Ultrasonic Testing for Defects in Complex Shaped Metal Products

Russian Journal of Nondestructive Testing - Automation is a topical issue in the development of methods and equipment for ultrasonic nondestructive testing. The conditions of modern industrial...     

Applying the Algorithm of Calculation in the Frequency Domain to Ultrasonic Tomography

Applying ultrasonic-tomography systems makes it possible to precisely determine the shape and dimensions of flaws with the aim of establishing the degree to which the flaws influence safe operation of tested objects. This problem is solved by using special algorithms that make use of echo-signals recorded by an ultrasonic transducer to generate synthesized images of flaws in the sample. The use of phased arrays in ultrasonic tomography is explained by their ability to provide exhaustive data about the internal structure of a test object, thus allowing formation of the high-quality synthesized images of flaws in the object. Increasing the speed of ultrasonic tomography by using phased arrays necessitates the development and implementation of fast data-processing algorithms. In this connection, of interest are calculation algorithms in the frequency domain, which ensure the high speed of producing synthesized images. An ultrasonic-tomography algorithm is proposed that is based on calculations in the frequency domain. The algorithm takes the complex nature of the propagation of ultrasonic waves into account and is connected with the presence of media with different acoustic properties (e.g., in the case of immersion tests). Possibilities offered by the algorithm are investigated by computer simulations using the licensed CIVA 2016 software package and experimentally.     

Study of Photodiodes Based on the InGaAs Structure with a Boundary Wavelength of 2.06 μm

Journal of Communications Technology and Electronics - I–V characteristics and spectral photosensitivities of photodiodes based on epitaxially grown hydrides of metal-organic compounds...     

Application of Nonuniform Fourier Transform to Solving Ultrasonic Tomography Problems with Antenna Arrays

Russian Journal of Nondestructive Testing - In ultrasonic tomography that employs the technique of digital focusing with an antenna (DFA), the problem of increasing the inspection performance is...     

Analysis of Current–Voltage Characteristics in UV AlGaN Heterostructure FPAs

Journal of Communications Technology and Electronics - UV visible-blind and solar-blind 320 × 256 photodiode arrays based on AlxGa1 – xN heteroepitaxial structures (AlGaN HES) and...     

Short-wavelength infrared array avalanche photodetectors on the basis of InGaAs heteroepitaxial structures

SWIR ADP 320 × 256 FPAs based on p–i–n photodiodes in InGaAs heterostructures have been developed and investigated. The typical InGaAs/InP PIN heterostructures are formed by Metal Organic Vapor Phase Epitaxy (MOVPE) on n⁺ type InP substrates. The InGaAs/InP PIN photodiodes performance have been estimated by measuring current-voltage characteristics. APD arrays are designed using a mesa-passivated avalanche photodiode device array of p–i–n junctions in heterostructure with common absorption and multiplication regions. The optimal operating point for managing avalanche application depended on various factors has been started at 15 V bias and the multiplication coefficient was of 2–4.     

Preliminary thermomechanical loading (warm prestressing) as a promising method for increasing the radiation resistance of the vessels of water-moderated water-cooled power reactors operating under high pressure

We study the influence of various modes of preliminary thermomechanical loading (warm prestressing) on the brittle-fracture resistance of heat-resistant pressure-vessel reactor steels with different levels of embrittlement induced by thermal treatment. The tests were performed on specimens 25, 50, and 150 mm in thickness with short and long cracks of various shapes in the temperature range 293–623 K, corresponding to the service temperatures of these types of steel. We analyzed the contributions of different mechanisms (such as residual stresses, strain hardening, and crack-tip blunting) to an increase in the brittle-fracture resistance of the investigated types of steel subjected to warm prestressing, the stability of the positive effect of warm prestressing for various times of holding of these metals under different working loads and at different temperatures, and the influence of the sizes of specimens on the optimal modes of warm prestressing and the characteristics of brittle-fracture resistance of steels after thermomechanical treatment. We propose an approach to the prediction of the influence of the modes of thermomechanical treatment on the behavior of the brittle-fracture resistance of cracked steels. Translated from Problemy Prochnosti, No. 2, pp. 38 – 55, March – April, 1998.