Resonant inductive coupling wireless power transfer

Recent research on wireless power transfer (WPT) using resonant inductive coupling has demonstrated very promising efficiencies (above 80%) [1] at large distances compared to the antenna dimensions (more than three times the receiver/transmitter diameters). Due to the number of applications that could benefit from WPT: from electric vehicles to sensor networks, commercial electronic devices, health equipment, biomedical implants, in-space systems and so on, the development and optimization of this technology is of great interest. Since RIC is still a very novel technology, different models should be proposed to analyze and predict the behavior of these systems and to increase the overall efficiencies and transmission ranges.Postprint (published version

Applying autonomy to distributed satellite systems: Trends, challenges, and future prospects

While monolithic satellite missions still pose significant advantages in terms of accuracy and operations, novel distributed architectures are promising improved flexibility, responsiveness, and adaptability to structural and functional changes. Large satellite swarms, opportunistic satellite networks or heterogeneous constellations hybridizing small-spacecraft nodes with highperformance satellites are becoming feasible and advantageous alternatives requiring the adoption of new operation paradigms that enhance their autonomy. While autonomy is a notion that is gaining acceptance in monolithic satellite missions, it can also be deemed an integral characteristic in Distributed Satellite Systems (DSS). In this context, this paper focuses on the motivations for system-level autonomy in DSS and justifies its need as an enabler of system qualities. Autonomy is also presented as a necessary feature to bring new distributed Earth observation functions (which require coordination and collaboration mechanisms) and to allow for novel structural functions (e.g., opportunistic coalitions, exchange of resources, or in-orbit data services). Mission Planning and Scheduling (MPS) frameworks are then presented as a key component to implement autonomous operations in satellite missions. An exhaustive knowledge classification explores the design aspects of MPS for DSS, and conceptually groups them into: components and organizational paradigms; problem modeling and representation; optimization techniques and metaheuristics; execution and runtime characteristics and the notions of tasks, resources, and constraints. This paper concludes by proposing future strands of work devoted to study the trade-offs of autonomy in large-scale, highly dynamic and heterogeneous networks through frameworks that consider some of the limitations of small spacecraft technologies.Postprint (author's final draft

A comparison of analytical models for resonant inductive coupling wireless power transfer

Recent research in wireless power transfer (WPT) using resonant inductive coupling has demonstrated very high e±ciencies (above 40%) at large distances compared to the antenna dimensions, which has exponentially increased the number of potential applications of WPT. Since resonant inductive coupling is a very multidisciplinary ¯eld, di®erent approaches have been proposed to predict the behaviour of these systems from physical theory of resonators, reflected load theory and the circuit point of view. However, the relation between these methods is still obscure. In this article, we compare the results of these models to find the effciency of a Resonant Inductive Coupling WPT system under Steady-State sonditions and to analyze the relation between the optimal load values obtained from this perspectives and the ones obtained using impedance matching techniques.Peer ReviewedPostprint (published version

Applying autonomy to distributed satellite systems

The need for autonomy in several fields of aerospace engineering has become apparent and widely accepted during the last decade. Autonomy promises to improve the systems' performances, their robustness and tolerance to failures, reduce operational costs and, ultimately increase the intelligence of the system. Many are the researchers that have tackled the design and implementation of autonomy technologies for system-specific purposes: from the control of a UAV fleet or the coordination of a team of robots, to the implementation of spacecraft FDIR techniques. In the area of satellite missions, autonomous systems may drastically reduce their response times when in the presence of internal perturbations (e.g. subsystem failures), or external changes (i.e. changes in the environment) and may allow new monitoring approaches such as the on-board identification of interesting targets (e.g. autonomous detection of natural disasters, crop and forest change detection, etc.) Autonomy has been deemed essential in the design and deployment of several distributed satellite architectures, especially for Earth Observation applications. The latter systems, grounded on small spacecraft technologies, potentially present node heterogeneity at the functional level as well as in terms of computational and communication capabilities. This, combined with some of their network characteristics (which are dynamic and are affected by the node's orbital properties) and architectural aspects (potentially hierarchically structured and composed of a massive number of spacecraft), enforces the need of autonomous operations. Finally, the absence of autonomy in Distributed Satellite Systems (DSS) architectures, not only could compromise their controllability but could complicate the operational requirements unnecessarily. This presentation is aimed at gathering the design, functional and execution aspects of autonomous mission planning software for DSS architectures and to identifying open issues that still need to be solved. In the context of distributed satellite architectures, autonomy may be translated as the capability of the system to plan its own activities and observational requests with minimum human intervention. Mission Planning and scheduling Systems (MPS) have been exhaustively explored to provide this capability to the system. Their design, modelling and execution characteristics, however, are particular to the missions for which they were developed and are usually not targeted for new and complex functions that next-generation architectures are aimed to address (e.g. multi-point observations, synchronization of nodes, exchange and management of infrastructure resources, on-board generation of observational requests, self-healing properties, etc.) Some authors have scrupulously identified the commonalities of MPS for monolithic satellite missions, but their characteristics and requirements for DSS are still unexplored. Because of that, this presentation will emphasize their characteristics in that specific context. Leveraging from the commonalities found in several MPS designs, this presentation will summarize: (a) their fundamental design approaches, ranging from the implementation of negotiation protocols, or multi-agent paradigms to bio-inspired and self-organizing applications; (b) their problem, resource and task modelling, including common algorithms and optimization schemes; and (c) their runtime characteristics (i.e. reactive or deliberative, centralized or distributed). From there, the presentation will conclude discussing the open questions and unsolved features with a focus on small-satellite limitations, network issues and collaborative task requirements, and will propose a roadmap for their resolution.Postprint (author's final draft

Magnetic characterization of interfering objects in resonant inductive coupling wireless power transfer

Resonant Inductive Coupling (RIC) Wireless Power Transfer is a key technology to provide an efficient and harmless wireless energy channel to consumer electronics, biomedical implants and wireless sensor networks. However, there are two factors that are limiting the applicability of this technology: the effects of distance variation between transmitter and receiver and the effects of interfering objects. While distance variation in WPT has been thoroughly studied, the effects of conductive interfering objects in resonant inductive coupling links are still unclear. When a conductive element is in the vicinity of a RIC link, both the transmitter and the receiver can experiment a change on their resonant frequencies as well as their impedances. This can greatly affect the efficiency of such WPT link causing it to a) make the transmitter and/or receiver act as a pass-band filter and b) loose part of the transmitter magnetic field through coupling to the interfering object. Depending on the natural resonant frequency of the object and the distances between this object and the transmitter and receiver antennas, this can affect significantly the RIC wireless power transfer link. In this article, we characterize the Magnetic behavior of a resonant inductive coupled link in the presence of a conductive interfering object using a Finite Element Field Solver (FEKO). Several distances between interference and transmitter/receiver are analyzed providing a design space exploration and applicability study of this link.Peer ReviewedPostprint (published version

ViTS: Video tagging system from massive web multimedia collections

The popularization of multimedia content on the Web has arised the need to automatically understand, index and retrieve it. In this paper we present ViTS, an automatic Video Tagging System which learns from videos, their web context and comments shared on social networks. ViTS analyses massive multimedia collections by Internet crawling, and maintains a knowledge base that updates in real time with no need of human supervision. As a result, each video is indexed with a rich set of labels and linked with other related contents. ViTS is an industrial product under exploitation with a vocabulary of over 2.5M concepts, capable of indexing more than 150k videos per month. We compare the quality and completeness of our tags with respect to the ones in the YouTube-8M dataset, and we show how ViTS enhances the semantic annotation of the videos with a larger number of labels (10.04 tags/video), with an accuracy of 80,87%.Postprint (published version

VLX-Stories: a semantically linked event platform for media publishers

In the recent years, video sharing in social media from different video recording devices has resulted in a exponential growth of videos on the Internet. Such video data is continuously increasing with daily recordings related to a wide number of topics. In this context, video understanding has become a critical problem to address. Video search and indexation benefits from the use of keyword tags related to the video content, but most of the shared video content does not contain these tags. Although the use of deep learning has become essential for image analysis in several areas, video domain is still a relatively unexplored field for these type of methods. On the other hand knowledge graphs as Freebase or WordNet store high quantities of information about the word and relations that can be used to disambiguate concepts and relate them through contextual information In this research project we search to explore and improve the understanding of video content through the use of automatic tagging models based on Machine Learning and Deep Learning techniques, improved by the use of knowledge bases.Peer ReviewedPostprint (published version

Designing CDIO capstone projects: a systems thinking approach

Given the all-pervasiveness of Systems thinking -which consists of thinking about things as systemsas a way of reasoning, in this work we will describe its application to make an interpretation of how to conceive and design a final year CDIO capstone course. Both the student teamwork structure as well as the complex engineering system itself addressed in the project are described in terms of entities, links, form and function, thereby pointing out their formal and functional interaction. The ultimate goal of the Systems thinking perspective is, given the necessary ingredients, to try maximizing the chances of the emergence of a fruitful capstone course, namely a culminating project that yields a set of students qualified to CDIO complex engineering systems.Peer ReviewedPostprint (published version