We report our experiences in porting and tuning the Apache Spark data analytics framework on the Cray XC30 (Edison) and XC40 (Cori) systems, installed at NERSC. We find that design decisions made in the development of Spark are based on the assumption that Spark is constrained primarily by network latency, and that disk I/O is comparatively cheap. These assumptions are not valid on Edison or Co...

This thesis focuses on a digital Built-in Self-Test (BIST) approach to perform specification oriented testing of the analog portion of a mixed-signal system. The BIST utilizes a direct digital synthesizer (DDS) based test pattern generator (TPG) and a multiplieraccumulator (MAC) based output response analyzer (ORA) to stimulate and analyze the analog devices under test, respectively. This appro...

To expand the coverage of current aviation VHF communication services, it is necessary to develop a satellite-based system. This research aims analyze satellite link budget calculations for AMS(R)S frequencies using Low Earth Orbit (LEO) at an altitude 600 km, in accordance with studies conducted by ICAO and ITU. The calculation, parameters such as aircraft antenna gain = -1 dBi, 8 RF power 16 ...

The paper addresses on-chip test for IC RF transceivers. The baseband DSP available on chip serves as a tester while the RF front-end is reconfigured for test. The basic test setup is a loopback, enabled by a test attenuator and in some cases by an offset mixer, too. Different variants of this setup adopt the bypassing technique to boost testability. The existing limitations and tradeoffs in te...

Introduction Transmit array systems offer the promise of accelerated excitation, B1 shimming, and the potential for SAR and RF safety management [1,2], while also demanding high-fidelity RF playback in a challenging multi-channel environment. Tx coil arrays are subject to mutual coupling and loading variations, while RF power amplifiers exhibit non-linearity, ill-defined output impedances, and ...

In 2005, Murdoch and Danezis demonstrated the first practical congestion attack against a deployed anonymity network. They could identify which relays were on a target Tor user’s path by building paths one at a time through every Tor relay and introducing congestion. However, the original attack was performed on only 13 Tor relays on the nascent and lightly loaded Tor network. We show that the ...

We present an application in topological map building and localization with a high resolution omnidirectional camera. A visual map uses sift features in combination with affinely invariant Harris corners as its feature points. We use an automatic scheme to find correspondences from a video sequence to create the map. Loop-back is also detected automatically while the map is built. For localizat...