Sensitivity of the Electromagnetic Acoustical Technique for Testing Railway Rails by the Mirror-Shadow Method

A study of the sensitivity of the electromagnetic acoustical (EMA) technique for detecting manufacturing defects of railway rails by a mirror-shadow method (MSM) has been carried out. It has been found that the sensitivity of the MSM with the EMA technique using bulk shear ultrasonic waves is, in certain cases, considerably higher than the sensitivity of the traditional wet echo-pulse method or mirror-shadow method with the use of longitudinal waves. Therefore, in order to renovate or design new technical means of ultrasonic acceptance testing of rails in factories, it is advisable to use the mirror-shadow method of testing with bulk elastic shear waves polarized normally to the direction of rail rolling. This would make it possible to reduce the acceptance of intolerable internal flaws of manufacturing origin.     

Experience of nondestructive testing of the impact strength of rolled products made of low-carbon and low-alloy steels at the Nizhni Tagil Iron and Steel Works

The experience of long-term application of nondestructive testing methods for studying the impact strength of rolled stock made of low-carbon and low-alloy steels intended for construction is presented.     

The Structure and the Magnetic and Mechanical Properties of Steel M74 and the Possibility of Nondestructive Testing of Heat-Treatment-Hardened Rails

Dependences of the coercive force, the relaxation magnetization, the hardness, and the strength and plastic properties of steel M74, intended for manufacturing railroad rails, on its tempering temperature were studied. Hardened specimens have the martensite structure as well as the sorbite structure of different dispersity. Analogous dependences of critical fields, which correspond to the displacement of 180° and 90° domain walls during the magnetization reversal, and of the induced magnetic-anisotropy field were also analyzed. An MC-ИФМ magnetic structure analyzer was shown to be suitable for the nondestructive testing of the mechanical properties of finished rails. The correlation model is two-parameter; i.e., analyzer readings are used that were recorded after successive magnetization reversals of inspected sections of rails to magnetic fields corresponding to two different currents in the electromagnetic coils.     

Artificial magnetic conductor for various antenna applications: An overview

Artificial Magnetic Conductor (AMC) is a type of implemented metamaterial in several antennae and microwave design applications. By utilizing the unique characteristics of metamaterials which do not exist naturally, the performance of various microwave devices can be enhanced. This article elaborates on the technical perspective and recent works on AMC for antenna applications. The technical perspective discusses the theoretical aspects, simulation design procedures, and the measurement setup used to characterize the AMC unit cell. Subsequently, various recent works of antenna design that involve the incorporation of AMC are discussed thoroughly. Each of the recent works is highlighted with specific performance enhancements that can be achieved with the introduction of AMC. The conventionally narrow band property of AMC, which is the bandwidth at which the radiation characteristics and directivity of the antenna can be manipulated, is discussed. The property limits the applications of AMC in wideband antenna applications. One of the techniques to improve the narrow band AMC as the ground plane is discussed in detail. The employment of AMC has solved many issues whilst overcoming the typical limitations in conventional antenna designs.     

A multi to wideband frequency reconfigurable antenna

A frequency reconfigurable antenna with a simple design structure and biasing circuit is presented. The antenna is able to configure its frequencies to operate either in multiband or wideband modes. The antenna is fed by a coplanar waveguide transmission line. The reconfiguration characteristics of the antenna is achieved by using PIN diode switches. The operating frequencies of the multiband mode are designed within the wideband mode operating range, from 2 to 6 GHz. Both simulated and measured results of S₁₁, radiation pattern and realized gains are verified. The antenna allows a degree of freedom in providing the frequency reconfiguration from multiband to wideband mode and vice versa.     

Magnetic tests of hardness and structure of rail steel

The correlation between the coercive force on the one side, and the structure and hardness of the rail steel on the other has been studied. A technique for testing rails quenched in oil based on measurements of the coercive force has been developed. The technique can be used in acceptance tests of rails by stages of main rail-roads.