Bulk Material Layer Research Articles

The condition of existing residential buildings with a sliding support in the foundation in the city of Bishkek

This article is devoted to the analysis of the current state of residential buildings with a sliding support in the foundation, in the city of Bishkek. The residential buildings under consideration were built at different times, according to different designs and different structural and planning schemes with seismic protection systems. As you know, with sliding supports, it is possible to significantly reduce the horizontal loads transmitted to the bearing above-ground structures of the building if it is possible for them to slip relative to the foundation. A detailed analysis and review of these existing residential buildings with a seismic-isolating sliding belt in the foundation using various structural and planning schemes and materials has been performed. The constructed experimental residential buildings with seismic protection systems, according to the results of the work performed, it is recommended to use sources of energy absorbers, consisting of rubbing surfaces of steel, fluoroplastic and a layer of bulk material placed between them.

Method and Apparatus of Measuring Velocity and Sound Attenuation Coefficient in Bulk Materials Based on the Analysis of the Structure of Sound-Insulation Materials on the Basis of Perlite

This paper presents the results of research and describes the apparatus for measuring the acoustic characteristics of bulk materials. Ultrasound, it has passed through a layer of bulk material, is further passes through an air gap. The presence of air gap prevents from measuring tract mechanical contacts, but complicates the measurement technology Studies were conducted on the example of measuring the acoustic characteristics of the widely used perlite-based sound-proofing material.

Thickness Dependence and Enhancement of $H_{{\rm C}1}$ in Epitaxial $\hbox{MgB}_{2}$ Thin Films

Thin film MgB2 is a promising material for technical improvements in superconducting radio frequency (SRF) technology and applications. At present, bulk niobium SRF accelerating cavities suffer from a fundamental upper limit in maximally sustained accelerating gradients; however, a scheme involving multilayered superstructures consisting of superconducting-insulating-superconducting (SIS) layers has been proposed to overcome this fundamental material limit of 50 MV/m. The SIS multilayer paradigm is reliant upon implementing a thin shielding material with a suitably high HC1, which may prevent early field penetration in a bulk material layer and consequently delay the high field breakdown. It has been predicted that for thin superconducting films - thickness less than the London penetration depth ( ~ 120 nm in the case of MgB2) - the lower critical field HC1 can be enhanced with decreasing thickness. Thus, MgB2, with a high TC and relatively low HC1 value, as compared with Nb, is a prime candidate for such SIS structures. Here we present our study on the microstructure, surface morphology, and superconducting properties on a thickness series of MgB2 thin films and correlate the effects of film thickness and surface morphology on HC1.