skip to main content
Explore Scholarly Publications and Datasets in the NSF-PAR

  • Home
  • Search Results
  • Page 1 of 13

Search for: All records

Creators/Authors contains: "Porter, J."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. ; ; ; ( , Mechanical systems and signal processing)
    Hysteretic models are widely used to model frictional interactions in joints to recreate experimental behavior. However, it is unclear which models are best suited for fitting or predicting the responses of structures. The present study evaluates 26 friction model/interface representation combinations to quantify the model form error. A Quasi-Static Modal Analysis approach (termed Rayleigh Quotient Nonlinear Modal Analysis) is adopted to calculate the nonlinear system response, and a Multi-Objective Optimization is solved to fit experimental data of the first mode of the Brake-Reuß Beam. Optimized parameters from the first mode are applied to the second and third bending modes tomore »quantify the predictive ability of the models. Formulations for both tracing full hysteresis loops and recreating hysteresis loops from a single loading curve (Masing assumptions) are considered. Smoothly varying models applied to a five patch representation showed the highest flexibility (for fitting mode 1) and good predictive potential (for modes 2 and 3). For a second formulation, which uses 152 frictional elements to represent the interface, the physically motivated spring in series with a Coulomb slip model (elastic dry friction) has high error for fitting mode 1 and performs near the middle for predicting higher modes. For both interface representation, the best fit models are not the most physical, but rather the ones with the most parameters (as expected); however, the more physical models perform somewhat better for predicting the higher modes.« less
    Free, publicly-accessible full text available January 1, 2023
  2. ; ; ; ( , RSC Advances)
    In this work, a proteolytic digest of cytochrome c (microperoxidase 11, MP-11) was used as a model to study the structural aspects of heme protein interactions and porphyrin networks. The MP-11 structural heterogeneity was studied as a function of the starting pH ( e.g. , pH 3.1–6.1) and concentration ( e.g. , 1–50 μM) conditions and adduct coordination. Trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) showed the MP-11 structural dependence of the charge state distribution and molecular ion forms with the starting pH conditions. The singly charged ( e.g. , [M] + , [M − 2H + NHmore »4 ] + , [M − H + Na] + and [M − H + K] + ) and doubly charged ( e.g. , [M + H] 2+ , [M − H + NH 4 ] 2+ , [M + Na] 2+ and [M + K] 2+ ) molecular ion forms were observed for all solvent conditions, although the structural heterogeneity ( e.g. , number of mobility bands) significantly varied with the pH value and ion form. The MP-11 dimer formation as a model for heme-protein protein interactions showed that dimer formation is favored toward more neutral pH and favored when assisted by salt bridges ( e.g. , NH 4 + , Na + and K + vs. H + ). Inspection of the dimer mobility profiles (2+ and 3+ charge states) showed a high degree of structural heterogeneity as a function of the solution pH and ion form; the observation of common mobility bands suggest that the different salt bridges can stabilize similar structural motifs. In addition, the salt bridge influence on the MP-11 dimer formations was measured using collision induced dissociation and showed a strong dependence with the type of salt bridge ( i.e. , a CE 50 of 10.0, 11.5, 11.8 and 13.0 eV was observed for [2M + H] 3+ , [2M − H + NH 4 ] 3+ , [2M + Na] 3+ and [2M + K] 3+ , respectively). Measurements of the dimer equilibrium constant showed that the salt bridge interactions increase the binding strength of the dimeric species.« less
    Full Text Available 
  3. ; ( , Journal of Vibration and Acoustics)
    Full Text Available 
  4. ; ( , CHI Play)
    Since the release of the Oculus Rift CV1 in 2016, millionsof VR headsets have found their way into consumer homes.In this paper, we sought to understand what shifts have takenplace within the two years since consumer VR became avail-able. In this paper, we consider what can be learned aboutlong-term use of consumer VR through an analysis of dis-cussions in online forums devoted to VR. We gathered postsmade on the /r/Vive subreddit from the first two years after theHTC Vive’s release. We present the results from an in-depthqualitative analysis concerning immersion, presence, and sim-ulator sickness. Over time, as users moved frommore »passive toactive, their attitudes and expectations towards immersion andsimulator sickness matured. Major trends of interest foundwere game design implementation and locomotion techniques.« less
    Accepted Manuscript Full Text Available
  5. ; ; ; ( , Virtual and Physical Prototyping)
    Full Text Available 
  6. ; ; ; ; ; ; ; ; ; ; et al ( , Physical Review Letters)
    Free, publicly-accessible full text available November 1, 2022
  7. ; ; ; ; ; ; ; ; ; ; et al ( , Physical Review Letters)
    Free, publicly-accessible full text available March 1, 2023
  8. ; ; ; ; ; ; ; ; ; ; et al ( , Physical Review D)
    Free, publicly-accessible full text available September 1, 2022
  9. ; ; ( , The Journal of Chemical Physics)
    Full Text Available 
  10. ; ; ; ; ; ; ; ; ; ; et al ( , Physical Review D)
    null (Ed.)
    Free, publicly-accessible full text available July 1, 2022