A general electroelastic analysis of piezoelectric shells based on levy-type solution and eigenvalue-eigenvector method

Eigenvalue-Eigenvector approach as well as Levy type solution are used for electroelastic analysis of a doubly curved shell made of piezoelectric material based on a shear deformable model and piezoelasticity relations. The electroelastic governing equations are derived using virtual work principle. The solution is proposed for a Levy type boundary conditions with two simply-supported boundary conditions and two clamped ones. After derivation of the governing equations, a solution satisfying two simply supported boundary conditions is assumed to arrive a system of ordinary differential equations. The latest governing equations are solved using Eigenvalue-Eigenvector method to satisfy clamped-clamped boundary conditions. The distribution of displacements, rotations, electric potential, strain and stress is presented along the planar coordinate. Accuracy of the proposed solution is justified through comparison with results of previous papers

Finite Element Analysis of Novel Stiffened Angle Shear Connectors at Ambient and Elevated Temperature

This is a numerical study to investigate the behavior of novel stiffened angle shear connectors embedded in solid concrete slabs at both ambient and elevated temperatures. An advanced nonlinear finite element model is developed and validated with available experimental work by Nouri, K., et al. 2021. Additionally, parametric studies are performed to evaluate the variations in concrete strength and the connector’s dimensions. The results indicate that the ultimate strength of the stiffened angle shear connector drops by 92% in 1050 °C. Comparing studies show the strength of the stiffened shear connector at 700–850 °C is equivalent to the ordinary C-shaped shear connectors. The stiffened shear connector is more ductile at elevated temperatures as compared to ambient temperatures. The shear strength raised to 66% and 159.7% by increasing the height and width of the stiffened shear connector, respectively. Furthermore, the height of the stiffened shear connector is crucial to enhance the shear strength capacity as compared to the ordinary C-shaped shear connector.</p

Numerical investigation on the performance of a solar air heater using inclined impinging jets on absorber plate with parallel and crossing orientation of nozzles

This work investigates the performance enhancement of a solar air heater using inclined impinging jets on the heater surface. Two main sets of arrangements are considered for the jet nozzles including the parallel and crossing orientation of nozzles in consecutive rows. The RNG k − ɛ model is employed to simulate the turbulent flow in the channel. The influence of different geometrical and operational parameters such as jet diameter ratio (Dj/Dh), inclination angle (α,β), stream wise pitch ratio (L/Dh), span wise pitch ratio (S/Dh), Re number and velocity ratio (Vr) on the hydraulic and thermal behavior of jet solar air heater was studied. Results showed that the proposed jet solar air heater improved the Nu number and thermohydraulic performance parameter compared to the conventional unimproved solar air heater. For the studied range of parameters, up to 4.26 times higher Nu number was obtained using the jet impingement compared to the smooth duct solar air heater. Moreover, it was shown that the amount of velocity ratio (Vr) is a significant factor when comparing the parallel and crossing orientations. Additionally, results indicated that the increment of stream wise and span wise pitch led to the increment of the Nu number while having a minor effect on the friction factor. For example, the increment of L/dh from 0.3 to 0.6 leads to the reduction of f/fs of case 1 and case 4 by 6.5% and 1.09%, respectively Also, the increment of the jet diameter first raises the thermohydraulic performance parameter, and then with a further increment of diameter, the amount of thermohydraulic performance parameter decreases

Artificial neural network-based optimization of baffle geometries for maximized heat transfer efficiency in microchannel heat sinks

Microchannel heat sinks (MCHSs) are widely utilized in various industries, including electronics, power systems, and aerospace, to dissipate heat generated by high-power components effectively. The efficient cooling of these devices is crucial for maintaining their optimal performance, reliability, and longevity. This research aimed to augment the overall efficiency of the MCHS by utilizing 25 baffles with varying geometric parameters. The aim was to identify the optimum geometry for these baffles using an Artificial Neural Network (ANN) model. The ANN model was applied to propose two optimal designs for the baffles, specifically targeting the maximum Nusselt number and overall performance of the MCHS. It was noticed that the vertical pitch of the baffles ''d'' had the most substantial influence on the device's behavior among the investigated geometric parameters. The higher value of ''d'' allowed the fluid to spread over the entire space of the heat sink rather than being confined to a specific area. This spreading effect enabled the fluid to contact all the baffles and channel walls, facilitating efficient heat transfer. The applied ANN model with R2 values of about 0.98 and lower values of MAE and RMSE successfully fitted the data. The findings of this study demonstrated that applying the specified input variables (horizontal pitch of 8.496 mm, vertical pitch of 5 mm, and attack angle of 210. 560°), as defined in the optimal overall design, in manufacturing of the baffles resulted in a remarkable enhancement of about 46% in the overall performance of the MCHS in comparison with the design proposed in the reference paper. The heat transfer improvement of the MCHS with baffles were due to the vortices in the baffles bring about chaotic advection and could greatly enhance the convective fluid mixing

Improving efficiency and optimizing heat transfer in a novel tesla valve through multi-layer perceptron models

Over the past few years, the distinctive design and versatile applications of Tesla valves have captured considerable interest across diverse industries. In contrast to conventional check valves, Tesla valves employ interconnected channels, establishing a highly efficient and reliable fluid flow control mechanism. This research delves into an investigation of the optimum geometric parameters that significantly influence the performance of a novel Tesla valve. The study focuses on three key geometric characteristics: the valve angle (α), the distance between consecutive stages (D), and the distance between the divider wall in the second stage of each step group and the wall of the straight channel (H). The authors carried out a numerical study using computational fluid dynamics to acquire the results. Four multi-layer perceptron models, each with a structure of 3-2-2-1, were applied to predict the selected responses of Nusselt numbers in the forward (Nuf) and reverse (Nur) directions, as well as pressure drops in the forward (ΔPf) and reverse (ΔPr) directions. The findings revealed that among all the variables examined, the parameter H exerted the most substantial influence on all measured responses. It was concluded that by incorporating specific values of α = 34.065°, D = 9 mm, and H = 5.624 mm during the manufacturing process of the valve and altering the flow direction from forward to reverse, a remarkable improvement of approximately 271.7% in pressure diodicity was achieved

Application of Polyacrylic Hydrogel in Durability and Reduction of Environmental Impacts of Concrete through ANN

While adding superabsorbent polymer hydrogel particles to fresh concrete admixtures, they act as internal curing agents that absorb and then release large amounts of water and reduce self-desiccation and volumetric shrinkage of cement that finally result in hardened concrete with increased durability and strength. The entrainment of microscopic air bubbles in the concrete paste can substantially improve the resistance of concrete. When the volume and distribution of entrained air are adequately managed, the microstructure is protected from the pressure produced by freezing water. This study addresses the design and application of hydrogel nanoparticles as internal curing agents in concrete, as well as new findings on crucial hydrogel&ndash;ion interactions. When mixed into concrete, hydrogel particles produce their stored water to power the curing reaction, resulting in less volumetric shrinkage and cracking and thereby prolonging the service life of concrete. The mechanical and swelling performance qualities of the hydrogel are very sensitive to multivalent cations found naturally in concrete mixes, such as aluminum and calcium. The interactions between hydrogel nanoparticles and alkaline cementitious mixes are described in this study, while emphasizing how the chemical structure and shape of the hydrogel particles regulate swelling behavior and internal curing efficiency to eliminate voids in the admixture. Moreover, in this study, an artificial neural network (ANN) was utilized to precisely and quickly analyze the test results of the compressive strength and durability of concrete. The addition of multivalent cations reduced swelling capacity and changed swelling kinetics, resulting in fast deswelling behavior and the creation of a mechanically stiff shell in certain hydrogel compositions. Notably, when hydrogel particles were added to a mixture, they reduced shrinkage while encouraged the creation of particular inorganic phases within the void area formerly held by the swelled particle

Mechanical Characteristics and Self-Healing Soil-Cementitious Hydrogel Materials in Mine Backfill Using Hybridized ANFIS-SVM

The compressive strength, shrinkage, elasticity, and electrical resistivity of the cement-soil pastes (slag, fly ash) of self-healing of cementitious concrete have been studied while adding hydrogels with nano silica (NSi) in this research. Defining the hydraulic and mechanical properties of these materials requires improvement to motivate more uptake for new buildings. Initially, examining the impact of different synthesized hydrogels on cement-soil pastes showed that solid particles in the mixtures highly affected the absorption capacity of NSi, representing the importance of direct interactions between solid particles and hydrogels in a cementitious matrix. All test results were analyzed by use of a hybridized soft computing model such as the adaptive neuro fuzzy inference system (ANFIS) and support vector regression (SVR) for precise studying and the avoidance of few empirical tests or error percentages. Subsequently, the best RMSE of ANFIS is 0.6568 and the best RMSE of SVM is 1.2564; the RMSE of ANFIS-SVM (0.5643) in the test phase is also close to zero, showing a better performance in hypothesizing self-healing soil-cementitious hydrogel materials in mine backfill. The R2 value for ANFIS-SVM is 0.9547, proving that it is a proper model for predicting the study&rsquo;s goal. Electrical resistivity and compressive strength declined in the cement-soil pastes including hydrogels according to experimental outcomes; it was lowered by the increase of NSi concentration in the hydrogel. There was a decrement in the autogenous shrinkage of cement-soil pastes while adding hydrogel, depending on the NSi concentration in the hydrogels. The findings of this research are pivotal for the internal curing of cementitious materials to define the absorption of hydrogels