Optimization of loss and gain multilayers for reducing the scattering of a perfect conducting cylinder

Reduction of electromagnetic scattering from a conducting cylinder could be achieved by covering it with optimized multilayers of normal dielectric and plasmonic material. The plasmonic material with intrinsic losses could degrade the cloaking effect. Using a genetic algorithm, we present the optimized design of loss and gain multilayers for reduction of the scattering from a perfect conducting cylinder. This multilayered structure is theoretically and numerically analyzed when the plasmonic material with low loss and high loss respectively is considered. We demonstrate by full-wave simulation that the optimized nonmagnetic gain-loss design can greatly compensate the decreased cloaking effect caused by loss material,which facilitates the realization of practical electromagnetic cloaking, especially in the optical range.

A Novel Multi-Hop Algorithm for Wireless Network with Unevenly Distributed Nodes

Node location estimation is not only the promise of the wireless network for target recognition,monitoring,tracking and many other applications,but also one of the hot topics in wireless network research.In this paper,the localization algorithm for wireless network with unevenly distributed nodes is discussed,and a novel multi-hop localization algorithm based on Elastic Net is proposed.The proposed approach is formulated as a regression problem,which is solved by Elastic Net.Unlike other previous localization approaches,the proposed approach overcomes the shortcomings of traditional approaches assume that nodes are distributed in regular areas without holes or obstacles,therefore has a strong adaptability to the complex deployment environment.The proposed approach consists of three steps:the data collection step,mapping model building step,and location estimation step.In the data collection step,training information among anchor nodes of the given network is collected.In mapping model building step,the mapping model among the hop-counts and the Euclidean distances between anchor nodes is constructed using Elastic Net.In location estimation step,each normal node finds its exact location in a distributed manner.Realistic scenario experiments and simulation experiments do exhibit the excellent and robust location estimation performance.

Multi–physical-field characteristics modeling and structure optimization for kW-level ultra-high-speed PM motors with integrated support system

In the aerospace industry,the low-mass ultra-high-speed flywheel system play a critical role.In this paper,a kW-level Ultra-High Speed Permanent Magnet Synchronous Motor(UHSPMSM)as the core component of flywheel system is proposed and analyzed with consideration of multiple physical fields,including electromagnetic characteristics,mechanical strength and rotor dynamics.The integrated support structure is put forward to improve rotation accuracy and operation stability of the UHSPMSM.Further,influence of the integrated support structure on critical speed is explored,and the key parameters such as support position and support stiffness are designed.Moreover,the rotor strength is analyzed by analytical model developed of rotor stress that can deal with multiple boundary types.Material and thickness of the sleeve are optimized,and range of interference value is accurately limited based on four extreme operating conditions.The 3-D Finite Element Model(FEM)is used to validate the strength characteristics and stress distribu-tion of rotor.A 1.5 kW-150000 r/min UHSPMSM with integrated support system is manufactured and tested.The feasibility of UHSPMSM proposed and the accuracy of analysis method are verified through electromagnetic,temperature rise and vibration characteristics test.The machine prototype realizes the load operation at rated speed and the multi-physical-field characteristics achieve the design specification.