Needle & knot : binder boilerplate tied up

To lighten the burden of programming language mechanization, many approaches have been developed that tackle the substantial boilerplate which arises from variable binders. Unfortunately, the existing approaches are limited in scope. They typically do not support complex binding forms (such as multi-binders) that arise in more advanced languages, or they do not tackle the boilerplate due to mentioning variables and binders in relations. As a consequence, the human mechanizer is still unnecessarily burdened with binder boilerplate and discouraged from taking on richer languages. This paper presents Knot, a new approach that substantially extends the support for binder boilerplate. Knot is a highly expressive language for natural and concise specification of syntax with binders. Its meta-theory constructively guarantees the coverage of a considerable amount of binder boilerplate for well-formed specifications, including that for well-scoping of terms and context lookups. Knot also comes with a code generator, Needle, that specializes the generic boilerplate for convenient embedding in COQ and provides a tactic library for automatically discharging proof obligations that frequently come up in proofs of weakening and substitution lemmas of type-systems. Our evaluation shows, that Needle & Knot significantly reduce the size of language mechanizations (by 40% in our case study). Moreover, as far as we know, Knot enables the most concise mechanization of the POPLmark Challenge (1a + 2a) and is two-thirds the size of the next smallest. Finally, Knot allows us to mechanize for instance dependentlytyped languages, which is notoriously challenging because of dependent contexts and mutually-recursive sorts with variables

Accelerometer based measurements of combustion in an automotive turbocharged diesel engine

The capability to detect combustion in a diesel engine has the potential of being an important control feature to meet increasingly stringent emission regulations, develop alternative combustion strategies, and use of biofuels. In this dissertation, block mounted accelerometers were investigated as potential feedback sensors for detecting combustion characteristics in a high-speed, high pressure common rail (HPCR), 1.9L diesel engine. Accelerometers were positioned in multiple placements and orientations on the engine, and engine testing was conducted under motored, single and pilot-main injection conditions. Engine tests were conducted at varying injection timings, engine loads, and engine speeds to observe the resulting time and frequency domain changes of the cylinder pressure and accelerometer signals. The frequency content of the cylinder pressure based signals and the accelerometer signals between 0.5 kHz and 6 kHz indicated a strong correlation with coherence values of nearly 1. The accelerometers were used to produce estimated combustion signals using the Frequency Response Functions (FRF) measured from the frequency domain characteristics of the cylinder pressure signals and the response of the accelerometers attached to the engine block. When compared to the actual combustion signals, the estimated combustion signals produced from the accelerometer response had Root Mean Square Errors (RMSE) between 7% and 25% of the actual signals peak value. Weighting the FRF’s from multiple test conditions along their frequency axis with the coherent output power reduced the median RMSE of the estimated combustion signals and the 95th percentile of RMSE produced from each test condition. The RMSE’s of the magnitude based combustion metrics including peak cylinder pressure, MPG, peak ROHR, and work estimated from the combustion signals produced by the accelerometer responses were between 15% and 50% of their actual value. The MPG measured from the estimated pressure gradient shared a direct relationship to the actual MPG. The location based combustion metrics such as the location of peak values and burn durations were capable of RMSE measurements as low as 0.9°. Overall, accelerometer based combustion sensing system was capable of detecting combustion and providing feedback regarding the in cylinder combustion proces

Application and comparison of soy based biodiesel fuel to ultra low sulfur diesel fuel in a HPCR diesel engine - Part II: combustion and emissions

Biofuels have the potential to diversify transportation energy sources and reduce dependence on petroleum based fuels. Of these biofuels, Methyl-ester biodiesel holds significant potential as it has many characteristics similar to petroleum based diesel and can be blended with petroleum. However, biodiesel's differences in viscosity, specific energy, oxygen content, and cetane number can cause significant changes in engine performance and emissions. Therefore, it is of prime interest to understand the combustion behaviour of biodiesel and identify key factors that contribute changes in engine performance and emissions. In this study, a 100% biodiesel fuel derived from soy and an ultra low sulphur diesel fuel were tested in a high-speed direct-injection high pressure common rail four-cylinder 1.9L diesel engine. The engine control strategy allowed real time calibration and testing of independent control parameters including start of injection, injection duration, injection pressure, and exhaust gas recirculation (EGR) level. The engine was equipped with in-cylinder pressure transducers for combustion analysis. Instrumentation for gaseous emissions detection and carbaceous particulate matter (PM) sampling was also utilized. Both the fuels were studied under varied injection timing of 0centigrade BTDC to 12 centigrade BTDC in increments of 3 centigrade, EGR percentages of 0 and 10%, and injection pressures of 400 to 900 bar. Analysis was performed to determine the rate of heat release, ignition delay, NOX and PM emissions

Application and comparison of soy based biodiesel fuel to ultra low sulfur diesel fuel in a HPCR diesel engine - part I: engine performance parameters

In the US transportation sector uses two-thirds of the country's total oil consumption. In order to minimize the consumption in this sector there is a need to investigate alternate sources of energy. Biodiesel is a possible alternative to conventional diesel. Biodiesel has many characteristics similar to petroleum based diesel and can be blended with petroleum. However biodiesel's differences in fuel properties including viscosity, bulk modulus, density, and energy content can have significant impacts on engine performance parameters like BSFC and thermal efficiency. As the availability of biodiesel fuel increases, the need for engines capable of running on various mixtures of biodiesel fuel will be required. Similar to flex-fuel ethanol vehicles, control systems for the diesel engine and aftertreatment systems will need to detect and compensate for the fuel type. In this work, a soy based B100 biodiesel fuel and an ultra low sulfur diesel fuel were tested in a high-speed direct-injection high pressure common rail four-cylinder 1.9 L diesel engine. An internally developed engine control strategy allowed real-time calibration and testing of independent control parameters including start of injection, injection duration, injection pressure, and exhaust gas recirculation (EGR) level. Both the fuels were studied under varied injection timing (0°BTDC to 12°BTDC with increments of 3°) and EGR percentages of 0 and 10%. Analysis was performed to determine the Torque, BSFC and Brake thermal efficiency

Combustion and emissions characterization of soy methyl ester biodiesel blends in an automotive turbocharged diesel engine

Recent increases in petroleum fuel costs, corporate average fuel economy (CAFE) regulations, and environmental concerns about CO2 emissions from petroleum based fuels have created an increased opportunity for diesel engines and non-petroleum renewable fuels such as biodiesel. Additionally, the Environmental Protection Agencies Tier II heavy duty and light duty emissions regulations require significant reductions in NOx and diesel particulate matter emissions for diesel engines. As a result, the diesel engine and aftertreatment system is a highly calibrated system that is sensitive to fuel characteristics. This study focuses on the impact of soy methyl ester biodiesel blends on combustion performance, NOx, and carbonaceous soot matter emissions. Tests were completed using a 1.9 L, turbocharged direct injection diesel engine using commercially available 15 ppm ultra low sulfur (ULS) diesel, a soy methyl ester B20 biodiesel blend (20 vol % B100 and 80 vol % ULS diesel), and a pure soy methyl ester biodiesel. Results show a reduction in NOx and carbonaceous soot matter emissions, and an increase in brake specific fuel consumption with the use of biodiesel. Further, traditional methodology assumes that diesel fuels with a high cetane number have a reduced ignition delay. However, results from this study show the cetane number is not the only parameter effecting ignition delay due to increased diffusion burn. © 2010 by ASME

Accelerometer based sensing of combustion in a high speed HPCR diesel engine

The capability to detect combustion in a diesel engine has the potential of being an important control feature to meet increasingly stringent emission regulations and for the development of alternative combustion strategies such as HCCI and PCCI. In this work, block mounted accelerometers are investigated as potential feedback sensors for detecting combustion characteristics in a high-speed, high pressure common rail (HPCR), 1.9L diesel engine. Accelerometers are positioned in multiple placements and orientations on the engine, and engine testing is conducted under motored, single and pilot-main injection conditions. Engine tests are then conducted at varying injection timings to observe the resulting time and frequency domain changes of both the pressure and acceleration signals. The higher frequency (3 kHz ≤ f ≤ 25 kHz) components of the in-cylinder pressure are found to correlate to the peak rate of in-cylinder heat release and indicated a potential application to the detection of combustion. The accelerometer and pressure signals are analyzed through the use of various functions including angle dependant fast Fourier transforms (FFT) and coherence to isolate frequency components that are well correlated between the cylinder pressure and accelerometer signals. In addition, these analysis techniques are used to compare the three accelerometer orientations and the individual accelerometer placements

Combustion and emissions characterization of soy methyl ester biodiesel blends in an automotive turbocharged diesel engine

Recent increases in petroleum fuel costs, CAFE standards, and environmental concerns about CO2 emissions from petroleum based fuels have created an increased opportunity for diesel engines and renewable alternative fuels such as biodiesel. Additionally, the Environmental Protection Agencies Tier II heavy duty and light duty emissions regulations require significant reductions in NOx and diesel particulate matter emissions for diesel engines. As a result, the diesel engine and aftertreatment system is a highly calibrated system that is sensitive to changing fuel characteristics. This study focuses on the impact of soy methyl ester biodiesel blends on combustion performance, carbonaceous soot matter and NOx emissions. Tests were completed with an I4 1.9L, turbocharged, high speed, direct injection diesel engine using commercially available 15 ppm ultra low sulfur diesel, a soy methyl ester B20 (20% biodiesel and 80% ultra low sulfur diesel) biodiesel blend and a pure soy methyl ester biodiesel. Results show a reduction in NOx and carbonaceous soot matter emissions and an increase in brake specific fuel consumption with the use of biodiesel. Further, traditional methodology assumes that diesel fuels with a high cetane number have a reduced ignition delay. However, results from this study show the cetane number is not the only parameter effecting ignition delay. Copyright © 2009 by ASME