published journal article

Interlaminar Fracture Toughness of CFRP Laminates Incorporating Multi-Walled Carbon Nanotubes

Polymers

Publication Date

June 1, 2015

Author(s)

Elisa Borowski, Eslam Soliman, Usama F. Kandil, Mahmoud Reda Taha

Abstract

Carbon fiber reinforced polymer (CFRP) laminates exhibit limited fracture toughness due to characteristic interlaminar fiber-matrix cracking and delamination. In this article, we demonstrate that the fracture toughness of CFRP laminates can be improved by the addition of multi-walled carbon nanotubes (MWCNTs). Experimental investigations and numerical modeling were performed to determine the effects of using MWCNTs in CFRP laminates. The CFRP specimens were produced using an epoxy nanocomposite matrix reinforced with carboxyl functionalized multi-walled carbon nanotubes (COOH–MWCNTs). Four MWCNTs contents of 0.0%, 0.5%, 1.0%, and 1.5% per weight of the epoxy resin/hardener mixture were examined. Double cantilever beam (DCB) tests were performed to determine the mode I interlaminar fracture toughness of the unidirectional CFRP composites. This composite material property was quantified using the critical energy release rate, GIC. The experimental results show a 25%, 20%, and 17% increase in the maximum interlaminar fracture toughness of the CFRP composites with the addition of 0.5, 1.0, and 1.5 wt% MWCNTs, respectively. Microstructural investigations using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) verify that chemical reactions took place between the COOH–MWCNTs and the epoxy resin, supporting the improvements experimentally observed in the interlaminar fracture toughness of the CFRP specimens containing MWCNTs. Finite element (FE) simulations show good agreement with the experimental results and confirm the significant effect of MWCNTs on the interlaminar fracture toughness of CFRP.

Suggested Citation
Elisa Borowski, Eslam Soliman, Usama F. Kandil and Mahmoud Reda Taha (2015) “Interlaminar Fracture Toughness of CFRP Laminates Incorporating Multi-Walled Carbon Nanotubes”, Polymers, 7(6), pp. 1020–1045. Available at: 10.3390/polym7061020.

book/book chapter

Attitude-Behaviour Relationships in Travel-Demand Modelling

Publication Date

January 1, 1979

Author(s)

Thomas Golob, Abraham D. Horowitz, Martin Wachs
Suggested Citation
Thomas F Golob, Abraham D. Horowitz and Martin Wachs (1979) “Attitude-Behaviour Relationships in Travel-Demand Modelling”, in Behavioural Travel Modelling. 1st ed. Routledge, p. 19. Available at: https://www.taylorfrancis.com/chapters/edit/10.4324/9781003156055-44/attitude-behaviour-relationships-travel-demand-modelling-thomas-golob-abraham-horowitz-martin-wachs.

published journal article

Travel demand of an elderly population: An attitudinal model and some comparisons

Transportation Research Forum

Publication Date

January 1, 1977

Author(s)

Will Recker, P. H. Edelstein
Suggested Citation
W. W. Recker and P. H. Edelstein (1977) “Travel demand of an elderly population: An attitudinal model and some comparisons”, Transportation Research Forum, 18(1).

published journal article

Integrating resident digital sketch maps with expert knowledge to assess spatial knowledge of flood risk: A case study of participatory mapping in Newport Beach, California

Applied Geography

Publication Date

September 1, 2016

Author(s)

Wing Cheung, Doug Houston, Jochen E. Schubert, Victoria Basolo, David Feldman, Richard Matthew, Brett F. Sanders, Beth Karlin, Kristen A. Goodrich, Seth Contreras, Adam Luke
Suggested Citation
Wing Cheung, Douglas Houston, Jochen E. Schubert, Victoria Basolo, David Feldman, Richard Matthew, Brett F. Sanders, Beth Karlin, Kristen A. Goodrich, Santina L. Contreras and Adam Luke (2016) “Integrating resident digital sketch maps with expert knowledge to assess spatial knowledge of flood risk: A case study of participatory mapping in Newport Beach, California”, Applied Geography, 74, pp. 56–64. Available at: 10.1016/j.apgeog.2016.07.006.

research report

Changes in transit use and service and associated changes in driving near a new light rail transit line

Publication Date

May 1, 2015

Abstract

Los Angeles is pursuing an ambitious rail transit investment program with plans to open six new lines by 2019. This report provides policy makes and planners a better understanding of the potential impacts of Los Angeles Metroâ??s rail transit investment program by assessing the changes in transit use of nearby residents and nearby bus service associated with the Expo Line, the first of the six new lines. The findings indicate that changes in bus service that are coincident with the introduction of new light rail transit can negatively affect the overall transit ridership in the corridor. In addition, households living near new Expo Line light rail stations reduced their vehicle miles traveled (VMT), but those households living near bus stops that were eliminated as part of the service change increased their VMT.

Suggested Citation
Hilary Nixon, Marlon Boarnet, Doug Houston, Steven Spears and Jeongwoo Lee (2015) Changes in transit use and service and associated changes in driving near a new light rail transit line, p. 63p.

published journal article

An exploratory analysis of alternative travel behaviors of ride-hailing users

Transportation

Abstract

The emergence of ride-hailing, technology-enabled on-demand services such as Uber and Lyft, has arguably impacted the daily travel behavior of users. This study analyzes the travel behavior of ride-hailing users first from conventional person- and trip-based perspectives and then from an activity-based approach that uses tours and activity patterns as basic units of analysis. While tours by definition are more easily identified and classified, daily patterns theoretically better represent overall travel behavior but are simultaneously more difficult to explain. We thus consider basic descriptive analyses for tours and a more elaborate approach, Latent Class Analysis, to describe pattern behavior. The empirical results for tours using data from the 2017 National Household Travel Survey show that 76% of ride-hailing tours can be represented by five dominant tour types with non-work tours being the most frequent. The Latent Class model suggests that the ride-hailing users can be divided into four distinct classes, each with a representative activity-travel pattern defining ride-hailing usage. Class 1 was composed of younger, employed people who used ride-hailing to commute to work. Single, older individuals comprised Class 2 and used ride-hailing for midday maintenance activities. Class 3 represented younger, employed individuals who used ride-hailing for discretionary purposes in the evening. Last, Class 4 members used ride-hailing for mode change purposes. Since each identified class has different activity-travel patterns, they will show different responses to policy directives. The results can assist ride-hailing operators in addressing evolving travel needs as users respond to various policy constraints.

Suggested Citation
Rezwana Rafiq and Michael G. McNally (2023) “An exploratory analysis of alternative travel behaviors of ride-hailing users”, Transportation, 50(2), pp. 571–605. Available at: 10.1007/s11116-021-10254-9.

working paper

Endogenous Trip Scheduling: The Henderson Approach Reformulated and Compared with the Vickrey Approach

Publication Date

April 1, 1993

Associated Project

Author(s)

Working Paper

No. 199

Areas of Expertise

Abstract

Two approaches to modeling peak-period congestion that account for travelers’ scheduling behavior have made their way into the economics literature. On the demand side of both approaches, travelers trade off a cost of travel delay against a cost of being early or late at destination in scheduling their trip. On the supply side, the Vickrey approach uses a queuing-congestion technology; the Henderson approach uses a flow-congestion technology, assuming that the travel time for any traveler is determined by the departure flow he departs with at origin. But the Henderson approach is found to have problems. This paper illustrates these problems; shows that they can be eliminated by assuming that the travel time for any traveler is determined by the arrival flow he arrives with at destination; and compares the behavior of the Vickrey and reformulated Henderson approaches both analytically and using simulations. The paper finds that the behavior of the reformulated Henderson approach varies with its elasticity of travel delay with respect to traffic flow, while the Vickrey approach lacks such a flexibility; and that the behavior of the Vickrey approach is the limit of that of the reformulated Henderson approach as the elasticity of travel delay goes to infinity.

Suggested Citation
Xeuhao Chu (1993) Endogenous Trip Scheduling: The Henderson Approach Reformulated and Compared with the Vickrey Approach. Working Paper No. 199. Institute of Transportation Studies, UC Irvine: University of California Transportation Center. Available at: https://escholarship.org/uc/item/93g0v0p8.

working paper

Clean or a Day: Troubles with California's Smog Check

Publication Date

August 1, 1993

Associated Project

Author(s)

Amihai Glazer, Daniel Klein, Charles Lave

Working Paper

UCI-ITS-WP-93-6, UCTC 163

Areas of Expertise

Abstract

We have carefully reviewed “Evaluation of the California Smog Check Program and Recommendations for Program Improvements: Fourth Report to the Legislature.” Overall, we find it a thorough and competent presentation of the basic facts, though we disagree with the conclusions. Our major concern is one of perspective. It appears that the authors of the report are simply too close to the issue, too enmeshed in the details of implementation. We think it worthwhile to step back from the technical issues to take an overall view of the inspection and maintenance (I/M) program for reducing auto emissions.

Suggested Citation
Amihai Glazer, Daniel Klein and Charles Lave (1993) Clean or a Day: Troubles with California's Smog Check. Working Paper UCI-ITS-WP-93-6, UCTC 163. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/8vm1s03r.

research report

Prototype design and evaluation of hybrid solid oxide fuel cell gas turbine systems for use in locomotives

Publication Date

October 1, 2019

Author(s)

Ali Azizi, Philipp Ahrend, Scott Samuelsen, Jack Brouwer

Abstract

Hybrid solid oxide fuel cell-gas turbine (SOFC-GT) systems are among the most efficient and lowest emitting power generation systems conceived for use in locomotives. Their superiority was proven in stationary power applications with near-zero (natural gas operation) to zero (hydrogen operation) pollutant emissions. However, the feasibility and dynamic operation of these systems for use in locomotives has not been extensively investigated. In this report, a new system based on existing National Fuel Cell Research Center (NFCRC) control methods was developed by NFCRC at the University of California, Irvine (UCI) for these types of systems. These control strategies enable the hybrid SOFC-GT system for locomotive engines to follow dynamic power demands while keeping all of the components and system operating variables within acceptable limits of performance under fuel utilizations between 75 and 80 percent. A detailed economic analysis of potential SOFC-GT locomotive production and operation costs in comparison to other low pollutant emitting alternatives (e.g., diesel-electric, battery electric, catenary-electric) was accomplished. The economic analyses show that SOFC-GT systems are likely to cost more and lead to higher costs for delivering goods per ton-mile than the diesel-electric alternative which has higher emissions. SOFC-GT locomotives are likely to produce lower operating costs compared to the catenary-electric alternative, and significantly lower operating costs compared to the battery-electric alternative.

Suggested Citation
Ali Azizi, Philipp Ahrend, G. Scott Samuelsen and Jack Brouwer (2019) Prototype design and evaluation of hybrid solid oxide fuel cell gas turbine systems for use in locomotives, p. 124p.