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Fast increased fidelity samplers for approximate Bayesian Gaussian process regression
Gaussian processes (GPs) are common components in Bayesian non-parametric models having a rich methodological literature and strong theoretical grounding. The use of exact GPs in Bayesian models is limited to problems containing several thousand observations due to their prohibitive computational demands. We develop a posterior sampling algorithm using H-matrix approximations that scales at O(n log 2 n). We show that this approximation’s Kullback-Leibler divergence to the true posterior can be made arbitrarily small. Though multidimensional GPs could be used with our algorithm, d-dimensional surfaces are modeled as tensor products of univariate GPs to minimize the cost of matrix construction and maximize computational efficiency. We illustrate the performance of this fast increased fidelity approximate GP, FIFA-GP, using both simulated and non-synthetic data sets
MALA-within-Gibbs Samplers for High-Dimensional Distributions with Sparse Conditional Structure
Not provided.
Transitional Markov Chain Monte Carlo Sampler in UQTk
Transitional Markov Chain Monte Carlo (TMCMC) is a variant of a class of Markov Chain Monte Carlo algorithms known as tempering-based methods. In this report, the implementation of TMCMC in the Uncertainty Quantification Toolkit is investigated through the sampling of high-dimensional distributions, multi-modal distributions, and nonlinear manifolds. Furthermore, the Bayesian model evidence estimates obtained from TMCMC are tested on problems with known analytical solutions and shown to provide consistent results.
A Hierarchical Gibbs Sampler for Spatially Varying Multi-Regularization Image Reconstructions
This is a presentation for SIAM's (Society for Industrial and Applied Mathematics) conference on computational science and engineering. This presentation describes research on novel techniques to deblur images under a Bayesian framework. The title of the conference is SIAM Conference on Computational Science and Engineering (CSE21). This is a VIRTUAL conference; it was originally scheduled in Fort Worth, TX. The conference dates are March 1-5, 2021. The link to the conference's website is https://www.siam.org/conferences/cm/conference/cse21
Description and Use of SCALE Sampler Parametric Capability for Engineering Analysis and Optimization [Slides]
Abstract not provided.
High Volume Air Sampler (HVAS) Filter Media Folding and Vacuum Sealing Procedure
This procedure describes the method for folding of the HVAS filter media, vacuum chamber setup and operation for sealing in preparation for Gamma counting.
Building LDMS Samplers for Slingshot Switches
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Enabling depth resolved temporal resolved soil microbial sampling with novel vadose zone diffusion sampler
To address the difficulty in Earth system science in making time-course measurements of molecular signatures in soil biochemistry, we developed a soil stake system to sample and replace a defined soil analog medium, connected through hydraulic connectivity via perforated casings and modular inserts. We deployed these stakes to a site in Prosser, WA and measured microbial colonization of sterile sand-clay inserts enriched with N-acetyl-glucosamine at different depths over spring and summer. DNA and RNA analyses revealed distinct microbial recruitment and activity patterns. Inserts showed lower microbial diversity but higher abundance of Proteobacteriota and Bacteriota compared to native soils, alongside seasonal shifts in taxonomic and functional profiles. The soil stake system offers a novel approach for studying microbial dynamics across temporal and spatial scales.
Data Order Reduction for Performance Monitoring of Supercomputers via the Kokkos Tools Sampler Utility
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Performance of mark 1 sampler mechanisms
Sampling device evaluation from X-ray diffraction patterns
Cleanroom air sampler counts, categorizes, and records particle data
Light scattering particle counter monitors particles in a clean room. It categorizes and records the particles according to size and functions simultaneously in three separate areas. The counter uses a transducer head to transform light signals into electric signals.
Part 5 - Soil mechanics surface sampler - Lunar surface tests and results
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Filter cassette for high volume air sampler
Filter cassette eliminates or substantially reduces contamination of filter media by extraneous material and facilitates handling.
Electrons in quiet-time increases, samplers of conditions in the outer solar system
An explanation for quiet-time electron increases is proposed which predicts as the existence of a modulating region for cosmic ray particles lying at approximately 30 AU from the Sun.
Examination of the Surveyor 3 surface sampler scoop
The operation and external appearance of the surface sampling scoop are discussed. An attempt was made to measure the magnitude of the existing adhesion between the lunar soil and the various surfaces of the scoop.
Martian gas, soil sampler tested.
A gas chromatograph mass spectrometer (GCMS) is scheduled to be carried aboard the Mars Viking lander, which is to make a soft landing on the Martian surface. The GCMS has two distinct tasks including a sampling of the Martian atmosphere and an analysis of Martian soil. The instrument is designed to be highly sensitive. It can detect 0.1 part per million of organic compounds in the soil and from 10 to 100 parts per million of atmospheric constituents.