http://www.rast.org.tr/JAST/index.php/JAST/issue/feed Journal of Aeronautics and Space Technologies 2018-08-02T05:43:14+00:00 Dr. Ömer ÇETİN ocetin@hho.edu.tr Open Journal Systems <p>Main objective of the Hezârfen Aeronautics and Space Technologies Institute is to contribute bringing up human power that is appropriate for the needs of developing science and technology, developing international knowledge, sophisticated, using scientific knowledge creatively and having secular and democratic values in addition to respecting nation benefit.</p> <p>The Journal of Aeronautics and Space Technologies is published as an international refereed journal that consists of scientific and academic knowledge in January and July biannually by Hezârfen Aeronautics and Space Technologies Institute.</p> http://www.rast.org.tr/JAST/index.php/JAST/article/view/291 AIR FUEL RATIO CONTROL USING DELAY RESISTANT CLOSED LOOP REFERENCE MODEL ADAPTIVE CONTROL 2018-07-19T13:19:04+00:00 Yildiray Yildiz yyildiz@bilkent.edu.tr <p><em>The focus of this paper is the air fuel ratio control of spark ignited engines. It is known that for an efficient removal of the pollutants from the exhaust gases, air fuel ratio has to be kept within a narrow band around the stoicometric ratio, which represents the condition where the air amount is perfectly matched with the fuel amount for a complete burn. The main challenges for this control problem are the inherent time delay of the system and uncertain dynamics. In this paper, employment of a high performance adaptive controller, which explicitly compensates for the delays without causing excessive oscillations, is proposed. The performance of this controller is demonstrated via simulation studies. To emphasize the importance of delay compensation, the controller is compared with the closed loop model reference adaptive controller, which do not have explicit delay compensation.</em></p> 2018-07-17T10:59:13+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/319 DESIGN AND MODELLING OF NANO AERIAL VEHICLE HUMMINGBIRD ON HOVER FLIGHT 2018-07-23T09:04:08+00:00 İbrahim Halil Güzelbey guzelbeyih@gantep.edu.tr Müslüm Özkesiciler ozkesicilermus@gmail.com Ahmet Şumnu ahmetsumnu@gantep.edu.tr <p><em>In nature, there are thousands of flapping insects and flying bird’s species. Each one has spectacular flight stability, dynamic and operated in high diversity of flight speed and mission. Each one has superior effectiveness and high efficiency. In this article, relates with designing and modelling for effective and efficient hummingbird mechanism design during hovering flight. This mechanism represents new and different concept for point of Nano aerial vehicle’s (NAV’s) mechanism design. Flapping wing tip path for hummingbird was generated from morphological experiment data’s. Slider crank mechanism designed to be an effective mechanism and same motion with path of hummingbird and analyzed on Simulink with driving crank hummingbird flapping frequency as 25 Hz. During hovering, forces were calculated. After that, structural components were designed in terms of consideration strengths and deflections. The system modelled on MATLAB using of Sim-mechanics Toolboxes.</em></p> 2018-07-17T11:02:48+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/308 A NUMERICAL MODEL FOR BALLISTIC IMPACT RESPONSE OF COMPOSITE ARMORS 2018-08-01T05:29:58+00:00 Demet Balkan kececidem@itu.edu.tr Seher EKEN seher.eken@omu.edu.tr <p><em>In this study, we present a numerical model to simulate the ballistic impact of a rigid right circular cylinder (RCC) projectile into a woven fabric target. The numerical solution of transverse ballistic impact on a laminar biaxial fabric is obtained using a forward finite-difference method. The ballistic impact analysis for different materials of targets made of aramid and polyethylene fibers are simulated to investigate the effect of fabric material on the ballistic resistance. Numerical simulations are performed to reveal the influences of crimp factor and fabric material on the ballistic performance of woven fabrics. Various cases have been presented showing the variations of yarn strains, yarn velocities, and yarn displacements over time. </em></p> 2018-07-17T11:06:54+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/321 FAULT INJECTION IN DYNAMIC PARTIAL RECONFIGURATION DESIGN BASED ON ESSENTIAL BITS 2018-07-23T09:11:07+00:00 Mohamed Elhady Magdy Keshk mo7amed_elhady@yahoo.com Kenichi Asami asami@mns.kyutech.ac.jp <p><em>SEU or soft error is an unintended change to the state of a configuration memory bit caused by ionizing radiation which causes unacceptable changes in the design behavior. In this paper, a fault injection and mitigation system, based on Xilinx essential bits technology, for partial and non-partial reconfiguration sections of kintex-7 xc7k325t FPGA using Xilinx SEM IP core and the dual use of ICAP primitive is described.&nbsp; Dynamic Partial Reconfiguration Design (DPRD) or the Design Under Test (DUT) is implemented on FPGA. A MATLAB program is used to inject errors into configuration memory during runtime by controlling SEM IP core, which implemented into FPGA, via UART interface between PC running MATLAB and FPGA board. This system reduces the time required to inject errors into FPGA configuration memory by injecting errors into the essential bits of configuration memory. In addition, the system describes the dual use of ICAP primitive to perform both partial reconfiguration and soft error mitigation processes. Results show the dual use ICAP primitive is performed successfully, and the time needed to perform soft error injection and mitigation process using essential bits is reduced by 96% comparing with the traditional methods.</em></p> 2018-07-17T11:12:16+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/307 DESIGN OF FRACTIONAL ORDER SLIDING MODE CONTROLLER FOR 2 DOF HELICOPTER SYSTEM 2018-08-02T05:43:14+00:00 Gurkan Kavuran gurkankavuran@gmail.com Celaleddin YEROGLU c.yeroglu@inonu.edu.tr <p><em>This paper presents a real time application for a prototype helicopter system by using sliding mode control strategy enhanced with small differential deviations. Experimental and simulation studies of the proposed controller demonstrate the control performance for a class of flight systems with unstable dynamics. It is shown that the controller decreases the steady state errors of the vertical and horizontal rotation of the system. Principally, small differential deviations successfully strengthen or weaken the effect of the differentiation to obtain better response in case of external disturbances. Numerical and experimental results are in agreement and confirm effectively tracking of desired rotor angles and suppression disturbances.</em></p> 2018-07-17T00:00:00+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/290 2D-STRAIGHT LINE PATH FOLLOWING AND NUMERICAL SIMULATION 2018-07-17T12:00:13+00:00 Zafer Öznalbant zoznalbant@anadolu.edu.tr Uğur Özdemir ugurozdemir@anadolu.edu.tr Mehmet Ş. Kavsaoğlu mskavsaoglu@anadolu.edu.tr <p><em>In this paper, a two-dimensional-straight-line path following methodology for an unmanned aircraft is developed. With the developed algorithm, the unmanned aerial vehicle is made to converge to a predefined path, and then to follow a virtual target on the path. A variable virtual target location is defined to get a smooth maneuver motion. The location of the virtual target is changed according to the magnitude of the cross track error which is the distance between the path and the aircraft itself. After defining the equations required for the calculation of the desired heading, the applied closed controller is explained. A numerical simulation model is created for the solution of equations of motion to investigate the outputs of the path following algorithm.&nbsp; The results of the algorithm and simulation are evaluated. </em></p> 2018-07-17T11:16:22+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/289 CFD ANALYSIS OF THE EFFECT OF PARABOLIC TAPER DISTRIBUTION OF AN UNTWISTED HELICOPTER ROTOR BLADE 2018-07-23T09:15:06+00:00 Munir Elfarra melfarra@ybu.edu.tr Mustafa Kaya mukaya@ybu.edu.tr <p><em>The effect of parabolic taper distribution along the span of a helicopter rotor blade is analyzed in terms of the rotor thrust, torque and Figure of Merit. Various maximum chord length values are investigated. The Reynolds Averaged Navier-Stokes computations are done using the FINE/Turbo flow solver developed by NUMECA International. The Spalart-Allmaras turbulence model is used to calculate the eddy viscosity. The baseline blade is selected as the Caradonna-Tung rotor blade. Different blade shapes were generated by setting the maximum chord length at different spanwise locations for the same planform area as the baseline blade. Three optimum cases are observed: maximum Figure of Merit, maximum thrust for the baseline Figure of Merit and maximum Figure of Merit for the baseline thrust.&nbsp; Those optimum cases are noticed when the maximum chord length is 1.3 times the baseline blade chord length.</em></p> 2018-07-17T11:18:22+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/327 A METHODOLOGY FOR THE ANALYSES OF UNSTEADY FLOWFIELDS AROUND FORWARD FLYING HELICOPTER ROTORS 2018-07-31T11:15:19+00:00 Murat Gecgel mrtgecgel@gmail.com Yavuz Nacaklı ynacakli@gmail.com <p><em>This study presents the outcomes of a series of computational fluid dynamics analyses conducted to obtain unsteady solutions of the flowfields around single rotor helicopter configurations. We use a methodology to obtain the time dependent solutions of the 3D, compressible Navier Stokes equations adapted for a rotating frame of reference. In order to carry out the simulations, the developed mathematical model is solved on hybrid meshes to optimally benefit the advantages of both the structured and the unstructured grids. For the entire flowfield calculations, one-equation Spalart-Allmaras turbulence model is employed. To decrease the computational time and memory requirements, parallel processing with distributed memory is utilized. We validate the developed model and the simulation methodology by comparing the results with the published experimental data. In the following phase of the study, the unsteady calculations of the flowfields around single, two bladed helicopter rotor configurations are conducted for hover and forward flight cases. As the forward flight speed increases, development of the dissymmetry of lift on advancing and retreating blades has been observed for six advance ratios. These time–accurate computations help to analyze the adverse effect of increasing forward flight speed in order especially to determine the never-exceed speed for single rotor helicopter configurations.</em></p> 2018-07-17T11:21:23+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/298 CONCEPTUAL FRAMEWORK FOR BUYER-SUPPLIER INTEGRATION STRATEGIES AND THEIR ASSOCIATION TO THE SUPPLIER SELECTION CRITERIA IN THE LIGHT OF SUSTAINABILITY 2018-07-23T09:18:08+00:00 Funda Seçkin ftan@hho.edu.tr Ceyda Güngör Şen cgungor@yildiz.edu.tr <p><em>In recent years, considering the evolution of consciousness about firms’ and their partners’ environmental and social responsibility, briefly sustainability, has become an important theme for enterprises. Henceforth, while evaluating the suppliers, not only economic performance, but also environmental and social dimensions of suppliers should be taken into account by the firms. On the other hand, firms often establish closer relationship with their suppliers in order to improve their competitiveness and to take advantage of complementary skills. In this paper, it is observed that too many integration strategies have been developed in the literature. However, to our knowledge, in almost all of these integration strategies, sustainability and association of strategy with supplier selection criteria have not been taken to the agenda. Therefore, the aim of this paper is twofold. First, we propose a classification for buyer-supplier integration strategies from buyers’ perspectives; second, we put effort to associate integration strategies with supplier selection criteria. An existing fuzzy weightened method is shown for determining whether criterion is important or not for a specific integration level. An actual evaluation is performed in Turkish Electrical and Electronics Industry to guide firms about how they decide selection criteria according to integration level.</em></p> 2018-07-17T11:23:21+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/335 DESIGNING A NEURAL NETWORK MODEL USING K-MEANS CLUSTERING FOR RISK ANALYSIS OF LUNG CANCER DISEASE 2018-07-23T09:22:44+00:00 Umut Kaya umut.kaya@kavram.edu.tr Atınç Yılmaz atincyilmaz@beykent.edu.tr Ediz Şaykol edizsaykol@beykent.edu.tr <p><em>According to the World Health Organization report in 2004, lung cancer belongs to highest mortality rate cancer type compared to others. Genetics and early starting smoke etc. become the basis for lung cancer risk. In recent years, lung cancer cases are increasing with the use of cigarettes at younger ages. One of the most important factor in the treatment of the disease is early diagnosis. Artificial intelligence methods, which have been used in many areas in recent years, are also used for early diagnosis and imaging of diseases. In this study, a hybrid artificial neural network (ANN) model was designed to bring a different perspective to the use of multilayer ANN in the literature for lung cancer risk prediction. Lung cancer risk factors were used as input data in predicting the disease. We tried to estimate the results using clustered data by K-means clustering algorithm and multi-layered ANN method. When the results obtained from the normalized and clustered data set are compared with the results in the literature, the proposed model has a higher accuracy value than the other methods. </em></p> 2018-07-17T11:24:45+00:00 ##submission.copyrightStatement## http://www.rast.org.tr/JAST/index.php/JAST/article/view/326 ANALYSING UML-BASED SOFTWARE MODELLING LANGUAGES 2018-07-19T13:10:44+00:00 Mert Ozkaya ozkaya.mert.1@gmail.com <p><em>UML is considered as the top popular software modelling language among practitioners. Expectedly, UML has been extended by many other languages, which tailor UML for particular domains (e.g., distributed systems, mobile systems, and embedded systems). In this paper, the existing 20 different UML-based software modelling languages have been analysed for a number of requirements that are believed to be highly important for practitioners who perform software modelling in different industries. These requirements are formal semantics, multiple viewpoints modelling, model analysis, code-generation, and modelling toolset.&nbsp; According to the analysis results, none of the existing UML-based languages support all those requirements – except UWE proposed for web applications. The model analysis is essentially enabled by those languages whose formal semantics are defined in terms of the translations into some formal verification languages that are supported with exhaustive model checkers. Moreover, code-generation for automatically transforming models into executable software is ignored by most of the languages. Lastly, the modelling tool support is ignored too, which is essentially because many languages offer UML profiles that can be used with the existing UML modelling tools.</em></p> 2018-07-17T11:27:25+00:00 ##submission.copyrightStatement##