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The postcollision motion starts immediately upon completion of a collision impact where the vehicles obtain new sets of velocities through an exchange of momentum. Similitude with model study and fullscale automobile experiments indicate that the post-collision trajectory is essentially a plane motion, governed by inertia and tire friction. Trajectories depend on many parameters (such as tire friction coefficient, front wheel steering angle, vehicle geometrics, and whether wheels are locked or free to rotate) but not on the vehicle weight. Theoretical computation of trajectories are compared with experiments.

The Variable Dynamic Testbed Vehicle (VDTV) concept has been proposed as a tool to evaluate collision avoidance systems and to perform driving-related human factors research. The goal of this study is to analytically investigate to what extent a VDTV with adjustable front and rear anti-roll bar stiffnesses, programmable damping rates, and four-wheel-steering can emulate the lateral dynamics of a broad range of passenger vehicles. Using a selected compact-sized automobile as a baseline, our study indicated this baseline vehicle can be controlled to emulate the lateral response characteristics (including the vehicle's understeer coefficient and the 90% lateral acceleration rise time in a J-turn maneuver) of a fleet of production vehicles, from low to high lateral acceleration conditions.

Vehicle stability augmentation has been refined over many years, and currently there are commercial systems that control right/left braking and throttle to create vehicles that remain controlled when road conditions are very poor. These systems typically use yaw rate and lateral acceleration in their control philosophy. The tire/road friction coefficient, μ, has a significant role in vehicle longitudinal and lateral control, and there has been associated efforts to measure or estimate the road surface condition to provide additional information for the stability augmentation system. In this paper, a differential braking control strategy using yaw rate feedback, coupled with μ feedforward is introduced for a vehicle cornering on different μ roads. A nonlinear 4-wheel car model is developed. A desired yaw rate is calculated from the reference model based on the driver steering input.

In principle, the thermodynamic and thermochemical processes evolve with time, irrespectively of their spatial orientation. They are, therefore, specified in terms of ordinary differential equations with respect to time as the only independent variable. This feature is well reflected in the literature by the so-called zero-dimensional models. Current demands of technological progress impose much stricter requirements upon the precision of such calculations than ever before. A methodology for catering to them is presented. Its application is illustrated by the performance analysis of a Renault engine, operated at full and part loads, with particular emphasis placed upon the formation of major combustion-generated pollutants, NOx and CO, in a premixed-charge engine.

Optimizing the hardware design and control strategies of thermal management systems (TMS) in battery packs using large format pouch cells is a difficult but important problem due to the limited understanding of how internal temperature distributions impact the performance and lifetime of the pack. Understanding these impacts is difficult due to the greatly varying length and time scales between the coupled phenomena, causing the need for complex and computationally expensive models. Here, an experimental investigation is performed in which a set of fixed one-dimensional temperature distributions are applied across the face of a Nickel-Cobalt-Manganese (NCM) cathode lithium ion pouch cell in order to study the performance impacts. Effects on the open circuit voltage (OCV), Ohmic resistance, bulk discharge and charge resistance and instantaneous power are investigated.

A microhygrometer has been developed at JPL's Microdevices Laboratory based on the principle of dewpoint/frostpoint detection. The surface acoustic wave device used in this instrument is approximately two orders of magnitude more sensitive to condensation than the optical sensor used in chilled-mirror hygrometers. In tests in the laboratory and on the NASA DC8, the SAW hygrometer has demonstrated more than an order of magnitude faster response than commercial chilled-mirror hygrometers, while showing comparable accuracy under steady-state conditions. Current development efforts are directed toward miniaturization and optimization of the microhygrometer electronics for flight validation experiments on a small radiosonde balloon.

This paper addresses the critical need to incorporate realistic models of the air supply sub-system in fuel cell system performance analysis. The paper first presents the dominant performance issues involved with the air supply operation in the fuel cell system. The report then goes on to propose a methodology for an air supply model that addresses many of the performance issues. Most importantly, a model is needed with a defined set of performance criteria and data input format, one that can accommodate multiple air supply configurations, and one that realistically and accurately simulates the air supply operation and its effect on the system power and efficiency. The paper concludes that it is possible to compare alternative air supply components under the constraint of maximizing the instantaneous net fuel cell system efficiency for a dynamic vehicle driving cycle under various ambient conditions.

Engine manufacturers have explored many routes to reducing the emissions of harmful pollutants and conserving energy resources, including development of after treatment systems to reduce the concentration of pollutants in the engine exhaust, using alternative fuels, and using alternative fuels with after treatment systems. Liquefied petroleum gas (LPG) is one alternative fuel in use and this paper will discuss emission measurements for several LPG vehicles. Regulated emissions were measured for five school buses, one box truck, and two small buses over a cold start Urban Dynamometer Driving Schedule (CS_UDDS), the Urban Dynamometer Driving Schedule (UDDS), and the Central Business District (CBD) cycle. In general, there were no significant differences in the gas phase emissions between the UDDS and the CBD test cycles. For the CS-UDDS cycle the total hydrocarbons and non-methane hydrocarbon emissions are higher than they are from the UDDS cycle.

This paper presents a driver assistance system designed to minimize the effect of driver reaction time on lane and speed maintenance operations. Nearly-instantaneous correcting actions are provided through a hierarchical arrangement of behaviors, by avoiding the time lag associated with deliberative or planning steps found in many control algorithms. Concepts originating in the field of robotics, including artificial potential fields and behavior-based systems, are interpreted for application to automotive control, where vehicle dynamics places considerable practical constraints on implementation. Ideas found in the study of emergent behavior in nature provide continuous, non-stepwise control signals, suitable for additive corrective inputs at highway velocities. This approach is effective for a substantial subset of road automobiles operating over a variety of speeds.

With stringent emission norms coming to place for automotive/Off-highway vehicles and locomotives in the next few years, there is a lot of research going on to minimize emission and SFC. For this purpose a lot of areas are explored for significant benefits including the intake and exhaust paths, combustion, after-treatment devices. Of these the intake system, which supplies the cylinder with the required amount of air at required pressure and temperature is one of the critical systems. Various components are modified and added to the intake system to either get the required pressure and temperature (ex: intercoolers and compressor) or to get the required composition (EGR circuit) for emission reduction. Addition or modification of these components increases the pressure loss in the intake system, which affects the airflow rate.

The potential for improving the efficiency of a heavy duty turbocharged diesel engine by closed loop Air-Fuel Ratio (AFR) management has been evaluated. Testing conducted on a 12 liter diesel engine, and subsequent data evaluation, has established the feasibility of controlling the performance through electronic control of air management hardware. Furthermore, the feasibility of using direct in-cylinder pressure measurement for control feedback has been established. A compact and robust fiber optics sensor for measuring real time in-cylinder pressure has been demonstrated on a test engine. A preferred method for reducing the cylinder pressure data for control feedback has been established for continued development.

The first concept and early experiments of a mechanical counter pressure (MCP) spacesuit were published by Webb in the late 1960's. MCP provides an alternative approach to the conventional full pressure suit that bears some significant advantages, such as increased mobility, dexterity, and tactility. The presented ongoing research provides a thorough investigation of the physiological effect of mechanical counter pressure applied onto the human skin. In this study, we investigated local microcirculatory effects produced with negative and positive ambient pressure on the lower body as a preliminary study for a lower body garment. The data indicates that the positive pressure was less tolerable than negative pressure. Lower body negative and positive pressure cause various responses in skin blood flow due to not only blood shifts but also direct exposure to pressure differentials.

The first concept and early experiments of a Mechanical Counter Pressure (MCP) spacesuit were published by Webb in the late 1960's. MCP provides an alternative approach to the conventional full pressure suit that bears some significant advantages, such as increased mobility, dexterity, and tactility. The presented ongoing research provides a thorough investigation of the physiological effect of mechanical counter pressure applied onto the human skin. In this study, we investigated local microcirculatory effects produced with negative and positive ambient pressure on a bare arm, and with a MCP glove and sleeve. The data indicates that the MCP glove and sleeve effectively counteracted the adverse effects of negative environmental pressure.

The first concept and early experiments of a Mechanical Counter Pressure (MCP) spacesuit were published by Webb in the late 1960’s. MCP provides an alternative approach to the conventional full pressure suit that bears some potential advantages, such as increased mobility, dexterity, and tactility. The presented ongoing research provides a thorough investigation of the physiological effect of mechanical counter pressure applied onto the human skin. Preliminary results are presented from glovebox testing with an existing MCP glove. The data indicates that properly applied mechanical counter pressure greatly reduces the effect of low-pressure exposure, which makes MCP a viable technology for spacesuit gloves.

Goods movement and port related activities are a significant source of emissions in many large urban areas. Electrification of diesel cargo handling equipment is one method of reducing community exposure to these emissions, that also provides the potential for reducing greenhouse gas emissions. This study evaluated the performance of several pieces of zero emission cargo transfer equipment for a demonstration conducted at two terminal locations at the Port of Long Beach (POLB). This included the data logging of three battery-electric top handlers and one battery-electric yard tractor, as well as two baseline diesel top handlers and one diesel yard tractor. The battery-electric equipment typically operated about 5 hours per day, while using between 34 to 50% of the battery pack state of charge (SOC). In general, the battery-electric equipment was able to provide comparable hours of operation to the diesel equipment over a typical 8-hour shift.

This paper is written to provide information on the fuel efficiency, emissions and energy cost of vehicles ranging from a pure electric (ZEV) to gasoline hybrid vehicles with electric range varying from 30 mi (50km) to 100 mi (160km). The Federal government s PNGV and CARB s ZEV have different goals, this paper explores some possibilities for hybrid-electric vehicle designs to meet both goals with existing technologies and batteries. The SAE/CARB testing procedures for determining energy and emission performance for EV and HEV and CARB s HEV ruling for ZEV credit are also critically evaluated. This paper intends to clarify some confusion over the comparison, discussion and design of electric- hybrid- and conventional- vehicles as well.

The question of whether or not direct-hydrogen fuel cell systems in automotive applications should be used in load following or load leveled (battery hybrid) configurations is addressed. Both qualitative and quantitative analyses are performed to determine the potential strengths and weaknesses of each option. It is determined that the amount of energy that can be recovered through regenerative braking has a strong impact on the relative fuel economy of load following versus load leveled operation. Further, it is demonstrated that driving cycles with lower power requirements will show an improvement in vehicle fuel economy from hybridization while those with higher power requirements will not. Finally it is acknowledged that the practical considerations of cost and volume must also weigh heavily into the decision between the two configurations.

The measurement of SO2 levels in vehicle exhaust can provide important information in understanding the relative contribution of sulfur and sulfate from fuel vs. oil source to PM. For this study, a differential optical absorption spectrometer (DOAS) that can measure SO2 down to 20 ppbV in real-time was built and evaluated. The DOAS consisted of an extractive sampling train, a cylindrical sampling cell with a single-path design to minimize cell volume, a spectrometer, and a deuterium lamp light source with a UVC range of ∼200-230 nanometer (nm). Laboratory tests showed detection limits were approximately in the range of 12 to 15 ppbV and showed good linearity over SO2 concentration ranges of 20 to 953 ppbV. Interference tests showed some interference by NO and by NH3, at levels of 300 ppmV and 16.6 ppmV, respectively.

Drivers continually require steering performance improvement, particularly in the area of feedback from the road. In this study, we develop a new electrically-assisted steering logic by 1) analyzing existing steering systems to determine key factors, 2) modeling an ideal steering system from which to obtain a desirable driver torque, 3) developing a rack force observer to faithfully represent road information and 4) building a feedback compensator to track the tuned torque. In general, the estimator uses the driver torque, assist torque and other steering system signals. However, the friction of the steering system is difficult to estimate accurately. At high speed, where steering feeling is very important, greater friction results in increased error. In order to solve this problem, we design two estimators generated from a vehicle model and a steering system model. The observer that uses two estimators can reflect various operating conditions by using the strengths of each method.

This study continues previous experimental studies which review the characteristics of the side impact exposure to the human head. We conducted a series of two experiments. The first series included four sequential impacts which were performed on a single embalmed specimen. This series of impacts showed a good correspondence between peak head acceleration and HIC and confirmed the adequacy of instrument placement and data analysis. The second series studied five impacts performed on individual unembalmed cadavers. The results suggest that side impacts produced pressure gradients in the brain. These superimposed gradients were proportional to the magnitudes of the head acceleration components. The largest component was found to be in the direction of impact and produced positive pressures near the impact and negative pressures opposite the impact. We found that a pressure limiting mechanism acted on the contra-coup side of the brain.