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Agricultural paper mulch is an indispensable part of modern agriculture. It had the functions of heat preservation, moisture preservation, insect resistance, disease prevention, and weed growth inhibition. In order to extend the service life of the paper mulch, we use the solution immersion method to modify the surface of the paper mulch. A super-hydrophobic paper mulch is mainly prepared by using hydrophobic silica. The static contact angle of the super-hydrophobic paper mulch with water is 160.6°. The super-hydrophobic paper mulch samples were immersed in acid solution (pH = 4.6 H2SO4) and alkaline solution (pH = 8.5 NaOH). The main instruments are contact angle tester, tensile testing machine and high-speed camera. The hydrophobic properties, mechanical properties and rebound properties of the two kinds of paper mulches were compared. The results showed that the tensile strength and droplet bounce height of the superhydrophobic paper mulch decreased after being soaked in acid or alkaline solution for 48 h. The mass loss rate of paper mulch was more significant in acid solution, but its contact angle was still greater than 145°, and it had good bounce performance. After observing the microscopic morphology of its surface, it was found that silica had a micro-rough structure on the surface of the paper mulch. The method was simple and environmentally friendly, and can alleviate the problem of poor acid and alkali corrosion resistance of the paper mulch, and had extraordinary significance for environmental protection. [ABSTRACT FROM AUTHOR]

To counter the paper flammability, Silk fibroin-Polyquaternium-10/Melamine phosphate-SiO2 (SF-JR400/MP-SiO2) based on natural silk protein may be applied to the Dongba Paper (DBP) surface using layer-by-layer assembly. The microstructure and composition of the coating may be assessed using a scanning electron microscope, fourier transform infrared spectrometer, and X-ray photoelectron spectroscopy. The presence of the coating increases the paper combustion limiting oxygen index from 20.4 to 38.0%. Compared to the untreated DBP, TGA analysis shows that the initial decomposition temperature of the 25-layer assembly rises from 115 to 148 °C, and the residual char yield increases from 11.3 to 38.8%. XPS shows that the formation of a char on the coating surface protects the internal fibers of paper from heat feedback and consequent thermal decomposition. Analysis using cone calorimeter tests (CONE) indicates that a 25-layer assembly can reduce the peak and total heat dissipation by 88.4% and 54.7%, respectively analysis suggests that silk protein may function as an agent to accelerate the coating, formation of a protective. This work provides technical implications to produce flame-retardant handmade paper. [ABSTRACT FROM AUTHOR]

In the paper, the impact of paper-mill sludge dried at 75 °C (PS) on cement hydration is being analysed. The used specimens were made of CEM I 42.5 R cement and the added PS replaced 0%, 5%, 10% and 15% by mass of cement. The results of calorimetric measurements of the mixtures and the compressive strength were analysed (W/(C + PS) = 0.35). SEM and XRD tests were carried out after 3, 14, 28 and 56 days of curing W/(C + PS) = 1. PS was found to extend the induction period of the cement hydration and delay the time of the secondary heat release effect, especially in specimens with the highest content of the PS. The total heat release (after 96 h) measurement results showed that the highest total heat evolved from specimens without the PS. The total liberated heat gradually increased with the increase in the PS content in the cement paste mixture. In the specimens with 15% of PS, the total heat release decreased by 20%, as compared to the control specimen without the additive. XRD test results revealed that the standard minerals listed below were formed in cement stone: ettringite, calcite, portlandite, and calcium aluminium silicate hydrate. SEM tests revealed significant changes in cement stone microstructure caused by the increase in the PS in cement paste. The compressive strength of specimens with PS waste was found to be considerably lower in the initial stage of hardening; however, when samples hardening time is increased up to 56 days, the difference between the values of compressive strength for specimens 5% of PS and the control specimens decreases. [ABSTRACT FROM AUTHOR]

The experimental measurement of density and enthalpy of mixture for two binary liquid mixtures of n-tridecane or n-tetradecane with decalin was reported in this paper. The measurements were conducted at a temperature range of 293.15–323.15 K and at 303.15 K using calorimeter C80. The mixtures were analyzed at various proportions, including the entire composition range and dilute solutions. The excess molar volume (VE) and excess molar enthalpy (HE) of mixtures were calculated and fitted using the Redlich–Kister equation. The paper observed the expansion phenomenon for the VE at all temperatures, including over the entire composition range and dilute solutions. Additionally, the HE exhibited endothermic behavior at the studied temperature range and composition range. The Prigogine–Flory–Patterson (PFP) theory was utilized to predict both thermodynamic properties, namely the VE and HE. The results obtained using the PFP theory were compared with those obtained using the Treszczanowicz and Benson association (TB) model for VE and with the NRTL, Wilson, and Flory models for HE. The PFP model, which employed a single-fitted parameter to describe VE, demonstrated satisfactory performance in predicting VE. Conversely, the Treszczanowicz and Benson association (TB) model yielded relatively poor results in fitting VE. However, the NRTL, Wilson, PFP, and Flory models exhibited good performance in predicting HE. [ABSTRACT FROM AUTHOR]

Paper membranes have long been used in an enthalpy exchanger. However, there has been a continuous concern on the durability or the anti-bacterial performance. In this study, heat and moisture transfer characteristics of a recently-developed PE/PA (polyethylene/polyacetate) composite membrane was investigated as a possible substitute to the paper membrane. Results showed that the diffusion coefficients of the PE/PA membrane (7.7 × 10−10 m2/s to 1.8 × 10−9 m2/s) were higher than those of the paper membrane (1.8 × 10−11 m2/s to 6.0 × 10−11 m2/s). Furthermore, the diffusion coefficient increased as relative humidity increased, reached a maximum at 50 % to 60 % and then decreased. For PE/PA membrane, the sorption constant increased as temperature increased, which was the reversed trend to the paper membrane. Successful prediction of the moisture transfer effectivenesses of the separate pseudo-counter flow enthalpy exchangers further strengthened the validity of the obtained diffusion coefficients. [ABSTRACT FROM AUTHOR]

In this paper, a new designed silicon-containing nitrogen and phosphorus flame-retardant system containing ammonium polyphosphate, modified molecular sieve and methylcellulose was used to prepare the flame-retardant corrugated cardboards (FRCCB). The samples before and after treatment were tested for combustion and thermal stability using vertical burning test (VBT), limiting oxygen index (LOI), cone calorimetric test (CCT) and thermogravimetry (TG). To further analyze the flame-retardant properties of the flame-retardant system, the microstructure, surface elements and functional groups of the materials were characterized by the scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the samples were tested to analyze the effect of flame-retardant treatment on the strength. The VBT and LOI tests showed that the samples after the flame-retardant treatment were able to self-extinguish after ignition, achieving the flame-retardant B-1 grade. The CCT tests showed that the total heat release of treated samples was reduced by 49.90%, and the total smoke production was decreased by 27.64%. TG tests showed that the thermal decomposition temperature of FRCCB decreased but the residual carbon content increased largely. FTIR tests showed that the functional group changed at different temperatures. After flame-retardant treatment, a dense carbon layer was formed on the surface of the treated sample, including N, P, Si and Cu, measured by SEM and EDS. Combining with various characterization methods, the flame-retardant system can retard flame by releasing nonflammable gases, forming covers and catalyzing char formation. [ABSTRACT FROM AUTHOR]

Coal spontaneous combustion (CSC) is one of the main disasters in the process of coal mining. In this paper, the important role of high-latent heat phase change material CH3COONa·3H2O (SAT) in controlling CSC was studied and compared with common inhibitors (NaCl, CaCl2, ascorbic acid (VC)). The thermal performance characteristics of SAT were revealed by the C80 micromanometer, and the effects of different inhibitors on the thermal behavior of Shengli lignite were analyzed and compared. Furthermore, the gas–solid coaxial fixed bed measurement system was used in conjunction with the Pfeiffer online mass spectrometer, to design the natural temperature rise experiment of coal after the heating interruption in the same programmed temperature rise interval, investigating the effects of different inhibitors on the temperature and gas production in the process of coal oxidation. The results show that the heat absorption effect of SAT is more significant than common inhibitors, which not only improves the heat absorption rate of the samples but also increases the total heat absorption of the sample by 236.6 J·g−1 compared with the raw coal. In the programmed temperature rise experiment, the maximum temperature point of the SAT-inhibited coal sample is reduced by 15.5% compared with raw coal, the time to reach the maximum temperature point is delayed by 20.5%, and the SAT inhibitor effectively inhibits the production of CO and CO2 gases. The method described in this paper provides a new idea for the prevention and control of CSC. [ABSTRACT FROM AUTHOR]

The heat dissipation capacity prediction and cooling adjustment of the space station are rarely reported and are currently very urgent. Therefore, this paper does the following work. First, a twin system equivalent to the actual thermal system is built based on the digital twin technology, and the net heat dissipation capacity that can reflect the energy storage characteristics of the radiator and the total heat that can reflect the load changes in the cabin are identified. Then, the optimum operating state of the thermal system is planned by using the changing characteristics of the two, to predict the maximum heat dissipation capacity and heat dissipation margin of the space station. Finally, the cooling adjustment method is given. The results show that the heat dissipation capacity of the shadow area of the space station is about 16kW, which is about 1.5 times the sunlit area. The series control reduces the time difference between hot and cold source from 677 s to about 77 s. The radiator absorptivity is only increased by 0.15, and its accumulated heat dissipation will be reduced by 7.48 kWh in one orbital period. The radiator emissivity decreased by 0.05, and the accumulated heat dissipation decreased by 1.6 kWh. When the solar azimuth is 20° and 160°, the heat dissipation capacity ratio of the whole module in the sunlit zone is about 0.9 of a single orbital period. It is worth mentioning that the idea of heat dissipation capacity prediction and cooling adjustment proposed in this paper has important reference significance for both fluid network and non-fluid network structures. [ABSTRACT FROM AUTHOR]

The dysregulation in heat balance, the main cause of exertional heat stroke, occurs not only in midsummer but also in the cold season. Possible causes of this are a reduction in convection and evaporation due to tailwinds and an acceleration of radiant heat inflow. Although the amount of radiant heat that reaches the surface can be estimated, the actual amount of heat that flows into the body cannot be specified yet. This paper made an experimental attempt at this. A device is made up of a temperature controllable heat sink and heat flow detector, which keeps the surface temperature constant and has a heat exchange coefficient comparable to that of the human body surface. The output of this device (total heat exchange) was divided into radiant heat exchange and other heat exchange using a standard radiant heat calibrator, Leslie cube. A phenomenon, in which a wet surface while the surface temperature was low absorbed larger heat than that of the dry surface, was found. And authors named this "hidden heat inflow". As a result of multiple regression analyses, both radiant heat exchange and other heat exchanges are closely related to the surface temperature, and the maximum difference in total heat exchange during the experiment reached 200 kcal/m2/h. It has been suggested that this phenomenon may also occur on the surface of human skin. One of the causes of this "hidden heat inflow" is considered to be the decrease in evaporative cooling due to the decrease in surface temperature. However, this alone cannot explain all of the phenomena, so water vapor aggregation may also be involved. A "hidden heat inflow" as a sufficient heat source for exertional heat stroke or collapse during a marathon race on a cold day was evidenced experimentally. [ABSTRACT FROM AUTHOR]

This paper is focused on the evolution of the vertical temperature profile of spilled plume originated from a compartment-facade fire under the conditions of different horizontal projection lengths. A series of reduced scale experiments were carried out in a 1:8 cubic fire compartment model with a single window at the center of the compartment's side wall. A vertical facade wall was attached to the compartment window, and a horizontal projection was installed at the level of window's top as the representative of a fire protection cornice in a real building. In the experiments, by varying the length of horizontal projection, the total heat release rate as well as the window sizes, the vertical temperature recorded by a series of thermocouples along the centerline of facade wall was analyzed. Results showed that, with the presence of horizontal projection, especially for a longer projection, the temperature of the spilled plume was reduced significantly, which is beneficial to fire protection in high-rise buildings. Meanwhile, two different regions were observed due to the flame retrieving effect to the facade wall, and therefore, the temperature would first increase and then decrease in the vertical direction, which is completely different from the results obtained without the horizontal projections. A critical vertical height with the highest temperature was discovered, and regarded as the new reference point. On this basis, a new normalized vertical height based upon the reference point and a new virtual origin were brought up. Finally, new correlations of vertical temperature with the updated normalized vertical height were proposed within the buoyancy plume region. This is a novel investigation for the spilled flow dynamics from a compartment-facade fire with horizontal projection conditions, and has great significance for improving the fire-fighting capabilities for a building in practice. For a compartment-facade fire, two new regions with a low temperature zone are newly discovered at the presence of horizontal projection, and new correlations of vertical temperature decay are discussed. [ABSTRACT FROM AUTHOR]

Measuring flame lengths and areas from turbulent flame flares developing from lithium-ion battery failures is complex due to the varying directions of the flares, the thin flame zone, the spatially and temporally rapid changes of the thermal runaway event, as well as the hazardous nature of the event. This paper reports a novel methodology for measuring heat release rate from flame flares resulting from thermal runaway of electric vehicle lithium-ion modules comprising eight 56.3Ah lithium nickel manganese cobalt (NMC) pouch cells using digital cameras and a newly developed numerical code to process the distortion of the flame size based on distance, direction, and shape. The model is tested with a set of experiments using lithium-ion battery packs and validated with a reference set of measurements using calibration boxes, a method commonly used in the reconstruction of flame areas. The experiments showed that the effect of calibration is large, and thus digital imaging without the appropriate calibration can give very large errors in measurement of flames. The combined imaging and processing method proposed in this work allows the determination of heat release rates from lithium-ion battery packs, one of the most challenging variables to quantify during the failure of a battery pack outside the laboratory. In the example experiment that this method was applied to, almost double the heat released was accounted for, meaning 50% of the total heat released would not have been accounted for without this image processing method. [ABSTRACT FROM AUTHOR]

In gas-insulated equipment, the decomposition of SF6 is closely related to the residual traces of O2 and H2O in the equipment. However, the decomposition mechanism has not yet been clarified. In this paper, the adsorption and defluorination of SF6 on the preadsorbed Cu(111) surface were calculated based on density flooding theory and transition state theory. Besides, the influence mechanism of O atoms and H2O molecules on the defluorination process is analyzed by comparing the energy barrier, reaction heat, and density of states. The results show that pre-adsorption of O atoms changes the adsorption sites of SFx, but has no significant effect on the adsorption energy. In addition, the O atom has a certain inhibitory effect on the decomposition process, and SF → S + F is the key to determining the reaction rate. In contrast, H2O will not only promote the adsorption of SFx to the surface but also reduce the total reaction heat of the decomposition reaction by 135.37 kcal·mol−1, driving the decomposition process of SF6. In this paper, stable co-adsorption configurations of low-fluorosulfide and co-adsorption groups were determined, and the effects of O and H2O preadsorption on SF6/Cu gas–solid interactions were initially revealed. [ABSTRACT FROM AUTHOR]

This paper introduces a novel hybrid material, MoS2@Ag@PA, with a core–shell structure aimed at improving the fire safety and critical properties of ethylene vinyl acetate (EVA). The incorporation of 2% of this hybrid material results in a remarkable enhancement in both thermal conductivity and tensile strength of EVA composites, increasing by 52.4% and 22.6%, respectively. Furthermore, the inclusion of 2% of this material leads to a significant reduction in the peak of heat release rate, total heat release, and total smoke production of the EVA composites by 36.2%, 28.1%, and 29.7%, respectively, compared to pure EVA. This indicates a substantial improvement in fire safety, mechanical properties, and thermal conductivity of the EVA composites. The enhanced flame retardancy of the EVA composites is primarily attributed to the synergistic effect of various substances within the hybrid material. Therefore, the design of these hybrids presents a promising approach to enhance the overall performance of EVA. [ABSTRACT FROM AUTHOR]

In this paper, a GaAs quantum wire is considered with a semi-parabolic lateral confinement potential in the presence of a crossed electromagnetic field with the inclusion of Rashba SOI. The effects of pressure on thermodynamic properties have been studied. To this end, first, the eigenenergies for the system have been calculated considering Rashba spin effects under electric and magnetic fields. Then a numerical analysis is done to derive the partition function and obtain the system's thermodynamic properties. The results show that at low temperatures, all four thermodynamic properties don't show much effect due to pressure. It is found that entropy increases with increasing hydrostatic pressure, whereas pressure affects mean energy and free energy in a different manner. A peak structure is observed in specific heat as a function of temperature where the peak position depends on hydrostatic pressure. [ABSTRACT FROM AUTHOR]

This paper reports formation enthalpies of phases in the Al–Mn–Pd ternary alloy system as calculated from first principles using electronic density functional theory. We consider all crystal structures as reported in the assessed phase diagrams of the ternary and its binary alloy subsystems (Al–Mn, Al–Pd, and Mn–Pd), as well as additional reported or hypothetical structures. Icosahedral and decagonal quasicrystalline approximants are among the structures that we predict to be stable, or nearly so. Our results suggest the need for careful experimental reexamination of phase stability in each of the alloy systems, in tandem with further efforts to refine crystallographic and ab-initio structures. [ABSTRACT FROM AUTHOR]

This paper employs the inclusion-based boundary element method (iBEM) to delve into heat transfer phenomena in composites. Initially, we integrate the heat flow function and ellipsoidal integral into a bounded domain containing multiple ellipsoidal inhomogeneities. The eigen-temperature gradient is utilized to simulate the thermal mismatch between inhomogeneities and the matrix. Subsequently, the temperature field is computed considering boundary heat flux and temperature conditions, eigen-temperature gradient, and virtual heat source acting on inhomogeneities. The eigen-temperature gradient and virtual heat source are then solved using the equivalent heat flow conditions to obtain the steady-state heat conduction results within the bounded domain. Through comprehensive numerical examples, we analyze the temperature distribution within composite and scrutinize the impact of particle shapes, orientations, volume fractions, and thermal conductivity ratios on the effective thermal conductivity of composite. Furthermore, we explore the distinctive properties of functional gradient material. Additionally, a comparison between iBEM and the finite element method is conducted. The findings reveal a progressive enhancement in the thermal conductivity of composite as the particle shape transitions from spherical to fibrous. [ABSTRACT FROM AUTHOR]

High quantum efficiency (QE) X-ray absorbers are needed for future X-ray astrophysics telescopes. The Advanced Telescope for High ENergy Astrophysics (ATHENA) mission requirements for the X-ray Integral Field Unit (X-IFU) instrument dictate, at their most stringent, that the absorber achieve vertical QE > 90.6% at 7 keV and low total heat capacity, 0.731 pJ/K. The absorber we have designed is 313 µm square composed of 1.05 μm Au and 5.51 μm electroplated Bi films (Barret et al. in Exp Astron 55:373–426, 2023). Overhanging the TES, the absorber is mechanically supported by 6 small legs whose 5 μm diameter is tuned to the target thermal conductance for the device. Further requirements for the absorber for X-IFU include a > 40% reflectance at wavelengths from 1 to 20 μm to reduce shot noise from infrared radiation from higher temperature stages in the cryostat. We meet this requirement by capping our absorbers with an evaporated Ti/Au thin film. Additionally, narrow gaps between absorbers are required for high fill fraction, as well as low levels of fine particulate remaining on the substrate and zero shorts between absorbers that may cause thermal crosstalk. The Light Element Mapper (LEM) is an X-ray probe concept optimized to explore the soft X-ray emission from 0.2 to 2.0 keV. These pixels for LEM require high residual resistance ratio (RRR) thin 0.5 µm Au absorbers to thermalize uniformly and narrow < 2 μm gaps between pixels for high areal fill fraction. This paper reports upon technology developments required to successfully yield arrays of pixels for both mission concepts and presents first testing results of devices with these new absorber recipes. [ABSTRACT FROM AUTHOR]

In this paper, isothermal thermogravimetric experiments were carried out on eight imidazolium-based ionic liquids. Their vapor pressure was determined using Langmuir equation, and their vapor pressure changed with temperature was discussed. It was found that their vapor pressure increased exponentially with temperature. Then, the evaporation enthalpy (Δ l g H m θ (T av)) at average temperature (T av) of eight imidazolium-based ionic liquids was determined by combining Langmuir equation and Clausius–Clapeyron equation. For comparison purposes, we converted the evaporation enthalpy (Δ l g H m θ (T av)) to the evaporation enthalpy ( Δ l g H m θ (298.15) ) at ambient temperature (298.15 K), and discussed the differences in evaporation enthalpy of them and the possible reasons for these differences. Finally, the polarity of eight imidazolium-based ionic liquids was discussed using polarity scale (δ μ) and polarity coefficient (P), and the universal applicability of the polarity coefficient (P) in ionic liquids and molecular liquids was demonstrated. [ABSTRACT FROM AUTHOR]

A molecular dynamics-based model of semi-solid formation from liquid melt of the novel Al–15Mg2Si–4.5Si composite is reported in the present study. Growth kinetics of Mg2Si phase is studied here at the pre-nucleation stage i.e., prior to the emergence of a stable nucleus. Moreover, insight has been grabbed on semi-solid processing of the said composite at atomic level, wherein the dynamic evolution of the Mg–Si clusters has been studied during cooling/semi solid slurry generation as well as during isothermal holding stage. The effect of variation of cooling rate on the number of clusters, average size of clusters and density of clusters has been investigated. The average size of clusters decays exponentially with cooling rate, whereas the average atomic density of clusters decays following a power-law relation with cooling rate. The change of the thermodynamic parameters (enthalpy and potential energy) during the phase transformation from liquid to semi-solid state are determined here, which are then employed to determine the value of interfacial free energy of Mg2Si-melt interface in the Al–15Mg2Si–4.5Si composite, along with the parameters obtained from the dynamic evolution of Mg-Si clusters. The paper also reports the temporal evolution of solid content within the melt, corresponding to the Mg2Si phase, during slurry generation as well as during isothermal holding stage. [ABSTRACT FROM AUTHOR]

This is a global ocean climatological dataset of 17 thermohaline parameters such as isothermal layer (ITL) depth (hT), mixed layer (ML) depth (hD), thermocline gradient (GT), pycnocline gradient (GD) determined from temperature (T) and salinity (S) profiles of the National Centers for Environmental Information (NCEI) world ocean atlas 2018 (WOA18) using the double gradient method along with the identity-index (i-index) showing the quality of the determination. With the identified (hT, hD) and (GT, GD), other parameters such as ITL heat content (HITL), mixed layer fresh-water content (FML), maximum thermocline gradient (GTmax), thermocline depth (hth), temperature at thermocline depth (Tth), maximum density gradient GDmax), pycnocline depth (hpyc), density at pycnocline depth (ρpyc), and (hT − hD) (barrier layer if positive or compensated layer if negative). The dataset is located at the NOAA/NCEI website (https://doi.org/10.25921/j3v2-jy50). It provides useful background information for ocean mixed layer dynamics, air-sea interaction, climatological studies. This paper is the only document for the dataset. [ABSTRACT FROM AUTHOR]

From the perspective of thermal-mass coupled transfer capacity, the enthalpy entransy dissipation number was proposed in this paper. Analytical models of liquid dehumidifier/regenerator based on enthalpy dissipation numbers were established and validated by comparing with numerical models and experiments, respectively. Finally, the analytical model was applied to a hybrid connection two-stage liquid dehumidification fresh air (HTLDFA) system by analyzing the effects of enthalpy entransy dissipation numbers and specific heat capacity ratio of the main components on the system performance. Study results of applying in the HTLDFA system show reducing enthalpy entransy dissipation number of each component of that system may decrease the temperature and moisture content of the supply air as well as increase the energy efficiency ratio. The enthalpy entransy dissipation numbers of the dehumidifier Deh Ι, the regenerator Reg Ι and the cooling tower CT Ι of the HTLDFA system have more significant effects on the system. The C*DehIII has the most significant effect on the results on the system performance. The enthalpy entransy dissipation number can be well used for evaluating irreversible loss analysis of liquid dehumidification/regeneration and the optimized HTLDFA system by applying the analytical method provides an effective reference for its industrial application. [ABSTRACT FROM AUTHOR]

Solution precursor plasma-sprayed (SPPS) yttrium aluminum garnet (YAG) thermal barrier coatings (TBCs) have previously been shown to have higher temperature capability and reduced thermal conductivity compared to state-of-the- art TBCs. This previous work was conducted using a relatively low enthalpy plasma gun (Metco 9 MB) and TBCs were deposited on laboratory specimens. The primary goal of this work was to advance the state of technology readiness of SPPS YAG TBC coatings by using a high enthalpy cascaded arc gun (Sinplex Pro) to produce varied microstructures optimized for specific engine components: a fuel nozzle tip, an annular combustor liner, and turbine ceramic outer air seals. The microstructure and properties of these TBCs have been characterized and shown to be superior to those obtained previously. Based on these favorable results, the processing technology was transferred to solar turbines incorporated. Their process optimization of coatings for the three engine components and the rig and engine testing of the coated components will be described in Part II of this paper. [ABSTRACT FROM AUTHOR]

AA6101 Al alloy is widely used as a high-strength conductive aluminum alloy, and the contents and existence of Mg and Si can influence its electrical conductivity and mechanical properties obviously. In this paper, experiments were conducted to find the optimal Mg, Si additions and Mg/Si ratio and then combined with heat treatment to improve the EC and mechanical properties at the same time. Firstly, considering the proper Mg/Si ratio, two optimal Mg and Si additions were determined: Al–0.7Mg–0.5Si and Al–0.4Mg–0.7Si with EC of 51.5%IACS and 51.4%IACS, and through homogenization treatment, their EC improved to 57.0%IACS and 55.7%IACS, respectively. Then, appropriate Fe was added to further control Si to achieve the balance of EC and mechanical properties. Results showed that for AA6101 Al alloy the ideal Mg/Si mass ratio was 1.4 and high Mg and low Si can obtain good EC and mechanical properties. Besides, it can be found that at low Mg/Si ratio, the alloy conductivity takes longer to reach its peak hardness. So the best performance Al–0.7Mg–0.5Si–0.2Fe alloy was obtained within the range of AA6101 national standard. The EC of Al–0.7Mg–0.5Si–0.2Fe can reach 56.3%IACS, and hardness is 91.3 Hv. Based on the study, a schematic diagram was drawn to analyze the influence mechanisms of Mg, Si and Fe on EC and hardness of AA6101 Al alloy. [ABSTRACT FROM AUTHOR]

This paper shows a novel approach and a new model to find the relation of formulas between the thermodynamic parameters and electromagnetic parameters, directly and indirectly. Effectiveness of formulas is discussed by considering issues: no thermoregulation process (including body metabolism), no heat transfer consideration, and the Heating loss has not occurred and boundary conditions in a closed system. The enthalpy, internal energy, and Gibbs free energy are perfect indicators for describing bio-reaction in the human body. Because they are state functions (they are independent of intermediate steps, just first and final steps), they are affected by the SAR estimation that represents the absorption power throughout human tissue. These formulas brought in many features to control body reactions or Krebs cycle. Moreover, the derived formulas convert the reaction from non-spontaneous to spontaneous form by converting Gibbs free energy to a negative value. According to findings, the model can be applied in across many disciplines, such as medical treatment, lipid decomposition, cancer healing, and physical therapy. And in the end, as a result of an increase in the concentration of electromagnetic waves in the atmosphere due to technological development, which urges urgently to amend and update all equations to take into account the effect of magnetic waves in all disciplines affected by them. [ABSTRACT FROM AUTHOR]

With its high thermal conductivity and excellent compliance with the requirements, lead-based babbitt is commonly used by manufacturers in structures to be subject to shock loading. Since some lead-based babbitt products have a uniform grain structure, they can be used under heavy loads at low constant rates. Lead-based babbitt is a low-cost alloy; therefore, it can be used for general-purpose machines, line shafting, and machine shops. It can also be used in farm machinery, cement equipment, conveyors, elevators, and metallurgical equipment. One of the most important physical properties of lead babbitt is heat capacity. The paper presents results of studying the temperature dependence of the specific heat capacity and changes in the thermodynamic functions of BLi lead babbitt (PbSb15Sn10Li) doped with lithium in the "cooling" mode in the range of 298.15 to 550 K. For this purpose, the curves of cooling rates of BLi babbitt test samples and a reference sample (lead of grade C00) were processed to derive polynomials that describe their cooling rates. Further, the experimental cooling rates and masses of the reference and test samples were used to establish the temperature dependence of the heat capacity of the alloys and the reference material, which is described by a four-term equation. Integrating the specific heat capacity led to polynomials describing the temperature dependence of changes in the enthalpy, entropy, and Gibbs energy of the alloys. The relationships obtained show that with increasing temperature and lithium concentration, the heat capacity, enthalpy, and entropy of the alloys increase, while the Gibbs energy decreases. [ABSTRACT FROM AUTHOR]

The well posedness of the two-phase Stefan problem with convection is established in L 1 . First we consider the case with a singular enthalpy and we fix the convection velocity. In the second part of the paper we study the case of a smoothed enthalpy, but the convection velocity is the solution to a Navier-Stokes equation. In the last section we give some numerical illustrations of a physical case simulated using the models studied in the paper. [ABSTRACT FROM AUTHOR]

We study and classify smooth bounded domains in an analytic Riemannian manifold which are critical for the heat content at all times t > 0 . We do that by first computing the first variation of the heat content, and then showing that Ω is critical if and only if it has the so-called constant flow property, so that we can use a previous classification result established in [33] and [34]. The outcome is that Ω is critical for the heat content at time t, for all t > 0 , if and only if Ω admits an isoparametric foliation, that is, a foliation whose leaves are all parallel to the boundary and have constant mean curvature. Then, we consider the sequence of functionals given by the exit-time moments T 1 (Ω) , T 2 (Ω) , ⋯ , which generalize the torsional rigidity T 1 . We prove that Ω is critical for all T k if and only if Ω is critical for the heat content at every time t, and then we get a classification as well. The main purpose of the paper is to understand the variational properties of general isoparametric foliations and their role in PDE's theory; in some respects they generalize the properties of the foliation of R n by Euclidean spheres. [ABSTRACT FROM AUTHOR]

There is a poor blocking effect of the paper diaphragm used in the transportation package of lithium-ion batteries. Hence, researches on barrier materials are necessary. In this study, the thermal runaway (TR) was triggered by a heating rod and propagated horizontally between battery packs, and the tests were conducted in a self-designed chamber to investigate the blocking effect of aerogel felt thickness on the TR propagation of 18,650 lithium-ion batteries with 30% SOC and 100% SOC. And a simplified model of TR propagation was established to illustrate the heat propagation between batteries. The results showed that when the barrier thickness of aerogel felt increased from 1 to 10 mm, the number of batteries with TR decreased, the total heat release rate (THR) triggering time was longer, and the blocking effect of TR propagation was better. Besides, the aerogel felt the thickness of 1 mm had a poor effect on the prevention and control of TR, and there was a threshold between the barrier thickness of 6 mm and 10 mm to prevent TR. Simultaneously, there was a slight fluctuation in the parameters of heat release rate (HRR), battery surface temperature, and peak concentrations of CO and CO2. And the concentrations of O2, CO2, and CO are related to the SOC and the number of TR of lithium-ion batteries. When the thickness of aerogel felt increased to a certain value, the difference between mass loss and the force effect produced by TR will be smaller, and the THR will be more. These results provide valuable proposals and inspiration for packaging in civil aviation transportation. [ABSTRACT FROM AUTHOR]

Despite the importance of variation in depletion index, nothing is known on the changes in the Optimized Exergy Depletion Index (XDI) with cost (USD) and Entransy Depletion Index (NDI) with cost (USD). The aim of this paper is to stablish a new depletion index based on entransy and to applicate this concept to the evaluation of efficiency and sustainability. The efficiency and sustainability of a thermal system can be evaluated through the Depletion Index. It was developed a new mathematical expression for assessing the depletion index based on entransy and it was compared with the conventional index based on exergy. Deductive inductive methods were used to obtain the new depletion index based on entransy theory. A multi-objective optimization is proposed considering as criteria the cost and efficiency based on exergy and entransy. Depletion index values based on entransy dissipation are similar than those ones based on exergy destruction and then the value of efficiency obtained by the two concepts is similar. Until recently, the generation of entropy was used for the Shell and tube heat exchangers optimization, however, the entransy dissipation or some function involving it can also be used for this purpose, being a new approach for assessing the depletion index. The optimization results obtained based on each of the efficiency indices were very similar mainly in relation to the total heat exchange rate. The Pareto fronts obtained in the multi-objective optimization allow to find and match optimum designs adjustable to costs and to the space available to install the equipment and the auxiliary services. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (XPS) is an important building exterior wall insulation material at present, and the investigation of fire behavior characteristics is an important way to solve the fire safety problem of XPS. In this study, the influence of low oxygen conditions and external radiation source on smoke and heat release characteristics of XPS are compared and investigated, and the fire spread characteristics of XPS under low oxygen conditions are also studied by investigating the characteristic parameters such as flame height, width, flame spread index and spread rate. The results indicate that the pyrolysis combustion of XPS is inhibited with the decreased oxygen concentration in the environment, resulting in reduced the ignition time and increased Smoke Produce Rate (SPR) peak. Moreover, the low oxygen condition has little effect on the heat release peak and total heat release of normal ignited materials due to the stable heat radiation source, but the heat release peak and total heat release is reduced greatly in the fire spread experiment. At the same time, there is a positive correlation between the heat release rate and the flame propagation index (FPI) under low oxygen conditions. This paper provides important data and theoretical support for the design and fire theory research of XPS. [ABSTRACT FROM AUTHOR]

This paper describes a procedure to precisely decouple the electrostatic and the nonelectrostatic contributions to the water activity of an electrolyte solution, using the partial molal enthalpy of water in the electrolyte solution. This work is an extension of our previous work [Sahu et al. in Fluid Phase Equil. 460:57–68, 2018, Data in Brief 19:485–494, 2018], where a methodology to segregate the electrostatic and non-electrostatic contributions to the water activity was discussed and the constancy of the electrostatic contribution to the water activity was shown. However, in this paper, it is a noticeable point that even a 2% variation in the electrostatic contribution to the water activity leads to a very large deviation in the electrostatic contributions to the partial molal enthalpy of water. Therefore, due to the high sensitivity of the enthalpy to the variation of the water activity, the partial molal enthalpy of water is used for refinement of the method of partitioning the water activity into electrostatic and nonelectrostatic contributions and to provide the physical interpretation of the electrostatic and nonelectrostatic contribution to the partial molal enthalpy of water. This paper also describes the procedure to estimate the partial molal enthalpy of water from the water activity of the electrolyte solution. Microcalorimetr has been used to estimate the closed spaced points of partial molal enthalpies. [ABSTRACT FROM AUTHOR]

Context: The reactions of radicals with O2 play the important role in the biological, medicinal, and industrial processes. The mechanism of this reaction is studied previously for the alkane, alkene, alkyne, phenols, and close-related radicals. According to these studies, the formation of intermediates in these reactions is predicted only for the aromatic radicals. Thus, the Van der Waals complexes of O2 with phenyl or benzyl radicals are predicted, as well as the π-π cluster for benzene. However, the possibility of the formation of such intermediate π-π clusters in the case of bisphenol radicals and the thermochemistry of its formation is not studied. Bisphenols are one of the main components of bio-oil, produced during pyrolysis of lignin-contained biomass. Synthetic bisphenols are used in polycarbonate plastics, epoxy resins, and thermal papers. Their mechanism of oxidation is important for the determination of fire safety of these materials, the possibility of using them as additives for fuels for the decreasing and the description of the ignition delays, as well as for the determination of its health risk assessment in medicine. Methods: The five DFT (M06-2X (i = 1), B3LYP (i = 2), wB97XD (i = 3), M08HX (i = 4), MN15 (i = 5)) approaches with 6–311 + + G(d,p) basis set are used for the determination of standard enthalpies of atomization (ΔraHo(Yi)) of considered compounds (molecules, radicals, and transition states). These values of ΔraHo(Yi) are corrected using the empirical linear calibration dependencies, reported previously. The different calibration dependencies are used for the hydrocarbons (including the aromatics and simple oxygenated derivatives) and for the peroxides. The corrected values of ΔraHo(Yi, CORR) are used according to Hess’s law for the determination of ΔfHo(Yi, CORR). The most consistent values of ΔfHo(Y, MEAN) are derived from the coordination of the values of ΔfHo(Yi, CORR) using the intersection of their values of standard deviations (3SDi). These values of ΔfHo(Y, MEAN), as well as the B3LYP values of So(Y), which are accounting the frequency correction and internal rotations, as well as their temperature dependencies, are used for the determination of thermochemistry of considered reactions and of the calculation, within transition state theory (TST), of the values of high-pressure limits of the rate constant. The values of Ho(Yi), So(Yi), and Go(Yi) are calculated using the Gaussian 16w program. The temperature dependencies of thermochemical properties and the values of rate constants are determined using the ChemRate program (v.1.5). The optimized structures are visualized using the Chemcraft. [ABSTRACT FROM AUTHOR]

Legendre transformation is a highly important topic in the study of thermodynamics. In this paper, the idea of Legendre transformation is discussed in a simple manner, and the interconnections between thermodynamic potentials are shown using Legendre transformation. Not only common potentials—internal energy, Helmholtz free energy, Gibbs potential, and enthalpy—a few uncommon potentials of various thermodynamic systems are also discussed. [ABSTRACT FROM AUTHOR]

This three-part paper lends new insight into the interpretation of internal state variable (ISV) theory and fundamentals of the behavior of thermally activated dislocation ensembles. We formally define important physical concepts undergirding ISV theory such as configurational subsystems (e.g., individual grains or phases), constrained local equilibrium, and thermally activated dislocation reactions in the context of crystal plasticity and then implement these concepts within a nonequilibrium statistical thermodynamics framework. The primal importance of the Gibbs free energy barrier to dislocation reactions within each subsystem is emphasized since the enthalpy barriers are affected by local constraint and resulting long-range and short-range athermal internal stresses acting within subsystems. Kinetic and kinematic aspects of individual dislocation reactions are defined. The role of athermal internal stresses in stabilizing the positions of dislocations between barriers is acknowledged by the formal identification of the anelastic deformation, along with its role in contributing to thermal dissipation. Thermal and configurational intrinsic entropy change that contribute to the change of Gibbs free energy as a driving force for reactions are formally introduced in the same way as in first principles methods and are based on probability of pending dislocation reactions at each step. We distinguish equilibrium thermodynamics up to the saddle point of reactions, for which change of both configurational and thermal entropy applies, from post-saddle point extended glide of dislocations, which couples with the thermal bath via dispersive phonon dynamics. We write subsystem and ensemble relations for intrinsic entropy production. The concept of "degree-of-correlation" of the enthalpy barriers of thermally activated dislocation processes is introduced at both the subsystem level and across the overall ensemble of subsystems, based on the ratio of the weighted average enthalpy barrier to the maximum (rate-limiting) enthalpy barrier. It is argued that nonequilibrium trajectories progressively move toward correlated behavior of the ensemble by virtue of internal stress redistribution among interacting subsystems that are favorable and unfavorable to reactions. The degree-of-correlation is a many-body concept involving populations of dislocations within and among various configurational subsystems. [ABSTRACT FROM AUTHOR]

The paper presents a formulation for simultaneous optimization of part and support in additive manufacturing. A pseudo heat conduction problem is solved to simulate heat transfer between the part and support. In the pseudo problem, a surface slope-dependent heat flux is applied on the part/support interfaces. The input heat is then transferred through the part and support to the build plate, which is treated as the heat sink. Since the density-based topology optimization does not involve explicit surface representation, the heat flux is implicitly imposed through a domain integration of a Heaviside projected density gradient. The proposed formulation has the inherent ability to control surface slope, which allows us to obtain self-supported enclosed voids and put removable external supports only on the open surfaces. Self-supporting supports can also be obtained by controlling the anisotropic thermal conductivity of the supports. Three different objective functions related to heat dissipation efficiency of the support are investigated. Both 2D and 3D numerical examples are presented to demonstrate the validity and efficiency of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper described the thermal decomposition and determined the thermodynamics and kinetics for pyrolysis of soybean de-oiled cake (soya DOC). Authors analysed the physicochemical characteristics of biomass based on proximate, elemental, lignocellulosic balance, calorific value, and FTIR results. The thermogravimetric data of soya DOC were obtained at 10, 20, and 30 °C min‒1 heating rates in an inert system. Thermal analysis of soya DOC reveals that the significant mass loss occurred between 200 and 550 °C temperature ranges. The kinetic parameters (activation energy and pre-exponential factor) and thermodynamic parameters (changes in enthalpy, entropy and Gibb's free energy) were examined by Kissinger, KAS, OFW, and CR methods. Kissinger method gives Ea 121.05 kJ mol‒1, while OFW and KAS give 162.33 and 151.88 kJ mol‒1, respectively. Results reveal that the Ea depends on decomposition. For soya DOC, the pre-exponential factor is found between 4.12 × 1012 and 6.39 × 1013 min−1, and this range depends on heating rates and conversion. In order to assess the importance of the soya DOC as a pyrolysis feedstock, the activation energy of soya DOC is also compared with the other biomass and the results are found satisfactory. Simulation of soya DOC pyrolysis using data obtained from TGA analysis showed good agreement with experimental data. [ABSTRACT FROM AUTHOR]

A van der Waals (vdW) heterostructure, can be used in efficient heat management, due to its promising anisotropic thermal transport feature, with high heat conductance in one direction and low conductance in the rest. A carbon nanotube (CNT) bundle, can be used as one of the most feasible vdW heterostructures in a wide range of nanoscale devices. However, detailed investigations of heat transport in CNT bundles are still lacking. In this paper, we study heat transport in different CNT bundles—homogeneous bundles consisting of the one CNT radius (curvature) and inhomogeneous bundles constructed from different CNTs with different curvatures. We also investigate the comparison between two possible thermostatting configurations: the two ends connected (TEC) case in which there is at least a direct covalently connected path between the hot and cold heat baths, and the one end connected (OEC) case in which the system can be divided at least into two parts, by a vdW interacting interface. Nonequilibrium molecular dynamics simulations have been carried out for a wide range of configurations and curvature differences. We find that, in homogeneous bundles, by increasing the number of outer CNTs, the heat conductance increases. In inhomogeneous bundles, the total heat flux shows dependence on the difference between the curvature of the core and outer CNTs. The less the difference between the curvature of the core and the outer CNTs, the more the thermal conductance in the system. By investigating the spectral heat conductance (SHC) in the system, we found that a larger curvature difference between the core and outer CNTs leads to a considerable decrease in the contribution of 0–10 THz phonons in the bundled zone. These results provide an insightful understanding of the heat transport mechanism in vdW nano-heterostructures, more important for designing nanoelectronic devices as well as systems in which asymmetry plays a significant role. [ABSTRACT FROM AUTHOR]

Accurately grasping the decomposition path of SF6 on the surface of typical metals and metal oxides is the key to reveal the decomposition mechanism of overheating fault. In this paper, the decomposition paths of SF6 on Cu and its oxides are theoretically analyzed by combining density functional theory and transition state theory. The results show that the participation of Cu surface reduces the energy required for the initial decomposition of SF6 by about 98.70 kcal/mol compared to that in free space. The decomposition reaction of SF5 on the Cu surface is energy barrier free, thus SF5 cannot stably exist in SF6 over-thermal decomposition system. Further, it was found that when Cu was oxidized at high temperature, reactions between SF6 and metal surface would be more intense. At this time, the total reaction heat of SF6 completely decomposed into S was -220.07 kcal/mol, significantly lower than -100.60 kcal/mol on Cu surface. This illustrates the catalytic effect of Cu and its oxides. On the surface of CuO, the interaction of O and F atoms may be the main reason to further reduce the activation energy. This article explained the over-thermal decomposition process of SF6 from microscopic level, laying a theoretical foundation for further study on the influence of the over-thermal decomposition of SF6-metal system. [ABSTRACT FROM AUTHOR]

In this paper we present a necessary and sufficient condition to guarantee that the zero-extended function of the solution for the heat equation in a smaller cylinder is still the solution of the corresponding extension problem in a larger cylinder. We prove the results under the frameworks of classical solutions, strong solutions and weak solutions. Moreover, we generalize these results to uniformly parabolic equations of divergence form. [ABSTRACT FROM AUTHOR]

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The stabilities, mechanical and electronic properties and Debye temperature of three novel Cr2C structures (Pnnm, Amm2 and P-31m space groups) are investigated and discussed in this paper. All of them are thermodynamically, mechanically and dynamically stable. Notably, the hardness of Amm2 Cr2C is 26.30 GPa at ambient pressure, better than the known Cr2C structures. Based on the results of the density of state and Mulliken overlap population simulation, there is strong covalent-ionic Cr-C bonding interaction in Amm2 Cr2C, which is also revealed by the analysis of Debye temperature. Furthermore, the relative enthalpy as functional of pressure of all structures were calculated to understand their stabilities under high pressure. Overall, the predicted stable structures will provide more options to facility the synthesis and application of transition metal carbides. [ABSTRACT FROM AUTHOR]

Aristino-Traianoupolis area hosts one of the most significant water-dominated low-temperature geothermal fields in Greece. It is located on the southwestern uplifted margin of the Tertiary Evros Delta molassic basin, 10 km east of the town of Alexandroupolis (Thrace, NE Greece). The upper hydrothermal system of the Aristino Geothermal Field (AGF), one of the most promising in continental Greece, contains fluids with temperatures ranging from 51 to 99 °C, within a series of overlapping aquifers at very low depths (100–430 m). The main geothermal anomaly for temperatures higher than 90 °C covers an area of 6 km2, to a maximum prospected depth of 500 m below ground surface. The scattered regional anomaly exceeds 50 km2 and is characterized by excessively high and abruptly changing thermal gradient (42 to 450 °C/km) and heat flow (80–800 mW/m2), that are both typical of a fault-controlled hydrothermal system. Since 1993, the AGF has undergone non-systematic geothermal investigation, with emphasis on low-depth (100–500 m) drilling. This paper provides, for the first time, a synthetic and detailed evaluation of all available temperature data gathered in the last 25 years. The steady-state temperature logs reveal the dominant role of conduction for the upper geothermal system, accompanied, in most cases, by rapidly changing and abnormally high thermal gradients (100–450 °C/km), triggered, most probably, by a deeper system of higher temperature. This hypothesis is also supported by the applied chemical geothermometers, which suggest initial fluid temperatures at 140–150 °C, the hydrochemical characteristics of the fluids hosted in the deeper and most promising investigated reservoir (ignimbrite) of the upper system, and the extrapolated temperatures from the conductive temperature–depth profiles. The lower widespread medium enthalpy hydrothermal system should extend at depths 500–1000 m within volcanics and the expected Eocene limestones and basal clastic series of the Tertiary sequence that have filled the basin. Nevertheless, these assumptions need to be verified by appropriate investigations and new drillings at depths greater than 600–700 m, which would confirm the presence of a productive medium enthalpy reservoir. [ABSTRACT FROM AUTHOR]

Estimation of design fires and thermal exposure conditions is an important step in structural fire engineering procedures. Mass timber, as a combustible material, may contribute to the fire intensity, yet there lacks methods to estimate design fires in compartments with exposed timber. This paper summarizes available experimental data on the contribution of exposed timber to heat release rate, describes a simple analytical method to evaluate this contribution, and discusses the effects on time–temperature curves and required firefighting resources based on a case study. Results show that the total heat release rate in compartments increases with the surface of exposed timber. This total heat release rate can be conservatively estimated using empirical relationships for ventilation-controlled burning rate and charring depth. In estimating gas temperature–time curves, both external flaming and extended fire duration combustion models can be applied to obtain an envelope of fire severity inside the compartment and for external spread. The proposed assessment approach provides a method to evaluate realistic design fires in timber buildings and to estimate the water supply required to put out these fires. Accurate modeling of the contribution of timber to fire severity is important for the design of mass timber construction as well as for the safety of firefighters. [ABSTRACT FROM AUTHOR]

This paper studies the spectral radiation characteristics of gas-fuel combustion media through numerical calculation from the perspective of radiative energy utilization. Based on accurate band model for gas radiation and the radiation transfer equation, one-dimensional cases representing flame temperature field are constructed to investigate the effects of different flame media parameters on the spectral radiative energy proportion and total radiative heat flux, including the temperature, total pressure, partial pressure, path-length, and molar ratio. The interactions between the parameters are also analyzed. The radiation energy quality is also properly analyzed based on the equivalent temperature theory. It is found that temperature is the dominant influencing factor. At an average temperature of 1600 K, the proportion of spectral radiation in the waveband of 0–3 μm accounts for 55%. Increases in the total pressure, partial pressure, and molar ratio enhance the total radiative energy and short-wavelength radiation proportion. The total pressure and partial pressure have similar effects, but the molar ratio has a less effect, especially under high-pressure conditions. The equivalent temperature method can be used to compare the quality of radiative energy more conveniently. Increasing temperature is the most important factor in improving energy quality. This study provides a reference for spectral radiative energy management and future research on photo and thermal energy cascade utilization based on fuel combustion. [ABSTRACT FROM AUTHOR]

The multi-pass double-sided arc welding (DSAW), as an advanced connection method, is typical for T-joints in large-scale arc structures. However, due to unknown deformation on reserved-clearance in the welding process, non-penetration is likely to occur. Therefore, it is of great significance to carry out welding deformation prediction and reserved-clearance calculation. In this paper, a dynamic heat distribution model and TEP-FE approach is presented to calculate the welding deformation on reserved-clearance. Furthermore, a deformation pattern is suggested to predict the clearance change. Firstly, a dynamic heat distribution and moving heat approach is proposed to calculate the temperature field of the DSAW process. Afterwards, the thermal elastic–plastic (TEP) finite element (FE) analysis is applied to calculate the welding deformation in the DSAW process. The heat distribution and moving heat function is iterated to the TEP-FE analysis as a subroutine. Heat convection and radiation dissipation are taken into consideration in the DSAW process. Compared with the previous welding calculation methods, the new method focuses on real-time deformation on reserved-clearance and arc-track moving heat source. Finally, the calculated results in TEP-FE analysis are verified by the measurement results. The welding deformation on reserved-clearance is in good agreement with the experimental results. The error of maximum reserved-clearance deformation between calculation and experimental is 7.8%. [ABSTRACT FROM AUTHOR]

Powders of various metals and boron are widely used in composite solid propellants to increase the combustion temperature and specific impulse of rocket engines. This paper presents the results of an experimental study of oxidation and ignition of ultrafine Alex aluminum powder, amorphous boron, microsized Al aluminum powder, and AlB2 and AlB12 aluminum borides in air. Metal and boron powders are heated and ignited by a CO2 laser in a heat flux density range of 65–190 W/cm2. It is revealed on the basis of thermal analysis data that the powder reactivity parameters are arranged in the following sequence (in descending order of activity): Alex B AlB12 AlB2 Al. The total specific heat release and the mass variation rate reach maximum values during the oxidation of amorphous boron and AlB12 aluminum dodecaboride. The Alex, boron, and AlB12 powders are easier to ignite in air under the action of an external radiant source. The power exponent in a dependence between the ignition delay time and the heat flux density = for the Al, AlB2, and AlB12 powders are approximately the same and equal to 2.0, and it is lower and reaches = 1.5 and 1.0 for ultrafine Alex and boron powders, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the numerical analysis of the transient performance of the latent heat thermal energy storage unit established on finite difference method. The storage unit consists of a shell and tube arrangement with phase change material (PCM) filled in the shell space and the heat transfer fluid (HTF) flowing in the inner tube. The heat exchange between the HTF, wall and PCM has been investigated by developing a 2-D fully implicit numerical model for the storage module and solving the complete module as a conjugate problem using enthalpy transforming method. A comparative investigation of the total melting time of the PCM has been performed based on natural convection in liquid PCM during the charging process. The novelty of this paper lies in the fact it includes convection in PCM and this investigation includes a detailed parametric study which can be used as a reference to design latent heat storage. The results indicate that natural convection accelerates the melting process by a significant amount of time. In order to optimize the design of the thermal storage unit, parametric study has been accompanied to analyze the influence of various HTF working conditions and geometric dimensions on the total melting time of the PCM. Another important feature considered in this work is the influence of the inner wall of the tube carrying the HTF on the entire melting time of the PCM. An error of around 7.2% is reported when inner wall of the tube is ignored in the analysis. [ABSTRACT FROM AUTHOR]

Extreme heat has occurred more frequently in recent years and will intensify in the future, and this change has serious impacts on rice (Oryza sativa L.) yields. Thus, it was crucial to evaluate its influence on rice yield reductions. Recent papers have shown that a lack of experimental data makes it difficult for most crop models to capture the impacts of heat stress. Therefore, this paper explored how to improve the performance of crop models under extreme heat stress based on the Decision Support System for Agrotechnology Transfer (DSSAT) CERES-Rice model. This study primarily focused on (i) quantifying spikelet fertility based on daily temperature and durations derived from controlled experiments, (ii) improving the performance of the CERES-Rice model under extreme heat stress, and (iii) simulating historical and future rice yields using the improved model. Specifically, a meta-analysis method was utilized to build a new heat stress function between spikelet fertility and temperature and heat day duration with high realization. Subsequently, independent artificial controlled experiments at two sites were proposed to calibrate and validate the CERES-Rice model. The results showed a higher R2 (> 0.739) and a lower RMSE that was reduced by 38~68% after incorporating the new heat stress function in the CERES-Rice model compared with that of the original model. Furthermore, a historical simulation (1980–2010) demonstrated that an improved CERES-Rice model could better capture rice yield in response to extreme heat. Using an ensemble of five climate model datasets and four Representative Concentration Pathways (RCPs), the analysis of the projected future (2020–2099) rice yield showed that the rice yield reduction caused by high temperature was considerable; however, the rice yields were overestimated by 34% and 18%, respectively, at the two sites. Some regions rarely affected by heat are likely to experience yield reductions in the future due to climate change. [ABSTRACT FROM AUTHOR]