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Commercially pure aluminium is a prominent material for aviation, construction and automotive industries; however, its poor mechanical properties have restricted its usages. Friction stir process (...

The application of the Internet of Things (IoT) in wireless sensor networks (WSNs) poses serious challenges in preserving network longevity since the IoT necessitates a considerable amount of energy usage for sensing, processing, and data communication. As a result, there are several conventional algorithms that aim to enhance the performance of WSN networks by incorporating various optimization strategies. These algorithms primarily focus on the network layer by developing routing protocols to perform reliable communication in an energy-efficient manner, thus leading to an enhanced network life. For increasing the network lifetime in WSNs, clustering has been widely accepted as an important method that groups sensor nodes (SNs) into clusters. Additionally, numerous researchers have been focusing on devising various methods to increase the network lifetime. The prime factor that helps to maximize the network lifetime is the minimization of energy consumption. The authors of this paper propose a multi-objective optimization approach. It selects the optimal route for transmitting packets from source to sink or the base station (BS). The proposed model employs a two-step approach. The first step employs a trust model to select the cluster heads (CHs) that manage the data communication between the BS and nodes in the cluster. Further, a novel hybrid algorithm, combining a particle swarm optimization (PSO) algorithm and a genetic algorithm (GA), is proposed to determine the routes for data transmission. To validate the efficacy of the proposed hybrid algorithm, named PSOGA, simulations were conducted and the results were compared with the existing LEACH method and PSO, with a random route selection for five different cases. The obtained results establish the efficiency of the proposed approach, as it outperforms existing methods with increased energy efficiency, increased network throughput, high packet delivery rate, and high residual energy throughout the entire iterations.

The excessive enhance in the number of subscribers in the wireless cell network, due to which the Mobile Network Operators (MNOs) facing the immense issues in giving the high-level executives of the broadband utility.cyc Long-Term Evolution (LTE) has capable of encountering the user’s demands by giving a high level of data rate. The key performance indicators (KPIs) have been recorded and reform the network execution in request to give the high-grade utility and also to attain better resource usage. Accessibility is utilized to figure out the success ratio of the user equipment (UE) in penetrating the cell network. The accessibility is indicated as the possibility that user equipment (UE) will be apt to penetrate the cell network utility for a fixed time duration. In this paper, the ANN tool is used to find out the prediction accuracy level of the accessibility of the wireless cellular network. For this purpose, key performance indicators (KPIs) data are acquired from the real field measurement of approximately 50,000 BTS locations by the Nokia Network Pvt. Ltd., India.

Thermodynamic, dielectric and electro-optical properties of a nematic liquid crystal namely 4-(trans-4-n-hexylcyclohexyl) isothiocyanatobenzoate (6CHBT) mixed with silver nanoparticles (Ag-NPs) of two widely different sizes have been studied. Thermodynamic studies suggest nominal increase in isotropic to nematic transition temperature of the nano composites as compared to the pure 6CHBT. Dielectric parameters of nano composites in the homeotropic and planar aligned samples have been measured in the frequency range of 1 Hz–35 MHz. Dielectric studies suggest that anisotropy is marginally decreased due to the dispersion of Ag-NPs. Threshold voltage for Freedericksz transition and splay elastic constant has decreased in the case of nano composites. Dielectric studies also suggest that relaxation mode corresponding to the molecular rotation about its long axis cannot be detected in the experimental window of the frequency. However, we obtained a relaxation mode due to the molecular rotation about its short axis.

Nanocomposites of discotic liquid crystal namely 2, 3, 6, 7, 10, 11-hexabutyloxytryphenylene (HAT4) in existence of variable concentration of gold nanoparticles (GNPs) have been studied at room tem...

Herein, we report the effect 50 keV nitrogen ion implantation at varying fluence on the optical properties of graphene nanosheets (number of layers

We report a systematic work on the effect of pressure on thermodynamic properties of a plastic columnar discotic liquid crystal (DLC), namely 2, 3, 6, 7, 10, 11-hexabutyloxytriphenylene (HAT4) dispersed with gold nanoparticles up to 1000 MPa by using a high-pressure differential scanning calorimeter. The goal is to determine how elevated pressure can be used to modify the physical properties of plastic columnar DLC and their nanocomposites via changes in inter- and intra-molecular distances of discotics. We find that the columnar hexagonal plastic to isotropic liquid (Colhp–IL) phase transition temperatures and enthalpy decrease with increasing pressure. However, crystal to plastic columnar hexagonal (Cr–Colhp) transition temperature remains almost unchanged for pure and their nanocomposites. The effect of pressure on the phase behaviour of DLC has been studied to elucidate the nature of the mesophase behaviour.

Clustering sensor nodes in a wireless sensor network is a key technique to reduce the energy consumption of sensors which extends the lifetime of the network. The head of the cluster plays a key role in a network and serves as a router. In addition, the head of the cluster is responsible for collecting and transmitting sensed information from their cluster members to a destination node or base station/sink. Hence, an efficient clustering approach is required to safely elect a cluster head. It remains a critical task for overall network performance. As a result, in this research approach, we proposed a scheme for selection of cluster head method based on a trust factor that ensures all nodes are trustworthy and authentic during communication. To achieve this, direct trust is calculated using parameters such as the residual energy and the distance between the nodes, along with the use of the k-means clustering algorithm. The simulation results show that in terms of network lifetime, packet delivery ratio, packet drop rate, and energy consumption, the proposed solution outperforms the LEACH protocol. In addition, this strategy can significantly improve performance while discriminating against the network's legitimate and malicious (or compromised) nodes.

In this research work we estimate the pollutant removal capability of two dimensional molybdenum disulfide (MoS2) nanosheets from aqueous medium, for these purpose molybdenum disulfide nanosheets was prepared by employing liquid exfoliation process on MoS2 bulk. The prepared samples of MoS2 nanosheets are characterized by using XRD, SEM, TEM, Raman, UV-visible absorption and photoluminescence measurements. After confirmation of MoS2 nanosheets formation, prepared MoS2 nanosheets are implemented for evaluating the pollutant removal capacity towards blue dye from aqueous medium.In this research work we estimate the pollutant removal capability of two dimensional molybdenum disulfide (MoS2) nanosheets from aqueous medium, for these purpose molybdenum disulfide nanosheets was prepared by employing liquid exfoliation process on MoS2 bulk. The prepared samples of MoS2 nanosheets are characterized by using XRD, SEM, TEM, Raman, UV-visible absorption and photoluminescence measurements. After confirmation of MoS2 nanosheets formation, prepared MoS2 nanosheets are implemented for evaluating the pollutant removal capacity towards blue dye from aqueous medium.

Changes in the electro-optical and dielectric properties of 4-pentyl-4-cyanobiphenyl due to the dispersion of single walled carbon nanotubes have been investigated. Dielectric spectroscopy for planar and homeotropic aligned samples has been carried out in the frequency range of 1 Hz–35 MHz. Threshold and switching voltages, dielectric anisotropy, dielectric strength, relaxation frequency, distribution parameter and activation energy of an observed relaxation mechanism have been determined for the pure as well as dispersed samples. Electro-optical experiments illustrate that the threshold voltage required for the switching of the molecular directors from the planar to the homeotropic orientation decreases due to the dispersion of single walled carbon nanotubes. The steepness of the transmission-voltage curve also improves due to the dispersion of single walled carbon nanotubes. The dielectric relaxation study of the homeotropic aligned samples shows that the relaxation frequency corresponding to the flip-flop motion of the molecules about their short axes increases due to the dispersion of single walled carbon nanotubes.

In the present work, single-walled carbon nanotubes (SWCNTs) were dispersed in a room temperature nematic liquid crystal 4-pentyl-4′-cyanobiphenyl at the concentration of 0.02 and 0.05 wt%. Differe...

We have studied the effect of gold nanoparticles (GNPs) on the thermodynamical, optical and dielectrical parameters of a discotic liquid crystal (DLC) namely hexabutyloxytriphenylene (HAT4). It has been observed that with the increase of GNPs concentration in DLC, composites shows two different regions. In the first regions i.e. low concentrations ( hp -I L ) transition temperature and enthalpy (ΔH) decrease rapidly while in the second region i.e. higher concentrations (>1 wt%) Col hp -I L transition temperature and ΔH are approximately constant. It has been observed that, in the case of composites having 0.2 and 0.6 wt% of GNPs, conductivity has enhanced but it is poor as compared to the composite having 1.2 wt% of GNPs. For 1.2 wt% of GNPs, conductivity has increased by seven orders of magnitude as compared to the DLC. Optical study suggests that band gap of nanocomposites has decreased due to dispersion of GNPs.

Dispersion of ferroelectric Barium Titanate Nano Particles (BTNPs) in a nematic liquid crystal (NLC) display material namely 4-pentyl-4′-cyanobipheny (5CB) has been studied by differential scanning calorimeter, UV–Vis spectroscopy, polarizing light microscopy, dielectric spectroscopy and electro optical studies. BTNPs have been dispersed in three different concentrations in pure 5CB viz. 0.05, 0.5 and 5.0 wt.%. It has been observed that with the increase of BTNP concentrations in 5CB, the nematic to isotropic transition temperatures, parallel components of dielectric permittivity and hence dielectric anisotropy decreases significantly unlike in the earlier studies. Threshold voltage for the Freedericksz transition, switching voltage and splay elastic constant have also decreased due to the dispersion of BTNPs. Relaxation frequency and activation energy of an observed relaxation mode corresponding to molecular rotation about the short axis are almost the same for pure and its nanocomposites. The ionic conductivity has increased by two orders of magnitudes for 0.05 wt.% of nanocomposites. The optical study suggests that due to dispersion of BTNPs band gap has decreased.

Thermodynamical, dielectric, optical and electro-optical characterisation of pure 8CB and its composites with gold and silver nanoparticles have been studied. Thermodynamical studies suggest a decrease in clearing temperature of the nanocomposite systems as compared to the pure system. Dielectric parameters of pure nematic liquid crystal and nanocomposites in the homeotropic and planar aligned samples have been measured in the frequency range of 1–35 MHz. Ionic conductivity increases significantly in nematic and smectic Ad (SmAd) phases, whereas dielectric anisotropy is almost unchanged for both the nanocomposites. Threshold voltage for Freederick transition, switching voltage and splay elastic constant have decreased in the case of nanocomposite systems. Relaxation frequency and activation energy of an observed relaxation mode corresponding to molecular rotation about the short axis increase in the SmAd phases of both the nanocomposites. The optical study suggests that due to dispersion of nanoparticles,...

Sensors these days are ubiquitous. They are in homes, factories, farms and just about everywhere. For distributed sensing requirements, several sensors are deployed and connected on a wireless media forming a Wireless Sensor Network (WSN). Sensor nodes communicate with each other and with a base station (BS). In this paper we first review recent work which is focused on cross-layer WSN design techniques based on the Open System Interconnection (OSI) model. Sensor nodes are often clustered and cluster heads (CH) are used to route data to the BS. We have also reviewed constraints-based routing algorithms which select a routing path satisfying administrative-oriented or Quality of Service-oriented (QoS-oriented) constraints. The algorithms minimize costs, balance network load, or increase security. Previous works of cross-layer design for malicious node identification, diagonal data aggregation and route adjustments were deficient to support WSN. The major problem was higher energy consumption and congestion during data aggregation. To overcome all the limitations and the problems that exist in cross layer design of WSN, we have proposed a novel design in this paper.

In this work, we emphasize on the surface property modification involved during the strong interfacial adhesion of graphene oxide (GO) nanosheets with poly vinyl alcohol (PVA) matrix. Raman, x-ray diffraction spectrum and scanning Kelvin probe microscopic measurement were done to analyze the effect of graphene oxide on surface property of poly vinyl alcohol.

A dispersion of colloidal gold nanoparticles (GNPs) in a triphenylene-based discotic liquid crystal (DLC), namely 2,3,6,7,10,11-hexabutyloxytriphenylene (HAT4), possessing a hexatic plastic columnar phase (Colhp) phase, has been studied by differential scanning calorimetry, polarized light microscopy, UV-Vis absorption spectroscopy, X-ray diffraction and dielectric spectroscopy. GNPs have been dispersed at three different concentrations in pure HAT4 viz. 0.2, 0.6 and 1.2 wt%. It has been observed that with the increase of GNPs concentration, the Colhp–isotropic liquid transition temperature decreases substantially but the crystal–Colhp transition temperature does not changes significantly. Electrical conductivity increases by at least five orders of magnitude for the highest concentration of GNPs (1.2 wt%) as compared to the pure material i.e. HAT4. Observed results suggest that although extremely low concentrations of GNPs are not very useful, a moderate concentration is highly useful for increasing the conductivity of the Colhp phase and also to implant surface plasmon resonance. These results may be exploited to enhance the efficiency of electro-optical devices by using HAT4–GNPs composites.

Present work describes the experimental analysis of unsteady state heat transfer of different solid geometries. Heat transfer process in considered as a function of time only i.e. solid body behave as ‘Lumped’ means there is uniform temperature with in the body and having negligible internal thermal conduction resistance. The lumped analysis is done with cylindrical, conical and mixed geometry of cylinder and cone of two different materials. Specimens are heated in water ant cooled in air to estimate the heat transfer response of geometries in same ambient conditions MATLAB programming is done for calculation to obtain good and accurate results and to estimate heat transfer response of different geometries used in many engineering application.

We report a new chemical method for synthesis of graphene with good yield. Graphene obtained by this chemical route was subjected to electrochemical characterization using two different redox materials for their suitability in electrochemical biosensing applications. The synthesized graphene was used for the detection of neurotransmitters like dopamine and serotonin. The electrodes exhibited 20% +/- 5% (N = 5) decrease in their signal after forty five days storage in the laboratory atmosphere. High stability of chemically synthesized graphene as electrochemical biosensor is presented in this work.

Carbon nanotubes, extreme-aspect ratio cylinders with walls of sp2 hybridized carbon atoms, have many interesting and highly anisotropic physical properties such as high electrical and thermal conductivity or mechanical rigidity along the tube axis. Nematics are orientationally ordered fluids whose average orientation direction can be manipulated on application of electric and magnetic fields. The self-organizing properties of nematics can be used to align the carbon nanotubes dispersed in them. In the present work, we have dispersed single walled carbon nanotubes (of 2 nm dia) in a room temperature nematic liquid crystal 4-pentyl-4′cyanobiphenyl and carried out many experimental studies.

The effect of swift heavy ions irradiation on optical and electronic properties of chemically synthesized graphene–TiO2 nanocomposites is presented. Modification of surface properties of these nanocomposites by irradiation with three different ions and with varying fluence was analyzed by Raman spectroscopy, transmission electron microscopy, and scanning Kelvin probe microscopy techniques. Raman spectra of irradiated samples exhibit systematic changes in the characteristic peaks of both graphene and TiO2. The nanocrystallite dimension calculated from Raman peak intensity decreases with fluence, indicating the occurrence of peripheral fragmentation. Furthermore, measurement of the surface contact potential difference using scanning Kelvin probe reveals that the work function of graphene–titanium dioxide nanocomposites can be effectively increased by more than 1 eV.

Surface potential of chemically synthesized graphene oxide (GO) and gold nanoparticles decorated GO (Au-GO) have been measured using scanning Kelvin probe (SKP) microscope. The Raman spectra of GO and Au-GO confirms presence of D and G peaks of GO. The intensity of both the peaks gets enhanced in case of Au-GO. The enhancement is due to surface enhanced Raman scattering (SERS) of GO. Such type of composite material has been used as a photocatalyst for degradation of Rhodamine B dye molecules. The degradation rate constant was found to be 1.6 × 10−2 min−1 in visible light.

Mobile ad hoc networks (MANET) support multi hop routing in the absence of central base station. The change in network topology due to the node movement associated with the link failure and creation, scarce in radio resources and bandwidth, limited battery power and computing capability pose challenges in packet routing in MANET. The proposed Energy Saving Ad hoc Routing (ESAR) algorithm targets to achieve better energy efficient with a longer network life time. The algorithm selects a path for routing by considering the actual distance between the source and destination along with the minimum available energy of a node in the path. This selected path is chosen as the best path for packet transmission till any node in the path exhausts battery power beyond a threshold value. At this point of time, a backup path is selected as an alternate path for packet transmission. The process is repeated till all the paths from the same source to destination are exhausted with their battery power. The simulation result of the proposed algorithm ESAR indicates that the network life time is improved upon the existing routing algorithms.

Correlation between the work function and oxygen content at various stages during synthesis of graphene by chemical route is presented. The values of work function in terms of contact surface potential difference (CPD) were estimated using a scanning Kelvin probe method. Oxygen content was determined using energy dispersive X-ray absorption (EDAX), and the data was further supported using the Rutherford back scattering method in oxygen resonance mode. Results indicated a linear correlation between the oxygen content and measured values of CPD at various stages during the chemical synthesis of graphene.