Computational transformation of signals of a measuring information system for eddy-current flaw detection

The features of a computational-transformation algorithm that is used for engineering implementation of an eddy-current nondestructive testing method using a combined multisector transducer with a magnetic field at different frequencies are described.     

A method of eddy-current flaw detection of bars and tubes based on the use of a combined eddy-current transducer with excitation of spatial magnetic-field components at different frequencies

The possibility of using the method of eddy-current testing using a combined multisectional transducer with a heterofrequency magnetic field is described. The technological implementation of this method for detecting flaws in bars and tubes under the conditions of significant transverse displacements is described.     

Portable BΔ-12HΦM and BΔ-12HΦΠ eddy-current flaw detectors

The scope of application, specific features of design and operation, and the main technical characteristics of portable BΔ-12HΦM and BΔ-12HΦΠ eddy-current flaw detectors are considered.     

舰船用气体分析仪检定装置的研制

研制了一种适合于舰船用气体分析仪的检定装置.舰船用气体分析仪检定装置采用气体混合比例泵动态配气,通过电路测试模块、波形测试模块、计算机数据采集模块对船用气体分析装备的主机及其接口的特征信号进行采集和诊断分析,检测所得信号与计算机进行双向通讯,由计算机命令各个诊断模块,然后由计算机中已存数据库与诊断数据相比较,从而自动诊断出船用气体分析仪的误差、稳定性、反应时间、灵敏度等各个技术参数的真实情况.通过计算机软件显示、存储、计算后,将各个参数绘成统一的报表,可直观、方便的辨别出舰船用气体分析仪器性能指标是否正常,达到对舰船用气体分析仪器的性能检测和故障诊断的目的.     

Determination and adaptive correction of calibration intervals of measuring instruments and systems

Methods of analytic determination of calibration intervals for off-line measuring facilities and means of determining the calibration intervals by simulation for redundant measuring systems are discussed.     

虚拟仪器的发展过程及应用

介绍了虚拟仪器的概念,产生,组成及分类,分析了其发展现状以及在电信、测量、监控、检测、教育等方面的应用。虚拟仪器有广阔的发展空间,并最终要取代大量的传统仪器成为仪器领域的主流产品。     

计算机化医学影像仪器的发展

医学影像学的发展非常迅速,本文总结医学影像仪器的发展,X线成像仪器,CT成像技术设备的基本结构,MR I的基本设备结构,CR的结构及PACS系统结构。这些仪器设备都与计算机联用,实现计算机化。     

安规测试仪用于塑料制品探伤检测

该文介绍了传统的超声波、渗透和射线等绝缘体探伤方法,分析了它们的优缺点,针对其缺点,提出了用安规测试仪探伤塑料制品的方法。实验中,设置安规测试仪为拉弧停止,试验检测合格品的最高耐受电压,高压扫描塑料制品,筛选出不合格品。其过程简单、高效、快速、准确而且经济适用,可以通过改造测试探头适应不同的塑料制品,能取得不错的检测效果。     

An eddy-current probe for testing the level of molten steel

An eddy-current probe of the level of molten metal for a sectional machine for continuous casting of steel is considered. The advantages of electromagnetic level sensors over radiometric ones lie in their insensitivity to the dross layer and high operating speed. The results obtained and directions of further studies are demonstrated.     

电磁铁涡流制动分析与设计

介绍了电磁铁涡流制动的工作原理.通过建立二维电磁场分析模型,对涡流制动系统进行了电磁场数学分析,推导并求解出了制动力和运行速度之间的关系表达式.同时,利用ANSYS有限元分析软件建立了电磁铁分析模型,通过改变励磁电流、气隙厚度、导轨厚度来求得这些参数对制动力和吸引力的影响,从而为涡流制动系统设计提供了依据.     

Long term plumb-line alignment of precise measuring instruments: an adaptive digital controller designed for an autoleveling platform

Plumb-line alignment can affect the sensors of precise scientific instruments. When its effect is one of the main contributors to the measurement uncertainty, the deviation from the true vertical must be continuously monitored or compensated. This paper describes a digital control system designed and tested for an autoleveling platform. Best performances are obtained with an adaptive digital compensator based on a convolution of the error signal. Although accuracy and resolution of the leveling transducer limit the ultimate sensitivity, laboratory tests showed that the controller kept for several hours the base-plate top within ±1?μrad. These performances are suitable for maintaining the alignment of relative spring gravimeters used by volcanologists in long-term gravity measurements.     

仿形磨边机的质量缺陷分析方法

仿形磨边机是一种广泛应用于加工各种薄脆性复杂外形产品的设备。仿形磨边机的常见产品质量缺陷有工件破裂、形状不准、精度不合格等。影响仿形磨边机质量缺陷的因素复杂多样,必须理解产品缺陷形成机理,找准缺陷产生的部位。本文提出了质量缺陷分析的新技巧,采用顺序查找的方法更容易找准缺陷原因和维修方向。     

Development of surgical instruments for implanting a flexible fixation device for the lumbar spine

A new flexible fixation device for the lumbar spine has been developed. This paper describes the development and evaluation of two surgical instruments required for implanting this device. Prototypes were designed, manufactured and then evaluated for use in surgery. Further evaluation was performed, if necessary, and the design finalized, in accordance with BS EN 12011. This process involved close collaboration between engineers and surgeons.     

Shape reconstruction of parallelogram flaw

To reconstruct the shape of the scatterer in elastic media, the authors deduce the Born approximation solution of the two-dimensional scattering problem, which includes the shape factor that embodies all information about the shape of the scatterer. Accordingly, the change in the shape of the scatterer only necessitates the number of the corresponding new shape factors. For a parallelogram void in a long Al rod, its shape factor can be obtained. In view of the definition of a characteristic function, the shape factor has a corresponding integral representation. Obviously, the shape factor can be considered as a Fourier transform of the characteristic function, which is reconstructed from the inverse Fourier transform. The integral equation is considered as the basic equation to reconstruct the shape of the scatterer. The identification of the geometrical character of a flaw is then given by the two dimensional inverse Born approximation in a low-frequency range. For the parallelogram void, a theoretical calculating identification is performed. At the same time, the numerical results are obtained by the finite element method.     

An eddy-current gauge for measuring the wall thickness of light-alloy drill pipes

The operating principle and design of an eddy-current transducer intended for in-service measurement of the wall thickness of light-alloy drill pipes are described. The block diagram and algorithm of conversion are provided for measurement-data signals from the eddy-current thickness gauge. The main technical specs are listed for a thickness gauge prototype.     

A generator of probing pulses for EMA flaw detectors

It is shown that an increase in the power of a probing-pulse generator is a desirable way to further increase the efficiency of EMA flaw detectors. A generator with an increased power was developed. Such a generator can form radio pulses of a current with a peak value of up to 200 A at a developed voltage of at least 500 V in an EMA transducer. The new generator is mainly intended for stationary EMA flaw detectors. It can supply transducers of virtually any type.     

Flaw detection of alloys using the eddy-current method

A subminiature transformer eddy-current transducer (ECT) that is intended for the study of different nonuniform materials, alloys, miniature parts, printed-circuit boards, and microscopic defects has been designed. A block diagram of the transducer is given and its basic technical characteristics ensuring localization of the magnetic field on areas of approximately 50 × 50 μm are stated. A scheme that uses a computer as a generator and receiver of signals from windings is proposed. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. The designed measuring system eliminates the main drawback of eddy-current transducers (the small area of the electromagnetic field), simultaneously significantly reducing the noise level due to the use of high-quality amplifiers and filters, and searches for defects in printed circuit boards, metal–dielectric–metal-junctions, and alloys of different metals. A measurement procedure that allows one to perform high-accuracy monitoring of flaws in different alloys is described. The eddy-current transducer was successfully tested on several objects, e.g., a 5.5-μm thick Al–Mg alloy and welded seams of 5-mm thick titanium plates, as well as other objects. The dependences of the ECT signal on the flaws in these structures are given.     

环境监测分析仪器的发展及展望

分析了我国环境监测分析仪器的现状及市场前景;介绍了分析仪器的发展趋势和环境监测分析仪器的发展重点;对发展分析仪器应采取的政策和措施提出了建议。     

Measuring instruments for shafts

Instruments for shaft measurement are considered for the example of Mahr (Germany) products. The instruments and measuring methods are described and their benefits are itemized.