A Bond Graph Modeling for Health Monitoring and Diagnosis of the Tennessee Eastman Process

Data-driven fault detection and diagnosis approaches are widely applicable in many real-time practical applications. Among these applications, the industrial benchmark of Tennessee Eastman Process (TEP) is widely used to illustrate and compare control and monitoring studies. However, due to the complexity of physical phenomena occurring in such process, no model-based approach for fault diagnosis has been developed and most of the diagnosis approaches applied to the TEP are based on experiences and qualitative reasoning that exploit the massive amount of available measurement data. In this paper, we propose to use the Bond Graph formalism as a multidisciplinary energetic approach that enables to obtain a graphical nonlinear model of the TEP not only for simulation purposes but also for monitoring tasks by generating formal fault indicators. In this study, the proposed BG model is validated from the experiment data and the problem of the TEP model design is hence overcome. A Bond Graph Modeling for Health Monitoring and Diagnosis of the Tennessee Eastman Process (PDF Download Available). Available from: https://www.researchgate.net/publication/314032904_A_Bond_Graph_Modeling... [accessed May 30, 2017]

A decision fusion based methodology for fault Prognostic and Health Management of complex systems

Prognostic and Health Management (PHM) represents an active field of research and a major scientific challenge in many domains. It usually focuses on the failure time or the Remaining Useful Life (RUL) prediction of a system. This paper presents a generic framework, based on a discrete Bayesian Network (BN), particularly tailored for decision fusion of heterogeneous prognostic methods. The BN parameters are computed according to the fixed prognostic objectives. The effectiveness of the proposed decision fusion based methodology for the prognostic is demonstrated through the RULs estimation of turbofan engines. The application highlights the ability of the approach to estimate RULs which overpasses the performance of most other published results in the literature

Model-based approach for fault diagnosis using set-membership formulation

This paper describes a robust model-based fault diagnosis approach that enables to enhance the sensitivity analysis of the residuals. A residual is a fault indicator generated from an analytical redundancy relation which is derived from the structural and causal properties of the signed bond graph model. The proposed approach is implemented in two stages. The first stage consists in computing the residuals using available input and measurements while the second level leads to moving horizon residuals enclosures according to an interval consistency technique. These enclosures are determined by solving a constraint satisfaction problem which requires to know the derivatives of measured outputs as well as their boundaries. A numerical differentiator is then proposed to estimate these derivatives while providing their intervals. Finally, an inclusion test is performed in order to detect a fault upon occurrence. The proposed approach is well suited to deal with different kinds of faults and its performances are demonstrated through experimental data of an omni-directional robot

A New Multi-Objective Decision-Making Approach Applied to the Tennessee Eastman Process

In this paper, a generic framework and a new methodology aiming to decisions fusion of various Fault Detection and Diagnosis (FDD) methods are proposed. The framework consists of a discrete Bayesian Network (BN) and can handle all FDD methods, regardless of their a prior knowledge or requirements. The methodology expresses the FDD objectives to achieve the desired performance and results in a theoretical learning of the BN parameters. The development leads to a multi-objective problem under constraints, resolved with a lexicographic method.The e ectiveness of the proposed Multi-Objective Decision-Making (MODM) approach is validated through the Tennessee Eastman Process (TEP), as a challenging industrial benchmark problem. The application shows the signi cant improvement in FDD performances that can be ensured by the proposed methodology, in terms of high fault detection rate and small false alarm rate

Les tumeurs parotidiennes

Objectif : Les tumeurs des glandes salivaires sont rares, dominées en fréquence par les tumeurs parotidiennes. elles sont caractérisées par une grande hétérogénéité morpho-histologique. Les formes bénignes sont les plus fréquentes dominées par l’adénome pléomorphe. Le traitement de ces tumeurs demeure chirurgical en premier lieu.Matériel et méthodes: Cette étude est rétrospective portant sur 47 cas de tumeurs parotidiennes sur une période de 10 ans (janvier 2000 à décembre 2009). L’étude des dossiers nous a permis de relever toutes les données cliniques et thérapeutiques. Notre recul est de deux ans.Résultats : L’âge moyen de nos patients était de 42 ans avec un sex-ratio de 2,58. Les tumeurs bénignes représentaient 89 % et 11 % étaient malignes. L’adénome pléomorphe était la tumeur bénigne la plus fréquente. La tumeur maligne la plus commune était le carcinome muco-épidermoïde. Le traitement de choix est la parotidectomie partielle ou totale. Cependant, la paralysie du nerf facial reste la complication principale de la chirurgie parotidienne.Conclusion : Les formes bénignes sont prédominante s, dont le plus fréquent demeure l’adénome pléomorphe. L’imagerie moderne permet une approche histopathologique de nature. Le traitement de choix est la parotidectomie totale ou partielle. La radiothérapie peut être indiquée dans les formes malignes.Mots-clés : Tumeur, Parotide, Adénome pléomorphe, Maligne, Chirurgie

Phylogeography of the marbled crab Pachygrapsus marmoratus (Decapoda, Grapsidae) along part of the African Mediterranean coast reveals genetic homogeneity across the Siculo-Tunisian Strait versus heterogeneity across the Gibraltar Strait

We investigate the influence of previously postulated biogeographic barriers in the Mediterranean Sea on the population genetic structure of a highly dispersive and continuously distributed coastal species. In particular, we examine nuclear and mitochondrial genetic variation in the marbled crab, Pachygrapsus marmoratus, across part of the African Mediterranean coast in order to assess the influence of the Siculo-Tunisian Strait on its population genetic structure. Four polymorphic microsatellite loci were genotyped for 110 individuals, collected from eight locations covering parts of the Algerian, Tunisian and Libyan coasts. In addition, mtDNA corresponding to the Cox1 gene was sequenced for 80 samples. The corresponding results show contrasting patterns of genetic differentiation. While mtDNA results revealed a homogeneous haplotype composition in our study area, microsatellite data depicted genetic differentiation among populations, but not associated with any geographic barrier. This pattern, already recorded for this species from different geographic regions, may hint at the involvement of a complex series of abiotic and biotic factors in determining genetic structure. Demographic history reconstruction, inferred from mtDNA data, supports demographic and spatial expansion for the North African metapopulation dating back to the Mid-Pleistocene and following an historical bottleneck. Comparison of these African mitochondrial sequences with new sequences from a Turkish population and previously published sequences revealed a weak but significant separation of Atlantic and Mediterranean populations across the Gibraltar Strait, which was not recorded in previous studies of this grapsid species

Sensitivity of Melt Pool Size and Porosity Appearing to Base Plate Preheating in Laser Powder Bed Fusion Process

The base plate temperature ranks among the crucial building parameters whose effect on melt pool dimensions and porosity defects generation has not been sufficiently discussed in literature. In the current study, with the aim to explore the dependence between melt pool dimensions, porosity defects and base plate preheating, a 3-dimensional thermal finite element model is carried out to create IN718 single beads, at various base plate temperatures. The dimensions of the melt pool behave favourably with the base plate preheating. Indeed, the melt pool depth, width and length increase continuously with the heat of the base plate, from 20 °C to 500 °C. The melt pool width is more responsive to the base plate temperature than the melt pool depth. Numerical results also indicate that the melt dimensions become more responsive to the temperature of the base plate at a slower scan speed. The degree of porosity is predicted under multiple values of base plate temperature and the results show that porosity tends to disappear with further preheating of the base plate. A satisfying accordance between the numerical finding and the experimental results from literature is identified

Parameters Selection for the Production of Fully Dense Metals Processed by Selective Laser Melting

Selective laser melting (SLM) presents significant assets for both industrial and academic fields. However, the process parameters selection is yet challenging. It presents tens of parameters to be carefully selected, including laser power and speed, bed thickness, hatching space, and other parameters, for the manufacturing of parts with high density. This paper provides a deeper understanding of the processing parameters’ effect on the evolution of the product’s density. A series of numerical simulations of porosity is achieved on Ansys Additive© software and it shows the evolution of the relative density at different laser powers and scan speeds. Numerical results show that low laser power and accelerated scan lead to the generation of a small melt pool, and consequently low density. In the opposite case, at high power and slow scan, the created melt pool is wide enough to avoid porosity and generate fully dense products. The product density is proportionally related to the melt pool size. Hence, it could be estimated through the correlation with the melt pool width, which enables the perfect selection of the hatching space for the selected set of parameters

Optimization of the Cooling of a Thermoplastic Injection Mold

In injection molding processes for thermoplastic parts, the polymer solidification phase in the molding cavity has a strong influence on the quality of the shaped parts and also on the process cycle time. Reducing cycle time is one of the major concerns for plastic injection industries. As cooling phase presents the most critical phase to get quality and cycle time of the part, the application of additive manufacturing (AM) technologies has been overcoming the limitations of traditional cooling system design. AM enables the construction of conformal cooling channels for higher cooling uniformity due to its almost unlimited freedom of design that can fulfil the desired functions in injection molding process equipment. The analysis of the heat transfer during the phase of cooling allows the investigation of the optimal positioning of the cold sources and their intensities. In this paper, a systematic approach is used to replace conventional channels in an injection molding tool with conformal cooling channels. A simulation is used to develop a numerical model that describes the heat transfer and predicts the cycle time of both the optimal and conventional designs. Finally, a numerical comparison is made between traditional and conformal cooling to demonstrate the beneficial effect on reducing the manufacturing cycle and enhancing part quality

Comparative Analysis of Melt Pool Evolution in Selective Laser Melting of Inconel 625 and Inconel 718 Nickel-Based Superalloys

One of the key advantages of Additive Manufacturing is the versatility in working with a wide range of materials. Among these materials, Nickel-based superalloys have drawn great attention of specialists.  This study investigates the behavior of Inconel 625 and Inconel 718 during selective laser melting. While these alloys have many similarities, thus their distinct chemical compositions determine different responses to this new process, which the authors aimed to elucidate in this study. Numerical simulations using ANSYS Additive® software were conducted to compare the melt pool dimensions (depth and width) of Inconel 625 and Inconel 718. The results reveal that the material's thermal properties play a significant role in determining the melt pool geometry. The Inconel 718 consistently exhibited larger melt pool dimensions than Inconel 625. The findings highlight the importance of understanding the connection between the material properties and process parameters