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  1. Free, publicly-accessible full text available June 8, 2023
  2. Finkbeiner, B. ; Wies, T. (Ed.)
    Stochastic model checking (SMC) is a formal verification technique for the analysis of systems with probabilistic behavior. Scalability has been a major limiting factor for SMC tools to analyze real-world systems with large or infinite state spaces. The infinite-state Continuous-time Markov Chain (CTMC) model checker, STAMINA, tackles this problem by selectively exploring only a portion of a model’s state space, where a majority of the probability mass resides, to efficiently give an accurate probability bound to properties under verification. In this paper, we present two major improvements to STAMINA, namely, a method of calculating and distributing estimated state reachability probabilitiesmore »that improves state space truncation efficiency and combination of the previous two CTMC analyses into one for generating the probability bound. Demonstration of the improvements on several benchmark examples, including hazard analysis of infinite-state combinational genetic circuits, yield significant savings in both run-time and state space size (and hence memory), compared to both the previous version of STAMINA and the infinite-state CTMC model checker INFAMY. The improved STAMINA demonstrates significant scalability to allow for the verification of complex real-world infinite-state systems.« less
    Free, publicly-accessible full text available June 14, 2023
  3. The purpose of this study was to develop a replicable methodology for testing the capabilities and characteristics of a wind turbine blade in a structural re-use application with the specific goal of creating and demonstrating an efficient and commercially viable wind blade pedestrian bridge design. Wind energy experienced a dramatic increase in popularity following the turn of the century and it is now a common source of renewable energy around the world. However, while wind turbines are able to produce clean energy while in service, turbine blades are designed for a fatigue life of only about 20 years. With themore »difficulty and costs associated with recycling the composite material blades used on the turbines, wind power companies choose to dispose of decommissioned blades in landfills instead. The Re-Wind BladeBridge project aims to promote a more sustainable life cycle for wind power by demonstrating that decommissioned wind turbine blades have the capability to be repurposed as structural elements in bridges. This paper presents an analysis and characterization of a LM 13.4 wind blade from a Nordex N29 turbine, along with a design for a pedestrian bridge using two LM 13.4 wind blades to create a 5-meter span bridge. Software developed by the Re-Wind team called “BladeMachine” was used to generate the engineering properties of the blade at multiple sections along the blade length. Resin burnout tests and mechanical testing in tension and compression were performed to determine the material and mechanical properties of the composite materials in the blade. Additionally, a four-point edgewise bending test was performed on a 4-meter section of the wind blade to evaluate its load carrying behavior. The results of these tests revealed that the LM 13.4 blades are suitable to be re-utilized as girders for a short-span pedestrian bridge. An overview of the design of the BladeBridge currently under construction in County Cork, Ireland is presented, including details on the architectural and structural design processes.« less
    Free, publicly-accessible full text available July 6, 2023
  4. Free, publicly-accessible full text available February 1, 2023
  5. Semiconductors with O(meV) band gaps have been shown to be promising targets to search for sub-MeV mass dark matter (DM). In this paper we focus on a class of materials where such narrow band gaps arise naturally as a consequence of spin-orbit coupling (SOC). Specifically, we are interested in computing DM-electron scattering and absorption rates in these materials using state- of-the-art density functional theory (DFT) techniques. To do this, we extend the DM interaction rate calculation to include SOC effects which necessitates a generalization to spin-dependent wave functions. We apply our new formalism to calculate limits for several DM benchmarkmore »models using an example ZrTe5 target and show that the inclusion of SOC can substantially alter projected constraints.« less
    Free, publicly-accessible full text available February 1, 2023
  6. Free, publicly-accessible full text available January 1, 2023
  7. Free, publicly-accessible full text available November 3, 2022
  8. Free, publicly-accessible full text available October 31, 2022
  9. Musier-Forsyth, Karin (Ed.)
    RNA-binding proteins play crucial roles in various cellular functions, and contain abundant disordered protein regions. The disordered regions in RNA-binding proteins are rich in repetitive sequences, such as poly-K/R, poly-N/Q, poly-A, and poly-G residues. Our bioinformatic analysis identified a largely neglected repetitive sequence family we define as electronegative clusters (ENCs) that contain acidic residues and/or phosphorylation sites. The abundance and length of ENCs exceed other known repetitive sequences. Despite their abundance, the functions of ENCs in RNA-binding proteins are still elusive. To investigate the impacts of ENCs on protein stability, RNA-binding affinity, and specificity, we selected one RNA-binding protein, themore »ribosomal biogenesis factor 15 (Nop15) as a model. We found that the Nop15 ENC increases protein stability and inhibits nonspecific RNA binding, but minimally interferes with specific RNA binding. To investigate the effect of ENCs on sequence specificity of RNA binding, we grafted an ENC to another RNA-binding protein, Ser/Arg-rich splicing factor 3 (SRSF3). Using RNA Bind-n-Seq, we found that the engineered ENC inhibits disparate RNA motifs differently, instead of weakening all RNA motifs to the same extent. The motif site directly involved in electrostatic interaction is more susceptible to the ENC inhibition. These results suggest that one of functions of ENCs is to regulate RNA binding via electrostatic interaction. This is consistent with our finding that ENCs are also overrepresented in DNA-binding proteins, while underrepresented in halophiles, in which nonspecific nucleic acid binding is inhibited by high concentrations of salts.« less
    Free, publicly-accessible full text available July 9, 2022