Time and Date: 11:00 - 12:40 on 11th June 2014
Room: Tully II
Chair: Abani Patra
|80|| A posteriori error estimates for DDDAS inference problems [abstract]
Abstract: Inference problems in dynamically data-driven application systems use physical measurements along with a physical model to estimate the parameters or state of a physical system. Errors in measurements and uncertainties in the model lead to inaccurate inference results. This work develops a methodology to estimate the impact of various errors on the variational solution of a DDDAS inference problem. The methodology is based on models described by ordinary differential equations, and use first-order and second-order adjoint methodologies. Numerical experiments with the heat equation illustrate the use of the proposed error estimation machinery.
|Vishwas Hebbur Venkata Subba Rao, Adrian Sandu|
|162|| Mixture Ensembles for Data Assimilation in Dynamic Data-Driven Environmental Systems [abstract]
Abstract: Many inference problems in environmental DDDAS must contend with high dimensional models and non-Gaussian uncertainties, including but not limited to Data Assimilation, Targeting and Planning. In this this paper, we present the Mixture Ensemble Filter (MEnF) which extends ensemble filtering to non-Gaussian inference using Gaussian mixtures. In contrast to the state of the art, MEnF embodies an exact update equation that neither requires explicit calculation of mixture element moments nor ad-hoc association rules between ensemble members and mixture elements. MEnF is applied to the chaotic Lorenz-63 model and to a chaotic soliton model that allows idealized and systematic studies of localized phenomena. In both cases, MEnF outperforms contemporary approaches, and replaces ad-hoc Gaussian Mixture approaches for non-Gaussian inference.
|Piyush Tagade, Hansjorg Seybold, Sai Ravela|
|169|| Optimizing Dynamic Resource Allocation [abstract]
Abstract: We present a formulation, solution method, and program acceleration techniques for two dynamic control scenarios, both with the common goal of optimizing resource allocations. These approaches allocate resources in a non-myopic way, accounting for long-term impacts of current control decisions via nominal belief-state optimization (NBO). In both scenarios, the solution techniques are parallelized for reduced execution time. A novel aspect is included in the second scenario: dynamically allocating the computational resources in an online fashion which is made possible through constant aspect ratio tiling (CART).
|Lucas Krakow, Louis Rabiet, Yun Zou, Guillaume Iooss, Edwin Chong, Sanjay Rajopadhye|
|165|| A Dataflow Programming Language and Its Compiler for Streaming Systems [abstract]
Abstract: The dataflow programming paradigm shows an important way to improve the programming productivity for domain experts. In this position paper we propose COStream,a programming language that is based on synchronization dataflow execution model for application. We also propose a compiler framework for COStream on multi-core architecture. In the compiler, we use an inter-thread software pipelining schedule to exploit the parallelism among the cores. We implement the COStream compiler framework on x86 multi-core architecture and perform the experiments to evaluate the system.
|Haitao Wei, Stephane Zuckerman, Xiaoming Li, Guang Gao|
|280|| Static versus Dynamic Data Information Fusion analysis using DDDAS for Cyber Security Trust [abstract]
Abstract: Information fusion includes signals, features, and decision-level analysis over various types of data including imagery, text, and cyber security detection. With the maturity of data processing, the explosion of big data, and the need for user acceptance; the Dynamic Data-Driven Application System (DDDAS) philosophy fosters insights into the usability of information systems solutions. In this paper, we explore a notion of an adaptive adjustment of secure communication trust analysis that seeks a balance between standard static solutions versus dynamic-data driven updates. A use case is provided in determining trust for a cyber security scenario exploring comparisons of Bayesian versus evidential reasoning for dynamic security detection updates. Using the evidential reasoning proportional conflict redistribution (PCR) method, we demonstrate improved trust for dynamically changing detections of denial of service attacks.
|Erik Blasch, Youssif Al-Nashif, Salim Hariri|