76,974 research outputs found
Feasibility of using the Massively Parallel Processor for large eddy simulations and other Computational Fluid Dynamics applications
The results of an investigation into the feasibility of using the MPP for direct and large eddy simulations of the Navier-Stokes equations is presented. A major part of this study was devoted to the implementation of two of the standard numerical algorithms for CFD. These implementations were not run on the Massively Parallel Processor (MPP) since the machine delivered to NASA Goddard does not have sufficient capacity. Instead, a detailed implementation plan was designed and from these were derived estimates of the time and space requirements of the algorithms on a suitably configured MPP. In addition, other issues related to the practical implementation of these algorithms on an MPP-like architecture were considered; namely, adaptive grid generation, zonal boundary conditions, the table lookup problem, and the software interface. Performance estimates show that the architectural components of the MPP, the Staging Memory and the Array Unit, appear to be well suited to the numerical algorithms of CFD. This combined with the prospect of building a faster and larger MMP-like machine holds the promise of achieving sustained gigaflop rates that are required for the numerical simulations in CFD
Do Android Taint Analysis Tools Keep Their Promises?
In recent years, researchers have developed a number of tools to conduct
taint analysis of Android applications. While all the respective papers aim at
providing a thorough empirical evaluation, comparability is hindered by varying
or unclear evaluation targets. Sometimes, the apps used for evaluation are not
precisely described. In other cases, authors use an established benchmark but
cover it only partially. In yet other cases, the evaluations differ in terms of
the data leaks searched for, or lack a ground truth to compare against. All
those limitations make it impossible to truly compare the tools based on those
published evaluations.
We thus present ReproDroid, a framework allowing the accurate comparison of
Android taint analysis tools. ReproDroid supports researchers in inferring the
ground truth for data leaks in apps, in automatically applying tools to
benchmarks, and in evaluating the obtained results. We use ReproDroid to
comparatively evaluate on equal grounds the six prominent taint analysis tools
Amandroid, DIALDroid, DidFail, DroidSafe, FlowDroid and IccTA. The results are
largely positive although four tools violate some promises concerning features
and accuracy. Finally, we contribute to the area of unbiased benchmarking with
a new and improved version of the open test suite DroidBench
Architectural Information Modelling in Construction History
The past few years show a significant increase in the usage of three-dimensional modelling and semantic description techniques for architectural research purposes. Where this increase has already shaped today’s design and construction industry, research in architectural and construction history can still improve its work methods and results through these techniques. Therefore, we propose a new conceptual approach for Architectural Information Modelling (AIM), which aims at describing historical information in construction and architecture directly related to design information and design practice. This paper will give an introduction into existing 3D modelling techniques and semantic description techniques, continuing with how these techniques are applied in the AIM approach. This investigation of 3D modelling and semantic technology shows promising results. However, in order to integrate these techniques into an AIM framework, more work is needed. Future work in this research project will therefore explore in further detail the semantic description scheme proposed below and the implementation of a proof-of-concept
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