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.     

Subwavelength Nanopatch Cavities for Semiconductor Plasmon Lasers

We propose and analyze a family of nanoscale cavities for electrically pumped surface-emitting semiconductor lasers that use surface plasmons to provide optical mode confinement in cavities which have dimensions in the 100-300-nm range. The proposed laser cavities are in many ways nanoscale optical versions of micropatch antennas that are commonly used at microwave/RF frequencies. Surface plasmons are not only used for mode confinement but also for output beam shaping to realize single-lobe far-field radiation patterns with narrow beam waists from subwavelength size cavities. We identify the cavity modes with the largest quality factors and modal gain, and show that in the near-IR wavelength range (1.0-1.6 mum) cavity losses (including surface plasmon losses) can be compensated by the strong mode confinement in the gain region provided by the surface plasmons themselves and the required material threshold gain values can be smaller than 700 cm^-1.     

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.     

Crosstalk suppression in networked resistive sensor arrays using virtual ground technique

In 2D resistive sensor arrays, the interconnections are reduced considerably by sharing rows and columns among various sensor elements in such a way that one end of each sensor is connected to a row node and other end connected to a column node. This scheme results in total N?+?M interconnections for N?×?M array of sensors. Thus, it simplifies the interconnect complexity but suffers from the crosstalk problem among its elements. We experimentally demonstrate that this problem can be overcome by putting all the row nodes at virtually equal potential using virtual ground of high gain operational amplifiers in negative feedback. Although it requires large number of opamps, it solves the crosstalk problem to a large extent. Additionally, we get the response of all the sensors lying in a column simultaneously, resulting in a faster scanning capability. By performing lock-in-amplifier based measurements on a light dependent resistor at a randomly selected location in a 4?×?4 array of otherwise fixed valued resistors, we have shown that the technique can provide 86?dB crosstalk suppression even with a simple opamp. Finally, we demonstrate the circuit implementation of this technique for a 16?×?16 imaging array of light dependent resistors.     

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.     

Performance analysis of wireless communication system over nonidentical cascaded generalised gamma fading channels

Multiplicative fading statistics usually encountered in different radio propagation environments. In this context, we evaluate and analyse the performance of a wireless communication system over the nonidentical cascaded generalised Gamma Fading Channels, also known as generalised Bessel‐K fading channel. To this end, the closed‐form expressions for the amount of fading (AOF), the outage probability (OP), the average symbol error probability (SEP), and the channel capacity are derived. In addition approximate expressions for the average SEP with maximal ratio combining (MRC) diversity are also provided. The low‐ and high‐power solutions for the channel capacity are also provided. Furthermore, simplified asymptotic average SEP expressions for MRC and selection combining (SC) are presented to gain the system performance with diversity. The proposed methodologies provide more flexibility to accommodate different radio propagation scenarios. To examine the accuracy of the proposed solutions, numerical and simulation results are compared and shown to fit for variety of fading parameters.