Search

This study investigates the turbulent flow characteristics around a complex pier (CP) with an elliptical pile-cap to understand the mechanics of the flow responsible for current-induced scour. The velocity data are recorded using an acoustic Doppler velocimeter for a Reynolds number of 67 745. This study gives mean velocities in different horizontal and vertical planes, Reynolds stresses, turbulent kinetic energy, and spectral analysis around the CP. The streamwise spectra with vortex-shedding frequencies and corresponding Strouhal numbers are discussed for three distinct regions generated by CP. The elliptical pile-cap shields the downward flow at the upstream of the column and the upward-moving wakes at the downstream of the CP, responsible for the sediment entrainment around a pier. In comparison, the effect of perturbed flow around the CP was considerably less than that of the simple pier, resulting in less scour around the CP for identical flow situations. Key words: bridge piers, complex piers, Reynolds stresses, scour, spectral analysis, turbulence. Cette etude examine les caracteristiques de l'ecoulement turbulent autour d'une pile complexe (PC) munie d'une semelle de piles elliptique dans le but de comprendre la mecanique de l'ecoulement causant de l'affouillement induit par le courant. Les donnees de vitesse sont enregistrees a l'aide d'un velocimetre Doppler acoustique (VDA) pour un nombre de Reynolds de 67 745. Cette etude donne les vitesses moyennes dans differents plans horizontaux et verticaux, les tensions de Reynolds, l'energie cinetique turbulente, et l'analyse spectrale autour de la PC. Les spectres de la composante longitudinale avec les frequences des decollements de tourbillons et les nombres Strouhal correspondants sont analyses pour trois regions distinctes generees par la PC. La semelle elliptique protege l'ecoulement descendant en amont de la colonne et les sillages ascendants en aval de la PC, responsables de l'entraaenement des sediments autour d'une pile. A titre comparatif, l'effet de l'ecoulement perturbe autour de la PC est considerablement inferieur a celui de la pile simple (PS), donnant lieu a moins d'affouillement autour de la PC pour des situations d'ecoulement identiques. [Traduit par la Redaction] Mots-cles : piles de pont, piles complexes (PC), tensions de Reynolds, affouillement, analyse spectrale, turbulence., 1. Introduction The prediction of scouring and the hydrodynamics of flow structures around the bridge piers in rivers are of great importance to civil and hydraulic engineers and researchers. The [...]

In semi-arid regions, production of good quality fodder is a challenge; cereal-legume intercropping can be a better alternative in improving forage yield and quality. The present study was conducted to assess the performance of feather Pennisetum (FP) in groundnut (GN) intercropping and for determining a sustainable forage cropping system. Therefore, an experiment was conducted with groundnut and feather Pennisetum as a monocrop and intercrop (2GN:1FP and 3GN:1FP), where FP was harvested at 60, 75, 90, and 120 days after sowing. The land equivalent ratio of intercropping was 15–29% higher indicating yield advantages and economic benefits over sole stands. Crude protein and fiber content was increased by 10 and 8% in intercropping, lignin content was reduced by 15% and neutral detergent fiber by 5% indicating the better quality of FP due to intercropping with GN. Intercropping of GN and FP increased the content of non-fibrous carbohydrate (13%), gas production (6.5%) and volatile fatty acids (6%) indicating better fodder digestibility. Furthermore, intercropping of GN and FP also increased the mineral content by 8-20% than sole stands. Apart from productivity, intercropping of FP and GN, improved water use efficiency over sole stand of both component crops. Considering, forage yield, quality and profitability, 3GN:1FP intercropping was superior and can be recommended as an alternative to monoculture. Our study concluded that in semi-arid regions double dual cropping of food and fodder can be achieved by intercropping which can provide opportunities to produce food and fodder simultaneously for livelihood, animal rearing and long-term sustainability. [ABSTRACT FROM AUTHOR]

ABSTRACT: Purpose: To estimate levels of serum vitamin D in patients of retinal vein occlusion (RVO) and compare with age- and sex-matched controls. Methods: A prospective case-control study of 54 patients of RVO and 54 age- and sex-matched attendants of patients presenting to a tertiary care hospital in Delhi was performed. Patients on vitamin D supplementations and RVO due to infective or immunological causes or patients of glaucoma were excluded. Serum vitamin D levels of all the study participants along with relevant blood investigations with history and examination were documented. Vitamin D deficiency was defined as <20 ng/ml Results: The mean serum vitamin D levels seen in RVO patients and the control group were 14.19 ± 5.23 ng/ml and 19.42 ± 10.27 ng/ml, respectively (P value = 0.001) with an odds ratio of 10.558 (CI = 2.34–47.50), indicating vitamin D deficiency to be strongly correlated with RVO. Maximum patients of RVO (46.3%) were seen during the winter season. The study noted hypertension [odds ratio 20.22 (CI = 5.812–70.347)], dyslipidemia, and anemia [odds ratio 4.107 (CI = 0.62–26.90)] to be the risk factors for RVO as previously proved in the literature. Smoking, diabetes, alcohol intake, and body mass index did not emerge as risk factors for RVO. Conclusion: Vitamin D deficiency is associated with RVO; hence, estimation of serum vitamin D levels should be advised as a part of routine investigations while looking for the cause of RVOs. Public health measures like food fortification with vitamin D micronutrients and public awareness towards increased sunlight exposure in the community are simple, inexpensive measures that can decrease the burden of sight-threatening disease of RVO in the community. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the higher-order turbulence statistics of flow and turbulent length scales around a complex pier (CP) and compare the results with those for a simple pier (SP). The velocity data were recorded in a laboratory flume using particle image velocimetry (PIV). The PIV data were analysed to estimate the velocity fluctuations of third order, turbulence production and dissipation rates, turbulent length scales and the contributions of burst–sweep events to the total Reynolds shear stress around the piers mounted on a rigid flat surface. The skewness and advection coefficients indicated a more asymmetric distribution of velocity fluctuations for the SP than for the CP. Ejection and sweep events illustrated the dominance of similar strengths for an extended period, downstream of the piers. The upstream turbulent kinetic energy production was similar for both piers, while the upstream dissipation rate was higher for the CP. The length scales were greater at the upstream for the case of the SP while, downstream, they were greater for the CP. The findings of this work demonstrate the importance of a pile cap in restricting downward-moving flow by showing a lower magnitude of scour-inducing turbulence parameters for the CP as compared with the SP. [ABSTRACT FROM AUTHOR]