An improved grid tied photovoltaic system based on current conditioning

An interconnection of a renewable energy source: photovoltaic generator (PVG) with the power grid is investigated. The interconnection uses the conventional power inverter to link the DC PVG with the AC power grid sides. What is new in the interconnection is that an improved control strategy/technique is proposed to control the switching operation of inverter semiconductor switches. Conditioning the current delivered by the power inverter is enhanced by employing a hysteresis controller. The proposed interconnection avoids the need of installing DC/DC voltage controller and filter that are quite common in the conventional interconnection setups.The proposed current conditioning offers superior features such as: preventing or nearly preventing the penetration of the harmonics into the power grid without the need to install additional power filter commonly found in similar interconnection setups, avoiding the requirement of having controllable DC voltage at the DC side of the power inverter, controlling the power factor level at the point of interconnection with the grid, and relaxing the constraint of synchronization between the inverter output voltage and the power grid voltage prior to the interconnection of the inverter to the power grid.Computer simulations proved the effectiveness of the proposed controller and quite satisfactory results were reached. Keywords: On line grid tied PV system, Inverter current conditioning, Hysteresis controller, Maximum power tracker, Matlab Simulink simulation

Using finite-state transducers to build lexical resources for Unitex Arabic package

International audienceThis paper addresses the issue of generating Arabic verbal inflectional paradigms using the FSA. In the process of the proposed approach the tokens drawn from the corpus are manually lemmatized and then finite state transducers are applied to the lemmas for producing all possible word forms with their full morphological features. The first strength of the approach lie in the algorithm of automatic generation of 184 transitions transducers, which is very cumbersome, if manually, designed. The second strength is the new classification of Arabic verbs; this classification is based on our new suggested inflection scheme that specifies the verb inflection paradigms. All resulting resources are publicly available and currently used as an open package in the Unitex framework under the LGPL license

Multiple Fault Localization Using Constraint Programming and Pattern Mining

International audienceFault localization problem is one of the most difficult processes in software debugging. The current constraint-based approaches draw strength from declarative data mining and allow to consider the dependencies between statements with the notion of patterns. Tackling large faulty programs is clearly a challenging issue for Constraint Programming (CP) approaches. Programs with multiple faults raise numerous issues due to complex dependencies between faults, making the localization quite complex for all of the current localization approaches. In this paper, we provide a new CP model with a global constraint to speed-up the resolution and we improve the localization to be able to tackle multiple faults. Finally, we give an experimental evaluation that shows that our approach improves on CP and standard approaches

A Multiple Fault Localization Approach based on Multicriteria Analytical Hierarchy Process

International audienceFault localization problem is one of the most difficult processes in software debugging. Several spectrum-based ranking metrics have been proposed and none is shown to be empirically optimal. In this paper, we consider the fault localization problem as a multicriteria decision making problem. The proposed approach tackles the different metrics by aggregating them into a single metric using a weighted linear formulation. A learning step is used to maintain the right expected weights of criteria. This approach is based on Analytic Hierarchy Process (AHP), where a ranking is given to a statement in terms of suspiciousness according to a comparison of ranks given by the different metrics. Experiments performed on standard benchmark programs show that our approach enables to propose a more precise localization than existing spectrum-based metrics

Terahertz imaging and spectroscopy for security and defense applications

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