S ound has been largely ignored or dismissed in digital communications. Given that computer systems have been traditionally aimed at long-distance and high-bit-rate communications, this dismissal is understandable. The data rates for sound are relatively low compared to media such as radio, and the sounds can be annoying. Designers of most current digital communication systems assume applicatio...

In recent years geographers have started to re-engage with issues of exclusion, social justice and moral philosophy, Ž rst explored by radical geographers in the 1970s. This re-engagement parallels the rapid growth in the 1990s of feminist and critical geographies. Geographers within these traditions have focused their attention on the intersection of issues such as identity, difference and spa...

The vision of safer transportation is strongly driven by the introduction of Vehicular Safety Communications (VSC) to enable new cooperative safety applications. In highly dense traffic scenarios, however, the current Dedicated Short Range Communications (DSRC) technology is expected to face serious performance problems due to simultaneous transmissions making packets to collide with each other...

ultra-wideband (uwb) radio is a promising technology for low-cost, high-rate communications at short ranges. however, high bandwidth and low power of the uwb signals impose some difficult challenges in signal processing and implementation of the receiver. acquisition of the signal timing is the first task to be performed in a coherent receiver. the high bandwidth of uwb signals demand for fine ...

During a recent long-range acoustic communication experiment carried out in deep water, multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) communication signals were transmitted with a 50 Hz bandwidth (225-275 Hz) at various source-receiver ranges from 100 to 700 km. The experiment consisted of two mobile components: (1) a source towed slowly at a speed of 2-3 knots at ∼75 m depth ...

through the history and since 1933, the iranian rial has declined from 11.2 rials per dollar to almost 8600 rials per dollar today in the parallel or black market. at the same time the official rate has been kept at artificial level most of the time, not consistent with other macro conditions of the country. historically, however, the central bank has adjusted the official rate and brought it i...