1,512 research outputs found
Modeling a Sensor to Improve its Efficacy
Robots rely on sensors to provide them with information about their
surroundings. However, high-quality sensors can be extremely expensive and
cost-prohibitive. Thus many robotic systems must make due with lower-quality
sensors. Here we demonstrate via a case study how modeling a sensor can improve
its efficacy when employed within a Bayesian inferential framework. As a test
bed we employ a robotic arm that is designed to autonomously take its own
measurements using an inexpensive LEGO light sensor to estimate the position
and radius of a white circle on a black field. The light sensor integrates the
light arriving from a spatially distributed region within its field of view
weighted by its Spatial Sensitivity Function (SSF). We demonstrate that by
incorporating an accurate model of the light sensor SSF into the likelihood
function of a Bayesian inference engine, an autonomous system can make improved
inferences about its surroundings. The method presented here is data-based,
fairly general, and made with plug-and play in mind so that it could be
implemented in similar problems.Comment: 18 pages, 8 figures, submitted to the special issue of "Sensors for
Robotics
Information-Based Physics: An Observer-Centric Foundation
It is generally believed that physical laws, reflecting an inherent order in
the universe, are ordained by nature. However, in modern physics the observer
plays a central role raising questions about how an observer-centric physics
can result in laws apparently worthy of a universal nature-centric physics.
Over the last decade, we have found that the consistent apt quantification of
algebraic and order-theoretic structures results in calculi that possess
constraint equations taking the form of what are often considered to be
physical laws. I review recent derivations of the formal relations among
relevant variables central to special relativity, probability theory and
quantum mechanics in this context by considering a problem where two observers
form consistent descriptions of and make optimal inferences about a free
particle that simply influences them. I show that this approach to describing
such a particle based only on available information leads to the mathematics of
relativistic quantum mechanics as well as a description of a free particle that
reproduces many of the basic properties of a fermion. The result is an approach
to foundational physics where laws derive from both consistent descriptions and
optimal information-based inferences made by embedded observers.Comment: To be published in Contemporary Physics. The manuscript consists of
43 pages and 9 Figure
Objectively Measured Physical Activity Varies by Task and Accelerometer Location in Younger and Older Adults
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Improved Parallel Rabin-Karp Algorithm Using Compute Unified Device Architecture
String matching algorithms are among one of the most widely used algorithms
in computer science. Traditional string matching algorithms efficiency of
underlaying string matching algorithm will greatly increase the efficiency of
any application. In recent years, Graphics processing units are emerged as
highly parallel processor. They out perform best of the central processing
units in scientific computation power. By combining recent advancement in
graphics processing units with string matching algorithms will allows to speed
up process of string matching. In this paper we proposed modified parallel
version of Rabin-Karp algorithm using graphics processing unit. Based on that,
result of CPU as well as parallel GPU implementations are compared for
evaluating effect of varying number of threads, cores, file size as well as
pattern size.Comment: Information and Communication Technology for Intelligent Systems
(ICTIS 2017
Energy Balance during Postpartum Period is Associated with Metabolic Adaptation
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Greater Forearm Blood Flow is Associated With Higher Physical Activity in Older Individuals
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GraCT: A Grammar based Compressed representation of Trajectories
We present a compressed data structure to store free trajectories of moving
objects (ships over the sea, for example) allowing spatio-temporal queries. Our
method, GraCT, uses a -tree to store the absolute positions of all objects
at regular time intervals (snapshots), whereas the positions between snapshots
are represented as logs of relative movements compressed with Re-Pair. Our
experimental evaluation shows important savings in space and time with respect
to a fair baseline.Comment: This research has received funding from the European Union's Horizon
2020 research and innovation programme under the Marie Sk{\l}odowska-Curie
Actions H2020-MSCA-RISE-2015 BIRDS GA No. 69094
Origin of Complex Quantum Amplitudes and Feynman's Rules
Complex numbers are an intrinsic part of the mathematical formalism of
quantum theory, and are perhaps its most mysterious feature. In this paper, we
show that the complex nature of the quantum formalism can be derived directly
from the assumption that a pair of real numbers is associated with each
sequence of measurement outcomes, with the probability of this sequence being a
real-valued function of this number pair. By making use of elementary symmetry
conditions, and without assuming that these real number pairs have any other
algebraic structure, we show that these pairs must be manipulated according to
the rules of complex arithmetic. We demonstrate that these complex numbers
combine according to Feynman's sum and product rules, with the modulus-squared
yielding the probability of a sequence of outcomes.Comment: v2: Clarifications, and minor corrections and modifications. Results
unchanged. v3: Minor changes to introduction and conclusio
Greater Energy Cost During Standardized Walking is Associated With Diminished Fitness in Older Adults
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