Polyurethane foam has many applications and can be used as a human skin substitute. Having an accurate numerical mechanical model can be useful in predicating of the behavior of the foam in its different applications. A uni-axial compression test, simple shear test and stress relaxation tests were conducted to capture the mechanical behavior of the foam. A 3rd order Hyperfoam model was fitted to data from the uni-axial compression test data and simple shear test data and the fit based on both data simultaneously was found to be better in terms of stability for uni-axial and shear behavior. Also, stress relaxation test was done and a 3rd order Prony series was fitted to it and the fitting was found to be representative of the test data.
This work aims to investigate the effect of incorporating zeolites with different Si/Al ratio as catalyst supports in hydrocracking processes. Heptane was hydrocracked in the presence of Ni-Zeolite type Y catalysts, Ni-ZY, having four different SiO2/Al2O3 ratios of 5, 30, 60, and 80. Nickel was added by wet impregnation method to the zeolites such that to get 5 wt. % of the metal in the catalyst, and then calcined in air at 500oC for 5 hours. Various characterization methods were used to study the structure, crystallinity, morphology, acidity, and reducibility of the catalysts, some of which are included in this short manuscript. The catalytic testing of the materials were done at two hydrocracking temperatures, 350 and 400oC.
The flow and heat transfer of hybrid nanofluids in a porous curved channel subjected to a constant wall heat flux is investigated. The interactions of various transport processes, i.e. mass, momentum and energy are considered in a fully coupled manner. Transport of nanoparticles driven by various mechanisms leading to non-uniform nanoparticle distribution is emphasized. The results showed that heat transfer increases with a higher total nanoparticle volume fraction and a larger porosity.
Increased power density in modern miniaturized electronics, caused difficulty to keep electronic perform effectively, this challenge lead to search for high-performance thermal management solutions as compact heat exchanger. Conventionally manufactured heat exchangers had limitations that thwart the development of geometrically complex heat exchangers which are capable of exploiting topological aspects to enhance the thermal performance. Subsequently, additive manufacturing (AM) is proposed as a powerful fabrication technique for compact heat exchanger based on triply periodic minimal surface (TPMS). In this work, we propose 3D compact cross flow heat exchanger (CCFHE) model with geometrically complex structures based on (TPMS) developed using STARCCM+ platform. Moreover, Computational fluid dynamics (CFD) modelling is used to obtain a new Characteristics Maps that relates Heat Transfer Effectiveness (Ɛ) and Number of Transfer Units (NTU) for the proposed heat exchanger. The convection heat transfer coefficient, pressure drop, and inlet and outlet fluid temperature are anticipated utilizing CFD method.
This work investigates a hollow version of the regular hexagonal honeycomb unit cell structure for the purpose of enhancing the in-plane stiffness. A model for calculating the relative density was developed alongside the results from numerical simulations were utilized to compare the two designs. The comparison was based on the fitted parameters of the Gibson-Ashby model. The results revealed that the hollow design offers better performance for out-of-plane direction and slightly inferior performance for in-plane directions with respect to the relative density of the unit cell.
In this paper, the effective behavior of shape memory alloy (SMA) triply periodic minimal surface (TPMS) structures is investigated by means of finite element analysis and numerical homogenization. For this purpose, the onset and subsequent thresholds of phase transformation are determined considering TPMS primitive unit cells subjected to different loading conditions. At lower void ratios, the initial phase transformation loading surfaces are found to be reasonably well represented by an anisotropic Hill's criterion. The observed fit, which also depends on geometry, degenerates as the effective martensite volume fraction increases. The determination of subsequent loading surfaces as a function of the effective volume fraction of martensite shows a nonlinear hardening behavior. Ultimately, the loading surfaces are found to reach an asymptotic state with distinctly different features compared to their initial shapes.
In this work lattices were fabricated from MoS2 as well as a heterostructure of MoS2 coated with rGO and vice versa, the lattices were tested for electrical conductivities and mechanical proprieties. MoS2 powder coated well on surface of the lattice, while the heterostructure faced some agglomerations. It was noticeable to see that the highest modules of elasticity was exhibited by the MoS2 lattice, while the two heterostructure lattices showed similar mechanical and electrical proprieties.
The increase in the number of stroke patients and limited accessibility of rehabilitation devices has triggered the design and development of mobile exoskeletons. In past, numerous lower limb exoskeletons have been designed for lower extremity rehabilitation. However, most of the proposed exoskeletons are heavy, costly, and induce unnecessary weight & inertial vibration on the limb. To overcome these issues, we aim to develop a lightweight cable-driven exoskeleton that can be used for stroke patient rehabilitation. The feasibility of different configurations of exoskeletons are being analyzed. Two link-based model has been developed for each configuration using MATLAB. The passive elastic joint moment is considered as user voluntary input from the impaired leg. Our preliminary results revealed that a 4-cable configuration is promising design for rehabilitation.
In response to the COVID-19 outbreak, many governments requested social distancing and shut down schools, daycares, and extracurricular programs. The shift to homeschooling added a tremendous burden and workload for most parents. Recent study results confirmed that women took on a lot more responsibility for household chores and care of children and family during the pandemic. In that sense, female doctoral students had to make more checks and balances to accomplish their daily work, pursue their graduate studies, take care of their young children, and help them with their homeschooling. The purpose of this study is to explore female Emirati Ph.D. students' lived experiences under the pressure of the pandemic and investigate the main strategies of coping with the multiple duties they have had. This case study applies a qualitative methodology- interpretative phenomenological approach (IPA). Data were from six in-depth semi-structured interviews of a purposeful homogenous sample.
There is a remarkable increase in divorce rate in UAE, this is a danger signal, and as a social worker one of my roles is to discover the effects of divorce on the families. This researched paper will use both qualitative and quantitative research methods, to discover the impact of Divorce in the United Arab Emirates society. Mixing methods is a form of triangulation in research to minimize the weaknesses found in a single method. To collect the data I used interview with N=6, and survey including N=60 of random population from the target group, and they are children, adolescents, and parents who have experienced Divorce. The research questions are: What are the effects of Divorce on children? What are the effects of Divorce on Adolescents? and What are the effects of Divorce on Adults?
