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Öğe Bio-mediated soil improvement: the way forward(Wiley, 2020) Jiang, Ning-Jun; Tang, Chao-Sheng; Hata, Toshiro; Courcelles, Benoit; Dawoud, Osama; Singh, Devendra N.Bio-mediated soil improvement involves the usage of microbes to improve soil engineering performance through a series of bio-geochemical processes. In particular, Microbially Induced Calcite Precipitation (MICP), a ubiquitous bio-geochemical process that occurs in soil and results in permanent inorganic cementation between soil grains, has received the greatest research focus. While substantial progress has been made to develop MICP as a mainstream soil improvement technique, we still need to: (a) improve our understanding of the fundamental microbial, chemical and flow processes involved; (b) achieve multi-functionality by coupling engineering performance enhancement with ecological, environmental and carbon footprint benefits; and (c) maintain ecological balance and environmental friendliness, avoid long-term deterioration and lower the energy demand.Öğe Experimental and numerical investigations of the influence of partial replacement of coarse aggregates by plastic waste on the impact load(Taylor & Francis Ltd, 2020) Al-Tayeb, Mustafa M.; Zeyad, Abdullah M.; Dawoud, Osama; Tayeh, B. A.The effect of partial replacement of coarse aggregate by plastic waste on the performance of concrete under impact three-point bending loading was investigated experimentally and numerically. Specimens were prepared for 5%, 10% and 20 % replacements by volume of coarse aggregate. For each case, three beams of 100 mm wide, 50 mm deep and 400 mm long were loaded to failure in a drop-weight impact machine by subjecting it to 30 N weight from 400 mm height, while another three beams of the same size were tested under static load. The load-displacement of beams of concrete with plastic waste subjected to static and impact loads were studied. The dynamic beam behaviour was also analysed numerically using the finite-element method (FEM) based LUSAS software. In general, the experimental results reveal that the impact tup, inertial load and bending load increase with the increase in the percentage of coarse aggregate replacement by plastic waste, while the static peak bending load always decreases. The concrete with plastic waste is stronger and more energy-absorbing under impact loading, than under static loading. The predicted load against displacement behaviours of both ordinary concrete and concrete with plastic waste, are well matched with the experimental results.Öğe Geotechnical and geoenvironmental engineering education during the pandemic(ICE Publishing, 2021) Jiang, Ningjun; Hanson, James L.; Vecchia, Gabriele Della; Zhu, Cheng; Yi, Yaolin; Arnepalli, Dalinaidu; Courcelles, Benoît; Dawoud, OsamaThis paper reports the impact of coronavirus disease 2019 on the practice and delivery of geotechnical and geoenvironmental engineering (GGE) education modules, including lectures, lab sessions, student assessments and research activities, based on the feedback from faculty members in 14 countries/regions around the world. Faculty members have since adopted a series of contingent measures to enhance teaching and learning experience during the pandemic, which includes facilitating active learning, exploring new teaching content related to public health, expanding e-learning resources, implementing more engaged and student-centred assessment and delivering high-impact integrated education and research. The key challenges that faculty members are facing appear to be how to maximise the flexibility of learning and meet physical distancing requirements without compromising learning outcomes, education equity and interpersonal interactions in the traditional face-to-face teaching. Despite the challenges imposed by the pandemic, this could also be a good opportunity for faculty members obliged to lecture, to rethink and revise the existing contents and approaches of professing GGE education. Three future opportunities namely, smart learning, flipped learning and interdisciplinary education, are identified. The changes could potentially provide students with a more resilient, engaged, interactive and technology-based learning environment.Öğe Mapping and Quantification of Soil Erosion and Sediment Delivery in Poorly Developed Urban Areas: A Case Study(Mdpi, 2023) Dawoud, Osama; Eljamassi, Alaeddinne; Abunada, ZiyadPoorly developed regions in the Gaza Strip, Palestine, face significant risks to public safety, the environment, and stormwater infrastructure due to soil erosion and deposition. This study is the first of its kind to investigate soil erosion in this area. A revised universal soil loss equation (RUSLE) model was utilized and validated using field measurements of accumulated sediments at three major stormwater detention basins from 2014 to 2020. High-resolution maps were created to capture the urbanization effect and to further improve the future prediction of urbanization. The findings revealed that the highest potential for sediment generation in the Gaza governorate occurred over the slopes of the eastern ridge, which drain toward the city center. Sediment generation ranged from 1784 to 4281 ton/ha for the years of 2018 and 2020, respectively. The average sediment delivery ratio (SDR) was calculated to be 0.00134. The estimations for sediment export ranged from 0 to 135.3 ton/ha for the year 2020, with an average of 0.0737 ton/ha. The urban areas exhibited the least sediment export rate; however, the model revealed abnormal behavior for a dataset of the field measurements which was ascribed to the impact of destruction/reconstruction activities in the corresponded watersheds that followed the war in 2014. This conducted research stands as a pioneering effort in quantifying and cartographically representing sediment erosion potential within the Gaza Strip. Thus, it serves as an indispensable point of reference for future researchers in terms of the employed parameterization and calibration methodology. Furthermore, it holds distinct significance as an unparalleled resource for experts and stakeholders who are invested in comprehending the ramifications of erosion on urban landscapes and drainage systems.Öğe A mixed model-based Johnson's relative weights for eco-efficiency assessment: the case for global food consumption(Elsevier Inc., 2021) Abdella, Galal M.; Küçükvar, Murat; Ismail, Radwa; Abdelsalam, Abdelsalam G.; Cihat Onat, Nuri; Dawoud, OsamaAbstract Eco-efficiency composite indicators are widely accepted as the ratio of environmental impact to created economic value. These indicators are realistic measures for assessing sustainability performance considering the economy and environment. The weights reflect the importance of indicators to the aggregated environmental impacts. Estimating the relative weight of indicators is highly subjective, and therefore the search for a single unique weighting method has been going on for years. The regression-based weights are one of the most recent trends in sustainability modeling. Since these methods are designed initially to investigate the impact of multiple variables on a response variable rather than to estimate weights, some drawbacks are associated with their potential to provide proper weights. This paper presents a novel weighting approach integrating linear mixed-effect models with Johnson's relative weights to address these drawbacks and provide meaningful relative weights for eco-efficiency composite indicators. The proposed approach's operational and computational procedures are illustrated using a real example, and the eco-efficiency of food consumption of 38 countries is estimated for the period between 1990 and 2012 using a consumption-based sustainability accounting method. The findings have shown that energy use and GHG indicators are the most critical contributor to global food consumption's environmental impacts. The country-based eco-efficiency performance in this work has shown that China, India, and Russia are located in the low eco-efficiency score class. The Spatio-temporal analysis downgraded the geographical location's significance on the trends of eco-efficiency behavior in time and space. On the other hand, it revealed the different types of emerging hot spots over the world.Öğe Modification of hydraulic conductivity of sandy soil using seawater and alkaline solutions(Institute of Physics Publishing, 2020) Dawoud, OsamaAltering soil characteristics by precipitation of the calcium carbonate between soil particles is attracting the interest of geotechnical engineers for a wide range of applications. However, current applied approaches still face challenges such as the high cost of materials, difficult handling of precursors, and hazardous by-products. The study described by the current paper investigated the modification of hydraulic conductivity of sandy soil by chemical precipitation of the calcium carbonate using seawater as the source of calcium. The designed experiment involved treatment of bench-scale soil columns by two readily mixed solutions. One of the solutions served as the source of calcium ions and the other contained carbonate ions. The current paper compares behavior of hydraulic reduction considering different resources. The results showed that the crystals formed in small sizes as a result of the instantaneous reaction of calcium precipitation; and thus, crystals transport with the solution as colloids. Accordingly, reductions in hydraulic conductivity were mainly governed by the filtration mechanisms; and the precipitated calcium carbonate was retained close to the injection point. Conducting treatment using seawater as the source for calcium ions induced 65% reduction in hydraulic conductivity at 5.5 g CaCO3/g soil. This reduction is identical to the case when the artificial source was used. Further treatment by the artificial source of calcium reduced the hydraulic conductivity of sandy soil by 97.2%. These outcomes suggest that the chemically induced calcium carbonate precipitation from seawater can be employed by some geo-environmental applications which are conducted in the vicinity of the shore and require reduction of hydraulic conductivity. © Published under licence by IOP Publishing Ltd.Öğe A spatial multi-criteria analysis approach for planning and management of community-scale desalination plants(Elsevier, 2020) Dawoud, Osama; Ahmed, Taha; Abdel-Latif, Mahmoud; Abunada, ZiyadThe rapid deterioration of the groundwater quality in the Gaza Strip-Palestine has increased reliance on community-scale brackish-water desalination plants (CBDPs). However, the escalating numbers of CBDPs is associated with poor operation practices and exhibit various adverse impacts, while the existing regulatory framework of this sector is still lacking the necessary tools for identifying and mitigating these impacts. The current study employed a GIS-based Multi-criteria Analysis (MCA) approach to plan and manage the existing and proposed CBDPs in Gaza Strip, Palestine. The criteria account for the various possible effects including: level of chloride and nitrate in the groundwater, variation in the water-table depth, population density, potential production capacity of CBDPs and operation hours, distance to the pumping wells, sea shoreline, and point-source contamination sites. The results showed that the locations of around 53% of the existing CBDPs are unsuitable; and the CBDPs exhibit potential risks to the environment. The study revealed that 65% of the total area of Gaza Strip would be unsuitable for CBDPs operating in a capacity above the current average. This highlights the significance of regulating the operational conditions of the existing CBDPs according to their geographical location and considering different alternatives of supply-demand schemes.
