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

Classification of large-scale environments that drive the formation of mesoscale convective systems over southern West Africa

Mesoscale convective systems (MCSs) are frequently observed over southern West Africa (SWA) throughout most of the year. These MCS events are the dominant rain-bearing systems, contributing over 50 % of annual rainfall over SWA. However, it has not yet been identified what variations in typical large-scale environments of the seasonal cycle of the West African monsoon may favour MCS occurrence in this region. Here, nine distinct synoptic states are identified and are further associated with being a synoptic-circulation type of either a dry, transition, or monsoon season using self-organizing maps (SOMs) with inputs from reanalysis data. We identified a pronounced annual cycle of MCS numbers with frequency peaks in April and October that can be associated with the start of rainfall during the major rainy season and the maximum rainfall for the minor rainy season across SWA, respectively. Comparing daily MCS frequencies, MCSs are most likely to develop during transition conditions featuring a northward-displaced moisture anomaly (2.8 MCSs per day), which can be linked to strengthened low-level westerlies. Considering that these transition conditions occur predominantly during the pre- and post-monsoon period, these patterns may in some cases be representative of monsoon onset conditions or a delayed monsoon retreat. On the other hand, under monsoon conditions, we observe weakened low-level south-westerlies during MCS days, which reduce moisture content over the Sahel but introduce more moisture over the coast. Finally, we find a majority of MCS-day synoptic states exhibiting positive zonal wind shear anomalies. Seasons with the strongest zonal wind shear anomalies are associated with the strongest low-level temperature anomalies to the north of SWA, highlighting that a warmer Sahel can promote MCS-favourable conditions in SWA. Overall, the SOM-identified synoptic states converge towards high-moisture and high-shear conditions on MCS days in SWA, where the frequency at which these conditions occur depends on the synoptic state.</p

Lessons learned from implementing health coaching in the heart healthy lenoir hypertension study

Background: Health coaching is increasingly important in patient-centered medical homes. Objectives: Describe formative evaluation results and lessons learned from implementing health coaching to improve hypertension self-management in rural primary care. Methods: A hypertension collaborative was formed consisting of six primary care sites. Twelve monthly health coaching phone calls were attempted for 487 participants with hypertension. Lessons Learned: Participant engagement was challenging; 58% remained engaged, missing fewer than three consecutive calls. Multivariate analyses revealed that older age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01–1.05), African American race (O,R 1.73; 95% CI, 1.15–2.60), greater number of comorbidities (OR, 1.17; 95% CI, 1.05–1.30) and receiving coaching closer to enrollment (OR, 5.03; 95% CI, 2.53–9.99) were correlated independently with engagement. Participants reported the coaching valuable; 96% would recommend health coaching to others. Conclusions: Health coaching in hypertension care can be successful strategy for engaging more vulnerable groups. A more tailored approach may improve engagement with counseling

A community-based lifestyle and weight loss intervention promoting a Mediterranean-style diet pattern evaluated in the stroke belt of North Carolina: the Heart Healthy Lenoir Project

Abstract Background Because residents of the southeastern United States experience disproportionally high rates of cardiovascular disease (CVD), it is important to develop effective lifestyle interventions for this population. Methods The primary objective was to develop and evaluate a dietary, physical activity (PA) and weight loss intervention for residents of the southeastern US. The intervention, given in eastern North Carolina, was evaluated in a 2 year prospective cohort study with an embedded randomized controlled trial (RCT) of a weight loss maintenance intervention. The intervention included: Phase I (months 1–6), individually-tailored intervention promoting a Mediterranean-style dietary pattern and increased walking; Phase II (months 7–12), option of a 16-week weight loss intervention for those with BMI ≥ 25 kg/m2 offered in 2 formats (16 weekly group sessions or 5 group sessions and 10 phone calls) or a lifestyle maintenance intervention; and Phase III (months 13–24), weight loss maintenance RCT for those losing ≥ 8 lb with all other participants receiving a lifestyle maintenance intervention. Change in diet and PA behaviors, CVD risk factors, and weight were assessed at 6, 12, and 24 month follow-up. Results Baseline characteristics (N = 339) were: 260 (77 %) females, 219 (65 %) African Americans, mean age 56 years, and mean body mass index 36 kg/m2. In Phase I, among 251 (74 %) that returned for 6 month follow-up, there were substantial improvements in diet score (4.3 units [95 % CI 3.7 to 5.0]), walking (64 min/week [19 to 109]), and systolic blood pressure (−6.4 mmHg [−8.7 to −4.1]) that were generally maintained through 24 month follow-up. In Phase II, 138 (57 group only, 81 group/phone) chose the weight loss intervention and at 12 months, weight change was: −3.1 kg (−4.9 to −1.3) for group (N = 50) and −2.1 kg (−3.2 to −1.0) for group/phone combination (N = 75). In Phase III, 27 participants took part in the RCT. At 24 months, weight loss was −2.1 kg (−4.3 to 0.0) for group (N = 51) and −1.1 kg (−2.7 to 0.4) for combination (N = 72). Outcomes for African American and whites were similar. Conclusions The intervention yielded substantial improvement in diet, PA, and blood pressure, but weight loss was modest. Trial registration clinicaltrials.gov Identifier: NCT0143348

Développement des ressources humaines dans le domaine des technologies de l'information et de la communication au Bénin

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Déterminants de la performance de remboursement dans les institutions de microfinance au Bénin?

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