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This work aims to make a unique polymer to be used as a conductive and flexible chip antenna. Its properties are robustness, rigidity, stretchability, and good conduction. The fabricated composite is composed of two copolymers, Polydimethylsiloxane (PDMS) and Polyethylenimine (PEI), assembled with nano metals (Copper, Silver), and graphene nanoparticles as a matrix. Nano metals fill out the inter-layer space, and polymer voids reinforce the cross linker. Graphene/metal nanoparticles help make chelating complexes using metallic bonds, enhancing the polymer’s conductivity from 1.87 × 10-4 to 5.64 ×10-6 σ Scm-1. The conductivity, self-healing, and surface morphology of fabricated composite are analyzed using different spectroscopic techniques, such as electrochemical impedance (EIS), Scanning Electronic Microscopy (SEM), Transition Electronic Microscopy (TEM), Infrared spectroscopy (IR), UV-Visible spectroscopy (UV), and a particle size analyzer.

Today, Wearable devices have been getting more attention in all life fields. Due to their unique characteristics like easier carriers, flexibility, durability, and biodegradable materials furthermore low-cost fabrication. in this...

Every year hundreds of serious accidents and catastrophic are accompanied by mining sector services as disaster, flooding, and demolition. To reduce the severity of the results such as high death numbers, lost communication inner and out mining, we have to find an easy way to improve communication means during that problems. In this paper, we reach out to fabricate durable, flexible, and wearable chaps, in addition to an easier carrier with highly efficient receiving and sending a signal at 2.4 GHz broad wide band. By doping a bunch of unique conductive metals (silver, copper, and gallium indium alloy) assembled on Graphene, its integration inside Polydimethylsiloxane to be future applicable antenna. Furthermore, we studied the physical and electric properties of a composite including Electrochemical Impedance properties (EIS), cyclic voltammetry (CV), and its thermal stability chip (DSC), as well as, using Transmission electron microscopy (TEM), and, scanning electron microscopy (SEM) techniques to clarify the surface morphology of fabricated materials. In addition to various measurements had been carried out such as Ultraviolet-visible, inductively coupled plasma (ICP) spectroscopy, and Energy-dispersive X-ray spectroscopy (EDX) to reinforce and elucidate the solid-state of ions inside fabricated Antenna. On the other hand, throughout stress-strain for the stretchability of fabricated is expanded to 30% of its original length, in addition to thermal stability reached to 485°C compared to pure PDMS substrate, with enhancing electric conductivity of composite ship.

Dielectric heating is a promising process for the uniform sterilization of food products as well as for the drying of products. However, radio frequency heating of wood-based materials (a highly anisotropic material with temperature, moisture and structural orientation dependent properties) does not seem to be elucidated in the literature. It is within this framework that this study is carried out and concerns the modeling of anisotropic dielectric heating by radio frequency (RF) and its application to the thawing of frozen wood. The nonlinear heat conduction problem involving phase changes is formulated in terms of volume enthalpy. For the numerical resolution of the thermal conduction equation, the finite element method is considered. Thermophysical and dielectric properties are expressed as a function of temperature, moisture content (MC), and structural orientation. The numerical approach is further validated by a combination of the analytical, numerical and experimental analyses. Finally, the effect of RF on the thawing of the Douglas-fir (Pseudotsuga menziesii) and the white oak (Quercus alba), which are two North American wood species, was studied based on an initial temperature of − 20 °C and a frequency of 50 MHz. In this regard, two MC of 65% and 90% are considered. For the two species of the studied wood, it is observed that the RF induce a uniform temperature profile.

In the veneer and plywood industry, the softening of a log, for better cutting (or unrolling), is generally done by immersing it in hot water (at a constant temperature). Accurate estimation of the heating time to reach a target temperature, at a given location in the log, is crucial, especially when the log is frozen. It is within this framework that this work is inscribed and it concerns four Canadian wood species: trembling aspen (Populus tremuloides), white birch (Betula papyrifera), yellow birch (Betula alleghaniensis) and sugar maple (Acer saccharum). The thermo-physical properties of the wood species are dependent on moisture content (MC), specific gravity (SG) temperature (T) and the structural directions (L,R,T). The initial temperature is − 20 °C and the target temperature, in the center of the log, is 60 °C. For the modeling of thermal conduction in the wood, the new approach 3D hybrid finite element enthalpy was used.

The aim of this work is to study the mechanical behavior of a hybrid composite based on polyester thermoset matrix reinforced by a mixture of Luffa (LF) and Glass (GF) fibers. The whole volume fraction of the fibers was limited to 20 vol% in which the LF fraction was varied from 5 vol% to 20 vol%. Composites plates were prepared using the resin transfer molding (RTM) method. The morphology was studied by scanning electron microscopy (SEM), and the mechanical properties of the composites were characterized using tensile, three points’ flexural tests and hardness. Obtained results have shown that the mechanical properties of the hybrid composites were superior to those of polyester/LF composite. The mechanical properties depend on the GF fraction and on the organization of GF and LF sheets in the composite. The analytical modeling of tensile properties showed that the mechanical behavior of these hybrid composites is better described by the model of Hirsch with an adjustable value between 0.37 and 0.55. In addition, the water absorption behavior of these hybrid composites was also investigated during 200 h.

In this work, the preparation and the physical evaluation of a series of miscible 0.2 M solutions in 50/50 volume ratios were addressed. A total of five solutions comprised of plain electrolyte/graphene, plain electrolyte/graphene-ethylene Glycol, plain electrolyte/graphene-poly-ethylene glycol, plain electrolyte/graphene-glycerol, and plain electrolyte/Graphene–Polyethylenimine. were assembled with Ag, and copper nanoparticles. The physical properties were studied by electrochemical impedance spectroscopy, solution conductivity calculations, and viscosity and flexibility measurements, particle size distribution analyses. Surface morphology characterizations were done by transmission electron microscopy. A comparative approach of the physical properties between the five solutions serves as a guide to select the most appropriate fluid applicable to the upcoming device.

This paper deals with the numerical study of the axial and radial forces, the stresses, the strains, and the vibrations induced by a liquid flow through a high pressure multistage centrifugal pump. This is to improve its performances account for the material of the shaft and the impellers. Indeed, a model of a 4-stage centrifugal pump is developed from a design point. The continuity and Navier-Stokes equations are used for the liquid flow through the pump. Furthermore, the equations of stresses, strains and vibrations are applied for the shaft and the impellers. The obtained system of equations is solved by means of ANSYS including the CFX, the static structural analysis and the harmonic response to determinate the fields of velocity and pressure, the axial and radial forces, the stress, the strain, and the amplitudes and the frequencies of vibrations on the pump shaft. In addition, numerical simulations are accomplished to analyze the shaft behavior in terms of the axial and radial forces, the stresses, the strains and the vibrations induced by liquid flow. The outlet blade height, the flow rate, the number of the stages, the diffuser return vanes and the diffuser in the last pump stage are used as parameters for these simulations. Good trends are achieved comparing the obtained results with these found in the literature and these calculated using the classical equations of stresses and strains.

Our work aims to make a unique polymer to be used as a conductive and flexible chip antenna. Its properties are robustness, rigidity, stretchability, and good conduction. The fabricated composite is composed of two copolymers, Polydimethylsiloxane (PDMS) and Polyethylenimine (PEI), assembled with nano metals (Copper, Silver ), and graphene nanoparticles as a matrix. Nano metals fill out the inter-layer space, and polymer voids reinforce the cross linker. Graphene/metal nanoparticles help make chelating complexes using metallic bonds, enhancing the polymer’s conductivity from 1.87 × 10− 4 to 5.64 ×10− 6 σ Scm− 1. We analyze the conductivity, self-healing, and surface morphology of fabricated composite using different spectroscopic techniques, such as electrochemical impedance (EIS), Scanning Electronic Microscopy ( SEM), Transition Electronic Microscopy (TEM), Infrared spectroscopy ( IR), UV-Visible spectroscopy (UV), and a particle size analyzer.

Purpose Reliability plays an important role in the execution of the maintenance improvement and the understanding of its concepts is essential to predict the type of maintenance according to the equipment state. Thereby, a computational tool was developed and programming with VBA in Excel® for reliability and failure analysis in a mining context. The paper aims to discuss these issues. Design/methodology/approach The developed approach use the modeling of stochastic processes, such as the renewal process, the non-homogeneous Poisson process and less conventional method as the Bayesian approach, by considering Jeffreys non-informative prior. The resolution gives the best associated model, the parameters estimation, the mean time between failure and the reliability estimate. This approach is validated with the reliability analysis of inter-failure times from underground rock bolters subsystems, over a two-year period. Findings Results show that Weibull and lognormal probability distribution fit to the most subsystems inter-failure times. The study revealed that the bolting head, the rock drill, the screen handler, the electric/electronic system, the hydraulic system, the drilling feeder and the structural consume the most repair frequency. The hydraulic and electric/electronic subsystems represent the lowest reliability after 50 operation hours. Originality/value For the first time, this case study defines practical failures and reliability information for rock bolter subsystems based on real operation data. This paper is useful to the comparative evaluation of rock bolter by detecting the weakest elements and understanding failure patterns in the individual observation subsystems on the overall machine performance.

High-density polyethylene (HDPE) nanocomposites were prepared by a melting-compounding process with a polymethylsilsesquioxane (PMSQ) as nanofiller. In this process, the PMSQ nanoparticles were swollen in an organic solvent using a Ultra-Turrax system and sonication and blended with molten HDPE using a twin-screw extruder. This was followed by solvent removal. Nanocomposites with different PMSQ mass contents from 0 to 1% were prepared. The nanocomposites were characterized with Fourier transformed infrared, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy and by thermal conductivity. The mechanical and thermomechanical properties of the materials were studied. The HDPE–PMSQ nanocomposites presented a remarkable increase in the elastic modulus (E′) compared to the neat HDPE. The obtained mechanical and thermomechanical properties of HDPE–PMSQ nanocomposites were found to be related to the barrier effect of the PMSQ nanoparticles.

The anisotropic problem of thermal conduction in a solid is generally treated in a reference coordinate system, which adequately describes its thermal conductivity tensor (Cartesian, cylindrical or spherical). For this problem, numerical treatment is difficult, especially if the thermophysical properties are non-linear or if the anisotropic medium undergoes a phase change. In this paper, we propose an approach using a Cartesian reference system to treat the anisotropic thermal conduction of problems for which the solid medium is characterized by a set of tensors of thermal conductivity of different natures (Cartesian and/or cylindrical and/or spherical), with or without phase change. For this purpose, we the anisotropic thermal conductivity tensor, with respect to a cylindrical or spherical coordinate system, is transformed by an equivalent tensor into global Cartesian coordinates. The nonlinear heat conduction problem involving phase changes, such as wood freezing, is solved using hybrid three-dimensional volumetric specific enthalpy based on finite-element analysis. The proposed approach is validated with analytical testing for two anisotropic media and with two experimental tests related to the heating of frozen woods. As an application, we have numerically quantified, on the one hand, the minimum time required for the thaw and, on the other hand, the freezing of a log of wood, such as white pine, according to the length of its radius (7.5, 10, 15, 20 and 25 cm). The thermophysical properties are a function of temperature, moisture content and structural orientation.

Our work aims to make a unique polymer to be used as a conductive and flexible chip antenna. Its properties are robustness, rigidity, stretchability, and good conduction. The fabricated composite is composed of two copolymers, PDMS and PEI, assembled with nano metals (Cu, Ag), and graphene nanoparticles as a matrix. Nano metals fill out the inter-layer space, and polymer voids reinforce the crosslinker. Graphene/metal nanoparticles help make chelating complexes using metallic bonds, enhancing the polymer’s conductivity from 1.87* 10− 4 to 5.64*10− 6 σ Scm− 1. We analyze the conductivity, self-healing, and surface morphology of fabricated composite using different spectroscopic techniques, such as electrochemical impedance (EIS), SEM, TEM, IR, UV, and a particle size analyzer.

There is a growing interest in unmanned aerial vehicles (UAVs) or drones in the aviation industry, both for military and civil applications. They are deployed for border surveillance, transport of medicines, data collection, and access to places which present a risk to humans to name a few. The materials used so far in the manufacture of UAVs are wood, plastic, aluminum, and carbon fibers. However, the level of performance of wood–plastic composites is expected to allow them to compete with both plastic and wood for the manufacture of UAVs’ small blades. In this regard, a family of biocomposites based on high-density polyethylene reinforced with 0%, 20%, 30%, 40%, and 50% (w/w) sawdust particles were developed and characterized. Their viscoelastic properties were determined by oscillatory shear tests and their viscoelastic behavior characterized by the Lodge integral model. A numerical study, using the nonlinear explicit finite element method, was further carried out to evaluate their suitability for shaping the blades of the drone by the thermoforming process. The forming pressure required by the numerical analysis was derived from the Van der Waals real gas equation of state. The influence of the airflow on the thickness of the thermoformed part, as well as the stress and energy required for the process were analyzed. The results indicate that the constituent equations have a significant impact on the final stress distribution in the thermoformed part; furthermore, the time and energy required for the forming process is related to the degree of reinforcement of the thermoplastic matrix.

In this work, the preparation and the physical evaluation of a series of miscible 0.2 M solutions in 50/50 volume ratios were addressed. A total of 5 solutions comprised of plain electrolyte/ graphene, plain electrolyte / graphene-ethylene Glycol, plain electrolyte/ graphene-poly-ethylene glycol, plain electrolyte/ graphene-glycerol, and plain electrolyte/ Graphene–Polyethylenimine. were assembled with Ag, and copper nanoparticles. The physical properties were studied by electrochemical impedance spectroscopy, solution conductivity calculations, and viscosity and flexibility measurements, particle size distribution analyses. Surface morphology characterizations were done by transmission electron microscopy. A comparative approach of the physical properties between the fives solutions serves as a guide to select the most appropriate fluid applicable to the upcoming device.

Simulation of airbag and membrane deployment under pressurized gas problems becomes more and more the focus of computational engineering, where finite element methods (FEMs) for structural mechanics and finite volume for computational fluid dynamics are dominant. New formulations have been developed for fluid structure interaction (FSI) applications using mesh free methods as smooth particle hydrodynamic (SPH) method. Up to these days very little has been done to compare different methods and assess which one would be more suitable. For small deformation, FEM Lagrangian formulation can solve structure interface and material boundary accurately, the main limitation of the formulation is high mesh distortion for large deformation and moving structure. One of the commonly used approaches to solve these problems is the arbitrary Lagrangian Eulerian (ALE) formulation which has been used with success in the simulation of FSI with large structure motion such as sloshing fuel tank in automotive industry and bird impact in aeronautic industry. For some applications, including bird impact and high velocity impact problems, engineers have switched from ALE to SPH method to reduce central processing unit (CPU) time and save memory allocation. Both ALE and SPH methods are described and compared here using similar mesh size, each ALE element is replaced by an SPH particle at the element center. From different simulation, it has been observed that for the SPH method to provide similar results as ALE or Lagrangian formulations, the SPH meshing needs to be finer than the ALE mesh. A contact algorithm is performed at the FSI for both SPH and ALE formulations. A simulation of airbag membrane deployment generated by high pressurized gas is performed.

Numerical modeling of the thermoforming process of polymeric sheets requires precise knowledge of the viscoelastic behavior under conjugate effect pressure and temperature. Using two different experiments, bubble inflation and dynamic mechanical testing on a high-density polyethylene (HDPE) nanocomposite reinforced with polymethylsilsesquioxane HDPE (PMSQ&ndash, HDPE) nanoparticles, material constants for Christensen&rsquo, s model were determined by the least squares optimization. The viscoelastic identification relative to the inflation test seemed to be the most appropriate for the numerical study of thermoforming of a thin PMSQ&ndash, HDPE part. For this purpose, the finite element method was considered.