3,689 research outputs found
An Investigation of a Dustless System of Dry Drilling
For many years the problem of removing dust particles while drilling dry has confronted the mining and construction industries. In areas where water is not available, rock drilling is still being done under hazardous dust conditions. It was in an attempt to find a partial solution to this problem that the material contained in this report was compounded
Stability of a horizontal viscous fluid layer in a vertical time periodic electric field
The stability of a horizontal interface between two viscous fluids, one of
which is conducting and the other is dielectric, acted upon by a vertical
time-periodic electric field is considered. The two fluids are bounded by
electrodes separated by a finite distance. By means of Floquet theory, the
marginal stability curves are obtained, thereby elucidating the dependency of
the critical voltage and wavenumber upon the fluid viscosities. The limit of
vanishing viscosities is shown to be in excellent agreement with the marginal
stability curves predicted by means of a Mathieu equation. The methodology to
obtain the marginal stability curves developed here is applicable to any
arbitrary but time periodic-signal, as demonstrated for the case of a signal
with two different frequencies. As a special case, the marginal stability
curves for an applied ac voltage biased by a dc voltage are depicted. It is
shown that the mode coupling caused by the normal stress at the interface due
to the electric field leads to appearance of harmonic modes and subharmonic
modes. This is in contrast to the application of a voltage with a single
frequency which always leads to a harmonic mode. Whether a harmonic or
subharmonic mode is the most unstable one depends on details of the excitation
signal. It is also shown that the electrode spacing has a distinct effect on
the stability bahavior of the system
Paradoxes in Fair Computer-Aided Decision Making
Computer-aided decision making--where a human decision-maker is aided by a
computational classifier in making a decision--is becoming increasingly
prevalent. For instance, judges in at least nine states make use of algorithmic
tools meant to determine "recidivism risk scores" for criminal defendants in
sentencing, parole, or bail decisions. A subject of much recent debate is
whether such algorithmic tools are "fair" in the sense that they do not
discriminate against certain groups (e.g., races) of people.
Our main result shows that for "non-trivial" computer-aided decision making,
either the classifier must be discriminatory, or a rational decision-maker
using the output of the classifier is forced to be discriminatory. We further
provide a complete characterization of situations where fair computer-aided
decision making is possible
Language Barriers in Health Care Settings: An Annotated Bibliography of Research Literature
Provides an overview of resources related to the prevalence, role, and effects of language barriers and access in health care
Pain in Active Pathologic Processes in Stomach or Duodenum: Gastric and Duodenal Contractions as the Direct Cause
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Private Multiplicative Weights Beyond Linear Queries
A wide variety of fundamental data analyses in machine learning, such as
linear and logistic regression, require minimizing a convex function defined by
the data. Since the data may contain sensitive information about individuals,
and these analyses can leak that sensitive information, it is important to be
able to solve convex minimization in a privacy-preserving way.
A series of recent results show how to accurately solve a single convex
minimization problem in a differentially private manner. However, the same data
is often analyzed repeatedly, and little is known about solving multiple convex
minimization problems with differential privacy. For simpler data analyses,
such as linear queries, there are remarkable differentially private algorithms
such as the private multiplicative weights mechanism (Hardt and Rothblum, FOCS
2010) that accurately answer exponentially many distinct queries. In this work,
we extend these results to the case of convex minimization and show how to give
accurate and differentially private solutions to *exponentially many* convex
minimization problems on a sensitive dataset
Embedding Principal Component Analysis for Data Reductionin Structural Health Monitoring on Low-Cost IoT Gateways
Principal component analysis (PCA) is a powerful data reductionmethod for
Structural Health Monitoring. However, its computa-tional cost and data memory
footprint pose a significant challengewhen PCA has to run on limited capability
embedded platformsin low-cost IoT gateways. This paper presents a
memory-efficientparallel implementation of the streaming History PCA
algorithm.On our dataset, it achieves 10x compression factor and 59x
memoryreduction with less than 0.15 dB degradation in the
reconstructedsignal-to-noise ratio (RSNR) compared to standard PCA. More-over,
the algorithm benefits from parallelization on multiple cores,achieving a
maximum speedup of 4.8x on Samsung ARTIK 710
Structural Change for a Post-Growth Economy: Investigating the Relationship between Embodied Energy Intensity and Labour Productivity
Post-growth economists propose structural changes towards labour-intensive services, such as care or education, to make our economy more sustainable by providing meaningful work and reducing the environmentally damaging production of material goods. Our study investigates the assumption underlying such proposals. Using a multi-regional input-output model we compare the embodied energy intensity and embodied labour productivity across economic sectors in the UK and Germany between 1995 and 2011. We identify five labour-intensive service sectors, which combine low embodied energy intensity with low growth in embodied labour productivity. However, despite their lower embodied energy intensities, our results indicate that large structural changes towards these sectors would only lead to small reductions in energy footprints. Our results also suggest that labour-intensive service sectors in the UK have been characterised by higher rates of price inflation than other sectors. This supports suggestions from the literature that labour-intensive services face challenges from increasing relative prices and costs. We do not find similar results for Germany, which is the result of low overall growth in embodied labour productivity and prices. This highlights that structural change is closely associated with economic growth, which raises the question of how structural changes can be achieved in a non-growing economy
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