Thermalization in many-body systems,especially with strong interactions,is a central question in physics.In this work,we present a novel framework for the thermalization of interacting wave systems,distinguishing betw...Thermalization in many-body systems,especially with strong interactions,is a central question in physics.In this work,we present a novel framework for the thermalization of interacting wave systems,distinguishing between trivial(no momentum exchange)and nontrivial interactions(significant energy redistribution).This distinction leads to a statistically equivalent model with weakened interactions.By applying this to FPUT-like models,we identify a unique double scaling of thermalization times.Crucially,our findings suggest the persistence of prethermalization in strong interactions.展开更多
Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe t...Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe the energylevel occupations for the quench within the normal phase,but it fails for the quench to the superradiant phase.For the finite systems which are considered non-integrable,the post quench systems were studied by comparing with the thermal ensembles.The canonical ensembles are directly available for the quench within the normal phase.With the increasing of the target coupling strength over the equilibrium phase transition critical point,sudden changes take place for the effective temperature and the distance to the thermal ensembles.The thermalization was also studied by comparing with the results of the microcanonical ensembles.展开更多
Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended B...Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended Bose–Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for different quench parameters and different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.展开更多
We study the behaviors of thermalization in Fermi–Pasta–Ulam–Tsingou(FPUT) system with small number of particles using periodic boundary conditions. The total energy has initially equidistributed among some of the ...We study the behaviors of thermalization in Fermi–Pasta–Ulam–Tsingou(FPUT) system with small number of particles using periodic boundary conditions. The total energy has initially equidistributed among some of the lowest frequency modes. The thermalization time t_(eq) depending on system's energy density ε scales as t_(eq) ∝ε^(-4) only within a certain range of nonlinearity. In this range of nonlinearity, energies can interchange between the initial excited modes and other modes continuously with time until reaching the thermalized state. With a further decreasing nonlinearity, a steeper growth than ε^(-4) will appear. In the very weakly nonlinear regime, energies on low frequency modes are found to be frozen on large time scales. Redistribution of mode energies happens through the resonances of high frequency modes.展开更多
In the standard fusion reactors, mainly tokamaks, the mechanical gain obtained is below 1. On the other hand, there are colliding beam fusion reactors, for which, the not neutral plasma and the space charge limit the ...In the standard fusion reactors, mainly tokamaks, the mechanical gain obtained is below 1. On the other hand, there are colliding beam fusion reactors, for which, the not neutral plasma and the space charge limit the number of fusions to a very small number. Consequently, the mechanical gain is extremely low. The proposed reactor is also a colliding beam fusion reactor, configured in Stellarator, using directed beams. D+/T+ ions are injected in opposition, with electrons, at high speeds, so as to form a neutral beam. All these particles turn in a magnetic loop in form of figure of “0” (“racetrack”). The plasma is initially non-thermal but, as expected, rapidly becomes thermal, so all states between non-thermal and thermal exist in this reactor. The main advantage of this reactor is that this plasma after having been brought up near to the optimum conditions for fusion (around 68 keV), is then maintained in this state, thanks to low energy non-thermal ions (≤15 keV). So the energetic cost is low and the mechanical gain (</span><i><span style="font-family:Verdana;">Q</span></i><span style="font-family:Verdana;">) is high (</span></span><span style="font-family:Verdana;">>></span><span style="font-family:Verdana;">1). The goal of this article is to study a different type of fusion reactor, its advantages (no net plasma current inside this reactor, so no disruptive instabilities and consequently a continuous working, a relatively simple way to control the reactor thanks to the particles injectors), and its drawbacks, using a simulator tool. The finding results are valuable for possible future fusion reactors able to generate massive energy in a cleaner and safer way than fission reactors.展开更多
Holographic thermalization for a black hole surrounded by phantom dark energy is probed. The result shows that the smaller the phantom dark energy parameter is, the easier the is plasma to thermalize as the chemical p...Holographic thermalization for a black hole surrounded by phantom dark energy is probed. The result shows that the smaller the phantom dark energy parameter is, the easier the is plasma to thermalize as the chemical potential is fixed, the larger the chemical potential is, and the harder the plasma is to thermalize as the dark energy parameter is fixed. The thermalization velocity and thermalization acceleration are presented by fitting the thermalization curves.展开更多
Fission-Track Dating (FTD) has been developed as a useful technique for geological studies. Parent elements are measured by counting 235 U tracks induced by thermal neutrons. If insufficient thermalization occurs, fis...Fission-Track Dating (FTD) has been developed as a useful technique for geological studies. Parent elements are measured by counting 235 U tracks induced by thermal neutrons. If insufficient thermalization occurs, fission of 238 U and 232 Th will be induced, and further measurement error will be introduced. Therefore, whether the neutrons are well thermalized or not will affect the FTD results. Due to requirement of safe operation, the 101 reactor was terminated in 2007. By using the 492 reactor as the new thermal neutron reactor, our present paper will attempt to study the feasibility and the potential influence on FTD. By irradiating monitor glass SRM612 and CN5 in pairs, we will study the thermalization situation of the 492 reactor. Irradiated data show that thermal neutrons are not evenly distributed either in horizontal or in vertical dimension. Especially, horizontal heterogeneity is obvious. But we discovered that proper irradiation position in the reactor can meet the requirement of FTD. Under the current irradiation condition, we calculated and assessed the insufficient thermalization effects on determining fission-track ages. We found that the difference between the 232 Th/ 238 U ratios of samples and standards is the main factor to the experiment results. The results will not be affected if the 232 Th/ 238 U value of samples is equal to the standard samples. However, if the 232 Th/ 238 U ratio is larger than that of the standards, the results will be smaller than actual ages. Comparatively, the ages will be more than expected if the 232 Th/ 238 U ratio is less. Therefore, to reduce the irradiation error, we suggest either locating the position of irradiation strictly, or minimizing the influence of lateral heterogeneity by reducing the amount of each sample package. Additionally, accuracy of the experimental results can be improved by increasing standard samples to adjust ζ value and using the monitor of standard glass SRM612 and CN5 together.展开更多
The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF...The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF)argon plasma,and the temperatures were measured using a DPV-2000 monitor.A model combining the electromagnetism,thermal flow,and heat transfer characteristics of powder during in-flight heating in argon plasma was proposed.The melting processes of CeO_(2)powders of different diameters,with and without thermal resistance effect,were investigated.Results show that the heating process of CeO_(2)powder particles consists of three main stages,one of which is relevant to a dimensionless parameter known as the Biot number.When the Biot value≥0.1,thermal resistance increases significantly,especially for the larger powders.The predicted temperature of the particles at the outlet(1800–2880 K)is in good agreement with the experimental result.展开更多
Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
The influence of Hf on the precipitation behavior of γ'phase and the subsequent tensile properties of a Ni-Cr-Mo alloy after long-term thermal exposure was investigated.The results reveal that the addition of Hf ...The influence of Hf on the precipitation behavior of γ'phase and the subsequent tensile properties of a Ni-Cr-Mo alloy after long-term thermal exposure was investigated.The results reveal that the addition of Hf increases the average diameter ofγ'phases after thermal exposure at 700℃ for 5000 h,which enhances the critical resolved shear stress required for dislocations to shear the γ'phases in the Ni-Cr-Mo alloy.Simultaneously,element Hf incorporated into the γ'phases increases the lattice mismatch between the γ'and γ phase,thereby strengthening the coherency strengthening effect.These two factors collectively contribute to the enhanced strength of the alloy.Thus,Hf alloying effectively improves the yield strength of the Ni-Cr-Mo alloy after thermal exposure at 700℃.展开更多
The present work provides a facile and efficient method for producing ultrafine copper powders.Ultrafine copper powders were synthesized through a solvothermal method,utilizing ethanol both as a solvent and a reducing...The present work provides a facile and efficient method for producing ultrafine copper powders.Ultrafine copper powders were synthesized through a solvothermal method,utilizing ethanol both as a solvent and a reducing agent.Specifically,by exploiting the weak reducing property of ethanol,the copper precursor is first converted to copper oxide and then further reduced to cuprous oxide and pure copper.Such a method can effectively control the morphology and particle size of the copper powder,reduce particle aggregation,and enhance oxidation resistance.It is cost-effective and produces fewer toxic by-products.Spherical copper particles with an average particle size of about 180 nm were obtained.The initial oxidation temperature is approximately 150℃,and the resulting copper powders can be stored stably under ambient conditions for at least 5 months,demonstrating excellent oxidation resistance and thermal stability.展开更多
Copper manufactured by laser powder bed fusion(LPBF)process typically exhibits poor strength-ductility coordination,and the addition of strengthening phases is an effective way to address this issue.To explore the eff...Copper manufactured by laser powder bed fusion(LPBF)process typically exhibits poor strength-ductility coordination,and the addition of strengthening phases is an effective way to address this issue.To explore the effects of strengthening phases on Cu,Cu-carbon nanotubes(CNTs)composites were prepared using LPBF technique with Cu-CNTs mixed powder as the matrix.The formability,microstructure,mechanical properties,electrical conductivity,and thermal properties were studied.The result shows that the prepared composites have high relative density.The addition of CNTs results in inhomogeneous equiaxed grains at the edges of the molten pool and columnar grains at the center.Compared with pure copper,the overall mechanical properties of the composite are improved:tensile strength increases by 52.8%and elongation increases by 146.4%;the electrical and thermal properties are also enhanced:thermal conductivity increases by 10.8%and electrical conductivity increases by 12.7%.展开更多
Dual-layer thermal barrier coatings(TBCs)with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components.The preparation of the MoSi_(2)-Gd_(2)Zr_(2)O_(7)dual-layer TB...Dual-layer thermal barrier coatings(TBCs)with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components.The preparation of the MoSi_(2)-Gd_(2)Zr_(2)O_(7)dual-layer TBCs was designed based on the coefficient of thermal expansion and the coating functionality,and it was completed using atmospheric plasma spraying technique.The microstructure,mechanical properties,and thermal properties were analyzed.Results indicate that the adhesion of the prepared dual-layer composite TBCs is excellent,and no noticeable cracks appear at the interface.Compared with the MoSi_(2)coating with a low fracture toughness(0.88 MPa·m^(1/2)),the Gd_(2)Zr_(2)O_(7)coating exhibits higher fracture toughness(1.74 MPa·m^(1/2))and stronger resistance to crack propagation.The prepared MoSi_(2)-Gd_(2)Zr_(2)O_(7)composite coatings have a high porosity(39%),low thermal conductivity(1.020 W·(m·K)^(−1),1200℃),and low thermal diffusivity(0.249 mm^(2)/s,1200℃).Additionally,they possess a high oxygen-vacancy concentration,which ensures excellent insulation performance.展开更多
A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescenc...A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescence(TADF)properties.All calculations were performed using density functional theory(DFT)and time‑dependent density functional theory(TDDFT).Calculations for electronic structures,frontier molecular orbital characteristics(which determine the efficiency roll‑off effect of the complexes),and photophysical properties were conducted using the Gaussian 09 software package.The calculation of spin‑orbit coupling matrix elements<T|HSOC|S>,which determine the TADF properties of the complexes,was performed using the ORCA software package.The calculation results show that the auxiliary ligand tetraphenylimidodiphosphinate(tpip),a strong electron‑withdrawing group,can mitigate the efficiency roll‑off effect of the complex.Furthermore,TADF is observed in one of the designed complexes,(F_(3)Phppy)_(2)Ir(tpip),where F_(3)Phppy=2‑[4‑(2,4,6‑trifluorophenyl)phenyl]pyridine.展开更多
Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectiv...Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.展开更多
High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective he...High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.展开更多
Outlast Technologies GmbH has been awarded the WTiN Innovate Textile Award in the category Material Innovation for Aersulate®,its aerogel-infused insulation technology.The award honors outstanding achievements in...Outlast Technologies GmbH has been awarded the WTiN Innovate Textile Award in the category Material Innovation for Aersulate®,its aerogel-infused insulation technology.The award honors outstanding achievements in advanced material development and textile innovation.Aersulate® marks a significant advancement in thermal insulation.The technology integrates aerogel,whose highly porous structure efficiently traps air,delivering exceptional thermal performance at extremely low weight and minimal thickness.In AersulateR wadding,aerogel accounts for approximately 50%of the material volume,enabling superior insulation without bulk.展开更多
Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens un...Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.展开更多
The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical sim...The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.展开更多
There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with h...There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.展开更多
基金partially supported by the National Natural Science Foundation of China (Grant Nos.11925507,12047503,11975190,12247106,12005156,12247101 and 12465010)the support from the Youth Talent (Team)Project of Gansu Provincefrom the Innovation Fund from Department of Education of Gansu Province (Grant No.2023A-106)。
文摘Thermalization in many-body systems,especially with strong interactions,is a central question in physics.In this work,we present a novel framework for the thermalization of interacting wave systems,distinguishing between trivial(no momentum exchange)and nontrivial interactions(significant energy redistribution).This distinction leads to a statistically equivalent model with weakened interactions.By applying this to FPUT-like models,we identify a unique double scaling of thermalization times.Crucially,our findings suggest the persistence of prethermalization in strong interactions.
基金Project supported by the National Natural Science Foundation of China(Grant No.11147110)the Natural Science Youth Foundation of Shanxi,China(Grant No.2011021003)。
文摘Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe the energylevel occupations for the quench within the normal phase,but it fails for the quench to the superradiant phase.For the finite systems which are considered non-integrable,the post quench systems were studied by comparing with the thermal ensembles.The canonical ensembles are directly available for the quench within the normal phase.With the increasing of the target coupling strength over the equilibrium phase transition critical point,sudden changes take place for the effective temperature and the distance to the thermal ensembles.The thermalization was also studied by comparing with the results of the microcanonical ensembles.
基金supported by the National Natural Science Foundation of China (Grant No. 11147110)the Natural Science Youth Foundation of Shanxi Province, China (Grant No. 2011021003)。
文摘Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended Bose–Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for different quench parameters and different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.
基金supported by the Fundamental Research Funds for the Central Universities,China (Grant Nos. 2017B17114 and B210202152)。
文摘We study the behaviors of thermalization in Fermi–Pasta–Ulam–Tsingou(FPUT) system with small number of particles using periodic boundary conditions. The total energy has initially equidistributed among some of the lowest frequency modes. The thermalization time t_(eq) depending on system's energy density ε scales as t_(eq) ∝ε^(-4) only within a certain range of nonlinearity. In this range of nonlinearity, energies can interchange between the initial excited modes and other modes continuously with time until reaching the thermalized state. With a further decreasing nonlinearity, a steeper growth than ε^(-4) will appear. In the very weakly nonlinear regime, energies on low frequency modes are found to be frozen on large time scales. Redistribution of mode energies happens through the resonances of high frequency modes.
文摘In the standard fusion reactors, mainly tokamaks, the mechanical gain obtained is below 1. On the other hand, there are colliding beam fusion reactors, for which, the not neutral plasma and the space charge limit the number of fusions to a very small number. Consequently, the mechanical gain is extremely low. The proposed reactor is also a colliding beam fusion reactor, configured in Stellarator, using directed beams. D+/T+ ions are injected in opposition, with electrons, at high speeds, so as to form a neutral beam. All these particles turn in a magnetic loop in form of figure of “0” (“racetrack”). The plasma is initially non-thermal but, as expected, rapidly becomes thermal, so all states between non-thermal and thermal exist in this reactor. The main advantage of this reactor is that this plasma after having been brought up near to the optimum conditions for fusion (around 68 keV), is then maintained in this state, thanks to low energy non-thermal ions (≤15 keV). So the energetic cost is low and the mechanical gain (</span><i><span style="font-family:Verdana;">Q</span></i><span style="font-family:Verdana;">) is high (</span></span><span style="font-family:Verdana;">>></span><span style="font-family:Verdana;">1). The goal of this article is to study a different type of fusion reactor, its advantages (no net plasma current inside this reactor, so no disruptive instabilities and consequently a continuous working, a relatively simple way to control the reactor thanks to the particles injectors), and its drawbacks, using a simulator tool. The finding results are valuable for possible future fusion reactors able to generate massive energy in a cleaner and safer way than fission reactors.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11405016 and 11365008the China Postdoctoral Science Foundation under Grant No 2016M590138
文摘Holographic thermalization for a black hole surrounded by phantom dark energy is probed. The result shows that the smaller the phantom dark energy parameter is, the easier the is plasma to thermalize as the chemical potential is fixed, the larger the chemical potential is, and the harder the plasma is to thermalize as the dark energy parameter is fixed. The thermalization velocity and thermalization acceleration are presented by fitting the thermalization curves.
基金supported by State Key Laboratory of Earthquake Dynamics (Grant No.LED2009A05)National Natural Science Foundation of China (Grant No.41030317)
文摘Fission-Track Dating (FTD) has been developed as a useful technique for geological studies. Parent elements are measured by counting 235 U tracks induced by thermal neutrons. If insufficient thermalization occurs, fission of 238 U and 232 Th will be induced, and further measurement error will be introduced. Therefore, whether the neutrons are well thermalized or not will affect the FTD results. Due to requirement of safe operation, the 101 reactor was terminated in 2007. By using the 492 reactor as the new thermal neutron reactor, our present paper will attempt to study the feasibility and the potential influence on FTD. By irradiating monitor glass SRM612 and CN5 in pairs, we will study the thermalization situation of the 492 reactor. Irradiated data show that thermal neutrons are not evenly distributed either in horizontal or in vertical dimension. Especially, horizontal heterogeneity is obvious. But we discovered that proper irradiation position in the reactor can meet the requirement of FTD. Under the current irradiation condition, we calculated and assessed the insufficient thermalization effects on determining fission-track ages. We found that the difference between the 232 Th/ 238 U ratios of samples and standards is the main factor to the experiment results. The results will not be affected if the 232 Th/ 238 U value of samples is equal to the standard samples. However, if the 232 Th/ 238 U ratio is larger than that of the standards, the results will be smaller than actual ages. Comparatively, the ages will be more than expected if the 232 Th/ 238 U ratio is less. Therefore, to reduce the irradiation error, we suggest either locating the position of irradiation strictly, or minimizing the influence of lateral heterogeneity by reducing the amount of each sample package. Additionally, accuracy of the experimental results can be improved by increasing standard samples to adjust ζ value and using the monitor of standard glass SRM612 and CN5 together.
基金National Natural Science Foundation of China(11875039)Shanxi Scholarship Council of China(2023-033)+2 种基金Fundamental Research Program of Shanxi Province(202303021221071)China Baowu Low Carbon Metallurgical Innovation Foundation(2022)2023 Anhui Major Industrial Innovation Plan Project。
文摘The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF)argon plasma,and the temperatures were measured using a DPV-2000 monitor.A model combining the electromagnetism,thermal flow,and heat transfer characteristics of powder during in-flight heating in argon plasma was proposed.The melting processes of CeO_(2)powders of different diameters,with and without thermal resistance effect,were investigated.Results show that the heating process of CeO_(2)powder particles consists of three main stages,one of which is relevant to a dimensionless parameter known as the Biot number.When the Biot value≥0.1,thermal resistance increases significantly,especially for the larger powders.The predicted temperature of the particles at the outlet(1800–2880 K)is in good agreement with the experimental result.
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
基金National Key Research and Development Program of China(2021YFB3704103)National Natural Science Foundation of China(51571191)。
文摘The influence of Hf on the precipitation behavior of γ'phase and the subsequent tensile properties of a Ni-Cr-Mo alloy after long-term thermal exposure was investigated.The results reveal that the addition of Hf increases the average diameter ofγ'phases after thermal exposure at 700℃ for 5000 h,which enhances the critical resolved shear stress required for dislocations to shear the γ'phases in the Ni-Cr-Mo alloy.Simultaneously,element Hf incorporated into the γ'phases increases the lattice mismatch between the γ'and γ phase,thereby strengthening the coherency strengthening effect.These two factors collectively contribute to the enhanced strength of the alloy.Thus,Hf alloying effectively improves the yield strength of the Ni-Cr-Mo alloy after thermal exposure at 700℃.
文摘The present work provides a facile and efficient method for producing ultrafine copper powders.Ultrafine copper powders were synthesized through a solvothermal method,utilizing ethanol both as a solvent and a reducing agent.Specifically,by exploiting the weak reducing property of ethanol,the copper precursor is first converted to copper oxide and then further reduced to cuprous oxide and pure copper.Such a method can effectively control the morphology and particle size of the copper powder,reduce particle aggregation,and enhance oxidation resistance.It is cost-effective and produces fewer toxic by-products.Spherical copper particles with an average particle size of about 180 nm were obtained.The initial oxidation temperature is approximately 150℃,and the resulting copper powders can be stored stably under ambient conditions for at least 5 months,demonstrating excellent oxidation resistance and thermal stability.
基金National Key Research and Development Program of China(2023YFB4606400)Supported by Longmen Laboratory Frontier Exploration Topics(LMQYTSKT003)。
文摘Copper manufactured by laser powder bed fusion(LPBF)process typically exhibits poor strength-ductility coordination,and the addition of strengthening phases is an effective way to address this issue.To explore the effects of strengthening phases on Cu,Cu-carbon nanotubes(CNTs)composites were prepared using LPBF technique with Cu-CNTs mixed powder as the matrix.The formability,microstructure,mechanical properties,electrical conductivity,and thermal properties were studied.The result shows that the prepared composites have high relative density.The addition of CNTs results in inhomogeneous equiaxed grains at the edges of the molten pool and columnar grains at the center.Compared with pure copper,the overall mechanical properties of the composite are improved:tensile strength increases by 52.8%and elongation increases by 146.4%;the electrical and thermal properties are also enhanced:thermal conductivity increases by 10.8%and electrical conductivity increases by 12.7%.
基金Supported by Scientific and Technological Innovation of Shaanxi Provincial State-Owned Capital Operation Budget(2022-056)Institute's Self-Developed Technology Program(0801YK2317)+4 种基金Qin Chuangyuan Cites High-Level Innovation and Entrepreneurship Talent Program(QCYRCXM-2023-120)Qin Chuangyuan Industry Cluster Zone“Four Chains”Integration Program(2024CY-JJQ-46)National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘Dual-layer thermal barrier coatings(TBCs)with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components.The preparation of the MoSi_(2)-Gd_(2)Zr_(2)O_(7)dual-layer TBCs was designed based on the coefficient of thermal expansion and the coating functionality,and it was completed using atmospheric plasma spraying technique.The microstructure,mechanical properties,and thermal properties were analyzed.Results indicate that the adhesion of the prepared dual-layer composite TBCs is excellent,and no noticeable cracks appear at the interface.Compared with the MoSi_(2)coating with a low fracture toughness(0.88 MPa·m^(1/2)),the Gd_(2)Zr_(2)O_(7)coating exhibits higher fracture toughness(1.74 MPa·m^(1/2))and stronger resistance to crack propagation.The prepared MoSi_(2)-Gd_(2)Zr_(2)O_(7)composite coatings have a high porosity(39%),low thermal conductivity(1.020 W·(m·K)^(−1),1200℃),and low thermal diffusivity(0.249 mm^(2)/s,1200℃).Additionally,they possess a high oxygen-vacancy concentration,which ensures excellent insulation performance.
文摘A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescence(TADF)properties.All calculations were performed using density functional theory(DFT)and time‑dependent density functional theory(TDDFT).Calculations for electronic structures,frontier molecular orbital characteristics(which determine the efficiency roll‑off effect of the complexes),and photophysical properties were conducted using the Gaussian 09 software package.The calculation of spin‑orbit coupling matrix elements<T|HSOC|S>,which determine the TADF properties of the complexes,was performed using the ORCA software package.The calculation results show that the auxiliary ligand tetraphenylimidodiphosphinate(tpip),a strong electron‑withdrawing group,can mitigate the efficiency roll‑off effect of the complex.Furthermore,TADF is observed in one of the designed complexes,(F_(3)Phppy)_(2)Ir(tpip),where F_(3)Phppy=2‑[4‑(2,4,6‑trifluorophenyl)phenyl]pyridine.
文摘Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.
基金funded by King Abdullah City for Atomic and Renewable Energy(KACARE),grant number“PC-2020-1”.
文摘High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.
文摘Outlast Technologies GmbH has been awarded the WTiN Innovate Textile Award in the category Material Innovation for Aersulate®,its aerogel-infused insulation technology.The award honors outstanding achievements in advanced material development and textile innovation.Aersulate® marks a significant advancement in thermal insulation.The technology integrates aerogel,whose highly porous structure efficiently traps air,delivering exceptional thermal performance at extremely low weight and minimal thickness.In AersulateR wadding,aerogel accounts for approximately 50%of the material volume,enabling superior insulation without bulk.
基金supported by National Natural Science Foundation of China (Nos.52264006,52364004,and 52464005)the Guizhou Provincial Science and Technology Foundation (No.GCC[2022]005-1)。
文摘Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.
基金Project(51879135)supported by the Taishan Scholars Program,ChinaProject(52309130)supported by the National Natural Science Foundation of China+1 种基金Project(SKLGME023003)supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,ChinaProject(2022AH051754)supported by the Natural Science Research Project of Anhui Universities,China。
文摘The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.
基金financially supported by National Natural Science Foundation of China(No.52175321)the Fund of Key Laboratory of High Temperature Electromagnetic Materials and Structure of MOE(No.KB202505)。
文摘There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.
