Browsing by Author "Altunok, Taner"

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Citation Count: Alam, Sajid Mahboob;...et.al. (2022). "A Survey on Generalized Topological Indices for Silicon Carbide Structure", Journal of Chemistry, Vol.2022, pp.1-11.
A Survey on Generalized Topological Indices for Silicon Carbide Structure
(2022) Alam, Sajid Mahboob; Jarad, Fahd; Mahboob, Abid; Siddique, Imran; Altunok, Taner; 234808
The application of graphs in chemical and molecular structures has exponentially increased during the last few years. Topological indices facilitate the collection of beneficial information and provide an approach to understanding the properties of chemical structure by providing information about algebraic graphs. Let G be a graph with u-vertices and Ωu be the degree of uth vertex. In this manuscript, we compute Zagreb index (ZI), first, and second, Hyper F-indices and sum and product connectivity of F-index of silicon carbides, namely, SiC4 - I[r, s] and SiC4 - II[r, s].
Citation Count: Demirkiran, Z.K.; Altunok, T., "A Systems Approach for Technology Assessment and Selection", Digital Avionics Systems Conference - Proceedings, pp. 6E11-6E111, (2012).
A Systems Approach for Technology Assessment and Selection
(2012) Demirkiran, Zuhal Kale; Altunok, Taner
Each system development project necessitates making decisions on the selection of technologies among available alternatives for the system and is covered in the technology assessment phase in the acquisition process. For the assessment very limited numbers of methodologies most of which are qualitative are defined in the literature. This study aims to propose a systematic model, which can be used as a guide by planners or system architects in the multi-criteria technology selection process. The model also proposes a method to define the critical technology elements for a system. A case study on Unmanned Aerial Vehicle (UAV) communication systems is presented to illustrate the applicability of the model.
Citation Count: Altunok, T., Çakmak, T. (2010). A technology readiness levels (TRLs) calculator software for systems engineering and technology management tool. Advance in Engineering Software, 41(5), 769-778. http://dx.doi.org/ 10.1016/j.advengsoft.2009.12.018
A technology readiness levels (TRLs) calculator software for systems engineering and technology management tool
(Elsevier Science Ltd, 2010) Altunok, Taner; Çakmak, Tanyel
Turkish defense industry and policy makers seek effective and successful system development programs by implementing a validation mechanism to verify the maturity of new technologies being developed in national laboratories and industry. Technology Readiness Levels (TRLs) developed by NASA as a general metric of technology advancement and it has been widely accepted as a systems engineering and technology management metric tool. In order to explore the sufficiency of this tool, first of all, academic and applicable studies of army and civil organizations have been searched out and the lessons learned have been analyzed in this study. Thereafter, questionnaires of awareness of TRLs and TRL Calculator have been applied to defense firms in Ankara, and interviews held with the technology developers, firms' speakers and defense authorities. Finally, the applicable algorithm of TRL calculator has been recommended for Turkish defense industry
Citation Count: Sindhu, Muhammad Sarwar;...et.al. (2022). "An Approach of Decision-Making under the Framework of Fermatean Fuzzy Sets", Mathematical Problems in Engineering, Vol.2022.
An Approach of Decision-Making under the Framework of Fermatean Fuzzy Sets
(2022) Sindhu, Muhammad Sarwar; Siddique, Imran; Ahsan, Muhammad; Jarad, Fahd; Altunok, Taner; 234808
Because of its influence on various elements of human life experiences and conditions, the building industry is a significant business. In the recent past, environmental considerations have been incorporated in the design and planning stages of building supply chains. The process of evaluating and selecting suppliers is one of the most important issues in supply chain management. A multicriteria decision-making (MCDM) problem can be utilized to handle such issues. The goal of this research is to present a new and efficient technique for selecting suppliers with ambiguous data. The suggested methodology's structure is based on technology for order of preference by similarity to ideal solution (TOPSIS), with Fermatean fuzzy sets (Fr FSs) employed to cope with information uncertainty. In this article, authors modified the distance between Fr FSs to propose the similarity measure and implemented it to form the MCDM model to resolve the vague and uncertain data. Moreover, we used this similarity measure to choose the optimal alternative. A practical example for alternative selection is provided, along with a comparison of the acquired findings to existing approach. Finally, to strengthen the outcome obtained through the proposed model, sensitivity analysis and time complexity analysis are performed.
Citation Count: Şahin, H.M...et al (2010). Analysis of exergy and energy of sugar production process in sugar plant. Jouurnal of the Energy Institute, 83(3), 178-185. http://dx.doi.org/ 10.1179/014426010X12759937396911
Analysis of exergy and energy of sugar production process in sugar plant
(Maney Publishing, 2010) Şahin, H.; Acır, Adem; Altunok, Taner; Baysal, E.; Koçyiğit, E.; 40424
In this paper, the energy and exergy analysis results of sugar production processes were presented by using operational system data from the Kayseri sugar plant, Turkey. All sugar production processes were thought as a steady state open thermodynamics system and employed the energy and exergy analyses, based on the first and second laws of thermodynamics. The best values of the energy and exergy efficiencies were obtained as 95.1% for the juice production process and 74.3% for the juice concentration process respectively. Moreover, the location of the energy degradation and the irreversibility were determined during the whole sugar production processes. Consequently, it has been pointed out that the energy and exergy efficiencies can be improved if the rates of the energy degradation and irreversibility in the sugar production processes are reduced
Citation Count: Altunok, T...et al (2010). Comparative analysis of multicriteria decision making methods for postgraduate student selection. Eğitim Araştırmaları-Eurosian Journal of Educational Research, 10(40), 1-15.
Comparative analysis of multicriteria decision making methods for postgraduate student selection
(Anı Yayıncılık, 2010) Altunok, Taner; Özpeynirci, Özgür; Kazançoğlu, Yiğit; Yılmaz, Recai; 44215; 55338
Problem Statement: The educational recourses available for postgraduate education are limited compared with the resources for undergraduate education. An academic advisor is required for each graduate student. The academic staff allocates an important portion of his/her time for graduate studies of his/her students. Since the number of academic staff is limited, the number of graduate students should be limited, too. While a large number of students may attend an undergraduate course, this may not be possible for some graduate courses, which are designed especially for small student groups. Hence, the selection of postgraduate students is an important problem. The postgraduate student selection problem can be defined as selecting a subset of students from the applicants for a postgraduate program. Naturally, this problem is a multi-criteria decision-making problem since each applicant has several attributes and these attributes should be considered simultaneously during the selection process. Purpose of Study: The purpose of this study is to compare the performance of different multi criteria decision-making methods developed for ranking alternatives for the postgraduate student selection problem. The best method will also be used in the student selection process for the Defense Sciences Institute of Turkish Military Academy. Methods: This paper discusses three multi-criteria decision making methods developed for ranking alternatives, namely Analytic Hierarchy Process (AHP), Weighted Product (WP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). A performance measure is defined and the performance values of the methods are compared using real data gathered from the graduates of Defense Sciences Institute of Turkish Military Academy for illustration purposes. Findings and Results: According to the findings, AHP is the best of the three competitors. The ranking obtained by AHP is quite similar to the ranking of students with respect to their cumulative grade point average (CGPA) after their graduation from the program. Conclusions and Recommendations: Considering graduate student selection problem as a multicriteria decision-making problem is very important and enables universities to enroll graduate students with important attributes and a variety of strengths. This paper compares the performance of different multicriteria decision-making methods on graduate student selection problem using a single performance measure. A further study can be making such a comparison with multiple performance measures
Citation Count: Şimşek, B., Şimşek, E.H., Altunok, T. (2013). Empirical and statistical modeling of heat loss from surface of a cement rotary kiln system. Journal of the Faculty of Engineering and Architecture of Gazi University, 28(1), 59-66.
Empirical and statistical modeling of heat loss from surface of a cement rotary kiln system
(Gazi University, Fac Engineering Architecture, 2013) Şimşek, Barış; Şimşek, Emir H.; Altunok, Taner; 220872; 8009
In branches of industry too much energy consuming such as cement sector, controlled use of energy, only it is possible to know how energy is distributed in the system. In cement production process, a large portion of the heat losses which is due to energy consumption consist of convection and radiation heat losses from the surface of rotary kiln. In this study, empirical equation was derived for heat loss from surface of rotary kiln in a cement factory using empirical equations and statistical modeling techniques by the help of temperatures measured surface of rotary kiln. Measured with thermal cameras and the data necessary for experimental modeling was obtained the factory central control room. Total heat loss of system was calculated using Matlab. Statistical analysis related to results was carried out by Minitab 15.1.1 program. It was concluded that heat losses throughout rotary kiln increased toward the center of the kiln.
Citation Count: Çalışkan, Sinan...et al (2011). "Numerical analysis of a commercial display cabinet with air curtain", Journal of the Faculty of Engineering and Architecture of Gazi University, Vol. 26, No. 2, pp. 415-425.
Numerical analysis of a commercial display cabinet with air curtain
(2011) Çalışkan, Sinan; Altunok, Taner; Başkaya, Şenol; Güngüneş, H. Murat
Maintaining food temperatures below critical values is the important maximising the high quality display life of chilled foods. Air curtains are especially used in stores and retailer supermarkets as barrier systems to seperate inner and outer spaces from each other. For both air quality and energy saving, it is crucial that the air transfer between these two spaces are at minimum. Minimization of air transfer between inner and outer spaces, not only decreases heat transfer but also stabilizes the humidity balance. In this study, numerical analysis of a commercial display cabinet has been carried out. For this purpose PHOENICS, a computational fluid dynamics code, is utilized. Optimum jet system conditions for each of the one jet, two jet and there jet systems has been modified according to temperature change of the air, and comparisons among them have been made. The results indicate that, the results the both CFD analysis and experimental results are almost equal and refrigeration systems with three jets is required to obtain the necessary temperature values to keep products fresh in display cabinets, especially because they can distribute temperature in a homogeneous way, meaning that the temperature value is the best ideal system at every point in the cabinet with three jets.
Citation Count: Acır, A., Altunok, T. (2010). Utilization of TRISO Fuel with LWR Spent Fuel in Fusion-Fission Hybrid Reactor System. Journal of Fusion Energy, 29(5), 436-442. http://dx.doi.org/ 10.1007/s10894-010-9301-3
Utilization of TRISO Fuel with LWR Spent Fuel in Fusion-Fission Hybrid Reactor System
(Springer, 2010) Acır, Adem; Altunok, Taner; 40424
HTRs use a high performance particulate TRISO fuel with ceramic multi-layer coatings due to the high burn up capability and very neutronic performance. TRISO fuel because of capable of high burn up and very neutronic performance is conducted in a D-T fusion driven hybrid reactor. In this study, TRISO fuels particles are imbedded body-centered cubic (BCC) in a graphite matrix with a volume fraction of 68%. The neutronic effect of TRISO coated LWR spent fuel in the fuel rod used hybrid reactor on the fuel performance has been investigated for Flibe, Flinabe and Li(20)Sn(80) coolants. The reactor operation time with the different first neutron wall loads is 24 months. Neutron transport calculations are evaluated by using XSDRNPM/SCALE 5 codes with 238 group cross section library. The effect of TRISO coated LWR spent fuel in the fuel rod used hybrid reactor on tritium breeding (TBR), energy multiplication (M), fissile fuel breeding, average burn up values are comparatively investigated. It is shown that the high burn up can be achieved with TRISO fuel in the hybrid reactor