424 research outputs found
Assessing the quality of land system models: moving from valibration to evaludation
Reviews suggest that evaluation of land system models is largely inadequate, with undue reliance on a vague concept of validation. Efforts to improve and standardise evaluation practices have so far had limited effect. In this article we examine the issues surrounding land system model evaluation and consider the relevance of the TRACE framework for environmental model documentation. In doing so, we discuss the application of a comprehensive range of evaluation procedures to existing models, and the value of each specific procedure. We develop a tiered checklist for going beyond what seems to be a common practice of ‘valibration’ (the repeated variation of model parameter values to achieve agreement with data) to achieving ‘evaludation’ (the rigorous, broad-based assessment of model quality and validity). We propose the Land Use Change – TRACE (LUC-TRACE) model evaludation protocol and argue that engagement with a comprehensive protocol of this kind (even if not this particular one) is valuable in ensuring that land system model results are interpreted appropriately. We also suggest that the main benefit of such formalised structures is to assist the process of critical thinking about model utility, and that the variety of legitimate modelling approaches precludes universal tests of whether a model is ‘valid’. Evaludation is therefore a detailed and subjective process requiring the sustained intellectual engagement of model developers and users
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
2023-2024 academic bulletin & course catalog
University of South Carolina Aiken publishes a catalog with information about the university, student life, undergraduate and graduate academic programs, and faculty and staff listings
Spatial delineation of urban corridors in North America: An approach incorporating fuzziness based on multi-source geospatial data
Urban corridors are – from a spatial perspective – massively large, linear urban agglomerations consisting of a number of big cities or clusters aligned along high-speed road or rail lines. Fixed administrative boundaries are commonly used to define such urban areas. However, this does not usually reflect the actual extent of the built-up space in today's changing, multi-faceted urban landscape. Earth observation data provide the means to identify urban space in its spatial dimension, disregarding preconceived boundaries. We therefore use multi-source geodata including night-time lights, settlement patterns and population density to spatially delineate large
urban corridors in the United States and parts of Canada and Mexico. Using pre-classified input layers, we identify and present varying outlines of 14 urban corridors through geospatial methods. With this approach, we address spatial ambiguities of such concepts and show fuzziness at the edges of these corridors
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A seven-step guide to spatial, agent-based modelling of tumour evolution
Spatial agent-based models are increasingly used to investigate the evolution of solid tumours subject to localised cell-cell interactions and microenvironmental heterogeneity. Here we present a non-technical step by step guide to developing such a model from first principles, aimed at both aspiring modellers and other biologists and oncologists who wish to understand the assumptions and limitations of this approach. Stressing the importance of tailoring the model structure to that of the biological system, we describe methods of increasing complexity, from the basic Eden growth model up to off-lattice simulations with diffusible factors. We examine choices that unavoidably arise in model design, such as implementation, parameterisation, visualisation, and reproducibility. Each topic is illustrated with examples drawn from recent research studies and state of the art modelling platforms. We emphasise the benefits of simpler models that aim to match the complexity of the phenomena of interest, rather than that of the entire biological system
Survival and complete convergence for a branching annihilating random walk
We study a discrete-time branching annihilating random walk (BARW) on the -dimensional lattice. Each particle produces a Poissonian number of offspring with mean which independently move to a uniformly chosen site within a fixed distance from their parent's position. Whenever a site is occupied by at least two particles, all the particles at that site are annihilated. We prove that for any the process survives when is sufficiently large. For fixed we show that the process dies out if is too small or too large. Furthermore, we exhibit an interval of -values for which the process survives and possesses a unique non-trivial ergodic equilibrium for sufficiently large. We also prove complete convergence for that case
Mobility-aware fog computing in dynamic networks with mobile nodes: A survey
Fog computing is an evolving paradigm that addresses the latency-oriented performance and spatio-temporal issues of the cloud services by providing an extension to the cloud computing and storage services in the vicinity of the service requester. In dynamic networks, where both the mobile fog nodes and the end users exhibit time-varying characteristics, including dynamic network topology changes, there is a need of mobility-aware fog computing, which is very challenging due to various dynamisms, and yet systematically uncovered. This paper presents a comprehensive survey on the fog computing compliant with the OpenFog (IEEE 1934) standardised concept, where the mobility of fog nodes constitutes an integral part. A review of the state-of-the-art research in fog computing implemented with mobile nodes is conducted. The review includes the identification of several models of fog computing concept established on the principles of opportunistic networking, social communities, temporal networks, and vehicular ad-hoc networks. Relevant to these models, the contributing research studies are critically examined to provide an insight into the open issues and future research directions in mobile fog computing research
Configuration space partitioning in tilings of a bounded region of the plane
Given a finite collection of two-dimensional tile types, the field of study
concerned with covering the plane with tiles of these types exclusively has a
long history, having enjoyed great prominence in the last six to seven decades.
Much of this interest has revolved around fundamental geometrical problems such
as minimizing the variety of tile types to be used, and also around important
applications in areas such as crystallography as well as others. All these
applications are of course confined to finite spatial regions, but in many
cases they refer back directly to progress in tiling the whole, unbounded
plane. Tilings of bounded regions of the plane have also been actively studied,
but in general the additional complications imposed by the boundary conditions
tend to constrain progress to mostly indirect results, such as recurrence
relations. Here we study the tiling of rectangular regions of the plane by
rectangular tiles. The tile types we use are squares, dominoes, and straight
tetraminoes. For this set of tile types, not even recurrence relations seem to
be available. Our approach is to seek to characterize this complex system
through some fundamental physical quantities. We do this on two parallel
tracks, one analytical for what seems to be the most complex special case still
amenable to such approach, the other based on the Wang-Landau method for
state-density estimation. Given a simple energy function based solely on tile
contacts, we have found either approach to lead to illuminating depictions of
entropy, temperature, and above all partitions of the configuration space. The
notion of a configuration, in this context, refers to how many tiles of each
type are used. We have found that certain partitions help bind together
different aspects of the system in question and conjecture that future
applications will benefit from the possibilities they afford.Comment: This version includes minor fixes and a new table, and updates
metadat
Approaches to Biosemiotics
Approaches to Biosemiotics is the first issue in the Biosocial World collection, and contains a series of articles on what biosemiotics does, how it does it and what its long-term objectives may be. As a more specialized discipline in the boundaries of linguistics, the biosociology, the philosophy of biology and the sciences, we hope to offer a point of entry into the world of biosemiotics through articles that deal with general topics from within the field. Our aim is, thus, to contribute to the biosemiotic landscape by opening a door to its recurring themes, problems and descriptions
Experiential Perspectives on Sound and Music for Virtual Reality Technologies
This thesis examines the intersection of sound, music, and virtuality within current and next-generation virtual reality technologies, with a specific focus on exploring the experiential perspectives of users and participants within virtual experiences. The first half of the thesis constructs a new theoretical model for examining intersections of sound and virtual experience. In Chapter 1, a new framework for virtual experience is constructed consisting of three key elements: virtual hardware (e.g., displays, speakers); virtual software (e.g., rules and systems of interaction); and virtual externalities (i.e., physical spaces used for engaging in virtual experiences). Through using and applying this new model, methodical examinations of complex virtual experiences are possible. Chapter 2 examines the second axis of the thesis through constructing an understanding of how sound is designed, implemented, and received within virtual reality. The concept of soundscapes is explored in the context of experiential perspectives, serving as a useful approach for describing received auditory phenomena. Auditory environments are proposed as a new model for exploring how auditory phenomena can be broadcast to audiences. Chapter 3 explores how inauthenticity within sound can impact users in virtual experience and uses authenticity to critically examine challenges surrounding sound in virtual reality. Constructions of authenticity in music performance are used to illustrate how authenticity is constructed within virtual experience. Chapter 4 integrates music into the understanding of auditory phenomena constructed throughout the thesis: music is rarely part of the created world in a virtual experience. Rather, it is typically something which only the audience – as external observers of the created world – can hear. Therefore, music within immersive virtual reality may be challenging as the audience is placed within the created world.The second half of this thesis uses this theoretical model to consider contemporary and future approaches to virtual experiences. Chapter 5 constructs a series of case studies to demonstrate the use of the framework as a trans-medial and intra/inter-contextual tool of analysis. Through use of the framework, varying approaches to implementation of sound and music in virtual reality technologies are considered, which reveals trans-medial commonalities of immersion and engagement with virtual experiences through sound. Chapter 6 examines near-future technologies, including brain-computer interfaces and other full-immersion technologies, to identify key issues in the design and implementation of future virtual experiences and suggest how interdisciplinary collaboration may help to develop solutions to these issues. Chapter 7 considers how the proposed model for virtuality might allow for methodical examination of similar issues within other fields, such as acoustics and architecture, and examines the ethical considerations that may become relevant as virtual technology develops within the 21st Century.This research explores and rationalises theoretical models of virtuality and sound. This permits designers and developers to improve the implementation of sound and music in virtual experiences for the purpose of improving user outcomes.<br/
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