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Recent advancements in wireless technology have prompted the development of wearable antennas, particularly for Wireless Body Area Networks (WBANs) used in sports, military activities, healthcare, and identification systems. Unlike traditional antennas, wearable antennas operate very close to the curved human body. Consequently, their performance metrics such as reflection coefficient, bandwidth, radiation characteristics, efficiency, gain, directivity, and Specific Absorption Rate (SAR) can be significantly affected by interactions with human body tissues. To address these challenges, periodic structures are integrated into wearable antenna designs to mitigate the effects of coupling and absorption by the human body. To date, a limited number of works have surveyed, compared, and categorized the proposed wearable antenna designs integrated with periodic structure based on their operating frequency bands and their interactions with the human body. To this end, this paper contributes to the literature by detailing the selection of materials, highlighting the limitations of wearable antennas, characterizing the periodic structures, elaborate on dielectric properties data of human body models, discussing the influence of periodic structures on antenna performance and their significance in isolating them from the human body. Furthermore, this study provides an in-depth review of 81 papers evaluating the performance of antennas integrated with periodic structures, both in free space and on the human body, across single-band, dual-band, and triple-band designs. The selected papers were chosen based on their publication in reputable journals, the quality of their research, and the comprehensiveness of their data analysis. In addition, it provides a summary of several common flexible materials used in wearable antennas with their electrical properties as well as the dielectric properties of the human body for different frequencies. Moreover, it discusses the challenges and considerations involved in designing appropriate wearable antennas.

Abstract In this work, the concept of peer-to-peer energy sharing in wildlife communication systems is explored. In this context, wild animals can share energy wirelessly besides their data communications as they opportunistically come into range of each other. Our goal is to find a way to balance the energy among the nodes and minimize this energy loss. We propose a novel encounter-based energy-sharing scheme, called EBES, that utilizes single and multi-hop transmission to achieve energy balance, minimize energy losses, and maximize the lifetime of the wildlife communication system. EBES is based on a variety of parameters, including the amount of energy left in the system and the nodes’ encounter rate, and buffer sizes. In the simulation studies, we considered a wildlife communication network that is involved in data communication and applied EBES over the opportunistic routing protocols such as EBR, Spray&Wait, and Epidemic resulting in a network lifetime increase of 35% and improving the routing protocols performance. Additionally, we compared EBES with the other well-known energy balancing techniques that also contribute to data communication such as EA-Epidemic, EERPFAnt, and OE-OLSR and the results show the remaining energy was improved by 31%, 26%, and 15%, respectively.

Abstract Among different types of transformerless photovoltaic inverters, multi‐level inverters based on switched‐capacitors (SC) are the burning topic of recent decades due to their potential advantages, such as, single source requirement, voltage boosting capability, and high power density. However, for a seven level output voltage, a conventional SC based inverter architecture uses more than two units of SC, a large amount of power switches, which then lead to capacitor voltage balancing problems. This paper presents a seven‐level switched‐capacitor transformerless inverter (SCTI), which is structured with only two SC units, ten power switches, and a single DC source. The proposed SCTI ensures voltage boosting capability, self‐voltage balancing, and low power semiconductor losses. Apart from these, a modified sinusoidal pulse width modulation (MSPWM) is also proposed in this work, which guarantees better thermal performance and low inverter output voltage THD for the proposed SCTI. The proposed SCTI along with the MSPWM is simulated in MATLAB/Simulink and PLECS computer simulation environments. A reduced scale laboratory prototype is also built and tested to ensure the feasibility of the proposed SCTI.

The magnetic linked converter plays a significant role in the power electronics industry due to its merits of being flexible to control, the high efficiency of power transmission, the performance of galvanic isolation, etc. These features make magnetic linked converter a prominent candidate for an effective interface for renewable energy integration to the traditional power grid, more electric aircraft applications, electric vehicle charging implementation, etc. The traditional controller of the magnetic linked converter is the linear control method which cannot ensure smooth bidirectional power routing and a high level of decoupling especially for the electric vehicle charging application. In the worst-case scenario, the traditional controllers can be fully saturated and cause severe system-wide unbalancing issues. Recently, the magnetic linked converter technology with advanced control decisions has been adopted for the electric vehicle charging application. The magnetic linked converter technology for electric vehicle charging applications provides a higher degree of control flexibility to supply multiple loads simultaneously in terms of soft-switching ability, galvanic isolation, and high-density power transmission. With regard to the control methods, numerous advanced controls are developed and proposed for the magnetic linked converter to ensure robust voltage control, smooth bidirectional power routing control, and high degree of decoupling to avoid any control interactions up to date. There have been a few review studies on the converter topology, control, and power management for magnetic-linked power converters for future for renewable energy integration to the traditional power grid, more electric aircraft applications, and electric vehicle charging implementation in the literature. However, a detailed review of magnetic-linked power converter topologies, controls, and power management on these applications is still limited in terms of a variety of power electronic interfaces with appropriate controls and power management. Therefore, this paper presents a comprehensive review with a more specific assessment of the variety of magnetic-linked power electronic interfaces with controls and power management for the widespread emerging applications.

Clean and sustainable renewable energy sources (RESs) are increasingly becoming the better replacement for traditional fossil fuel-based electricity generation. RESs are typically connected with the utility grid through power electronic energy conversion systems. Power electronic energy conversion systems are becoming increasingly important for distribution networks, electric vehicles, or renewable energy applications. Magnetic links (MLs) play an important role as an isolating medium between the input-output stages of the converters in power electronic energy conversion systems. ML can also be used to increase fault-tolerant capability and enhance the power transfer reliability of the system. By increasing the frequency, the size of the ML can be reduced. However, some challenging technical issues with the ML operating with medium/high-frequency (HF) might affect the power converter performance. Several reviews have been published on the specific ML core materials for low-frequency applications. However, as the frequency used in the ML increases, there is an urgent need to investigate newer magnetic materials for use in such HFMLs, because, at medium/HF, the efficiency of MLs largely depends on the core losses that occurred due to the core materials. In this article, a comprehensive review has been carried out on the ML core materials for medium/HF applications from the historical development to the current status. The industrial production process of these materials from the raw phase to the production phase is presented. Electromagnetic and physical properties of the core materials are studied and addressed in the paper. Based on the properties, system requirements, and applications, a ranking has been proposed that can play an important role in selecting core materials for designing medium/HFMLs for power electronic energy conversion systems. A comparative analysis has also been carried out based on mathematical modeling and experimental core loss measurement techniques which can be used to predict the specific losses of the material. Finally, challenges to the design and implementation of medium/HFMLs for power converters are studied, and possible suggestions have been proposed to overcome the challenges to make the systems more efficient and reliable.

In this paper, we designed and implemented a multi-antenna configured secure millimeter-wave (mmWave) CP-less multi-user orthogonal chirp division multiplexing (OCDM) transceiver. The proposed simulated system emphasizes more applicable performance metrics for a typically assumed case of four users and a passive eavesdropper for audio data transmission. We introduce a four-dimensional hyperchaotic system-based encryption algorithm to enhance physical layer security (PLS). In addition, low-density parity check (LDPC), TURBO, ( $3, 2$ ) single parity check (SPC), and repeat and accumulate (RA) channel coding with Cholesky decomposition-based zero-forcing (CD-ZF) and minimum mean square error (MMSE) signal detection techniques for a better bit error rate (BER) were also implemented. The simulation results signify the effectiveness of the proposed system in terms of PLS enhancement with low correlation coefficients (14.62%, 7.61%, 13.61%, and 15.39% for users 1, 2, 3, and 4, respectively), an achievable secrecy rate with a low signal-to-interference and noise ratio (SINR) of the passive eavesdropper, an achievable out-of-band (OOB) power emission of 341 dB, an estimated average short-time Fourier transform (STFT) spectral power difference of 7.68 dB and estimated peak-to-average power ratios (PAPRs) ranging from 7 to 7.5 dB at a complementary cumulative distribution function (CCDF) of $1\times 10^{-3}$ for different ground transmitting channels. At an identical signal-to-noise ratio (SNR) of 17 dB, all four users achieved a bit error rate of $1\times 10^{-4}$ under RA channel coding, CD-ZF, and 16-QAM (quadrature amplitude modulation) digital modulation.

A highly bendable, and a low-profile Artificial Magnetic Conductor (AMC)-based antenna for wearable applications operating at 2.4 GHz is presented. The AMC is employed to ensure consistent antenna performance in both free space and on the body, with its safety limit complying with standards. The proposed AMC design incorporates a Jerusalem cross shape slot on its conventional patch, integrated with the antenna, resulting in overall dimensions of $60\times 60 \times 3$ mm3. The proposed low-profile AMC demonstrates superior performance under extreme bending, whether in free space or on the body, and offers a wide bandwidth, addressing the frequency detuning problem associated with deformation. In free space, the integrated design exhibited a gain of 7.61 dBi, a bandwidth of 27.13%, a front-to-back ratio (FBR) of 17.7 dBi, and an efficiency of 83.5%. When placed on the body, it resulted in a gain of 6.98 dBi, a bandwidth of 25.7%, an FBR of 18.2 dBi, and an efficiency of 70.1%. SAR analysis was conducted with different input power levels (100 mW, 500 mW, and 1000 mW) and demonstrated excellent results. The numerical and experimental results collectively suggest that the integrated design is a promising candidate for wearable applications.

This paper presents a novel wideband circularly polarized CPW-fed printed monopole antenna for CubeSat applications. An AMC reflector with $5\times 5$ -unit cells is used to increase antenna gain. The overall size of the antenna is $0.48\lambda _{0} \times 0.48\lambda _{0} \times 0.042\lambda _{0}$ at the operating frequency of 8-GHz. The proposed printed monopole antenna provides a wide impedance bandwidth and a wide 3-dB axial ratio bandwidth. When comparing our proposed antenna to all designs, it is evident that the proposed printed monopole antenna offers several advantages. Firstly, it exhibits higher gain and a wider 3-dB axial ratio bandwidth (ARBW) while maintaining a smaller physical size. More specifically, the measured results show a wide -10 dB impedance bandwidth of 97.5% (6.1–13.9 GHz), and a wide measured 3-dB axial ratio bandwidth of 98.75% (5.1–13 GHz) and total measured gain of 7.3-dBi at 8 GHz.

Opportunistic Networks (OppNets) are characterized by intermittently connected nodes with fluctuating performance. Their dynamic topology, caused by node movement, activation, and deactivation, often relies on controlled flooding for routing, leading to significant resource consumption and network congestion. To address this challenge, we propose the Adaptive Clustering-based Routing Protocol (ACRP). This ACRP protocol uses the common member-based adaptive dynamic clustering approach to produce optimal clusters, and the OppNet is converted into a TCP/IP network. This protocol adaptively creates dynamic clusters in order to facilitate the routing by converting the network from a disjointed to a connected network. This strategy creates a persistent connection between nodes, resulting in more effective routing and enhanced network performance. It should be noted that ACRP is scalable and applicable to a variety of applications and scenarios, including smart cities, disaster management, military networks, and distant places with inadequate infrastructure. Simulation findings demonstrate that the ACRP protocol outperforms alternative clustering approaches such as kRop, QoS-OLSR, LBC, and CBVRP. The analysis of the ACRP approach reveals that it can boost packet delivery by 28% and improve average end-to-end, throughput, hop count, and reachability metrics by 42%, 45%, 44%, and 80%, respectively.

Abstract Adversaries may target alerting alarms raised by PLCs (Programmable Logic Controllers) to prevent notifying operators of critical conditions, to hide faults, to disrupt operations, to cause damages to ICS (Industrial Control Systems) and surrounding environment, or to lead to financial loss. The paper focuses on exposing vulnerabilities of the ladder logic code that handles the alerting alarm messages and how to mitigate them. A real-time test bed of a PLC alarms code was developed and used to conduct several stealthy attack techniques to suppress or hinder alarms by exploiting code vulnerabilities. A novel ladder logic solution that consists of countermeasures against the introduced attacks was proposed, demonstrated, and tested. The countermeasure techniques, such as scan time and heartbeat techniques, were able to detect and prevent the code vulnerabilities and other abnormalities. The provided countermeasure techniques in this experiment could be applied to any PLC to enhance the validity and security of its PLC alarms code. Article Highlights Four stealthy attack models were introduced to exploit PLC alarms code. They were embedded to skip, delete, fake out, or delay alerting alarms. Real-time countermeasure solutions with different techniques were introduced: scan time code, heartbeat code, and physical plausibility check. They effectively detected and prevented the introduced attack models. PLC alarms Code general abnormalities was validated and detected using scan time techniques. A list of general best code practices for PLC alarms code was introduced to mitigate code vulnerabilities.

Application demand for faster data rates is driving the need for wider operating bandwidth of future 5G/6G communication systems which in turn poses stringent requirements on the design of suitable antennas. A candidate antenna that can support 5G/6G systems are reflectarrays (RAs) due to their numerous potentials, such as high gain, beam shaping, beam scanning, reconfigurability and multi-beam characteristics. However, reflectarrays are usually limited by their narrowband characteristics. Hence, this work examines the state of the art of wideband reflectarrays. Wideband reflectarrays are reviewed and categorized according to four wideband phase tuning mechanisms. The bandwidth is reviewed and compared both from a unit cell and reflectarray system perspective with emphasis on the gain-bandwidth performance. Different wideband unit cell geometries are covered and grouped by the wideband phase tuning approach. The effect of each wideband phase tuning approach on the gain-bandwidth RA performance is then analyzed by considering the operating frequency, the reflection phase range, the substrate structure and material, the aperture size, the aperture efficiency, the focal distance, the cross-polarization performance as well as the gain and side lobe levels. Finally, the phase tuning approaches are compared against each other, and guidelines are provided for designing reflectarrays with wide gain-bandwidth.

The accurate classification of landfill waste diversion plays a critical role in efficient waste management practices. Traditional approaches, such as visual inspection, weighing and volume measurement, and manual sorting, have been widely used but suffer from subjectivity, scalability, and labour requirements. In contrast, machine learning approaches, particularly Convolutional Neural Networks (CNN), have emerged as powerful deep learning models for waste detection and classification. This paper analyses VGG-16, InceptionResNetV2, DenseNet121, Inception V3, and MobileNetV2 models to classify real-life waste when trained on pristine and unadulterated materials, versus samples collected at a landfill site. When training on DiversionNet, the unadulterated material dataset with labels required for landfill modelling, classification accuracy was limited to 49.69% in the real environment. Using real-world samples in the newly formed RealWaste dataset showed that practical applications for deep learning in waste classification are possible, with Inception V3 reaching 89.19% classification accuracy on the full spectrum of labels required for accurate modelling.

In this paper, multi-antenna transceiver for zero-padded orthogonal frequency division multiplexing (OFDM) system is designed at mmWave by integrating full-duplex unmanned aerial vehicle (UAV) into the terrestrial cellular networks. Assuming that there exist no direct communication links between the ground base station (GBS) and the mobile users due to unexpected blockages from high storied buildings in urban area, the UAV applies decode-and-forward cooperative strategy on the received OFDM signals transmitted from GBS and re-transmits to the ground mobile users and passive eavesdropper. In this proposed system, intertwining logistic map (ILM)-cosine transform aided encryption algorithm combined with artificial noise enhancing physical layer security (PLS) is introduced. Also walsh-hadamard transform technique integrated with QR-decomposition based zero forcing (ZF) block diagonalization (QR-ZF-BD) precoding for multi-user interference reduction and non-iterative clipping and filtering technique for peak to average power ratio (PAPR) reduction are utilized. In addition, Low density parity check (LDPC) and repeat and accumulate (RA) channel coding with cholesky decomposition based ZF and minimum mean square error signal detection schemes for improved bit error rate (BER) are also introduced. Numerical results demonstrate the effectiveness of the proposed system in terms of PLS for color image transmission at high order digital modulation (16-PSK and 16-QAM). At the complementary cumulative distribution function of probability level 1-6%, the estimated PAPR is found to have value of 6 dB.The three users achieve BER $= 1\times {10}^{-4}$ at signal-to-noise ratio of 1.5 dB, 4 dB and 6 dB under RA channel coding and 16-QAM digital modulation.

Cube Satellites, aka CubeSats, are a class of nano satellites that have gained popularity recently, especially for those that consider CubeSats as an emerging alternative to conventional satellites for space programs. This is because they are cost-effective, and they can be built using commercial off-the-shelf components. Moreover, CubeSats can communicate with each other in space and ground stations to carry out many functions such as remote sensing (e.g., land imaging, education), space research, wide area measurements and deep space communications. Consequently, communications between CubeSats and ground stations is critical. Any antenna design for a CubeSat needs to meet size and weight restrictions while yielding good antenna radiation performance. To date, a limited number of works have surveyed, compared and categorised the proposed antenna designs for CubeSats based on their operating frequency bands. To this end, this paper contributes to the literature by focusing on different antenna types with different operating frequency bands that are proposed for CubeSat applications. This paper reviews 48 antenna designs, which include 18 patch antennas, 5 slot antennas, 4 dipole and monopole antennas, 3 reflector antennas, 3 reflectarray antennas, 5 helical antennas, 2 metasurface antennas and 3 millimeter and sub-millimeter wave antennas. The current CubeSat antenna design challenges and design techniques to address these challenges are discussed. In addition, we classify these antennas according to their operating frequency bands, e.g., VHF, UHF, L, S, C, X, Ku, K/Ka, W and mm/sub-mm wave bands and provide an extensive qualitative comparison in terms of their size, −10 dB bandwidths, gains, reflection coefficients, and deployability. The suitability of different antenna types for different applications as well as the future trends for CubeSat antennas are also presented.

Delay-tolerant networks (DTNs) are networks where there is no immediate connection between the source and the destination. Instead, nodes in these networks use a store–carry–forward method to route traffic. However, approaches that rely on flooding the network with unlimited copies of messages may not be effective if network resources are limited. On the other hand, quota-based approaches are more resource-efficient but can have low delivery rates and high delivery delays. This paper introduces the Enhanced Message Replication Technique (EMRT), which dynamically adjusts the number of message replicas based on a node’s ability to quickly disseminate the message. This decision is based on factors such as current connections, encounter history, buffer size history, time-to-live values, and energy. The EMRT is applied to three different quota-based protocols: Spray and Wait, Encounter-Based Routing (EBR), and the Destination-Based Routing Protocol (DBRP). The simulation results show that applying the EMRT to these protocols improves the delivery ratio, overhead ratio, and latency average. For example, when combined with Spray and Wait, EBR, and DBRP, the delivery probability is improved by 13%, 8%, and 10%, respectively, while the latency average is reduced by 51%, 14%, and 13%, respectively.

Free Space Optical (FSO) communication links are although extremely vulnerable to atmospheric adversities, multi-hop relay transmission can however, significantly improve the link performance and reliability. This paper proposes 120 Gbps DP-16 QAM modulated multi-hop serial FSO link with coherent reception for delivering medical consultation services in remote and isolated locations. Considering the current situation wherein pandemic of highly infectious nature, COVID-19 has affected millions of people globally; doctors can use the proposed high-speed architecture for “contact-less” supervision of quarantined patients and suspects through video conferencing. Each relay terminal uses an all-optical amplify-and-forward technique with Erbium-doped fiber amplifier (EDFA) and gain optimization as its core elements. As a possible last-mile application for delivering medical/health care services, the proposed link has been evaluated for reliability by exposing the link to varied atmospheric conditions. Our results reveal that at target BER of 10-5, the useful communication link range of proposed multi-hop link increments by 1.8 kms as compared to direct link that operates under similar channel conditions. Furthermore, compared to results from recent literature on high-speed FSO [30], the proposed link shows enhancement in link range by approximately 0.7 km. The analysis also reveals that as the number of relay nodes increases, the error performance of the link for different atmospheric conditions approaches a state of convergence.

Drones have become prevalent for the delivery of goods by many retail companies such as Amazon and Dominos. Amazon has an issued patent that describes how drones scan and collect data on their fly-overs while dropping off packages. In this context, we propose a path optimization algorithm for a drone multi-hop communications network that can carry and forward data in addition to its primary function of parcel deliveries. We argue that traditional Delay Tolerant Networking (DTN) based protocols may not be efficient for this purpose. Therefore, this paper proposes a new DTN-based algorithm that optimizes drone flight paths in conjunction with optimized routing to deliver both parcels and data in a power efficient way and within the shortest possible time. We propose a heuristic algorithm called Weighted Flight Path Planning (WFPP) that priorities the data packets in an exchange pool in order to create an optimized path for the drones. Our approach is to determine a weight for each packet based on the packet's remaining time to live, priority, size, and location of the packet's destination. When two drones meet each other, they exchange the high weighted packets. Simulation studies show that WFPP delivers up to 25% more packets compared with EBR, EPIDEMIC, and a similar path planning method. Also, WFPP reduces the data delivery delays by up to 66% while the overhead ratio is low.

In this article, a low profile circularly polarized (CP) antenna with wide 3-dB axial ratio beamwidth (ARBW) is presented. Two-pair of parallel slots are etched on a circular patch and manifested as magnetic dipoles (MDs). These narrow slots are arranged symmetrically about the axes, and one pair is orthogonal to another pair of slots. The philosophy of CP radiation across a wide angular range strongly depends on the spacing between the paired-dipoles, for example spacing of $0.22\lambda _{0}$ , two-orthogonal far-field radiated components become equal across a wide-angle. Moreover, this particular spacing between the paired-dipoles provides a symmetrical electric field distribution along the periphery of the patch, which ensures the broadside LHCP radiation with wide 3-dB ARBW of 228° and 214° at the plane of $\varphi = 0^{\circ }$ and $\varphi = 90^{\circ }$ , respectively. The measured results from the fabricated prototype exhibit good agreement with the simulated results. The antenna has impedance bandwidth (IBW) and CP bandwidth (CPBW) of 2.6% (64 MHz), and 0.9% (22 MHz), respectively. The broadside radiation holds antenna gain higher than 5 dBic across the entire CPBW.

Free-space optical (FSO) communication systems are being anticipated to offer promising alternatives to existing radio networks in delivering high-speed data access to end-users. Ease of installation, robust features, and cost-effective operation have been the hallmark of FSO systems, and these features will play an obvious role in deciding the ways in which futuristic smart communication models will operate. Despite these arrays of features, FSO links suffer severe performance degradation due to channel-induced impairments caused by atmospheric effects such as rain, haze, and fog. In this work, we have investigated and compared the performance of 40 Gbps FSO links for different channel conditions ranging from clear weather to severe attenuation by incorporating spatial and wavelength diversity as performance booster techniques. The use of an erbium-doped fiber amplifier (EDFA) with FSO links has also been proposed here. Using performance metrics like bit error rate (BER) and eye patterns, it has been found that the use of EDFA not only helps in compensating for the link losses but also aids in realizing an all-optical processing based last-mile access system. The proposed FSO system will be capable of bridging the existing backbone fiber networks with end-users with minimal changes to the existing hardware regime, thereby proving to be extremely cost-effective in sharp contrast to radio-frequency generations which require major infrastructure overhaul.

Conductive biomaterials have recently gained much attention, specifically owing to their application for electrical stimulation of electrically excitable cells. Herein, flexible, electrically conducting, robust fibers composed of both an alginate biopolymer and graphene components have been produced using a wet-spinning process. These nanocomposite fibers showed better mechanical, electrical, and electrochemical properties than did single fibers that were made solely from alginate. Furthermore, with the aim of evaluating the response of biological entities to these novel nanocomposite biofibers, in vitro studies were carried out using C2C12 myoblast cell lines. The obtained results from in vitro studies indicated that the developed electrically conducting biofibers are biocompatible to living cells. The developed hybrid conductive biofibers are likely to find applications as 3D scaffolding materials for tissue engineering applications.

Energy storage is a key requirement for the emerging wearable technologies. Recent progress in this direction includes the development of fiber based batteries and capacitors and even some examples of such fibers incorporated into prototype textiles. Herein we discuss the advantages of using the wet-spinning process to create nanostructured carbon based materials as wearable energy storage. The ability to control the physical, mechanical, electrical, and electrochemical properties of carbon nanotube based fibers holds great promise to develop smart polymeric structure as an energy storing materials including fibers and textiles. This is the first comprehensive review to discuss effect of nanostructured energy materials on the electrochemical properties of carbon nanotube based fibers which covers the various compositions, spinning and fabrication conditions on the performance of wearable energy storage.

Flexible wearable wireless devices have found practical uses as their cost has fallen and Internet of Things applications have gained further acceptance. These devices are gaining further use and acceptance in the consumer and wearable space for applications such as logistical tracking and maintaining sensor information, including temperature, humidity, and location. In such applications, antennas are exposed to bending and crumbling. Therefore, flexible substrate antennas for use with polymer-based flexible devices are an important area of research that needs to be addressed. In this study, the bending capabilities of flexible polymer substrate antennas for general IoT applications were practically analyzed by fabricating flexible antennas on Polyethylene Terephthalate (PET), Polytetrafluoroethylene (PTFE) Teflon, and Polyvinylchloride (PVC) substrates operating at 2.45, 4.45, and 7.25 GHz frequencies. The basic premise was to investigate the flexibility and bending ability of polymer materials, and their tendency to withstand deformation. In the current paper, we start by providing an equivalent model for the flexible microstrip patch antenna under bent conditions, followed by outlining the process of designing flexible antennas on polymer substrates. Finally, the fabricated flexible antennas were tested in an anechoic chamber for various radiation characteristics such as reflection coefficients, operating frequency shifts, and impedance mismatch with the transmission line, under bending conditions up to 7 mm. The practical outcomes were then compared with our recent investigation on flexible polymer substrate antennas for wearable applications. This study provides a means to select a suitable polymer substrate for future wearable sensors and antennas with high bendability.

In this paper, a coordinated multipoint joint transmission (CoMP-JT) framework at mmWave for a cyclic prefix (CP)-free multiuser OFDM wireless communication system is developed and analyzed. The aim is to provide high-quality service to cell-edge users; otherwise, the cell-users would suffer from significant signal degradation due to undesired interference. The impact of complex Hadamard transform with block diagonalization channel precoding for multiuser interference reduction and designed subcarrier mapping for out-of-band (OOB) reduction are investigated. In addition, the paper studied the input back-off-aided high-power amplifier for peak-to-average power ratio (PAPR) reduction and forward error correction channel coding for improved bit error rate (BER) for cell-edge users at mmWave frequencies. Moreover, signal-to-interference-noise ratio and ergodic achievable rate are estimated both in the presence and absence of CoMP-JT-based transmission technique to verify their significance in terms of transmitted power. Numerical investigations showed an OOB reduction of 312 dB, PAPR reduction from 17.50 dB to 7.66 dB, and improved BER of 1×10−3 in 16-QAM for a signal-to-noise ratio of −6 dB. Hence, the simulation results demonstrated the effectiveness of the developed system.

There is a significant nascent market for ethically produced products with enormous commercial potential around the world. A reliable method to signal the provenance of products is therefore critical for industry, given that competition based on price is not a viable strategy. The ability to trace and signal ethical treatment of animals is also of significant value to textiles manufactures. The efficacy of such a method can be measured with respect to the cost of implementation, scalability, and the difficulty of counterfeiting. The key to traceability is to win the trust of the consumer about the veracity of this information. Wearable sensors make it possible to monitor and improve the management of traceability and/or provenance. In this paper, we introduce a method for signalling the provenance of garments using radio frequency watermarks. The proposed model consists of two levels of authentication that are easy to use by legitimate vendors, but extremely difficult to imitate or hack, because the watermark is built-in and based on the radiation signature of electroactive materials.

Works on pico-satellites have gained momentum recently, especially those that consider pico-satellites as part of a much larger constellation or swarm. This feature allows pico-satellites to provide high temporal resolution of observational data and redundancy. In particular, it reduces the need for satellite-to-ground communications and, hence, helps save energy and allows the execution of distributed processing algorithms on the satellites themselves. Consequently, satellite-to-satellite or cross-link communication is critical. To realize these advantages, the cross-link antenna employed on pico-satellites must meet many criteria, namely, small size, lightweight, low-power consumption, high gain, wide bandwidth, circular polarization, and beam steerability. To date, no works have examined the suitability of existing planar antenna designs for the use on pico-satellites. To this end, this paper contributes to the literature by focusing on microstrip patch and slot antennas that have the ability to achieve high gain, beam steering, and wide bandwidth. This paper reviews 66 planar antenna designs, which includes 38-patch and 28-slot antennas. In addition, we provide an extensive qualitative comparison of these antennas in terms of their mass, size, gain, beam steerability, type of polarization, operating frequency band, and return loss. In addition, we have evaluated three antenna designs that best address the pico-satellite challenges on a common platform. We find that the asymmetric E-shaped patch antenna design is the most suitable for the use on 2U CubeSats. This is because of its small size (34 × 13 mm2) and high gain (7.3 dB). In addition, the E-shaped patch antenna yields a wide -10-dB bandwidth of 2300 MHz and a small return loss of -15.2 dB.

Critical wastewater events such as sewer main blockages or overflows are often not detected until after the fact. These events can be costly, from both an environmental impact and monetary standpoint. A standalone, portable radar device allowing non-invasive benchmarking of sewer pumping station (SPS) pumps is presented. Further, by configuring and deploying a complete Low Power Wide Area Network (LPWAN), Shoalhaven Water (SW) now has the opportunity to create “Internet of Things” (IoT)-capable devices that offer freedom from the reliance on mobile network providers, whilst avoiding congestion on the existing Supervisory Control and Data Acquisition (SCADA) telemetry backbone. This network infrastructure allows for devices capable of real-time monitoring to alert of any system failures, providing an effective tool to proactively capture the current state of the sewer network between the much larger SPSs. This paper presents novel solutions to improve the current wastewater network management procedures employed by SW. This paper also offers a complete review of wastewater monitoring networks and is one of the first to offer robust testing of Long Range Wide Area Network (LoRaWAN) network capabilities in Australia. The paper also provides a comprehensive summary of the LoRa protocol and all its functions. It was found that a LPWAN, utilising the LoRaWAN protocol and deployed appropriately within a geographic area, can attain maximum transmission distances of 20 km within an urban environment and up to 35 km line of sight.

In this work, the concept of peer-to-peer energy sharing in wildlife communication systems is explored. In this context, wild animals can share energy wirelessly besides their data communications as they opportunistically come into range of each other. Our goal is to find a way to balance the energy among the nodes and minimize this energy loss. We propose a novel encounter-based energy-sharing scheme, called EBES, that utilizes single and multi-hop transmission to achieve energy balance, minimize energy losses, and maximize the lifetime of the wildlife communication system. EBES is based on a variety of parameters, including the amount of energy left in the system and the nodes' encounter rate, and buffer sizes. In the simulation studies, we considered a wildlife communication network that is involved in data communication and applied EBES over the opportunistic routing protocols such as EBR, Spray&Wait, and Epidemic resulting in a network lifetime increase of 35% and improving the routing protocols performance. Additionally, we compared EBES with the other well-known energy balancing techniques that also contribute to data communication such as EA-Epidemic, EERPFAnt, and OE-OLSR and the results show the remaining energy was improved by 31%, 26%, and 15%, respectively. [ABSTRACT FROM AUTHOR]

High-performance biocompatible composite materials are gaining attention for their potential in various fields such as neural tissue scaffolds, bio-implantable devices, energy harvesting, and biomechanical sensors. However, these devices currently face limitations in miniaturization, finite battery lifetimes, fabrication complexity, and rigidity. Hence, there is an urgent need for smart and self-powering soft devices that are easily deployable under physiological conditions. Herein, we present a straightforward and efficient fabrication technique for creating flexible/stretchable fiber-based piezoelectric structures using a hybrid nanocomposite of polyvinylidene fluoride (PVDF), reduced graphene oxide (rGO), and barium-titanium oxide (BT). These nanocomposite fibers are capable of converting biomechanical stimuli into electrical signals across various structural designs (knit, braid, woven, and coil). It was found that a stretchable configuration with higher output voltage (4 V) and a power density (87 μW cm−3) was obtained using nanocomposite coiled fibers or knitted fibers, which are ideal candidates for real-time monitoring of physiological signals. These structures are being proposed for practical transition to the development of the next generation of fiber-based biomedical devices. The cytotoxicity and cytocompatibility of nanocomposite fibers were tested on human mesenchymal stromal cells. The obtained results suggest that the developed fibers can be utilized for smart scaffolds and bio-implantable devices. [ABSTRACT FROM AUTHOR]