A Fourier domain technique has been proposed previously which, in principle, quanti®es the extent to which multipoint in-situ measurements can identify whether or not an observed structure is time stationary in its rest frame. Once a structure, sampled for example by four spacecraft, is shown to be quasistationary in its rest frame, the structure's velocity vector can be determined with respect...

A discrete representation of the reconstruction process, consistent with the method of data collection, has been used to derive expressions for the noise power spectrum, autocorrelation function and noise equivalent quanta (NEQ) of a computed tomography (CT) image. These parameters have been expressed in terms of basic scanning factors such as tube current, exposure time, slice width and number...

One of the parameters of the pulsed RADAR that contributes range capability is the average power of the transmitter. The average power can be increased by increasing the peak power or transmitted pulse width or both. The complexity in the design of transmitter components to withstand high peak power is the most challenging task. On the other hand larger transmitted pulse width affects the RADAR...

Studies on Performance of Pulse Shaped OFDM Signal Written by Administrator Wednesday, 16 March 2011 08:55 Last Updated Monday, 21 March 2011 07:29 The Orthogonal Frequency Division Multiplexing (OFDM) transmission system is one of the optimum versions of the multi-carrier transmission scheme. The OFDM is referred in the literature as Multi-carrier, Multi-tone and Fourier Transform based modula...

The fast Fourier transform (FFT), which is employed by all commercially available ultrasonic systems, provides a time-frequency representation of Doppler ultrasonic signals obtained from blood flow. The FFT assumes that the signal is stationary within the analysis window. However, the presence of short duration embolic signals invalidates this assumption. For optimal detection of embolic signal...

In this article, Professor Howard Chang addresses the role of trade restric­ tions in supporting policies to protect the global environment and proposes a more liberal treatment of these environmental trade measures than that adopted by dispute-settlement panels of the General Agreement on Tariffs and Trade (GATT). The GATT Secretariat has recommended that countries like the United States rely ...

Multitaper spectral analysis using sinusoidal taper has been carried out on the backscattered signals received from the troposphere and lower stratosphere by the Gadanki Mesosphere-Stratosphere-Troposphere (MST) radar under various conditions of the signal-to-noise ratio. Comparison of study is made with sinusoidal taper of the order of three and single tapers of Hanning and rectangular tapers,...

Studies on Performance of Pulse Shaped OFDM Signal Written by Administrator Wednesday, 16 March 2011 08:55 Last Updated Monday, 21 March 2011 07:29 The Orthogonal Frequency Division Multiplexing (OFDM) transmission system is one of the optimum versions of the multi-carrier transmission scheme. The OFDM is referred in the literature as Multi-carrier, Multi-tone and Fourier Transform based modula...

Analytical expressions are demonstrated for fast calculations of time-harmonic and transient near-field pressures generated by triangular pistons. These fast expressions remove singularities from the impulse response, thereby reducing the computation time and the peak numerical error with a general formula that describes the near-field pressure produced by any triangular piston geometry. The ti...