Optical electronegativity, bulk modulus and electronic polarizability of materials

Correlations between the energy gap, optical electronegativity and bulk modulus are given for compound and ternary chalcopyrite semiconductors. Bulk modulus and electronic polarizability values have been evaluated from the optical electronegativity. The estimated values of these parameters are in good agreement with the available experimental data.     

Transparent and Flexible Cellulose Nanocrystal/Reduced Graphene Oxide Film for Proximity Sensing

The rapid development of touch screens as well as photoelectric sensors has stimulated the fabrication of reliable, convenient, and human‐friendly devices. Other than sensors that detect physical touch or are based on pressure sensing, proximity sensors offer controlled sensibility without physical contact. In this work we present a transparent and eco‐friendly sensor made through layer‐by‐layer spraying of modified graphene oxide filled cellulose nanocrystals on lithographic patterns of interdigitated electrodes on polymer substrates, which help to realize the precise location of approaching objects. Stable and reproducible signals generated by keeping the finger in close proximity to the sensor can be controlled by humidity, temperature, and the distance and number of sprayed layers. The chemical modification and reduction of the graphene oxide/cellulose crystal composite and its excellent nanostructure enable the development of proximity sensors with faster response and higher sensitivity, the integration of which resolves nearly all of the technological issues imposed on optoelectronic sensing devices.     

Biodegradation potential of pure and mixed bacterial cultures for removal of 4-nitroaniline from textile dye wastewater

Environmentally toxic aromatic amines including nitroanilines are commonly generated in dye contaminated wastewater in which azo dyes undergo degradation under anaerobic conditions. The aim of this study was to develop a process for biological treatment of 4-nitroaniline. Three bacteria identified as Acinetobacter sp., Citrobacter freundii and Klebsiella oxytoca were isolated from enrichment cultures of activated sludge on 4-nitroaniline, after which the isolates and the mixed culture were studied to determine optimal conditions for biodegradation. HPLC analyses showed the mixed culture was capable of complete removal of 100 μmol/L of 4-nitroaniline within 72 h under aerobic conditions. There was an inverse linear relationship (R² = 0.96) between the rate of degradation (V) and 4-nitraoaniline concentrations [S] over 100-1000 μmol/L. The bacterial culture was also capable of decolorizing structurally different azo dyes (Acid Red-88, Reactive Black-5, Direct Red-81, and Disperse Orange-3) and also degraded nitrobenzene. Our findings show that enrichment cultures from activated sludge can be effective for the removal of dyes and their toxic intermediates, and that treatment may best be accomplished using an anaerobic-aerobic process.     

Development and characterization of nano‐crystalline cellulose incorporated poly(lactic acid) composite films

Development of nano‐cellulose has fascinated a substantial attention for last few decades because of their exceptional and potentially useful features. Herein, nano‐crystalline cellulose has successfully been prepared from local cotton yarn via acid hydrolysis. Both X‐ray diffraction and scanning electron microscopy showed improvement in crystallinity of nano‐crystalline cellulose on acid hydrolysis of cotton yarn. The prepared nano‐crystalline cellulose has been used for the fabrication of poly(lactic acid) composite films using solution casting approach. The prepared composite films were characterized using advanced analytical techniques. The differential scanning calorimetry analysis, moreover, showed that on incorporating nano‐crystalline cellulose in the poly(lactic acid) matrix, glass transition temperature increased; whereas, melting temperature and cold crystallization temperature decreased. The decreasing value of crystallization temperature indicated an enhancement in chain mobility of composite films. The mechanical analysis showed that the composite films were stronger and more flexible than the pure poly(lactic acid) films.     

Robust Cluster-Based Routing Protocol for IoT-Assisted Smart Devices in WSN

The Internet of Things (IoT) is gaining attention because of its broad applicability, especially by integrating smart devices for massive communication during sensing tasks. IoT-assisted Wireless Sensor Networks (WSN) are suitable for various applications like industrial monitoring, agriculture, and transportation. In this regard, routing is challenging to find an efficient path using smart devices for transmitting the packets towards big data repositories while ensuring efficient energy utilization. This paper presents the Robust Cluster Based Routing Protocol (RCBRP) to identify the routing paths where less energy is consumed to enhances the network lifespan. The scheme is presented in six phases to explore flow and communication. We propose the two algorithms: i) energy-efficient clustering and routing algorithm and ii) distance and energy consumption calculation algorithm. The scheme consumes less energy and balances the load by clustering the smart devices. Our work is validated through extensive simulation using Matlab. Results elucidate the dominance of the proposed scheme is compared to counterparts in terms of energy consumption, the number of packets received at BS and the number of active and dead nodes. In the future, we shall consider edge computing to analyze the performance of robust clustering.     

Ultra-Low Power Small Size 5.8.GHz RF Transceiver Design for WiMAX/4G Applications

A state of the art ultra-low power small sized transceiver design has been proposed. This device consists of four blocks, including a frequency synthesizer (FS), a crystal oscillator (XO), transmitter and receiver attached with an antenna. It has been seen that wireless information technology and systems have played a vital role in the transformation of society in different aspects of life. Mobile wireless communications including WiMAX/4G have attracted researchers and developers. WiMAX/4G applications need a transceiver that can be used in the worst channel conditions, but with low power consumption and low input voltage at the 5.8 GHz frequency. The proposed transceiver operates on 1.2 V. The operating frequency, noise figure (NF) and receiver gain are 5.8 GHz, 4.0 dB and 90 dB respectively. It is a highly compatible transceiver with all the 4 G technologies. Implementation details and results have revealed that the proposed transceiver is much more efficient than the previously proposed transceivers in literature.     

Performance evaluation of control chart for multiple assignable causes using genetic algorithm

With a view to monitoring and controlling manufacturing processes in industries, control charts are widely used and needed to be designed economically to achieve minimum quality costs. Many authors have studied the economic design of the $ \overline{X} $ control chart after Duncan (J Am Stat Assoc 51(274):228–242, 1956) first proposed the economic model of the $ \overline{X} $ control chart for a single assignable cause. But, in practice, multiple assignable causes are more logical and realistic. Moreover, the economic design does not consider statistical properties like bound on type I and type II error, and average time to signal (ATS). This paper focuses on evaluating the performance of genetic algorithm (GA) in pure economic and economic statistical design of the $ \overline{X} $ control chart for multiple assignable causes. The performances of GA are demonstrated by comparing its result with the previously proposed grid search technique for a numerical example. The Duncan model of multiple assignable causes is adopted to formulate objective function, and the computation is achieved by approximation through a numerical method named Simpson's 1/3 rule. Comparison distinctly shows the superiority of GA over grid search results for economic statistical design.     

Performance analysis of secure communications over correlated slow‐fading additive white Gaussian noise channels

The broadcast nature of communications in wireless communication networks makes it vulnerable to some attacks, particularly eavesdrop attack. Hence, information security can have a key role to protect privacy and avoid identity theft in these networks, especially in distributed networks. In the wireless systems, the signal propagation is affected by path loss, slow fading (shadowing), and fast fading (multi‐path fading). As we know, there is a correlation between communication channels in the real radio environments. This correlation is defined by the correlation between their shadowing and/or multipath fading factors. So when there are several channels in the wireless systems, there is certainly a correlation between the channels. In this paper, we assume that the transmitter knows the full channel state information (CSI), it means the transmitter knows both the channel gains of the illegitimate (ie, eavesdropper) and the legitimate receivers and study the performance of secure communications of single‐input single‐output (SISO) systems consisting of single antenna devices, in the presence of a single antenna passive eavesdropper over correlated slow fading channels, where the main (transmitter to legitimate receiver) and eavesdropper (transmitter to illegitimate receiver) channels are correlated. Finally, we present numerical results and verify the accuracy of our analysis by Monte‐Carlo simulations.     

Design of a novel miniaturized bandstop frequency selective surface exhibiting polarization insensitivity and enhanced oblique stability

In this article, a miniaturized 2.5‐dimensional frequency selective surface (FSS) bandstop filter operating at 2.4 GHz is presented. The proposed FSS contains meander lines as well as metallic patches on top and bottom layer of FR‐4 substrate, and vertical vias are employed to connect the top and the bottom layers. The proposed configuration significantly reduced the size of unit cell to 0.040λ₀ × 0.040λ₀ (where λ₀ is the free space wavelength) at the desired frequency of 2.4 GHz. Additionally, this element arrangement assists in achieving fractional bandwidth of 140%. The measured ?10 dB bandwidth is from 1 to 4.5 GHz. The proposed FSS is polarization insensitive and highly angularly stable (up to 75°). The equivalent circuit model (ECM) of this FSS and related surface current distribution are also provided to understand its working mechanism. The design performance validation has been carried out through the construction and testing of a functional prototype. The full wave simulation, the ECM, and the measured results depict a promising agreement.     

Effective technique for the recognition of offline Arabic handwritten words using hidden Markov models

In this paper, we present a novel segmentation-free Arabic handwriting recognition system based on hidden Markov model (HMM). Two main contributions are introduced: a new technique for dividing the image into nonuniform horizontal segments to extract the features and a new technique for solving the problems of the skewing of characters by fusing multiple HMMs. Moreover, two enhancements are introduced: the pre-processing method and feature extraction using concavity space. The proposed system first pre-processes the input image by setting the thickness of the input word to three pixels and fixing the spacing between the different parts of the word. The input image is divided into constant number of nonuniform horizontal segments depending on the distribution of the foreground pixels. A set of robust features representing the gradient of the foreground pixels is extracted using sliding windows. The input image is decomposed into several images representing the vertical, horizontal, left diagonal and right diagonal edges in the image. A set of robust features representing the densities of the foreground pixels in the various edge images is extracted using sliding windows. The proposed system builds character HMM models and learns word HMM models using embedded training. Besides the vertical sliding window, two slanted sliding windows are used to extract the features. Three different HMMs are used: one for the vertical sliding window and two for the slanted windows. A fusion scheme is used to combine the three HMMs. The proposed system is very promising and outperforms all the other Arabic handwriting recognition systems reported in the literature.