Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology...Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.展开更多
Water-based aerosol is widely used as an effective strategy in electro-optical countermeasure on the battlefield used to the preponderance of high efficiency,low cost and eco-friendly.Unfortunately,the stability of th...Water-based aerosol is widely used as an effective strategy in electro-optical countermeasure on the battlefield used to the preponderance of high efficiency,low cost and eco-friendly.Unfortunately,the stability of the water-based aerosol is always unsatisfactory due to the rapid evaporation and sedimentation of the aerosol droplets.Great efforts have been devoted to improve the stability of water-based aerosol by using additives with different composition and proportion.However,the lack of the criterion and principle for screening the effective additives results in excessive experimental time consumption and cost.And the stabilization time of the aerosol is still only 30 min,which could not meet the requirements of the perdurable interference.Herein,to improve the stability of water-based aerosol and optimize the complex formulation efficiently,a theoretical calculation method based on thermodynamic entropy theory is proposed.All the factors that influence the shielding effect,including polyol,stabilizer,propellant,water and cosolvent,are considered within calculation.An ultra-stable water-based aerosol with long duration over 120 min is obtained with the optimal fogging agent composition,providing enough time for fighting the electro-optic weapon.Theoretical design guideline for choosing the additives with high phase transition temperature and low phase transition enthalpy is also proposed,which greatly improves the total entropy change and reduce the absolute entropy change of the aerosol cooling process,and gives rise to an enhanced stability of the water-based aerosol.The theoretical calculation methodology contributes to an abstemious time and space for sieving the water-based aerosol with desirable performance and stability,and provides the powerful guarantee to the homeland security.展开更多
The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs m...The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs makes the design of the guidance,navigation,and control(GNC)have a larger-thanbefore impact on the main-body design(shape,motor,and layout design)and its design objective,i.e.,flight performance.Pursuing a trade-off between flight performance and guidance precision,all the relevant interactions have to be accounted for in the design of the main body and the GNC system.Herein,a multi-objective and multidisciplinary design optimization(MDO)is proposed.Disciplines pertinent to motor,aerodynamics,layout,trajectory,flight dynamics,control,and guidance are included in the proposed MDO framework.The optimization problem seeks to maximize the range and minimize the guidance error.The problem is solved by using the nondominated sorting genetic algorithm II.An optimum design that balances a longer range with a smaller guidance error is obtained.Finally,lessons learned about the design of the MM and insights into the trade-off between flight performance and guidance precision are given by comparing the optimum design to a design provided by the traditional approach.展开更多
We propose a modified evolutionary computation method to solve the optimization problem of additively decomposed function with constraints. It is based on factorized distribution instead of penalty function and any tr...We propose a modified evolutionary computation method to solve the optimization problem of additively decomposed function with constraints. It is based on factorized distribution instead of penalty function and any transformation to a linear model or others. The feasibility and convergence of the new algorithm are given. The numerical results show that the new algorithm gives a satisfactory performance.展开更多
A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system ...A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.展开更多
A new type of iron-based matrix formula as a potential substitute for traditional WC-based matrix formula for hot pressed diamond bit was investigated.Iron,phosphor-iron,663-Cu,nickel,cobalt and certain additives were...A new type of iron-based matrix formula as a potential substitute for traditional WC-based matrix formula for hot pressed diamond bit was investigated.Iron,phosphor-iron,663-Cu,nickel,cobalt and certain additives were selected as the studied formula constituents.Among matrix performances,the hardness and wear resistance were chosen as experimental indexes in this paper.Constrained uniform design method was used for the formula design of iron-based matrix.Two forms of regression models of matrix hardness and wear resistance were obtained by regression analysis using MATLAB.Moreover,the optimization of matrix formulae and matrix performances were also achieved through constrained nonlinear programming.It was found that matrix hardness,significantly affected by the factor of Ni-Co-additives and Fe,increased with the increment of Ni-Co-additives,Fe and P-Fe,but reduced with the increase of 663-Cu.On the other hand,matrix wear resistance is mainly affected by Fe;the effect of the interaction between Fe and P-Fe is also relatively obvious. The increment of 663-Cu powder may result in a slight improvement in matrix wear resistance.In addition,the results of nonlinear programming revealed that the predictive optimum value of hardness was 139.5 HRB and the optimum wear resistance was 0.056 g,whereas they could not reach the optimum value at the same time.展开更多
The open-loop crossover frequency is pointed as an important parameter for practical autopilot design. Since different gain designs may achieve the same open-loop crossover frequency, it should be neither considered a...The open-loop crossover frequency is pointed as an important parameter for practical autopilot design. Since different gain designs may achieve the same open-loop crossover frequency, it should be neither considered as a performance objective of the optimal autopilot design-schemes nor neglected. Besides, the main assignment of the autopilot is to drive the missile to track the acceleration commands, so the autopilot gain design should be evaluated directly according to the resultant tracking performance. For this purpose, an optimal design methodology of the three-loop missile autopilot is introduced based on constraint optimization technique, where the tracking performance is established analytically as the design objective and the open-loop crossover frequency is formed as inequality constraint function, both are manipulated in terms of stable characteristic parameters of the autopilot closed-loop. The proposed technique is implemented with the assistance of a numerical optimization algorithm which automatically adjusts the design parameters. Finally, numerical simulation results are provided to demonstrate the effectiveness and feasibility of the proposed approach compared with that in some references.展开更多
Satellite constellation design for space optical systems is essentially a multiple-objective optimization problem. In this work, to tackle this challenge, we first categorize the performance metrics of the space optic...Satellite constellation design for space optical systems is essentially a multiple-objective optimization problem. In this work, to tackle this challenge, we first categorize the performance metrics of the space optical system by taking into account the system tasks（i.e., target detection and tracking）. We then propose a new non-dominated sorting genetic algorithm（NSGA） to maximize the system surveillance performance. Pareto optimal sets are employed to deal with the conflicts due to the presence of multiple cost functions. Simulation results verify the validity and the improved performance of the proposed technique over benchmark methods.展开更多
基金sponsored by the National Key Research and Development Program of China[Grant Nos.2020YFC0826804 and 2022YFC3320504]the National Natural Science Foundation of China[Grant No.11772059]。
文摘Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.
基金supported by the Preparation and Characterization of Fogging Agents,Cooperative Project of China(Grant No.1900030040)Preparation and Test of Fogging Agents,Cooperative Project of China(Grant No.2200030085)。
文摘Water-based aerosol is widely used as an effective strategy in electro-optical countermeasure on the battlefield used to the preponderance of high efficiency,low cost and eco-friendly.Unfortunately,the stability of the water-based aerosol is always unsatisfactory due to the rapid evaporation and sedimentation of the aerosol droplets.Great efforts have been devoted to improve the stability of water-based aerosol by using additives with different composition and proportion.However,the lack of the criterion and principle for screening the effective additives results in excessive experimental time consumption and cost.And the stabilization time of the aerosol is still only 30 min,which could not meet the requirements of the perdurable interference.Herein,to improve the stability of water-based aerosol and optimize the complex formulation efficiently,a theoretical calculation method based on thermodynamic entropy theory is proposed.All the factors that influence the shielding effect,including polyol,stabilizer,propellant,water and cosolvent,are considered within calculation.An ultra-stable water-based aerosol with long duration over 120 min is obtained with the optimal fogging agent composition,providing enough time for fighting the electro-optic weapon.Theoretical design guideline for choosing the additives with high phase transition temperature and low phase transition enthalpy is also proposed,which greatly improves the total entropy change and reduce the absolute entropy change of the aerosol cooling process,and gives rise to an enhanced stability of the water-based aerosol.The theoretical calculation methodology contributes to an abstemious time and space for sieving the water-based aerosol with desirable performance and stability,and provides the powerful guarantee to the homeland security.
文摘The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs makes the design of the guidance,navigation,and control(GNC)have a larger-thanbefore impact on the main-body design(shape,motor,and layout design)and its design objective,i.e.,flight performance.Pursuing a trade-off between flight performance and guidance precision,all the relevant interactions have to be accounted for in the design of the main body and the GNC system.Herein,a multi-objective and multidisciplinary design optimization(MDO)is proposed.Disciplines pertinent to motor,aerodynamics,layout,trajectory,flight dynamics,control,and guidance are included in the proposed MDO framework.The optimization problem seeks to maximize the range and minimize the guidance error.The problem is solved by using the nondominated sorting genetic algorithm II.An optimum design that balances a longer range with a smaller guidance error is obtained.Finally,lessons learned about the design of the MM and insights into the trade-off between flight performance and guidance precision are given by comparing the optimum design to a design provided by the traditional approach.
基金National Natural Science Foundation of China(60072029)
文摘We propose a modified evolutionary computation method to solve the optimization problem of additively decomposed function with constraints. It is based on factorized distribution instead of penalty function and any transformation to a linear model or others. The feasibility and convergence of the new algorithm are given. The numerical results show that the new algorithm gives a satisfactory performance.
基金Project(51176143)supported by the National Natural Science Foundation of ChinaProject(K201919)supported by the Scientific Research Foundation of Wuhan Institute of TechnologyChina。
文摘A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.
文摘A new type of iron-based matrix formula as a potential substitute for traditional WC-based matrix formula for hot pressed diamond bit was investigated.Iron,phosphor-iron,663-Cu,nickel,cobalt and certain additives were selected as the studied formula constituents.Among matrix performances,the hardness and wear resistance were chosen as experimental indexes in this paper.Constrained uniform design method was used for the formula design of iron-based matrix.Two forms of regression models of matrix hardness and wear resistance were obtained by regression analysis using MATLAB.Moreover,the optimization of matrix formulae and matrix performances were also achieved through constrained nonlinear programming.It was found that matrix hardness,significantly affected by the factor of Ni-Co-additives and Fe,increased with the increment of Ni-Co-additives,Fe and P-Fe,but reduced with the increase of 663-Cu.On the other hand,matrix wear resistance is mainly affected by Fe;the effect of the interaction between Fe and P-Fe is also relatively obvious. The increment of 663-Cu powder may result in a slight improvement in matrix wear resistance.In addition,the results of nonlinear programming revealed that the predictive optimum value of hardness was 139.5 HRB and the optimum wear resistance was 0.056 g,whereas they could not reach the optimum value at the same time.
文摘The open-loop crossover frequency is pointed as an important parameter for practical autopilot design. Since different gain designs may achieve the same open-loop crossover frequency, it should be neither considered as a performance objective of the optimal autopilot design-schemes nor neglected. Besides, the main assignment of the autopilot is to drive the missile to track the acceleration commands, so the autopilot gain design should be evaluated directly according to the resultant tracking performance. For this purpose, an optimal design methodology of the three-loop missile autopilot is introduced based on constraint optimization technique, where the tracking performance is established analytically as the design objective and the open-loop crossover frequency is formed as inequality constraint function, both are manipulated in terms of stable characteristic parameters of the autopilot closed-loop. The proposed technique is implemented with the assistance of a numerical optimization algorithm which automatically adjusts the design parameters. Finally, numerical simulation results are provided to demonstrate the effectiveness and feasibility of the proposed approach compared with that in some references.
文摘Satellite constellation design for space optical systems is essentially a multiple-objective optimization problem. In this work, to tackle this challenge, we first categorize the performance metrics of the space optical system by taking into account the system tasks（i.e., target detection and tracking）. We then propose a new non-dominated sorting genetic algorithm（NSGA） to maximize the system surveillance performance. Pareto optimal sets are employed to deal with the conflicts due to the presence of multiple cost functions. Simulation results verify the validity and the improved performance of the proposed technique over benchmark methods.
