conference paper
Real-time density estimation using inductive signature technology
Proceedings of the university of california transportation center student conference, UC davis
Publication Date
April 1, 2012
Area of Expertise: Unspecified
published journal article
Airline competition and domestic US airfares: A comprehensive reappraisal
Economics of Transportation
Publication Date
March 1, 2013
Author(s)
Jan Brueckner, Darin Lee, Ethan S. Singer
Suggested Citation
Jan K. Brueckner, Darin Lee and Ethan S. Singer (2013) “Airline competition and domestic US airfares: A comprehensive reappraisal”, Economics of Transportation, 2(1), pp. 1–17. Available at: 10.1016/j.ecotra.2012.06.001. MS Thesis
Performance study of dynamic origin-destination estimation for incremental expansion of urban traffic network simulation models
Publication Date
January 1, 2014
Author(s)
Abstract
The goal of this research is to suggest a new approach for performing dynamic origin-destination estimation on a controlled simulation network that is expanded from an existing/starting network by adding different sub-areas to the existing network. In micro-simulation analyses, estimating origin-destination (OD) is a very time consuming and data intensive process. This research presents an incremental procedure to develop dynamic OD (origin-destination) matrices for a controlled network with different sub-areas added to the starting network to avoid extensive effort in re-estimating the matrices for an existing area for which matrices are already estimated once, thus reducing the time required to obtain the OD matrices for vehicular micro-simulation. Fractions of traffic from existing external origins and destinations to various other origins and destinations are utilized in the scheme to properly develop the origin and destination demand to/from the new origins and destination in the additional areas.
Suggested Citation
Shayesteh Vafai (2014) Performance study of dynamic origin-destination estimation for incremental expansion of urban traffic network simulation models. MS Thesis. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991015039829704701. published journal article
Regulating mobility-on-demand services: Tri-level model and Bayesian optimization solution approach
Transportation Research Part C: Emerging Technologies
Publication Date
April 1, 2021
Author(s)
Florian Dandl, Roman Engelhardt, Michael Hyland, Gabriel Tilg, Klaus Bogenberger, Hani Mahmassani
Abstract
The goal of this paper is to develop a modeling framework that captures the inter-decision dynamics between mobility service providers (MSPs) and travelers that can be used to optimize and analyze policies/regulations related to MSPs. To meet this goal, the paper proposes a tri-level mathematical programming model with a public-sector decision maker (i.e. a policymaker/regulator) at the highest level, the MSP in the middle level, and travelers at the lowest level. The public-sector decision maker aims to maximize social welfare via implementing regulations, policies, plans, transit service designs, etc. The MSP aims to maximize profit by adjusting its service designs. Travelers aim to maximize utility by changing their modes and routes. The travelers’ decisions depend on the regulator and MSP’s decisions while the MSP decisions themselves depend on the regulator’s decisions. To solve the tri-level mathematical program, the study employs Bayesian optimization (BO) within a simulation–optimization solution approach. At the lowest level, the solution approach includes an agent-based transportation system simulation model to capture travelers’ behavior subject to specific decisions made by the regulator and MSP. At the middle and highest levels, the solution approach employs BO for the MSP to maximize profit and for the regulator to maximize social welfare. The agent-based transportation simulation model includes a mode choice model, a road network, a transit network, and an MSP providing automated mobility-on-demand (AMOD) service with shared rides. The modeling and solution approaches are applied to Munich, Germany in order to validate the model. The case study investigates the tolls and parking costs the city administration should set, as well as changes in the public transport budget and a limitation of the AMOD fleet size. Best policy settings are derived for two social welfare definitions, in both of which the AMOD fleet size is not regulated as the shared-ride AMOD service provides significant value to travelers in Munich.
Suggested Citation
Florian Dandl, Roman Engelhardt, Michael Hyland, Gabriel Tilg, Klaus Bogenberger and Hani S. Mahmassani (2021) “Regulating mobility-on-demand services: Tri-level model and Bayesian optimization solution approach”, Transportation Research Part C: Emerging Technologies, 125, p. 103075. Available at: 10.1016/j.trc.2021.103075. published journal article
Electronic integration in the air cargo industry: An information processing model of on-time performance
TRANSPORTATION JOURNAL
Publication Date
January 1, 2001
Author(s)
PW Forster, Amelia Regan
Abstract
This study examines electronic integration in logistics supply chains using the non-integrated U.S. international air cargo industry as a case study. We ask what impact electronic integration has on interorganizational task performance, and hypothesize about factors limiting the effectiveness of electronic integration. Surprisingly, our study does not find evidence of direct impacts of electronic integration on performance, though it does find evidence of indirect impacts of information systems use and performance. The findings suggest that the use of electronic integration as a strategy to improve operational performance across firms is limited by the nature of the interorganizational task, environmental dynamism, and the power relationships between firms in the supply chain.
Suggested Citation
PW Forster and AC Regan (2001) “Electronic integration in the air cargo industry: An information processing model of on-time performance”, TRANSPORTATION JOURNAL, 40(4), pp. 46–61. published journal article
Comparative analysis of SOFC–GT freight locomotive fueled by natural gas and diesel with onboard reformation
Applied Energy
Publication Date
June 1, 2015
Author(s)
Andrew S. Martinez, Jack Brouwer, Scott Samuelsen
Abstract
Due to increasing awareness of the deleterious environmental and health effects of diesel combustion emissions, major regulatory action and policy measures are focused on reducing emissions from diesel engines. Freight operations, including rail-based freight transportation, have received special attention as an industry where major change can be affected, especially in neighborhoods located near operations centers. A FORTRAN-based dynamic simulation model of an SOFC-GT (Solid Oxide Fuel Cell Gas Turbine) system from a prior feasibility study has been adapted to analyze system operation along a representative but demanding route in southern California. In previous simulations with the model, the basic operational feasibility of the system has been demonstrated as well as the in-service operation for pre-reformed fuels. In the current study, the analysis is extended to include reformation of two fuels (diesel and natural gas) onboard the locomotive and analyses of system efficiency, fuel consumption, CO2 emission, and NOx emission that can be attained through careful thermal integration of the reformer unit. Route-averaged fuel-to-wheels system efficiencies of 60% and 52% are predicted for natural gas and diesel fuel, respectively. Additionally, SOFC-GT operation could provide (1) a reduction approaching 98% in NOx for both fuels; (2) a 54% savings in CO2 for operation on natural gas; and (3) a 30% CO2 reduction for operation on diesel fuel compared to state-of-the-art locomotive technology. These gains may be offset by design challenges, especially for the diesel case, due to the requirement for large volumes of water to support the reformation process even for medium-length freight hauling trips. (C) 2015 Elsevier Ltd. All rights reserved.
Suggested Citation
Andrew S. Martinez, Jacob Brouwer and G. Scott Samuelsen (2015) “Comparative analysis of SOFC–GT freight locomotive fueled by natural gas and diesel with onboard reformation”, Applied Energy, 148, pp. 421–438. Available at: 10.1016/j.apenergy.2015.01.093. research report
Real-time mass transport vehicle routing problem: Local routing with global optimization
Publication Date
January 1, 2007
Author(s)
Suggested Citation
R Jayakrishnan (2007) Real-time mass transport vehicle routing problem: Local routing with global optimization. published journal article
Potential Applications of Knowledge-Based Expert Systems in Transportation Planning and Engineering
Transportation Research Record: Journal of the Transportation Research Board
Publication Date
January 1, 1986
Author(s)
Chung Yeh, Stephen Ritchie, Jerry B Schneider
Suggested Citation
Che-I Yeh, Stephen G Ritchie and Jerry B Schneider (1986) “Potential Applications of Knowledge-Based Expert Systems in Transportation Planning and Engineering”, Transportation Research Record: Journal of the Transportation Research Board, (1076), pp. 59–65. Available at: http://onlinepubs.trb.org/Onlinepubs/trr/1986/1076/1076-009.pdf. published journal article
Characterizing pandemic waves: A latent class analysis of COVID-19 spread across US counties
Pattern Recognition Letters
Publication Date
October 1, 2022
Author(s)
Md Yusuf Sarwar Uddin, Rezwana Rafiq
Abstract
The spread of the COVID-19 pandemic is observed to follow the shape of “waves” (i.e., the rise and fall of population-adjusted daily new infection cases with time). Different geographic regions of the world have experienced different position and span of these waves over time. The presence and strength of these waves broadly characterize the dynamics of the pandemic spread in a given area, so their characterization is important to draw meaningful intervention and mitigation plans tailored for that area. In this paper, we propose a novel technique to represent the trend of COVID-19 spread as a sequence of a fixed-length text string defined on three symbols: R (rise), S (Steady), and F (fall). These strings, termed as trend strings, enabled us searching for specific patterns in them (such as for waves). After analyzing county-level infection data, we observe that, US counties—despite their wide variation in trend strings—can be grouped into a number of heterogeneous classes each of which might have a representative COVID spread pattern over time (in terms of presence and propensity of waves). To this end, we conduct a latent class analysis to cluster 3142 US counties into four distinct classes based on their wave characteristics for one year pandemic data (January 2020 to January 2021). We observe that counties in each class have distinct socio-demographics, location, and human mobility characteristics. In short summary, counties have differing number of waves (class 1 counties have only one wave and class 3 counties have three) and their positions also vary (class 1 had the wave later in the year whereas class 3 had waves throughout the year). We believe that this way of characterizing pandemic waves would provide better insights in understanding the complex dynamics of COVID-19 spread and its future evolution, and would, therefore, help in taking class-specific policy interventions.
Suggested Citation
Md Yusuf Sarwar Uddin and Rezwana Rafiq (2022) “Characterizing pandemic waves: A latent class analysis of COVID-19 spread across US counties”, Pattern Recognition Letters, 162, pp. 31–39. Available at: 10.1016/j.patrec.2022.08.017. published journal article
Resource location and relocation models with rolling horizon forecasting for wildland fire planning
INFOR: Information Systems and Operational Research
Publication Date
February 1, 2011