conference paper
published journal article
published journal article
This paper uses an endogenous-growth model with overlapping generations to explore the connection between fiscal federalism and economic growth. The analysis shows that federalism, which allows public-good levels to be tailored to suit the differing demands of young and old consumers, who live in different jurisdictions, increases the incentive to save. This stronger incentive in turn leads to an increase in investment in human capital, and a byproduct of this higher investment is faster economic growth. (c) 2006 Elsevier B.V. All rights reserved.
conference paper
conference paper
other
A local computing device of a vehicle receives a stream of sensor data from one or sensors of the vehicle. If a remote computing device is estimated to process the stream of sensor data and provide driving instructions within a maximum acceptable wait time, then the local computing device sends a request to the remote computing device to process the stream of sensor data and provide driving instructions. If the processing is estimated to meet or exceed the maximum acceptable wait time, then the local computing device uses a locally executed neural network to determine driving instructions. The driving instructions received either from the remote computing or from the local neural network are sent to an autonomous driving system of the vehicle. Offloading processing the sensor data to the remote computing device may result in the local computing device consuming less energy.
Phd Dissertation
This dissertation is comprised of three chapters. Chapter 1 and 2 investigate the interactions between land-use patterns and household travel and vehicle-choice patterns, both empirically and theoretically. Chapter 3 explores institutional aspects of the housing and the rental markets in Korea. Chapter 1, which is coauthored with David Brownstone, estimates the influence of residential density on vehicle usage and fuel consumption. The empirical model accounts for both residential self-selection effects and non-random missing data problems. While most previous studies focus on a specific region, this paper uses national samples from the 2001 National Household Travel Survey. The estimation results indicate that the joint effect of the contextual density measure (density in the context of its surrounding area) and residential density on vehicle usage is quantitatively larger than the sole effect of residential density. We also find that a lower neighborhood residential density induces consumer choices toward less fuel-efficient vehicles, which confirms the finding in Brownstone and Golob (2009). Motivated by a finding in Chapter 1 of this dissertation, Chapter 2 presents a modified monocentric city model, which incorporates the consumer’s optimal vehicle-type choice problem. Consumers are assumed to explicitly consider driving inconvenience in the choice of vehicle sizes, and the resulting commuting cost is a function of residential density. This vehicle-type choice problem is embedded in an otherwise standard monocentric city model. Comparative static analyses suggest that an increase in commuting cost per mile, especially from increased unit cost of driving inconvenience, may induce spatial expansion of the city. Part of comparative static analysis shows how the city’s vehicle fuel efficiency depends on the city characteristics such as population and agricultural rent. Chapter 3 explores a unique kind of rental contract to Korea, called chonsei. The tenant pays an upfront deposit, typically from 40% to 70% of the property value, to the landlord, and the landlord repays the deposit to the tenant upon contract termination. The main goal of this paper is to show why such a unique rental contract exists and has been popular in Korea. The model shows that chonsei is an ingenious market response in the era of “financial repression” in Korea (Renaud (1989)), allowing landlords to accumulate sufficient funds for housing investment without major reliance on a mortgage and providing renters with cheap rental housing. The model implies that the chonsei renter may save while the landlord and the owner-occupier put all their assets into housing and thus have no financial savings, the hypothesis that is empirically tested and confirmed
Phd Dissertation
The growth of urban vehicle traffic generates serious transportation and environmental problems in most countries of the world. Intelligent transportation systems (ITS) are effective means to solve basic traffic problems, such as driving safety, road congestion, disaster supplies, emissions, etc. Inter-vehicle communication (IVC) system is one of the most important components of ITS. In recent years, the rapid development of information technologies leads a revolution in IVC, enabling IVC be a powerful multifunctional system. However, there exist numerous challenges for ITS studies. This dissertation is aimed to address three urgent and critical issues in IVC: efficiency of information exchanging among connected vehicles, simulation methods, and IVC applications. Information transmission efficiency, which can be measured by communication throughput or capacity, is a fundamental property of vehicular ad hoc networks. This dissertation theoretically analyzes communication throughputs, including broadcast and unicast communications, under discrete and continuous vehicular ad hoc networks (VANETs). We also examine influence of transmission range, interference ratio, market penetration rate of IVC-equipped vehicles, percentage of senders, and traffic waves on throughputs. Furthermore, we derive a theoretical formulation to calculate communication capacities under uniform traffic streams. And, an integer programming (IP) model is improved to explore capacities in general traffic, and a genetic algorithm is constructed to search the solutions efficiently. The second contribution of this dissertation is the development of a hybrid traffic simulation model to evaluate transportation systems incorporated with IVC technologies. As IVC-equipped vehicles are able to obtain more road information and they are controlled to pursue some objectives, they will behave differently from others, and transportation systems will become heterogeneous. This dissertation presents a hybrid traffic simulation model coupling microscopic and macroscopic models to address heterogeneity in transportation systems. In the model, equipped vehicles are regulated by a car-following model, while the other vehicles are described as continuous media with the Lighthill-Whitham-Richard (LWR) model. We analytically study the model on a single-lane road using a modified Godunov method. The hybrid model shows its potential of accurate wave propagation from individual vehicles to continuous traffic streams, and reversely; i.e., the model is capable of analyzing heterogeneous traffic. Moreover, consistency, stability and convergence of the hybrid model are carefully investigated. The model also shows the advancement of computational efficiency and control flexibility on traffic simulations. Finally, for IVC applications in environment, we propose a green driving strategy to smooth traffic flow and lower pollutant emissions and fuel consumption. In this dissertation, we study constant and dynamic green driving strategies based on inter-vehicle communications. Generally, speed limit control in successful strategies guarantee a vehicle’s speed profile be smooth while still following its leader during a relative long time period. A theoretical analysis of constant strategies demonstrates that optimal smoothing effects can be achieved when a speed limit is set to be close to but not smaller than average speed of traffic. We consider a dynamic strategy in which controlled vehicles share location and speed information based on a feedback control system. The influence of market penetration rate of equipped vehicles and communication delay on the strategy is also analyzed. Besides the development of the green driving strategy, we construct a green driving APP for smartphones on the Google Android platform and design a field experiment to check the feasibility of the strategy. The results are promising and support the advancements of IVC on reducing emissions and fuel consumption.
published journal article
Using the conceptual framework of time-space geography, this paper incorporates both spatio-temporal constraints and household interaction effects into a meaningful measure of the potential of a household to interact with the built environment. Within this context, personal accessibility is described as a measure of the potential ability of individuals within a household not only to reach activity opportunities, but to do so with sufficient time available for participation in those activities, subject to the spatio-temporal constraints imposed by their daily obligations and transportation supply environment. The incorporation of activity-based concepts in the measurement of accessibility as a product of travel time savings not only explicitly acknowledges a temporal dimension in assessing the potential for spatial interaction but also expands the applicability of accessibility consideration to such real-world policy options as the promotion of ride-sharing and trip chaining behaviors. An empirical application of the model system provides an indication of the potential of activity-based modeling approaches to assess the bounds on achievable improvements in accessibility and travel time based on daily household activity patterns. It also provides an assessment of roles for trip chaining and ride-sharing as potentially effective methods to facilitate transportation policy objectives. (C) 2001 Elsevier Science Ltd. All rights reserved.
research report
This report describes the results of PATH Task Order 5324—the first year of a multi-year project to integrate the Cartesius incident management system with Cal-trans CTNET traffic signal management system. The results of this research are a set of software requirements for reimplementing the Cartesius to interoperate with CTNET. An analysis of the existing Cartesius prototype explains how the need to focus the system on deployment and technical shortcomings of the existing system justifies a reimplementation of the software. From here, we describe the problem to be solved by the new software implementation, including general use cases, the expected users, the systems that Cartesius will interoperate with, and the constraints that will be placed on the system. The problem statement is followed by a detailed discussion of the functional requirements, database requirements, the user interface requirements, and other external interface requirements. The report concludes with a discussion the reimplementation work to be completed under PATHTask Order 6324. This reimplementation will serve the more general purpose of making Cartesius capable of working with existing traffic management subsystems to provide multi-jurisdictional incident mitigation, thus improving its deployability and subsequent value for Caltrans.
research report |
May 2010