In the present work,seven Mg-Zn-Ag alloys with the nominal composition of Mg_(96-x)Zn_(x)Ag_(4)(x=17,20,23,26,29,32,35 in at.%)were prepared by induction melting and single-roller melt-spinning.The X-ray diffraction(X...In the present work,seven Mg-Zn-Ag alloys with the nominal composition of Mg_(96-x)Zn_(x)Ag_(4)(x=17,20,23,26,29,32,35 in at.%)were prepared by induction melting and single-roller melt-spinning.The X-ray diffraction(XRD)analyses indicate the metallic glasses with three composition of Mg_(73)Zn_(23)Ag_(4),Mg_(70)Zn_(26)Ag_(4),and Mg_(67)Zn_(29)Ag_(4)were obtained successfully.The differential scanning calorimetry(DSC)measurement was used to obtain the characteristic temperature of Mg-Zn-Ag metallic glasses for the glass-forming ability analysis.The maximum glass transition temperature(Trg)was found to be 0.525 with a composition close to Mg_(67)Zn_(29)Ag_(4),which results in the best glass-forming ability.Moreover,the immersion test in simulated body fluid(SBF)demonstrate the relative homogeneous corrosion behavior of the Mg-Zn-Ag metallic glasses.The corrosion rate of Mg-Zn-Ag metallic glasses in SBF solution decreases with the increase of Zn content.The sample Mg_(67)Zn_(29)Ag_(4)has the lowest corrosion rate of 0.19mm/yr,which could meet the clinical application requirement well.The in vitro cell experiments show that the Madin-Darby canine kidney(MDCK)cells cultured in sample Mg_(67)Zn_(29)Ag_(4)and its extraction medium have higher activity.However,the Mg-Zn-Ag metallic glasses exhibit obvious inhibitory effect on human rhabdomyosarcoma(RD)tumor cells.The present investigations on the glass-forming ability,corrosion behavior,cytocompatibility and tumor inhibition function of the Mg-Zn-Ag based metallic glass could reveal their biomedical application possibility.展开更多
In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical...In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical system with the quadratic criterion cost function, is employed. In our approach, the model-based optimal control problem is reformulated into the input-output equations. In this way, the Hankel matrix and the observability matrix are constructed. Further, the sum squares of output error is defined. In these point of views, the least squares optimization problem is introduced, so as the differences between the real output and the model output could be calculated. Applying the first-order derivative to the sum squares of output error, the necessary condition is then derived. After some algebraic manipulations, the optimal control law is produced. By substituting this control policy into the input-output equations, the model output is updated iteratively. For illustration, an example of the direct current and alternating current converter problem is studied. As a result, the model output trajectory of the least squares solution is close to the real output with the smallest sum squares of output error. In conclusion, the efficiency and the accuracy of the approach proposed are highly presented.展开更多
Output measurement for nonlinear optimal control problems is an interesting issue. Because the structure of the real plant is complex, the output channel could give a significant response corresponding to the real pla...Output measurement for nonlinear optimal control problems is an interesting issue. Because the structure of the real plant is complex, the output channel could give a significant response corresponding to the real plant. In this paper, a least squares scheme, which is based on the Gauss-Newton algorithm, is proposed. The aim is to approximate the output that is measured from the real plant. In doing so, an appropriate output measurement from the model used is suggested. During the computation procedure, the control trajectory is updated iteratively by using the Gauss-Newton recursion scheme. Consequently, the output residual between the original output and the suggested output is minimized. Here, the linear model-based optimal control model is considered, so as the optimal control law is constructed. By feed backing the updated control trajectory into the dynamic system, the iterative solution of the model used could approximate to the correct optimal solution of the original optimal control problem, in spite of model-reality differences. For illustration, current converted and isothermal reaction rector problems are studied and the results are demonstrated. In conclusion, the efficiency of the approach proposed is highly presented.展开更多
The databases of the FactSage thermodynamic computer system have been under development for 30 years. These databases contain critically evaluated and opthnized data for thousands of compounds and hundreds of multicom...The databases of the FactSage thermodynamic computer system have been under development for 30 years. These databases contain critically evaluated and opthnized data for thousands of compounds and hundreds of multicomponent solutions of solid and liquid metals, oxides, salts, sulfides, etc. The databases are automatically accessed by user-friendly software that calculates complex multiphase equilibria in large multicomponent systems for a wide variety of possible input/output constraints. The databases for solutions have been developed by critical evaluation/optimization of all available phase equilibrium and thermodynamic data. The databases contain parameters of models specifically developed for different types of solutions involving sublattices, ordering, etc. Through the optimization process, model parameters are found which reproduce all thermodynamic and phase equilibrium data within experimental error limits and permit extrapolation into regions of tempea＇ature and composition where data are unavailable. The present article focuses on the databases for solid and liquid oxide phases involving 25 elements. A short review of the available databases is presented along with the models used for the molten slag and the solid solutions such as spinel, pyroxene, olivine, monoxide, corundum, etc. The critical evaluation/optimization procedure is outlined using examples from the Al203-SiO2-CaO-FeO-Fe2O3 system. Sample calculations are presented in which the oxide databases are used in conjunction with the FactSage databases for metallic and other phases. In particular, the use of the FactSage module for the calculation of multicomponent phase diagrams is illustrated.展开更多
The phase equilibria of the Mg–Ag–Cu ternary system at 350℃and 400℃were experimentally investigated using twenty-eight key samples.The phase equilibria and compositions in key samples were investigated using scann...The phase equilibria of the Mg–Ag–Cu ternary system at 350℃and 400℃were experimentally investigated using twenty-eight key samples.The phase equilibria and compositions in key samples were investigated using scanning electron microscopy(SEM)equipped with energydispersive spectroscopy(EDS).Powder X-ray diffraction(XRD)technique was used to analyze the crystal structure and solid solubility of compounds.Five three-phase equilibria and several two-phase equilibria have been determined at 350℃and 400℃.The solid solubility range of Cu in the compounds Mg_(3)Ag,MgAg and fcc(Ag)were examined at 350℃and 400℃.The maximum solid solubility of Ag in the compound MgCu_(2)was found to be 11.46 at.%and 11.25 at.%with a constant value of about 66 at.%Cu at 350℃and 400℃,respectively.Besides,the solid solubility limits of Ag in the compounds Mg_(2)Cu and fcc(Cu)were found to be less than 5 at.%at 350℃and 400℃.No ternary compound was observed in the present work.展开更多
This study focuses on the transient analysis of nonlinear dispersion of a polymeric pollutant ejected by an external source into a laminar pipe flow of a Newtonian liquid under axi-symmetric conditions.The influence o...This study focuses on the transient analysis of nonlinear dispersion of a polymeric pollutant ejected by an external source into a laminar pipe flow of a Newtonian liquid under axi-symmetric conditions.The influence of density variation with pollutant concentration is approximated according to the Boussinesq approximation and the nonlinear governing equations of momentum,pollutant concentration are obtained together with and Oldroyd-B constitutive model for the polymer stress.The problem is solved numerically using a semi-implicit finite difference method.Solutions are presented in graphical form for various parameter values and given in terms of fluid velocity,pollutant concentration,polymer stress components,skin friction and wall mass transfer rate.The model can be a useful tool in understanding the dynamics of industrial pollution situations arising from improper discharge of hydrocarbon pollutants into,say,water bodies.The model can also be quite useful for available necessary early warning methods for detecting or predicting the scale of pollution and hence help mitigate related damage downstream by earlier instituting relevant decontamination measures.展开更多
Reproducibility can be considered as one of the basic requirements to ensure that a given research finding is accurate and acceptable.This paper presents a new layered approach that allows scientific researchers to pr...Reproducibility can be considered as one of the basic requirements to ensure that a given research finding is accurate and acceptable.This paper presents a new layered approach that allows scientific researchers to provide a)data to fellow researchers to validate research and b)proofs of research quality to funding agencies,without revealing sensitive details associated with the same.We conclude that by integrating smart contracts,blockchain technology,and self-sovereign identity into an automated system,it is possible to assert the quality of scientific materials and validate the peer review process without the need of a central authority.展开更多
Blockchains have been around for more than ten years,and since 2015,a plethora of systems have been launched to target more flexible use cases.More recently,several enterprise blockchain systems,such as Consensys Quor...Blockchains have been around for more than ten years,and since 2015,a plethora of systems have been launched to target more flexible use cases.More recently,several enterprise blockchain systems,such as Consensys Quorum and Hyperledger Fabric,have been launched to make blockchain simpler to apply in complex organizational configurations.In this paper,we identify a specific Department of Defense use case,extrapolate requirements,and perform a thorough assessment of the different layers of the blockchain stack to identify the existing state of the art and undertake a gap analysis of the technology for this context.We describe a platform that meets many of these challenges and show how we architected,designed,and implemented a solution for this use case for deployment at NAVAIR.This solution connects transactions from two separate blockchain systems,Consensys Quorum and Hyperledger Fabric,by using a graph-based approach that preserves privacy while enabling full transparency across the military and supplier networks.展开更多
基金National Key Research and Development Program of China(2018YFC1106702)Guangdong Basic and Applied Basic Research Foundation(2020A1515011301,2019A1515110067 and 2020A1515110055)+1 种基金Shenzhen Basic Research Project(JCYJ20210324120001003,JCYJ20200109144608205 and JCYJ20200109144604020)IER Foundation(HT-JDCXY-201902 and HT-JD-CXY-201907)for financial support.
文摘In the present work,seven Mg-Zn-Ag alloys with the nominal composition of Mg_(96-x)Zn_(x)Ag_(4)(x=17,20,23,26,29,32,35 in at.%)were prepared by induction melting and single-roller melt-spinning.The X-ray diffraction(XRD)analyses indicate the metallic glasses with three composition of Mg_(73)Zn_(23)Ag_(4),Mg_(70)Zn_(26)Ag_(4),and Mg_(67)Zn_(29)Ag_(4)were obtained successfully.The differential scanning calorimetry(DSC)measurement was used to obtain the characteristic temperature of Mg-Zn-Ag metallic glasses for the glass-forming ability analysis.The maximum glass transition temperature(Trg)was found to be 0.525 with a composition close to Mg_(67)Zn_(29)Ag_(4),which results in the best glass-forming ability.Moreover,the immersion test in simulated body fluid(SBF)demonstrate the relative homogeneous corrosion behavior of the Mg-Zn-Ag metallic glasses.The corrosion rate of Mg-Zn-Ag metallic glasses in SBF solution decreases with the increase of Zn content.The sample Mg_(67)Zn_(29)Ag_(4)has the lowest corrosion rate of 0.19mm/yr,which could meet the clinical application requirement well.The in vitro cell experiments show that the Madin-Darby canine kidney(MDCK)cells cultured in sample Mg_(67)Zn_(29)Ag_(4)and its extraction medium have higher activity.However,the Mg-Zn-Ag metallic glasses exhibit obvious inhibitory effect on human rhabdomyosarcoma(RD)tumor cells.The present investigations on the glass-forming ability,corrosion behavior,cytocompatibility and tumor inhibition function of the Mg-Zn-Ag based metallic glass could reveal their biomedical application possibility.
文摘In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical system with the quadratic criterion cost function, is employed. In our approach, the model-based optimal control problem is reformulated into the input-output equations. In this way, the Hankel matrix and the observability matrix are constructed. Further, the sum squares of output error is defined. In these point of views, the least squares optimization problem is introduced, so as the differences between the real output and the model output could be calculated. Applying the first-order derivative to the sum squares of output error, the necessary condition is then derived. After some algebraic manipulations, the optimal control law is produced. By substituting this control policy into the input-output equations, the model output is updated iteratively. For illustration, an example of the direct current and alternating current converter problem is studied. As a result, the model output trajectory of the least squares solution is close to the real output with the smallest sum squares of output error. In conclusion, the efficiency and the accuracy of the approach proposed are highly presented.
文摘Output measurement for nonlinear optimal control problems is an interesting issue. Because the structure of the real plant is complex, the output channel could give a significant response corresponding to the real plant. In this paper, a least squares scheme, which is based on the Gauss-Newton algorithm, is proposed. The aim is to approximate the output that is measured from the real plant. In doing so, an appropriate output measurement from the model used is suggested. During the computation procedure, the control trajectory is updated iteratively by using the Gauss-Newton recursion scheme. Consequently, the output residual between the original output and the suggested output is minimized. Here, the linear model-based optimal control model is considered, so as the optimal control law is constructed. By feed backing the updated control trajectory into the dynamic system, the iterative solution of the model used could approximate to the correct optimal solution of the original optimal control problem, in spite of model-reality differences. For illustration, current converted and isothermal reaction rector problems are studied and the results are demonstrated. In conclusion, the efficiency of the approach proposed is highly presented.
文摘The databases of the FactSage thermodynamic computer system have been under development for 30 years. These databases contain critically evaluated and opthnized data for thousands of compounds and hundreds of multicomponent solutions of solid and liquid metals, oxides, salts, sulfides, etc. The databases are automatically accessed by user-friendly software that calculates complex multiphase equilibria in large multicomponent systems for a wide variety of possible input/output constraints. The databases for solutions have been developed by critical evaluation/optimization of all available phase equilibrium and thermodynamic data. The databases contain parameters of models specifically developed for different types of solutions involving sublattices, ordering, etc. Through the optimization process, model parameters are found which reproduce all thermodynamic and phase equilibrium data within experimental error limits and permit extrapolation into regions of tempea＇ature and composition where data are unavailable. The present article focuses on the databases for solid and liquid oxide phases involving 25 elements. A short review of the available databases is presented along with the models used for the molten slag and the solid solutions such as spinel, pyroxene, olivine, monoxide, corundum, etc. The critical evaluation/optimization procedure is outlined using examples from the Al203-SiO2-CaO-FeO-Fe2O3 system. Sample calculations are presented in which the oxide databases are used in conjunction with the FactSage databases for metallic and other phases. In particular, the use of the FactSage module for the calculation of multicomponent phase diagrams is illustrated.
基金Financial supports from the Science and Technology Project of Shenzhen city (No. JCYJ20170815153210359)。
文摘The phase equilibria of the Mg–Ag–Cu ternary system at 350℃and 400℃were experimentally investigated using twenty-eight key samples.The phase equilibria and compositions in key samples were investigated using scanning electron microscopy(SEM)equipped with energydispersive spectroscopy(EDS).Powder X-ray diffraction(XRD)technique was used to analyze the crystal structure and solid solubility of compounds.Five three-phase equilibria and several two-phase equilibria have been determined at 350℃and 400℃.The solid solubility range of Cu in the compounds Mg_(3)Ag,MgAg and fcc(Ag)were examined at 350℃and 400℃.The maximum solid solubility of Ag in the compound MgCu_(2)was found to be 11.46 at.%and 11.25 at.%with a constant value of about 66 at.%Cu at 350℃and 400℃,respectively.Besides,the solid solubility limits of Ag in the compounds Mg_(2)Cu and fcc(Cu)were found to be less than 5 at.%at 350℃and 400℃.No ternary compound was observed in the present work.
文摘This study focuses on the transient analysis of nonlinear dispersion of a polymeric pollutant ejected by an external source into a laminar pipe flow of a Newtonian liquid under axi-symmetric conditions.The influence of density variation with pollutant concentration is approximated according to the Boussinesq approximation and the nonlinear governing equations of momentum,pollutant concentration are obtained together with and Oldroyd-B constitutive model for the polymer stress.The problem is solved numerically using a semi-implicit finite difference method.Solutions are presented in graphical form for various parameter values and given in terms of fluid velocity,pollutant concentration,polymer stress components,skin friction and wall mass transfer rate.The model can be a useful tool in understanding the dynamics of industrial pollution situations arising from improper discharge of hydrocarbon pollutants into,say,water bodies.The model can also be quite useful for available necessary early warning methods for detecting or predicting the scale of pollution and hence help mitigate related damage downstream by earlier instituting relevant decontamination measures.
文摘Reproducibility can be considered as one of the basic requirements to ensure that a given research finding is accurate and acceptable.This paper presents a new layered approach that allows scientific researchers to provide a)data to fellow researchers to validate research and b)proofs of research quality to funding agencies,without revealing sensitive details associated with the same.We conclude that by integrating smart contracts,blockchain technology,and self-sovereign identity into an automated system,it is possible to assert the quality of scientific materials and validate the peer review process without the need of a central authority.
基金funding from a Phase Ⅱ SBIR grant(Contract No.N68335-20-C-0302)for the VIPART project(PO,Dr Manivannan Venkat)to support NAVAIR.
文摘Blockchains have been around for more than ten years,and since 2015,a plethora of systems have been launched to target more flexible use cases.More recently,several enterprise blockchain systems,such as Consensys Quorum and Hyperledger Fabric,have been launched to make blockchain simpler to apply in complex organizational configurations.In this paper,we identify a specific Department of Defense use case,extrapolate requirements,and perform a thorough assessment of the different layers of the blockchain stack to identify the existing state of the art and undertake a gap analysis of the technology for this context.We describe a platform that meets many of these challenges and show how we architected,designed,and implemented a solution for this use case for deployment at NAVAIR.This solution connects transactions from two separate blockchain systems,Consensys Quorum and Hyperledger Fabric,by using a graph-based approach that preserves privacy while enabling full transparency across the military and supplier networks.
