A bas nombre de Reynolds, le concept de voilure battante est récemment apparu comme une alternative aux concepts conventionnels de voilure fixe et voilure tournante. Dans le cadre d'une application pratique (micro-drones ou MAVs), l'évaluation de l'adaptabilité d'un tel mode de sustentation requiert la compréhension fine des principaux mécanismes aérodynamiques mis en jeu et de leur impact sur les efforts résultants. Ces derniers se caractérisent par une instationnarité forte et des comportements complexes. Le travail réalisé s'articule autour de trois points. Dans un premier temps, l'établissement d'une corrélation précise entre comportement spatio-temporel des structures cohérentes et effort résultant passe par la définition de méthodes d'investigation adaptées à l'étude d'écoulements bi et tridimensionnels résolus en temps. En ce sens, l'analyse repose d'une part sur une approche numérique DNS par maillage mobile, et d'autre part sur les approches expérimentales TRPIV- 2D2C/3D3C conduisant à la mesure non-intrusive des efforts aérodynamiques par application du bilan de quantité de mouvement. Les difficultés associées à ces techniques novatrices sont ici mises en exergue. En second lieu, nous abordons deux types de configurations bidimensionnelles caractérisées par des cinématiques de battement respectivement symétriques et asymétriques. Nous nous limitons à l'étude du vol stationnaire ou sur place pour lequel les effets instationnaires sont prépondérants vis- à-vis des effets quasi-stationnaires. D'abord, l'analyse détaillée d'un cas de référence permet d'affiner les résultats reportés dans la littérature. Ensuite, la confrontation systématique de cas asymétriques rév`ele l'occurrence de phénom`enes aérodynamiques particuliers contribuant favorablement à l'efficacité de l'aile. L'approximation bidimensionnelle occulte toutefois l'influence du tourbillon marginal ou du gradient transverse de vitesse incidente établi le long de l'envergure d'une aile en révolution autour de son emplanture. L'une des spécificités des configurations tridimensionnelles provient effectivement du caract`ere stabilisateur de certains mécanismes aérodynamiques. Ainsi, nous présentons les effets tridimensionnels et leur dépendance vis-à-vis de l'allongement dans le cas de mouvements de battement en translation rectiligne et en rotation autour d'un axe vertical.

reproduction de : Thèse de doctorat : Mécanique des milieux fluides : Poitiers : 2008. / Titre provenant de l' écran-titre. Bibliogr. 139 réf.

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη και τη μοντελοποίηση ενός ελεγκτή, ο οποίος δύναται να διατηρήσει τον έλεγχο ενός ιπτάμενου ελικοπτέρου τεσσάρων ελίκων γνωστό και ως quadrotor, σε περίπτωση δυσλειτουργίας κάποιου κινητήρα. Η μοντελοποίηση και η προσομοίωση γίνεται με τη βοήθεια του προγράμματος Μatlab/Simulink. Αναλυτικότερα, στο κεφάλαιο 1, γίνεται μια σύντομη παρουσίαση του quadrotor, αναφέροντας τον τρόπο λειτουργίας του και τους σημαντικότερους σταθμούς της ιστορίας του μέχρι σήμερα. Στη συνέχεια, επισημαίνεται η αναγκαιότητα ενσωμάτωσης συστημάτων αυτομάτου ελέγχου σε συστήματα που επηρεάζουν άμεσα ή έμμεσα την ανθρώπινη ζωή καθώς και η σπουδαιότητα βελτίωσης αυτών, κάνοντάς τα ανεχτικά σε σφάλματα και δυσλειτουργίες. Στο κεφάλαιο 2, μελετώνται οι εξισώσεις που περιγράφουν την κίνηση και τον προσανατολισμό του quadrotor. Έτσι δημιουργείται το μοντέλο του συστήματος, τόσο με σταθερό όσο και με μεταβλητό κέντρο μάζας, το οποίο θα χρησιμοποιηθεί στις προσομοιώσεις για την αξιολόγηση των ελεγκτών. Τονίζεται πως η αντίσταση του αέρα δεν θεωρείται πλέον αμελητέα καθώς επηρεάζει σε σημαντικό βαθμό τη κατάσταση του οχήματος. Στο κεφάλαιο 3, δίνεται το θεωρητικό υπόβαθρο στο όποιο θα στηριχτούν οι ελεγκτές που θα δημιουργηθούν. Πιο συγκεκριμένα, γίνεται μια παρουσίαση του ελεγκτή PID, καθώς και πως επηρεάζουν οι μεταβλητές του ένα σύστημα. Στη συνέχεια, παρουσιάζονται σημαντικές πληροφορίες για την μοντελοποίηση των σφαλμάτων και το κεφάλαιο κλείνει με τη παρουσίαση ελεγκτών με ανοχή σε σφάλματα. Στο κεφάλαιο 4, παρουσιάζονται τα μοντέλα των ελεγκτών που χρησιμοποιήθηκαν στις προσομοιώσεις. Πιο αναλυτικά, ξεκινώντας από ένα ελεγκτή ικανό υπό προϋποθέσεις, καταλήγουμε σε ένα εύρωστο ελεγκτή αξιοποιώντας τη μετακίνηση του κέντρου μάζας. Για κάθε ελεγκτή δίνονται οι παράμετροι καθώς και η σχηματική του απεικόνιση στο simulink. Στο κεφάλαιο 5, παρουσιάζονται και σχολιάζονται αναλυτικά τα αποτελέσματα των προσομοιώσεων. Δίνονται γραφήματα που αφορούν τη θέση και τον προσανατολισμό σε όλη τη διάρκεια της πτήσης αλλά και στο κρίσιμο μεταβατικό φαινόμενο. Τέλος, επισημαίνονται τα πλεονεκτήματα και τα μειονεκτήματα καθενός από τους υλοποιημένους ελεγκτές. Στο κεφάλαιο 6, δίνονται τα συμπεράσματα, αναφέρονται παρόμοιοι ελεγκτές και επιτεύγματα στο τομέα αυτό καθώς και οι διαφορές των ήδη υπαρχόντων λύσεων με τη δική μας προσέγγιση. / In this thesis, a control system, capable of retaining the control of a quadrotor vehicle when one of its actuators fails, is studied and simulated. The software which was used for modeling and simulation is Matlab/Simulink. Specifically, in Chapter 1, there is a brief presentation of quadrotor, stating how it operates and mentioning the most important historical cornerstones. Subsequently, we point to the necessity of integration of automatic control systems to systems that directly or indirectly affect human life and the importance of their improvement by making them tolerant to errors and malfunctions. In Chapter 2, we study the equations that describe the movement and orientation of the quadrotor. Using these equations, the quadrotor model is created, both for fixed and movable center of mass, which will be used in this thesis’ simulations. It is important to mention that the air resistance is no longer considered negligible as it significantly affects the state of the vehicle. In Chapter 3, the theoretical background is given upon which the controllers will be implemented. More specifically, the PID controller is presented, and its influence on the system’s performance. The modeling of quadrotor’s faults is presented and the chapter ends with the presentation of fault tolerant controllers. Chapter 4 presents the controllers’ models which were used in the simulations. Specifically, starting from a controller designed around a nominal operating point, we arrive at a robust controller utilizing the movement of the center of mass. For each controller, its parameters are given as well as its model in Simulink. In Chapter 5, the simulations’ results are presented and discussed in detail. Graphs are used to show the position and the orientation not only throughout the flight but also during the critical transition phenomenon. Finally, advantages and disadvantages of each of the implemented controllers are stated. In Chapter 6, there is the conclusion of the thesis. Similar controllers or achievements are mentioned and how our approximation differs from the other existing solutions.

As the role of technology within warfare continues to increase, it is important to investigate whether or not the consequences of these weapons are being adequately considered. The use of new weapons technologies, such as Unmanned Combat Aerial Vehicles and Precision Guided Munitions, have been both praised and condemned within the war in Afghanistan. Although praised as saving civilian lives due to the precision capabilities of the weaponry there are consistent civilian deaths attributed to these weapons systems. This study examines debates regarding new weapons technologies that have been utilised during the war in Afghanistan. Current literature regarding emerging weapons technology is examined in order to identify key debates. The literature was recognised as falling predominantly within three perspectives - strategy, law and ethics. By identifying the key debates within each perspective it is possible to identify where these debates overlap or diverge. This research concludes that the introduction of counterinsurgency strategy to modern warfare has led to an increasing concern with the ethical and legal dimensions of the debate surrounding new weapons technology.

Thesis (M.M.A.S.)--School of Advanced Airpower Studies, 1995. / Subject: An analysis of whether Special Operations Forces should use Unmanned Aerial Vehicles to support intelligence, surveillance, reconnaissance, communications and re-supply capability deficiencies. Cover page date: June 1995. Vita. Includes bibliographical references.

Em um futuro próximo, “dispositivos inteligentes” serão massivamente empregados em campos de batalha. Essa já é uma realidade, porém, o número de dispositivos utilizados em campos de batalha tende a aumentar em ordens de magnitude. As redes de comunicação de dados serão essenciais para transmitir os dados que esses dispositivos coletam e transformá-los em informações valiosas utilizadas como suporte à atuação humana. O suporte à tomada de decisão, ou mesmo níveis de autonomia, permitindo que estes dispositivos coordenem outros dispositivos, exigem comunicação contínua. Desafios relacionados à comunicação surgirão devido à dinamicidade do ambiente. A configuração da rede deve refletir decisões superiores automaticamente. A grande escala das redes conectando os altos escalões, tropas, veículos e sensores, aliada à falta de padronização dos dispositivos, tornará a integração destes desafiadora. Em um ambiente tão heterogêneo, muitos protocolos e tecnologias coexistirão. As redes de campo de batalha são um elemento de suma importância nas operações militares modernas e conceito de guerra centrada em rede é uma tendência sem volta e influencia desde os altos escalões até o controle de tropas Embora estudos tenham sido realizados nessa área, a maioria deles aborda redes estratégicas de alto nível e portanto não levam em conta as “redes táticas de última milha” (TEN), que compreendem dispositivos de comunicação com recursos limitados, como sensores ou ainda pequenos veículos aéreos não tripulados. Em uma tentativa de preencher esta lacuna, esse trabalho propõe uma arquitetura que combina conceitos dos paradigmas de redes definidas por software (SDN) juntamente com redes tolerantes à atraso/disrupçoes (DTN), para aplicação em redes táticas de última milha. O uso de SDN em cenários com nodos móveis é avaliado considerando uma aplicação de vigilância que utiliza streaming de vídeo e medidas de Qualidade de Experiência (QoE) de usuário são coletadas. Com base nos resultados obtidos, uma aplicação em conjunto dos conceitos de SDN e DTN é proposta, além disso abordamos a escolha do nodo que atuará como controlador SDN na rede. Os experimentos foram executados utilizando um emulador de redes. Apesar de pesquisas adicionais serem necessárias – considerado requisitos de segurança, por exemplo – os resultados foram promissores e demonstram a aplicabilidade destes conceitos no cenários das TENs. / The future battlefield tends to be populated by a plethora of “intelligent things”. In some ways, this is already a reality, but in future battlefields, the number of deployed things should be orders of magnitude higher. Networked communication is essential to take real advantage of the deployed devices on the battlefield, and to transform the data collected by them into information valuable for the human warfighters. Support for human decision making and even a level of autonomy, allowing devices to coordinate and interact with each other to execute their activities in a collaborative way require continuous communication. Challenges regarding communication will arise from the high dynamics of the environment. The network adaption and management should occur autonomously, and it should reflect upper-level decisions. The large scale of the network connecting high-level echelons, troops on the field, and sensors of many types, beside the lack of communication standards turn the integration of the devices more challenging. In such a heterogeneous environment, many protocols and communication technologies coexist. This way, battlefield networks is an element of paramount importance in modern military operations Additionally, a change of paradigm regarding levels of autonomy and cooperation between humans and machines is in course and the concept of network-centric warfare is a no way back trend. Although new studies have been carried out in this area, most of these concern higher-level strategic networks, with abundant resources. Thus, these studies fail to take into account the “last-mile Tactical Edge Network (TEN) level,” which comprises resource constrained communication devices carried by troopers, sensor nodes deployed on the field or small unmanned aerial vehicles. In an attempt to fill this gap, this work proposes an architecture combining concepts from software-defined networking (SDN) paradigm and the delay-tolerant approach to support applications in the last-mile TEN. First, the use of SDN in dynamic scenarios regarding node positioning is evaluated through a surveillance application using video streaming and Quality of Experience (QoE) measures are captured on the video player. We also explore the election of nodes to act as SDN Controllers in the TEN environment. The experiments use emulator for SDN with support to wireless networks. Further investigation is required, for example, considering security requirements, however the results are promising and demonstrate the applicability of this architecture in the TEN network scenario.

Over the last few years, the concept of civil Unmanned Aircraft System(s) (UAS) has been realised, with small UASs commonly used in industries such as law enforcement, agriculture and mapping. With increased development in other areas, such as logistics and advertisement, the size and range of civil UAS is likely to grow. Taken to the logical conclusion, it is likely that large scale UAS will be operating in civil airspace within the next decade. Although the airborne operations of civil UAS have already gathered much research attention, work is also required to determine how UAS will function when on the ground. Motivated by the assumption that large UAS will share ground facilities with manned aircraft, this thesis describes the preliminary development of an Automated Taxiing System(ATS) for UAS operating at civil aerodromes. To allow the ATS to function on the majority of UAS without the need for additional hardware, a visual sensing approach has been chosen, with the majority of work focusing on monocular image processing techniques. The purpose of the computer vision system is to provide direct sensor data which can be used to validate the vehicle s position, in addition to detecting potential collision risks. As aerospace regulations require the most robust and reliable algorithms for control, any methods which are not fully definable or explainable will not be suitable for real-world use. Therefore, non-deterministic methods and algorithms with hidden components (such as Artificial Neural Network (ANN)) have not been used. Instead, the visual sensing is achieved through a semantic segmentation, with separate segmentation and classification stages. Segmentation is performed using superpixels and reachability clustering to divide the image into single content clusters. Each cluster is then classified using multiple types of image data, probabilistically fused within a Bayesian network. The data set for testing has been provided by BAE Systems, allowing the system to be trained and tested on real-world aerodrome data. The system has demonstrated good performance on this limited dataset, accurately detecting both collision risks and terrain features for use in navigation.

No description available.

[pt] O uso de Veículos Aéreos Não Tripulados (VANTs) na ajuda humanitária tem sido proposto por pesquisadores para localizar vítimas em áreas afetadas por desastres. A urgência desse tipo de operação é encontrar pessoas afetadas o mais rápido possível, o que significa que determinar a roteirização ótima para os VANTs é muito importante para salvar vidas. Como os VANTs tem que percorrer toda a área afetada para encontrar vítimas, a operação de roteirização se torna equivalente a um problema de cobertura. Neste trabalho, uma metodologia para resolver o problema de cobertura é proposta, baseada na heurística do Processo de Decisão de Markov Parcialmente Observável (POMDP), onde as observações feitas pelos VANTs são consideradas. Essa heurística escolhe as ações baseando-se nas informações disponíveis, essas informações são as ações e observações anteriores. A formulação da roteirização do VANT é baseada na ideia de dar prioridades mais altas às áreas mais propensas a terem vítimas. Para aplicar esta técnica em casos reais, foi criada uma metodologia que consiste em quatro etapas. Primeiramente, o problema é modelado em relação à área afetada, tipo de drone que será utilizado, resolução da câmera, altura média do voo, ponto de partida ou decolagem, além do tamanho e prioridade dos estados. Em seguida, a fim de testar a eficiência do algoritmo através de simulações, grupos de vítimas são distribuídos pela área a ser sobrevoada. Então, o algoritmo é iniciado e o drone, a cada iteração, muda de estado de acordo com a heurística POMDP, até percorrer toda a área afetada. Por fim, a eficiência do algoritmo é testada através de quatro estatísticas: distância percorrida, tempo de operação, percentual de cobertura e tempo para encontrar grupos de vítimas. Essa metodologia foi aplicada em dois exemplos ilustrativos: um tornado em Xanxerê, no Brasil, que foi um desastre de início súbito em Abril de 2015, e em um campo de refugiados no Sudão do Sul, um desastre de início lento que começou em 2013. Depois de fazer simulações, foi demonstrado que a solução cobre toda a área afetada por desastres em um período de tempo razoável. A distância percorrida pelo VANT e a duração da operação, que dependem do número de estados, não tiveram um desvio padrão significativo entre as simulações, o que significa que, ainda que existam vários caminhos possíveis devido ao empate das prioridades, o algoritmo tem resultados homogêneos. O tempo para encontrar grupos de vítimas, e portanto o sucesso da operação de resgate, depende da definição das prioridades dos estados, estabelecidas por um especialista. Caso as prioridades sejam mal definidas, o VANT começará a sobrevoar áreas sem vítimas, o que levará ao fracasso da operação de resgate, uma vez que o algoritmo não estará salvando vidas o mais rápido possível. Ainda foi feita uma comparação do algoritmo proposto com o método guloso. A princípio, esse método não cobriu 100 por cento da área afetada, o que tornou a comparação injusta. Para contornar esse problema, o algoritmo guloso foi forçado a percorrer 100 por cento da área afetada e os resultados mostram que o POMDP tem resultados melhores em relação ao tempo para salvar vítimas. Já em relação a distância percorrida e tempo de operação, os resultados são iguais ou melhores para o POMDP. Isso ocorre porque o algoritmo guloso tem o viés de otimizar distância percorrida e, logo, otimiza o tempo de operação. Já o POMDP tem como objetivo, nesta dissertação, salvar vidas e faz isso de forma dinâmica, atualizando sua distribuição de probabilidades a cada observação feita. O ineditismo desta metodologia é ressaltado no capítulo 3, onde mais de 139 trabalhos foram lidos e classificados com o intuito de mostrar quais são as aplicações que drones em logística humanitária, como o POMDP é usado em drones e como a técnica de simulação é utilizada em logística humanitária. Apenas um artigo propõe o u / [en] The use of Unmanned Aerial Vehicles (UAVs) in humanitarian relief has been proposed by researchers for searching victims in disaster affected areas. The urgency of this type of operation is to find the affected people as soon as possible, which means that determining the optimal flight path for UAVs is very important to save lifes. Since the UAVs have to search through the entire affected area to find victims, the path planning operation becomes equivalent to an area coverage problem. In this study, a methodology to solve the coverage problem is proposed, based on a Partially Observable Markov Decision Processes (POMDP) heuristic, which considers the observations made from UAVs. The formulation of the UAV path planning is based on the idea of assigning higher priorities to the areas which are more likely to contain victims. The methodology was applied in two illustrative examples: a tornado in Xanxerê, Brazil, which was a rapid-onset disaster in April 2015 and a refugee s camp in South Sudan, a slow-onset disaster that started in 2013. After simulations, it is demonstrated that this solution achieves full coverage of disaster affected areas in a reasonable time span. The traveled distance and the operation s durations, which are dependent on the number of states, did not have a significative standard deviation between the simulations. It means that even if there were many possible paths, due to the tied priorities, the algorithm has homogeneous results. The time to find groups of victims, and so the success of the search and rescue operation, depends on the specialist s definition of states priorities. A comparison with a greedy algorithm showed that POMDP is faster to find victims while greedy s performance focuses on minimizing the traveled distance. Future research indicates a practical application of the methodology proposed.

A introdução de 33 rainhas africanas (Apis mellifera scutellata) em 1956, com o objetivo de iniciar um programa de seleção e melhoramento genético no Brasil, e a posterior enxameação de algumas destas rainhas, deu inicio ao processo de Africanização, originando o poli-híbrido, denominado, Abelha africanizada. Este processo envolveu uma série de fatores biológicos e ambientais, cujas interações não são suficientemente claras. Os acasalamentos em abelhas melíferas ocorrem em sítios denominados como Áreas de Congregação de Zangões (ACZ), estes locais têm sido bem estudados em abelhas européias, porém, pouco pesquisados em abelhas africanizadas. Assim, é mister a necessidade de desenvolver novos estudos sobre o comportamento reprodutivo destas subespécies, que contribuíram para a rápida expansão das abelhas africanizadas nas Américas. Foram observados os comportamentos de vôos de 10 rainhas (Apis mellifera carnica e Apis mellifera africanizada) e de 126 e 146 zangões de cada raça, respectivamente. Observou-se 6 pontos, localizados no campus da USP de Ribeirão Preto, os quais poderiam ter uma maior concentração de zangões em vôo. Estes pontos foram analisados por meio de uma rainha fecundada presa a um balão preenchido com gás Helio e determinadas características ambientais. Todas as rainhas retornnaram ao núcleo com a marca de acasalamento e iniciaram o processo de postura. Os dados revelaram que não existem diferenças significativas (? = 0,05%) ao compararmos: A idade da rainha no seu primeiro vôo (T=123: P=0,185); a idade da rainha no vôo do acasalamento (t=1,721; P=0,104); o numero de vôos que cada rainha realizou (T=79,5; P=0,789); a duração do vôo de acasalamento (t=1,065; P=0,303); a temperatura no dia do vôo de acasalamento (t=0,263; P=0,796) e o horário do dia no qual ocorrem os vôos de acasalamento (t = 0,0; P=1,0). A atividade de vôo dos zangões carnicos nunca precedeu o horário as 14:15 e 14:30h para zangões carnicos e africanizados, respectivamente, confirmando que não existem diferenças significativas no período do dia em que estes realizam seus vôos (t = -3,11E-015; P = 1,000). Dos 6 pontos observados, somente um ponto não atraiu zangões à isca. Não foram encontrados diferenças significativas entre as diferentes ACZ (P = 0,109). Ao analisar a velocidade do vento (m/s), a analise de variância encontrou diferenças significativas entre as diferentes ACZ (P=<0,001), porém não influenciando a presença de zangões na isca. Dados coletados neste experimento revelaram que os zangões freqüentam estas áreas durante condições de vento superiores a 4 m/s, e em algumas ocasiões com ventos de 8.1 m/s. Também foi observado que os zangões realizam seus vôos de acasalamento em dias nublados e com pouca luminosidade. Não existiu uma preferência, pelos zangões, por determinadas ACZ, constatando-se que o ambiente oferece muitos espaços abertos típicos de ACZ, garantindo e facilitando o acasalamento destas abelhas. / The introduction of 33 African queens ( Apis mellifera scutellata ) in 1956 , aiming to start a program of selection and breeding in Brazil , and later some of these swarming queens , began the process of Africanization , yielding poly - hybrid called , \" Africanized Bee \" . This process involved a number of biological and environmental factors whose interactions are unclear. Mating in honeybees occur at sites referred to as Areas of Congregation Hornets ( ACZ ) , these sites have been well studied in European bees , but little researched in Africanized bees . Thus , it is essential the need to develop new studies on the reproductive behavior of these subspecies, which contributed to the rapid expansion of Africanized bees in the Americas . Behaviors Flight 10 queens ( Apis mellifera and Apis mellifera Africanized carnica ) and 126 and 146 Hornets each race respectively were observed . There was 6 points , located in the USP , Ribeirão Preto , which could have a higher concentration of drones in flight campus . These points were analyzed by means of a fertilized queen attached to a balloon filled with helium and certain environmental characteristics. All queens retornnaram the core branded mating and begun the process of laying. The data revealed no significant differences when comparing : The age of the queen on her first flight (T = 123 : P = 0.185 ) ( = 0.05 % ? ) ; the age of the queen in flight mating ( t = 1.721 , P = 0.104 ) ; the number of flights that each queen performed (T = 79.5 , P = 0.789 ) ; the flight duration of mating ( t = 1.065 , P = 0.303 ) ; the temperature on the mating flight ( t = 0.263 , P = 0.796 ) and time of day in which mating flights occur ( t = 0.0, P = 1.0 ) . Flight activity of CARNICOS Hornets never preceded the hours 14:15 and 14:30 for CARNICOS and Africanized drones, respectively , confirming that there are no significant differences in time of day in which they perform their flights ( t = -3.11 and -015 , P = 1.000) . 6 of the observed points , only one point not attracted to the bait Hornets . No significant differences were found between the different ACZ (P = 0.109 ) . By analyzing the wind speed ( m / s ) , analysis of variance found significant differences between the different ACZ ( P = < 0.001), but not influencing the presence of drones at the bait . Data collected in this experiment revealed that the Hornets frequent these areas during windy conditions exceeding 4 m / s , and on some occasions with winds of 8.1 m / s . It was also observed that the Hornets perform their mating flights on cloudy days and low light . There was a preference by the Hornets , by certain ACZ , noting that if the environment offers many open spaces typical of ACZ , ensuring and facilitating mating these bees.