38 research outputs found
Algorithms for Data Dissemination and Collection
Broadcasting and gossiping are classical problems that have been
widely studied for decades. In broadcasting, one source node wishes to
send a message to every other node, while in gossiping, each node has
a message that they wish to send to everyone else. Both are some of
the most basic problems arising in communication networks. In this
dissertation we study problems that generalize gossiping and
broadcasting. For example, the source node may have several messages
to broadcast or multicast. Many of the works on broadcasting in the
literature are focused on homogeneous networks. The algorithms
developed are more applicable to managing data on local-area
networks. However, large-scale storage systems often consist of
storage devices clustered over a wide-area network. Finding a suitable
model and developing algorithms for broadcast that recognize the
heterogeneous nature of the communication network is a significant part of
this dissertation.
We also address the problem of data collection in a wide-area network,
which has largely been neglected, and is likely to become more
significant as the Internet becomes more embedded in everyday life. We
consider a situation where large amounts of data have to be moved from
several different locations to a destination. In this work, we focus
on two key properties: the available bandwidth can fluctuate, and the
network may not choose the best route to transfer the data between two
hosts.
We focus on improving the task completion time by re-routing the data
through intermediate hosts and show that under certain network
conditions we can reduce the total completion time by a factor of
two. This is done by developing an approach for computing coordinated
data collection schedules using network flows
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Ray Tracing Gems
This book is a must-have for anyone serious about rendering in real time. With the announcement of new ray tracing APIs and hardware to support them, developers can easily create real-time applications with ray tracing as a core component. As ray tracing on the GPU becomes faster, it will play a more central role in real-time rendering. Ray Tracing Gems provides key building blocks for developers of games, architectural applications, visualizations, and more. Experts in rendering share their knowledge by explaining everything from nitty-gritty techniques that will improve any ray tracer to mastery of the new capabilities of current and future hardware. What you'll learn: The latest ray tracing techniques for developing real-time applications in multiple domains Guidance, advice, and best practices for rendering applications with Microsoft DirectX Raytracing (DXR) How to implement high-performance graphics for interactive visualizations, games, simulations, and more Who this book is for: Developers who are looking to leverage the latest APIs and GPU technology for real-time rendering and ray tracing Students looking to learn about best practices in these areas Enthusiasts who want to understand and experiment with their new GPU
Exploring multi-granular documentation strategies for the representation, discovery and use of geographic information
This thesis explores how digital representations of geography and Geographic
Information (GI) may be described, and how these descriptions facilitate the use of
the resources they depict. More specifically, it critically examines existing geospatial
documentation practices and aims to identify opportunities for refinement therein,
whether when used to signpost those data assets documented, for managing and
maintaining information assets, or to assist in resource interpretation and
discrimination. Documentation of GI can therefore facilitate its utilisation; it can be
reasonably expected that by refining documentation practices, GI hold the potential
for being better exploited. The underpinning theme connecting the individual papers
of the thesis is one of multi-granular documentation. GI may be recorded at varying
degrees of granularity, and yet traditional documentation efforts have predominantly
focussed on a solitary level (that of the geospatial data layer). Developing
documentation practices to account for other granularities permits the description of
GI at different levels of detail and can further assist in realising its potential through
better discovery, interpretation and use. One of the aims of the current work is to
establish the merit of such multi-granular practices. Over the course of four research
papers and a short research article, proprietary as well as open source software
approaches are accordingly presented and provide proof-of-concept and conceptual
solutions that aim to enhance GI utilisation through improved documentation
practices. Presented in the context of an existing body of research, the proposed
approaches focus on the technological infrastructure supporting data discovery, the
automation of documentation processes and the implications of describing geospatial
information resources of varying granularity. Each paper successively contributes to the notion that geospatial resources are potentially better exploited when
documentation practices account for the multi-granular aspects of GI, and the
varying ways in which such documentation may be used. In establishing the merit of
multi-granular documentation, it is nevertheless recognised in the current work that
instituting a comprehensive documentation strategy at several granularities may be
unrealistic for some geospatial applications. Pragmatically, the level of effort
required would be excessive, making universal adoption impractical. Considering
however the ever-expanding volumes of geospatial data gathered and the demand for
ways of managing and maintaining the usefulness of potentially unwieldy
repositories, improved documentation practices are required. A system of
hierarchical documentation, of self-documenting information, would provide for
information discovery and retrieval from such expanding resource pools at multiple
granularities, improve the accessibility of GI and ultimately, its utilisation
TOWARD SYMBIOTIC HUMAN-AI INTERACTION FOCUSING ON PROGRAMMING BY EXAMPLE
Programming has become a new literacy, but is still inaccessible to ordinary people. Programming-by-example (PBE) is an alternative approach that allows people to teach computers repetitive tasks by demonstrating couple input and output examples of the tasks. While the advancements of PBE have been mainly driven by algorithmic improvements, a growing community of researchers started realizing the importance of issues on the human side of PBE. For instance, inexperienced users often find it hard to provide complete and consistent examples, which is crucial for computers to learn the correct programs. Unfortunately, most PBE systems have limited ways to communicate with users about what it can or cannot do, and how to handle unsuccessful situations. The lack of symbiotic interaction between human users and PBE engines remain as a major hurdle against a widespread adoption of PBE techniques.
To address the issues on the human side of PBE, this dissertation has four research threads. First, we began with two formative studies to establish a better understanding of inexperienced users' needs and mental models. Second, based on the findings of the formative studies, we developed a Visual Environment for Symbiotic Programming, called VESPY. VESPY interleaves visual programming and PBE techniques, enabling users (1) to decompose complex tasks into small modules on its 2-d grid, and (2) to complete each module by providing input and output examples. Four sample programs demonstrate VESPY's remarkable versatility. However, we also noticed that VESPY still had a number of usability issues. Third, to better understand the usability issues and how to help users out from common mistakes, we conducted an online user study that observed how inexperience users perform program decomposition and disambiguation, which are the two core activities of PBE. We identified seven types of mistakes, and reaffirmed that informative feedback on those mistakes is crucial for designing usable systems. Finally, we explored the design space of feedback components, in order to understand their impact on user's experience.
My dissertation contributes to the AI and HCI communities with: (i) identification of unmet needs of end-users of the Web; (ii) characterization of non-programmers’ mental model; (iii) design process of interleaving visual programming and PBE; (iv) identification of mistakes people make while using PBE; and (v) design and assessment of feedback components for PBE users
Credibility assessment and labelling of map mashups
The Web 2.0 revolution has changed the culture of mapping by opening it up to a wider range of users and creators. Map mashups, in particular, are being widely used to map variety of information. There is, however, no gatekeeper to validate the correctness of the information presented. The purpose of this research was to understand better what it is that influence users’ perceived credibility and trust within a map mashup presentation and to support the future implementation of automated credibility assessment and labelling of map mashup applications.
This research has been conducted in three stages using mixed method approaches. The objective of the first stage was to examine the influence of metadata related to sources, specifically the map producer and map supplier, on respondents’ assessment of the credibility of map mashup information. The findings indicate a low influence of the tested metadata and a high influence of visual cue elements on users’ credibility assessment. Only half of the respondents used the metadata whilst the other half did not include it in their assessment.
These findings became the basis of stage two, which was to examine the influence of colour coded traffic light (CCTL) labelling on respondents’ assessment of credibility. From the findings, the probability of respondents making informed judgements by choosing a high credibility map based on this rating label (CCTL) was three times higher than where only the metadata was presented.
The third stage was to propose a conceptual framework to support the implementation of automated credibility labelling for map mashup applications. The framework was proposed on the basis of thorough reviews from the literature. The suggested parameters and approaches are not limited to assess credibility of information in the map mashup context, but could be applied to other Web GIS applications