一种新型关节轴承寿命-扭矩试验装置的研制

本试验机主要用于检测关节轴承的寿命、磨损量及摩擦扭矩。本机最大特点在于用双力传感器结构来进行扭矩测量,这一结构克服了传统扭矩传感器测量轴承扭矩时的误差。本机能对试样实现径向加载及使试样内圈作摆动动作,径向载荷通过杠杆弹簧机构施加,摆动动作通过曲柄摇杆机构施加。扭矩和扭角由双力传感器和角度传感器分别测量,本机可手动进行摆角的角度调整。     

传动轴扭矩测量误差分析

传动轴扭矩测量是研究车辆动力系统性能的重要手段.介绍了传动轴扭矩精确测量的重要性,给出了影响传动轴扭矩测量精度的一些因素,并详细分析了由传动轴扭矩应变式测量方式、传动轴本身产生的弯矩以及传动系统带来的扭振对测试结果所产生的影响,为下一步更精确地测量传动轴的扭矩打下了坚实的基础.     

用动态水平基准测量系统实时测量船体横扭角和纵挠角

设计了动态实时水平基准测量系统,讨论了用该测量系统测量远望号测量船变形角的可行性及利用该系统测量船体横扭角和纵挠角的原理和误差项。依据测量船的实际需要确定了动态水平基准测量系统的关键技术指标,并分析了测量船体横扭角和纵挠角的测量精度。分析结果表明：系统对船体横扭角和纵挠角的测量误差均不大于3″,测量距离理论上不受任何限制,远大于200 m(测量船船体长度)。利用现有外场试验条件进行了码头停靠状态下远望号测量船两测量点间的船体横扭角和纵挠角测量试验,结果表明：利用动态水平基准测量系统实时测量船体横扭角和纵挠角的方法切实可行,不仅提高了测量精度,而且克服了传统的大钢管基准测量法体积大、重量沉,装调及维护困难等缺陷。实验显示,该动态实时水平基准测量系统的应用领域相对广泛。     

矩形截面杆弹塑性扭转变形分析

通过对矩形截面杆弹塑性扭转阶段进行有限元分析,得到了弹塑性扭转阶段的扭角-扭矩相关数据,通过MATLAB曲线拟合得到矩形截面杆弹塑性扭转阶段扭矩计算方程,并且对有限元分析数据进行了分析,总结出了矩形截面杆件弹塑性扭转变形的相关规律.     

非接触式船舶轴系扭矩监测装置的研究

船舶轴系的工作状态决定了其对推动功率的传递效率,而一种新型的船舶轴系扭矩监测装置可以利用光电测量技术对轴系进行实时监控.通过测量轴的扭转角,测算出扭矩.同时,设计了一种逻辑算法用于消除光电开关之间因温度或振动而产生的相位误差.该装置抗干扰性强,安装简便,可进行动态测量.     

皮带传动试验台的微机化测量系统设计

在对NF-Ⅰ型带传动试验台充分分析的基础上,提出了改造方案.根据试验要求及试验台的特点选择了测量扭矩及电机转速的传感器,实现了电机扭矩、转速的自动测量、数据显示和存储.在此基础上,还实现了计算机的数据处理,使试验更直观.本文详细论述扭矩测量系统的硬件设计和软件编程.     

嵌入式容栅传感技术及轴功率测试研究

针对旋转轴功率测试存在的传感器信号引线困难、安装空间受限、信号易受干扰的问题,设计了一种嵌入式容栅扭矩、转速传感器和测试系统.测试时在轴的两端分别安装容栅传感器,轴在受到扭矩时产生扭角,则两容栅的输出信号会产生一个相位差,通过测量相位差的变化得到扭矩.容栅传感器的差动结构提高了灵敏度减小了误差,容栅的嵌入式安装,将对被测轴的影响降到了最低.实验证明容栅传感器可靠性高,可以在环境要求严格的情况下长时间使用,并且无需通过滑环、无线或红外进行供电和信号的传输,克服了以上方式安装复杂、信号易受干扰的缺点.     

基于虚拟仪器技术的扭转试验机的改造

为了将虚拟仪器技术应用于传统的力学性能测试仪器,从一种常用的扭转试验机入手,采用了技术较为成熟的扭矩传感器．通过平衡力法测量扭矩,并采用光电编码器测量扭转角。应用应变电测原理及虚拟仪器技术,设计了虚拟仪器,建立了虚拟测量系统,实现了扭转试验的电测法改造。改造后的扭转试验方法已经在高校的实验室中付诸实践,效果良好。虚拟仪器技术应用于力学性能测试仪器,提高了力学性能测试的自动化水平,值得推广。     

压电式积累扭矩测试仪

压电式积累扭矩测试仪压电式积累扭矩测试仪采用压电式传感器作为传感元件，测量精度高，动态性能好，且工作性能稳定，寿命长。主要用于电动、气动冲击式（或称撞击式）螺刀积累扭矩的测量，也能测量静扭式（定扭矩）螺刀的最大扭矩。压电式积累扭矩测量仪可方便地安装在...     

基于FPGA的轴系扭矩光电测量装置的研究

设计一种以现场可编程门列阵( FPGA)为核心的相位差式扭矩测量装置,该装置基于光电原理,通过测量轴系扭转角来计算扭矩值,并采用Verilog HDL语言设计系统硬件电路,以Visual C++为开发平台编写上位机软件,通过串口通信将上位机与下位机相连,以实现数据采集、数据传输、数据存储、结果分析和作图的功能.通过实验,证明此装置的有效性和精确性.     

正则化参数自适应选取的声学CT温度场重建

声学CT温度场重建为不适定逆问题。正则化参数的选取对重建精度有重要影响。提出一种正则化参数自适应选取的温度场重建算法——ARPSM(adaptive regularization parameter selection by minimum change criterion)算法。该算法采用一种新的、称为最小变化法的正则化参数选取法,自适应地选取正则化参数,兼顾温度场细节重建和噪声抑制。模型温度场和实验室内均匀温度场的重建结果表明,与常用的L曲线法相比,最小变化法确定的正则化参数对应着更小的温度场重建误差。ARPSM算法具有较高的重建精度和较强的噪声抑制能力,可望用于仓储粮食温度分布监测等对重建质量有较高要求的应用场合。     

电容层析成像传感器场域剖分及图像重建算法

电容层析成像传感器的敏感场受多相流介质分布的影响，软场特性给图像重建带来很大困难，为了提高重建图像质量，对敏感场分布进行分析是非常必要的。采用有限元法，通过对敏感机理的分析，提出一种利用不等间距的场域剖分方法，对敏感场分布进行计算机仿真，依据敏感场计算的数据及测量结果，提出了基于遗传算法的图像重建算法。实验证明有限元模型是正确的，说明利用不等间距的剖分形式可以得到较好的仿真结果，重建的图像具有较高的精度。     

Total fractional-order variation regularization based image reconstruction method for capacitively coupled electrical resistance tomography

Compared with electrical resistance tomography, capacitively coupled electrical resistance tomography (CCERT) is preferred since it avoids problems of electrode corrosion and electrode polarization. However, reconstruction of conductivity distribution is still a great challenge for CCERT. To improve reconstruction quality, this work proposes a novel image reconstruction method based on total fractional-order variation regularization. Simulation work is conducted and reconstruction of several typical models is studied. Robustness of the proposed method to noise is also conducted. Additionally, the performance of the proposed reconstruction method is quantitatively evaluated. We have also carried out phantom experiment to further verify the effectiveness of the proposed method. The results demonstrate that the quality of reconstruction has been largely improved when compared with the images reconstructed by Landweber, Newton-Raphson and Tikhonov methods. The inclusion is more accurately reconstructed and the background is much clearer even under the impact of noise.     

A fast surface reconstruction method for fluorescence molecular tomography based on cross-beam edge back projection

An accurate surface reconstruction method is important to fluorescence molecular tomography (FMT) for it provides boundary information of the domain occupied by the image object which is essential to modeling light propagation in free space and inside the object. In this paper, a method based on cross-beam edge back projection (CEBP) is proposed to achieve fast and three-dimensional (3D) surface reconstruction for FMT. This method consists of a cost effective and easy-to-implement setup; it back-projects the edge of an image object of all projection angles along the actual light propagation path to perform 3D surface reconstruction. Simulation studies and experiments were performed to compare the reconstruction accuracy and computational cost of the CEBP based method and the conventional radon transform (RT) based method. Results demonstrate that the CEBP based method significantly accelerates surface reconstruction compared with the RT based method while keeping similar accuracy.     

复杂散乱点重构方法的研究与实现

复杂散乱点重构技术历来是实物逆向工程中的关键技术.在深入分析现有经典的重构方法基础上,提出了一种基于三角域上改进的NURBS曲面重构方法.在复杂散乱点上进行基于Delaunay的三角刨分并重构出品质优良的Bezier曲面,然后在它的约束下完成NURBS曲面的二次重构.开发了复杂散乱点重构模块FastForm,并以IGES作为数据通讯接口搭建了一个实现反求全过程的反求平台,通过电话听筒实例验证了该反求系统的实效性.     

面向导弹天线罩精密加工的三维曲面重构

导弹天线罩的精密加工,属于自由曲面精密加工的范畴,它对天线罩以及导弹的性能起着至关重要的作用。根据测量所得的天线罩几何表面的离散数据点,结合对其综合电气性能测试数据的处理和分析,实现原始曲面的重构,并由此构造出要求的曲面,再进行分析和规划,实现按需去除加工,是实现对其精密加工的关键。以及三次B样条曲面方法为工具,利用其良好的几何特性以及简单有效的算法,实现了天线罩廓形曲面的重构,为在计算机上实现曲面绘制提供了理论基础。求算的等距面方程,为数控加工中刀具轨迹的规划奠定了基础。     

A new nonlinear reconstruction method based on total variation regularization of neutron penumbral imaging

Neutron penumbral imaging is a significant diagnostic technique in laser-driven inertial confinement fusion experiment. It is very important to develop a new reconstruction method to improve the resolution of neutron penumbral imaging. A new nonlinear reconstruction method based on total variation (TV) regularization is proposed in this paper. A TV-norm is used as regularized term to construct a smoothing functional for penumbral image reconstruction in the new method, in this way, the problem of penumbral image reconstruction is transformed to the problem of a functional minimization. In addition, a fixed point iteration scheme is introduced to solve the problem of functional minimization. The numerical experimental results show that, compared to linear reconstruction method based on Wiener filter, the TV regularized nonlinear reconstruction method is beneficial to improve the quality of reconstructed image with better performance of noise smoothing and edge preserving. Meanwhile, it can also obtain the spatial resolution with 5 μm which is higher than the Wiener method.     

基于混沌相空间重构的数控机床运动精度演化分析

数控机床运动精度状态的变化是一个复杂非线性动力系统的时空演化过程,难以通过数学建模方法分析其演化规律。提出基于混沌相空间重构理论的数控机床运动精度演化分析方法。根据混沌系统内在的规律性和有序性,分析基于相空间重构的数控机床精度演化原理,对数控机床运动精度的一维时间序列进行相空间重构,从而得到与原系统拓扑同构的高维相空间。提出用相点轨迹描述运动精度在相空间中的演化规律,构造一个非线性演化模型,用相点的多维分量构成输入向量,对其精度趋势进行演化。实验结果表明,基于混沌相空间重构的演化模型,可以很好地追踪数控机床运动精度的演变趋势和规律,且具有较高的演化精度。     

基于UG的产品设计特征继承与重构

特征继承与重构技术是原有设计特征的再利用,是对产品形态的创新设计和变形设计,对产品造型概念设计的形成具有重要的研究价值.介绍目前特征继承技术的研究概况.结合面向对象技术和特征技术,对面向特征继承的特征分类方法、特征重构技术的基本算法进行了研究,并以此为基础,在UG环境下利用OPEN API函数,实现了凸台类、腔孔类、沟槽类、倒角类等特征的继承和重构算法,并将其成功地运用到手机下盖的造型概念设计中.     

Three-dimensional reconstruction from a single-exposure,random conical tilt series applied to the 50S ribosomal subunit of Escherichia coli

We present a new reconstruction method that takes advantage of the fact that many biological macromolecular assemblies show a preferred orientation with respect to the plane of the specimen grid in the electron microscopic preparation. From one micrograph taken of such a specimen tilted by a large angle, a conical tilt series with random azimuthal angles can be extracted and used for a three-dimensional reconstruction. Our technique allows the determination of the molecular structure under low-dose conditions, which are not achievable with reconstruction methods that use conventional tilt series. The reconstruction method combines a number of existing image processing techniques with a newly developed weighted back-projection algorithm designed for three-dimensional reconstruction from projections taken with arbitrary projecting directions. The method is described as it was applied to the three-dimensional reconstruction of the structure of the 50S ribosomal subunit of Escherichia coli (E. coli).