955 resultados para Radio detectors
Resumo:
Tony Mann reviews Robin Wilson's appearance as Michael Berkeley's guest on Private Passions. Broadcast on BBC Radio 3, on 9 September 2007.
Radio propagation modeling for capacity optimization in wireless relay MIMO systems with partial CSI
Resumo:
The enormous growth of wireless communication systems makes it important to evaluate the capacity of such channels. Multiple Input Multiple Output (MIMO) wireless communication systems are shown to yield significant performance improvement to data rates when compared to the traditional Single Input Single Output (SISO) wireless systems. The benefits of multiple antenna elements at the transmitter and receiver have become necessary to the research and the development of the next generation of mobile communication systems. In this paper we propose the use of Relaying MIMO wireless communication systems for use over long throughput. We investigate how Relays can be used in a "demodulate-and-forward" operation when the transmitter is equipped with spatially correlated multiple antenna elements and the receiver has only partial knowledge of the statistics of the channel. We show that Relays between the source and destination nodes of a wireless communication system in MIMO configuration improve the throughput of the system when compared to the typical MIMO systems, or achieve the desired channel capacity with significantly lower power resources needed.
Resumo:
Radio advertising is suffering from a remarkable crisis of creativity as it has yet not found its role in a radio model based on voice locution and information genres. This article suggests the need for implementing a peripheral or heuristic strategy to attract and hold listeners’ attention. Within this framework, the narration and scene representation are proposed as suitable persuasion techniques. The objective is to design a useful conceptual tool for an efficient creative conception of narration at the service of certain commercial strategy. First, the concept of narrative persuasion is grounded according to the possibilities of the sound code. Second, the keys of scene representation and commercial strategy (brand, product, advantage, benefit and target) within the sound message are presented. And third, these keys are articulated in a model. This model is pre-tested by means of analyzing eight different case-radio ads.
Resumo:
Social networks have increasingly become a showcase where the media can be promoted. Like many other media, radio stations have made use of social networks to promote themselves in a better way and, sometimes, to keep more feedback with their listeners. But not all programs make the same use and not all of them have managed to reach in the same way his followers. This article discusses the consolidation in the social networks of the major radio sports programs in Spain. Through a comparative analysis between 2010 and 2015, throughout the text, the authors have tried to observe the evolution of the programs and, at the same time, to establish comparisons between the followers that these programs have on social networks and the number of listeners as EGM.
Resumo:
The work analyse from a journalistic point of view the history radio divulgation of health during the Second Republic and the start of the Franco era. For it, printed sources of the health broadcast conferences have been analysed. The most frequently used radio genre was a combination of informative monologue and monologue opinion. Questions relating to maternal-juvenile health were the most disseminated. In general, the radio language employed responded to the needs for clarity, as well as adapting the message to the target audience. With Francoism, the political slogans were incorporated and the gender discussions were given more importance.
Resumo:
The processing of motion information by the visual system can be decomposed into two general stages; point-by-point local motion extraction, followed by global motion extraction through the pooling of the local motion signals. The direction aftereVect (DAE) is a well known phenomenon in which prior adaptation to a unidirectional moving pattern results in an exaggerated perceived direction diVerence between the adapted direction and a subsequently viewed stimulus moving in a diVerent direction. The experiments in this paper sought to identify where the adaptation underlying the DAE occurs within the motion processing hierarchy. We found that the DAE exhibits interocular transfer, thus demonstrating that the underlying adapted neural mechanisms are binocularly driven and must, therefore, reside in the visual cortex. The remaining experiments measured the speed tuning of the DAE, and used the derived function to test a number of local and global models of the phenomenon. Our data provide compelling evidence that the DAE is driven by the adaptation of motion-sensitive neurons at the local-processing stage of motion encoding. This is in contrast to earlier research showing that direction repulsion, which can be viewed as a simultaneous presentation counterpart to the DAE, is a global motion process. This leads us to conclude that the DAE and direction repulsion reflect interactions between motion-sensitive neural mechanisms at different levels of the motion-processing hierarchy.
Atomic oxygen surface loss coefficient measurements in a capacitive/inductive radio-frequency plasma
Resumo:
Spatially resolved measurements of the atomic oxygen densities close to a sample surface in a dual mode (capacitive/inductive) rf plasma are used to measure the atomic oxygen surface loss coefficient beta on stainless steel and aluminum substrates, silicon and silicon dioxide wafers, and on polypropylene samples. beta is found to be particularly sensitive to the gas pressure for both operating modes. It is concluded that this is due to the effect of changing atom and ion flux to the surface. (C) 2002 American Institute of Physics.
Resumo:
The interaction between supernova ejecta and circumstellar matter, arising from previous episodes of mass loss, provides us with a means of constraining the progenitors of supernovae. Radio observations of a number of supernovae show quasi-periodic deviations from a strict power-law decline at late times. Although several possibilities have been put forward to explain these modulations, no single explanation has proven to be entirely satisfactory. Here we suggest that Luminous blue variables undergoing S-Doradus type variations give rise to enhanced phases of mass loss that are imprinted on the immediate environment of the exploding star as a series of density enhancements. The variations in mass loss arise from changes in the ionization balance of Fe, the dominant ion that drives the wind. With this idea, we find that both the recurrence timescale of the variability and the amplitude of the modulations are in line with the observations. Our scenario thus provides a natural, single-star explanation for the observed behaviour that is, in fact, expected on theoretical grounds.
Resumo:
An industrial, confined, dual frequency, capacitively coupled, radio-frequency plasma etch reactor Exelan®, Lam Research has been modified for spatially resolved optical measurements. Space and phase resolved optical emission spectroscopy yields insight into the dynamics of the discharge. A strong coupling of the two frequencies is observed in the emission profiles. Consequently, the ionization dynamics, probed through excitation, is determined by both frequencies. The control of plasma density by the high frequency is, therefore, also influenced by the low frequency. Hence, separate control of plasma density and ion energy is rather complex.
Resumo:
This letter reports the statistical characterization and modeling of the indoor radio channel for a mobile wireless personal area network operating at 868 MHz. Line of sight (LOS) and non-LOS conditions were considered for three environments: anechoic chamber, open office area and hallway. Overall, the Nakagami-m cdf best described fading for bodyworn operation in 60% of all measured channels in anechoic chamber and open office area environments. The Nakagami distribution was also found to provide a good description of Rician distributed channels which predominated in the hallway. Multipath played an important role in channel statistics with the mean recorded m value being reduced from 7.8 in the anechoic chamber to 1.3 in both the open office area and hallway.
Resumo:
The dynamics of high energetic electrons (>= 11.7 eV) in a modified industrial confined dual-frequency capacitively coupled RF discharge (Exelan, Lam Research Inc.), operated at 1.937 MHz and 27.118 MHz, is investigated by means of phase resolved optical emission spectroscopy. Operating in a He-O-2. plasma with small rare gas admixtures the emission is measured, with one-dimensional spatial resolution along the discharge axis. Both the low and high frequency RF cycle are resolved. The diagnostic is based on time dependent measurements of the population densities of specifically chosen excited rare gas states. A time dependent model, based on rate equations, describes the dynamics of the population densities of these levels. Based on this model and the comparison of the excitation of various rare gas states, with different excitation thresholds, time and space resolved electron temperature, propagation velocity and qualitative electron density as well as electron energy distribution functions are determined. This information leads to a better understanding of the dual-frequency sheath dynamics and shows, that separate control of ion energy and electron density is limited.
Resumo:
A planar inductively coupled radio-frequency (rf) magnetic neutral loop discharge has been designed. It provides diagnostic access to both the main plasma production region as well as a remote plane for applications. Three coaxial coils are arranged to generate a specially designed inhomogeneous magnetic field structure with vanishing field along a ring in the discharge-the so-called neutral loop (NL). The plasma is generated by applying an oscillating rf electric field along the NL, induced through a four-turn, planar antenna operated at 13.56 MHz. Electron density and temperature measurements are performed under various parameter variations. Collisionless electron heating in the NL region allows plasma operation at comparatively low pressures, down to 10(-2) Pa, with a degree of ionization in the order of several per cent. Conventional plasma operation in inductive mode without applying the magnetic field is less efficient, in particular in the low pressure regime where the plasma cannot be sustained without magnetic fields.