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.     

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.     

Multichannel Strain-Gauging System Equipped with Microprocessor for Strength Measurements of Structures

The structure of a 64-channel microprocessor strain-measuring system designed for operation with strain gauges and thermal transducers is discussed. The system measures strain and temperature during strength and thermal-strength tests of structures of machines and buildings. The computer codes have been designed in the Borland C++ Builder medium for operations with isolated transducers (1/4-bridge mode), and in the modes 1/2-bridge, bridge, and thermal transducer. The system has been certified. The paper describes examples of its practical utilization in strength tests of struts of the Tupolev-154B airliner and of the undercarriage foreleg of an aerobatic airplane.     

Part family formation by memory association

Most of the part family formation methods are concerned with how to form the families as opposed to how to identify the families. However, a more appropriate approach would be to identify naturally occurring families since these methods are based on the production flow analysis, which uses already implemented routing data. This paper presents a new approach using the memory association of neural networks to identify naturally existing families. The developed system, Feature-Based Memory Association Network (FBMAN), operates by the exhaustive association approach which deals with the difficult problem of exceptional parts. Comparison with the results generated by other methods proves the effectiveness of FBMAN.     

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.     

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.     

Single-Electron Characteristics of a ФЭУ-184U Photomultiplier Tube

Single-electron and time characteristics of a -184U photomultiplier tube with a uviol window are presented. The -184U single-electron resolution can reach a value of 63–64%, and, in case of single-electron light-striking of the photocathode, the photoelectron transit time distribution (full width at half maximum) is 6 ns.     

Identification of Characteristic Features of Envelopes of Testing Pulses with the Help of the Diade Convolution Adaptable to Noise Level: I. Identification of Types of Characteristic Features

A method has been suggested for binary coding of envelopes of measured pulses from eddy-current transducers. The method enables one to identify their characteristic features of various types, such as leading edge, trailing edge, maximum, minimum, horizontal portion, start point of leading edge, end point of leading edge, start point of trailing edge, and end point of trailing edge, using weighted sums of no more than four Hadamard-ordered Walsh functions with numbers 0, 1, 2 ^n–1, and 2 ^n–1 + 1. The paper demonstrates the existence of obvious diade correlations of coded combinations corresponding to specific fragments with both one another and distortions of a current sampling simulated by adding an error vector. These properties make possible an identification of types of characteristic features in current samplings of binary data with four levels of a noise immunity, which are selected in the process of adaptation to the noise intensity with due account of the significance of identified features.     

A Stable Temperature Sensor Based on GaAs Structures with Schottky Barriers

The current–voltage and temperature–voltage characteristics of a GaAs structure with a Schottky barrier were measured, and their dependence on technological factors and temperature were determined. The main technological parameters of the device (the concentration of free carriers n ₀ in the base of diodes, the area S of the contact of the barrier-forming metal, and the value of the direct current I through the structure) were optimized. As a result, an element with a highly linear temperature–voltage characteristic was obtained. For Pd–GaAs structures with S 0.32 mm² (d 640 m), I 10 A, and n ₀ = (1–3) × 10¹⁶ cm^–3, the thermal sensitivity coefficient is 2 mV/°C, and the nonlinearity coefficient is < 0.5% within a range of 100 K, which is much lower than obtained theoretically. A highly stable temperature sensor is manufactured on the sensitive element offered.     

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'.     

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).     

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.     

Capacitive Discharge Excilamps

UV radiating sources on KrCl ( 222 nm), XeCl ( 308 nm), and XeBr ( 282 nm) molecules excited by a capacitive discharge are described. The sources have a simple design of the radiator and are characterized by a high radiation efficiency (up to 25%), a lifetime of up to 2500 h, and a radiation band half-width of 4–8 nm.     

The Tribological Properties of Monolayer KCl Films on Iron in Ultrahigh Vacuum: Modeling the Extreme-Pressure Lubricating Interface

The friction coefficients of thin KCl films deposited onto clean iron in ultrahigh vacuum are measured using a tungsten carbide tip. A rapid decrease is found in the friction coefficient from 2 for clean iron to 0.27 ± 0.03 after the deposition of 40 Å of KCl. Based on previous contact resistance measurements, this was proposed to be due to the completion of the first layer of KCl. The first-layer KCl coverage was measured by adsorbing deuterium onto an iron surface partially covered by KCl, where deuterium selectively adsorbs onto the iron. This revealed that the first monolayer is complete after the deposition of 40 Å of KCl and that the first-layer KCl film coverage _KCl ⁽¹⁾ is given by _KCl ⁽¹⁾ = 1 - exp(-0.39±0.02t), where t is the film thickness. XPS data suggest that heating a KCl film to 550 K causes it to wet the surface. This leads to decreases in the friction coefficients for thin KCl films in accord with the idea that friction is reduced by the first monolayer of KCl on iron. Temperature-programmed desorption data indicate that KCl in the first monolayer is 5 kJ/mol more stable than the multilayer consistent with the wetting behavior. Finally, the kinetic data are analyzed to suggest that the first-layer film is 2.6 Å thick.     

Magnetic-Powder Inspection of the Crystallographic Texture of Electrical Steel

A theoretical model of the formation of rhombic (in the case of an edge texture) or square (on cubic texture) indicator patterns upon magnetization of single crystals of electrical steel orthogonally to the (110) and (100) planes is described. The model is based on a solution of Maxwell's equations for a magnetostatic problem, with magnetic permeability introduced as a tensor. Two field sources are considered as limiting cases: (a) loop, short coil; (b) semi-infinite magnet, long coil. Two cases of permanent magnet diameters are considered: thin, d = 4 mm; thick, d = 20 mm. Two cases of density of magnetic charges are considered: (a) = const; (b) = ₀/ .     

Efficient Generation of Microwave Oscillations at Harmonics of the Conductance of a Gunn Diode

Basic characteristics of prototype oscillators operating at the second (19 GHz) and third (36 GHz) harmonics of the negative conductance of a 3715 Gunn diode are presented. The output power of these oscillators is 1.5–8.0 mW and the range of electronic frequency tuning is up to 390 MHz.     

An Automatic Data-Processing Technique for the High-Pressure Xenon γ-Ray Spectrometer

We describe an algorithm for radionuclide detection and identification by the -ray spectra recorded with a high-pressure xenon -ray spectrometer. The algorithm is based on the comparison of the measured spectra with the tabulated radionuclide data. The fitting criteria were formulated. The software package, implementing the algorithm and providing the execution of a complete cycle of -ray spectrum processing, was developed. The algorithm usability and efficiency were demonstrated by testing it with actual spectra.     

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.     

Portable Electromagnetic-Acoustic Thickness Meters (EMAT)

Two varieties of contactless electromagnetic-acoustic portable thickness meters with autonomous power supply, created on the basis of up-to-date digital technologies, are described. The instruments implement a new highly efficient design of magnetic field concentrator developed on the basis of new magnetic materials. The -- thickness meter is equipped with a powerful microprocessor-based data processing system, which expands the capabilities of the instrument. The -100 thickness meter is a small-size and small-weight instrument. The main advantage of both instruments is that they can be operated on corroded untreated surfaces without the use of a contact fluid. Both instruments are suitable for testing through coatings of considerable thickness (up to 2 mm) and can be operated under workshop and field conditions.     

An IGES pre-processor to integrate CAD and CAPP for turned components

EXCAP, is a knowledge-based process-planning system for rotational components. CADEXCAP is software which has been developed to integrate EXCAP with CAD systems via IGES (Initial Graphics Exchange Specification). CADEXCAP deciphers a full 2D model of a turned component developed on a CAD system and then via IGES it fully automatically generates a product model in a format suitable for EXCAP. CADEXCAP has a modular structure of three modules: readiges, preprocess and postprocess. The preprocess module, which is the concern of this paper, was written in FORTRAN77 to pre-process the IGES entities. The pre-processing process includes two main tasks. The first task is to extract only the necessary information from the IGES entities. The second task is to locate the entities in one coherent coordinate system, which is the model space coordinate system, using transformation matrices.