551 research outputs found
âIt was, we felt, their countryâ : childhood elsewhere in Mordecai Richlerâs The Street
Since the Industrial revolution, historians and critics agree, concepts of time and space have become inappropriate to describe contemporary society: it is a shifting, moving, liquid world, and progresses in technologies only contribute to peopleâs feeling of being always âelsewhereâ. Instantaneity and movement are the constituent referents of our post-modern era, where the loss of certainties leaves human beings with little self-confidence and beliefs. To be foreign in oneâs own country is daily routine; but it can also be an incitement to produce stories of condemnation. This article seeks to show how Jewish-Canadian author Mordecai Richler uses his powerful and striking irony to denounce Jews condition in 1940sâ Montreal ghetto, and how the stories collected in The Street describe the âelsewherenessâ his community was forced to experience. Nevertheless, the paper will analyse how Richler challenges stereotypes and prejudices, focusing on the spaces of otherness he had experienced in his childhood years and which have made him one of the greatest Canadian voices of 20th century.peer-reviewe
il Canada nelle autobiografie di Frederick P. Grove, Mordecai Richler e Michael Ondaatje
2012-2013Autobiography is a highly problematic genre whose main features are commonly considered memory, experience and identity. Nonetheless, there is also an inevitably degree of fiction-making concerned with the autobiographical act, as most autobiographies are inspired by a creative, and therefore fictional, impulse to select only those events and experiences in the writerâs life that build up an integrated pattern. As such, this encourages questions about fact and fiction, about the relations between reality and the text, and about origins: in this sense, there is a necessary link between the conditions â political, economic, and social â in which writers find themselves and the kinds of stories they choose to tell. The space they inhabit and the accrued meanings of space and time play a constitutive role in their narratives; but space is not given: it is culturally constructed or produced, it incorporates temporal change. The progresses in technology, the new media and migrations have finally led to «time-space compression», and to the concept of nonplaces, where the individual is out-of-the-world. In this sense, Canada perfectly represents what it means to live in a «third space» of in-betweenness: so, we will see how German-Canadian writer Frederick Philip Grove avoids categorization of literary nationalism locating himself in an isolated and paradigmatic position between literatures; we will appreciate Mordecai Richler, whose irony is crucial in order to describe the moments and spaces given to a Canadian Jew in Montrealâs ghetto; finally, we will look at Michael Ondatjeeâs continuous references to the cultural and political situation in Sri Lanka, and how he uses these connections to build a sort of third-person autobiography through which he can recover the memory of the places from his Ceylonese childhood. At the end of this analysis, it will be clear how many difficulties the autobiographical impulse has to face, how many parameters it has to respect, and how much truth and fiction influence and corrupt each other. [edited by author]XII n.s
Air-fuel Ratio Estimation Along Diesel Engine Transient Operation Using In-cylinder Pressure
Abstract The increasing competition among automotive OEMs together with the worsening of the environmental pollution has lead to the development of complex engine systems. Innovative control strategies are needed to simplify and improve the Engine Management System (EMS), moving towards energy saving and complying with the restrictions on emissions standards. In this scenario the application of methodologies based on the in-cylinder pressure measurement finds widespread applications. Indeed, the in-cylinder pressure signal provides direct in-cylinder information with a high dynamical potentiality that is fundamental for the control and diagnosis of the combustion process. Furthermore, the in-cylinder pressure measurement may also allow reducing the number of existing sensors on-board, thus lowering the equipment costs and the engine wiring complexity. The paper focuses on the estimation of the Air-Fuel ratio from the in-cylinder pressure signal. The methodology is based on the analysis of the statistical moments of the pressure cycle and was already presented by the authors and applied to a set of steady state engine operation conditions. In this paper the technique has been enhanced in order to be applied under the more critical engine transient operation. The results achieved show a satisfactory accuracy in predicting the Air-Fuel ratio during engine transients performed at the engine test bench on a Common-Rail turbocharged Diesel engine
Second order nonlinear optics in AlGaAs metasurfaces
Recently, nonlinear optics at the nanoscale level has emerged as a promising branch of nanophotonics. In this work, we focus our attention on Aluminum Gallium Arsenide (AlGaAs) nanoantennas and metasurfaces for efficient and controlled second harmonic photon emission. After a brief introduction concerning the main studies in this field, we present the latest results achieved in AlGaAs platforms both in the lossless and absorption regimes
Harmonic generation with multi-layer dielectric metasurfaces
Abstract
Metasurfaces have recently gained extensive interest because of their extraordinary optical behavior as artificial material interfaces with ultrahigh compactness. In this framework, dielectric platforms have newly become very promising for nonlinear nanophotonics, providing opportunities, especially for ultrafast optical switching, and high harmonic generation, opening the research field of nonlinear metaoptics. Up to now, nonlinear metaoptics have been mostly explored using single metasurfaces. However, in a long-term vision, the stacking of optical metasurfaces, very challenging in terms of fabrication, is one key goal of this research field. Here, we demonstrate a three-layer metasurface in the AlGaAs-on-insulator platform, which improves the second harmonic generation efficiency by more than one order of magnitude with respect to its one-layer counterpart. Our achievement paves the way toward phase-shaping multilayer and multifunctional all-dielectric metasurfaces
All-optical free-space routing of upconverted light by metasurfaces via nonlinear interferometry
All-optical modulation yields the promise of high-speed information
processing. In this frame, metasurfaces are rapidly gaining traction as
ultrathin multifunctional platforms for light management. Among the featured
functionalities, they enable light wavefront manipulation and, more recently,
demonstrated the ability to perform light-by-light manipulation through
nonlinear optical processes. Here, by employing a nonlinear periodic
metasurface, we demonstrate all-optical routing of telecom photons upconverted
to the visible range. This is achieved via the interference between two
frequency-degenerate upconversion processes, namely third-harmonic and
sum-frequency generation, stemming from the interaction of a pump pulse with
its frequency-doubled replica. By tuning the relative phase and polarization
between these two pump beams, and concurrently engineering the nonlinear
emission of the individual elements of the metasurfaces (meta-atoms) along with
its pitch, we route the upconverted signal among the diffraction orders of the
metasurface with a modulation efficiency up to 90%. Thanks to the phase control
and the ultrafast dynamics of the underlying nonlinear processes, free-space
all-optical routing could be potentially performed at rates close to the
employed optical frequencies divided by the quality factor of the optical
resonances at play. Our approach adds a further twist to optical
interferometry, which is a key-enabling technique in a wide range of
applications, such as homodyne detection, radar interferometry, LiDAR
technology, gravitational waves detection, and molecular photometry. In
particular, the nonlinear character of light upconversion combined with phase
sensitivity is extremely appealing for enhanced imaging and biosensing.Comment: 18 pages, 6 figure
A non-involutory selfduality
We report the effect of the aluminum oxide substrate on the emission of monolithic AlGaAs-on-insulator nonlinear nanoantennas. By coupling nonlinear optical measurements with electron diffraction and microscopy observations, we find that the oxidation-induced stress causes negligible crystal deformation in the AlGaAs nanostructures and only plays a minor role in the polarization state of the harmonic field. This result highlights the reliability of the wet oxidation of thick AlGaAs optical substrates and further confirms the bulk chi(2) origin of second harmonic generation at 1.55 um in these nanoantennas, paving the way for the development of AlGaAs-on-insulator monolithic metasurfaces
Metalâdielectric hybrid nanoantennas for efficient frequency conversion at the anapole mode
Background: Dielectric nanoantennas have recently emerged as an alternative solution to plasmonics for nonlinear light manipulation at the nanoscale, thanks to the magnetic and electric resonances, the strong nonlinearities, and the low ohmic losses characterizing high refractive-index materials in the visible/near-infrared (NIR) region of the spectrum. In this frame, AlGaAs nanoantennas demonstrated to be extremely efficient sources of second harmonic radiation. In particular, the nonlinear polarization of an optical system pumped at the anapole mode can be potentially boosted, due to both the strong dip in the scattering spectrum and the near-field enhancement, which are characteristic of this mode. Plasmonic nanostructures, on the other hand, remain the most promising solution to achieve strong local field confinement, especially in the NIR, where metals such as gold display relatively low losses. Results: We present a nonlinear hybrid antenna based on an AlGaAs nanopillar surrounded by a gold ring, which merges in a single platform the strong field confinement typically produced by plasmonic antennas with the high nonlinearity and low loss characteristics of dielectric nanoantennas. This platform allows enhancing the coupling of light to the nanopillar at coincidence with the anapole mode, hence boosting both second- and third-harmonic generation conversion efficiencies. More than one order of magnitude enhancement factors are measured for both processes with respect to the isolated structure. Conclusion: The present results reveal the possibility to achieve tuneable metamixers and higher resolution in nonlinear sensing and spectroscopy, by means of improved both pump coupling and emission efficiency due to the excitation of the anapole mode enhanced by the plasmonic nanoantenna
Metalâdielectric hybrid nanoantennas for efficient frequency conversion at the anapole mode
Background: Dielectric nanoantennas have recently emerged as an alternative solution to plasmonics for nonlinear light manipulation at the nanoscale, thanks to the magnetic and electric resonances, the strong nonlinearities, and the low ohmic losses characterizing high refractive-index materials in the visible/near-infrared (NIR) region of the spectrum. In this frame, AlGaAs nanoantennas demonstrated to be extremely efficient sources of second harmonic radiation. In particular, the nonlinear polarization of an optical system pumped at the anapole mode can be potentially boosted, due to both the strong dip in the scattering spectrum and the near-field enhancement, which are characteristic of this mode. Plasmonic nanostructures, on the other hand, remain the most promising solution to achieve strong local field confinement, especially in the NIR, where metals such as gold display relatively low losses. Results: We present a nonlinear hybrid antenna based on an AlGaAs nanopillar surrounded by a gold ring, which merges in a single platform the strong field confinement typically produced by plasmonic antennas with the high nonlinearity and low loss characteristics of dielectric nanoantennas. This platform allows enhancing the coupling of light to the nanopillar at coincidence with the anapole mode, hence boosting both second- and third-harmonic generation conversion efficiencies. More than one order of magnitude enhancement factors are measured for both processes with respect to the isolated structure. Conclusion: The present results reveal the possibility to achieve tuneable metamixers and higher resolution in nonlinear sensing and spectroscopy, by means of improved both pump coupling and emission efficiency due to the excitation of the anapole mode enhanced by the plasmonic nanoantenna
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