Dynamic source aggregation of subwavelength connections in elastic optical networks

Elastic optical network technologies arise as promising solutions for future high-speed optical transmission, since they can provide superior flexibility and scalability in spectrum allocation toward the seamless support of diverse services along with the rapid growth of Internet traffic. In elastic optical networks, heterogeneous traffic demands are typically supported by a single type of bandwidth-variable transmitters, which is not always spectrum and cost-efficient. In light of this, the aggregation of same source but different destination subwavelength connections has been recently introduced for elastic optical networks, aiming to obtain both transmitter and spectrum usage savings. In this paper, we propose a novel algorithm for dynamic source aggregation of connections. Moreover, we introduce a novel node architecture enabling the realization of the proposed source aggregation in a cost-effective way. The obtained results demonstrate considerable improvement in the network spectrum utilization, as well as a significant reduction in the number of necessary transmitters per node.     

Generalized uncertainty principle and the Ramsauer-Townsend effect

The scattering cross-section of electrons in noble gas atoms exhibits a minimum value at electron energies of approximately 1 eV. This is the Ramsauer-Townsend effect. In this letter, we study the Ramsauer-Townsend effect in the framework of the Generalized Uncertainty Principle.     

In Silico Evaluation of Hexamethylene Amiloride Derivatives as Potential Luminal Inhibitors of SARS-CoV-2 E Protein

The coronavirus E proteins are small membrane proteins found in the virus envelope of alpha and beta coronaviruses that have a high degree of overlap in their biochemical and functional properties despite minor sequence variations. The SARS-CoV-2 E is a 75-amino acid transmembrane protein capable of acting as an ion channel when assembled in a pentameric fashion. Various studies have found that hexamethylene amiloride (HMA) can inhibit the ion channel activity of the E protein in bilayers and also inhibit viral replication in cultured cells. Here, we use the available structural data in conjunction with homology modelling to build a comprehensive model of the E protein to assess potential binding sites and molecular interactions of HMA derivatives. Furthermore, we employed an iterative cycle of molecular modelling, extensive docking simulations, molecular dynamics and leveraging steered molecular dynamics to better understand the pore characteristics and quantify the affinity of the bound ligands. Results from this work highlight the potential of acylguanidines as blockers of the E protein and guide the development of subsequent small molecule inhibitors.     

Adaptive yaw stability control by coordination of active steering and braking with an optimized lower-level controller

In this article, an integrated multiinput multioutput model reference adaptive control algorithm is presented based on active front steering and effective direct yaw moment distribution as an advanced driver assistance system. Vehicle parameter uncertainties in mass and tire-road friction coefficient are considered through adaptation laws at the upper level in the control structure. The efficient distribution of yaw moment on the rear wheels is performed via a constrained optimization at the lower control level. Control commands are executed by additive steering angle on front wheels and brake torque applied on one of the rear wheels. Simulation results for different lateral maneuvers are employed for the evaluation of the proposed adaptive control method. The performance of the integrated control algorithm to enhance vehicle handling and stability is shown on various road conditions.     

Energy and exergy analyses of hydrogen production via solar-boosted ocean thermal energy conversion and PEM electrolysis

Energy and exergy analyses are reported of hydrogen production via an ocean thermal energy conversion (OTEC) system coupled with a solar-enhanced proton exchange membrane (PEM) electrolyzer. This system is composed of a turbine, an evaporator, a condenser, a pump, a solar collector and a PEM electrolyzer. Electricity is generated in the turbine, which is used by the PEM electrolyzer to produce hydrogen. A simulation program using Matlab software is developed to model the PEM electrolyzer and OTEC system. The simulation model for the PEM electrolyzer used in this study is validated with experimental data from the literature. The amount of hydrogen produced, the exergy destruction of each component and the overall system, and the exergy efficiency of the system are calculated. To better understand the effect of various parameters on system performance, a parametric analysis is carried out. The energy and exergy efficiencies of the integrated OTEC system are 3.6% and 22.7% respectively, and the exergy efficiency of the PEM electrolyzer is about 56.5% while the amount of hydrogen produced by it is 1.2 kg/h.     

Prescribed performance adaptive fuzzy dynamic surface control of nonaffine time‐varying delayed systems with unknown control directions and dead‐zone input

In this paper, an adaptive prescribed performance control method is presented for a class of uncertain strict feedback nonaffine nonlinear systems with the coupling effect of time‐varying delays, dead‐zone input, and unknown control directions. Owing to the universal approximation property, fuzzy logic systems are used to approximate the uncertain terms in the system. Since there is no systematic approach to determine the required upper bounds of errors in control systems, the prior selection of control parameters to have a satisfactory performance is somehow impossible. Therefore, the prescribed performance technique as a solution is applied in this study to bring satisfactory performance indices to the system such as overshoot and steady state performance within a predetermined bound. Dynamic surface control strategy is also introduced to the proposed control scheme to address the “explosion of complexity” behavior existing in conventional backstepping methods. To ease the control design, the mean‐value theorem is utilized to transform the nonaffine system into the affine one. Moreover, with the help of this theorem, the unknown dead‐zone nonlinearity is separated into the linear and nonlinear disturbance‐like bounded term. The proposed method relaxes a prior knowledge of control direction by employing Nussbaum‐type functions, and the effect of time‐varying delays are compensated by constructing the proper Lyapunov‐Krasovskii functions. The proposed controller guarantees that all the closed‐loop signals are semiglobally uniformly ultimately bounded and the error evolves within the decaying prescribed bounds. In the end, in order to demonstrate the superiority of this method, simulation examples are given.     

Performance evaluation of a continuous flow Photo-Impinging Streams Cyclone Reactor for phenol degradation

In this study, an impinging streams cyclone reactor has been utilized as a novel apparatus in photocatalytic degradation of phenol. Degussa P25 TiO₂ nano particles have been applied as the photocatalyst under UV radiation. The operating parameters including catalyst loading, pH, initial phenol concentration and light Intensity have been found to affect the efficiency of the photocatalytic degradation process within this photoreactor. Photocatalytic degradation of phenol has been also investigated in a continuous flow impinging streams system. The results have shown a higher efficiency and an increased performance capability of the present reactor in comparison with the conventional processes.     

Primary service outage and secondary service performance in cognitive radio networks

In this work, we have used stochastic geometry to analyze the effects of the radio environment and the secondary service sensing error on the primary service outage probability. We have also obtained a closed form expression for the primary service outage probability in a Rayleigh fading channel. Furthermore, an approximation was formulated for a general fading channel. The results obtained were used to drive an expression for the secondary service successful transmission density. Finally, we formulated an optimization problem to achieve highest density of secondary service successful transmissions while keeping the primary service outage probability in check by adjusting sensing error and secondary service node density to their optimal values. Copyright © 2014 John Wiley & Sons, Ltd.