Radial Basis Function Interpolation and Galerkin Projection for Direct Trajectory Optimization and Costate Estimation

This work presents a novel approach combining radial basis function(RBF)interpolation with Galerkin projection to efficiently solve general optimal control problems.The goal is to develop a highly flexible solution to optimal control problems,especially nonsmooth problems involving discontinuities,while accounting for trajectory accuracy and computational efficiency simultaneously.The proposed solution,called the RBF-Galerkin method,offers a highly flexible framework for direct transcription by using any interpolant functions from the broad class of global RBFs and any arbitrary discretization points that do not necessarily need to be on a mesh of points.The RBF-Galerkin costate mapping theorem is developed that describes an exact equivalency between the Karush-Kuhn-Tucker(KKT)conditions of the nonlinear programming problem resulted from the RBF-Galerkin method and the discretized form of the first-order necessary conditions of the optimal control problem,if a set of discrete conditions holds.The efficacy of the proposed method along with the accuracy of the RBF-Galerkin costate mapping theorem is confirmed against an analytical solution for a bang-bang optimal control problem.In addition,the proposed approach is compared against both local and global polynomial methods for a robot motion planning problem to verify its accuracy and computational efficiency.

Radial solution of the Logarithmic Laplacian system

The paper generalizes the direct method of moving planes to the Logarithmic Laplacian system.Firstly,some key ingredients of the method are discussed,for example,Narrow region principle and Decay at infinity.Then,the radial symmetry of the solution of the Logarithmic Laplacian system is obtained.

Application of neural networks for permanent magnet synchronous motor direct torque control

Neural networks require a lot of training to understand the model of a plant or a process. Issues such as learning speed, stability, and weight convergence remain as areas of research and comparison of many training algorithms. The application of neural networks to control interior permanent magnet synchronous motor using direct torque control （DTC） is discussed. A neural network is used to emulate the state selector of the DTC. The neural networks used are the back-propagation and radial basis function. To reduce the training patterns and increase the execution speed of the training process, the inputs of switching table are converted to digital signals, i.e., one bit represent the flux error, one bit the torque error, and three bits the region of stator flux. Computer simulations of the motor and neural-network system using the two approaches are presented and compared. Discussions about the back-propagation and radial basis function as the most promising training techniques are presented, giving its advantages and disadvantages. The system using back-propagation and radial basis function networks controller has quick parallel speed and high torque response.

Electron acceleration by tightly focused radially polarized few-cycle laser pulses

Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters. We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution.

Reversal of radial glow distribution in helicon plasma induced by reversed magnetic field

In this work, the reversal of radial glow distribution induced by reversed magnetic field is reported. Based on the Boswell antenna which is symmetric and insensitive to the magnetic field direction, it seems such a phenomenon in theory appears impossible. However, according to the diagnostic of the helicon waves by magnetic probe, it is found that the direction of magnetic field significantly affects the propagation characteristic of helicon waves, i.e., the interchange of the helicon waves at the upper and the lower half of tube was caused by reversing the direction of magnetic field. It is suggested that the variation of helicon wave against the direction of magnetic field causes the reversed radial glow distribution. The appearance of the traveling wave does not only improve the discharge strength, but also determines the transition of the discharge mode.

结构区间参数反求的DIRECT算法

提出一种基于DIRECT算法的结构区间参数反求方法。对于结构不确定性参数反求问题,一般转化为不确定性传播和模型参数优化的双层求解问题。首先,区间模型用来描述响应和待识别结构参数的不确定性,并建立了相应区间参数反求模型。其次,在迭代反求过程中自适应更新径向基函数用来近似原系统模型,并利用DIRECT算法来求解内层不确定性传播问题。最后,通过遗传算法来求解外层的优化模型,从而识别结构不确定性参数的区间。数值算例用来验证了该方法的正确性和有效性,并将该方法应用来反求车辆乘员约束系统中的不确定性参数。

PBL结合情景教学在激光辅助超声桡动脉穿刺教学中的应用

目的探究以问题为导向的学习法(PBL)与情景教学法相结合的创新模式在激光辅助超声桡动脉穿刺技术教学中的应用效果,以提升学生的实践能力和临床技能。方法选取2022-2023年在吉林大学第一医院麻醉科进行住院医师培训的40名学生,随机信封法分为传统教学组(对照组)18名和PBL结合情景教学组(结合组)22名。对照组接受传统教学方式,结合组以问题为基础,结合真实临床情景进行教学。通过基础理论知识和直接观察操作技能(DOPS)评估,对两组学生教学效果进行比较分析,并比较两组学生的临床能力。结果结合组在临床操作技能考核中,对物品准备、无菌操作及穿刺评分等技能操作的DOPS评估均明显优于对照组(P<0.05);临床能力考核Mini-CEX评估,结合组在医疗面谈能力、人文关怀、临床诊断、整体临床能力方面均明显优于对照组(P<0.05);教学效果的调查问卷,结合组在临床思维能力和操作能力方面认可人数明显多于对照组(P<0.05)。结论PBL结合情景教学模式明显优于传统教学,学生的临床能力和技能操作更佳,教学效果显著。

数字化转型与流通产业绿色发展

基于2003—2017年我国省际面板数据,使用NDDF函数测算流通绿色发展水平,实证检验了数字化转型对流通产业绿色发展的影响及其作用机制。研究显示,流通数字化能够显著促进流通产业绿色发展,提高流通产业绿色发展效率。异质性研究显示,行业不同、环境规制水平不同、流通渠道畅通水平不同,数字化转型对流通产业绿色发展水平的影响有所差异。机制检验表明,流通数字化可以提高流通效率、降低产业能耗,优化产业能源结构从而促进流通业绿色发展。

Effect of transverse static magnetic field on radial microstructure of hypereutectic aluminum alloy during directional solidification

The effect of different scales thermoelectric magnetic convection(TEMC)on the radial solidification microstructure of hypereutectic Al alloy has been investigated under transverse static magnetic field during directional solidification,focusing on the formation of freckle.Our experimental and numerical simulation results indicate that the TEMC circulation at sample scale under transverse static magnetic field leads to the enrichment of solute Al on one side of the sample.The TEMC and the solute enrichment degree increase with the increase of magnetic field when the magnetic field increases to 0.5 T.The enrichment degree of solute elements under magnetic field is affected by temperature gradient and growth rate.The non-uniform distribution of solute Al in the radial direction of the sample results in the non-uniform distribution of primary dendrite arm spacing(PDAS).Moreover,the applied magnetic field can lead to freckle formation and its number increases with the increase of magnetic field.The change of freckle is consistent with the anisotropy TEMC caused by the anisotropy of primary dendrite or primary dendrite network under magnetic field.Finally,the mechanism of synergism effect of the anisotropy TEMC,the distribution of solute Al and the PDAS on freckle formation and evolution is studied during directional solidification under magnetic field.

ENTIRE SOLUTIONS OF HIGHER ORDER DIFFERENTIAL EQUATIONS WITH ENTIRE COEFFICIENTS HAVING THE SAME ORDER

In this paper,we consider entire solutions of higher order homogeneous differential equations with the entire coefficients having the same order,and prove that the entire solutions are of infinite lower order.The properties on the radial distribution,the limit direction of the Julia set and the existence of a Baker wandering domain of the entire solutions are also discussed.

天气雷达实时回波省级直显系统设计与应用

天气雷达实时回波所见即所得的特性在气象业务工作中发挥着不可替代的作用。受技术条件限制,实时回波只能在雷达本站或本级气象台接收使用。该文分析了实时回波难于在大范围共享使用的主要原因,总结了目前主流解决方案的弊端,并提出省级直显系统设计实现思路与方法:以天气雷达径向流传输业务为支撑,从径向流传输的省级节点上采集雷达实时数据,实现与原雷达系统的彻底解耦;在云端建立Linux集群,向全网用户转发雷达实时数据,转发时采用分段式多线程内存压缩传输技术,既保障实时性又降低网络宽带占用;客户端从集群获取实时数据,经解压缩还原后完成回波的可视化。2022年4月,该系统在甘肃省气象信息与技术装备保障中心部署成功,并向全省提供8部C波段和7部X波段共15部天气雷达的实时回波直显服务,实现了省级范围内多部天气雷达实时回波的集中接收和直接显示。

Mechanical behaviour of wood compressed in radial direction-part I.New method of determining the yield stress of wood on the stress-strain curve

A test equipment was developed,which allows for real time observation of the deformation behav-ior of wood cellular structure under a compression load applied in radial direction.Compression tests were performed on jack pine(Pinus banksiana)and balsam poplar(Populus balsamifera)spec-imens to explore the relationship between the yield stress and the first failure occurring in wood cell layers during radial compression.The microstructural changes for P.banksiana and P.bal-samifera wood below and above the yield point were analyzed.The study results showed that for P.banksiana the first failure of wood cells occurred at the first earlywood layer,while for P.balsamifera it occurred at the layer with the largest vessels.The first failure of wood cell layer for each species tested was found to correspond to the yield point on the stress-strain curve.A new method of determining the yield stress for wood specimens under radial compression was developed.

可调频旋转磁场仪的装置设计与磁场测量

在教学演示仪器中利用三相交流电产生旋转磁场的传统方法存在仪器损耗大、安全隐患多、成本昂贵等问题。本论文设计了一种可调频旋转磁场的产生装置,在四个辐射状横放的带铁芯螺线管中通入低压直流电,通过PLC板编程对电流进行换向,同时改变换向时间可使置入装置中心的小磁针的偏转周期发生变化,从而达到可调频的效果。螺线管中通入单相恒定直流电时,小磁针不发生偏转;通入双相矩形脉冲电流时,小磁针以45°角步进旋转。磁场方向的转速取决于电流的换向频率。该装置不仅规避了传统方法的不足,且同时兼具定性演示和定量测量双重功能,可作为一款性能优异的实验教学仪器。

Mechanical behaviour of wood compressed in radial direction:Part II.Influence of temperature and moisture content

This study investigated the influence of pressing temperature and moisture content on the me-chanical properties of wood compressed in radial direction.Jack pine(Pinus banksiana)and bal-sam poplar(Populus balsamifera)specimens were tested under a combination of pressing temper-ature(20℃,55℃,90℃,and 125℃)and wood moisture content(2%,7%,12%,and 17%).The yield stress(_(δ)y)and modulus of elasticity(MOE)of the specimens were determined from the stress-strain response.It was found that an increase in either pressing temperature or moisture content of wood generally caused a decrease in the mechanical properties for both species.The t-test results revealed that jack pine specimens are more sensitive to changes in pressing tem-perature and wood moisture content than balsam poplar.For jack pine specimens,at any of the pressing temperatures,the moisture content of 12%was found to be a crucial level to start a significant decrease in𝜎y and MOE,while at any of the moisture content,a change in temper-ature from 55℃to 90℃exhibited a significant change in𝜎y and MOE.The regression models developed can be used to predict𝜎y and MOE as a function of temperature and moisture content.

可调角型双金属温度计示值误差的分析

本文将详细介绍可调角型双金属温度计的示值误差和角度调整误差的校准和数据处理,分析径向位置和轴向位置示值误差的一些问题。通过对示值误差的分析,帮助有关人员更好地开展可调角型双金属温度计示值误差的校准工作。

中国粮食生产效率的内生增长潜力与提升路径

文章基于非径向方向性距离函数和MGML指数考察中国粮食生产效率的变化趋势、内生增长潜力及提升来源,进而探寻促进粮食产业高质量发展的优化路径。研究结果表明:中国粮食生产效率总体水平不高,且在研究期内呈现“下降—稳定—上升”的三阶段演化特征,2020年距有效前沿仍有22.3%的提升空间;投入和非期望产出冗余是阻碍粮食生产效率提升的两个主要原因,面源污染、碳排放以及劳动力和机械投入过多均会带来一定程度的效率损失;2015年之前中国粮食生产效率提升主要依赖于技术进步,2015年之后技术效率和技术追赶发挥了较大作用;中国粮食生产效率下降的地区大都分布在秦岭—淮河以南以及边疆地区,且导致各地区粮食生产效率下降的原因有所差异,粮食主产区主要受制于技术退步,粮食主销区主要受制于技术效率低下,产销平衡区主要受制于自身技术水平与共同前沿越来越大的差距。

电液比例方向阀阀芯及流道结构优化

电液比例方向阀作为液压系统的关键元件,对系统控制性能起关键作用。以某型号电液比例方向阀为研究对象,针对主阀芯凹角处漩涡和进出油口处阀芯所受径向力不均匀问题,提出在阀芯凸肩处增加上下双斜边加圆弧的阀芯结构、进出油口流道设计为圆弧型的结构优化方法。研究中,首先建立了电液比例方向阀的三维模型,并对内部流场进行抽取,采用Fluent软件对不同结构的电液比例方向阀内部流场进行仿真和分析。研究表明,在主阀芯阀口开度一定,入口压力相同的条件下,随着上斜边夹角增大,阀芯凹角处最低压力明显增大,最大湍动能明显减小,有效地抑制了漩涡产生和发展。通过圆弧形流道设计,在不同进口压力和不同阀口开度下,阀芯所受径向力均有所减小,为电液比例方向阀结构优化提供理论基础。

大堤路快速路(二环—三环段)工程总体设计

大堤路作为射线快速路,在加强环线快速路沟通的同时,也要充分发挥环线快速路的分流及屏蔽作用,尽可能减缓快速交通对中心城区的拥堵,因此,工程方案需遵循交通规划“多级分流”的思路。同时考虑上沙地块规划滞后性,方案也需兼顾近远期。

基于线性自抗扰控制的纵向舰载机直接升力全自动着舰控制

舰载机的最终着舰过程受到强烈的舰尾流的干扰,为了抑制舰尾流扰动,本文提出一种基于径向基函数神经网络(radial basis functions neural network,RBFNN)结合线性自抗扰控制(liner active disturbance rejection control,LADRC)的创新设计方法,确保舰载机直接升力控制自动着舰系统的鲁棒性。LADRC将阵风扰动和系统不确定项作为总扰动,通过线性扩展状态观测器(liner extended state observer,LESO)对总扰动进行估计,并通过线性反馈控制律进行补偿,然后根据系统状态利用RBFNN在线调整LADRC控制器的参数,并构建Lyapunov函数以证明闭环系统的稳定性。舰载机跟踪理想下滑道的仿真结果表明,RBF-LADRC的抗干扰性、鲁棒性和跟踪精度均优于与之对比的控制方法。