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In this paper, the shear behavior of ferro-cement hollow beams is investigated experimentally and analytically. Ten reinforced concrete beams with cross-sectional dimensions of 100 × 200 × 1300 mm and a clear span of 1000 mm were cast and tested until failure under a two-point loading system. Ferrocement beams in this research contained either an autoclaved aerated lightweight brick core (AAC) or an extruded foam core (EFC) and were reinforced with either expanded metal mesh (EMM) or welded wire mesh (WWM). The structural behavior of the studied beams, including first crack, deflection, ultimate load, crack pattern, failure mode, and ductility index, was investigated. The experimental data were used to validate finite element models created with the ABAQUS finite element program. It can be concluded that the optimum performance of ferrocement beams can be achieved using beams with a second layer of expanded steel mesh as additional reinforcement, which led to an increase in the ultimate load and maximum deflection by 12.9% and 22.8%, respectively. Furthermore, the Numerical results agreed with the experimental results, where the ratio between the NLFE ultimate loads and the experimental ultimate loads varies between 1.02 and 1.07, with an average ratio of 1.04. [ABSTRACT FROM AUTHOR]

This paper proposes an iteration-based algorithm for the optimum design of a high frequency transformer for solid-state transformer (SST) applications. This algorithm minimizes the total owning cost (TOC) of a distribution type solid-state transformer. The unique features of this algorithm compared with the available algorithms in the literature are as follows: it iterates eight design variables, four constraints are defined for selecting the valid designs, and it works with different core materials and AC test voltages. The algorithm uses various user-defined data inputs to calculate loss capitalization values for TOC calculation. In every iteration, TOC is estimated, and calculated values of design constraints are compared with their threshold limits. A case study is conducted on a high-frequency transformer (HFT) incorporated in 1000-kVA, 11-kV/415-V, Dyn11 three-phase wound core SST. This is to determine the optimum design parameters. In this case study, the algorithm was iterated with 2,100,000 design data inputs, generating 258,272 designs that satisfied all design constraints. The optimum design with minimum TOC is selected from the generated 258,272 designs. The optimum design is validated using finite element analysis in ANSYS software. Comparing the results of both analyses, the deviation is less than 5%. Hence, the algorithm's reliability is proved. [ABSTRACT FROM AUTHOR]

In this work, fringing effect is studied on planar transformers for various frequencies, air gap lengths, core materials and core geometries to aid engineers in choosing the best transformer design with least fringing losses. Using finite element modelling, fringing losses were analysed for four different core geometries, namely EE, EI, ER and ETD, with varying core widths to estimate a generalized fringing losses equation. Emerging core materials like amorphous and nanocrystalline materials were analysed in addition to the common ferrite material for the core of the transformer. Simulations were performed for frequencies ranging from 50 to 400 kHz and air gap lengths varying from 0.05 mm to 0.25 mm. Using curve fitting, an equation was developed to estimate fringing losses. Fringing losses of a planar transformer were found to be directly dependent on its frequency, magnetic flux density, air gap length and core width. The fundamental difference of the proposed equation from the traditional fringing losses formula is that fringing losses were found to be proportional to the square of the frequency instead of the first power of frequency. Fringing losses were also calculated with the traditional formula, to analyse the improvement obtained with the proposed finite element modelling-based equation. It was observed that the proposed formula gave fringing losses results with a minimal error of about 9% for a range of lower and higher frequencies, whereas the traditional formula accounted for about 45% error for higher frequencies and around 11% error for lower frequencies. [ABSTRACT FROM AUTHOR]

In order to achieve low refractive index detection in biomedical and material chemistry, a D-type microstructured optical fiber (MOF) sensor based on surface plasmon resonance (SPR) is proposed in this paper. The sensor uses gold nanofilm as sensing material between the core of the fiber and the plasma on the surface, and is coated at the open ring. Parametric analysis of the open-ring diameter, air hole diameter, and thickness of the gold nanofilm of the sensor was carried out by finite element method. The simulation results show that the sensor has a wavelength sensitivity of up to 10,900 nm/RIU, the refractive index range of 1.20–1.34, optimal resolution of 9.17 × 10−6 RIU, and a decent figure of merit (FOM) is 46.2 RIU−1. The proposed MOF-SPR sensor has high wavelength sensitivity and low resolution in a similar detection range compared to existing studies. The sensor is capable of detecting not only low refractive index substances, such as liquid medical oxygen with a refractive index of 1.22 and sevoflurane with a refractive index of 1.27, but also conventional refractive index substances such as water contamination with a refractive index near 1.33, providing a wide detection range. Therefore, the sensor is competitive in the detection of some low refractive index material detection fields. [ABSTRACT FROM AUTHOR]

Purpose: The constitutive parameters of viscoelastic materials, such as storage modulus and loss factor, usually have frequency-dependent characteristics. The combination of polymers with different reinforcement and fillers usually exhibits various mechanical characteristics, which makes the identification of the material properties of viscoelastic materials a challenging task. The present study proposes an inverse identification technique based on a neural network optimization (NNO) algorithm to characterize the frequency-dependent material properties of a viscoelastic material. Methods: To this end, a symmetric three-layered sandwich plate is considered having face layers of isotropic elastic material and a core layer of viscoelastic material. The experimental free vibration tests are performed using the impact hammer method to determine resonant frequencies and modal loss factors for various eigenmodes. In addition, a numerical model of the sandwich plate is developed to determine vibrational responses utilizing the finite element method. The vibration-based material parameter identification technique is implemented based on the NNO algorithm. The identified material parameters are then compared with the experimental dynamic mechanical analysis (DMA) test results. Furthermore, a numerical parametric study is performed considering the optimized viscoelastic material properties to investigate the influence of various geometrical and structural factors on the free vibration response of the sandwich plate. Results: The identified results are in excellent agreement with the experimental DMA test results affirming the robustness of the proposed inverse technique. The parametric study not only investigates the effect of various structural and geometric parameters on the dynamic response of the sandwich plate but also verifies that the calibrated properties are both realistic and physically meaningful. Conclusions: The proposed algorithm is a useful and efficient tool for inverse identification of the constitutive properties, and this approach can be extended for the calibration of other parameters (constitutive or not) for a variety of viscoelastic materials in any field of application. This study is a critical step forward in understanding viscoelastic materials and their frequency-dependent behaviorur. [ABSTRACT FROM AUTHOR]

In this work, the response of a sandwich cylindrical shell with carbon nanotubes (CNTs)-stiffened faces is investigated under a general distributed static loading. The shell boundaries can exhibit any combination of feasible boundary conditions. Specifically, the faces are made of an isotropic material reinforced with CNTs, while the core is composed of an isotropic material. The faces are modeled as thin cylindrical shells following the Kirchhoff–Love assumptions. Additionally, the in-plane stresses in the core material are assumed to be negligible. The governing equations are derived using the principle of the stationary potential energy. The harmonic differential quadrature method is employed to solve the equations for the deformed components. Subsequently, the obtained results are compared with those from finite element analysis. The maximum discrepancies between the two methods amount to approximately 2%. Next, the effects of various parameters including CNTs incorporation and volume percentage, core flexibility, and the core-to-face thickness ratio on the stress and displacement of sandwich cylindrical shells are explored. Considering all types of boundary conditions and examining the impact of relevant parameters, this study asserts that it represents a comprehensive contribution to the field. The main findings have practical implications for engineers and designers working with cylindrical sandwich shells. Incorporating CNTs into the face sheets, with a V-shaped distribution along the thickness, can significantly alter stress and displacement characteristics. Increasing core thickness, the thickness-to-curvature ratio, the CNT volume percentage, and the Young modulus ratio of face sheets to core reduces transverse displacement at the core mid-surface. [ABSTRACT FROM AUTHOR]

A low confinement loss of hollow-core photonic crystal Fiber (HC-PCF) for liquid-/gas-sensing applications has been proposed. Various HC-PCF backgrounds such as silica, BK7 and Teflon glass with different core materials such as glycerol, benzene and toluene have been studied using a finite element method with perfectly matched layer-based COMSOL software. The performance of the proposed PCF is analyzed using different metrics such as confinement loss, effective area, numerical aperture, relative sensitivity and effective refractive index for different combinations to compare the effects of different backgrounds in HC-PCF. The proposed HC-PCF structure offers relative sensitivity of 91.96% and 1.74 × 10−14 dB/m of confinement loss using Teflon glass as the substrate for benzene. The proposed PCF can be used for liquid- and gas-sensing applications with its low confinement loss and high sensitivity. The proposed simple cladding structure is easy to fabricate and offers 26% improved relative sensitivity compared to existing PCFs in the literature. [ABSTRACT FROM AUTHOR]

This paper presents a novel point of view for the performance investigation and optimization of energy absorber devices, which is numerically introduced using the finite element method employing corrugated tubes. The numerical results show that structural or material softening leads to an optimal configuration at which the corrugated or circular tube achieves its peak performance. The performance and optimization parameters used in this study are absorbed crash energy and specific energy absorption. The force-displacement (f-d) diagram of the energy absorbers is divided into three parts for numerical investigation. The optimum point of each corrugated tube is observed when the values of energy absorption (EA) at different stages of the stroke (i.e., in the first, middle, and last portions of deformation) are almost equal or close to one another. Furthermore, the effect of material softening is discussed. The effects of cladding a ductile layer on f-d diagram, EA and deformation of thin-walled circular tubes are numerically investigated. Adding soft material layers oriented at 30° to 70° to the model can increase the performance of energy absorbers by approximately 10 % compared with the model that uses only the core material. [ABSTRACT FROM AUTHOR]

We propose two mid-infrared photonic crystal fibers with an elliptical As2S3 core and a dual-cladding structure with high birefringence and high nonlinearity. The cladding filling material is silica and the core material is As2S3. The full vector finite-element method is used to study the birefringence, and nonlinear coefficient of the structure in the 3–5 μm band. The Simulation results show that the birefringence of the two structures can reach a maximum of 0.2169, and the nonlinear coefficient can reach a maximum of 3763.42 W−1/km. From these characteristics, it is concluded that the proposed structure will be ideal for mid-infrared fiber sensing, precision optics and nonlinear optics. [ABSTRACT FROM AUTHOR]

A solid core photonic crystal fiber (PCF) is preferred to signify the work of circular-pattern PCF for chemical identifying motive. Finite element method is used to obtain several properties of PCF. Various computations are applied to numerically explore the use of PCF for sensing justifications at different wavelengths ranging between 1.4 and 1.65 μm. The solid core is filled with liquid glycerol (n = 1.4722), ethanol (n = 1.354), and toluene (n = 1.4968), and on applying various geometric parameters of the fiber, 65.16%, 61.65%, and 64.05% of sensitivity are observed respectively. Transmission of heavy data with high speed depends on effective mode area. For glycerol and toluene, the effective area is observed as 2.81 μm2 and 3.07 μm2 respectively. Perfectly matched layer is applied in outer most cladding to overcome reflection. Higher sensitivity is observed by this design operating at different wavelengths. Similarly, properties like confinement loss and effective area are also computed. Design containing core material such as glycerol, ethanol, and toluene has been compared by different properties. The core materials employed in this paper are used to analyze the potential of sensors. This PCF can be used in diverse application of bio sensing or sensing related areas. [ABSTRACT FROM AUTHOR]

In this paper two crucial variables, namely type of winding material and number of core steps, have been proposed to minimize the purchase cost, total mass, loss, and life time cost of the transformer. In order to make cost-effective and energy-efficient transformer design, the proposed variables are used in conjunction with six primary variables for deciding the most appropriate conductor and core step size. Further, the efficacy of the proposed methodology, in terms of cost savings, material savings, and loss reduction, is tested on 1500-kVA transformer using covariance matrix adaptation evolution strategy (CMA-ES) and self-adaptive differential evolution (SaDE). It is revealed that the proposed crucial variables with CMA-ES provide better design option than the SaDE and knowledge-based systems. Also, faster convergence and consistency have been established with CMA-ES than SaDE through the statistical analysis. Core losses are calculated using proposed methodology, and employing analytical equations is validated using 3D finite element method. [ABSTRACT FROM AUTHOR]

A novel elliptical core photonic crystal fiber (EC-PCF) is proposed with a trapezoidal outer cladding and three different inner claddings in this paper. The material of proposed fiber is a combination of the background material of silica and core material of As2S3. Using the finite element method (FEM) with the boundary condition of the circular perfectly matched layer (C-PML), the effect of different inner cladding structures (ellipse plus circles, strip circles, and hexagonal circles) on birefringence and nonlinear coefficients is analyzed. Simulation results show that the inner cladding has revealed a high birefringence in the order of 3.3136 × 10-1 with strip circles, while the nonlinear coefficients for x- and y-polarization is 2.81 × 104 w−1/km and 2.09 × 104 w−1/km at an operation wavelength of 1.55 μm, respectively. The demonstration of our proposed fiber can supply a feasible method for optical communication and supercontinuum generation. [ABSTRACT FROM AUTHOR]