Policy

Quantified Traveler: Travel Feedback Meets the Cloud to Change Behavior

Sengupta, Raja
Walker, Joan L.
2015

Halting climate change will require a concerted effort to reduce emissions from on-road vehicles. While significant progress has been made to improve vehicle efficiency and reduce CO 2 emissions, surface transportation accounted for half the increase in US green-house gas (GHG) emissions over the past two decades. Today, surface transportation accounts for 24 percent of all US emissions. Automobile improvements alone will not be sufficient to meet federal and state emissions targets; policy makers also need to identify solutions that reduce the demand for car travel. Information technology...

Real-time Estimation of a Markov Process Over a Noisy Digital Communication Channel

Xu, Qing
Sengupta, Raja
2011

We study the real-time estimation of a Markov process over a memoryless noisy digital communication channel. The goal of system design is to minimize the mean squared estimation error. We first show the optimal encoder and decoder can be memoryless in terms of the source symbols. We then prove the optimal encoder separates the real space with hyperplanes. In the case of the binary symmetric channel and scalar source, the optimal encoder can be a threshold. A recursive algorithm is given to jointly find a locally optimal encoder and decoder for the binary symmetric channel. For a memoryless...

Scaling Laws for Cooperative Node Localization in Non-Line-of-Sight Wireless Networks

Ekambaram, Venkatesan
Ramchandran, Kannan
Sengupta, Raja
2011

We study the problem of cooperative node localization in non-line- of-sight (NLOS) wireless networks and address design questions such as, "How many anchors and what fraction of line-of-sight (LOS) measurements are needed to achieve a specified target accuracy?". We analytically characterize the performance improvement in localization accuracy as a function of the number of nodes in the network and the fraction of LOS measurements. In particular, we show that the Cramer- Rao Lower Bound (CRLB) can be expressed as a product of two factors - a scalar function that depends only on the...

Stability Bounds on Entropy Rate for Real-Time Tracking an Unstable LTI Process Over a Multi-Access Network

Huang, Ching-Ling
Sengupta, Raja
2009

We assume the separation of source/channel coding and propose a framework for real-time tracking an unstable, scalar, linear time-invariant (LTI) process via a G/G/1- queueing network. We derive a stability bound on the entropy rate of an unstable LTI process such that tracking error can stay bounded for specified moment. This bound is a function of the moment to be stabilized, encoder efficiency, quantization accuracy, and network parameters. This bound is sufficient under all load conditions and tight when the network is heavily utilized. Proposed framework covers a broad class of...

Stability of Dynamic Traveling Repairman Problem Under Polling-Sequencing Policies

Huang, Jiangchuan
Sengupta, Raja
2013

We establish a necessary and sufficient condition for stability in the dynamic traveling repairman problem (DTRP) [3] under the class of polling-sequencing (P-S) policies satisfying unlimited-polling and economy of scale. The P-S class includes some of the policies proven to be optimal for the expectation of system time under light and heavy loads in the DTRP literature. The number of tasks inside each polling partition is shown to be a Markov chain. Policies such as first come first serve, traveling salesman policy, nearest neighbor and Daganzo's algorithm are shown to have economy of...

System Time Distribution of Dynamic Traveling Repairman Problem Under the PART-n-TSP Policy

Huang, Jiangchuan
Sengupta, Raja
2015

We propose the PART-n-TSP policy for the Dynamic Traveling Repairman Problem [1]. We compute a good approximation for the distribution of the system time, defined as the elapsed time between the arrival and the completion of each task. PART-n-TSP stabilizes the system for every load in [0; 1). PART-n-TSP has lower system time variance than PARTTSP [14] and Nearest Neighbor [1] when the load is neither too small or too large. We show that PART-n-TSP is also optimal for system time expectation under light and heavy loads.

WTRP - Wireless Token Ring Protocol

Ergen, M.
Lee, Duke
Sengupta, Raja
Varaiya, P.
2004

The wireless token ring protocol (WTRP) is a novel medium access control (MAC) protocol for wireless local area networks (WLANs). In contrast with IEEE 802.11 networks, WTRP guarantees quality of service (QoS) in terms of bounded latency and reserved bandwidth, which are critical in many real-time applications. Compared to 802.11, WTRP improves efficiency by reducing the number of retransmissions due to collisions, and it is more fair as all stations use the channel for the same amount of time. Stations take turns transmitting and give up the right to transmit after a specified amount of...

National Algorithms for Determining Stocking Class, Stand Size Class, and Forest Type for Forest Inventory and Analysis Plots

Arner, Stanford L
Woudenberg, Sharon
Waters, Shirley
Vissage, John
MacLean, MacLean
Thompson, Mike
Hansen, Mark
2001

Procedures to assign stocking values to individual trees, and forest type, stand size, and stocking class to all Forest Inventory and Analysis plots nationwide are presented. The stocking values are assigned using species specific functions of diameter developed from normal yield tables and stocking charts. These algorithms will be included as part of the set of standardized procedures being developed by Forest Inventory and Analysis that will result in consistent estimates without regard to political boundaries.

Safe At Home? An Experiment in Domestic Airline Security

Barnett, Arnold
Shumsky, Robert
Hansen, Mark
Odoni, Amedeo
Gosling, Geoffrey
2001

The paper describes a scientific experiment about a contentious policy issue: What costs and disruptions might arise if U.S. domestic airlines adopted positive passenger bag-match (PPBM), an antiterrorist measure aimed at preventing baggage unaccompanied by passengers from traveling in aircraft luggage compartments? The heart of the effort was a two-week live test of domestic bag-match that involved 11 airlines, 8,000 flights, and nearly 750,000 passengers. Working with the Federal Aviation Administration, the authors played a major role in designing, monitoring, and analyzing the live...

Unintended Environmental Impacts of Nighttime Freight Logistics Activities

Sathaye, Nakul
Harley, Robert
Madanat, Samer
2009

In recent years, the reduction of freight vehicle trips during peak hours has been a common policy goal. To this end, policies have been implemented to shift logistics operations to nighttime hours. The purpose of such policies has generally been to mitigate congestion and environmental impacts. However, the atmospheric boundary layer is generally more stable during the night than the day. Consequently, shifting logistics operations to the night may increase 24‐hour average concentrations of diesel exhaust pollutants in many locations. This paper presents realistic scenarios for two...