published journal article
The Scheduling of Consumer Activities: Work Trips
The American Economic Review
Publication Date
June 1, 1982
Archives: Research Products
working paper
Population Uncertainty and the Timing of an Urban Transportation Infrastructure Investment
Publication Date
February 1, 2006
Author(s)
Working Paper
UCI-ITS-WP-06-1
Areas of Expertise
Abstract
This paper analyzes the impacts of stochastic population changes on the timing of an investment that reduces congestion in an open, monocentric city with fixed boundaries. Congestion pricing cannot be implemented, but a welfare-maximizing planner can buy land and build transportation infrastructure. Under certainty, I derive a rule of thumb to evaluate infrastructure investments that corrects a standard benefit-cost analysis. Under uncertainty, I show that relying on a standard benefit-cost ratio could lead to investing in bad projects, or investing prematurely, or ignoring attractive projects because of population barriers and the impacts of the congestion externality on the land market.
Suggested Citation
Jean-Daniel M. Saphores (2006) Population Uncertainty and the Timing of an Urban Transportation Infrastructure Investment. Working Paper UCI-ITS-WP-06-1. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/3kg8g9z4. conference paper
An Empirical Investigation of the Dynamic Processes on Activity Scheduling and Trip Chaining
43rd Annual Meeting of the Western Regional Science Association
Publication Date
February 1, 2004
Author(s)
Areas of Expertise
Suggested Citation
Ming-Sheng Lee and Michael G. McNally (2004) “An Empirical Investigation of the Dynamic Processes on Activity Scheduling and Trip Chaining”. Maui, HI. Available at: https://escholarship.org/uc/item/4nk4q801?conferencePaper. published journal article
Nonstandard second-order formulation of the LWR model
Transportmetrica B: Transport Dynamics
Publication Date
December 23, 2019
Author(s)
Abstract
In this study, we present an equivalent second-order formulation of the LWR model based on Phillips’ model, in which the acceleration rate equals a relaxation term with an infinitesimal relaxation time. We convert the model into a continuum car-following model and demonstrate its equivalence to that of the LWR model. We demonstrate that the nonstandard second-order model is stable, but the original Phillips model is not. We derive conditions for the nonstandard model to be forward-traveling and collision-free, prove that the collision-free condition is consistent with but more general than the CFL condition, and demonstrate that only anisotropic and symplectic Euler discretization methods lead to physically meaningful solutions. Numerically, the nonstandard second-order model has the same shock and rarefaction wave solutions as the LWR model for both Greenshields and triangular fundamental diagrams; for a non-concave fundamental diagram, the collision-free condition, but not the CFL condition, yields physically meaningful results.
Suggested Citation
Wen-Long Jin (2019) “Nonstandard second-order formulation of the LWR model”, Transportmetrica B: Transport Dynamics, 7(1), pp. 1338–1355. Available at: 10.1080/21680566.2019.1617803. Phd Dissertation
Research universities as gateways the expanding roles of higher education institutions and their contribution to economic development
Publication Date
January 1, 2021
Author(s)
Abstract
The past 30 years have witnessed a gradual expansion in the missions of many universities, and in the ways in which they contribute to local and regional economic development. While teaching and research continue to serve as the foundational core of most university missions, increased attention has been afforded to how universities, by their presence and functions, influence the spatial geographies of neighborhoods, cities, and regions. This dissertation research explores the changing roles of research universities in small and medium-sized metropolitan areas with an emphasis on their impacts across the different geographical scales by investigating associations between university presence and (1) growth in foreign-born populations; (2) the attraction and retention of highly educated residents; and (3) student-driven neighborhood change dynamics. The findings of this dissertation extend previous studies emphasizing the increasing importance of higher education institutions to economic development activities at various scales. Results from metropolitan area level analyses demonstrate that counties with large research universities were associated with an increase in foreign-born residents following the 1990 Immigration and Naturalization Act, as well as an increase in highly educated residents in the 2000-2014 period. More specifically, while findings revealed that the presence of research universities generate significant spatial spillovers of highly educated residents from university host counties to metropolitan levels, there was little evidence of such spatially-explicit dynamics occurring amongst foreign-born residents. Furthermore, findings from neighborhood-level analyses indicated that proximity to large research university campuses may play an outsized role on the likelihood of neighborhoods undergoing studentification (i.e., student-driven neighborhood change) in the 2000-2014 period. These results may be indicative of a bifurcation of neighborhoods in university-dominant counties into wealthy and highly educated renter populations situated near the university campus, and relatively less wealthy and less educated homeowners residing on the further away from the campus or on the periphery of the county. By exploring university contributions beyond the spheres of research, teaching, and service contributions, this dissertation presents scholars, urban planners, and policymakers with a more comprehensive portrait of the relationship between universities and their host communities. The evidence of this work suggests that the evolving role of higher education institutions, including their role as gateways for new populations, should be reflected in policymaking which seeks to leverage the locational advantages of research universities for city building or revitalization efforts. Further, policymakers and planners should also be cognizant that scale matters when considering how higher education institutions can better serve their surrounding communities. The contributions of research universities should not be thought of as monolithic or uniform, but should rather be seen as presenting different opportunities and challenges at different geographical levels.
Suggested Citation
Nene, Osutei (2021) Research universities as gateways the expanding roles of higher education institutions and their contribution to economic development. PhD Dissertation. University of California, Irvine,. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991035329641804701. MS Thesis
Red cars reborn : transforming the abandoned Pacific Electric Santa Ana line into a 21st century transit system
Publication Date
December 31, 2005
Author(s)
Areas of Expertise
Suggested Citation
Tyler Bonstead (2005) Red cars reborn : transforming the abandoned Pacific Electric Santa Ana line into a 21st century transit system. MS Thesis. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991032614729704701. published journal article
Evaluation of the California Safe Routes to School legislation: Urban form changes and children’s active transportation to school
American Journal of Preventive Medicine
Publication Date
February 1, 2005
Associated Project
Author(s)
Areas of Expertise
Suggested Citation
Marlon G. Boarnet, Craig L. Anderson, Kristen Day, Tracy McMillan and Mariela Alfonzo (2005) “Evaluation of the California Safe Routes to School legislation: Urban form changes and children’s active transportation to school”, American Journal of Preventive Medicine, 28(2), pp. 134–140. Available at: 10.1016/j.amepre.2004.10.026.Related Publications
working paper |
Jan 2003
Evaluation of the California Safe Routes to School Construction Program
working paper |
Sep 2006
California's Safe Routes to School Program: Impacts on Walking, Bicycling, and Pedestrian Safety
published journal article
A first-order behavioral model of capacity drop
Transportation Research Part B: Methodological
Publication Date
November 1, 2017
Author(s)
Suggested Citation
Wen-Long Jin (2017) “A first-order behavioral model of capacity drop”, Transportation Research Part B: Methodological, 105, pp. 438–457. Available at: 10.1016/j.trb.2017.09.021. published journal article
Extreme Heat and Severe Maternal Morbidity in Southern California: Evidence of Health Disparities from a Large Pregnancy Cohort
ISEE Conference Abstracts
Publication Date
September 17, 2023
Author(s)
Anqi Jiao, Yi Sun, Chantal Avila, Vicki Chiu, John Molitor, Jeff Slezak, David Sacks, Jiu Chiuan Chen, Tarik Benmarhnia, Darios Getahun, Jun Wu
Abstract
BACKGROUND AND AIM: The rate of severe maternal morbidity (SMM) has continued to increase in the United States. We aimed to examine if maternal exposure to extreme heat is associated with the risk of SMM. METHOD: We conducted a retrospective cohort study and included 425,722 singleton pregnancies from Kaiser Permanente Southern California in 2008-2018. Daily maximum temperature data at a 4 km resolution were obtained. An extreme heat day was defined as a day with the daily maximum temperature exceeding a certain threshold. Four percentiles (i.e., 75th, 90th, 95th, and 98th) of daily maximum temperature during the warm season (May-September) in 2007-2018 in Southern California were selected to define the extreme heat day. Long-term exposures included the proportions of extreme heat days during the entire pregnancy and by trimester. Short-term exposures were measured by 12 different heatwave exposures (combining the four thresholds with three durations, i.e., ≥ 2, ≥ 3, and ≥ 4 consecutive days) during the last gestational week. The discrete-time approach and Cox proportional hazards model were used to estimate the long- and short-term associations between heat exposure and SMM, respectively. Stratified analyses were conducted to examine vulnerable subpopulations and the effectiveness of mitigation measures. RESULTS: There were 7,767 (1.8%) SMM cases during delivery hospitalization in this study. Long-term associations with extreme heat were detected in the entire pregnancy and each trimester. Heatwave exposures during the last gestational week were associated with higher risks of SMM. Stronger associations were observed in mothers who were Hispanic, with lower education or incomes, or smokers. More green space may attenuate heat effects. CONCLUSIONS: Long- and short-term maternal exposure to extreme heat can be associated with an increased risk of SMM. More residential green space can be a potential mitigation strategy.
Suggested Citation
Anqi Jiao, Yi Sun, Chantal Avila, Vicki Chiu, John Molitor, Jeff Slezak, David Sacks, Jiu Chiuan Chen, Tarik Benmarhnia, Darios Getahun and Jun Wu (2023) “Extreme Heat and Severe Maternal Morbidity in Southern California: Evidence of Health Disparities from a Large Pregnancy Cohort”, ISEE Conference Abstracts, 2023(1). Available at: 10.1289/isee.2023.EP-162. Phd Dissertation
Location-based Services in Vehicular Networks
Publication Date
January 1, 2013
Author(s)
Areas of Expertise
Abstract
Location-based services have been identified as a promising communication paradigm in highly mobile and dynamic vehicular networks. However, existing mobile ad hoc networking cannot be directly applied to vehicular networking due to differences in traffic conditions, mobility models and network topologies. On the other hand, hybrid architectures in vehicular networks, with ad hoc-based inter-vehicle and infrastructure-based vehicle-to-roadside communications, can facilitate robust and efficient communication services using geographical information. In this dissertation, we focus on the design and evaluation of location-based protocols and algorithms to improve scalability, efficiency, and resiliency in hybrid vehicular networks. We first provide a cross-layer self-localization algorithm for moving vehicles. A new ultra-wide band (UWB) coding method, based on an orthogonal variable spreading factor and time hopping, is proposed for minimum interference during ranging. Then, a UWB based non-metric multidimensional scaling derives accurate and robust self-localization results. In addition, we employ an online compressive sensing scheme to count and localize sparse roadside units (RSUs) for war-driving applications. Online war-driving records received signal strength (RSS) values at runtime, and can recover the number and location of RSUs immediately based on far fewer noisy RSS readings. After obtaining the location information of vehicles and RSUs, we address multiple channel scheduling in hybrid vehicular networks. We use the natural beauty of Latin squares to achieve fair and deterministic scheduling in micro-time scale for channel access and macro-time scale for channel assignment. A grid based scalable scheme is proposed to map Latin squares to grids for dynamic single-radio multi-channel scheduling. Another interference graph based scheme uses nodal location and social centrality to reflect the social behavior patterns related to access in vehicular networks, and then form adaptive clusters for multi-radio multi-channel scheduling. We also investigate several vehicular environments, and propose corresponding location- and environment-aware data dissemination solutions. We first present an efficient on-demand bounce routing method in vehicular tunnels. It applies a hybrid signal propagation model and location-based forwarding metric to choose the best data dissemination strategy. Then, we design a hybrid routing scheme for robust and reliable data dissemination in urban transportation environments, in which the choice of communication method is dependent upon geographical connectivity, by taking network coding based multicast routing in dense network and opportunistic routing using carry and forward method in sparse network. In addition, we propose an online learning based knowledge dissemination in unmanned aerial vehicle (UAV) swarms under delay/disruption-tolerant networking, where each UAV adaptively chooses broadcast probability by learning link status. A fractionated Cyber-Physical System framework, based on partial ordering for knowledge sharing and colored Petri net for work flow, is implemented to achieve distributed knowledge management in UAV swarms. Our extensive simulation and real testbed results show the robustness and efficiency of location-based services in vehicular networks with hybrid architectures.