The Stackelberg prediction game(SPG)is a bilevel optimization frame-work for modeling strategic interactions between a learner and a follower.Existing meth-ods for solving this problem with general loss functions are ...The Stackelberg prediction game(SPG)is a bilevel optimization frame-work for modeling strategic interactions between a learner and a follower.Existing meth-ods for solving this problem with general loss functions are computationally expensive and scarce.We propose a novel hyper-gradient type method with a warm-start strategy to address this challenge.Particularly,we first use a Taylor expansion-based approach to obtain a good initial point.Then we apply a hyper-gradient descent method with an ex-plicit approximate hyper-gradient.We establish the convergence results of our algorithm theoretically.Furthermore,when the follower employs the least squares loss function,our method is shown to reach an e-stationary point by solving quadratic subproblems.Numerical experiments show our algorithms are empirically orders of magnitude faster than the state-of-the-art.展开更多
Background:Schistosomiasis is a parasitic disease.It is caused by a prevalent infection in tropical areas and is transmitted through contaminated water with larvae parasites.Schistosomiasis is the second most parasiti...Background:Schistosomiasis is a parasitic disease.It is caused by a prevalent infection in tropical areas and is transmitted through contaminated water with larvae parasites.Schistosomiasis is the second most parasitic disease globally,so investigating its prevention and treatment is crucial.Methods:This paper aims to suggest a time-fractional model of schistosomiasis disease(T-FMSD)in the sense of the Caputo operator.The T-FMSD considers the dynamics involving susceptible ones not infected with schistosomiasis(S_(h)(t)),those infected with the infection(Ih(t)),those recovering from the disease(R(t)),susceptible snails with and without schistosomiasis infection,respectively shown by I_(v)(t)and S_(v)(t).We use a new basis function,generalized Bernoulli polynomials,for the approximate solution of T-FMSD.The operational matrices are incorporated into the method of Lagrange multipliers so that the fractional problem can be transformed into an algebraic system of equations.Results:The existence and uniqueness of the solution,and the convergence analysis of the model are established.The numerical computations are graphically presented to depict the variations of the compartments with time for varied fractional order derivatives.Conclusions:The proposed method not only provides an accurate solution but also can accurately predict schistosomiasis transmission.The results of this study will assist medical scientists in taking necessary measures during screening and treatment processes.展开更多
针对航空发动机高空环境模拟过渡态试验对高空舱进气环境压力模拟系统提出的强抗扰性、强鲁棒性等控制综合品质要求,设计了一种基于鲁棒模型预测控制(Robust Model Predictive Control,RMPC)的高空舱进气环境压力控制方法。RMPC采用滚...针对航空发动机高空环境模拟过渡态试验对高空舱进气环境压力模拟系统提出的强抗扰性、强鲁棒性等控制综合品质要求,设计了一种基于鲁棒模型预测控制(Robust Model Predictive Control,RMPC)的高空舱进气环境压力控制方法。RMPC采用滚动时域优化和扰动反馈补偿的方法,在预测控制框架内处理模型的不确定性。通过建立进气环境压力模拟系统设备特性模型,设计了基于RMPC的进气环境压力控制策略,搭建了仿真平台,与线性自抗扰控制(Linear Active Disturbance Rejection Control,LADRC)方法进行了对比分析。仿真结果表明,应用RMPC技术后,动态调节时间由7.68 s缩短至3.91 s,最大瞬时波动量由0.94%减小至0.25%,该技术能够大幅提高发动机高空环境模拟过渡态试验中进气环境压力模拟的动态响应速度、控制精度和抗扰能力。展开更多
近几年循环流化床锅炉水冷壁磨损较为严重,虽然采用防磨凸台可以有效减缓壁面磨损,然而基于凸台优化设计的文献还鲜见报道,因此文中使用声发射设备研究凸台绕流过程中稠密气固两相流颗粒与壁面接触程度问题,在一冷态实验台密相区,采用...近几年循环流化床锅炉水冷壁磨损较为严重,虽然采用防磨凸台可以有效减缓壁面磨损,然而基于凸台优化设计的文献还鲜见报道,因此文中使用声发射设备研究凸台绕流过程中稠密气固两相流颗粒与壁面接触程度问题,在一冷态实验台密相区,采用声发射对相同尺寸不同截面形状凸台下方颗粒与壁面接触程度进行测量,并用小波包分解处理信号。实验结果表明,0~10.5 k Hz低频段信号可以反应颗粒与壁面接触程度,重点分析该特征频段能量百分比,提出方形凸台为理论优化凸台,对进一步改进循环流化床防磨技术提供指导意见。展开更多
文摘The Stackelberg prediction game(SPG)is a bilevel optimization frame-work for modeling strategic interactions between a learner and a follower.Existing meth-ods for solving this problem with general loss functions are computationally expensive and scarce.We propose a novel hyper-gradient type method with a warm-start strategy to address this challenge.Particularly,we first use a Taylor expansion-based approach to obtain a good initial point.Then we apply a hyper-gradient descent method with an ex-plicit approximate hyper-gradient.We establish the convergence results of our algorithm theoretically.Furthermore,when the follower employs the least squares loss function,our method is shown to reach an e-stationary point by solving quadratic subproblems.Numerical experiments show our algorithms are empirically orders of magnitude faster than the state-of-the-art.
文摘Background:Schistosomiasis is a parasitic disease.It is caused by a prevalent infection in tropical areas and is transmitted through contaminated water with larvae parasites.Schistosomiasis is the second most parasitic disease globally,so investigating its prevention and treatment is crucial.Methods:This paper aims to suggest a time-fractional model of schistosomiasis disease(T-FMSD)in the sense of the Caputo operator.The T-FMSD considers the dynamics involving susceptible ones not infected with schistosomiasis(S_(h)(t)),those infected with the infection(Ih(t)),those recovering from the disease(R(t)),susceptible snails with and without schistosomiasis infection,respectively shown by I_(v)(t)and S_(v)(t).We use a new basis function,generalized Bernoulli polynomials,for the approximate solution of T-FMSD.The operational matrices are incorporated into the method of Lagrange multipliers so that the fractional problem can be transformed into an algebraic system of equations.Results:The existence and uniqueness of the solution,and the convergence analysis of the model are established.The numerical computations are graphically presented to depict the variations of the compartments with time for varied fractional order derivatives.Conclusions:The proposed method not only provides an accurate solution but also can accurately predict schistosomiasis transmission.The results of this study will assist medical scientists in taking necessary measures during screening and treatment processes.
文摘针对航空发动机高空环境模拟过渡态试验对高空舱进气环境压力模拟系统提出的强抗扰性、强鲁棒性等控制综合品质要求,设计了一种基于鲁棒模型预测控制(Robust Model Predictive Control,RMPC)的高空舱进气环境压力控制方法。RMPC采用滚动时域优化和扰动反馈补偿的方法,在预测控制框架内处理模型的不确定性。通过建立进气环境压力模拟系统设备特性模型,设计了基于RMPC的进气环境压力控制策略,搭建了仿真平台,与线性自抗扰控制(Linear Active Disturbance Rejection Control,LADRC)方法进行了对比分析。仿真结果表明,应用RMPC技术后,动态调节时间由7.68 s缩短至3.91 s,最大瞬时波动量由0.94%减小至0.25%,该技术能够大幅提高发动机高空环境模拟过渡态试验中进气环境压力模拟的动态响应速度、控制精度和抗扰能力。
文摘为了筛选嗜酸乳杆菌固体发酵棉粕的最佳产酸发酵条件,试验采用单因素试验,根据响应面的基本原理,以发酵饲料中乳酸含量为优化指标,利用Design Expert软件对发酵条件(接种量、发酵、温度和时间)进行优化。结果表明:理论最佳发酵条件是接种量为5.96 m L,发酵温度为36.99℃,发酵时间为48.26 h;此条件下发酵产物中乳酸含量预测可达7.57%,实际含量为7.50%。
文摘近几年循环流化床锅炉水冷壁磨损较为严重,虽然采用防磨凸台可以有效减缓壁面磨损,然而基于凸台优化设计的文献还鲜见报道,因此文中使用声发射设备研究凸台绕流过程中稠密气固两相流颗粒与壁面接触程度问题,在一冷态实验台密相区,采用声发射对相同尺寸不同截面形状凸台下方颗粒与壁面接触程度进行测量,并用小波包分解处理信号。实验结果表明,0~10.5 k Hz低频段信号可以反应颗粒与壁面接触程度,重点分析该特征频段能量百分比,提出方形凸台为理论优化凸台,对进一步改进循环流化床防磨技术提供指导意见。
