The main pump blades of lead cooled fast reactor have complex mechanical characteristics, and there are complex fluid-structure coupling problems in the structural analysis of the impeller. In this paper, CFX software...
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The climate crisis necessitates the development of non-fossil energy *** solar energy for fuel production shows promise and offers the potential to utilize existing energy ***,solar fuel production is in its early sta...
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The climate crisis necessitates the development of non-fossil energy *** solar energy for fuel production shows promise and offers the potential to utilize existing energy ***,solar fuel production is in its early stages of development,constrained by low conversion efficiency and challenges in scaling up *** solar energy(CSE)technology has matured alongside the rapid growth of solar thermal power *** review provides an overview of current CSE methods and solar fuel production,analyzes their integration compatibility,and delves into the theoretical mechanisms by which CSE impacts solar energy conversion efficiency and product selectivity in the context of photo-electrochemistry,thermochemistry,and photo-thermal co-catalysis for solar fuel *** review also summarizes approaches to studying the photoelectric and photothermal effects of ***,it explores emerging novel CSE technology methods in the field of solar fuel production.
An intelligent flow control on the flow separation over an airfoil under weak turbulent conditions is investigated and solved by deep reinforcement learning(DRL)*** single and synthetic jet control at the airfoil angl...
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An intelligent flow control on the flow separation over an airfoil under weak turbulent conditions is investigated and solved by deep reinforcement learning(DRL)*** single and synthetic jet control at the airfoil angles of attack of 10°,13°,15°are compared by training a neural network for closed-loop active flow control strategy based on the soft actor-critic(SAC)*** training results demonstrate the effectiveness of the deep reinforcement learning-based active flow control method in suppressing the flow separation at high angles of attack,validating its potential in complex flow *** improve the stability of the shedding vortex alley over airfoil,a novel reward function considering the vorticity statistics in terms of both vortex and asymmetric shear intensity is first proposed in this *** vorticity driven reward is demonstrated to perform better in suppressing the rotation and shear intensity and the aerodynamic optimization than the traditional ***,it can accelerate the convergence speed during the exploration ***,it can accelerate the convergence speed during the exploration *** study provides valuable insights for future applications of DRL in active flow control under more complex flow conditions.
Plastic has caused serious"white pollution"to the environment,and the highly inert characteristics of plastic bring a major challenge for *** fluids have unique physical properties and have been widely used ...
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Plastic has caused serious"white pollution"to the environment,and the highly inert characteristics of plastic bring a major challenge for *** fluids have unique physical properties and have been widely used in various *** this work,supercritical CO_(2)(Sc-CO_(2))with mild conditions was selected and assisted by NaOH/HCl solution to degrade polystyrene(PS)plastic,and the reaction model was designed using response surface methodology(RSM).It was found that,regardless of the types of assistance solutions,the factors affecting PS degradation efficiencies were reaction temperature,reaction time,and NaOH/HCl *** the temperature of 400℃,time of 120 min,and base/acid concentration of 5%(in weight),0.15 g PS produced 126.88/116.99±5 mL of gases with 74.18/62.78±5 mL of H2,and consumed 81.2/71.5±5 mL of CO_(2).Sc-CO_(2)created a homogeneous environment,which made PS highly dispersed and uniformly heated,thus promoting the degradation of ***,Sc-CO_(2)also reacted with the degradation products to produce new CO and more CH_(4)and C_(2)H_(x)(x=4,6).Adding NaOH/HCl solution not only improved the solubility of PS in Sc-CO_(2),but also provided a base/acid environment that reduced the activation energy of the reaction,and effectively improved the degradation efficiencies of *** short,degrading PS in Sc-CO_(2)is feasible,and better results are obtained with the assistance of base/acid solution,which can provide a reference for the disposal of waste plastics in the future.
Based on the existing energy-minimization multi-scale(EMMS)model for turbulent flow in pipe,an improved version is proposed,in which not only a new radial velocity distribution is introduced but also the quantificatio...
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Based on the existing energy-minimization multi-scale(EMMS)model for turbulent flow in pipe,an improved version is proposed,in which not only a new radial velocity distribution is introduced but also the quantification of total dissipation over the cross-section of pipe is improved for the dominant mechanism of fully turbulent flow in *** four dynamic equality constraints and some other constraints are constructed but there are five parameters involved,leading to one free variable *** the compromise in competition between dominant mechanisms for laminar and fully turbulent flow in pipe respectively,the above four constructed dynamic equality constraints can be ***,the cases for turbulent flow in pipe with low,moderate and high Reynolds number are simulated by the improved EMMS *** numerical results show that the model can obtain reasonable results which agree well with the data computed by the direct numerical simulation and those obtained by *** illustrates that the improved EMMS model for turbulent flow in pipe is reasonable and the compromise in competition between dominant mechanisms is indeed a universal governing principle hidden in complex ***,one more EMMS model for a complex system is offered,pro-moting the further development of mesoscience.
Given the limited exposure of active sites and the retarded separation of photogenerated charge carriers in those developed photocata-lysts,photocatalyticCO_(2)splitting into value-added chemicals has suffered f...
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Given the limited exposure of active sites and the retarded separation of photogenerated charge carriers in those developed photocata-lysts,photocatalyticCO_(2)splitting into value-added chemicals has suffered from the poor activity and remained in great challenge for real ***,hydrothermally synthesized BiOCl with layered structure(BOC-NSs)was exfoliated into thickness reduced nanosheets(BOCNSs-w)and even atomic layers(BOCNSs-i)via ultrasonication in water and isopro-panol,*** comparison with the pristine BOCNSs,the exfoli-ated BiOCl,especially BOCNSs-i with atomically layered structure,exhibits much improved photocatalytic activity forCO_(2)overall splitting to produce CO andO_(2) at a stoichiometric ratio of 2:1,with CO evolution rate reaching 134.8µmolg^(-1)h^(-1) under simulated solar light(1.7 suns).By surpassing the photocatalytic performances of the state-of-the-artBi_(l)O_(m)X_(n)(X:Cl,Br,I)based photocatalysts,the CO evolution rate is further increased by 99 times,reaching 13.3 mmolg^(-1)h^(-1) under concentrated solar irradiation(34 suns).This excellent photocatalytic performance achieved over BOCNSs-i should be benefited from the shortened transfer distance and the increased built-in electric field intensity,which acceler-ates the migration of photogenerated charge carriers to ***,with oxygen vacancies(VO)introduced into the atomic layers,BOCNSs-i is exposed with the electrons enriched Bi active sites that could transfer electrons to activateCO_(2)molecules for highly efficient and selective CO production,by lowering the energy barrier of rate-determining step(RDS),*OH+*CO_(2)-→HCO_(3)-.It is also realized that theH_(2)O vapor supplied during photocatalytic reaction would exchange oxygen atoms withCO_(2),which could alter the reaction path-ways and further reduce the energy barrier of RDS,contributing to the dramatically improved photocatalytic performance forCO_(2)overall splitting to CO andO_(2).
Designing high efficacy photocatalysts is a promising way to improve solar fuel production *** this work,we prepared a core/shell composite of loose ZnCr layered double hydroxide nanosheets modified CdS nanorods for e...
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Designing high efficacy photocatalysts is a promising way to improve solar fuel production *** this work,we prepared a core/shell composite of loose ZnCr layered double hydroxide nanosheets modified CdS nanorods for efficient visible light driven photocatalytic hydrogen *** highest hydrogen production rate achieved 425.8μmol·h^(−1) without adding any noble metal cocatalyst under the visible light stimulus,which is 22.4 times that of 1 wt.%Pt-modified *** corresponding apparent quantum yield is 13.9%at 420 *** is revealed that the synergistic actions of the interfacial redox shuttle of Cr^(3+)/Cr^(δ+)and the interfacial electric field enable the efficient separation of photoinduced charge carriers between two components via a Z-scheme energy band ***,with the hydrogen evolution contribution of Zn^(2+),a remarkable improvement in photocatalytic performance was achieved in contrast to bare *** work provides an effective methodology to construct highly efficient and economically viable photocatalysts for solar H_(2)production and mechanistic study.
Porous cryptomelane-type octahedral molecular sieve(OMS-2)with mixed Mn valence and abundant lattice oxygen species has attracted much attention in volatile organic compounds(VOC)catalytic ***,complete conversion of a...
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Porous cryptomelane-type octahedral molecular sieve(OMS-2)with mixed Mn valence and abundant lattice oxygen species has attracted much attention in volatile organic compounds(VOC)catalytic ***,complete conversion of arene over OMS-2 catalysts at relatively low temperature is still a challenge due to its limited crystal structure and inferior ***,a series of PdCe/OMS-2 catalysts with different Pd/Ce molar ratios was fabricated by a facile impregnation method and the physicochemical properties of which were extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HR-TEM),B runauer-Emmett-Teller(BET)method,X-ray fluorescence(XRF),X-ray photoelectron spectroscopy(XPS),temperature programmed reduction of H2(H2-TPR),Raman,In situ diffused reflectance infrared Fourier transform spectra(DRIFTS),and density functional theory(DFT)*** show that the total conversion of toluene can be achieved at 207℃ over PdCe2 with apparent activation energy as low as 62.6 kJ/*** strong synergistic effect between Pd and Ce remarkably boosts the catalytic activity of OMS-2,attributed to the abundant Mn^(3+)-O bands and active surface oxygen *** results reveal that oxygen vacancy can be formed over PdCe2 much easily than that of Pd/OMS-2 and Ce/OMS-2 with the oxygen vacancy formation energy of2.42,2.83 and 2.68 eV,*** increasing the Pd content cannot promote the catalytic activity although PdO is a critical active center in toluene *** vacancy attributed to the integrative effect of Pd,Ce and Mn species plays a promine nt role over prepared catalysts in toluene activation *** findings reported in this work showed new insights into the designing of highly efficient OMS-2catalysts for VOC deep oxidation by tuning oxygen vacancy concentration.
Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater ***,a pollen-derived biochar catalyst with a unique honeycomb-like structure,coupled with th...
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Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater ***,a pollen-derived biochar catalyst with a unique honeycomb-like structure,coupled with the dispersion of magnetic Fe_(3)O_(4)/FeS(Fe/S)nanoparticles,was synthesized by simple impregnation precursor,followed by *** prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range,with 98%of which eliminated even under neutral conditions(pH 7.0).The high catalytic activity was due to the multilevel porous structure of pollenderived biochar provided enough active sites and allowed for better electron transfer,then increases oxidation ability to promote the ***,the acid microenvironment formed by SO_(4)^(2-)group from Fe/S composite extended the pH range for Fenton reaction,and S^(2-)facilitated the conversion of≡Fe^(3+)to≡Fe^(2+),resulting in remarkable degradation ***,biochar can effectively promote cycling stability by limiting Fe *** work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.
Selective oxidation of alkanes to produce highvalue chemicals is an essential strategy and means to realize efficient utilization of *** this work,a strategy of lanthanum manganese mixed metal oxides(LMMO)regulated vi...
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Selective oxidation of alkanes to produce highvalue chemicals is an essential strategy and means to realize efficient utilization of *** this work,a strategy of lanthanum manganese mixed metal oxides(LMMO)regulated via a facile ionic liquid(IL)-assisted hydrothermal method was proposed to construct the multifunctional catalysts,which exhibited excellent catalytic performance in the selective aerobic oxidation of *** 8.9%cyclohexane conversion with 90%KA oi(cyclohexanol and cyclohexanone)selectivity was achieved over the optimal LMMO catalyst under mild *** effects of anion type,carbon chain length and concentration of ILs on the structure and properties of catalysts were investigated through various characterizations,indicating the structure-directing and template effect of ILs on the multifunctional *** formation of self-assembled spherical nanoparticles followed the"dissolution-nucleation-proliferation"mechanism with the introduction of 1-butyl-3-methylimidazolium hydrogen sulfate,ascribing the synergistic effect between the microenvironment of ILs and the hydrothermal ***,the high reactive oxygen concentration redox capacity,and suitable basic sites of LMMO catalysts mediated by ILs enhance the activation of C-H bonds and molecular oxygen,simultaneously influencing the adsorption and desorption of the substrate.A comprehensive understanding of the high KA oil selectivity and radical reaction mechanism was elucidated based on in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and radical trapping *** recycling and regeneration experiments further illuminated that the removal of adsorbed cyclohexanone acting on the LMMO catalyst was the key to achieve high KA oil selectivity.
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