WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Modeling and Analysis of a Microfluidic Capillary Valve(Gazi Univ, 2017) Yildirim, EnderHere, a numerical model for analysis of a capillary valve for use in microfluidic devices was presented. Capillary valves are preferred especially in passive microfluidic systems, where the capillary forces dominate the liquid motion, to manipulate the flow. The capillary valve in this work, was formed by the sudden expansion of a rectangular microchannel to an opening, whose depth and width are larger than the height and the width of the channel respectively. Noting that there was no available analytical model to determine the pressure capacity of such valves, a numerical model based on energy minimization was utilized. Free software Surface Evolver was used to solve the model. Dependence of the pressure capacity on the contact angle of the working liquid on the channel material was investigated. It was found that the pressure capacity of the valves would be maximum if the contact angle on all surfaces is 90 degrees. Accordingly, the valves could withstand approximately 2.5 kPa for 100 mu m x 100 mu m channels when the contact angle was 90 degrees. The model was verified by comparing the results with those available in the literature.Article Laminar Forced Convection Over An Inclined Flat Plate With Unheated Starting Length(Gazi Univ, 2019) Turgut, Oguz; Ozcan, Ahmet Cem; Turkoglu, HasmetTwo-dimensional laminar forced convection over an inclined flat plate with an unheated starting length was investigated numerically for both constant surface temperature and constant heat flux boundary conditions. The numerical study was implemented using the commercial software ANSYS Fluent 15.0. Air is used as working fluid. The influence of Reynolds number, inclination angle and the length of unheated plate on velocity and temperature distributions, surface temperature, surface heat flux and local Nusselt number was investigated. The results show that Reynolds number, inclination angle and the length of unheated region of plate play important role on heat transfer from the plate. It is seen that Nusselt number increases with increasing Reynolds number and inclination angle of inclined flat plate but decreases with increasing the length of unheated region of plate.Article Importance of Zoning for Vertical Circulation Planning of Densely Populated Buildings: A Simulation Based Approach for Elevator Traffic Analyses(Gazi Univ, 2025) Deligoz, Dostcan; Harputlugil, TimucinElevator systems are essential in multi-story buildings, affecting circulation, travel time, and user comfort. Traditional design methods, based on mathematical calculations, provide initial estimates of elevator numbers and capacities by considering basic operational criteria. However, these methods cannot fully capture dynamic passenger flows and temporal variations in demand. Dynamic simulation-based elevator traffic analysis, on the other hand, allows for more comprehensive evaluation of elevator operations and enables testing of alternative zoning scenarios. In this study, a dynamic simulation-based analysis is applied as a case study for a hospital outpatient building. Different zoning strategies are implemented for elevator groups to evaluate their effect on system performance. Performance criteria, including Average Waiting Time (AWT), Average Time To Destination (ATTD), and Interval (INT), are assessed across different zoning scenarios and compared with values commonly reported in the literature. The results highlight the potential of zoning to improve elevator performance, including passenger handling, waiting times, and travel efficiency. Especially in buildings where physical modifications are difficult, the combination of simulation-based analysis and carefully designed zoning strategies can reveal the potential for enhancing operational performance and optimizing elevator efficiency within existing physical constraints.Article W-Band RCS Prediction of Small Objects: Comparing Two Widely Used Methods with Experimental Validation(Gazi Univ, 2025) Kara, Ali; Aydın, Elif; Yardım, Funda Ergün; Sezgin, Deniz; Ergun Yardim, FundaThis paper compares the accuracy of Shooting and Bouncing Rays and Electric Field Integral Equation methods for Radar Cross Section prediction of small objects at 77-81 GHz band. Existing studies on RCS prediction methods often lack comprehensive comparisons between computational and experimental results, particularly for small objects measured with a 77 GHz radar. This study addresses this gap by presenting an in-depth analysis of both simulation and measurement data. In this work, three targets with varying geometries and materials were measured with a frequency modulated continuous wave radar and simulated using Ansys HFSS and CST Studio Suite. The measurements were performed with a commercial off-the-shelf (COTS) frequency modulated continuous wave radar operating at 77-81 GHz. This study aims to emphasize the importance of considering both efficiency and accuracy when opting for an RCS prediction method. Overall, the outcomes of both methods have largely demonstrated good alignment. It has been noted that, while Shooting and Bouncing Rays method offers promising time-saving advantages, Electric Field Integral Equation method remains a valuable tool for complex geometries where precise results are crucial.Article Citation - WoS: 3Completion of Tvs-Cone Metric Spaces and Some Fixed Point Theorems(Gazi Univ, 2011) Abdeljawad, Thabet; Abdeljawad, Thabet; MatematikIn this paper a completion theorem for cone metric spaces and a completion theorem for cone normed space over a complete locally convex topological vector space E are proved. The completion spaces are defined by means of an equivalence relation obtained by convergence via the topology of the locally convex space E. Very recently some fixed point theorems obtained in cone Banach spaces are generalized to locally convex cone Banach spaces. These theorems can not be generalized or proved trivially by using the nonlinear scalarization function used very recently by Wei-Shih Du in " A note on cone metric fixed point theory and its equivalence, Nonlinear Analysis Theory Methods and Applications 72 (5):2259-2261 (2010)".Article A Novel Hypercube-Based Approach To Overlay Design Algorithms on Topic Distribution Networks(Gazi Univ, 2022) Yumusak, Semih; Hassanpour, Reza; Layazali, Sina; Oztoprak, Kasim; Hassanpour, Reza; Yazılım MühendisliğiData communication in peer-to-peer (P2P) network requires a fine-grained optimization for memory and processing to lower the total energy consumption. When the concept of Publish/subscribe (Pub/Sub) systems were used as a communication tool in a P2P network, the network required additional optimization algorithms to reduce the complexity. The major difficulty for such networks was creating an overlay design algorithm (ODA) to define the communication patterns. Although some ODAs may perform worse on a high-scale, some may have better average/maximum node degrees. Based on the experimentation and previous works, this study designed an algorithm called the Hypercube-ODA, which reduces the average/maximum node degree for a topic connected Pub/Sub network. The Hypercube-ODA algorithm creates the overlay network by creating random cubes within the network and arranging the nodes with the cubes they belong to. In this paper, the details of the proposed Hypercube algorithm were presented and its performance was compared with the existing ODAs. Results from the experiments indicate that the proposed method outperforms other ODA methods in terms of lower average node degree (lowering the average node degree by up to 60%).Article Citation - WoS: 4Citation - Scopus: 5Architect - Structural Engineer Collaboration in Sustainable Structural System Design(Gazi Univ, 2011) Ozmen, Cengiz; Özmen, Cengiz; Unay, Ali Ihsan; MimarlıkThis paper explores ways of collaboration between architects and structural engineers in the design of sustainable structural systems. Areas of collaboration are explored in terms of seismic design of new structures and rehabilitation of existing structures. Multidisciplinary design teams and an integrated design approach are critical to the process of sustainable building construction. The required group-work skills should be acquired by architects and engineers during their professional education. As a result, this paper also investigates ways in which the structural design education of architects and structural engineers can be redesigned to make their future professional collaboration more harmonious.Article Citation - WoS: 1Citation - Scopus: 1Structures and Energetics of Cu21-Cu71 Clusters: a Molecular Dynamics Study(Gazi Univ, 2009) Güvenç, Ziya Burhanettin; Cetin, Saime Sebnem; Ozcelik, Suleyman; Guvenc, Ziya B.; Bilgisayar MühendisliğiUsing Molecular Dynamics and thermal quenching simulations the stable geometrical structures and energies of Cun (n=21-71) clusters are identified. The interaction between the cluster atoms is modeled by an EmbeddedAtom Potential Surface, Voter and Chen's version. The stable geometrical structures and energies are obtained from 500 phase space coordinates generated along high-energy trajectories. The internal energy (about T=2500 K) is above the melting temperature of the Cun clusters. The thermal quenching technique is employed to remove slowly the internal kinetic energy of the clusters. Because of this slow minimization process the locally stable isomers are separated from those meta-stable ones.Article Citation - WoS: 16Citation - Scopus: 16A Gap in the Paper "a Note on Cone Metric Fixed Point Theory and Its Equivalence" [Nonlinear Anal. 72(5), (2010), 2259-2261](Gazi Univ, 2011) Abdeljawad, Thabet; Karapinar, ErdalThere is a gap in Theorem 2.2 of the paper of Du [1]. In this paper, we shall state the gap and repair it.Article Citation - WoS: 2Citation - Scopus: 1A Simple Selection Method of PV Systems for University Campuses(Gazi Univ, 2023) Harputlugil, Gülsu Ulukavak; Bara, Marıam; Ulukavak Harputlugil, GulsuThis paper briefly outlines part of the research work being carried out on the application of the photovoltaic systems to cover universities’ electrical energy needs, with due consideration to the technical, architectural, economic, social. and legal aspects and impacts of this application. The paper considers optimizing the PV system selection objectives and methodology with a case study application. at a university campus in Ankara, Turkey. The main objective here is to develop a practical simple method of selecting an optimum PV system that gives the maximum energy yield possible in a certain period of one year, with the minimum specific energy cost per kWh, where a multiple-variable multi-criteria decision-making making method is applied, to help designers and system engineers in selecting the optimum system. The developed method is demonstrated in the example of the typical case, where the recommended PV system was turned out to be at an Azmuth angle of 0 degrees, the PV technology was monocrystelline Silicon, the annual electrical energy yield per 100 m2 of PV modules surface area 22.4 MWH/Year, the specific electrical energy cost was 0.15 Euos/Kwh, as a first merit option, making a difference of around 13% of saving compared with the 10th last option. The work concludes that a viable PV application is feasible, encouraging its application in various campuses provided that comprehensive planning and careful considerations are given to the related aspects.