Phase-locking of multicore fibre laser due to talbot self-reproduction

Abstract

The multicore fibre laser (MCFL), containing an array of single-mode microcores in a circle inside the pump core, is a promising compact laser source. The problem is to synchronize the radiation of microcores with different propagation constants at a given radiation frequency. The theory of phase-locking of an MCFL with an external mirror and an annular waveguide matched to the multicore fibre and having a length some fraction of the Talbot distance is developed. Collective mode selection appears to occur due to spatial filtering at fractional Talbot distances, while the radiation frequency self-adjusts within the spectral gain range to minimize losses. Parallel coupling between microcores is achieved in the limit of a small fill factor. The maximum number of microcores that can be coupled is found. Good agreement is achieved between the theory and previously published experimental results.     

Fabrication of reinforcing nanostructured coatings by electron beam processing

In this work, electron beam welding by electron accelerator of tungsten and chromium carbides and subsequent pulse processing by low-energy electrons has been applied for fabrication of nano- and ultradisperse grain structures penetrated by the system of nanosized pores. It has been demonstrated that, in the region of secondary pulse exposure, the nanohardness and elasticity modulus achieve high values. The wear resistance of the modified structure depends on the value of the specific load in the vicinity of contact with indentor.     

Solid solution decomposition mechanisms in cast and microcrystalline Al-Sc alloys: I. Experimental studies

The structure and the electrical and mechanical properties of Al-Mg-0.22 wt % Sc-0.15 wt % Zr alloys with various magnesium contents (0, 1.5, 4.5 wt %) are experimentally studied during the decomposition of the solid solution of scandium and zirconium in the states after solidification from a melt (cast ingots) and after subsequent multicycle equal-channel angular pressing (microcrystalline structure). The dependences of electrical resistivity ??, microhardness HV, macroelasticity limit ??₀, and yield strength ??_y on the annealing temperature and time are analyzed.     

DNA Comet Giemsa Staining for Conventional Bright-Field Microscopy

This study was undertaken to evaluate the compatibility of Giemsa staining protocol with the comet assay. We showed, for the first time, that DNA comets can be visualized and analyzed using Giemsa staining. We generated DNA damage dose response curves for human peripheral blood lymphocytes exposed to X-ray radiation using the comet assay with either SybrGreen I or Giemsa stain. The dose response curves were fitted by linear regressions (R² > 0.977). The SybrGreen I results showed only ~1.2-fold higher slope coefficient (method sensitivity) compared to the Giemsa results. The unexpectedly high sensitivity of Giemsa staining for the comet assay is due to the Romanowsky-Giemsa effect, the stain photo-stability and the higher resolution of bright-field imaging compared to fluorescence imaging. Our results demonstrate that Giemsa staining can effectively be used for measuring DNA damage by the comet assay. The low cost and availability of Giemsa stain makes this method affordable for any low budget research and will facilitate new applications of the comet assay in biology and medicine.     

Seismic tests of fuel assemblies

Seismic tests of full-scale mockups of fuel assemblies from the VVER-1000 reactor permit the determination of the transfer characteristics between the stimulus (acceleration of the supports) and the response of the fuel assemblies. No resonant responses of the fuel assemblies to seismic loads are observed.     

Device for measuring the length of a bolt of cloth woven on a loom

A measuring device is developed to replace devices used previously in order to more accurately measure the length of a bolt of cloth being woven on a loom. Knowing the actual weft density of the cloth, it is possible to reliably measure the length of the bolt by determining the number of weft threads in it. The measurement error in tests performed on STB-type looms is no greater than ±0.03-0.05 m for bolts up to 50 m in length.     

Tasks and methods of drawing up “The Program of Modernization of the Power Industry of Russia for the Period through the Year 2020”

The structure of tasks, stages, and methods of drawing up “The Program of Modernization of the Power Industry for the Period through the Year 2020” as part of the state program “Energy Efficiency and Development of the Energy Industry” have been determined.     

Determination of the Viscoelastic Characteristics of Polymer Materials on the Example of Polyacrylonitrile Fibre

Methods are developed for determining viscoelastic characteristics with the results of brief laboratory measurements based on both independent processing of families of relaxation and creep curves and on their combined processing using a new mathematical model and the normalized arc tangent of the logarithm of the reduced time as the relaxation function and the creep function. The expediency of using these methods is demonstrated on the example of polyacrylonitrile fibre. The results of the calculations are confirmed by the experimental data.     

Magnetic inspection of fatigue degradation of a high-carbon pearlitic steel

The effect of high-cycle fatigue loading of U10 steel specimens with a fine-lamellar pearlite structure that were a annealed for a short time on the character of variations of the tangential component of the magnetic induction vector of specimens in a residual-magnetization state has been studied. It was found that fatigue loading up to major fatigue-crack formation leads to an increase in the tangential component of the magnetic induction vector and to nonuniformity of the magnetic induction distribution along the length of a specimen. This is due to the spheroidization of cementite plates, which occurs in U10 steel specimens under a fatigue load. Major fatigue-crack formation is accompanied by the appearance of a clearly pronounced peak in the distribution of the tangential component of the magnetic induction vector. The magnetic measurement technique that was used allows us to record both structural changes and cracks that result from the fatigue degradation of high-carbon-pearlitic steel.