Wave forecasting dependent from bottom roughness: The case of the Marano and Grado Lagoon

Several forecasting curves have been developed in order to provide a useful estimation of the wind wave field generated on shallow depths. In particular, these equations can be successfully applied in confined and sheltered basins, such as lakes, or even lagoons and semi \u2013 enclosed estuarine in coastal environments. The important role of the bottom friction dissipation in the generation process has been deeply recognized, leading to a reformulation of the available curves in terms of the equivalent bed roughness. In the present study, the recent new set of equations is considered and applied to a coastal lagoon. The results in terms of significant wave height and peak period are compared to those derived from a complete numerical model and other previous curves. The performed application corroborates and further validate the forecasting equations

A complete morphodynamic study to face a river engineering issue

The last reach of the Tagliamento River, in North East Italy, is progressively changing its planimetric geometry, causing sediment deposition close to a port and preventing the regular navigation in that area. In the present paper, this river engineering issue has been addressed in a complete way, first investigating the cause which brought to the present situation, and then proposing a number of design solution to mitigate the problem. Some of them have been analyzed by means of a morphodynamic numerical model, reproducing the effects on the bottom height of an average year in terms of flow and tides. The results of each simulation are compared to those of the present situation, in order to underline any advantages of the proposed design solution

The tidal prism as a dynamic response of a nonlinear harmonic system

As known, the empirical relationship between the equilibrium cross-sectional area of a lagoon inlet and the tidal prism was intuited for the first time by LeConte ["Discussion on the paper, "Notes on the improvement of river and harbor outlets in the United States"by D. A. Watt,"Trans. ASCE 55, 306-308 (1905).] and then formalized by O'Brien ["Estuary tidal prism related to entrance areas,"Civ. Eng. 1(8), 738-739 (1931)]. This relationship requires knowledge of the tidal prism, which can be estimated either using the cubature method or the current data method [Jarrett, Tidal Prism-Inlet Area Relationships (Coastal Engineering Research Center, US Army Corps of Engineers, Fort Belvoir, VA, 1976)], both of which involve the execution of a number of experimental measurements. However, these methods, besides being very expensive, can only provide the prism value in the present condition and do not allow for predictions in the case of significant morphological changes, of both natural and anthropic origin, to the tidal inlet. On the other hand, the hydrodynamic relationship, which links the tidal prism to the product of the tidal range and the basin extension, can only give a coarse estimate of the prism, especially when the value of the tide outside the lagoon is considered. In this work, we propose a simple hydrodynamic relationship based on the dynamic response of a nonlinear harmonic system. This is a relationship that requires the calibration of a single physically based parameter. Through this relationship, knowing the geometric characteristics, the bottom friction of the inlet channel, the surface of the basin, and the tide amplitude in the open sea, it is possible to estimate the tidal prism. The application of this relationship to real cases shows a good agreement with the experimental data

Post Harvest Losses: A Dilemma in Ensuring Food Security in Nigeria

Nigeria is a country rich in a great supply of agricultural products but post-harvest losses is a great concern. Majority of our farm produce are lost to pest, rodents, and deterioration, due to lack of proper post- harvest process and storage. The major problems are  improper handling, lack of proper storage and packaging, This paper reviews this problems, the approach that can be used in reducing this problem, the role of government and individuals in combating this problem was also discussed. Keywords: Postharvest loss, Improper handling, Process, Storage

Evaluation of acute and subacute toxicity of Alstonia congensis Engler (Apocynaceae) bark and Xylopia aethiopica (Dunal) A. Rich (Annonaceae) fruits mixtures used in the treatment of diabetes

The present study was carried out to evaluate acute and subacute toxicity of a hydroalcoholic extract of a mixture (1:1) of A. congensis bark and X. aethiopica fruits used locally in the treatment of diabetes.Acute toxicity of the extract was evaluated in Swiss albino mice. The animals were fed with the hydroalcoholic extract between the doses of 1.0 to 20.0 g/kg body weight and were observed continuously for the first 4 h and for every hour for the next 24 h, then 6 hourly for 48 h. Wistar rats were also fed with different doses of the extract for 30 days and effects on biochemical parameters evaluated (subacute toxicity model). The LD50 of the extract was found to be above 20.0 g/Kg bodyweight. There was reduction in the plasma glucose and low-density lipoprotein (LDL)-cholesterol levels, and increase in high-density lipoprotein (HDL)-cholesterol level in the treated animals. A significantincrease in the body weight was observed for groups treated with lower doses of the extract while groups treat with higher doses showed no significant weight increase. Aspartate aminotransferases(AST) and alanine aminotransferases (ALT) levels were not affected at lower doses of the extract but there was increase in creatinine levels in all the treated animals. The extract demonstrated good hypoglycaemic effects by lowering the plasma sugar level and also had some beneficial and reduction effects on cardiovascular risk factors. There was no evidence of drug-induced symptoms or death at all the doses of the extract administered in acute study but subacute results revealed a tendency to cause kidney problems on a long-term use

Evaluation of acute and subacute toxicity of Alstonia congensis Engler (Apocynaceae) bark and Xylopia aethiopica(Dunal) A. Rich (Annonaceae) fruits mixtures used in the treatment of diabetes

The present study was carried out to evaluate acute and subacute toxicity of a hydroalcoholic extract of a mixture (1:1) of A. congensis bark and X. aethiopica fruits used locally in the treatment of diabetes.Acute toxicity of the extract was evaluated in Swiss albino mice. The animals were fed with the hydroalcoholic extract between the doses of 1.0 to 20.0 g/kg body weight and were observed continuously for the first 4 h and for every hour for the next 24 h, then 6 hourly for 48 h. Wistar rats were also fed with different doses of the extract for 30 days and effects on biochemical parameters evaluated (subacute toxicity model). The LD50 of the extract was found to be above 20.0 g/Kg bodyweight. There was reduction in the plasma glucose and low-density lipoprotein (LDL)-cholesterol levels, and increase in high-density lipoprotein (HDL)-cholesterol level in the treated animals. A significantincrease in the body weight was observed for groups treated with lower doses of the extract while groups treat with higher doses showed no significant weight increase. Aspartate aminotransferases (AST) and alanine aminotransferases (ALT) levels were not affected at lower doses of the extract but there was increase in creatinine levels in all the treated animals. The extract demonstrated good hypoglycaemic effects by lowering the plasma sugar level and also had some beneficial and reduction effects on cardiovascular risk factors. There was no evidence of drug-induced symptoms or death at all the doses of the extract administered in acute study but subacute results revealed a tendency to cause kidney problems on a long-term use

Ascending non-Newtonian long drops in vertical tubes

We report on theoretical and experimental studies describing the buoyancy-driven ascent of a Taylor long drop in a circular vertical pipe where the descending uid is Newtonian, and the ascending uid is non-Newtonian yield-shear-thinning and described by the threeparameter Herschel-Bulkley model, including the Ostwald-deWaele (OdW) model as a special case for zero yield. Results for the Ellis model are included to provide a more realistic description of purely shear-thinning behaviour. In all cases, lubrication theory allows obtaining the velocity pro les and the corresponding integral variables in closed form, for lock-exchange ow with a zero net ow rate. The energy balance allows deriving the asymptotic radius of the inner current, corresponding to a stable node of the di erential equation describing the time evolution of the core radius. We carried out a series of experiments measuring the rheological properties of the uids, the speed and the radius of the ascending long drop. For some tests, we measured the velocity pro le with Ultrasound velocimetry technique. The measured radius of the ascending current compares fairly well with the asymptotic radius as derived through the energy balance, and the measured ascent speed shows a good agreement with the theoretical model. The measured velocity pro les also agree with their theoretical counterparts. We have also developed dynamic similarity conditions to establish whether laboratory physical models, limited by availability of real uids with de ned rheological characteristics, can be representative of real phenomena on a large scale, such as exchanges in volcanic conduits. The Appendix contains scaling rules for the approximated dynamic similarity of the physical process analysed; these rules serve as a guide for the design of experiments reproducing real phenomena