Studies show that different geometries of a Variable Cycle Engine(VCE)can be adjusted during the transient stage of the engine operation to improve the engine performance.However,this improvement increases the complex...Studies show that different geometries of a Variable Cycle Engine(VCE)can be adjusted during the transient stage of the engine operation to improve the engine performance.However,this improvement increases the complexity of the acceleration and deceleration control schedule.In order to resolve this problem,the Transient-state Reverse Method(TRM)is established in the present study based on the Steady-state Reverse Method(SRM)and the Virtual Power Extraction Method(VPEM).The state factors in the component-based engine performance models are replaced by variable geometry parameters to establish the TRM for a double bypass VCE.Obtained results are compared with the conventional component-based model from different aspects,including the accuracy and the convergence rate.The TRM is then employed to optimize the control schedule of a VCE.Obtained results show that the accuracy and the convergence rate of the proposed method are consistent with that of the conventional model.On the other hand,it is found that the new-model-optimized control schedules reduce the acceleration and deceleration time by 45%and 54%,respectively.Meanwhile,the surge margin of compressors,fuel–air ratio and the turbine inlet temperature maintained are within the acceptable criteria.It is concluded that the proposed TRM is a powerful method to design the acceleration and deceleration control schedule of the VCE.展开更多
针对便携式设备中图形用户界面图像显示需求的不断提高,分析讨论了2D图像加速引擎的实现技术,基于GBA(Game Boy Advance)的模拟器VBA(Visual Boy Advance)的绘图方法提出了2D图像硬件加速引擎的实现架构,该架构对速度、面积及总线带宽...针对便携式设备中图形用户界面图像显示需求的不断提高,分析讨论了2D图像加速引擎的实现技术,基于GBA(Game Boy Advance)的模拟器VBA(Visual Boy Advance)的绘图方法提出了2D图像硬件加速引擎的实现架构,该架构对速度、面积及总线带宽等因素进行了优化处理,减轻了CPU的负荷、同时达到了低功耗设计的目的.基于该架构实现的2D图像硬件加速引擎通过了正确的验证与测试,能有效地支持GBA等2D游戏,根据需要可以应用到不同的图形用户界面,提供高效的图像加速显示能力.展开更多
The fuel consumption of a ship has always been an important research topic,but nowadays its importance has even increased as it is directly related to a ship’s greenhouse gas(GHG)emissions,which is now tightly regula...The fuel consumption of a ship has always been an important research topic,but nowadays its importance has even increased as it is directly related to a ship’s greenhouse gas(GHG)emissions,which is now tightly regulated.In this paper,such a dynamic model is presented.The ship’s resistance in calm water and propeller’s performance in open water are required as input.The hull efficiency is estimated empirically.The diesel engine is modelled by a first-order transfer function with a delayed response and its performance is calibrated with the data from the manufacturer’s catalogue.A governor is applied to maintain the pre-set engine’s rotational speed and to control the engine fuel rate.A slope limiter is employed to approximate the actual engine operation during engine transients.The default values can be obtained from the manufacturer engine load acceptance diagram.The developed model is implemented in MATLAB SIMULINK environment.After validation against third-party published results,the influence of using different types of governors on ship speed and fuel consumption is investigated.The model is also applied to simulate the fuel consumption of a ship during a typical acceleration manoeuvre and the scenario of a real ship encountering harsh weather conditions.展开更多
John Metric was shocked the first time he drove his electric dragster,a modified 1984 Pontiac Fiero(Fig.1).Metric had swapped the car’s gasoline engine for two electric motors that could generate 1830 N·m of tor...John Metric was shocked the first time he drove his electric dragster,a modified 1984 Pontiac Fiero(Fig.1).Metric had swapped the car’s gasoline engine for two electric motors that could generate 1830 N·m of torque.When he hit the accelerator,“it threw me back in my seat so hard,”he said.展开更多
The Efficient Global Optimization(EGO)algorithm has been widely used in the numerical design optimization of engineering systems.However,the need for an uncertainty estimator limits the selection of a surrogate model....The Efficient Global Optimization(EGO)algorithm has been widely used in the numerical design optimization of engineering systems.However,the need for an uncertainty estimator limits the selection of a surrogate model.In this paper,a Sequential Ensemble Optimization(SEO)algorithm based on the ensemble model is proposed.In the proposed algorithm,there is no limitation on the selection of an individual surrogate model.Specifically,the SEO is built based on the EGO by extending the EGO algorithm so that it can be used in combination with the ensemble model.Also,a new uncertainty estimator for any surrogate model named the General Uncertainty Estimator(GUE)is proposed.The performance of the proposed SEO algorithm is verified by the simulations using ten well-known mathematical functions with varying dimensions.The results show that the proposed SEO algorithm performs better than the traditional EGO algorithm in terms of both the final optimization results and the convergence rate.Further,the proposed algorithm is applied to the global optimization control for turbo-fan engine acceleration schedule design.展开更多
基金supported by the Aviation Power Foundation of China(6141B09050382)。
文摘Studies show that different geometries of a Variable Cycle Engine(VCE)can be adjusted during the transient stage of the engine operation to improve the engine performance.However,this improvement increases the complexity of the acceleration and deceleration control schedule.In order to resolve this problem,the Transient-state Reverse Method(TRM)is established in the present study based on the Steady-state Reverse Method(SRM)and the Virtual Power Extraction Method(VPEM).The state factors in the component-based engine performance models are replaced by variable geometry parameters to establish the TRM for a double bypass VCE.Obtained results are compared with the conventional component-based model from different aspects,including the accuracy and the convergence rate.The TRM is then employed to optimize the control schedule of a VCE.Obtained results show that the accuracy and the convergence rate of the proposed method are consistent with that of the conventional model.On the other hand,it is found that the new-model-optimized control schedules reduce the acceleration and deceleration time by 45%and 54%,respectively.Meanwhile,the surge margin of compressors,fuel–air ratio and the turbine inlet temperature maintained are within the acceptable criteria.It is concluded that the proposed TRM is a powerful method to design the acceleration and deceleration control schedule of the VCE.
文摘针对便携式设备中图形用户界面图像显示需求的不断提高,分析讨论了2D图像加速引擎的实现技术,基于GBA(Game Boy Advance)的模拟器VBA(Visual Boy Advance)的绘图方法提出了2D图像硬件加速引擎的实现架构,该架构对速度、面积及总线带宽等因素进行了优化处理,减轻了CPU的负荷、同时达到了低功耗设计的目的.基于该架构实现的2D图像硬件加速引擎通过了正确的验证与测试,能有效地支持GBA等2D游戏,根据需要可以应用到不同的图形用户界面,提供高效的图像加速显示能力.
文摘The fuel consumption of a ship has always been an important research topic,but nowadays its importance has even increased as it is directly related to a ship’s greenhouse gas(GHG)emissions,which is now tightly regulated.In this paper,such a dynamic model is presented.The ship’s resistance in calm water and propeller’s performance in open water are required as input.The hull efficiency is estimated empirically.The diesel engine is modelled by a first-order transfer function with a delayed response and its performance is calibrated with the data from the manufacturer’s catalogue.A governor is applied to maintain the pre-set engine’s rotational speed and to control the engine fuel rate.A slope limiter is employed to approximate the actual engine operation during engine transients.The default values can be obtained from the manufacturer engine load acceptance diagram.The developed model is implemented in MATLAB SIMULINK environment.After validation against third-party published results,the influence of using different types of governors on ship speed and fuel consumption is investigated.The model is also applied to simulate the fuel consumption of a ship during a typical acceleration manoeuvre and the scenario of a real ship encountering harsh weather conditions.
文摘John Metric was shocked the first time he drove his electric dragster,a modified 1984 Pontiac Fiero(Fig.1).Metric had swapped the car’s gasoline engine for two electric motors that could generate 1830 N·m of torque.When he hit the accelerator,“it threw me back in my seat so hard,”he said.
基金the financial support of the National Natural Science Foundation of China(Nos.52076180,51876176 and 51906204)National Science and Technology Major Project,China(No.2017-I0001-0001)。
文摘The Efficient Global Optimization(EGO)algorithm has been widely used in the numerical design optimization of engineering systems.However,the need for an uncertainty estimator limits the selection of a surrogate model.In this paper,a Sequential Ensemble Optimization(SEO)algorithm based on the ensemble model is proposed.In the proposed algorithm,there is no limitation on the selection of an individual surrogate model.Specifically,the SEO is built based on the EGO by extending the EGO algorithm so that it can be used in combination with the ensemble model.Also,a new uncertainty estimator for any surrogate model named the General Uncertainty Estimator(GUE)is proposed.The performance of the proposed SEO algorithm is verified by the simulations using ten well-known mathematical functions with varying dimensions.The results show that the proposed SEO algorithm performs better than the traditional EGO algorithm in terms of both the final optimization results and the convergence rate.Further,the proposed algorithm is applied to the global optimization control for turbo-fan engine acceleration schedule design.
