Resource discovery approaches in cloudIoT: a systematic review

The Journal of Supercomputing - The cloud of things (CloudIoT) represents a general system of supporting infrastructure for storing and processing information gathered from smart objects and their...     

Zinc oxide nanoparticles: solvent-free synthesis,characterization and application as heterogeneous nanocatalyst for photodegradation of dye from aqueous phase

In present study, for the first time, ZnO nanoparticles have been synthesized via a simple, novel, solvent and template free solid-state thermal decomposition of the mixed Zn(NO₃)·6H₂O and cochineal powders as a novel starting reagent at 600?°C for 3 h. The as-prepared product was analyzed by XRD, EDS, SEM, TEM, FT-IR and DRS. Besides, the effect of cochineal powder on the morphology and particle size of ZnO nanoparticles was investigated. The results exhibited that cochineal powder prevents the sintering of nanoparticles and leads to formation of uniform particles. Moreover, the efficiency of ZnO nanoparticles as a photocatalyst for the decolorization of methylene orange (MO) has been evaluated and 90% degradation of MO was obtained after 120 min.     

Transport Properties of Topological Insulator-Based Ferromagnet/f-Wave Superconductor Junction

We investigate effect of magnetically-induced relativistic mass and also anisotropic f-wave pair coupling on the tunneling conductance on the surface of a 3D topological insulator ferromagnet/superconductor junction, which two types of pairing for superconductivity are possible. A topological insulator as a new state of condensed-matter caused by spin–orbit interaction and time-reversal symmetry has a bulk band gap and gapless surface states. We use the BTK formalism to find the charge carriers behavior. Due to two different nature of order parameters of the f-wave superconductivity, the tunneling conductance is found to be linearly dependent on the magnetic gap in terms of f ₁ and the exponential for f ₂. It is shown that the conversion of the conductance peak from ZBCP to ZBCD occurs in the f ₁ case with increasing m, while this is not observed in f ₂. Also, we find that the conductance behaves as a unit step function for the superconductor electrostatic potential in f ₁, and this should be usable in nanoelectronic switch devices. In addition, we illustrate how the magnetic gap affects the transmission coefficient in quite different behaviors for order parameters.     

Poly(acrylic acid)/gum arabic/ZnO semi-IPN hydrogels: synthesis,characterization and their optimizations by response surface methodology

Iranian Polymer Journal - Synthesis of novel semi-interpenetrating poly(acrylic acid) (PAA)/gum arabic (AG)/ZnO hydrogels by in situ free radical polymerization was optimized using response surface...     

Ammonia-free chemical bath deposition of nanocrystalline ZnS thin film buffer layer for solar cells

In this work, we prepared zinc sulfide thin films on glass substrates by ammonia-free chemical bath deposition method using thioacetamide as the sulfide source and Ethylene Diamine Tetra Acetic Acid disodium salt as the complexing agent in a solution of pH = 6.0. Thin films of ZnS with different thicknesses of 18–450 nm were prepared. The effect of film thickness and annealing temperature in atmospheric air, on optical properties, band gap energy and grain size of nanocrystals were studied. The X-ray diffraction analysis showed a cubic zinc blend structure and a diameter of about 2–5 nm for ZnS nanocrystals. The Fourier Transform Infrared spectrum of films revealed no peaks due to impurities. The as-deposited ZnS films had more than 70% transmittance in the visible region. The direct band gap of as-deposited films ranged from 3.68 to 3.78 eV and those of annealed films varied from 3.60 to 3.70 eV.     

MDP-Based Network Selection Scheme by Genetic Algorithm and Simulated Annealing for Vertical-Handover in Heterogeneous Wireless Networks

The hybrid algorithm for real-time vertical handover using different objective functions has been presented to find the optimal network to connect with a good quality of service in accordance with the user’s preferences. Markov processes are widely used in performance modelling of wireless and mobile communication systems. We address the problem of optimal wireless network selection during vertical handover, based on the received information, by embedding the decision problem in a Markov decision process (MDP) with genetic algorithm (GA), we use GA to find a set of optimal decisions that ensures the best trade-off between QoS based on their priority level. Then, we emerge improved genetic algorithm (IGA) with simulated annealing (SA) as leading methods for search and optimization problems in heterogeneous wireless networks. We formulate the vertical handoff decision problem as a MDP, with the objectives of maximizing the expected total reward and minimizing average number of handoffs. A reward function is constructed to assess the QoS during each connection, and the AHP method are applied in an iterative way, by which we can work out a stationary deterministic handoff decision policy. As it is, the characteristics of the current mobile devices recommend using fast and efficient algorithms to provide solutions near to real-time. These constraints have moved us to develop intelligent algorithm that avoid the slow and massive computations. This paper compares the formulation and results of five recent optimization algorithms: artificial bee colony, GA, differential evolution, particle swarm optimization and hybrid of (GA–SA). Simulation results indicated that choosing the SA rules would minimize the cost function, and also that, the IGA–SA algorithm could decrease the number of unnecessary handovers, and thereby prevent the ‘Ping-Pong’ effect.     

Nanocrystalline samarium tungstate: facile morphology-controlled preparation,characterization and investigation of optical and photocatalytic properties

In the current study, samarium tungstate Sm₂(WO₄)₃ nanoparticles were synthesized via a new route based on the reaction between samarium nitrate hexahydrate and sodium tungstate dihydrate in an aqueous solution. Besides, three amino acids such as cysteine, alanine, and glycine were introduce as capping agents and their effects on the morphology and particle size of Sm₂(WO₄)₃ were investigated. It was found that size and morphology could be easily realized by changing the type of amino acids. XRD, SEM, EDS, and UV–Vis spectroscopy were employed to characterize structural, morphological, and optical properties of Sm₂(WO₄)₃ nanoparticles. Sm₂(WO₄)₃ nanoparticles indicated a paramagnetic behavior at room temperature, as evidenced by using vibrating sample magnetometer. Furthermore, the photocatalytic properties of as synthesized Sm₂(WO₄)₃ were evaluated by degradation of methyl orange as water contaminant.     

Modeling the hollow cylindrical piezo-ceramics with axial polarization using equivalent electro-mechanical admittance matrix

Modeling a piezo-ceramics as an electro-mechanical element is usually done using the laws of electricity. Due to complexity of the derived circuits, this kind of modeling usually results in some simplifications. In this paper using the force–velocity boundary conditions and equalizing the mechanical elements to the electrical ones, the governing equations of a hollow cylindrical piezo-ceramics with axial polarization are solved. Then the equivalent electro-mechanical impedance is represented via matrix notation. Using the matrix algebra the resonance and anti-resonance frequencies are calculated and then compared to the experimental results. The proposed method does not need to any simplification in circuit analysis, and provides the capability of modeling the various layers of piezo-ceramics and metals together in electro-acoustical transducers.