scholarly journals Smooth stochastic density field reconstruction

Author(s):  
M A Aragon-Calvo

Abstract We introduce a method for generating a continuous, mass-conserving and high-order differentiable density field from a discrete point distribution such as particles or haloes from an N-body simulation or galaxies from a spectroscopic survey. The method consists on generating an ensemble of point realizations by perturbing the original point set following the geometric constraints imposed by the Delaunay tessellation in the vicinity of each point in the set. By computing the mean field of the ensemble we are able to significantly reduce artifacts arising from the Delaunay tessellation in poorly sampled regions while conserving the features in the point distribution. Our implementation is based on the Delaunay Tessellation Field Estimation (DTFE) method, however other tessellation techniques are possible. The method presented here shares the same advantages of the DTFE method such as self-adaptive scale, mass conservation and continuity, while being able to reconstruct even the faintest structures of the point distribution usually dominated by artifacts in Delaunay-based methods. Additionally, we also present preliminary results of an application of this method to image denoising and artefact removal, highlighting the broad applicability of the technique introduced here.

2015 ◽  
Vol 50 (3) ◽  
pp. 228-239
Author(s):  
A. Spindler ◽  
J. Krampe

Continuous mass balancing defines a new standard in data quality validation. Likewise relying on the principles of mass conservation it outperforms long-term static mass balancing approaches because faults in data can be assigned to their time of occurrence. This research was carried out with practical application to routine operational data in mind and two major aspects are investigated to make this application feasible. Sludge concentrations of typically balanced components (chemical oxygen demand, total nitrogen, total phosphate) are not routinely measured in wastewater treatment plants. Therefore they need to be determined from alternative, more frequent measurements such as total suspended solids. To provide the necessary statistical basis for such determination, monthly sludge sampling was found sufficient. Further, contrary to long-term static mass balancing, the effects of delay between input and output loads must not be neglected in continuous mass balancing based on daily data. While a storage/release approach did not give the desired results, the consideration of hydraulic retention (first-order flow dynamics) fundamentally improved the performance of the proposed method.


2015 ◽  
Vol 805 (2) ◽  
pp. 121 ◽  
Author(s):  
Behnam Darvish ◽  
Bahram Mobasher ◽  
David Sobral ◽  
Nicholas Scoville ◽  
Miguel Aragon-Calvo

2020 ◽  
Author(s):  
Thanh Minh Nguyen ◽  
Jacob John Jeevan ◽  
Nuo Xu ◽  
Jake Chen

AbstractIn this work, we design the Polar Gini Curve (PGC) technique, which combines the gene expression and the 2D embedded visual information to detect biomarkers from single-cell data. Theoretically, a Polar Gini Curve characterizes the shape and ‘evenness’ of cell-point distribution of cell-point set. To quantify whether a gene could be a marker in a cell cluster, we can combine two Polar Gini Curves: one drawn upon the cell-points expressing the gene, and the other drawn upon all cell-points in the cluster. We hypothesize that the closers these two curves are, the more likely the gene would be cluster markers. We demonstrate the framework in several simulation case-studies. Applying our framework in analyzing neonatal mouse heart single-cell data, the detected biomarkers may characterize novel subtypes of cardiac muscle cells. The source code and data for PGC could be found at https://figshare.com/projects/Polar_Gini_Curve/76749.


2019 ◽  
Vol 28 (3) ◽  
pp. 521-528
Author(s):  
Xinlei Wei ◽  
Junping Du ◽  
Meiyu Liang ◽  
Zhe Xue

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