Data-processing algorithms for automatic operation of ultrasonic systems with coherent data processing

Two algorithms for the automatic determination of flaw parameters during ultrasonic testing of welded joints with a high level of structural background noises are considered. The experimental data collected in the course of automated ultrasonic testing (AUT) using Avgur series with coherent processing of data (Avgur 4.2 and Avgur 5 systems) and the results of the assessment of nondestructive testing data are used. The first algorithm is used to identify zones where flaws may be located. This algorithm is applied after running AUT in the search mode. If the parameters of the algorithm application are selected properly, this algorithm makes it possible to determine the coordinates and the conventional length of the identified flaws. The second processing algorithm is intended to determine the flaws actual length and height. For its operations the algorithm uses the images obtained from coherent data processing. Results of testing methods for automatic (computer) determination of flaw parameters are cited. These results are obtained by the Avgur system during testing of austenite welded joints in stainless-steel pipes with a diameter of 325 mm and in perlite-steel pipes of various diameters.Translated from Defektoskopiya, Vol. 40, No. 12, 2004, pp. 3–15.Original Russian Text Copyright © 2004 by Badalyan, Vopilkin, Dolenko, Orlov, Persiantsev.This revised version was published online in April 2005 with a corrected cover date.     

A novel representation of tandem systems with inter-stage storage applied to on-line system monitoring

One of the goals of operating a tandem manufacturing system with finite inter-stage storage and asynchronous operations is to meet the demand without over-producing, under-producing or carrying large quantities of material in storage. We believe that analysing the operation of such a system on a real-time basis helps achieve this goal. The first step in this real-time analysis would be to quantitatively associate the causes and effects of over-production or under-production as they occur. This requires determining the cumulative effect that the performance that any stage has on the system, based on its history, the current system state and the interrelationships between the stages. This paper proposes a method which first represents uniquely and completely each stage and surrounding storage as an element. While this system, which consists only of this simple type of element functions in exactly the same way as the original one, each element is put into an ideal world for decoupled measurement. Though an element behaves in exactly the same way whether it is in the ideal world or in the real world, the elapsed times in the two worlds since the beginning of production can be different, since the responses (occurrences and durations of the blockings and starvations) of the two worlds can be different. A phase parameter is introduced for each element to represent this difference. Once the formation of the phase parameter of the output element is formulated, quantitative relationships between causes and effects of over-producing or under-producing can be explained as they occur.     

An Energy Source Based on Helical Explosion–Magnetic Generators for High-Impedance Loads

A transportable standard module developed at the Institute of Experimental Physics as a component of an energy source for modeling current pulses of positive lightning is described. The source is designed as a combination of several unified helical explosion–magnetic generators with output transformers and an inner diameter of the stator of 200 mm. According to our calculations, the source generates current pulses with an amplitude of up to 100 kA in loads with an inductance of 100 H and a resistance of several tens of ohms. The results from testing a typical module operating with a circuit having an inductance of 100 H and a resistance of 4 are presented. The experimental data coincide well with the results of a mathematical simulation of the module's operation.     

Model of a Surface Flaw and Calculation of Topography of Its Magnetic Field for Tangential Magnetization by Alternating Magnetic Fields. Quasi-Stationary Case

A model of a surface flaw is proposed. The model describes topography of the magnetic field for tangential magnetization by an alternating magnetic field H at a frequency . It is shown that H can be represented in the form of two multipliers: one describes the dependence on the (X, Z) coordinates and the flaw parameters (the depth h and the opening width 2b) and the other describes the dependence on the electrophysical properties of the tested material in which the surface flaw is located (the specific conductivity and the relative magnetic permeability ). The computational model proposed makes it possible to describe the magnetic field topography ( = 0) reducing it to the quasi-stationary case and extend representations on the formation of magnetic fields induced by surface flaws with allowance of the magnetization frequency . The data on processing the experimental dependences in accordance with the proposed computational formulas give satisfactory results which confirm the validity of the computational model proposed in the study.     

A Two-Section Gas-Filled Ionization Chamber for Neutron Flux Measurements

A promising design of a -type two-section gas-filled ionization chamber is described for the first time. A relationship between the design parameters, gas pressure, and characteristics of the material is determined, under which full compensation of the background currents from the -radiation and the measurement of thermal neutron fluxes in a range of 400 to 7 ×10⁹cm^–2s^–1at a load characteristic with a 5% nonlinearity are provided. Test results of the chamber are presented.     

A Study of Distortions in Double-Sided Emulsion Films by FoMos

FoMos makes double-sided emulsion tapes. Films of desired size cut from such tapes are used as emulsion trackers. The technique for measuring distortions is described, and the results of measurements are presented for several films cut from different sections of a standard piece of double-sided tape with a length of 7 m and a useable width of 20 cm. The standard plastic base of the tape under investigation is 190 m thick; 50-m-thick layers of diluted PX3 emulsion–gel are applied to its opposite sides.     

Automated Devices for the Testing of Mill Rolls

Multichannel -type devices developed at TsNIITMASh for the automated ultrasonic inspection of cylindrical objects, such as mill rolls, shafts of turbines and compressor units, circular welded joints of thick-walled shell rings, etc., are described. These devices feature from two to eight acoustoelectronic channels. Acoustic contact occurs through industrial water. The testing is performed under workshop conditions; the object being inspected is rotated by a turning lathe or any other handling mechanism. Sonication is simultaneously performed by piezoelectric transducers (PETs) with input angles of 0, 40, 50, 60, and 70° and also by surface and head waves in order to reveal surface and subsurface flaws. A wide-span eddy-current transducer of special design is also used for this purpose. All data are stored in flash memory and retrieved on a PC located in an office. The inspection results are displayed as C- and B-type scanning defectograms. Moreover, it is possible to obtain an isometric image of flaw zones. -type devices have been used for over one and a half years in two workshops at OAO Severstal'.     

Time-of-Flight Trigger Based on a Time-to-Amplitude Converter

A time-of-flight trigger based on a time-to-amplitude converter and differential discriminator is described. The trigger has a short decision time (60 ns) and high (100%) efficiency of useful event selection.     

Error Corrections in a Sampling Sliding Along a Pulse Envelope Based on Decoding Tables

Code combinations of 2 ⁿ symbols +1 and –1 suggested for identification of characteristic features leading edge, trailing edge, maximum, minimum, horizontal portion, start of leading edge, end of leading edge, start of trailing edge, and end of trailing edge in a binary-code envelope of a pulse measured by an eddy-current transducer (ECT) scanning a tested surface generate a group code. This group code ensures for four levels of noise immunity the maximal likelihood in identification of reference sequences distorted by noise. The structure of a product code, which is also generated by the reference fragments, results in a higher capability of correcting for errors in moving samplings of signal envelopes, in particular, it reduces the degree of uncertainty in identification of the most important features of ECT pulses. The paper suggests simple decoding algorithms and regular logical structures that provide a high efficiency of the procedure eliminating errors in binary sequences of coded envelopes.     

Ultrasonic nondestructive testing by head waves: Physical prerequisites and practical use

In 1972, studies on ultrasonic testing of metals from equipment at nuclear power stations performed at TsNIITMASh revealed a phenomenon of excitation of longitudinal waves with angle probes and their further propagation along the contact surface. This phenomenon was further comprehensively studied and called head waves in ultrasonic nondestructive testing of metals. Head waves have found use in practical ultrasonic testing both in Russia and abroad. This paper presents some principal points of the development of the theory and practice of ultrasonic testing by head waves.Translated from Defektoskopiya, Vol. 40, No. 9, 2004, pp. 27–37.Original Russian Text Copyright © 2004 by Razygraev.This paper is based on the materials reported by the author at the International Forum of Specialists of Universities, Research Institutes, and Companies from Different Countries of the World Ultrasonic Nondestructive Testing-75, St. Petersburg, Russia, February 4–5, 2003.     

Interferometric Methods for Surface Testing. High-Order White-Light Interferometer

A high-order white-light interferometer for three-dimensional fast noncontact testing of optical surface profiles is described. The device ensures measurements of absolute flatness deviations to an accuracy of /1000 within a wide technological field of 80 mm (the resolution in the plane is 0.1 mm).     

An Automated Setup for Investigating the Temperature Dependence of the Permittivity Spectra of Polar Liquids in the Range of 0.1–1.25 GHz

An automated setup for measurements of the temperature dependences of permittivity spectra is described. It uses an irregular microstrip resonator and allows measurements to be performed at a junction of methods using lumped elements and electrodynamic systems with distributed parameters. Measurements can be carried out without expensive thermostabilization devices in the temperature range of 200–350 K with a step of 1 K. The temperature dependences of the permittivity of polar liquids—water, methanol, and ethanol, whose dielectric relaxation regions lie within the frequency range of 0.1–1.25 GHz—are presented. Comparing the measured values of the permittivity to the Debye curve calculated from the reference data shows agreement within the limits of 3% for and 1% for . The random error of measurements was 2–3% for and 5–7% for .     

Assessment of the Hazard Level (Depth) of Flaws Using a ВД-12НФМ Eddy Current Flaw Detector

The operation features and the main technical characteristics of the -12 eddy current flaw detector are considered. A method is proposed for testing complex-shaped parts with the use of holding attachments and a specialized transducer with a slanted sensitive element. The capabilities of the device in assessing the hazard level (depth) of a flaw are shown. The distinctive features of the -12 eddy current flaw detector are presented.     

Thermal Nondestructive Testing of Buildings and Builded Constructions

A thermal nondestructive testing method ensuring the determination of characteristics of tested objects from an analysis of their temperature fields including the heat engineering characteristics of buildings and builded constructions with the use of the thermal imaging technique of recording the temperature fields is developed. The method is based on solving the inverse problem of time-dependent heat transfer in a multilayered three-dimensional domain. A method of simplification of solving the inverse problem, namely, the simplification of the total plausibility functional by separating the implicit dependence on a part of the parameters is proposed. A specific realization of the industrial testing of an object under full-scale environmental conditions is considered with reference to thermal nondestructive testing of envelope structures of an apartment house.     

Modelling and forecasting industrial innovations via the transfer function S-shaped learning curve

Algorithms are derived for the four-parameter transfer function S-shaped curve, using a least-squared-error (LSE) method for an exponential function. The S-shaped curve is just one in a family of industrial dynamics learning-curve models of increasing complexity which may be used to replicate and forecast the start-up of industrial innovations.Controlled experiments are undertaken, via simulation of message and noise, to test the modelling and forecasting capabilities of the algorithms. A number of strategies are introduced to improve forecasting performance, such as boots-trapping, sequential and parallel adaptation, and alternatively adopting the simplified three-parameter S-curve model.Four examples of modelling industrial innovations via the transfer function learning curve models are presented. The paper concludes that although there is now the capability to model the general four-parameter S-curve, its applications are limited. This is because simpler (and hence less accurate) transfer function models tend to be more robust.     

Formation of High-Power Pulses of Nanosecond Duration by Generators on Reverse Switch-on Dynistors with Sharpening Circuits Based on Diode Opening Switches

The basic principles of constructing generators of nanosecond pulses on reverse switch-on dynistors with sharpening output circuits based on diode opening switches are considered. The results of an experimental study of a high-power generator incorporating such a dynistor; a step-up pulse transformer; and a high-voltage diode opening switch, which is an assembly of drift step-recovery diodes connected in series, are presented. The output voltage pulses of the generator with an amplitude of 45 kV, a duration of 50 ns, a rise time of 10 ns, and a repetition rate of 1 kHz are applied to a load resistance of 25 .     

A Position-Sensitive Detector for the Polarized-Neutron Spectrometer

A linear detector of thermal neutrons, developed at the Laboratory for High Energies (Joint Institute for Nuclear Research), is used in the polarized-neutron spectrometer of the -2 reactor (JINR). The data are acquired in the regime of frame-by-frame survey to select neutrons with a wavelength = 1–12 Å by the time of flight. The neutron-detection efficiency is 70% for a wavelength of 2 Å. The detector exhibits a low sensitivity to -rays, a differential nonlinearity of 1.5%, and a spatial resolution of 1.5 mm at counting rates of 10⁵events/s.     

Detection of the Increment of an Instantaneous Phase in a Long-Base Laser Meter of Small Vibrations

A phase meter for processing signals of a laser meter of small displacements and vibrations at long base distances is described. Vibrations of objects are transformed into small increments of a signal phase at an RF carrier, which are detected by the phase meter and are outputted as signals proportional to microvibrations in the acoustic range. At a given carrier frequency f _c = 10.7 MHz, vibrations are detected within a band f = 3 kHz. Such vibrations produce phase fluctuations of 10^–42, which correspond to magnitudes of 1 nm for a laser wavelength 10 m.     

Development of a knowledge-based manufacturing modelling system based on IDEF0 for the metal-cutting industry

This paper looks into a new area for knowledge-based system application, that of manufacturing modelling. The objective is to develop a knowledge-based manufacturing modelling system that can be used to build company-specific as-is and to-be IDEF0 models, and can therefore greatly reduce the turnaround time and effort involved in IDEF0 modelling of manufacturing systems, which can be time-consuming if done manually or even with the aid of a commercially available software package like DESIGN/IDEF. This is especially so when the systems being modelled are large and complex. Besides, there is also the inconsistency problem associated with conventional IDEF0 modelling systems owing to the terms and terminologies in IDEF0 not being precisely defined, and hence being subject to individual interpretations. In this paper, a knowledge-based IDEF0 modelling system that can not only automate the tiresome and time-consuming process of manufacturing modelling but can also eliminate the inconsistency problem is proposed. The paper explains the knowledge-based approach to automated generation of IDEF0 models, and also identifies the kinds of domain knowledge that are required for the construction of the knowledge-based manufacturing modelling system.     

The СПРУТ-VI Instrument Complex for the Mir Orbital Station

The basic elements of the instrument package program for orbital stations are presented. The characteristics of the -VI equipment developed for the Mir orbital station within the framework of this program are described. This equipment allows the simultaneous recording of the characteristics of near-earth space (electron, proton, and nucleus fluxes, magnetic fields, and low-frequency electromagnetic waves) and their effect on the elements of spaceborne equipment and systems. The mass of the equipment is 16 kg; the power consumption is no more than 20 W.