Browsing by Author "Balci, Arif"

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    Development of a decision support system to select materials for pressure vessels
    (2018) Ic, Yusuf Tansel; Balci, Arif; Yurdakul, Mustafa; AAI-1081-2020
    Improvements in technologies applied in material field and continual increase in the number of material types force to develop and use new approaches in material selection. In this paper, a multi-criteria decision support system, called MATSEL, is developed to make material selection decisions for pressure vessel components more thorough and inclusive. MATSEL consists of two separate stages. In the first elimination stage of the MATSEL, it obtains a feasible set of materials for a specified pressure vessel component. MATSEL, then, uses three different multi criteria approaches namely ELECTRE, TOPSIS and VIKOR in the second stage to rank the feasible materials. An overall total score is obtained by summing the rankings of every feasible material and MATSEL proposes the material with the lowest total score as the most suitable one for the specified component. In this study, the statistical similarities between the rankings are also calculated to analyze the differences between rankings if there are any. Instead of inputting the materials every time MATSEL is used, a material data base is formed with the usage of ASME (American Society of Mechanical Engineers) and Ashby material selection diagrams for selection of alternative materials for the specified application.
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    A knowledge-based material selection system for interactive pressure vessel design
    (2020) Yurdakul, Mustafa; Balci, Arif; Ic, Yusuf Tansel; AAI-1081-2020
    Continual introduction of new materials and improvements in existing materials increase the variety of materials that can be used for pressure vessel components. Among wide variety of materials, the most suitable one must be selected for a component by matching its functional requirements with various available materials' specifications. This study proposes an interactive knowledge-based decision support system for selecting the most suitable material for a given pressure vessel component and its working environment. The developed decision support system, namely Pressure Vessel SELection (PVSEL), consists of two separate phases. In the first elimination phase of PVSEL, the user obtains a feasible set of alternative materials by answering various questions and providing lower-limit values at materials' critical specifications. PVSEL, then, uses a ranking phase which uses ELECTRE, TOPSIS and VIKOR methods to rank the feasible materials. In the second phase, each alternative material's ranking is determined by combining its performance values at weighted critical specifications (selection criteria), which are considered as important in meeting the functional requirements of the component. Usage of PVSEL is illustrated in the paper and the results show that the proposed PVSEL is an effective selection tool and provides meaningful results for the designers.
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    Understanding the Impact of Pulmonary Rehabilitation on Airway Resistance in Patients with Severe COPD: A Single-Center Retrospective Study
    (2023) Kilic, Lutfiye; Onur, Seda Tural; Dilektasli, Asli Gorek; Ulubay, Gaye; Balci, Arif; 36628301
    Purpose: We investigated the effect of pulmonary rehabilitation (PR) on airway resistance in chronic obstructive pulmonary disease (COPD) patients with severe airway obstruction and hyperinflation. Patients and Methods: This retrospective cohort study was conducted with data from severe COPD cases with those who underwent an 8-week PR program. Main inclusion criteria were having severe airflow obstruction (defined as a forced expiratory volume in one second (FEV1) <50%) and plethysmographic evaluation findings being compatible with hyperinflation supporting the diagnosis of emphysema (presence of hyperinflation defined as functional residual capacity ratio of residual volume to total lung capacity (RV/TLC) >120%). Primary outcomes were airway resistance (Raw) and airway conductance (Gaw) which were measured by body plethysmography, and other measurements were performed, including 6-minute walk test (6-MWT), modified Medical Research Council dyspnea scale (mMRC) and COPD assessment test (CAT).Results: Twenty-six severe and very severe COPD patients (FEV1, 35.0 +/- 13.1%; RV/TLC, 163.5 +/- 29.4) were included in the analyses, mean age 62.6 +/- 5.8 years and 88.5% males. Following rehabilitation, significant improvements in total specific airway resistance percentage (sRawtot%, p = 0.040) and total specific airway conductance percentage (sGawtot%; p = 0.010) were observed. The post-rehabilitation mMRC scores and CAT values were significantly decreased compared to baseline results (p < 0.001 and p < 0.001, respectively). Although there were significant improvements in 6-MWT value (p < 0.001), exercise desaturation (Delta SaO2, p = 0.026), the changes in measured lung capacity and volume values were not significant.Conclusion: We concluded that PR may have a positive effect on airway resistance and airway conductance in COPD patients with severe airflow obstruction.