982 research outputs found
Compositional Semantics for Probabilistic Programs with Exact Conditioning
We define a probabilistic programming language for Gaussian random variables
with a first-class exact conditioning construct. We give operational,
denotational and equational semantics for this language, establishing
convenient properties like exchangeability of conditions. Conditioning on
equality of continuous random variables is nontrivial, as the exact observation
may have probability zero; this is Borel's paradox. Using categorical
formulations of conditional probability, we show that the good properties of
our language are not particular to Gaussians, but can be derived from universal
properties, thus generalizing to wider settings. We define the Cond
construction, which internalizes conditioning as a morphism, providing general
compositional semantics for probabilistic programming with exact conditioning.Comment: 16 pages, 5 figure
Shaping contactless forces through anomalous acoustic scattering
Waves impart momentum and exert force on obstacles in their path. The
transfer of wave momentum is a fundamental mechanism for contactless
manipulation, yet the rules of conventional scattering intrinsically limit the
radiation force based on the shape and the size of the manipulated object.
Here, we show that this intrinsic limit can be overcome for acoustic waves with
subwavelength-structured metasurfaces, where the force becomes controllable by
the arrangement of surface features, independent of the object's overall shape
and size. Harnessing such anomalous metasurface scattering, we demonstrate
complex actuation phenomena: self-guidance, where a metasurface object is
autonomously guided by an acoustic wave, and contactless pulling, where a
metasurface object is pulled by the wave. Our results show that bringing
metasurface physics, and its full arsenal of tools, to the domain of mechanical
manipulation opens the door to diverse actuation mechanisms that are beyond the
limits of traditional wave-matter interactions
Probabilistic Programming Semantics for Name Generation
We make a formal analogy between random sampling and fresh name generation.
We show that quasi-Borel spaces, a model for probabilistic programming, can
soundly interpret Stark's -calculus, a calculus for name generation.
Moreover, we prove that this semantics is fully abstract up to first-order
types. This is surprising for an 'off-the-shelf' model, and requires a novel
analysis of probability distributions on function spaces. Our tools are diverse
and include descriptive set theory and normal forms for the -calculus.Comment: 29 pages, 1 figure; to be published in POPL 202
Effectiveness of Aerobic Exercise for Adults with Leukemia
We wanted to look at the most effective interventions for increasing strength and endurance in clients with Leukemia experiencing functional decline
The Beta-Bernoulli process and algebraic effects
In this paper we use the framework of algebraic effects from programming language theory to analyze the Beta-Bernoulli process, a standard building block in Bayesian models. Our analysis reveals the importance of abstract data types, and two types of program equations, called commutativity and discardability. We develop an equational theory of terms that use the Beta-Bernoulli process, and show that the theory is complete with respect to the measure-theoretic semantics, and also in the syntactic sense of Post. Our analysis has a potential for being generalized to other stochastic processes relevant to Bayesian modelling, yielding new understanding of these processes from the perspective of programming
2015 AFRL University Design Challenge
The University of Akron’s Air Force Research Laboratory’s Design Challenge Team has engineered a Heat Stress Prevention Kit that includes a facial mask in which the soldier will cool down from the inside out by breathing in the cool air circulating throughout the mask. This cool air is produced from a thermoelectric chip, which has a specific temperature difference on either side, one hot and one cold. Each of the sides is isolated from one another and with the combination of heat sinks, fans, and the simple process of breathing, a system is created by inhaling cool air. The entire system is powered and controlled by a power source including two LiPo batteries, an Arduino Uno Circuit Board, and a relay all encased in an external pouch which can attach to any Molle strap system. A bonus feature to this mask system is it can be turned into a Hypothermia Prevention Kit by switching the wires or the voltage of the thermoelectric chip
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