Autor: Ibrahim, Amir - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Numerical investigations of stilling basin efficiency downstream radial gates : A case study of New Assuit Barrage, Egypt
Autorzy:: Elberry, Mohamed
Ali, Abdelazim
Abdelhaleem, Fahmy
Ibrahim, Amir
Powiązania:: https://bibliotekanauki.pl/articles/28411659.pdf
Data publikacji:: 2023
Wydawca:: Instytut Technologiczno-Przyrodniczy
Tematy:: Flow-3D
New Assuit Barrage
riprap stability
stilling basin
verification
Opis:: Radial gates are more common than vertical sluice gates for a number of reasons. They are simpler to use, cause less flow disturbance, require less lifting force, and deliver better discharge. Radial gates are commonly used in new barrages, such as the New Assuit Barrage. Prior researchers used physical investigations to study the efficiency of stilling basin downstream radial gates, but physical studies cost a lot of money and time, so numerical solutions should be investigated. The current study aimed to explore numerically the influence of stilling basin shape and baffle block arrangement on the stability of bed protection, near-bed velocity, energy dissipation, and hydraulic jump characteristics downstream of radial gates. Different 12 discharges were investigated, and their results were compared with previous physical results to verify the performance of the numerical results. The results obtained from the numerical model from all trials are almost identical to the physical model results. Five different alternative designs were carried out numerically to enhance the design of the New Assuit Barrage (NAB) spillway stilling basin. Results showed that alternatives 4 (changing the geometry of the basin by removing the end step and concrete slab) and 5 (as alternative 4 in addition to adding rounded baffle blocks presented in two rows arranged in a staggered way) gave good velocity distribution with low turbulence, low values of near-bed velocities, and stability of bed protection. Also, it is more economical because of the lower cost of concrete and excavation.
Źródło:: Journal of Water and Land Development; 2023, 59; 126--134
1429-7426
2083-4535
Pojawia się w:: Journal of Water and Land Development
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Sequence stratigraphy of the Upper Cretaceous–Eocene Belqa Group of Jordan (southern Tethys margin)
Autorzy:: Kalifi, Amir
Ardila-Sanchez, Maria
Messaoud, Jihede Hay
Laila, Wesam Abu
Buchem, Frans van
Ibrahim, Khalil
Powell, John
Powiązania:: https://bibliotekanauki.pl/articles/24202139.pdf
Data publikacji:: 2023
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:: Tethys
stratigraphy
Jordan
Opis:: The Belqa Group of Jordan (Upper Cretaceous–Eocene) contains a remarkable succession of sedimentary lithofacies, including chalk, sandstone, chert, phosphorite, oyster mounds and organic-rich marls deposited along the passive southern margin of the Neo-Tethys Ocean. The Belqa Group is now outcropping in spectacular wadis where they can be studied in detail. The exceptional outcrops exposures provide unique opportunities for studying three-dimensional spatial facies variations. However, this 3D facies distribution requires robust time control and the combination of modern sequence stratigraphic concepts and high-resolution dating methods. We report the establishment of a regional sequence stratigraphic model that provides the temporal framework for further detailed sedimentological, palaeontological and geochemical studies. Preliminary results show a stratigraphic organization in four major depositional sequences (3rd order), which are broadly in agreement with the lithostratigraphic formations. The age dating is based on new nano-fossil analyses and C/O and Sr isotope stratigraphy. A subdivision into higher-frequency sequences (4th/5th order) significatively improves the resolution of the stratigraphic framework and our understanding of spatio-temporal distribution of the sedimentary facies. The four sequences are: 1) The B1 sequence (Upper Coniacian-Santonian), characterized by a transgressive phase of chalk-rich sedimentation (coccolithophore-dominated) and a regressive phase of a prograding siliciclastics with a distal transition to the first phosphorite-chert facies. 2) The B2 sequence (Lower Campanian) also starts with a transgressive chalk dominated facies and subsequently develops into a chert-dominated marl facies (radiolarian-dominated). The chert is locally associated with thin phosphates and coquinas, as well as organic-matter rich facies in proximal marine settings. 3) The B3 sequence (Upper Campanian) is also characterized by a transgressive chalk dominated facies. The regressive phase is constituted by dm- to m-thick phosphorite beds that were deposited coevally with giant oyster banks (decameter scale). 4) The B4 sequence (Maastrichtian-Paleocene) represents a dramatic facies change to organic-rich pelagic marls, and can probably be further subdivided. This sedimentary succession highlights both gradual and rapid changes in biogenic productivity and geochemistry. These changes are punctuated and partly driven by significant relative sea-level changes, and likely also larger scale palaeoceanographical processes that are the focus of future work.
Źródło:: Geotourism / Geoturystyka; 2023, 1-2 (72-73); 32--32
1731-0830
Pojawia się w:: Geotourism / Geoturystyka
Dostawca treści:: Biblioteka Nauki

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