PLiMoS, a DSML to Reify Semantics Relationships: An Application to Model-Based Product Lines

In the Model-Based Product Line Engineering (MBPLE) context, modularization and separation of concerns have been introduced to master the inherent complexity of current developments. With the aim to exploit e ciently the variabilities and commonalities in MBPLs, the challenge of management of dependencies becomes essential (e.g. hierarchical and variability decomposition, inter-dependencies between models). However, one may observe that, in existing approaches, relational information (i) is mixed with other concerns, and (ii) lacks semantics and abstraction level identi cation. To tackle this issue, we make explicit the relationships and their semantics, and separate the relational concern into a Domain Speci c Modeling Language (DSML) called PLiMoS. Relationships are treated as rst-class entities and quali ed by operational semantics properties, organized into viewpoints to address distinct objectives, e.g. product derivation, variability consistency management, archi- tectural organization. This paper provides a description of the PLiMoS relationships de nition and its implementation in a model-based product line process using two variability languages: Feature Model and OVM. The independence with variability and core assets modeling languages provides bene ts to cope with the product line maintenance

ACTIVE CONTROL FOR THE RE-ENTRY OPERATION OF FLEXIBLE RISERS

International audienceThis paper presents an active control dedicated to a re-entry problem found in the offshore oil industry. The re-entry operation consists in connecting the bottom of a very long pipeline to the wellhead, by dynamically modifying the pipeline top position, which is linked to a floating device (vessel or plat- form). These long pipelines are usually called risers, because they are used to rise the drilling mud or the hydrocarbons from the wellhead to the platform. Nowadays the re-entry operation is done manu- ally. The use of an active control intends to reduce the operation time, and to make it possible even under bad weather conditions. The considered offshore structure can be analyzed as a cable submerged in a flow. A convenient model is given by the Bernoulli's historical cable equation, completed with a damping factor, that linearly depends on the structure speed. The damping factor is developed in series around zero, to get an approximate solution. The corresponding model turns out to be differentially flat[1], a property directly used in the control design, providing an extension to previous works of Petit and Rouchon [2], Thull et al [3], and Sabri [4]. This paper presents an overview of the results of [5]. Furthermore it contains material concerning a new tracking system, that uses the system inversion to define the feedback control

ACTIVE CONTROL AND MOTION PLANNING FOR OFFSHORE STRUCTURES

This paper presents an active control dedicated to the positioning of vertical offshore structures. The trajectory planning and the closed loop system use a convenient model given by the Bernoulli's historical cable equation, completed with a damping factor, that linearly depends on the structure speed. Its solution is directly used in the control design, providing an extension to previous works on control of heavy chains and offshore structures

Feedback control and optimization for the production of commercial fuels by blending

International audienceThis paper presents a control algorithm for blending systems. Such systems are used in refining to produce mixtures having specified properties from several components. The underlying control problem is multi-variable, with constraints on the inputs and outputs, and involves large uncertainties. To address this complexity, a constrained optimization problem is formulated, while the uncertainties are treated in closed-loop by an estimator of the components properties. Besides a theoretical study of the main algorithm and a study of convergence, the paper presents numerous technical details that are needed to solve blending problems as they appear in refining operations. Among them are a general lack of measurements, variable delays, measurement synchronization, infeasibilities management, hydraulic constraints, and pre-blends. Industrial case-studies are provided and stress the relevance of the approach

Competing coexisting phases in 2D water

International audienceThe properties of bulk water come from a delicate balance of interactions on length scales encompassing several orders of magnitudes: i) the Hydrogen Bond (HBond) at the molecular scale and ii) the extension of this HBond network up to the macroscopic level. Here, we address the physics of water when the three dimensional extension of the HBond network is frustrated, so that the water molecules are forced to organize in only two dimensions. We account for the large scale fluctuating HBond network by an analytical mean-field percolation model. This approach provides a coherent interpretation of the different events experimentally (calorimetry, neutron, NMR, near and far infra-red spectroscopies) detected in interfacial water at 160, 220 and 250 K. Starting from an amorphous state of water at low temperature, these transitions are respectively interpreted as the onset of creation of transient low density patches of 4-HBonded molecules at 160 K, the percolation of these domains at 220 K and finally the total invasion of the surface by them at 250 K. The source of this surprising behaviour in 2D is the frustration of the natural bulk tetrahedral local geometry and the underlying very significant increase in entropy of the interfacial water molecules