A TYPE ANALYSIS OF REWRITE STRATEGIES

Rewrite strategies provide an algorithmic rewriting of terms using strategic compositions of rewrite rules. Due to the programmability of rewrites, errors are often made due to incorrect compositions of rewrites or incorrect application of rewrites to a term within a strategic rewriting program. In practical applications of strategic rewriting, testing and debugging becomes substantially time-intensive for large programs applied to large inputs derived from large term grammars. In essence, determining which rewrite in what position in a term did or did not re comes down to logging, tracing and/or di -like comparison of inputs to outputs. In this thesis, we explore type-enabled analysis of strategic rewriting programs to detect errors statically. In particular, we introduce high-precision types to closely approximate the dynamic behavior of rewriting. We also use union types to track sets of types due to presence of strategic compositions. In this framework of high-precision strategic typing, we develop and implement an expressive type system for a representative strategic rewriting language TL. The results of this research are sufficiently broad to be adapted to other strategic rewriting languages. In particular, the type-inferencing algorithm does not require explicit type annotations for minimal impact on an existing language. Based on our experience with the implementation, the type system significantly reduces the time and effort to program correct rewrite strategies while performing the analysis on the order of thousands of source lines of code per second

The DOE E3SM Coupled Model Version 1: Overview and Evaluation at Standard Resolution

This work documents the first version of the U.S. Department of Energy (DOE) new Energy Exascale Earth System Model (E3SMv1). We focus on the standard resolution of the fully coupled physical model designed to address DOE mission-relevant water cycle questions. Its components include atmosphere and land (110-km grid spacing), ocean and sea ice (60 km in the midlatitudes and 30 km at the equator and poles), and river transport (55 km) models. This base configuration will also serve as a foundation for additional configurations exploring higher horizontal resolution as well as augmented capabilities in the form of biogeochemistry and cryosphere configurations. The performance of E3SMv1 is evaluated by means of a standard set of Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima simulations consisting of a long preindustrial control, historical simulations (ensembles of fully coupled and prescribed SSTs) as well as idealized CO2 forcing simulations. The model performs well overall with biases typical of other CMIP-class models, although the simulated Atlantic Meridional Overturning Circulation is weaker than many CMIP-class models. While the E3SMv1 historical ensemble captures the bulk of the observed warming between preindustrial (1850) and present day, the trajectory of the warming diverges from observations in the second half of the twentieth century with a period of delayed warming followed by an excessive warming trend. Using a two-layer energy balance model, we attribute this divergence to the model’s strong aerosol-related effective radiative forcing (ERFari+aci = -1.65 W/m2) and high equilibrium climate sensitivity (ECS = 5.3 K).Plain Language SummaryThe U.S. Department of Energy funded the development of a new state-of-the-art Earth system model for research and applications relevant to its mission. The Energy Exascale Earth System Model version 1 (E3SMv1) consists of five interacting components for the global atmosphere, land surface, ocean, sea ice, and rivers. Three of these components (ocean, sea ice, and river) are new and have not been coupled into an Earth system model previously. The atmosphere and land surface components were created by extending existing components part of the Community Earth System Model, Version 1. E3SMv1’s capabilities are demonstrated by performing a set of standardized simulation experiments described by the Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima protocol at standard horizontal spatial resolution of approximately 1° latitude and longitude. The model reproduces global and regional climate features well compared to observations. Simulated warming between 1850 and 2015 matches observations, but the model is too cold by about 0.5 °C between 1960 and 1990 and later warms at a rate greater than observed. A thermodynamic analysis of the model’s response to greenhouse gas and aerosol radiative affects may explain the reasons for the discrepancy.Key PointsThis work documents E3SMv1, the first version of the U.S. DOE Energy Exascale Earth System ModelThe performance of E3SMv1 is documented with a set of standard CMIP6 DECK and historical simulations comprising nearly 3,000 yearsE3SMv1 has a high equilibrium climate sensitivity (5.3 K) and strong aerosol-related effective radiative forcing (-1.65 W/m2)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151288/1/jame20860_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151288/2/jame20860.pd

\u3ci\u3eEncyclopedia of E-Collaboration\u3c/i\u3e

Editor: Ned Knock Chapter 73, The Practice and Promise of Virtual Project Management, co-authored by Ilze Zigurs, Deepak Khazanchi and Azamat Mametjanov,UNO faculty members. E-collaboration, while having its roots in electronic technology such as telephones and other rudimentary electronic devices, has expanded dramatically with today\u27s plethora of computer-supported cooperation and computer-mediated communication. The Encyclopedia of E-Collaboration includes 109 authoritative contributions on information on the design and implementation of e-collaboration technologies, the behavioral impacts of e-collaboration technologies on individuals and groups, and theoretical considerations on links between the use of e-collaboration technology and behavioral patterns.With more than 2,600 references to existing literature and over 850 key terms this cutting-edge encyclopedia delivers indispensable content to libraries and researchers looking to develop programs of investigation into the use of electronic collaboration.https://digitalcommons.unomaha.edu/facultybooks/1266/thumbnail.jp

\u3ci\u3eVirtual Technologies: Concepts, Methodologies, Tools, and Applications\u3c/i\u3e

Editor: Jerzy Kisielnicki Chapter 13, The Practice and Promise of Virtual Project Management, co-authored by Ilze Zigurs, Deepak Khazanchi and Azamat Mametjanov, UNO faculty members. Chapter 85, Patterns for Effective Management of Virtual Projects: Theory and Evidence, co-authored by Deepak Khazanchi and Ilze Zigurs, UNO faculty members. Virtual Technologies: Concepts, Methodologies, Tools and Applications includes the most encompassing research of the concepts and realities involved in the field of virtual communities and technologies. This ground breaking, multi-volume compendium of over 300 chapters from a global pool of more than 225 experts presents an in-depth analysis of the social and economic impacts of virtual environments. Comprised of such topics as collaborative technologies, resource-based view strategy, structuration theory, synchronous and asynchronous environments, and videoconferencing life-cycle, this Premier Reference source is the defining core of research for the field of virtual technologies. This 3-volume compendium enlivens the coverage within the field of virtual technologies while providing the fundamental research base necessary for any library.https://digitalcommons.unomaha.edu/facultybooks/1267/thumbnail.jp

Characterizing Tropical Cyclones in the Energy Exascale Earth System Model Version 1

Abstract In this study, we analyze the realism with which tropical cyclones (TCs) are simulated in the fully coupled low‐ and high‐resolution Energy Exascale Earth System Model (E3SM) version 1, with a focus on the latter. Compared to the low‐resolution (grid spacing of ∼1°), the representation of TCs improves considerably in the high‐resolution configuration (grid spacing of ∼0.25°). Significant improvements are found in the global TC frequency, TC lifetime maximum intensities, and the relative distribution of TCs among the different basins. However, at both resolutions, spurious TC activity is found in some basins, notably in the subtropical regions. Contrasting the simulated large‐scale TC environment with observations reveals that the model environment is unrealistically conducive for TC development in those regions. Further analysis indicates that these biases are likely related to those in thermodynamic potential intensity, caused by systematic SST biases, and vertical wind shear in the coupled model. TC‐ocean interaction is also examined in the high‐resolution configuration of the model. The salient features of the ocean's response to TC‐induced mixing and the ocean's impact on TC intensification are well‐reproduced. Finally, an evaluation of the influence of El Niño Southern Oscillation (ENSO) on TCs in the high‐resolution configuration of the model reveals that the ENSO‐TC relationship in the model has the right sign and is significant for the North Atlantic and Northwest Pacific, albeit weaker than in observations. In summary, the high‐resolution configuration of the E3SM model simulates TC activity reasonably and hence could be a useful tool for TC‐related research