working paper
The 1990 amendments to the Clean Air Act mandated that local governments that violate federal ozone (urban smog) standards abide by a dizzying array of regulations, many of the most controversial of which–centralized state inspection and maintenance programs, carpooling requirements, zero- emission vehicle sales quotas, use of alternative fuels, and new-vehicle emission standards–are intended to control automobile emissions.
working paper |
Dec 1994
working paper |
Sep 1994
working paper |
Oct 1993
working paper |
Jan 1997
book/book chapter |
Oct 1998
working paper
Rubin (1987) has proposed multiple imputations as a general method for estimation ion the presence of missing data. Rubin’s results only strictly apply to Bayesian models, but Schenker and Welsh (1988) directly prove the consistency of multiple imputations inferences when there are missing values of the dependent variable in linear regression models. This paper extends and modifies Schenker and Welsh’s theorems to give conditions where multiple imputations yield consistent inferences for both ignorable and nonignorable missing data in exogenous variables. One key condition is that the imputed values must have the same conditional first and second moments as the true values. Monte Carlo studies show that the multiple imputation covariance estimates are accurate for realistic sample sizes. They also support the applications of multiple imputations in Brownstone and Valletta (1991), where the multiple imputations estimates substantially changed the qualitative conclusions implied by the model.
working paper |
Jun 1991
working paper |
Jun 1989
working paper |
Nov 1991
working paper |
Nov 1988
working paper |
Sep 1991
published journal article
Diesel heavy-duty drayage trucks (HDDTs) serving the Ports of Los Angeles and Long Beach in Southern California are large contributors to regional air pollution, but cost remains an obstacle to replacing them with zero-emission HDDTs. To quantify the health and equity impacts of operating diesel HDDTs, we built a microscopic simulation model of a regional freeway network and quantified their emissions of PM2.5 (particulate matter with a diameter < 2.5 μm) and CO2 in 2012 and 2035, before estimating their contribution to selected health outcomes. We found that 483 premature deaths ($5.59 billion) and 15,468 asthma attacks could be attributed to HDDTs in 2012. Regulations and technological advances could shrink these impacts to 106 premature deaths ($1.31 billion) and 2,142 asthma attacks in 2035 (over 2/3 accruing to disadvantaged communities) despite population growth and a 145 % jump in drayage traffic, but they still justify replacing diesel HDDTs with zero-emission HDDTs by 2035.
conference paper
published journal article
book/book chapter
‘Hall Sensor Security, The’ published in ‘Encyclopedia of Cryptography, Security and Privacy’
conference paper
Localization in high-level Autonomous Driving (AD) systems is highly security critical. Recently, researchers found that state-of-the-art Multi-Sensor Fusion (MSF) based localization is vulnerable to GPS spoofing, which can cause road hazards such as driving off road or onto the wrong way. In this work, we perform the first exploration of using Lane Detection (LD) to detect and correct deviations caused by such attacks and design a novel LD-based system-level defense, LD3. We evaluate LD3 on real-world sensor traces and find that it can achieve effective and timely detection against the state-of-the-art attack with 100% true positive rates and 0% false positive rates. Results show that LD3 can be highly effective at steering the AD vehicle to safely stop within the current traffic lane. We implement LD3 on 2 open-source AD systems and validate its end-to-end defense capability using an industry-grade AD simulator and also in the physical world with a real vehicle-sized AD R&D vehicle.
Phd Dissertation
An increasing number of alternative vehicle fuel and powertrain options are evolving for both light-duty vehicles (LDVs) and heavy-duty vehicles (HDVs) to combat climate change and degraded air quality. Electricity, hydrogen, substitute natural gas, renewable gasoline, and renewable diesel are examples of alternative fuels, while internal combustion engines, fuel cell engines, plug-in battery engines, hybrids, plug-in hybrids, and electrical drivetrains are examples of components comprising powertrains. With such a diverse set of options for LDVs and HDVs, a systematic evaluation of the options that meet environmental goals at a minimum cost is required. Using linear programming with fuel pathway and vehicle costs, emission constraints, realistic growth scenarios for travel and technology, and fuel feedstock availability, a methodology is developed (“Transportation Rollout Affecting Cost and Emissions, TRACE”) to assess combinations of fuel and vehicle pathways. Each pathway has an associated efficiency, cost, and emission of greenhouse gases (GHGs) and criteria air pollutants (CAPs). Techno-economic data from the literature and Wright’s Law project the cost of infrastructure to produce, distribute, and dispense fuel, and to produce vehicles through 2050. The results from a Reference Case, comprised of business-as-usual fossil fuel and internal combustion vehicles (ICVs), projects costs of $1.43 trillion. For current LDV regulations in California, the optimization suggests adoption of ICVs fueled by renewable gasoline in the early years with many plug-in hybrid electric vehicles, a large population of zero-emission battery electric vehicles starting in 2030, and significant plug-in fuel cell electric vehicle (PFCEV) adoption in 2050. For all modeled HDV vocations (linehaul, drayage, refuse, and construction), TRACE projects ICVs fueled by renewable diesel until 2045, after which hybrids and PFCEVs are adopted for all vocations except refuse. This LDV and HDV rollout is projected to cost $1.28 trillion by 2050, 10% less than the Reference Case. Significant factors affecting results include battery costs, change in vehicle miles traveled, and zero-emissions vehicles (ZEV) constraints. For cases with proactive ZEV inducements, plug-in FCEVs displace ICVs while satisfying the long range and short fueling attributes provided today by ICVs, reducing GHGs an additional 18% and CAPs up to an additional 40%.
published journal article
BACKGROUND AND AIM: Risk perception plays an important role in developing response actions to wildfires and can be influenced by a variety of factors. We aimed to conduct a systematic review to compile a comprehensive list of factors that affect the public’s wildfire risk perception. METHOD: We performed an online search for PubMed, ProQuest, and Web of Science databases to identify research published between January 2000 and August 2022. Studies reporting factors related to risk perception based on surveys were included in the review. RESULTS: From 3,466 papers retrieved, 20 studies met our screening criteria, and 16 were conducted in the United States. Several major factors were identified as influential factors for the risk perception of wildfires: sociodemographic characteristics, property ownership, living environment, prior wildfire-related experience, and wildfire-related information resources. The most common factors studied were age, income, education, dense vegetation around the residence, and prior wildfire experience. The associations of age and prior experience with wildfire risk perception were largely inconsistent across papers, with some papers associating older age and having prior wildfire experience with lower risk perception, while others concluded the opposite or no association at all. Other factors, such as owning a property and being able to receive wildfire-related information from different resources were associated with higher risk perception in most of the studies. CONCLUSIONS: To our knowledge, this is the first review to summarize associations of factors with wildfire-related risk perception. Future studies can provide further investigations and theories to explain inconsistent results for certain variables.
