Search results for "MAZ"

Rill flow resistance law under equilibrium bed‐load transport conditions

2019

In this paper, a recently deduced flow resistance equation for open channel flow was tested under equilibrium bed-load transport conditions in a rill. First, the flow resistance equation was deduced applying dimensional analysis and the incomplete self-similarity condition for the flow velocity distribution. Then, the following steps were carried out for developing the analysis: (a) a relationship (Equation) between the Γ function of the velocity profile, the rill slope, and the Froude number was calibrated by the available measurements by Jiang et al.; (b) a relationship (Equation) between the Γ function, the rill slope, the Shields number, and the Froude number was calibrated by the same …

Testing slope effect on flow resistance equation for mobile bed rills

2018

In this paper, a recently theoretically deduced rill flow resistance equation, based on a power-velocity profile, is tested experimentally on plots of varying slopes in which mobile bed rills are incised. Initially, measurements of flow velocity, water depth, cross-sectional area, wetted perimeter and bed slope conducted in 106 reaches of rills incised on an experimental plot having a slope of 14% were used to calibrate the flow resistance equation. Then, the relationship between the velocity profile parameter Γ, the channel slope, and the flow Froude number, which was calibrated using the 106 rill reach data, was tested using measurements carried out in plots having slopes of 22% and 9%. …

Estimating flow resistance in steep slope rills

2021

Recent research recognized that the slope of 18% can be used to distinguish between the ‘gentle slope’ case and that of ‘steep slope’ for the detected differences in hydraulic variables (flow depth, velocity, Reynolds number, Froude number) and those representatives of sediment transport (flow transport capacity, actual sediment load). In this paper, using previous measurements carried out in mobile bed rills and flume experiments characterized by steep slopes (i.e., slope greater than or equal to 18%), a theoretical rill flow resistance equation to estimate the Darcy-Weisbach friction factor is tested. The main aim is to deduce a relationship between the velocity profile parameter Γ, the c…

Thematic Issue on Soil Water Infiltration

2017

Interpretive Summary: When water is applied to the land surface through irrigation or rainfall, it infiltrates into the soil surface and percolates deeper through the soil profile under the influence of gravity and capillary forces. Soil infiltration is one of the most complex processes within the terrestrial hydrologic cycle, yet the process is only partially understood. Infiltration is affected by the physical, chemical and biological properties of the soil, vegetation cover, rainfall, irrigation properties, and management practices. Measurement of infiltration rate is essential in studies concerning water budget, hydrology, runoff, erosion, irrigation, drainage and water conservation. Ho…

Effects of the benzodiazepine receptor agonist midazolam and antagonist flumazenil on 5-hydroxytryptamine release from guinea-pig intestine in vitro

1990

Isolated segments of the guinea-pig small intestine and the guinea-pig stomach were vascularly perfused and the release of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid into the portal venous effluent determined by high pressure liquid chromatography with electrochemical detection. Test substances were applied intraarterially. The benzodiazepine receptor agonist, midazolam, concentration-dependently increased (by 58%, at 1 nmol/l) and decreased (by 32%, at 100 nmol/l) the release of 5-HT from small intestine preparations. Both effects were blocked by the benzodiazepine receptor antagonist flumazenil (10 nmol/l) The stimulatory effect of midazolam was also abolished in the presen…

[ 18 F]Fluoroethylflumazenil: a novel tracer for PET imaging of human benzodiazepine receptors

2001

5-(2'-[18F]Fluoroethyl)flumazenil ([18F]FEF) is a fluorine-18 labelled positron emission tomography (PET) tracer for central benzodiazepine receptors. Compared with the established [11C]flumazenil, it has the advantage of the longer half-life of the fluorine-18 label. After optimisation of its synthesis and determination of its in vitro receptor affinities, we performed first PET studies in humans. PET studies in seven healthy human volunteers were performed on a Siemens ECAT EXACT whole-body scanner after injection of 100-280 MBq [L8F]FEF. In two subjects, a second PET scan was conducted after pretreatment with unlabelled flumazenil (1 mg or 2.5 mg i.v., 3 min before tracer injection). A t…

Benzodiazepines for catatonic symptoms, stupor, and mutism.

1988

Closure to "New stage-discharge equation for the SMBF flume"

2017

Closure alle discussions sull'articolo "New stage-discharge equation for the SMBF flume"

Testing the Stage-Discharge Relationship in Sloping SMBF Flumes

2021

The Samani, Magallanez, Baiamonte, Ferro (SMBF) flume is a simple and inexpensive instrument for indirect discharge measurement that was originally proposed for use in a horizontal channel and then also applied in sloping channels. The contraction of the flow cross section, aimed at establishing a critical flow condition, is simply obtained by applying two half cylinders to the walls of a rectangular cross section. In this paper a theoretical approach previously proposed for a horizontal SMBF flume is first extended to a sloping SMBF flume and a new stage-discharge relationship is deduced. Then, this equation is experimentally tested using laboratory measurements from literature for differe…

Closure to “Experimental Study of Central Baffle Flume” by F. Lotfi Kolavani, M. Bijankhan, C. Di Stefano, V. Ferro, and A. Mahdavi Mazdeh

2020

This is a Closure of the discussions on the paper “Experimental Study of Central Baffle Flume” by F. Lotfi Kolavani, M. Bijankhan, C. Di Stefano, V. Ferro, and A. Mahdavi Mazdeh