Characterizing Smartphone Power Management in the Wild

For better reliability and prolonged battery life, it is important that users and vendors understand the quality of charging and the performance of smartphone batteries. Considering the diverse set of devices and user behavior it is a challenge. In this work, we analyze a large collection of battery analytics dataset collected from 30K devices of 1.5K unique smartphone models. We analyze their battery properties and state of charge while charging, and reveal the characteristics of different components of their power management systems: charging mechanisms, state of charge estimation techniques, and their battery properties. We explore diverse charging behavior of devices and their users.Comment: Proceedings of 7th International Workshop on Hot Topics in Planet-Scale Measurement, HotPlanet'1

Simulating Vehicle Movement and Multi-Hop Connectivity from Basic Safety Messages

The Basic Safety Message (BSM) is a standardized communication packet that is sent every tenth of a second between connected vehicles using Dedicated Short Range Communication (DSRC). BSMs contain data about the sending vehicle's state, such as speed, location, and the status of the turn signal. Currently, many BSM datasets are available through the connected vehicle testbeds of U.S. Department of Transportation from all over the country. However, without a proper visualization tool, it is not possible to analyze or visually get an overview of the spatio-temporal distribution of the data. With this goal, a web application has been developed which can ingest a raw BSM dataset and display a time-based simulation of vehicle movement. The simulation also displays multi-hop vehicular network connectivity over DSRC. This paper gives details about the application, including an explanation of the multi-hop partitioning algorithm used to classify the vehicles into separate network partitions. A performance analysis for the simulation is included, in which it is suggested that calculating a connectivity matrix with the multi-hop partitioning algorithm is computationally expensive for large number of vehicles

Simulated rotor test apparatus dynamic characteristics in the 80- by 120-foot wind tunnel

A shake test was conducted in the 80 by 120 foot Wind Tunnel at NASA Ames Research Center, using a load frame and dummy weights to simulate the weight of the NASA Rotor Test Apparatus. The simulated hub was excited with broadband random excitation, and accelerometer responses were measured at various locations. The transfer functions (acceleration per unit excitation force as a function of frequency) for each of the accelerometer responses were computed, and the data were analyzed using modal analysis to estimate the model parameters