conference paper

Distributed Radiance Fields for Edge Video Compression and Metaverse Integration in Autonomous Driving

2024 IEEE International Conference on Smart Computing (SMARTCOMP)

Publication Date

June 1, 2024

Author(s)

Eugen Šlapak, Matúš Dopiriak, Mohammad Al Faruque, Juraj Gazda, Marco Levorato

Abstract

The metaverse is a virtual space that combines physical and digital elements, creating immersive and connected digital worlds. For autonomous mobility, it enables new possibilities with edge computing and digital twins (DTs) that offer virtual prototyping, prediction, and more. DTs can be created with 3D scene reconstruction methods that capture the real world’s geometry, appearance, and dynamics. However, sending data for real-time DT updates in the metaverse, such as camera images and videos from connected autonomous vehicles (CAVs) to edge servers, can increase network congestion, costs, and latency, affecting metaverse services. Herein, a new method is proposed based on distributed radiance fields (RFs), multi-access edge computing (MEC) network for video compression and metaverse DT updates. RF-based encoder and decoder are used to create and restore representations of camera images. The method is evaluated on a dataset of camera images from the CARLA simulator. Data savings of up to 80% were achieved for H.264 I-frame – P-frame pairs by using RFs instead of I-frames, while maintaining high peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) qualitative metrics for the reconstructed images. Possible uses and challenges for the metaverse and autonomous mobility are also discussed.

Suggested Citation
Eugen Šlapak, Matúš Dopiriak, Mohammad Abdullah Al Faruque, Juraj Gazda and Marco Levorato (2024) “Distributed Radiance Fields for Edge Video Compression and Metaverse Integration in Autonomous Driving”, in 2024 IEEE International Conference on Smart Computing (SMARTCOMP). 2024 IEEE International Conference on Smart Computing (SMARTCOMP), pp. 71–76. Available at: 10.1109/SMARTCOMP61445.2024.00031.

Phd Dissertation

Built Environment and Psychological Well-Being: The Role of The Third Place and Neighborhood Walkability

Publication Date

August 31, 2021

Author(s)

Abstract

The level of life quality can be closely tied to the quality of our surrounding environments. Though the psychological benefits of the natural environment have been exhaustively studied, we still have a limited understanding of the mechanism behind the built environment’s role in psychological well-being. Given that urbanization is an ongoing phenomenon, how to create the urban environment healthier and happier for people who spend time in the place should be understood. For this reason, this study is designed to understand the impact of the urban environment on people’s psychological well-being throughout a three-part empirical study. Before these studies, I proposed a theoretical framework that can explain the underlying mechanism behind the relationship between the built environment and psychological well-being by adopting two key concepts, walkability and third place.In the first empirical study, I delved into the role of third places for the psychological well-being of people by conducting a survey. This study found that third places can be psychologically restorative places and have stress-relieving effects. By serving as a resting place for contemporary people, third places were found to be the most popular resting place for them. Also, this study found that third places should be easily accessible, have enough space with chairs and tables, and provide openness for people to frequent the places. In the second study, I tested the impact of accessible (i.e., numbers of third places) and walkable neighborhood design on community-wide psychological well-being. This study measured psychological well-being by translating tweets into the level of mood and collected neighborhoods’ sociodemographic characteristics throughout the City of Los Angeles. Using multiple linear regression with ordinary least squares, this study assessed the impact of walkability and accessibility on community-wide psychological well-being. These research findings showed that walkability and accessibility can raise the level of psychological well-being of people. Also, the number of third places was more crucial for low-walkable communities. Lastly, the last study focused on providing an in-depth discussion on the applicability of prediction models and deep neural networks (DNN) in urban planning and policy to create healthy urban environments. To that end, this study developed two prediction models by using deep neural network (DNN): Binary mood classification model and Crime regression models. This study’s findings showed that DNN has a great potential in urban planning and policy to develop advanced prediction models using big data. However, this study also showed that prediction models can be more applicable when the output data is objective and concrete and can be explained by spatial patterns.

Suggested Citation
NARAE LEE (2021) Built Environment and Psychological Well-Being: The Role of The Third Place and Neighborhood Walkability. PhD Dissertation. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991035329554904701.

published journal article

The Becker-DeGroot-Marschak mechanism and generalized utility theories: Theoretical predictions and empirical observations

Theory and Decision

Publication Date

March 1, 1993

Author(s)

Robin Keller, Uzi Segal, Tan Wang

Abstract

Karni and Safra [8] prove that the Becker-DeGroot-Marschak mechanism reveals a decision maker’s true certainty equivalent of a lottery if and only if he satisfies the independence axiom. Segal [17] claims that this mechanism may reveal a violation of the reduction of compound lotteries axiom. This paper empirically tests these two interpretations. Our results show that the second interpretation fits better with the collected data. Moreover, we show by means of some nonexpected utility examples that these results are consistent with a wide range of functionals.

Suggested Citation
L. Robin Keller, Uzi Segal and Tan Wang (1993) “The Becker-DeGroot-Marschak mechanism and generalized utility theories: Theoretical predictions and empirical observations”, Theory and Decision, 34(2), pp. 83–97. Available at: 10.1007/bf01074895.

published journal article

The impact of long-term exposure to traffic-related air pollution and genetic susceptibility on Parkinson’s disease

ISEE Conference Abstracts

Publication Date

August 15, 2024

Author(s)

Dayoon Kwon, Cynthia Kusters, Kimberly Paul, Jun Wu, Jeff Bronstein, Christina Lill, Beate Ritz

Abstract

BACKGROUND AND AIM[|]Although environmental and genetic factors have been linked to Parkinson’s disease (PD), the influence of genetic susceptibility on the association between long-term exposure to traffic-related air pollution and PD is not well understood.[¤]METHOD[|]Our case-control analysis included 664 PD and 733 population controls, who also provided blood samples. We estimated annual average traffic-related air pollutant concentrations (represented by carbon monoxide; CO) at residential and workplace locations from 1981 to 2016 using the California Line Source Dispersion Model version 4. Long-term exposures were calculated as 10-year averages with a 5-year lag time prior to a PD diagnosis for cases and the interview date for controls and we categorized it as high/low using a median cut. A polygenic risk score (PRS) was computed by summing the effect estimates of well-known risk alleles from existing genome-wide association studies (GWAS) summary statistics with data from individuals genetic array to assess individual genetic risks for PD. Logistic regression models were employed to estimate odds ratios (OR) and 95% confidence interval (CI), adjusting for age, race, sex, education, and study wave, for the effect of genetic risk on the association between air pollution exposure and PD risk.[¤]RESULTS[|]The OR for PD among individuals with high PD-PRS risk (> median) and high CO exposure (> median) at residences was 2.55 (95% CI: 1.86, 3.48) and 3.62 (2.11, 6.18) at workplaces compared to individuals with low PD-PRS and low CO. Gene-environment interactions were observed on a multiplicative scale (p = 0.05) at residential locations.[¤]CONCLUSIONS[|]Our findings suggest that a combination of long-term exposure to air pollution from traffic and genetic susceptibility contributes to the risk of developing PD.[¤]

Suggested Citation
Dayoon Kwon, Cynthia Kusters, Kimberly Paul, Jun Wu, Jeff Bronstein, Christina Lill and Beate Ritz (2024) “The impact of long-term exposure to traffic-related air pollution and genetic susceptibility on Parkinson’s disease”, ISEE Conference Abstracts, 2024(1). Available at: 10.1289/isee.2024.1369.

published journal article

Operational benefits and challenges of shared-ride automated mobility-on-demand services

Transportation Research Part A: Policy and Practice

Publication Date

April 1, 2020

Author(s)

Michael Hyland, Hani Mahmassani

Abstract

This paper presents a quantitative analysis of the operations of shared-ride automated mobility-on-demand services (SRAMODS). The study identifies (i) operational benefits of SRAMODS including improved service quality and/or lower operational costs relative to automated mobility-on-demand services (AMODS) without shared rides; and (ii) challenges associated with operating SRAMODS. The study employs an agent-based stochastic dynamic simulation framework to model the operational problems of AMODS. The agents include automated vehicles (AVs), on-demand user requests, and a central AV fleet controller that can dynamically change the plans (i.e. routes and AV-user assignments) of AVs in real-time using optimization-based control policies. The agent-based simulation tool and AV fleet control policies are used to test the operational performance of AMODS under a variety of scenarios. The first set of scenarios vary user demand and a parameter constraining the maximum user detour distance. Results indicate that even with a small maximum user detour distance parameter value, allowing shared rides significantly improves the operational efficiency of the AV fleet, where the efficiency gains stem from economies of demand density and network effects. The second set of scenarios vary the mean and coefficient of variation of the curbside pickup time parameter; i.e. how long an AV must wait curbside at a user’s pickup location before the user gets inside the AV. Results indicate that increases in mean curbside pickup time significantly degrade operational performance in terms of user in-vehicle travel time and user wait time. The study quantifies the total system (user plus fleet controller) cost as a function of mean curbside pickup time. Finally, the paper provides an extensive discussion of the implications of the quantitative analysis for public-sector transportation planners and policy-makers as well as for mobility service providers.

Suggested Citation
Michael Hyland and Hani S. Mahmassani (2020) “Operational benefits and challenges of shared-ride automated mobility-on-demand services”, Transportation Research Part A: Policy and Practice, 134, pp. 251–270. Available at: 10.1016/j.tra.2020.02.017.

working paper

Density Estimation using Inductive Loop Signature based Vehicle Re-identification and Classification

Abstract

This paper presents a new method for estimating traffic density on freeways, and an adaptation for real-time applications. This method uses re-identified vehicles and their travel times estimated from a real-time vehicle re-identification (REID) system which attempts to anonymously match vehicles based on their inductive signatures. The accuracy of the section- 6 based density estimation algorithm is validated against ground-truth data obtained from recorded video for a six-lane, 0.66-mile freeway segment of I-405N in Irvine, California, during the morning peak period. The proposed density estimation algorithm results are compared against a g-factor based method which relies on inductive loop detector occupancy data and estimated vehicle lengths from the Caltrans Performance Measurement System (PeMS) as well as a selected REID method which uses a sparse REID algorithm based on long vehicle detection and volume counts at detector stations. Although the g-factor approach produces real-time density estimates, it requires seasonally calibrated parameters. In addition to the calibration effort to maintain overall accuracy of the system, the g-factor approach will also produce errors in density estimation if the actual composition of vehicles yields a different observed g-factor from the calibrated value. In contrast, the proposed method uses an existing vehicle re-identification model based on the matching of inductive vehicle signatures between two locations spanning a freeway section. This approach does not require assumptions on the vehicle composition, hence does not require calibration. The proposed algorithm obtained section-based density measures with a mean absolute percentage error (MAPE) of less than four percent when compared against groundtruth data and provides accurate density estimates even during congested conditions, improving both the PeMS and selected alternative REID based methods.

Suggested Citation
Sarah Hernandez, Andre Tok and Stephen G. Ritchie (2013) Density Estimation using Inductive Loop Signature based Vehicle Re-identification and Classification. Working Paper UCI-ITS-WP-13-4. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/3x50n93f.

published journal article

Exploring the role of ride-hailing in trip chains

Transportation

Abstract

Ride-hailing can potentially provide a variety of benefits to individuals who need to chain several activities together within a single trip chain, relative to other travel modes. Using household travel diary/survey data, the goal of this study is to assess the role ride-hailing currently plays within trip chains. Specifically, the study aims to determine, within trip chains, who uses ride-hailing services, for what trip/activity purposes, and to/from what types of areas, as well as the characteristics of trip chains that involve ride-hailing segments. To meet these objectives, the study estimates a binary logit model using 2017 National Household Travel Survey data, where the dependent variable denotes the inclusion of at least one ride-hailing trip within a trip chain. Similar to the non-trip-chaining ride-hailing literature, this study indicates that trip chains with ride-hailing legs are positively associated with travelers who are younger, live in high-income households, frequently use transit, and reside in high-density areas. However, this study includes novel findings indicating statistically significant relationships between ride-hailing and trip chains that end in healthcare and social/recreational activities. Moreover, trip chains with ride-hailing tend to have fewer stops and longer activity durations than trip chains without ride-hailing. This study also includes nested logit choice models, wherein the dependent variable denotes the primary mode (ride-hailing, transit, personal vehicle, or non-motorized transport) of a trip chain. These model results provide additional insights into the role of ride-hailing within trip chains, as they allow for cross-mode comparisons. The paper discusses the potential transportation planning and policy implications of the model results as well as future research directions.

Suggested Citation
Tanjeeb Ahmed and Michael Hyland (2023) “Exploring the role of ride-hailing in trip chains”, Transportation, 50(3), pp. 959–1002. Available at: 10.1007/s11116-022-10269-w.

working paper

Development of Hardware in the Loop Simulation and Paramics/VS-PLUS Integration

Abstract

The report describes three research efforts carried out under a project titled “Development of Hardware-in-the-Loop (HiL) Simulation and Paramics/VS-PLUS Integration” sponsored by the California Department of Transportation (Caltrans) under Task Order 5311. The first effort developed and evaluated traffic signal optimization with Hardware-in-the-Loop Simulation (HiLS), using the NIATT Controller Interface Device (CID) manufactured by McCain Traffic Supply to provide real-time linkage between the Paramics microscopic simulation and a NEMA TS1 controller. An adaptive control system incorporated the traffic flow prediction model to predict the traffic flows from the surrounding intersections, and an online signal optimization model was used to obtain the signal timing plan for the subsequent cycle, based on the traffic flows predicted in the previous cycle. The performance of the proposed adaptive control system was evaluated through a case study in which HiLS is applied to a small urban network in Logan, Utah. The second effort developed a Paramics plug-in that worked over a serial port connection to a specially modified 170 for HiL operation. After this initial development, the NIATT/McCain CID was configured to work as a Paramics plug-in with both 170 and 2070 controllers, and experiments were carried out to compare the performance of Paramics simulations with the UC Irvine Paramics signal controller plug-in with HiLS. In the third effort, investigation and evaluation of integrated Paramics/VS-PLUS software was carried out, resulting in a user’s guide for use of the integrated Paramics/VS-PLUS simulation software.

working paper

Heterogeneity in Motorists' Preferences for Time Travel and Time Reliability: Empirical Findings from Multiple Survey Data Sets and Its Policy Implications

Publication Date

January 1, 2002

Author(s)

Abstract

The deregulation experience in airline, banking, and telecommunication suggests that the heterogeneity in consumers’ preferences has important policy significance. However, the varied nature in motorists’ preferences has been hardly recognized in urban passenger transportation sector. In this public sector, the public authority generally offers a uniform class of services to all potential users. This dissertation employs the new advances in econometrics on survey data sets from road pricing experiment in Los Angeles area to study the diversity in motorists’ preferences for travel time and travel time reliability. The empirical findings are used to explore the efficiency and distributional effects of road pricing that accounts for users’ heterogeneity.

This dissertation found substantial heterogeneity in motorists’ preferences for both travel time and travel time reliability. Furthermore, based on a simulation model, this dissertation found that road pricing policies catering to varying preferences can substantially increase efficiency while maintaining the same political feasibility as the current experiments. This dissertation also explores how to apply the recent developments in Bayesian econometrics to estimate the multinomial probit models combining different sources of data, which can be used to estimate the diversity in peoples’ preferences with more flexibility in model specification.