Evidence of lower-hybrid rotating spoke oscillations in a direct current magnetron microdischarge

High frequency current-carrying spokes are observed propagating in the E$\times$B direction in a neon direct current magnetron discharge. Two modes are found with distinct frequencies and behaviors. At low discharge currents, we see highly coherent 60 MHz fluctuations. Above a distinct current threshold, secondary 5 - 10 MHz fluctuations emerge in addition to turbulent fluctuations spanning the 60 - 100 MHz range. The presence of lower-hybrid waves is invoked to explain the high frequency oscillations. We attribute the appearance of the low frequency axial modes concomittant with the onset of the high frequency turbulence to an inverse cascade process, as suggested by recent simulations

Gaussian mixture model classification of odontocetes in the Southern California Bight and the Gulf of California

A method for the automatic classification of free-ranging delphinid vocalizations is presented. The vocalizations of short-beaked and long-beaked commo

An Analysis into Physical and Virtual Power Draw Characteristics of Embedded Wireless Sensor Network Devices under DoS and RPL-Based Attacks

Currently, within the world, cybercrime is becoming increasingly rampant—often targeting civil infrastructure like power stations and other critical systems. A trend that is being noticed with these attacks is their increased use of embedded devices in denial-of-service (DoS) attacks. This creates a substantial risk to systems and infrastructures worldwide. Threats to embedded devices can be significant, and network stability and reliability can suffer, mainly through the risk of battery draining or complete system hang. This paper investigates such consequences through simulations of excessive loads, by staging attacks on embedded devices. Experimentation within Contiki OS focused on loads placed on physical and virtualised wireless sensor network (WSN) embedded devices by launching DoS attacks and by exploiting the Routing Protocol for Low Power and Lossy Networks (RPL). Results from these experiments were based on the metric of power draw, mainly the percentage increase over baseline and the pattern of it. The physical study relied on the output of the inline power analyser and the virtual study relied on the output of a Cooja plugin called PowerTracker. This involved experiments on both physical and virtual devices, and analysis of the power draws characteristics of WSN devices with a focus on embedded Linux platforms and Contiki OS. Experimental results provide evidence that peak power draining occurs with a malicious-node-to-sensor device ratio of 13-to-1. Results show a decline in power usage with a more expansive 16-sensor network after modelling and simulating a growing sensor network within the Cooja simulator

Investigation of non-normal incidence charged-particle response of CR39 nuclear track detectors, with applications in nuclear diagnostics for inertial confinement fusion

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2020Cataloged from the official PDF of thesis.Includes bibliographical references (pages 44-45).CR39 is a plastic nuclear track detector used at inertial confinement fusion (ICF) facilities to characterize the energy spectra of fusion products. This thesis presents data collected at MIT's Linear Electrostatic Ion Accelerator (LEIA) to measure CR39's detection efficiency for protons at non-normal incidence to CR39 detectors. We specifically study protons resulting from D-D fusion reactions with incident angles up to 50 degrees. Understanding the CR39 response to charged particles at an angle is essential to designing a D-D neutron spectrometer at the Z facility, which uses CR39 to detect protons incident at an angle. We find that small adjustments of 10 degrees have no effect on detection efficiency, and high detection efficiency is preserved up through 25 degrees in the range of 1.0 to 2.1 MeV. For the ICF applications, incident angles above 30 degrees are generally impractical for spectrometer design due to significant drops in proton detection. We compare the experimental results to related theoretical simulations, proposing significant constraints on these theoretical models of detection efficiency.by Ryan Przybocki.S.B.S.B. Massachusetts Institute of Technology, Department of Physic

Odyssey Text Independent Evaluation Data

We discuss the text-independent data supplied for the 2001: A Speaker Odyssey evaluation track. We cover the data creation and selection process, and we present results restricted to the Odyssey test set for participating systems in the 2000 NIST Speaker Recognition Evaluation

Speaker Recognition Evaluation Chronicles

NIST has coordinated annual evaluations of textindependent speaker recognition since 1996. During the course of this series of evaluations there have been notable milestones related to the development of the evaluation paradigm and the performance achievements of state-of-the-art systems. We document here the variants of the speaker detection task that have been included in the evaluations and the history of the best performance results for this task. Finally, we discuss the data collection and protocols for the 2004 evaluation and beyond

NIST Speaker Recognition Evaluation Chronicles

NIST has coordinated annual evaluations of textindependent speaker recognition since 1996. During the course of this series of evaluations there have been notable milestones related to the development of the evaluation paradigm and the performance achievements of state-of-the-art systems. We document here the variants of the speaker detection task that have been included in the evaluations and the history of the best performance results for this task