Travelling Ionospheric Disturbances (TIDs) are signatures of atmospheric gravity waves (AGWs) observed in changes the electron density. The analysis TIDs is relevant for studying coupling processes thermosphere–ionosphere system. A new TID index ATID introduced, which based on an easy extension commonly used approach detection. This activity index, can be applied individual Global Navigation Satellite Systems (GNSS) stations and also mapping activity, capable to study both Large Scale...

Given the impact ionosphere electron density has on radio wave propagation, understanding, characterizing and predicting its behaviour associated perturbations is of high importance. One type perturbation commonly observed during geomagnetic storm events Large Scale Travelling Ionospheric Disturbance (LSTID). LSTIDs correspond to signature in large-scale atmospheric gravity waves that are generated thermosphere. Such disturbances attributed input energy from solar wind into...

The main goal of this study was to provide a new categorization the different types interactions between model-based system engineering (MBSE) and digital twins (DTs). To achieve goal, an overview relationships these two concepts obtained based on representative set articles. search identified 444 unique valid records, which 16 were selected for analysis article screening eligibility assessments. articles then analyzed identify DT-MBSE relations area case study. As result, classified into...

This paper deals with the design, realization, and testing of an earth magnetic field simulator, which allows us to validate hardware-in-the-loop algorithms, as well test new actuators. The design is driven by typical small satellites functional requirements. subsystems that compose simulator are described in detail. validation performed assessing its functioning, uniformity recreated field, functionality a magnetorquer.

This study investigates the problem of controller design for systems with uncertain sampling rates. The system is controlled through a communication network. period, within given interval, assumed to be time-varying and simplified framework network-induced delay considered. overall thus described by an discrete-time model parameters inside polytope whose vertices are obtained means Cayley–Hamilton theorem. A digital robust that minimises upper bound ℋ∞ performance closed-loop networked...

<p>Este trabalho teve como objetivo ajustar e selecionar modelos matemáticos para a estimativa do volume comercial com casca espécies comerciais de uma Floresta Ombrófila Densa Terra Firme localizada no sul Roraima. Foram abatidas cubadas pelo método Smalian 122 árvores 18 diâmetro à altura peito maior que 50 cm. testados nove modelos, ajustados pelos métodos dos mínimos quadrados, selecionados em função coeficiente determinação ajustado, erro padrão porcentagem, valor F calculado da...

To simulate the conditions of space environment at ground, Laboratory Application and Innovation in Aerospace Science (LAICA) University Brasília (UnB) is developing a dedicated testbed to reproducing nanosatellite attitude motion. The composed an air-bearing table Helmholtz cage. spacecraft simulator that can frictionless with three rotational degrees freedom. Balancing essential order make gravitational torque negligible. also equipped cage recreate Earth's magnetic field spacecrafts...

Abstract The problem of gain‐scheduled state feedback control for discrete‐time linear systems with time‐varying parameters is considered in this paper. are assumed to belong the unit simplex and have bounded rates variation, which depend on values can vary from slow arbitrarily fast. An augmented vector defined take into account possible time‐delayed inputs, allowing a simplified closed‐loop analysis by means parameter‐dependent Lyapunov functions. A controller that minimizes an upper bound...

No AccessEngineering NoteAttitude Control of an Underactuated Satellite Using Two Reaction WheelsJefferson R. Chaurais, Henrique C. Ferreira, João Y. Ishihara and Renato A. BorgesJefferson ChauraisDepartment Electrical Engineering, University Brasilia, 70910-900 DF, Brazil, FerreiraDepartment IshiharaDepartment Brazil BorgesDepartment BrazilPublished Online:23 Jul 2015https://doi.org/10.2514/1.G000145SectionsRead Now ToolsAdd to favoritesDownload citationTrack citations About References [1]...

Traveling Ionospheric Disturbances (TIDs) reflect changes in the ionospheric electron density which are caused by atmospheric gravity waves. These impact functionality of different applications such as precise navigation and high-frequency geolocation. The Horizon 2020 project TechTIDE establishes a warning system for occurrence TIDs with motivation to mitigate their on communication applications. This requires identification appropriate indicators generation this purpose we investigate...

The use of robust design techniques such as the one based on H2 and H∞ for tuning proportional integral (PI) derivative (PID) controllers have been limited to address a small set processes. This work addresses problem by considering wide possible plants, both first- second-order continuous-time systems with time delays zeros, leading PI PID controllers. structured uncertainties handle neglected dynamics allows expand range processes be considered. proposed approach takes into account...

This paper addresses the voltage regulation of dual active bridge converters based on robust PI controllers. The plant model presents a dependence an uncertain parameter, which defines operation condition, motivating design controllers for this application. Linear matrix inequalities are then used to synthesize control gains ensure closed-loop pole location inside sector in left-hand complex plane entire set uncertainties. Comparisons with controller designed only nominal condition indicate...

This work presents the first advanced level CanSat developed by University of Brasilia, LAICAnSat-1. The main objective is to design, build and launch an experimental high altitude balloon withmeteorology remote sensing applications. Both scientific need for a self retrievable radiosonde, with precise quality sensors, low-cost platform inspired team on concept has broad sensor suite that provides information about temperature, pressure, humidity UV light level. It also modular based stacks,...

In this paper, the problem of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering for linear systems affected by arbitrarily time-varying parameters in polytopic domains is investigated. A parameter-varying filter which minimizes an upper bound to estimation error performance determined both continuous and discrete-time cases. Different from other strategies literature, design accomplished means a convex optimization procedure...

This paper considers the development of a Low-Cost Attitude Determination and Control Subsystem (LCADCS) for first Ukrainian University Nanosatellite, UYS-1. For attitude determination part, an framework is implemented to combine all available data at each time sample using modified Unscented Kalman Filter, based on Quaternion Estimator (USQUE). control subsystem should rely only magnetic actuation with magnetorquers operating in relay mode. A proposed strategy presented. The choice hardware...

In this paper, the problem of reduced order H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filter design for time-invariant discrete-time linear systems is investigated. The filtering rewritten as a static output feedback control and elimination lemma applied to derive conditions both precisely known uncertain systems. An algorithm proposed solve in two stages involving only matrix inequalities. A robust arbitrary obtained by solving...