A lot of research has been carried out on fabricating carbon nanotubes (CNTs) based buckypapers (or sheets, mats) by using different techniques and to explore the potential applications of these buckypapers. The most common technique is the membrane-based vacuum filtration method, which is generally slow. Another faster technique that has been advocated recently is based on tape-casting. In this paper, we compare the quality and multifunctional properties of CNT-based buckypapers that are fabricated based on both vacuum filtration and tape-casting methods. Novel types of multi-walled CNTs, provided by Lockheed Martin Company, are used in manufacturing the buckypapers.
This work considers the equiatomic CoCrNi alloy, a recent multi-principal element alloy (MPEA), which in bulk form, has shown superior mechanical properties, excellent oxidation, and corrosion resistance. Such a combination of desirable characteristics motivates further research into the potential use of CoCrNi in thin-film form for challenging applications. This study aims to grow and optimize the deposition parameters of CoCrNi thin films. The CoCrNi medium entropy alloy thin films were deposited onto silicon oxide substrates by DC magnetron sputtering at different temperatures and pressures using a pre-alloyed target. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to study the surface morphology and chemical composition of the films, respectively. The crystal structure was detected by X-ray diffraction (XRD). Furthermore, confocal microscopy was used for surface topography characterizations. This study provides new insight into the preparation of MPEA thin films which hold significant potential for future applications.
Fatigue is a failure that is initiated by a crack from an applied cyclic load led to a sudden fracture; time is a key factor that determines failure. It occurs under the static strength of the material, which is the stress that a material can withstand before it enters the plastic deformation or failure under static load. In various structural applications, the fiber-reinforced plastic composites used widely due to their high specific strength and stiffness, to withstand constant and variable amplitude fatigue loads in service. Hence, fatigue durability and high fracture toughness of the composite material are equally important as for metals. A simple fatigue testing system has designed and constructed in our lab that can test the cyclic loading behavior of the prepared composites. The machine can test composite and polymeric samples subjected to completely reversed and fluctuating fatigue loads. The S-N curve of the tested material is determined.
Fusion Deposition Modeling (FDM) 3D printing is proven to be an effective, accurate and low cost method of manufacturing where complex structures and assemblies were made easily. Mostly, products of conventional 3D printing exhibit rather rigid structures with fixed set of properties. This issue is addressed by introducing Four-Dimensional Printing (4D printing) through the use of time-active metamaterials such as the heat-activated Shape Memory Polymers (SMP). It has been previously found that 4D printed structures suffer significant shape distortion when subjected to heat for the first time (shrinkage phenomenon). Knowing that conventional 3D printing parameters such as deposition pattern and infill density play an important role in deciding the mechanical properties of the 3D printed structures, this current work investigates the effect of different deposition patterns and infill densities on the shrinkage behavior, as well as the mechanical properties, of SMP 4D printed structures.
In this work, micro-3D printing is applied to fabricate light absorbing feed spacers for air gap membrane distillation (AGMD) application. Triply periodic minimal surface (TPMS) structure is selected as the spacer model, and graphene oxide (GO) coating is applied on the 3D printed spacer to harvest solar energy more effectively. UV-visible light characterization of coated and uncoated spacers is conducted, and their impact on solar AGMD is also evaluated with permeate flux measurements.
Many applications in biomedical and terrestrial imaging require solutions of inverse radiative transfer problems for detection and image reconstruction. However, the inverse problems in radiative transfer are nonlinear, ill-posed, and underdetermined imaging problems. Solving such problems is difficult and very time intensive, and achieving good accuracy is challenging. In this study a machine learning method with neural networks is proposed to solve the inverse problem of the Diffuse Optical Tomography (DOT) medical imaging modality. The neural network model is trained to recover the location and size parameters of a single inclusion in a specific geometry. Preliminary results indicate that the neural network model can accurately recover the targeted parameters for inclusions that are larger than a certain size, thus validating the proof-of-concept.
Simulating particles behavior in microchannel considered to be an important and useful in many microfluidic applications that researchers try to understand, e.g. separation of cancer cells from blood. A dynamic behavior of polystyrene particle in water is described in this paper. Theoretical analysis of forces acting on particles is conducted. Newton's equation of motion is used to describe the trajectory of the particles. The governing equations are solved using fourth order of Runga-Kutta method. The particles assumed to be at rest at the inlet of the channel. Standing surface acoustic waves are applied to align the particles at the center of channel. The most effective forces are found to be drag force and the acoustic radiation force. The larger particle will move faster towards the centerline. The effect of added mass force, basset force, and Brownian motion are assumed to be very small and neglected for this case.
Nanoparticles have become a prominent topic in the medical field over the past several decades because of their similarity in scale with biological systems and the increased controllability over drug release and dosage in drug delivery applications. Nanoparticle material can be tuned depending on the type of application. For example, gold nanoparticles are used in cancer diagnosis and lipid nanoparticles drug delivery. Traditional synthesis of nanoparticles results in particles with high size non-uniformity. Utilizing microfluidic channels for nanoparticle generation overcomes traditional methods by its high flow controllability and microscale.
The cost of renewable energy, especially solar energy is constantly reducing, hence, encouraging more solar energy projects to develop, specifically in the United Arab Emirates. CSP systems such as parabolic dish can be used to produce the high temperatures required for these systems. This work will focus on studying and analysing a commercial parabolic dish developed by a Swedish company called Azelio. An optical model is created using a commercial software called TracePro which is used simulate how the dish system concentrates solar energy in a perfect environment. In addition, two experimental setups have been developed to measure the temperature and the flux of the dish system. The results obtained from the flux measurement setup validated the optical model. The maximum flux obtained by the optical model was 163 kW/m2 and the maximum flux obtained from the experiment was 155 kW/m2 and this resulted in a 5% loss.
In this research work, Non-premixed, counterflow, NH3-oxygen and CH4-oxygen flames with same momentum were studied in 3 various cases and a computational tool for the study of these flames was developed in a computer program and verified with grid independence study and with previous computations of the same flame. It was shown that NH3 flames has lower temperature and narrower high temperature area compare to CH4 flames in all studied cases as NH3 flame seems to be a heat-releasing sheet with minimal effect on the velocity profile. As flames transition from strainless to strained, flames achieve higher temperature while high temperature areas shrink, especially for NH3 flames which is due to the limited heat release from NH3 oxidization. The fact that maximum temperature increases with imposed strain is of course not expected for "near-equilibrium" flames and deserves serious consideration.
