No abstract

The purpose of this study was to determine the diagnostic accuracy of knee extensor muscle torque tracings in patients suspected of having damage to the anterior cruciate ligament of the knee joint. The knee extensor torque tracings of 30 patients suspected of having anterior instability of the knee joint were reviewed independently for abnormalities believed to be associated with anterior cruciate ligament damage. These results were compared blindly with an arthroscopic evaluation. The diagnostic accuracy of the torque tracing approach was determined by calculating the prevalence, sensitivity, specificity, and positive and negative predictive values. The sensitivity and specificity were calculated to be 25.0% and 85.7%, respectively. These results suggest that the curve patterns examined in this article have poor diagnostic accuracy and are of little benefit as a clinical diagnostic aid.

This paper documents results of fuel consumption and exhaust emission tests performed on a 1,500 kW EMD GP38-2 locomotive equipped with an auxiliary power unit (APU) designed to minimize main engine idling time by providing stand-by services normally provided by the main EMD 16-645-E engine at idle. The purpose of these tests was to perform an evaluation of the exhaust emissions and fuel consumption of both the EMD 16-645-E engine and the APU. The APU diesel engine was a 2.0L, 4-cylinder, turbocharged, Kubota model V2003-TEBG rated at 30.6 kW. The APU was tested using an external load box over a range of load conditions, ranging from unloaded (0 kW) through 16 kW, which was the maximum APU load expected as installed in the locomotive. Fuel consumption and exhaust emissions are compared between an idling EMD 16-645-E engine and the APU engine at a “typical” stand-by condition with the coolant and lubricating oil heaters operating and the locomotive control cab air conditioner turned off. Test results showed that the APU fuel consumption and exhaust emissions are dramatically lower than the idling EMD locomotive engine. Because the APU is designed to automatically start and stop as a function of the locomotive water temperature, and therefore operates only a portion of the time that the EMD engine would otherwise be idling. Reductions in fuel consumption and exhaust emissions over an extended period of time would be even more dramatic.

The 1,500 kW EMD 16-645E engine is popular in switcher and shunter locomotive applications for railroads in North America. These locomotives are typically lightly loaded with extended periods of idle operation, and usually operate in large urban areas. With the advent of EPA emissions standards, and increasing fuel costs, many in the railroad industry are looking at replacing these locomotives with hybrid locomotives, installing APU systems or automatic start stops systems, repowering with newer engines, or using new technology to reduce emissions and improve fuel consumption. This paper documents results of research into ways to improve idle and low power emissions and fuel consumption from these roots-blown two-cycle EMD 645E engines. Specifically, this research looked at disabling one bank of injectors to simulate skip fire operation, and the stopping the rotation of one of the two roots-type blowers used to supply boost air to the uni-flow, two-cycle, diesel engine. The results of this work demonstrated that the EMD 16-645E engine did not respond positively when the injectors of one cylinder bank were disabled (simulating bank to bank skip fire operation). However, the engine did demonstrate both a reduction of NOx emissions and brake specific fuel consumption, over the US-EPA switcher and line haul emissions cycles, while operating on only one of the two blowers at idle and light loads. Additionally this concept of blower cut-out allows for reduced mass flow and higher exhaust temperatures at light loads, which could be beneficial for future application of exhaust aftertreatment. However, there is an associated increase in particulate matter emissions.

As part of the Norfolk-Southern Railroad’s on-going investigation into fuel consumption reductions for their fleet of 3000 locomotives, the Center for Alternative Fuels, Engines and Emissions at West Virginia University conducted on-site locomotive engine performance and emissions measurements to characterize the performance, fuel consumption and emissions associated with fuel injectors from two injector suppliers. Emissions and fuel consumption were measured using the West Virginia University Transportable Locomotive Emissions Testing Laboratory, which was set up at the Norfolk-Southern Heavy Repair Facility in Roanoke, Virginia. The tests were conducted to evaluate potential emissions and fuel consumption differences between two fuel injector suppliers using an EMD GP38-2 locomotive equipped with a 2100 hp (1566 kW), 16-cylinder, EMD 16-645E engine. The test locomotive engine was freshly overhauled and certified to the EPA locomotive Tier 0 emissions standards. Emissions and fuel consumption measurements were conducted according to the Federal Test Procedures defined in the Code of Federal Regulations 40CFR Part 92 Subpart B [1]. The engine was first tested in the “as overhauled” configuration with the OEM fuel injectors to establish the baseline emissions and fuel consumption. The baseline FTP results confirmed that this locomotive was in compliance with the Federal Tier 0 emissions standards. The OEM specification fuel injectors were replaced with “Fuel Saver” injectors designed and manufactured by an aftermarket injector supplier referred to in this paper as Supplier B. The Supplier B injectors reduced fuel consumption on the average of 2–4% for each notch, except for Notch 4 and Low Idle. However, the Supplier B injectors increased the NOx levels by 20–30% for almost every notch, which is an expected result due to the improved combustion efficiency.