In this work, the influences of ethanol and iso-butanol blended with gasoline on engine-out and post three-way catalyst (TWC) particle size distribution and number concentration were studied using a General Motors (GM) 2.0L turbocharged spark ignition direct injection (SIDI) engine. The engine was operated using the production engine control unit (ECU) with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at 10 selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm. Idle and low-speed / low-load conditions emitted higher total particle numbers than other operating conditions. At idle, the engine-out particulate matter (PM) emissions were dominated by nucleation mode particles, and the production TWC reduced these nucleation mode particles by more than 50%, while leaving the accumulation mode particle distribution unchanged. At an engine load higher than 6 bar net mean effective pressure (NMEP), accumulation mode particles dominated the engine-out particle emissions, and the TWC had little effect. Compared to the baseline gasoline (E0), E10 does not significantly change PM emissions, while E20 and BU12 both reduce PM emissions under the conditions studied. Iso-butanol was observed to impact PM emissions more than ethanol, with up to 50% reductions at some conditions. In this paper, issues related to PM measurement using the FMPS are also discussed. While some uncertainties are due to engine variation, the FMPS must be carefully maintained in order to achieve repeatable measurement results. 15. SUBJECT TERMS gasoline; ethanol blended; biofuel; iso-butanol; particle size distribution; emissions 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UL 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON a. REPORT

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Powered ankle-foot prostheses assist users through plantarflexion during stance and dorsiflexion during swing. Provision of motor power permits faster preferred walking speeds than passive devices, but use of active motor power raises the issue of control. While several commercially available algorithms provide torque control for many intended activities and variations of terrain, control approaches typically exhibit no inherent adaptation. In contrast, muscles adapt instantaneously to changes in load without sensory feedback due to the intrinsic property that their stiffness changes with length and velocity. We previously developed a "winding filament" hypothesis (WFH) for muscle contraction that accounts for intrinsic muscle properties by incorporating the giant titin protein. The goals of this study were to develop a WFH-based control algorithm for a powered prosthesis and to test its robustness during level walking and stair ascent in a case study of two subjects with 4-5 years of experience using a powered prosthesis. In the WFH algorithm, ankle moments produced by virtual muscles are calculated based on muscle length and activation. Net ankle moment determines the current applied to the motor. Using this algorithm implemented in a BiOM T2 prosthesis, we tested subjects during level walking and stair ascent. During level walking at variable speeds, the WFH algorithm produced plantarflexion angles (range = −8 to −19 •) and ankle moments (range = 1 to 1.5 Nm/kg) similar to those produced by the BiOM T2 stock controller and to people with no amputation. During stair ascent, the WFH algorithm produced plantarflexion angles (range −15 to −19 •) that were similar to persons with no amputation and were ∼5 times larger on average at 80 steps/min than those produced by the stock controller. This case study provides proof-of-concept that, by emulating muscle properties, the WFH algorithm provides robust, adaptive control of level walking at variable speed and stair ascent with minimal sensing and no change in parameters.

The purpose of this study was to measure the impact of various sources of petroleum-based and bio-based diesel fuels on regulated emissions and fuel economy in diesel particulate filter (DPF) equipped diesel engines. Two model year 2008 diesel engines were tested with nine fuels including a certification ultra-low sulfur diesel (ULSD), local ULSD, high aromatic ULSD, low aromatic ULSD, and twenty percent blends of biodiesel derived from algae, camelina, soy, tallow, and yellow grease. Regulated emissions were measured over the heavy duty diesel transient test cycle. Measurements were also made of DPF-out particle size distribution and total particle count from a 13-mode steady state test using a fast mobility particle sizer. Test engines were a 2008 Cummins ISB and a 2008 International Maxx Force 10, both equipped with actively regenerated DPFs. Fuel consumption was roughly 2% greater over the transient test cycle for the B20 blends versus certification ULSD in both engines, consistent with the slightly lower energy content of biodiesel. Unlike studies conducted on older model engines, these engines equipped with diesel oxidation catalysts and DPFs showed small or no measurable fuel effect on the tailpipe emissions of total hydrocarbons (THC), carbon monoxide (CO) and particulate matter (PM). No differences in particle size distribution or total particle count were seen in a comparison of certification ULSD and B20 soy, with the exception of engine idling conditions where B20 produced a small reduction in the number of nucleation mode particles. In the Cummins engine, B20 prepared from algae, camelina, soy, and tallow resulted in an approximately 2.5% increase in nitrogen oxides (NOx) compared to the base fuel. The International engine demonstrated a higher degree of variability for NOx emissions, and fuel effects could not be resolved (p > 0.05). The group of petroleum diesel test fuels produced a range of NOx emissions very similar to that caused by blending of biodiesel. Test cycles where an active regeneration of the DPF occurred resulted in a nearly threefold increase in NOx emissions and a 15% increase in fuel consumption. The full quantification of DPF regeneration events further complicates the accurate calculation of fuel impacts on emissions and fuel consumption.

The influences of ethanol and iso-butanol on gasoline engine performance, engine-out and tailpipe emissions were studied using a General Motors (GM) 2.0L turbocharged gasoline spark ignition direct injection (SIDI) engine. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuels were tested. Fourier-Transform Infrared (FTIR) spectroscopy was used to measure non-regulated species including methane, ethylene, acetylene, formaldehyde, acetaldehyde, isobutylene, 1,3-butadiene, n-pentane, and iso-octane. A Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle number (PN) size distribution in the range from 5.6 to 560 nm. The regulated emissions total hydrocarbon (THC), carbon monoxide (CO), and oxides of nitrogen (NOx) were also measured. Both engine-out and tailpipe emissions results are presented as functions of alcohol content. In general, the alcohols tested reduced total PN emissions, with iso-butanol demonstrating the greatest reduction. Increasing ethanol content and iso-butanol increased formaldehyde emissions, with iso-butanol exhibiting the highest increase. Iso-butanol increased iso-butylene emission; however, it reduced emissions of 1,3-butadiene. Within the context of this study, the alcohols did not significantly change the other regulated emissions.