Anoptimal Method Research Articles

Broadband achromatic metalens for linearly polarized light from 450 to 800 nm.

Metalens is a planar optical component that uses nanostructures with a thickness on the order of the wavelength to manipulate the wavefront of the incident light. A key problem, especially in color imaging and display applications, is the correction of chromatic aberration, which is an inherent effect caused by the dispersion of periodic lattices and resonance modes. However, the current achromatic metalenses either use the PB phase method that is only valid for circularly polarized light or nanostructures with complex cross sections that are difficult to manufacture. Here, we designed a broadband achromatic metalens for linearly polarized light from 450 to 800 nm. Rectangular titanium dioxide nanofins of various lengths and widths were applied to modulate the phase and dispersion of the incident light. The metalens can fulfill three target phases simultaneously by using an optimization method. The designed metalens has a stable focus from 450 to 800 nm with an average focusing efficiency of 64%. It can be potentially applied in microscopes, lithography machines, sensors, and displays.

Modeling of syngas composition obtained from fixed bed gasifiers using Kuhn–Tucker multipliers

This work consists of developing a predictive model (PM) for syngas composition obtained from biomass gasification in fixed bed gasifiers. The PM is composed of three correlations which are made for carbon conversion efficiency, gasification temperature and the correction factor for the equilibrium constant of the water-gas homogeneous reaction. Such correlations were established using results obtained from the application of an optimization method (AOM) that uses Kuhn–Tucker multipliers. Syngas compositions determined through AOM were compared with experimental compositions and those estimated by other models, resulting that the AOM always determines the best estimates with respect to the root mean square error (RMSE). For syngas compositions estimated by AOM, the RMSE interval is [0.21, 4.11]. The PM was validated with six experimental compositions. From the predicted syngas compositions it was found that the ranges for LHV, cold gas efficiency, carbon conversion efficiency and gasification temperature were [4.594, 5.116 MJ/Nm3], [55.74, 68.18%], [74.20, 88.40%] and [749, 918 °C], respectively. Additionally, for the predicted syngas compositions the RMSE interval was determined as [0.68, 2.25]. Therefore, the PM was considered to be effective in estimating syngas compositions.

Decentralized controller gain scheduling using PSO for power system restoration assessment in a two-area interconnected power system

Load Frequency Control (LFC) is one of the most important issues in electrical power system design/operation and is becoming much more significant recently with increasing size, changing structure and complexity in restoration of interconnected power systems. In practice, LFC systems are used with simple Proportional-Integral (PI) or Integral (I) controllers. However, since the PI or I control parameters are usually tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamic performance if the power system is more vulnerable due to various load changing scenarios in multi-area power system. For this reason, in this study the P and I control parameters are tuned based on Particle Swarm Optimization (PSO) algorithm for a better Load-Frequency Control in a Two-Area Two-Unit Thermal Reheat Power System (TATURIPS) with step load perturbation. To exemplify the optimum parameter search PSO is used as it is an optimization method, therefore, even in the uncertainty area of controller parameters, finds the best parameters for controller and obtained controller is an optimal controller. This makes a trade-off between exploration and exploitation of search space to find global optimum in less number of generations. A TATURIPS is taken for the study to illustrate the proposed method. To show effectiveness of proposed method, the performance of optimized PI controller is obtained with several time-domain simulations for various load changes scenarios and is presented. Simulation results emphasis on the better settling time based stability performance of optimized PI controller in the TATURIPS with GT unit when compared with that of the SMES and the conventional system two-unit two-area interconnected power systems.

Optimization of multiple gateway deployment for underwater acoustic sensor networks

This research aims to develop novel technologies to efficiently integrate wireless communication networks and Underwater Acoustic Sensor Networks (UASNs). Surface gateway deployment is one of the key techniques for connecting two networks with different channels. In this work, we propose an optimization method based on the genetic algorithm for surface gateway deployment, design a novel transmission mechanism-simultaneous transmission, and realize two efficient routing algorithms that achieve minimal delay and payload balance among sensor nodes. We further develop an analytic model to study the delay, energy consumption and packet loss ratio of the network. Our simulation results verify the effectiveness of the model, and demonstrate that the technique of multiple gateway deployment and the mechanism of simultaneous transmission can effectively reduce network delay, energy consumption and packet loss rate.

Optimal Acoustic Attenuation of Weakly Compressible MediaPermeated with Air Bubbles

Based on fuzzy logic (FL) and genetic algorithm (GA), we present anoptimization method to obtain the optimal acoustic attenuation of alongitudinal acoustic wave propagating in a weakly compressible mediumpermeated with air bubbles. In the optimization, the parameters of thesize distribution of bubbles in the medium are optimized for providinguniformly high acoustic attenuation in the frequency band of interest.Compared with other traditional optimization methods, the uniqueadvantage of the present method is that it can locate the global optimumquickly and effectively in need of knowing the mathematical modelprecisely. As illustrated by a numerical simulation, the method iseffective and essential in enhancing the acoustic attenuation of such amedium in an optimal manner. The bubbly medium with optimized structuralparameters can effectively attenuate longitudinal waves at intermediatefrequencies with an acoustic attenuation approximating a constant valueof 10(dB/cm). Such bubbly media with optimal acoustic attenuations maybe applied to design acoustic absorbent by controlling broaderattenuation band and higher efficiency.

A Novel Multiaccess Strategy for Multimedia Wireless LANs

The main focus of the research presented in thispaper is to evaluate how efficiently a commoncommunication medium such as broadcast radio can beshared by a large number of network devices in anin-building environment. The goal is to recommend anoptimal method to fulfil the demanding requirementsdictated by broadband multimedia applications operatingin wireless local area networks. To this end, apractical and efficient multiaccess scheme called“reserved polling” is proposed and analyzed.It is shown that the new method is able to handle anintegrated mix of multimedia traffic and operaterobustly in an unreliable wireless transport medium. Ananalytical approach based on queueing theory is employedto gain some insight into the complex behavior of theprotocol. This approach appears to be accurate in predicting its performance for both bursty andperiodic traffic types. The analytical results areverified by network simulation.

ChemInform Abstract: SEARCH FOR AN OPTIMAL METHOD FOR SYNTHESIS OF 2‐METHOXY‐5‐NITROBENZOPHENONE ON A LARGE LABORATORY SCALE

Chemischer InformationsdienstVolume 9, Issue 7 Isocyclic Compounds ChemInform Abstract: SEARCH FOR AN OPTIMAL METHOD FOR SYNTHESIS OF 2-METHOXY-5-NITROBENZOPHENONE ON A LARGE LABORATORY SCALE M. MAKOSZA, M. MAKOSZASearch for more papers by this authorM. JAWDOSIUK, M. JAWDOSIUKSearch for more papers by this authorW. CWIKIEWICZ, W. CWIKIEWICZSearch for more papers by this author M. MAKOSZA, M. MAKOSZASearch for more papers by this authorM. JAWDOSIUK, M. JAWDOSIUKSearch for more papers by this authorW. CWIKIEWICZ, W. CWIKIEWICZSearch for more papers by this author First published: February 14, 1978 https://doi.org/10.1002/chin.197807188Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume9, Issue7February 14, 1978 RelatedInformation