Browsing by Publisher "EDP Sciences"
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Item Parameters affecting of Akkuyu's safety assessment for severe core damages(EDP Sciences, 2015) Kavun Y.; Karasulu M.We have looked at all past core meltdowns (Three Mile Island, Chernobyl and Fukushima incidents) and postulated the fourth one might be taking place in the future most probably in a newly built reactors anywhere of the earth in any type of NPP. The probability of this observation is high considering the nature of the machine and human interaction. Operation experience is a very significant parameter as well as the safety culture of the host nation. The concerns is not just a lack of experience with industry with the new comers, but also the infrastructure and established institutions who will be dealing with the Emergencies. Lack of trained and educated Emergency Response Organizations (ERO) is a major concern. The culture on simple fire drills even makes the difference when a severe condition occurs in the industry. The study assumes the fourth event will be taking place at the Akkuyu NGS and works backwards as required by the "what went wrong " scenarios and comes up with interesting results. The differences studied in depth to determine the impact to the severe accidents. The all four design have now core catchers. We have looked at the operator errors'like in TMI); Operator errors combined with design deficiencies(like in Chernobyl) and natural disasters(like in Fukushima) and found operator errors to be more probable event on the Akkuyu's postulated next incident. With respect to experiences of the operators we do not have any data except for long and successful operating history of the Soviet design reactors up until the Chernobyl incident. Since the Akkuyu will be built, own and operated by the Russians we have found no alarming concerns at the moment. At the moment, there is no body be able to operate those units in Turkey. Turkey is planning to build the required manpower during the transition period. The resolution of the observed parameters lies to work and educate, train of the host nation and exercise together. © 2015 Owned by the authors, published by EDP Sciences.Item The average lower reinforcement number of a graph(EDP Sciences, 2016) Turaci T.; Aslan E.Let G = (V(G),E(G)) be a simple undirected graph. The reinforcement number of a graph is a vulnerability parameter of a graph. We have investigated a refinement that involves the average lower reinforcement number of this parameter. The lower reinforcement number, denoted by re∗(G), is the minimum cardinality of reinforcement set in G that contains the edge e∗ of the complement graph G. The average lower reinforcement number of G is defined by rav (G)=1/E(G) ∑e∗∈E(G) re∗(G). In this paper, we define the average lower reinforcement number of a graph and we present the exact values for some well-known graph families. © EDP Sciences 2016.Item Neighbor isolated tenacity of graphs(EDP Sciences, 2016) Aslan E.The tenacity of a graph is a measure of the vulnerability of a graph. In this paper we investigate a refinement that involves the neighbor isolated version of this parameter. The neighbor isolated tenacity of a noncomplete connected graph G is defined to be {x+c(G/X)/i(G/X), i(G/X) ≥1} where the minimum is taken over all X, the cut strategy of G, i(G/X)is the number of components which are isolated vertices of G/X and c(G/X) is the maximum order of the components of G/X. Next, the relations between neighbor isolated tenacity and other parameters are determined and the neighbor isolated tenacity of some special graphs are obtained. Moreover, some results about the neighbor isolated tenacity of graphs obtained by graph operations are given. © EDP Sciences 2016.Item The average scattering number of graphs(EDP Sciences, 2016) Aslan E.; Kilinç D.; Yücalar F.; Borandaǧ E.The scattering number of a graph is a measure of the vulnerability of a graph. In this paper we investigate a refinement that involves the average of a local version of the parameter. If v is a vertex in a connected graph G, then scv(G) = max {ω(G - Sv) - | Sv |}, where the maximum is taken over all disconnecting sets Sv of G that contain v. The average scattering number of G denoted by scav(G), is defined as scav(G) = Σv ϵ V(G) scv(G) / n, where n will denote the number of vertices in graph G. Like the scattering number itself, this is a measure of the vulnerability of a graph, but it is more sensitive. Next, the relations between average scattering number and other parameters are determined. The average scattering number of some graph classes are obtained. Moreover, some results about the average scattering number of graphs obtained by graph operations are given. © EDP Sciences 2016.Item Preliminary results of Sr/Ca ratio study of teeth samples by photoactivation analysis(EDP Sciences, 2016) Kavun Y.; Boztosun I.; Maraş I.; Dapo H.; Segebade C.In this paper, we have performed Photoactivation Analysis (PAA), a non-destructive method, which is used to determine elemental concentration of any sample. This paper presents the first use of this method in medical sciences in Turkey. The method was applied to the determination of Sr/Ca ratios in teeth. The collected teeth samples and standards (SrO and CaCO3) have been irradiated for a fixed time interval with high energy photons. The photons were generated by a clinical linear accelerator (cLINAC). The photon end-point energy was 18 MeV. The energy and the time interval were sufficient to achieve good activation. Afterward, the samples and standards have been analysed with gamma spectroscopic analysis by using an HPGe detector system. By analysing many samples, a database of Sr/Ca ratios will be created at Nuclear Research and Application Center (NUBA). In this paper we present a small subset of the already analysed data as an example of our capabilities and goal. We hope to set an example for future studies. © The Authors, published by EDP Sciences.Item Proton bombarded reactions of Calcium target nuclei(EDP Sciences, 2017) Tel E.; Sahan M.; Sarpün I.H.; Kavun Y.; Gök A.A.; Depedelen M.In this study, proton bombarded nuclear reactions calculations of Calcium target nuclei have been investigated in the incident proton energy range of 1-50 MeV. The excitation functions for 40Ca target nuclei reactions have been calculated by using PCROSS nuclear reaction calculation code. Weisskopf-Ewing and the full exciton models were used for equilibrium and for pre-equilibrium calculations, respectively. The excitation functions for 40Ca target nuclei reactions (p,α), (p,n), (p,p) have been calculated using the semi-empirical formula Tel et al. [5]. © The Authors, published by EDP Sciences, 2017.Item Reaction cross section calculation of some alkaline earth elements(EDP Sciences, 2017) Tel E.; Kavun Y.; Sarpün I.H.Reaction cross section knowledge is crucial to application nuclear physics such as medical imaging, radiation shielding and material evaluations. Nuclear reaction codes can be used if the experimental data are unavailable or are improbably to be produced because of the experimental trouble. In this study, there action cross sections of some target alkaline earth elements have been calculated by using pre-equilibrium and equilibrium nuclear reaction models for nucleon induced reactions. While these calculations, the Hybrid Model, the Geometry Dependent Hybrid Model, the Full Exciton Model, the Cascade Exciton Model for pre-equilibrium reactions and the Weisskopf-Ewing Model for equilibrium reactions have been used. The calculated cross sections have been discussed and compared with the experimental data taken from Experimental Nuclear Reaction Data library. © The Authors, published by EDP Sciences, 2017.Item Particle induced nuclear reaction calculations of Boron target nuclei(EDP Sciences, 2017) Tel E.; Sahan M.; Sarpün I.H.; Kavun Y.; Gök A.A.; Poyraz M.Boron is usable element in many areas such as health, industry and energy. Especially, Boron neutron capture therapy (BNCT) is one of the medical applications. Boron target is irradiated with low energy thermal neutrons and at the end of reactions alpha particles occur. After this process recoiling lithium-7 nuclei is composed. In this study, charge particle induced nuclear reactions calculations of Boron target nuclei were investigated in the incident proton and alpha energy range of 5-50 MeV. The excitation functions for 10B target nuclei reactions have been calculated by using PCROSS Programming code. The semi-empirical calculations for (p,α) reactions have been done by using cross section formula with new coefficient obtained by Tel et al. The calculated results were compared with the experimental data from the literature. © The Authors, published by EDP Sciences, 2017.Item Effect of Gr Contents on Wear Properties of Al2024/MgO/Al2O3/Gr Hybrid Composites(EDP Sciences, 2018) Ovall I.; Esen C.; Albayrak S.; Karakoç H.In the present study, hybrid metal matrix composites, Al2024/10Al2O3, Al2024/10Al2O3/3MgO, Al2024/10Al2O3/6MgO, Al2024/10Al2O3/3MgO/1.5 Gr, Al2024/10Al2O3/3MgO/3Gr, and reinforcement samples (AA 2024) produced with powder metallurgy process. AA 2024 and reinforcement powders were determined mixture rations and separately mixed during 30 minutes in a three-dimensional Turbula mixer. The mixed compositions were pressed at 300 MPa and sintered at 550°C during 1 h. After that, three materials were extruded at the same temperature. Experimental results show that hybrid metal matrix composites (HMMCs) a better wear resistance than the reinforcement samples because of higher hardness. Gr behave as a lubricant during wear process. The wear resistance of HMMCs can be optimized with controlling of the reinforcement content and type. © 2018 The Authors.Item Average covering number for some graphs(EDP Sciences, 2019) Doǧan Durgun D.; Bagatarhan A.The interconnection networks are modeled by means of graphs to determine the reliability and vulnerability. There are lots of parameters that are used to determine vulnerability. The average covering number is one of them which is denoted by β(G) , where G is simple, connected and undirected graph of order n ≥ 2. In a graph G = (V (G), E(G)) a subset Sv ⊆ V (G) of vertices is called a cover set of G with respect to v or a local covering set of vertex v, if each edge of the graph is incident to at least one vertex of Sv. The local covering number with respect to v is the minimum cardinality of among the Sv sets and denoted by βv. The average covering number of a graph G is defined as (Equation Presented). In this paper, the average covering numbers of kth power of a cycle Ckn and Pn □ Pm, Pn □ Cm, cartesian product of Pn and Pm, cartesian product of Pn and Cm are given, respectively. © 2019 EDP Sciences, ROADEF, SMAI.Item Prediction of heat and fluid flow in microchannel condensation(EDP Sciences, 2019) Basaran A.; Benim A.C.; Yurddas A.The condensing flow inside the microchannel has gained importance as the microchannel heat exchangers are widely used in the industry. In this study, a number of numerical simulations on condensing flow inside the microchannel were conducted to investigate heat transfer characteristic. Circularmicrochannel geometries with the various diameters were considered. The Volume of Fluid model was used to model twophase flow. The phase change at the saturation temperature was modeled by the Lee model.In the considered geometries, different from the conventional channels, surface tension forces can be importantcomparedto other forces. Therefore, surface tension was considered in the simulations. Constant wall heatflux and constant saturation temperature were applied as simulation conditions, similar to actual operating conditions. The predictions were validated by comparisons with the experimental results that exist in the literature. A satisfactory agreement of the present predictions with the experimental data was observed. © The Authors, published by EDP Sciences, 2019.Item An investigation of cutting parameters effect on sound level, surface roughness, and power consumption during machining of hardened AISI 4140(EDP Sciences, 2020) Sahinoǧlu A.; Ulas E.In recent years, the necessity for energy in the manufacturing industry has become an important problem because fossil fuel reserves are decreasing in order to produce energy. Therefore, the efficient use of energy has become an important research topic. In this study, energy efficiency is investigated in detail for sustainable life and manufacturing. AISI 4140 material with high hardness of 50 HRC hardness has been applied cryogenic process to improve mechanical and machinability properties. In this experiment study, the effects of feed rate (0.04, 0.08, 0.12 mm/rev), cutting speed (140, 160, 180 m/min), depth of cut (0.05, 0.10, 0.15 mm) and tool radius (0.4, 0.8) on energy consumption, surface roughness and sound intensity were investigated. Then, a new mathematical model with high accuracy was developed. Total power consumption was calculated by considering the instantaneous current value and machining time. As a result, it is found that good surface quality obtained when the feed rate is low, and the tool radius is high and the machining time is shortened, the energy consumption is reduced due to the increase in cutting speed, depth of cut and feed rate. Also, it is found that the tool radius has a limited effect on energy consumption, but low feed value increases energy consumption. © 2020 AFM, EDP Sciences.Item Weak and strong domination on some graphs(EDP Sciences, 2022) Durgun D.D.; Kurt B.L.Let G = (V(G), E(G)) be a graph and uv?E. A subset D âV of vertices is a dominating set if every vertex in V-D is adjacent to at least one vertex of D. The domination number is the minimum cardinality of a dominating set. Let u and v be elements of V. Then, u strongly dominates u and v weakly dominates u if (i)uv?E and (ii)deg(u) ?deg(v). A set D â V is a strong (weak) dominating set (sd-set)(wd-set) of G if every vertex in V-D is strongly dominated by at least one vertex in D. The strong (weak) domination number ?s(?w) of G is the minimum cardinality of a sd-set (wd-set). In this paper, the strong and weak domination numbers of comet, double comet, double star and theta graphs are given. The theta graphs are important geometric graphs that have many applications, including wireless networking, motion planning, MST construction and real-Time animation. © The authors.Item An Experimental Design Frame for Active Dam Reserve Ratio Forecasting Using Neural Networks(EDP Sciences, 2024) Mizrak Ozfirat P.; Ari D.Today, one of the important and frequently spoken problems of the world is global warming and climate change. Due to these subjects, water drought and scarcity may become a trouble in the future. To prevent these problems, scientific studies are being carried out, solutions are being recommended and preventive applications are developing. In this study, to examine and foresee the decrease in water resources, active dam reserve ratio is considered and estimated using artificial neural networks. Time series analysis is performed using the active dam reserve ratio of Guzelhisar Dam, located in city of Izmir, Turkiye. Active reserve ratio data between 2012 and 2023 are considered on monthly basis. Since the data set displays high seasonality, this cyclic effect is extracted out of the data to get non-seasonal series. Then, using non-linear autoregressive artificial neural network method, both original seasonal data and non-seasonal data is forecasted. Three parameters are considered for neural network models: Input neurons, middle layer neurons and backpropagation algorithm. Results are compared according to mean absolute percent error. In the result, values of parameters to give minimum error are presented. In addition, performances of backpropagation algorithms are compared. © The Authors, published by EDP Sciences, 2024.Item Energy Use and Lighting of Algal Green Buildings(EDP Sciences, 2024) Tokuç A.; Yaman Y.; Budakoğlu B.; Gülden Köktürk G.; Deniz I.; Ezan M.A.Green buildings can provide a growth environment for microalgae growth on their façades, where a closed environment mimicks the organisms' natural environment and functions as a window. This study investigates such a façade's effect on energy saving by optimizing the performances of useful daylight illuminance (UDI) and energy use intensity (EUI) in the Mediterranean climate. The study was carried out in two stages. The first stage is a parametric study using the Colibri tool to look at the algae content and the effect of WWR for the north and south orientations. Meanwhile the second stage adds different design parameters of orientation, window type, WWR, wall type and thickness, insulation thickness. Optimization of UDI and EUI separately allows an in-depth discussion of these parameters for both performances. The obtained parametric results show the effects of WWR and algae content. Regression analysis explains that WWR has a linear relationship with EUI and a polynomial relationship with UDI. There is no such relationship for algae content, yet it changes UDI results the most (%46.22-81.66 for 50% WWR). Then, computational simulations regard effects of other factors for performance optimization. © The Authors.