Journal of Aeronautics and Space Technologies http://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> Milli Savunma Üniversitesi, Hezârfen Havacılık ve Uzay Teknolojileri Enstitüsü en-US Journal of Aeronautics and Space Technologies 1304-0448 <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> Optimization of a Nano-Satellite Communication System Through a Software Defined Radio (SDR) Platform Implementation http://jast.hho.edu.tr/index.php/JAST/article/view/379 <p>In small satellite communications systems, Software Defined Radios (SDR) have been used for increase the system flexibilization both in the space segment and on the ground station implementations. In this paper, an SDR implementation for the space segment is proposed in order to optimize the communication system designed for the Low Earth Orbit (LEO) environment observation satellite (Ten-Koh). This optimization consists in the integration of a Raspberry PI module and a LimeSDR-mini RF module using embedded Linux, Python and GNU radio tools. The Ten-Koh mission, communication system architecture, on-orbit mission constraints and issues will be described in order to be compared with the proposed optimization to demonstrate the improvements in terms of performance, flexibility and developing time. The purpose is to demonstrate that the proposed system can be replaced safely in future satellite missions similar to Ten-Koh meeting the mission requirements.</p> Rafael Armando Rodriguez Leon Kenichi Asami Kei-Ichi Okuyama ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 1 16 The Analysis of Hot-Air Balloon Accidents by Human Factor Analysis and Classification System http://jast.hho.edu.tr/index.php/JAST/article/view/391 <p>Although hot-air balloon accidents are infrequent with respect to the total number of flights, the rate of hot-air balloon accidents has shown a significant increase over the past two decades. The aim of this study is to classify previously identified causal factors of hot-air balloon accidents. 103 NTSB (National Transportation Safety Board) accident reports were analyzed, and causal factors of hot-air balloon accidents were classified by using HFACS (Human Factors Analyzing and Classification System) as a framework. The relative importance of contributing factors to hot-air balloon accidents was established. We found that environmental factors were the most important contributing factors, following skill-based errors as the second-highest contributing factors. Our results will contribute to countermeasures to prevent future reoccurrences of the hot air balloon accidents and incidents and may provide an insight into high-risk factors which are associated with the severity of the balloon crashes.</p> Bilal Kılıç ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 17 24 Magnetic Cleanliness Program on CubeSats and Nanosatellites for Improved Attitude Stability http://jast.hho.edu.tr/index.php/JAST/article/view/387 <p>CubeSats are being increasingly specified and utilized for demanding astronomical and Earth observation missions where precise pointing and stability are critical requirements. Such precision is difficult to achieve in the case of CubeSats, mainly because of their small moment of inertia, this means that even small disturbance torques, such as those due to a residual magnetic moment are an issue and have a significant effect on the attitude of nanosatellites, when a high degree of stability is required. Also, hardware limitations in terms of power, weight and size, make the task more challenging. Recently, a PhD research program has been undertaken at the University of Surrey, to investigate the magnetic characteristics of CubeSats, it has been found that the disturbances may be mitigated by good engineering practice, in terms of reducing the use of permeable materials and minimizing current-loop area. This paper discusses the dominant source nanosatellites disturbances and presents a survey and a short description of magnetic cleanliness techniques to minimize the effect of the residual magnetic field. It is mainly intended to supply a guide for CubeSat community to design future CubeSats with improved attitude stability. We present then our findings to date of a new technique of the residual magnetic dipole determination for CubeSats and Nanosatellites. This method is performed by implementing a network of eight miniature 3-axis magnetometers on the spacecraft. These are used to determine the strength, the direction and the center of the magnetic dipole of the spacecraft dynamically in-orbit and in real-time. This technique will contribute to reduce the effect of magnetic disturbances and improve the stability of CubeSats. A software model and a hardware prototype using eight magnetometers controlled via a Raspberry-Pi were developed and successfully tested with the boom payload of the Alsat-1N CubeSat and a magnetic air coil developed for validation purposes.</p> Abdelmadjid Lassakeur Craig Underwood Benjamin Taylor Richard Duke ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 25 41 A Conceptual Design Synthesis for the Model Satellite http://jast.hho.edu.tr/index.php/JAST/article/view/393 <p>The annually organised Türksat Satellite Model Competition gives undergraduate and graduate students, who are students of engineering, the opportunity to transform theoretical knowledge into practice and to share interdisciplinary work and experience. Bulent Ecevit University participated in the Türksat Satellite Model Competition 2019 [1] with B-Dispate Black Diamond Space Team. The team is based on undergraduate students, which consist of multidisciplinary engineering departments collaborating with the professional guidance and supervision from academia. The main goal of the team is to send the telemetry information (pressure, height, battery level, photograph and video recording, equipment opening, load carrying, ability to send location upon landing, attitude information, etc.) collected from the sensor equipment on board attached to the model satellite, to the ground station during the flight stage. Also, the team will have to fulfil particular tasks designated by the competition board. A comprehensive conceptual model satellite synthesis is reported in this paper. It is shown how the model satellite design should be driven, allowing significant savings in terms of qualification tests, and giving way to a procedure to design and manufacture a low-cost educational microsatellite.</p> Caglar Uyulan Samet Kolcu Taha Gül Ertan Abakay Eren Delen Kerem Demir Ömer Numan Özdemir ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 43 56 Systematic Reviews in Model-Driven Engineering: A Tertiary study http://jast.hho.edu.tr/index.php/JAST/article/view/399 <p>To cope with growing complexity of software-intensive systems, model-driven engineering (MDE) has become a widely used approach in the industry by providing many (potential) benefits with different purposes. Although there has been an increasing interest in conducting secondary studies among MDE researchers such as surveys, systematic mapping (SM) and systematic literature review (SLR), there have been no tertiary study to synthesize the findings from all these existing secondary studies, which also examines various characteristics of software modeling (e.g., purposes, benefits and challenges) as a meta-analysis. In order to investigate and understand the state-of-the-practices in MDE based on the modeling characteristics, we collected the set of all the existing 64 secondary studies in this field. By being a tertiary study, (i.e., a systematic review of systematic reviews), this article presents inputs for modeling stakeholders to better understand and use different purposes, benefits, and challenges of MDE by aggregating consolidated findings on this approach.</p> Deniz Akdur Onur Demirörs ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 57 68 Plasma Thruster with Diffusion Control Using Real-Time Simulations with Observer Structure and Ionising Radiation Caused by Electrodynamic Effects in the Accelerator Chamber http://jast.hho.edu.tr/index.php/JAST/article/view/404 <p>The script in this paper describes the use of propellant for plasma thrusters based on electrostatic accelerator. The generation and control of plasma is essential for the ion thrusters. The effects of generated plasma may be used for simulation with heavy ions also. Since of used neutralisation by most types the ion current with the electron current unites to one neutral mass current with very high speeds. The types of achieved energies about 10 keV by first ionisation are state of the art and about 15 keV of second ionisation are rare types also. The cathode has to be able to withstand this energy permanently because some of the ions hit with its grid. The beam of them differs from typical alpha radiation. The ionisation chamber with the accelerator generate high speed of the ions, which produce the ionising and electromagnetic radiation due acceleration. This process may be used for the radiation tests also.</p> <p>With the proposed model it is possible to calculate the spatial distribution of the electromagnetic fields as well the spatial temperature distribution in real-time. For this purpose are radiation hardened electronic systems with microcontroller, operational amplifiers and FPGA required for control with an observer structure working with parallel real-time simulation based on state-space representation with an additional model for diffusion effects. With an observer system, the disturbances may be determined. This provides the estimation of the more precise systems states for the control and additionally the estimation of the disturbances that arise due to radiation effects.</p> <p>The results have also shown that an observer system can be developed specifically for the real-time calculation of the radiation effects only. The possibilities are related to all discrete solutions of differential equation systems, linear time invariant, the partial differential equations and the high performance digital mathematic operations. The paper gives also an overview of the diffusion effects and their mechanisms. The consideration is made by proposed extension of the of the Fick's laws and Maxwell equations; the introduction of new vector sizes is performed also. The analytical results were good enough for calculation of fields with diffusion. Using the advanced control method of thrust, a control structure for the electric test system could be created.</p> Alexander Norbach ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 69 80 Evaluation of Object-Based Water Body Extraction Approaches Using Landsat-8 Imagery http://jast.hho.edu.tr/index.php/JAST/article/view/396 <p>Water body extraction plays a key role in water resource management and development which is one of the key issues in research topics related to remote sensing in recent decades. Pixel-based; supervised and unsupervised classification methods and water indices have been developed for extracting water body from satellite imagery while for some cases they are unable to differentiate water body from low albedo features with different spectral characteristics. The object of this paper is to evaluate the efficiency of object-based, pixel-based and water indices for water body extraction. Landsat-8 imagery used for this study which has 30m resolution in Visible, NIR (Near-Infrared), SWIR (Shortwave Infrared) spectrum and panchromatic band with 15m resolution. The Edge-Based Segmentation (EBS) algorithm and the Support Vector Machine (SVM) classification method has been used for object-based approach, on the other hand, Maximum Likelihood and K-means methods has been selected for pixel-based classification. As a water index, Normalized Difference Water Index (NDWI) has been selected to extract water body from satellite imagery. The study area selected in both urban and mountainous regions, with different characteristics, which located in Turkey. Results show that object-based water body extraction is more accurate than the other methods tested.</p> Hamed Hafizi Kaan Kalkan ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 81 89 Airlines Employees Service Quality Perception of the Ground Handling Management http://jast.hho.edu.tr/index.php/JAST/article/view/410 <p>Ground handling companies are enterprises in which airline companies have to cooperate intensively while producing services. Ground handling companies, offer a variety of services for airline’s planes, employees and passengers. Airline services and ground handling services have different service quality perceptions since the ground handling services companies operate in the industrial markets. In the airline industry, studies in which the quality of the services offered by the ground handling services company is assessed by the airline's employees are limited In this study, measurement of the service quality perception of airline employees who benefit from the ground handling services (cockpit and cabin crews, ground operations employees, etc.) of the ground handling services and measurement of the impact of the service quality perception on customer’s satisfaction and customer’s loyalty are aimed. SERVPERF service quality measurement questions have been utilized. These questions have been restructured according to the services given by the ground handling company. The survey questions prepared have beeen replied by 248 airline employees. The perception of service quality of airline employees towards ground handling services was measured. The effect of service quality dimensions on customer satisfaction and customer loyalty attitudes of airline employees was examined. The results show that there is a significant difference between perception of service quality dimensions of airline employees and service quality physical appearance-reliability and empathy dimensions and customer satisfaction. The dimensions of service quality, assurance, empathy and responsiveness have an impact on customer loyalty.</p> Emre Bahar ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 91 105 Competitive Profiling to Evaluate Airline Hub Connectivity http://jast.hho.edu.tr/index.php/JAST/article/view/411 <p>Hub connectivity, measuring accessibility of an airline hub, is a performance indicator for airlines with hub-and-spoke network. This research develops a new methodology to calculate hub connectivity and to do strategic comparative analysis for airline hubs. The study utilizes a strategic management tool, competitive profiling matrix to design a measure which is a result of evaluation of various important dimensions enabling a competitive profiling revealing relative strengths and weaknesses of hubs. The methodology combines a wide range of critical success factors representing key components to achieve a level of excellence in terms of hub connectivity. By profiling method, this research evaluates weaknesses and strengths from different dimensions, calculates an overall weighted connectivity as well as overall efficiency producing the overall competitiveness. There are various literature providing methodology to evaluate hub connectivity of airlines. However, this research develops a unique perspective with the application of strategic profiling method and with a wide range of structural and practical factors considered. Methodology is demonstrated with computational experiments as well as a sensitivity analysis to validate the results and overcome the quantitative side of the approach.</p> Zeliha Akça ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 107 119 A Broadband High Gain Antenna with Parasitic Elements for Wireless Applications http://jast.hho.edu.tr/index.php/JAST/article/view/405 <p>Wireless devices and mobile communication are very popular and commonly used nowadays. Antennas allow data transfer between wireless devices without using cable. Researchers always try to improve some technical characteristics of antennas such as antenna gain, bandwidth, radiation pattern. High gain and wideband patch antenna is used for UMTS band in this study. In the designed antenna, air is used instead of dielectric material between the ground plane and the radiation part. It is shown that, by designing the impedance matching part in a different geometry, broadband antennas can be designed and developed without changing the gain too much. It is seen that such antennas have a wide range of application areas. The operation bandwidth of the designed antenna is approximately 1750-2550 MHz. The operation bandwidth covers UMTS band. The antenna has a rectangular conductive part between feed connector and radiating element. There are conductive trapezoidal parasitic elements on both sides of the rectangular part. A thin air gap between trapezoidal parts and radiating element that helps impedance matching. The antenna is designed, analyzed and simulated by using commonly used commercial EM simulation software package, HFSS. Detailed configuration, simulated return loss, radiation pattern and gain plot of the antenna are presented.</p> Ibrahim Catalkaya ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 121 128 Product Development with Additive Manufacturing and 3D Printer Technology in Aerospace Industry http://jast.hho.edu.tr/index.php/JAST/article/view/400 <p>The additive manufacturing and 3-dimensional manufacturing technology offer unparalleled flexibility in terms of part geometry, material composition and manufacturing time. There are many difficulties in manufacturing parts in the aerospace field. Thin-walled aircraft engine components and structures with complex geometry, the difficulties encountered in the processing of materials, are the other main factors that compel the aviation industry to adopt the use of layered manufacturing technology. It is progressing in the direction of radically changing the aerospace sector in the production of extremely complex and lightweight parts with material wastes that are almost none. The aerospace engine industry requires stronger, lighter and more durable components. Today's additive manufacturing technology provides new possibilities to meet these situations. In this study, research and development activities carried out in the field of layered manufacturing in the aviation industry have been examined and a literature review has conducted. In the experimental study, a scaled 3D prototype of an exemplary rocket equipment was produced using 3D printer technology. The pressure parameters of the study have been examined.</p> Murathan Kalender Yahya Bozkurt Sezgin Ersoy Serdar Salman ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 129 138 An ANFIS Based Vehicle Sales Forecasting Model Utilizing Feature Clustering and Genetic Algorithms http://jast.hho.edu.tr/index.php/JAST/article/view/402 <p><em>The automotive sector is one of Turkey’s most important industries, and the developments in technology are affecting the automotive sector as well as the other sectors. The methods that have been used to date indicate that the use of AI should be increased when the demand forecasting applications take into account the developments in the industry. For this purpose, by using the data taken from the Automotive Distributors Association and Turkish Statistical Institute Internet pages, intuitive learning hybrid ANFIS method is used to forecast the sales in this study. A clustering scheme is first applied to group the features, and then the features are fed into genetic algorithms to improve the prediction model performance. The experiments show that the prediction performance of the proposed method is good when compared to existing related studies in the literature.</em></p> Atınç Yılmaz Umut Kaya Ediz Şaykol ##submission.copyrightStatement## http://creativecommons.org/licenses/by-sa/4.0 2020-01-17 2020-01-17 13 1 139 154