Single-mode behaviour judgment of optical waveguides by imaginary-distance beam propagation method under perfectly matched layer boundary condition

Imaginary-distance beam propagation method under the perfectly matched layer boundary condition is applied to judge single-mode behaviour of optical waveguides, for the first time to our knowledge. A new kind of silicon-on-insulator-based rib structures with half-circle cross-section is presented. The single-mode behaviour of this kind of waveguide with radius 2mum is investigated by this method. It is single-mode when the slab height is not smaller than the radius.

Study of the ionic conductivity of polymer electrolyte using imaginary impedance spectroscopy

Polymeric electrolytes of (PEO1)(10) LiClO4-Al2O3 (PEO: poly (ethyleneoxide)) and (PEO2)(16)LiClO4-EC (EC: ethylene carbonate) were prepared. We proposed an equivalent circuit and gave the meaning of the concerned circuit elements. When the impedance spectrum deformed severely, the ionic conductivity of polymer electrolyte was determined by using the maximum of imaginary impedance, which is a convenient method.

Separating the scattering and absorption coefficients using the real and imaginary parts of the refractive index with low-coherence interferometry.

We present an analytical method that yields the real and imaginary parts of the refractive index (RI) from low-coherence interferometry measurements, leading to the separation of the scattering and absorption coefficients of turbid samples. The imaginary RI is measured using time-frequency analysis, with the real part obtained by analyzing the nonlinear phase induced by a sample. A derivation relating the real part of the RI to the nonlinear phase term of the signal is presented, along with measurements from scattering and nonscattering samples that exhibit absorption due to hemoglobin.

Analysing admittance of obstacles in evanescent waveguide using the Imaginary Smith Chart

We present a technique, using the Imaginary Smith Chart, for determining the admittance of obstacles introduced into evanescent waveguide. The admittance of an inductive iris, capacitive iris, capacitive post, variable width strip and length of evanescent waveuide are investigated. © 2012 IEEE.

Increased Bandwidth Evanescent Open-Ended Waveguide Antenna Design Using the Imaginary Smith Chart

We present a novel antenna matching technique that uses the Imaginary Smith Chart to permit wideband matching of an evanescent open-ended waveguide antenna using a dielectric sheet air-spaced from the aperture. The fabricated antenna design is demonstrated to have a measured bandwidth of 24%, from 2.13–2.7 GHz, for reflection coefficient $qquad{<} -!!10~{rm dB}$ , with 2.725 GHz waveguide cutoff. The antenna's maximum aperture dimension is ${< 0.5}lambda_{0}$ at the upper frequency in the bandwidth and so it is suitable for use in a wide angle scanning phased array

Between Imaginary Lines: Violence and its Justifications at the Military Checkpoints in Occupied Palestine

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.

Empowering Art: Reconfiguring narratives of trauma and hope in the Australian national imaginary

Aboriginal art has been the source of much contention between art curators, gallery owners, art critics and Aboriginal artists themselves. Early aesthetic debates about whether so-called traditional works should be considered ethnographic or artistic have led, at times, to conflicts over the rights of Aboriginal people to have their works exhibited according to the criteria applied to other kinds of Western artworks. This article explores how the dilemmas of troubled ethno-histories are critically embodied and reconfigured in texture and colour. It considers the problems that silenced histories pose for those responsible for their display to the public. As Aboriginal images often conceal troubled intercultural encounters it asks how artworks can be used to provide a counter-polemic to national rhetoric as artists seek to reshape and improve intergenerational futures. This text is published as a counterpart to the contribution to Disturbing Pasts from the artist Heather Kamarra Shearer.

Dublin’s ephemeral and imaginary architectures

In 1989, the Irish architectural practice O’Donnell and Tuomey were commissioned to build a temporary pavilion to represent Ireland at the 11 Cities/11 Nations exhibition at Leeuwarden in the Netherlands. Citing Peter Smithson, John Tuomey suggested the pavilion, which drew inspirations from the forms and materials of the modern Irish barn, embodied an intention ‘not just to build but to communicate’. Its subsequent reassembly for the inauguration of the Irish Museum of Modern Art in the courtyard of the seventeenth-century Royal Hospital Kilmainham in Dublin in 1991, drew comparisons between the urban sophistication of this colonial building, its svelte new refit, and the rural expression of O’Donnell + Tuomey’s barn. It was, one critic recently noted, as if ‘a wedding had been crashed by a country cousin who had forgotten to clean his boots’.
It has been argued that temporary or ephemeral pieces of architecture, unburdened by the traditional constraints of firmitas or utilitas, have the ability to offer a concise distillation of meaning and intention. Approaching the qualities of rhetoric, such architectures share similarities with the monument and yet differ in fundamental ways. Their rapid construction in lightweight materials can allow for an almost instantaneous negotiation of zeitgeist. And, unlike the monument, from the outset the space and form of these installations is designed to disappear.
This paper analyses the ephemeral architectures of Dublin in the modern period contextualising their qualities and intentions as they manifest themselves across colonial, post-colonial and contemporary epochs. It finds origins in the theatrical sets of the late eighteenth century and traces their movements into the semi-public sphere of the pleasure garden and finally into the theatre of the streets. It is here that temporary architecture in the city has been at its most potent, allowing the amplification or subversion of the meanings of much larger spaces. Historically, much of Dublin’s most conspicuous instances of ephemeral architecture have been realised as a means of articulating mass spectacle in political, religious or nationalistic events. And while much of this has sought to confirm dominant ideologies, it has also been possible to discern moments of opposition.
The contemporary period, however, has arguably witnessed a shift in ephemeral architectures from explicitly representing ‘positive ideologies’ towards something more oblique or nebulous. This turn towards abstraction in form and space has rendered an especially communicative form of architecture particularly elusive. By examining continuities within the apparent disjuncture between historical and contemporary examples, this paper begins to unpick the language of recent ephemeral architecture in Dublin and situate it within wider global trends where political and economic imperatives are often simultaneously obscured and expressed in public space by a vocabulary of universality. As Jurgen Habermas has suggested, the contemporary value given to the transitory and the ephemeral ‘discloses a longing for an undefiled, immaculate and stable present’.

'O daughter ... forget your people and your father's house': Early Modern Women Writers and the Spanish Imaginary

‘O daughter … forget your people and your father’s house’: Early Modern Women Writers and the Spanish ImaginaryAnne Holloway and Ramona WrayHolloway and Wray consider the perspectives offered by two very different seventeenth-century women (Mary Bonaventure Browne, or Mother Browne (b.1615- and Lady Ann Fanshawe (b.1625) both of whom exchanged Ireland for Spain, and both of whom record journeys both ‘real’ and imagined in their writings. Browne’s deployment of hagiographical tropes in her History of the Poor Clares may reveal the potential impact of Iberian conventual culture; her allusions to the markers of sanctity insistent on the immutability of the body, whilst accepting and anticipating spectral presence in the form of bilocation. Fanshawe’s Memoirs are considered alongside the material legacy of her ‘Booke of Receipts of Physickes, Salues, Waters, Cordialls, Preserues and Cookery.’ Her impressions both in transit and within the domus are similarly marked by receptivity and sensitivity to the host culture. Amidst a backdrop of religious persecution and political uncertainty, in both cases Spain emerges as a potentially enabling context for creativity and self-expression.Keywords: Memoir; Franciscan; Poor Clares; Fanshawe; Mary Bonaventure Browne; hagiography; life-writing; autobiography, women writers