Methodology of using delay-time analysis for a manufacturing industry

This paper has been written to give a methodology of applying delay-time analysis to a maintenance and inspection department. The aim is to reduce downtime of plant items and/or reducing maintenance and inspection costs, taking into account the possible environmental impact of a failure in terms of cost, both to the company and the environment. The paper also attempts to give a subjective measure of the consequences of such a failure in terms of cost to the environment, in monetary value to the company and the damaging effect to the company image.     

Methodology for Mapping the Residual Stress Field in Serviced Rails Using LCR Waves

Thermal barrier coatings (TBCs), as effective thermal protection separating the substrate from high-temperature combustion gases and reducing the substrate temperature, are widely used in aerospace and other fields. During the service cycle of life, surface crack defects, interface disbond defects, and coating thickness changes are the main non-destructive testing (NDT) objects of TBCs. In this paper, the main active infrared thermography NDT techniques including the optical infrared thermography testing, the ultrasonic infrared thermography testing, and the microwave thermography testing techniques are reviewed. Through the summary and highlight of the detection principle and application status of these state-of-the-art techniques, the development of the active infrared thermography DNT technique in TBCs is presented. By comparing the sensitivity, advantages, and disadvantages of the techniques in TBC NDT, can provide a significant reference for researchers to choose an appropriate method. It is noteworthy that fabrication techniques of artificial defects for calibration of the active infrared thermography NDT technique inspection of TBC systems are also reviewed. Moreover, future trends in NDT for the TBC system based on the active infrared thermography NDT technique are also discussed and analyzed.

     

Dosimetry with a recombination chamber in outdoor conditions and at low dose rates

A system with a recombination chamber for outdoor dosimetry in mixed radiation fields is proposed. The chamber works as a passive detector, with polarising electrodes supplied from capacitors permanently connected to the electrodes. Ions, collected on the measuring electrode, charge a measuring capacitor, also permanently connected to the electrode. A special procedure, including recharging of the supplying capacitors, was introduced in order to compensate the side charge caused by changes of ambient temperature and leakage of the electrical charge from the supplying capacitors. Experimental tests indicated that the chamber of REM-2 type or a specially designed KR-20 chamber could also be used at low dose rates. It was possible to measure the ambient dose of a fraction of μGy with accuracy of about 10%, and the H*(10) of about 1 μSv, with accuracy better than 25%, in any field of penetrating radiation, provided the time of charge collection is less than 24 h.     

Detectors with Ir/Au-thermometers for high count rate tests in the CRESST experiment

With simultaneous measurement of the temperature signal and the scintillation light of a CaWO₄ absorber crystal, it is possible to reject the gamma and electron background in the Cryogenic Rare Event Search with Superconducting Thermometers experiment. In order to understand the different events from various particles correctly a neutron calibration experiment and other tests are necessary. Using an existing accelerator facility these tests will be performed above ground. For such an experiment, a detector with good stability at high count rates is necessary. The detectors used in the Gran Sasso Laboratory are equipped with W-thermometers. They show long decay times and need active stabilisation and therefore are not well suitable for experiments with high count rates. We report on developments and first results on detectors based on Ir/Au-thermometers in electrothermal feedback mode.     

Enhanced Spin Tunneling in a Molecular Magnet Mixed with a Superconductor

We report characterization and magnetic studies of mixtures of micrometer-size ribbons of Mn₁₂ acetate and micrometer-size particles of YBaCuO superconductor. Extremely narrow zero-field spin-tunneling resonance has been observed in the mixtures, pointing to the absence of the inhomogeneous dipolar broadening. It is attributed to the screening of the internal magnetic fields in the magnetic particles by Meissner currents flowing between superconducting grains surrounding the particles.     

Homogeneous Solutions of a Skew-Symmetric Problem with Mixed Boundary Conditions for a Piezoceramic Layer

On the basis of a modified scheme of homogeneous solutions significantly simplifying the Lur'e scheme, we construct homogeneous solutions for a piezoceramic layer with mixed boundary conditions imposed on its faces. We consider an electroelastic state skew-symmetric about the median plane of the layer. It is shown that the corresponding homogeneous solutions do not contain biharmonic terms and the components of the conjugate electroelastic field in the layer have the form of Fourier series with respect to the coordinate x ₃.