Journal of Aeronautics and Space Technologies http://www.jast.hho.edu.tr/index.php/JAST <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> <p>The authors cannot make any payment for the papers published in the journal. Papers published in the journal are open access without being a member of the journal.</p> en-US <p>The manuscript with title and authors is being submitted for publication in Journal of Aeronautics and Space Technologies. This article or a major portion of it was not published, not accepted and not submitted for publication elsewhere. If accepted for publication, I hereby grant the unlimited and all copyright privileges to Journal of Aeronautics and Space Technologies.<br><br>I declare that I am the responsible writer on behalf of all authors.&nbsp;</p> <p>&nbsp;</p> ocetin@hho.edu.tr (Asst.Prof. Ömer ÇETİN) oalparslan@hho.edu.tr (Önder ALPARSLAN) Tue, 28 Jul 2020 19:07:15 +0000 OJS 3.1.1.4 http://blogs.law.harvard.edu/tech/rss 60 Performance Characteristics of Turkey’s First 1,5 kW Hall Thruster Electric Propulsion System http://www.jast.hho.edu.tr/index.php/JAST/article/view/385 <p>Due to significant advantages and successful applications, electric propulsion has become a key technology for both scientific and commercial space missions. Nowadays, almost every satellite is equipped with an electrical propulsion subsystem for the purposes of orbit transfer, orbit correction, collision avoidance, and performing stating-keeping maneuvers. Considering these advances in space propulsion technology, TUBITAK UZAY initiated a project to establish an electric propulsion test facility and develop a Hall thruster propulsion system (HALE Project). The project was started in 2010 and completed by the end of 2018. In the scope of the project, Turkey’s first qualification test model electric propulsion system has been developed in Turkey’s very first electric propulsion laboratory. The facility has all necessary equipment to test Hall Thruster systems up to 5kW power. The developed system is optimized to be used at 1350 W providing 80 mN thrust and 1500 s specific with 45% efficiency. In this paper, all project activities are summarized and outcomes are presented.</p> Demet Uluşen, Banu Çiçek Aydın, Yusuf Yurttaş, Barış Çal, Andrii Tsybulnyk, Sergii Neugodnikov, Oleksii Cherkun, Seda Kayra Güllü ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/385 Tue, 28 Jul 2020 15:48:03 +0000 The General-Purpose Modeling, Analysis, and Implementation of Software Architectures http://www.jast.hho.edu.tr/index.php/JAST/article/view/416 <p>In this paper, a new software modeling language called SAMP is proposed, which is inspired from UML and enables the general-purpose modeling of software architectures but at the same time promotes the multiple-viewpoints modeling, formal verification of the models for the desired requirements, and combination of model and code together. SAMP supports the high-level modeling of software architectures from the requirements, logical, behaviour, and deployment perspectives and supports checking the consistencies between the software models in different perspectives. SAMP is also supported with a modeling toolset that allows for the visual modeling of software architectures in those perspectives. The toolset further generates formal ProMeLa models that can be accepted by the SPIN model checker for the exhaustive verification of the software behaviours against the user-defined properties and some pre-defined properties (e.g., deadlock, race-condition, wrong and incomplete pre-conditions). Moreover, the toolset can also generate the Java Modeling Language (JML) code that combines the contractual models with the Java program for ensuring the consistency between model and code throughout the software development.</p> Mert Özkaya ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/416 Tue, 28 Jul 2020 00:00:00 +0000 Robust Hyperspectral Feature Extraction Method Using Edge Preserving Filters and Intrinsic Image Decomposition http://www.jast.hho.edu.tr/index.php/JAST/article/view/413 <p>Spectral-spatial feature extraction methods present an effective way for classification of hyperspectral images. However, performances of these methods may decrease depending on different data sets, classifier type, number of training samples, noise and smoothness level of data sets. In this paper, these terms are called as robustness criteria. This paper first discusses the effects of each robustness criteria for the feature extraction methods in the state-of-the-art. Secondly, a robust feature extraction method that can solve aforementioned problems is proposed for hyperspectral image classification. The proposed method first performs dimensionality reduction and then extracts features using multiple edge preserving filters and intrinsic image decomposition method. Each robustness criteria is thoroughly examined in experiments and the results are compared with the state-of-the-art feature extraction methods. Experimental results demonstrate that the proposed method not only achieves better classification accuracies for different classifiers at lower training samples but also presents robust performance on different data sets that includes noise and smoothness effects.</p> Ali Can Karaca ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/413 Tue, 28 Jul 2020 16:16:06 +0000 Numerical Investigation of Propeller - Frame Arm Interaction in Hovering Flight http://www.jast.hho.edu.tr/index.php/JAST/article/view/422 <p>This study explores the interaction between a propeller and various frame arm geometries, which are typically used in multi-rotor applications. The influence of the arm on the propulsive performance of the propeller is investigated by using commercial computational fluid dynamics (CFD) solver ANSYS Fluent 17 in hovering flight. CFD results are validated for hover and vertical climb conditions with thrust and torque measurements conducted on a 16x4 carbon fiber propeller. Four different arm geometries (i.e., an Eppler arm, a cylindrical tube, a square tube, and a slotted square tube) are studied to investigate their effect on the propulsive performance of the propeller and the complete propeller-arm configuration. Regardless of the geometry, the arm enhances the thrust generation of the propeller for all propeller-arm distances considered in this study.&nbsp; However, the total thrust of the propeller-arm configuration is smaller than the single propeller case due to drag exerting on the arm. In this respect, the Eppler arm configuration has the best performance in terms of the total force generation due to relatively low drag of the Eppler profile. The square arm configuration yields the highest thrust generation and propulsive efficiency for the propeller despite having the lowest total force generation.</p> Serkan Yener, Mustafa Perçin ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/422 Tue, 28 Jul 2020 16:33:27 +0000 Three-Dimensional Formation Flight with Generalized Explicit Guidance http://www.jast.hho.edu.tr/index.php/JAST/article/view/423 <table style="height: 144px;" width="855"> <tbody> <tr> <td width="381"> <p>In this study, a three-dimensional formation flight guidance approach is developed. The proposed method has three aspects to be considered: the formation geometry, the virtual leader, and the tail-chase engagement. Upon deciding on the formation geometry, virtual leaders that are rigidly attached to the leader are generated accordingly. Afterwards, the virtual leaders are pursued in tail-chase fashion by the followers. The trajectory tracking of the virtual leaders is accomplished by the so-called generalized vector explicit guidance, which controls the three-dimensional acceleration vector of the followers. The arrowhead formation with one leader and four followers is simulated and the performance is discussed.</p> <p>&nbsp;</p> </td> </tr> </tbody> </table> Koray Erer, Raziye Tekin ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/423 Tue, 28 Jul 2020 16:39:02 +0000 Aerodynamic Performance Losses due to Ice Formation on the UAV’s Wings http://www.jast.hho.edu.tr/index.php/JAST/article/view/424 <p><span lang="EN-US">Ice accretion on the UAV’s wing profile modifies the initial airfoil contour and changes the aerodynamic characteristic of the wing. The aim of this research is to calculate performance losses on a wing due to the accretion of rime ice. The computations are based on the </span><span lang="EN-US">Lifting line method</span><span lang="EN-US"> in order to predict the aerodynamic performance of both iced and clean wings for different aspect ratios. Currently, ice formation on NREL S826 airfoil is predicted by using ice accretion tool and computed aerodynamic loads compared with clean and iced wing profiles for different aspect ratios. It is seen that predicted aerodynamic performance loss is higher for small aspect ratio than that of the bigger for the rime ice.</span></p> <p>&nbsp;</p> Durmuş Sinan Körpe, Özcan Yırtıcı, Serkan Özgen ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/424 Tue, 28 Jul 2020 16:51:05 +0000 Clutter Learning Based LS Method for Buried Target Detection in GPR Images http://www.jast.hho.edu.tr/index.php/JAST/article/view/426 <p>A regularized version of the least squares (LS) target detection method is combined with the subspace-based clutter learning for buried target detection in ground penetrating radar (GPR) images. The LS method is used to estimate the next A-scans from previously observed A-scans which are assumed to belong to the clutter component. Generally, A-scans used in the initial stage are accepted as target-free for the LS to work correctly. However, this is not guaranteed and if the first observed A-scan samples contain any target information, LS method will fail. In this paper, the clutter information is retrieved via robust principal component analysis (RPCA) as a preprocessing stage and used in the LS estimation of the actual A-scan. Thus for A-scans containing target information LS method will provide an increase in the estimation error indicating target presence at this location. Moreover, due to the regularization, the proposed method is more robust to noise caused by the irregularities of the soil.</p> Deniz Kumlu, Işın Erer ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/426 Tue, 28 Jul 2020 16:58:21 +0000 Customer Segmentation Based on Self-Organizing Maps: A Case Study on Airline Passengers http://www.jast.hho.edu.tr/index.php/JAST/article/view/430 <p>Customer segmentation is a customer grouping model based on common features and it directly relates with customer satisfaction of the companies. It provides access to the right customer with the right methods by knowing the customer better. Dealing with changes in a competitive market means airlines have to redefine customer segmentations, which translates from social-demography to a more complex behavioral approach that covers the entire travel experience and the way airlines deliver at every touch point. In this paper, a customer segmentation was performed using an airline ticket sales data. Customers with similar sales tendencies were clustered by using self- organizing map method and totally 15 clusters were obtained.</p> İlkay YELMEN, Serpil ÜSTEBAY, Metin ZONTUL ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/430 Tue, 28 Jul 2020 17:46:56 +0000 Nano and Micro satellites as the Pillar of the “New Space” Paradigm http://www.jast.hho.edu.tr/index.php/JAST/article/view/420 <p>Six decades after the launch of the first satellite in 1957, space business and space technologies are taking a new turn: From big to small, from primarily government to extensively private sector and from a few players to profusely many. The new paradigm, or “New Space”, as it has been called, can be characterized by new startups with venture capital backing entering the field or in fact leading the field in new innovative applications, universities and countries with no previous space experience joining the bandwagon, lean design and development techniques benefitting from the newly available COTS parts and subsystems, mass production of satellites, constellations of hundreds or thousands of small satellites serving old and new emerging niche needs, small launchers available for reaching orbit at low cost and rather short notice, capability to launch a rocket several times a month, and more exotic applications such as the coming space tourism and asteroid mining. Although there were initiatives in this direction in the previous century, they proved too feeble to set a trend. “New Space” started showing its first signs of emergence after the turn of the millennium, but the market acceptance has really taken root in the last 3 or 4 years. Market data clearly shows an accelerated pace shaping the future of space industry. This paper reviews the developments in the nano and micro satellites considering them as the pillar of the New Space paradigm. The road leading to the present state and the current trends are elaborated. A look to the future points to the proliferation of space applications among the many startups, big and small institutions, but being limited by market forces and survival by a few as the decade proceeds.</p> Fuat İnce ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 http://www.jast.hho.edu.tr/index.php/JAST/article/view/420 Tue, 28 Jul 2020 17:45:48 +0000