Quasi oppositional Aquila optimizer-based task scheduling approach in an IoT enabled cloud environment

The Journal of Supercomputing - Large-scale applications of the Internet of Things (IoT) necessitate significant computing tasks and storage resources that are progressively installed in the cloud...     

Fibonacci sequences quasiperiodic A5B6C7 ferroelectric based photonic crystal: FDTD analysis

In this study, we present an investigation of the optical properties and band structures for the conventional and Fibonacci photonic crystals (PCs) based on some A⁵B⁶C⁷ ferroelectrics (SbSBr and BiTeCl). Here, we use one dimensional SbSBr and BiTeCl based layers in air background. We have theoretically calculated the photonic band structure and transmission spectra of SbSBr and BiTeCl based PC superlattices. The position of minima in the transmission spectrum correlates with the gaps obtained in the calculation. The intensity of the transmission depths is more intense in the case of higher refractive index contrast between the layers. In our simulation, we employed the finite-difference time domain technique and the plane wave expansion method, which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives.     

A Comparison of Energy Detectability Models for Cognitive Radios in Fading Environments

In this work, we first analyze the accuracy of different energy detector models in approximating the exact solution in AWGN. These models motivate us to develop approximation analysis to address energy detection for fading channels. Our analysis develops approximation that has almost the same performance as the exact solution in Rayleigh channels. Our new model is simple enough to derive the relationship between the required number of samples (N) and the signal-to-noise ratio for a single Rayleigh channel similar to the one obtained for AWGN channels. We also define a fading margin for link budget calculations that relates N in fading channels to AWGN channels. Furthermore, we analyze the impact of multiple antennas for cognitive radios considering two receiver diversity schemes and quantify the improvement in performance regarding this margin. All the analytical results derived in this paper are verified by simulations. Finally, we have implemented and verified energy detection models in our multiple antenna wireless testbed.     

Hierarchical switching for active disturbance attenuation with fine controller tuning

In this paper, a novel adaptive disturbance attenuation algorithm is proposed combining switching and tuning. A two‐level hierarchical switching logic is developed, which first selects in a short time the potentially best controller among a finite pre‐designed family and then performs a local refinement of its attenuation capability. Thanks to the controller fine tuning, the proposed technique is able to provide a substantial performance improvement in terms of attenuation level as compared with a pure adaptive switching control scheme; at the same time, it retains the positive features of switching‐based approaches, in particular, concerning the possibility of rapidly achieving a satisfactory behavior. Further, an arbitrary attenuation level is ensured in the presence of particular classes of disturbances and provided that it is compatible with robust stability requirement. Simulation results are shown to underline the potential of the approach as a solution to the problem. Copyright © 2016 John Wiley & Sons, Ltd.     

Gallium recovery from Bayer's liquor using hydroxamic acid resin

Gallium, which is extensively used in the production of semiconductor materials, is present at the parts per million level in Bayer's liquor. The low concentration of gallium in the liquor, along with the high concentration of aluminum, prompted the use of chelating ion exchangers as an alternative separation process. A chelating ion exchange resin with hydroxamic groups attached to the copolymer of acrylonitrile‐divinylbenzene has been prepared by suspension polymerization followed by hydrolysis and chelation with hydroxylamine hydrochloride. Adsorption studies of gallium, using the above hydroxamic acid resin, were carried out. Adsorption was dependent on particle size of the resin and optimum conditions are determined for obtaining 0.3‐ to 0.5‐mm particles by varying the composition of the emulsion, using a secondary polymerization technique, and adding of diluents. Acrylic acid, as a diluent in the copolymer matrix, was found to increase the particle size and stability of the resin. IR studies, carried out for the products obtained at various stages, confirmed the conversion of polymer to resin with a hydroxamic acid group and its complex formation with gallium. Both batch and column studies were carried out for the determination of the capacity of the resin with synthetic Bayer's liquor containing gallium and commercial Bayer's liquor. Scaled‐up column studies were carried out with commercial Bayer's liquor to test the cyclability and stability of the resin. It was observed that chelated ion exchange resin could be recycled up to 30 times. The optimal liquid to solid phase ratio was found to be 1:12. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 847–855, 2004     

Mean grain size determination in marbles by ultrasonic velocity techniques

Grain size determinations by various ultrasonic techniques have been considered by several researches. In this paper, we have studied mean grain size determination of some marbles by using ultrasonic velocity measurements. We have represented ultrasonic velocity–grain size size master graph. Using this graph, we have compared mean grain size of marble samples by optic microscope images.     

Boron Trifluoride‐Promoted Indium(III) Triflate‐Catalyzed Sequential One‐Pot Synthesis of (1,2‐Diaryl‐2‐oxoethyl)malonates from trans‐2‐Aryl‐3‐nitrocyclopropane‐1,1‐dicarboxylates and Activated Arenes

A sequential one‐pot synthesis of Michael adducts of aroylmethylidenemalonates with activated aromatics is described. The method involves treatment of trans‐2‐aryl‐3‐nitro‐cyclopropane‐1,1‐dicarboxylates with boron trifluoride etherate to form aroylmethylidenemalonates in situ and then addition of activated aromatics such as indoles, carbazole, pyrrole, thiophenes, methoxybenzenes and benzodioxole followed by a catalytic amount of indium(III) triflate to the same reaction vessel. To prove the synthetic potential of the resulting Michael adducts, one of the adducts was transformed into a pharmaceutically interesting dihydropyridazinone derivative.

     

Extended fuzzy function model with stable learning methods for online system identification

The aim of the online nonlinear system identification is the accurate modeling of the current local input‐output behavior of the plant without using any prior knowledge and offline modeling phase. It is a challenging task for many intelligent systems when used for real‐time control applications. In this paper, we propose a novel computationally efficient extended fuzzy functions (EFF) model for system identification of unknown nonlinear discrete‐time systems. The main contributions are to introduce an effective quasi‐nonlinear model (EFF) and propose adaptive learning rates (ALR) for recursive least squares (RLS) and gradient‐descent (GD) methods. The asymptotic convergence of the modeling errors and boundedness of the parameters are proved by using the input‐to‐state stability (ISS) approach. Numerical simulations are performed for Box–Jenkins gas furnace system and a nonlinear dynamic system. The benefits of its accuracy, stability and simple implementation in practice indicate that EFF model is a promising technique for online identification of nonlinear systems. Copyright © 2010 John Wiley & Sons, Ltd.