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A manifold filling model is used to derive a real time cylinder air charge estimate for mass air flow rate sensor equipped vehicles. The derivation shows that a simple first order linear difference equation in the discrete cylinder event domain is obtained from a coupled set of nonlinear differential equations.

The Texas Department of Transportation (TxDOT) has initiated an aggressive plan to convert its on-road motor vehicle fleet of 9,000 vehicles to alternative fuels. State legislation passed in 1989 requires that TxDOT have 90% of its fleet converted by 1998. This undertaking has radically changed the way the Department both purchases and manages its fleet and thus has required major changes in the planning, procurement and utilization of its vehicles. The initial implementation of an alternative fuels program should consider and account Incentives: Energy abundance, environmental protection, economic concerns Initiatives: (Federal) Clean Air Act Amendment, Energy Policy Act, individual state legislation Barriers: Equipment cost, fuel availability, market inertia, underdeveloped infrastructure

The cost–effectiveness of using alternative fuels (AF) versus a conventional fuel (gasoline) in light duty vehicles is traditionally presented with a simple analysis on what can best be described as “one sheet of paper.” Unfortunately, oversimplification of the cost analysis can lead to extensive errors in the results and misleading cost and/or benefit conclusions. An extensive model for analyzing the costs and benefits of using alternative fuels has been developed which allows in–depth modeling of major characteristics of a single vehicle (or an entire fleet) which uses alternative fuel. Net present value (NPV) theorem financial modeling has been used to compute a true lifetime cost of ownership. An important output of the model is the required fuel spread needed in order to obtain a NPV of zero dollars, indicating that the savings resulting from using the alternative fuel offset the cost of the additional AF components.

The Idaho State University design team, competing in the 2003 Clean Snowmobile Challenge Collegiate Design Competition, has developed a strategy to reduce the amount of harmful emissions common to two-stroke snowmobiles. The team designed a Low Pressure In-Cylinder Fuel Injection system to reduce the amount of fuel being short-circuited through the exhaust system. The system was installed on a 500cc Polaris two-stroke engine in a 2000 Polaris RMK chassis. Noise emissions were addressed by designing a muffler capable of dissipating more energy by way of damping materials and frequency attenuating techniques. Damping materials were added to the engine compartment and unnecessary vent holes were removed to reduce engine noise emitted.

The Texas Department of Transportation (TxDOT) began using an emulsified diesel fuel in July 2002. They initiated a simultaneous study of the effectiveness of this fuel in comparison to 2D on-road diesel fuel, which they use in both their on-road and off-road equipment. The study also incorporated analyses for the fleet operated by the Associated General Contractors (AGC) in the Houston area. Some members of AGC use 2D off-road diesel fuel in their equipment. The study included comparisons of fuel economy and emissions for the emulsified fuel relative to the conventional diesel fuels. Cycles that are known to be representative of the typical operations for TxDOT and AGC equipment were required for use in this study. Four test cycles were developed from data logged on equipment during normal service: 1) the TxDOT Telescoping Boom Excavator Cycle, 2) the AGC Wheeled Loader Cycle, 3) the TxDOT Single-Axle Dump Truck Cycle, and 4) the TxDOT Tandem-Axle Dump Truck Cycle.

The Texas Department of Transportation began using an emulsified diesel fuel in 2002. They initiated a simultaneous study of the effectiveness of this fuel in comparison to 2D on-road diesel fuel and 2D off-road diesel. The study included comparisons of fuel economy and emissions for the emulsion, Lubrizol PuriNOx®, relative to conventional diesel fuels. Two engines and eight trucks, four single-axle dump trucks, and four tandem-axle dump trucks were tested. The equipment tested included both older mechanically-controlled diesels and newer electronically-controlled diesels. The two engines were tested over two different cycles that were developed specifically for this project. The dump trucks were tested using the “route” technique over one or the other of two chassis dynamometer cycles that were developed for this project In addition to fuel efficiency, emissions of NOx, PM, CO, and HCs were measured. Additionally, second-by-second results were obtained for NOx and HCs.

The Texas Department of Transportation (TxDOT) began using an emulsified diesel fuel as an emissions control measure in July 2002. They initiated a study of the effectiveness of this fuel in comparison to conventional diesel fuel for TxDOT's Houston District operations and included the fleet operated by the Associated General Contractors (AGC) in the Houston area. Cost-effectiveness analyses, including the incremental cost per ton of NOx removed, were performed. NOx removal was the focus of this study because Houston is an ozone nonattainment area, and NOx is believed to be the limiting factor in ozone formation in the Houston area. The cost factors accounted for in the cost-effectiveness analyses included the incremental cost of the fuel (including an available rebate from the State of Texas), the cost of refueling more often, implementation costs, productivity costs, maintenance costs, and various costs associated with the tendency of the emulsion to separate.

The Texas Department of Transportation (TxDOT) began using an ultra-low-sulfur, low aromatic, high cetane number diesel fuel (TxLED, Texas Low Emission Diesel) in June 2003. They initiated a simultaneous study of the effectiveness to reduce emissions and influence fuel economy of this fuel in comparison to 2D on-road diesel fuel used in both their on-road and off-road equipment. The study incorporated analyses for the fleet operated by the Association of General Contractors (AGC) in the Houston area. Some members of AGC use 2D off-road diesel in their equipment. One off-road engine, two single-axle dump trucks, and two tandem-axle dump trucks were tested. The equipment tested included newer electronically-controlled diesels. The off-road engine was tested over the TxDOT Telescoping Boom Excavator Cycle. The dump trucks were tested using the “route” technique over the TxDOT Single-Axle Dump Truck Cycle or the TxDOT Tandem-Axle Dump Truck Cycle.