利用三次样条改进蚁群算法的无人机航路规划

针对无人机在二维平面自动飞行中转弯角度过大、路径规划困难的问题,研究了蚁群算法在复杂环境下航路规划中的应用,利用链接图简洁的特点建立空间模型,对无人机的飞行环境和航迹代价进行了描述,并结合三次样条插值函数与蚁群算法,提出了改进蚁群算法,对无人机飞行路径进行优化,并给出算法软件流程。利用MATLAB进行了仿真实验,得出了最优的航路,算法具有较好的稳定性和鲁棒性,对轨迹中不可飞的尖角进行了平滑处理,使得航路为曲线轨迹,满足无人机工作的性能要求,减少无人机在飞行中的代价损耗,验证了该优化算法在无人机航路规划中的可行性。     

锚泊状态下船载测控系统对塔相位标校研究

航天器海上测量船是搭载着船载测控系统的海上平台,主要完成对目标的海上测控任务。测量船在新建之时或大修之后均要对搭载的测控系统进行标校,主要是进行海上合作目标校飞。海上校飞过程中锚泊状态下天线对塔相位标校必不可少,对此进行研究有助于提高锚泊状态下对塔相位标校过程的认识,提升船载测控系统的标校精度。研究过程首先分析了我国测量船所采用的差模双通道单脉冲雷达的跟踪原理和天线对塔校相原理,然后再结合锚泊状态下大型海上测量船的运动规律,建立了船体运动对锚泊状态下对塔校相精度影响的数学模型,最后在远场条件下对数学模型进行了的仿真,分析了测量船锚泊时不同运动模式对相位标校的影响,并进一步给出了锚泊状态下船载测控天线对塔校相的建议。     

复杂环境下蓝牙定位模型优化方法研究

社会经济以及移动网络技术的快速发展,使得室内定位需求大幅度增长。但是,建筑结构等因素导致普遍使用的全球定位系统GPS在室内定位中性能急剧下降,不能很好满足室内定位的需要。针对各类复杂室内环境,提出了基于环境参数校准的自适应信号强度优化算法。从理论上分析了高斯滤波的性能,使用蓝牙4.0技术,以锚节点作为参考节点,采用均值滤波和高斯滤波优化RSSI值校准基准信号,运用线性规划实时、动态估算环境衰减系数,分析了改进基准信号模型和改进衰减系统模型的性能,最后获得信号传输综合优化模型。使用计算机仿真及实验方式对算法进行了研究,实验结果表明,在复杂办公室环境下,定位误差绝对值小于1dbm,定位误差小于2%,能够较好地满足室内定位的需求。     

双星光学观测体系的目标定位误差分析

为提高双星光学观测体系的定位精度,构建了新型双星光学定位系统。通过对卫星、光电观测平台的建模,构建了地惯系下平台与目标间的观测矢量模型。利用几何定位算法,推导出了地惯系下的目标定位模型与定位误差模型,并利用蒙特卡罗法获得了定位误差分布。在此基础上,引入了小波理论进行误差的优化重构,以提高双星光学观测体系的定位精度。利用测量数据进行仿真,结果表明,引入小波理论对目标定位误差进行降噪重构后,可以使目标定位精度提高30%,为工程上减小目标定位误差提供了新的思路。     

搜索策略改进的波束形成定位方法研究

针对传统时差方法定位精度低和波束形成方法定位效率低的问题,提出了一种基于遗传算法和波束形成算法的海洋平台损伤定位方法。通过遗传算法对待搜索区域坐标进行编码、选择、交叉、变异等操作,对波束形成算法的搜索策略进行改进,快速搜索损伤位置坐标。实验证明,与时差定位算法相比,本文方法的定位误差降低了50%;与波束形成算法相比,本文方法的运算时间减少了53%。因此,本文方法在保证定位精度的前提下,提高了算法的执行效率,对海洋平台损伤的实时监测和定位具有一定的实用价值。     

基于禁忌算法优化神经网络的海洋船舶流量预测

为了有效缓解船舶交通拥堵和提高通航效率,对海洋港口和航道管理提供一个更可靠的数据,设计了一种基于禁忌算法优化神经网络的海洋船舶流量预测的方法。首先,建立了基于禁忌算法优化神经网络的海洋船舶流量预测模型。然后,设计了三层的脊波神经网络结构,提出了采用禁忌算法优化脊波神经网络结构参数的具体方法,从而得到一个初始化的脊波神经网络流量预测模型。然后,采用有标签的训练样本数据集对网络进行训练,将满足误差阈值的训练模型作为最终的预测模型。以某港口为例进行仿真实验,结果表明文中得到的预测结果与真实值较为接近,且与其它方法相比,具有更好的预测效果。     

基于跳距修正L-M优化的WSN定位算法

针对DV-Hop定位算法在节点随机分布的网络拓扑环境下存在误差较大的问题,文中通过分析平均跳距估计、未知节点坐标估计区域求解对定位精度的影响,提出了一种基于跳距修正L-M优化的WSN定位算法CLDV-Hop(Correct L-M DV-Hop)。仿真结果表明,在不增加额外开销且仿真环境相同的条件下,CLDV-Hop算法比现有改进的算法具有更高的定位精度,与DV-Hop算法相比精度提高了约33%——41%。     

基于多物理场耦合分析的压接型IGBT散热器多目标优化

为研究处于电磁场、温度场和应力场相互耦合的多物理场环境下的压接型IGBT水冷散热器热阻、流阻及表面压力分布特性,结合ANSYS软件,提出一种在电磁–热–应力多物理场耦合环境下水冷散热器多目标优化方法。在满足表面压力的前提下,以水冷散热器热阻、流阻最小化为优化目标。采用Kriging方法构建响应面模型,利用AMGA优化算法对水冷散热器内部流道结构进行多目标优化设计,计算出了最优方案。搭建试验平台对仿真分析结果进行试验验证,证明文中对压接型IGBT水冷散热器的多物理场耦合分析方法可以指导多物理场下的水冷散热器的设计。     

无线传感中的WPSO-DVHOP算法在节点定位中的研究

节点的定位一直都是无线传感网中的重要研究对象,针对使用传统算法定位节点容易出现估算不准确,定位精度低,算法自身局部收敛速度快等缺点,提出一种基于权值粒子群优化(WPSO)算法,首先分析了采用锚节点估算未知节点的距离与真实距离误差,采用最小二乘法的距离修正值策略,其次针对粒子群算法的收敛速度不足,提出了采用权值来调节粒子的速度,改进后的算法对节点定位误差进行修正。在仿真平台Matlab上的实验说明WPSO算法相对于基本的定位算法,粒子群定位算法相比提高了传感器节点定位精度,从算法的收敛性,节点定位的精度以及能量消耗等方面说明该算法具有一定的有效性,如何能够更好进行权值的设置使之能够更加有效提高算法的效率是下一步研究的重点。     

浅海时变声速环境下的自适应匹配场定位算法实现*

针对浅海环境下声速剖面失配引起的匹配场处理器失配问题,提出了一种自适应匹配场定位算法在声速剖面时变环境下的实现方式。将先验声速剖面集简化为经验正交函数表示,结合蒙特卡洛方法与环境扰动约束算法对当下时刻的目标声源进行匹配场定位。本文以某次试验获取的连续20小时的声速剖面数据为研究对象,通过仿真试验对该算法进行验证,结果表明：在先验声速剖面集的半小时之后,利用自适应算法的距离和深度定位成功率较常规匹配场算法有较大提升,其中,深度正确定位概率相对较低。     

Microscopic basis for Fick's law for self-diffusion

We investigate self-diffusion in a classical fluid composed of two species which are distinguished through the color of their particles, either black or white, but are identical as regards their mechanical properties. Disregarding color the fluid is in thermal equilibrium. We show that if a single test particle in the one-component fluid moves asymptotically as Brownian motion, then the color density and current in certain classes of nonequilibrium states are related, on the appropriate macroscopic scale, through Fick's law, and the former is governed by the diffusion equation. If in addition several test particles move asymptotically as independent Brownian motions, then the colored fluid is, on a macroscopic scale, in local equilibrium with parameters governed by the solution of the diffusion equation.Part of this work was done while both authors were at IHES, Bures-sur-Yvette, France.Supported in part by NSF Grant No. PHY 78-15920-02.Supported by a Heisenberg fellowship of the Deutsche Forschungsgemeinschaft.     

Convolution identities for quasiprobabilities for Bose functions

We present identities relating the equations of motion of various quasiprobabilities for quantum oscillators. These identities turn out useful for checking the consistency of approximations made in constructing the equations of motion with the basic Bose commutator. Moreover, our identities allow to identify the quasiprobability distributions which have the easiest-to-solve equations of motion.     

Requirements for Optical Systems for Virtual Displays

Currently, there are many types of virtual displays and new types arise every year. However, their vast majority appear technically inapplicable because they are inconsistent with a number of key factors related to the eye physiology. In this paper, we present the general requirements for optical systems of virtual displays, taking into account human eye physiology.     

Figure of merit for spectrometers for EDXRF

How should one select the best detector for a particular measurement in energy dispersive X‐ray fluorescence (EDXRF)? How should one select the optimum system configuration, i.e. the best shaping time and beam current? Manufacturers provide a variety of specifications, such as energy resolution and maximum count rate, but these are indirectly related to the end use of an EDXRF instrument, the measurement and detection limit of the measured elemental concentrations. We suggest in this paper using the time required to achieve a given statistical uncertainty as a figure of merit. We derive scaling rules for this figure of merit based on conventional specifications, including energy resolution, peaking time, maximum count rate, detector area, and intrinsic efficiency. These scaling rules also include the peak to background ratio of a photopeak and the number of overlapping peaks. We then show how this figure of merit can be used to select the optimum detector and spectrometer configuration for specific applications and compare the results to data obtained with typical systems. Copyright © 2012 John Wiley & Sons, Ltd.     

内窥镜校正中棋盘格标志点自动提取方法

为了解决具有大畸变内窥镜标定的标志点提取困难和人工参与较多等问题,提出了一种简单快速准确的棋盘格标志点提取方法。该方法是采用粗提取和优化来完成棋盘格标志点的提取的:首先利用高斯滤波去除图像噪声,并计算两次图像的梯度特征,利用梯度极值约束得到粗提取的角点;然后利用棋盘格标志点的对称特点消除噪声点的影响,并得到优化的角点位置。实验结果表明,该方法简单易行,计算量小,不需要人工干预即可获得全部标志点,反投影误差小于0.2pixel。     

Memory for pitch versus memory for loudness

The decays of pitch traces and loudness traces in short-term auditory memory were compared in forced-choice discrimination experiments. The two stimuli presented on each trial were separated by a variable delay (D); they consisted of pure tones, series of resolved harmonics, or series of unresolved harmonics mixed with lowpass noise. A roving procedure was employed in order to minimize the influence of context coding. During an initial phase of each experiment, frequency and intensity discrimination thresholds [P(C) = 0.80] were measured with an adaptive staircase method while D was fixed at 0.5 s. The corresponding physical differences (in cents or dB) were then constantly presented at four values of D: 0.5, 2, 5, and 10 s. In the case of intensity discrimination, performance (d') markedly decreased when D increased from 0.5 to 2 s, but was not further reduced when D was longer. In the case of frequency discrimination, the decline of performance as a function of D was significantly less abrupt. This divergence suggests that pitch and loudness are processed in separate modules of auditory memory.     

溶剂化的热力学集团展开理论

把二元溶液的过剩内能（ｅｘｃｅｓｓ ｅｎｅｒｇｙ）分成溶剂－溶剂、溶剂－溶质及溶质－溶质相互作用部分。利用集团展开方法给出了二元溶液在正则系综的配分函数的表达式，利用该表达式得到了溶质的偏摩尔内能（ｐａｒｔｉａｌ ｍｏｌａｒ ｅｎｅｒｇｙ）和偏摩尔熵（ｐａｒｔｉａｌ ｍｏｌａｒ ｅｎｔｒｏｐｙ）的表达式。在无限稀溶液情形，过剩偏摩尔内能的溶剂－溶剂部分又称重组织内能（ｒｅｏｒｇａｎｉｚａｔｉｏｎ ｅｎｅｒｇｙ），它反映了溶质存在时对其周围溶剂分子之间的相互作用能的影响。研究表明，在溶质的粒子数密度相对较大时，溶质分子之间的相互作用将影响过过剩偏摩尔内能的溶剂－溶剂部分，对于稀溶液，过氧偏摩尔内能的溶剂－溶剂部分与溶质的摩尔分数成线性关系。对低蜜度二元溶液，溶质的过剩偏摩尔内能和过剩偏摩尔熵也与溶质的摩尔分数成线     

Expressions for third-order aberration theory for holographic images

Expressions for third-order aberration in the reconstructed wave front of point objects are established by Meier. But Smith, Neil Mohon, Sweatt independently reported that their results differ from that of Meier. We found that coefficients for spherical aberration, astigmatism, tally with Meier’s while coefficients for distortion and coma differ.     

Map for Simultaneous Measurements for a Quantum Logic

In this paper we will study a function of simultaneous measurements for quantum events (s-map) which will be compared with the conditional states on an orthomodular lattice as a basic structure for quantum logic. We will show the connection between s-map and a conditional state. On the basis of the Rényi approach to the conditioning, conditional states, and the independence of events with respect to a state are discussed. Observe that their relation of independence of events is not more symmetric contrary to the standard probabilistic case. Some illustrative examples are included.