2015

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Visible to the public Characterizing Smartphone Usage Patterns from Millions of Android Users

Submitted by awhitesell on Wed, 01/13/2016 - 4:45pm. Contributors:

The prevalence of smart devices has promoted the popularity of mobile applications (a.k.a. apps) in recent years. A number of interesting and important questions remain unanswered, such as why a user likes/dislikes an app, how an app becomes popular or eventually perishes, how a user selects apps to install and interacts with them, how frequently an app is used and how much trac it generates, etc. This paper presents an empirical analysis of app usage behaviors collected from millions of users of Wandoujia, a leading Android app marketplace in China.

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Visible to the public Reliability Analysis with Dynamic Reliability Block Diagrams in the Mobius Modeling Tool

Submitted by awhitesell on Wed, 01/13/2016 - 4:04pm. Contributors:

Reliability block diagram (RBD) models are a commonly used reliability analysis method. For static RBD models, combinatorial solution techniques are easy and ecient. However, static RBDs are limited in their ability to express varying system state, dependent events, and non-series-parallel topologies. A recent extension to RBDs, called Dynamic Reliability Block Diagrams (DRBD), has eliminated those limitations.

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Visible to the public Controller Synthesis for Linear Time-varying Systems with Adversaries

Submitted by awhitesell on Wed, 01/13/2016 - 11:53am. Contributors:

We present a controller synthesis algorithm for a discrete time reach-avoid problem in the presence of adversaries. Our model of the adversary captures typical malicious attacks envisioned on cyber-physical systems such as sensor spoong, controller corruption, and actuator intrusion. After formulating the problem in a general setting, we present a sound and complete algorithm for the case with linear dynamics and an adversary with a budget on the total L2-norm of its actions.

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Visible to the public L2-gain Analysis for a Class of Hybrid Systems with Applications to Reset and Event-triggered Control A Lifting Approach

Submitted by awhitesell on Wed, 01/13/2016 - 11:45am. Contributors:

Abstract: In this paper we study the stability and L2-gain properties of a class of hybrid systems that exhibit linear flow dynamics, periodic time-triggered jumps and arbitrary nonlinear jump maps. This class of hybrid systems is relevant for a broad range of applications including periodic event-triggered control, sampled-data reset control, sampled-data saturated control, and certain networked control systems with scheduling protocols.

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Visible to the public Detecting and Recovering from Faults in Programmed Molecular Systems

Submitted by Robyn.Lutz on Wed, 12/23/2015 - 3:12pm. Contributors:

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For reliable operation of programmed molecular systems, the capability to detect faults when they occur and to initiate recovery is essential. Since a faulty system cannot be depended upon to report its own failure, a monitoring device is needed. The work presented here describes the design of one such fault protection device, called a molecular watchdog timer.

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Visible to the public Source Localization by a Network of Imperfect Binary Sensors

Submitted by Er-Wei Bai on Wed, 12/23/2015 - 2:04pm. Contributors:

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In this work, target or source localization and tracking by a network of primitive binary sensors under various imperfections are studied. Detailed analysis and mathematical modeling of imperfect binary sensors are presented. Imperfections include sensor failures of two types, uncertainty and heterogeneity in binary sensor trigger thresholds, presence of noise and non-radial symmetry of sensing ranges. Numerical algorithms for source localization and tracking are proposed along with convergence and asymptotic normality results.

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Visible to the public Architectural and Algorithmic Solutions for Large Scale PEV Integration into Power Grids

Submitted by Vijay Gupta on Wed, 12/23/2015 - 12:39pm. Contributors:

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This project designs algorithms for the integration of plug-in hybrid electric vehicles (PEVs) into the power grid. Specifically, the project will formulate and solve optimization problems critical to various entities in the PEV ecosystem -- PEV owners, commercial charging station owners, aggregators, and distribution companies -- at the distribution / retail level.

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Visible to the public Go-RealTime: Knowledge and Control of Time in High Level Programming Language

Submitted by rgupta on Tue, 12/22/2015 - 8:40pm. Contributors:

Abstract:

General purpose operating systems (OS) are concurrent and multithread, and the primary goal of thread scheduler is to enforce fairness among all threads. This design is unsuitable for Real-Time (RT) systems, because tasks have soft or hard deadline of finishing time. Concurrency breaks timing of RT applications because users never know when their program is actually running. Explicitly allocation of processor resource to programs (threads) is thus necessary for timing-aware applications.

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Visible to the public Converting Multi-Axis Machine Tools into Subtractive 3D Printers by using Intelligent Discrete Geometry Data Structures

Submitted by Thomas Kurfess on Tue, 12/22/2015 - 7:11pm. Contributors:

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The overarching goal of this project is to develop a novel cyberphysical platform for fast and efficient, fully digital, 3-dimensional, 5-axis machining. Proposed methodology is inspired by 3D printing, which is easy to program but limited in terms of the materials that can be used, the finishing quality that can be achieved, and relatively slow printing speeds. By contrast, CNC milling can address these limitations.

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Visible to the public Controller Design for Systems with Clock Offsets

Submitted by Joao Hespanha on Tue, 12/22/2015 - 6:32pm. Contributors:

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It's common in controller design to assume that the controller reads the sensors and writes to the actuators at the same time instant. This assumption is often violated in practice because the controller executes its code sequentially on a microprocessor. If the microprocessor is "fast enough," often the controller will still work.