396 research outputs found

    Guest Artist:Mike Block, Cello & Composer & Faculty Artist:Katherine Lewis, Viola

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    Center for the Performing Arts Thursday Evening February 15, 2007 8:00p.m

    Practical Experiences of a Smart Livestock Location Monitoring System leveraging GNSS, LoRaWAN and Cloud Services.

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    Livestock farming is, in most cases in Europe, unsupervised, thus making it difficult to ensure adequate control of the position of the animals for the improvement of animal welfare. In addition, the geographical areas involved in livestock grazing usually have difficult access with harsh orography and lack of communications infrastructure, thus the need to provide a low-power livestock localization and monitoring system is of paramount importance, which is crucial not for a sustainable agriculture, but also for the protection of native breeds and meats thanks to their controlled supervision. In this context, this work presents an Internet of things (IoT)-based system integrating low-power wide area (LPWA) technology, cloud and virtualization services to provide real-time livestock location monitoring. Taking into account the constraints coming from the environment in terms of energy supply and network connectivity, our proposed system is based on a wearable device equipped with inertial sensors, Global Positioning System (GPS) receiver and LoRaWAN transceiver, which can provide a satisfactory compromise between performance, cost and energy consumption. At first, this article provides the state-of-the-art localization techniques and technologies applied to smart livestock. Then, we proceed to provide the hardware and firmware co-design to achieve very low energy consumption, thus providing a significant positive impact to the battery life. The proposed platform has been evaluated in a pilot test in the Northern part of Italy, evaluating different configurations in terms of sampling period, experimental duration and number of devices. The results are analyzed and discussed for packe delivery ratio, energy consumption, localization accuracy, battery discharge measurement and delay

    Hybrid visibility compositing and masking for illustrative rendering

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    In this paper, we introduce a novel framework for the compositing of interactively rendered 3D layers tailored to the needs of scientific illustration. Currently, traditional scientific illustrations are produced in a series of composition stages, combining different pictorial elements using 2D digital layering. Our approach extends the layer metaphor into 3D without giving up the advantages of 2D methods. The new compositing approach allows for effects such as selective transparency, occlusion overrides, and soft depth buffering. Furthermore, we show how common manipulation techniques such as masking can be integrated into this concept. These tools behave just like in 2D, but their influence extends beyond a single viewpoint. Since the presented approach makes no assumptions about the underlying rendering algorithms, layers can be generated based on polygonal geometry, volumetric data, point-based representations, or others. Our implementation exploits current graphics hardware and permits real-time interaction and rendering.publishedVersio

    Recent progress in distributed feedback InGaN/GaN laser diodes

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    Laser diodes based on Gallium Nitride (GaN) are useful devices in a wide range of applications including atomic spectroscopy, data storage and optical communications. To fully exploit some of these application areas there is a need for a GaN laser diode with high spectral purity, e.g. in atomic clocks, where a narrow linewidth blue laser source can be used to target the atomic cooling transition. We report on the continuous wave, room temperature operation of a distributed feedback laser diode (DFB-LD) with high-order notched gratings. The design, fabrication and characterization of DFB devices based on the (Al,In) GaN material system is described. A single peak emission at 408.6 nm with an optical power of 20 mW at 225 mA and a side mode suppression ratio (SMSR) of 35 dB was achieved. Additionally, we demonstrate the use of a GaN DFB-LD as a transmitter in visible optical communications system. We also present results from a DFB-LD optimized for laser cooling of Sr+

    Exile Vol. XXVII No. 1

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    ANDY ACKER: Four Lane Breakfast 30 MIKE AUGUSTA: The Store 25-27 J. L. FREEMAN: Bobbie 22 Poem 33 JENNIFER E. GARDNER: Photo 3 Deeds Field 9 Photo 21 Photo 23 Photo 24 LAURA GILBERT: Photo 13 Photo 28 Photo 29 Photo 31 Photo 36 KATE GLAZER: Drawing 14 MICHAEL HEINLIN: Reflections 19 DAVE HOGSHIRE: The Life And Times Of General Worm 29 CHAD HUSSEY: Waiting for Anne Sexton 13 JOHN WHITWORTH KROPF: Friends in the Park 30 DANE LAVIN: Story 4-8 LISA LAWRENCE: Poem 17 The Man With The Red Hat 15 JAMES LUNDY: Bonds 10 Photo 30 Photo 34 Twisted Ulna 11 LISA MEAD: Resistance 9 LISA MINACCI: The Drop 33 A. PENCE: The Minstrels 1 Mussels 33 PENELOPE A. RISEBOROUGH: Poem 2 Regent Street Mannequins 2 RICK RORICK: Photo 18 A. K. SESSIONS Nervious Tension 10 SUZIE SNYDER: Photo 16 L. S. VIOLA: Trash Can JOHN ZARCHEN: In Autumn 20 ANONYMOUS: Untitled Article 32 Sandymount Strand 35 Cover drawing by Kate Glaze

    GaN-based distributed feedback laser diodes for optical communications

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    Over the past 20 years, research into Gallium Nitride (GaN) has evolved from LED lighting to Laser Diodes (LDs), with applications ranging from quantum to medical and into communications. Previously, off-the-shelf GaN LDs have been reported with a view on free space and underwater communications. However, there are applications where the ability to select a single emitted wavelength is highly desirable, namely in atomic clocks or in filtered free-space communications systems. To accomplish this, Distributed Feedback (DFB) geometries are utilised. Due to the complexity of overgrowth steps for buried gratings in III-Nitride material systems, GaN DFBs have a grating etched into the sidewall to ensure single mode operation, with wavelengths ranging from 405nm to 435nm achieved. The main motivation in developing these devices is for the cooling of strontium ions (Sr+) in atomic clock applications, but their feasibility for optical communications have also been investigated. Data transmission rates exceeding 1 Gbit/s have been observed in unfiltered systems, and work is currently ongoing to examine their viability for filtered communications. Ultimately, transmission through Wavelength Division Multiplexing (WDM) or Orthogonal Frequency Division Multiplexing (OFDM) is desired, to ensure that data is communicated more coherently and efficiently. We present results on the characterisation of GaN DFBs, and demonstrate their capability for use in filtered optical communications systems
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