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Enabling Monetization of Depreciating Data on Blockchains
Get PDFIn this paper, we introduce a protocol to securely exchange data on chain while varying its price according to their freshness, maturity and lifetime. The exchange protocol, implemented as a smart contract, is best applied to crowdsourcing systems for fast depreciating digital goods, in which information is publicly shared after a given delay. The smart contract acts as a trusted intermediary to make sure that the funds of a client are delivered to the provider if and only if the data were really transferred. It also ensures that the data will be freely shared on the blockchain when the data has sufficiently depreciated. We demonstrate our work with an available prototype for specific space tracking data exchange
Combustor-turbine interactions: Hot spot migration and thermal environment prediction for a better understanding and design of helicopter engines
Get PDFThis PhD thesis, funded by SAFRAN Helicopter Engines, focuses on Large Eddy Simulation (LES) of the FACTOR test rig to investigate combustor-turbine interactions in the context of next generation lean combustion engines. The FACTOR test rig is a full annular non-reactive lean combustion simulator with a single staged high-pressure turbine located at the DLR in G�ottingen. Another test rig featuring three sectors or 54_ of the full annular DLR test rig is available at the University of Florence. Both rigs provide a huge amount of validation data. In this thesis, certain aspects of LES in turbomachinery are investigated in detail and the manuscript is divided into two parts dealing respectively with the modeling of cooling systems and an analysis of the ow _eld in the combustion chamber and high-pressure vane passage. First, a heterogeneous and a homogeneous coolant injection model for multiperforated plates in combustion chambers are tested against experimental results. From this _rst study it is shown that the heterogeneous model allows for a more realistic coolant jet representation and should be retained for future simulations. In gas turbine engines the application of coolant systems is not only mandatory in the combustion chamber, but also in the _rst stages of the high-pressure turbine. The next section therefore investigates the previously presented heterogeneous injection model as a mean to model the e_ects of the NGV cooling system on the main ow and compares the simulation to a second one with a fully resolved coolant system. The second part deals with simulations that extend over combustion chamber and high-pressure vanes and speci_cally addresses the impact of the ow _eld in the combustor on the high-pressure vanes. The main objective here is to better understand wall temperature distribution on the turbine blade wall which is obtained by use of higher order statistics analysis to highlight thermally critical areas. Based on such coupled multiple component LES, a discussion is initiated to identify a path allowing to take into consideration the impact of the combustion chamber on isolated high-pressure vane simulations using di_erent reconstructed unsteady inlet conditions
Développement d'un module d'apprentissage en ligne dédié au rôle du vétérinaire officiel dans la lutte contre la tuberculose bovine à l'abattoir
Get PDFLe rôle des vétérinaires officiels dans les abattoirs d’ongulés domestiques est essentiel dans la lutte contre la tuberculose bovine. Les vétérinaires officiels doivent acquérir les compétences leur permettant de réaliser ces missions au cours de leur formation initiale. Un module d’autoapprentissage en ligne sur le rôle du vétérinaire officiel dans la lutte contre la tuberculose bovine a été créé. Ce module et sera mis à disposition des étudiants dès la rentrée 2021 sur la plateforme Moodle de l’École Nationale Vétérinaire de Toulouse. Ce module comporte cinq parties : (i) le contexte sanitaire rencontré à l’abattoir, (ii) la méthodologie d’une inspection post mortem, (iii) les types de lésions tuberculeuses et leurs stades d’évolution, (iv) la sanction de l’inspection en ce qui concerne la carcasse, et (v) les démarches à suivre lors de la réalisation des prélèvements. Ce module est interactif et comporte de nombreuses photographies
Effet de taille et de nature des charges sur les propriétés thermiques et mécaniques de micro et nanocomposites à matrice PEEK
No full textLes propriétés des composites sont gouvernées par les propriétés de chacun des constituants et par leurs interactions à l’interface. Dans les nanocomposites, cette surface de contact est plus élevée à taux de charge constant, ce qui rend prépondérant le rôle de l’interface. Ce rôle est d’autant plus dominant que la taille des charges diminue; en passant d’une charge micronique à nanométrique, la surface spécifique augmente d’un facteur 1 000 pour des sphères. Pour les nanocomposites, l’objectif des chercheurs est de prédire comment la chimie et la morphologie de la matrice sont en synergie avec la chimie de surface, la taille et la forme des charges nanométriques pour définir les propriétés du matériau résultant
Populating MBSE Models from MDAO Analysis
No full textOver the past decade, Systems Engineering has
switched from document-centric approaches to model-based ones. In this context, Model Based System Engineering (MBSE) andMultidisciplinary Design Analysis and Optimization (MDAO)
have emerged as two complementary disciplines. How to combine MBSE and MDAO approaches for the benefits of systems
engineers is still an open issue. This paper discusses a case study of coupling MBSE and MDAO. The MBSE part relies on SysML and timed automata, two modeling languages that are supported by the TTool and UPPAAL-SMC tools, respectively. The MDAO part is developed in the context of Open MDAO. The paper uses a drone as a case study and focuses discussion on battery usage. The SysML model of the drone is enhanced with a timed automata model of the battery. The SysML model of the battery is populated with results from MDAO analysis. In this context, combining SysML, UPPAAL-SMC and Open-MDAO offers to improve self-confidence in some values lying in the model,improve self-confidence in the requirements satisfaction, as well as to refine some requirements values with better accurac
Description of the variation of retention versus pH in nanofiltration of organic acids
Get PDFNanofiltration can be used to recover chemicals, like VFAs, produced by the fermentation of biomass. Solution pH is a key parameter for fermentation as well as for recovery using nanofiltration. Current work reports an experimental investigation carried out with single and mixed solutions that contain acetic, propionic, and butyric acids, at various concentrations and pHs. It is shown that retention of VFAs increases with solution pH following an S-shaped curve related to the VFA dissociation. Retentions of VFAs decrease with the concentration, the influence being negligible at low pH values and more significant at high pH values. A simple model is proposed to calculate VFAs retentions versus pH for different concentrations and a given filtration flux, considering the dissociation of VFAs and the retention of dissociated and undissociated solutes. Calculated retentions can fit well with the experimental ones, on condition to consider solutes pKa values slightly higher than theoretical ones, up to 1.24 pH units, or a variation of the membrane charge with pH, corresponding to an effective membrane pKa between 5.44 and 5.80. Both assumptions are supported by previous investigations
Impact of body inclination on the flow past a rotating cylinder
Get PDFThe rotation applied to a circular cylinder, rigidly mounted in a current perpendicular to its axis can result in the suppression of vortex shedding and of the associated force fluctuations. It also causes the emergence of a myriad of two- and three-dimensional flow regimes. The present paper explores numerically the impact of a deviation from the normal incidence configuration, by considering a rotating cylinder inclined in the current. The Reynolds number based on the body diameter and the magnitude of the current velocity component normal to its axis (U⊥) is set to 100. The range of values of the rotation rate (ratio between body surface velocity and U⊥, α ∈ [0, 5.5]) encompasses the two unsteady flow regions and three-dimensional transition identified at normal incidence. The inclination angle (θ) refers to the angle between the current direction and the plane perpendicular to the cylinder axis. A low inclination angle (θ ∈ {15◦,30◦}), i.e. slight deviation from normal incidence (θ = 0◦), has a limited influence on the global evolution of the flow with α, which can be predicted via the independence principle (IP), based on U⊥ only. This highlights the robustness of prior observations made for θ = 0◦. Some effects of the axial flow are however uncovered in the high-α range; in particular, the single-sided vortex shedding is replaced by an irregular streamwise-oriented structure. In contrast, a large inclination angle (θ = 75◦) leads to a major reorganization of flow evolution scenario over the entire α range, with the disappearance of all steady regimes, the occurrence of structures reflecting the pronounced asymmetry of the configuration (oblique shedding, strongly slanted vorticity tongues) and a dramatic departure of fluid forces from the IP prediction
Predicting the propagation of acoustic waves using deep convolutional neural networks
Get PDFA novel approach for numerically propagating acoustic waves in two-dimensional quiescent media has been developed through a fully convolutional multi-scale neural network following a spatio-temporal auto- regressive strategy. This data-driven method managed to produce accurate results for long simulation times with a database of Lattice Boltzmann temporal simulations of propagating Gaussian Pulses, even in the case of initial conditions unseen during training time, such as the plane wave configuration or the two initial Gaussian pulses of opposed amplitudes. Two different choices of optimization objectives are com- pared, resulting in an improved prediction accuracy when adding the spatial gradient difference error to the traditional mean squared error loss function. Further accuracy gains are observed when performing an a posteriori correction on the neural network prediction based on the conservation of acoustic energy, indicating the benefit of including physical information in data-driven methods. Finally, the method is shown to be capable of relaxing the classical time-step constraint of LBM and to provide parallel properties suitable for accelerating significantly acoustic propagation simulations
Dynamic electrical and mechanical properties of epoxy/silver nanowires composites
Get PDFThe aim of this work is to study electrically conductive composites from an epoxy matrix loaded with silver nanowires (AgNWs). Dynamic mechanical analysis (DMA) and dynamic dielectric spectroscopy (DDS) were used to study the molecular mobility of the epoxy matrix and its epoxy/AgNWs composites. The influence of the epoxy/amine ratio on the macroscopic properties was analyzed. The loss modulus of the epoxy matrix highlights two major relaxations, β and α. The β relaxation is due to the localized mobility initiated by hydroxyl groups. The α trelaxation is the anelastic effect liberated at the glass transition. The introduction of a small amount of AgNWs (<8 vol%) has practically no influence on the mechanical properties of the glassy state. For the rubbery state, AgNWs cause an increase in the storage modulus as a function of the filler content. The loss modulus profile is modified: The ω relaxation due to heterogeneities of the 3D network is observed independently from the hydration level of composites. The magnitude of the α mode is increased due to the stick– slip phenomenon. Moreover, it is shifted toward lower temperatures upon the introduction of AgNWs. In other words, the activation enthalpy decreases for both modes. Electrical study through DDS and conductivity measurement of epoxy/AgNWs composites shows the consequence of a lower relative degree of conversion caused by the insertion of AgNWs. Epoxy/AgNWs composites allow us to obtain one of the highest values of the electrical conductivity for polymerbased composites without any drastic evolution of mechanical properties
Populating MBSE Models from MDAO Analysis
No full textOver the past decade, Systems Engineering has switched from document-centric approaches to model-based ones.
In this context, Model Based System Engineering (MBSE) and Multidisciplinary Design Analysis and Optimization (MDAO) have emerged as two complementary disciplines. How to combine MBSE and MDAO approaches for the benefits of systems engineers is still an open issue. This paper discusses a case study of coupling MBSE and MDAO. The MBSE part relies on SysML and timed automata, two modeling languages that are supported by the TTool and UPPAAL-SMC tools, respectively. The MDAO part is developed in the context of Open MDAO. The paper uses a drone as a case study and focuses discussion on battery usage. The SysML model of the drone is enhanced with a timed automata model of the battery. The SysML model of the battery is populated with results from MDAO analysis.
In this context, combining SysML, UPPAAL-SMC and Open-MDAO offers to improve self-confidence in some values lying in the model, improve self-confidence in the requirements satisfaction, as well as to refine some requirements values with better accuracy