bluuebunny/crossref_metadata_2025 huggingface dataset:
µKMS: micro key management system for WSNs
Authors: Aissani Sofiane , Omar Mawloud , Tari Abdelkamel , Bouakkaz Feriel
Published: January 2018

Key management is the basic building block of all the security protocols and is one of the most challenging issues in wireless sensor networks (WSNs). Centralising a trusted key management server is not an appropriate solution in such fully distributed networks. On the other hand, designing a distributed key management system is a challenging task, due to the constrained characteristics of sensor nodes, which are limited in storage, computation, communication, and energy. In the literature, there is a hot research effort on key management purpose for WSNs. The greatest part of the existing solutions focuses mainly on the optimisation of the key number, rekeying frequency and process or the encryption system of the distributed keys. Unfortunately, these systems are implemented as an additional and independent service, involving a considerable overhead. In this study, the authors propose µKMS (micro key management system) for WSNs. µKMS implements a dissimulation scheme, embedding the rekeying process messages on the unexploited coding space of the exchanged ZigBee packets. They have developed simulations, where the obtained results show the relevance of µKMS in terms of communication overhead, storage overhead, and energy consumption.
Procedure optimisation for green synthesis of silver nanoparticles by Taguchi method
Authors: Aghajani Kalaki Zahra , SafaeiJavan Raheleh , Faraji Hossein
Published: January 2018

This study is dealing with optimisation of the green synthesised silver nanoparticles (AgNPs) using the Taguchi design. Orthogonal array of L9 type was used as an experimental design to detect the optimum conditions for synthesis of AgNPs. AgNPs were synthesised using the extract of Mentha longifolia as a reducing agent. In addition to the colour changes, ultraviolet visible spectroscopy was used to attest the appearance of AgNPs. Meanwhile, yielded AgNPs were characterised by FT‐IR, scanning electron microscopy and dynamic light scattering (DLS) technique. UV–visible spectrophotometer showed absorbance peak at 340 nm. DLS analysis showed that the synthesised AgNPs are 21.1 nm in optimum conditions. The optimised condition for the synthesis of AgNPs revealed that silver nitrate concentration was 10 mM, temperature was 60°C, pH was 9 and plant extract concentration was 3%. The results demonstrated that AgNPs can be synthesised by controlling silver nitrate and plant extract concentration, pH and temperature. The minimum diameter predicted by statistical model was 35 nm while the obtained diameter was 21.1 nm which is very close to the experimental designed measure. This indicates that the statistical predicated proposed by Taguchi was correct.
Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets
Authors: Turbet Martin , Bolmont Emeline , Leconte Jeremy , Forget François , Selsis Franck , Tobie Gabriel , Caldas Anthony , Naar Joseph , Gillon Michaël
Published: January 2018

TRAPPIST-1 planets are invaluable for the study of comparative planetary science outside our solar system and possibly habitability. Both transit timing variations (TTV) of the planets and the compact, resonant architecture of the system suggest that TRAPPIST-1 planets could be endowed with various volatiles today. First, we derived from N-body simulations possible planetary evolution scenarios, and show that all the planets are likely in synchronous rotation. We then used a versatile 3D global climate model (GCM) to explore the possible climates of cool planets around cool stars, with a focus on the TRAPPIST-1 system. We investigated the conditions required for cool planets to prevent possible volatile species to be lost permanently by surface condensation, irreversible burying or photochemical destruction. We also explored the resilience of the same volatiles (when in condensed phase) to a runaway greenhouse process. We find that background atmospheres made of N2, CO, or O2are rather resistant to atmospheric collapse. However, even if TRAPPIST-1 planets were able to sustain a thick background atmosphere by surviving early X/EUV radiation and stellar wind atmospheric erosion, it is difficult for them to accumulate significant greenhouse gases like CO2, CH4, or NH3. CO2can easily condense on the permanent nightside, forming CO2ice glaciers that would flow toward the substellar region. A complete CO2ice surface cover is theoretically possible on TRAPPIST-1g and h only, but CO2ices should be gravitationally unstable and get buried beneath the water ice shell in geologically short timescales. Given TRAPPIST-1 planets large EUV irradiation (at least ~103 × Titan’s flux), CH4and NH3are photodissociated rapidly and are thus hard to accumulate in the atmosphere. Photochemical hazes could then sedimentate and form a surface layer of tholins that would progressively thicken over the age of the TRAPPIST-1 system. Regarding habitability, we confirm that few bars of CO2would suffice to warm the surface of TRAPPIST-1f and g above the melting point of water. We also show that TRAPPIST-1e is a remarkable candidate for surface habitability. If the planet is today synchronous and abundant in water, then it should very likely sustain surface liquid water at least in the substellar region, whatever the atmosphere considered.
Gamma-ray emission from internal shocks in novae
Authors: Martin P. , Dubus G. , Jean P. , Tatischeff V. , Dosne C.
Published: January 2018

Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission.

Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst.

Methods. We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr.

Results. The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to ~100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10−5–10−4 M⊙ expands in a homologous way with a maximum velocity of 1000–2000 km s−1, followed within a day by a wind with a velocity <2000 km s−1 and a mass-loss rate of 10−4–10−3 M⊙ yr−1 declining over a time scale of a few days. Because of the large uncertainties in the measurements, many parameters of the problem are degenerate and/or poorly constrained except for the wind velocity, the relatively low values of which result in the majority of best-fit models having gamma-ray spectra with a high-energy turnover below ~10 GeV. Our typical model is able to account for the main features in the observations of the recent gamma-ray nova ASASSN-16ma.

Conclusions. The internal shock model can account for the gamma-ray emission of the novae detected by Fermi LAT. Gamma-ray observations hold potential for probing the mechanism of mass ejection in novae, but should be combined to diagnostics of the thermal emission at lower energies to be more constraining.
Flare particle acceleration in the interaction of twisted coronal flux ropes
Authors: Threlfall J. , Hood A. W. , Browning P. K.
Published: January 2018

Aim. The aim of this work is to investigate and characterise non-thermal particle behaviour in a three-dimensional (3D) magnetohydrodynamical (MHD) model of unstable multi-threaded flaring coronal loops.

Methods. We have used a numerical scheme which solves the relativistic guiding centre approximation to study the motion of electrons and protons. The scheme uses snapshots from high resolution numerical MHD simulations of coronal loops containing two threads, where a single thread becomes unstable and (in one case) destabilises and merges with an additional thread.

Results. The particle responses to the reconnection and fragmentation in MHD simulations of two loop threads are examined in detail. We illustrate the role played by uniform background resistivity and distinguish this from the role of anomalous resistivity using orbits in an MHD simulation where only one thread becomes unstable without destabilising further loop threads. We examine the (scalable) orbit energy gains and final positions recovered at different stages of a second MHD simulation wherein a secondary loop thread is destabilised by (and merges with) the first thread. We compare these results with other theoretical particle acceleration models in the context of observed energetic particle populations during solar flares.
Convective blueshifts in the solar atmosphere
Authors: Löhner-Böttcher J. , Schmidt W. , Stief F. , Steinmetz T. , Holzwarth R.
Published: January 2018

Context. The solar convection manifests as granulation and intergranulation at the solar surface. In the photosphere, convective motions induce differential Doppler shifts to spectral lines. The observed convective blueshift varies across the solar disk.

Aim. We focus on the impact of solar convection on the atmosphere and aim to resolve its velocity stratification in the photosphere.

Methods. We performed high-resolution spectroscopic observations of the solar spectrum in the 6302 Å range with the Laser Absolute Reference Spectrograph at the Vacuum Tower Telescope. A laser frequency comb enabled the calibration of the spectra to an absolute wavelength scale with an accuracy of 1 m s−1. We systematically scanned the quiet Sun from the disk center to the limb at ten selected heliocentric positions. The analysis included 99 time sequences of up to 20 min in length. By means of ephemeris and reference corrections, we translated wavelength shifts into absolute line-of-sight velocities. A bisector analysis on the line profiles yielded the shapes and convective shifts of seven photospheric lines.

Results. At the disk center, the bisector profiles of the iron lines feature a pronounced C-shape with maximum convective blueshifts of up to −450 m s−1 in the spectral line wings. Toward the solar limb, the bisectors change into a “\”-shape with a saturation in the line core at a redshift of +100 m s−1. The center-to-limb variation of the line core velocities shows a slight increase in blueshift when departing the disk center for larger heliocentric angles. This increase in blueshift is more pronounced for the magnetically less active meridian than for the equator. Toward the solar limb, the blueshift decreases and can turn into a redshift. In general, weaker lines exhibit stronger blueshifts.

Conclusions. Best spectroscopic measurements enabled the accurate determination of absolute convective shifts in the solar photosphere. We convolved the results to lower spectral resolution to permit a comparison with observations from other instruments.
The STAGGER-grid: A grid of 3D stellar atmosphere models
Authors: Chiavassa A. , Casagrande L. , Collet R. , Magic Z. , Bigot L. , Thévenin F. , Asplund M.
Published: January 2018

Context. The surface structures and dynamics of cool stars are characterised by the presence of convective motions and turbulent flows which shape the emergent spectrum.

Aims. We used realistic three-dimensional (3D) radiative hydrodynamical simulations from the STAGGER-grid to calculate synthetic spectra with the radiative transfer code OPTIM3D for stars with different stellar parameters to predict photometric colours and convective velocity shifts.

Methods. We calculated spectra from 1000 to 200 000 Å with a constant resolving power of λ∕Δλ = 20 000 and from 8470 and 8710 Å (Gaia Radial Velocity Spectrometer – RVS – spectral range) with a constant resolving power of λ∕Δλ = 300 000.

Results. We used synthetic spectra to compute theoretical colours in the Johnson-Cousins UBV (RI)C, SDSS, 2MASS, Gaia, SkyMapper, Strömgren systems, and HST-WFC3. Our synthetic magnitudes are compared with those obtained using 1D hydrostatic models. We showed that 1D versus 3D differences are limited to a small percent except for the narrow filters that span the optical and UV region of the spectrum. In addition, we derived the effect of the convective velocity fields on selected Fe I lines. We found the overall convective shift for 3D simulations with respect to the reference 1D hydrostatic models, revealing line shifts of between −0.235 and +0.361 km s−1. We showed a net correlation of the convective shifts with the effective temperature: lower effective temperatures denote redshifts and higher effective temperatures denote blueshifts. We conclude that the extraction of accurate radial velocities from RVS spectra need an appropriate wavelength correction from convection shifts.

Conclusions. The use of realistic 3D hydrodynamical stellar atmosphere simulations has a small but significant impact on the predicted photometry compared with classical 1D hydrostatic models for late-type stars. We make all the spectra publicly available for the community through the POLLUX database.
Advanced Channeling Technologies in Plasma and Laser Fields
Authors: Dabagov Sultan B.
Published: January 2018

Channeling is the phenomenon well known in the world mostly related to the motion of the beams of charged particles in aligned crystals. However, recent studies have shown the feasibility of channeling phenomenology application for description of other various mechanisms of interaction of charged as well as neutral particle beams in solids, plasmas and electromagnetic fields covering the research fields from crystal based undulators, collimators and accelerators to capillary based X-ray and neutron optical elements. This brief review is devoted to the status of channeling-based researches at different centers within international and national collaborations. Present and future possible developments in channeling tools applied to electron interactions in strong plasma and laser fields will be analyzed.
Why do Electrons with “Anomalous Energies” appear in High-Pressure Gas Discharges?
Authors: Kozyrev Andrey , Kozhevnikov Vasily , Semeniuk Natalia
Published: January 2018

Experimental studies connected with runaway electron beams generation convincingly shows the existence of electrons with energies above the maximum voltage applied to the discharge gap. Such electrons are also known as electrons with “anomalous energies”. We explain the presence of runaway electrons having so-called “anomalous energies” according to physical kinetics principles, namely, we describe the total ensemble of electrons with the distribution function. Its evolution obeys Boltzmann kinetic equation. The dynamics of self-consistent electromagnetic field is taken into the account by adding complete Maxwell’s equation set to the resulting system of equations. The electrodynamic mechanism of the interaction of electrons with a travelling-wave electric field is analyzed in details. It is responsible for the appearance of electrons with high energies in real discharges.
Development and optimization of a “water window” microscope based on a gas-puff target laser-produced plasma source
Authors: Torrisi Alfio , Wachulak Przemyslaw , Bartnik Andrzej , Węgrzyński Łukasz , Fok Tomasz , Fiedorowicz Henryk
Published: January 2018

A laser-plasma double stream gas-puff target source coupled with Fresnel zone plate (FZP) optics, operating at He-like nitrogen spectral line λ=2.88nm, is capable of acquire complementary information in respect to optical and electron microscopy, allowing to obtain high resolution imaging, compared to the traditional visible light microscopes, with an exposition time of a few seconds. The compact size and versatility of the microscope offers the possibility to perform imaging experiments in the university laboratories, previously restricted to large-scale photon facilities. Source and microscope optimization, and examples of applications will be presented and discussed.
Strong electromagnetic pulses generated in laser-matter interactions with 10TW-class fs laser
Authors: Rączka Piotr , Rosiński Marcin , Zaraś-Szydłowska Agnieszka , Wołowski Jerzy , Badziak Jan
Published: January 2018

The results of an experiment on the generation of electromagnetic pulses (EMP) in the interaction of 10TW fs pulses with thick (mm scale) and thin foil (μm scale) targets are described. Such pulses, with frequencies in the GHz range, may pose a threat to safe and reliable operation of high-power, high-intensity laser facilities. The main point of the experiment is to investigate the fine temporal structure of such pulses using an oscilloscope capable of measurements at very high sampling rate. It is found that the amazing reproducibility of such pulses is confirmed at this high sampling rate. Furthermore, the differences between the EMP signals generated from thick and thin foil targets are clearly seen, which indicates that besides electric polarization of the target and the target neutralization current there may be other factors essential for the EMP emission.
Raman investigation of laser-induced structural defects of graphite oxide films
Authors: Romano Valentino , Torrisi Lorenzo , Cutroneo Mariapompea , Havranek Vladimir , D’Angelo Giovanna
Published: January 2018

Since the beginning of intensive studies on graphene and graphitic materials, Raman spectroscopy has always been used as a characterisation technique. This is due to two main reasons: the non-destructive nature of this experimental technique and its ability to distinguish between the plethora of existing carbon materials. One of the most challenging research activities concerns the production of graphene microcircuits. To address this issue, a possible strategy is to directly reduce and pattern graphite oxide (GO) film by laser irradiation. The objective of this study is to evaluate the laser irradiation-induced structural changes on thin GO films by using Micro-Raman spectroscopy. We used as a source a Nd:YAG laser (1064 nm) and different laser fluences: 15 J/cm2, 7.5 J/cm2 and 5 J/cm2. We have analyzed the modifications of the main Raman contributions of these graphitic materials: the D band (defect induced band), the G band (band due to sp2 hybridized carbon atoms) and the 2D band (D band overtone). In particular, we found out that our figure of merit (FOM) parameters, i.e. the intensity ratio ID/IG (for the D band and G band) and I2D/IG (for the 2D band and G band), change with the laser fluences, revealing a different effect induced by the laser irradiation. The best results are found in the sample irradiated with 5 J/cm2, suggesting that higher fluences do not lead to better results.
Remarks on non-singular black holes
Authors: Frolov Valeri P.
Published: January 2018

We briefly discuss non-singular black hole models, with the main focus on the properties of non-singular evaporating black holes. Such black holes possess an apparent horizon, however the event horizon may be absent. In such a case, the information from the black hole interior may reach the external observer after the complete evaporation of the black hole. This model might be used for the resolution of the information loss puzzle. However, as we demonstrate, in a general case the quantum radiation emitted from the black hole interior, calculated in the given black hole background, is very large. This outburst of the radiation is exponentially large for models with the redshift function α = 1. We show that it can be suppressed by including a non-trivial redshift function. However, even this suppression is not enough to guarantee self-consistency of the model. This problem is a manifestation of a general problem, known as the "mass inflation". We briefly comment on possible ways to overcome this problem in the models of non-singular evaporating black holes.
Schwinger mechanism in electromagnetic field in de Sitter spacetime
Authors: Bavarsad Ehsan , Pyo Kim Sang , Stahl Clément , Xue She-Sheng
Published: January 2018

We investigate Schwinger scalar pair production in a constant electromagnetic field in de Sitter (dS) spacetime. We obtain the pair production rate, which agrees with the Hawking radiation in the limit of zero electric field in dS. The result describes how a cosmic magnetic field affects the pair production rate. In addition, using a numerical method we study the effect of the magnetic field on the induced current. We find that in the strong electromagnetic field the current has a linear response to the electric and magnetic fields, while in the infrared regime, is inversely proportional to the electric field and leads to infrared hyperconductivity.
Holographic Entanglement Entropy, SUSY & Calibrations
Authors: Colgáin Eoin Ó
Published: January 2018

Holographic calculations of entanglement entropy boil down to identifying minimal surfaces in curved spacetimes. This generically entails solving second-order equations. For higher-dimensional AdS geometries, we demonstrate that supersymmetry and calibrations reduce the problem to first-order equations. We note that minimal surfaces corresponding to disks preserve supersymmetry, whereas strips do not.
Evolution of an electron-positron plasma produced by induced gravitational collapse in binary-driven hypernovae
Authors: Melon Fuksman J. D. , Becerra L. , L. Bianco C. , Karlica M. , Kovacevic M. , Moradi R. , Muccino M. , B. Pisani G. , Primorac D. , A. Rueda J. , Ruffini R. , Vereshchagin G. V. , Wang Y.
Published: January 2018

The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN). This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.
On the effective Stefan-Boltzmann law and the thermodynamic origin of the initial radiation density in warm inflation
Authors: Gim Yongwan , Kim Wontae
Published: January 2018

In this presentation, we are going to explain the thermodynamic origin of warm inflation scenarios by using the effetive Stefan-Boltzmann law. In the warm inflation scenarios, radiation always exists to avoid the graceful exit problem, for which the radiation energy density should be assumed to be finite at the starting point of the warm inflation. To find out the origin of the non-vanishing initial radiation energy density, we derive an effective Stefan-Boltzmann law by considering the non-vanishing trace of the total energy-momentum tensors. The effective Stefan-Boltzmann law successfully shows where the initial radiation energy density is thermodynamically originated from. And by using the above effective Stefan-Boltzmann law, we also study the cosmological scalar perturbation, and obtain the sufficient radiation energy density in order for GUT baryogenesis at the end of inflation. This proceeding is based on Ref. [1]
On Gauge Invariant Cosmological Perturbations in UV-modified Hořava Gravity: A Brief Introduction
Authors: Park Mu-In
Published: January 2018

We revisit gauge invariant cosmological perturbations in UV-modified, z = 3 Hořava gravity with one scalar matter field, which has been proposed as a renormalizable gravity theory without the ghost problem in four dimensions. We confirm that there is no extra graviton modes and general relativity is recovered in IR, which achieves the consistency of the model. From the UV-modification terms which break the detailed balance condition in UV, we obtain scale-invariant power spectrums for non-inflationary backgrounds, like the power-law expansions, without knowing the details of early expansion history of Universe. This could provide a new framework for the Big Bang cosmology.
Accelerated cosmological expansion without tension in the Hubble parameter
Authors: van Putten Maurice H.P.M.
Published: January 2018

The H0-tension problem poses a confrontation of dark energy driving latetime cosmological expansion measured by the Hubble parameter H(z) over an extended range of redshifts z. Distinct values H0 ≃ 73 km s–1 Mpcs–1 and H0 ≃ 68 km s–1 Mpcs–1 obtain from surveys of the Local Universe and, respectively, ΛCBM analysis of the CMB. These are representative of accelerated expansion with H′(0) ≃ 0 by [see formula in PDF] and, respectively, H′(0) > 0 in ΛCDM, where [see formula in PDF] is a fundamental frequency of the cosmological horizon in a Friedmann-Robertson-Walker
universe with deceleration parameter q(z) = -1 + (1+z)H–1 H′(z). Explicit solution H(z) = H0 [see formula in PDF] and, respectively, H(z) = H0[see formula in PDF] are here compared with recent data on H(z) over 0 ≲ z ≲ 2.The first is found to be free of tension with H0 from local surveys, while the latter is disfavored at 2:7σ A further confrontation obtains in galaxy dynamics by a finite sensitivity of inertia to background cosmology in weak gravity, putting an upper bound of m ≲ 10–30 eV on the mass of dark matter. A C0 onset to weak gravity at the de Sitter scale of acceleration adS = cH(z), where c denotes the velocity of light, can be seen in galaxy
rotation curves covering 0 ≲ z ≲ 2 Weak gravity in galaxy dynamics hereby provides a proxy for cosmological evolution.
Quasilocal angular momentum of gravitational fields in (2+2) formalism
Authors: Oh Seung Hun , Yoon Jong Hyuk
Published: January 2018

Recently the Poisson algebra of a quasilocal angular momentum of gravitational fields L(ξ) in (2+2) formalism of Einstein’s theory was studied in detail [1]. In this paper, we will briefly review the definition of L(ξ) and its remarkable properties. Especially, it will be discussed that L(ξ) satisfies the Poisson algebra {L(ξ); L(η){P.B. = L([ξ, η]L), up to a constant normalizing factor, and this algebra reduces to the standard SO(3) algebra at null infinity. It will be also argued that our angular momentum is a quasilocal generalization of A. Rizzi’s geometric definition.
Planning pesticides usage for herbal and animal pests based on intelligent classification system with image processing and neural networks
Authors: Dimililer Kamil , Kirsal Ever Yoney
Published: January 2018

Pests are divided into two as herbal and animal pests in agriculture, and detection and use of minimum pesticides are quite challenging task. Last three decades, researchers have been improving their studies on these manners. Therefore, effective, efficient, and as well as intelligent systems are designed and modelled. In this paper, an intelligent classification system is designed for detecting pests as herbal or animal to use of proper pesticides accordingly. The designed system suggests two main stages. Firstly, images are processed using different image processing techniques that images have specific distinguishing geometric patterns. The second stage is neural network phase for classification. A backpropagation neural network is used for training and testing with processed images. System is tested, and experiment results show efficiency and effective classification rate. Autonomy and time efficiency within the pesticide usage are also discussed.
Integrated artificial intelligence algorithm for skin detection
Authors: Bush Idoko John , Abiyev Rahib , Sallam Ma’aitah Mohammad Khaleel , Altıparmak Hamit
Published: January 2018

The detection of skin colour has been a useful and renowned technique due to its wide range of application in both analyses based on diagnostic and human computer interactions. Various problems could be solved by simply providing an appropriate method for pixel-like skin parts. Presented in this study is a colour segmentation algorithm that works directly in RGB colour space without converting the colour space. Genfis function as used in this study formed the Sugeno fuzzy network and utilizing Fuzzy C-Mean (FCM) clustering rule, clustered the data and for each cluster/class a rule is generated. Finally, corresponding output from data mapping of pseudo-polynomial is obtained from input dataset to the adaptive neuro fuzzy inference system (ANFIS).
Analysis of docking algorithms by HPC methods generated in bioinformatics studies
Authors: Stoilov Anton , Yurukov Borislav , Milanov Peter
Published: January 2018

High-performance computing (HPC) is an important domain of the computer science field. For more than 30 years, it has allowed finding solutions to problems and enhanced progress in many scientific areas such as bioinformatics and drug design. The binding of small molecule ligands to large protein targets is central to numerous biological processes. The accurate prediction of the binding modes between the ligand and protein (the docking problem) is of fundamental importance in modern structure-based drug design. The interactions between the receptor and ligand are quantum mechanical in nature, but due to the complexity of biological systems, quantum theory cannot be applied directly. Consequently, most methods used in docking and computational drug discovery are more empirical in nature and usually lack generality.
Model Residual Stress by Finite Element Method
Authors: Garleanu Delia , Borda Claudia , Garleanu Gabriel , Popovici Victor
Published: January 2018

This paper presents an original model developed by finite element method to simulate the behavior of the material to the method “Blind Hole Drilling”, to determine the residual stress. Modeling of this method is possible through the use of the “Birth and Death” which have some elements of ANSYS library. After obtaining the analysis of movements, appropriate loads, a node located from the center hole at a radius calculated. In this way it is easier to estimate the stresses and deformations of a piece. Several measurements are made and based on this model is given in ANSYS. In this way we can have a map of tensions and deformations in a material
Calculation and Experimental Validation of Pressure and Temperature Effects on COG-Air Fuel Mixtures
Authors: Jan Skrinsky
Published: January 2018

COG have been widely used together with blast furnace gas and blast furnace oxygen gas in the steel industry in Moravian-Silesian region of Czech Republic. COG is a flammable and explosive substance. Most explosion characteristics published so far are valid for pure compounds and limited experimental conditions, mostly ambient. There have been no explosion characteristic exists for COG-air mixtures which cover industrial conditions up to 423 K. Experimental tests have been carried out in a 20-L closed explosion chamber adopted for the explosion tests. The element potential approach in the thermochemical equilibrium calculations applied in the Chemkin subroutine has been used for explosion pressure calculations. Different explosion characteristics have been reported in a range from 298 K up to 423 K and from 0.5 bar(a) up to 1.0 bar(a).
Potential of multispectral imaging technology for assessment coniferous forests bitten by a bark beetle in Central Bulgaria
Authors: Stoyanova Marina , Kandilarov Alexander , Koutev Vesselin , Nitcheva Olga , Dobreva Polya
Published: January 2018

Much of the coniferous forest in Bulgaria is struck by Ips typographus, Ips acuminatus and Ips sexdentatus beetles. The multispectral camera test near the town of Kalofer, Bulgaria in August 2017, showed the good capabilities of remote-piloted aircraft for observation and mapping of large areas in highly intersected areas. The collected data from the multispectral camera allowed producing maps with different indices of the observed vegetation. Beetles damaged stains were identified and outlining the areas of intervention and their sizing is possible by forestry specialists. The NDVI index in the range of 0.7 to 0.95 characterizes green tree vegetation. Affected forest subjected to stress has lower NDVI index values - 0.65.The NDVI index of damaged areas range from 0.45-0.5. Identifying affected forest areas is the first important step to solve the problem. Taking pictures of drones and multispectral camera can be of great help, and the test conducted clearly demonstrates it. Preventive actions can happen much earlier before trees are completely destroyed and the problem is clearly visible with the naked eye. In view of the rapid spread and the complete destruction of some conifers, immediate action is needed to cut out and remove the diseased and infected trees in order to break the development cycle and prevent subsequent contamination of adjacent plots
Study of the mechanical properties of Ti-and Cr-based multicomponent hard coatings
Authors: Cholakova Tetiana , Chitanov Vasilliy , Kolaklieva Lilyana , Kakanakov Roumen , Balashev Konstantin , Ranguelov Bogdan , Rupetchov Velko , Mishev Georgi
Published: January 2018

TiCrAlN and CrTiAlN multicomponent coatings have been developed using closed-field unbalanced magnetron sputtering technique (CFUBMS) in a gas mixture of Ar + N2. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). An investigation into the effect of the CFUBMS process parameters on the properties of the coatings was undertaken. The main coatings parameters such as thickness, surface morphology, nanohardness, strength of adhesion and wear resistance were studied by means of ball-cratering method, atomic force microscopy, scanning electron microscopy, scratch tests and nanoindentation measurements. The study revealed strong dependency of the mechanical properties on the nitrogen flow rate. Analysis of the experimental results showed that Cr-based multicomponent coatings possess better mechanical properties than Ti-based coatings at a nitrogen flow rate of 21 sccm: higher value of hardness (≤ 31GPa) and higher scratch resistance (> 30 N).
Thermoacoustic waves in pulsed Pirani sensor MEMS. Numerical Investigation
Authors: Gospodinov Peter , Dankov Dobri , Roussinov Vladimir , Mironova Mirona
Published: January 2018

The transient heat transfer process is studied in rarefied gas confined between two stationary concentric cylinders. The inner cylinder (filament) is subjected to a periodically heating-cooling cycle. The energy transfer is modeled with continuous model based on Navier-Sockes Fourier equations of motion and energy transfer and with a statistical DSMC model. Numerical results for the temperature, thermodynamic pressure and pressure difference between thermodynamic pressure and radial stress tensor component are obtained for different circular frequencies of heating cooling cycle of filament and for different filament radii. The pressure variation at the end of any local heating stage of heating-cooling cycle is close to the value of equilibrium thermodynamic pressure. The results are applicable in designing the pulsed Pirani sensors.
Magnetohydrodynamic calculation of the temperature and wind velocity profile of the solar transition region. Preliminary results.
Authors: Mishonov Todor M. , Varonov Albert M. , Zahariev Nedeltcho I. , Topchiyska Rositsa V. , Lazov Boian V. , Mladenov Stefan B.
Published: January 2018

The sharp almost step like increase the temperature in the transition region (TR) between chromosphere and solar corona is well-known from decades; for first time we are giving a detailed magnetohydrodynamic (MHD) calculation of the height dependence of the temperature. The width of the transition region is evaluated by maximal value of the logarithmic derivative of the temperature. At fixed heating, only MHD can give such a narrow width and in such sense, even the qualitative agreement with the observational data, gives the final verdict what the heating mechanism of the solar corona is. Static profiles of the temperature and wind velocity are calculated for static frequency dependent spectral density of the incoming MHD waves; no time dependent computer simulations. At fixed spectral density of MHD waves, the MHD calculation predicts height dependence of the non-thermal broadening of spectral lines and its angular dependence. For illustration is used one dimensional approximation of completely ionized hydrogen plasma in weak magnetic field, but it is considered that the width of the TR is weakly dependent with respect of further elaboration. The analyzed MHD calculation is a numerical confirmation of the qualitative concept of self-induced opacity of the plasma with respect to MHD waves. The plasma viscosity strongly increases with the temperature. Heated by MHD waves, plasma increases the wave absorption and this positive feedback leads to further heating. The static temperature profile is a result of a self-consistent calculation of propagation of MHD wave through the static background of wind and temperature profile. The numerical method allows consideration of incoming MHD waves with an arbitrary spectral density. Further elaboration of the method are briefly discussed: influence of second viscosity in the chromospheric part of the TR, influence of the magnetic field on the coronal side of the TR and investigation of such type effects on the width of the TR.
Efficient control of mechatronic systems in dynamic motion tasks
Authors: Despotova Desislava , Kiriazov Petko , Karastanev Stefan
Published: January 2018

Robots and powered exoskeletons have often complex and non-linear dynamics due to friction, elasticity, and changing load. The proposed study addresses various-type robots that have to perform dynamic point-to-point motion tasks (PTPMT). The performance demands are for faster motion, higher positioning accuracy, and lower energy consumption. With given motion task, it is of primary importance to study the structure and controllability of the corresponding controlled system. The following natural decentralized controllability condition is assumed: the signs of any control input and the corresponding output (the acceleration) are the same, at least when the control input is at its maximum absolute value. Then we find explicit necessary and sufficient conditions on the control transfer matrix that can guarantee robust controllability in the face of arbitrary, but bounded disturbances. Further on, we propose a generic optimisation approach for control learning synthesis of various type robotic systems in PTPMT. Our procedure for iterative learning control (LC) has the following main steps: (1) choose a set of appropriate test control functions; (2) define the most relevant input-output pairs; and (3) solve shooting equations and perform control parameter optimisation. We will give several examples to explain our controllability and optimisation concepts.
Magnetic flux distribution in a ferromagnetic material magnetized by U-shaped electromagnets of different geometric dimensions types
Authors: Povolotskaya Anna , Gorkunov Eduard , Nosov Pavel , Zadvorkin Sergey
Published: January 2018

A model experiment has been carried out on studying the type of changes in the magnetic induction in a homogeneous isotropic sample that is locally magnetized with attached U-type electromagnets of different geometrical dimensions. The study was aimed at finding out magnetic flux distribution at different locations within the sample and determining the effect that the geometry of attached electromagnets has on this distribution.
A method of laser ultrasound tomography for solid surfaces mapping
Authors: Zarubin Vasily , Bychkov Anton , Karabutov Alexander , Simonova Varvara , Cherepetskaya Elena
Published: January 2018

Surface control is an important problem for production inspection in industry. Traditionally it is solved using mechanical and optical profilometry, providing high spatial resolution. However, such methods are inappropriate for bodies immersed in opaque liquids and require preliminary preparation of samples. Current work focuses on an application of a method of laser ultrasound tomography to mapping of solid surfaces. The suggested approach combines high acoustical resolution, high performance and allows profilometry of contaminated and immersed samples. An automated prototype for real-time surface profile measurements is constructed and tested on several bodies of revolution. Linear approximation of a cylinder profile obtained by the prototype shows maximum approximation inconsistency of 15μm. The results are verified by those obtained by the conventional x-ray method.
Critical defect size assessment in pipelines on a nuclear power plant
Authors: Dimova Galya , Yurukov Vladimir , Djivdjanov Kiril
Published: January 2018

In many energy industry structures, pipeline systems are subject to the impact of mechanical forces, moments of forces and fluid flows of high pressure and temperature. These load factors cause defects in the pipeline metal. As the years of operation increase, defects may occur and grow, which may lead to the destruction of pipeline walls. Special measures have been planned and implemented to ensure the safe operation of high-energy facilities. This study focused on pipelines and nozzles of nuclear power plant equipment with bimetal welded joints on which the size of critical defects was assessed. The base of assessment covers material properties, temperature and stress fields, fracture mechanics calculations. This study involves developing of finite element models and implementing simulations on them in order to obtain temperature fields and determine the stress-strain state of the component.
Ostéotomie de Le Fort 1 : gérer les tissus mous pour contrôler les modifications du nez
Authors: Hernández-Alfaro Federico , Paredes de Sousa Gil Ariane , Haas Junior Orion Luiz , Masià-Gridilla Jorge , Valls-Ontañón Adaia , Guijarro-Martinez Raquel
Published: January 2018

Introduction : Dans le cadre d'une chirurgie de Le Fort 1, il est important d'anticiper les effets indésirables qui peuvent se produire dans la région naso-labiale. Des facteurs peropératoires tels que l'étendue de la dissection chirurgicale, le type de fermeture et de reconstruction des tissus mous péri-nasaux semblent influencer la réponse des téguments. Ces dernières années, plusieurs techniques ont été proposées pour tenter de contrôler ces changements. Matériels et méthodes : Les auteurs présentent ici une alternative peu invasive. Il s'agit d'une technique chirurgicale permettant de contrôler à la fois l'élargissement de la distance qui sépare les ailes du nez et le raccourcissement des lèvres.
Une orthodontie contemporaine fondée sur l'harmonie esthétique et sur la biomécanique. Un entretien avec Ravindra Nanda
Authors: Nanda Ravindra , Amat Philippe
Published: January 2018

Le Pr Ravindra Nanda a obtenu une licence et une maîtrise en dentisterie et en orthodontie duKing George's Medical College, Lucknow University. En 1967, il a intégré l'Université Catholique de Nimègue, aux Pays-Bas, où il a obtenu un doctorat en philosophie en 1969. Il a rejoint la nouvelle école dentaire de Loyola à Chicago en 1970, après avoir occupé le poste de Professeur assistant en orthodontie dans le service dirigé par Frans van der Linden. En 1972, il fut promu au Département d'Orthodontie de l'Université du Connecticut à Farmington, CT, et y reçu son certificat en orthodontie sous la direction de Charles Burstone. Professeur adjoint, puis professeur titulaire à partir de 1979, il a assumé le poste de Chef du Département d'Orthodontie à partir de 1992 et a été promu pour diriger le Département des Sciences Craniofaciales en 2004, dont les divisions de chirurgie orale et maxillo-faciale, de dentisterie pédiatrique, de l'enseignement supérieur en dentisterie générale et en orthodontie.

Il est membre et ancien président de la composante Atlantique Nord de laEdward H. Angle Society of Orthodontists. Il occupe actuellement la fonction de rédacteur en chef deProgress in Orthodontics, de rédacteur associé duJournal of Clinical Orthodonticset est membre du comité éditorial de neuf revues d'orthodontie nationales et internationales. Il est membre de l'Association dentaire américaine, de l'Association dentaire de l'État du Connecticut, de laHartford Dental Society, de l'Association américaine des orthodontistes, de la Société européenne d'orthodontie, de l'Association internationale de recherche dentaire et duCollege of Diplomates of American Board of Orthodontists.

Il a rédigé et publié sept manuels et plus de 200 articles dans des revues à comité de lecture. Il a donné des conférences magistrales dans plus de 40 pays et a reçu de nombreux prix et honneurs pour ses contributions en dentisterie et en orthodontie, aux États-Unis et de la part d'organisations internationales d'orthodontie. Il est membre d'honneur desJordan Orthodontic Society,Czech Orthodontic Society,Taiwanese Orthodontic Society,Central American Orthodontics Societyet membre d'honneur à vie de l'Indian Orthodontic Society.

Ravindra Nanda a été honoré duLife Time Achievement Award(University of Connecticut Foundation), et il estSenior Research Fellow(Japan Promotion for Science, Sendai, Japan − Tohoku University). Il a prononcé de nombreuses conférences d'honneur : laJohn Taylor Lecture, lors de la réunion annuelle del'Australian Society of Orthodontics Foundation, laSheldon Friel Memorial Lecturelors de la réunion annuelle del'European Orthodontic Society, laGordon Kirkness Memorial Lecturelors de la réunion annuelle de l'Australian Society of Orthodontics, laJohn Mershon Memorial Lecture, Boston, Massachusetts lors de la réunion annuelle de l'American Association of Orthodonticset laWendell L. Wylie Memorial Lecture, à l'Université de San Francisco, Californie.
Lateral movements in Rayleigh–Taylor instabilities due to frontiers. Experimental study
Authors: Binda L. , Fernández D. , El Hasi C. , Zalts A. , D'Onofrio A.
Published: January 2018

Lateral movements of the fingers in Rayleigh-Taylor hydrodynamic instabilities at the interface between two fluids are studied. We show that transverse movements appear when a physical boundary is present; these phenomena have not been explained until now. The boundary prevents one of the fluids from crossing it. Such frontiers can be buoyancy driven as, for example, the frontier to the passage of a less dense solution through a denser solution or when different aggregation states coexist (liquid and gaseous phases). An experimental study of the lateral movement velocity of the fingers was performed for different Rayleigh numbers (Ra), and when oscillations were detected, their amplitudes were studied. Liquid-liquid (L–L) and gas-liquid (G–L) systems were analysed. Aqueous HCl and Bromocresol Green (sodium salt, NaBCG) solutions were used in L–L experiments, and CO2 (gas) and aqueous NaOH, NaHCO3, and CaCl2 solutions were employed for the G–L studies. We observed that the lateral movement of the fingers and finger collapses near the interface are more notorious when Ra increases. The consequences of this, for each experience, are a decrease in the number of fingers and an increase in the velocity of the lateral finger movement close to the interface as time evolves. We found that the amplitude of the oscillations did not vary significantly within the considered Ra range. These results have an important implication when determining the wave number of instabilities in an evolving system. The wave number could be strongly diminished if there is a boundary.