The integration of membrane technology with nanotechnology has prompted revolutionary advances in the treatment of wastewaters. Graphene oxide and multi-walled carbon nanotubes have recently attracted attention, as they have proved to have potential in various applications. In this study, functionalized multi-walled carbon nanotubes (f-MWCNT)-graphene oxide (GO) composite was prepared and incorporated into polylactic acid (PLA) membranes via phase inversion. The effect of f-MWCNT-GO addition on the flux, heavy metals rejection and other characterization tests were investigated. Different concentrations of f-MWCNT-GO (2, 4, 6, and 8 wt.% of polymer) were used. The obtained results will demonstrate the potential application of PLA/f-MWCNT-GO in the treatment of wastewaters.
Here, bottom-up directional freezing experiments are conducted to obtain the optimal salinity gradient of the frozen. The salinity gradient is measured under small thickness and high resolution through the entire volume for a specific condition and under different freezing temperature and salinity conditions. This experimental work is distinctive at it gives the salinity measurement for each frozen layer instead of the overall frozen volume, and this gives the salinity gradient during freezing. Results obtained demonstrate there is an optimal freezing condition that enables the high salinity diffusion front to migrate/travel and leaving the lowest possible salinity level behind.
Fouling has been known as the major problem that limit the performance of membrane-based desalination processes as it causes a decrease in permeate flux with time which leads to an increase in maintenance requirements. These consequences are the result of the deposition of unwanted material on the surface of the membrane. One way to mitigate fouling tendencies is membrane surface modification by nanomaterials. In this paper, a set of experiments have been designed to investigate the antifouling behaviors of different nanomaterials. The performance of Graphene Oxide (GO) and Molybdenum disulfide (MoS2) nanomaterials were investigated by running bovine serum albumin (BSA) Deionized (DI) water as foulant for 10 hours. In addition, recovery of initial permeate flux have been tested after cleaning with DI water for 1 hour.
Freeze desalination is a promising unconventional method with the advantages of low energy consumption, enduring less corrosion, and suitable for higher brine concentration at normal pressure. Experimental study of salinity gradient development in freezing ice is limited, and a few literature addresses the time consumption of the freezing process. In this work, bottom-up directional freezing experiments are conducted to study salinity gradient development of the frozen brine under different salinity conditions. The obtained salinity gradient, on one hand is used to assess the deployment of successive freezing melting desalination method, and on the other to determine the localized brine properties used in first principle heat and mass conservation model development. Results suggest that the first principle model can be used to predict the freezing time. However, as the salinity decreases model discrepancies rise which requires further model tuning or relying on higher fidelity modeling.
The effect of crack propagation and bearings anisotropy in an overhung rotor system that is subjected to transient operation through critical whirl rotational speeds on the so called post-resonance backward whirl is investigated here. The equations of motion of the considered Finite Element model of the considered overhung rotor system with breathing crack model are numerically simulated to obtain the whirl response. The obtained whirl responses at transient operations in which acceleration effect is incorporated at different bearing conditions are evaluated for the appearance and excitation of the post-resonance backward whirl phenomena. Accordingly, the intensity and recurrence of these post-resonance backward whirl zones are found here to be affected by the crack propagation and bearings-induced damages. Therefore, capturing these damage-based post-resonance backward whirl can be proposed as damage detection approach in OH rotor systems.
Xenon oscillations is caused by the imbalance between three key parameters, flux distribution in the core, Xenon distribution, and Iodine distribution. To ensure the safe operation of nuclear power plants, nuclear operators are in need of simple and quick method to dampen such oscillations. One of such proven methods is the bang-bang method where the operator inserts and then withdraws the control rods at the right time and by the correct amount in order to eliminate xenon oscillations (Al Nuaimi et al., 2019). Finding the right time and control rods' worth for the insertion is the key to control these oscillations. The backward method along with Xenon Oscillation Elimination (XOE) code are used in this research to successfully dampen these oscillations.This research aims to find the optimum data fitting period for reactor measured data that will produce accurate results for ? and ?.
This research will focus on understanding the physics behind chip formation during machining metal syntactic foams through development of a 2D finite element (FE) model which will enable to predict cutting forces using AdvantEdge FE software. Cutting tests were conducted on the aluminium syntactic foam with varying cutting velocity and undeformed chip thickness. From the FE results, it is shown that the increase in cutting speed results in reduction of cutting force due to thermal softening of matrix alloy. However, the measured cutting force increased with increasing undeformed chip thickness is primarily due to increasing chip load. Increase in shear strength of the material is noticed with increasing volume fraction and finer hollow microsphere size which contributes to a higher magnitude of cutting force. The AdvantEdge FE model shows comparable results with the validation experiments within an error of 15%.
Transmissive CPVs (Concentrated Photovoltaics) are investigated for their ability in increasing the overall potential of CPV technology by collecting diffuse sunlight and reducing the cost associated with large tracking mechanisms for the main aim of integrating them in greenhouses. Simulation results conducted on SAM (System Advisory Model) and the experimental plan are briefly outlined in this paper.
The 3D graphene structures were expected to exhibit optimum mechanical, electrical, and multifunctional properties which can be exploited in various applications. The graphene TPMS structures have higher potential to generate such properties. A graphene gyroid 3D lattice was fabricated in this study using a self-assembly assisted hydrothermal technique. A polymer 3D printed gyroid lattice of 5% relative density was used as a sacrificial template. The SEM images of the initial polymer and output rGO lattices showed successful 3D printing and preservation of the gyroid structure after the fabrication process. The micro CT-scan images confirmed the polymer removal from the hollow internal tubes. The rGO composition was proved using Raman, EDS, and XRD. The mechanical properties were calculated from the developed compressive stress-strain curve. The measured Young's modulus was 0.23 MPa, while the measured electrical conductivity was 6.95 S/m.
Passive radiative cooling has obtained growing attention because of its potential for subambient cooling with no extra energy and zero greenhouse gas emission. This work studies the structural effect of truncated pyramid, conical, cylindrical and cubic microarrays based radiative coolers using full-wave electromagnetic simulations. It was found that the truncated pyramid microstructure not only enhanced the long wavelength infrared emissivity but also contributed to improved solar light reflection. Besides, we also propose a novel facial and scalable method to fabricate the microstructure using 3D printing.
