The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe ...The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe plastic deformation(SPD)technique,refines microstructures by generating fine grains,uniformly dispersed fragmented particles,and a high fraction of high-angle grain boundaries(HAGBs),thereby facilitating superplastic forming at high strain rates and low temperatures.In the present work,a dual eccentric-pin tool(DEPT)FSP was employed to incorporate ZrO_(2) particles into a 6 mm thick AZ91D Mg alloy,leading to the formation of high volume{10-12}twins,dislocations,and β-Mg_(17)Al_(12) precipitates within the stirred zone.The microstructural evolution and mechanical behaviour of the stir zone under various process parameters were analysed using scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The DEPT enhanced plastic shearing and dynamic recrystallization,significantly reducing the grain size from 15.6μm to 2.35μm while promoting uniform dislocation distribution within the stir zone(SZ).Grain orientation analysis revealed a transition from basal to prismatic texture dominance(29.3% volume fraction)due to intensified radial-tangential coupling shear deformation,facilitating the activation of non-basal slip systems.The DEPT evidently improved the hardness of the SZ from 58 to 92 HV and increased tensile strength from 234 MPa to 325 MPa while maintaining an elongation of 23.8%,achieving an optimal strengthductility balance.This work presents a one-step approach for tailoring microstructural heterogeneity and enhancing mechanical properties in AZ91D/ZrO_(2) composites using the DEPT FSP technique.The method provides an effective strategy for mitigating the strength-ductility trade-off commonly observed in Mg alloys.展开更多
In order to obtain a uniform and effectively toughened poly(lactic acid)film by blending with low content of poly(ethylene octene)(POE)with high elasticity,the tailored interfacial intermolecular interaction and entan...In order to obtain a uniform and effectively toughened poly(lactic acid)film by blending with low content of poly(ethylene octene)(POE)with high elasticity,the tailored interfacial intermolecular interaction and entanglement between the two phases of the PLA/POE blend was innovatively constructed via the facile reactive melt blending process through the reaction of the epoxy/anhydride groups grafted on the POE chains with the end groups of PLA chains(PLA/GPOE-MPOE).It was observed that POE domains were embedded tightly in PLA matrix with a fuzzy interface and abundant interface transition area,and the impact fractured surface of the blend showed an obvious plastic deformation with less occurrence of fibrillation of PLA matrix or interfacial de-bonding.Compared with neat PLA and directly blended PLA/POE blends,the PLA/GPOE-MPOE blend exhibited much higher complex viscosity/storage modulus,much lower tanδvalues in the terminal region,and obvious strain-hardening behavior.The deviation in viscoelastic behavior of PLA/GPOE-MPOE from linear PLA indicated the enhanced molecular entanglement between the long-branched chains,resulting in an enhancement of the stretching ability during biaxial drawing of the blend.Uniform PLA/GPOE-MPOE films with draw ratio as high as 7×7 were obtained through biaxial stretching,which showed much higher tensile strength and the elongation at break than that of neat PLA and PLA/POE film.This work provides a facile method for fabricating toughening PLA films with application potentials.展开更多
The integration of large-scale-distributed new energy resources has led to heightened source‒load uncertainty.As energy prosumers,microgrids urgently require enhanced real-time regulation capabilities over controllabl...The integration of large-scale-distributed new energy resources has led to heightened source‒load uncertainty.As energy prosumers,microgrids urgently require enhanced real-time regulation capabilities over controllable resources amid uncertain environments,rendering real-time and rapid decision-making a critical issue.This paper proposes a tailored twin delayed deep deterministic policy gradient(TD3)reinforcement learning algorithm that explicitly accounts for source‒load uncertainty.First,following an expert experience-based methodology,Gaussian process regression was implemented using the radial basis function covariance with historical source and load data.The parameters were adaptively adjusted by maximum likelihood estimation to generate the expected curves of demand and wind‒solar power generation,along with their 95%confidence regions,which were treated as representative uncertainty scenarios.Second,the traditional scheduling model was transformed into a deep reinforcement learning(DRL)environment through a Markov process.To minimize the total operational cost of the microgrid,the tailored TD3 algorithm was applied to formulate rapid intraday scheduling decisions.Finally,simulations were conducted using real historical data from an actual region in Zhejiang province,China,to verify the efficacy of the proposed method.The results demonstrate the potential of the algorithm for achieving economic scheduling for microgrids.展开更多
基金the financial support from the Shandong Provincial Science Foundation for Outstanding Young Scholars(Grant No ZR2024YQ020)the National Natural Science Foundation of China(Grant Nos.52275349 and 52035005)+3 种基金the National Key Research and Development Program of China(Grant No 2022YFB4600902)the Excellent Young Team Project of Central Universities(No.2023QNTD002)Key Research and Development Program of Shandong Province(Grant No 2021ZLGX01)sponsored by the China/Shandong University International Postdoctoral Exchange Program.
文摘The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe plastic deformation(SPD)technique,refines microstructures by generating fine grains,uniformly dispersed fragmented particles,and a high fraction of high-angle grain boundaries(HAGBs),thereby facilitating superplastic forming at high strain rates and low temperatures.In the present work,a dual eccentric-pin tool(DEPT)FSP was employed to incorporate ZrO_(2) particles into a 6 mm thick AZ91D Mg alloy,leading to the formation of high volume{10-12}twins,dislocations,and β-Mg_(17)Al_(12) precipitates within the stirred zone.The microstructural evolution and mechanical behaviour of the stir zone under various process parameters were analysed using scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The DEPT enhanced plastic shearing and dynamic recrystallization,significantly reducing the grain size from 15.6μm to 2.35μm while promoting uniform dislocation distribution within the stir zone(SZ).Grain orientation analysis revealed a transition from basal to prismatic texture dominance(29.3% volume fraction)due to intensified radial-tangential coupling shear deformation,facilitating the activation of non-basal slip systems.The DEPT evidently improved the hardness of the SZ from 58 to 92 HV and increased tensile strength from 234 MPa to 325 MPa while maintaining an elongation of 23.8%,achieving an optimal strengthductility balance.This work presents a one-step approach for tailoring microstructural heterogeneity and enhancing mechanical properties in AZ91D/ZrO_(2) composites using the DEPT FSP technique.The method provides an effective strategy for mitigating the strength-ductility trade-off commonly observed in Mg alloys.
基金financially supported by the National Natural Science Foundation of China(No.51773122 and No.51933007)the International Scientific and Technological Cooperation Project of Sichuan Province(No.2020YFH0084)
文摘In order to obtain a uniform and effectively toughened poly(lactic acid)film by blending with low content of poly(ethylene octene)(POE)with high elasticity,the tailored interfacial intermolecular interaction and entanglement between the two phases of the PLA/POE blend was innovatively constructed via the facile reactive melt blending process through the reaction of the epoxy/anhydride groups grafted on the POE chains with the end groups of PLA chains(PLA/GPOE-MPOE).It was observed that POE domains were embedded tightly in PLA matrix with a fuzzy interface and abundant interface transition area,and the impact fractured surface of the blend showed an obvious plastic deformation with less occurrence of fibrillation of PLA matrix or interfacial de-bonding.Compared with neat PLA and directly blended PLA/POE blends,the PLA/GPOE-MPOE blend exhibited much higher complex viscosity/storage modulus,much lower tanδvalues in the terminal region,and obvious strain-hardening behavior.The deviation in viscoelastic behavior of PLA/GPOE-MPOE from linear PLA indicated the enhanced molecular entanglement between the long-branched chains,resulting in an enhancement of the stretching ability during biaxial drawing of the blend.Uniform PLA/GPOE-MPOE films with draw ratio as high as 7×7 were obtained through biaxial stretching,which showed much higher tensile strength and the elongation at break than that of neat PLA and PLA/POE film.This work provides a facile method for fabricating toughening PLA films with application potentials.
基金supported in part by Science and Technology Project of State Grid Corporation of China(No.5400-202319829A-4-1-KJ).
文摘The integration of large-scale-distributed new energy resources has led to heightened source‒load uncertainty.As energy prosumers,microgrids urgently require enhanced real-time regulation capabilities over controllable resources amid uncertain environments,rendering real-time and rapid decision-making a critical issue.This paper proposes a tailored twin delayed deep deterministic policy gradient(TD3)reinforcement learning algorithm that explicitly accounts for source‒load uncertainty.First,following an expert experience-based methodology,Gaussian process regression was implemented using the radial basis function covariance with historical source and load data.The parameters were adaptively adjusted by maximum likelihood estimation to generate the expected curves of demand and wind‒solar power generation,along with their 95%confidence regions,which were treated as representative uncertainty scenarios.Second,the traditional scheduling model was transformed into a deep reinforcement learning(DRL)environment through a Markov process.To minimize the total operational cost of the microgrid,the tailored TD3 algorithm was applied to formulate rapid intraday scheduling decisions.Finally,simulations were conducted using real historical data from an actual region in Zhejiang province,China,to verify the efficacy of the proposed method.The results demonstrate the potential of the algorithm for achieving economic scheduling for microgrids.
