Sill

Local scour downstream the box culverts outlet may cause to a complete failure of the culvert structure. New research is employed to reduce the max scour depth downstream the outlet of the box culvert under a different flow conditions based on an experimental investigation. A sharp edge sill is proposed on a rigid bed to dissipate the flow excess energy. Consequently, a great reduction of the scour hole dimensions is obtained by using the sharp edge sill. The experimental study was carried out using a different positions, heights and shapes of the sharp edge sill with different flow rates as well as tail water depths too. The results indicates that the sharp edge sill is a promising tool to reduce the scour dimensions. The reduction of the scour depths by using the sharp edge sill are 60%, while the reduction in the scour depths are 64%,that is because of using of rigid apron of length 7 times the height of culvert, compared to previous results without rigid bed.

Local scour downstream the box culverts outlet may cause to a complete failure of
the culvert structure. New research is employed to reduce the max scour depth
downstream the outlet of the box culvert under a different flow conditions based on an
experimental investigation. A sharp edge sill is proposed on a rigid bed to dissipate
the flow excess energy. Consequently, a great reduction of the scour hole dimensions
is obtained by using the sharp edge sill. The experimental study was carried out using
a different positions, heights and shapes of the sharp edge sill with different flow rates
as well as tail water depths too. The results indicates that the sharp edge sill is a
promising tool to reduce the scour dimensions. The reduction of the scour depths by
using the sharp edge sill are 60%, while the reduction in the scour depths are
64%,that is because of using of rigid apron of length 7 times the height of culvert,
compared to previous results without rigid bed.

Archipelagos consist of a set of islands forming a collection of basins interconnected by straits, and are typically characterized by widely varying spatial and temporal scales regarding geometry and forcing conditions. Focusing on the strait exchange parameterization, we describe an archipelago water exchange model in which the archipelago is subdivided into a network of discrete basins and interconnecting straits and where the time integration assumes a series of quasi-steady states. We propose an algorithm that should be sufficiently flexible to provide reasonable strait exchange estimates under the variety of forcing conditions encountered in the Stockholm archipelago. We start from the functional formulation of two-layer hydraulic theory, which allows numerical schemes to be designed that, given the forcing conditions at the ends of a given strait, distinguish between maximal and sub-maximal flow cases and solve the flow accordingly. We relax the assumption of two homogeneous l...

Local scour downstream the box culverts outlet may cause to a complete failure of the culvert structure. New research is employed to reduce the max scour depth downstream the outlet of the box culvert under a dif erent flow conditions based on an experimental investigation. A sharp edge sill is proposed on a rigid bed to dissipate the flow excess energy. Consequently, a great reduction of the scour hole dimensions is obtained by using the sharp edge sill. The experimental study was carried out using a dif erent positions, heights and shapes of the sharp edge sill with dif erent flow rates as well as tail water depths too. The results indicates that the sharp edge sill is a promising tool to reduce the scour dimensions. The reduction of the scour depths by using the sharp edge sill are 60%, while the reduction in the scour depths are 64%,that is because of using of rigid apron of length 7 times the height of culvert, compared to previous results without rigid bed.

Pumiceous peperite comprising irregularly shaped apophyses of feldspar-phyric rhyolitic tube pumice and siltstone occurs within well-bedded volcaniclastic sandstone and siltstone facies of the Early Permian Berserker beds at Mount Chalmers, Australia. The tube pumice structure is preserved where sericite or silica have replaced the glass of vesicle walls and vesicles have been infilled by silica. In some instances, the peperite occurs gradationally above or below intervals of coherent feldspar-phyric rhyolite that are also predominantly pumiceous. The siltstone in the pumiceous peperite is texturally homogeneous, locally vesicular and contains shards and crystals derived from disintegration of the pumiceous rhyolite. Pumiceous rhyolite and peperite occur at various positions in the stratigraphy and may represent interconnected intrusive digits or lobes. Intrusion of the lobes was accommodated by expansion of the pore water and possible fluidisation of the host sediment, resulting in local destruction of bedding. The lobes developed chilled margins at contacts with wet sediment and inflated in response to vesiculation and the supply of new magma. Cooling of the lobes was possibly accompanied by development of microfractures in the glassy vesicle walls. Rupture of the chilled margin and propagation of fractures into the interior could have temporarily and locally depressurised the lobes, resulting in failure, disintegration and mixing with the adjacent wet and/or steam-rich sediment. Hot pumiceous rhyolite in lobe interiors may have interacted directly with the wet sediment and been dismembered by quench fragmentation and/or steam explosions. Bubbles of magmatic gas and/or steam were trapped in the sediment that mixed with the pumiceous rhyolite. The development of pumiceous texture in the sills was favoured by emplacement beneath a thin cover of wet sediment in a relatively shallow, submarine shelf setting in which the confining pressure was sufficiently low to permit vesiculation. This setting was also important in limiting the extent of degassing of the pumiceous rhyolite during cooling.

This study mainly aims to investigate the preferences of language learning strategies by English Language Teaching Department students. Oxford’s five-scale Likert type inventory, consisting of 50 items on the use of language learning strategies, was administered to 189 participants at the ELT department of Çanakkale Onsekiz Mart University, Turkey to identify the impact of gender, class, and period of English study on the use of strategies. Descriptive statistics indicated that the participants mostly preferred compensation and metacognitive strategies. Controversy, affective and social strategies were the least preferred strategies by the participants. A significant difference was found between preparatory class and 3 rd year students in terms of use of strategies. However, t-test and post hoc test did not indicate significant differences among the participants in terms of their gender, age, and period of English study.

Cooling cracks, developing from the margins of solidifying lava flows or intrusive dykes or sills, often propagate inward and divide the rock into prismatic columns. It has been shown that: (1) the initial crack pattern that forms at the surface of the body is not as regular as ...

Measurements of hydrographic conditions in the Ponta Rasa tidal mangrove swamp, Inhaca Island, Mozambique were made in August–October 1994 during the winter dry season. The Ponta Rasa swamp/creek is tidally choked on account of the narrow channel that connects it to Maputo Bay and at neap tides, a sill prevents bay water entering the creek system altogether. Temperature variation in the swamp (15–25°C) was predominantly diurnal with an additional signal due to the tidal advection of bay waters. There is no river discharge into Ponta Rasa and during the observation period, there was no significant rainfall. The mean salinity in the swamp (c. 38) was controlled by evaporation and transpiration by mangroves and an overall evapotranspiration rate of 0·5cmday−1was estimated from a steady salt balance. Salinity variation (c. 2) was predominantly due to semi-diurnal tidal advection of lower salinity Maputo Bay water into the swamp/creek. A model which incorporates tidal dynamics coupled to...

Magmatic sills have a basic tendency to form concave-upward saucer shapes. This morphology is observed in numerous seismic images and in the striking formations which dominate the landscape in South Africa's Karoo Basin. The propensity of sills to curve upward has also been suggested as a mechanism for magma ascent, particularly in compressive tectonic regions. Recent efforts that are focused