24,442 research outputs found
Motivation, Design, and Ubiquity: A Discussion of Research Ethics and Computer Science
Modern society is permeated with computers, and the software that controls
them can have latent, long-term, and immediate effects that reach far beyond
the actual users of these systems. This places researchers in Computer Science
and Software Engineering in a critical position of influence and
responsibility, more than any other field because computer systems are vital
research tools for other disciplines. This essay presents several key ethical
concerns and responsibilities relating to research in computing. The goal is to
promote awareness and discussion of ethical issues among computer science
researchers. A hypothetical case study is provided, along with questions for
reflection and discussion.Comment: Written as central essay for the Computer Science module of the
LANGURE model curriculum in Research Ethic
A Domain Specific Approach to High Performance Heterogeneous Computing
Users of heterogeneous computing systems face two problems: firstly, in
understanding the trade-off relationships between the observable
characteristics of their applications, such as latency and quality of the
result, and secondly, how to exploit knowledge of these characteristics to
allocate work to distributed computing platforms efficiently. A domain specific
approach addresses both of these problems. By considering a subset of
operations or functions, models of the observable characteristics or domain
metrics may be formulated in advance, and populated at run-time for task
instances. These metric models can then be used to express the allocation of
work as a constrained integer program, which can be solved using heuristics,
machine learning or Mixed Integer Linear Programming (MILP) frameworks. These
claims are illustrated using the example domain of derivatives pricing in
computational finance, with the domain metrics of workload latency or makespan
and pricing accuracy. For a large, varied workload of 128 Black-Scholes and
Heston model-based option pricing tasks, running upon a diverse array of 16
Multicore CPUs, GPUs and FPGAs platforms, predictions made by models of both
the makespan and accuracy are generally within 10% of the run-time performance.
When these models are used as inputs to machine learning and MILP-based
workload allocation approaches, a latency improvement of up to 24 and 270 times
over the heuristic approach is seen.Comment: 14 pages, preprint draft, minor revisio
Analysis of Three-Dimensional Protein Images
A fundamental goal of research in molecular biology is to understand protein
structure. Protein crystallography is currently the most successful method for
determining the three-dimensional (3D) conformation of a protein, yet it
remains labor intensive and relies on an expert's ability to derive and
evaluate a protein scene model. In this paper, the problem of protein structure
determination is formulated as an exercise in scene analysis. A computational
methodology is presented in which a 3D image of a protein is segmented into a
graph of critical points. Bayesian and certainty factor approaches are
described and used to analyze critical point graphs and identify meaningful
substructures, such as alpha-helices and beta-sheets. Results of applying the
methodologies to protein images at low and medium resolution are reported. The
research is related to approaches to representation, segmentation and
classification in vision, as well as to top-down approaches to protein
structure prediction.Comment: See http://www.jair.org/ for any accompanying file
Internet Predictions
More than a dozen leading experts give their opinions on where the Internet is headed and where it will be in the next decade in terms of technology, policy, and applications. They cover topics ranging from the Internet of Things to climate change to the digital storage of the future. A summary of the articles is available in the Web extras section
Reliability analysis of structural ceramic components using a three-parameter Weibull distribution
Described here are nonlinear regression estimators for the three-Weibull distribution. Issues relating to the bias and invariance associated with these estimators are examined numerically using Monte Carlo simulation methods. The estimators were used to extract parameters from sintered silicon nitride failure data. A reliability analysis was performed on a turbopump blade utilizing the three-parameter Weibull distribution and the estimates from the sintered silicon nitride data
Numerical simulation of liquid sloshing in LNG tanks using a compressible two-fluid flow model
In this investigation the Reynolds-Averaged Navier-Stokes (RANS)
equations are modified to account for variable density and viscosity of
the two-fluids flow (i.e. water-air), assuming both fluids compressible.
By introducing a preconditioner, the governing equations in terms of
primitive variables are solved for both fluids in a unified manner. The
non-conservative implicit Split Coefficient Matrix Method (SCMM) is
modified to approximate convective flux vectors in the dual time
formulation. The free surface waves inside the tank, due to sloshing, are
implicitly captured by using a level set approach.
The method is illustrated through applications to rectangular and
chamfered tanks subject to sway or roll motions at different filling
levels and excitation conditions (i.e. amplitude and frequency of
oscillation). Comparisons are made between calculated and
experimental pressures, where available
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