Publications & Research Presentations

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Data Analytics for Commercial Buildings

Energy Management and Information Systems to Improve Operational Efficiency

Publications and Research Presentations

2021

Chen, Yimin, Guanjing Lin, Eliot Crowe, and Jessica Granderson."Development of a Unified Taxonomy for HVAC System Faults."Energies 14 (2021).
Touzani, Samir, Marc Wudunn, Samuel Fernandes, Avideh Zakhor, Rohullah Najibi, and Jessica Granderson."A MACHINE LEARNING APPROACH TO ESTIMATE WINDOWS-TO-WALL RATIO USING DRONE IMAGER." (2021).
Luo, Na, Marco Pritoni, and Tianzhen Hong."An overview of data tools for representing and managing building information and performance data."Renewable and Sustainable Energy Reviews 147 (2021) 111224. DOI
Granderson, Jessica, Mrinalini Sharma, Eliot Crowe, David A. Jump, Samuel Fernandes, Samir Touzani, and Devan Johnson."Assessment of Model-Based Peak Electric Consumption Prediction for Commercial Buildings."Energy and Building 245 (2021). DOI
Walker, Iain S., Brennan Less, David M. Lorenzetti, and Michael D. Sohn."Development of Advanced Smart Ventilation Controls for Residential Applications."Energies (2021). DOI
Touzani, Samir, and Jessica Granderson."Open Data and Deep Semantic Segmentation for Automated Extraction of Building Footprints."Remote Sensing Vol.13 No..2578 (2021). DOI
Lin, Guanjing, Marco Pritoni, Yimin Chen, Christopher Weyandt, Raphael Vitti, and Jessica Granderson."Fault “Auto-correction” for HVAC Systems: A Preliminary Study."The 6th International High Performance Buildings Conference at Purdue (2021).
Satchwell, Andrew, Mary Ann Piette, Aditya Khandekar, Jessica Granderson, Natalie Mims Frick, Ryan Hledik, Ahmad Faruqui, Long Lam, Stephanie Ross, Jesse Cohen, Kitty Wang, Daniela Urigwe, Dan Delurey, Monica Neukomm, and David Nemtzow."A National Roadmap for Grid-Interactive Efficient Buildings." (2021).
Ferrando, Martina, Tianzhen Hong, and Francesco Causone."A simulation-based assessment of technologies to reduce heat emissions from buildings."Building and Environment 195 (2021) 107772. DOI
Kim, Janghyun, Kim Trenbath, Jessica Granderson, Yimin Chen, Eliot Crowe, Hayden Reeve, Sarah Newman, and Paul Ehrlich."Research challenges and directions in HVAC fault prevalence."Science and Technology for the Built Environment 27 (2021). DOI
Li, Haoran, Juan Hou, Tianzhen Hong, Yuemin Ding, and Natasa Nord."Energy, economic, and environmental analysis of integration of thermal energy storage into district heating systems using waste heat from data centres."Energy 219 (2021) 119582. DOI

2020

Granderson, Jessica, Samuel Fernandes, Samir Touzani, Chih-Cheng Lee, Eliot Crowe, and Margaret Sheridan."Spatio-temporal impacts of a utility’s efficiency portfolio on the distribution grid."Energy 212.118669 (2020). DOI
Crowe, Eliot, Evan Mills, Tom Poeling, Claire Curtin, Diana Bjornskov, Liz Fischer, and Jessica Granderson."Building Commissioning Costs and Savings Across Three Decades and 1,500 North American Buildings."Energy and Buildings 227.110408 (2020). DOI
Luo, Xuan, Pouya Vahmani, Tianzhen Hong, and Andrew Jones."City-Scale Building Anthropogenic Heating during Heat Waves."Atmosphere 11.11 (2020) 1206. DOI
Fierro, Gabe, Anand Prakash, Cory Mosiman, Marco Pritoni, Paul Raftery, Michael Wetter, and David Culler."Interactive Metadata Integration with Brick."BuildSys '20: Proceedings of the 7th ACM International Conference on Systems for Energy-Efficient Buildings, Cities, and Transportation (2020). DOI
Hong, Tianzhen, Martina Ferrando, Xuan Luo, and Francesco Causone."Modeling and analysis of heat emissions from buildings to ambient air."Applied Energy 277 (2020) 115566. DOI
Bergmann, Harry, Cory Mosiman, Avijit Saha, Selam Haile, William Livingood, Steven Bushby, Gabe Fierro, Joel Bender, Michael Poplawski, Jessica Granderson, and Marco Pritoni."Semantic Interoperability to Enable Smart, Grid-Interactive Efficient Buildings."2020 Summer Study on Energy Efficiency in Buildings (2020). DOI
Kramer, , Hannah, Claire Curtin, Guanjing Lin, Eliot Crowe, and Jessica Granderson."Proving the Business Case for Building Analytics." (2020). DOI
Zhang, Kun, David H. Blum, Milica Grahovac, Jianjun Hu, Jessica Granderson, and Michael Wetter."Development and Verification of Control Sequences for Single- Zone Variable Air Volume System Based on ASHRAE Guideline 36."American Modelica Conference 2020 (2020). DOI
Pritoni, Marco, Anand Prakash, David H. Blum, Kun Zhang, Rui Tang, and Jessica Granderson."Advanced control sequences and FDD technology. Just shiny objects, or ready for scale?."ACEEE Summer Study 2020 (2020). DOI
Lin, Guanjing, Marco Pritoni, Yimin Chen, Jessica Granderson, Ricardo Moromisato, and Stephen Kozlen."Can We Fix It Automatically? Development of Fault Auto-Correction Algorithms for HVAC and Lighting Systems."ACEEE Summer Study (2020). DOI
Singh, Reshma, Anand Prakash, Mary Ann Piette, and Shreya Agarwal."A Community Energy Operations and Planning System: Concept, Use cases, Metrics, and Benefits."The American Council for an Energy-Efficient Economy (2020).
Casillas, Armando, Guanjing Lin, and Jessica Granderson."Curation of Ground-Truth Validated Benchmarking Datasets for Fault Detection & Diagnostics Tools."2020 ACEEE Summer Study (2020). DOI
Fernandes, Samuel, Eliot Crowe, Samir Touzani, and Jessica Granderson."Detecting the undetected: Dealing with non-routine events using advanced M&V meter-based savings approaches."ACEEE Summer Study on Energy Efficiency in Buildings (2020). DOI
Touzani, Samir, Marc Wudunn, Avideh Zakhor, Marco Pritoni, Reshma Singh, Harry Bergmann, and Jessica Granderson."Machine Learning for Automated Extraction of Building Geometry."The American Council for an Energy-Efficient Economy (2020).
Chen, Yimin, Eliot Crowe, Guanjing Lin, and Jessica Granderson."What's in a Name? Developing a Standardized Taxonomy for HVAC System Faults."2020 ACEEE Summer Study on Energy Efficiency in Buildings (2020). DOI
Granderson, Jessica, Eliot Crowe, Samir Touzani, and Samuel Fernandes."Meter-Based Assessment of the Time and Locational Benefits of a Large Utility’s DSM Portfolio."2020 Summer Study on Energy Efficiency in Buildings (2020).
WuDunn, Mark, Avideh Zakhor, Samir Touzani, and Jessica Granderson."​Aerial 3D Building Reconstruction from RGB Drone Imagery."SPIE Geospatial Informatics X (2020).
Lin, Guanjing, Marco Pritoni, Yimin Chen, and Jessica Granderson."Development and Implementation of Fault-Correction Algorithms in Fault Detection and Diagnostics Tools."Energies 13 (2020). DOI
Granderson, Jessica, Guanjing Lin, Ari Harding, Piljae Im, and Yan Chen."Building fault detection data to aid diagnostic algorithm creation and performance testing."Nature: Scientific Data Vol.7 No.65 (2020).
Kramer, Hannah, Rui Tang, Richard E. Brown, Claire Curtin, and Jessica Granderson."Market Brief: Customer-sited Distributed Energy Resources." (2020). DOI
Lin, Guanjing, Hannah Kramer, and Jessica Granderson."Building fault detection and diagnostics: Achieved savings, and methods to evaluate algorithm performance."Building and Environment 168 (2020) 106505. DOI
Prakash, Anand, Samir Touzani, Mariam Kiran, Shreya Agarwal, Marco Pritoni, and Jessica Granderson."Deep Reinforcement Learning in Buildings: Implicit Assumptions and their Impact."RLEM'20: Proceedings of the 1st International Workshop on Reinforcement Learning for Energy Management in Buildings & Cities (2020). DOI

2019

Granderson, Jessica, Samir Touzani, Eliot Crowe, Samuel Fernandes, Shankar Earni, and Kaiyu Sun."Realizing high-accuracy low-cost measurement and verification for deep cost savings." (2019). DOI
Langevin, Jared, Chioke B. Harris, and Janet L. Reyna."Assessing the Potential to Reduce U.S. Building CO2 Emissions 80% by 2050."Joule (2019). DOI
Singh, Reshma, Paul A. Mathew, Jessica Granderson, and Yash Shukla."Energy Information Systems: From the Basement to the Boardroom." (2019). DOI
Crowe, Eliot, Jessica Granderson, and Samuel Fernandes."From Theory to Practice: Lessons Learned from an Advanced M&V Commercial Pilot."International Energy Program Evaluation Conference (2019).
Singh, Reshma, Baptiste Ravache, and Mary Ann Piette."Energy Modeling in Urban Districts: Forecast of multi-sector Energy Use and GHG Emissions." (2019).
Touzani, Samir, Jessica Granderson, David A. Jump, and Derrick Rebello."Evaluation of Methods to Assess the Uncertainty in Estimated Energy Savings."Energy and Buildings 193 (2019). DOI
Frank, Stephen, Guanjing Lin, Xin Jin, Rupam Singla, Amanda Farthing, and Jessica Granderson."A performance evaluation framework for building fault detection and diagnosis algorithms."Energy and Buildings 192 (2019) 84 - 92. DOI
Kramer, Hannah, Guanjing Lin, Claire Curtin, Eliot Crowe, and Jessica Granderson."Building analytics and monitoring-based commissioning: industry practice, costs, and savings."Energy Efficiency (2019). DOI
Hu, R. L., Jessica Granderson, David M. Auslander, and Alice M. Agogino."Design of machine learning models with domain experts for automated sensor selection for energy fault detection."Applied Energy 235 (2019) 117 - 128. DOI
Blum, David H., K. Arendt, Lisa Rivalin, Mary Ann Piette, Michael Wetter, and C.T. Veje."Practical factors of envelope model setup and their effects on the performance of model predictive control for building heating, ventilating, and air conditioning systems."Applied Energy 236 (2019) 410 - 425. DOI
Granderson, Jessica, Guanjing Lin, David H. Blum, Janie Page, Michael Spears, and Mary Ann Piette."Integrating diagnostics and model-based optimization."Energy and Buildings 182 (2019) 187 - 195. DOI
Touzani, Samir, Baptiste Ravache, Eliot Crowe, and Jessica Granderson."Statistical change detection of building energy consumption: Applications to savings estimation."Energy and Buildings 185 (2019) 123 - 136. DOI

2018

Granderson, Jessica, Guanjing Lin, Rupam Singla, Samuel Fernandes, and Samir Touzani."BuildingIQ Technology Field Validation." (2018). DOI
Granderson, Jessica, Guanjing Lin, Rupam Singla, Ebony Mayhorn, Paul Ehrlich, and Draguna Vrabie."Commercial Fault Detection and Diagnostics Tools: What They Offer, How They Differ, and What’s Still Needed."2018 ACEEE Summer Study on Energy Efficiency in Buildings (2018).
Granderson, Jessica, Guanjing Lin, Rupam Singla, Samuel Fernandes, and Samir Touzani."Field evaluation of performance of HVAC optimization system in commercial buildings."Energy and Buildings 173 (2018) 577 - 586. DOI
Blum, David H., Guanjing Lin, Michael Spears, Janie Page, and Jessica Granderson."When Data Analytics Meet Site Operation: Benefits and Challenges."2018 ACEEE Summer Study on Energy Efficiency in Buildings (2018).
Harris, Nora, Tripp Shealy, Hannah Kramer, Jessica Granderson, and Georg Reichard."A Framework for Monitoring-Based Commissioning: Identifying Variables That Act as Barriers and Enablers to the Process."Energy and Buildings 168 (2018) 331 - 346. DOI
Singh, Reshma, Paul A. Mathew, Jessica Granderson, Yash Shukla, Amiya Ranjan Behera, and Michael Pitt."Packaged Scalable Energy Information Systems for Hotels."Journal of Facilities Management 16.2 (2018) 119 - 141. DOI
Fernandes, Samuel, Jessica Granderson, Rupam Singla, and Samir Touzani."Corporate Delivery of a Global Smart Buildings Program."Energy Engineering (2018). DOI
Touzani, Samir, Jessica Granderson, and Samuel Fernandes."Gradient boosting machine for modeling the energy consumption of commercial buildings."Energy and Buildings (2018). DOI
Walker, Iain S., and Brennan Less."Rethinking Occupancy-Based Ventilation Controls."39th AIVC Conference (2018).

2017

Granderson, Jessica, Guanjing Lin, David H. Blum, Shankar Earni, Janie Page, and Mary Ann Piette."Optimizing Operational Efficiency: Integrating Energy Information Systems and Model-Based Diagnostics." (2017). DOI
Granderson, Jessica, Rupam Singla, Ebony Mayhorn, Paul Ehrlich, Draguna Vrabie, and Stephen Frank."Characterization and Survey of Automated Fault Detection and Diagnostics Tools." (2017).
Fernandes, Samuel, and Jessica Granderson."The State of Advanced Measurement and Verification Technology and Industry Application."The Electricity Journal 30.8 (2017) 8-16. DOI
Singla, Rupam, and Jessica Granderson."Using EMIS to Identify Top Opportunities for Commercial Building Efficiency." (2017).
Granderson, Jessica, Samir Touzani, Samuel Fernandes, and Cody Taylor."Application of Automated Measurement and Verification to Utility Energy Efficiency Program Data."Energy and Buildings (2017) 191-199. DOI

2016

Granderson, Jessica, Marco Bonvini, Mary Ann Piette, Janie Page, Guanjing Lin, and R. Lily Hu."Can We Practically Bring Physics-based Modeling Into Operational Analytics Tools?."Proceedings of the 2016 ACEEE Summer Study on Energy Efficiency in Buildings, Pacific Grove, CA, August 2016 (2016).
Granderson, Jessica, Samir Touzani, Cody Taylor, and Samuel Fernandes."Will the Measurement Robots Take Our Jobs? An Update on the State of Automated M&V for Energy Efficiency Programs."Proceedings of the 2016 ACEEE Summer Study on Energy Efficiency in Buildings, Pacific Grove, CA, August 2016." (2016).
Granderson, Jessica, Samir Touzani, Claudine Y. Custodio, Michael D. Sohn, David A. Jump, and Samuel Fernandes."Accuracy of Automated Measurement and Verification (M&V) Techniques for Energy Savings in Commercial Buildings."Applied Energy 173 (2016) 296-308. DOI
Granderson, Jessica, Erin L. Hult, Samuel Fernandes, Paul A. Mathew, and Robin Mitchell."Unlocking Energy Efficiency in Small Commercial Buildings through Mechanical Contractors."Journal of Architectural Engineering (2016).

2015

Price, Phillip N., Mary Ann Piette, Jessica Granderson, and John Elliott."Automated Measurement and Verification of Transactive Energy Systems, Load Shape Analysis, and Consumer Engagement."GridWise® Architecture Council Transactive Energy Conference (2015).
Price, Phillip N., Bruce Nordman, Mary Ann Piette, Richard E. Brown, Janie Page, Steven Lanzisera, and Jessica Granderson."Automated Measurement and Verification and Innovative Occupancy Detection Technologies." (2015).
Granderson, Jessica, Samir Touzani, Claudine Y. Custodio, Michael D. Sohn, Samuel Fernandes, and David A. Jump."Assessment of Automated Measurement and Verification (M&V) Methods." (2015).
Granderson, Jessica, Phillip N. Price, David A. Jump, Nathan J. Addy, and Michael D. Sohn."Automated Measurement and Verification: Performance of Public Domain Whole-Building Electric Baseline Models."Applied Energy 144 (2015) 106-113. DOI
Granderson, Jessica, Phillip N. Price, Stephen Czarnecki, Janie Page, Richard E. Brown, and Mary Ann Piette."Development of Diagnostic and M&V Agents, and Implementation in an Occupied Office Environment." (2015).

2014

Gao, Yafeng, Jiangmin Xu, Shichao Yang, Xiaomin Tang, Quan Zhou, Jing Ge, Tengfang T. Xu, and Ronnen M. Levinson."Cool Roofs in China: Policy Review, Building Simulations, and Proof-Of-Concept Experiments."Energy Policy 74 (2014) 190-214. DOI
Granderson, Jessica, David A. Jump, Phillip N. Price, and Michael D. Sohn."Performance Metrics and Objective Testing Methods for Energy Baseline Modeling Software." (2014).
Granderson, Jessica, and Phillip N. Price."Development and Application of a Statistical Methodology to Evaluate the Predictive Accuracy of Building Energy Baseline Models."Energy 66 (2014) 981-990. DOI

2013

Granderson, Jessica, Guanjing Lin, and Mary Ann Piette."Energy information systems (EIS): Technology costs, benefit, and best practice uses." (2013).
Price, Phillip N., Jessica Granderson, Michael D. Sohn, Nathan J. Addy, and David A. Jump."Commercial Building Energy Baseline Modeling Software: Performance Metrics and Method Testing with Open Source Models and Implications for Proprietary Software Testing." (2013).
Jump, David A., Phillip N. Price, Jessica Granderson, and Michael D. Sohn."Functional Testing Protocols for Commercial Building Efficiency Baseline Modeling Software." (2013).
Granderson, Jessica, and Phillip N. Price."Development and Application of a Statistical Methodology to Evaluate the Predictive Accuracy of Building Energy Baseline Models." (2013).
Maddalena, Randy L., Na Li, Alfred T. Hodgson, Francis J. Offermann, and Brett C. Singer."Maximizing Information from Residential Measurements of Volatile Organic Compounds."Healthy Buildings 2012 - 10th International Conference (2013).
Garcia, Guillermo, Raffaella Buonsanti, Anna Llordes, Evan L. Runnerstrom, Amy Bergerud, and Delia J. Milliron."Near-Infrared Spectrally Selective Plasmonic Electrochromic Thin Films."Advanced Optical Materials 1.3 (2013) 215 - 220. DOI

2012

Granderson, Jessica, and Phillip N. Price."Evaluation of the Predictive Accuracy of Five Whole-Building Baseline Models." (2012).
Piette, Mary Ann, Jessica Granderson, Michael Wetter, and Sila Kiliccote."Responsive and Intelligent Building Information and Control for Low-Energy and Optimized Grid Integration."ACEEE 2012 Summer Study on Energy Efficiency in Buildings, August 12-17, 2012 (2012).
Offermann, Francis J., Randy L. Maddalena, Francis J. Offermann, Brett C. Singer, and Henry Willem."The impact of ventilation rate on the emission rates of volatile organic compounds in residences."Healthy Buildings 2012 - 10th International Conference (2012).
Piette, Mary Ann, Jessica Granderson, Michael Wetter, and Sila Kiliccote."Intelligent Building Energy Information and Control Systems for Low-Energy Operations and Optimal Demand Response."IEEE Design and Test of Computers 29.4 (2012) 8-16. DOI
Mills, Evan, and Paul A. Mathew."Monitoring-Based Commissioning: Benchmarking Analysis of 24 University Buildings in California."Energy Engineering (2012).

2011

Granderson, Jessica, Mary Ann Piette, Ben Rosenblum, R. Lily Hu, Daniel Harris, Paul A. Mathew, Phillip N. Price, Geoffrey C. Bell, Srinivas Katipamula, and Michael Brambley."Energy Information Handbook: Applications for Energy-Efficient Building Operations." (2011).
Levinson, Ronnen M., Heng Pan, George A. Ban-Weiss, Pablo J. Rosado, Riccardo Paolini, and Hashem Akbari."Potential benefits of solar reflective car shells: Cooler cabins, fuel savings and emission reductions."Applied Energy 88.12 (2011) 4343-4357. DOI
Garcia, Guillermo, Raffaella Buonsanti, Evan L. Runnerstrom, Rueben J. Mendelsberg, Anna Llordes, André Anders, Thomas J. Richardson, and Delia J. Milliron."Dynamically Modulating the Surface Plasmon Resonance of Doped Semiconductor Nanocrystals."Nano Letters 11.10 (2011) 4415 - 4420. DOI
Mills, Evan."Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse Gas Emissions in the United States.."Energy Efficiency (2011). DOI
Granderson, Jessica, Mary Ann Piette, and Girish Ghatikar."Building Energy Information Systems: User Case Studies."Energy Efficiency 4.1 (2011) 17-30. DOI
Marini, Kyle, Girish Ghatikar, and Richard C. Diamond."Using Dashboards to Improve Energy and Comfort in Federal Buildings." (2011).
Mills, Evan, and Arne Jacobson."From Carbon to Light: A New Framework for Estimating Greenhouse Gas Emissions Reducitons from Replacing Fuel-Based Lighting with LED Systems.."Energy Efficiency (2011). DOI

2010

Kircher, Kevin, Girish Ghatikar, Steve E. Greenberg, David S. Watson, Richard C. Diamond, Dale A. Sartor, Clifford C. Federspiel, Alex McEachern, and Tom Owen."Toward the Holy Grail of Perfect Information: Lessons Learned Implementing an Energy Information System in a Commercial Building."2010 ACEEE Summer Study on Energy Efficiency in Buildings (2010).
Ni, Pavel A., and André Anders."Supersonic metal plasma impact on a surface: an optical investigation of the pre-surface region."Journal of Physics D: Applied Physics 43.13 (2010). DOI

2009

Coffey, Brian E., Sam Borgeson, Stephen E. Selkowitz, Joshua S. Apte, Paul A. Mathew, and Philip Haves."Towards a Very Low Energy Building Stock: Modeling the U.S. Commercial Building Sector to Support Policy and Innovation Planning."Building Research & Information (2009).

2008

Price, Lynn K., Christina Galitsky, Klaas Jan Kramer, and Aimee T. McKane."International Experience with Key Program Elements of Industrial Energy Efficiency or Greenhouse Gas Emissions Reduction Target-Setting Programs." (2008).

2004

Nazaroff, William W., and Brett C. Singer."Inhalation of Hazardous Air Pollutants from Environmental Tobacco Smoke in US Residences."Journal of Exposure Analysis and Environmental Epidemiology 14 (2004) S71-77.

2003

Wenzel, Thomas P.."Use of remote sensing measurements to evaluate vehicle emission monitoring programs: results from Phoenix, Arizona."Transportation Research Part D 6.2 (2003). DOI

2001

Wenzel, Thomas P.."Evaluating the long-term effectiveness of the Phoenix IM240 program."Environmental Science & Policy 4.6 (2001). DOI
Wenzel, Thomas P.."Reducing emissions from in-use vehicles: an evaluation of the Phoenix inspection and maintenance program using test results and independent emissions measurements."Environmental Science & Policy 4.6 (2001) 359-376. DOI
Piette, Mary Ann, Satkartar T. Khalsa, and Philip Haves."Analysis of an Information Monitoring and Diagnostic System to Improve Building Operations."Energy and Buildings 33.8 (2001) 783-792. DOI

2000

Johnson, Francis X, and Jeffrey P. Harris."Estimated Savings from Energy- Efficient Federal Purchasing." (2000).

1998

McPherson, E. Gregory, Klaus I. Scott, and James R. Simpson."Estimating cost effectiveness of residential yard trees for improving air quality in Sacramento, California, using existing models."Atmospheric Environment 32.1 (1998) 75-84. DOI

1997

Taha, Haider, Sharon Douglas, and Jay Haney."Mesoscale meteorological and air quality impacts of increased urban albedo and vegetation."Energy and Buildings 25.2 (1997) 169-177. DOI

1996

Taha, Haider."Modeling impacts of increased urban vegetation on ozone air quality in the South Coast Air Basin."Atmospheric Environment 30 (1996) 3423-3430. DOI

1995

Özer, Nilgün, Din-Guo Chen, and Carl M Lampert."Preparation and Properties of Spin-Coated Nb2O5 Films by the Sol-Gel Process for Electrochemical Applications."Thin Solid Films 277.1-2 (1995) 162-168.

1976

Bentley, Michael, Philip Haves, Ralph E. Spencer, and David Stannard."The Radio Structure of a Sample of 101 Quasars from the Parkes ±4º Survey."Monthly Notices of the Royal Astronomical Society 176 (1976) 275-306.

1974

Haves, Philip, Robin G. Conway, and David Stannard."The Polarization of Radio Sources at 31 CM."Monthly Notices of the Royal Astronomical Society 169 (1974) 117-131.