlikely to be effective given microhabitat variation and differential rates of cooling in the evening hours when flies are most active. Our results can be interpreted more broadly to suggest (i) temperature effects on intraspecific communication systems may be more tightly coupled than are effects on interspecific eavesdropping, and (ii) variation in thermal microhabitats in the field make it difficult to translate laboratory physiological responses to natural selection in the wild.

Exploring Urban Heat Distribution via Intra- and Extra-Block Morphologies with Integrated Stacked Models

The spatial variability of land surface temperature (LST) is considerably affected by urban morphology. Previous research has focused separately on the thermal effects of urban morphology and the cooling effects of water bodies and urban parks. However, the combined influence of intra- and extra-block factors on LST has not been thoroughly examined. To bridge this research gap, we conducted an extensive analysis of 17 urban morphology factors in Hangzhou by employing a novel stacked ensemble approach. Results showed that the stacked ensemble models outperformed commonly used techniques, such as random forest and boosted regression trees. Extra-block factors, alongside building density, average building height, and vegetation coverage within blocks, predominantly influenced the LST distribution across all seasons. Building density was positively correlated with LST, with a maximum influence of 1.5 °C in spring, whereas building height was negatively correlated with it, with a maximum influence of 1.8 °C in winter. The cooling distance of the Qiantang River extends up to 2500 m into the urban blocks and has a maximum effect of 2 °C in summer. These insights deepen our comprehension of the interplay between LST and intra- and extra-block urban morphologies, thus offering valuable guidance for urban planners and policymakers.

Effect of IR Laser Energy on Several Polymers Using LIBS Analysis

ABSTRACTThe focus of this research is to use the thermal ablation properties of a Nd:YAG infrared laser to highlight the thermal damage caused by the extinction of the plasma, which leads to the disappearance of the spectra of certain polymers as the laser energy increases. The study involved testing five commonly used polymers: polytetrafluoroethylene (PTFE) also known as Teflon, polyoxymethylene (POM), polyvinyl chloride (PVC), Bakelite, and polyamide. Laser induced breakdown spectroscopy (LIBS) analysis was used to qualitatively analyze the plasma generated from the polymer samples, identifying the excited species present in each of the five polymers. Wavelength dispersive X‐ray fluorescence (WDXRF) analysis of the polymer samples further confirmed the identification of these excited species. The results obtained from the spectra recorded at different laser energies in an air environment showed that the saturation observed in the plasma, induced by increasing laser energy, is not consistently observed for all polymers. This plasma extinction phenomenon in certain polymers is attributed to thermal effects when using an infrared (IR) laser as a heating source.