A new technique for the numerical simulation of periodic structures including EBGs, FSSs and Metamaterials

Author(s):  
Raj Mittra ◽  
Kyungho Yoo
Author(s):  
Yoshitaka Yamashita ◽  
Mitsuru Ikeda

This paper proposes a new technique to improve the current collection performance of pantographs. For this purpose, the pan springs, which are usually coil springs, are replaced with variable stiffness devices. The device described in this paper is comprised of two air springs facing each other. This paper firstly outlines the method for the improvement for current collection performance and exhibits some numerical simulation results, which supports the efficacy of the method. It then presents the prototype of the variable stiffness device and shows its basic characteristics. Finally, it shows the experimental results of the dynamic characteristics control of a pantograph using the variable stiffness devices.


Author(s):  
Prigiarto Hokkal Yonatan ◽  
Filip Van den Abeele ◽  
Jean-Christophe Ballard

Designing the cover height of buried pipelines to prevent them from buckling requires a method that can thoroughly and realistically model the phenomenon. This paper introduces a new technique to assess the risk of upheaval buckling (UHB) by using backfill soil springs (BFSS) to represent the uplift resistance provided by the backfill soil on top of a buried pipeline. This paper investigates the pre-buckling pipeline behavior related to UHB and highlights some of the key parameters governing the analysis. UHB assessment based on a case study was carried out and the results were then compared with those obtained from force-equilibrium methods generally used in the industry. The comparison shows that UHB assessment can be performed more rigorous using BFSS than using force-equilibrium methods. Therefore, using BFSS for UHB assessment improve the reliability in cover height design.


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