管片拼装机提升系统动力学分析与试验

在考虑液压弹簧力和液压摩擦力的基础上建立了管片拼装机提升系统的动力学模型,对管片拼装机提升系统的振动特性进行仿真,分析了管片拼装机在拼装不同位置管片时扼架的振动特性,并进行试验测试,提出了拼装机提升系统的抑振方法.结果表明:在拼装不同位置的管片时,拼装机扼架存在等幅周期性振动,振动速度范围为8～35 mm/s,振动位移...     

盾构机管片拼装机振动与摩擦分析

针对盾构机管片拼装过程中,管片拼装机运行到水平或者垂直位置时发生剧烈振动和产生噪声的问题,对管片拼装机的运动机制进行分析,利用ADAMS对管片拼装机进行运动学和动力学仿真分析,得到运动过程中关键部件的受力情况。仿真结果表明:管片拼装机运行至水平和垂直位置出现振动和噪声可能的原因有2种,加工精度不够导致摩擦力过大和接触应力比较大的接触面由于空隙发生碰撞。提出在空隙间增加金属橡胶涂层来减少接触面之间接触应力的解决方案,并通过ADAMS仿真验证该方案能减少接触应力,从而能有效消除振动和噪声。     

基于数字样机的TBM管片拼装机运动学和动力学仿真

针对全断面掘进机管片拼装机在设计过程中的约束变量多、干涉情况复杂和设计周期长等问题,进行管片拼装机运动学和动力学仿真的研究.首先对管片拼装机进行了运动学分析,然后利用Pro/E进行三维设计,最后将三维模型导入ADAMS中进行动态仿真.通过对该机构的仿真分析,得出各主动件的速度和驱动力曲线;以空间搜索的方法,找出各主动件的最大速度和最大驱动力,从而获得了管片拼装机的运动学和动力学特性,为机构设计及动力系统的选型设计提供了依据,缩短了设计周期.     

基于虚拟样机技术的隧道掘进机管片安装机的施工仿真

在Pro/E软件中建立隧道掘进机(TBM)管片安装机数字化模型,并通过接口Mechanism/Pro导入ADAMS中建立管片安装机的虚拟样机.应用step函数对管片安装机中的主要驱动进行拟合,并以秦岭隧道为例计算单一管片安装所用平均时间,对管片安装过程进行动力学仿真分析.比较结果分析得出在管片拼装机不同工况条件下安装机大梁所受的载荷情况,利用ANSYS软件在已知载荷条件下对安装机大梁进行有限元分析,得到管片安装机大梁的应力和变形情况并进行结构强度校核,为拼装机大梁的结构优化提供依据.     

管片拼装机回转啮合系统动力学特性分析

针对管片拼装机工作特点,利用有限元软件与动力学仿真软件,建立考虑回转驱动系统实际结构、支撑刚度、轮齿变形的回转驱动系统刚柔耦合动力学仿真模型.分析管片拼装机安装不同位置管片的动态过程,研究回转驱动系统的载荷变化规律.在此基础上进行动态模拟,分析啮合齿轮角速度变化等动态响应特性.对比分析发现,增大大齿轮的回转支承刚度能够提高回转啮合系统的传动平稳性和回转系统的定位精度.     

基于AMESim的盾构管片拼装机液压回转系统仿真分析

根据盾构管片拼装机液压回转系统,建立管片拼装机液压回转系统的AMESim模型,进行不同参数下液压回转系统仿真分析。仿真分析结果表明:管片拼装回转速度与柱塞泵排量、比例阀开口度基本成正比,压力补偿器与比例阀的配合使用能够减小管片负载波动对回转速度稳定性的影响,管片拼装回转系统的调速性能良好,仿真结果能够为管片拼装液压系统的优化及实际操作提供理论依据。     

基于ADAMS的管片拼装机多体动力学仿真

利用ADAMS仿真分析软件，对全断面掘进机TBM后配套设备中管片拼装机工作过程的几种典型工况进行分析，初步得出管片拼装过程中的速度和加速度以及各种典型工况中拼装机所承受的最大转矩。为拼装机的设计提供了有力的依据。     

海底钻机收放机构动力学仿真与优化设计

为确保海底钻机收放机构工作的可靠性,对收放机构进行动力学仿真和优化设计。首先,介绍了钻机收放机构的组成和工作原理,分析了四级海况中母船的运动情况;其次,建立了钻机收放机构的三维模型并导入ADAMS软件进行动力学仿真分析,得到了收放机构液压缸在四级海况下的受力曲线;最后,以收放过程中液压缸最大受力值最小为优化目标,对收放机构各铰接点布置进行了优化设计,并将优化后得到的结果代入模型重新进行动力学仿真分析。结果表明,优化后收放液压缸的最大受力显著降低,且整个钻机回收过程中液压缸受力变化幅值较小,满足收放机构设计和工作要求。通过对优化后模型的动力学仿真,得到优化后收放机构关键部件的运动规律和各铰接点的受力变化情况,为后续收放机构运行平稳性分析及关键构件有限元分析提供参数指导。     

管片拼装机回转系统齿轮啮合动力学分析

为了研究管片拼装机回转系统齿轮啮合的动力学特性,以管片拼装机小齿轮-大齿圈的传动系统为研究对象,采用集中参数法建立了考虑齿面摩擦的六自由度直齿轮动力学模型,依据管片拼装机实际工况参数,利用Runge-Kutta方法分析了管片拼装机回转系统在空载和负载两种工况下小齿轮和大齿圈的振动位移情况,对管片拼装机回转系统进行了振动测试,验证了模型及求解的正确性,并提出了可以通过增大管片拼装机回转系统刚度来减小振动的方法。研究结果对管片拼装机回转系统的减振和降噪处理,以及提高管片拼装机回转系统的精度有重要的理论和实用价值。     

隧道管片拼装机变负载拼装技术探讨

隧道管片拼装机作为土压平衡盾构机施工的关键部件,其性能关系到管片的拼装效率。在地铁施工过程中,管片机在旋转过程中出现抖动现象,影响管片拼装的质量和施工进度。主要对管片拼装机液压马达旋转平衡块的设计和改进进行详细研究,以及液压半桥在平衡阀先导控制中的应用。通过理论分析解决施工过程中管片机的抖动现象,以达到理想的响应速度和运行平稳性。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...