15,062 research outputs found
Extending the 5S Framework of Digital Libraries to support Complex Objects, Superimposed Information, and Content-Based Image Retrieval Services
Advanced services in digital libraries (DLs) have been developed and widely used to address the required capabilities of an assortment of systems as DLs expand into diverse application domains. These systems may require support for images (e.g., Content-Based Image Retrieval), Complex (information) Objects, and use of content at fine grain (e.g., Superimposed Information). Due to the lack of consensus on precise theoretical definitions for those services, implementation efforts often involve ad hoc development, leading to duplication and interoperability problems. This article presents a methodology to address those problems by extending a precisely specified minimal digital library (in the 5S framework) with formal definitions of aforementioned services. The theoretical extensions of digital library functionality presented here are reinforced with practical case studies as well as scenarios for the individual and integrative use of services to balance theory and practice. This methodology has implications that other advanced
services can be continuously integrated into our current extended framework whenever they are identified. The theoretical definitions and case study we present may impact future development efforts and a wide range of digital library researchers, designers, and developers
Binding and Normalization of Binary Sparse Distributed Representations by Context-Dependent Thinning
Distributed representations were often criticized as inappropriate for encoding of data with a complex structure. However Plate's Holographic Reduced Representations and Kanerva's Binary Spatter Codes are recent schemes that allow on-the-fly encoding of nested compositional structures by real-valued or dense binary vectors of fixed dimensionality.
In this paper we consider procedures of the Context-Dependent Thinning which were developed for representation of complex hierarchical items in the architecture of Associative-Projective Neural Networks. These procedures provide binding of items represented by sparse binary codevectors (with low probability of 1s). Such an encoding is biologically plausible and allows a high storage capacity of distributed associative memory where the codevectors may be stored.
In contrast to known binding procedures, Context-Dependent Thinning preserves the same low density (or sparseness) of the bound codevector for varied number of component codevectors. Besides, a bound codevector is not only similar to another one with similar component codevectors (as in other schemes), but it is also similar to the component codevectors themselves. This allows the similarity of structures to be estimated just by the overlap of their codevectors, without retrieval of the component codevectors. This also allows an easy retrieval of the component codevectors.
Examples of algorithmic and neural-network implementations of the thinning procedures are considered. We also present representation examples for various types of nested structured data (propositions using role-filler and predicate-arguments representation schemes, trees, directed acyclic graphs) using sparse codevectors of fixed dimension. Such representations may provide a fruitful alternative to the symbolic representations of traditional AI, as well as to the localist and microfeature-based connectionist representations
A simple conceptual model of abrupt glacial climate events
Here we use a very simple conceptual model in an attempt to reduce essential
parts of the complex nonlinearity of abrupt glacial climate changes (the
so-called Dansgaard-Oeschger events) to a few simple principles, namely (i) a
threshold process, (ii) an overshooting in the stability of the system and
(iii) a millennial-scale relaxation. By comparison with a so-called Earth
system model of intermediate complexity (CLIMBER-2), in which the events
represent oscillations between two climate states corresponding to two
fundamentally different modes of deep-water formation in the North Atlantic, we
demonstrate that the conceptual model captures fundamental aspects of the
nonlinearity of the events in that model. We use the conceptual model in order
to reproduce and reanalyse nonlinear resonance mechanisms that were already
suggested in order to explain the characteristic time scale of
Dansgaard-Oeschger events. In doing so we identify a new form of stochastic
resonance (i.e. an overshooting stochastic resonance) and provide the first
explicitly reported manifestation of ghost resonance in a geosystem, i.e. of a
mechanism which could be relevant for other systems with thresholds and with
multiple states of operation. Our work enables us to explicitly simulate
realistic probability measures of Dansgaard-Oeschger events (e.g. waiting time
distributions, which are a prerequisite for statistical analyses on the
regularity of the events by means of Monte-Carlo simulations). We thus think
that our study is an important advance in order to develop more adequate
methods to test the statistical significance and the origin of the proposed
glacial 1470-year climate cycle
Marinas and other ports and facilities for the recreational craft sector: an ontology domain to support spatial planning.
Marinas and other ports and facilities for the recreational craft sector in Sardinia (Italy) can host more than 19,000 pleasure boats and yachts, according to a recent estimate (Osservatorio Nautico Nazionale, 2010); this capacity, at the national level, is second only to that of the Liguria region. However, Sardinian infrastructures and facilities are not part of a coherent network. Moreover, they are unevenly scattered along the coastline and are very diverse, in terms of type, dimension, and endowment of facilities for sailors. A key issue to be taken into account in the early stages of the preparation of a plan for the pleasure craft sector, which might create the conditions for the setting up of a coherent network, is the lack of a proper, detailed knowledge of the system of Sardinian marinas and other facilities. To this end, this paper begins with an analysis of current information (both spatial and non-spatial) and attempts to build a spatial database that integrates available data. The analysis identifies differences in structure and semantics, together with differences in purpose and date of production/update of the data, as the roots of inconsistencies among existing data produced by different sources. Such differences in structure and semantics risk, if not properly identified, considered and handled, to cause an incorrect integration of data. Following the methodology provided by the guidelines produced by the Ordnance Survey with regards to domain ontologies (Hart et al., 2007; Hart e Goodwin, 2007; Kovacs et al., 2006), the construction of an ontology of the domain of infrastructure and facilities for the recreational craft sector is therefore proposed as a possible solution to the problem. By applying this methodology, a ‘knowledge glossary,’ consisting of a shared vocabulary of core and secondary concepts and of relationships (some of which spatial) among concepts is developed, leading to the construction of a conceptual model of the domain, later formalized by means of the software Protégé.
Collaboration in the Semantic Grid: a Basis for e-Learning
The CoAKTinG project aims to advance the state of the art in collaborative mediated spaces for the Semantic Grid. This paper presents an overview of the hypertext and knowledge based tools which have been deployed to augment existing collaborative environments, and the ontology which is used to exchange structure, promote enhanced process tracking, and aid navigation of resources before, after, and while a collaboration occurs. While the primary focus of the project has been supporting e-Science, this paper also explores the similarities and application of CoAKTinG technologies as part of a human-centred design approach to e-Learning
A Finite Horizon Inventory Model: An Operational Framework
We present a simulation based decision support system to decide the inventory ordering policy in the context of a single commodity, multi pack, and finite horizon situation. The multiple objectives include (a) Minimizing the end of the season inventory, (b) Maximizing the operating profit, (c) Minimizing the peak working capital requirements during the season. Stochastic demand and positive lead time add to the complexity of the problem context. In addition multiple partners in the supply chain with distinct and conflicting set of objectives necessitate the need for a formal approach. The motivation for this model is based on a real life situation. The model addresses the decision choices faced by the distributor in a specific logistics chain. In this chain, a typical distributor has to balance between the stochastic nature of the demand and the attractive nature of financial incentives (order quantity based) proposed by the manufacturer. The problem can be formulated as a multi-period dynamic programming problem with stochastic demand with an objective to optimize the expected operating profit, subject to specific constraints on working capital requirement, service level, order fill rate and end of the season inventory. Such a formulation is hard to solve and does not lend itself to analyze several ordering policies. Based on simulation experiments, we propose an ordering policy which optimizes the overall objectives of supply chain partners and hence demonstrated the possibility of jointly managing the uncertain demand by supply chain partners. The model is simple and easy to use. It is implemented by using spreadsheet. It provides adequate flexibility to conduct what-if analysis. The model has a potential to be useful in a wide range of situations.
NN Scattering: Chiral Predictions for Asymptotic Observables
We assume that the nuclear potential for distances larger than 2.5 fm is
given just by the exchanges of one and two pions and, for the latter, we adopt
a model based on chiral symmetry and subthreshold pion-nucleon amplitudes,
which contains no free parameters. The predictions produced by this model for
nucleon-nucleon observables are calculated and shown to agree well with both
experiment and those due to phenomenological potentials.Comment: 16 pages, 12 PS figures included, to appear in Physical Review
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