Algorithm Research and Development Group [PAGE UNDER DEVELOPMENT]

Welcome to the Algorithm Research and Development Group (ARDG) page on NRAO Wiki.

---

The Algorithms Research and Development Group (ARDG) was re-constructed and approved in 2018 under the NRAO's Data Management and Software (DMS) division. The group is tasked with developing a long-term road-map for algorithms R&D at NRAO, executing the approved road-map and distributing yearly progress report to the community. The proposed road-map is currently in discussion with the stakeholders and once finalized, it will be posted on this page.

This page is currently under construction and more details and information will be distributed via this page shortly.

Group Members

The total ARDG effort is about 2 FTE contribution from the functional time of the following staff members:

Sanjay Bhatnagar	Scientist	Group Lead	Reports to Head DMSD
Mingyu (Genie) Hsieh	Software Engg-IV		Reports to Lead ARDG
Preshanth Jagannathan	Assoc. Scientist		Reports to Lead ARDG
Brian Kirk	NRAO Student Intern/PhD Student		Reports to thesis supervisor (U. Rau)
Srikrishna Sekhar	NRAO-IDIA/SA Joint PDF		Reports to Lead ARDG/Director IDIA

Work in progress

Pointers to relevant documents

This is place holder for pointers to relevant documents related to ARDG.

ARDG Memos

Reference	Author(s)	Date
ngVLA Computing Memo No. 7	S. Bhatnagar, F. Madsen and J. Robnett	May 09, 2022
Same as ngVLA Comp. Memo No.7 with minor corrections in Figs. 1&2
ngVLA Draft Memo - Recommended Developments for Applying (W)Asp	M. Hsieh, S. Bhatnagar, R. Hiriart, M. Pokorny	Mar. 2022
Wide-band implementation of the Asp-Clean algorithm	M. Hsieh, U Rau & S. Bhatnagar	Mar. 2022
The design of the AWProject framework	S. Bhatnagar	Feb. 2022
High Performance Gridding	M. Pokorny	Aug. 31, 2021
Size-of-Computing Estimates for ngVLA Synthesis Imaging	S. Bhatnagar, R. Hiriart and M. Pokorny	Aug. 10, 2021
Full-Mueller Imaging with ALMA: ALMA Study Project report	S. Bhatnagar et al.	Feb. 2021
Narrow-band implementation of the Asp-Clean algorithm	M. Hsieh & S. Bhatnagar	Jan. 2021
VLASS Memo #15: VLASS Imaging Project: Proposed workflow	J. Tobin, J. Marvil, J. Ott, and S. Bhatnagar	May, 2020
Heterogeneous Pointing Corrections in AW-Projection	P. Jagannathan, S.Bhatnagar	Oct 2019
Building a model for antenna aperture illumination pattern	S.Sekhar, P.Jagannathan, B.Kirk, S.Bhatnagar and R.A.Taylor	Feb 2019
Wideband Mosaic Imaging for VLASS	U. Rau & S.Bhatnagar	Sep 2018

Talk Slides

Reference	Author(s)	Date
Synthesis Imaging with CASA	P. Jagannathan	Mar. 24, 2022
A to Z Solver Methodology	P. Jagannathan	Jan. 5, 2022
A Systems approach to Imaging and Calibration (a talk in the RCI Seminar Series)	S. Bhatnagar	Feb. 12, 2021
Algorithms R&D Update: Retrospective 2019 + Proposed plan 2020	S. Bhatnagar	Jan. 22, 2020
Understanding and using the AWProjection algorithm	S. Bhatnagar	Sept. 7, 2018

ARD Discussion Topics (dates and speakers TBD)

TOPIC	DESCRIPTION	DATE
Foundations of radio interferometric observations	Details of the measurement process in theory and in practice	MM/DD/YY
Demystification of post-processing: Understanding RA calibration and indirect imaging	Simplified description of the theoretical framework for calibration and imaging	MM/DD/YY
Quantization in the measurement chain	Understanding the effects of the inevitable quantization at various stages of the measurement, calibration & imaging process	MM/DD/YY
User-level understanding the algorithmic framework implementation in CASA	Mapping the theory to the data processing operations most users are familiar with	MM/DD/YY
Understanding connections between algorithms, imaging performance and computing load	Impact on run-time of the algorithmic choices, estimating what's needed when	MM/DD/YY
Deconvolution through the ages	A review and comparison of deconvolution algorithm formulations over the past 20yrs.	MM/DD/YY
Spectral Line Deconvolution	State of the art in line search algorithms and the need for joint deconvolution algorithms	MM/DD/YY
RFI mitigation	ngVLA study and other ideas to pursue at the VLA. Review of what other observatories do	MM/DD/YY
Faraday Rotation Synthesis	Review of methods and what would be useful to adopt here	MM/DD/YY
Wide-field Imaging	Review of methods such as AW-Projection, Different types of DD-cals, Using spherical geometry for W-term, etc	MM/DD/YY
Single Dish and Interferometer Combinations	State of the art and outstanding problems/requirements	MM/DD/YY
Generic HPC solver frameworks	Moving beyond our standard chi-square minimization and major/minor cycles for next gen algorithms	MM/DD/YY
Primary Beam Models	CASA's models, Zernicke models for ALMA/VLA/MeerKAT, Review of other approaches, guidelines for what a good model is	MM/DD/YY
Full Mueller Imaging	Review of methods, explanation of Full Mueller Imaging vs what is usually described as Full-Stokes Imaging	MM/DD/YY
Machine Learning Applications	Do we have use cases where Machine Learning and AI will halp ?	MM/DD/YY
Pipeline Heuristics	Invite SRDP/ALMA/VLA pipeline folk to describe top heuristics they depend on plus unsolved algorithmic problems they face	MM/DD/YY
Simulations in CASA	Going beyond simobserve.	MM/DD/YY

Relevant Scientific Publications

Software Packages

The ARDG staff conducts majority of their R&D using the CASA package.

• wide-band implementation of of the Asp-Clean algorithm: WAsp.pdf

• Memo for ngVLA-38: Recommended Developments Necessary for Applying WAsp to ngVLA: ngvla_wasp.pdf