Endurable Transient Inconsistency in Byte-Addressable Persistent B+-Tree

Department of Computer Science and EngineeringWith the emergence of byte-addressable persistent memory (PM), a cache line, instead of a page, is expected to be the unit of data transfer between volatile and non-volatile devices, but the failure-atomicity of write operations is guaranteed in the granularity of 8 bytes rather than cache lines. This granularity mismatch problem has generated interest in redesigning block-based data structures such as B+-trees. However, various methods of modifying B+-trees for PM degrade the efficiency of B+-trees, and attempts have been made to use in-memory data structures for PM. In this study, we develop Failure-Atomic ShifT (FAST) and Failure-Atomic In-place Rebalance (FAIR) algorithms to resolve the granularity mismatch problem. Every 8-byte store instruction used in the FAST and FAIR algorithms transforms a B+-tree into another consistent state or a {\it transient inconsistent} state that read operations can tolerate. By making read operations tolerate transient inconsistency, we can avoid expensive copy-on-write, logging, and even the necessity of read latches so that read transactions can be non-blocking. Our experimental results show that legacy B+-trees with FAST and FAIR schemes outperform the state-of-the-art persistent indexing structures by a large margin.clos

Real-time interactive speech technology at Threshold Technology, Incorporated

Basic real-time isolated-word recognition techniques are reviewed. Industrial applications of voice technology are described in chronological order of their development. Future research efforts are also discussed

Muscle Memory and the Local Concentration of Capital Punishment

The modern death penalty is not just concentrating in a handful of practicing states; it is disappearing in all but a few capitally active localities. Capital-punishment concentration, however, still surfaces more as the subject of casual observation than as the object of sophisticated academic inquiry. Normative and doctrinal analyses of the phenomenon are virtually nonexistent, in part because the current ability to measure and report concentration is so limited. This Article is the first attempt to measure capital-punishment concentration rigorously, by combining different sources of county-level data and by borrowing quantitative tools that economists use to study market competition. The analysis yields three major findings: (1) capital sentencing is concentrating dramatically; (2) executions are concentrating more gradually; and (3) both trends persist within most capitally active states. Certain normative and doctrinal conclusions follow from the empirical findings. The causes of concentration are likely to be more bureaucratic and path dependent than they are democratic and pragmatic, reflecting what I call the “muscle memory” of local institutional practice. If local muscle memory indeed explains concentration, such concentration violates basic punishment norms requiring equal treatment of similar offenders. This problem notwithstanding, existing death penalty jurisprudence does not account for local concentration. For concentration to have any influence on the outcome of constitutional inquiry, the Supreme Court would have to revise its working definition of “arbitrariness.

A LiDAR Based Semi-Autonomous Collision Avoidance System and the Development of a Hardware-in-the-Loop Simulator to Aid in Algorithm Development and Human Studies

In this paper, the architecture and implementation of an embedded controller for a steering based semi-autonomous collision avoidance system on a 1/10th scale model is presented. In addition, the development of a 2D hardware-in-the-loop simulator with vehicle dynamics based on the bicycle model is described. The semi-autonomous collision avoidance software is fully contained onboard a single-board computer running embedded GNU/Linux. To eliminate any wired tethers that limit the system’s abilities, the driver operates the vehicle at a user-control-station through a wireless Bluetooth interface. The user-control-station is outfitted with a game-controller that provides standard steering wheel and pedal controls along with a television monitor equipped with a wireless video receiver in order to provide a real-time driver’s perspective video feed. The hardware-in-the-loop simulator was developed in order to aid in the evaluation and further development of the semi-autonomous collision avoidance algorithms. In addition, a post analysis tool was created to numerically and visually inspect the controller’s responses. The ultimate goal of this project was to create a wireless 1/10th scale collision avoidance research platform to facilitate human studies surrounding driver assistance and active safety systems in automobiles. This thesis is a continuation of work done by numerous Cal Poly undergraduate and graduate students