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2,034 results on '"Keller, Robert"'

2. Pure-Water-Fed Forward-Bias Bipolar Membrane CO2 Electrolyzer

Author

Heßelmann, Matthias, Lee, Jason Keonhag, Chae, Sudong, Tricker, Andrew, Keller, Robert Gregor, Wessling, Matthias, Su, Ji, Kushner, Douglas, Weber, Adam Z, and Peng, Xiong

Subjects
Macromolecular and Materials Chemistry, Engineering, Chemical Sciences, Climate Action, Affordable and Clean Energy, asymmetric, bipolar membrane, cell design, electrochemical CO2 reduction, forward-bias, water-fed, Nanoscience & Nanotechnology, Chemical sciences, Physical sciences
Abstract

Coupling renewable electricity to reduce carbon dioxide (CO2) electrochemically into carbon feedstocks offers a promising pathway to produce chemical fuels sustainably. While there has been success in developing materials and theory for CO2 reduction, the widespread deployment of CO2 electrolyzers has been hindered by challenges in the reactor design and operational stability due to CO2 crossover and (bi)carbonate salt precipitation. Herein, we design asymmetrical bipolar membranes assembled into a zero-gap CO2 electrolyzer fed with pure water, solving both challenges. By investigating and optimizing the anion-exchange-layer thickness, cathode differential pressure, and cell temperature, the forward-bias bipolar membrane CO2 electrolyzer achieves a CO faradic efficiency over 80% with a partial current density over 200 mA cm-2 at less than 3.0 V with negligible CO2 crossover. In addition, this electrolyzer achieves 0.61 and 2.1 mV h-1 decay rates at 150 and 300 mA cm-2 for 200 and 100 h, respectively. Postmortem analysis indicates that the deterioration of catalyst/polymer-electrolyte interfaces resulted from catalyst structural change, and ionomer degradation at reductive potential shows the decay mechanism. All these results point to the future research direction and show a promising pathway to deploy CO2 electrolyzers at scale for industrial applications.

Published
2024

19. Current developments in S corporations

Author

Brajcich, Andrew M., Hill, Kristin, Jamison, Robert W., Jr., Keller, Robert S., Mitchell, Kirk T., Orbach, Kenneth N., Nitti, Tony, Walsh, Kevin J., and Williamson, Jonathan

Subjects
United States. Internal Revenue Service -- Aims and objectives -- Powers and duties, Tax planning -- Laws, regulations and rules -- Methods, Tax consultants -- Laws, regulations and rules -- Management, S corporations -- Laws, regulations and rules -- Taxation, Taxpayer compliance -- Laws, regulations and rules -- Management, Stockholders -- Laws, regulations and rules -- Taxation, Government regulation, Company business management, Banking, finance and accounting industries, Business, American Institute of Certified Public Accountants -- Powers and duties -- Management
Abstract

Fourteen sections of the Internal Revenue Code are central to the taxation of Subchapter S corporations and their shareholders. (1) Over the 12-month period ending March 2023 covered by this [...]

Published
2023

22. Recent Developments in Blockchain Technology and their Impact on Energy Consumption

Author

Sedlmeir, Johannes, Buhl, Hans Ulrich, Fridgen, Gilbert, and Keller, Robert

Subjects
Computer Science - Cryptography and Security, Computer Science - Distributed, Parallel, and Cluster Computing
Abstract

The enormous power consumption of Bitcoin has led to undifferentiated discussions in science and practice about the sustainability of blockchain and distributed ledger technology in general. However, blockchain technology is far from homogeneous - not only with regard to its applications, which now go far beyond cryptocurrencies and have reached businesses and the public sector, but also with regard to its technical characteristics and, in particular, its power consumption. This paper summarizes the status quo of the power consumption of various implementations of blockchain technology, with special emphasis on the recent 'Bitcoin Halving' and so-called 'zk-rollups'. We argue that although Bitcoin and other proof-of-work blockchains do indeed consume a lot of power, alternative blockchain solutions with significantly lower power consumption are already available today, and new promising concepts are being tested that could further reduce in particular the power consumption of large blockchain networks in the near future. From this we conclude that although the criticism of Bitcoin's power consumption is legitimate, it should not be used to derive an energy problem of blockchain technology in general. In many cases in which processes can be digitised or improved with the help of more energy-efficient blockchain variants, one can even expect net energy savings., Comment: This is a translated version of a German article published in Informatik Spektrum

Published
2021
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27. Korea--3 August 1950--the Corps goes to war

Author

Keller, Robert P., LtGen, Ret

Subjects
MARINE CORPS AVIATION - History, KOREAN WAR, 1950-1953 - Aerial Operations, American, CLOSE AIR SUPPORT - History
Abstract

illus

Published
2004

34. Program Language Translation Using a Grammar-Driven Tree-to-Tree Model

Author

Drissi, Mehdi, Watkins, Olivia, Khant, Aditya, Ojha, Vivaswat, Sandoval, Pedro, Segev, Rakia, Weiner, Eric, and Keller, Robert

Subjects
Computer Science - Machine Learning, Computer Science - Programming Languages, Statistics - Machine Learning
Abstract

The task of translating between programming languages differs from the challenge of translating natural languages in that programming languages are designed with a far more rigid set of structural and grammatical rules. Previous work has used a tree-to-tree encoder/decoder model to take advantage of the inherent tree structure of programs during translation. Neural decoders, however, by default do not exploit known grammar rules of the target language. In this paper, we describe a tree decoder that leverages knowledge of a language's grammar rules to exclusively generate syntactically correct programs. We find that this grammar-based tree-to-tree model outperforms the state of the art tree-to-tree model in translating between two programming languages on a previously used synthetic task., Comment: Accepted at the ICML workshop Neural Abstract Machines & Program Induction v2. 4 pages excluding acknowledgements/references (6 pages total)

Published
2018

36. Current developments in S corporations

Author

Brajcich, Andrew M., Hill, Kristin, Jamison, Robert W., Keller, Robert S., Mitchell, Kirk T., Orbach, Kenneth N., Scott, Alexander, and Walsh, Kevin J.

Subjects
S corporations -- Laws, regulations and rules -- Taxation, Corporate income taxes -- Laws, regulations and rules -- Research, Government regulation, Banking, finance and accounting industries, Business
Abstract

Fourteen sections of the Internal Revenue Code are central to the taxation of Subchapter S corporations and their shareholders. Over the 12-month period ending February 2022, some of these sections [...]

Published
2022

43. Dynamics of the Boundary Layer in Pulsed CO2 Electrolysis.

Author

Heßelmann, Matthias, Felder, Daniel, Plischka, Wenzel, Nabi, Sajad, Linkhorst, John, Wessling, Matthias, and Keller, Robert

Subjects
ELECTRIC double layer, ELECTROLYTIC reduction, BOUNDARY layer (Aerodynamics), RENEWABLE natural resources, ELECTROLYSIS
Abstract

Electrochemical reduction of CO2 poses a vast potential to contribute to a defossilized industry. Despite tremendous developments within the field, mass transport limitations, carbonate salt formation, and electrode degradation mechanisms still hamper the process performance. One promising approach to tweak CO2 electrolysis beyond today's limitations is pulsed electrolysis with potential cycling between an operating and a regeneration mode. Here, we rigorously model the boundary layer at a silver electrode in pulsed operation to get profound insights into the dynamic reorganization of the electrode microenvironment. In our simulation, pulsed electrolysis leads to a significant improvement of up to six times higher CO current density and 20 times higher cathodic energy efficiency when pulsing between −1.85 and −1.05 V vs SHE compared to constant potential operation. We found that elevated reactant availability in pulsed electrolysis originates from alternating replenishment of CO2 by diffusion and not from pH‐induced carbonate and bicarbonate conversion. Moreover, pulsed electrolysis substantially promotes carbonate removal from the electrode by up to 83 % compared to constant potential operation, thus reducing the risk of salt formation. Therefore, this model lays the groundwork for an accurate simulation of the dynamic boundary layer modulation, which can provide insights into manifold electrochemical conversions. [ABSTRACT FROM AUTHOR]

Published
2024
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44. Removal of Emerging Contaminants from Water Using Novel Electroconductive Membranes in a Hybrid Membrane Distillation and Electro-Fenton Process

Author

Omi, Farah Rahman, primary, Rastgar, Masoud, additional, Mohseni, Mojtaba, additional, Singh, Upasana, additional, Dilokekunakul, Waralee, additional, Keller, Robert, additional, Wishart, David A., additional, Wessling, Matthias, additional, Vecitis, Chad Davis, additional, and Sadrzadeh, Mohtada, additional

Published
2024
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