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241.
Theoretical and Applied Climatology - Bangladesh is one of the countries in the north-eastern part of South Asia, and it covers an area of about one hundred forty-eight thousand (1.48 × 105)... 相似文献
242.
Azad Md. Abul Kalam Islam Abu Reza Md. Towfiqul Ayen Kurratul Rahman Md. Siddiqur Shahid Shamsuddin Mallick Javed 《Theoretical and Applied Climatology》2022,148(3-4):1261-1278
Theoretical and Applied Climatology - Understanding changes in monsoon precipitation patterns is crucial as it determines the occurrence, intensity, and duration of floods and droughts in... 相似文献
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ATM Sakiur Rahman Md. Kamruzzama Chowdhury Sarwar Jahan Quamrul Hasan Mazumder 《Journal of the Geological Society of India》2016,87(2):179-193
In Bangladesh, agriculture plays a major role in the national economy. In the drought prone Barind area in NW Bangladesh, cropping intensity has increased almost double since late eighties of last century (from 1985) because of the introduction of groundwater irrigation. Long-term behavior of groundwater table (GWT) in the drought prone Barind area has been studied using MAKESENS model in the wake of massive installation of tube-wells. The study reveals that the maximum and minimum depths to GWT during 1991-2010 show on average declining trend of 4.51 m and 4.73 m. The long-term prediction for the period of 2020-50 assuming the current rate of groundwater withdrawal is that the declining trend will be 1.16 to 1.59 and 1.07 to 1.82 times more for maximum and minimum groundwater depths respectively in comparison to the present. The rigorous exploitation of groundwater for irrigation, decreasing rainfall and surface geological attributes lead towards declining trend of GWT. This will hamper the country’s food security and ultimately threaten its socio-economic sustainability. So the appropriate strategies for the management of groundwater resource on a sustainable basis should be the priority for maintaining agricultural productivity. 相似文献
248.
Utilization of bituminous limestone ash from EL-LAJJUN area for engineering applications 总被引:1,自引:1,他引:0
The following work aims at minimizing the environmental impact of the solid wastes (ash) that is produced after the utilization
of the bituminous limestone in thermal power stations and /or retort processes. Limy ash has been prepared from the El-Lajjun
bituminous limestone by direct combustion at 1,200, 950, and 525°C respectively. The laboratory tests have been selected with
respect to construction needs and possible post construction conditions. Utilization of the various types of ash in the stabilization
problematic soils from Jordan as brown soils and the clayey marl has revealed optimum results. The unconfined compressive
strength of the parent brown soil and the clayey marl has been raised from 5 kg/cm2 to 50 and 25 kg/cm2, respectively. The CBR value has been raised from 4.5 to 150% for both problematic soil types. Various mortars and construction
elements can be produced at normal room curing temperature without the use of ordinary Portland cement (OPC). Low quality
sub-base and base course can be mixed with ash to produce cement treated base (CTB) and roller compacted concrete (RCC) without
OPC. Durable pavements, embankments can be constructed with very long life and low cost. CTB and RCC utilizing ash can be
used in dam construction instead of normal soil in earth fill dams. The high alkalinity of El-Lajjun ash is considered as
a disadvantage to be utilized in normal concrete mixes for structural purposes. Ash only can be mixed with aggregates to produce
lean concrete like for blinding purposes to be prepared for foundation activities. 相似文献
249.
Flow‐through column experiments were carried out to investigate the influence of pH on the sorption of three phenols (2‐methyl‐4, 6‐dinitrophenol, 2, 4, 6‐trichlorophenol, pentachlorophenol) onto a natural sandy aquifer material collected from a bank filtration site of River Elbe, Germany. For the phenols investigated, an increase in sorption (retardation) with decreasing pH is observed indicating a stronger sorption of the neutral species in comparison to that of the anions formed by dissociation. The anions of 2‐methyl‐4, 6‐dinitrophenol and 2, 4, 6‐trichlorophenol do not show significant sorption. On the contrary, pentachlorophenol showed sorption not only in neutral form but also in ionic form significantly which should be taken into account while assessing the fate and transport of such compound. A linear model based on the degree of protonation (calculated from pH and pKa) can be used to resolve the apparent (observed) sorption coefficient (Kd, app) into its neutral (Kd, n) and ionised (Kd, i) components. Knowing pKa, Kd, n, and Kd, i the apparent sorption coefficient for pH values other than experimentally investigated can be predicted. 相似文献
250.
Matiur Rahman 《Ocean Engineering》1987,14(1)
An approximate analytical analysis is demonstrated in this research note to obtain the approximate wave forces on rectangular caissons fixed vertically on the sea-bed. A data plot has been depicted to show the effect of linear forces for the case of rectangular caissons and that for the case of square caissons. 相似文献