Ozcan F.,Nide University
Construction and Building Materials | Year: 2012
In this study, gene expression programming (GEP) formulations for splitting tensile strength (f spt) of the cylinder specimens with 150 mm diameter and 300 mm height using compressive strength (f c) of concrete cube specimens with 150 mm dimension are developed. Two models, called as GEP-I and GEP-II, are developed for predicting f spt by using GEP. The database used in the GEP models is based on experimental data obtained from literature. In the GEP-I model, while f c is used as input variable, f spt is used as output variable. However, in the GEP-II model, as well as f c, water-binder ratio (WB) is used as input variables. The data sets used in training and testing stages are randomly selected among all experimental data. The GEP formulations are also validated with additional experimental data other than the data used in training and testing sets of the GEP models. Experimental f spt results of concrete specimens are compared with GEP formulations, proposed formulations by some national building codes and the developed regression-based formulation results. The results show that GEP formulations have strong potential as a feasible tool for prediction of the f spt from only 150 mm cube f c or WB and 150 mm cube f c of concrete. © 2011 Elsevier Ltd. All rights reserved.
Bahar M.K.,Karamanoglu Mehmetbey University |
Soylu A.,Nide University
Physics of Plasmas | Year: 2014
We numerically solve the Schrödinger equation, using a more general exponential cosine screened Coulomb (MGECSC) potential with an electric field, in order to investigate the screening and weak external electric field effects on the hydrogen atom in plasmas. The MGECSC potential is examined for four different cases, corresponding to different screening parameters of the potential and the external electric field. The influences of the different screening parameters and the weak external electric field on the energy eigenvalues are determined by solving the corresponding equations using the asymptotic iteration method (AIM). It is found that the corresponding energy values shift when a weak external electric field is applied to the hydrogen atom in a plasma. This study shows that a more general exponential cosine screened Coulomb potential allows the influence of an applied, weak, external electric field on the hydrogen atom to be investigated in detail, for both Debye and quantum plasmas simultaneously. This suggests that such a potential would be useful in modeling similar effects in other applications of plasma physics, and that AIM is an appropriate method for solving the Schrödinger equation, the solution of which becomes more complex due to the use of the MGECSC potential with an applied external electric field. © 2014 AIP Publishing LLC.
Gokek M.,Nide University
International Journal of Hydrogen Energy | Year: 2010
This study presents a techno-economic evaluation on hydrogen generation from a small-scale wind-powered electrolysis system in different power matching modes. For the analysis, wind speed data, which measured as hourly time series in Kirklareli, Turkey, were used to predict the electrical energy and hydrogen produced by the wind-hydrogen energy system and their variation according to the height of the wind turbine. The system considered in this study is primarily consisted of a 6 kW wind-energy conversion system and a 2 kW PEM electrolyzer. The calculation of energy production was made by means of the levelized cost method by considering two different systems that are the grid-independent system and the grid-integrated system. Annual production of electrical energy and hydrogen was calculated as 15,148.26 kWh/year and 102.37 kg/year, respectively. The highest hydrogen production is obtained in January. The analyses showed that both electrical energy and hydrogen production depend strongly on the hub height of wind turbine in addition to the economic indicators. In the grid-integrated system, the calculated levelized cost of hydrogen changes in the range of 0.3485-4.4849 US$/kg for 36 m hub height related to the specific turbine cost. The grid-integrated system can be considered as profitable when the excess electrical energy delivered by system sold to the grid. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
Saridemir M.,Nide University
Construction and Building Materials | Year: 2010
Soft computing techniques have recently been widely used to model some of human activities in many areas of civil engineering applications. In this paper, two models in gene expression programming (GEP) approach for predicting compressive strength of concretes containing rice husk ash have been developed at the age of 1, 3, 7, 14, 28, 56 and 90 days. For purpose of building the models, experimental results for 188 specimens produced with 41 different mixture proportions are obtained from the literature. According to these experimental results, the models are arranged by using seven different input variables in GEP approach. In according to these input variables, the compressive strength values from mechanical properties of concretes containing rice husk ash are predicted in GEP approach models. The results of training, testing and validation sets of the models are compared with experimental results. All of the results showed that GEP is a strong technique for the prediction of compressive strength values of concretes containing rice husk ash. © 2010 Elsevier Ltd. All rights reserved.
Vapur H.,Cukurova University |
Bayat O.,Cukurova University |
Uurum M.,Nide University
Energy Conversion and Management | Year: 2010
This study discusses a new coal flotation optimization approach. It is conducted using modified flotation parameters and combustible recovery. The experimental work was evaluated in two stages. In the first stage, recoveries (1, 2, 3, 5 and 8 min of flotation times) of Jameson flotation operating parameters were fitted to first-order kinetic model, R = R∞ [1 - exp (-kt)] where R was recovery at t time, R∞ was ultimate recovery and k was the first-order rate constant to draw the time recovery curves in the experimental study. Two parameters, the ultimate recovery (R ∞) and first-order rate constant (k), were then obtained from the model to fit an experimental time recovery curve. A modified flotation rate constant (Km) defined as product of R∞ and k, i.e., Km = R∞ k, and selectivity index (SI) defined as the ratio of the modified rate constant of coal to the modified rate constant of ash (SI)=Km of Coal/Km of Ash), which could be collectively called "modified flotation parameters". It was used to determine of the sub and upper values of operation variables. In the second one, combustible recovery (%) and ash content (%) were used to optimization of the Jameson flotation variables and it was found that d80 = 0.250 mm particle size, 1/1 vegetable oil acids/kerosene ratio, 20% solids pulp density, 0.600 L/min wash water rate and 40 cm downcomer immersion dept could be used to separate efficiently coal from ash. Final concentrate was obtained with 94.83% combustible recovery and 17.86% ash content at optimum conditions after 8 min flotation time. © 2010 Elsevier Ltd. All rights reserved.
Menguc E.C.,Nide University |
Acir N.,Bursa Teknik University
2015 23rd Signal Processing and Communications Applications Conference, SIU 2015 - Proceedings | Year: 2015
In this study, a new approach based on Lyapunov stability theory (LST) is proposed for channel equalization problem. For the first time, the convergence capability of the proposed algorithm is presented on the channel equalization problem. The proposed approach is compared with normalized least mean square (NLMS) algorithm. Simulation results show that the convergence capability of the proposed algorithm is better than NLMS algorithm. As a result, the proposed approach can effectively be used for the channel equalization problem. © 2015 IEEE.
Saridemir M.,Nide University
Expert Systems with Applications | Year: 2011
Compressive strength and splitting tensile strength are both mechanical properties of concrete that are utilized in structural design. This study presents gene expression programming (GEP) as a new tool for the formulations of splitting tensile strength from compressive strength of concrete. For purpose of building the GEP-based formulations, 536 experimental data have been gathered from existing literature. The GEP-based formulations are developed for splitting tensile strength of concrete as a function of age of specimen and cylinder compressive strength. In experimental parts of this study, cylindrical specimens of 150 × 300 mm and 100 × 200 mm in dimensions are utilized. Training and testing sets of the GEP-based formulations are randomly separated from the complete experimental data. The GEP-based formulations are also validated with additional 173 data of experimental results other than the data used in training and testing sets of the GEP-based formulations. All of the results obtained from the GEP-based formulations are compared with the results obtained from experimental data, the developed regression-based formulation and formulas given by some national building codes. These comparisons showed that the GEP-based formulations appeared to well agree with the experimental data and found to be quite reliable. © 2011 Elsevier Ltd. All rights reserved.
Guneyisi E.,University of Gaziantep |
Gesolu M.,University of Gaziantep |
Altan I.,University of Gaziantep |
Oz H.O.,Nide University
Construction and Building Materials | Year: 2015
In this study, lightweight fly ash fine aggregates (LWFAs) were used as a partial replacement of natural fine aggregate to investigate the fresh and hardened states of self-compacting mortars (SCMs). For this, a powder mixture of 90% fly ash (FA) and 10% Portland cement (PC) by weight were pelletized in a tilted pan through a cold-bonded agglomeration process. Thereafter, a total of five mixtures of SCMs were prepared in which natural fine aggregate was replaced by LWFA partially started from 0% to 100% by 25% increment. Subsequently, tests carried out on the fresh mortar involved mini-slump flow, mini-V-funnel flow time and viscosity while the hardened properties of SCMs were evaluated using the compressive strength, ultrasonic pulse velocity, gas permeability and sorptivity tests. The hardened characteristics of SCMs were determined at different ages up to 56 days. It was observed that the increased percentage of LWFA improved the workability and the flowability of SCMs. On the other hand, the strength and permeability properties of SCMs had a negative effect due to the substitution of LWFAs for natural fine aggregate, especially at higher replacement level. © 2014 Elsevier Ltd. All rights reserved.
Karaca Z.,Canakkale Onsekiz Mart University |
Hacimustafaolu R.,Dokuz Eylül University |
Gokce M.V.,Nide University
Construction and Building Materials | Year: 2015
In this study, the effects of relationships of micro-structure, grain size and grain boundary of 15 well-known worldwide marbles on some physical and mechanical properties (dry unit weight, porosity, uniaxial compressive strength, tensile strength) and on abrasion loss value were investigated in detail, being the first in terms of elaborateness in the literature considering the mentioned features. 10 different samples were tested for each marble in each test. Microscope images were grouped as intergranular properties (shape of grains, shape of grain aggregates, grain boundary type and pressure solution), intragranular properties (twinning and alteration) and deformation. All marbles which were tested were found to be of heteroblastic texture. Nine samples were monomineralic marble while six were polymineralic. It was determined that grain characteristics and grain boundary interaction affected dry unit weight, porosity, uniaxial compressive strength, tensile strength and abrasion loss value of each marble tested. © 2015 Elsevier Ltd. All rights reserved.
Deniz H.,Erciyes University |
Inci F.,Nide University
Journal of Psychosocial Oncology | Year: 2015
This study was conducted to identify the burden of care and quality of life of caregivers of leukemia and lymphoma patients who had undergone peripheric stem cell transplantation. The sample consisted of 123 patient caregivers, all of whom were relatives. Data were collected using a survey, the Burden Interview, and the Caregiver Quality of Life Index Cancer Scale. Data evaluation was done using correlation analysis, Kruskall Wallis, and Mann-Whitney U tests. Factors that were significantly associated with quality of life and care burden perception included caring for an older patient, patient dependence for daily activities, and having low economic status. Copyright © 2015 Taylor & Francis Group, LLC.