基于静电势场法改进的蚁群算法用于路径规划

本文针对移动机器人路径规划中,蚁群算法初始阶段搜索盲目性高;容易陷入局部极小值;容易陷入死锁,提出了一种改进的蚁群算法用于路径规划。将静电势场函数引入蚁群算法的启发函数中,增加初始搜索阶段的目的性;加入回退机制,使进入死锁的蚂蚁回退到上一个节点,并将回退之前的节点加入禁忌表,减少死锁情况;将信息素挥发因子动态调整,使初始阶段搜索能力增强而末尾阶段更快收敛。仿真结果表明改进后的算法在复杂环境下能得到更优的路径,收敛速度更快,证明了改进后蚁群算法的优越性。

基于电势场法的移动机器人全局路径规划算法

针对传统路径规划算法计算量大、电路映射地图建模复杂等问题,提出了一种基于电势场法的路径规划新方法.首先,为降低环境建模的复杂度,对Zhang细化算法进行了改进,获得能够细致描绘地图连通关系的骨干图;在此基础上,提出了一种基于电势场理论的模型建立方法,此后通过对模型电流通路的快速搜索获取初始路线,大大降低了路径规划算法的运算量;然后,基于内接圆角方法对路径进行平滑处理,解决了路径离散问题,得到适合服务机器人行走的最优路径.大量对比实验表明,该改进Zhang细化算法有效降低了建模及求解复杂度,提出的基于电势场法的全局路径规划算法很好地解决了传统算法搜索效率低的问题.

对静电场电势求解的有限差分法和逐次超松弛迭代法的研究

通过有限差分法求得静态场的差分方程组,利用超松弛迭代法求解差分方程组,可以得到静态场的近似解.本文以静态场的求解问题为例,利用Python编写程序并绘制图像,验证了此方法的正确性.同时,研究了逐次超松弛迭代法中迭代次数对误差的影响以及逐次超松弛迭代法中最优松弛因子与有限差分法中网格密度的关系,为有限差分法和逐次超松弛迭代法在工程问题中的应用提供科学参考.

强脉冲磁场中Al-Cu共晶定向凝固组织的演变

脉冲磁场作用于Al-Cu共晶凝固的界面,研究了定向凝固组织的演变.随着脉冲磁场强度的提高,Al-Cu共晶定向凝固组织经历了由规则柱晶到破碎枝晶、粗化枝晶到重新规则化柱晶三个演化阶段; 在重新规则化柱晶试样中,共晶片层间距减小,晶团间富铜相析出明显.将感生电势场与溶质扩散场相耦合, 分析了脉冲磁场对凝固界面稳定性的影响,发现强脉冲磁场在金属熔体引起感生电势场效应,在凝固界面前沿诱发具有振荡特征的电致迁移,从而促进晶间扩散和减小成分过冷区域.

不同电流密度下的TIG焊电弧行为分析

文中以TIG焊电弧为研究对象,通过流体力学和电磁学耦合理论建立了不同电流密度下的二维轴对称数学模型.通过Fluent用户自定义函数(UDF)二次开发,对自由状态下的TIG焊电弧行为进行了数值模拟,获得了不同电流密度下的TIG焊电弧热场和流场的分布规律.结果表明,TIG焊电弧阴极温度较高,在较大的电流密度下,阴极区域存在较大的电势差,等离子体受到向下向内的电磁力增大,造成其最大运动速度增大,对阳极造成了强有力的冲击,形成较大的电弧压力.同时验证了TIG焊电弧的热场呈现典型钟罩形态,在焊接过程中氩气比热容在钟罩电弧内部存在带状低谷区域.

侦察无人机航迹规划设计研究

对侦察无人机航迹进行规划,可以提高无人机生存概率,保证无人机能突破敌方威胁,安全到达目标点,成功完成侦察任务。而在航迹规划中,经常因陷入局部最优而导致规划失败,成为无人机航迹规划的难点。针对容易陷入局部最优的问题,采用改进的蚁群算法,引入"电势场"理论,把威胁源视为带电体,将形成电势场,则待选航迹节点具有不同的电势能,从而区分出待选航迹节点的优先级,使无人机选择远离威胁优先级高的航迹点,而不会落入威胁交叉作用区域,避免了陷入局部最优。仿真结果表明,所改进的算法是可行的,可为侦察无人机的航迹规划提供依据。

温室内轨道式喷灌装置设计

为达到温室内灌溉节约用水的目的,设计可沿轨道运动的三自由度倒挂机械臂喷灌装置,同时,可保障作物生长在最佳湿度土壤中,以提高作物产量。本文提出一种基于势函数、电势场理论的土壤湿度传感器均匀性布点方法,可精确采集区域内土壤湿度;采用模糊控制更加精确地控制土壤湿度;为快速响应控制指令,采用PI方法对各关节电机进行控制。计算、分析及仿真结果表明:PI控制可使装置快速响应指令进行运动,响应时间小于1 s;传感器均匀布点方法与土壤湿度模糊控制方法相结合,可精确控制电磁阀开闭时间,模糊控制响应时间小于1 s。装置整体结构模型搭建完成,响应速度快,运动路径及动作可按设定执行。

导体网络阴极保护的新设计方法

在工业区和市区地下埋设的导体网络，广泛采用阴极保护。但对具有若干分支和结点的复杂的而互相衔接的延伸的导体网络，阴极保护设计中就遇上了如何在理论上预测其电势分布的问题。本文介绍的新设计方法，是根据网络各分支的无源双通道模型，把整个网络作为线性导体的计算模型，这就把目前实践上根据试验计算、工程经验和近似经验法，变成可用传统的线性网络方程式求解，而且也很容易在计算机上完成。此方法已在一些情况下做过试验，其测试结果与理论上得到的电势场能很好地吻合。

铸铁中石墨形成机理的再探讨

用金属型可控实验仪证实：进行冷却的铸造铁水内部存在着温差电势场，且为点电势场，其寿命约为０．０５～３．５８ｓ。我们发现：这种电势场是运动的，运动速率与其所在区域的温度梯度的变化率有关。分析并找出了决定铸铁中石墨形态的关键因素。

The Bipolar Theory of the Field-Effect Transistor:X.The Fundamental Physics and Theory(All Device Structures)

This paper describes the foundation underlying the device physics and theory of the semiconductor field effect transistor which is applicable to any devices with two carrier species in an electric field. The importance of the boundary conditions on the device current-voltage characteristics is discussed. An illustration is given of the transfer DCIV characteristics computed for two boundary conditions,one on electrical potential,giving much higher drift-limited parabolic current through the intrinsic transistor, and the other on the electrochemical potentials, giving much lower injection-over-thebarrier diffusion-limited current with ideal 60mV per decade exponential subthreshold roll-off, simulating electron and hole contacts. The two-MOS-gates on thin pure-body silicon field-effect transistor is used as examples

The Bipolar Field-Effect Transistor:II.Drift-Diffusion Current Theory(Two-MOS-Gates on Pure-Base)

This paper describes the drift-diffusion theory of the bipolar field-effect transistor （BiFET） with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin-pure-base. Analytical solution is obtained by partitioning the two-dimensional transistor into two one-dimensional problems coupled by the parametric sur- face-electric-potential. Total and component output and transfer currents and conductances versus D. C. voltages from the drift-diffusion theory, and their deviations from the electrochemical （quasi-Fermi） potential-gradient theory,are presented over practical ranges of thicknesses of the silicon base and gate oxide. A substantial contri- bution from the longitudinal gradient of the square of the transverse electric field is shown.

Piezopotential augmented photo-and photoelectro-catalysis with a built-in electric field

Rapid technological development and population growth are responsible for a series of imminent environmental problems and an ineluctable energy crisis.The application of semiconductor nanomaterials in photocatalysis or photoelectrocatalysis(PEC)for either the degradation of contaminants in the environment or the generation of hydrogen as clean fuel is an effective approach to alleviate these problems.However,the efficiency of such processes remains suboptimal for real applications.Reasonable construction of a built-in electric field is considered to efficiently enhance carrier separation and reduce carrier recombination to improve catalytic performance.In the past decade,as a new method to enhance the built-in electric field,the piezoelectric effect from piezoelectric materials has been extensively studied.In this review,we provide an overview of the properties of piezoelectric materials and the mechanisms of piezoelectricity and ferroelectricity for a built-in electric field.Then,piezoelectric and ferroelectric polarization regulated built-in electric fields that mediate catalysis are discussed.Furthermore,the applications of piezoelectric semiconductor materials are also highlighted,including degradation of pollutants,bacteria disinfection,water splitting for H2 generation,and organic synthesis.We conclude by discussing the challenges in the field and the exciting opportunities to further improve piezo-catalytic efficiency.

Path planning for light-induced dielectrophoretic manipulation of micro-particles

To realize automatic manipulation of micro-particles by light-induced dielectrophoresis （LDEP）, a path-planning scheme based on the improved artificial potential field （APF） for micro light pattern movements is proposed. An algorithm combining guided target and point obstacle based on a new local minimum judging criterion is specially designed, which can solve the local minimum problems encountered by the traditional APF. Experiments of real-time particle manipulation based on this algorithm are implemented and the experimental results show that the proposed approach can overcome the local minimum problems of the traditional APF method, and it is validated to be highly stable for intensive particle obstacles during LDEP manipulation. Consequently, this method can realize real-time manipulation of micro-nano particles with safety, decrease the difficulty of manual manipulation, and thus improve the efficiency of manipulation of micro-particles.

Effect of Magnetic Field on the Ionization Potential of the Atoms and Ions

The authors found the effect of magnetic field on the ionization of atoms and ions and shown that the magnetic field affected the rate of ionization and electron emission at angle of 60°, 120°, 240° and 300°. It is shown that the calculation must take into account the ionization potential of the magnetic field.

A Model for Periodic Nonlinear Electric Field Structures in Space Plasmas

In this study,we present a physical model to explain the generation mechanism of nonlinear periodic waveswith a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic field.The'Sagdeev potential' from the MHD equations is derived and the nonlinear electric field waveforms are obtained when theMach number,direction of propagation,and the initial electric field satisfy certain plasma conditions.For the parallelpropagation,the amplitude of the electric field waves with ion-acoustic mode increases with the increase of initial electricfield and Mach number but its frequency decreases with the increase of Mach number.The amplitude and frequency ofthe electric field waves with ion-cyclotron mode decrease with the increase of Mach number and become less spiky,andits amplitude increases with the increase of initial electric field.For the oblique propagation,only periodic electric fieldwave with an ion-cyclotron mode obtained,its amplitude and frequency increase with the increase of Mach number andbecome spiky.From our model the electric field structures show periodic,spiky,and saw-tooth behaviours correspondingto different plasma conditions.

Effect of the interfacial electric field on the HER on Pt(111)modified with iron adatoms in alkaline media

The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen production as an energy vector in the so-called hydrogen economy.In previous works,laser-induced temperature jump(LITJ)experiments on Pt(111)modified with Ni(OH)_(2)in alkaline media have revealed the importance of the interfacial electric field in the rate of the HER.It was hypothesised that small amounts of Ni(OH)_(2)cause a decrease of the electric field because of a negative shift of the pzfc toward the onset of the hydrogen evolution.In this work,to test the validity of this hypothesis,the study has been extended to Pt(111)surfaces modified with Fe(OH)_(2).The modified surfaces have been studied voltammetrically,and the voltammetric charges have been analysed.The voltammograms show a peak in the hydrogen evolution region that suggest the transformation in the adlayer from Fe(II)to Fe(0).In agreement with the coulometric analysis,the voltammetric features in the OH adsorption region would be related with the oxidation to the+3 valence state.The results obtained with LITJ method reflect the existence of a strong interaction of the Fe oxophilic species with the water molecules,shifting the potential of maximum entropy away from the onset of the HER.Hence,the most catalytic surface is the one with the lowest Fe coverage.

Research on the Developmental Trend of Modern Film Art under Perspectives of Scene Color and Aesthetic

In this paper, we conduct research on the developmental trend of modern fi lm art under perspectives of scene color and aesthetic.Modern movie space have already walked out of the studio, camera to record the real world, more is the fl eeting moments. And constructionspace scene as one of the most straightforward language, fi lm is often shows these bright spots mean to force. Generally speaking, the scene isfully able to meet the need of fi lm narrative, in some music in the movie was also involved in promoting the development of the plot. Music is theart of can directly evokes the emotional reaction, fi lm music in the fi lm’s narrative should properly appear in the process, in order to show thecharacters emotions and feelings. This paper starts from analyzing the general features of the trend of modern fi lm art under perspectives of scenecolor and aesthetic that could serve as the basis of the further research that will be meaningful.

碳纤维复合材料电导特性和力电耦合行为研究进展

碳纤维复合材料具有良好的导电性能,但其作为增强体的树脂基复合材料的导电性能与增强体结构显著相关,且在加载条件下的结构变形触发碳纤维复合材料的导电行为发生改变,这一特性在智能传感器方面具有重要的应用。本文从复合材料电阻法结构健康监测应用出发,着重概述了不同维度增强体碳纤维树脂基复合材料的导电性能和预测模型、表面电势场分布和主要测量技术及力电耦合行为和本构模型,以期为碳纤维复合材料“材料-结构-功能”一体化集成系统的设计提供新方向和新途径。

微纳电子技术进展专辑·编者按--功率超结器件的理论与优化

本文基于从表面场到体内场优化的思想,综述了超结器件的基本理论与两类解析优化法.超结与一般功率MOS结构的本质区别是：前者为N/P型周期排列的结型耐压层,后者为单一导电型的阻型耐压层.超结在耐压层引入等量异型电荷,满足电荷平衡,产生二维场,使高场从表面转向体内,实现场分布优化.文中给出了电荷场与电势场的概念,分析了非全耗尽与全耗尽耐压模式,介绍了瞬态工作机理和安全工作区,讨论了横向超结的等效衬底模型和理想衬底条件,最后提出一种基于最低比导通电阻Ron,min的优化法,寻求给定耐压VB下的Ron,min.超结器件在相同耐压下显著降低其比导通电阻,Ron-VB关系从VB的2.5次方变为1.32次方,甚至是1.03次方,使之成为＂功率MOS器件发展的里程碑＂.

对称及非对称形式下点状电极单元的二维电渗固结研究

针对同性电极间距较大时电渗固结模型的计算,依据电极排布形式提出点状电极单元的概念。基于点状电极单元模型,建立点状电极单元的二维电渗固结理论,采用Galerkin法进行控制方程的离散,给出电势场、孔压场控制方程的有限元形式;基于Python语言开发点状电极单元的二维电渗固结计算数值模块PyEcFem,并进行对称单元的二维效应数值研究以及非对称单元的电渗固结计算,同时进行试验验证。研究表明:(1)排水边界数量早期对排水速率起主要作用,电渗后期阳极数量对排水速率影响较大,非对称单元的排水效果以及负孔压幅值均要高于对称单元。(2)对称单元中,电极间距比能够描述同性边界上的电势跌落幅度,同性电极间距越小,二维效应系数越小,两者之间满足负指数关系。(3)非对称单元的电渗固结中,单元排水能力的限制会导致电渗初期阴极区产生孔隙水压力堆积现象,产生局部的正超孔隙水压力,该现象会影响负孔隙水压力的变化速率以及极值。