Bank M.,Holon Institute of Technology |
Tapuchi S.,Sami Shamoon |
Haridim M.,Holon Institute of Technology |
Bank M.,Hebrew University of Jerusalem |
And 2 more authors.
10th WSEAS International Conference on EHAC'11 and ISPRA'11, 3rd WSEAS Int. Conf. on Nanotechnology, Nanotechnology'11, 6th WSEAS Int. Conf. on ICOAA'11, 2nd WSEAS Int.Conf. on IPLAFUN'11 | Year: 2011
In this paper we investigate the performances of the Orthogonal Frequency Division Multiple Access (OFDMA) and Frequency Bank Signal (FBS) methods over High Altitude Platforms ( HAPs) systems with different Doppler scales. FBS is an enhanced OFDMA technique, which is capable to eliminate the negative effects of Doppler shifts even in extreme cases, such as non-uniform Doppler shifts across the OFDMA subcarriers. Our simulations show that HAP- OFDMA systems can work if frequency shift due to Doppler Effects is smaller than 2% of carrier frequencies separation. These conditions correspond to the frequency band of 2GHz and train velocity 120 km/h. FBS method allows increasing the permissible Doppler shift up to 6 - 8 %, hence enabling higher carrier frequency bands and higher speed vehicles.
Cunliffe and Ness | Date: 2014-10-08
A bone fixation device comprising first and second screw receiving members, each member having an aperture extending therethrough for receiving a screw; and a plastically deformable connecting arm extending between the screw receiving members along a long axis defined by the first and second screw receiving members; the arm being adapted to be more pliable than the screw receiving members such that (a) on twisting the device about its long axis the arm twists before the screw receiving members deform; and (b) on bending the device along its long axis the arm bends before the screw receiving members deform.