20 research outputs found
Rural settlement and economic activity
Get PDFRural Settlement and Economic Activity is a key new addition to literature on the rural economy of Tripolitania during Antiquity. The chapters explore the geography and climate of the area and present the results of the author’s archaeological survey. Settlement types and their constructions are examined, followed by a detailed analysis of olive oil presses and their production capacity. Finally, amphora production sites are discussed, with examples of the types of amphora and their capacities. The conclusions give an overview of the rural economy of Tarhuna during the Roman period, focusing on economic aspects and offering an astonishing new picture of this highly productive landscape
The role of ausforming in the stability of retained austenite in a medium-C carbide-free bainitic steel
No full textIn this work, the influence of thermomechanical treatments, consisting of a combination of ausforming followed by isothermal holding and cooling to room temperature, on the stability of retained austenite of a carbide-free medium carbon-high silicon steel was investigated. The amount of retained austenite and its transformation to martensite for a range of ausforming treatments was determined by means of X-ray diffraction, dilatometry signal analysis, and metallographic investigation. Different amounts of deformations were applied at 600 ◦C in the austenite region prior to fast cooling into the bainitic transformation region. Four isothermal temperatures (325, 350, 375, and 400 C) with a holding time of 1800 s were selected to estimate the extent of the stability of the retained austenite after the completion of the bainitic transformation. The results show that the deformation-free austenite was more stable for the samples isothermally treated at temperatures between 325 and 350 ◦C. However, the decomposition of retained austenite to martensite during cooling to room temperature increased for isothermal holding temperatures above 350 ◦C. It was found that the stability of retained austenite was a function of the temperature and percent deformation, and the critical temperature and percent deformations were determined. It was also found that ausforming enhanced the formation of blocky-shaped retained austenite for isothermal holdings above 350 C, resulting in a decrease in retained austenite stability. The results were analyzed in terms of the influence of thermomechanical conditions on bainitic transformation and its impact on the transformation of retained austenite to martensite.This research was supported by the Ministry of Higher Education and Scientific Research in Libya with the collaboration with the Canadian Bureau for International Education (CBIE). The author also would like to thank Adriana Eres-Castellanos from CENIM-CSIC in Spain, for her informative scientific support
A novel fully convolutional network for visual saliency prediction
No full textA human Visual System (HVS) has the ability to pay visual attention, which is one of the many functions of the HVS. Despite the many advancements being made in visual saliency prediction, there continues to be room for improvement. Deep learning has recently been used to deal with this task. This study proposes a novel deep learning model based on a Fully Convolutional Network (FCN) architecture. The proposed model is trained in an end-to-end style and designed to predict visual saliency. The entire proposed model is fully training style from scratch to extract distinguishing features. The proposed model is evaluated using several benchmark datasets, such as MIT300, MIT1003, TORONTO, and DUT-OMRON. The quantitative and qualitative experiment analyses demonstrate that the proposed model achieves superior performance for predicting visual saliency.Memorial University Open Access Author's Fun
Biotechnology for gas-to-liquid (GTL)wastewater treatment: A review
Get PDFGas-to-liquid (GTL) technology involves the conversion of natural gas into several liquid hydrocarbon products. The Fischer-Tropsch (F-T) process is the most widely applied approach for GTL, and it is the main source of wastewater in the GTL process. The wastewater is generally characterized by high chemical oxygen demand (COD) and total organic carbon (TOC) content due to the presence of alcohol, ketones and organic acids. The discharge of this highly contaminated wastewater without prior treatment can cause adverse effects on human life and aquatic systems. This review examines aerobic and anaerobic biological treatment methods that have been shown to reduce the concentration of COD and organic compounds in wastewater. Advanced biological treatment methods, such as cell immobilization and application of nanotechnology are also evaluated. The removal of alcohol and volatile fatty acids (VFA) from GTL wastewater can be achieved successfully under anaerobic conditions. However, the combination of anaerobic systems with aerobic biodegradation processes or chemical treatment processes can be a viable technology for the treatment of highly contaminated GTL wastewater with high COD concentration. The ultimate goal is to have treated wastewater that has good enough quality to be reused in the GTL process, which could lead to cost reduction and environmental benefits.BT/Environmental Biotechnolog
Isolation and Identification of Organics-Degrading Bacteria From Gas-to-Liquid Process Water
No full textThe gas-to-liquid (GTL) process generates considerable amounts of wastewater that are highly acidic and characterized by its high chemical oxygen demand (COD) content, due to the presence of several organic pollutants, such as alcohols, ketones, aldehydes, and fatty acids. The presence of these organics in the process water may lead to adverse effect on the environment and aquatic life. Thus, it is necessary to reduce the COD content of GTL process water to an acceptable limit before discharging or reusing the treated water. Due to several advantages, biological treatment is often utilized as the main step in GTL process water treatment plants. In order to have a successful biotreatment process, it is required to choose effective and suitable bacterial strains that have the ability to degrade the organic pollutants in GTL process water. In this work, bacterial strains were isolated from the GTL process water, identified by 16S rRNA gene sequencing and then used in the biodegradation process. The detailed identification of the strains confirmed the presence of three organics-degrading bacteria identified as Alcaligenes faecalis, Stenotrophomonas sp., and Ochrobactrum sp. Furthermore, biodegradation experiments were carried out and confirmed that the pure culture as well as the mixed culture consortium of the bacterial strains has the ability to reduce the organic pollutants in GTL process water. However, the growth rate and biodegradation efficiency depend on the type of strains and the initial COD content. Indeed, the removal percentage and growth rate were enhanced after 7 days for all cultures and resulted in COD reduction up to 60%. Moreover, the mixed culture of bacterial strains can tolerate and treat GTL process water with a variety of ranges of COD contents.BT/Environmental Biotechnolog
Adsorption of organic water pollutants by clays and clay minerals composites: A comprehensive review
Get PDFClays and clay minerals are inexpensive, non-toxic, and naturally occurring minerals that have been utilized in water remediation as adsorbents. However, clays and clay minerals and those modified with heat, surfactants, acids, or organic-inorganic modifiers exhibit low adsorption capacity and re-generation ability towards organic water pollutants. The development of clays and clay minerals composites has gained considerable attention in recent years due to their enhanced adsorption capacity, ease of recovery from aqueous solution and improved physiochemical properties relative to raw and modified clays and clay minerals. This review aims to assess recent literature on clays and clay minerals composites including bentonite, montmorillonite and kaolinite intercalated with carbonaceous, metals, metal oxides, chitosan and polymeric materials and appraise their adsorption performance towards organic water pollutants. The review examines the effect of the composites' physicochemical properties on the adsorption performance and evaluates the adsorption mechanism as well as regeneration methods. The review also attempts to highlight the current progress in this area by assessing the outcomes of recently published articles and outline the research gaps for future research.This publication was made possible by an Award [GSRA6-2-0516-19029] from Qatar National Research Fund (a member of Qatar Foundation). The contents herein are solely the responsibility of the author[s]. Open access funding is provided by the Qatar National Library.Scopu
Assessing the scale contributing factors of three carbide-free bainitic steels: A complementary theoretical and experimental approach
No full textThe bainitic ferrite plate thickness is the main parameter that controls the strength of this type of microstructures. Such thickness has been proved to mainly depend on the austenite yield strength, the driving force for the transformation and the transformation temperature. However, no research has focused on how these parameters evolve throughout the transformation and how this evolution can affect the outcome. In this study, thermal and thermomechanical treatments have been performed in three selected steels. The treatments have been designed in such a way that all the mentioned parameters are comparable, aiming to obtain similar microstructures in terms of bainitic ferrite plate thickness. However, significant differences have been found among the microstructures, with variations in plate thickness larger than 100 nm. These results indicate that there might be other factors that take part in the scale of bainitic microstructures. To explain these differences and based on the kinetics of the transformation and on the carbon content of austenite at the end of the transformation, a possible explanation has been proposed.Team Kevin Ross
Material properties for fracture mechanics based strength assessment of cast iron water mains
Get PDFMunicipal water distribution systems in Canada and other countries include a large number of cast iron pipes that were installed almost 50 years ago. For structural integrity assessment of these pipes, the fracture mechanics approach is found to be more effective than the conventional continuum mechanics-based approach. This paper presents the mechanical properties for fracture mechanics-based strength assessment of water mains determined through testing of cast iron pipes exhumed from two cities in Canada. Microstructure analysis is conducted to understand the materials’ inherent properties. Uniaxial tensile tests are conducted to determine the stress–strain relations. The influence of the rate of loading on stress–strain behaviour and loading-unloading responses are investigated. A simplified single-edge notch beam test is used to obtain the fracture toughness. Probabilistic distributions of the parameters are provided to account for the uncertainty and variabilities observed in the test results.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Enhanced Removal of Diesel Oil Using New Magnetic Bentonite-Based Adsorbents Combined with Different Carbon Sources
No full textIn this work, new magnetic bentonite-based adsorbents combined with different carbon sources, namely, reduced graphene oxide and multiwall carbon nanotubes, were synthesized via co-precipitation method. The synthesized adsorbents were characterized using XRD, TGA, SEM, EDX, TEM, and BET analysis techniques. The adsorbents were then used to remove oil from aqueous solutions of water-in-oil emulsion by performing batch adsorption experiments. The experimental data were fitted to three isotherm models including Langmuir, Freundlich, and Sips models using non-linear regression and were compared using Akaike Information Criterion statistical model. The data analysis showed that Sips model best fits the experimental data for the adsorption of oil onto both adsorbents. The maximum adsorption capacity of oil from sips model were 81.65�mg/g and 77.12�mg/g for Fe3O4/Bent/rGO and Fe3O4//Bent/MWCNTs, respectively. The obtained kinetics data were fitted to pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Pseudo-second order kinetic model best fitted the kinetic data of both adsorbents. Overall, both adsorbents showed high removal efficiency reaching equilibrium in less than 50�min indicating that both adsorbents can be successfully utilized in industrial adsorption process. Graphical abstract: [Figure not available: see fulltext.]This publication was made possible by an Award [GSRA6-2-0516-19029] from Qatar National Research Fund (a member of Qatar Foundation). Open Access funding provided by Qatar National Library. The contents herein are solely the responsibility of the author[s]. The authors would like to acknowledge the technical support of CLU at Qatar University in performing SEM and TEM analysis.Scopu
