Intelligent Information Interaction for Managing Distributed Collections of Web Documents

Digital collections are ubiquitous. However, not all digital collections are the same. While most digital collections have limited forms of change - primarily creation and deletion of additional resources - there exists a class of digital collections that undergo additional kinds of change. These collections are made up of resources that are distributed across the Internet and brought together into the collection via hyperlinking. This means the underlying collection members are not controlled by the curator of the collection. Resources can be expected to change as time goes on. To further complicate matters these collections can be hard to maintain when they are large, highly dynamic, or lacking active curation. Part of the difficulty in maintaining these collections is determining if a changed page is still a valid member of the collection. While others have tried to address this problem by measuring change and defining a maximum allowed threshold of change, these methods treat all change as a potential problems and treat web content as a static document despite its intrinsically dynamic nature. Instead, I approach the problem of determining significance of change on the web by embracing it as a normal part of a web document's lifecycle, Instead of using thresholds to identify abnormal changes, I determine the difference between what a maintainer expects a page to do and what it actually does. These models are created using a variety of feature extractors to find pertinent information in a page, a Kalman filter to model the history of a page and predict a next version and finally classification of results into either expected or unexpected change. I evaluate the different options for extractors and analyzers to determine the best options from my suite of possibilities. This work is informed by a series of studies on both web pages and potential collection maintainers, observations of the NSDL Pathways, and a ground-truth set of blog changes tagged by a human judgment of the kind of change. The results of this work showed a statistically significant improvement over a range of traditional threshold techniques when applied to the collection of tagged blog changes

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

Online Connectivity : A Social Study of Educators’ Affinity for Teaching and Learning Using Social Media

This qualitative study investigated an online space for educators, known as #sschat, for the purpose of helping to inform and shape more formal professional learning experiences. Participants were able to engage in asynchronous and synchronous discussions related to social studies education by interacting in any of the four hashtags associated with the #sschat affinity space (i.e., #engsschat, #hsgovchat, #sschat, #worldgeochat), the #sschat Facebook page, the archived #chat sessions, and/or by contributing to the creation of the weekly #worldgeochat questions. Seven common elements of Gee’s affinity spaces conceptual framework were used to frame this study. This framework drew attention to the practices of self-directed learners who were guided by their passions related to teaching and learning. By engaging as an insider during this one-month study of #sschat, I was able to consider what was happening in this affinity space from the participants’ perspective. I collected and analyzed more than 6,000 tweets and almost 300 Facebook posts along with the websites associated with the #sschat affinity space and shared by the participants. The question that guided this study was: what could be learned from online spaces such as #sschat that can help inform and shape more formal professional development experiences. Through a deep analysis of the data, three important findings emerged that help to provide insight into the types of experiences that are likely to be valued by educators and conducive to learning. The first finding concerns how the diverse experiences and needs of the participants seemed to affect the interactions that occurred in the #sschat affinity space. The second key finding involved how the combination of social media platforms and functions, participants’ knowhow and experiences, and their practices appeared to contribute to a participatory environment that facilitated a wide range of interactions in support of social studies education. The third key finding of my study suggests that professional learning is a personal experience; educators want the ability to choose with whom they interact, the design of the space, and the manner in which they engage in these experiences. Digital technologies were leveraged by participants making it possible for them to engage in crowdsourcing, reflective thinking, and role-shifting activities. This study expands the notion of affinity spaces beyond a space for individuals to engage in activities involving their personal interests and passions. A deep analysis of the data suggests that affinity spaces may also be beneficial for professionals, such as educators who want to engage in experiences involving teaching and learning

A Wearable Indoor Navigation System for Blind and Visually Impaired Individuals

Indoor positioning and navigation for blind and visually impaired individuals has become an active field of research. The development of a reliable positioning and navigational system will reduce the suffering of the people with visual disabilities, help them live more independently, and promote their employment opportunities. In this work, a coarse-to-fine multi-resolution model is proposed for indoor navigation in hallway environments based on the use of a wearable computer called the eButton. This self-constructed device contains multiple sensors which are used for indoor positioning and localization in three layers of resolution: a global positioning system (GPS) layer for building identification; a Wi-Fi - barometer layer for rough position localization; and a digital camera - motion sensor layer for precise localization. In this multi-resolution model, a new theoretical framework is developed which uses the change of atmospheric pressure to determine the floor number in a multistory building. The digital camera and motion sensors within the eButton acquire both pictorial and motion data as a person with a normal vision walks along a hallway to establish a database. Precise indoor positioning and localization information is provided to the visually impaired individual based on a Kalman filter fusion algorithm and an automatic matching algorithm between the acquired images and those in the pre-established database. Motion calculation is based on the data from motion sensors is used to refine the localization result. Experiments were conducted to evaluate the performance of the algorithms. Our results show that the new device and algorithms can precisely determine the floor level and indoor location along hallways in multistory buildings, providing a powerful and unobtrusive navigational tool for blind and visually impaired individuals

Altitude Control System for Indoor Airship

The indoor airship is designed to estimate direction and altitude using dead reckoning techniques. Sensors such as gyroscopes and accelerometers provide measurements affected by biases and additive noise. Degradation of accuracy produced by these errors is corrected using independent measurements from ultrasonic range finder, barometer and magnetometer that are supplied to the Kalman filter. A real-time fuzzy logic controller uses the statistical best estimate to perform a feedback control loop. As result the airship is capable of maintaining the altitude in a range of 5cm from the set point

Exploring space situational awareness using neuromorphic event-based cameras

The orbits around earth are a limited natural resource and one that hosts a vast range of vital space-based systems that support international systems use by both commercial industries, civil organisations, and national defence. The availability of this space resource is rapidly depleting due to the ever-growing presence of space debris and rampant overcrowding, especially in the limited and highly desirable slots in geosynchronous orbit. The field of Space Situational Awareness encompasses tasks aimed at mitigating these hazards to on-orbit systems through the monitoring of satellite traffic. Essential to this task is the collection of accurate and timely observation data. This thesis explores the use of a novel sensor paradigm to optically collect and process sensor data to enhance and improve space situational awareness tasks. Solving this issue is critical to ensure that we can continue to utilise the space environment in a sustainable way. However, these tasks pose significant engineering challenges that involve the detection and characterisation of faint, highly distant, and high-speed targets. Recent advances in neuromorphic engineering have led to the availability of high-quality neuromorphic event-based cameras that provide a promising alternative to the conventional cameras used in space imaging. These cameras offer the potential to improve the capabilities of existing space tracking systems and have been shown to detect and track satellites or ‘Resident Space Objects’ at low data rates, high temporal resolutions, and in conditions typically unsuitable for conventional optical cameras. This thesis presents a thorough exploration of neuromorphic event-based cameras for space situational awareness tasks and establishes a rigorous foundation for event-based space imaging. The work conducted in this project demonstrates how to enable event-based space imaging systems that serve the goals of space situational awareness by providing accurate and timely information on the space domain. By developing and implementing event-based processing techniques, the asynchronous operation, high temporal resolution, and dynamic range of these novel sensors are leveraged to provide low latency target acquisition and rapid reaction to challenging satellite tracking scenarios. The algorithms and experiments developed in this thesis successfully study the properties and trade-offs of event-based space imaging and provide comparisons with traditional observing methods and conventional frame-based sensors. The outcomes of this thesis demonstrate the viability of event-based cameras for use in tracking and space imaging tasks and therefore contribute to the growing efforts of the international space situational awareness community and the development of the event-based technology in astronomy and space science applications