research report

Resiliency Impacts of Plug-in Electric Vehicles in a Smart Grid

Publication Date

February 1, 2021

Author(s)

Abstract

This project assesses the impact of plug-in electric vehicles (PEVs) on the resiliency of the electricity distribution system by: (1) Assessing the use of PEVs as a resiliency resource during grid outages (Mobility Services+), (2) Assessing and simulating the impact of PEVs on the distribution infrastructure during normal operations, and (3) Determining the local environmental impact of clustering PEVs. A previously developed model of a smart grid consisting of two distribution circuits and a distribution substation was modified to enable the use of PEVs in vehicle-to-home (V2H) and vehicle-to-grid (V2G) configurations. Scenarios were simulated in which PEVs were used to serve critical loads in a home or community shelters, and a model was developed to assess the feasibility of using PEVs in grid restoration, which determined the inrush current of the substation transformer to determine the required power and energy for startup. The use of clustered PEVs and scattered PEVs in grid restoration was also considered. During normal operations, the stress on system components from high PEV demand resulted in accelerated aging and possible failure, thereby negatively impacting distribution infrastructure during normal grid operations. Smart charging is required to retain an acceptable level of resiliency. In contrast, during grid outages, this study demonstrated that PEVs can be used as an environmentally friendly resiliency resource to both serve critical loads and facilitate grid restoration with the qualification that implementation requires system upgrades including smart switches, upgraded inverters, energy management systems, and communication links.

Suggested Citation
Ghazal Razeghi, Jennifer Lee and G. Scott Samuelsen (2021) Resiliency Impacts of Plug-in Electric Vehicles in a Smart Grid. Available at: https://escholarship.org/uc/item/4j19d5p1 (Accessed: October 11, 2023).

conference paper

A freight transshipment network model for forecasting commodity and cyclic commercial vehicle flows

Proceedings of the 91st annual meeting of the transportation research board

Publication Date

January 1, 2012

Abstract

A freight forecast model that assigns commodity flows to cyclic commercial vehicles is proposed in this study. The commercial vehicles are formulated to traverse in cycles and include loading and unloading costs at zone centroids. Empty hauls can be tracked, as can transshipment flows by commodity type and by inbound and outbound modes. A linear programming formulation is proposed as well as nonlinear objectives for link and transshipment congestion. An inverse nonlinear programming approach using Karush-Kuhn-Tucker conditions is formulated to calibrate the congestion parameters of this model such that observed flow variables are optimal. Because the forward problem is convex and composed of only equality or non-negativity constraints, it can be readily solved with classical nonlinear optimization methods instead of treating the inverse problem as a nonlinear complementarity problem. The models are tested on a 6-node network with up to 54 transshipment activities. The model is shown to be sensitive to supply side changes on links and transshipment facilities or to fuel cost changes. The appendix includes an inverse traffic assignment problem using the inverse nonlinear programming method.

Suggested Citation
Joseph Y.J. Chow and Stephen G. Ritchie (2012) “A freight transshipment network model for forecasting commodity and cyclic commercial vehicle flows”, in Proceedings of the 91st annual meeting of the transportation research board, p. 30p.

published journal article

Motivating students to pursue transportation careers. Implementation of Service-Learning Project on Transit

Transportation Research Record

Publication Date

January 1, 2015
Suggested Citation
Sarah Hernandez and Stephen G. Ritchie (2015) “Motivating students to pursue transportation careers. Implementation of Service-Learning Project on Transit”, Transportation Research Record, 2480(1), pp. 30–37. Available at: 10.3141/2480-04.

working paper

Modeling Land Use and Transportation: An Interpretive Review for Growh Areas

Publication Date

October 30, 1988

Author(s)

Yossi Berechman, Kenneth Small

Working Paper

UCTC No. 1

Areas of Expertise

Abstract

Urban growth is taking new forms in recently urbanized or formerly suburban areas, characterized by low density, heavy dependence on automobile transportation, and multiple activity centers. In order to understand better such ‘contemporary urban areas’, researchers need land-use models that realistically capture the key features of such areas and that can handle detailed data sets.We review the literature on large-scale land-use modeling with this objective in mind. Characterizing the known models along several dimensions describing purpose, conceptual basis, mathematical content, and level of detail, we select models that are representative of the range of approaches taken. Six of these are reviewed in detail, and four others are discussed more briefly.We find that the existing literature forces one to choose between tractability and suitability for contemporary urban areas. The key omission in the tractable models is economies of agglomeration that would help explain the emergence of subcenters. Most tractable models also lack a dynamic structure suitable for handling rapid disequilibrium growth. Models that contain these two features are suitable for broad-brush computer simulation, but they cannot be calibrated with real disaggregated land-use data. This conclusion leads to some brief suggestions on directions for future work.

Suggested Citation
J. Berechman and K. A. Small (1988) Modeling Land Use and Transportation: An Interpretive Review for Growh Areas. Working Paper UCTC No. 1. Institute of Transportation Studies, UC Irvine: University of California Transportation Center. Available at: https://escholarship.org/uc/item/4nw2t7n5.

published journal article

Point queue models: A unified approach

Transportation Research Part B: Methodological

Publication Date

July 1, 2015

Author(s)

Suggested Citation
Wen-Long Jin (2015) “Point queue models: A unified approach”, Transportation Research Part B: Methodological, 77, pp. 1–16. Available at: 10.1016/j.trb.2015.02.015.

published journal article

Physiological and affective responses to green space virtual reality among pregnant women

Environmental Research

Publication Date

January 1, 2023

Author(s)

Yi Sun, Fu Li, Tao He, Yaohan Meng, Jie Yin, Ilona S. Yim, Lu Xu, Jun Wu

Abstract

Background Benefits of green spaces on stress reduction have been shown in previous studies. Most existing studies to date have focused on the general population. However, there is a lack of understanding of physiological mechanisms underlying the beneficial effects of green space among special populations, such as pregnant women. Objectives To examine physiological and affective responses to green space on stress recovery among pregnant women, using simulated green space exposure through virtual reality (VR). Methods We recruited 63 pregnant women between 8 and 14 weeks’ gestational age for a laboratory experiment. Participants were randomly assigned to view one of three, 5-min, VR videos of an urban scene with different green space levels (i.e., non-green, moderate, and high) after a laboratory stressor, the Trier Social Stress Test. Physiological stress responses were measured via changes in blood pressure, heart rate, skin conductance level, salivary alpha-amylase, and salivary cortisol. Affective response was measured using the Positive and Negative Affect Scale. Results We found that visual exposure to a green space environment in VR was associated with both physiological and affective stress reduction among pregnant women, including lower systolic blood pressure [-4.6 mmHg, 95% confidence interval (CI): −8.8, −0.4], reduced salivary alpha-amylase concentration (−1.2 ng/ml, 95% CI: −2.2, −0.2), improved overall positive affect (score: 6.6, 95% CI: 0.3, 13.0) and decreased negative affect of anxiety (score: −2.6, 95% CI: −5.19, −0.04) compared to non-green space environment. Exposure to high green space environment in park-like setting had the strongest impacts on stress recovery. Conclusion This study demonstrated that virtual green space exposure could effectively ease stress and improve mental health and well-being during pregnancy. Even a short immersion in VR-based green space environment may bring health benefits, which has significant implications for pregnant women when access to an actual nature may not be possible.

Suggested Citation
Yi Sun, Fu Li, Tao He, Yaohan Meng, Jie Yin, Ilona S. Yim, Liyan Xu and Jun Wu (2023) “Physiological and affective responses to green space virtual reality among pregnant women”, Environmental Research, 216, p. 114499. Available at: 10.1016/j.envres.2022.114499.

published journal article

Opportunistic UAV navigation with carrier phase measurements from asynchronous cellular signals

IEEE Transactions on Aerospace and Electronic Systems

Publication Date

August 1, 2020

Abstract

This article presents a framework for opportunistic unmanned aerial vehicle (UAV) navigation by exploiting carrier phase measurements from ambient cellular signals of opportunity. In the proposed framework, the cellular base transceiver stations (BTSs) are not assumed to be synchronous. A complete framework that employs an extended Kalman filter (EKF) is presented, including filter initialization and process and measurement noise covariance selection. The EKF estimates the position and velocity of the UAV, as well as the differences between the UAV-mounted receiver and each of the BTSs’ clock bias and clock drift. The observability of the estimation framework is analyzed, and the boundedness of the EKF’s errors is studied. It is shown that the system is observable given a class of vehicle and receiver clock dynamics. A lower bound for the EKF estimation error covariance is derived, and it is shown that the covariance remains bounded. Monte Carlo simulations are conducted to study the effect of the number of BTSs, the initial UAV speed, and the receiver’s oscillator quality, on the estimation performance. Two sets of experimental results are presented demonstrating UAVs navigating exclusively with cellular carrier phase measurements via the developed framework, achieving a total position root-mean-squared error of 2.94 and 5.99 m for UAV trajectories of 2.6 and 2.9 km, respectively.

Suggested Citation
Joe Khalife and Zaher M. Kassas (2020) “Opportunistic UAV navigation with carrier phase measurements from asynchronous cellular signals”, IEEE Transactions on Aerospace and Electronic Systems, 56(4), pp. 3285–3301. Available at: 10.1109/taes.2019.2948452.

conference paper

Toward alternative decentralized infrastructures

Proceedings of the 2015 annual symposium on computing for development - DEV '15

Publication Date

January 1, 2015

Author(s)

Bill Tomlinson, Bonnie Nardi, Donald J. Patterson, Ankita Raturi, Debra Richardson, Jean-Daniel Saphores, Dan Stokols
Suggested Citation
Bill Tomlinson, Bonnie Nardi, Donald J. Patterson, Ankita Raturi, Debra Richardson, Jean-Daniel Saphores and Dan Stokols (2015) “Toward alternative decentralized infrastructures”, in Proceedings of the 2015 annual symposium on computing for development - DEV '15. ACM Press, pp. 33–40. Available at: 10.1145/2830629.2830648.

published journal article

An intersection turning movement estimation procedure based on path flow estimator

Mathematical and Computer Modelling

Publication Date

November 1, 2010

Author(s)

Anthony Chen, Piya Chootinan, Seungkyu Ryu, Ming-Sheng Lee, Will Recker
Suggested Citation
Anthony Chen, Piya Chootinan, Seungkyu Ryu, Ming Lee and Will Recker (2010) “An intersection turning movement estimation procedure based on path flow estimator”, Mathematical and Computer Modelling, 46(2), pp. 161–176. Available at: 10.1002/atr.151.