174 research outputs found
A Game of Attribute Decomposition for Software Architecture Design
Attribute-driven software architecture design aims to provide decision
support by taking into account the quality attributes of softwares. A central
question in this process is: What architecture design best fulfills the
desirable software requirements? To answer this question, a system designer
needs to make tradeoffs among several potentially conflicting quality
attributes. Such decisions are normally ad-hoc and rely heavily on experiences.
We propose a mathematical approach to tackle this problem. Game theory
naturally provides the basic language: Players represent requirements, and
strategies involve setting up coalitions among the players. In this way we
propose a novel model, called decomposition game, for attribute-driven design.
We present its solution concept based on the notion of cohesion and
expansion-freedom and prove that a solution always exists. We then investigate
the computational complexity of obtaining a solution. The game model and the
algorithms may serve as a general framework for providing useful guidance for
software architecture design. We present our results through running examples
and a case study on a real-life software project.Comment: 23 pages, 5 figures, a shorter version to appear at 12th
International Colloquium on Theoretical Aspects of Computing (ICTAC 2015
Palaeoclimatology and palaeohydrography of the glacial stages on Celtic and Armorican margins over the last 360 000 yrs
Core MD03-2692 was retrieved in a water-depth of 4064 m on the Celtic margin (Bay of Biscay) during the SEDICAR cruise onboard the RV Marion Dufresne II. It covers the last 360 ka in a total length of 39 m. Multidisciplinary analyses have been applied to this sequence with the aim of studying the palaeoclimatic and palaeoenvironmental signals of the last few climatic cycles. The analyses undertaken include: (1) non-destructive logging with: physical properties (magnetic susceptibility, sediment colour), X-ray radiography and measurement of the major elements by X-ray-fluorescence, (2) analyses of planktonic and benthic foraminifera, lithic grains and stable isotopic measurements (oxygen and carbon). We have focused on the long-term evolution of glacial stages (with special attention to terminations and Heinrich events). The results obtained confirm the close correlation between deep-sea sedimentation recorded on the Celtic margin and changes in the terrestrial environment of the adjacent continent. Heinrich layers have been identified in MIS 2, 3, 6 and 8. We note the occurrence of laminated facies within deglacial sequences deposited during Termination I and MIS 6. These facies are closely linked to disintegration phases of the British–Irish Ice Sheet (BIS). The laminations contain lower ice-rafted detritus (IRD) concentrations than the equivalent Heinrich layers and are linked to abrupt changes in sea-surface palaeotemperatures. We suggest that the laminations are formed by an annual cycle of meltwater and iceberg release from the disintegrating BIS generating cascading plumes of dense turbid meltwater coeval with IRD release
MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013
Architectural mismatch tolerance
The integrity of complex software systems built from existing components is becoming more dependent on the integrity of the mechanisms used to interconnect these components and, in particular, on the ability of these mechanisms to cope with architectural mismatches that might exist between components. There is a need to detect and handle (i.e. to tolerate) architectural mismatches during runtime because in the majority of practical situations it is impossible to localize and correct all such mismatches during development time. When developing complex software systems, the problem is not only to identify the appropriate components, but also to make sure that these components are interconnected in a way that allows mismatches to be tolerated. The resulting architectural solution should be a system based on the existing components, which are independent in their nature, but are able to interact in well-understood ways. To find such a solution we apply general principles of fault tolerance to dealing with arch itectural mismatche
Morphodynamique d'une dune sous-marine du détroit du Pas de Calais. Morphodynamics of an undersea sandwave of the Dover Straits
This paper investigates the dynamics of sandwaves in relationship with tidal currents and weather conditions. The studied sandwaves are located in the Dover Straits and are covered by megaripples. These megaripples have migration speeds of and slopes of 34°, suggesting the potential for avalanches to occur along the flanks of the sandwave. Tidal cycles without reversing currents were observed during stormy weather. Wind-induced currents lead to a unidirectional migration of megaripples and sandwaves. Well-defined areas without megaripples were observed and correlated with an increase in sandwave height. We propose interpretations for understanding sandwave saturation and migratio
Residual transport model in correlation with sedimentary dynamics over an elongate tidal sandbar in the Gironde Estuary (Southwestern France)
This study qualitatively describes by a multidisciplinary approach hydrodynamic and residual sediment transport over a sandbar in a macrotidal environment. The sandbar is elongated and attached to a headland that is located in the Gironde estuary (southwestern France). Bathymetric surveys, side-scan-sonar sonograms, grain-size trends of surficial sediment, and 2DH numerical simulations of current patterns were used to define a conceptual model for the dynamics of this sandbar. The sandbar is oriented anticlockwise with respect to the main flow. The channel-oriented bar face is ebb-dominated, whereas the opposite face is flood-dominated, resulting in a clockwise residual transport. The line of sediment flux convergence corresponds to the crest of the bar. The residual flow over the bar appears to originate from the regional estuarine flow. The dominant process responsible for the maintenance of the sandbar seems to be the depth-averaged main tidal flow rather than secondary circulation due to headlands or the interaction between the tidal flow and the seabed. To generalize this regional conceptual model a qualitative comparison is made with the theories of sandbar dynamics due to tidal currents (Pingree and Maddock 1979, Zimmerman 1981, Huthnance 1982, and others). The seabed stability approach developed by Huthnance (1982) seems to be the most reliable theory to explain the Saint-Georges Bank dynamics, even though many natural factors are not taken into account
Utilisation of numerical and statistical techniques to describe sedimentary circulation patterns in the mouth of the Gironde estuary
Sediment distribution is well defined in the mouth of the Gironde estuary but the sediment dynamics is still poorly understood. The aim of this work is to analyse residual circulation of non-cohesive sediment due to the action of the main hydrodynamic factor: tidal currents. A depth-averaged numerical model emphasises the residual circulation of the Gironde estuary, which is characterised by residual tidal gyres. The comparison between sediment transport calculated from the numerical model and from a statistical analysis of the sedimentary distribution leads to the definition of a simple scheme of non-cohesive sediment circulation in the Gironde estuary’s mouth
Direct characterization of circulating DNA in blood plasma using ÎĽLAS technology
Circulating cell-free DNA (cfDNA) is a powerful cancer biomarker for establishing targeted therapies or monitoring patients' treatment. However, current cfDNA characterization is severely limited by its low concentration, requiring the extensive use of amplification techniques. Here we report that the ÎĽLAS technology allows us to quantitatively characterize the size distribution of purified cfDNA in a few minutes, even when its concentration is as low as 1 pg/ÎĽL. Moreover, we show that DNA profiles can be directly measured in blood plasma with a minimal conditioning process to speed up considerably speed up the cfDNA analytical chain
Separating Agent-Functioning and Inter-Agent Coordination by Activated Modules: The DECOMAS Architecture
The embedding of self-organizing inter-agent processes in distributed
software applications enables the decentralized coordination system elements,
solely based on concerted, localized interactions. The separation and
encapsulation of the activities that are conceptually related to the
coordination, is a crucial concern for systematic development practices in
order to prepare the reuse and systematic integration of coordination processes
in software systems. Here, we discuss a programming model that is based on the
externalization of processes prescriptions and their embedding in Multi-Agent
Systems (MAS). One fundamental design concern for a corresponding execution
middleware is the minimal-invasive augmentation of the activities that affect
coordination. This design challenge is approached by the activation of agent
modules. Modules are converted to software elements that reason about and
modify their host agent. We discuss and formalize this extension within the
context of a generic coordination architecture and exemplify the proposed
programming model with the decentralized management of (web) service
infrastructures
Shuffle–based verification of component compatibility
An extension of earlier work on component compatibility is described in this paper. Similarly as before, the behavior of components is specified by component interface languages, and the shuffle operation is introduced to represent possible interleavings of service requests that originate at several concurrent components. The paper shows that the verification of component compatibility is possible without the exhaustive analysis of the state space of interacting components. Exhaustive analysis of state spaces was the basis of earlier approaches to compatibility verification
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