48,173 research outputs found
Geospatial Narratives and their Spatio-Temporal Dynamics: Commonsense Reasoning for High-level Analyses in Geographic Information Systems
The modelling, analysis, and visualisation of dynamic geospatial phenomena
has been identified as a key developmental challenge for next-generation
Geographic Information Systems (GIS). In this context, the envisaged
paradigmatic extensions to contemporary foundational GIS technology raises
fundamental questions concerning the ontological, formal representational, and
(analytical) computational methods that would underlie their spatial
information theoretic underpinnings.
We present the conceptual overview and architecture for the development of
high-level semantic and qualitative analytical capabilities for dynamic
geospatial domains. Building on formal methods in the areas of commonsense
reasoning, qualitative reasoning, spatial and temporal representation and
reasoning, reasoning about actions and change, and computational models of
narrative, we identify concrete theoretical and practical challenges that
accrue in the context of formal reasoning about `space, events, actions, and
change'. With this as a basis, and within the backdrop of an illustrated
scenario involving the spatio-temporal dynamics of urban narratives, we address
specific problems and solutions techniques chiefly involving `qualitative
abstraction', `data integration and spatial consistency', and `practical
geospatial abduction'. From a broad topical viewpoint, we propose that
next-generation dynamic GIS technology demands a transdisciplinary scientific
perspective that brings together Geography, Artificial Intelligence, and
Cognitive Science.
Keywords: artificial intelligence; cognitive systems; human-computer
interaction; geographic information systems; spatio-temporal dynamics;
computational models of narrative; geospatial analysis; geospatial modelling;
ontology; qualitative spatial modelling and reasoning; spatial assistance
systemsComment: ISPRS International Journal of Geo-Information (ISSN 2220-9964);
Special Issue on: Geospatial Monitoring and Modelling of Environmental
Change}. IJGI. Editor: Duccio Rocchini. (pre-print of article in press
Symmetry-breaking Answer Set Solving
In the context of Answer Set Programming, this paper investigates
symmetry-breaking to eliminate symmetric parts of the search space and,
thereby, simplify the solution process. We propose a reduction of disjunctive
logic programs to a coloured digraph such that permutational symmetries can be
constructed from graph automorphisms. Symmetries are then broken by introducing
symmetry-breaking constraints. For this purpose, we formulate a preprocessor
that integrates a graph automorphism system. Experiments demonstrate its
computational impact.Comment: Proceedings of ICLP'10 Workshop on Answer Set Programming and Other
Computing Paradig
A graph-based aspect interference detection approach for UML-based aspect-oriented models
Aspect Oriented Modeling (AOM) techniques facilitate separate modeling of concerns and allow for a more flexible composition of these than traditional modeling technique. While this improves the understandability of each submodel, in order to reason about the behavior of the composed system and to detect conflicts among submodels, automated tool support is required. Current techniques for conflict detection among aspects generally have at least one of the following weaknesses. They require to manually model the abstract semantics for each system; or they derive the system semantics from code assuming one specific aspect-oriented language. Defining an extra semantics model for verification bears the risk of inconsistencies between the actual and the verified design; verifying only at implementation level hinders fixng errors in earlier phases. We propose a technique for fully automatic detection of conflicts between aspects at the model level; more specifically, our approach works on UML models with an extension for modeling pointcuts and advice. As back-end we use a graph-based model checker, for which we have defined an operational semantics of UML diagrams, pointcuts and advice. In order to simulate the system, we automatically derive a graph model from the diagrams. The result is another graph, which represents all possible program executions, and which can be verified against a declarative specification of invariants.\ud
To demonstrate our approach, we discuss a UML-based AOM model of the "Crisis Management System" and a possible design and evolution scenario. The complexity of the system makes con°icts among composed aspects hard to detect: already in the case of two simulated aspects, the state space contains 623 di®erent states and 9 different execution paths. Nevertheless, in case the right pruning methods are used, the state-space only grows linearly with the number of aspects; therefore, the automatic analysis scales
An uneasy reality: Donor support for IDPs in Ukraine Łukasz Wenerski, Andriy Korniychuk, Oleksandr Kliuzhev (cooperation)
According to international organizations, since the annexation of Crimea and the beginning of the war in Donbas, internal migrations might have affected from two to three million people. From Crimea and Donbas alone, 1.5 million Ukrainian citizens had to change their place of residence. Concerns that these internally displaced persons (IDPs) will become “Ukraine’s lost generation” have been voiced. A considerable number of Ukrainian citizens affected by the war in eastern Ukraine have started to look for either international protection on the territory of the EU or possible ways to pursue economic migration. Taking into account the unresolved refugee crisis in Europe, the international community has a particular interest in making sure the situation in Ukraine does not get out of hand. In this regard, the effectiveness of the assistance to the Ukrainian state and its civil society provided by international donors is of paramount importance.
Whereas the migration crisis has revealed new challenges faced by the Ukrainian state as it is undergoing the process of reform, it has also contributed to an increase in the public activity of Ukrainian citizens. Some of the most active IDPs have managed to find their place in the new reality (within the country or outside Ukraine), however, many have failed to cope with the displacement and are still struggling with huge economic and social problems.
In some places, basic humanitarian aid is still required, yet IDPs today generally face other problems, most frequently difficulties in finding a job and the lack of proper housing. There are several reasons for IDPs’ critical situation on the labor market: the unfavorable condition of the Ukrainian economy, skills that do not fit the Ukrainian economy (a consequence of the fact that Donbas was dominated by heavy industry and the mining industry, in particular), and sometimes the inactivity of the displaced people themselves (an effect of living many years under non- democratic rule in the region).
This paper aims at analyzing the socio-economic reality of IDPs in Ukraine as well as the state’s response to their challenges from the perspective of the IDP community. In addition, it presents how Ukrainian NGOs assess donor support for IDPs and what Ukrainian civil society expects from the international community in those areas where assistance is needed most
Early aspects: aspect-oriented requirements engineering and architecture design
This paper reports on the third Early Aspects: Aspect-Oriented Requirements Engineering and Architecture Design Workshop, which has been held in Lancaster, UK, on March 21, 2004. The workshop included a presentation session and working sessions in which the particular topics on early aspects were discussed. The primary goal of the workshop was to focus on challenges to defining methodical software development processes for aspects from early on in the software life cycle and explore the potential of proposed methods and techniques to scale up to industrial applications
BaFe12O19 single-particle-chain nanofibers : preparation, characterization, formation principle, and magnetization reversal mechanism
BaFe12O19 single-particle-chain
nanofibers have been successfully prepared by
an electrospinning method and calcination
process, and their morphology, chemistry,
and crystal structure have been characterized
at the nanoscale. It is found that individual
BaFe12O19 nanofibers consist of single nanoparticles which are found to stack along the
nanofiber axis. The chemical analysis shows that the atomic ratio of Ba/Fe is 1:12, suggesting a
BaFe12O19 composition. The crystal structure of the BaFe12O19 single-particle-chain nanofibers
is proved to be M-type hexagonal. The single crystallites on each BaFe12O19 single-particlechain
nanofibers have random orientations. A formation mechanism is proposed based on
thermogravimetry/differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and transmission
electron microscopy (TEM) at six temperatures, 250, 400, 500, 600, 650, and 800 �C.
The magnetic measurement of the BaFe12O19 single-particle-chain nanofibers reveals that the
coercivity reaches a maximum of 5943 Oe and the saturated magnetization is 71.5 emu/g at
room temperature. Theoretical analysis at the micromagnetism level is adapted to describe the
magnetic behavior of the BaFe12O19 single-particle-chain nanofibers
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