Eigenvalue analysis for plain-woven fabric structure using shell element and one smoothing cell in the smoothed finite element method

An efficient four-node quadrilateral (Q4) shell element based on the first-order shear deformation theory of plate (FSDT) and the strain smoothing technique in finite elements (referred as SFEM) was proposed for eigenvalue analysis of plain-woven fabric structure. A one smoothing domain (or cell) integration scheme in SFEM was proposed to evaluate the nodal train fields of Q4 shell elements. The numerical result of eigenvalue analysis, which was in the case of free vibration analysis, approximated to that one implemented in the finite element method (FEM) but gave a higher efficiency in computation in terms of central processing unit (CPU) time and numerical implementation.The authors wish to express their acknowledgment to FCT funding from FCT – Foundation for Science and Technology within the scope of the project “PEST UID/CTM/00264; POCI-01-0145-FEDER 007136

Buckling analysis of plain-woven fabric structure using shell element and a one cell-based integration scheme in smoothed finite element method

A one smoothing cell integration scheme in the strain smoothing technique in finite elements (referred as SFEM) was proposed to evaluate the nodal train fields of a four-node quadrilateral (Q4) shell element, which is based on the first-order shear deformation theory of plate (FSDT). A mixed interpolation of tensorial components (MITC) approaches for Q4 transverse shear strains also applied to eliminate a shear locking phenomenon that may occur when the thin plate/shell elements are geometrically distorted in curved geometries of fabric sheet. The numerical eigenvalues of buckling analysis of a plain-woven fabric sample, of which physical and mechanical parameters extracted from Kawabata evaluation system for fabrics (KES-FB), obtained a higher efficiency in numerical computation and approximated to Q4 shell element implemented in the finite element method (FEM).The authors wish to express their acknowledgment to FCT funding from FCT – Foundation for Science and Technology within the scope of the project “PEST UID/CTM/00264; POCI-01-0145-FEDER 007136”

Common-aperture sub-6 GHz and millimeter-wave 5G antenna system

The realization of a common-aperture (or shared-aperture) 5G antenna system is proposed for compact and integrated wireless devices. As a combination of a dipole and tapered slots, an integrated antenna design, which operates at multi-bands, i.e. sub-6 GHz at 3.6 GHz and mm-wave at 28 GHz, is validated. The antenna design procedure starts with a dipole operating at 3.6 GHz, which is fed by a modified balun consisting of a tapered slot and a microstrip line. Here, the tapered slot has a dual feature, i.e., it is used to excite the dipole at 3.6 GHz and works as a tapered slot antenna at 28 GHz. Only a single feeder is optimized and used for both structures making the design unique and provides an extremely large frequency ratio. Moreover, the dipole's arms are utilized as an antenna footprint for two tapered slot mm-wave arrays, making the dipole dual-functional. The tapered slot antenna and the mm-wave arrays are optimized in a way that the main beams point at different directions. By this configuration, the design is able to cover an angle of 120° of space in θ-direction. As a proof of concept, a prototype is fabricated on Rogers RO-5880 with an overall size of 75 × 25 × 0.254 mm³. The simulated and measured results confirm the validity of the proposed concept.Muhammad Ikram, Nghia Nguyen-Trong and Amin M. Abbos

Realization of a tapered slot array as both decoupling and radiating structure for 4G/5G wireless devices

As a combination of microwave Multiple-Input Multiple-Output (MIMO) antenna system and mm-wave antenna array, an integrated design is proposed to provide multi-band, high port isolation, and high gain antenna solution for 4G/5G wireless devices. In this work, an array of tapered slots is used as a decoupling structure at microwave frequency and as an antenna array at mm-wave frequency. The proposed geometry consists of a dual-band monopole MIMO antenna system operating at 4G (2.6 GHz) and 5G (3.5 GHz) sub-6 GHz bands. The wideband port isolation of more than 25 dB is achieved by introducing a tapered slot array structure. One of the key design features is the utilization of these slots as an antenna array with a peak realized gain of 15 dBi at 28 GHz, making this array dual-functional, thus more feasible for compact 4G/5G handheld devices. The proposed design is printed on an RO-5880 substrate with an overall size of 70 mm × 50 mm × 0.51 mm. The measured -10-dB impedance matching bandwidth covers two sub-6 GHz bands (from 2.45 GHz to 2.85 GHz and from 3.18 GHz to 3.68 GHz), and the wide mm-wave band from 25 GHz to 30 GHz.Muhammad Ikram, Nghia Nguyen-Trong, and Amin M. Abbos

Transmission-line model of nonuniform leaky-wave antennas

Nonuniform leaky-wave antennas (LWAs) are analyzed and synthesized using a lossy transmission line model. The analysis is based on a general waveguide circuit theory. Compared to the classical approach, the model yields a higher accuracy in the computation of both aperture field distribution and radiation patterns. The proposed analysis is also able to provide scattering parameters of the whole structure in a fraction of a second, which is valuable for antenna optimization. Based on the analysis, a general method for far-field pattern synthesis utilizing global optimization is presented. As an application demonstration, the half-mode substrate-integrated waveguide (HMSIW), or half-width microstrip line, has been selected as basis structure for the LWA designs. Two antennas have been optimized targeting different specifications, i.e., a low-sidelobe level and a wide null in the radiation pattern. Experimental results are provided for these selected examples of nonuniform LWAs, which ultimately validate the proposed technique as an improvement over the classical approach.Nghia Nguyen-Trong, Leonard Hall, Christophe Fumeau

A comprehensive study in efficacy of Vietnamese herbal extracts on whiteleg shrimp (<em>Penaeus vannamei</em>) against <em>Vibrio parahaemolyticus</em> causing acute hepatopancreatic necrosis disease (AHPND)

Traditional Vietnamese herbal species were examined for their antimicrobial activity and disease resistance in whiteleg shrimp. In-vitro screening, the extracts of ten herbs were conducted to test the inhibition ability against Vibrio parahaemolyticus, causing acute hepatopancreatic necrosis disease. The results showed that five out of ten herbal species, including Pithecellobium dulce, Melaleuca leucadendron, Eucalyptus globulus, Mimosa pirga, and Hibiscus sabdariffa displayed potent antibacterial activity. Besides, three types of extracts of H. sabdariffa, E. globulus, and M. pirga were coated to the pellet feed at a concentration of 1%. After 30 days of feeding, the whiteleg shrimp (Penaeus vannamei) were challenged by V. parahaemolyticus through immersion. The growth performance (such as growth rate in length and weight, survival rate), hematological parameters of total hemocytes (THC), hyaline hemocytes (HC), and granulocytes (GC), and hepatopancreas recovery under the treatments with herbal extracts of the whiteleg shrimp were significantly enhanced as compared with the control (without herbal extract). The mortality and the bacterial density in the hepatopancreas of shrimp decreased. Specifically, the mortality of shrimp in the treatment supplemented with the methanol extract of H. sabdariffa was the lowest, followed by M. pirga and E. globulus. The experimental results also indicated that H. sabdariffa, E. globulus, and M. pirga could improve immune parameters and disease resistance; therefore, they should be employed in sustainable shrimp, practical farming

Tuning-Range Extension Strategies for Varactor-Based Frequency-Reconfigurable Antennas

OnlinePublTuning range extension strategies for varactor-based frequency-reconfigurable planar patch antennas are presented. The three tuning range optimization methods described in the paper include cooptimization of antenna dimensions and varactor properties, exploitation of multiple radiation modes, and reduction of parasitic capacitance. The first two strategies are emphasized by briefly reviewing two previously reported wide tuning range frequency-agile planar antennas. Importantly, the influence of parasitic capacitance on reducing the tuning range of the varactor-based frequency-reconfigurable antennas is then demonstrated by examining two antennas. The three tuning range extension methods are then combined to further expand the frequency tuning range of a reported frequency-reconfigurable antenna. The antenna has been re-designed, fabricated and experimentally characterized to demonstrate enhanced performance, which validates the proposed techniques, and their simultaneous application to reconfigurable antenna designs.Quoc Hung Dang, Nghia Nguyen-Trong, Christophe Fumeaux, Shengjian Jammy Che

Sub-6 GHz and mm-Wave 5G Vehicle-to-Everything (5G-V2X) MIMO Antenna Array

A multi-beam and multi-polarized Multiple-Input Multiple-Output (MIMO) antenna system, which operates at Sub-6 GHz and mm-wave frequency bands is realized for 5G Vehicle-to-Everything (5GV2X) application. Since the vehicle needs to communicate in different scenarios with the others, e.g. vehicles, passengers, control units, and mobile networks, in the surrounding area, an antenna with 360° coverage area is required. In this paper, an eight-element MIMO antenna is designed and implemented for this purpose. Four elements are distributed evenly in a circular substrate placed in the azimuth plane. Meanwhile, the other four elements are printed on two orthogonal substrates which are fixed perpendicularly to the circular substrate. Each radiating component is a tapered slot antenna integrated with a dipole to operate at both microwave and mm-wave bands. The simulated and measured results demonstrate capability of the proposed design in covering the whole surrounding area (360° coverage in azimuth plane). The antenna achieves a realized gain of more than 9 dBi at the mm-wave range and 4 dBi at the microwave range.Muhammad Ikram, Kamel S. Sultan, Amin M. Abbosh, Nghia Nguyen-Tron

Identification of apple fruit-skin constitutive laws by full-field methods using uniaxial tensile loading

The protective and preservative role of apple skin in maintaining the integrity of the fruit is well-known, with its mechanical behaviour playing a pivotal role in determining fruit storage capacity. This study employs a combination of experimental and numerical methodologies, specifically utilising the digital image correlation (DIC) technique. A specially devised inverse strategy is applied to evaluate the mechanical behaviour of apple skin under uniaxial tensile loading. Three apple cultivars were tested in this work: Malus domestica Starking Delicious, Malus pumila Rennet, and Malus domestica Golden Delicious. Stress–strain curves were reconstructed, revealing distinct variations in the mechanical responses among these cultivars. Yeoh’s hyperelastic model was fitted to the experimental data to identify the coefficients capable of reproducing the non-linear deformation. The results suggest that apple skin varies significantly in composition and structure among the tested cultivars, as evidenced by differences in elastic properties and non-linear behaviour. These differences can significantly affect how fruit is handled, stored, and transported. Thus, the insights resulting from this research enable the development of mathematical models based on the mechanical behaviour of apple tissue, constituting important data for improvements in the economics of the agri-food industry.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT—MCTES) for the conceded financial support through the reference grant EXPL/EMEAPL/0587/2021. The second author also acknowledges FCT for his grant ref. BI/UTAD/22/2022. The third author also acknowledges FCT for its financial support via the projects UIDB/00667/2020 and UIDP/00667/2020 (UNIDEMI)