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  1. The five interglacials before the Mid-Brunhes Event (MBE) [c.430 thousand years (ka) ago] are generally considered to be globally cooler than those post-MBE. Inhomogeneities exist regionally, however, which suggest that the Arctic was warmer than present during Marine Isotope Stage (MIS) 15a. Using the first speleothem record for the High Arctic, we investigate the climatic response of northeast Greenland between c.588 and c.549 ka ago. Our results indicate an enhanced warmth of at least +3.5°C relative to the present, leading to permafrost thaw and increased precipitation. We find that δ 18 O of precipitation was at least 3‰ higher thanmore »today and recognize two local cooling events (c.571 and c.594 ka ago) thought to be caused by freshwater forcing. Our results are important for improving understanding of the regional climatic response leading up to the MBE and specifically provide insights into the climatic response of a warmer Arctic.« less
  2. This proceeding was published in a special issue of J. Laser Appl. as: H. Cheng, C. Xia, S. M. Kuebler, P. Golvari, M. Sun, M. Zhang, X. Yu*. "Generation of Bessel-beam arrays for parallel fabrication in two-photon polymerization." J. Laser Appl. 2021, 33, 012040-1 - 012040-6; https://doi.org/10.2351/7.0000313.
  3. Abstract The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hardmore »scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.« less
    Free, publicly-accessible full text available December 1, 2023
  4. This paper describes a method of teaching image processing in a computer science (CS) course in which students obtain and analyze polar data through a computational guided inquiry (CGI) module. In CGI, the instructor guides the students in the process of learning, through the use of a computational tool: for this course, a Jupyter Notebook is used, consisting of alternating text and blocks of Python code that the students can modify as needed and execute. The students obtain images of polar ice and use them to learn about image processing while increasing their climate literacy. Students demonstrated learning of coursemore »disciplinary objectives through assessments built into the CGI module. Pre- and post-module surveys indicate increases in student self-reporting of comfort with Python and exposure to polar data. Over half of students indicated increased interest in learning more about polar research, and students overall rated the CGI modules positively. Improvements in climate literacy were tested through asking students to ask a question about a visual representation of polar data; results of this assessment were inconclusive. Future work will focus on strengthening the connection between goals, activities, and assessment, in order to better understand whether the goal of improved climate literacy was achieved.« less