Low-heat Portland(LHP)cement is a new type of Portland cement that has been widely used in recent years due to its low heat of hydration,which makes it exceptional in temperature control for mass concrete construction...Low-heat Portland(LHP)cement is a new type of Portland cement that has been widely used in recent years due to its low heat of hydration,which makes it exceptional in temperature control for mass concrete construction.However,limited studies have investigated the impact of temperature and magnesium oxide(MgO)content on LHP cement-based materials.This study utilizes thermodynamic simulations to study the hydration process,pore structure,and autogenous shrinkage of LHP cement pastes with different water-to-cement ratios(0.3,0.4,and 0.5),curing temperatures(5,15,20,and 30℃),and MgO contents(mass fractions of 2%,4%,and 5%).Higher curing temperature is found to promote the hydration reactions in cement paste.Moreover,the incorporation of 4%MgO moderately decreases both porosity and dimensional shrinkage in pastes.The microstructural evolution of different LHP pastes is examined through a comparative analysis,lending insights into LHP cement-based material applications.展开更多
In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusio...In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusion mobility database, which can accurately predict the phase equilibrium, solute diffusion coefficients, specific heat capacity and latent heat release in the whole system. The results show that these parameters are not constants and their values depend on local concentration and temperature. Quantitative simulation of solidification in multicomponent alloys is almost impossible without such parameters available. In this model, the interfacial region is assumed to be a mixture of solid and liquid with the same chemical potentials, but with different composition. The anti-trapping current is also considered in the model. And this model was successfully applied to industrial A1-Cu-Mg alloy for the free equiaxed dendrite solidification process.展开更多
The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of fiv...The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Qi from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Qi were obtained, denoted as Qi-Ca-Qj and Qi-[Ob]-Qj, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.展开更多
UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechani...UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.展开更多
Propylene oxide(PO)is an important petrochemical materials used to produce downstream products such as propylene glycol(PG),polyether polyols,and dipropylene glycol(DPG).Among these,DPG is commonly used as a solvent f...Propylene oxide(PO)is an important petrochemical materials used to produce downstream products such as propylene glycol(PG),polyether polyols,and dipropylene glycol(DPG).Among these,DPG is commonly used as a solvent for fragrances,cosmetics,food additives,and detergents,and can also be served as a moisturizer in cosmetics,showing broad application prospects.The distribution of DPG isomers in the products synthesized from PO and PG has a significant impactΔrGΔrHΔfHθΔfGθPO+PG⇌DPG PO+DPG⇌TPG PG+PG⇌DPG+H_(2)O PG+DPG⇌TPG+H_(2)O on the quality of the products.Therefore,conducting thermodynamic calculation on the reaction of PO and PG to synthesize DPG can provide a theoretical basis for practical operations and product distribution regulation.So,in this paper,the thermodynamic parameters of PO,1,2-PG,H_(2)O,tripropylene glycol(TPG)and three isomers of DPG under different reaction conditions is calculated.Additionally,the,and lnK for four potential reactions at various reaction temperatures and pressures are calculated.By designing isodesmic reactions and combining the results of thermodynamic calculations,the and for the isomers of DPG are obtained,and the relative error is less than 7%.The results show that in the process of preparing DPG by PO and PG,when PO∶PG=1,the reaction temperature ranges from 298.15 to 413.15 K,and the pressure ranges from 101.325 to 506.625 kPa,the reactions of and are thermodynamically spontaneous.While the reactions of and are thermodynamically unspontaneous.The optimal reaction temperature and pressure are 413.15 K and 101.325 kPa.The thermodynamic stability of the three isomers is DPG1>DPG2>DPG3 under standard conditions.The accuracy of the computational results is verified through experimental design,and based on this,the factors affecting product distribution are analyzed.展开更多
Under certain accident conditions in particle accelerators,high-power beam irradiation may damage vacuum pipes,magnets,and other key equipment.Therefore,machine protection for high-power accelerators is critical to en...Under certain accident conditions in particle accelerators,high-power beam irradiation may damage vacuum pipes,magnets,and other key equipment.Therefore,machine protection for high-power accelerators is critical to ensure safe operation.It is important to study radiation damage to materials to support the design and operation of machine protection systems.In the shock-wave regime,a pronounced hydrodynamic tunneling effect occurs within materials.The traditional one-way coupling simulation method results in substantial errors in this regime.Therefore,a bidirectional iterative coupling simulation method was developed.This method enables the bidirectional coupling of the Monte Carlo code FLUKA and the thermodynamic program Ansys-Autodyn.Density changes are monitored during the simulations,and the updated density is promptly fed back to FLUKA.The program remodels the target with the new density distribution to calculate the new energy deposition distribution,which is then returned to Autodyn for subsequent simulations.This iterative process continues until the entire beam has completed the energy deposition process.Compared to existing methods,this automated method significantly improves the efficiency of the coupled simulations and reduces the possibility of human error.The HRMT-12 beam irradiation experiment at CERN was used for a benchmark study,and simulations were conducted and compared using different equations of state.The results demonstrate the efficiency and accuracy of this simulation method.Compared to complex and costly beam irradiation experiments,this approach is expected to provide fast and cost-effective scientific guidance for the machine protection of high-power accelerators.Considering the severe consequences of the hydrodynamic tunneling effect,machine protection components such as beam collimators,absorbers,and dump blocks should adopt low-density materials to reduce the energy deposition density.Beam dilution may be required in beam dumping systems to avoid target damage.This method can be applied to the redundancy design of such beam dumping systems.展开更多
Given the considerable global interest in the preparation of Ti and TiC,a novel reduction method for TiO_(2) in a CH_(4)-H_(2) atmosphere was proposed,and the reduction thermodynamic behavior,phase equilibrium,and ene...Given the considerable global interest in the preparation of Ti and TiC,a novel reduction method for TiO_(2) in a CH_(4)-H_(2) atmosphere was proposed,and the reduction thermodynamic behavior,phase equilibrium,and energy consumption of TiO_(2) during its reaction with a CH_(4)-H_(2) gas mixture were investigated.The results indicate that the reaction proceeds via a stepwise reduction pathway from TiO_(2) to Ti(C,O),with the Magnéli phase(TinO_(2n-1))and Ti_(3)O_(5) serving as intermediate phases.Notably,the reduction of TiO_(2) by H_(2) is more challenging than that by CH_(4),which may be attributed to the inhibitory effect of H_(2) on the surface carbon precipitation.For the complete carbonization of 1 mol TiO_(2),the total energy required at 1000,1100,and 1200℃is 1159,925,and 977 kJ/mol,respectively,which may be related to the shift of gas-phase equilibrium and the increase in side reactions at high temperatures.展开更多
Combining the phase-field method and the moving boundary method,a three-dimensional phase-field simulation was conducted for the growth and grain evolution of Ti films deposited by physical vapor deposition under diff...Combining the phase-field method and the moving boundary method,a three-dimensional phase-field simulation was conducted for the growth and grain evolution of Ti films deposited by physical vapor deposition under different deposition rates and grain orientations.The evolution of grain morphology and grain orientation was also taken into consideration.Simulation results show that at lower deposition rates,the surface of the formed Ti film exhibits a distinct oriented texture structure.The surface roughness of the Ti film is positively correlated with the grain misorientation.Moreover,the surface roughness obtained from the simulation is in good agreement with the experiment results.展开更多
The core-shell structure in bulk TiNb binary alloy was designed and studied by phase-field simulations,where various core-shell structures were obtained by precise control of the initial and boundary conditions of the...The core-shell structure in bulk TiNb binary alloy was designed and studied by phase-field simulations,where various core-shell structures were obtained by precise control of the initial and boundary conditions of the TiNb binary alloy system during spinodal decomposition,and then the formation mechanism of core-shell structure was revealed.In addition,the influences of initial temperature gradient,average temperature,and initial concentration distribution of the system on the core-shell structure were investigated.Results show that the initial concentration gradient is the key factor for forming the core-shell structure.Besides,larger initial temperature gradient and higher average temperature can promote the formation of core-shell structure,which can be stabilized by adjusting the initial concentration distribution of the Nb-rich region in TiNb binary alloy.As a theoretical basis,this research provides a novel and simple strategy for the preparation of TiNb-based alloys and other materials with peculiar core-shell structures and desirable mechanical and physical properties.展开更多
The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viabili...The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
Activation pruning reduces neural network complexity by eliminating low-importance neuron activations,yet identifying the critical pruning threshold—beyond which accuracy rapidly deteriorates—remains computationally...Activation pruning reduces neural network complexity by eliminating low-importance neuron activations,yet identifying the critical pruning threshold—beyond which accuracy rapidly deteriorates—remains computationally expensive and typically requires exhaustive search.We introduce a thermodynamics-inspired framework that treats activation distributions as energy-filtered physical systems and employs the free energy of activations as a principled evaluation metric.Phase-transition-like phenomena in the free-energy profile—such as extrema,inflection points,and curvature changes—yield reliable estimates of the critical pruning threshold,providing a theoretically grounded means of predicting sharp accuracy degradation.To further enhance efficiency,we propose a renormalized free energy technique that approximates full-evaluation free energy using only the activation distribution of the unpruned network.This eliminates repeated forward passes,dramatically reducing computational overhead and achieving speedups of up to 550×for MLPs.Extensive experiments across diverse vision architectures(MLP,CNN,ResNet,MobileNet,Vision Transformer)and text models(LSTM,BERT,ELECTRA,T5,GPT-2)on multiple datasets validate the generality,robustness,and computational efficiency of our approach.Overall,this work establishes a theoretically grounded and practically effective framework for activation pruning,bridging the gap between analytical understanding and efficient deployment of sparse neural networks.展开更多
SiO_(2)–CaO–Al_(2)O_(3)ternary inclusions are among the most common complex oxide inclusions in steel.Nevertheless,the chemical and physical properties of these composite inclusions,particularly with detailed compos...SiO_(2)–CaO–Al_(2)O_(3)ternary inclusions are among the most common complex oxide inclusions in steel.Nevertheless,the chemical and physical properties of these composite inclusions,particularly with detailed composition changes,have not been sufficiently investigated.In this study,first-principles density functional theory calculations were used to determine the electronic,mechanical,and thermodynamic properties of two stable phases in the SiO_(2)–CaO–Al_(2)O_(3)ternary inclusion system:anorthite(CaAl_(2)Si_(2)O_(8))and gehlenite(Ca_(2)Al_(2)SiO_(7)).Based on the electronic density of states analysis and band structure calculations,oxygen atoms play important roles in the electron reactivity of both phases.Young’s modulus and Poisson’s ratios were calculated and compared with those of the SiO_(2)–CaO inclusions.The Young’s moduli of CaAl_(2)Si_(2)O_(8)(101.32 GPa)and Ca_(2)Al_(2)SiO_(7)(131.43 GPa)were close to the maximum and minimum Young’s moduli of the binary oxide inclusions,respectively.With increasing temperature,the Young’s moduli of CaAl_(2)Si_(2)O_(8)and Ca_(2)Al_(2)SiO_(7)showed slight increasing and decreasing trends,respectively,whereas the Poisson’s ratio decreased.Furthermore,the thermodynamic properties,particularly temperature-related thermal expansion coefficients,were also deeply investigated.The thermal expansion coefficients of both CaAl_(2)Si_(2)O_(8)and Ca_(2)Al_(2)SiO_(7)increased rapidly with increasing temperature in the low-temperature regime above 300K.As the temperature increased,the increasing trend slowed.When the temperature reached 2000 K,the thermal expansion coefficients of CaAl_(2)Si_(2)O_(8)and Ca_(2)Al_(2)SiO_(7)respectively were 12×10^(−6)and 8.5×10^(−6)K^(−1).These findings enhance the understanding of the physical nature of ternary inclusions in steels and provide a scientific foundation for analyzing their effects on steel performance using a more comprehensive inclusion database,thereby contributing to inclusion engineering in the development of materials with superior mechanical integrity.展开更多
With the legislative development,the organic and inorganic composition separation has become the primary requirement for sewer sediment disposal,however the relevant technology has been rarely reported and the driving...With the legislative development,the organic and inorganic composition separation has become the primary requirement for sewer sediment disposal,however the relevant technology has been rarely reported and the driving mechanism was still unclear.In this study,direct disintegration of biopolymers and indirect broken of connection point were investigated on the hydrolysis and component separation.Three typical sewer sediment treatment approaches,i.e.,alkaline,thermal and cation exchange treatments were proposed,which represented the hydrolysis-driving forces of chemical hydrolysis,physical hydrolysis and innovative cation bridging break-age.The results showed that the organic and inorganic separation rates of sewer sediment driven by alkaline,thermal and cation exchange treatments reached 21.26%,23.80%,and 19.56%-48.0%,respectively,compared to 4.43%in control.The secondary structure of proteins was disrupted,transitioning from𝛼α-helix to𝛽β-turn and random coil.Meanwhile,much biopolymers were released from solid to the liquid phase.From thermody-namic perspective,sewer sediment deposition was controlled by short-range interfacial interactions described by extended Derjaguin-Landau-Verwey-Overbeek theory.Additionally,the separation of organic and inorganic components was positively correlated with the thermodynamic parameters(Corr=0.87),highlighted the robust-ness of various driving forces.And the flocculation energy barriers were 2.40(alkaline),1.60 times(thermal),and 4.02–4.97 times(cation exchange)compared to control group.The findings revealed the contrition differ-ence of direct disintegration of gelatinous biopolymers and indirect breakage of composition connection sites in sediment composition separation,filling the critical gaps in understanding the specific mechanisms of sediment biopolymer disintegration and intermolecular connection breakage.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51602229 and U2040222)the Opening Project of Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education(Tongji University)+1 种基金the Joint Fund Project of Hubei Provincial Natural Science Foundation(No.2023AFD196)the Opening Funding of Henan Key Laboratory of Green Building Materials Manufacturing and Intelligent Equipment(No.2024LGSYS02),China.
文摘Low-heat Portland(LHP)cement is a new type of Portland cement that has been widely used in recent years due to its low heat of hydration,which makes it exceptional in temperature control for mass concrete construction.However,limited studies have investigated the impact of temperature and magnesium oxide(MgO)content on LHP cement-based materials.This study utilizes thermodynamic simulations to study the hydration process,pore structure,and autogenous shrinkage of LHP cement pastes with different water-to-cement ratios(0.3,0.4,and 0.5),curing temperatures(5,15,20,and 30℃),and MgO contents(mass fractions of 2%,4%,and 5%).Higher curing temperature is found to promote the hydration reactions in cement paste.Moreover,the incorporation of 4%MgO moderately decreases both porosity and dimensional shrinkage in pastes.The microstructural evolution of different LHP pastes is examined through a comparative analysis,lending insights into LHP cement-based material applications.
基金Project(2011CB606306) supported by the National Basic Research Program of ChinaProject(51101014) supported by the National Natural Science Foundation of China
文摘In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusion mobility database, which can accurately predict the phase equilibrium, solute diffusion coefficients, specific heat capacity and latent heat release in the whole system. The results show that these parameters are not constants and their values depend on local concentration and temperature. Quantitative simulation of solidification in multicomponent alloys is almost impossible without such parameters available. In this model, the interfacial region is assumed to be a mixture of solid and liquid with the same chemical potentials, but with different composition. The anti-trapping current is also considered in the model. And this model was successfully applied to industrial A1-Cu-Mg alloy for the free equiaxed dendrite solidification process.
基金Project(2012CB722805)supported by the National Basic Research Program of ChinaProjects(50504010,50974083,51174131,51374141)supported by the National Natural Science Foundation of China+1 种基金Project(50774112)supported by the Joint Fund of NSFC and Baosteel,ChinaProject(07QA4021)supported by the Shanghai"Phosphor"Science Foundation,China
文摘The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Qi from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Qi were obtained, denoted as Qi-Ca-Qj and Qi-[Ob]-Qj, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.
基金financially supported by the National Natural Science Foundation of China(Nos.52303298 and 52233002)。
文摘UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.
基金Supported by the Natural Science Foundation of Shanxi Province(202203021221303)the Science and Technology Major Project of Shanxi Province(202005D121002)the Science and Technology Cooperation and Communication Project of Shanxi Province(202304041101016)。
文摘Propylene oxide(PO)is an important petrochemical materials used to produce downstream products such as propylene glycol(PG),polyether polyols,and dipropylene glycol(DPG).Among these,DPG is commonly used as a solvent for fragrances,cosmetics,food additives,and detergents,and can also be served as a moisturizer in cosmetics,showing broad application prospects.The distribution of DPG isomers in the products synthesized from PO and PG has a significant impactΔrGΔrHΔfHθΔfGθPO+PG⇌DPG PO+DPG⇌TPG PG+PG⇌DPG+H_(2)O PG+DPG⇌TPG+H_(2)O on the quality of the products.Therefore,conducting thermodynamic calculation on the reaction of PO and PG to synthesize DPG can provide a theoretical basis for practical operations and product distribution regulation.So,in this paper,the thermodynamic parameters of PO,1,2-PG,H_(2)O,tripropylene glycol(TPG)and three isomers of DPG under different reaction conditions is calculated.Additionally,the,and lnK for four potential reactions at various reaction temperatures and pressures are calculated.By designing isodesmic reactions and combining the results of thermodynamic calculations,the and for the isomers of DPG are obtained,and the relative error is less than 7%.The results show that in the process of preparing DPG by PO and PG,when PO∶PG=1,the reaction temperature ranges from 298.15 to 413.15 K,and the pressure ranges from 101.325 to 506.625 kPa,the reactions of and are thermodynamically spontaneous.While the reactions of and are thermodynamically unspontaneous.The optimal reaction temperature and pressure are 413.15 K and 101.325 kPa.The thermodynamic stability of the three isomers is DPG1>DPG2>DPG3 under standard conditions.The accuracy of the computational results is verified through experimental design,and based on this,the factors affecting product distribution are analyzed.
基金supported by the National Natural Science Foundation of China(No.12275196)。
文摘Under certain accident conditions in particle accelerators,high-power beam irradiation may damage vacuum pipes,magnets,and other key equipment.Therefore,machine protection for high-power accelerators is critical to ensure safe operation.It is important to study radiation damage to materials to support the design and operation of machine protection systems.In the shock-wave regime,a pronounced hydrodynamic tunneling effect occurs within materials.The traditional one-way coupling simulation method results in substantial errors in this regime.Therefore,a bidirectional iterative coupling simulation method was developed.This method enables the bidirectional coupling of the Monte Carlo code FLUKA and the thermodynamic program Ansys-Autodyn.Density changes are monitored during the simulations,and the updated density is promptly fed back to FLUKA.The program remodels the target with the new density distribution to calculate the new energy deposition distribution,which is then returned to Autodyn for subsequent simulations.This iterative process continues until the entire beam has completed the energy deposition process.Compared to existing methods,this automated method significantly improves the efficiency of the coupled simulations and reduces the possibility of human error.The HRMT-12 beam irradiation experiment at CERN was used for a benchmark study,and simulations were conducted and compared using different equations of state.The results demonstrate the efficiency and accuracy of this simulation method.Compared to complex and costly beam irradiation experiments,this approach is expected to provide fast and cost-effective scientific guidance for the machine protection of high-power accelerators.Considering the severe consequences of the hydrodynamic tunneling effect,machine protection components such as beam collimators,absorbers,and dump blocks should adopt low-density materials to reduce the energy deposition density.Beam dilution may be required in beam dumping systems to avoid target damage.This method can be applied to the redundancy design of such beam dumping systems.
文摘Given the considerable global interest in the preparation of Ti and TiC,a novel reduction method for TiO_(2) in a CH_(4)-H_(2) atmosphere was proposed,and the reduction thermodynamic behavior,phase equilibrium,and energy consumption of TiO_(2) during its reaction with a CH_(4)-H_(2) gas mixture were investigated.The results indicate that the reaction proceeds via a stepwise reduction pathway from TiO_(2) to Ti(C,O),with the Magnéli phase(TinO_(2n-1))and Ti_(3)O_(5) serving as intermediate phases.Notably,the reduction of TiO_(2) by H_(2) is more challenging than that by CH_(4),which may be attributed to the inhibitory effect of H_(2) on the surface carbon precipitation.For the complete carbonization of 1 mol TiO_(2),the total energy required at 1000,1100,and 1200℃is 1159,925,and 977 kJ/mol,respectively,which may be related to the shift of gas-phase equilibrium and the increase in side reactions at high temperatures.
基金National MCF Energy R&D Program of China(2018YFE0306100)Natural Science Foundation of Hunan Province for Distinguished Young Scholars(2021JJ10062)+1 种基金National Natural Science Foundation of China(52101028)China Postdoctoral Science Foundation(2021M703628)。
文摘Combining the phase-field method and the moving boundary method,a three-dimensional phase-field simulation was conducted for the growth and grain evolution of Ti films deposited by physical vapor deposition under different deposition rates and grain orientations.The evolution of grain morphology and grain orientation was also taken into consideration.Simulation results show that at lower deposition rates,the surface of the formed Ti film exhibits a distinct oriented texture structure.The surface roughness of the Ti film is positively correlated with the grain misorientation.Moreover,the surface roughness obtained from the simulation is in good agreement with the experiment results.
基金National Natural Science Foundation of China(12372152)Guangdong Basic and Applied Basic Research Foundation(2023A1515011819,2024A1515012469)Shandong Provincial Natural Science Foundation(ZR2023MA058)。
文摘The core-shell structure in bulk TiNb binary alloy was designed and studied by phase-field simulations,where various core-shell structures were obtained by precise control of the initial and boundary conditions of the TiNb binary alloy system during spinodal decomposition,and then the formation mechanism of core-shell structure was revealed.In addition,the influences of initial temperature gradient,average temperature,and initial concentration distribution of the system on the core-shell structure were investigated.Results show that the initial concentration gradient is the key factor for forming the core-shell structure.Besides,larger initial temperature gradient and higher average temperature can promote the formation of core-shell structure,which can be stabilized by adjusting the initial concentration distribution of the Nb-rich region in TiNb binary alloy.As a theoretical basis,this research provides a novel and simple strategy for the preparation of TiNb-based alloys and other materials with peculiar core-shell structures and desirable mechanical and physical properties.
基金the financial support from the National Key R&D Program of China(No.2024YFC2910800)National Natural Science Foundation of China(52404336)+6 种基金China Postdoctoral Science Foundation(2024M750176)Postdoctoral Fellowship Program of CPSF(GZC20240109)the Young Elite Scientist Sponsorship Program by CAST(YESS20210090)Beijing Natural Science Foundation(J210017)the Project of SKLAM(No.KF24-14)China Baowu Low Carbon Metallurgical Technology Innovation Fund under Grant No.20210901Anhui Major Industrial Innovation Program under Contract No.AHZDCYCX-LSDT2023-01.
文摘The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金output of a research project implemented as part of the Basic Research Program at HSE University。
文摘Activation pruning reduces neural network complexity by eliminating low-importance neuron activations,yet identifying the critical pruning threshold—beyond which accuracy rapidly deteriorates—remains computationally expensive and typically requires exhaustive search.We introduce a thermodynamics-inspired framework that treats activation distributions as energy-filtered physical systems and employs the free energy of activations as a principled evaluation metric.Phase-transition-like phenomena in the free-energy profile—such as extrema,inflection points,and curvature changes—yield reliable estimates of the critical pruning threshold,providing a theoretically grounded means of predicting sharp accuracy degradation.To further enhance efficiency,we propose a renormalized free energy technique that approximates full-evaluation free energy using only the activation distribution of the unpruned network.This eliminates repeated forward passes,dramatically reducing computational overhead and achieving speedups of up to 550×for MLPs.Extensive experiments across diverse vision architectures(MLP,CNN,ResNet,MobileNet,Vision Transformer)and text models(LSTM,BERT,ELECTRA,T5,GPT-2)on multiple datasets validate the generality,robustness,and computational efficiency of our approach.Overall,this work establishes a theoretically grounded and practically effective framework for activation pruning,bridging the gap between analytical understanding and efficient deployment of sparse neural networks.
基金financially supported by the National Nat-ural Science Foundation of China(No.52404337)the Chun-hui Plan Collaborative Research Project from Chinese Edu-cation Ministry(No.HZKY20220036)+1 种基金the Guangdong Ba-sic and Applied Basic Research Foundation,China(No.2022A1515110062)the Young Elite Scientists Spon-sorship Program by China Association for Science and Tech-nology(No.YESS20220231).
文摘SiO_(2)–CaO–Al_(2)O_(3)ternary inclusions are among the most common complex oxide inclusions in steel.Nevertheless,the chemical and physical properties of these composite inclusions,particularly with detailed composition changes,have not been sufficiently investigated.In this study,first-principles density functional theory calculations were used to determine the electronic,mechanical,and thermodynamic properties of two stable phases in the SiO_(2)–CaO–Al_(2)O_(3)ternary inclusion system:anorthite(CaAl_(2)Si_(2)O_(8))and gehlenite(Ca_(2)Al_(2)SiO_(7)).Based on the electronic density of states analysis and band structure calculations,oxygen atoms play important roles in the electron reactivity of both phases.Young’s modulus and Poisson’s ratios were calculated and compared with those of the SiO_(2)–CaO inclusions.The Young’s moduli of CaAl_(2)Si_(2)O_(8)(101.32 GPa)and Ca_(2)Al_(2)SiO_(7)(131.43 GPa)were close to the maximum and minimum Young’s moduli of the binary oxide inclusions,respectively.With increasing temperature,the Young’s moduli of CaAl_(2)Si_(2)O_(8)and Ca_(2)Al_(2)SiO_(7)showed slight increasing and decreasing trends,respectively,whereas the Poisson’s ratio decreased.Furthermore,the thermodynamic properties,particularly temperature-related thermal expansion coefficients,were also deeply investigated.The thermal expansion coefficients of both CaAl_(2)Si_(2)O_(8)and Ca_(2)Al_(2)SiO_(7)increased rapidly with increasing temperature in the low-temperature regime above 300K.As the temperature increased,the increasing trend slowed.When the temperature reached 2000 K,the thermal expansion coefficients of CaAl_(2)Si_(2)O_(8)and Ca_(2)Al_(2)SiO_(7)respectively were 12×10^(−6)and 8.5×10^(−6)K^(−1).These findings enhance the understanding of the physical nature of ternary inclusions in steels and provide a scientific foundation for analyzing their effects on steel performance using a more comprehensive inclusion database,thereby contributing to inclusion engineering in the development of materials with superior mechanical integrity.
基金supported by Shaanxi Key Research and Development Program(No.2024SF-YBXM-546)the National Natural Science Foundation of China(No.52470161)the State Key Laboratory of Pollution Control and Resource Reuse Foundation(No.PCRRF21007).
文摘With the legislative development,the organic and inorganic composition separation has become the primary requirement for sewer sediment disposal,however the relevant technology has been rarely reported and the driving mechanism was still unclear.In this study,direct disintegration of biopolymers and indirect broken of connection point were investigated on the hydrolysis and component separation.Three typical sewer sediment treatment approaches,i.e.,alkaline,thermal and cation exchange treatments were proposed,which represented the hydrolysis-driving forces of chemical hydrolysis,physical hydrolysis and innovative cation bridging break-age.The results showed that the organic and inorganic separation rates of sewer sediment driven by alkaline,thermal and cation exchange treatments reached 21.26%,23.80%,and 19.56%-48.0%,respectively,compared to 4.43%in control.The secondary structure of proteins was disrupted,transitioning from𝛼α-helix to𝛽β-turn and random coil.Meanwhile,much biopolymers were released from solid to the liquid phase.From thermody-namic perspective,sewer sediment deposition was controlled by short-range interfacial interactions described by extended Derjaguin-Landau-Verwey-Overbeek theory.Additionally,the separation of organic and inorganic components was positively correlated with the thermodynamic parameters(Corr=0.87),highlighted the robust-ness of various driving forces.And the flocculation energy barriers were 2.40(alkaline),1.60 times(thermal),and 4.02–4.97 times(cation exchange)compared to control group.The findings revealed the contrition differ-ence of direct disintegration of gelatinous biopolymers and indirect breakage of composition connection sites in sediment composition separation,filling the critical gaps in understanding the specific mechanisms of sediment biopolymer disintegration and intermolecular connection breakage.
