Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2025Scopus SJRQ2/r/gumushane/12464
  Investigation of Nonstandard Finite Difference for Fractional Order Covid-19 Model

  Merdan, Mehmet; Acikgoz, Pınar

  This article examines a mathematical model of the Covid-19 type. We demonstrate how the population is impacted by immigration, protection, the mortality, exposure, curing, and interactions between sick and healthy individuals. There are five classifications in our model: exposed, susceptible, infected, quarantined, and recovered. The model is subjected to numerical and fractional analysis in this instance. The numerical analysis is performed using the fractional order non-standard finite difference (NSFD) scheme. The Grunwald-Letnikov numerical approximation technique is used for fractional analysis. The findings are evaluated by simulations using the Matlab tool.

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  AtıfScopus3·WoS2·OpenAlex2

  İncele
• MakaleAçık Erişim2022Scopus SJRQ2/r/gumushane/14411
  Homotopy Perturbation Elzaki Transform Method for Obtaining the Approximate Solutions of the Random Partial Differential Equations

  Anac, Halil; Merdan, Mehmet; Kesemen, Tulay

  The series solutions of the random nonlinear partial differential equations have been examined by a hybrid method. The random nonlinear partial differential equations are studied by both normal and uniform distributions. Two initial-value problems are indicated to exemplify the influence of the solutions acquired by the hybrid method. Also, the functions for the first and second moments of the approximate solutions of random nonlinear partial differential equations are acquired in the MAPLE software. The hybrid method is implemented to analyze the solutions of the random nonlinear partial differential equations. MAPLE software is used to find the solutions. Besides, MAPLE software is used for the drawing the figures.

  AtıfScopus7·WoS6·OpenAlex10

  İncele
• MakaleAçık Erişim2021Scopus SJRQ2/r/gumushane/12878
  Predicting stock prices using machine learning methods and deep learning algorithms: The sample of the istanbul stock exchange

  Demirel, Ugur; Cam, Handan; Unlu, Ramazan

  Stock market prediction in financial and commodity markets is a major challenge for speculators, investors, and companies but also profitable with an accurate prediction. Thus, obtaining accurate prediction results becomes extremely important especially while the stock market is essentially volatile, nonlinear, complicated, adaptive, nonparametric and unpredictable in nature. This study aims to forecast the opening and closing stock prices of 42 firms listed in Istanbul Stock Exchange National 100 Index (ISE-100) using well-known machine learning methods, Multilayer Perceptrons (MLP) and Support Vector Machines (SVM) models and deep learning algorithm, Long Short Term Memory (LSTM) by comparing their forecasting performances. The analysis includes 9 years of data from 01.01.2010 to 01.01.2019. For each firm 2249 data for the opening and 2249 for the closing stock prices were established as daily data sets. Forecasting performance of these methods was evaluated by applying different criteria for each model: root mean squared error (RMSE), mean squared error (MSE) and R-squared (R2). The results of this study show that MLP and LSTM models become advantageous in estimating the opening and closing stock prices comparing to SVM model.

  AtıfScopus25·WoS9·OpenAlex37·TR Dizin5

  İncele
• MakaleYalnız künye2017Scopus SJRQ2/r/gumushane/15217
  An integrated intuitionistic fuzzy set and mathematical programming approach for an occupational health and safety policy

  Efe, Burak; Kurt, Mustafa; Efe, Ömer Faruk

  This paper aims to establish an occupational health and safety policy for three firms. This paper provides to overcome the drawbacks of traditional FMEA (failure mode and effects analysis) by using an integrated intuitionistic fuzzy multi-criteria decision making method and a linear programming. Priority value of criteria has been defined by utilizing intuitionistic fuzzy analytic hierarchy process method and the highest risky failure mode among failure modes has been found by utilizing intuitionistic fuzzy VIKOR (VIsekriterijumska optimizacija i KOm-promisno Resenje). The application of risk evaluation is conducted to show the effectiveness of the proposed method in three firms. The reliability of the risk ranking is verified by helping of a sensitivity analysis and the advantages of the proposed approach are shown by comparing with the other methods. The managers of the firm present some limitations for the occupational health and safety policy so that these constraints are solved by helping of a linear programming. The results show that destroying of the existing steel ropes during production of plaster, risks that caused from work equipment and electric shock during cutting were determined the highest risky failure modes for construction, textile and metal firms, respectively.

  AtıfScopus29·WoS27

  İncele
• MakaleYalnız künye2011Scopus SJRQ2/r/gumushane/15442
  The effect of antifreeze admixtures on compressive strength of concretes subjected to frost action

  Arslan, Metin; Çullu, Mustafa; Durmuş, Gökhan

  This study aims to determine the effect of antifreeze admixture used in the concretes subjected to frost action on the concrete compressive strength. Three groups of concrete samples of C30 class were prepared with antifreeze admixtures by using the mixture of 30% calcium nitrate and 5% hydroxy ethoxy amin (A), calcium nitrate (B), Polyhydroxy amine (C). Concrete samples are put in the freezer in a fresh state 15 min after the mixing. Samples are subjected to frost action in 0, -5, -10, -15 and -20°C degrees for 48 hours. On the concrete samples water cured after 48 hours, compressive strength tests of 28 day are conducted. Consequently, it is seen that with the increase of the set temperature that concrete is cured, compressive strength of concrete is decreased and among all types of antifreezes the maximum decrease is seen between 0 and -5°C while the decrease in compressive strength is relatively less for -10, -15 and -20°C.

  AtıfScopus6·WoS7

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