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Item Behavior of normal and recycled aggregates beams strengthened with different types of externally bonded shear reinforcement(Elsevier, 2024-02-29)This study aims at investigating the effect of strengthening shear-deficient recycled aggregate concrete (RAC) beams with carbon fiber-reinforced polymer (CFRP) laminates. Five RAC beams were cast, four of which were strengthened with different CFRP shear strengthening configurations: U-wraps bonded at 45°, vertical U-wraps, continuous U-wraps along the shear span, and side-boned laminates. In addition, one RAC specimen was left unstrengthened to act as a benchmark specimen. For comparison purposes, an additional five normal aggregate concrete (NAC) beams were cast, three of which are strengthened with similar CFRP schemes as that of the RAC, and one was left unstrengthened. All beams are loaded under four-point bending tests, and the results in terms of shear force-deflection graphs and failure modes are analyzed and compared. Experimental results indicated that the shear force values obtained in NAC and RAC beams are comparable. In fact, the percentage increase in the shear strength compared to the respective control beam was higher for RAC beams than that of NAC beams. This proves the effectiveness of using different shear strengthening configurations and the viability of using CFRP shear strengthened RAC beams compared to CFRP shear strengthened NAC beams.Item Influence of synthesized nanomaterials in the strength and durability of cementitious composites(Elsevier, 2023-06-07)The development of high-performance materials has been prompted by a constantly expanding infrastructure with complex technical constraints. Performance modification of cement composites using nanoparticles has been thoroughly researched to address demands in the construction industry. This cutting-edge review examines the various parameters of cement composites, such as fresh properties, mechanical properties, and durability characteristics that can be improved using synthesized nanomaterials such as nano-SiO2, nano-Al2O3, graphene oxide, and carbon nanotubes, as well as their inherent limitations. Based on the detailed review, the ideal replacement levels of nano-SiO2 (1–4 wt%), nano-Al2O3 (1–3 wt%), graphene oxide (0.05–0.1 wt%), and carbon nanotubes (0.1–0.5 wt%) can be recommended for the practical applications. It has been noted that the addition of synthesized nanomaterials tends to lower the workability of cement composites. However, nanoalumina, graphene oxide, nano-silica, and carbon nanotubes improve mechanical qualities such as compressive strength, flexural strength, and resistance to abrasion of the blended cementitious system at an optimum replacement level. Similarly, resistance against chemical attacks was imporved with the addition nano-silica, while the addition of graphene oxide in cement is more effective against chloride migration and fire exposure. The overall effect of synthesized nanomaterials is also compared in the study.Item Geopolymer concrete incorporating recycled aggregates: A comprehensive review(Elsevier, 2022-02-22)Several industrial by-products are extensively used again as a supplementary cementitious material or aggregates in the interest to reduce environmental footprints in terms of energy depletion, pollution, waste disposition, resource depletion, and global warming related with conventional cement. A remarkable quantity of industrial scrap materials, primarily designated as construction and demolition waste from the construction industry, has transformed into crucial apprehension of governments. In the recent past, substantial explorations have been accomplished to appreciate the distinct characteristics of concrete, employing recycled aggregates from construction and demolition waste. Geopolymer composite is a new cementitious material, and it appears to be a potential replacement for conventional cement concrete. This paper summarises the previous research concerning the utilisation of recycled aggregate as a partial or complete supplants for conventional aggregates in geopolymer concrete. The influence of recycled aggregate addition on the fresh and hardened properties of geopolymer concrete is comprehensively reviewed in this paper. The studies suggest significant improvement in the workability on addition of recycled aggregates to geopolymer concrete. However, the addition results in increased water absorption and sorptivity.Item Design and Utilization of a Direct Methanol Fuel Cell(MDPI, 2022-12-14)This study introduces a step-by-step, summarized overview of direct methanol fuel cell (DMFC) fundamentals, thermodynamic–electrochemical principles, and system evaluation factors. In addition, a parametric investigation of a JENNY 600S DMFC is conducted to simulate cell performance behavior under varying operating conditions. The system is mathematically modeled and solved in MATLAB and accounts for multi-irreversibilities such as the activation and ohmic and concentration overpotentials. The performance of the modeled system was validated against theoretical and experimental results from the literature. The results indicated that increasing the fuel cell’s operating temperature yields enhanced output cell voltages due to enhanced methanol oxidation reactions. Nevertheless, the maximum efficiency limits of the fuel cell tend to decrease with an increase in temperature. In addition, the model has also depicted that enhanced output cell voltages are associated with increased oxygen consumption, resulting in the lower exit flowrates of the reactants.Item Remaining Shelf-Life Estimation of Fresh Fruits and Vegetables During Transportation(IEEE, 2023-01-25)During transportation, prediction of the Remaining Shelf-Life (RSL) of Fresh Fruits and Vegetables (FFVs) is critical for planning and quality cost estimation. The Internet of Things (IoT) enables measured environmental variables to be processed in real-time. However, there is a need for a validated, real-time computational method that translates environmental measurements to dynamic RSL estimates. Most existing generic RSL models for FFVs are qualitative, invasive, or static. This study establishes a generic RSL model for FFVs under dynamic and unplanned logistic conditions. The model is based on estimating the current rate of general decay based on the expected respiration rate of the product, and integrating the decay rate with respect to time. Its implementation is non-destructive, non-invasive, and does not require accelerated shelf-life experiments before deployment. In addition, since the original model is rather computationally intensive, a surrogate model was proposed to allow the model to be implemented in fast, real-time applications for ‘Edge IoT.’ Experimental validation of the model using three fresh products (strawberries, apricots, and spinach) in a domestic refrigerator resulted in a maximum deviation of 1.3 days in prediction error using the original model and 2.95 days using the surrogate model. Nonetheless, the predictions made using either the original or surrogate models were statistically sound and not significantly different from the observed shelf lives of the samples, even at the 0.01 significance level.
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