Resumo em Inglês:

ABSTRACT The use of Global Navigation Satellite System (GNSS) for air and terrestrial navigation and for many applications is increasing in the last decades. However, the Earth’s ionosphere causes GNSS signal delay due to the total electron content (TEC) and scintillation in the signal phase and amplitude. This scintillation can give rise to deleterious effects in the GNSS positioning. So, it is important to assess the effects of the ionosphere over the GNSS signal. To achieve this goal, it is necessary to have a large spatial and temporal coverage of data from many different sounders, being the GNSS receivers of great importance due to their global coverage and availability. In this work, we present a retrospective of the scintillation monitoring networks in Brazil and their characteristics. As the RBMC network managed by the IBGE provides TEC and as rate of TEC index (ROTI) is well correlated with ionospheric irregularities, we present also the RBMC network description. These RBMC GNSS receivers provide data in regions with scarcity of scintillation monitors. The description of the Ionospheric Scintillation Monitoring Receivers (ISMR) Query Tool, that is a web software that has been supporting research on the ISMR data, is also presented.

Resumo em Inglês:

ABSTRACT Couple stresses because of magnetic particles additives on the lubrication performance of a journal bearing system was embraced and scrutinized in the current examinations theoretically. The governing equations of Reynolds (pressure field), energy (temperature field), and heat conduction (temperature field through the solids) are coupled and solved instantaneously in term of temperature and viscosity. After these set of equation pressure is obtained, it is used to obtain the bearing characteristic. It was found that the load currying capacity and maximum pressure are increased due the employing of magnetic fluids along with the couple stresses, as well as side leakage flow and the friction coefficient are decreased. It can be also concluded that the magnetic fluids with couple stresses are better lubricant than magnetic fluid only (l = 0), Newtonian fluids, and couple stress fluid (ʎ = 0).

Resumo em Inglês:

ABSTRACT The use of artificial intelligence, along with its various components, is rapidly increasing in various fields of study today, going beyond the traditional domains of computer science and mathematics. To gain insights into how artificial intelligence is being applied in the air transport industry, uncover underlying correlations and trends in the literature, and identify potential research gaps, we conducted a systematic literature review supplemented with bibliometric elements such as keyword co-occurrence and author influence. The key findings of our research shed light on the most prolific institutions and authors globally involved in generating knowledge about AI applications in air transport. Additionally, we identified five research clusters that dominate the overall research direction: prediction and optimisation (constituting 65% of the articles), inter-industry collaborations (17% of the articles), human experience (9% of the articles), safety, risks, and ethical considerations (6% of the articles), and ecology and sustainable development (3% of the articles). Overall, further research is needed to explore the ethical implications, legal considerations, integration processes, and impact on employment and the environment in the air transport industry.

Resumo em Inglês:

ABSTRACT The historic flight of cosmonaut Yuri Alekeseyevich Gagarin, in 1961, established the need for research regarding the physiological adaptations of the human body when exposed to the space environment. Since then, several morpho-functional transformations – varying between normal and pathological – have been identified within the organisms of astronauts subjected to the extremely disparate environments of the cosmos, consequently, comprehension and preparation of these transformations becomes essential, considering the possibilities (1) of returning to the Moon and (2) of initiating the trip to Mars. Accordingly, the purpose of this article – conceived as a narrative literature review – is to present the main aspects of the physiological modifications within the human body due to the extraterrestrial environment, with emphasis on cardiovascular, renal, hydroelectrolytic, hematological, immunological, respiratory, neurological, psychological, sensory, gastrointestinal, endocrine, musculoskeletal, integumentary, and genetic adaptations.

Resumo em Inglês:

ABSTRACT From the perspective of the evolution of modern mass-production industrial sectors, the establishment of an industry can occur in a typical sequence of four conceptual phases: the introduction phase, in which a new technological concept is introduced; the growth phase, in which application of this concept in the form of a product or service is undertaken; the maturity phase, in which the direct use of the product and the advent of product-enabled services establish the new economic sector, and an eventual decline phase when one or more substitute products appear. Most of the current industrial products may be considered systems. The application of established concepts, such as interchangeable parts, permits firms to manufacture systems on a large scale, making sophisticated products available to society at manageable prices. The large availability of a product in a socioeconomic environment favors the use of this product in innovative ways, many of them unprecedented. In this way, introducing an innovative product in the market may nucleate a whole new industry over time, which may experience growth either through the continual evolvement of the product or expansion of the breadth of applications. Recent years have shown impressive development in the space industry. This article presents data that suggests that the global satellite space industry is transitioning from a growth to a maturity stage. It will be argued that barriers to entry are still at a level that permits Brazil, given its current position, to engage in the global space industry.

Resumo em Inglês:

ABSTRACT In order to intercept hypersonic vehicles in near-space, a head-pursuit cooperative guidance law is proposed in this paper. Firstly, interceptors are regarded as multi-agents, and the communication relationship between them is represented by graph theory. Based on the time consistency theory of multi-agent system and sliding mode theory, a guidance law is designed along line-of-sight (LOS) to ensure the time cooperation of interceptors. Secondly, considering the requirement of the head-pursuit theory to the lead angle, a finite-time guidance law is designed perpendicular to LOS to ensure that each interceptor can complete head-pursuit interception. For the purpose of improving the intercept precision, extended state observers are used to estimate the system disturbances. The correctness of the guidance law is analyzed by Lyapunov stability theory. Finally, numerical simulations are presented and the results further verify the correctness of the guidance law.

Resumo em Inglês:

ABSTRACT Cusped-field Hall thrusters (CFHT) have significant potential for use in many space missions due to their simplicity, long life and high efficiency. CFHT-27, designed and developed at the Bogazici University Space Technologies Laboratory (BUSTLab), is a prototype CFHT with a 27-mm diameter discharge channel. CFHT-27 utilizes samarium-cobalt (SmCo) permanent magnets. The thrust and efficiency of a cusped-field thruster is closely related to its size and design parameters. In this study, in order to understand the relationships between the design parameters and the thruster performance, the performance tests of the CFHT-27 are carried out for a given magnetic field topology. The thruster was operated at discharge voltages ranging from 250 to 500V with argon propellant with up to 3,000 s of specific impulse. The measurements show that CFHT-27 can achieve thrust values from 1 to 46 mN. Thus, this thruster can be used for a wide range of thrust values allowing throttle capabilities for different missions.

Resumo em Inglês:

ABSTRACT This work presents the design and prototyping of two 1U standard CubeSats for the First Brazilian MCTI Satellite Olympiad, launching one in a stratospheric helium-filled balloon. The nanosatellites were designed for two missions: Internet of Things connectivity in remote areas based on CubeSat (IoSat) and low-orbit harmful gamma radiation mapping (LOHGRM). The IoSat mission aimed to provide server connectivity for a remote sensor network. The LOHGRM CubeSat was designed for sensing and mapping gamma radiation power levels in the satellite’s orbit to construct a heat map to study the gamma radiation effect on the equipment. The prototype’s performance was evaluated based on physical, mechanical, magnetic, thermal, and transmission characterization, with satisfactory results under test conditions. The LOHGRM mission test was carried out on the ground as proof of concept without flying while a stratospheric balloon launched the IoSat prototype. Due to restrictions imposed by the competition, the IoSat nanosatellite only captured and registered altitude, pressure, and temperature data without testing the communication payload. Instead, this data was sent to the ground station through the competition communication system and stored in a memory card to assess its operation during the flying. The satellite’s maximum altitude was 22.6 km, operating under –23.5 °C.

Resumo em Inglês:

ABSTRACT Airports are seen as a crucial component of infrastructure in the construction of modern cities in the Middle East, where aviation is recognized as a top priority in their development strategy. While the airline industry in the Middle has been investigated, there are no studies that explored the region’s successful global aviation hubs from a national competitive advantage perspective. Therefore, this paper examines the macro environmental elements affecting a nation’s competitiveness in the aviation industry using a mixed-methods approach, including Porter’s notion of national competitive advantage and expert views. The analysis shows that while macro environmental factors such as geographical advantage, physical and intellectual infrastructure, and business attractiveness are important for a successful aviation development, they are not necessarily required to guarantee a hub status unless the governments are devoted to developing the sector.

Resumo em Inglês:

ABSTRACT Fixed-wing unmanned aerial vehicles (UAVs) offer the best aerodynamic efficiency required for long-distance or high-endurance applications, albeit their runway requirement for take-off and landing in comparison with quadcopters, helicopters, and flapping-wing UAVs that can perform vertical take-off and landing (VTOL). Integrating a multirotor system with a fixed-wing UAV imparts VTOL capabilities without significantly compromising fixed-wing aerodynamic efficiency, endurance, payload capacity or range. Documented system design approaches to address various challenges of such fusion processes are sparse. This research proposes a holistic approach for designing, prototyping, and testing an electric-powered fixed-wing hybrid VTOL UAV. The proposed system design approach augments the standard aircraft design process with additional steps to integrate VTOL capabilities. Separate fixed-wing and multirotor designs were derived from the frozen mission requirements, which were then fused. The process used simulation for modeling and evaluating alternatives for the hybrid UAV created using standard aircraft design equations. We prototyped and instrumented the final design to validate operational capabilities through test flights. Multiple flight trials identified the ideal combination of Lithium-Polymer (Li-Po) batteries for VTOL (8000mAh) and fixed-wing (14000mAh) modes to meet the endurance and range requirements. The redundant power supplies also increased the survivability chances of the hybrid UAV during failures.

Resumo em Inglês:

ABSTRACT Normally, flight delays and cancellations have significant impact on airlines operations and passenger’s satisfaction. Flight delays reduce the performance of airline operations and make significant effect on airports on time performance. Previously statistical models have been used for flight delays analysis. This study was applied in Indian aviation industry and it has given statistical analysis of domestic airlines. In this research paper, we have applied Machine Learning models with the help of computational intelligence techniques for predicting airport transport management system. We have also applied computational intelligence techniques such as Particle Swarm Optimization (PSO) and Ant Colonization Optimization (ACO) to optimize the prediction model for delay period time and calculating the most optimal dependability. We have made comprehensive analysis of Data Efficiency Model for different airlines with various approaches as well as comparative analysis of accuracy for predicting airport model by using various machine learning models. In this study we have presented invaluable insights for the analysis of flight delay models.

Resumo em Inglês:

ABSTRACT Currently, the presence of spurious microwave radiation is increasing in the environment, which has caused concern due to possible health problems in living beings and electromagnetic interference in electronic systems. To control this problem, studies in the materials area are taking place, aiming to attenuate the spurious radiation and meet requirements of good performance in broadband, low cost and low weight. The present work aimed to study Cu and Ni nanometric films with thicknesses of 65 and 200 nm, deposited on polyethylene terephthalate substrate by magnetron sputtering. Scanning electron microscopy with a field emission gun (FEG-SEM) showed that the films produced have different morphological textures, due to the parameters used in the sputtering process and also the free energy of metals. Impedance spectroscopy measurements showed that the films have low conductivity values, due to the metallic oxides formed on the film surfaces, confirmed by X-ray diffraction, and also to the presence of defects. Electromagnetic characterization (8.2 – 12.4 GHz) showed that the Cu and Ni thin films had low performance, except the Ni_200 nm film, which showed a total shielding efficiency of about 30% in broadband. This result is promising considering the nanometric thickness of the Ni film.

Resumo em Inglês:

ABSTRACT This paper proposes a new approach in multi-step sequential system optimization (MSSO) to implement a conceptual design for satellite upper stage with a maneuver in the conditions close to reality. In this method of design, there are two main cycles; trajectory optimization cycle and optimal design cycle, each one is correlated to each other in another cycle called configuration. In the trajectory optimization, the optimization objective is to place the upper stage in the destination orbit, using the minimum amount of fuel consumption. In this cycle, a new approach has been introduced for a three-dimensional trajectory using two genetic algorithms inside each other. In addition, selecting the suitable engine is carried out in this cycle. Convergence of design and exclusion of design are carried out in the configuration cycle. Convergence and optimization of subsystems design are carried out in the optimal design cycle. The innovations of this paper are implementation of the design according to multi-step sequential system design in which optimization is performed step by step, and orbital optimization is introduced according to a new approach. Choosing a desirable criterion for optimization process and proper coefficient for convergence in design, are among considerable characteristics of this paper. Validation has been performed using one of the upper stages in the world.

Resumo em Inglês:

ABSTRACT Aimed at the deficiency of existing PID controller for quad rotor UAV, a single neuron PID controller with gravity compensation is presented. After using feed forward control to compensate gravity, the position loop adopts PID control to ensure control accuracy, while the attitude loop adopts single neuron control to increase adaptive ability. Then, by using Matlab/simulink simulation software, the position control of quad rotor UAV is carried out, and the simulation result shows, compared with the traditional double closed loop PID controller, the control algorithm based on the Single Neuron adaptive PID with gravity compensation can effectively improve the robustness and adaptability of the quad rotor UAV system.

Resumo em Inglês:

ABSTRACT Solar energy is one of the most efficient forms of renewable energy. Solar air collectors are promising utilization of solar energy. The present study used unsteady three-dimensional Computational Fluid Dynamic (CFD) analysis to investigate the heat transfer and fluid friction in solar air collectors with smooth and v-corrugation absorber plates. The studied parameters are Reynolds number, v-corrugation height, and pitch. Three Reynolds number (500, 1000, 1500) values were used with three arrangements configuration of the v-corrugation of relative heights of 0.10, 0.16, and 0.23. Roughness pitches varied between 1.33, 1.66, and 2. By comparing the simulated thermal efficiency with the currently known experimental values, great agreement can be approved. Results show the superiority of the performance of v-corrugated collector against the traditional or smooth type. The outlet temperature obtained in case of relative roughness height = 0.23 and relative roughness pitch = 2 is 61 °C, while it is 53 °C for a smooth type. Also, a higher thermal efficiency of 46.7 % can be obtained compared to 33.01% for smooth type.

Resumo em Inglês:

ABSTRACT The aim of the work is to develop conceptual directions for the structure formation and the number of airline’s fleet based on satisfying consumer preferences of enterprises-customers of helicopter operations. The helicopters currently in operation cannot fully satisfy the requirements of customers in terms of their flight technical and economic characteristics, which leads to a decrease in their use and it negatively affects the economy of the airline and corresponding economic region. There is a real need to update and expand the type and fleet of Russian-made helicopters, which will better meet the requirements of the helicopter operations market. To solve it, a helicopter manufacturing enterprise needs to carefully study the market requirements for existing and new types of helicopters, its volumes, formation trends, prices, operating costs, service systems, etc. The work presents a model that makes it possible to formulate for each airline the need for helicopters of various types and specializations for each year of the forecasting period has been developed, depending on the dynamics of changes in the level of socio-economic development of the region and the corresponding changes in the airline’s flight operations, considering the effective demand. It also makes it possible to predict promising types and helicopter fleet.

Resumo em Inglês:

ABSTRACT Slot resources are limited and not properly allocated, and the wave-system structures of airlines can organize slot time effectively. The article identifies and evaluates the wave-system structure of Beijing Daxing International Airport and Beijing Capital International Airport. It is found that: the wave-system of Beijing Capital International Airport is more obvious than that of Beijing Daxing International Airport, and the density and amplitude of waves are higher in summer and autumn than in winter and spring; the system waveforms of both Daxing Airport and Capital Airport are in the shape of morning and evening peaks; the indirect connection quality of flights from different departure airports via Capital Airport is higher than that of Daxing Airport; the indirect connections to destination airports via the two airports in Beijing are uneven in spatial distribution. The spatial distribution of indirect connections to destination airports via the two airports is uneven, but the wave-system plays a significant role in connecting small and medium-sized regional airports.

Resumo em Inglês:

ABSTRACT In this research, a new method named δ to solve non-linear constrained and un constrained optimal control problems for trajectory optimization was proposed. The main objective of this method was defined as solving optimal control problems by the combination of the orthogonal functions, the heuristic optimization techniques, and the principles of optimal control theory. Three orthogonal functions Fourier, Chebyshev, and Legendre were considered to approximate the control variables. Also, GA-PSO and imperialist competition algorithms were considered as heuristic optimization techniques. Moreover, the motivation of the mentioned method belonged to a novel combination of zero Hamiltonian in the optimal control theory, optimality conditions, and newly proposed criteria. Furthermore, lunar landing, asteroid rendezvous, and low-thrust orbital transfer with respect to minimum-time and minimum-fuel criteria were investigated to show the ability of the proposed method in regard to constrained and un constrained optimal control problems. Results demonstrated that the δ method has high accuracy in the optimal control theory for non-linear problems. Hence, the δ method allows space trajectory and mission designers to solve optimal control problems with a simple and precise method for future works and studies.

Resumo em Inglês:

ABSTRACT The use of continuous fibers reinforced polymeric composites has increased substantially in the last year’s due to their high specific mechanical strength compared to other materials. Despite this property, this class of material is susceptible to low, medium, or high energy impacts, which can cause severe damage to composite laminates. One of the most serious damages is delamination, which can lead to partial or total rupture of the structure. In order to minimize this problem, several studies have been carried out in this area. In this context, this work aims to evaluate the influence of aramid reinforcement with bi-directional (2D) and tri-directional (3D) arrangements impregnated with two epoxy resins of different stiffness on the impact strength of composites submitted to the 340 J dart drop test. The impact results showed that the 2D composites had lower impact strength than the 3D ones, with the presence of perforations (when impregnated with the more rigid resin) and delaminations. Delaminations occurred regardless of the epoxy resin used in the impregnation. On the other hand, the 3D composites impregnated with the less rigid epoxy matrix absorbed more energy (3DF: 97.9%) with less deformation and no delamination compared to the 2D laminate (2DF: 96.1%) produced.

Resumo em Inglês:

ABSTRACT New technologies are increasingly being implemented in people’s daily lives and with the growth of smart devices around the globe, the users’ needs and demands have changed in favor of more technological cities, cars, houses, and airplanes. Therefore, it is important to define the stakeholder’s needs and requirements to understand which technologies, smart or not, can be implemented on the cabin to support or even fulfill stakeholder needs. Consequently, those technologies enhance airplane operation and increase product competitiveness for airlines. This paper is the first of a two-part series where design thinking tools are applied to establish high-level requirements based on the concept of a “Smart Cabin” for regional airplanes from 60 to 120 seats. To achieve this goal, a series of methods such as stakeholders’ studies, personas creation and user journey methods are used. The Smart Cabin concept aims to enhance the passenger experience by granting a new level of cabin comfort, customization and connectivity that allows the reduction of airplane time on ground because of the real-time monitoring of airplane cabin components that enables the prediction of maintenance procedures, creates new profits and revenues opportunities for services, provides a more sustainable airplane operation and derived services, and creates new business opportunities for all companies that integrate regional aviation ecosystem.

Resumo em Inglês:

ABSTRACT The use of smart devices is driving the growth of modern systems markets, resulting in more technological cities, cars, houses, and airplanes. Therefore, it is important to understand which smart technologies can support or even fulfill stakeholder needs and consequently enhance airplane operation and increase product competitiveness for airlines. This paper is the second of two-part series and has as its main objective the study of smart technologies that can be implemented on cabins of regional airplanes, from 60 to 120 seats, to comply with the needs and requirements pre-established on the first part of this series of articles. The integration of those technologies results in a “Smart Cabin” architecture which its purpose is to enhances the passenger experience by granting a new level of cabin comfort, customization, and connectivity that allows the reduction of airplane time on ground because of the real-time monitoring of airplane cabin components that enables the prediction of maintenance procedures; creates new profits and revenues opportunities for services, provides a more sustainable airplane operation and derived services, and creates new business opportunities for all companies that integrate regional aviation ecosystem.

Resumo em Inglês:

ABSTRACT Public Science and Technology Institutions (STIs) need to assume and consolidate a proactive role in innovation management to transform knowledge advances into appropriate results for the industrial base. It is required a strategic managerial action aimed at sustaining the sector’s ecosystem and guided by the principle of entrepreneurship. Considering the context of STIs in an integrated approach to the technological innovation process, two questions were raised: How to guarantee an architecture and organizational governance that favor entrepreneurial behavior by linking it to the technological innovation strategy in the ecosystem, and how to expand and promote interactions among ecosystem agents, ensuring an environment leading to innovation and the dissemination of the knowledge generated. The proposed managerial model can be applied in any national or international technology-based innovation ecosystem keeping the characteristics of the business environment. The authors used extensive literature research and direct observation to develop ideas and link them to this management practice. The result was a strategic innovation management model for technology-based STIs. It has management instruments that enhance the proactive performance of ecosystem agents and helps them transfer and absorb the developed technologies.

Resumo em Inglês:

ABSTRACT In utilizing a variable-structure multiple-model (VSMM) algorithm for kinematic state estimation, the core step is the model set design. This study aims to refine the existing expected-mode augmentation (EMA) algorithm, a method of model set design. First, the OTSU algorithm is employed to determine an adaptive threshold, which in turn allows for a reasonable partition of the basic model set. Next, a subset of possible models is preserved, reactivating models adjacent to the one with the highest prediction probability, eliminating improbable models, and yielding an augmented expected mode. Additionally, the study leverages the translation properties of radial functions and inverse trigonometric function formulas to derive a maneuvering model for star-convex extended targets under uniformly accelerated conditions. In order to assess the effectiveness of the proposed algorithm and the validity of the established maneuvering model, simulation experiments were carried out in both fixed and random scenarios. The proposed algorithm demonstrates improved performance when compared to the interactive multiple-model algorithm and the unmodified EMA algorithm.

Resumo em Inglês:

ABSTRACT Axially-functionally graded materials are/ types of traditional composite materials in which the mechanical and physical properties are gradually varied from one end to the other. They were used extensively in industries such as defense, automotive and aerospace because of the ability to design its mechanical and physical properties. Two numerical models are built in this work in order to investigate the deflection of a simply supported beam made by axial-functionally graded material. The first model is the new model and it is built by adopting the Rayleigh Method, while the second model used the Finite-Element technique to build an 1D model utilizing the ANSYS APDL. The mechanical and physical of the axial-functionally graded beam were changed in axial direction according to Power-Law Equation. The new model, based on Rayleigh Method ANSYS- 1D model, shows an excellent agreement with the results and available literature. In addition to the validation of the two models, the influences of elastic moduli ratio and material distribution on the maximum static deflection and its position were studied. In ANSYS- 1D model, the position of the maximum deflection was deviated from the middle span of A-FG beam and this deviation in position of maximum deflection reduces, as well as increases the index of power-law equation and the elastic moduli ratio (ME-Ratio) when it diverges from 1.

Resumo em Inglês:

ABSTRACT Vacuum chambers providing a low pressure environment similar to the vacuum environment in low earth orbit have been used for the testing of plasma thrusters. A significant proportion of research on the effects of vacuum facility on plasma thrusters has focused on the effects of background pressure and plume expansion; however, the electrical interaction of the conductive chamber walls with the plasma thrusters needs to be explored further. In this study, the operation of a prototype Hall thruster, HK40, was investigated to understand the effects of wiring configuration of the thruster-cathode-chamber system. During the tests, the thruster was operated in two different grounding configurations. A resistance analogy regarding the changes in the electrical potentials and measured currents was introduced. The calculated thrust and efficiency values of the two configurations were compared. This study shows that the current extracted from the emitter surface of the cathode, along with the cathode-to-ground voltage can be used to estimate the thrust and thruster efficiency. In addition, the theoretical predictions were compared with the values based on the measurements made with an in-house-built inverted pendulum type thrust stand. The presented results show that the thrust and efficiency values are predicted with 3.4% and 8.3% uncertainty, respectively.

Resumo em Inglês:

ABSTRACT In this work, a review of the theoretical aspects and an assessment to validate a Computational Fluid Dynamics (CFD) open-source code for applications in aerospace problems are discussed. The code uses a finite volume method, with cell-centered implementation, and it is suitable for simulations of inviscid, laminar, and turbulent flows. The code considers two-dimensional cases with unstructured meshes and employs the turbulence model known as Spalart-Allmaras. The implementation is detailed presenting the spatial discretization, including the upwind scheme, the linear reconstruction algorithm, and the calculation applying the method of gradients. The temporal discretization considers the application of a multistage explicit algorithm using a 5 stages Runge-Kutta method. The validation was done considering three cases of study: the inviscid shock tube, the laminar flat plate, and the flow over a rocket fairing. These cases are simulated using the software developed and the results are compared with analytical and experimental results. The rocket fairing case is related to the analysis of the Brazilian VLS launch during its transonic flight and it exemplifies the effect of the shock wave/boundary-layer interaction in its pressure distribution. The simulation results present a good agreement with the experimental results.

Resumo em Inglês:

ABSTRACT Several aspects make nitrocellulose based powders adequate as a solid propellant for rockets and missiles and the prefe rable propellant to be used in firearms and artillery: it produces less smoke and less fouling than other propellants; its burning rate shows a well-defined relation to pressure and the composition of the gaseous mixture resulting from its decomposition by burning can be predicted with relatively high levels of accuracy. This last feature, if coupled with adequate thermodynamic models, leads to a reliable framework for the simulation of internal ballistics and, ultimately, to an efficient design. Some simpler models use an ideal gas approach, which is obviously not adequate, and some others perform corrections based on the Virial E quation of S tate for sake of algebraic simplicity. This work employs the Peng-Robinson equation of state to model the pressure-volume-temperature (PVT) behavior of the gases produced during the burning reaction, once it is known to be accurate in the high pressures obtained inside combustion chambers. The results were compared to experimental data obtained in a closed vessel device and showed that the Peng-Robinson equation of state could predict the chamber pressure with higher accuracy.

Resumo em Inglês:

ABSTRACT Communication with UAV (Unmanned Aerial Vehicle) can be organized using terrestrial radio (high efficiency, but limited in terms of service area) and satellite (global coverage area, but large delay in propagation of radio signals) communication networks. Their integration will ensure high efficiency and reliability of information interaction with UAV. The task of dynamic control of information flows to ensure the specified characteristics is relevant. The article analyzes the algorithm for managing information flows when a communication session with UAV is performed through that segment of the network (terrestrial or satellite one), which at the moment will provide the maximum efficiency of information delivery. A mathematical model of information exchange in this integrated communication network as a queuing network with Poisson incoming traffic and exponential distribution of the volume of transmitted information has been developed. Ratios are obtained for calculating the average network delay depending on the ratio between throughputs of satellite and terrestrial segments of integration of the communication network. The proposed model allows selecting the required bandwidth of satellite and terrestrial segments of communication networks, where the specified requirements for the speed of information delivery are provided. The use of dynamic flow control can significantly increase the efficiency of information exchange with UAV.