INTELLIGENT CAD OF CRANE TRAVELLING MECHANISMS

Based on common characteristics in crane design, a new procedure of intelligent CAD for crane travelling mechanisms is proposed. The CAD used for crane travelling mechanisms is usually involved in choosing electrical motors.gear reducers,brakes and couplings, arranging travelling wheels and equilibrium beams.checking temperature increase of motors and slippage of driving wheels,estimating the time used for starting and stopping the cranes, drawing up the travelling mechanism.and so on. By enhancing the CAD, the related expert system and overall intelligent con trol are further developed here in treated as individual module. Accordingly,the intelligent CAD is constructed by combing the CAD with the two modules.

Eliminating shrinkage defects and improving mechanical performance of large thin-walled ZL205A alloy castings by coupling travelling magnetic fields with sequential solidification

ZL205 A alloys with large thin-walled shape were continuously processed by coupling travelling magnetic fields(TMF)with sequential solidification,to eliminate the shrinkage defects and optimize the mechanical performance.Through experiments and simulations,the parameter optimization of TMF and the influence on feeding behavior,microstructure and properties were systematically studied.The results indicate that the magnetic force maximizes at the excitation current of 20 A and frequency of 200 Hz under the experimental conditions of this study,and increases from center to side-walls,which is more convenient to process thin-walled castings.TMF can break secondary dendritic arm and dendrites overlaps,widen feeding channels,prolong the feeding time,optimize the feeding paths,eliminate shrinkage defects and improve properties.Specifically,for as-cast state,TMF with excitation current of 20 A increases ultimate tensile strength,elongation and micro-hardness from 186 MPa,7.3%and 82.1 kg/mm^(2) to 221 MPa,11.7%and 100.5 kg/mm^(2),decreases porosity from 1.71%to 0.22%,and alters brittle fracture to ductile fracture.

Multiscale Characteristics and Connection Mechanisms of Attraction Networks:A Trajectory Data Mining Approach Leveraging Geotagged Data

Urban tourism is considered a complex system,and multiscale exploration of the organizational patterns of attraction networks has become a topical issue in urban tourism,so exploring the multiscale characteristics and connection mechanisms of attraction networks is important for understanding the linkages between attractions and even the future destination planning.This paper uses geotagging data to compare the links between attractions in Beijing,China during four different periods:the pre-Olympic period(2004–2007),the Olympic Games and subsequent‘heat period’(2008–2013),the post-Olympic period(2014–2019),and the COVID-19(Corona Virus Disease 2019)pandemic period(2020–2021).The aim is to better understand the evolution and patterns of attraction networks at different scales in Beijing and to provide insights for tourism planning in the destination.The results show that the macro,meso-,and microscales network characteristics of attraction networks have inherent logical relationships that can explain the commonalities and differences in the development process of tourism networks.The macroscale attraction network degree Matthew effect is significant in the four different periods and exhibits a morphological monocentric structure,suggesting that new entrants are more likely to be associated with attractions that already have high value.The mesoscale links attractions according to the common purpose of tourists,and the results of the community segmentation of the attraction networks in the four different periods suggest that the functional polycentric structure describes their clustering effect,and the weak links between clusters result from attractions bound by incomplete information and distance,and the functional polycentric structure with a generally more efficient network of clusters.The pattern structure at the microscale reveals the topological transformation relationship of the regional collaboration pattern,and the attraction network structure in the four different periods has a very similar importance profile structure suggesting that the attraction network has the same construction rules and evolution mechanism,which aids in understanding the attraction network pattern at both macro and micro scales.Important approaches and practical implications for planners and managers are presented.

Design of a Mobile Mechanism for Missing Miner Search Robots in Underground Mines

A mobile mechanism with four tracked-units for a missing miner search robot (MMSR) is presented, with a design based on the terrain features and atrocious environment of an underground mine. Its structure and working prin- ciple is discussed. The four tracked-units are controlled independently and driven cooperatively. By means of two DC motors being controlled respectively, one tracked-unit can accomplish two types of driving mode: tracked travel and in- tegral unit legged rotation (IULR), forming a track-legged compound function mechanism. Its capabilities of surmount- ing obstacles and its toppling stability in underground mines have also been analyzed. The results show that the mobile mechanism can directly surmount an obstacle of the height less than the length of one tracked-unit and get across a raceway with a span less than the length of one tracked-unit by using tracked travel and IULR. Its unstable slope angle is 51.3°. Toppling stability is determined by its structural size, moving direction and slope angle. IULR of four tracked-units can adjust the robot’s posture and then enhance toppling stability or assist in surmounting obstacles. Its track-legged compound function mechanism makes it suitable for working in underground mines.

Optimum traveling and rotation speeds in friction stir welding for dissimilar Al alloys

Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding of 5052-O and 6061-T6 Al alloys were determined.The optimum traveling and rotation speeds were identified to be 61mm/min and 1600r/min using various mechanical characteristic evaluation methods.

The Stable Wave Packet in the Foundations of Quantum Mechanics

The stable wave packet has been missing in quantum mechanics for a long time. A consistent argument finds, in antimatter, regular group and phase velocities, along with negative energy and negative mass. For this, a new wave function is derived for free antiparticles, consistent with the Feynman-Stueckelberg switching principle. The wave packet, expressing internal periodicity together with external confinement, is ubiquitous in physics. The stable wave packet has many consequences, a few of which are mentioned. They extend to the debate about what is measurable in physics and to localization of quantized properties in entangled particles.

网络思想政治教育仪式的建构与优化——以“带着国旗去旅行”全民网络活动为例

网络思想政治教育仪式的开展已成为信息化时代思想政治教育发展的重要趋势。“带着国旗去旅行”全民网络爱国活动,以生活叙事活化爱国话语,以数字化+仪式营造爱国活动的共联共境,以寓意驱动建构情感共同体,通过创新性的仪式展演流程和数字化仪式展演手段,成功地将爱国情感融入网络空间,引起参与者的强烈共鸣。该活动从仪式符号运用、仪式时空构建、仪式展演形式、仪式传播模式四个方面成功地将教育仪式与互联网相结合,实现了全民网络爱国活动的仪式化建构。为提升网络思想政治教育仪式实效,可从以下方面进一步优化:创新仪式符号话语表现形态、拓展仪式时空、促进仪式教育资源融合共进、扩展仪式传播的多维创新空间。

融合知识图谱和图注意力网络的旅游推荐算法

为缓解旅游推荐模型面临的数据稀疏和冷启动的问题,提出一种融合知识图谱和图注意力网络的旅游推荐算法KRGAT(knowledge ripple graph attention network)。借助水波网络从用户的历史旅游行为和知识图谱中挖掘用户偏好增强用户特征表示,针对当前旅游项目特征学习的方法难以提取节点深层特征的问题,利用图注意力网络聚合相关度更高的邻居节点信息,增强旅游项目特征表示。实验在自建立的旅游数据集上与5个基线方法进行对比,其结果表明,KRGAT的精确率(P)、召回率(R)和AUC值分别提升了5.73%、4.42%和1.42%。

基于时空注意力机制的网约车出行需求预测模型

解决网约车运营中的乘客出行需求预测问题,以降低车辆空载率、减少乘客等待时间。在考虑乘客出行需求的动态时空依赖性的基础上,提出一种基于空间数据可视化和格兰杰因果检验的乘客出行需求空间依赖性分析方法,并结合卷积神经网络和注意力机制,建立了一种基于注意力机制的时空图卷积神经网络模型来预测乘客出行需求。实例研究表明,本模型能有效捕获乘客出行需求时空依赖性的动态特征,提升模型的预测性能,具有较高的准确性和实用性。

新能源汽车政策下居民出行意向多群组分析

为研究新能源汽车政策对不同群体居民出行意向影响存在的差异性问题,提出新能源汽车政策下居民出行意向多群组模型.以计划行为理论为基础,整合居民对新能源汽车政策的态度、响应程度以及低碳理念,构建新能源汽车政策下居民出行意向模型,并对模型进行检验及修正,划分多群组,对修正后的模型进行多群组分析,研究新能源汽车政策对不同出行方式偏好群体影响机理的差异性.研究结果表明:居民对新能源汽车政策的态度、响应以及低碳理念对出行态度、主观规范、知觉行为控制以及行为意向的影响在不同出行方式偏好下存在显著差异;居民对新能源汽车政策的态度越积极、低碳理念越强,则选择新能源汽车或公共交通出行的意向越强;居民对新能源汽车政策的响应越积极,则选择新能源汽车出行的意向越强;改善居民对新能源汽车政策的态度、响应,可促进新能源汽车的使用;通过提升居民的低碳理念,可提高居民采用公共交通或新能源汽车出行的意向.研究可为通过交通政策调整居民出行意向以及制定交通政策提供参考.

传统村落文化遗产融入研学旅行实践的时代价值与策略机制研究

传统村落文化遗产是加强大中小学生国情教育、传统文化教育和理想家园教育的生动教材,是宝贵的研学教育资源。因此,加强学生以国情教育、传统文化教育和素质教育为核心的研学教育活动,把传统村落文化的基因传承好,把优秀的乡村文化、农耕文化、民俗文化发扬好,是新时代实现中华民族伟大复兴中国梦的内在要求。对此,本文着眼传统村落融入研学旅行实践的时代价值,结合研学旅行的本质特征,系统分析传统村落遗产研学旅行实践实施的有效策略机制。

长三角地区居民城际出行时间异质性及影响机制研究

探究城际出行网络的时间异质性及其影响机制,对推动区域内部不同城市的分工协同和一体化发展具有重要价值。文章基于百度迁徙数据,利用PPML(Poisson Pseudo Maximum Likelihood)重力模型和交互项检验方法,分析长三角地区工作日、周末和节假日城际出行网络特征,并挖掘城际出行时间异质性的影响机制。结果表明:1)长三角地区城际出行具有明显的时间异质性特征,表现为工作日城际出行强度最低,周末倾向短途出行,节假日城际出行强度最高的特点;2)城际出行受到推拉力和中间障碍的影响作用。城市发展水平、个体出行诱因等推拉力要素对城际出行具有促进作用,出行成本和行政文化壁垒等中间障碍因素对城际出行具有阻碍作用,推拉要素的作用效果在不同时段具有差异性。

光伏板智能清洁机器人设计与实现

为有效解决光伏板表面灰尘覆盖问题,提高光伏电站光电转化效率,根据目前光伏板安装环境,设计一种光伏板智能清洁机器人。机器人由行走机构、清洁机构、控制模块以及各传感器组成,可在光伏板上自主进行清洁工作。对机器人的行走机构和清洁机构进行设计计算,再通过力学分析得出机器人运动稳定性条件,然后结合机器人功能对机器人的控制系统进行设计,最后制作出机器人样机。通过对机器人进行运动和清洁性能测试,此机器人可在25°以下的斜面上稳定运动,清洁机构对于浮尘或积垢类污渍都具有一定的清洁能力,且机器人可按照设计路径自主完成清洁工作。与传统清洁方式相比,在解决光伏板灰尘覆盖问题的同时,极大地降低了人工成本,减少了水资源的浪费。

一种电机直驱操动机构行程曲线规划方法

电机直驱操动机构过控制电机按照行程曲线运行,直接驱动高压开关实现分合闸动作。针对电机直驱操动机构行程曲线缺乏系统性规划方法,无法与机构运行特性相匹配,规划、验证及优化周期长,可移植性差等问题,结合多项式模型与负载特性模型提出一种电机直驱操动机构行程曲线规划方法。根据运动学和动力学分析,建立电机直驱操动机构负载特性数学模型。利用多项式模型生成行程曲线簇,并结合电机直驱操动机构及高压开关特性建立多目标优化算法,筛选出最佳行程曲线。仿真和实验结果表明,所提方案可以实现电机直驱操动机构及高压开关的稳定、可靠运行,与传统的行程曲线规划方法相比,可以实现10.3%的能耗优化,能够进一步提升控制系统整体功率密度。

真空断路器弹簧操动机构的优化

真空断路器触头弹簧压力增大会导致断路器无法可靠合闸,四连杆结构在一定程度上会影响机构的出力特性和机械效益,进而影响断路器合闸的可靠与稳定。文中分析了真空断路器的动作原理,建立弹簧操动机构的数学模型;对机构中的凸轮轮廓、传动拐臂的角度和尺寸、连板与合闸滚子的尺寸参数进行优化,建立弹簧操动机构的仿真模型。动力学仿真表明,优化后的触头弹簧压力增大了58%(从1 700 N提升到2 686 N),仍能保证断路器操动机构可靠合闸。试验结果显示,触头弹簧压力为2 500 N时断路器触头能够可靠吸合,平均合闸速度降至0.68 m/s,弹跳时间缩短了18.4%,整体优化后的方案满足设计要求并具有良好的可靠性与稳定性。

利用改进匈牙利算法求解旅行商问题

针对传统的匈牙利算法在求解旅行商问题(travelling salesman problem,TSP)时会导致多回路闭合的问题,提出了破环机制,设计了破环匈牙利算法。通过采用分配问题的描述方法对旅行商问题进行建模,并建立二者之间的转换关系,论证了TSP可行解的充分必要条件是对应分配问题的可行解与辅助边结合后仅包含一个环路,对6个标准旅行商进行测试和对比分析,验证算法的有效性。实验结果表明:在不同的数据集中,改进匈牙利算法能有效求出TSP问题的解。

行波磁场对Cu-Ni-Si-Mg合金组织和性能的影响

研究了在凝固过程中行波磁场对Cu-Ni-Si-Mg合金组织和性能的影响。结果表明,随着磁场电流强度的增加,在晶粒细化的同时,合金的组织形貌逐渐向等轴晶转变,树枝晶在磁场的作用下尺寸不断减小。磁场电流为90 A时晶粒细化效果最好,铸锭几乎全部由细小的等轴晶组成,晶粒尺寸降至(0.5±0.19) mm,相比于未加行波磁场的合金,晶粒细化了约94%。采用透射电子显微镜对显微组织进行观察,并对衍射花样进行标定,发现晶界处的析出相为δ-Ni2Si。在磁场电流为60 A的条件下,合金的拉伸性能最好,与未施加磁场的样品相比,屈服强度提高了41.8%,抗拉强度提高了12.9%,但合金的硬度不受行波磁场影响。本文通过行波磁场细化晶粒,为提高时效强化型铜合金的强度提供了一种可规模化生产的技术。

校地协同共育驻村文旅师运行机制探索研究——以无锡市为例

乡村振兴,需广招英才、高效用才。高校是乡村人才重要“供给源”之一,应在乡村人才建设方面发挥作用,承担责任。无锡市很多乡村探索农文旅融合发展致富之路,成果显著,但仍然存在乡村文旅人才匮乏、村干部创新思路有限、文旅发展势头放缓等诸多问题。基于校地协同共育合作模式,结合无锡乡村发展现状,探索符合时代发展需求的驻村文旅师制度,以拓宽校地协同合作路径,为推动无锡市乡村振兴提供坚强的人才支撑和智力保障。

基于演化博弈的城市公共交通出行激励机制研究

外部环境机制作为影响交通出行方式选择的要因,在交通流转移、缓解交通拥堵问题中起至关重要的作用。将激励机制引入公共交通管理机制,运用演化博弈的理论建立以出行人群和轨交公司为主体的复制动态方程,探索采用激励机制下主体双方的演化路径和演化规律,并应用Matlab对演化结果进行数据仿真验证。均衡点稳定性分析和仿真结果表明:合理的激励机制能够有效引导交通流转移至公共交通网络。同时,交通管理部门的监管程度与轨交公司的策略选择、外界社会的关注程度与出行人群的策略选择这两组变量之间有正相关性。

基于空间聚焦机制的混沌随机蚁群算法

为了提高蚁群算法在大规模旅行商问题上的性能,本文提出了一种基于空间聚焦机制的混沌随机蚁群算法(CRACS)。首先,使用空间聚焦机制将旅行商问题划分为几个子类;其次,提出了一种改进混沌随机蚁群算法来求解子类;最后,将各个子类路线进行聚焦,选择最优连接路线动态连接各个子类,形成旅行商问题的最优解决方案。本文选取不同规模的典型旅行商问题进行了仿真实验,实验结果表明本文提出的算法在大规模问题上具有优秀的性能,相比于其他智能算法具有更优质的解和更快的搜索速度。