The hot deformation behaviors of Ni18 Cr9 Co9 Fe5 Nb3 Mo superalloy were explored in the formation temperature range free ofγ’phase with various strain rates applied.The hot deformation behaviors are initially model...The hot deformation behaviors of Ni18 Cr9 Co9 Fe5 Nb3 Mo superalloy were explored in the formation temperature range free ofγ’phase with various strain rates applied.The hot deformation behaviors are initially modeled with Arrhenius equation which gives an average activation energy of 581.1 kJ mol^(-1).A modified Arrhenius approach,including the updated Zener-Hollomon parameter is proposed to consider the change of activation ene rgy under different deformation conditions which turns out a relatively accurate computation for activation energy of hot deformation,i.e.,the standard variance for modified model calculated in the covered deformation condition is just 35.4%of that for Arrhenius equation.The modified model also proposes a map for activation ene rgy which ranges from 571.5-589.0 kJ mol^(-1)for various deformation conditions.Microstructural features of the representative superalloy specimens were characterized by electron backscattered diffraction(EBSD)techniques in order to clarify the influence of activation energy on the microstructural formation.It is found that the Ni-based superalloy samples with higher activation energy are promoted by the degree of dynamic recrystallization which suggests that the rise in activation energy gives either a better recrystallization rate or finer grains.展开更多
The determination of intrinsic deformation parameters inducing grain refinement mechanism of dynamic recrystallization (DRX) contributes to the relative forming process design. For Ni80A superalloy, the processing map...The determination of intrinsic deformation parameters inducing grain refinement mechanism of dynamic recrystallization (DRX) contributes to the relative forming process design. For Ni80A superalloy, the processing maps were constructed by the derivation of the stress-strain data coming from a series of isothermal compression tests at temperatures of 1273^-1473 K and strain rates of 0.01-10 s^-1. According to the processing maps and microstructural validation, the deformation parameter windows with DRX mechanism were separated in an innovative deformation mechanism map. In addition, the deformation activation energy representing deformation energy barrier was introduced to further optimize such windows. Finally, the enhanced processing maps were constructed and the parameter domains corresponding to DRX mechanism and lower deformation barrier were determined as follows: at ε=0.3, domains: 1296-1350 K, 0.056-0.32 s^-1 and 1350-1375 K, 0.035-0.11 s^-1;at ε=0.5, domains: 1290-1348 K, 0.2-0.5 s^-1 and 1305-1370 K, 0.035-0.2 s^-1;at ε=0.7, domains: 1290-1355 K, 0.042-0.26 s^-1;at ε=0.9, domains: 1298-1348 K, 0.037-0.224 s^-1.展开更多
Hot compression tests were performed to investigate the hot deformation behavior of Fe–27.34Mn–8.63Al–1.03C lightweight steel and optimize the hot workability parameters. The temperature range was 900–1150℃ and t...Hot compression tests were performed to investigate the hot deformation behavior of Fe–27.34Mn–8.63Al–1.03C lightweight steel and optimize the hot workability parameters. The temperature range was 900–1150℃ and the strain rate range was 0.01–5 s^(-1)on a Gleeble-3800 thermal simulator machine. The results showed that the flow stress increased with decreasing deformation temperature and increasing strain rate. According to the constitutive equation, the activation energy of hot deformation was 422.88 kJ·mol^(-1). The relationship between the critical stress and peak stress of the tested steel was established, and a dynamic recrystallization kinetic model was thus obtained. Based on this model, the effects of strain rate and deformation temperature on the volume fraction of dynamically recrystallized grains were explored. The microstructural examination and processing map results revealed that the tested steel exhibited a good hot workability at deformation temperatures of 1010–1100℃ and strain rate of 0.01 s^(-1).展开更多
The plastic flow behavior of a newly developed high ductility magnesium alloy, Mg-4Al-2Sn-Y-Nd, was investigated by hot compression from 200 to 400 ℃ with a strain rate of 1.5×10-3 to 7.5 s-1. The results reveal...The plastic flow behavior of a newly developed high ductility magnesium alloy, Mg-4Al-2Sn-Y-Nd, was investigated by hot compression from 200 to 400 ℃ with a strain rate of 1.5×10-3 to 7.5 s-1. The results reveal that the strain rate sensitivity factor （m） of the alloy is much lower than that of the AZ31 alloy, which implies that the alloy should be more suitable for processing at high strain rate. The constitutive relationship of the alloy deformed at elevated temperature was obtained by plotting the experimental data. The stress exponent of the alloy is 10.33, which reveals that climb-controlled dislocations creep is the dominated deformation mechanism. The processing-map technique was used to determine the practical processing window. The proper deformation temperature and strain rate of the cast alloy were determined as 350-400 ℃ and 0.01-0.03 s-1, respectively.展开更多
Recent advances in battery energy storage technologies enable increasing number of photovoltaic-battery energy storage systems(PV-BESS)to be deployed and connected with current power grids.The reliable and efficient u...Recent advances in battery energy storage technologies enable increasing number of photovoltaic-battery energy storage systems(PV-BESS)to be deployed and connected with current power grids.The reliable and efficient utilization of BESS imposes an obvious technical challenge which needs to be urgently addressed.In this paper,the optimal operation of PV-BESS based power plant is investigated.The operational scenarios are firstly partitioned using a self-organizing map(SOM)clustering based approach.The revenue optimization model is adopted for the PV-BESS power plants to determine the optimal operational modes under typical conditions for a set of considerations,e.g.power generation revenue,assessing rewards/penalties as well as peak shaving/valley filling revenue.The solution is evaluated through a set of case studies,and the numerical result demonstrates the effectiveness of the suggested solution can optimally operate the BESS with the maximal revenue.展开更多
为更系统地了解生物质能源领域研究的演化趋势、现状及热点,基于Web of Science核心合集数据库进行检索,利用文献计量的方法,对1993~2023年生物质能源相关文献进行数据分析与挖掘,并结合CiteSpace软件对结果进行可视化分析.结果表明:生...为更系统地了解生物质能源领域研究的演化趋势、现状及热点,基于Web of Science核心合集数据库进行检索,利用文献计量的方法,对1993~2023年生物质能源相关文献进行数据分析与挖掘,并结合CiteSpace软件对结果进行可视化分析.结果表明:生物质能源研究正逐渐引起各国重视,研究成果稳步增长,受资助比例较大;全球围绕生物质能源研究形成了紧密的合作关系,生物质能源领域国家层面上的合作关系有明显的地域特征,研究机构层面上的合作关系受时域影响呈明显的“双星分布”;对生物质能源的研究层次由理论研究逐渐深入到物理、材料、化学、生物学的多学科交叉应用研究.生物质能碳捕集与封存技术、微生物光合制氢技术是下一阶段生物质能源研究领域的关键技术和前沿方向.展开更多
Nonlinear circuits can show multistability when a magnetic flux-dependent memristor(MFDM) or a charge-sensitive memristor(CSM) is incorporated into a one branch circuit,which helps estimate magnetic or electric field ...Nonlinear circuits can show multistability when a magnetic flux-dependent memristor(MFDM) or a charge-sensitive memristor(CSM) is incorporated into a one branch circuit,which helps estimate magnetic or electric field effects.In this paper,two different kinds of memristors are incorporated into two branch circuits composed of a capacitor and a nonlinear resistor,thus a memristive circuit with double memristive channels is designed.The circuit equations are presented,and the dynamics in this oscillator with two memristive terms are discussed.Then,the memristive oscillator is converted into a memristive map by applying linear transformation on the sampled time series for the memristive oscillator.The Hamilton energy function for the memristive oscillator is obtained by using the Helmholtz theorem,and it can be mapped from the field energy of the memristive circuit.An energy function for the dual memristive map is suggested by imposing suitable weights on the discrete energy function.The dynamical behaviors of the new memristive map are investigated,and an adaptive law is proposed to regulate the firing mode in the memristive map.This work will provide a theoretical basis and experimental guidance for oscillator-to-map transformation and discrete map energy calculation.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52034004 and 51975404)。
文摘The hot deformation behaviors of Ni18 Cr9 Co9 Fe5 Nb3 Mo superalloy were explored in the formation temperature range free ofγ’phase with various strain rates applied.The hot deformation behaviors are initially modeled with Arrhenius equation which gives an average activation energy of 581.1 kJ mol^(-1).A modified Arrhenius approach,including the updated Zener-Hollomon parameter is proposed to consider the change of activation ene rgy under different deformation conditions which turns out a relatively accurate computation for activation energy of hot deformation,i.e.,the standard variance for modified model calculated in the covered deformation condition is just 35.4%of that for Arrhenius equation.The modified model also proposes a map for activation ene rgy which ranges from 571.5-589.0 kJ mol^(-1)for various deformation conditions.Microstructural features of the representative superalloy specimens were characterized by electron backscattered diffraction(EBSD)techniques in order to clarify the influence of activation energy on the microstructural formation.It is found that the Ni-based superalloy samples with higher activation energy are promoted by the degree of dynamic recrystallization which suggests that the rise in activation energy gives either a better recrystallization rate or finer grains.
基金Project(cstc2018jcyj AX0459)supported by Chongqing Basic Research and Frontier Exploration,ChinaProject(P2017-020)supported by Open Fund Project of State Key Laboratory of Materials Processing and Die&Mould Technology,ChinaProject(SKLMTZZKT-2017M15)supported by Research Project of State Key Laboratory of Mechanical Transmission,China
文摘The determination of intrinsic deformation parameters inducing grain refinement mechanism of dynamic recrystallization (DRX) contributes to the relative forming process design. For Ni80A superalloy, the processing maps were constructed by the derivation of the stress-strain data coming from a series of isothermal compression tests at temperatures of 1273^-1473 K and strain rates of 0.01-10 s^-1. According to the processing maps and microstructural validation, the deformation parameter windows with DRX mechanism were separated in an innovative deformation mechanism map. In addition, the deformation activation energy representing deformation energy barrier was introduced to further optimize such windows. Finally, the enhanced processing maps were constructed and the parameter domains corresponding to DRX mechanism and lower deformation barrier were determined as follows: at ε=0.3, domains: 1296-1350 K, 0.056-0.32 s^-1 and 1350-1375 K, 0.035-0.11 s^-1;at ε=0.5, domains: 1290-1348 K, 0.2-0.5 s^-1 and 1305-1370 K, 0.035-0.2 s^-1;at ε=0.7, domains: 1290-1355 K, 0.042-0.26 s^-1;at ε=0.9, domains: 1298-1348 K, 0.037-0.224 s^-1.
基金financially supported by the National Natural Science Foundation of China (Nos. 52071300 and 51904278)the Special Funding Projects for Local Science and Technology Development guided by the Central Committee (No. YDZX20191400004587)+1 种基金the Key Research and Development Project of Zhejiang Province, China (No.2020C01131)the Innovation projects of colleges and universities in Shanxi Province, China (No. 2019L0577)。
文摘Hot compression tests were performed to investigate the hot deformation behavior of Fe–27.34Mn–8.63Al–1.03C lightweight steel and optimize the hot workability parameters. The temperature range was 900–1150℃ and the strain rate range was 0.01–5 s^(-1)on a Gleeble-3800 thermal simulator machine. The results showed that the flow stress increased with decreasing deformation temperature and increasing strain rate. According to the constitutive equation, the activation energy of hot deformation was 422.88 kJ·mol^(-1). The relationship between the critical stress and peak stress of the tested steel was established, and a dynamic recrystallization kinetic model was thus obtained. Based on this model, the effects of strain rate and deformation temperature on the volume fraction of dynamically recrystallized grains were explored. The microstructural examination and processing map results revealed that the tested steel exhibited a good hot workability at deformation temperatures of 1010–1100℃ and strain rate of 0.01 s^(-1).
基金Project(2011BAE22B01-1)supported by the National Key Technology R&D ProgramProject(2011DFA50903)supported by the International Science&Technology Cooperation Program of China
文摘The plastic flow behavior of a newly developed high ductility magnesium alloy, Mg-4Al-2Sn-Y-Nd, was investigated by hot compression from 200 to 400 ℃ with a strain rate of 1.5×10-3 to 7.5 s-1. The results reveal that the strain rate sensitivity factor （m） of the alloy is much lower than that of the AZ31 alloy, which implies that the alloy should be more suitable for processing at high strain rate. The constitutive relationship of the alloy deformed at elevated temperature was obtained by plotting the experimental data. The stress exponent of the alloy is 10.33, which reveals that climb-controlled dislocations creep is the dominated deformation mechanism. The processing-map technique was used to determine the practical processing window. The proper deformation temperature and strain rate of the cast alloy were determined as 350-400 ℃ and 0.01-0.03 s-1, respectively.
基金Supported by National Natural Science Foundation of China（61105089） State Key Laboratory of Robotics and System（SKLRS-2013-ZD-03） Open Foundation of the State Key Laboratory of Fluid Power Transmission and Control（GZKF-201212）
文摘Recent advances in battery energy storage technologies enable increasing number of photovoltaic-battery energy storage systems(PV-BESS)to be deployed and connected with current power grids.The reliable and efficient utilization of BESS imposes an obvious technical challenge which needs to be urgently addressed.In this paper,the optimal operation of PV-BESS based power plant is investigated.The operational scenarios are firstly partitioned using a self-organizing map(SOM)clustering based approach.The revenue optimization model is adopted for the PV-BESS power plants to determine the optimal operational modes under typical conditions for a set of considerations,e.g.power generation revenue,assessing rewards/penalties as well as peak shaving/valley filling revenue.The solution is evaluated through a set of case studies,and the numerical result demonstrates the effectiveness of the suggested solution can optimally operate the BESS with the maximal revenue.
文摘为更系统地了解生物质能源领域研究的演化趋势、现状及热点,基于Web of Science核心合集数据库进行检索,利用文献计量的方法,对1993~2023年生物质能源相关文献进行数据分析与挖掘,并结合CiteSpace软件对结果进行可视化分析.结果表明:生物质能源研究正逐渐引起各国重视,研究成果稳步增长,受资助比例较大;全球围绕生物质能源研究形成了紧密的合作关系,生物质能源领域国家层面上的合作关系有明显的地域特征,研究机构层面上的合作关系受时域影响呈明显的“双星分布”;对生物质能源的研究层次由理论研究逐渐深入到物理、材料、化学、生物学的多学科交叉应用研究.生物质能碳捕集与封存技术、微生物光合制氢技术是下一阶段生物质能源研究领域的关键技术和前沿方向.
基金supported by the National Science Foundation of China under Grant No. 12072139。
文摘Nonlinear circuits can show multistability when a magnetic flux-dependent memristor(MFDM) or a charge-sensitive memristor(CSM) is incorporated into a one branch circuit,which helps estimate magnetic or electric field effects.In this paper,two different kinds of memristors are incorporated into two branch circuits composed of a capacitor and a nonlinear resistor,thus a memristive circuit with double memristive channels is designed.The circuit equations are presented,and the dynamics in this oscillator with two memristive terms are discussed.Then,the memristive oscillator is converted into a memristive map by applying linear transformation on the sampled time series for the memristive oscillator.The Hamilton energy function for the memristive oscillator is obtained by using the Helmholtz theorem,and it can be mapped from the field energy of the memristive circuit.An energy function for the dual memristive map is suggested by imposing suitable weights on the discrete energy function.The dynamical behaviors of the new memristive map are investigated,and an adaptive law is proposed to regulate the firing mode in the memristive map.This work will provide a theoretical basis and experimental guidance for oscillator-to-map transformation and discrete map energy calculation.
