Analysis of the distribution of thermal residual stresses in bonded composite repair of metallic aircraft structures

In this study, the distribution of the thermal residual stresses due to the adhesive curing in bonded composite repair is analysed using the finite element method. The computation of these stresses comprises all components of the structures: cracked plate, composite patch and adhesive layer. In addition, the influence of these residual stresses on the repair performance is highlighted by analysing their effect on the stress intensity factor at the crack tip. The obtained results show that the normal thermal stresses in the plate and the patch are important and the shear stresses are less significant. The level of the adhesive thermal stresses is relatively high. The presence of the thermal stresses increases the stress intensity factor at the crack tip, what reduce the repair performance.     

Integrating Blockchain Technology into Healthcare Through an Intelligent Computing Technique

The blockchain technology plays a significant role in the present era of information technology. In the last few years, this technology has been used effectively in several domains. It has already made significant differences in human life, as well as is intended to have noticeable impact in many other domains in the forthcoming years. The rapid growth in blockchain technology has created numerous new possibilities for use, especially for healthcare applications. The digital healthcare services require highly effective security methodologies that can integrate data security with the available management strategies. To test and understand this goal of security management in Saudi Arabian perspective, the authors performed a numerical analysis and simulation through a multi criteria decision making approach in this study. The authors adopted the fuzzy Analytical Hierarchy Process (AHP) for evaluating the effectiveness and then applied the fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) technique to simulate the validation of results. For eliciting highly corroborative and conclusive results, the study referred to a real time project of diabetes patients’ management application of Kingdom of Saudi Arabia (KSA). The results discussed in this paper are scientifically proven and validated through various analysis approaches. Hence the present study can be a credible basis for other similar endeavours being undertaken in the domain of blockchain research.     

Numerical/experimental investigations on reducing drag penalty of passive vortex generators on a NACA 4415 airfoil

A study emphasizing the effects of passive vortex generators (VGs) on aerodynamic characteristics of a NACA 4415 airfoil is presented. Both experimental and numerical works have been carried out on an array of VGs attached to a NACA 4415 airfoil. Lift and drag measurements are made at various angles of attack by using three‐axis component balance system. On the numerical side, Reynolds‐averaged Navier‐Stokes (RANS) equations have been solved with ANSYS FLUENT 14.5 commercial code with fully structured mesh and three turbulence models (realizable k‐ε, k‐ω shear stress transport [SST] and the Spalart‐Allmaras model) at Reynolds number Re = 2 × 10⁵. Parametric studies have been conducted to find out optimal configurations with respect to span‐wise separation distance between VGs, along with their location along the chord. A very good agreement has been obtained between experimental and computational results indicating that this optimized configuration is robust for the considered parameters. It turns out that increasing the span‐wise separation length increases the aerodynamic performances (lift‐to‐drag ratio) at low attack angles for which low parasitic drag is achieved but conversely degrades it at higher ones. For the stream‐wise location along the chord, upstream position of VGs degrades the lift‐to‐drag ratio at low attack angles and conversely improves it at higher ones.     

Failure Analysis of Brazed Joints—A Case Study

Journal of Failure Analysis and Prevention - Heat exchangers presented water leaking at brazed joints. The first was exposed to water–salt solution, and both interfacial and crevice corrosion...     

Statistical study of the crushing of limestone grains under shearing

Bulletin of Engineering Geology and the Environment - The behavior of granular materials subjected to shear loading is often very complex to be correctly characterized. Loads on a discrete medium...     

Queue-aware scheduling in full-duplex wireless networks

Wireless Networks - Contemporary progress in telecommunication technologies have made full-duplex wireless communications feasible. The latter promise to double the capacity of wireless networks by...     

Fractal-fractional neuro-adaptive method for system identification

Engineering with Computers - Neuronal networks are used in different fields of science and technology due to their capacity to approximate nonlinear functions through the synaptic weights...     

Improvement of the heat transfer quality by air cooling of three-heated obstacles in a horizontal channel using the lattice Boltzmann method

This study focuses on the cooling of three heated obstacles with different heights mounted on the bottom of the channel wall using different aspects that influence the enhancement of the heat exchange, as is known in the concept of cooling electronic devices. The lattice Boltzmann method associated with multiple relaxation times (LBM-MRT) was adopted to simulate the physical configurations of the studied system. In this context, the D2Q9 and D2Q5 models are applied to describe the fluid flow behavior and conjugate heat transfer, respectively. The evaluation of heat exchange between the cold fluid and three-heated obstacles has been accurately analyzed under the effect of several parameters such as Reynolds number, obstacle spacing, and thermal conductivity ratio. In addition, the setting of two and three fluids flow inlets were also studied. The results are presented in terms of streamlines, isotherms, and local Nusselt curves. The heat transfer increases with increasing solid-fluid thermal conductivity. It is also more pronounced for large Reynolds numbers. Moreover, the heat transfer significantly enhances for the second and third obstacles when obstacle spacing increases. The improvement of the heat transfer is performed by the implementation of several jet flows in the studied system.     

Implementation of Advanced Tunnel Field Effect Transistor (DP-TFET) for High Power Switching Applications

Silicon - As the technology advances to the nanoscale, advanced Tunnel Field-Effect Transistors are very prominent as a part of integrated circuits in the present trend. Advanced Tunnel FET devices...     

Heat and mass transfer influence on potential variation in a PEMFC membrane

Water transport in the membrane of a PEM fuel cell is provided essentially by a convective force, resulting from a pressure gradient, an osmotic force, due to a concentration gradient and an electric force caused by the protons migration from the anode to the cathode. Through these three types of force the two-dimensional behavior of electric potential has been studied in this paper. The adopted model in this work is based on the assumption of single phase and multi-species flow, supposed two-dimensional and transient in a porous medium. The species conservation equation is coupled with the energy equation through the diffusion coefficient of water and the heat convective flux. The set of governing equations in the form of convection–diffusion problem has been solved numerically using the finite volume method. The obtained results show the transient two-dimensional effect of heat and mass transfer on the voltage variation within the membrane.