Splitting Arabic Texts into Elementary Discourse Units

International audienceIn this article, we propose the first work that investigates the feasibility of Arabic discourse segmentation into elementary discourse units within the segmented discourse representation theory framework. We first describe our annotation scheme that defines a set of principles to guide the segmentation process. Two corpora have been annotated according to this scheme: elementary school textbooks and newspaper documents extracted from the syntactically annotated Arabic Treebank. Then, we propose a multiclass supervised learning approach that predicts nested units. Our approach uses a combination of punctuation, morphological, lexical, and shallow syntactic features. We investigate how each feature contributes to the learning process. We show that an extensive morphological analysis is crucial to achieve good results in both corpora. In addition, we show that adding chunks does not boost the performance of our system

Machining and drilling processes in composites manufacture: Damage and material integrity

International audienceThis chapter discusses the influence of the machining process and machining parameters during machining of composite materials. In the first time, the chapter summarizes reviews of the machining processes and its impact on the mechanical behavior of composite materials. In the second time, a characterization of the surface defects induced by different processes of machining (conventional and nonconventional) is presented. Finally, the chapter focuses on the impact of the different nature of damage generated on the mechanical behavior of composites structures during static and fatigue tests. Keywords: Process of machining; Material integrity; Damage; Drilling; Trimmin

Evaluation of the performance of coated and uncoated carbide tools in drilling thick CFRP/aluminium alloy stacks

This paper aims to establish the wear mechanisms of coated and uncoated tungsten carbide drills when drilling carbon fibre reinforced plastics (CFRP)/aluminium alloy (Al) stacks. During the drilling experiments, thrust forces were measured. A scanning electron microscope (SEM) and a numerical microscope, provided with a scanning device, were periodically used to analyse tool wear mechanisms and to measure wear progression of the tool cutting edges. For both coated and uncoated drills, abrasion was the dominant tool wear mechanism, affecting the entire cutting edges. Higher wear was observed on uncoated tools which caused a significant increase in thrust force during drilling both Al and CFRP materials. The influence of these phenomena on the quality of the holes and on the generated roughness was also discussed.FUI-Usinage de Multi-Matériaux et Innovation (U2MI

Investigating the effect of machining processes on the mechanical behaviour of composite plates with circular holes

International audienceThe influence of the machining quality on the mechanical behavior of CFRP composites is yet not fully understood. There are only few works in the literature that have investigated the effect of the machining quality on CFRP. In fact, most of these works focus only on conventional machining such as axial or orbital drilling. The aim of this paper is to examine the influence of two machining processes namely conventional machining (CM) and abrasive water jet machining (AWJM) on the mechanical behavior of composite plates under cyclic loading. For this purpose, an experimental study using several composite plates drilled with a cutting tool and an abrasive water jet machining was carried out. In order to study the impact of the process of machining on the mechanical behavior, thermographic infrared testing and fatigue cyclic tests were performed to assess temperature evolutions, stiffness degradation, and the damage evolution in these plates. Fatigue testing results have shown that the damage accumulation in specimens drilled with CM process was higher than the AWJM specimens. Furthermore, the endurance limit for a composite plate drilled with CM was approximately 10% inferior compared to specimens drilled with AWJM. This difference can be related to the initial surface integrity after machining induced by the difference in the mechanism of material's removal between the two processes used. Key words: E. Machining, C. Damage mechanics; D. Mechanical testing, E. Thermal analysis

Round trip time TCP tracking: a first step towards QoS pricing

Packet discard policies extending those used by RED and the like are presented. These policies are designed through the tracking of a pre-specified round trip time trajectory. The design of the latter can possibly include fine grained QoS and/or pricing specifications

Study of trimming damages of CFRP structures in function of the machining processes and their impact on the mechanical behavior

International audienceThe main focus of this paper is to investigate the defects generated by different machining processes (namely burr tool machining, abrasive water jet machining \textquoteleftAWJM\textquoteright and abrasive diamond cutter \textquoteleftADS\textquoteright) and their impact on the mechanical behavior of CFRP in quasi-static (compression and inter-laminar shear) and tensile\textendashtensile fatigue tests. The cutting conditions are selected so that different levels of degradation can be obtained. The machined surface is characterized using roughness measuring devices with and without contact and SEM observations. The results show that the defects generated during the trimming process with a cutting tool are fibers pull-out and resin degradation. These defects are mainly located in the layers with the fibers oriented at -45° and 90°. However, when using abrasive water jet and abrasive diamond processes, the defects generated have the form of streaks and are not dependent on the fiber orientation. Furthermore, the results of quasi-static tests performed on specimens machined by cutting tools show that AWJ specimens offer a better resistance in compression but the ADS samples offer higher inter-laminar-shear strengths. Moreover, the results of fatigue tests show that specimens machined with a burr tool offer higher endurance limit. Finally, it is concluded that the type and the mode of the mechanical loading (quasi-static fatigue) affect the mechanical response of CFRP and favor a given machining process

Role of the surface quality on the mechanical behavior of CFRP bolted composite joints

International audienceIn this research paper, the influence of two drilling processes on the mechanical behavior of bolted composite joints was investigated. Two stacking sequences were studied namely, [\textpm45°]2S and [90/+45/0/-45]S. The composite specimens were drilled using conventional machining (CM) and abrasive water-jet machining (AWJM). Fatigue tests combined with infrared thermography (IR) were used to determine the high cycle fatigue strength and monitor damage accumulation and heat dissipation. Fatigue test results at 65% of the ultimate tensile strength showed that the damage for [\textpm45°]2S and [90/+45/0/-45]S bolted joints drilled with CM were 65% and 54% respectively. However, when the AWJM was used, the damage accumulated was 25% more compared to CM. This difference was confirmed by IR results which showed that [\textpm45°]2S bolted joints drilled with CM dissipate 23% more heat than those drilled with AWJM. The current study demonstrated that AWJM extends the high cycle fatigue strength and the fatigue life of bolted composite joints

Influence of trimming process on the surface quality and on the mechanical behavior of CFRP structures.

International audienceIn this paper, the effect of machining process, conventional machining (burr tool and abrasive diamond cutter (ADS)) and non conventional machining (abrasive water jet (AWJ)), on the mechanical behavior of composite parts made of carbon/epoxy is investigated

Influence of trimming process on the surface quality and on the mechanical behavior of CFRP structures.

International audienceIn this paper, the effect of machining process, conventional machining (burr tool and abrasive diamond cutter (ADS)) and non conventional machining (abrasive water jet (AWJ)), on the mechanical behavior of composite parts made of carbon/epoxy is investigated

Benefit from embedded sensors to study polymeric composite structures

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