Comment on "Spatial optical solitons in highly nonlocal media" and related papers

In a recent paper [A. Alberucci, C. Jisha, N. Smyth, and G. Assanto, Phys. Rev. A 91, 013841 (2015)], Alberucci et al. have studied the propagation of bright spatial solitary waves in highly nonlocal media. We find that the main results in that and related papers, concerning soliton shape and dynamics, based on the accessible soliton (AS) approximation, are incorrect; the correct results have already been published by others. These and other inconsistencies in the paper follow from the problems in applying the AS approximation in earlier papers by the group that propagated to the later papers. The accessible soliton theory cannot describe accurately the features and dynamics of solitons in highly nonlocal media.Comment: 2 page

Optimization of Excitation in FDTD Method and Corresponding Source Modeling

Source and excitation modeling in FDTD formulation has a significant impact on the method performance and the required simulation time. Since the abrupt source introduction yields intensive numerical variations in whole computational domain, a generally accepted solution is to slowly introduce the source, using appropriate shaping functions in time. The main goal of the optimization presented in this paper is to find balance between two opposite demands: minimal required computation time and acceptable degradation of simulation performance. Reducing the time necessary for source activation and deactivation is an important issue, especially in design of microwave structures, when the simulation is intensively repeated in the process of device parameter optimization. Here proposed optimized source models are realized and tested within an own developed FDTD simulation environment

Hybrid Optical Switching for Data Center Networks

Current data centers networks rely on electronic switching and point-to-point interconnects.When considering future data center requirements, these solutions will raise issues in terms of flexibility, scalability, performance, and energy consumption. For this reason several optical switched interconnects, which make use of optical switches and wavelength division multiplexing (WDM), have been recently proposed. However, the solutions proposed so far suffer from low flexibility and are not able to provide service differentiation. In this paper we introduce a novel data center network based on hybrid optical switching (HOS). HOS combines optical circuit, burst, and packet switching on the same network. In this way different data center applications can be mapped to the optical transportmechanism that best suits their traffic characteristics. Furthermore, the proposed HOS network achieves high transmission efficiency and reduced energy consumption by using two parallel optical switches. We consider the architectures of both a traditional data center network and the proposed HOS network and present a combined analytical and simulation approach for their performance and energy consumption evaluation. We demonstrate that the proposed HOS data center network achieves high performance and flexibility while considerably reducing the energy consumption of current solutions

Power considerations towards a sustainable pan-european network

Energy savings are observed and quantified in the Pan-European network using transparent optical network technology. The network was dimensioned, using realistic traffic predictions of the optical networking roadmap of the European project BONE

Analysis of Fatigue and Crack Growth in Carbon-Fiber Epoxy Matrix Composite Laminates

A study of high frequency fatigue in carbon-fiber reinforced composites has been undertaken. A comparison has been made between the fatigue behavior of crossply (0/90°) and angleply (±45°) carbon/epoxy unnotched and notched laminates. Additionally, a micromechanical analysis of fracture surfaces performed by scanning electron microscopy was carried out to evaluate the micromechanisms that occurred during fatigue. Experimental observations indicate that fatigue damage consists of a combination of matrix cracks, longitudinal splitting, fiber fracture, and delamination. In order to minimize the effects of residual strain due to temperature rise, a method is proposed for determining real fatigue strength at the level of variable load not lower than the fatigue limit, at which residual strains are minimal.Выполнены высокочастотные усталостные испытания композитных материалов, армированных графитовыми волокнами. Проведен сравнительный анализ усталостного поведения графитоэпоксидных ламинатных материалов с надрезом и без надреза для различных случаев ориентации волокон (0°/90° и ±45°). Кроме того, с применением метода сканирующей электронной микроскопии осуществлен микромеханический анализ поверхностей разрушения с целью обнаружения микромеханизмов разрушения материала. Полученные экспериментальные результаты показали, что усталостное повреждение обусловлено комбинированными эффектами трещинообразования в матрице, продольного расслоения, разрушения волокон и деламинации. Для минимизирования остаточных деформационных эффектов, связанных с повышением температуры, предложен метод определения фактической усталостной прочности как переменного уровня нагрузки не ниже предела усталостной прочности, при котором имеют место минимальные остаточные напряжения.Виконано високочастотні втомні випробування композитних матеріалів, армованих графітовими волокнами. Проведено порівняльний аналіз втомного поведінки графітоепоксідних ламінатних матеріалів з ​​надрізом і без надрізу для різних випадків орієнтації волокон (0 ° / 90 ° і ± 45 °). Крім того, із застосуванням методу скануючої електронної мікроскопії здійснено мікромеханічних аналіз поверхонь руйнування з метою виявлення мікромеханізм руйнування матеріалу. Отримані експериментальні результати показали, що утомлююча пошкодження обумовлено комбінованими ефектами тріщиноутворення в матриці, поздовжнього розшарування, руйнування волокон і деламінаціі. Для минимизирования залишкових деформаційних ефектів, пов'язаних з підвищенням температури, запропонований метод визначення фактичної втомної міцності як змінного рівня навантаження не нижче межі втомної міцності, при якому мають місце мінімальні залишкові напруги

MILOPrOductIOn Of vIabLe Miscanthus gigantheus rhIzOMes at fertILe and degraded sOIL

abstract ArAndjelovic, M., G. drAzic, j. MilovAnovic and S. AlekSic, 2014. Miloproduction of viable Miscanthus gigantheus rhizomes at fertile and degraded soil. Bulg. J. Agric. Sci., 20: 1189-1194 expanding supplies of home grown biomass and facilitation of the development and competitiveness of a supply chain in an sustainable manner, presents a core of government's strategy, for energy development in republic of Serbia. Growing agroenergy corps may be one of the solutions according to analysis that were carried out. one of these corps that was found to be especially amenable due to its potentially high productivity and cultivation on degraded terrain is Miscanthus giganteus. The possibility of producing after mentioned plant for the biomass supply chain, at very low cost is the main aim of this study. due to its sterility Miscanthus giganteus can only by propagated by vegetative division. Potential of production of viable rhizome on terrains with different rate of fertility was followed by method of experiments on the field. 6 parameters that were following growth of the rhizome and planting survival rate were monitored. According to the results, main factors that affect production of viable rhizomes are age of mother plants, and biotic effects of weed vegetation. Size of rhizomes and nursery fertilization shoved significantly smaller effect. This study concentrates on available data regarding the potential directions by which Miscanthus material could achieve maximum production, by high density planting

ELECTRO-ACOUSTIC ANALOGIES BETWEEN THERMOELASTIC COMPONENT OF THE PHOTOACOUSTIC SIGNAL AND LOW-PASS RC FILTER

This paper presents a new approach to the thermal characterization of aluminum, based on the electro-acoustic analogy between the thermoelastic component of the photoacoustic signal and the passive RC low-pass filter. The analogies were used to calculate the characteristic thermoelastic cut-off frequencies of the photoacoustic component and obtain their relationship with the thickness of the aluminum samples. Detailed numerical analysis showed that the required relationship is linear in the log-log scale and can serve as a reference curve for the given material. The results of the numerical analysis were also confirmed experimentally

Acceleration and radiation of ultra-high energy protons in galaxy clusters

Clusters of galaxies are believed to be capable to accelerate protons at accretion shocks to energies exceeding 10^18 eV. At these energies, the losses caused by interactions of cosmic rays with photons of the Cosmic Microwave Background Radiation (CMBR) become effective and determine the maximum energy of protons and the shape of the energy spectrum in the cutoff region. The aim of this work is the study of the formation of the energy spectrum of accelerated protons at accretion shocks of galaxy clusters and of the characteristics of their broad band emission. The proton energy distribution is calculated self-consistently via a time-dependent numerical treatment of the shock acceleration process which takes into account the proton energy losses due to interactions with the CMBR. We calculate the energy distribution of accelerated protons, as well as the flux of broad-band emission produced by secondary electrons and positrons via synchrotron and inverse Compton scattering processes. We find that the downstream and upstream regions contribute almost at the same level to the emission. For the typical parameters characterising galaxy clusters, the synchrotron and IC peaks in the spectral energy distributions appear at comparable flux levels. For an efficient acceleration, the expected emission components in the X-ray and gamma-ray band are close to the detection threshold of current generation instruments, and will be possibly detected with the future generation of detectors.Comment: 9 pages, 13 figures, submitted to Astronomy & Astrophysic