ECE- Monographs, Research and Papers

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This is a collection of Monographs, Research and Papers in the field of Electrical and Computer Engineering.

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    Best practices for instrumenting honey bees.
    Koenig, Phoebe A.; Petersen, Kirstin H. (2022)
    Honey bees are vital pollinators and can be used to monitor the landscape. Consequently, interest in mounting technologies onto bees to track foraging behaviors is increasing. The barrier to entry is steep, in part because the methodology for fastening tags to bees, and the success rates, are often missing from publications. We tested six factors suspected to influence the presence and tag retention rates of nurse honey bees after their introduction to hives, and followed bees until foraging age. We also compared reintroducing foragers to their maternal colony using the best method for nurse bees to releasing them in front of their maternal hive and allow them to fly back unaided. Nurses were most likely to be present in the hive with their tag still attached if sprayed with sucrose syrup and introduced using an introduction cage at night. Glue type was important, but may further be influenced by tag material. Foragers were most likely to be present with a tag attached if released in front of their colony. Preparation and introduction techniques influence the likelihood of tagged honey bee survival and of the tags remaining attached, which should be considered when executing honey bee tagging and tracking experiments.
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    Finite Element Modeling of Silicon Bead Placement for Ultrasonic Vagus Nerve Excitation
    Murthy, Chinmay (2021-08-10)
    In this paper, using finite element modeling, we investigate the possibility of using diffraction effects to focus and amplify ultrasonic waves via the placement of silicon beads in the body (water is used as the medium here for simplicity). We show that pressure waves are amplified and localized when specifically sized beads are placed, and the effects of amplification are seen even when the bead is not in line with the ultrasonic transducer, although optimum amplification results when the bead is exactly inline with the transducer. We also show that we can use stereo microphones to detect the specific location of the bead in relation to the pulse transducer so that precise control is possible for linear alignment to maximize pressure amplification. This work is motivated by the need to seek more efficient and less invasive ways of stimulating the vagus nerve in the human body, and has many applications in medicine.
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    A Reconfigurable Analog Substrate for Highly Efficient Maximum Flow Computation
    Liu, Gai; Zhang, Zhiru (2015-12)
    We present the design and analysis of a novel analog reconfigurable substrate that enables fast and efficient computation of maximum flow on directed graphs. The substrate is composed of memristors and standard analog circuit components, where the on/off states of the crossbar switches encode the graph topology. We show that upon convergence, the steady-state voltages in the circuit capture the solution to the maximum flow problem. We also propose techniques to minimize the impacts of variability and non-ideal circuit components on the solution quality, enabling practical implementation of the proposed substrate. Our performance evaluation indicates two to three orders of magnitude improvements in speed and energy efficiency compared to a standard CPU implementation. In the last part of this report, we also discuss the major limitations of the current design, and suggest promising research directions.
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    Two-Hop Interference Channels Impact of Linear Time-Varying Schemes
    Issa, Ibrahim; Fong, Silas L.; Avestimehr, Salman (2013-02-26)
    We consider the two-hop interference channel (IC) with constant channel coefficients, which consists of two source-destination pairs, separated by two relays. We analyze the achievable degrees of freedom (DoF) of such network when relays are restricted to perform scalar amplify-forward (AF) operations, with possibly time-varying coefficients. We show that, somewhat surprisingly, by providing the flexibility of choosing time-varying AF coefficients at the relays, it is possible to achieve 4/3 sum-DoF. We also develop a novel outerbound that matches our achievability, hence characterizing the sum-DoF of two-hop interference channels with time-varying AF relaying strategies.