many procedures suggest for reduction of responses of riser to vortex induced vibrations (viv). natural frequencies of marine risers is an important parameter that can affect the responses of riser to viv. change of riser properties such as top tension and bending stiffness can alter natural frequencies. in this study effects of riser specifications on the responses and fatigue damage of marine...

For the use of the mains networks as high speed data path for Internet, voice and data services carrier frequencies within the range from 500 kHz up to 20 MHz must be considered. The development of suitable communication systems and the planning of power line communication networks requires measurement-based models of the transfer characteristics of the mains network in the abovementioned frequ...

In this paper, we compare and analyze six different path loss models (i.e. FSPL model, COST 231 Hata model, ECC-33 model, SUI model, Ericsson model and COST 231 Walfish-Ikegami model) in different receiver antenna heights in urban, suburban and rural environments in NLOS condition for WiMAX. We consider Bangladesh as three regions such: Urban, Suburban, flat area and use operating frequency 2.5...

This paper presents an experimental characterization of millimeter-wave (mm-wave) channels in the 6.5 GHz, 10.5 GHz, 15 GHz, 19 GHz, 28 GHz and 38 GHz frequency bands in an indoor corridor environment. More than 4,000 power delay profiles were measured across the bands using an omnidirectional transmitter antenna and a highly directional horn receiver antenna for both co- and cross-polarized an...

This paper addresses a path loss prediction and optimization by means of Lee’s model for Jiza town, south of Amman city, Jordan. Data were collected from mobile companies in Jordan in the frequency band of 900, and 1800 MHz. The calibrated Lee’s, Hata, and Egli’s path loss models were compared with respect to the original collected data. It is found that for the 900 MHz Lee’s prediction model h...

In an environment such as underwater channel where placing test equipments are difficult to handle, it is much practical to have hardware simulators to examine suitably designed transceivers (transmitter/receiver). The simulators of this kind will then allow researchers to observe their intentions and carry out repetitive tests to find suitable digital coding/decoding algorithms. In this p...

The Hubbard model is used to study an electronic system at half filling. Starting from a functional integral representation the spinup Grassmann field is integrated out. It is shown that the resulting spinless fermion theory has an instantaneous cluster interaction, and that the spinless fermions are coupled to thermally fluctuating Ising spins. The coupling parameter of the spinless fermion in...

This paper discusses the possibility of deploying a shortrange cognitive radio (secondary communication system) within the service area of a primary system. Although the secondary system interferes with the primary system, there are certain locations in the service area of the primary system where the cognitive radio can reuse the frequency of the primary system without causing harmful interfer...