scholarly journals Transit Bus Fuel Economy and Performance Simulation

1984 ◽  
Author(s):  
Russell W. Zub
2021 ◽  
Author(s):  
Xinyi Xiao ◽  
Byeong-Min Roh

Abstract The integration of Topology optimization (TO) and Generative Design (GD) with additive manufacturing (AM) is becoming advent methods to lightweight parts while maintaining performance under the same loading conditions. However, these models from TO or GD are not in a form that they can be easily edited in a 3D CAD modeling system. These geometries are generally in a form with no surface/plane information, thus having non-editable features. Direct fabricate these non-feature-based designs and their inherent characteristics would lead to non-desired part qualities in terms of shape, GD&T, and mechanical properties. Current commercial software always requires a significant amount of manual work by experienced CAD users to generate a feature-based CAD model from non-feature-based designs for AM and performance simulation. This paper presents fully automated shaping algorithms for building parametric feature-based 3D models from non-feature-based designs for AM. Starting from automatically decomposing the given geometry into “formable” volumes, which is defined as a sweeping feature in the CAD modeling system, each decomposed volume will be described with 2D profiles and sweeping directions for modeling. The Boolean of modeled components will be the final parametric shape. The volumetric difference between the final parametric form and the original geometry is also provided to prove the effectiveness and efficiency of this automatic shaping methodology. Besides, the performance of the parametric models is being simulated to testify the functionality.


2021 ◽  
pp. 1-45
Author(s):  
Benjamin Leard ◽  
Joshua Linn ◽  
Yichen Christy Zhou

Abstract During historical periods in which US fuel economy standards were unchanging, automakers increased performance but not fuel economy, contrasting with recent periods of tightening standards and rising fuel economy. This paper evaluates the welfare consequences of automakers forgoing performance increases to raise fuel economy as standards have tightened since 2012. Using a unique data set and a novel approach to account for fuel economy and performance endogeneity, we find undervaluation of fuel cost savings and high valuation of performance. Welfare costs of forgone performance approximately equal expected fuel savings benefits, suggesting approximately zero net private consumer benefit from tightened standards.


Author(s):  
Daniel Crunkleton ◽  
Robert Strattan

The fuel economy and emission advantages of diesel-electric hybrid powertrain modifications and an auxiliary fuel cell subsystem over those of a conventional midsize crossover SUV are discussed. The vehicle architecture is representative of one selected for the multiyear ChallengeX intercollegiate student design contest. To analyze the fuel economy, a simple “top-level” approach is used to estimate the fuel economy characteristics and performance potential to illustrate the advantages of the hybrid-electric powertrain configuration and the auxiliary fuel cells. Chained energy efficiency assumptions for the powertrain components lead to gasoline equivalent fuel mileage estimates. In the emission analysis, the greenhouse gases, regulated emissions, and energy use in transportation model is used to track the environmental impact of the powertrain on a well-to-wheels basis.


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