From Extremal Trajectories to Token Deaths in P-time Event Graphs

In this technical note, we consider the (max,+) model of P-time Event Graphs whose behaviors are defined by lower and upper bound constraints. The extremal trajectories of the system starting from an initial interval are characterized with a particular series of matrices for a given finite horizon. Two dual polynomial algorithms are proposed to check the existence of feasible trajectories. The series of matrices are used in the determination of the maximal horizon of consistency and the calculation of the date of the first token deaths

Compromise Approach for Predictive Control of Timed Event Graphs with Specifications Defined by P-time Event Graphs

In this paper, the aim is to make the predictive control of a plant described by a Timed Event Graph which follows the specifications defined by a P-time Event Graph. We propose a compromise approach between the ideal optimality of the solution and the on-line application of the computed solution when the relevant optimal control cannot be applied for a given computer. The technique is based on a reduction of the number of iterations of the fixed point algorithm such that the computed control remains causal. The analysis of the partial satisfaction of the specifications at each iteration of the algorithm defined in the (max, +) algebra shows that a subset of constraints is guaranteed by the control computed at each iteration while another one is possibly satisfied

Cycle Time of a P-time Event Graph with Affine-Interdependent Residence Durations

In this paper, we widen the class of P-time Event graphs by introducing affine-interdependent residence durations. This new class is studied through a general algebraic model. Considering a periodic behavior, we provide conditions of existence of a trajectory and propose a technique allowing the determination of extremal solutions. We show that the cycle time is intrinsic to this new model: it depends on the circuits of an associated graph but also on more complex structures

Causality Phenomenon and Compromise Technique for Predictive Control of Timed Event Graphs with Specifications Defined by P-time Event Graphs

International audienc

State estimation and detection of changes in time interval models

This paper presents an estimation approach for Time Event Graphs such as P-Time Event Graphs and Time Stream Event Graphs. It is assumed that the nominal behavior is known and that transitions are partitioned as observable and unobservable transitions. The technique is applied to the detection of changes which are (possibly small) finite variations of dynamic models compared to this nominal behavior. The detected changes provide indications that can be used in future maintenance operations. Using the algebra of dioids, the approach uses a receding-horizon estimation of the greatest state and analyzes the consistency of the data

Optimal Control Synthesis of Timed Event Graphs With Interval Model Specifications

The purpose of this technical note is the optimal control synthesis of a timed event graph when the state and control trajectories should follow the specifications defined by an interval model. The problem is reformulated in the fixed point form and the spectral theory gives the conditions of existence of a solution

Determinants of grassland primary production in seasonally-dry silvopastoral systems in Central America

Grassland primary productivity is the function that underpins the majority of the fodder production in cattle-rearing silvopastoral farms. Hence, understanding the factors that determine grassland productivity is critical for the design and management of silvpastoral systems. We studied the effect of two factors with documented impact on grassland productivity in seasonally dry silvopastures of Nicaragua, rainfall and trees. We assessed the effects of three species that differed in crown size and phenology, one evergreen, Cassia grandis, and two deciduous species, Guazuma ulmifolia and Tabebuia rosea. Overall, grassland ANPP had a quadratic response to rainfall, with a decline at high rainfall that coincided with peak standing biomass and grassland cover. Trees had a predominately negative effect on grassland productivity, and the effect was concentrated in the rainy season at peak productivity. The effect of the trees corresponded with the tree crown area, but not with crown density. Trees reduced the standing biomass of graminoids and increased forb biomass; thus, the effect of trees on grassland ANPP appears in part to respond to changes in grassland composition. We also found higher levels of soil moisture content below the tree canopy, particularly at the peak of the rainy season when soils tend to become waterlogged. The evergreen species, C. grandis, affected grassland ANPP more strongly than the deciduous specie

Intelligent multimedia indexing and retrieval through multi-source information extraction and merging

This paper reports work on automated meta-data\ud creation for multimedia content. The approach results\ud in the generation of a conceptual index of\ud the content which may then be searched via semantic\ud categories instead of keywords. The novelty\ud of the work is to exploit multiple sources of\ud information relating to video content (in this case\ud the rich range of sources covering important sports\ud events). News, commentaries and web reports covering\ud international football games in multiple languages\ud and multiple modalities is analysed and the\ud resultant data merged. This merging process leads\ud to increased accuracy relative to individual sources

Acción COST “Red europea para la ciencia de datos lingüísticos centrada en la web” (NexusLinguarum)

We present the current state of the large “European network for Web-centred linguistic data science”. In its first phase, the network has put in place several working groups to deal with specific topics. The network also already implemented a first round of Short Term Scientific Missions (STSM).Presentamos el estado actual de la “Red Europea para la ciencia de datos lingüísticos centrada en la Web”. En su primera fase, el proyecto ha establecido varios grupos de trabajo para tratar temas específicos. La red también implementó una primera ronda de Misiones Científicas de Corto Plazo (la sigla STSM en Ingles, para Short Term Scientifc Mission).Work presented here was supported in part by the COST Action CA18209 – NexusLinguarum “European network for Web-centred linguistic data science”, the project Prêt-à-LLOD, under grant agreement no. 825182, and the ELEXIS project, under grant agreement no. 731015