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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.

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.

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.

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.

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 FROM AUTHOR]

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.