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This paper presents an analysis of 67 neck injuries incurred in diving and sliding accidents in swimming pools. The accidents were investigated to establish the appropriate medical and mechanical factors involved. A mathematical model was developed to allow the prediction of the trajectory and velocity of the subjects prior to their injury. Nine of the accidents were selected for real life simulation. The simulation included the selection of test subjects of similar physical build to the accident victims who then performed the maneuvers leading to the injury, but in deeper water. High speed movies (200 frames per second) were taken, above and below the water, to measure the motion. A frame by frame analysis provided data to determine the trajectory and velocity profiles of the test subject. The maneuvers studied included diving from the pool edge, diving from various board types and sliding down various sliding board configurations.

This paper illustrates the design of a linear step actuator. The unit develops 1.1 newtons of axial thrust in .1 mm steps for a total travel of 13.2 mm.

Designing a climate control system for a new highway tractor is a multi-phase project. This paper outlines the process and the various challenges each step presented, starting with outside temperatures and going through zone controls, register placement, system design, heat transfer components and testing. From the different steps emerged a multiple heater/evaporator system with performance superior to existing designs. The system has three sets of controls which provide a means of regulating the temperature in the driver, passenger and sleeper areas of the cab. The paper also describes the various packaging concepts investigated, how the choice of vacuum as a power medium for the controls was selected and briefly outlines the testing conducted on the new design.

The limitations of conventional solenoids will be explained and reasons given to show that as they are made more powerful their speed of operation decreases. HELENOID actuators are capable of armature travel times in less than one millisec irrespective of preloads or masses, despite the larger size and power required as the duty increases. The relationships between eddy currents and flux penetration; materials and flux leakage; inductance and power supply are illustrated, together with the way they are all interconnected and varying with time, requiring a comprehensive computer program to design for optimum performance.

From 1973 to 1977 a series of laboratory tests involving almost 3000 people were conducted to determine the factors that contribute to the thermal comfort of automobile passengers while using air conditioning under summer heat loads. Four studies will be reviewed. In the first study, 2200 subjects were exposed for 45 min. to an environment of 110°F/40% in a 1973 Ford Vehicle buck for the purpose of evaluating the effects of the register size, the air flow rate and the discharge air temperature on comfort. The results showed that while the register size does not affect the time to reach a comfortable condition, the time to reach comfort in the front seat varies from 4 minutes with an air flow of 400 cfm (50°F discharge air at 10 minutes) to 18 minutes with 150 cfm (60°F discharge air); in the rear seat, the corresponding times were 8.5 and 39 minutes.

This paper contains the methodological and empirical results of an investigation into the energy consumption characteristics of a GM manufacturing plant. In examining the energy portfolios of a particular plant, two statements can be made concerning the energy sources. Their level of utilization should be: a) directly correlated, in some degree, to endogenous variables such as direct labor hours, production volume, degree days, etc., and b) impacted significantly by any “visible” change in the composition of the technologies, the physical aspects of the work environment, and the labor force. The question to be answered is “which variables are directly related to energy consumption?” In answer to that query, a model constructed to account for future energy is usage, by source, within the manufacturing environment. Data was collected from eight plants for a twenty-eight month time period.

An examination of some design considerations of gas turbine automobile engines is made including an overview of the unsolved problems. Emphasis is placed on the design and manufacturing aspects. Performance penalties due to size effects are discussed. The gains in cycle thermal efficiency with increasing peak temperatures are examined in view of these penalties. A cursory investigation of thermal efficiency is performed on a 75 horsepower and a 150 horsepower gas turbine. This was done considering both current and advanced design and manufacturing technology with regard to rotor clearances and blade thicknesses. Design and manufacturing limits used in defining the penalties in engines with advanced technology are qualified. This investigation indicates an improvement of about 15 percent in thermal efficiency due to increasing the peak cycle temperature from 1850°F to 2500°F for a gas turbine engine suitable for an automobile but requiring advanced technology.

The anatomy of the major structures of the neck are presented including the anterior throat structures and the components of the cervical spine and associated structures. Basic neck movements and generalized muscle actions are described. Anatomical relationships of the bones, ligaments, muscles and joints of the cervical spine are emphasized as a foundation for a clear understanding of the structural elements involved in neck fractures and dislocations.

Detroit Diesel Allison Division of General Motors Corporation has been conducting a field evaluation program on the 300 hp GT-404-3 and the 390 hp GT-505-3 Industrial Gas Turbine Engines over the time period from late 1974 until late 1977. This paper describes the overall program plan which involved installations in trucks, coaches, marine and industrial applications and the field experience which has been accumulated to date. Emphasis will be placed on operator reaction, environmental effects, performance and field revealed problems. Two particular applications will be explored in considerable detail; bulk hauling trucks with self unloading capabilities and the Greyhound inter-city coach operation with gas turbine power and automatic transmissions.

An analysis is presented for the quantitative evaluation of spark ignition engine control parameters (spark advance, air-to-fuel ratio, exhaust gas recirculation) for optimal fuel economy, constrained emission levels and tradeoffs. Emphasis is placed on the procedures and techniques adopted for the off-line approach using steady state mapping dynamometer data of conventional engines in production. The analysis structure is composed primarily of existing documented tools, in particular, a) vehicle simulation programs, b) FTP-urban and highway drive cycle schedule, c) multiple regression techniques, and d) dynamic programming procedures. Analytical methods are evaluated along with illustrative examples, and discussions are presented on their sensitivities. Applications of engine control parameter optimizations are also illustrated with reference to two engine (one eight and one four cylinder) data bases. Major factors are discussed.

Seven mathematical models for the interaction of a pneumatic tire with a roadway are analyzed. This study involves a single-wheel trailer, and it is assumed that the tire and roadway touch each other at only one point. Results of numerical solutions of equations of motion are given in graphical form for the first four models. Significant disparities are found among the predictions of the various theories. This work is intended to form the basis for experiments to be performed to determine which model, if any, is, in fact, valid.

A procedure has been developed for establishing optimum engine performance, in terms of fuel economy and exhaust emission constraints, as a function of spark advance, exhaust gas recirculation and air-to-fuel ratio. The salient features of the procedure are: (i) it is based on mathematical engine models that have been validated over a driving cycle on an engine dynamometer, (ii) it is based on solving a nonlinear programming problem with equality and inequality constraints, and (iii) the results of the optimization are used to develop control calibrations that can be implemented on a vehicle. This paper describes the procedure to determine optimal calibrations for a fuel injected spark ignition engine under warmed-up operating conditions. Validation of these results on an actual vehicle has yet to be demonstrated.

An automated engine dynamometer test procedure is developed and mathematical models for the main engine control variables are derived from the resulting data base. The new procedure involves sequential testing at many speed/load conditions for various combinations of air fuel ratio, spark timing and exhaust gas recirculation. The total testing time required for generating the data base of more than 2000 test points is less than twelve hours. An independent transient speed/load test is also conducted for the purpose of validating the engine models. The measured and model predicted data are compared for this test which corresponds to a segment of the EPA urban schedule.

A seven-degrees-of-freedom model of an articulated recreational vehicle is described and used to determine the relative significance of parameters and of degrees of freedom that affect lateral stability. Thirty-five parameters are used to describe tire-road interactions, roll freedom, suspension systems, geometry, mass distribution, the hitch, the drawbar, and the forward speed. Critical speeds associated with different systems are calculated. Comparisons of these critical speeds lead to conclusions important to the design and safe operation of articulated recreational vehicles.

The steady-state turning behavior of vehicles pulling trailers is formulated in a simplified manner using the concept of a handling diagram. The formulation assumes small slip angles but admits a non-linear relationship between the slip angle and side force of the tires.

The effect on trailer stability of hitchpoint lateral stiffness and damping is examined by means of a simplified model. The model used in the stability analysis is a one degree of freedom nonholonomic dynamical system and yields a third order linear differential equation. Trailer stability criteria are developed, and stability charts are presented which depict the stability criteria in terms of nondimensional parameters. The analysis shows that increasing hitchpoint lateral stiffness does not improve trailer stability whereas increasing hitchpoint lateral damping is much more important to trailer stability. In addition, the importance of hitchpoint loading to trailer stability is shown.

The paper presents a fuel modulation attenuation model for single point closed-loop fuel metering systems. The model calculates the attenuation of a metered air-fuel perturbation and the time delay in the transport of the perturbed signal from the metering point through the engine to the exhaust system as functions of the modulation frequency, engine RPM, intake manifold vacuum, and exhaust gas recirculation. Results are shown for a V-8 engine with sine wave, triangular wave and square wave modulations. It is found that the attenuation for the triangular wave is the highest and that for the square wave is the smallest. It is also found that in general the attenuation increases with increasing modulation frequency and increasing EGR, but decreases with increasing RPM. The model can be extended to study the attenuation and transport delay of other engines and wave forms.

Recently, Taylor and Kane have drawn attention to the potentially destabilizing influence of drawbar flexibility on the stability of articulated vehicles. They assumed that roll freedom does not affect stability. Moncarz, however, used a model that did not include drawbar flexibility and concluded that roll has a significant influence. Two questions are addressed in this paper. How do roll steer and drawbar flexibility affect stability? Are these effects independent? Comparisons of the stability predictions from four different articulated vehicle models lead to the conclusions that both roll steer and drawbar flexibility can have significant effects on stability and that these effects are not independent.

The automotive industry is in the process of reducing vehicle weight to meet the Federal mandate for gas mileage. Lightweight sheet molding compound (SMC) can make a significant contribution. However, to be competitive with other improved lightweight materials, several changes in the standard compression molding process must take place. This paper will present the current work in sheet molding compound processes at General Motors Manufacturing Development. It covers the processes of programmable force velocity control, molded coating, and mold heat transfer analysis; and the concepts on compounding of SMC sheet and of a multi-station, high productivity compression molding line.

Advance in technology and the necessity for conservation of energy have forced the design engineer to look closer to plastic materials in order to save weight of cars. The situation in Europe, and in particular the chances for fiber glass reinforced polyester are explained in detail.