Les systèmes avioniques sont soumis à de fortes contraintes de criticité et de temps réel. Pour certifier de telssystèmes, il est nécessaire de calculer une borne supérieure du délai de bout en bout de chaque message transmisdans le réseau. Cette thèse se focalise principalement sur l'étude des systèmes avioniques civils utilisant le réseauAFDX (Avionics Full Duplex Switched Ethernet), qui a été par exemple introduit dans l'architecture de l'AirbusA380.Dans ce contexte, nous nous sommes focalisés sur le calcul des délais de bout en bout des messages circulant dansle réseau. Parmi les méthodes existantes, nous nous sommes intéressés à la méthode des trajectoires proposéedans la littérature. Cette méthode permet de calculer des bornes supérieures du temps de traversée des messagesdans les noeuds d'un réseau AFDX. Notre première contribution a été de démontrer que cette méthode peutcalculer des délais bout en bout optimistes. Cette méthode ne peut donc pas sans modification être utilisée pourvalider les délais de bout en bout des messages transmis dans l'AFDX. Malgré l'identification des problèmes ausein de la méthode des trajectoires, il ne nous apparaît pas simple d'apporter une correction aux problèmes misen évidence. Dans un deuxième temps, nous avons proposé une nouvelle approche pour calculer ces délais quirepose sur la caractérisation pire cas du trafic que peut rencontrer un paquet, sur chaque noeud. / Avionics systems are subject to hard real-time constrainst and criticality. To certify these systems, it is neccessaryto compute the upper bound of the end-to-end delay of each message transmitted in the network. In this thesis,we mainly focus on civils avionics systems that use AFDX (Avionics Full Duplex Switched Ethernet) networkand that has been introduced in the Airbus A380 architecture.In this context, we focus in the computation of the end-to-end delays of messages crossing the network. Amongthe existing methods, we interested in the trajectory approach precedently proposed by researchers. The goal ofthis method is to compute end-to-end delay upper bounds of messages in the nodes of AFDX network. As a firstcontribution, we prove that the end-to-end delays computed by this method can be optimistic. This means thatwithout any modification, it cannot be used to validate transmission end-to-end delays for the AFDX. Despitethe identification of these optimistic problems in the trajectory approach, a solution to remove them seems notto be simple from our point of view. Hence, as a second contribution, we propose a new approach to computethese delays based on the characterization of the worst-case traffic encountered by a packet on each crossednode.

Although the importance of early identification and intervention of infants at risk for communication delays and disorders have been advocated and emphasized in literature, case finding and service delivery in rural areas in South Africa appears to be problematic. The implementation of early communication intervention (ECI) within public service delivery has been proposed in the past. The primary health care (PHC) package had to be considered as a possible vehicle to be utilized for the implementation of ECI functions in rural communities. Against this background the existing identification methods and referral systems, utilized in Ditsobotla sub-district, were described in the current study to determine the limitations in case finding, and the feasibility of the implementation of ECI functions in collaboration with other PHC programmes. A descriptive dominant-less-dominant model provided the design to describe the identification process and teamwork in Ditsobotla sub-district. Data triangulation was utilized to improve reliability and validity of results which entailed a rating scale, face-to-face interviews with PHC personnel (participants in Group 1) and face-to-face interviews with PHC programme managers (participants in group 2). The results indicated that the capacity of facilities and human resources to support the implementation of ECI functions vary within the sub-district. Therefore an incremental implementation of ECI functions is feasible in collaboration with the existing PHC package. The current identification methods and referral systems are limited and a great need for collaboration exists. ECI functions need to be implemented formally within the PHC package and guidelines for such an implementation are provided. Furthermore the identification process to be introduced needs to form part of the incremental implementation of ECI functions. The implications are discussed in terms of ECI service delivery in rural South Africa. The proposed process of incremental implementation of ECI functions in rural areas, i.e. Ditsobotla sub-district, within the PHC package is provided. The need to develop identification methods, referral systems and guidelines for the implementation of ECI in PHC are emphasized. Future practice-based research is recommended in order to improve ECI service delivery in rural areas in South Africa. Copyright / Dissertation (MCommunication Pathology)--University of Pretoria, 2009. / Speech-Language Pathology and Audiology / Unrestricted

In this thesis, we first use the reachability theory to develop algorithms for state predictionunder delayed state or output measurements. We next develop control strategies forcollision avoidance and trajectory tracking of UAVs based on the devised algorithms andthe model predictive control theory. Finally, simulations results for collision avoidanceand trajectory tracking problems are presented, for different communication delays,using a UAV model with 6 degrees of freedom. / I denna avhandling använder vi först tillgänglighetsteorin för att utveckla algoritmerför tillståndsförutsägelse under fördröjda tillstånds- eller utgångsmätningar. Därefterutvecklar kontrollstrategier för undvikande av kollision och spårning av UAV: er baseradepå de planerade algoritmerna och modellen förutsägbar kontrollteori. Slutligenpresenteras simuleringsresultat för att undvika kollision och problem med spårningav banan, för olika kommunikationsförseningar, med en UAV-modell med 6 frihetsgrader.

Ce travail concerne la commande des systèmes multi-agent d’ordre fractionnaire utilisant une topologie de communication fixe. Premièrement, la production en formation avec atténuation absolue et retard de communication est étudiée. Pour cela, une loi de commande et des conditions suffisantes sont proposées. Toutefois, dans certains scénarios, il est souhaitable que tous les agents atteignent la formation souhaitée tout en se déplacent en groupe, au lieu d’un rendez-vous à un point fixe. Ce cas sera traité en étudiant la production en formation avec atténuation relative et retard de communication. Troisièmement, la poursuite par consensus des systèmes avec un état de référence variable dans le temps est étudiée. Une loi de commande commune et une seconde basée sur la prédiction d’erreur sont proposées, et le problème du consensus est résolu quand le graphe de communication contient un arbre dirigé. Il a été prouvé que la convergence du système est plus rapide en utilisant la loi basée sur la prédiction d’erreur plutôt que celle de commande commune. Enfin, les lois de commande ci-dessus sont étendues au cas de la poursuite en formation. En effet, dans de nombreux cas, l'information peut être envoyée à partir d'un état de référence vers les agents voisins uniquement et non pas à l’ensemble des agents. Afin de résoudre ce problème, une loi de commande est proposée afin de résoudre le problème du consensus avec un état de référence constant. Puis, deux lois de commande sont proposées afin de résoudre le problème du consensus avec un état de référence variant dans le temps. Ces lois sont étendues pour résoudre le problème de la poursuite en formation / This thesis focuses on the distributed coordination of fractional-order multi-agent systems under fixed directed communication graph. Firstly, formation producing with absolute damping and communication delay of fractional-order multi-agent systems is studied. A control law is proposed and some sufficient conditions are derived for achieving formation producing. However, in some scenarios, it might be desirable that all agents achieve formation and move as a group, instead of rendezvous at a stationary point. Therefore, secondly, formation producing with relative damping and communication delay is considered. Thirdly, consensus tracking of fractional-order multi-agent systems with a time-varying reference state is studied. A common control law and a control law based on error predictor are proposed, and it is shown that the control laws are effective when a communication graph has directed spanning trees. Meanwhile, it is proved that the convergence of systems is faster using the control law based on error predictor than by the common one. Finally, the above control laws are extended to achieve formation-tracking problems. In fact, in many cases information can be sent from a reference state to only its neighbor agents not to all the agents. In order to solve the above problem, an effective control law is given to achieve consensus with a constant reference state. Then, an effective general control law and an effective particular one are proposed to achieve consensus with a time-varying reference state. Furthermore, the above control laws are extended to achieve the formation tracking problems

Communication is vital for humans, and a delay in a child’s communication is not only negative for the individual, but for everyone surrounding them. In Swedish healthcare, communication delays are not always identified during the first important years of a child’s life and that needs to change. Research has shown that early intervention has a greater effect on improving children’s communication. The aim of this study is to investigate the effect of the ComeAlong Toddler parental course on children’s initiation and response to joint attention, compared to a follow up telephone consultation with a speech and language pathologist. In total, the parents of 38 children with communication delays were enrolled in the study and randomised into two groups. The children were all under 2,5 years old. Data has been collected pre- and post-intervention through an assessment carried out by a speech and language pathologist. These assessments were video recorded and coded for joint attention initiated by the child or adult and measured in seconds as well as the number of times the dyad was in joint attention. The result shows statistical significance in adult initiated joint attention when comparing the two groups. The median shows an increase in joint attention in both groups, with a larger increase in the ComeAlong Toddler group. / Att kunna kommunicera med sin omgivning är ett grundläggande behov hos människan. En störning i kommunikationsutvecklingen är inte bara negativt för individen utan också för alla i personens omgivning. Svårigheter i kommunikation uppmärksammas inte alltid under småbarnsåren. Detta är något som bör förändras, då tidigare forskning har visat att intervention i ett tidigt skede har en bättre effekt på kommunikationsutvecklingen. Syftet med denna uppsats är att jämföra KOMiTID-föräldrautbildning med ett uppföljande rådgivningssamtal via telefon gällande gemensam uppmärksamhet mellan barn och vuxen. I studien ingår 38 barn med kommunikationssvårigheter som randomiserats till två grupper. Samtliga barn var yngre än 2,5 år då studien inleddes. Barnens kommunikation bedömdes av logoped vid två tillfällen, före och efter intervention, med cirka sex månaders mellanrum. Dessa bedömningar har filmats och kodats gällande barn- och vuxeninitierad gemensam uppmärksamhet, mätt i sekunder och antal tillfällen. Resultatet visar en statistisk signifikant skillnad mellan grupperna vid andra bedömningstillfället gällande vuxeninitierad gemensam uppmärksamhet. Medianvärdena visar en ökning i gemensam uppmärksamhet hos båda grupperna. Ökningen är störst hos barnen vars vårdnadshavare deltagit i interventionen KOMiTID.

<p>    </p> <p>This thesis studies networked Gaussian linear control systems with random delays. Networked control systems is a popular topic these years because of their versatile applications in daily life, such as smart grid and unmanned vehicles. With the development of these systems, researchers have explored this area in two directions. The first one is to derive the inherent rate-cost relationship in the systems, that is the minimal transmission rate needed to achieve an arbitrarily given stability requirement. The other one is to design achievability schemes, which aim at using as less as transmission rate to achieve an arbitrarily given stability requirement. In this thesis, we explore both directions. We assume the sensor-to-controller channels experience independently and identically distributed random delays of bounded support. Our work separates into two parts. In the first part, we consider networked systems with only one sensor. We focus on deriving a lower bound, R_{LB}(D), of the rate-cost tradeoff with the cost function to be E{| <strong>x^</strong>T<strong>x </strong>|} ≤ D, where <strong>x </strong>refers to the state to be controlled. We also propose an achievability scheme as an upper bound, R_{UB}(D), of the optimal rate-cost tradeoff. The scheme uses lattice quantization, entropy encoder, and certainty-equivalence controller. It achieves a good performance that roughly requires 2 bits per time slot more than R_{LB}(D) to achieve the same stability level. We also generalize the cost function to be of both the state and the control actions. For the joint state-and-control cost, we propose the minimal cost a system can achieve. The second part focuses on to the covariance-based fusion scheme design for systems with multiple > 1 sensors. We notice that in the multi-sensor scenario, the outdated arrivals at the controller, which many existing fusion schemes often discard, carry additional information. Therefore, we design an implementable fusion scheme (CQE) which is the MMSE estimator using both the freshest and outdated information at the controller. Our experiment demonstrates that CQE out-performances the MMSE estimator using the freshest information (LQE) exclusively by achieving a 15% smaller average L2 norm using the same transmission rate. As a benchmark, we also derive the minimal achievable L2 norm, Dmin, for the multi-sensor systems. The simulation shows that CQE approaches Dmin significantly better than LQE. </p>