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81.
Hamid Mohammadi Mohammad Ali Ebrahimi Farsangi Hossein Jalalifar Ali Reza Ahmadi 《Rock Mechanics and Rock Engineering》2016,49(1):303-314
In this paper a geometric computational model (GCM) has been developed for calculating the effect of longwall face on the extension of excavation-damaged zone (EDZ) above the gate roadways (main and tail gates), considering the advance longwall mining method. In this model, the stability of gate roadways are investigated based on loading effects due to EDZ and caving zone (CZ) above the longwall face, which can extend the EDZ size. The structure of GCM depends on four important factors: (1) geomechanical properties of hanging wall, (2) dip and thickness of coal seam, (3) CZ characteristics, and (4) pillar width. The investigations demonstrated that the extension of EDZ is a function of pillar width. Considering the effect of pillar width, new mathematical relationships were presented to calculate the face influence coefficient and characteristics of extended EDZ. Furthermore, taking GCM into account, a computational algorithm for stability analysis of gate roadways was suggested. Validation was carried out through instrumentation and monitoring results of a longwall face at Parvade-2 coal mine in Tabas, Iran, demonstrating good agreement between the new model and measured results. Finally, a sensitivity analysis was carried out on the effect of pillar width, bearing capacity of support system and coal seam dip. 相似文献
82.
M. N. I. Amir N. M. Julkapli S. B. Abd Hamid 《International Journal of Environmental Science and Technology》2016,13(3):865-874
It is demonstrated that single titanium dioxide (TiO2) has high potential for photodegradation of pollutants. However, it is still far from becoming an effective photocatalyst system, due to issues of adsorption process, separation, as well as dissolution. Therefore, this study highlights the high adsorption capacity, simplified separation, and the promising stability of TiO2(SY) (synthesized via sol–gel method) photocatalyst, fabricated using chitosan–TiO2(SY) and supported by glass substrate (Cs–TiO2(SY)/glass substrate) photocatalysts. Chitosan (Cs), with abundant –R–NH and NH2 groups, promotes the adsorption sites of methyl orange (MO) and OH groups for major attachment to TiO2(SY). Meanwhile, the glass substrate increases stability and assists separation of the photocatalysts. Initially, nano-TiO2(SY) has been characterized using high-resolution transmission electron microscope. Cs–TiO2(SY)/glass substrate was fabricated via dip-coating. The distribution and interface between the photocatalytic components were characterized by Fourier transform infrared absorption spectroscopy, UV–Vis diffuse reflectance spectroscopy, field emission scanning electron microscopy, and energy-dispersive spectrometer. UV–Vis analysis of the multilayer photocatalyst (2, 4, 6, and 8 layers) was further carried out by the adsorption–photodegradation, with MO as model of pollutant. Seventy percent of the total removal of MO via optimized eight layers of photocatalyst was achieved within 1 h of UV irradiation. The adsorption photocatalyst achieved 50 % with no exposure to UV light for 15 min of irradiation. It is concluded that suitable photocatalytic conditions and sample parameters possessing the multilayer photocatalyst of Cs–TiO2(SY) are beneficial toward the adsorption–photodegradation process in wastewater treatment. 相似文献
83.
Leila Gholami Abdulvahed Khaledi Darvishan Ataollah Kavian 《Arabian Journal of Geosciences》2016,9(19):729
The soil conditioner in processes of soil conservation is important especially in heavily eroded areas. Because in this study done in Educational and Research Forest Watershed of Tarbiat Modares University, north of Iran, the experiments created four treatments of control and different wood chips with rates of 0.5, 1, and 1.5 kg m?2, by rainfall simulation in rainfall intensity of 60 mm h?1, and plot scale of 1 m2 on changing ponding time, runoff coefficient, sediment concentration, and soil loss. The results showed that the average change ponding time in control treatment and wood chip treatments with rates of 0.5, 1, and 1.5 kg m?2 were 4.25, 7.48, 11.63, and 12.45 min. Also, the average change runoff coefficient in control treatment and wood chip treatments with rates of 0.5, 1, and 1.5 kg m?2 were 50.03, 26.27, 15.28, and 13.17 %. The results also indicated that the wood chips could decrease average soil loss with the rates of ?52.15, ?82.18, and ?89.35 % compared with control treatment for 0.5, 1, and 1.5 kg m?2 of wood chips, respectively. The one-way ANOVA results showed that the runoff coefficient, sediment concentration, and soil loss decreased with increasing wood chip amount, and the effect of conservation treatment was significant on study variables (R 2 = 0.99). But, the ponding time increased with increasing wood chip amount, and this effect was significant on study variables (R 2 = 0.99). 相似文献
84.
Flood is one of the most devastating natural disasters with socio-economic and environmental consequences. Thus, comprehensive flood management is essential to reduce the flood effects on human lives and livelihoods. The main goal of this study was to investigate the application of the frequency ratio (FR) and weights-of-evidence (WofE) models for flood susceptibility mapping in the Golestan Province, Iran. At first, a flood inventory map was prepared using Iranian Water Resources Department and extensive field surveys. In total, 144 flood locations were identified in the study area. Of these, 101 (70%) floods were randomly selected as training data and the remaining 43 (30%) cases were used for the validation purposes. In the next step, flood conditioning factors such as lithology, land-use, distance from rivers, soil texture, slope angle, slope aspect, plan curvature, topographic wetness index (TWI) and altitude were prepared from the spatial database. Subsequently, the receiver operating characteristic (ROC) curves were drawn for produced flood susceptibility maps and the area under the curves (AUCs) was computed. The final results indicated that the FR (AUC = 76.47%) and WofE (AUC = 74.74%) models have almost similar and reasonable results. Therefore, these flood susceptibility maps can be useful for researchers and planner in flood mitigation strategies. 相似文献
85.
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87.
Probabilistic analyses of soil consolidation by prefabricated vertical drains for single‐drain and multi‐drain systems 下载免费PDF全文
Natural soils are one of the most inherently variables in the ground. Although the significance of inherent soil variability in relation to reliable predictions of consolidation rates of soil deposits has long been realized, there have been few studies that addressed the issue of soil variability for the problem of ground improvement by prefabricated vertical drains. Despite showing valuable insights into the impact of soil spatial variability on soil consolidation by prefabricated vertical drains, available stochastic works on this subject are based on a single‐drain (or unit cell) analyses. However, how the idealized unit cell solution can be a supplement to the complex multi‐drain systems for spatially variable soils has never been addressed in the literature. In this study, a rigorous stochastic finite elements modeling approach that allows the true nature of soil spatial variability to be considered in a reliable and quantifiable manner, both for the single‐drain and multi‐drain systems, is presented. The feasibility of performing an analysis based on the unit cell concept as compared with the multi‐drain analysis is assessed in a probabilistic context. It is shown that with proper input statistics representative of a particular domain of interest, both the single‐drain and multi‐drain analyses yield almost identical results. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
88.
Pourkerman Majid Marriner Nick Hamzeh Mohammad-Ali Lahijani Hamid Morhange Christophe Amjadi Sedigheh Vacchi Matteo Maghsoudi Mehran Shah-Hosseini Majid Afarin Mohammad 《Natural Hazards》2022,112(2):1823-1849
Natural Hazards - The western Makran subduction zone is capable of producing considerable tsunami run-up heights that penetrate up to 5 km inland. In this study, we show how climate change... 相似文献
89.
Ashraf Samaneh AghaKouchak Amir Nazemi Ali Mirchi Ali Sadegh Mojtaba Moftakhari Hamed R. Hassanzadeh Elmira Miao Chi-Yuan Madani Kaveh Mousavi Baygi Mohammad Anjileli Hassan Arab Davood Reza Norouzi Hamid Mazdiyasni Omid Azarderakhsh Marzi Alborzi Aneseh Tourian Mohammad J. Mehran Ali Farahmand Alireza Mallakpour Iman 《Climatic change》2019,152(3-4):379-391
Climatic Change - By combining long-term ground-based data on water withdrawal with climate model projections, this study quantifies the compounding effects of human activities and climate change... 相似文献
90.
Natural Hazards - Hydrological modeling academic studies have focused on the response to human-caused land use changes. The effects of land use change on flood degree in the catchment basin of... 相似文献