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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Article
Research Reports (2001)

Intelligent "driver assistance" systems which utilize in-vehicle forward-looking sensors can be supplemented by vehicle-vehicle and vehicle-highway cooperative elements to comprise a "sensor-friendly" highway environment that would enhance the operational efficiency, and ultimately, the safety benefits of these systems. In our research, we have identified the current limitations of autonomous sensing systems in target/background discrimination with cluttered highways. Based upon this, and by limiting ourselves to "sensed" (and not wireless) systems, we have conceived relatively inexpensive vehicle-highway cooperative systems to allow those limitations to be mitigated. Emphasis has been placed on 77 GHz (millimeter wave) automotive radar sensors - a sensor type which is in current use and when improved, will result in improved longitudinal safety products in the near-to-mid term, up through the longer term vision of full vehicle-highway automation. In the work reported here, we introduce the concept of sensor-friendly high systems, describe roadside signatures, and using these as bases, discuss our concepting and experiments several cooperative vehicle-highway concepts. We describe experiments and results from prototypes of three of the potentially nearest term means to realize a cooperative collision avoidance systems, which we regard as the first step toward sensor-friendly highways 1 . We describe three potential systems: Light Emitting Diode Brake Light Messaging, Roadside-Mounted Corner Cubes, and Passive License Plates. We believe that while experimental results point toward the need for further proof-of-concept refinements, these systems potentially represent technologically sound cooperative vehicle-roadway components, and that indeed, "sensor friendly" systems, when put to the test, can eventually translate into significant benefit in terms of lives saved.

    Cover page: Sensor-Friendly Freeways: Investigation of Progressive Roadway Changes to Facilitate Deployment of AHS
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2021)
    Ascorbic acid is among the most abundant antioxidants in the lung, where it likely plays a key role in the mechanism by which particulate air pollution initiates a biological response. Because ascorbic acid is a highly redox active species, it engages in a far more complex web of reactions than a typical organic molecule, reacting with oxidants such as the hydroxyl radical as well as redox-active transition metals such as iron and copper. The literature provides a solid outline for this chemistry, but there are large disagreements about mechanisms, stoichiometries and reaction rates, particularly for the transition metal reactions. Here we synthesize the literature, develop a chemical kinetics model, and use seven sets of laboratory measurements to constrain mechanisms for the iron and copper reactions and derive key rate constants. We find that micromolar concentrations of iron(III) and copper(II) are more important sinks for ascorbic acid (both AH2 and AH-) than reactive oxygen species. The iron and copper reactions are catalytic rather than redox reactions, and have unit stoichiometries: Fe(III)/Cu(II) + AH2/AH-  + O2 → Fe(III)/Cu(II) + H2O2 + products. Rate constants are 5.7 × 104 and 4.7 × 104 M-2 s-1 for Fe(III) + AH2/AH- and 7.7 × 104 and 2.8 × 106 M-2 s-1 for Cu(II) + AH2/AH-, respectively.
      Cover page: Ascorbate oxidation by iron, copper and reactive oxygen species: review, model development, and derivation of key rate constantsCreative Commons 'BY' version 4.0 license
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