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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.

Rapid neck motions can load cervical nerve roots and produce persistent pain. This study investigated the cellular basis of radicular pain and mechanical implications of tissue loading rate. A range of peak loads was applied in an in vivo rat model of dorsal root compression, and mechanical allodynia (i.e., pain) was measured. Axonal damage and nociceptive mediators were assessed in the axons and cell bodies of compressed dorsal roots in separate groups of rats at days 1 and 7 after injury. In the day 7 group, damage in the compressed axons, evaluated by decreased heavy chain neurofilament immunoreactivity, was increased for compressions above a load of 34.08 mN, which is similar to the load-threshold for producing persistent pain in that model.

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.

While studies have demonstrated the cervical facet capsule is at risk for tensile injury during whiplash, the relationship between joint loading, changes in the capsule's structure, and pain is not yet fully characterized. Complementary approaches were employed to investigate the capsule's structure-function relationship in the context of painful joint loading. Isolated C6/C7 facet joints (n=8) underwent tensile mechanical loading, and measures of structural modification were compared for two distraction magnitudes: 300 µm (PV) and 700 µm (SV). In a matched in vivo study, C6/C7 facet joints (n=4) were harvested after the same SV distraction and the tissue was sectioned to analyze collagen fiber organization using polarized light microscopy. Laxity following SV distraction (7.30±3.01%) was significantly greater (p<0.001) than that produced following PV distraction (0.99±0.44%).

Computational ergonomic analyses are often laboriously tested one task at a time. As digital human models improve, we can partially automate the entire analysis process of checking human factors requirements or regulations against a given design. We are extending our Parameterized Action Representation (PAR) to store requirements and its execution system to drive human models through required tasks. Databases of actions, objects, regulations, and digital humans are instantiated into PARs and executed by analyzers that simulate the actions on digital humans and monitor the actions to report successes and failures. These extensions will allow quantitative but localized design assessment relative to specific human factors requirements

Simulating human reach is still challenging when considering complex interactions with the environment. Standard approaches involve inverse kinematics (IK) methods and usually require a complete but exponential cost search in configuration space. In ergonomic applications, both “naturalness” and interactive performance are important. We describe a real-time, collision-free, sternum-rooted IK solution for an articulated human figure based on motion capture data, human strength models, and multi-joint coordination functions. Movement paths are discovered through spatial search in a partitioned workspace. The system generates natural collision-free reach motions in real-time. The resulting animations and statistics demonstrate the efficacy of this approach.

The earliest Digital Human Modeling systems were non-interactive analysis packages with crude graphics. Next generation systems added interactivity and articulated kinematic human models. The newest systems use real-time computer graphics, deformable figures, motion controllers, and user interfaces. Our long-term goal is to free the user as much as possible from interactive human model manipulation through direct understanding and execution of task instructions. We present a next generation DHM testbed that includes a scriptable interface, real-time collision-avoidance reach, empirical joint motion models, a versatile locomotion engine, motion capture and synthetic motion blends and combinations, and a smooth skinned scalable human model.

While extensive research points to mechanical injury of the cervical facet joint as a mechanism of whiplash injury, findings remain speculative regarding its potential for causing pain. The purpose of this study was to examine the relationship between facet joint distraction, capsular ligament strain, cellular nociceptive responses, and pain. A novel rat model of in vivo facet joint injury was used to impose C6/C7 joint distraction in separate studies of subcatastrophic and physiologic vertebral distraction, as well as sham procedures. A common clinical measure of behavioral hypersensitivity (allodynia) was measured for 14 days after injury, as quantification of resulting pain symptoms. Also, on day 14, spinal activation of microglia and astrocytes was quantified to examine the potential role of glial activation as a physiologic mechanism of facet-mediated painful injury. Vertebral distractions of 0.90±0.53 mm across the rat facet joint reliably produced symptoms of persistent pain.

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).

To meet the increasing electrical power demands for advanced internal combustion engine (ICE) vehicles, auxiliary power units (APUs) are of growing interest. Fuel cell based APUs offer the potential for high chemical-to-electrical conversion efficiency with low noise and low emissions. It has recently been shown that solid oxide fuel cells (SOFCs) can be used to directly convert the chemical energy of liquid hydrocarbon fuels to electricity. Because the combustion reaction takes place by direct oxidation of vaporized fuel at the fuel cell anode, the expectation exists for development of compact, reformerless APUs that can operate on the same fuel that the ICE uses for vehicle propulsion. Critical issues for the transportation SOFC-APU applications are fast start-up and the need to survive extensive thermal cycling.

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.

In vivo, tissue-level, mechanical thresholds for axonal injury in the guinea pig optic nerve were determined by comparing morphological injury to estimated in vivo tissue strain. The right optic nerve of adult male guinea pigs was stretched to one of seven ocular displacement levels. Morphological injury was detected three days post-stretch with neurofilament immunohistochemical staining (NF68). A companion set of in situ experiments was used to determine the empirical relationship between ocular displacement and optic nerve stretch. Logistics regression analysis, combined with sensitivity and specificity measures and receiver operating characteristic (ROC) curves were then used to predict strain thresholds for axonal injury. From this analysis, we determined three Lagrangian strain- based thresholds for morphological damage to the guinea pig white matter.

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.

Carnegie Mellon Driving Research Center, together with ISIM, is presently involved in the design and development of an Advanced Human Factors Research and Driving Training Research Facility. The facility has been designed to address human factors issues and driver training issues. Human factors interests include developing countermeasures for fatigue and driver/vehicle interface issues. Driver training issues include validating the usefulness of simulators for driver training, developing effective curricula and investigating simulator fidelity needed for effective training. A key component of the facility is the Carnegie Mellon TruckSim that will be capable of simulating a variety of commercial and emergency vehicles using interchangeable cabs mounted to a common motion platform. TruckSim's modular configuration will allow for rapid and cost effective design of experiments and training scenarios. A first research program to evaluate fatigue countermeasures is presented as an example.

Traumatic brain injury finite element analyses have evolved from crude geometric representations of the skull and brain system into sophisticated models which take into account distinct anatomical features. However, two distinct finite element modeling approaches have evolved to account for the relative motion that occurs between the skull and cerebral cortex during traumatic brain injury. The first and most common approach assumes that the relative motion can be estimated by representing the cerebrospinal fluid inside the subarachnoid space as a low shear modulus, virtually incompressible solid. The second approach assumes that the relative motion can be approximated by defining a frictional interface between the cerebral cortex and dura mater. This study presents data from an experimental model of traumatic brain injury coupled with finite element analyses to evaluate the modeling approach's ability to predict specific forms of traumatic brain injury.