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The apprehension of the last three factors of the Drake equation, fi · fc · L, is misguided or at least not very well examined. This article scrutinizes the underlying suppositions involved in the search for extraterrestrial intelligence (SETI) research. What is meant by “intelligence,” “technology,” and “civilization”? What makes them possible, and how do they evolve? The present examination aims

In this work, we propose a method for determining an optimal, non-uniform, sampling scheme for multi-dimensional signals by solving a convex optimization problem reminiscent of the sensor selection problem. The optimal sampling scheme is determined given a suitable estimation bound on the parameters of interest, as well as incorporating any imprecise a priori knowledge of the locations of the para

This work proposes a frequency and amplitude estimator tailored for noise corrupted signals that have been clipped. Formulated as a sparse reconstruction problem, the proposed algorithm estimates the signal parameters by solving an atomic norm minimization problem. The estimator also exploits the waveform information provided by the clipped samples, incorporated in the form of linear constraints t

In this work, we propose a method for determining a non-uniform sampling scheme for multi-dimensional signals by solving a convex optimization problem reminiscent of the sensor selection problem. The resulting sampling scheme minimizes the sum of the Cramér–Rao lower bounds for the parameters of interest, given a desired number of sampling points. The proposed framework allows for selecting an arb

We consider channel estimation (CE) in narrowband Internet-of-Things (NB-IoT) systems. Due to the fluctuations in phase within receiver and transmitter oscillators, and also the residual frequency offset (FO) caused by discontinuous receiving of repetition coded transmit data-blocks, random phase noises are presented in received signals. Although the coherent-time of fading channel can be assumed

Channel measurements of large-scale multiuser multiple-input multiple-output (MU-MIMO) radio propagation channels are presented. In the setup, three users with patch antennas communicate simultaneously with a base station (BS) equipped with a large antenna array in an indoor environment. Both a uniform linear array (ULA) and a uniform planar array (UPA) are used, and their relative ability to sepa

The effects of five different calcium antagonists (diltiazem, felodipine, nifedipine, nimodipine, and verapamil) on cat skeletal muscle resistance and capacitance vessels were studied in a whole organ preparation. These calcium antagonists seemed to have the similar qualitative effects on these vascular functions. Calcium antagonists were found to be potent inhibitors of myogenic vascular reactivi

As the demand for connectivity and infotainment services increases in the automotive world, the need to measure and characterize the propagation channels inside vehicles also increases. In this work, a measurement study was performed to investigate the influence of RF cables on in-vehicle channels. It was found that, for the same transmit and receive antenna positions, the routing of the measureme