The scattering of sound from the sea surface is important for the operation of underwater sonar and underwater acoustic communications systems. Studies of low to mid-frequency surface reverberation have a long history, but studies of very high frequency (>300 kHz) surface scattering in the literature are rare. The physics of very high frequency (VHF) scattering is expected to be strongly depend...

iran has 1260 km of coastline that borders the persian gulf and the oman sea in the northwest indian ocean. marine algae are one of the natural resources in the marine ecosystem which produce a wide range of new secondary metabolites with various biological activities that play an important role in the pharmaceutical care. in this study the cytotoxic activity of 28 marine algae of chabahar coas...

Caspian Sea with an average depth of 27m is the largest enclosed water body in the world. Despite its enormity and valuable biotic and economic resources, investigations on the biota and seawater properties are mosaic at best. In previous studies, the monitoring of the chlorophyll-a concentrations in the Southern Caspian Sea was organized based on satellite data sets however, vertical dis...

This paper presents NIDA, a Non-Intrusive Disconnection-aware vocal quality assessment Algorithm. NIDA accurately estimates vocal perceived quality over wireless data networks by discriminating the perceptual effect of a single random packet loss, 2-4 consecutive packet losses (burst) stemming from contentions, and discontinuity entailed by transient loss of connectivity. NIDA properly accounts...

Dynamic service level negotiation is necessary to flexibly allocate resources according to QoS demands of a host or a domain. We have designed COPS-SLS as a service level negotiation protocol for IP-based networks. In this paper, we analyse a COPS-SLS-based negotiation system from the protocol design and system’s scalability perspectives. This analysis is useful not only to the improvement of t...

An alternative method for communicating over frequency-selective channels is multi-carrier modulation. In a multi-carrier system, the available bandwidth is divided into many narrow subbands, such that the channel distortion appears as flat (frequency-nonselective) within each subband. Thus, no equalization is needed per subband. Instead, modulation and demodulation have to be performed over mu...

Direct influence over communication media is a potent resource during electoral campaigns, and politicians have an incentive to gain control of the airwaves to advance their careers. In this article, we use data on community radio license applications in Brazil to identify both the causal effect of incumbency on politicians’ ability to control the media and the causal effect of media control on...

Iran has 1260 km of coastline that borders the Persian Gulf and the Oman Sea in the northwest Indian Ocean. Marine algae are one of the natural resources in the marine ecosystem which produce a wide range of new secondary metabolites with various biological activities that play an important role in the pharmaceutical care. In this study the cytotoxic activity of 28 marine algae of Chabahar coas...