International audienceEfficient reconfiguration of optical multicast trees in wavelength division multiplexing (WDM) networks is required. Multimedia applications which consume a huge bandwidth, require multicasting. So, multicast concept is extended to optical networks to improve performance. Today, networks are facing many phenomena such as changes in the traffic model, failures, additions or deletions of some network resources due to a maintenance operation. To cope with these phenomena, network operators compute new topology according to the applications requirements. Some real-time multicast applications are not indulgent with lightpath interruptions. So the configuration of the network must be done as quickly as possible to be spontaneously deal with the problem before other events appear and without connection interruption. To the best of our knowledge, there is no work in the literature that considers the reconfiguration of an optical multicast tree to another one without connection interruption. We prove that it is impossible to reconfigure any initial tree into any final tree using only one wavelength and without connection interruption. We propose in this paper BpBAR_2 method, using several wavelengths to reconfigure optical WDM network. This algorithm does tree reconfiguration without lightpath interruption, reduce the reconfiguration setup time and the cost of wavelengths used

Abstract-In this article, we present a chatbot model that can automatically respond to learners' concerns on an online training platform. The proposed chatbot model is based on an adaptation of the similarity of Dice to understand the concerns of learners. The first phase of this approach allows selecting the preestablished concerns that the teacher has in a knowledge base which are closest to those posed by the learner. The second phase consists of selecting among these k most appropriate concerns based on a measure of similarity built on the concept of domain keywords. The experimentation of the prototype of this chatbot makes it possible to find the adequate answers. In the case, where the question refers to a question from the teacher, the learner is asked if the question identified is the one he was referring to. If he answers in the affirmative, the instructions associated with his request are sent to him. If not, the learner's concern is sent to the human tutor. The hybridization of this chatbot with the human agent comes to enrich the initial knowledge base of the chatbot. The results obtained with the concept based on the keywords of the domain are encouraging. The learner's comprehension rate is above 50% when applying the concept of domain keywords while the measure of Dice is below 50%.

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Belief entropy, which represents the uncertainty measure between several pieces of evidence in the Dempster-Shafer framework, is attracting increasing interest in research. It has been used in many applications and is mainly based on the theory of evidence. To quantify uncertainty, several measures have been proposed in the literature. These measures, sometimes in extended or hybrid forms, use the Shannon entropy principle to determine uncertainty degree. However, the failure to consider the scale of the frame of discernment framework remains an open issue in quantifying uncertainty. In this paper, we propose a new uncertainty measure that takes into account the power set of the frame of discernment. After analysing the different existing methods, we show the performance and effectiveness of our proposed approach.

Data warehouses are widely used in the fields of Big Data and Business Intelligence for statistics on business activity. Their use through multidimensional queries allows to have aggregated results of the data. The confidential nature of certain data leads malicious people to use means of deduction of this information. Among these means are data inference methods. To solve these security problems, the researchers have proposed several solutions based on the architecture of the warehouses, the design phase, the cuboids of a data cube and the materialized views of multidimensional queries. In this work, we propose a mechanism for detecting inference in data warehouses. The objective of this approach is to highlight partial inferences during the execution of a multidimensional OLAP (Online Analytical Processing) SUM-type multidimensional query. The goal is to prevent a data warehouse user from inferring sensitive information for which he or she has no access rights according to the access control policy in force. Our study improves the model proposed by a previous study carried out by Triki, which proposes an approach based on average deviations. The aim is to propose an optimal threshold to better detect inferences. The results we obtain are better compared to the previous study.