Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 341 for “"Backscatter"”.
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YSCAT Backscatter Distributions
… 6 m/s.</p> <p>In order to characterized YSCAT94 backscatter distributions, a second order polynomial in log space is developed as a model for the probability of the radar cross sectionΓρ(σ°). Following Gotwols and ThompsonΓρ(σ°) is found to adhere to a log-normal distribution for horizontal …
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FMCW RFID backscatter localization
… frequency-modulated continuous-wave radar for backscatter channel estimation. Overall, our system contributes improvements in the sampling rate and cost of the current state-of-the-art one-shot estimation systems.
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Mobile Underwater Backscatter Networking
Underwater backscatter is a recently introduced technology for ultra-low-power underwater networking. Despite advances in this technology, existing systems are limited to static environments and cannot operate reliably under mobility. This thesis presents EchoRider, the first system that enables …
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Longer Range Backscatter Communications for IoT
… range of applications. Within this network, backscatter communication plays a significant role. Expanding the operational range of backscatter systems holds the potential to unlock new application possibilities. One of the limitations faced by the backscatter system is the presence of phase …
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Backscatter and Attenuation Characterization of Ventricular Myocardium
… the myocardium. In this Dissertation, integrated backscatter and attenuation analyses were performed on midgestational fetal hearts to assess potential differences in the left and right ventricular myocardium. The hearts were interrogated using a 50 MHz transducer that enabled finer spatial …
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3D backscatter localization for fine-grained robotics
… unique capability is that it can localize backscatter nodes with sub-centimeter accuracy without any constraints on their locations or mobility. TurboTrack makes two key technical contributions. First, it presents a pipelined architecture that can extract a sensing bandwidth from every …
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Backscatter of electromagnetic waves from a rough layer
Call number: LD2668 .T4 1966 K96
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Backscatter And Attenuation Properties Of Mammalian Brain Tissues
… of mammalian brain tissues focusing on backscatter and attenuation. Orientation dependence and spatial averaging of data were analyzed using the same method resulting from insertion of tissue sample between a transducer and a reference reflector. Apparent Backscatter Transfer Function …
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Orientation dependence of the acoustic backscatter for elongated zooplankton
The width of the main lobe of the acoustic backscatter directivity pattern of decapod shrimp (Palaemonetes vulgaris) is examined versus acoustic frequency. Using the distorted wave Born approximation (DWBA) and the geometry of a prolate spheroid, an analytic formula for the backscatter cross …
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Pushing the Limits of RF and Underwater Backscatter Systems
Backscatter communication systems, in both air and water, are great alternatives to traditional communication systems due to their low power requirement. The fact that backscatter systems can communicate at near-zero power makes them desirable for long-term applications such as environmental …
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Distributed Vibration Sensing using Rayleigh Backscatter in Optical Fibers
Sensing has been essential for the investigation, understanding, exploitation, and utilization of physical phenomena. Traditional single-point sensing methods are being challenged by the multi-point or distributed sensing capabilities afforded by optical fiber sensors. A powerful technique …
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Azimuth Modulation of the Radar Backscatter at Near-Normal Incidence
… important to understand the sensitivity of the backscatter to both radar parameters and surface parameters.</p> <p>At near-normal incidence angles, it has been assumed that the radar backscatter exhibits little or no azimuth dependence (Colton, 1989). However, recent data taken by the BYU YSCAT …
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Ultrasound backscatter microscope for In vivo imaging of human fingertip
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
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Analog Underwater Backscatter: Networked Underwater Sensing at Microwatt Power Levels
We present Analog Underwater Backscatter (AUB), the first technology for microwatt-level underwater wireless sensor networks. AUB departs from past underwater backscatter technologies in that it encodes sensor data directly into the physical layer through analog (frequency) modulation. Our design …
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Enabling Long-Range Underwater Backscatter via Van Atta Acoustic Networks
… the core of VAB is a novel, scalable underwater backscatter architecture that bridges recent advances in RF backscatter (Van Atta architectures) with ultra-low-power underwater acoustic networks. Our design introduces multiple innovations across the networking stack, which enable it to overcome …
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Microstructure of Flash processed Steel Characterized by Electron Backscatter Diffraction
… techniques. In this investigation, electron backscatter diffraction was used to measure the grain size, grain orientations, and phase fractions in AISI 8620 samples flash processed to a series of different maximum temperatures. The combination of high strength with moderate ductility obtained …
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Distributed fibre sensing using microwave heterodyne detection of spontaneous Brillouin backscatter
… all recent cases using direct detection of the backscattered power. As the input pulse power is increased, nonlinear processes ensue, compromising the accuracy of the sensor. These processes were investigated both experimentally and theoretically for a range of input pulse durations, focussing …
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Using the piezoelectric backscatter signal for remote sensing of neural signals
… system that is based on modulation of the backscatter signal from a piezoelectric element by the neural signals. The hypothesis is that if the neural signal is detected with a simple amplifier and the output of this amplifier is connected in parallel to a piezoelectric element, the …
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Backscatter Spatial Coherence for Ultrasonic Image Quality Characterization: Theory and Applications
… This dissertation explores the application of backscatter spatial coherence as an alternative image quality metric for adaptive imaging. Adaptive ultrasound methods applying spatial coherence feedback are evaluated in the context of three different applications: 1) the automated selection of …
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