Authors:Chayapoj Lee-Anant Abstract: This paper discusses the important roles of frequent flyer programs (FFPs) in the airline industry with an emphasis on FFPs as a tool for airline business development, a customer relationship management (CRM) tool, and an airline tool of highest return of investment among CRM initiatives. An FFP is a sort of loyalty program sponsored by an airline or a group of airlines that rewards regular passengers with extras and prizes to make flying with the airlines convenient. Thus, advantages and disadvantages of FFPs between airline businesses and passengers are critically discussed. The paper examined existing and recent literature reviews with some add-on case studies. Interestingly, FFPs can be both push and pull factors for airline competitiveness enhancement, analytically reviewed. All discussions presented has revealed that FFPs can be a forceful tool for creating airline competitiveness, depending on how the airline manage it professionally or not. It can be summed that if the airlines manage their FFPs effectively, they can retain their existing passengers and be able to keep the market share. Hence, the airline competitors cannot effortlessly enter to the selected market. PubDate: 2022-04-22 Issue No:Vol. 14 (2022)
Authors:Shanzhong Liu, Mengqi Xue, Yaolong Qiu, Xingyu Zhou, Qingxiu Zhao Abstract: Targeting at the stable tracking control problem of the interceptor missile’s flight attitude in the terminal guidance phase, the nonlinear mathematical model of missile attitude is used as the research object, in which the coupling among the channels is considered. The control strategies of Proportion Differentiation (PD) control, nonlinear and linear active disturbance rejection control are studied. Firstly, the expanded state observer is designed to estimate the total disturbance information in real time, and the error feedback controller is designed to provide disturbance compensation, so that the original second-order nonlinear system is decoupled into the canonical form of cascade integrators to realize the stable tracking control of the missile attitude. Secondly, the three-channel coupling closed-loop control system model is established, and under the influence of external disturbance and model parameter perturbation, the comparison between the three control methods is demonstrated by simulations. The simulation results show that these three methods can stabilize the missile attitude and track the reference input signal. Among them, the nonlinear active disturbance rejection control has the smallest overshoot, the strongest antiinterference ability, and better robustness. PubDate: 2022-04-22 Issue No:Vol. 14 (2022)
Authors:Heitor Andrade Porto, Carlos Alberto Fortulan, Arthur José Vieira Porto, Roberto Hideaki Tsunaki Abstract: One of the many benefits of additive manufacturing (AM) is to produce parts ready to assemble and use, a concept called direct digital manufacturing (DDM). This, besides the ease of manufacturing complexes geometries, creates a potential for applying the AM technology for producing small wind turbines (SWT) blades. Small wind turbines have an increasing role in the worldwide energy matrix, which can be built up by developing site-optimized and customized turbines. Customizing SWT can increase the energy harvesting potential of such machines; however, it requires flexible manufacturing procedures. The blade’s geometric complexity and flexible manufacturing are features that can benefit from the potentials of AM. This work analyses the final geometry of SWT blades manufactured by AM, assessing the scope of DDM in the SWT field. The parts length is 225 mm, the blades were manufactured by the Fused Deposition Modeling (FDM) method using a Dimension Elite machine produced by Stratasys. The geometric evaluation was performed using a CROMA coordinate measuring machine. The measurements showed good results when compared to values adopted in several studies that investigated the effects of geometric disturbances on wind turbine blades. This work affirms that AM is a powerful technology for manufacturing SWT blades in a DDM scope. PubDate: 2022-04-22 Issue No:Vol. 14 (2022)
Authors:Devinder Kumar Yadav, Maryil O Goriet Abstract: Since the beginning of globalisation and open sky policies, airlines experience intense competition, and their performance get affected by many external factors in addition to internal issues. Fuel price fluctuation, aircraft maintenance, labour and aircraft technical operations cost are primary factors that significantly drain the budget of an airline while exerting strong impact on its operational performance. However, this study focused on effects of external factors, such as political, economic and legal mandates on an airline performance. Therefore, relationships between these factors and airline operational performance are identified and analysed in this paper. Kenya Airways has been chosen as a representative airline for this study. Nevertheless, examples from other airlines are also included for the analysis. Data for this research were collected though a descriptive survey designed according to a qualitative mixed approach. Consequently, focused interviews and questionnaires were used, and reliability of obtained results was checked using Cronbach’s alpha method. The results indicate strong positive correlations between the external factors and performance of an airline. This study therefore confirms that performance of an airline can be influence by market driven fluctuations or intentionally altered external factors discussed in this project. PubDate: 2022-03-30 Issue No:Vol. 14 (2022)
Authors:Sergey Gennadievich Konstantinov, Yuri Mikhailovich Ignatkin, Pavel Viacheslavovich Makeev, Alexander Ivanovich Shomov, Sergey Olegovich Nikitin Abstract: This paper is dedicated to the numerical modeling of the aerodynamic characteristics of the full-scale coaxial main rotor. The modes of forward flight in the range of values V = 30−60 m∙s–1 (108−216 km∙h–1) have been under consideration. The simulation has been performed with the usage of two computational fluid dynamics (CFD) approaches: the free wake model (FWM) developed by the authors and the unsteady Reynolds-averaged Navier–Stokes (URANS) equations method based on the Ansys Fluent software. The coefficients of rotor thrust and torque, vortex wake shapes and induced velocity fields have been obtained and analyzed. The FWM and the URANS modeling data match satisfactorily. The FWM demonstrates a significant advantage in computing time and resources costs with sufficient accuracy in resulting rotor’s basic aerodynamic characteristics. That’s why it seems appropriate to use the FWM for preliminary simulations, taking into account before using the high time and resource intensive the URANS method for comprehensive investigation of coaxial rotor aerodynamics at flight modes. PubDate: 2022-03-15 Issue No:Vol. 14 (2022)
Authors:Marcelo Tadeu Ferreira, Claudio Antonio Federico Abstract: Today, the certification process for onboard electro-electronic systems against nonionizing radiation can be considered mature and independent, having its own set of requirements. In turn, the current proposal for this process with regard to ionizing radiation is relatively recent and is in the process of improvement and discussion by industry and regulatory bodies, and presents important differences in approach. In this work these two processes are presented comparatively in detail, pointing out similarities and differences in order to contribute to this ongoing discussion, which should, in the medium term, result in regulation for the effects of ionizing radiation. PubDate: 2022-03-15 Issue No:Vol. 14 (2022)
Authors:Antonio Gil Vicente de Brum, Carolina Schuindt Abstract: In addition to radio navigation, optical navigation has been used successfully in deep-space missions since the launch of the Voyager spacecraft, in the 1970s. In the 1990s, the NASA’s Deep Space-1 mission successfully tested an autonomous optical navigation system which allowed great reduction in mission costs, and maximized scientific results. The ASTER mission, the first Brazilian deep space mission, shall count on the support of optical navigation for all its phases. The platform of the probe is the Russian Pilgrim spacecraft developed by the Russian Space Research Institute for the Finnish-Russian mission to Mars (MetNet). As such, besides the scientific camera on board (which may also be used for navigation purposes), the probe will also dispose of a navigation camera (NAVCAM). This study is related to the formulation of a general proposal of optical navigation, that can be used in the ASTER mission, which takes into account the equipment available on board, especially the NAVCAM, along with tracking software suitable for the conduction of optical navigation. The description of an appropriate navigation algorithm together with its successful application to simulated and real images (from NASA’s New Horizons mission) is carried out. PubDate: 2022-03-15 Issue No:Vol. 14 (2022)
Authors:João Francisco Galera Monico, Eurico Rodrigues de Paula, Alison de Oliveira Moraes, Emanoel Costa, Milton Hirokazu Shimabukuro, Daniele Marra Barroca Alves, Jonas Rodrigues De Souza, Paulo De Oliveira Camargo, Fabricio Dos Santos Prol, Bruno César Vani, Vinicius Stuani Amadeo Pereira, Paulo Sergio de Oliveira Junior, Italo Tsuchiya, Claudinei Rodrigues Aguiar Abstract: Air navigation is increasingly dependent on the use of Global Navigation Satellite Systems (GNSS). It allows the determination of the aircraft’s position in all phases of the flight and brings many advantages. Although GNSS navigation results in gains, the radio signals from these systems are strongly influenced by the ionospheric environment. It introduces errors that can affect the accuracy, integrity, availability and continuity requirements established by the International Civil Aviation Organization (ICAO). The ionospheric layer has different behaviors depending on the latitude, time of day, season of the year, geomagnetic activity and solar cycle. Since Brazil is located in a region of low latitudes, it experiences a series of unique challenges when compared to regions of mid-latitudes. For this reason, the application of GNSS-based technologies in aviation over the Brazilian territory requires an in-depth assessment of the ionosphere effects. Therefore, the Instituto Nacional de Ciência e Tecnologia (INCT) named GNSS Technology for Supporting Air Navigation was formed in 2017 to better assess the ionosphere impacts and assist government agencies and companies in the development of safe air navigation procedures over Brazil in a near future. This paper presents the most relevant advances achieved so far within this multidisciplinary project that involves Brazilian research centers and universities. PubDate: 2022-03-15 Issue No:Vol. 14 (2022)
Authors:Gregory Morose, David Pinsky, Chandler Humphrey, Kent DeFranco Abstract: Conversion coatings containing hexavalent chromium are currently used in aerospace and defense manufacturing on various aluminum alloys to provide corrosion protection and enhanced adhesion of subsequent coatings. However, hexavalent chromium is toxic to humans with negative health effects from acute and chronic exposure. Regulatory mandates have accelerated a global effort to replace hexavalent chromium-containing materials because of their toxicity. A consortium was established to evaluate safer conversion coating materials, including the chemical processing of the surfaces prior to applying the conversion coatings. Four conversion coatings without hexavalent chromium were compared against a hexavalent chromium-based conversion coating for the following tests: coating weight, electrical contact resistance, paint adhesion, bare and painted neutral salt fog corrosion tests, painted SO2 salt fog corrosion test, and painted outdoor beachfront corrosion test. The test results for the four conversion coatings without hexavalent chromium were encouraging since several candidates exceeded some of the specification requirements or consortium expectations. In particular, the Socosurf TCS/PACS conversion coating performed well in the coating weight, electrical contact resistance, paint adhesion, and corrosion tests. The results of this evaluation provide significant progress toward providing a replacement material for a traditionally hexavalent chromium material application on aluminum. PubDate: 2022-02-23 Issue No:Vol. 14 (2022)
Authors:Xueer Zhang, Tianping Zhang, Detian Li Abstract: An approach to quantify the lifetime and reliability of dual-mode ion thruster is presented based on coupling analyses of thruster failure modes, throttle levels, life models, input uncertainties, and throttle profiles. This approach involves lifetime characterization based on each failure mode, a conservative life margin assessment followed by a failure mode reduction and a quantification of life margins and uncertainties which gives a further reduction of the failure modes, Weibull fitting of the sampled lifetimes based on each of the remained failure modes to obtain their reliability functions, and derivation of a combined reliability function according to the throttle profile. The results for LIPS-200E completing a 13 kh mission show that the lifetime distribution and mission reliability strongly depend on the throttle profile. PubDate: 2022-02-21 Issue No:Vol. 14 (2022)
Authors:Yurii Mitikov, Olexiy Shynkarenko Abstract: The work focuses on optimizing the pressurization system’s operating performance for a fuel tank of a turbo-pumped liquid propellant rocket engine. This system is the most complex and expensive in a medium-size launch vehicle, after the engine. A new patented methodology of reducing the final mass of a rocket stage is proposed, studied, and validated. The application of the proposed method is efficient at the end of the engine operation sequence during the throttling regime. The calculation method of the helium excess in the high-pressure cylinders uses the model of the real gas. It also involves empirical relations describing nonstationary heat and mass transfer in the system. As an innovative technical solution, the authors propose to estimate excess gas discharge from tanks and cylinders after the engine’s last throttling. The practical application of the research allows saving tenths of kilograms of a payload with the implementation of simple modification in the launcher control program. The research results demonstrated the effectiveness of the methodology on the example of the RD-171 fuel tank pressurization system. PubDate: 2022-01-27 Issue No:Vol. 14 (2022)
Authors:Karine Klippel, Elisa Valentim Goulart, Gilberto Fisch, Bruno Furieri, Cayo Prado Fernandes Francisco, Neyval Costa Reis Junior Abstract: The Alcantara Launch Center (ALC) is the main Brazilian access to space. It is positioned over a complex terrain, and it has some important buildings for assembling, integration and launching activities, such as the Mobile Integration Tower. Being in a region of prevalent trade winds, the flow interaction between the complex terrain and the buildings can affect the safety of operations on the platform, and the dispersion of toxic gases emitted during the launching. The main objective of this work was to study the influence of topography and buildings on the atmospheric flow of ALC using computational fluid dynamics (CFD) techniques. Three geometries were considered: simplified terrain (case 1), smooth complex terrain(case 2), and roughness complex terrain (case 3). The flow conditions over ALC were simulated using the ANSYS Fluent 19.0 CFD commercial code. The numerical simulations used a realizable κ-ε to model turbulence effects and the results presented a good agreement with the in-situ field measurements for the most complex geometry (case 3). The topography clearly influences the flow pattern at ALC, with the cliff influence over the wind being the major cause for establishing the flow patterns. PubDate: 2022-01-27 Issue No:Vol. 14 (2022)
Authors:Ramesh Kumar Rajamanickam, Rajesh Durvasulu, Sundarraj Moorthi Abstract: Nowadays, many industries are shown interest in the hybrid composites, natural fibers, and reinforced materials due to reduction of the weight. The reason is that it will not affect environmental conditions. This experimental investigation identified the mechanical properties of hybrid composites. The hybrid composite materials are extensively used by E-glass/epoxy, carbon, and titanium alloy. Composites have good strength and less weight. The highest challenge of the automobile industry is to replace the steel leaf spring instead of the composite leaf spring. The composite structures have been providing better corrosion resistance. The conventional leaf spring experimental results were compared to analytical results of composite leaf spring. The design, simulation, and maximum stresses were done with the help of Ansys Workbench 15. Ansys Workbench materials are selected by titanium alloy, epoxy glass, aluminum alloy, and epoxy carbon. The design parameters were selected and analyzed to compare stress, deformation, elastic strain, and weight of the composite leaf spring as compared to conventional steel leaf spring. Deflection results were identified in the mechanical properties of the leaf spring. It should absorb shock loads and vertical vibrations due to road abnormalities. The composite experimental samples were analyzed using scanning electron microscopy PubDate: 2022-01-27 Issue No:Vol. 14 (2022)
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