Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and...Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.展开更多
Today,the e-commerce live broadcast industry has formed a huge market,and it has become one of the important ways for most netizens to purchase goods.Live streaming has brought new opportunities for e-commerce and new...Today,the e-commerce live broadcast industry has formed a huge market,and it has become one of the important ways for most netizens to purchase goods.Live streaming has brought new opportunities for e-commerce and new growth for brand value.The interaction between brands and customers has gradually expanded,in this case,the importance of value co-creation has become more and more prominent.This article will take e-commerce live broadcast marketing as the research object,and the brand value co-creation as the research perspective,then provide a direction based on the value co-creation perspective for the healthy and long-term development of e-commerce live broadcast marketing by studying and analyzing the cases of brand value co-creation.展开更多
This paper addresses the robust attitude control problem for quadrotors subject to model mismatch and disturbances.A dynamic inversion based attitude control scheme is proposed,which consists of an outer loop attitude...This paper addresses the robust attitude control problem for quadrotors subject to model mismatch and disturbances.A dynamic inversion based attitude control scheme is proposed,which consists of an outer loop attitude controller and an inner loop angular acceleration controller.The attitude controller is designed based on the Nonlinear Dynamic Inversion(NDI)to precisely linearize the nonlinear dynamics between the angular acceleration and the attitude.An onboard actuator model-based Incremental Nonlinear Dynamic Inversion(INDI)controller is designed in the angular acceleration control loop to improve the robustness against the model mismatch and disturbances.Meanwhile,the onboard actuator model with a modified structure eliminates the oscillation phenomenon when the sampling rate of the controller is higher than that of the actuator.Numerical simulations and flight tests demonstrate the effectiveness and robustness of the proposed controller in comparison with the PID controller.展开更多
基金supported by National Science and Technology Major Project (J2019-IV-0003-0070)the Natural Science Foundation of China (91860105,52074366)+4 种基金China Postdoctoral Science Foundation (2019M662799)Natural Science Foundation of Hunan Province of China (2021JJ40757)the Science and Technology Innovation Program of Hunan Province (2021RC3131)Changsha Municipal Natural Science Foundation (kq2014126)Project Supported by State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.
文摘Today,the e-commerce live broadcast industry has formed a huge market,and it has become one of the important ways for most netizens to purchase goods.Live streaming has brought new opportunities for e-commerce and new growth for brand value.The interaction between brands and customers has gradually expanded,in this case,the importance of value co-creation has become more and more prominent.This article will take e-commerce live broadcast marketing as the research object,and the brand value co-creation as the research perspective,then provide a direction based on the value co-creation perspective for the healthy and long-term development of e-commerce live broadcast marketing by studying and analyzing the cases of brand value co-creation.
基金co-supported by the National Natural Science Foundation of China(Nos.61803009,61903084)the Fundamental Research Funds for the Central Universities of China(No.YWF-20-BJ-J-542)。
文摘This paper addresses the robust attitude control problem for quadrotors subject to model mismatch and disturbances.A dynamic inversion based attitude control scheme is proposed,which consists of an outer loop attitude controller and an inner loop angular acceleration controller.The attitude controller is designed based on the Nonlinear Dynamic Inversion(NDI)to precisely linearize the nonlinear dynamics between the angular acceleration and the attitude.An onboard actuator model-based Incremental Nonlinear Dynamic Inversion(INDI)controller is designed in the angular acceleration control loop to improve the robustness against the model mismatch and disturbances.Meanwhile,the onboard actuator model with a modified structure eliminates the oscillation phenomenon when the sampling rate of the controller is higher than that of the actuator.Numerical simulations and flight tests demonstrate the effectiveness and robustness of the proposed controller in comparison with the PID controller.