海上遇险小目标的无人机定基点搜寻建模与仿真

无人机的快速发展使其成为搜寻海上遇险目标的重要工具之一。通过报告的遇险目标的初始位置,优化确定无人机的搜寻航路是发挥光电侦察装备效能、提高遇险目标搜寻效率的核心问题之一。基于遇险目标定基点位置,通过建立无人机定基点扩展方形搜寻和扇形搜寻方法模型,设计仿真应用程序,对两种搜寻方法进行仿真评估分析。研究发现在相同的发现概率下,扩展方形搜寻方法具有时间优势,对制定和指导无人机的海上搜寻计划行动具有现实的参考价值。     

海上搜寻规划方法研究综述

对1946年以来海上搜寻规划方法的发展情况进行综述.分别从搜索理论、经典搜寻规划方法、计算机化的经典搜寻规划方法以及基于蒙特卡罗技术的计算机仿真方法等方面对海上搜寻规划系统做较深入的介绍,分析和比较一些海上搜寻规划系统的原理和优缺点,最后,对海上搜寻规划系统的发展趋势作了展望.     

基于MAXWELL的瞬变电磁“8”字形发射线圈仿真分析

针对瞬变电磁技术在工程应用中易受干扰、探测结果不准确的问题,本文提出了一种瞬变电磁“8”字形发射线圈方案。采用MAXWELL仿真软件对瞬变电磁“8”字形发射线圈和方形发射线圈进行了仿真分析,通过对比“8”字形发射线圈和方形发射线圈在不同大小电流情况下产生的磁场分布发现,“8”字形发射线圈在远距离位置具有较强的聚焦性,在近距离位置能产生明显大于方形线圈的磁通密度。所以“8”字形发射线圈对增强瞬变电磁超前探测的抗干扰能力和提高探测结果的准确度具有重要作用。     

多对多无人机空战的智能决策研究

针对能够进行自主空战的无人机,设计了一套空战流程.建立了基于双方位置、姿态和能量等的优势函数评价体系,通过改进的混合粒子群优化算法实现了多对多空战的目标分配,结合改进的Double Q-learning算法设计了无人机的机动决策策略,并在4对4空战场景下进行仿真验证.仿真结果显示无人机可以很好地追踪并击败敌方目标,还能...     

海上客船遇险应急响应预案

运用模糊加权综合评判数学方法对海上客运危险源进行了辨别和风险评估,并由此确定危险源．在此基础上通过对国内外一般突发事故预案的进一步分析、研究和归纳总结,找出客船遇险救助的规律和特点以及目前我国海上救助机构的构成和职责划分,提出预案编制的一般要素和结构特征,并拟定我国海上客船遇险应急响应框架,可为我国海上客船遇险的预警、应急响应及善后处理提供借鉴和帮助．     

基于Dubins路径的无人机避障规划算法

研究了一种基于Dubins路径的无人机的避障规划算法. 通过采用遗传算法,结合无人机的飞行性能和最小转弯半径,提出了一种在已知障碍空间位置前提下的无人机路径规划方法,并通过算法改进,将其推广成为在未知障碍位置等先验知识的前提下的无人机实时避障算法. 仿真结果表明,该算法原理正确,对于多障碍环境下无人机避障策略的获取具有较好效果.      

一种用于天线面形恢复测量的无人机导航方案

天线近场面形恢复算法需要搭载发射源的无人机沿特定轨迹飞行,并获得其位置。根据面形恢复算法对无人机飞行的要求设计一种包含差分GPS和视觉传感器的导航方案,在此导航方案的数据融合时间策略下使用常规扩展卡尔曼滤波器将出现震荡问题。为此提出一种基于SageHusa滤波算法改进的自适应扩展卡尔曼滤波器,并通过仿真和实际飞行测试将其与常规扩展卡尔曼滤波器进行对比。实验结果表明,此自适应扩展卡尔曼滤波器在实际应用中表现出更好的性能,并在弱GPS信号情况下能够趋向于更可信的视觉里程计数据。此方案基本满足天线测量时无人机沿轨迹飞行并采集位置数据的要求,有望实现射电望远镜主动面实时闭环修正。     

基于滑模控制的四旋翼无人机的轨迹跟踪控制

针对四旋翼无人机,研究了基于滑模控制的轨迹跟踪问题.根据无人机复杂的数学模型,首先利用单位四元数法描述系统姿态,再将其分解为位置和姿态两个子系统;通过引入中间控制输入,跟踪三个自由度的位置信息;考虑到位置和姿态子系统分别受到干扰力和干扰力矩的影响,设计了鲁棒反演滑模控制器,保证了对目标轨迹的稳定跟踪.仿真结果验证了该控制方法的有效性.     

基于尺度估计的无人机场景车辆跟踪算法研究

无人机场景下的车辆跟踪发展迅速,并且研究方向较为广阔.近些年来,基于相关滤波的目标跟踪算法达到了不错的跟踪效果,并且它的快速算法满足了我们的需求,具有很好的应用前景.以相关滤波算法作为框架,使用基于尺度估计核相关滤波目标跟踪算法.通过循环位移的方法扩展候选训练样本,经过计算训练样本与目标样本的相关系数产生置信响应图,并通过置信响应图的相应最大值来确定当前帧的目标位置.特征选择双选机制并结合颜色模型,可改进目标跟踪的精度和速度.采用德国实验室提供的无人机车辆视频,并对提出的算法和特征选择方法与之前方法进行对比实验.由实验结果得出,本研究所提出的算法比以往的算法有较大提升.     

无人机编队协同追踪控制律和编队信息架构

针对"长机-僚机"模式的无人机编队追踪运动目标出现姿态信息和位置信息不一致而导致碰撞的问题,设计了一种协同追踪控制器并对该控制器进行稳定性分析。该控制器以3架无人机构成的编队作为控制体,采用拉氏矢量场方法获取无人机编队追踪运动目标的轨迹,同时构建无人机之间的信息架构,实现无人机编队按照预期的姿态和位置信息在运动目标周围的圆形轨道飞行的目的。研究单架无人机的航迹规划和多无人机编队协同追踪:对于单架无人机的航迹规划,采用反馈控制完成航向收敛证明;对于多无人机编队,采用一种多变量控制器可以保持无人机编队在圆形轨道运动,同时使用未知风和运动目标的自适应估计量来确定无人机编队在圆形轨道飞行的稳定性。仿真结果表明:在追踪过程中,3架无人机能够快速(15 s)以相同的姿态和位置渐进靠近目标,同时保持相对稳定;在满足航向速率和空速条件时,任意两架无人机相对距离误差能够快速(10 s)收敛到稳定值。该控制器突破了多无人机编队近距协同追踪目标的局限,可为多无人机分布式控制器设计提供方法借鉴。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with