Dynamical nonlinear excitations induced by interaction quench in a two-dimensional box-trapped Bose-Einstein condensate

Manipulating nonlinear excitations,including solitons and vortices,is an essential topic in quantum many-body physics.A new progress in this direction is a protocol proposed in[Phys.Rev.Res.2043256(2020)]to produce dark solitons in a one-dimensional atomic Bose–Einstein condensate(BEC)by quenching inter-atomic interaction.Motivated by this work,we generalize the protocol to a two-dimensional BEC and investigate the generic scenario of its post-quench dynamics.For an isotropic disk trap with a hard-wall boundary,we find that successive inward-moving ring dark solitons(RDSs)can be induced from the edge,and the number of RDSs can be controlled by tuning the ratio of the after-and before-quench interaction strength across different critical values.The role of the quench played on the profiles of the density,phase,and sound velocity is also investigated.Due to the snake instability,the RDSs then become vortex–antivortex pairs with peculiar dynamics managed by the initial density and the after-quench interaction.By tuning the geometry of the box traps,demonstrated as polygonal ones,more subtle dynamics of solitons and vortices are enabled.Our proposed protocol and the discovered rich dynamical effects on nonlinear excitations can be realized in near future cold-atom experiments.

Analysis of Quenching Resistor Effect to Improve Stability of TIA Circuit for APD-A Secondary Publication

In this paper,since the Avalanche Photo Diode(APD)for Light-to-Voltage LTV conversion uses a high voltage in the operating range unlike other Photo Diodes(PD),the quenching resistor must be connected in series to prevent overcurrent when using the Transimpedance Amplifier(TIA).In such a case,quenching resistance may affect the transfer function of the TIA circuit,resulting in serious stability.Therefore,in this paper,by analyzing the effect of APD quenching resistance on the voltage and current loop transfer function of TIA,we proposed a loop analysis and a method for determining the quenching resistance value to improve stability.A TIA circuit with quenching resistance was designed by the proposed method and its operational stability was verified through simulation and chip fabrication.

Discussion on the Free Quenching Heat Treatment Process of Automotive Leaf Springs

Free quenching of automotive leaf springs is a new technology that has gradually started to be applied in the industry in China in recent years.Only a few manufacturers are applying it in the industry.Through more than half a year of on-site practice,the changes in the hot forming of spring plates before free quenching have been explored,and finally a heat treatment process that meets the production requirements of our company has been developed,achieving normal production.

Exact solution of slow quench dynamics and nonadiabatic characterization of topological phases

Previous studies have shown that the bulk topology of single-particle systems can be captured by the band inversion surface or by the spin inversion surface emerging on the time-averaged spin polarization.Most of the studies,however,are based on the single-particle picture even though the systems are fermionic and multi-bands.Here,we study the slow quench dynamics of topological systems with all the valence bands fully occupied,and show that the concepts of band inversion surface and spin inversion surface are still valid.More importantly,the many-particle nonadiabatic quench dynamics is shown to be reduced to a new and nontrivial three-level Landau-Zener model.This nontrivial three-level Landau-Zener problem is then solved analytically by applying the integrability condition and symmetry considerations,and thus adds a new member to the few models that are exactly solvable.Based on the analytical results,the topological spin texture revealed by the time-averaged spin polarization can be applied to characterize the bulk topology and thus provides a direct comparison for future experiments.

Influence of quenching medium on the dendrite morphology,hardness,and tribological behaviour of cast Cu-Ni-Sn spinodal alloy for defence application

Cu-Ni-Sn spinodal alloys(Spinodal bronze)are potential materials with robust applications in components associated with defence applications like bearings,propellers,bushes,and shafts of heavily loaded aircraft,off-road vehicles,and warships.This paper presents a comparative study using water,Brine solution,and SAE 40 oil as the quenching media in regular bronze(Cu-6Sn)and spinodal bronze(Cu-9Ni-6Sn)alloys.Morphological analysis was conducted by optical microscopy,transmission electron microscopy(TEM),and X-ray diffraction technique(XRD)on bronze and spinodal bronze samples immersed in the three different quenching media to understand the grain size and hardness values better.Tribological analysis was performed to analyze the effect of quenching media on the wear aspects of bronze and spinodal bronze samples.The hardness value of the brine-aged spinodal bronze samples was as high as 320 Hv,and the grain size was very low in the range of 60μm.A quantitative comparison between brine-aged regular bronze and brine-aged spinodal bronze showed that the hardness(Hv)was almost 80%higher for brine-aged spinodal bronze.Further,the grain size was approximately 30%finer for spinodal bronze when compared with regular bronze.When the load was increased in spinodal bronze samples,there was an initial dip in wear rate followed by a marginal increase.There was a steady increase in friction coefficient with a rise in load for brine-aged regular bronze and spinodal bronze samples.These results indicate that brine solution is the most effective quenching medium for cast Cu-Ni-Sn spinodal alloys.

Entanglement and thermalization in the extended Bose–Hubbard model after a quantum quench: A correlation analysis

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.

100 kA/10kV thyristor stack design for the quench protection system in CRAFT

Thyristors have longer lifetimes,higher reliability,and very high voltage and current ratings and they require less maintenance than other high-power semiconductor devices.As a result,they are particularly suitable for quench protection systems(QPSs),which protect the superconducting magnets in large fusion devices from damage.In this paper,we propose a design for a 100 k A/10 k V thyristor stack supported by both theoretical and simulation-based analyses as well as experimental verification.Due to the ultrahigh electrical performance requirements imposed on the QPS by the Comprehensive Research Facility for Fusion Technology(CRAFT),three main issues must be considered:the voltage-balancing problem caused by multiple thyristors in a series structure,the increased junction temperature problem caused by extremely high currents,and the reverse recovery phenomenon that arises from the thyristor’s physical structure.Hence,a series of detailed theoretical analyses,simulations,and experiments,including a thyristor junction temperature prediction method and reverse recovery process modeling,were carried out to optimize the design.Finally,the reliability and stability of the thyristor stack were verified by a series of prototype experiments.The results confirmed the correctness and accuracy of the proposed thyristor stack design method and also indicated that the proposed thyristor stack can meet the application conditions of a 100 k A QPS in the CRAFT project.

Residual stress with asymmetric spray quenching for thick aluminum alloy plates

Solution and quenching heat treatments are generally carried out in a roller hearth furnace for large-scale thick aluminum alloy plates.However,the asymmetric or uneven spray water flow rate is inevitable under industrial production conditions,which leads to an asymmetric residual stress distribution.The spray quenching treatment was conducted on self-designed spray equipment,and the residual stress along the thickness direction was measured by a layer removal method based on deflections.Under the asymmetric spray quenching condition,the subsurface stress of the high-flow rate surface was lower than that of the low-flow rate surface,and the difference between the two subsurface stresses increased with the increase in the difference in water flow rates.The subsurface stress underneath the surface with a water flow rate of 0.60 m^(3)/h was 15.38 MPa less than that of 0.15 m^(3)/h.The simulated residual stress by finite element(FE)method of the high heat transfer coefficient(HTC)surface was less than that of the low HTC surface,which is consistent with the experimental results.The FE model can be used to analyze the strain and stress evolution and predict the quenched stress magnitude and distribution.

Effects of quantum quench on entanglement dynamics in antiferromagnetic Ising model

We study the relationship between quench dynamics of entanglement and quantum phase transition in the antiferromagnetic Ising model with the Dzyaloshinskii–Moriya(DM)interaction by using the quantum renormalization-group method and the definition of negativity.Two types of quench protocols(i)adding the DM interaction suddenly and(ii)rotating the spins around x axis are considered to drive the dynamics of the system,respectively.By comparing the behaviors of entanglement in both types of quench protocols,the effects of quench on dynamics of entanglement are studied.It is found that there is the same characteristic time at which the negativity firstly reaches its maximum although the system shows different dynamical behaviors.Especially,the characteristic time can accurately reflect the quantum phase transition from antiferromagnetic to saturated chiral phases in the system.In addition,the correlation length exponent can be obtained by exploring the nonanalytic and scaling behaviors of the derivative of the characteristic time.

Influence of two distinct quenching end-temperatures on phase development and mechanical properties in QP980 steel

Bainite microstructures have become increasingly attractive for the development of advanced high-strength steel owing to their balanced strength-plasticity properties.In this study, the final microstructure and mechanical properties of a quenching and partitioning(QP) steel sample after two distinct QP processes were analyzed.The results reveal that martensite transformation after quenching resulted in a lathed morphology with higher yield strength and hole expansion ratio.In contrast, bainite transformation after quenching resulted in the formation of a blocky microstructure composed of bainitic ferrite retained austenite and nanoscale precipitates during the subsequent phase transformation at a higher temperature.This kind of final microstructure is beneficial to the elongation of QP steel but detrimental to the hole expansion ratio.

Development and Application of Multi-phase Nitrides Bonded Silicon Carbide Lintel Blocks for Dry Quenching Furnaces

Multi-phase nitrides bonded silicon carbide lintel blocks were prepared using industrial SiC(SiC≥98 mass%,3-0.5,≤0.5 and≤0.044 mm),Si powder(Si≥98 mass%,≤0.044 mm),and SiO2 micropowder(SiO2≥96 mass%,d50=0.15 pm)as raw materials,and calcium lignosulfonate as the additive,batching,mixing,and molding on a vibration pressure molding machine,drying and then firing at 1420℃for 10 h in high-purity N2.The apparent porosity,the bulk density,the cold modulus of rupture,the hot modulus of rupture,and the linear expansion coefficient of the samples were tested.The phase composition and the microstructure of the samples at different nitriding depths(50,100,and 150 mm)were analyzed by XRD and SEM.The field application effects of the blocks were studied.The results show that:(1)the multi-phase nitrides bonded silicon carbide refractories can dynamically adjust their own phase composition and minimize structural and thermal stresses,improving the service life of key parts of dry quenching furnaces;(2)calcium lignosulfonate can improve the nitriding micro-environment of multi-phase nitrides bonded silicon carbide lintel blocks,successfully increasing the effective nitriding thickness of the blocks to 300 mm;(3)Sinosteel LI RR provides a unique concept in the design of materials and block types as well as the stable and scientific overall structure,promoting the industrialization process of dry quenching furnaces with long service life in China.

Effect of quenching and tempering processes on properties and microstructure of G115 steel

The novel martensitic heat-resistant steel G115 was designed for thick-section boiler components of ultra-supercritical(USC) power plants at 630-650 ℃.The impact of the quenching and tempering processes on the properties and microstructure of G115 steel was explored.The samples that were quenched and tempered twice had a higher tensile strength at room temperature and 650 ℃,and the impact energy was significantly improved.The strength and impact energy increased in proportion to the increase in the first quenching temperature.The microstructure differences between the single and double quenched and tempered samples were examined using metallographic microscopy and scanning electron microscopy.The grain size of the double quenched and tempered samples was finer than that of the single quenched and tempered samples, and the tempered martensite lath is more visible, as are the carbides and other precipitates, which are finer and more uniformly distributed.As the first quenching temperature increased, the grains became coarser but more uniform.

Visualization of Vapor Film Collapse Behavior with Complexity on Quenching Process by Cellular Automaton

The vapor film collapse that occurs in the quenching process is complicated and affects the heat treatment quality and its distortion.In order to incorporate it into the MBD(Model Based Development)technology required these days,it is necessary to predict the quality of heat treatment by CAE(Computer Added Engineering),shorten the product development period.The calculation of the vapor film collapses in a simple and practical time in order to improve the product performance.However,in the past,in order to formulate the vapor film collapse on a simulation,it was necessary to perform a very large amount of computational calculation CFD(computational fluid dynamics),which was a problem in terms of computer resources and the model of vapor film collapse.In addition,this phenomenon has a complexity behavior of the phenomenon in iterative processing,which also complicates the calculation.In this study,the vapor film collapse phenomenon is easily visualized using self-organized cellular automaton simulation which includes the phenomena of“vapor film thickness and its fluctuation”,“flow disturbance”,“surface step of workpiece”,and“decrease of cooling due to r shape of surface”.The average cooling state and repeated fluctuations of the cooling state were reproduced by this method.

Neutron irradiation influence on high-power thyristor device under fusion environment

Because of their economy and applicability,high-power thyristor devices are widely used in the power supply systems for large fusion devices.When high-dose neutrons produced by deuterium–tritium(D–T)fusion reactions are irradiated on a thyristor device for a long time,the electrical characteristics of the device change,which may eventually cause irreversible damage.In this study,with the thyristor switch of the commutation circuit in the quench protection system(QPS)of a fusion device as the study object,the relationship between the internal physical structure and external electrical parameters of the irradiated thyristor is established.Subsequently,a series of targeted thyristor physical simulations and neutron irradiation experiments are conducted to verify the accuracy of the theoretical analysis.In addition,the effect of irradiated thyristor electrical characteristic changes on the entire QPS is studied by accurate simulation,providing valuable guidelines for the maintenance and renovation of the QPS.

Numerical Simulation on Carburizing and Quenching of Gear Ring

The carburizing process of the gear ring was simulated by taking into account the practical carburizing and quenching techniques of the gear ring and by solving the diffusion equation. The carbon content distribution in the carburized layer was obtained. Based on the results, the quenching process of the gear ring was then simulated using the metallic thermodynamics and FEM： it was found that the carburization remarkably affects the quenching process. Microstructures and stress distributions of the gear ring in the quenching process were simulated, and the results are confirmed by experiments.

Interface Migration between Martensite and Austenite during Quenching and Partitioning (Q&P) Process

An Fe-0.2C-1.5Si-1.67Mn steel was subjected to quenching and partitioning （Q＆P） process, and the interface migration between martensite and austenite at an elevated partitioning temperature was observed. The interface migration is excluded in constrained paraequilibrium （CPE） model. Based on ＂endpoint＂ predicted by CPE model the thermodynamic condition of interface migration is analyzed, that is, the difference in the chemical potential of iron in both ferrite （martenisite） and austenite produces the driving force of the iron atoms to migrate from one phase to the other phase. In addition, the interface migration can change the austenite fraction; as a result, the austenite fraction at partitioning temperature may be higher than that at quenching temperature through the interface migration, but this phenomenon cannot be explained by CPE model.

The Mechanisms and Applications of Quorum Sensing(QS) and Quorum Quenching(QQ)

Quorum sensing(QS)is a regulatory system that regulates the behavior of microbial populations by sensing the concentration of signal molecules that are spontaneously produced and released by bacteria.The strategy of blocking the QS system and inhibiting the production of virulence factors is termed as quorum quenching(QQ).This strategy attenuates virulence without killing the pathogens,thereby weakening the selective pressure on pathogens and postponing the evolution of QQ-mediated drug resistance.In recent years,there have been significant theoretical and practical developments in the field of QS and QQ.In particular,with the development and utilization of marine resources,more and more marine microbial species have been found to be regulated by these two mechanisms,further promoting the research progress of QS and QQ.In this review,we described the diversity of QS signals and QS-related regulatory systems,and then introduced mechanisms related to QS interference,with particular emphasis on the description of natural QQ enzymes and chemicals acting as QS inhibitors.Finally,the exploitation of quorum sensing quenchers and the practical application of QQ were introduced,while some QQ strategies were proposed as promising tools in different fields such as medicine,aquaculture,agriculture and biological pollution prevention areas.

Changes in the thermodynamic properties of alkaline granite after cyclic quenching following high temperature action

During the development of hot dry rock,the research on thermal fatigue damage caused by thermal shock of cold and heat cycles is the basis that ensures the long-term utilization of geothermal resources,but there are not enough relevant studies at present.Based on this,the thermal damage tests of granite at different temperatures(250,350,450°C)and quenching cycles(1,5,10,15 cycles)were carried out.Preliminary reveals the damage mechanism and heat transfer law of the quenching cycle effect on hot dry rock.The results show that with the increase of temperature and cycles,the uneven thermal expansion of minerals and the thermal shock caused by quenching promote the crack development of granite,resulting in the decrease of P-wave velocity,thermal conductivity and uniaxial compressive strength of granite.Meanwhile,the COMSOL was used to simulate the heat transfer of hot dry rock under different heat treatment conditions.It concluded that the increase in the number of quenching cycles reduced the heat transfer capacity of the granite,especially more than 10 quenching cycles,which also reflects that the thermal fatigue damage leads to a longer time for the temperature recovery of the hot dry rock mass.In addition,the three-dimensional nonlinear fitting relationship among thermal conductivity,temperature and cycle number was established for the first time,which can better reveal the change rule of thermal conductivity after quenching thermal fatigue effect of hot dry rock.The research results provide theoretical support for hot dry rock reservoir reconstruction and production efficiency evaluation.

COUPLED NUMERICAL SIMULATION ON COLD ROLLER'S TEMPERATURE FIFLD-PHASE TRANSFORMATION - STRESS FIELD DURING ITS QUENCHING PSOCESS

Complicated changns occur inside the steel parts during quenching process. The abruptly changed boundary conditions make the temperature field,micro - structure and stress field change dramatically in very short time, and these variables take a contact interactions in the whole process. In this paper, a three dimensional non - linear mathematical model for queeching process has been founded and the numerical simulation on temperature field,microstructre and stress field has been realized.In the FEM analysis, the incremental iteration method is used to deal with such complicated nonlinear as boundary nonlinear, physical property nonlinear,transformation nonlinear etc.The effect of stress on transformation kinetics has been considered in the calculation of microstructure. In the stress field anal- ysis,a thermo- elasto - plastic model has been founded, which considers such factors as transforma- tion strain,transformation plastic strain, themal strain and the effect of temperature and transforma- tion on mechanical propertier etc. The transient temperature field, microstructure distribution and stress field of the roller on any time can be displayed vividly,and the cooling curve and the changes of stress on any position can also be given.

Design of Quenching Process for Large-sized AISI P20 Steel Block Used as Plastic Die

For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching processes of AISI P20 steel block such as oil quenching, direct water quenching, water quenching with precooling and water quenching with pre-cooling and self-tempering were numerically investigated by computer simulation based on the detailed discussion on the mathematical models of quenching processes including partial differential equations of heat transfer, thermal physical properties, latent heat, heat transfer coefficient and calculation of phase transformation, The results show that the water quenching with pre-cooling and self-tempering process can not only effectively avoid quenching cracks, but also obtain deeper harden depth than oil quenching.