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Natural gas (NG) is an alternative fuel for spark-ignition engines. In addition to its cleaner combustion, recent breakthroughs in drilling technologies increased its availability and lowered its cost. NG consists of mostly methane, but it also contains heavier hydrocarbons and inert diluents, the levels of which vary substantially with geographical source, time of the year and treatments applied during production or transportation. To investigate the effects of NG composition on engine performance and emissions, a 3D CFD model of a heavy-duty diesel engine retrofitted to NG spark ignition simulated lean-combustion engine operation at low speed and medium load conditions. The work investigated three NG blends with similar lower heating value (i.e., similar energy density) but different Methane Number (MN). The results indicated that a lower MN increased flame propagation speed and thus increased in-cylinder pressure and indicated mean effective pressure.

This paper presents 3D finite element analysis performed for a composite cylindrical tank made of 6061-aluminum liner overwrapped with carbon fibers subjected to a burst internal pressure of 1610 bars. As the service pressure expected in these tanks is 700 bars, a factor of safety of 2.3 is kept the same for all designs. The optimal design configuration of such high pressure storage tanks includes an inner liner used as a gas permeation barrier, geometrically optimized domes, inlet/outlet valves with minimum stress concentrations, and directionally tailored exterior reinforcement for high strength and stiffness. Filament winding of pressure vessels made of fiber composite materials is the most efficient manufacturing method for such high pressure hydrogen storage tanks. The complexity of the filament winding process in the dome region is characterized by continually changing the fiber orientation angle and the local thickness of the wall.

The hydrogen economy envisioned in the future requires safe and efficient means of storing hydrogen fuel for either use on-board vehicles, delivery on mobile transportation systems or high-volume storage in stationary systems. The main emphasis of this work is placed on the high -pressure storing of gaseous hydrogen on-board vehicles. As a result of its very low density, hydrogen gas has to be stored under very high pressure, ranging from 350 to 700 bars for current systems, in order to achieve practical levels of energy density in terms of the amount of energy that can be stored in a tank of a given volume. This paper presents 3D finite element analysis performed for a composite cylindrical tank made of 6061-aluminum liner overwrapped with carbon fibers subjected to a burst internal pressure of 1610 bars. As the service pressure expected in these tanks is 700 bars, a factor of safety of 2.3 is kept the same for all designs.

West Virginia University characterized the emissions and fuel economy performance of a 30-foot 2010 transit bus equipped with urea selective catalytic reduction (u-SCR) exhaust aftertreatment. The bus was exercised over speed-time driving schedules representative of both urban and on-highway activity using a chassis dynamometer while the exhaust was routed to a full-scale dilution tunnel with research grade emissions analyzers. The Paris speed-time driving schedule was used to represent slow urban transit bus activity while the Cruise driving schedule was used to represent on-highway activity. Vehicle weights representative of both one-half and empty passenger loading were evaluated. Fuel economy observed during testing with the urban driving schedule was significantly lower (55%) than testing performed with the on-highway driving schedule.

Currently, the chassis assembly contributes about 73 percent of the overall weight of a 14.63 m long haul trailer. This paper presents alternative design concepts for the structural floor of a van trailer utilizing sandwich panels with various material and geometric characteristics of the core layer in order to reduce its weight significantly below that of the current design configuration. The main objective of the new designs is to achieve optimal tradeoffs between the overall structural weight and the flexural stiffness of the floor. Various preliminary design concepts of the core designs were compared on the basis of a single section of the core structure. Six different designs were analyzed by weight, maximum displacement and maximum stress under bending and torsion loads. Each concept was kept uniform by length, thickness, loading and boundary conditions. Each design concept was examined through testing of scaled model for floor assemblies.

Recent advances in Metal Matrix Composites have made them ready for transition to large-volume production and commercialization. Such new materials seem to allow the fabrication of higher quality parts at less than 50 percent of the weight as compared to steel. The increasing requirements of weight savings and extended durability motivated the potential application of MMC technology into the heavy vehicle market. However, significant technical barriers such as joining are likely to hinder the broad applications of MMC materials in heavy vehicles. The focus of this paper is to examine the feasibility of manufacturing and the behavior of bolted joint connections made from aluminum matrix reinforced with Silicon Carbide (SiC) particles. Two reinforcement ratios: 20% and 45% were considered in this study. The first part of the paper concentrates on experimental evaluation of bolted MMC joints.

When operating a piece of heavy equipment, the equipment operator is exposed to Whole Body Vibration (WBV), with peaks in the acceleration called jolting and jarring. Various published consensus standards exist to analyze overall WBV, but a consensus standard does not exist for describing, detecting, and categorizing the jolting and jarring peaks. During previous research into methods of measuring jolting and jarring, a Root Mean Square (RMS) method was implemented and deployed in jolting and jarring event meters called Shox Boxes (invented by the National Institute for Occupational Safety and Health, NIOSH). The RMS assessment was difficult for end users of the Shox Boxes to utilize for describing and categorizing the peaks. This paper offers a hypothetical standard, the Jolt-Duration (JD) method, based on the simple amplitude and duration of the peaks, as well as the time between peaks.

Comfort assessment of respirator fit plays an important role in the respirator design process and standard development. To reduce the cost and design time of respirators, the design, fit, and evaluation process can be performed in a virtual environment. Literature shows that respirator-induced discomfort relates to stress, area, and region of the face covered. In this work, we investigate the relationship between the strap tensions and the stress and deformation distribution on the interface between the respirator and the headform. This is the first step towards a comprehensive understanding of the contribution of contact stress to the mathematical comfort fit model. The 3D digital models for respirators and headforms have been developed based on 3D scanning point-cloud using a Cyberware® 3D digitizer. Five digital headform models have been generated: small, medium, large, long and short.

Digital human modeling (DHM) progress worldwide will be much faster and cohesive if the diverse community now developing simulations has a global blueprint for DHM, and is able to work together efficiently. DHM developers and users can save time by building on each other's work. This paper highlights a panel discussion on DHM goals and strategic plans for the next decade to begin formulating the international blueprint. Four subjects are chosen as the starting points: (1) moving DHM into the public safety and internet arenas, (2) role of DHM in computer assisted surgery and automotive safety, (3) DHM in defense applications, and (4) DHM to improve workplace ergonomics.

Facial measurements were collected during the 2003 National Institute for Occupational Safety and Health (NIOSH) survey of 3,997 respirator users. In addition to traditional measuring techniques, 1013 subjects were scanned with a Cyberware 3-D Rapid Digitizer. Ten facial dimensions relevant to respirator fit were chosen for defining a principal component analysis (PCA) model which divides the user population into five face-size categories. Mean facial dimensions were then computed as a goal for a representative headform for each size category and used to identify 5 scans in each category. An average of the five scanned subjects was used to develop a single standard headform for each face-size category. Four digital 3-D models were developed: small, medium, large, and long. The new headforms include facial features not found on current standard headforms.

Incidents in which a piece of construction equipment backed into a worker resulted in an average of 17 deaths per year at road construction sites and 15 deaths per year at building construction sites from 1997 through 2001. This trend continues and researchers at the National Institute for Occupational Safety and Health are evaluating methods to decrease these incidents. A new technology based on the detection of electronic identification tags worn by workers has been developed and evaluated at a road construction site. The tag-based proximity warning system consists of a magnetic field generator and communications system that mounts on the back of a piece of construction equipment such as a dump truck, road grader, or loader. Workers at a construction site wear a small tag that detects the magnetic marker field.

Feature-envelope technique is a method that describes the spatial location and orientation of areas or landmarks of interest with respect to a well-defined, easily duplicated coordinate system. This technique has been tested in a NIOSH study in guiding tractor designers in their placement of tractor control components in order to best accommodate the user population. NIOSH recently measured the human body dimensions of 100 West Virginia farm workers, including whole body surface scans, to examine body size accommodation issues associated with safe farm tractor operation and rollover protective structures. Multivariate anthropometric models were derived from this population based on measurements related to the workstation. The Euclidian distance of each subject for each model was computed, and those that scored the closest were identified as “nearest neighbors.”

Further growth of diesel engines in the light-duty and heavy-duty vehicular market is closely linked to the potential health risks of diesel exhaust. The California Air Resources Board and the Office of Environmental Health Hazard Assessment have identified diesel exhaust as a toxic air contaminant. The International Agency for Research on Cancer concluded that diesel particulate is a probable human carcinogen [1]. Cleaner burning liquid fuels, such as those derived from natural gas via the Fischer-Tropsch (FT) process, offer a potentially economically viable alternative to standard diesel fuel while providing reduced particulate emissions. Further understanding of FT operation may be realized by investigating the differences in toxicity and potential health effects between particulate matter(PM) derived from FT fuel and that derived from standard Federal diesel No. 2 (DF).

Particulate emission control from diesel engines is one of the major concerns in the urban areas in California. Recently, regulations have been proposed for stringent PM emission requirements from both existing and new diesel engines. As a result, particulate emission control from urban diesel engines using advanced particulate filter technology is being evaluated at several locations in California. Although ceramic based particle filters are well known for high PM reductions, the lack of effective and durable regeneration system has limited their applications. The continuously regenerated diesel particulate filter (CRDPF) technology discussed in this presentation, solves this problem by catalytically oxidizing NO present in the diesel exhaust to NO2 which is utilized to continuously combust the engine soot under the typical diesel engine operating condition.

Hybrid-electric transit buses offer benefits over conventional transit buses of comparable capacity. These benefits include reduced fuel consumption, reduced emissions and the utilization of smaller engines. Factors allowing for these benefits are the use of regenerative braking and reductions in engine transient operation through sophisticated power management systems. However, characterization of emissions from these buses represents new territory: the whole vehicle must be tested to estimate real world tailpipe emissions levels and fuel economy. The West Virginia University Transportable Heavy Duty Emissions Testing Laboratories were used to characterize emissions from diesel hybrid-electric powered as well as diesel and natural gas powered transit buses in Boston, MA and New York City.

Engineering analyses of work methods can help identify approaches to reduce the risk of occupational injuries; computer-aided simulation technology is effective in terms of time and cost for evaluating multiple work methods. This paper analyzed scaffolding, a common activity in construction with high frequency of overexertion injuries, through a computer simulation model (3DSSPP) to identify less stressful work strategies. A laboratory study was also performed to verify the appropriateness of using the model for scaffolding job analyses. Seven commonly used end-frame lifting techniques were evaluated. Computer simulations of these work techniques show that considerable biomechanical stress occurs to most of the workers at their shoulders and elbows. A symmetric front-lifting at knuckle height appears to be the less stressful work technique, as determined by computer simulation.

Specific aspects of a study aimed at developing a microwave assisted regeneration system for diesel particulate traps are discussed. Results from thermal and microwave characteristic studies carried out in the initial phase of the study are reported. The critical parameters that need to be optimized, for achieving controlled regeneration, are microwave preheating time period, regenerative air supply, regenerative air temperature, and soot deposition. Using a 1000 W magnetron, power measurements were made to select the best waveguide configuration for optimized transmission. A six cylinder naturally aspirated, indirect injection diesel engine was retrofitted with a customized exhaust system that included a Corning EX80 (5.66″ × 6.00″) type ceramic particulate trap. An automated exhaust bypass system enabled trap loading and subsequent regeneration with a customized microwave regeneration system. The paper discusses the salient details of both on-line and off-line regeneration setups.

Diesel soot interacts with the engine oil and leads to wear of engine parts. Engine oil additives play a crucial role in preventing wear by forming the anti-wear film between the wearing surfaces. The current study was aimed at investigating the interactions between engine soot and oil properties in order to develop high performance oils for diesel engines equipped with exhaust gas re-circulation (EGR). The effect of soot contaminated oil on wear of engine components was examined using a statistically designed experiment. To quantitatively analyze and simulate the extent of wear a three-body wear machine was designed and developed. The qualitative wear analysis was performed by examining the wear scars on an AISI 52100 stainless steel ball worn in the presence of oil test samples on a ball-on-flat disc setup. The three oil properties studied were base stock, dispersant level and zinc dithiophosphate level.

Synthetic diesel fuel can be made from a variety of feedstocks, including coal, natural gas and biomass. Synthetic diesel fuels can have very low sulfur and aromatic content, and excellent autoignition characteristics. Moreover, synthetic diesel fuels may also be economically competitive with California diesel fuel if produced in large volumes. Previous engine laboratory and field tests using a heavy-duty chassis dynamometer indicate that synthetic diesel fuel made using the Fischer-Tropsch (F-T) catalytic conversion process is a promising alternative fuel because it can be used in unmodified diesel engines, and can reduce exhaust emissions substantially. The objective of this study was a preliminary assessment of the emissions from older model transit operated on Mossgas synthetic diesel fuel. The study compared emissions from transit buses operating on Federal no. 2 Diesel fuel, Mossgas synthetic diesel (MGSD), and a 50/50 blend of the two fuels.

Emissions of six 32 passenger transit buses were characterized using one of the West Virginia University (WVU) Transportable Heavy Duty Emissions Testing Laboratories, and the fixed base chassis dynamometer at the Colorado Institute for Fuels and High Altitude Engine Research (CIFER). Three of the buses were powered with 1997 ISB 5.9 liter Cummins diesel engines, and three were powered with the 1997 5.9 liter Cummins natural gas (NG) counterpart. The NG engines were LEV certified. Objectives were to contrast the emissions performance of the diesel and NG units, and to compare results from the two laboratories. Both laboratories found that oxides of nitrogen and particulate matter (PM) emissions were substantially lower for the natural gas buses than for the diesel buses. It was observed that by varying the rapidity of pedal movement during accelerations in the Central Business District cycle (CBD), CO and PM emissions from the diesel buses could be varied by a factor of three or more.