Newtonian and non-Newtonian two-phase flow in complex pipelines

Two-phase gas/non-Newtonian fluid flow through pipes commonly occurs in many industrial applications, such as in the chemical industry and oil and gas refineries. Many fluids used in oil and gas industries display non-Newtonian behaviour. Their rheology strongly affects pressure drop, flow structure, interface fluctuation, void fraction, heat transfer, and other flow features. In fact, non-Newtonian systems are not governed by the Newtonian law of viscosity. However, little experimental work has been devoted to studying non-Newtonian flow behaviour. This present work has conducted an experimental investigation to understand the fundamental physics of non-Newtonian two-phase (gas/ liquid) flow through pipes. In the experiments, several concentrations of Xanthan Gum were used as the non-Newtonian liquid, and both compressed air and carbon dioxide were used as gases. The flow rate and pressure of liquid and gas are changed by using a pump placed ahead of the mixing point. Pressure values are recorded by pressure sensors fixed at specific points along the pipe loop, and more than 10,000 experimental data points have been collected. The Experimental data analysis went through four categories. The first part is to calibrate all pressure sensors. The second step was applying rheology tests on our non-Newtonian Fluid to define the fluid behaviour and estimate the fluid properties. The third goal is to develop a new model for estimating pressure drop for the gas/non-Newtonian flow. The last part of the experiments is void fraction measurements. Pressure drop is one of the most challenging concerns related to industrial process design. In fact, multiphase flow process design depends on a better understanding of multiphase flow regimes. Numerous research has been done on gas/Newtonian liquid flow in horizontal and vertical pipes in the past few decades. Still, only a few research studies have been carried out to identify gas/non-Newtonian flow regimes. [1]. Creating a new model to estimate void fraction for gas-non-Newtonian flow is another objective done in the present work. The void fraction is considered one of the most important flow parameters used to describe two-phase flows in tubes. Void fraction is an important process variable for the volume and mass calculation required to transport gas-liquid mixture in pipelines, storage in tanks, metering, and custody transfer. Furthermore, it is important to determine other flow parameters such as two-phase density and viscosity or the average velocities of gas and liquid mixture. In addition, it plays a significant role in estimating and modelling two-phase pressure drop and flow pattern transitions. The created void fraction model is used to determine constants of general form posted by Butterworth[2]. Both developed void fraction models give a good estimation for the void fraction with about 5% percent errors compared with our experimental results and other available literature experimental results

Extraction of Insider Attack Scenarios from a Formal Information System Modeling

International audienceThe early detection of potential threats during the modelling phase of a Secure Information System is required because it favours the design of a robust access control policy and the prevention of malicious behaviours during the system execution. This paper deals with internal attacks which can be made by people inside the organization. Such at- tacks are difficult to find because insiders have authorized system access and also may be familiar with system policies and procedures. We are in- terested in finding attacks which conform to the access control policy, but lead to unwanted states. These attacks are favoured by policies involving authorization constraints, which grant or deny access depending on the evolution of the functional Information System state. In this context, we propose to model functional requirements and their Role Based Access Control (RBAC) policies using B machines and then to formally reason on both models. In order to extract insider attack scenarios from these B specifications our approach first investigates symbolic behaviours. The use of a model-checking tool allows to exhibit, from a symbolic behaviour, an observable concrete sequence of operations that can be followed by an attacker. In this paper, we show how this combination of symbolic execution and model-checking allows to find out such insider attack sce- narios

Potential of a polyculture of Arundo donax and Typha latifolia for growth and phytotreatment of wastewater pollution

Arundo donax and Typha latifolia are emergent macrophyte species that commonly reproduce in humid areas during warm months. This study investigated the growth and pollutant removal capacity of these two species planted in polyculture in a vertical flow filter bed for rural wastewater treatment. Plant shoot height was monitored and biomass production and nutrient uptake were assessed. Water physicochemical parameters were also monitored. A. donax showed higher height elongation (288 cm), phytomass production (2.4 kg dry biomass/m²) and nitrogen uptake (21.1 mg/kg DW) than did T. latifolia. Phosphorus and potassium retention was identical for both species. The macrophyte bed achieved higher removal rates for biochemical oxygen demand (BOD) (76%), chemical oxygen demand (COD) (82%), total suspended solids (TSS) (96%), total Kjeldahl nitrogen (TKN) (33%) and total phosphorus (TP) (46%), compared to an unplanted basin. The macrophyte species used were able to grow and to contribute to the rural wastewater purification in the adopted experimental constructed wetland.Key words: Arundo donax, Typha latifolia, wastewater, phytotreatment, nutrient uptake, constructed wetland

Adaptability of collaborative design within an augmented space

peer reviewedThis paper presents a research on the reuse of a collaborative design scenario with a co-presence of a situation of collaboration at a distance. Our interrogations are about the adaptability of activities of collaborative design at a distance within augmented spaces sheltering specific situations. Our objective is to observe the influence of space components variability on the activity and conceivers’ exchange quality. The paper presents the established method, the obtained data and the observations developed from the analysis of initial and adapted situations. With reference to our analysis, it displays the evolution of design practices, in the field of design and architecture, from constraints, means and work devices standpoints. We refer as well to the impact of ICT (Information and Communications Technology) insertion on the way of exchange between collaborators

Espaces de conception collaborative réels et augmentés : proposition pour une mesure ergonomique de l’interaction.

peer reviewedDans le domaine de la conception architecturale, l’insertion du numérique dans les activités collaboratives n’est plus seulement considéré comme l’insertion d’un outil dans le processus, mais comme un concept qui interagit avec la notion de l’espace. L’analyse de cette interaction nécessite l’élaboration d’une méthode qui permet de mesurer l’impact de l’environnement spatial sur l’activité de conception. La méthode présentée ici offre la possibilité d'analyser les différents types de configurations de travail collective, que ce soit en coprésence ou à distance, dans un espace réel ou augmenté

Impact des outils numériques de communication et d’échange d’information dans les processus de conception collaborative.

peer reviewedCet article présente les premiers résultats d’une étude sur l’articulation des pratiques numériques durant des processus de conception collaboratifs de longue durée. A l’aide d’un système dédié, nous tentons de tracer les usages d’outils de groupes de concepteurs distants et en co-présence, sur l’entièreté de leur activité de projet (douze semaines). L’étude relate les observations récoltées par notre méthode immersive originale, dans un premier contexte expérimental d’atelier de master. Notre réflexion cherche à mieux comprendre l’articulation entre les échanges d’information et les phases de conception, mais aussi les "modes de conversations". Elle montre comment ceux-ci s’articulent, entre les moments synchrones, repères temporels qui structurent le processus de points-clefs, et les conversations asynchrones, tous révélés par les outils connectés

Conception collaborative distante : étude architecturologique pour la caractérisation des opérations cognitives.

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Preuves par induction implicite : cas des théories associatives-commutatives et observationnelles

Texte intégral accessible uniquement aux membres de l'Université de LorraineAutomated induction proofs are a formal means for systems validation. In the framework of test set induction, we propose two automated proofs methods for conditional specifications: one deals with associative-commutative (AC) theories, the other with observational theories. In the first method, we give an algorithm for computing induction schemes, as well as a new inference system using elaborated AC rewriting techniques. For a class of specifications, the method detects non valid conjectures in a finite time. Interesting experiments on the correctness of digital circuits produced proofs requiring less interaction than other well-known provers. In the observational approach, data type objects are cnsidered as equal if they cannot be distinguished by experiments with observational results. These experiments are represented by particular terms called observable contexts. We propose an automated proof method of observational properties, relying on the computation of a finite set of well-chosen contexts called test contexts, that shematizes all the observable contexts. We also propose methods for computing such test contexts and a new inference system. For an interesting class of specifications, the method detects non observationally valid conjectures in a finite time.Les preuves automatiques par induction sont un moyen formel pour la validation de systèmes informatiques. Dans le cadre de l'induction par ensemble test, nous proposons deux méthodes de preuves automatiques s'appliquant à des spécifications conditionnelles : l'une opérant dans les théories associatives-commutatives (AC), l'autre dans les théories observationnelles. Dans la première méthode nous proposons un calcul des schémas d'induction, ainsi qu'un système d'inférence utilisant des techniques élaborées de réécriture modulo AC. Pour une classe de spécifications, la méthode détecte toute conjecture non valide en un temps fini. Des expérimentations intéressantes sur la correction de circuits digitaux, ont produit des preuves nécessitant moins d'interaction qu'avec d'autres prouveurs connus. Dans l'approche observationnelle, les objets d'un type de données sont considérés comme égaux s'ils ne peuvent être distingués par des expérimentations à résultats observables. Ces expérimentations sont représentées par des termes particuliers appelés contextes observables. Nous proposons une méthode de preuve automatique de propriétés observationnelles reposant sur le calcul d'un ensemble fini de contextes, appelés contextes tests, qui schématise l'ensemble de tous les contextes observables. Nous proposons également des méthodes de calcul de ces contextes tests ainsi qu'un nouveau système d'inférence. Pour une classe de spécifications, la méthode détecte toute conjecture non observationnellement valide en un temps fini

Construction 4.0: Défis technologiques ou enjeux stratégiques ?

info:eu-repo/semantics/publishe

Modélisation de la collaboration distante dans les pratiques de conception architecturale: Caractérisation des opérations cognitives en conception collaborative instrumentée

info:eu-repo/semantics/nonPublishe