8 resultados para power lines

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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Ground vehicle tests have been performed to evaluate the performance of a Passive Millimeter Wave (PMMW) imager in reduced visibility conditions and in particular, the ability to detect power lines and cables. A PMMW imager was
compared with Long Wave Infrared (LWIR) and visible imaging cameras. The three sensors were mounted on a Land Rover, together with GPS and digital recording system. All three sensors plus the GPS data were recorded simultaneously in order to provide direct comparisons. The vehicle collected imagery from a number of sites in the vicinity of Malvern, UK, in January, 2008. Imagery was collected both while the vehicle was stationary at specific sites
and while it was moving. Weather conditions during the data collection included clear, drizzle, rain and fog. Imagery was collected during the day, at night, and during dusk/dawn transition periods. The PMMW imager was a prototype which operated at 94 GHz and was based on a conically scanned folded Schmidt camera and the LWIR and visible sensors were commercial off the shelf items.

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In this article we propose a technique for dual-band Class-E power amplifier design using composite right/left-handed transmission lines, CRLH TLs. Design equations are presented and design procedures are elaborated. Because of the nonlinear phase dispersion characteristic of CRLH TLs, the single previous attempt at applying this method to dual bond Class-E amplifier design was not sufficient to simultaneously satisfy, the minimum requirement of Class-E impedances at both the fundamental and the second harmonic frequencies. This article rectifies this situation. A design example illustrating the synthesis procedure for a 0.5W-5V dual band Class-E amplifier circuit simultaneously operated at 900 MHz and 2.4 GHz is given and compared with ADS simulation.

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This article is concerned with resituating the state at the centre of the analytical stage and, concomitantly, with drawing attention to the dangers of losing sight of the state as a locus of power. It seeks to uncover the relationship between two related lines of critical inquiry: Marxist and Foucauldian theories of the state; and the attempts by three postwar American novelist (Ken Kesey, William Burroughs and E.L. Doctorow) to determine the nature and extent of this power and to consider under what conditions political struggle might be possible. It argues that such a move is needed because recent critical analysis has been too preoccupied by corporeal micropolitics and global macropolitics, and that the postwar American novel can help us in this move because it is centrally concerned with the repressive potentiality of the US state. It maintains that the resuscitation of Marxist state theories in early 1970s and a debate between Poulantzas and Foucault is intriguingly foreshadowed and even critiqued by these novels. Consequently, it concludes that these novels constitute an unrecognized pre-history of what would become one of the key intellectual debates of the late twentieth century: an engagement between Marxist and post-structuralist conceptions of the power and resistance.

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The role of optical FeIII absorption lines in B-type stars as iron abundance diagnostics is considered. To date, ultraviolet Fe lines have been widely used in B-type stars, although line blending can severely hinder their diagnostic power. Using optical spectra, covering a wavelength range ~3560-9200Å, a sample of Galactic B-type main-sequence and supergiant stars of spectral types B0.5 to B7 are investigated. A comparison of the observed FeIII spectra of supergiants, and those predicted from the model atmosphere codes TLUSTY [plane-parallel, non-local thermodynamic equilibrium (LTE)], with spectra generated using SYNSPEC (LTE), and CMFGEN (spherical, non-LTE), reveal that non-LTE effects appear small. In addition, a sample of main-sequence and supergiant objects, observed with the Fiber-fed Extended Range Optical Spectrograph (FEROS), reveal LTE abundance estimates consistent with the Galactic environment and previous optical studies. Based on the present study, we list a number of FeIII transitions which we recommend for estimating the iron abundance from early B-type stellar spectra.

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This paper addresses the theoretical aspects of passive intermodulation (PIM) generation in printed transmission lines. In order to elucidate the mechanisms of PIM generation, a new model of the transmission line length with distributed nonlinearity is proposed. The developed model has been validated by the near-field measurements of PIM product distributions along the microstrip lines. The contributions of nonlinear mixing, power dissipation, and load matching to PIM products have been analyzed in detail. The obtained results reveal the fundamental properties of PIM generation in finite lengths of printed lines with distributed non-linearity and identify possible means for PIM mitigation. It was shown for the first time that the reverse PIM products in a matched transmission line with distributed nonlinearity are generated due to nonlinear scattering. © 2008 IEEE.

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Looking at one site, the Israeli checkpoints in the occupied Palestinian territory, this article seeks to understand the mechanisms by which violence can present itself as justifiable (or justified), even when it materializes within frames presumably set to annul it. We look at the checkpoints as a condensed microcosmos operating within two such frames. One is the prolonged IsraeliPalestinian ‘peace process’ (the checkpoints became a primary technology of control in the period following the beginning of the peace process), and the other is regulatory power (disciplinary and biopower), which in the Foucauldian framework presumably sidelines the violent form which sovereign power takes. We argue that the checkpoints, which dissect the Palestinian occupied territories into dozens of enclaves and which are one of the most effective and destructive means of control within the current stage of occupation, can be seen as more than obstacles in the way of Palestinian movement; we suggest that they also function as corrective technologies that are meant to fail. It is with this failure that violence can appear as justified. In order to show the operation of this embedded failure, we examine one mechanism operating within the checkpoints: ‘the imaginary line’. The imaginary line is both a component within, and an emblem of a mode of control that constantly undoes itself in order to summon violence. Since it is never visibly marked in the physical space, the imaginary line is bound to be unintentionally crossed, thereby randomly rendering Palestinians as ‘transgressors’ of the rule and thus facilitating eruptions of violence by the soldiers stationed at the checkpoints. This article proposes an analysis of this hidden demarcation of space in order to question the different relations between subjects and power which it both assumes and constitutes.

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This paper presents the design and implementation of a differential 4-way power-combining amplifier operating at E-band. The proposed 4-way power combiner (4WPC) facilitates short interconnects to the PA cells, thereby resulting in reduced loss. Simple C-L-C and L-C networks are deployed in order to compensate inductive loading due to the routing lines that would otherwise introduce mismatch and subsequently increase overall loss. Realized in SiGe technology, the PA prototype delivered 13.2 dBm output-referred 1-dB compression point and 14.3 dBm saturated output power when operated from a single 3.3 V DC supply at 75 GHz.