3,777 research outputs found

    Analysing climate action plans of selected UK cities for their SDG alignment

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    In UK, the Climate change Act of 2008 has placed a binding target of reducing the net carbon emission in 2050 by at least 80% compared to the 1990 baseline. With a high share of urban population, the contribution of cities and urban areas towards climate change mitigation and adaptation becomes crucial. UK being a signatory to the Sustainable Development Goals (SDG) in 2016, there is a new emphasis on the sustainability of cities as well. In this paper, a preliminary analysis of climate action initiatives of three UK cities (Bristol, Leicester and Milton Keynes) and their alignment with the SDG is presented. We used a text mining approach to analyse the climate action plans and then use this to map the alignment with the SDGs. We find that climate action plans have not focused on the sustainable development goals or the SDGs and their focus remains limited mainly to mitigation activities through promotion of renewable energies at homes and in buildings and actions on transport. However, climate action plans could influence a significant number of SDGs and an integrated approach could be beneficial for the cities and their residents

    Analysis of the extraterrestrial life detection problem

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    Analysis of extraterrestrial life detection proble

    Measurement of spontaneous emission from a two-dimensional photonic band gap defined microcavity at near-infrared wavelengths

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    An active, photonic band gap-based microcavity emitter in the near infrared is demonstrated. We present direct measurement of the spontaneous emission power and spectrum from a microcavity formed using a two-dimensional photonic band gap structure in a half wavelength thick slab waveguide. The appearance of cavity resonance peaks in the spectrum correspond to the photonic band gap energy. For detuned band gaps, no resonances are observed. For devices with correctly tuned band gaps, a two-time enhancement of the extraction efficiency was demonstrated compared to detuned band gaps and unpatterned material

    Photonic bandgap disk laser

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    A two-dimensional photonic crystal defined hexagonal disk laser which relies on Bragg reflection rather than the total internal reflection as in traditional microdisk lasers is described. The devices are fabricated using a selective etch to form free standing membranes suspended in air. Room temperature lasing at 1650nm for a 150nm thick, ~15μm wide cavity fabricated in InP/GaAsP is demonstrated with pulsed optical pumping

    Integration of fiber coupled high-Q silicon nitride microdisks with atom chips

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    Micron scale silicon nitride (SiN_x) microdisk optical resonators are demonstrated with Q = 3.6 x 10^6 and an effective mode volume of 15 (\lambda / n)^3 at near visible wavelengths. A hydrofluoric acid wet etch provides sensitive tuning of the microdisk resonances, and robust mounting of a fiber taper provides efficient fiber optic coupling to the microdisks while allowing unfettered optical access for laser cooling and trapping of atoms. Measurements indicate that cesium adsorption on the SiN_x surfaces significantly red-detunes the microdisk resonances. A technique for parallel integration of multiple (10) microdisks with a single fiber taper is also demonstrated.Comment: Published vesion. Minor change

    Mechanical oscillation and cooling actuated by the optical gradient force

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    In this work we combine the large per-photon optical gradient force with the sensitive feedback of a high quality factor whispering-gallery microcavity. The cavity geometry, consisting of a pair of silica disks separated by a nanoscale gap, shows extremely strong dynamical backaction, powerful enough to excite giant coherent oscillations even under heavily damped conditions (mechanical Q=4). In vacuum, the threshold for regenerative mechanical oscillation is lowered to an optical input power of only 270-nanoWatts, or roughly 1000 stored cavity photons, and efficient cooling of the mechanical motion is obtained with a temperature compression factor of 13-dB for 4-microWatts of dropped optical input power.Comment: 29 pages, 8 figure

    Intelligent Bio-Environments: Exploring Fuzzy Logic Approaches to the Honeybee Crisis

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    Project in collaboration with the Institute of Energy and Sustainable Development (IESD)This paper presents an overview of how fuzzy logic can be employed to model intelligent bio-environments. It explores how non-invasive monitoring techniques, combined with sensor fusion, can be used to generate a warning signal if a critical event within the natural environment is on the horizon. The honeybee hive is presented as a specific example of an intelligent bio-environment that unfortunately, under certain indicative circumstances, can fail within the natural world. This is known as Colony Collapse Disorder (CCD). The paper describes the design of a fuzzy logic methodology that utilizes input from non-invasive beehive monitoring systems, combining data from dedicated sensors and other disparate sources. An overview is given of two fuzzy logic approaches that are being explored in the context of the beehive; a fuzzy logic system and an Adaptive Neuro-Fuzzy Inference System (ANFIS)

    Proof-of-principle of surface detection with air-guided quantum cascade lasers

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    We report a proof-of-principle of surface detection with air-guided quantum cascade lasers. Laser ridges were designed to exhibit an evanescent electromagnetic field on their top surface that can interact with material or liquids deposited on the device. We employ photoresist and common solvents to provide a demonstration of the sensor setup. We observed spectral as well as threshold currents changes as a function of the deposited material absorption curve. A simple model, supplemented by 2D numerical finite element method simulations, allows one to explain and correctly predict the experimental results

    High temperature cavity polaritons in epitaxial Er_2O_3 on silicon

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    Cavity polaritons around two Er^(3+) optical transitions are observed in microdisk resonators fabricated from epitaxial Er_2O_3 on Si(111). Using a pump-probe method, spectral anticrossings and linewidth averaging of the polariton modes are measured in the cavity transmission and luminescence at temperatures above 361 K
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