In this work, we develop a finite volume weighted essentially non-oscillatory (WENO) scheme based on an exponential approximation space for solving the five-equation transport model of compressible two-medium flows. Compared to the scheme based on the conventional polynomial approximation space, the performance of the present scheme is improved by locally optimizing the shape parameter in the exponential function such that the reconstructed solution can attain one enhanced order of accuracy without the need of increasing the stencil size. More importantly, through analyzing the relationship between the shape parameter and the linear weights of the WENO approximation, we present a suitable upper bound for the shape parameter which is able to avoid the appearance of negative linear weights. Finally, with the aim of maintaining computational robustness under large density and pressure ratios, we design a bound-preserving and positivity-preserving limiting algorithm targeted for the non-polynomial approximation space based finite volume WENO scheme. Numerical results demonstrate that the present scheme achieves high-order accuracy, high resolution and strong robustness in simulating compressible two-medium flows.

In this study, we present a novel robust discontinuous Galerkin (DG) method based on the Harten-Lax-van Leer-contact (HLLC) approximate Riemann solver for weakly compressible two-phase flows governed by a three-equation model. The proposed method satisfies the mechanical equilibrium criterion which states that uniform velocity and pressure should be remained uniform during the simulation. It also maintains a positive density solution and an oscillation-free material interface by employing a positivity-preserving limiter and a compact multi-resolution weighted essentially non-oscillatory (MRWENO) limiter without violating the mechanical equilibrium criterion. A series of one- and two-dimensional numerical results are presented to demonstrate the exceptional accuracy and robustness of the proposed method. More importantly, based on the extensive numerical results, we successfully derive a suitable choice on the linear weight of the MRWENO limiter, which plays an important role in both accuracy and robustness in simulating weakly compressible two-phase flows.

Large and complex components usually have surfaces with variable curvature. Most of the existing climbing robots are difficult to cover the whole surface of the component for post-processing operations such as grinding. In this paper, a wheeled negative pressure climbing robot is presented, which is equipped with novel flexible double-layer adsorption chambers that can passively comply with complex uneven curved surfaces. The proposed robot can carry various actuators to operate on the surface of the component. The dynamic analysis of the robot is carried out, and the stable adsorption condition for the robot moving on a curved surface with variable curvature is established. A series of experiments are carried out on the curved surface of the blade of a large wind turbine. The results indicate that the robot equipped with the proposed adsorption chamber can adapt to the variablecurvature surfaces of wind turbine blades (with a minimum curvature radius of 1.1 m) and carry specially designed endeffectors weighing 7.5 kg to perform surface grinding operations.

Predicting fracture of heterogeneous composites under chemo-mechanical circumstances is still challenging, owing to intricate interactions between different components and complex crack paths. Herein, we present novel phase-field model (PFM) based framework for chemo-mechanical fracture of heterogeneous composites from a thermodynamically consistent formulation. By introducing two phase-field variables, both interface and crack are represented in a smeared manner, and the damage of bulk and interface is unified for providing computational conveniences. To characterize quasi-brittle fracture, a cohesive zone model (CZM) with the linear traction-separation law (TSL) is incorporated to the PFM through elegantly choosing optimal constitutive functions. Besides, the material properties are regularized by the interface phase-field to avoid the discontinuity in stress across the material interface, and an analytical expression of modified interface fracture toughness derived to guarantee the energetic equivalence. For numerical implementation, a staggered solution scheme adopted to enable algorithmic efficiency and robustness. Representative numerical experiments are conducted to demonstrate the capability of the framework in capturing fracture behaviors including matrix cracking, interface failure, and crack branching and merging.

In the context of low-carbon transition, ammonia (NH3) is considered as a promising zero-carbon fuel owing to its high hydrogen density, well-established storage, and transportation systems. However, its low reactivity and high nitrogen content could induce flame instability and high NO emission problems during combustion, which hinders its large-scale application in industrial furnaces, gas turbines, and engines. The reactivity of NH3 can be effectively boosted by blending it with a more reactive fuel, such as methane (CH4). In addition, it has been demonstrated that burning NH3 at slightly rich equivalence ratios produces low NO emissions, but air-staging is needed to oxidize the unburned fuel in a secondary lean combustion zone. This paper carries out an experimental and numerical study for NH3/CH4 premixed swirling flames in a model combustor with and without air-staging. The main objective is to investigate the potential of using air-staging for controlling NO emissions from NH3/CH4 flames, and to examine the influence of key air-staging parameters, such as staged air ratio (SAR), height of staged-air (H) and number of staged-air nozzle (N), on flame typology as well as NO and CO emissions. Experimental results show that globally lean condition fails to generate satisfactory NO emission for NH3/CH4 mixtures under non-staging mode, and the maximum NO emission is produced by the XNH3 = 50% mixture which exhibits the largest challenge for NO control. By initiating air-staging for XNH3 = 50% mixture, the flame topology as well as CO and NO emissions are strongly affected by the key air-staging parameters. In relatively large SAR (> 30%) and small H (< 80 mm) conditions, the staged-air impinging effect should be taken into consideration since it could destroy the locally rich atmosphere in the primary combustion zone, creating lean burning pockets and enhancing NO formation. Increasing N plays an accelerating role on NO generation due to improved mixing homogeneity in the vicinity of staged-air, while this effect can be counteracted by mitigating the staged-air impinging effect via decreasing the staged-air injection momentum. Moreover, an improved NH3/CH4 reaction mechanism based on Okafor's is proposed which shows remarkably high accuracy in predicting NO emission for NH3/CH4 mixtures under both non-staging and air-staging modes. This work provides new insights towards the understanding of NH3/CH4 combustion using air-staging.

Despite the high microstructural heterogeneity of fiber-reinforced composites, few modeling framework provides a comprehensive and detailed understanding of the failure mechanisms of these materials. The aim of this work is to present a coupled phase-field cohesive-modeling framework that can precisely capture the progressive failure and damage behaviors of multiphasic microstructures and multifiber systems. Here, the phase-field method captures crack evolution in the matrix, and a coupled cohesive-zone model is introduced to characterize interfacial debonding. The novel model framework comprises the following novel aspects. (1) A newly developed scalar indicator that directly extracts inelastic strain from the total strain field and couples the cohesive traction-separation law with the phase-field model to determine the regularized interfacial displacement jump. (2) The periodic boundary conditions in the coupled phase-field cohesive framework are incorporated to characterize crack evolution in random fiber systems. (3) A complete set of failure modes, namely crack initiation, propagation, kinking, and coalescence are characterized in highly heterogeneous solids. Parametric studies of the novel framework yield numerical results that are highly consistent with experimental findings and reveal the effects of fiber distributions, fiber volume fractions, and boundary conditions on the nonlinear mechanical behaviors of fiber-reinforced composites. The results demonstrate the excellent potential of the novel numerical framework to evaluate the mechanical performances of composite materials in engineering applications.

Adapting to unfavorable environments is a necessary step in plant terrestrialization and radiation. The dehydration-responsive element-binding (DREB) protein subfamily plays a pivotal role in plant abiotic stress regulation. However, relationships between the origin and expansion of the DREB subfamily and adaptive evolution of land plants are still being elucidated. Here, we constructed the evolutionary history of the DREB subfamily by compiling APETALA2/ethylene-responsive element-binding protein superfamily genes from 169 representative species of green plants. Through extensive phylogenetic analyses and comparative genomic analysis, our results revealed that the DREB subfamily diverged from the ethylene-responsive factor (ERF) subfamily in the common ancestor of Zygnemophyceae and Embryophyta during the colonization of land by plants, followed by expansions to form three different ancient archetypal genes in Zygnemophyceae species, designated as groups archetype-I, archetype-II/III, and archetype-IV. Four large-scale expansions paralleling the evolution of land plants led to the nine-subgroup divergence of group archetype-II/III in angiosperms, and five whole-genome duplications during Brassicaceae and Poaceae radiation shaped the diversity of subgroup IIb-1. We identified a Poaceae-specific gene in subgroup IIb-1, ERF014, remaining in a Poaceae-specific microsynteny block and co-evolving with a small heat shock protein cluster. Expression analyses demonstrated that heat acclimation may have driven the neofunctionalization of ERF014s in Pooideae by engaging in the conserved heat-responsive module in Poaceae. This study provides insights into lineage-specific expansion and neofunctionalization in the DREB subfamily, together with evolutionary information valuable for future functional studies of plant stress biology.

Background: Ibuprofen (IBP) is typically ubiquitous in various environments, which has negatively impacted microorganisms, animals, and human health. Methods: A carbon nanofiber-supported bimetallic catalyst (Co/Fe@CNFs) was synthesized by electrospinning and carbonization for sulfate radical-based advanced oxidation processes (SR-AOPs) in IBP treatment. Co and Fe nanoparticles were wrapped inside the CNFs to avoid agglomeration and achieve uniform distribution. The performances of catalysts were evaluated via IBP degradation efficiencies. Findings: Co/Fe@CNFs could efficiently activate both peroxymonosulfate and persulfate, achieving 100% and 89.1% degradation of IBP within 60 min with an activation energy of 37.4 and 65.4 kJ/mol, respectively. In the PMS system, both Co and Fe catalyze PMS to generate reactive oxygen species (SO4 center dot, center dot OH, O2(center dot) and O-1(2)), all of which contributed significantly to degradation. However, the main functional species were SO4 center dot and center dot OH in the Fe activated PS system. This work would deepen the understanding of sulfate radical-based advanced oxidation process to further expand its application in environmental remediation. (C) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Pretreatment before biomass combustion is significant for its efficient utilization and that combined water washing and carbonization can be efficient. An agricultural processing residues sesame stalk was selected and carried out two pretreatments separately, i.e., water washing-torrefaction (W-T) and torrefaction-water washing (T-W), to explore the effect on the fuel properties, combustion characteristics and particulate matter (PM) emission. The obtained biochar was also combusted under air and oxy50 (CO2:O2 = 50:50) conditions for the sake of investigating the effect of pretreatment and combustion atmosphere. The results indicate that, W-T and T-W both not only have great effect on the improvement of fuel properties but also reduce the content of water-soluble elements like K, Cl, etc. Due to the difference in hydrophobicity, the biochar obtained by W-T have the optimal fuel properties. At the same time, the pretreatment also hinder the combustion in a certain extent in which the comprehensive combustion characteristics (SN) show a downward trend. Furthermore, both two pretreatments have obvious benefit on the reduction of PM1 emission and W-T have the best effect related to the higher removal efficiency of inorganic elements (especially K + Na + Cl + S). Under oxy50 condition, the oxygen concentration and combustion temperature is higher, improving the sulfation of K and vaporization of Ca, P and Mg which result in weakening in the pretreatment reduction effect on PM1 emission.

ABSTRACT A solution of Al(NO3)3.9H2O and NaOH was used to perform Mg-Al LDH plugging treatment on the LA103Z magnesium-lithium alloy micro-arc oxidation ceramic layer. The effect of treatment temperature on the micro-arc oxidation ceramic layer structure and corrosion resistance was studied. The formation mechanism of Mg-Al LDH film and corrosion mechanism of the film layer were discussed. The results show that the sealing essence of Mg-Al LDH is that the Mg2+ obtained by dissolving the MgO component of the MAO film layer is combined with OH– in the hydrothermal solution to form a layered Mg(OH)2, the formation of LDH tends to be inside the pores. In the lower temperature range, the temperature increase is conducive to the increase and thickening of the LDH layer and the film layer is dense and corrosion resistant. In the higher temperature range, the increase in temperature is conducive to the increase in the size of the LDH layer. The layer is loose and coarse, and the corrosion resistance is reduced. The composite film is the densest at 90oC, and its insulation and corrosion resistance are better than the composite film obtained at other temperatures, the MAO film and the substrate. GRAPHICAL ABSTRACT

In this work, sorbent pellets were prepared based on six synthetic powdery sorbents. CO2 uptake tests and kinetic analysis were carried out to screen sorbent pellets. Experimental results showed that the CO2 capture capacity of sorbent pellets was lower than that of powdery sorbents, which was mainly attributed to reduced Brunauer-Emmett-Teller (BET) specific surface area caused by pore structure damage during the pelletization process. However, the sorbent pellet CaSi75p containing 75 wt % CaO and 25 wt % Ca2SiO4 was less affected by pelletization than other sorbent pellets, which can be explained by the formation of cracks and pores that resulted from the crystalline change of Ca2SiO4 during the calcination-carbonation cycles. Among all of the sorbent pellets, CaSi75p showed the highest CO2 capture capacities of 0.531 g/g and 0.26 g/g in the first and 25th cycles. The performance of sorbent pellets was improved by adding cellulose as a pore-forming material. The reaction rate constants for all sorbents in each cycle were calculated. The experimental and kinetic data indicated that CaSi75p was an excellent sorbent even without adding cellulose.

The micro-arc oxidization (MAO) ceramic layer on an LA103Z Mg-Li alloy substrate was treated with a hydrothermal treatment at 90 °C for various times. The effect of the hydrothermal treatment time on the microstructure and corrosion behavior of MAO/LDH composite coatings in 3.5 wt.% NaCl solution was investigated, and the mechanism of hydrothermal film formation and corrosion was discussed. The results show that MgO on the surface of the MAO ceramic coating was partially dissolved during the hydrothermal treatment, and the released Mg2+ ions combined with OH− ions in the hydrothermal solution to form Mg(OH)2 nanosheets, which were deposited on the surface of the ceramic coating and its pores. The hydrogen evolution rates of the MAO/LDH composite coatings rank as MAO/LDH-24 h < MAO/LDH-18 h < MAO < MAO/LDH-12 h. A MAO/LDH composite coating had the minimum weight loss, which proves that the MAO/LDH composite coating prepared by MAO and hydrothermal treatment has better corrosion resistance than a single MAO ceramic layer and adds long-term corrosion resistance to the magnesium alloy.

Sea rice is a strategic resource which will play an important role in global food supply, especially in the context of rapid population growth and the associated reduction in agricultural land areas, freshwater shortage, and sea-level rise as a result of global warming. This study investigates the occurrence characteristics of ash-forming elements in sea rice waste (including sea rice straw and sea rice husk) and their effects on thermal behavior and particulate matter emissions during combustion. The results show that sea rice waste has more Na, Mg and Ca than ordinary rice waste. The Na content in sea rice straw is 1643 mg/kg_fuel, whereas that in ordinary rice straw is only 380 mg/kg_fuel, and sea rice husk contains approximately 30 times more Na than ordinary rice husk. Sea rice husk also has a lower K content, which increases its thermal stability. Furthermore, maximum of decomposition rates occur at about 301 degrees C which is a higher temperature than that for ordinary rice husk (290 degrees C). Sea rice waste combustion was conducted in a high-temperature drop tube furnace at 1500 degrees C. Results show that sea rice waste combustion released more PM10 than ordinary rice waste, and the oxy-fuel atmosphere promoted the formation of PM10.

In order to improve the corrosion resistance of magnesium-lithium (Mg-Li) alloy, a micro-arc oxidation (MAO) ceramic layer was first prepared on LA103Z Mg-Li alloy, and then the MAO coating on LA103Z Mg-Li alloy was sealed by layered double hydroxide (LDH) hydrothermal treatment. The obtained samples were subjected to immersion test in 3.5% NaCl solution for 8 days. The growth characteristics of different coatings before immersion were studied by XRD, SEM and EDS. Morphology and composition of the coatings were observed before and after corrosion. Electrochemical test of the composite film was performed to explore the corrosion resistance and influence of different time on corrosion resistance of MAO/LDH composite film. The results displayed that MAO/LDH composite film have the lowest corrosion current density, the most positive corrosion potential, can effectively protect the substrate from corrosion by NaCl solution, improved long-term corrosion protection, and can considerably improve the corrosion resistance of the alloy.

钙基吸附剂循环CO2吸附性能对增强式生物质气化连续高效制氢起重要作用.采用将CaO颗粒分散在惰性载体中的方法并结合挤压成型技术制备了合成吸附剂颗粒.为了筛选循环吸附性能较好的吸附剂,在热重分析仪上进行了循环吸附性能测试.基于热重测试结果开展了吸附剂循环利用条件下的增强式生物质气化制氢实验.结果表明:添加惰性载体能延缓CaO烧结,提高吸附剂的循环吸附能力;挤压成型过程会破坏吸附剂原有孔隙结构,导致吸附剂颗粒吸附性能不同程度降低,其中CaSi75p、CaAl75p和CaY75p三种吸附剂循环性能较好;添加以上三种吸附剂颗粒均可显著提高生物质气化合成气中H2浓度及产率,5次循环过程中气体成分和产率变化不大,表明吸附剂循环吸附能力和稳定性较好.

With the hypothesis of a small deformation, the novel cyclic visco-plasticity constitutive model (CV-CM) is constructed to study the cyclic deformation responses of polycrystalline metals. In this model, a modified Armstrong–Frederick nonlinear kinematic hardening (NKH) law is adopted to simulate the ratchetting deformation more precisely. The cyclic hardening characteristic of FCC polycrystalline copper is investigated with the use of flow stress evolution of slip system. For the issue of the transition from single crystal to polycrystalline crystals, the explicit [Formula: see text] rule is introduced to compute the polycrystalline response. Finally, through comparison with the experimental data, the proposed model is verified. It is demonstrated that the uniaxial ratchetting response of FCC metal can be precisely captured. The ratchetting response of copper single crystal and its relation with the crystallographic directions can be exactly traced by the present model as well.

Direct transformation of cellulose (PH101: DP similar to 200) into 5-hydroxymethylfurfural (HMF) was investigated using the single CrCl3 or the combination of metal chlorides (CrCl3 with AlCl3, FeCl3, SnCl4, MnCl4, and CuCl2) in ionic liquid [Bmim]Cl under oil-bath heating. As a result, a novel co-catalysis CrCl3-AlCl3 was determined to be the most efficient catalyst for the production of HMF. Compared with single CrCl3, the reaction time with CrCl3-AlCl3 was reduced by nearly 1/3 when a similar HMF yield (58.3%) was obtained at 120 degrees C. Additionally, the catalytic mechanism of CrCl3-AlCl3 was discussed. Furthermore, when celluloses with higher polymerization degree (filter paper: DP similar to 1500 and cotton: DP similar to 1950) were used, exceedingly higher yields of HMF (54.7% for filter paper and 59.5% for cotton) were obtained compared with previous work. This important result strongly indicates the general applicability of CrCl3-AlCl3 for various kinds of natural cellulose with a huge range of DP.

China greenhouse gas inventories show that CO2 emissions from the lime industrial process are large scales and closely related to the development of its downstream industries. Therefore, there is high importance to analyze and forecast on reducing China’s CO2 emissions from lime industrial process. The aims of this paper are to make up the research gaps in China and provide a quantitative reference for related authorities to formulate relevant policies. The prediction method in this paper is consistent with the published national inventory, which is an activity data based method to predict carbon dioxide emissions from the industrial process of four categories of lime products. Three future scenarios are assumed. The business as usual scenario (BAU) is a frozen scenario. There are two emission reduction scenarios (ERS and SRS) assumed under different emission reduction strength considering combined industrial process CO2 emission reduction approaches from both the production side and the consumption side. The results show that between 2020 and 2050, China’s lime industrial process has an increasingly significant CO2 emission reduction potential, enabling both emission intensity reductions and total emission reductions to be achieved simultaneously. Based on the simulation results from emission reduction scenarios, compared with 2012 level, in 2050, the emission intensity can be reduced by 13–27%, the total lime production can be reduced by 49–78%, and the CO2 emissions in the lime industrial process can be reduced by 57–85%.

Pyrolysis is increasingly employed to dispose rubber wastes by thermal cracking into chemicals. Previous studies focus on pyrolysis recycling of tyre rubber wastes. The pyrolysis of non-tyre rubber wastes, which may be different from that of tyre rubber wastes, receives scarce attention. For the purpose of providing guidance for thermo-chemical process management for the pyrolysis recycling of non-tyre rubber wastes, the pyrolysis kinetics and mechanism of representative industrial non-tyre rubber wastes namely the mixture of waste hoses, floor coverings and sealing strips are investigated using thermogravimetry in nitrogen and peak-differentiating analysis with Guassian function. Multi kinetics methods are adopted. Results indicate that three peaks and three shoulders occur in the reaction rate curves. Guassian function is capable to well separate the pyrolysis of non-tyre rubber wastes mixture into six independent one-step sub reactions. The six sub reactions may be characterized by traditional power law model and nucleation mechanism. However, the pyrolysis of non-tyre rubber wastes mixture may be well characterized employing a modified power law model f (alpha) = 1.89 x 10(-5)alpha(-1.19) and nucleation mechanism. The average value of activation energy and pre-exponential factor for the whole pyrolysis process of non-tyre rubber wastes mixture is 97.77 kJ/mol and 1.37 x 10(10) min(-1), respectively.

In this study, three kinds of monocarboxylic acids, formic, acetic, and propionic acids, are first applied to modified microalgae residuals (M1-RD, M2-RD, and M3-RD, respectively) after lipid extraction, aiming to enhance the adsorption capacity and selective binding ability for Hg(II) ions in simulated wastewater. The effect of pH, temperature, and initial Hg(II) concentration was investigated to identify the optimum adsorption conditions. Batch adsorption tests showed that the maximum adsorption efficiency obtained was 96.7% for Ml-RD, 91.1% for M2-RD, and 84.4% for M3-RD at pH 4.05 compared to 48.5 and 57.6% for raw and residual microalgae at pH 5.01, respectively. The adsorption capacity of raw, residual, and modified microalgae increased with the increase of the temperature. Langmuir and Freundlich isotherm model tests showed that the maximum equilibrium adsorption capacity among three modified adsorbents reached 63 +/- 3 mg/g for M1-RD, in contrast to 17 +/- 1 and 25 +/- 2 mg/g for raw and residual microalgae, respectively. The characterization of the modified sample by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, and scanning electron microscopy showed that the fibrous structure of the algae was decomposed by carboxyl groups in organic acids involved in microalgae, resulting in a larger surface area and more binding sites. In consideration of ion interference in the actual process, a kind of actual desulfurization wastewater from a 1000 MW coal-fired power plant (Guangdong, China) was introduced in the simulated adsorption system. Verification tests in desulfurization wastewater showed that up to 96% of Hg(II) ions were removed, probably as a result of co-precipitation of mercury and other co-existing ions.