Relativistic electrons from sparks in the laboratory

Discharge experiments were carried out at the Eindhoven University of Technology in 2013. The experimental setup was designed to search for electrons produced in meter-scale sparks using a 1 MV Marx generator. Negative voltage was applied to the high voltage (HV) electrode. Five thin (1 mm) plastic detectors (5 $\rm cm^2$ each) were distributed in various configurations close to the spark gap. Earlier studies have shown (for HV negative) that X-rays are produced when a cloud of streamers is developed 30-60 cm from the negative electrode. This indicates that the electrons producing the X-rays are also accelerated at this location, that could be in the strong electric field from counterstreamers of opposite polarity. Comparing our measurements with modeling results, we find that $\sim$300 keV electrons produced about 30-60 cm from the negative electrode are the most likely source of our measurements. A statistical analysis of expected detection of photon bursts by these fiber detectors indicates that only 20%-45% of the detected bursts could be from soft ($\sim$10 keV) photons, which further supports that the majority of detected bursts are produced by relativistic electrons

Discrete soliton mobility in two-dimensional waveguide arrays with saturable nonlinearity

We address the issue of mobility of localized modes in two-dimensional nonlinear Schr\"odinger lattices with saturable nonlinearity. This describes e.g. discrete spatial solitons in a tight-binding approximation of two-dimensional optical waveguide arrays made from photorefractive crystals. We discuss numerically obtained exact stationary solutions and their stability, focussing on three different solution families with peaks at one, two, and four neighboring sites, respectively. When varying the power, there is a repeated exchange of stability between these three solutions, with symmetry-broken families of connecting intermediate stationary solutions appearing at the bifurcation points. When the nonlinearity parameter is not too large, we observe good mobility, and a well defined Peierls-Nabarro barrier measuring the minimum energy necessary for rendering a stable stationary solution mobile.Comment: 19 pages, 4 figure

INVESTIGATION OF EFFICIENCY OF SMALL POWER STATIONS UNDER CONDITIONS OF UNCERTAINTY

Рассмотрена задача оценки эффективности сооружения автономной электростанции на газе по отношению к централизованному электроснабжению. Построена регрессионная модель зависимости эффективности собственной электрогенерации от внешних и внутренних факторов. Определено влияние отдельных факторов на исследуемую эффективность. Показано наибольшее положительное влияние увеличения цены на отпускаемую энергосистемой электроэнергию на оценку эффективности сооружения собственной малой электростанции. Влияние размера фонда оплаты труда практически незначимо.The problem of estimating the efficiency of the construction of an autonomous power station on gas with respect to a centralized power supply is considered. A regression model is constructed for the dependence of the efficiency of intrinsic electrical generation on external and internal factors. The influence of individual factors on the efficacy was determined. The greatest positive effect of the increase in the price of electricity released by an energy system on the assessment of the efficiency of the construction of one’s own small power plant is shown. The effect of the size of the wage fund is practically insignificant

UNCERTAINTY ANALYSIS IN COMPUTER-AIDED DEVELOPMENT OF ELECTRICAL POWER SYSTEMS

В статье описываются особенности разработки и применения автоматизированных программных модулей в задачах развития электроэнергетических систем (ЭЭС), с учетом фактора неопределенности. В качестве примера демонстрируется, разработанный авторами автоматизированный программный комплекс анализа перспектив развития ЭЭС.The article describes the features of automated software modules application in the context of electrical power systems development (EPS). Also taking into account uncertainty factor

Landscape-Epidemiological Zoning of the Krasnodar Territory and the Republic of Adygea by Tularemia

Objective of the study was epizootic-epidemiological zoning of the area of Krasnodar Territory and the Republic of Adygea by manifestations of tularemia to determine the level of epidemic hazard of each zone.Materials and methods. Utilized were archival data of the Black Sea Plague Control station over the period of 1946–2017 and plague Control Center of the Rospotrebnadzor. With the help of GIS software packages, MapINFO 10.5 and ArcGIS 10.2, the data bases containing the point-like layers of the sites of infection with tularemia (49), isolation of tularemia agent (195), and the layer of landscape-geographical regions in the Krasnodar Territory and the Republic of Adygea were created.Results and discussion. Usage of the geo-information technologies allowed for detailed consideration of tularemia manifestations in different parts of the region. The prospects of applying Arc GIS and MapINFO for geoencoding, processing and creation of geo-information pool of tularemia manifestations over a long period was shown. Vector data of landscapes and sites of epidemics and epizootic manifestations of tularemia on different species of mammals and ticks were generated. The conversion of the database to Microsoft Excel made it possible to make full use of statistical capabilities for epidemiological analysis. The work on epidemiological zoning carried out in the Krasnodar region and the Republic of Adygea starkly illustrated the feasibility of using GIS technologies for those purposes. The results of the analysis allowed for optimization of the mode of epizootiological survey in different parts of the studied region. Advisability of epizootiological inspection and monitoring of the territories with identification of geographical coordinates for epizootic manifestation sites was proved

Self-trapping and stable localized modes in nonlinear photonic crystals

We predict the existence of stable nonlinear localized modes near the band edge of a two-dimensional reduced-symmetry photonic crystal with a Kerr nonlinearity. Employing the technique based on the Green function, we reveal a physical mechanism of the mode stabilization associated with the effective nonlinear dispersion and long-range interaction in the photonic crystals.Comment: 4 pages (RevTex) with 5 figures (EPS

A survey on software defect prediction using deep learning

Defect prediction is one of the key challenges in software development and programming language research for improving software quality and reliability. The problem in this area is to properly identify the defective source code with high accuracy. Developing a fault prediction model is a challenging problem, and many approaches have been proposed throughout history. The recent breakthrough in machine learning technologies, especially the development of deep learning techniques, has led to many problems being solved by these methods. Our survey focuses on the deep learning techniques for defect prediction. We analyse the recent works on the topic, study the methods for automatic learning of the semantic and structural features from the code, discuss the open problems and present the recent trends in the field. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Experimental demonstration of mode structure in ultralong Raman fiber lasers

We present the first experimental demonstration of a resolvable mode structure with spacing c/2nL in the RF spectra of ultralong Raman fiber lasers. The longest ever demonstrated laser cavity (L=84km), RF peaks of ∼100 Hz width and spacing ∼1 kHz have been observed at low intracavity powers. The width of the peaks increases linearly with growing intracavity power and is almost independent of fiber length. © 2007 Optical Society of America

270-km ultralong raman fiber laser

We analyze the physical mechanisms limiting optical fiber resonator length and report on the longest ever laser cavity, reaching 270 km, which shows a clearly resolvable mode structure with a width of ~120??Hz and peak separation of ~380Hz in the radio-frequency spectrum