conference paper

Communication throughput of vehicular ad hoc networks

Proceedings of the 4th IEEE vehicular network conference (VNC 2012), seoul, south korea

Publication Date

January 1, 2012

Author(s)

Suggested Citation
Hao Yang and W.-L. Jin (2012) “Communication throughput of vehicular ad hoc networks”, in Proceedings of the 4th IEEE vehicular network conference (VNC 2012), seoul, south korea.

working paper

Projecting Use of Electric Vehicles from Household Vehicle Trials: Trial and Error?

Publication Date

September 5, 1998

Abstract

In 1995-96, the authors participated in an eight-month long trial of prototype EVs, with the proviso that we could use some of the results for academic research. We were particularly interested in comparing data collected from trials with matched data collected from a panel survey. Our objective was to better understand vehicle trials as a source of information for transportation planning and market research, beyond the usual consumer preference information gathered for vehicle design purposes. The methodological issues were of particular concern, for as we discuss in the next section, trials provide useful data at one level, but they can also introduce new sources of bias and uncertainty to data collection and interpretation. We also investigated how perceptions towards EVs would change with the “hands-on” experience of a trial. In this paper we report findings from this trial, with a particular emphasis upon the methodological issues. We intentionally do not discuss purchase intentions, and focus, instead, upon a broader set of results. An objective is to provide transportation planners with useful data about characteristics like vehicle miles travelled, intra-household vehicle switching, and long trip taking when there are multiple data sources from the same respondents, including travel diaries and pre- and post trial panel survey data. This provides insight into how households might choose to use future electric vehicles, and it also addresses the issue of whether trials are an effective and efficient data collection method. The research is expected to provide useful information for those who wish to organize and interpret data from future consumer vehicle trials and it also provides more limited evidence about how households would use future electric vehicles that had a limited range.

Suggested Citation
Thomas F. Golob and Jane Gould (1998) Projecting Use of Electric Vehicles from Household Vehicle Trials: Trial and Error?. Working Paper UCI-ITS-WP-98-2. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/3d82n6k5.

published journal article

Coordinated flow model for strategic planning of autonomous mobility-on-demand systems

Transportmetrica A: Transport Science

Abstract

High-quality strategic planning of autonomous mobility-on-demand (AMOD) systems is critical for the success of the subsequent phases of AMOD system implementation. To assist in strategic AMOD planning, we propose a dynamic and flexible flow-based model of an AMOD system. The proposed model is computationally fast while capturing the state transitions of two coordinated flows (i.e. co-flows): the AMOD service fleet vehicles and AMOD customers. Capturing important quantity dynamics and conservations through a system of ordinary differential equations, the model can economically respond to a large number and a wide range of scenario-testing requests. The paper illustrates the model efficacy through a basic example and a more realistic case study. The case study envisions replacing Manhattan’s existing taxi service with a hypothetical AMOD system. The results show that even a simple co-flow model can robustly predict the systemwide AMOD dynamics and support the strategic planning of AMOD systems.

Suggested Citation
Jiangbo (Gabe) Yu and Michael F. Hyland (2023) “Coordinated flow model for strategic planning of autonomous mobility-on-demand systems”, Transportmetrica A: Transport Science, 21(2), pp. 1–39. Available at: 10.1080/23249935.2023.2253474.

working paper

A Joint Household Travel Distance Generation And Car Ownership Model

Publication Date

March 1, 1989

Associated Project

Working Paper

Reprint No. 8

Areas of Expertise

Abstract

The product of this research is a dynamic simultaneous equations model of car ownership and modal travel distances as a function of income. The data are from the Dutch National Mobility Panel (1984-1987); and four modes are encompassed: car driver, car passenger, train, and bus-tram-subway. A novel feature of the simultaneous equation system is the consistent treatment of the measurement scales of the variables: ordered probit functions for income and car ownership and tobit functions for distances. The dynamics are expressed in terms of pooled panel survey measurements of the variables at two points in time one year apart. This allows the identification of lagged responses and serial correlations over a one-year time-horizon. Results indicate that increased car ownership and car kilometers at time T2 is influenced by heavy usage of other modes at time T1. This indicates there are significant noninstantaneous adjustments of car ownership and usage that represent modal substitutions.

Suggested Citation
Thomas F. Golob and Leo Van Wissen (1989) A Joint Household Travel Distance Generation And Car Ownership Model. Working Paper Reprint No. 8. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/72h4k912.

published journal article

The Association Between Ambient Fine Particulate Matter and Spontaneous Preterm Birth: Evidence From a Large Pregnancy Cohort in Southern California [ID 1244]

Obstetrics & Gynecology

Publication Date

June 1, 2025

Author(s)

Alexa N. Reilly, Anqi Jiao, Tarik Benmarhnia, Yi Sun, Chantal Avila, Jun Wu

Abstract

INTRODUCTION:  Although studies have found positive associations between exposure to PM2.5 and preterm birth, distinguishing between spontaneous preterm birth (sPTB) and iatrogenic preterm birth (iPTB) was a challenge in previous research. This study examined associations between total PM2.5 and PM2.5 constituent exposure and sPTB. METHODS:  This is a retrospective cohort study from 2008 to 2018 of singleton live births within a large health care system in southern California, United States. Daily total PM2.5 concentrations and monthly data on five PM2.5 constituents (sulfate, nitrate, ammonium, organic matter, and black carbon) were obtained. The average concentrations of total PM2.5 and constituents were calculated over the pregnancy and by trimester. A novel natural language processing algorithm was used to identify sPTB in medical records. Discrete-time survival models were used to estimate the associations of total PM2.5 and constituents with sPTB. Effect modifiers included maternal race/ethnicity, educational attainment, household income, and green space. RESULTS:  There were 19,341 (4.7%) sPTBs among 409,037 births. We observed significant associations of sPTB with PM2.5, black carbon, nitrate, and sulfate. The second trimester was the most susceptible window. Significantly higher associations with PM2.5 were observed among mothers with lower educational attainment, lower income, and less green space exposure. CONCLUSIONS/IMPLICATIONS:  Maternal exposures to PM2.5 and specific PM2.5 constituents were associated with an increased risk of sPTB. Mothers with lower socioeconomic status were vulnerable, whereas green space was a protective effect modifier.

Suggested Citation
Alexa N. Reilly, Anqi Jiao, Tarik Benmarhnia, Yi Sun, Chantal Avila and Jun Wu (2025) “The Association Between Ambient Fine Particulate Matter and Spontaneous Preterm Birth: Evidence From a Large Pregnancy Cohort in Southern California [ID 1244]”, Obstetrics & Gynecology, 145(6S), p. 40S. Available at: 10.1097/AOG.0000000000005917.037.

Phd Dissertation

Commercial vehicle classification system using advanced inductive loop technology

Abstract

Commercial vehicles typically represent a small fraction of vehicular traffic on most roadways. However, their influence on the economy, environment, traffic performance, infrastructure, and safety are much more significant than their diminutive numerical presence suggests. This dissertation describes the development and prototype implementation of a new high-fidelity inductive loop sensor and a ground-breaking commercial vehicle classification system based on the vehicle inductive signatures obtained from this sensor technology. This new sensor technology is relatively easy to install and has the potential to yield reliable and highly detailed vehicle inductive signatures for advanced traffic surveillance applications. The Speed PRofile INterpolation Temporal-Spatial (SPRINTS) transformation model developed in this dissertation improves vehicle signature data quality under adverse traffic conditions where acceleration and deceleration effects can distort inductive vehicle signatures. The axle classification model enables commercial vehicles to be classified accurately by their axle configuration. The body classification models reveal the function and unique impacts of the drive and trailer units of each commercial vehicle. Together, the results reveal the significant potential of this inductive sensor technology in providing a more comprehensive commercial vehicle data profile based on a unique ability to extract both axle configuration information as well as high fidelity undercarriage profiles within a single sensor technology to provide richer insight on commercial vehicle travel statistics.

Suggested Citation
Yeow Chern Andre Tok (2008) Commercial vehicle classification system using advanced inductive loop technology. Ph.D.. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/1go3t9q/alma991035092965004701 (Accessed: October 14, 2023).

Phd Dissertation

Combinatorial auctions: Applications in freight transportation contract procurement

Publication Date

June 30, 2003

Abstract

This dissertation focuses on the development of optimization methods and approximation algorithms for combinatorial auctions, particularly with application to the contract procurement problem in freight transportation. Combinatorial auctions are auctions in which a set of heterogeneous items are sold simultaneously and in which bidders can bid for their preferred combinations of items. They involve many difficult optimization problems both for auction hosts and bidders and have received significant attention from computer scientists, operations researchers and economists recently. Large shippers (typically manufacturing companies or retailers) have begun to use this method to procure services from trucking companies and logistics services providers. This dissertation first analyzes the economic impact of combinatorial auction-based procurement methods both on shippers and carriers using a simulation study and reveals that both parties can benefit from this economically efficient price discovery mechanism. While the majority of prior research has been from an auctioneer’s perspective, we demonstrate that bidders have even more complicated optimization problems in combinatoiral auctions. The bid construction problem, that is, how bidders should identify and construct beneficial bids, is very hard and remains an open question. This dissertation investigates this problem and proposes an optimization based approximation method that involves solving an NP-hard problem only once, yielding significant improvements in computational efficiency. Further, the current state of trucking and third party logistics industries are examined. The trucking industry is very competitive and small carriers are operating under thin margins. This dissertation addresses these issues by proposing an auction based collaborative carrier network in which participating carriers can identify inefficient lanes from daily operations quickly and exchange them with partners under an auction protocol. This system is proved to be Pareto efficient. Further, decision problems are discussed regarding how carriers should identify inefficient operations and how to make and select bids. This represents an effort to use advanced auction mechanisms to enhance the carriers’ operational efficiencies.

Suggested Citation
Jiongjiong Song (2003) Combinatorial auctions: Applications in freight transportation contract procurement. PhD Dissertation. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991035093498004701.

published journal article

An extension of Newell's simplified kinematic wave model to account for first-in-first-out violation: With an application to vehicle trajectory estimation

Transportation Research Part C: Emerging Technologies

Publication Date

December 1, 2019
Suggested Citation
Adrian Rey, Wen-Long Jin and Stephen G. Ritchie (2019) “An extension of Newell's simplified kinematic wave model to account for first-in-first-out violation: With an application to vehicle trajectory estimation”, Transportation Research Part C: Emerging Technologies, 109, pp. 79–94. Available at: 10.1016/j.trc.2019.10.005.

published journal article

Asymptotic traffic dynamics arising in diverge–merge networks with two intermediate links

Transportation Research Part B: Methodological

Publication Date

June 1, 2009

Author(s)

Suggested Citation
Wen-Long Jin (2009) “Asymptotic traffic dynamics arising in diverge–merge networks with two intermediate links”, Transportation Research Part B: Methodological, 43(5), pp. 575–595. Available at: 10.1016/j.trb.2008.10.002.

published journal article

Association of urban green space with metabolic syndrome and the role of air pollution

Landscape and Urban Planning

Publication Date

August 1, 2024

Author(s)

Yi Sun, Yunli Chen, Yuanyuan Huang, Yan Luo, LiPing Yan, Sailimai Man, Canqing Yu, Jun Lv, Chuangshi Wang, Jun Wu, Heling Bao, Bo Wang, Liming Li, Hui Liu
Suggested Citation
Yi Sun, Yunli Chen, Yuanyuan Huang, Yan Luo, LiPing Yan, Sailimai Man, Canqing Yu, Jun Lv, Chuangshi Wang, Jun Wu, Heling Bao, Bo Wang, Liming Li and Hui Liu (2024) “Association of urban green space with metabolic syndrome and the role of air pollution”, Landscape and Urban Planning, 248, p. 105100. Available at: 10.1016/j.landurbplan.2024.105100.