Enabling microstructural changes of FCC/BCC alloys in 2D dislocation dynamics

Dimension reduction procedure is the recipe to represent defects in two dimensional dislocation dynamics according to the changes in the geometrical properties of the defects triggered by different conditions such as radiation, high temperature, or pressure. In the present study, this procedure is extended to incorporate further features related to the presence of defects with a special focus on face-centered cubic/body-centered cubic alloys used for diverse engineering purposes. In order to reflect the microstructural state of the alloy on the computational cell of two dimensional dislocation dynamics, the distribution of the multi-type defects over slip lines is implemented by using corresponding strength and line spacing for each type of defect. Additionally, a simple recursive incremental relation is set to count the loop accumulation on the precipitates. In the case of continuous resistance against the motion of edge dislocations on the slip lines, an expression of friction is introduced to see its contribution on the yield strength. Each new property is applied independently on a different material by using experimental information about defect properties and grain sizes under the condition of plain strain deformation: both constant and dynamically increasing obstacle strength for precipitate coarsening in prime-aged and heat-treated copper-chromium-zirconium, internal friction in tantalum-2.5tungsten, and mixed hardening due to the presence of precipitates and prismatic loops in irradiated oxide dispersion strengthened EUROFER with 0.3% yttria.Comment: 23 pages, 16 figures, 8 table

COME: Cylindrical oriented muon emission in GEANT4 simulations

In this study, a source scheme based on source biasing as well as discrete energy spectrum in the cylindrical geometry is presented for the simulations of muon tomography in the GEANT4 toolkit. First, a lateral cylindrical surface as well a top circular disc acts as a generation surface that surrounds the tomographic setup, and the generated muons are directed towards the origin where the target volume is situated. Secondly, the kinetic energy of the entering muons is assigned by using a 80-bin discrete energy spectrum between 0 and 8 GeV that is extracted from the CRY muon generator. Thus, the present recipe is called cylindrical oriented muon emission (COME). This source scheme may especially find its applications in the cases where the lateral muon detectors are utilized in order to profit from the horizontal or horizontal-like muons.Comment: 6 pages, 2 figure

Müoni kvantitatiivsed ja kvalitatiivsed uuringud hajuv tomograafia GEANT4 simulatsioonide kaudu: arvutuslik uuring

Müüontomograafia on suhteliselt uudne kuvatehnika, mis kasutab kosmiliste kiirte vastastikmõjus atmosfääriga tekkivat vaba looduslikku müüonite kiirgusvoogu. Müüonite hajumisel põhinevas tomograafias mõõdetakse müüonite levikut ja hajumist uuritavas ruumalas või kehas, mis sõltub peamiselt aine aatomarvust, materjali tihedusest ning paksusest. Käesoleva doktoritöö eesmärk on karakteriseerida müüonite käitumist valitud tomograafilises süsteemis ja materjalides, nagu näiteks tuumamaterjalid. Uuringud on läbi viidud nii kvantitatiivses kui ka kvalitatiivses vormingus. Esiteks, hindasime sissetulevate müüonite kineetilist energiat, kasutades polüvinüültolueenist valmistatud detektorikihtide poolt tekitatavaid müüonite trajektooride hälbeid. Teiseks, hindasime keha positsioneerimise teostatavust triangulatsioonkorrelatsiooni meetodil ning määrasime homogeniseeritud ja homogeniseerimata tuumajäätmete konteinerite mõõtmise jaoks sellised iseloomulikud parameetrid, nagu hajumisjaotus, müüoni neeldumine ja müüonite trajektooride nihked. Püüdsime täiustada ka müüoniallikaid. Selle asemel, et kasutada diskreetse või ühtlase energiajaotusega laiapindset vertikaalset müüonkiirgusallikat, lõime ise keerulisemad, piiratud ulatusega, diskreetse energiaspektriga allikad.Muon tomography is a relatively novel imaging technique that makes use of the free natural flux of muons originating from the interaction of cosmic rays in the atmosphere. The principle behind the muon scattering tomography is to track the propagation of the cosmic ray muons within the target volume through which the incoming muons of a certain energy deviate from their initial trajectories after a series of physical processes predominantly depending on the atomic number, the material density, and the material thickness. In this PhD thesis, our objective is to summarize a number of presentations and publications that are devoted to the computational aspects of muon tomography, the purpose of which is to characterize the target materials such as nuclear materials in diverse applications. We present our outcomes in a quantitative as well as in a qualitative format when/if necessary. First, we attempt to estimate the kinetic energy of the incoming muons by using the deflection angle through the detector layers fabricated from polyvinyl toluene. Secondly, in addition to the derivation of the triangular correlation, we determine the characteristic parameters such as the scattering angle, the muon absorption, and the muon displacement for the bulky nuclear waste barrels as well as the homogenized nuclear waste barrels. Finally, rather than using the vertical muons with either a constant energy or a uniform energy distribution, we try to sophisticate the muon sources by utilizing a restrictive plane and a discretized energy spectrum.https://www.ester.ee/record=b555893

Towards energy discretization for muon scattering tomography in GEANT4 simulations: A discrete probabilistic approach

In this study, by attempting to eliminate the disadvantageous complexity of the existing particle generators, we present a discrete probabilistic scheme adapted for the discrete energy spectra in the GEANT4 simulations. In our multi-binned approach, we initially compute the discrete probabilities for each energy bin, the number of which is flexible depending on the computational goal, and we solely satisfy the imperative condition that requires the sum of the discrete probabilities to be the unity. Regarding the implementation in GEANT4, we construct a one-dimensional probability grid that consists of sub-cells equaling the number of the energy bin, and each cell represents the discrete probability of each energy bin by fulfilling the unity condition. Through uniformly generating random numbers between 0 and 1, we assign the discrete energy in accordance with the associated generated random number that corresponds to a specific cell in the probability grid. This probabilistic methodology does not only permits us to discretize the continuous energy spectra based on the Monte Carlo generators, but it also gives a unique access to utilize the experimental energy spectra measured at the distinct particle flux values. Ergo, we initially perform our simulations by discretizing the muon energy spectrum acquired via the CRY generator over the energy interval between 0 and 8 GeV along with the measurements from the BESS spectrometer and we determine the average scattering angle, the root-mean-square of the scattering angle, and the number of the muon absorption by using a series of slabs consisting of aluminum, copper, iron, lead, and uranium. Eventually, we express a computational strategy in the GEANT4 simulations that grants us the ability to verify as well as to modify the energy spectrum depending on the nature of the information source in addition to the exceptional tracking speed.Comment: 9 pages, 5 figures, 4 tables, ACAT 202

BLOCKCHAIN FUTURES IN CRYPTOCURRENCIES, TRADE AND FINANCE: A PRELIMINARY ASSESSMENT

The study explores whether blockchain technology can change the paradigm of the current financial structure and the balance of power in the international financial system. Accordingly, this study reviews the development of blockchain technology by analyzing China and Venezuela, both of which struggle to harness their technological advancement and to enhance their power in the international realm. We found that Venezuela invests in blockchain technology to create an alternative payment structure for survivability, while China’s desire is to become a global leader in global blockchain technology.The study explores whether blockchain technology can change the paradigm of the current financial structure and the balance of power in the international financial system. Accordingly, this study reviews the development of blockchain technology by analyzing China and Venezuela, both of which struggle to harness their technological advancement and to enhance their power in the international realm. We found that Venezuela invests in blockchain technology to create an alternative payment structure for survivability, while China’s desire is to become a global leader in global blockchain technology

Particle generation through restrictive planes in GEANT4 simulations for potential applications of cosmic ray muon tomography

In this study, by attempting to resolve the angular complication during the particle generation for the muon tomography applications in the GEANT4 simulations, we exhibit an unconventional methodology that is hinged on the direction limitation via the vectorial construction from the generation location to the restriction area rather than using a certain angular distribution or interval. In other words, we favor a momentum direction that is determined by a vector constructed between an initial point randomly chosen on a generative point/plane and a latter point arbitrarily selected on a restrictive plane of the same dimensions with the basal cross section of the volume-of-interest (VOI). On account of setting out such a generation scheme, we optimize the particle loss by keeping an angular disparity that is directly dependent on the VOI geometry as well as the vertical position of the restrictive plane for a tomographic system of a finite size. We demonstrate our strategy for a set of target materials including aluminum, copper, iron, lead, and uranium with a dimension of 40$\times$10$\times$40 $\rm cm^{3}$ over three restrictive planes of different positions by using a discrete energy spectrum between 0.1 and 8 GeV and we compute the scattering angle, the number of absorption, and the particle loss. Upon our simulation outcomes, we show that the particle generation by means of restrictive planes is an effective strategy that is flexible towards a variety of computational objectives in the GEANT4 simulations.Comment: 7 pages, 2 figures, 9 tables, ACAT 202

Bitcoin and altcoins price dependency: Resilience and portfolio allocation in COVID-19 outbreak

The main aim of this article is to examine the inter-relationships among the top cryptocurrencies on the crypto stock market in the presence and absence of the COVID-19 pandemic. The nine chosen cryptocurrencies are Bitcoin, Ethereum, Ripple, Litecoin, Eos, BitcoinCash, Binance, Stellar, and Tron and their daily closing price data are captured from coinmarketcap over the period from 13 September 2017 to 21 September 2020. All of the cryptocurrencies are integrated of order 1 i.e., I(1). There is strong evidence of a long-run relationship between Bitcoin and altcoins irrespective of whether it is pre-pandemic or pandemic period. It has also been found that these cryptocurrencies' prices and their inter-relationship are resilient to the pandemic. It is recommended that when the investors create investment plans and strategies they may highly consider Bitcoin and altcoins jointly as they give sustainability and resilience in the long run against the geopolitical risks and even in the tough time of the COVID-19 pandemic.Q2WOS:00064362100000

Investigation of deflection angle for muon energy classification in muon scattering tomography via GEANT4 simulations

In muon scattering tomography, the investigated materials are discriminated according to the scattering angle that mainly depends on the atomic number, the density, and the thickness of the medium at a given energy value. The scattering angles at different initial energies also provide the opportunity to classify the incoming muons into a number of energy groups. In this study, by employing the GEANT4 code, we show that the deflection angle exponentially decays as a function of energy, and the numerical values for the current configuration are below the detector accuracy except the initial energy bins owing to the low-Z, low density, and low thickness of the current plastic scintillators. This implies the necessity of additional components that provoke the muon scattering. Therefore, we introduce stainless steel surfaces into the top and bottom sections in order to amplify the deflection angle as well as to reduce the uncertainty, thereby improving the detector performance