| 1. |
- Kokkolaras, Michael, et al.
(författare)
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Design Under Uncertainty and Assessment of Performance Reliability of a Dual-Use Medium Truck with Hydraulic-Hybrid Powertrain and Fuel Cell Auxiliary Power Unit
- 2005
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Ingår i: 2005 SAE world congress. - Warrendale, Pa : Society of Automotive Engineers, Incorporated.
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Konferensbidrag (refereegranskat)abstract
- Medium trucks constitute a large market segment of the commercial transportation sector, and are also used widely for military tactical operations. Recent technological advances in hybrid powertrains and fuel cell auxiliary power units have enabled design alternatives that can improve fuel economy and reduce emissions dramatically. However, deterministic design optimization of these configurations may yield designs that are optimal with respect to performance but raise concerns regarding the reliability of achieving that performance over lifetime. In this article we identify and quantify uncertainties due to modeling approximations or incomplete information. We then model their propagation using Monte Carlo simulation and perform sensitivity analysis to isolate statistically significant uncertainties. Finally, we formulate and solve a series of reliability-based optimization problems and quantify tradeoffs between optimality and reliability. The most relevant design parameters of the diesel engine, fuel cell, driveline and vehicle are considered. The results demonstrate the necessity for addressing uncertainty to make valid assessments and design decisions
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| 2. |
- Li, Zhijun, et al.
(författare)
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An Optimization Study of Manufacturing Variation Effects on Diesel Injector Design with Emphasis on Emissions
- 2005
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Ingår i: S A E Transactions. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0096-736X. ; 113:Section 5, s. 724-733
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the effects of manufacturing variations in fuel injectors on the engine performance with emphasis on emissions. The variations are taken into consideration within a Reliability-Based Design Optimization (RBDO) framework. A reduced version of Multi-Zone Diesel engine Simulation (MZDS), MZDS-lite, is used to enable the optimization study. The numerical noise of MZDS-lite prohibits the use of gradient-based optimization methods. Therefore, surrogate models are developed to filter out the noise and to reduce computational cost. Three multi-objective optimization problems are formulated, solved and compared: deterministic optimization using MZDS-lite, deterministic optimization using surrogate models and RBDO using surrogate models. The obtained results confirm that manufacturing variation effects must be taken into account in the early product development stages
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| 3. |
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| 4. |
- Michelena, Nestor, et al.
(författare)
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Design of an Advanced Heavy Tactical Trucks : A Target Cascading Case Study
- 2001
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Ingår i: International Truck and Bus Meeting and Exhibition. - Warrendale, Pa : Society of Automotive Engineers, Incorporated.
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Konferensbidrag (refereegranskat)abstract
- The target cascading methodology is applied to the conceptual design of an advanced heavy tactical truck. Two levels are defined: an integrated truck model is represented at the top (vehicle ) level and four independent suspension arms are represented at the lower (system ) level. Necessary analysis models are developed, and design problems are formulated and solved iteratively at both levels. Hence, vehicle design variables and system specifications are determined in a consistent manner. Two different target sets and two different propulsion systems are considered. Trade-offs between conflicting targets are identified. It is demonstrated that target cascading can be useful in avoiding costly design iterations late in the product development process.
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| 5. |
- Olsson, Jan-Ola, et al.
(författare)
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Compression Ratio Influence on Maximum Load of a Natural Gas Fueled HCCI Engine
- 2002
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Ingår i: SAE Transactions, Journal of Engines. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0096-736X. ; 111:3, s. 442-458
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses the compression ratio influence on maximum load of a Natural Gas HCCI engine. A modified Volvo TD100 truck engine is controlled in a closed-loop fashion by enriching the Natural Gas mixture with Hydrogen. The first section of the paper illustrates and discusses the potential of using hydrogen enrichment of natural gas to control combustion timing. Cylinder pressure is used as the feedback and the 50 percent burn angle is the controlled parameter. Full-cycle simulation is compared to some of the experimental data and then used to enhance some of the experimental observations dealing with ignition timing, thermal boundary conditions, emissions and how they affect engine stability and performance. High load issues common to HCCI are discussed in light of the inherent performance and emissions tradeoff and the disappearance of feasible operating space at high engine loads. The problems of tighter limits for combustion timing, unstable operational points and physical constraints at high loads are discussed and illustrated by experimental results. Finally, the influence on operational limits, i.e., emissions peak pressure rise and peak cylinder pressure, from compression ratio at high load are discussed.
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