Etude thermique expérimentale des suspensions non newtoniennes en écoulement dans une conduite horizontale à géométrie variable

Dans l'industrie Agro-alimentaire, de nouveaux produits, de plus en plus complexes pour les chercheurs, sont mis en consommation. Sur ce papier nous exposons les résultats d‟une étude thermique expérimentale des suspensions non newtoniennes et pseudoplastiques en écoulement dans une conduite horizontale à géométrie variable. Ces suspensions sont constituées de grosses sphères dures dans une solution de Tylose. Elle nous a permis de mettre en exergue les limites du développement de la couche limite thermique dont la l‟augmentation est favorisée par la présence de sphères rigides dans le mélange. L‟étude met en évidence, d‟une part, l‟interdépendance entre l‟hydrodynamique et la thermique des suspensions des particules dont le diamètre moyen d est de 4,4 mm et le rapport d‟aspect d/D est égal à 0,13 et d‟autre part, les effets convectifs des particules (perturbations de la couche limite) dans des écoulements dans une conduite à géométrie variable. Cette étude nous a permis de comprendre les mécanismes de chauffage du mélange à partir de la paroi en observant une amélioration de la qualité du transfert de chaleur avec la fraction volumique des sphères dures et avec l‟utilisation d‟une conduite à géométrie variable.Mots-clés: solide-liquide, suspensions, sphères, thermique, concentration, hydrodynamique. Experimental thermal study of the non-newtonian suspensions flowing in a horizontal duct with variable geometryIn the Agri-Food industry, new products, more and more complex for researchers, are put into consumption. This paper presents the results of an experimental study of heating Non-Newtonian and pseudoplastic suspensions flowing in a horizontal pipe with variable geometry. These suspensions are composed of large hard spheres in a solution of Tylose. It helped to highlight the limits of the development of the thermal boundary layer, which the increase is enhanced by the presence of rigid spheres in the mixture. The study highlights the interdependence between hydrodynamics and thermal of the suspensions of particles with a mean diameter d is 4.4 mm and the aspect ratio d / D is equal to 0.13. It shows the convective effects of the particles (disturbances of the boundary layer) flowing in a duct with a variable geometry. This study helped us to understand the mechanisms of heating of the mixture from the wall observing an improvement in the quality of heat transfer with the volume fraction of hard spheres and with the use of a duct with variable geometry.Keywords: solid-liquid, suspension, sphere, thermal, concentration, hydrodynamics

Caractérisation du matériau bois de structures utilisé en construction par la méthode vibratoire : une technique de mesure non destructive

Le présent article décrit une nouvelle méthode non destructive de caractérisation des poutres de structures en bois. Basée sur l’excitation par vibrations, la méthode développée est fondée sur la théorie de Bernoulli et Timoshenko. Elle a été appliquée aux types de bois lamellé-collé, Laminated Veener Lumbers ainsi qu’aux composites en I, pour les règles de conception, de calculs de dimensionnement et de suivi de leur endommagement. Sur la base d’un vaste programme expérimental de caractérisation des poutres de ces différents types de bois, la comparaison des modules élastiques a été effectuée entre les valeurs estimées par la méthode vibratoire et celles fournies par la méthode statique fondée sur la mesure de la flèche relative. Les résultats obtenus mettent en évidence que la mesure du module d’élasticité par la méthode dynamique non destructive proposée peut être retenue pour caractériser les poutres en vue de la détermination des niveaux de charge des essais de comportement différé et de la durée de vie, deux facteurs phénoménologiques très importants qui, à ce jour, ne sont pas assez clarifiés dans les règles régissant les calculs des poutres à base de bois de grandes dimensions.Mots-clés : vibrations, poutres de structures, durée de vie, flexion circulaire.Characterization of structural wooden beams by vibratory method : a nondestructive technique of measurement This paper describes a new non-destructive characterization method for structural wooden beams. Based on vibrations exciting, the developed method is based on Bernoulli and Timoshenko theory. It has been applied to the lamellate-stuck types, Laminated Veener Lumbers and I composites types, for their design rules, calculations and damage monitoring. Based on an extensive experimental program of beams characterization for such different wood types, comparison of elastic modulus was made between estimated values from vibrations method and those provided by the static method funded on relative arrow or flitch measurement. The obtained results show that elasticity modulus measurement with the proposed nondestructive dynamic method can be used for wood beams characterization, in view of determination of loading levels during delayed behavior testing and lifespan studying, two very important phenomenological factors that, to date, are not sufficiently clarified in the governing rules for larger wood beams calculation.Keywords : vibrations, structures’ beams, lifespan, circular bending

Factors precipitating the risk of aspiration in hospitalized patients: findings from a multicentre critical incident technique study

Objective: To elucidate factors, other than those clinical, precipitating the risk of aspiration in hospitalized patients. Design: The Critical Incident Technique was adopted for this study in 2015. Setting: Three departments located in two academic hospitals in the northeast of Italy, equipped with 800 and 1500 beds, respectively. Participants: A purposeful sample of 12 registered nurses (RN), all of whom (i) had reported one or more episodes of aspiration during the longitudinal survey, (ii) had worked 653 years in the department, and (iii) were willing to participate, were included. Main Outcome Measure(s): Antecedent factors involved in episodes of aspiration as experienced by RNs were collected through an open-ended interview, and qualitatively analysed. Results: In addition to clinical factors, other factors interacting with each other may precipitate the risk of aspiration episodes during hospitalization: at the nursing care level (misclassifying patients, transferring tasks to other healthcare professionals and standardizing processes to remove potential threats); at the family level (misclassifying patients, dealing with the cultural relevance of eating) and at the environmental level (positioning the patient, managing time pressures, distracting patient while eating, dealing with food consistency and irritating oral medication). Conclusions: At the hospital level, an adequate nursing workforce and models of care delivery, as well as time for initial and continuing patient and family assessment are required. At the unit level, patient-centred models of care aimed at reducing care standardization are also recommended; in addition, nursing, family and environmental factors should be recorded in the incident reports documenting episodes of aspiratio

Physical and mechanical characteristics of the earthen barns used for food crop storage in the North-West of Benin (West Africa)

Atacora and Donga are two departments regarded as the barns of Benin. In these two regions, the surplus of food crops harvested by farmers is stocked in earthen barns whose primary construction material is kneaded clay soil with an admixture of vegetable straws (fonio, rice…) pounded beforehand. The following research is designed to scrutinize the variation of compression strength and/or tensile strength of the used earthen material with respect to the optimum straw content, and the fluctuation of the fracture related parameters. Laboratory tests have shown that an optimum straw content of 2% provides the highest compression strength with the best mechanical performances in terms of cohesion and internal angle of friction. Tensile strength, however, continues to increase with higher straw percentages with no breakpoint indication. Moreover, the laboratory determination of the composite material’s modulus of elasticity has proven that the used soil does not have a linear elastic behavior

A holistic multi-methodology for sustainable renovation

A review of the barriers for building renovation has revealed a lack of methodologies, which can promote sustainability objectives and assist various stakeholders during the design stage of building renovation/retrofitting projects. The purpose of this paper is to develop a Holistic Multi-methodology for Sustainable Renovation, which aims to deal with complexity of renovation projects. It provides a framework through which to involve the different stakeholders in the design process to improve group learning and group decision-making, and hence make the building renovation design process more robust and efficient. Therefore, the paper discusses the essence of multifaceted barriers in building renovation regarding cultural changes and technological/physical changes. The outcome is a proposal for a multi-methodology framework, which is developed by introducing, evaluating and mixing methods from Soft Systems Methodologies (SSM) with Multiple Criteria Decision Making (MCDM). The potential of applying the proposed methodology in renovation projects is demonstrated through a case study

CD90/Thy-1 is preferentially expressed on blast cells of high risk acute myeloid leukaemias

Different transformation mechanisms have been proposed for elderly acute myeloid leukaemia (AML) and secondary AML (sAML) when compared with de novo AML or AML of younger patients. However, little is known regarding differences in the immunophenotypic profile of blast cells in these diseases. We systematically analysed, by flow cytometry, 148 patients affected by de novo (100 cases) or sAML (48 cases). By defining a cut-off level of 20% of CD34+ cells co-expressing CD90, the frequency of CD90+ cases was higher in sAML (40%) versus de novo AML (6%, P < 0.001), elderly AML (>60 years) (24%) versus AML of younger patients (10%, P = 0.010) and poor- versus good-risk karyotypes (according to the Medical Research Council classification, P < 0.001). The correlation between CD90 expression, sAML and unfavourable karyotypes was confirmed by analysing the subset of CD34+ AML cases alone (91/148). Consistently, univariate analysis showed that expression of CD90 was statistically relevant in predicting a shorter survival in CD90+ AML patients (P = 0.042). Our results, demonstrating CD90 expression in AML with unfavourable clinical and biological features, suggest an origin of these diseases from a CD90-expressing haemopoietic progenitor and indicate the use of CD90 as an additional marker of prognostic value in AML