幕墙钢索张力测试装置的原理及性能分析

阐述幕墙钢索张力的测试装置,介绍张力机械式测试装置、频谱分析测试装置及电阻应变式测试装置的原理,并进行性能分析,最后给出应用实例.     

基于MC68332的剑杆织机纬纱张力测试系统

为了准确地测量剑杆织机引纬时纬纱的张力，合理地配置织机的工艺参数，采用单片机MC68332、主轴转角传感器、张力传感器、数据采集芯片、显示器等组成纬纱张力检测系统，实现对纬纱动态张力的实时测量，阐述了张力测试系统的原理和设计方法，并运用该系统时T196型剑杆织机不同纬纱的张力进行了测试和分析。     

多功能张紧装置设计与试验分析

为实验室的带钢抖动试验装置设计了一款具有张紧、张力检测及纠偏的多功能张紧装置。包括结构设计,传感器选型与标定,装置的安装与调试,系统的张力分析。由LMS动态测试与分析系统对张紧装置进行数据采集。试验结果表明:该装置基本实现了预设功能,可为带钢抖动试验装置提供额定的张力,测试动态张力,并防止铜带跑偏。在与张力的动态测试中发现,辊子转频在力传感器频谱图上表现明显。当电机转速n=120r/min、张力T=17.41N时,整个装置会出现比较明显的共振现象。其中采集到的各组动态张力是研究模型铜带抖动规律的基础数据之一。     

张力传感器在智能间歇提捞式抽油机上的应用

本文分别对智能间歇提捞式抽油机的发展背景、载荷测试原理、张力传感器的特点、载荷指标分析、安装结构设计和应用情况进行介绍。基于"三点弯曲法"原理的张力传感器,测试出抽油机柔性抽油杆的张力,从而测出智能间歇提捞式抽油机载荷。     

机械式位移传感器在幕墙钢索(预)张力测试中的应用

本文阐述钢索(预)张力测试概况,研究采用机械式位移传感器测试钢索(预)张力的原理、设计构思及精度计算,并给出幕墙钢索(预)张力位移测量计算实例。     

称重传感器在带式输送机胶带张力测试中的应用

提出了一种基于ATm ega8单片机和计算机控制的带式输送机胶带张力测试系统,它可以完成带式输送机胶带张力的测试,完成胶带张力的实时监控和张力曲线的绘制。该系统包括计算机和单片机,两者之间采用RS232进行数据通信。     

基于微应变的刮板输送机张力测试系统及特性分析

针对刮板输送机工作过程中刮板链张力及运行阻力的检测瓶颈问题,开发了一套基于微应变检测的刮板输送机张力测试系统,通过在刮板中安装应变片及无线信号收发装置实现对刮板链张力的检测,并对不同位置刮板链的张力及运行阻力进行分析。实验测试结果表明,刮板过链轮时最大瞬时张力为342.681 3 k N,刮板在同一链轮啮入点与啮出点的最大张力差值为46 k N,刮板输送机上端链的最大运行阻力为41.4 k N,下端链运行阻力为22.2 k N,测试结果与现场实际工况基本一致,系统的检测精度与可靠性较高。     

7500t浮吊重型锚绞车钢丝绳张力的测试方案

针对振华港机7 500 t浮吊重型锚绞车钢丝绳张力如何测试的问题,提出了3种张力测试的方案.由于方案中的诸多模糊因素,给出了运用模糊综合评判选择最佳方案的方法,并用此方法对张力测试方案进行评价.最后把评价结果转化为定量数值,从而确定最佳的方案.     

超声波传感器在自动化放线机中的应用

介绍了在线缆绕制行业中的张力控制装置,针对张力控制装置所采用的张力传感器进行了分析,根据总结发现的不足改用超声波传感器,并实际应用于为某电力公司设计制作自动放线机中,设备性能得到了极大提升,在测试和实际使用中取得了良好的效果。     

基于GPRS的电气化铁路线索张力监测系统

针对我国电气化铁路地域分布广、"空窗"时间短从而导致接触网线索张力采集困难这一问题,设计了基于GPRS的电气化铁路线索张力监测系统,分析了数据在通信网络中的传输过程,比较了GPRS模块与监测主机建立连接的不同方案,给出了监测系统的软硬件设计方案,并进行了相关测试。测试结果表明:该系统工作稳定,实时性好,可以满足铁路系统线索张力监测的应用需求。     

A CO2 tracer-gas method for local air leakage detection and characterization

A method for local measurement of air leakage rate is presented that can be used to accurately and quickly assess leakage rates across a surface, such as around a valve or hatch in a pressurized gas tank or a window in a building. The method uses a small local enclosure with constant volume placed about a region on the structure under investigation (e.g., a window), which is depressurized and injected with a small concentration of carbon dioxide as a tracer gas. The time variation of the pressure and carbon dioxide concentration inside the enclosure are monitored and used to quantify the leakage flow rate as a function of pressure difference. This method uses a small enclosure with internal mixing so that a quasi-steady-state condition is quickly achieved. Because of the small size of the enclosure, advanced data processing techniques are necessary to reduce uncertainty in determination of the rate of change of the carbon dioxide concentration that arises from sensor variability. Results of a laboratory demonstration of the proposed leakage detection and characterization device are reported for the problem of leakage through a circular hole in a plate with prescribed pressure differences. Experimental results from the laboratory tests are found to be in excellent agreement with results of a numerical simulation of leakage flow through a hole, as well as predictions from a number of empirical equations for this problem found in the literature.     

计算机辅助设计凸轮及其数控加工

介绍了如何利用计算机对于形状复杂和高精度的凸轮进行辅助设计,以及将设计结果直接在数控机床上加工的方法,分析了图解法设计的局限性和计算机辅助设计的优越性,指出了利用计算机辅助解析法设计是实现数控加工的基础,也是未来机械设计的发展方向。     

CMM Probing Accessibility in a Single Slot

This study presents a novel mathematical method for resolving the accessibility of a through slot when using coordinate measuring machines. The proposed method considers the actual shape of a probe consisting of a motor column, a stylus, and a probe tip. Also derived herein is a mathematical method to derive the feasible probe orientation of the measurement point in the bottom of a slot using a geometrical relationship between the probe and the slot.     

智能气体识别仪的研究

智能气体识别仪用以识别气体种类,它具有学习识别多种气体的功能。本文介绍了仪器的工作原理、特点及仪器的硬件和软件构成。     

Automated fixture configuration using projective geometry approach

The geometric and topological specification of a workpiece boundary is usually represented in a specific data format in a CAD database. To retrieve a set of workpiece data, to analyse its shape in addition to the machining requirements, and to determine the proper fixture configuration accordingly, are not trivial tasks when a part has a complicated shape. The real challenge is to recognise and synthesise the shape of a workpiece from its data representation. Consequently, the decision for fixturing can be made when the shape of a workpiece and the relationship of the shape and the fixturing configuration can be derived by a systematic methodology. In this paper, a projective spatial occupancy enumeration (PSOE) approach is applied as a representational and manipulating scheme for developing algorithms in automatic fixture configuration. The workpiece is projected onto the working plane of the fixture baseplate. A 2D projection is defined as a matrix of cells which can represent a workpiece with an arbitrary shape. Using a discrete search based upon the matrix of cells, the fixture types and their locations are generated according to a set of heuristic algorithms. This work is a generalisation and extension of previous works for prismatic parts. The same methodology is equally applicable in general robot grasping.     

An inverse shock response spectrum

The shock response spectrum (SRS) is a tool commonly used by application engineers that characterizes the severity of a transient acceleration. Due to the definition of the SRS, neither an analytical nor a unique inverse exists for an arbitrary function. An SRS presented without any temporal information makes creating a corresponding acceleration time history for an experimental or numerical study prohibitively difficult without a rigorous method to determine an inverse of the SRS (a corresponding time history). The present work develops a method to calculate an inverse of an arbitrary SRS using three sets of well characterized basis functions: an impulse function, a sine function/damped sine function, and a modified Morlet wavelet. These three basis functions are specifically chosen for the properties of their transformations: the impulse introduces a constant increase to the SRS above a given frequency, the sine wave introduces a narrow peak at a given frequency, and the Morlet wavelet introduces a plateau with an adjustable width and relative height. Using the definition of the SRS, the transformations of the basis functions are calculated and these expressions are used to derive a methodology for calculating an inverse SRS. The effectiveness of the method is demonstrated by several examples. The quality of an inverse SRS is evaluated by comparing the SRS of the inverse to the target SRS. This method is developed in order to provide a quick estimate of a corresponding time history; in applications where a higher fidelity representation of the SRS is needed than can be provided by the method developed, a genetic algorithm is used to optimize the coefficients of the basis functions. Given a sufficient number of basis functions for the optimization, the resulting SRS can almost exactly match a randomly generated target SRS that is nonzero over the frequency range considered. For applications in which the permissable basis functions are limited (such as for an experimental test apparatus), an extension of the genetic algorithm method is discussed.     

Robust scene recognition using a GA and real-world raw-image

This paper presents a new concept of scene recognition by a genetic algorithm (GA), using the 2-D gray-scale image of a working space, termed here as raw-image, and a model shaping the 2-D top-surface of a target object. In fact here, the problem of object recognition in the raw-image is changed into an optimization problem of a model-based evaluation function. We make use in this research of a GA, as a search and optimization method. This GA employs a model-based fitness function as its objective function to perform the search of a target in the raw-image. In this research, three object models, namely a frame model, a surface model, and a surface-strips model are investigated in order to determine which one is the best for scene recognition in a noisy environment. Also, in order to appraise the recognition performance of each model, a comparative study is performed by analyzing the answers to the following criteria questions: sensitivity, reliability, and speed. The effectiveness of the method has been verified through experiments using real-world raw-images, and the method has shown its robustness of object recognition with the surface-strips model, in spite of the noises in the scene.     

Spatial distribution and polarization dependence of the optical near-field in a silicon microfabricated probe

This paper reports on the spatial distribution and polarization behaviour of the optical near-field at the aperture of a Si micromachined probe. A sub-100 nm aperture at the apex of a SiO₂ tip on a Si cantilever was successfully fabricated by selective etching of the SiO₂ tip in a buffered-HF solution using a thin Cr film as a mask. The aperture, 10–100 nm in size, can be reproducibly fabricated by optimizing the etching time. The optical throughput of several apertures was measured. For a 100 nm aperture, a throughput of 1% was approved. The probe shows a very high optical throughput owing to the geometrical structure of the tip. The spatial distribution of the near-field light is measured and simulated using a finite difference-time domain method. The polarization behaviour of apertures with different shapes was analysed using a photon counting camera system.     

无磁热量表中的一种流量校准方法

热量表是计量热流回路所释放热量的智能仪器。它主要由流量传感器、配对温度传感器、主控MCU和液晶显示等部分组成。其中流量计量的准确程序直接决定了热量表的精度等级。论述了以TI MSP430F135作为主控MCU的热量表的工作原理，讨论了该叶轮式无磁热量表流量测量的动态校准原理，并给出软硬件设计及分析。     

A re-configurable cross-sectional imaging system for reverse engineering based on a CNC milling machine

This paper presents a novel reverse engineering digitizing system for full part geometry, which is based on a cross-sectional imaging device built in a NC milling machine. The system successively captures a picture for each planar cross-section contour of the part by end-milling and CCD imaging, and builds the geometry for both external and internal surfaces of the complex 3D part based on a set of the vectored cross-sectional contours. The system mainly consists of three components: a NC milling machine, a cross-sectional imaging device and a computer control unit. Some issues involving the principle and process flow of the system, encasing materials, cross-sectional imaging and NC code generation, etc. are described in detail. Built on an existing NC milling machine, a portable device for capturing the cross-sectional images is designed, which includes an isolated light source, a digital camera, a protective case, a rigid arm and a robust tripod. The device, connected to a computer control unit, serves as a highly flexible accessory for the NC milling machine, constructing the cross-sectional imaging system for reverse engineering. Furthermore, the error analysis and accuracy assessment of the system are also addressed. A typical case is discussed in detail to illustrate the applications of the system. Such a re-configurable digitizing system for reverse engineering offers a number of advantages, such as the functional extension of an existing NC milling machine, low costs, and rapid construction. As a result, this system provides a feasible and useful scheme for many enterprises to construct their own reverse measuring system based on existing equipment to aid in rapid product development and extend the function of existing equipment.