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Fast population transfer with a superconducting qutrit via non-Hermitian shortcut to adiabaticity 被引量:1
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作者 董新平 冯志波 +2 位作者 路晓静 李明 赵正印 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期228-233,共6页
Non-Hermitian dissipation dynamics,capable of turning the conventionally detrimental decoherence effects to useful resources for state engineering,is highly attractive to quantum information processing.In this work,an... Non-Hermitian dissipation dynamics,capable of turning the conventionally detrimental decoherence effects to useful resources for state engineering,is highly attractive to quantum information processing.In this work,an effective scheme is developed for implementing fast population transfer with a superconducting qutrit via the non-Hermitian shortcut to adiabaticity(STA).We first deal with aΛ-configuration interaction between the qutrit and microwave drivings,in which the dephasing-assisted qubit state inversion requiring an overlarge dephasing rate is constructed non-adiabatically.After introducing a feasible ancillary driving that directly acts upon the qubit states,the target state transfer can be well realized but with an accessible qubit dephasing rate.Moreover,a high fidelity could be numerically obtained in the considered system.The strategy could provide a new route towards the non-Hermitian shortcut operations on superconducting quantum circuits. 展开更多
关键词 population transfer superconducting qutrit non-Hermitian shortcut to adiabaticity
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Linear instability and adiabaticity of a dark state during conversion of two species of fermionic atoms to stable molecules
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作者 孟少英 陈希浩 +1 位作者 吴炜 傅立斌 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第4期99-105,共7页
In the present paper, we investigate the linear instability and adiabaticity of a dark state during conversion of two species of fermionic atoms to stable molecules through the stimulated Raman adiabatic passage aided... In the present paper, we investigate the linear instability and adiabaticity of a dark state during conversion of two species of fermionic atoms to stable molecules through the stimulated Raman adiabatic passage aided by Feshbach resonance. We analytically obtain the regions for the appearance of linear instability. Moreover, taking 40K and 6Li atom molecule conversion systems as examples, we give the unstable regions numerically. We also attempt to obtain the adiabatic criterion for this nonlinear system with classical adiabatic dynamics and study the adibaticity of the dark state with the adiabatic condition. 展开更多
关键词 linear instability adiabaticity dark state atom molecule conversion
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Lie transformation on shortcut to adiabaticity in parametric driving quantum systems
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作者 Jian-Jian Cheng Yao Du Lin Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第6期111-115,共5页
Shortcut to adiabaticity(STA) is a speedway to produce the same final state that would result in an adiabatic, infinitely slow process. Two typical techniques to engineer STA are developed by either introducing auxili... Shortcut to adiabaticity(STA) is a speedway to produce the same final state that would result in an adiabatic, infinitely slow process. Two typical techniques to engineer STA are developed by either introducing auxiliary counterdiabatic fields or finding new Hamiltonians that own dynamical invariants to constraint the system into the adiabatic paths. In this paper,an efficient method is introduced to naturally cover the above two techniques with a unified Lie algebraic framework and neatly remove the design difficulties and loose assumptions in the two techniques. A general STA scheme for different potential expansions concisely achieves with the aid of squeezing transformations. 展开更多
关键词 shortcut to adiabaticity parametric driving Lewis–Riesenfeld invariants
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On Verification of the New Criterion of Adiabaticity by Numerical Simulation of Acoustic Propagation through the Polar Front
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作者 WANG Y.Y SHANG E.C. 《Journal of Ocean University of Qingdao》 2002年第1期25-28,共4页
To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation(forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is propos... To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation(forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is proposed recently (Shang et al., 2001). In this paper, numerical simulation has been conducted for acoustic propagation through the Polar Front to verify the new criterion. Numerical results on the f (frequency) -m (mode number) plan demonstrate that the new criterion works very well for this extremely non-gradual ocean structure. 展开更多
关键词 Barents Polar Front acoustic propagation criterion of adiabaticity
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Instability, adiabaticity, and controlling effects of external fields for the dark state in a homonuclear atom tetramer conversion system
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作者 孟少英 陈希浩 +1 位作者 吴炜 傅立斌 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期125-129,共5页
In the present paper, we investigate the instability, adiabaticity, and controlling effects of external fields for a dark state in a homonuclear atom-tetramer conversion that is implemented by a generalized stimulated... In the present paper, we investigate the instability, adiabaticity, and controlling effects of external fields for a dark state in a homonuclear atom-tetramer conversion that is implemented by a generalized stimulated Raman adiabatic passage. We analytically obtain the regions for the appearance of dynamical instability and study the adiabatic evolution by a newly defined adiabatic fidelity. Moreover, the effects of the external field parameters and the spontaneous emissions on the conversion efficiency are also investigated. 展开更多
关键词 dynamical instability adiabatic fidelity dark state atom-molecule conversion
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On criterion of modal adiabaticity 被引量:4
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作者 王宁 《Science China Mathematics》 SCIE 2001年第11期1469-1476,共8页
Two new criterions of adiabaticity and two estimation formulas for backward scattering strength are derived in this paper. Numerical simulation shows that the estimations given here are better than the usual one.
关键词 criterion of adiabaticity scattering strength estimation formula
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Noncyclic nonadiabatic holonomic quantum gates via shortcuts to adiabaticity 被引量:3
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作者 Sai Li Pu Shen +1 位作者 Tao Chen Zheng-Yuan Xue 《Frontiers of physics》 SCIE CSCD 2021年第5期39-46,共8页
High-fidelity quantum gates are essential for large-scale quantum computation.However,any quantum manipulation will inevitably affected by noises,systematic errors and decoherence effects,which lead to infidelity of a... High-fidelity quantum gates are essential for large-scale quantum computation.However,any quantum manipulation will inevitably affected by noises,systematic errors and decoherence effects,which lead to infidelity of a target quantum task.Therefore,implementing high-fidelity,robust and fast quantum gates is highly desired.Here,we propose a fast and robust scheme to construct high-fidelity holonomic quantum gates for universal quantum computation based on resonant interaction of three-level quantum systems via shortcuts to adiabaticity.In our proposal,the target Hamiltonian to induce noncyclic non-Abelian geometric phases can be inversely engineered with less evolution time and demanding experimentally,leading to high-fidelity quantum gates in a simple setup.Besides,our scheme is readily realizable in physical system currently pursued for implementation of quantum computation.Therefore,our proposal represents a promising way towards fault-tolerant geometric quantum computation. 展开更多
关键词 noncyclic holonomic quantum gates shortcuts to adiabaticity Lewis-Riesenfeld invariant
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Thermal characteristic evolution of lithium-ion batteries during the whole lifecycle
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作者 Guangxu Zhang Xuezhe Wei +4 位作者 Donghai Chen Xueyuan Wang Siqi Chen Jiangong Zhu Haifeng Dai 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第5期534-547,共14页
This work extensively investigates the thermal characteristic evolution of lithium-ion batteries under different degradation paths,and the evolution mechanism through multi-angle characterization is revealed.Under dif... This work extensively investigates the thermal characteristic evolution of lithium-ion batteries under different degradation paths,and the evolution mechanism through multi-angle characterization is revealed.Under different degradation paths,the evolution trend of temperature rise rate remains unchanged with respect to depth of discharge during the adiabatic discharge process,albeit to varying degrees of alteration.The temperature rise rate changes significantly with aging during the adiabatic discharge process under low-temperature cycling and high-rate cycling paths.The total heat generation rate,irreversible heat generation rate,and reversible heat generation rate exhibit similar evolution behavior with aging under different degradation paths.The interval range of endothermic process of reversible electrochemical reactions increases and the contribution of irreversible heat to the total heat increases with aging.To further standardize the assessment of different degradation paths on the thermal characteristics,this work introduces the innovative concept of“Ampere-hour temperature rise”.In low-temperature cycling and high-rate cycling paths,the ampere-hour temperature rise increases significantly with aging,particularly accentuated with higher discharge rates.Conversely,in high-temperature cycling and high-temperature storage paths,the ampere-hour temperature rise remains relatively stable during the initial stages of aging,yet undergoes a notable increase in the later stages of aging.The multi-angle characterization reveals distinct thermal evolution behavior under different degradation paths primarily attributed to different behavior changes of severe side reactions,such as lithium plating.The findings provide crucial insights for the safe utilization and management of lithium–ion batteries throughout the whole lifecycle. 展开更多
关键词 Lithium-ion batteries Adiabatic discharge Thermal characteristics Ampere-hour temperaturerise DEGRADATION
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Direct Observation on H-Elimination Enhancement from C_(2)H_(4) through Non-Adiabatic Process by Femtosecond Laser Induced Coulomb Explosion
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作者 金无维 王春成 +6 位作者 赵晓戈 杨译章 任殿相 刘泽槿 李孝开 罗嗣佐 丁大军 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第5期17-22,共6页
Ethylene, the simplest model of a carbon-carbon double bond system, is pivotal in numerous chemical and biological processes. By employing intense infrared laser pump-probe techniques alongside coincidence measurement... Ethylene, the simplest model of a carbon-carbon double bond system, is pivotal in numerous chemical and biological processes. By employing intense infrared laser pump-probe techniques alongside coincidence measurements, we investigate the ultrafast non-adiabatic dynamics involved in the breakage of carbon-carbon double bonds and hydrogen elimination in dissociation of ethylene. Our study entails analyzing the dynamic kinetic energy release spectra to assess three bond-breaking scenarios, movements of nuclei, and structural changes around the carbon atoms. This allows us to evaluate the relaxation dynamics and characteristics of various dissociative states. Notably, we observe a significant rise in the yield of fragments resulting from C–H bond breakage with the delay time extended, suggesting non-adiabatic coupling through conical intersections from C–C bond breakage as a probable cause. 展开更多
关键词 PUMP FEMTO ADIABATIC
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Mechanical behavior of nanorubber reinforced epoxy over a wide strain rate loading
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作者 Yinggang Miao Jianping Yin +1 位作者 Wenxuan Du Lianyang Chen 《Nano Materials Science》 EI CAS CSCD 2024年第1期106-114,共9页
Nanorubber/epoxy composites containing 0,2,6 and 10 wt%nanorubber are subjected to uniaxial compression over a wide range of strain rate from 8×10^(-4) s^(-1) to~2×10^(4) s^(-1).Unexpectedly,their strain rat... Nanorubber/epoxy composites containing 0,2,6 and 10 wt%nanorubber are subjected to uniaxial compression over a wide range of strain rate from 8×10^(-4) s^(-1) to~2×10^(4) s^(-1).Unexpectedly,their strain rate sensitivity and strain hardening index increase with increasing nanorubber content.Potential mechanisms are proposed based on numerical simulations using a unit cell model.An increase in the strain rate sensitivity with increasing nanorubber content results from the fact that the nanorubber becomes less incompressible at high strain,generating a higher hydro-static pressure.Adiabatic shear localization starts to occur in the epoxy under a strain rate of 22,000 s^(-1) when the strain exceeds 0.35.The presence of nanorubber in the epoxy reduces adiabatic shear localization by preventing it from propagating. 展开更多
关键词 Strain rate Strain hardening Nano rubber EPOXY Adiabatic shearing localization
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Quantum State-Resolved Nonadiabatic Dynamics of the H+NaF→Na+HF Reaction
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作者 毛叶 陈航航 +2 位作者 杨紫江 布仁巴雅尔 陈茂笃 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第3期152-160,共9页
The H+NaF reaction is investigated at the quantum state-resolved level using the time-dependent wavepacket method based on a set of accurate diabatic potential energy surfaces.Oscillatory structures in the total react... The H+NaF reaction is investigated at the quantum state-resolved level using the time-dependent wavepacket method based on a set of accurate diabatic potential energy surfaces.Oscillatory structures in the total reaction probability indicate the presence of the short-lived intermediate complex. 展开更多
关键词 complex. ADIABATIC QUANTUM
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Recent progress on impact induced reaction mechanism of reactive alloys
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作者 Yansong Yang Chuanting Wang +5 位作者 Yuanpei Meng Yue Ma Lei Guo Yuan He Zhichao Sun Yong He 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第7期69-95,共27页
In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive effectiveness.As a new type of reactive material,r... In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive effectiveness.As a new type of reactive material,reactive alloy contains a large portion of reactive metal elements(Al,Mg,Ti,Zr,etc.),which breaks up under high-velocity impact conditions,generating a large number of high-temperature combustible fragments,which undergo a violent combustion reaction with air.Compared with traditional metal polymers(Al-PTFE)and other reactive composites,it has higher density and strength,excellent mechanical properties and broader application prospects.Currently,researchers have mainly investigated the impact energy release mechanism of reactive alloys through impact tests,and found that there are several important stages in the process of the material from fragmentation to reaction,i.e.,impact fragmentation of the material,rapid heating and combustion reaction.This paper focuses on three problems that need to be solved in the impact-induced energy release process of reactive alloys,namely:the fragmentation mechanism and size distribution law of the fragments produced by the impact of the material on the target,the relationship between the transient temperatures and the size of the fragments,and the reaction temperatures and size thresholds of the fragments to undergo the chemical reaction.The current status of the research of the above problems is reviewed,some potential directions to reveal the impact induced reaction mechanism of reactive alloy is discussed. 展开更多
关键词 Reactive alloys IMPACT FRAGMENTATION Mass and size distribution Shock temperature rise Adiabatic shear COMBUSTION
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Balancing the Quantum Speed Limit and Instantaneous Energy Cost in Adiabatic Quantum Evolution
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作者 徐建文 张宇佳 +9 位作者 郑文 蔡浩阳 周浩宇 李先科 廖绪东 张钰 李邵雄 兰栋 谭新生 于扬 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第4期7-12,共6页
Adiabatic time-optimal quantum controls are extensively used in quantum technologies to break the constraints imposed by short coherence times.However,practically it is crucial to consider the trade-off between the qu... Adiabatic time-optimal quantum controls are extensively used in quantum technologies to break the constraints imposed by short coherence times.However,practically it is crucial to consider the trade-off between the quantum evolution speed and instantaneous energy cost of process because of the constraints in the available control Hamiltonian.Here,we experimentally show that using a transmon qubit that,even in the presence of vanishing energy gaps,it is possible to reach a highly time-optimal adiabatic quantum driving at low energy cost in the whole evolution process.This validates the recently derived general solution of the quantum Zermelo navigation problem,paving the way for energy-efficient quantum control which is usually overlooked in conventional speed-up schemes,including the well-known counter-diabatic driving.By designing the control Hamiltonian based on the quantum speed limit bound quantified by the changing rate of phase in the interaction picture,we reveal the relationship between the quantum speed limit and instantaneous energy cost.Consequently,we demonstrate fast and high-fidelity quantum adiabatic processes by employing energy-efficient driving strengths,indicating a promising strategy for expanding the applications of time-optimal quantum controls in superconducting quantum circuits. 展开更多
关键词 PROCESS QUANTUM ADIABATIC
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Ion acoustic solitary waves in an adiabatic dusty plasma:Roles of superthermal electrons,ion loss and ionization
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作者 饶强华 陈辉 +1 位作者 刘三秋 陈小昌 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期337-342,共6页
We investigate propagation of dust ion acoustic solitary wave(DIASW)in a multicomponent dusty plasma with adiabatic ions,superthermal electrons,and stationary dust.The reductive perturbation method is employed to deri... We investigate propagation of dust ion acoustic solitary wave(DIASW)in a multicomponent dusty plasma with adiabatic ions,superthermal electrons,and stationary dust.The reductive perturbation method is employed to derive the damped Korteweg-de Vries(DKdV)equation which describes DIASW.The result reveals that the adiabaticity of ions significantly modifies the basic features of the DIASW.The ionization effect makes the solitary wave grow,while collisions reduce the growth rate and even lead to the damping.With the increases in ionization cross sectionΔσ/σ_(0),ion-to-electron density ratioδ_(ie)and superthermal electrons parameterκ,the effect of ionization on DIASW enhances. 展开更多
关键词 dust ion acoustic wave solitary wave IONIZATION adiabatic process
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Giant reversible barocaloric effects with high thermal cycle stability in epoxybonded(MnCoGe)_(0.96)(CuCoSn)_(0.04) composite
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作者 Yafei Kuang Kun Tao +7 位作者 Bo Yang Peng Tong Yan Zhang Zhigang Sun Kewei Zhang Dunhui Wang Jifan Hu Liang Zuo 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第11期2528-2534,共7页
Hexagonal MnMX-based(M=Co or Ni,X=Si or Ge)alloys exhibit giant reversible barocaloric effects.However,giant volume expansion would result in the as-cast MnMX ingots fragmenting into powders,and inevitably bring the d... Hexagonal MnMX-based(M=Co or Ni,X=Si or Ge)alloys exhibit giant reversible barocaloric effects.However,giant volume expansion would result in the as-cast MnMX ingots fragmenting into powders,and inevitably bring the deterioration of mechanical properties and formability.Grain fragmentation can bring degradation of structural transformation entropy change during cyclic application and removal of pressure.In this paper,giant reversible barocaloric effects with high thermal cycle stability can be achieved in the epoxy bonded(MnCoGe)0.96(CuCoSn)0.04 composite.Giant reversible isothermal entropy change of 43.0 J·kg^(−1)·K^(−1) and adiabatic temperature change from barocaloric effects(ΔT_(BCE))of 15.6 K can be obtained within a wide temperature span of 30 K at 360 MPa,which is mainly attributed to the integration of the change in the transition temperature driven by pressure of−101 K·GPa^(−1) and suitable thermal hysteresis of 11.1 K.Further,the variation of reversibleΔ_(TBCE) against the applied hydrostatic pressure reaches up to 43 K·GPa^(−1),which is at the highest level among the other reported giant barocaloric compounds.More importantly,after 60 thermal cycles,the composite does not break and the calorimetric curves coincide well,demonstrating good thermal cycle stability. 展开更多
关键词 barocaloric effects cycle stability reversible isothermal entropy change reversible adiabatic temperature change MnCoGe alloys
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Numerical Analysis of Explosion Characteristics of Vent Gas From 18650 LiFePO_(4) Batteries With Different States of Charge
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作者 Shi-Lin Wang Xu Gong +5 位作者 Li-Na Liu Yi-Tong Li Chen-Yu Zhang Le-Jun Xu Xu-Ning Feng Huai-Bin Wang 《电化学(中英文)》 CAS 北大核心 2024年第8期28-35,共8页
The combustion and explosion characteristics of lithium-ion battery vent gas is a key factor in determining the fire hazard of lithium-ion batteries.Investigating the combustion and explosion hazards of lithium-ion ba... The combustion and explosion characteristics of lithium-ion battery vent gas is a key factor in determining the fire hazard of lithium-ion batteries.Investigating the combustion and explosion hazards of lithium-ion batteries vent gas can provide guidance for rescue and protection in explosion accidents in energy storage stations and new energy vehicles,thereby promoting the application and development of lithium-ion batteries.Based on this understanding and combined with previous research on gas production from lithium-ion batteries,this article conducted a study on the combustion and explosion risks of vent gas from thermal runaway of 18650 LFP batteries with different states of charge(SOCs).The explosion limit of mixed gases affected by carbon dioxide inert gas is calculated through the“elimination”method,and the Chemkin-Pro software is used to numerically simulate the laminar flame speed and adiabatic flame temperature of the battery vent gas.And the concentration of free radicals and sensitivity coefficients of major elementary reactions in the system are analyzed to comprehensively evaluate the combustion explosion hazard of battery vent gas.The study found that the 100%SOC battery has the lowest explosion limit of the vent gas.The inhibitory elementary reaction sensitivity coefficient in the reaction system is lower and the concentration of free radicals is higher.Therefore,it has the maximum laminar flame speed and adiabatic flame temperature.The combustion and explosion hazard of battery vent gas increases with the increase of SOC,and the risk of explosion is the greatest and most harmful when SOC reaches 100%.However,the related hazards decrease to varying degrees with overcharging of the battery.This article provides a feasible method for analyzing the combustion mechanism of vent gas from lithium-ion batteries,revealing the impact of SOC on the hazardousness of battery vent gas.It provides references for the safety of storage and transportation of lithium-ion batteries,safety protection of energy storage stations,and the selection of related fire extinguishing agents. 展开更多
关键词 Combustion and explosion characteristics Explosion limit Laminar flame speed Adiabatic flame temperature Sensitivity analysis
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Highly efficient charging and discharging of three-level quantum batteries through shortcuts to adiabaticity
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作者 Fu-Quan Dou Yuan-Jin Wang Jian-An Sun 《Frontiers of physics》 SCIE CSCD 2022年第3期101-109,共9页
Quantum batteries are energy storage devices that satisfy quantum mechanical principles.How to improve the battery’s performance such as stored energy and power is a crucial element in the quantum battery.Here,we inv... Quantum batteries are energy storage devices that satisfy quantum mechanical principles.How to improve the battery’s performance such as stored energy and power is a crucial element in the quantum battery.Here,we investigate the charging and discharging dynamics of a three-level counterdiabatic stimulated Raman adiabatic passage quantum battery via shortcuts to adiabaticity,which can compensate for undesired transitions to realize a fast adiabatic evolution through the application of an additional control field to an initial Hamiltonian.The scheme can significantly speed up the charging and discharging processes of a three-level quantum battery and obtain more stored energy and higher power compared with the original stimulated Raman adiabatic passage.We explore the effect of both the amplitude and the delay time of driving fields on the performances of the quantum battery.Possible experimental implementation in superconducting circuit and nitrogen–vacancy center is also discussed. 展开更多
关键词 quantum battery charging and discharging dynamics shortcuts to adiabaticity
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Bridging the gap between resonance and adiabaticity:a compact and highly tolerant vertical coupling structure
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作者 CHUNHUI YAO QIXIANG CHENG +1 位作者 GüNTHER ROELKENS RICHARD PENTY 《Photonics Research》 SCIE EI CAS CSCD 2022年第9期2081-2090,共10页
We present a compact,highly tolerant vertical coupling structure,which can be a generic design that bridges the gap between conventional resonant couplers and adiabatic couplers for heterogeneously integrated devices.... We present a compact,highly tolerant vertical coupling structure,which can be a generic design that bridges the gap between conventional resonant couplers and adiabatic couplers for heterogeneously integrated devices.We show insights on relaxing the coupler alignment tolerance and provide a detailed design methodology.By the use of a multisegmented inverse taper structure,our design allows a certain proportion of the odd supermode to be excited during the coupling process,which simultaneously facilitates high tolerance and compactness.With a total length of 87μm,our coupler is almost threefold shorter than the state-of-the-art alignment-tolerant adiabatic couplers and outperforms them by demonstrating a more than 94%coupling efficiency(for<0.3 d B coupling loss)with±1μm misalignment tolerance,which,to our best knowledge,is a new record for III-V-on-silicon vertical couplers.Furthermore,our design has high tolerance to fabrication-induced structural deformation and ultrabroad bandwidth.These features make it particularly suitable for building densely integrated III-V-onsilicon photonic circuits with commercially available microtransfer printing assembly tools.The proposed design can be widely adopted in various integration platforms. 展开更多
关键词 coupling ADIABATIC structure
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Failure mode change and material damage with varied machining speeds:a review 被引量:2
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作者 Jianqiu Zhang Binbin He Bi Zhang 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2023年第2期36-60,共25页
High-speed machining(HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However,the underlying mechanisms of HSM have not ... High-speed machining(HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However,the underlying mechanisms of HSM have not been formally reviewed thus far. This article focuses on the solid mechanics framework of adiabatic shear band(ASB) onset and material metallurgical microstructural evolutions in HSM. The ASB onset is described using partial differential systems. Several factors in HSM were considered in the systems, and the ASB onset conditions were obtained by solving these systems or applying the perturbation method to the systems. With increasing machining speed, an ASB can be depressed and further eliminated by shock pressure. The damage observed in HSM exhibits common features. Equiaxed fine grains produced by dynamic recrystallization widely cause damage to ductile materials, and amorphization is the common microstructural evolution in brittle materials. Based on previous studies, potential mechanisms for the phenomena in HSM are proposed. These include the thickness variation of the white layer of ductile materials. These proposed mechanisms would be beneficial to deeply understanding the various phenomena in HSM. 展开更多
关键词 high-speed machining adiabatic shear band subsurface damage dynamic recrystallization
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Effect of CO_(2) dilution on laminar burning velocities,combustion characteristics and NO_(x) emissions of CH_(4)/air mixtures 被引量:2
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作者 Wenlong Dong Longkai Xiang +2 位作者 Jian Gao Bingbing Qiu Huaqiang Chu 《International Journal of Coal Science & Technology》 EI CAS CSCD 2023年第5期119-136,共18页
The laminar combustion characteristics of CH_(4)/air premixed flames with CO_(2) addition are systemically studied.Experimental measurements and numerical simulations of the laminar burning velocity(LBV)are performed ... The laminar combustion characteristics of CH_(4)/air premixed flames with CO_(2) addition are systemically studied.Experimental measurements and numerical simulations of the laminar burning velocity(LBV)are performed in CH_(4)/CO_(2)/Air flames with various CO_(2) doping ratio under equivalence ratios of 1.0–1.4.GRI 3.0 mech and Aramco mech are employed for predicting LBV,adiabatic flame temperature(AFT),important intermediate radicals(CH_(3),H,OH,O)and NO_(x) emissions(NO,NO_(2),N2O),as well as the sensitivity analysis is also conducted.The detail analysis of experiment and simulation reveals that as the CO_(2) addition increases from 0%to 40%,the LBVs and AFTs decrease monotonously.Under the same CO_(2) doping ratio,the LBVs and AFTs increase first and then decrease with the increase of equivalence ratio,and the maximum of LBV is reached at equivalence ratio of 1.05.The mole fraction tendency of important intermediates and NO_(x) with equivalence ratio and CO_(2) doping ratio are similar to the LBVs and AFTs.Reaction H+O_(2)⇔O+OH is found to be responsible for the promotion of the generation of important intermediates and NO_(x) under the equivalence ratios and CO_(2) addition through sensitivity analysis.The sensitivity coefficients of elementary reactions that the increasing of CO_(2) doping ratio promotes or inhibits formation of intermediate radicals and NO_(x) decreases. 展开更多
关键词 CO_(2)dilution Laminar burning velocity Adiabatic flame temperature Sensitivity analysis
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