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Search Results: 1 - 10 of 211253 matches for " Stephen P. Mattingly "
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Statistical Model for Estimating Carbon Dioxide Emissions from a Light-Duty Gasoline Vehicle  [PDF]
Benjamin Afotey, Melanie Sattler, Stephen P. Mattingly, Victoria C. P. Chen
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.48A1002

The objective of this research was development of a statistical model for estimating vehicle tailpipe emissions of carbon dioxide (CO2). Forty hours of second-by-second emissions data (144,000 data points) were collected using an On-Board emissions measurement System (Horiba OBS-1300) installed in a 2007 Dodge Charger car. Data were collected for two roadway types, arterial and highway, around Arlington, Texas, and two different time periods, off peak and peak (both a.m. and p.m.). Multiple linear regression and SAS software were used to build emission models from the data, using predictor variables of velocity, acceleration and an interaction term. The arterial model explained 61% of the variability in the emissions; the highway model explained 27%. The arterial model in particular represents a reasonably good compromise between accuracy and ease of use. The arterial model could be coupled with velocity and acceleration profiles obtained from a micro-scale traffic simulation model, such as CORSIM, or from field data from an instrumented vehicle, to estimate percent emission reductions associated with local changes in traffic system operation or management.

A New Paradigm in User Equilibrium-Application in Managed Lane Pricing
Asapol Sinprasertkool, Siamak Ardekani, Stephen P. Mattingly
International Journal of Engineering , 2011,
Abstract: Ineffective use of the High-Occupancy-Vehicle (HOV) lanes has the potential to decrease theoverall roadway throughput during peak periods. Excess capacity in HOV lanes during peakperiods can be made available to other types of vehicles, including single occupancy vehicles(SOV) for a price (toll). Such dual use lanes are known as “Managed Lanes.” The main purposeof this research is to propose a new paradigm in user equilibrium to predict the travel demand fordetermining the optimal fare policy for managed lane facilities. Depending on their value of time,motorists may choose to travel on Managed Lanes (ML) or General Purpose Lanes (GPL). In thisstudy, the features in the software called Toll Pricing Modeler version 4.3 (TPM-4.3) aredescribed. TPM-4.3 is developed based on this new user equilibrium concept and utilizes it toexamine various operating scenarios. The software has two built-in operating objective options: 1)what would the ML operating speed be for a specified SOV toll, or 2) what should the SOV toll befor a desired minimum ML operating speed.A number of pricing policy scenarios are developed and examined on the proposed managedlane segment on Interstate 30 (I-30) in Grand Prairie, Texas. The software provides quantitativeestimates of various factors including toll revenue, emissions and system performance such asperson movement and traffic speed on managed and general purpose lanes. Overall, among thescenarios examined, higher toll rates tend to generate higher toll revenues, reduce overall COand NOx emissions, and shift demand to general purpose lanes. On the other hand, HOVpreferential treatments at any given toll level tend to reduce toll revenue, have no impact on orreduce system performance on managed lanes, and increase CO and NOx emissions.
Rare Transition Events in Nonequilibrium Systems with State-Dependent Noise: Application to Stochastic Current Switching in Semiconductor Superlattices
Matthias Heymann,Stephen W. Teitsworth,Jonathan C. Mattingly
Mathematics , 2010,
Abstract: Using recent mathematical advances, a geometric approach to rare noise-driven transition events in nonequilibrium systems is given, and an algorithm for computing the maximum likelihood transition curve is generalized to the case of state-dependent noise. It is applied to a model of electronic transport in semiconductor superlattices to investigate transitions between metastable electric field distributions. When the applied voltage $V$ is varied near a saddle-node bifurcation at $V_th$, the mean life time $$ of the initial metastable state is shown to scale like $log \propto |V_th - V|^{3/2}$ as $V\to V_th$.
Optimization of R(e+e-) and "Freezing" of the QCD Couplant at Low Energies
A. C. Mattingly,P. M. Stevenson
Physics , 1993, DOI: 10.1103/PhysRevD.49.437
Abstract: The new result for the third-order QCD corrections to R_{e^+e^-}, unlike the old, incorrect result, is nicely compatible with the principle-of-minimal-sensitivity optimization method. Moreover, it leads to infrared fixed-point behaviour: the optimized couplant, alpha_s/pi, for R(e+e-) does not diverge at low energies, but "freezes" to a value 0.26 below about 300 MeV. This provides some direct theoretical evidence, purely from perturbation theory, for the "freezing" of the couplant -- an idea that has long been a popular and successful phenomenological hypothesis. We use the "smearing" method of Poggio, Quinn, and Weinberg to compare the resulting theoretical prediction for R(e+e-) with experimental data down to the lowest energies, and find excellent agreement.
QCD Perturbation Theory at Low Energies
A. C. Mattingly,P. M. Stevenson
Physics , 1992, DOI: 10.1103/PhysRevLett.69.1320
Abstract: We apply the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of $\R$. The effective couplant remains finite, freezing to a value $\alpha_s/\pi = 0.26$ at low energies. Using Poggio-Quinn-Weinberg smearing we find good agreement between theory and experiment right down to zero energy.
Applying Optimized Perturbation Theory to QCD at Low Energies
A. C. Mattingly,P. M. Stevenson
Physics , 1992,
Abstract: We discuss the use of the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of {\mbox{${R_{e^+e^-}}$}}. The effective coupling constant remains finite allowing us to apply the Poggio-Quinn-Weinberg smearing method down to energies below 1 GeV, where we find good agreement between theory and experiment. The couplant freezes to a value of $\alpha_s/\pi = 0.26$ at zero energy which is in remarkable concordance with values obtained phenomenologically.
A practical criterion for positivity of transition densities
David P. Herzog,Jonathan C. Mattingly
Mathematics , 2014,
Abstract: We establish a simple criterion for locating points where the transition density of a degenerate diffusion is strictly positive. Throughout, we assume that the diffusion satisfies a stochastic differential equation (SDE) on $\mathbf{R}^d$ with additive noise and polynomial drift. In this setting, we will see that it is often that case that local information of the flow, e.g. the Lie algebra generated by the vector fields defining the SDE at a point $x\in \mathbf{R}^d$, determines where the transition density is strictly positive. This is surprising in that positivity is a more global property of the diffusion. This work primarily builds on and combines the ideas of Ben Arous and L\'eandre (1991) and Jurdjevic and Kupka (1981, 1985).
Noise-Induced Stabilization of Planar Flows I
David P. Herzog,Jonathan C. Mattingly
Mathematics , 2014,
Abstract: We show that the complex-valued ODE \begin{equation*} \dot z_t = a_{n+1} z^{n+1} + a_n z^n+\cdots+a_0, \end{equation*} which necessarily has trajectories along which the dynamics blows up in finite time, can be stabilized by the addition of an arbitrarily small elliptic, additive Brownian stochastic term. We also show that the stochastic perturbation has a unique invariant measure which is heavy-tailed yet is uniformly, exponentially attracting. The methods turn on the construction of Lyapunov functions. The techniques used in the construction are general and can likely be used in other settings where a Lyapunov function is needed. This is a two-part paper. This paper, Part I, focuses on general Lyapunov methods as applied to a special, simplified version of the problem. Part II of this paper extends the main results to the general setting.
Noise-Induced Stabilization of Planar Flows II
David P. Herzog,Jonathan C. Mattingly
Mathematics , 2014,
Abstract: We continue the work started in Part I of this article, showing how the addition of noise can stabilize an otherwise unstable system. The analysis makes use of nearly optimal Lyapunov functions. In this continuation, we remove the main limiting assumption of Part I by an inductive procedure as well as establish a lower bound which shows that our construction is radially sharp. We also prove a version of Peskir's \cite{Peskir_07} generalized Tanaka formula adapted to patching together Lyapunov functions. This greatly simplifies the analysis used in previous works.
Modern Tests of Lorentz Invariance
Mattingly David
Living Reviews in Relativity , 2005,
Abstract: Motivated by ideas about quantum gravity, a tremendous amount of effort over the past decade has gone into testing Lorentz invariance in various regimes. This review summarizes both the theoretical frameworks for tests of Lorentz invariance and experimental advances that have made new high precision tests possible. The current constraints on Lorentz violating effects from both terrestrial experiments and astrophysical observations are presented.
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