Higher-order CFD and Interface Tracking Methods on Highly-Parallel MPI and GPU systems

A computational investigation of the effects on parallel performance of higher-order accurate schemes was carried out on two different computational systems: a traditional CPU based MPI cluster and a system of four Graphics Processing Units (GPUs) controlled by a single quad-core CPU. The investigation was based on the solution of the level set equations for interface tracking using a High-Order Upstream Central (HOUC) scheme. Different variants of the HOUC scheme were employed together with a 3rd-order TVD Runge-Kutta time integration. An increase in performance of two orders of magnitude was seen when comparing a single CPU core to a single GPU with a greater increase at higher orders of accuracy and at lower precision

Building Consensus and Partnerships for Implementing the MAP-21 Section 5310 Program in California, MTI Report WP 12-25

The Moving Ahead for Progress in the 21st Century Act (MAP-21)—the legislation that currently provides funding for federal transportation—allows metropolitan planning organizations (MPOs) or eligible large, urbanized area (UZA) agencies to assume administrative responsibility for Federal Transit Administration (FTA) Section 5310—the Enhanced Mobility of Seniors and Individuals with Disabilities grant program. Caltrans engaged Mineta Transportation Institute (MTI) to conduct research and facilitate a dialogue with the State’s 5310 stakeholders. The MTI team conducted interviews with key stakeholders and Caltrans staff and performed in-depth quantitative analysis of the existing administrative activities of the 5310 program. This research was followed by two statewide 5310 program workshops led by Drs. Ferrell and Appleyard to facilitate discussion among stakeholders and reach consensus on how the new MAP-21 program would be implemented. The key findings from this research and dialogue are: A “full transition” to MPO Program administration could significantly reduce the benefits of the 5310 program for the entire state. A full transition could leave smaller MPOs lacking sufficient administrative funds to adequately run the program in their jurisdictions. Stakeholders are concerned that their local project funding priorities may not receive enough attention if Caltrans retains sole administrative responsibilities for the program. A majority of stakeholders prefer to pursue a partnership with Caltrans to jointly run the 5310 program (the “Hybrid/Partnership Option”). The Hybrid/Partnership Option can provide the maximum amount of flexibility for the program over the long term while building the administrative capacities of all partners

Improving Livability Using Green and Active Modes: A Traffic Stress Level Analysis of Transit, Bicycle, and Pedestrian Access and Mobility

Understanding the relative attractiveness of alternatives to driving is vitally important toward lowering driving rates and, by extension, vehicle miles traveled (VMT), traffic congestion, greenhouse gas (GHG) emissions, etc. The relative effectiveness of automobile alternatives (i.e., buses, bicycling, and walking) depends on how well streets are designed to work for these respective modes in terms of safety, comfort and cost, which can sometimes pit their relative effectiveness against each other. In this report, the level of traffic stress (LTS) criteria previously developed by two of the authors was used to determine how the streets functioned for these auto alternative modes. The quality and extent of the transit service area was measured using a total travel time metric over the LTS network. The model developed in this study was applied to two transit routes in Oakland, California, and Denver, Colorado

Neighborhood Crime and Transit Station Access Mode choice - Phase III of Neighborhood Crime and Travel Behavior

This report provides the findings from the third phase of a three-part study about the influences of neighborhood crimes on travel mode choice. While previous phases found evidence that high levels of neighborhood crime discourage people from choosing to walk, bicycle and ride transit, consistent with the authors’ hypothesis, they also produced counterintuitive findings suggesting that in some cases, high crime neighborhoods encourage transit ridership at the expense of driving—the opposite of what common sense would suggest. Phase 3 tested possible explanations for these counterintuitive findings with a series of methodological improvements. These improvements were: Improvement 1: Used the Bay Area Rapid Transit (BART) system‘s 2008 Station Profile Survey travel data set to replace the Bay Area Travel Survey (BATS) 2000 data used in previous phases. Improvement 2: Separated drop-off and drive-alone modes in logit models. Improvement 3: Variables at the corridor level replaced previous variables at the transportation analysis zone (TAZ) level. Improvement 4: Average parcel size (APS) variable replaced the intersection density measure of urban design. Improvement 5: Used nested logit modeling techniques. These yielded strong evidence supporting the hypothesis that high-crime neighborhoods encourage driving, and they generated none of the counterintuitive findings from previous phases

Ronny Meyer: Wolane. Descriptive Grammar of an East Gurage Language (Ethiosemitic)

Revie

XXVIII. The conductometer

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