Ice rupture hydrodynamic modeling

Le bris d'un barrage est un événement exceptionnel et rare. Toutefois, lorsqu'il se produit, il peut engendrer de nombreuses pertes aussi bien matérielles qu'humaines. La modélisation de la propagation d'ondes de crue intumescentes issues d'un bris de barrage a fait l'objet d'inombrables études durant les quarante dernières années. À ce jour, il existe de nombreux modèles commerciaux capables de prédire avec satisfaction la propagation d'une onde de crue dans un canal à surface libre. Cependant, ces modèles ne sont pas conçus pour décrire la propagation dynamique des ondes de crue dans le cas des conditions hivernales caractérisées par la présence d'un couvert de glace à la surface des rivières. Pour les analyses de sécurité ou les études d'impact, les gestionnaires d'ouvrages de retenues et d'autres aussi qui s'intéressent aux écoulements fluviaux ont donc besoin de nouveaux outils de prédiction mieux adaptés à ces conditions particulières. Cette thèse se situe dans le cadre des efforts menés actuellement pour palier ce manque. L'objectif spécifique de la présente recherche est d'étudier la propagation des ondes hydrodynamiques dans un canal recouvert d'un couvert de glace. Pour y arriver, l'analyse s'est faite en deux parties. Premièrement, une analyse statique de la réponse du couvert de glace aux vagues de différentes formes est présentée. Cette dernière, faite à l'aide de modèles numériques uni- et bi-dimendionnels, a pour but de formuler des critères simples de bris du couvert de glace en rivière. Dans la seconde partie, un nouveau modèle numérique couplé eau-glace intitulé HYDROBEAM est bâti pour simuler la propagation dynamique des ondes dans un canal recouvert de glace. Pour ce nouveau modèle couplé, les équations de Saint-Venant, sous leurs formes conservatives et en présence d'un couvert flottant, sont reformulées. Les équations de Saint-Venant sont ensuite couplées aux équations décrivant le mouvement d'un couvert de glace semi-rigide. Les résultats du modèle couplé démontrent que la présence du couvert a pour effet d'atténuer et de ralentir les ondes et que l'effet se fait ressentir surtout sur des ondes très courtes (typiquement inférieures à 100 m)

Seismic response of a steel composite bridge considering a frame scheme. Case of a conceived three spans frame bridge

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Sustainable natural adsorbents for heavy metal removal from wastewater: Lead sorption on pine bark (Pinus radiata D.Don)

Aqueous Pb(II) adsorption on pine bark (Pinus Radiata D.Don), an inexpensive and sustainable natural sorbent material, has been evaluated and the mechanism of metal retention characterized by scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray photoelectron spectroscopy (XPS). Bark pulp densities >1.5 g l-1 achieve near 100% Pb(II) removal from aqueous solutions containing 100 mg l-1 Pb(II). Adsorption rates increased with pulp density, although adsorption capacity diminished at high densities because of blockage of adsorption sites. The effects of washing and sulfuric acid activation were assessed and found to be less important than in previous metal sorption studies. Pb(II) sorption takes place mainly at the lignocellulosic C-O groups, with adsorption at phenolic sites appearing to be most significant

Influence of Wood Extractives on Moisture Sorption and Wettability of Red Oak (Quercus Rubra), Black Cherry (Prunus Serotina), and Red Pine (Pinus Resinosa)

Red oak (Quercus rubra), black cherry (Prunus serotina), and red pine (Pinus resinosa) wood samples were soxhlet extracted with various combinations of organic solvents including ethanol, toluene, and water according to ASTM 1110-96, ASTM D1107-96, TAPPI T207 OM-88 and TAPPI T204 om-88 standards.Contact angle and sorption isotherms of extracted and unextracted specimens were determined to evaluate the role of wood extractives on the wettability and sorption properties of these wood species.Extracted specimens adsorbed more water than unextracted specimens at high relative humidity in agreement with the literature. The contact angle decreased with increased extraction due to the removal of hydrophobic extractives. However, the absorption rate of water, estimated as the decrease in contact angle over time suggests physical modification of the wood surface by solvent extraction due to the migration and redistribution of hydrophobic extractives

Effects of groundcover management practices in a Fraser fir (Abies fraseri)-cover crop intercropping system on soil microbial biomass and community catabolic diversity

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Soil microbial biomass carbon (SMB-C) and nitrogen (SMB-N) as well as microbial community-level physiological profiling (CLPP) were investigated in an intercropping system involving Fraser fir, two leguminous (Dutch white clover and alfalfa) and a non-leguminous (perennial rye grass) cover crops. For each cover crop, two competition-management practices, banding and no banding, were evaluated. Conventionally-managed plots were used as controls. Soil microbial biomass was assessed at the 0-15, 15-30 and 30-35 cm soil depths and CLPP at the 0-15 cm soil depth. Cover cropping had limited early effects on soil organic carbon. However, significant increase of total soil nitrogen at the surface soil layer was observed. The leguminous cover crops with banding yielded higher SMB-C and SMB-N than the non legume. SMB-C and SMB-N significantly decreased with soil depth. Plots managed with bands averaged 559 mg SMB-C kg-1 dry soil, and plots without bands averaged 536 mg C kg-1 dry soil. For SMB-N, plots managed with bands averaged 83 mg N kg-1 dry soil, while plots without bands averaged 79 mg N kg-1 dry soil. Leguminous cover crops significantly improved microbial community diversity compared to the controls. Multivariate analysis showed that the microbial communities in plots with cover crops had a catabolic potential that differed from that of control, with the communities from the leguminous cover crops with bandings exhibiting the strongest dissimilarity. These results suggest that cover cropping with proper management can provide a good environment for microbial development and be an alternative approach to sustainable tree production.Paligwende Nikiema (1), Pascal Nzokou (1), and David Rothstein (1), and Mathieu Gouajio (2) ; 1. Department of Forestry, Michigan State University, 126 Natural Resources, East Lansing, MI 48824. 2. Department of Horticulture, Michigan State University, A428 Plant and Soil Sciences, East Lansing, MI 48824.Includes bibliographical references

Résultats des cupules de grand diamètre dans les reprises d’arthroplastie totale de hanche : suivi minimum de deux ans

La révision d’arthroplastie de la hanche en cas d’important déficit osseux acétabulaire peut être difficile. Les reconstructions avec cupule de très grand diamètre ou cupule « jumbo » (≥ 62 mm chez la femme et ≥ 66 mm chez l’homme) sont une option thérapeutique. Nous voulions évaluer la préservation et la restauration du centre de rotation de la hanche reconstruite en la comparant au coté controlatéral sain ou selon les critères de Pierchon et al. Nous voulions également évaluer la stabilité du montage à un suivi d’au moins 2 ans. Il s’agissait de 53 cas consécutifs de révision acétabulaire pour descellement non septique avec implantation d’une cupule jumbo sans ciment à l’Hôpital Maisonneuve-Rosemont. Le déficit osseux évalué selon la classification de Paprosky et al. Les cupules implantées avaient un diamètre moyen de 66 mm (62-81) chez les femmes et 68 mm (66-75) chez les hommes. L’allogreffe osseuse morcelée et massive était utilisée dans 34 et dans 14 cas respectivement. La cupule a été positionnée avec un angle d’inclinaison moyen de 41.3° (26.0-53.0). Le centre de rotation de la hanche reconstruite a été jugé satisfaisant dans 78% de cas sur l'axe médiolatéral, 71% sur l'axe craniopodal et amélioré dans 27% dans cet axe. Au recul moyen radiologique de 84.0 mois (24.0-236.4) et clinique de 91.8 mois (24.0 – 241.8): 6 cas étaient décédés, 3 perdus au suivi. On a observé le descellement radiologique dans un 1 cas, la luxation récidivante dans 5 cas et l’infection dans 4 cas. Le retrait de la cupule a été effectué dans 2 cas pour infection. L’ostéointégration des greffons osseux était complète dans tous les cas sauf 3. Les scores cliniques étaient pour le HHS de 82 +/-17, le WOMAC de 86 +/- 14 et le SF-12 physique de 46 +/- 12 et mental 53 +/-13. La cupule jumbo peut être considérée comme un moyen fiable pour gérer le déficit osseux dans les révisions acétabulaires. Elle permet de conserver ou d’améliorer la position du centre de rotation physiologique de la hanche. La fixation sans ciment favorise l’ostéointégration de la cupule et permet une stabilité à moyen terme. Le taux de complications est comparable ou inférieur à d'autres procédures de reconstruction.Acetabular implant revision with large bone defects, can be challenging. One of the reconstruction options is a large outer diameter cup or “jumbo cup” (≥62 mm in women and ≥66 mm in men). We hypothesized that cementless jumbo cups is a reliable technique to preserve or reconstruct hip center of rotation. We also evaluated stability at least 2 two years follow up. Fifty-three consecutive non septic loosening acetabular arthroplasty revisions at Hopital Maisonneuve-Rosemont where a cementless jumbo cup was used were assessed. Bone defect was evaluated according to Paprosky classification. Mean implanted component size was 66 mm (62-81) in women and 68 mm (66-75) in men. Cancelous bone chips allograft was used in 34 cases and bulk bone allograft in 14. Immediate postoperative AP view showed a mean abduction cup angle of 41.3° (26.0-53.0). Hip centre were found at satisfy position in 78% on mediolateral axis, in 71% on craniopodal axis and it was improved in 27% in this late axis. At the mean follow up of 84.0 months (24.0-236.4) radiologically and 91.8 months (24.0-241.8) clinically: 6 patients were died and 3 were lost of follow up. Complications were: dislocation in 5 cases (4 revisions with constrained liner), infection in 4 cases (2 treated conservatively and 2 revised in 2 times procedure) and radiographic loosening in 1 case. Bone graft integration was completed in all except in 3 cases. Clinically, the mean HHS was 82% +/- 17, WOMAC 86 +/- 14, physical SF-12 46 +/- 12 and mentally SF-12 53 +/- 13. Jumbo cups appear as a reliable procedure to manage bone loss in acetabular revision. It allows conservation or improvement of physiologic hip center. Also, cementless fixation promote bone integration. with subsequent cup stabilitity. The complication rate is comparable or may be less than others reconstruction procedures

Morphology and foliar chemistry of containerized Abies fraseri (Pursh) Poir. seedlings as affected by water availability and nutrition

• We present the results of a two-year (2007–2008) greenhouse study investigating the effect of water availability and nitrogen fertilization on the growth, biomass partitioning, and foliar nutrient content of Abies fraseri (Pursh) Poir. • Fertilizer and moisture content (irrigation) were varied in a factorial experiment combining four levels of irrigation and three levels of fertilization to evaluate growth and foliar nutrient content. In addition, a numerical optimization was used to estimate appropriate levels of each factor necessary to achieve simulated goals for response variables. • Irrigation increased the height growth by 12 to 35% depending on the fertilization treatment (p = 0.0001). Fertilization increased height growth by 10 to 26% (p = 0.02). A similar response was observed for stem diameter growth (SDG). Total biomass accumulation increased as result of positive response of stem and root biomass development, and foliar nitrogen content was positively affected by nitrogen fertilization and negatively affected by irrigation. The numerical optimization for simulated target growth and nitrogen content responses produced levels of input combinations with high desirability factors to achieve the target responses. • These results suggest that nutrient addition is a strong determining factor for early development of this species. The improved growth efficiency in this study is likely attributed to a combination of factors including, improved photosynthetic capacity, decreased stomatal limitations, or increased resource allocation to stems

Gas exchange parameters of 8-year-old Abies fraseri (Pursh) Poir. seedlings under different irrigation regimes

Eight-year-old Abies fraseri seedlings were grown under different irrigation regimes to determine how drought stress might affect the seedlings in terms of gas exchange parameters. In this study, net photosynthesis (Anet), transpiration rate (E), stomatal conductance (gs), intercellular CO2 (Ci), Ci to ambient CO2 (Ca) concentration ratio (Ci/Ca), intrinsic water use efficiency (iWUE), and water use efficiency (WUE) were measured on August 11 and 27. Irrigation and measurement time were statistically significant on all gas exchange parameters except WUE for irrigation and measurement time and Anet for measurement time. E and gs were significant under the irrigation and measurement time interactions. In this study, increasing irrigation generally decreased Anet, and gs, while increased E, iWUE, and Ci/Ca. On August 27, A. fraseri had higher Anet, gs, E, Ci, Ci/Ca, and lower iWUE values than August 11. However, there was a robust positive correlation between gs and Anet, while a negative correlation between gs and iWUE in A. fraseri seedlings. In general, prolonged water deficiency leads plants to decrease Anet, gs, and E while iWUE increases, contrary to the current study. A well-developed and deeper root system, especially in plants under less or no-irrigation regimes, may alleviate drought stress effects in the long run and provide an advantage in leaf gas exchange parameters. In addition, the fact that soil moisture did not differ much between treatments, although irrigation levels were different, may explain the similar behavior among individuals measured in terms of gas exchange parameters

The effect of silicone on some properties of flakeboard

Waxes are used as water repellent in wood composites, and there are only limited alternative waterrepellent systems for wood composites. The aim of this study was to investigate the effectiveness of a silicone compound as a water repellent for flakeboard and to compare the properties of boards made with silicone treated flakes to those made with commercial wax treated flakes. Three levels of silicone and wax application rates were used (0.25, 0.5, and I %). The hydrophobic nature of silicone-treated flakes was evaluated by measuring the contact angle and the rate of water absorption (W A) on the surface of the wood flake. The internal bonding strength (IB), the modulus of elasticity (MOE) and modulus of rupture (MOR) in bending regime, the W A, and the thickness swelling at edges of boards were evaluated. Results obtained showed that IB, MOE and MOR decreased as the concentration of silicone on the flakes increased from 0.25% to 1%. The IB, MOE and MOR of panels made with 0.25% siliconetreated flakes were comparable to boards made with 1% wax-treated flakes. Thickness swell at edges and WA were significantly reduced as the amount of silicone increased. No significant difference was found for the thickness swelling at edges and the W A between panels made with I % silicone-treated flakes and 1% waxtreated flakes. The silicone treated flakes had high water repellency

Periodontal disease and serum uric acid levels in the absence of metabolic syndrome: is there a link? A study on a sample of Cameroonian adults

Background: The relationship between serum uric acid level (SUA) and periodontal diseases (PD) is still controversial, and few studies have been carried out in population with no element of metabolic syndrome especially in sub-Saharan Africa. The aim of this study was to assess the relationship between PD and SUA in Cameroonian adults not suffering from metabolic syndrome. Methods: We carried out a cross-sectional study including Cameroonians aged over 18 years recruited in the general population and free of metabolic syndrome elements. They were assessed for frequency of consumption of purine-rich foods, periodontal indices (plaque index, gingival index, calculus index, pocket depth and clinical loss of attachment), and SUA. The diagnosis of PD was based on the American Academy of Periodontology criteria revised in 2015, and hyperuricemia was defined for values exceeding 70 and 60mg/L in men and women respectively. Comparison of SUA means was performed with the ANOVA test. Association between hyperuricemia and PD were evaluated using Fischer's exact test. The threshold of significance was 0.05. Results: One hundred and seventy-four participants were included (57.5% women, mean age 29 (10.39) years). The frequencies of PD were 75.9%, gingivitis (59.1%) and periodontitis (40.1%). Hyperuricemia was found in 20.45% of people with PD, with no difference in frequency comparing with those without PD. The frequency of consumption of purine-rich foods was similar in individuals with and without PD. Serum uric acid levels were not different in individuals with and without PD, and differed among periodontal indices only for calculus index, where SUA were higher in participants with the highest score (p=0.026). We found no association between hyperuricemia and PD. Conclusion: In individuals without elements of metabolic syndrome, hyperuricemia affects one in five people with PD. There appears to be no link between SUA and overall periodontal status in this population. Further studies are needed to better understand the salivary interaction between uric acid and periodontium in our population