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This is an article in the field of metallurgical engineering. China is short of bauxite resources, which makes the high alumina fly ash a kind of potential bauxite resources. The extraction of alumina oxide from fly ash will be used as a reserve technology, which will make the in-depth development and research constantly pushed forward. The pre-desilication soda lime sintering method of alumina extraction from fly ash has been introduced as the only large-scale and industrialized manufacture technology. It can provide reference information for technology development and the industrialization, and make the national bauxite strategic reserve system safe.

Abstract Lattice Boltzmann (LB) methods with reactive boundary conditions are widely used in pore-scale simulations of dissolution and ablation processes. The staircase approximation of curved boundary is often employed because of its simplicity in handling solid structure changes. In this work, the mass transfer of two typical LB reactive boundary schemes are analyzed for the staircase boundary. The Type I boundary scheme is based on relations of local distribution functions and a wet-node boundary mesh. The Type II boundary scheme adopts the half-way bounce-back scheme. Boundary concentrations are determined by finite difference, and a link-wise boundary mesh is used. The analyses demonstrate that for straight boundaries, both the boundary schemes have accurate mass transfer rates, which means the mass transfer calculated by exchanges of distribution functions is the same as that calculated by reaction rates. For curved boundaries with staircase approximation, including interfacial normal directions in the Type I boundary scheme can provide accurate mass transfer for inclined straight boundaries. However, if the staircase boundary geometry is used directly without normal directions, the reaction rate will be overestimated. One-dimensional and two-dimensional reaction-diffusion processes with dissolution are simulated to validate the analyses. Both the boundary schemes work well for one-dimensional simulations. For two-dimensional simulations, the Type II boundary scheme significantly overestimates the reaction rate, and stronger artificial anisotropic effects are observed. The Type I boundary scheme with normal directions has better performance, but error still exists.

Soil samples were excavated from 101 geographical locations in Beijing and transported back to a laboratory. The samples were tested for nine physical and chemical parameters, and the distribution ranges of the soil parameters were obtained. The soil in Beijing is mainly loam, involving clay and sand, with the pH being mainly neutral or weakly alkaline; its chloride content is low. Additionally, the soil parameters that vary substantially are the moisture content, resistivity, self-corrosion potential, redox potential, and self-corrosion current density. Herein, because of the long period required, in addition to the difficulty of burying corrosion-inspection pieces in the field, weight-loss experiments were performed in seven locations. Moreover, the corrosion rates calculated using Faraday’s law and the weight-loss method were compared and verified for seven locations. The results revealed that the corrosion rate obtained using Faraday’s law is consistent with that obtained using the weight-loss method. Therefore, the corrosion-rate data obtained using Faraday’s law in the laboratory have a certain practical significance; such data can provide support for follow-up research and analysis. The characteristics of the soil parameters and the correlation among different such parameters were obtained using the machine learning random-forest algorithm and Pearson coefficient analysis. The results reveal the soil self-corrosion potential, water content, and resistivity to be the key factors affecting the Q235 steel corrosion rate for the Beijing soil. The corrosion–rate prediction model of Q235 steel for the Beijing soil was established based on the machine learning random-forest algorithm. An average absolute error of

Phase change material (PCM) are characterized by their high latent heat and low density. Combining PCM with building walls, aircraft fuselages, and other structures can significantly enhance the thermal sink capability of these structures. In order to address the issue of low heat storage efficiency resulting from the low thermal conductivity of PCM, a novel integrated thermal protection structure (ITPS) architecture with a supportive structure based on a porous lattice has been designed. Experimental and numerical methods were employed to investigate the thermal response characteristics of the ITPS with and without PCM, the melting behavior of PCM within the porous lattice, and the effects of lattice configuration and pore size on the PCM melting rate. The current ITPS study includes evaluation of two types of lattice configurations and three different pore sizes. The results indicate that the inclusion of PCM reduces the internal panel temperature of the ITPS by approximately 15%. The melting of PCM occurs primarily at the central region of the porous lattice and gradually spreads towards the periphery until complete melting is achieved. Specifically, the Gibson–Ashby lattice configuration enhances the PCM melting rate by 43.5%, while the tetradecahedron lattice configuration yields a 53.1% improvement. Furthermore, for PCM with different pore sizes, smaller pores exhibit faster melting rates during the early and intermediate stages, whereas larger pores exhibit faster melting rates in the later stages as the proportion of liquid PCM increases. The conclusions of this study provide valuable insights for the application of PCM in the field of thermal management.

Flexible anodes are a common form of anode ground bed for the cathodic protection of buried pipes in station areas, especially in new stations. In most cases, flexible anode ground beds could obtain uniform potential distribution and good protection. However, in the process of operation, there are also failure conditions such as anode body or cable breakage, electronic shorting between anode and pipes and other situations, resulting in poor protection. How to troubleshoot failures has become a difficult problem restricting the application of flexible anodes in actual production. In this paper, the failures of a flexible anode cathodic protection system in a station were assessed and analyzed in detail. The main reasons for the failures were the electronic shorting between the flexible anode and buried pipe in local area and the breaking of a partial flexible anode. The troubleshooting methods for two kinds of failures were explored. By measuring the potentials of both the flexible anode and pipes in different areas and the excavation test, the location of electronic shoring was determined. And through measuring the grounding resistance of the flexible anode and excavation test, the breaking location of the flexible anode was found. By repairing the failure sites, the failed system was restored to normal, which could provide guidance for the failure analyses of the flexible anode cathodic protection system.

Abstract Background Temperature is involved in the regulation of carotenoid accumulation in many plants. The floral color of sweet osmanthus (Osmanthus fragrans Lour.) which is mainly contributed by carotenoid content, is affected by temperature in autumn. However, the mechanism remains unknown. Here, to reveal how temperature regulates the floral color of sweet osmanthus, potted sweet osmanthus ‘Jinqiu Gui’ were treated by different temperatures (15 °C, 19 °C or 32 °C). The floral color, carotenoid content, and the expression level of carotenoid-related genes in petals of sweet osmanthus ‘Jinqiu Gui’ under different temperature treatments were investigated. Results Compared to the control (19 °C), high temperature (32 °C) changed the floral color from yellow to yellowish-white with higher lightness (L*) value and lower redness (a*) value, while low temperature (15 °C) turned the floral color from yellow to pale orange with decreased L* value and increased a* value. Total carotenoid content and the content of individual carotenoids (α-carotene, β-carotene, α-cryptoxanthin, β-cryptoxanthin, lutein and zeaxanthin) were inhibited by high temperature, but were enhanced by low temperature. Lower carotenoid accumulation under high temperature was probably attributed to transcriptional down-regulation of the biosynthesis gene OfPSY1, OfZ-ISO1 and OfLCYB1, and up-regulation of degradation genes OfNCED3, OfCCD1-1, OfCCD1-2, and OfCCD4-1. Up-regulation of OfLCYB1, and down-regulation of OfNCED3 and OfCCD4-1 were predicted to be involved in low-temperature-regulated carotenoid accumulation. Luciferase assays showed that the promoter activity of OfLCYB1 was activated by low temperature, and repressed by high temperature. However, the promoter activity of OfCCD4-1 was repressed by low temperature, and activated by high temperature. Conclusions Our study revealed that high temperature suppressed the floral coloration by repressing the expression of carotenoid biosynthesis genes, and activating the expression of carotenoid degradation genes. However, the relative low temperature had opposite effects on floral coloration and carotenoid biosynthesis in sweet osmanthus. These results will help reveal the regulatory mechanism of temperature on carotenoid accumulation in the petals of sweet osmanthus.

Abstract This work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets. According to the experimental results, two different splashing patterns, corona splash and levitating-lamella breakup, are observed. A new breakup mode, named rim-segmenting, is found during the levitating-lamella breakup. In particular, the detailed information of the splashing secondary droplets, including the size, velocity, angle, and total volume of the splashing secondary droplets is obtained from the experimental data. The size distribution of the splashing secondary droplets obeys the gamma distribution function. The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re, and can be expressed as functions of Re. High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets. We also put forward an empirical model to predict the total splashing volume, which is consistent with the experimental data both in this work and previous studies. This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets.

A new ultrasonic method for synchronous measurement of multiple parameters of heated materials is proposed in this paper. Based on the thermal-acoustic-solid coupling theory, the internal temperature distributions and thickness of solid structures are reconstructed synchronously by an alternate iterative multi-parameter identification method. Firstly, a numerical model of multi-parameter synchronous identification is obtained based on temperature dependence of the velocity of the ultrasonic wave propagating through the heated material. Then, an inverse analysis by the alternate iterative method for estimating equivalent thermal boundary conditions and thickness. In addition, experiments are carried out in order to validate the feasibility and reliability of the developed method, whose stability and accuracy are also analyzed through a comprehensive parameter analysis. The research results show that the structure thickness obtained by the alternate iteration method based on ultrasonic transit time accords with the physical reality and the internal transient temperature profiles determined ultrasonically agrees well with those obtained using thermocouples installed in the steel. It demonstrates that the method proposed in this work is an effective multi-parameter synchronous measurement means to determine the internal transient temperature distribution and thickness of high temperature structures with high accuracy by ultrasonic pulse echo measurements.

The effect of high temperature on corrosion behavior and passive film composition of Ni-based alloy 825 in H2S-containing environment was investigated by Confocal Laser Microscope (CLM), Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray Photoelectron Spectroscopy (XPS). The experiment was carried out at 150 and 230°C in NaCl solution. The partial pressure of H2S was set to 1.2 MPa and CO2 was set to 3.2 MPa. The results showed that Ni-based alloy 825 presented good general corrosion resistance. Pitting corrosion was likely to occur at 230°C because of Cr depleted in the passive film. NiS appeared at high temperature and is damaging to protectiveness of passive film.

The structural anisotropy of open-cell foam leads to the anisotropy of effective thermal conductivity (ETC). To quantitatively analyze the effect of structural anisotropy on the anisotropy of ETC, a new predicting model for the ETC of anisotropic open-cell foam was proposed based on an anisotropy tetrakaidecahedron cell (ATC). Feret diameters in three orthogonal directions obtained by morphological analysis of real foam structures were used to characterize the anisotropy of ATC. To validate our proposed anisotropic model, the ETCs of real foam structures in three orthogonal directions predicted by it were compared with the numerical results, for which the structures of numerical models are reconstructed by X-ray computed tomography (X-CT). Using the present anisotropic model, the influences of the thermal conductivity ratio (TCR) and porosity of the foams on the anisotropic ratios of ETCs are also investigated. Results show that there is good consistency between the ETCs obtained by the anisotropic model and the numerical method. The maximum relative errors between them are 2.84% and 13.57% when TCRs are 10 and 100, respectively. The present anisotropic model can not only predict the ETCs in different orthogonal directions but also quantitatively predict the anisotropy of ETC. The anisotropies of the ETCs decrease with porosity because the proportion of the foam skeleton decreases. However, the anisotropies of ETCs increase with TCR, and there exist asymptotic values in anisotropic ratios of ETCs as TCR approaches infinity and they are equal to the relative Feret diameters in different orthogonal directions.

High-enthalpy dissociating aerodynamic environment during high-speed spacecraft entries brings new challenges to the prediction of heat transfer characteristics on the surface of thermal protection system. This study numerically dealt with the coupling modeling of chemically reacting interface in carbon-oxygen dissociating environment in order to accurately and reliably predict the Mars entry heating load. Computational fluid dynamics, computational heat transfer and interface balance with proper coupling strategy were involved in the coupling algorithm to take into account the surface catalysis, material ablation and structural thermal response. Numerical simulation shows that the interfacial reaction model has influences on coupling evolution by exchanging various patterns of heat transfer on the interface, including that from temperature gradient, that caused by chemical reaction, and that carried by the injection kinetic energy. The types and energy barriers of interfacial reaction were found to change the aerodynamic heating enhancement and its evolution over coupling time, which is the most remarkable difference from the perfect gas result. Gas-solid interaction involving interfacial reaction exhibits three distinct temporal intervals: the initial, developing and fully developed stages, and the chemical dynamics and heat transfer characteristics vary at different temporal scales. Related research provides important technical support for the design of thermal protection system for space vehicles.

X80 steel has great risk of corrosion in high voltage direct current (HVDC) interference cases. In this study, the anodic polarization behavior of X80 steel under high potential and current density in Na2SO4 solution was investigated. The I × R drop was eliminated using current interrupt technique during the potentiodynamic measurement. Therefore, the real polarization curve was obtained. The corrosion behavior was investigated by galvanostatic polarization, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results show a new form of passivation route. The steel dissolved actively below −0.388 VSCE, then became partly passivated from −0.388 to 1.448 VSCE, and fully passivated above 1.448 VSCE. The passive film was formed containing Fe2O3 and FeOOH, and resistant to SO42− ions. It not only blocked the direct dissolution of steel, but also facilitated oxygen evolution. The corrosion rates of steel samples decreased after the passivation.

With the development of high voltage direct current (HVDC) systems, some pipelines have been badly interfered. The corrosion mechanism of pipelines has not been clearly clarified. In this work, laboratory experiments were designed to study the corrosion behavior of X80 steel under HVDC interference in sandy soil. The corrosion rates were related to the change in direct current (DC) density, which experienced three stages in the interference process. As soon as high DC interference voltage was applied to the working electrode, the current density increased sharply to a peak value in a few seconds. It then decreased rapidly to a steady value over dozens of seconds. Finally, it remained steady for the remaining time. With the measurement of local soil properties, the change in DC density was attributed to the local soil temperature increment, the water content decrement, and the substantial growth in the soil spread resistance. Moreover, the parameters contribute to the corrosion reaction during the interference process. The corrosion products were characterized at different times of interference via Raman spectroscopy. Lepidocrocite was produced under high DC density and then transformed to hematite under low DC density. Based on the above, the corrosion model during HVDC interference is proposed.

Keeping steps ahead of the bacteria in the race for more efficacious antibacterial strategies is increasingly difficult with the advent of bacterial resistance genes. Herein, we engineered copper sulfide nanoclusters (CuSx NCs) with variable sulfur defects for enhanced dual-treatment of bacterial infections by manipulating photothermal effects and Fenton-like activity. Next, by encasing CuSx NCs with a complex mixture of amino acids and short peptides derived from Luria-Bertani bacterial culture media as a protein corona, we managed to coax E. Coli to take up these CuSx NCs. As a whole, Amino-Pep-CuSx NCs was perceived as a food source and actively consumed by bacteria, enhancing their effective uptake by at least 1.5-fold greater than full length BSA protein BSA-corona CuSx NCs. Through strategically using defect-engineering, we successfully fine-tune photothermal effect and Fenton-like capacity of CuSx NCs. Increased sulfur defects lead to reduced but sufficient heat generation under solar-light irradiation and increased production of toxic hydroxyl radicals. By fine-tuning sulfur defects during synthesis, we achieve CuSx NCs with an optimal synergistic effect, significantly enhancing their bactericidal properties. These ultra-small and biodegradable CuSx NCs can rapidly break down after treatment for clearance. Thus, Amino-Pep-CuSx NCs demonstrate effective eradication of bacteria both in vitro and in vivo because of their relatively high uptake, optimal balanced photothermal and chemodynamic outcomes. Our study offers a straightforward and efficient method to enhance bacterial uptake of next generation of antibacterial agents.