Cooperative wideband sensing based on cyclostationary features with multiple malicious user elimination

Spectrum sensing is an essential concept in cognitive radio. To overcome the single node sensing issue that arises due to channel impediments, cooperative/multinode sensing is being used. Although cooperation among multiple cognitive users enhances the sensing performance, presence of few malicious cognitive users may severely degrade the efficiency of the system. In this paper, generalized extreme studentized deviate (GESD) and adjusted box-plot (ABP) methods are introduced to increase the sensing reliability of cooperative network by eliminating multiple malicious cognitive users. The performance of the cyclostationary feature detection method is compared with the energy detection method under different channel impediments. The simulation results are carried out with false alarm probability of 0.01 and a detection probability of 0.9. The simulation results reveal that there is a significant improvement in cooperative sensing performance by elimination of multiple malicious user in the network.     

Formulation of mobile agents for integration of supply chain using the KLAIM concept

With the ever-growing use of the internet for electronic commerce and data mining type applications, there seems to be a need for new network computing paradigms that can overcome the barriers posed by network congestion and unreliability. Mobile agent programming is a paradigm that enables programs to move from one host to another, do the processing locally and return results asynchronously. In this article, mobile computing is implemented by the use of a kernel programming language, Kernel Language for Agent Interaction and Mobility (KLAIM), to coordinate efficiently and streamline the functionality of a supply chain in terms of data transactions. The proposed KLAIM-based approach addresses the issues relating to mobility, integrity, privacy and security, which are a prime concern when operating in an open environment as normally encountered in a supply chain network. The proposed approach is supported by an example case study where an attempt is made to expedite and streamline the information transaction of a supply chain related to an automotive industry.     

Electromagnetic interference shielding behavior of chemically and thermally reduced graphene based multifunctional polyurethane nanocomposites: A comparative study

This article presents the effect of exfoliation, dispersion, and electrical conductivity of graphene sheets onto the electrical, electromagnetic interference (EMI) shielding, and gas barrier properties of thermoplastic polyurethane (TPU) based nanocomposite films. The chemically reduced graphene (CRG) and thermally reduced/annealed graphene (TRG) having Brunauer–Emmett–Teller surface areas of 18.2 and 159.6 m²/g, respectively, when solution blended with TPU matrix using N,N-dimethylformamide as a solvent. Graphene sheets based TPU nanocomposites have been evaluated and compared for EMI shielding in Ku band, electrical conductivity, and gas barrier property. TRG/TPU nanocomposite films showed excellent gas barrier against N₂ gas as compared to CRG/TPU. The EMI shielding effectiveness for neat CRG and TRG graphene sheets is found to be −80, −45 dB, respectively, at 2 mm thickness. The EMI shielding data revealed that TRG/TPU nanocomposites showed better shielding at lower concentration (10 wt %), while CRG displayed better attenuation at higher concentrations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47666.     

Microstructural,magnetic, and hyperfine characterizations of Cu-doped cobalt ferrite nanoparticles

We have investigated the structural and magnetic properties of polycrystalline Cu-substituted cobalt ferrite (Cu_xCo_1−xFe₂O₄: x = 0.00, 0.15, 0.30, 0.45, 0.60) nanoparticles, synthesized via chemical coprecipitation method. The prepared samples were of single phase as confirmed by X-ray diffraction analysis. The mean crystallite size ranged from 44 to 65 nm was obtained using Scherrer's formula. M-T curves revealed that the Curie temperature of all the samples was above room temperature and it was found to decrease with increasing Cu concentration, which was supported by Mössbauer spectra. Field cooled (FC) hysteresis curves showed ferrimagnetic nature at 5 K and room temperature. It was observed that careful variation of Cu concentration in cobalt ferrite lead to weak A-B interaction with tunable magnetic properties.     

A Phase Diagram for Epitaxial PbZr1−xTixO3 Thin Films at the Bulk Morphotropic Boundary Composition

A phase diagram of temperature versus strain was constructed for a (001)-oriented PbZr_{1− x} Ti _x O₃ epitaxial single crystal thin film near the bulk morphotropic boundary composition ( x =0.47) on an (001)-oriented cubic substrate. The phase-field approach is employed. It is shown that a mixture of distorted rhombohedral, orthorhombic, and tetragonal phases exists under small values of strain, i.e., close to the in-plane clamped boundary condition. This result contradicts thermodynamic calculations assuming a single-domain state that predicted a single distorted rhombohedral phase under similar strains. Furthermore, it is demonstrated that under a large tensile strain current phase-field simulations showed a tetragonal phase with a ₁ /a ₂ twin structures as the stable state whereas thermodynamic calculations predicted an orthorhombic phase.     

A simple synthesis of amine-derivatised superparamagnetic iron oxide nanoparticles for bioapplications

Adsorption of 3-aminopropyltriethoxysilane (APTS) on magnetite nanoparticles during its formation has been investigated to optimise the preparation of stable aqueous dispersion of amine derivatised magnetite nanoparticles. APTS adsorbs chemically on the surface of magnetite particle modifying its surface which is evident from thermal and C, H, N analysis. The variation of particle size has been observed with change of APTS concentration. X-ray diffractogram shows the formation of pure inverse spinel phase magnetite with average crystallite size 7 nm when equimolar (Fe₃O₄: APTS = 1:1) quantity of APTS was used during its synthesis. The presence of free surface –NH₂ groups and Fe–O–Si bonds was observed by FTIR. Raman spectrum further confirms the presence of surface –NH₂ groups. Transmission electron microscopy shows formation of particles of average size between 7 nm and 12 nm. The effective hydrodynamic diameter of the APTS coated particle agglomerates is 45.8 nm in stable aqueous colloidal dispersion, which is evident from photon correlation spectroscopy. VSM measurements at room temperature of both silanised and unsilanised magnetite shows their superparamagnetic nature with saturation magnetisation 41 e.m.u/g and 56 e.m.u/g, respectively. Avidin has been immobilised on the surface through glutaraldehyde, which demonstrates the possibility of the synthesised material to be used in protein immobilisation to form bioactive magnetic particles.     

Multinode sensing with forward error correction and differential evolution algorithms for noisy cognitive radio networks

Spectrum sensing is a vital phase in Cognitive Radio (CR) to identify the unutilized spectrum for dynamic spectrum access (DSA). Cooperative/multinode sensing is being used for signal detection to achieve spatial diversity gains. In cooperative sensing, the sensing channels are assumed to be noisy. However, the reporting/control channels (channels between CR and fusion center) are also contaminate with the noise, which degrades the cooperative detection accuracy. In this paper, (i) effect of reporting channels are studied and used forward error correction technique (convolutional encoder) to mitigate the effect of reporting channel noise, (ii) differential evolution algorithm is used to evaluate the optimum weights for cooperative users to maximize the sensing performance. Three different detection methods are considered for performance analysis. The simulations are carried out with different signal-to-noise ratio in control channel with and without error correction. The results reveal that, detection probability and accuracy of the system can be improved with convolutional coding together with differential evolution algorithm.     

FPGA‐based embedded platform for fiber optic gyroscope signal denoising

This paper presents System on Chip (SoC) implementation of a proposed denoising algorithm for fiber optic gyroscope (FOG) signal. The SoC is developed using an Auxillary Processing Unit of the proposed algorithm and implemented in the Xilinx Virtex‐5‐FXT‐1136 field programmable gate array. SoC implementation of this application is first of its kind. The proposed algorithm namely adaptive moving average‐based dual‐mode Kalman filter (AMADMKF) is a hybrid of adaptive moving average and Kalman filter (KF) technique. The performance of the proposed AMADMKF algorithm is compared with the discrete wavelet transform and KF of different gains. Allan variance analysis, standard deviation and signal to noise ratio (SNR) are used to measure the efficiency of the algorithm. The experimental result shows that AMADMKF algorithm reduces the standard deviation or drift of the signal by an order of 100 and improves the SNR approximately by 80 dB. The Allan variance analysis result shows that this algorithm also reduces different types of random errors of the signal significantly. The proposed algorithm is found to be the best suited algorithm for denoising the FOG signal in both the static and dynamic environments. Copyright © 2013 John Wiley & Sons, Ltd.     

Metal-Free Electrochemical [3+2] Cycloaddition between α-Amino Carbonyls and Tosylmethyl Isocyanide en route to Substituted Imidazoles

The established strategy unveils a metal and mediator-free electrochemical [3+2] cycloaddition approach among α-amino carbonyls and tosylmethyl isocyanide (TosMIC) fabricating substituted imidazole scaffolds. Implementation of electro-redox conditions on this cycloaddition approach eliminates the essential requirement of transition metal catalysts and chemical oxidants. A wide variety of different functionalities are well tolerated under this reaction condition, contributing to the substrate scope and applicability. Several control experiments and cyclic voltammetry studies suggest an electro-oxidation triggered successive C−C and C−N bond formations followed by rapid aromatization for constructing the five-membered core structure.