648 research outputs found
Statistical Learning Approaches to Information Filtering
Enabling computer systems to understand human thinking or
behaviors has ever been an exciting challenge to computer
scientists. In recent years one such a topic, information
filtering, emerges to help users find desired information items (e.g.~movies, books, news) from large amount of available data, and has become crucial in many applications, like product recommendation, image retrieval, spam email filtering, news filtering, and web navigation etc..
An information filtering system must be able to understand users' information needs. Existing approaches either infer a
user's profile by exploring his/her connections to other users, i.e.~collaborative filtering (CF), or analyzing the content descriptions of liked or disliked examples annotated by the user, ~i.e.~content-based filtering (CBF). Those methods work well to some extent, but are facing difficulties due to lack of insights into the problem.
This thesis intensively studies a wide scope of information
filtering technologies. Novel and principled machine
learning methods are proposed to model users' information needs. The work demonstrates that the uncertainty of user profiles and the connections between them can be effectively modelled by using probability theory and Bayes rule. As one major contribution of this thesis, the work clarifies the ``structure'' of information filtering and gives rise to principled solutions. In summary, the work of this thesis mainly covers the following
three aspects:
Collaborative filtering: We develop a probabilistic model for memory-based collaborative filtering (PMCF), which has clear links with classical memory-based CF. Various heuristics to improve memory-based CF have been proposed
in the literature. In contrast, extensions based on PMCF can be made in a principled probabilistic way. With PMCF, we describe a CF paradigm that involves interactions with
users, instead of passively receiving data from users in conventional CF, and actively chooses the most informative patterns to learn, thereby greatly reduce user efforts and computational costs.
Content-based filtering: One major problem for CBF is the
deficiency and high dimensionality of content-descriptive
features. Information items (e.g.~images or articles) are typically described by high-dimensional features with mixed types of attributes, that seem to be developed independently but intrinsically related. We derive a generalized principle component analysis to merge high-dimensional and heterogenous content features into a low-dimensional continuous latent space. The derived features brings great conveniences to CBF, because most existing algorithms easily cope with low-dimensional and continuous data, and more importantly, the extracted data highlight the intrinsic semantics of original content features.
Hybrid filtering: How to combine CF and CBF in an ``smart'' way remains one of the most challenging problems in information filtering. Little principled work exists so far. This thesis reveals that people's information needs can be naturally modelled with a hierarchical Bayesian thinking, where each individual's data are generated based on his/her own profile model, which itself is a sample from a common distribution of the population of user profiles. Users are thus connected to each other via this common distribution. Due to the complexity of such a distribution in real-world applications, usually applied parametric models are too restrictive, and we thus introduce a nonparametric hierarchical Bayesian model using Dirichlet process. We derive effective and efficient algorithms to learn the described model. In particular, the finally achieved hybrid filtering methods are surprisingly simple and intuitively understandable, offering clear insights to previous work on pure CF, pure CBF, and hybrid filtering
Realizing pervasive compution vision: A context-aware mobile application approach.
Ph.DDOCTOR OF PHILOSOPH
Geoinformatics in Citizen Science
The book features contributions that report original research in the theoretical, technological, and social aspects of geoinformation methods, as applied to supporting citizen science. Specifically, the book focuses on the technological aspects of the field and their application toward the recruitment of volunteers and the collection, management, and analysis of geotagged information to support volunteer involvement in scientific projects. Internationally renowned research groups share research in three areas: First, the key methods of geoinformatics within citizen science initiatives to support scientists in discovering new knowledge in specific application domains or in performing relevant activities, such as reliable geodata filtering, management, analysis, synthesis, sharing, and visualization; second, the critical aspects of citizen science initiatives that call for emerging or novel approaches of geoinformatics to acquire and handle geoinformation; and third, novel geoinformatics research that could serve in support of citizen science
Training of Crisis Mappers and Map Production from Multi-sensor Data: Vernazza Case Study (Cinque Terre National Park, Italy)
This aim of paper is to presents the development of a multidisciplinary project carried out by the cooperation between Politecnico di Torino and ITHACA (Information Technology for Humanitarian Assistance, Cooperation and Action). The goal of the project was the training in geospatial data acquiring and processing for students attending Architecture and Engineering Courses, in order to start up a team of "volunteer mappers". Indeed, the project is aimed to document the environmental and built heritage subject to disaster; the purpose is to improve the capabilities of the actors involved in the activities connected in geospatial data collection, integration and sharing. The proposed area for testing the training activities is the Cinque Terre National Park, registered in the World Heritage List since 1997. The area was affected by flood on the 25th of October 2011. According to other international experiences, the group is expected to be active after emergencies in order to upgrade maps, using data acquired by typical geomatic methods and techniques such as terrestrial and aerial Lidar, close-range and aerial photogrammetry, topographic and GNSS instruments etc.; or by non conventional systems and instruments such us UAV, mobile mapping etc. The ultimate goal is to implement a WebGIS platform to share all the data collected with local authorities and the Civil Protectio
Mapping and the Citizen Sensor
Maps are a fundamental resource in a diverse array of applications ranging from everyday activities, such as route planning through the legal demarcation of space to scientific studies, such as those seeking to understand biodiversity and inform the design of nature reserves for species conservation. For a map to have value, it should provide an accurate and timely representation of the phenomenon depicted and this can be a challenge in a dynamic world. Fortunately, mapping activities have benefitted greatly from recent advances in geoinformation technologies. Satellite remote sensing, for example, now offers unparalleled data acquisition and authoritative mapping agencies have developed systems for the routine production of maps in accordance with strict standards. Until recently, much mapping activity was in the exclusive realm of authoritative agencies but technological development has also allowed the rise of the amateur mapping community. The proliferation of inexpensive and highly mobile and location aware devices together with Web 2.0 technology have fostered the emergence of the citizen as a source of data. Mapping presently benefits from vast amounts of spatial data as well as people able to provide observations of geographic phenomena, which can inform map production, revision and evaluation. The great potential of these developments is, however, often limited by concerns. The latter span issues from the nature of the citizens through the way data are collected and shared to the quality and trustworthiness of the data. This book reports on some of the key issues connected with the use of citizen sensors in mapping. It arises from a European Co-operation in Science and Technology (COST) Action, which explored issues linked to topics ranging from citizen motivation, data acquisition, data quality and the use of citizen derived data in the production of maps that rival, and sometimes surpass, maps arising from authoritative agencies
Proceedings of the GIS Research UK 18th Annual Conference GISRUK 2010
This volume holds the papers from the 18th annual GIS Research UK (GISRUK). This year the conference, hosted at University College London (UCL), from Wednesday 14 to Friday 16 April 2010. The conference covered the areas of core geographic information science research as well as applications domains such as crime and health and technological developments in LBS and the geoweb.
UCL’s research mission as a global university is based around a series of Grand Challenges that affect us all, and these were accommodated in GISRUK 2010.
The overarching theme this year was “Global Challenges”, with specific focus on the following themes:
* Crime and Place
* Environmental Change
* Intelligent Transport
* Public Health and Epidemiology
* Simulation and Modelling
* London as a global city
* The geoweb and neo-geography
* Open GIS and Volunteered Geographic Information
* Human-Computer Interaction and GIS
Traditionally, GISRUK has provided a platform for early career researchers as well as those with a significant track record of achievement in the area. As such, the conference provides a welcome blend of innovative thinking and mature reflection. GISRUK is the premier academic GIS conference in the UK and we are keen to maintain its outstanding record of achievement in developing GIS in the UK and beyond
Furthering perspectives
Includes bibliographical references.Fair trade, women’s empowerment, and international development / Shadi Azadegan -- Development within a developed country: how economic growth creates economic and social inequality / Kara Lentz -- Ethical consumption: moral sentiment and the capitalist market / Stefanie Berganini -- The decline of swidden in Southeast Asia under changing property regimes: assessing political-economic drivers of land-use/land-cover change and associated human-environment impacts / Kirk Saylor -- Climate change and food security: nutrition and health impacts on women and children in Sub-Saharan Africa / Shadi Azadegan -- “Indians don’t get transplants”: barriers in accessing kidney transplantation on the Pine Ridge Indian Reservation / Julia Reedy -- Mismatch and the effects of hormonal contraceptives on breast cancer risk / Ashley Snyder -- Just scraping by: an analysis of unifacial tool reduction from Pack Rat Shelter (5LR170) / Nick Simpson -- Lasers through the leaves: an overview of LiDAR applications in archaeology for forested regions / Alex Friedl -- Identification Of Kaplan-Hoover projectile point assemblage: a geometric morphometric analysis / Edwin Harris
Cognitive aspects of work with digital maps
Digital maps of geographic areas are increasingly common in many types of
workplace, in education and in the public domain. Their interactivity and visual
features, and the complexity of geographic(al) information systems (GIS) which
create, edit and manipulate them, create special cognitive demands on the end-user
which are not present in traditional cartographic maps or in most human-computer
interaction (HCI). This thesis reviews cross-disciplinary literature regarding cognitive
aspects of viewing and interacting with digital maps.
Data from an observational study of GIS use, including real-time recordings of
normal workplace activities, was analysed using various approaches to examine the
interactive and visual aspects of people's work. The implications for cartographic,
psychological and HeI aspects of GIS are discussed, in the context of the actual tasks
people perform with them (rather than the computationally advanced analyses
assumed by most literature).
The second phase of the research examined the spatial knowledge attained and used
during this interaction. The relevance of specific concepts in cognitive psychology,
and of factors that create individual differences in cognition, are discussed in depth,
alongside work in environmental and educational psychology, cartography and
geography.
A controlled experiment examined the degree to which task characteristics induce a
different spatial model or reference frame when viewing a digital map. It was shown
that even novice users can switch between considering the map as an abstract
geometric display or as a geographical representation, without affecting performance.
However, tasks forcing subjects to focus entirely on the geometry rather than the
geography did affect performance in a surprise post-test photograph identification
task. Map users' mental model or reference frame is apparently affected by these task
constraints; this has implications for GIS design and practice as well as for
understanding spatial cognition The study also considered the role of expertise and
other individual difference factors, although conclusions were limited by sample size.
Further research issues are highlighted, particularly regarding the knowledge
structures and spatial language used in interpreting digital maps
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