published journal article
published journal article
published journal article
published journal article
The potential of system-wide implementation of delayed deceleration approaches is presented through modeling a day of operations. Conventional approach procedures may involve early deceleration in the flight trajectory, resulting in early high-lift device deployment. Alternatively, delayed deceleration approaches involve delaying high-lift device deployment, thus maintaining higher airspeeds for longer and lowering thrust requirements, which reduces fuel burn and community noise. When implementing delayed deceleration approach procedures within traffic, the primary challenge is accrued from the variability of deceleration rates, which can significantly impact approach timing and thus separation among aircraft. In this work, a framework was developed that constructs delayed deceleration approach models based on observed radar data. This framework was then implemented on an average day at Boston Logan Airport to assess the feasibility of implementing delayed deceleration approaches on commercial traffic. The results indicate that delayed deceleration approaches can be implemented for 92.2% of the evaluated traffic without separation concerns, providing an average approach fuel burn savings of 10.27% and reducing exposure of configuration noise along the flight path by an average of 8.10 N miles of ground track distance. Therefore, implementing the delayed deceleration approach on a commercial traffic may provide environmental benefits.
published journal article
Public sector involvement in research is examined, with emphasis on the creation of incentives by government. In transportation, government investment in research is often a spark for improvements in overall economic productivity. This connection has been dubbed “the Virtuous Circle” and helps justify basic and applied research. Is research always justifiable from a societal perspective? The answer to this question is best approached with the application of cost-benefit analysis, or more specifically net present value (NPV). While NPV appears to be simple calculation yielding transparent solutions, a proper cost-benefit analysis requires careful construction of a base case as well as decisions on discount rates and indirect impacts. Sensitivity analysis is used to check the validity of the chosen assumptions. A case study of new, high speed rail technology illustrates how some of the concepts can be applied.
conference paper
conference paper
conference paper
Autonomous Driving (AD) is a rapidly developing technology and its security issues have been studied by various recent research works. With the growing interest and investment in leveraging intelligent infrastructure support for practical AD, AD system may have new opportunities to defend against existing AD attacks. In this paper, we are the first to systematically explore such a new AD security design space leveraging emerging infrastructure-side support, which we call Infrastructure-Aided Autonomous Driving Defense (I-A2D2). We first taxonomize existing AD attacks based on infrastructure-side capabilities, and then analyze potential I-A2D2 design opportunities and requirements. We further discuss the potential design challenges for these I-A2D2 design directions to be effective in practice.
published journal article
published journal article
This paper estimates the effect of building-height limits on the spatial sizes of Indian cities. Regression results show that height limits, which are imposed in draconian fashion in India, cause spatial expansion of its cities, as predicted by the theoretical model of Bertaud and Brueckner (2005). The regression coefficients, by yielding the implied reduction in the area of an average city from a marginal increase in its height limit, allow computation of the annual saving in commuting cost for the city’s edge household when the limit is relaxed. This cost saving, which is an exact measure of the common welfare gain for each urban household, can be scaled up to yield the aggregate consumer gain in a typical city from relaxation of India’s restrictive height limits. For a moderate height-limit increase, this gain equals 106 million rupees. (C) 2012 Elsevier B.V. All rights reserved.