DEICA: A differential evolution-based improved clustering algorithm for IoT-based heterogeneous wireless sensor networks

With the evolution of technology, many modern applications like habitat monitoring, environmental monitoring, disaster prediction and management, and telehealth care have been proposed on wireless sensor networks (WSNs) with Internet of Things (IoT) integration. However, the performance of these networks is restricted because of the various constraints imposed due to the participating sensor nodes, such as nonreplaceable limited power units, constrained computation, and limited storage. Power limitation is the most severe among these restrictions. Hence, the researchers have sought schemes enabling energy-efficient network operations as the most crucial issue. A metaheuristic clustering scheme is proposed here to address this problem, which employs the differential evolution (DE) technique as a tool. The proposed scheme achieves improved network performance via the formulation of load-balanced clusters, resulting in a more scalable and adaptable network. The proposed scheme considers multiple parameters such as nodes' energy level, degree, proximity, and population for suitable network partitioning. Through various simulation results and experimentation, it establishes its efficacy over state-of-the-art schemes in respect of load-balanced cluster formation, improved network lifetime, network resource utilization, and network throughput. The proposed scheme ensures up to 57.69%, 33.16%, and 57.74% gains in network lifetime, energy utilization, and data packet delivery under varying network configurations. Besides providing the quantitative analysis, a detailed statistical analysis has also been performed that describes the acceptability of the proposed scheme under different network configurations.     

Design and Performance Study of Dynamic Fractors in Any of the Four Quadrants

A fractor is a simple fractional-order system. Its transfer function is \(1/Fs^{\alpha }\); the coefficient, F, is called the fractance, and \(\alpha \) is called the exponent of the fractor. This paper presents how a fractor can be realized, using RC ladder circuit, meeting the predefined specifications on both F and \(\alpha \). Besides, commonly reported fractors have \(\alpha \) between 0 and 1. So, their constant phase angles (CPA) are always restricted between \(0^{\circ }\) and \(-90^{\circ }\). This work has employed GIC topology to realize fractors from any of the four quadrants, which means fractors with \(\alpha \) between \(-\)2 and +2. Hence, one can achieve any desired CPA between \(+180^{\circ }\) and \(-180^{\circ }\). The paper also exhibits how these GIC parameters can be used to tune the fractance of emulated fractors in real time, thus realizing dynamic fractors. In this work, a number of fractors are developed as per proposed technique, their impedance characteristics are studied, and fractance values are tuned experimentally.     

Annealing-Induced Morphological Changes in Nanocrystalline Quantum Dots and Their Impact on Charge Transport Properties

The effects of thermal annealing on the morphological and photoconductive properties of cadmium selenide quantum dots coated with zinc sulfide are studied. The results of transmission electron microscopy with in situ annealing show a number of events taking place simultaneously, including aggregation of dots, changes in the size and shape distribution, and reduction in interdot separation. Transient absorption results indicate that there is a small redshift of the spectrum. There is a shortening of the absorption decay lifetimes due to annealing. Higher photocurrents are measured in the annealed compared with unannealed dots at room temperature.     

Sink Mobility-Based Energy Efficient Routing Algorithm Variants in WSN

International Journal of Wireless Information Networks - In this work, energy efficient routing protocol variants considering different sink mobility in hierarchical cluster based wireless sensor...     

Impacts of user-selfishness on cooperative content caching in social wireless networks

Cooperative caching can be an effective mechanism for reducing electronic content provisioning cost in Social Wireless Networks (SWNETs). These networks are formed by a collection of mobile data enabled devices physically gathering in settings such as university campus, malls, airport and other public places. In this paper, we first propose an optimal collaborative object caching policy in order to minimize the object provisioning cost in SWNETs with homogenous user requests and a peer-rebate model for promoting collaboration. Then using an analytical model we study the impacts of user selfishness on the provisioning cost and the earned rebate when certain nodes in an SWNET selfishly deviate from the optimal policy. User selfishness is motivated in order to either increase individually earned rebate or to reduce content provisioning cost. The analytical model is validated by experimental results from simulated SWNETs using the network simulator ns2.     

The IEEE P1520 standards initiative for programmable networkinterfaces

This article discusses the need for standard software interfaces for programming of networks, specifically for service and signaling control, through programming interfaces. The objective is to enable the development of open signaling, control, and management applications as well as higher-level multimedia services on networks. The scope of this effort includes ATM switches, circuit switches, IP routers, and hybrid switches such as those that provide for fast switching of IP packets over an ATM backbone. The basic ideas represented herein are in the process of development as a standard for application programming interfaces for networks under IEEE Standards Project IEEE P1520     

Spectrally selective NbAlN/NbAlON/Si3N4 tandem absorber for high-temperature solar applications

A new spectrally selective NbAlN/NbAlON/Si₃N₄ tandem absorber was deposited on copper substrates using a reactive direct current magnetron sputtering system. A high solar absorptance (0.956) and a low emittance (0.07) were achieved by gradually decreasing the refractive index from the substrate to the surface. The tandem absorber was characterized using solar spectrum reflectometer and emissometer, X-ray photoelectron spectroscopy, phase-modulated spectroscopic ellipsometry, atomic force microscopy and micro-Raman spectroscopy techniques. In order to study the thermal stability of the tandem absorbers, they were subjected to heat treatment (in air and vacuum) at different durations and temperatures. The tandem absorber deposited on copper substrate exhibited high solar selectivity in the order of 13–15 even after heat treatment in air up to 500 °C for 2 h. These tandem absorbers also exhibited high thermal stability (450 °C) in air for longer durations (116 h). The onset of oxidation for the tandem absorber deposited on silicon substrates was 650 °C, indicating a high oxidation resistance. The results of the present study indicate the importance of NbAlN/NbAlON/Si₃N₄ tandem absorber for high-temperature solar selective applications.     

A pairing-free identity-based authenticated group key agreement protocol for imbalanced mobile networks

The secure and reliable group communication gains popularity in imbalanced mobile networks due to the increase demand of the group-oriented applications such as teleconferences, collaborative workspaces, etc. For acquiring the group security objectives, many authenticated group key agreement (AGKA) protocols exploiting the public key infrastructure have been proposed, which require additional processing and storage space for validation of the public keys and the certificates. In addition, the most of the AGKA protocols are implemented using bilinear pairing and a map-to-point (MTP) hash function. The relative computation cost of the bilinear pairing is approximately two to three times more than the elliptic curve point multiplication (ECPM) and the MTP function has higher computation cost than an ECPM. Due to the limitation of communication bandwidth, computation ability, and storage space of the low-power mobile devices, these protocols are not suitable especially for insecure imbalanced mobile networks. To cope with the aforementioned problems, in this paper, we proposed a pairing-free identity-based authenticated group key agreement protocol using elliptic curve cryptosystem. It is found that the proposed protocol, compared with the related protocols, not only improves the computational efficiencies, but also enhances the security features.     

4D Printing of Shape Memory Materials for Textiles: Mechanism,Mathematical Modeling,and Challenges

Shape memory materials (SMMs) in 3D printing (3DP) technology garnered much attention due to their ability to respond to external stimuli, which direct this technology toward an emerging area of research, “4D printing (4DP) technology.” In contrast to classical 3D printed objects, the fourth dimension, time, allows printed objects to undergo significant changes in shape, size, or color when subjected to external stimuli. Highly precise and calibrated 4D materials, which can perform together to achieve robust 4D objects, are in great demand in various fields such as military applications, space suits, robotic systems, apparel, healthcare, sports, etc. This review, for the first time, to the best of the authors’ knowledge, focuses on recent advances in SMMs (e.g., polymers, metals, etc.) based wearable smart textiles and fashion goods. This review integrates the basic overview of 3DP technology, fabrication methods, the transition of 3DP to 4DP, the chemistry behind the fundamental working principles of 4D printed objects, materials selection for smart textiles and fashion goods. The central part summarizes the effect of major external stimuli on 4D textile materials followed by the major applications. Lastly, prospects and challenges are discussed, so that future researchers can continue the progress of this technology.