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A 10 KWe dual-mode space power system concept has been identified which is based on INEL's Small Externally-fueled Heat Pipe Thermionic Reactor (SEHPTR) concept. This power system will enhance user capabilities by providing reliable electric power and by providing two propulsion systems; electric power for an arc-jet electric propulsion system and direct thrust by heating hydrogen propellant inside the reactor. The low thrust electric thrusters allow efficient station keeping and long-term maneuvering. The direct thrust capability can provide tens of pounds of thrust at a specific impulse of around 730 seconds for maneuvers that must be performed more rapidly. The direct thrust allows the nuclear power system to move a payload from Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO) in less than one month using approximately half the propellant of a cryogenic chemical stage.

Increased torque values passing from engine to transmission have, increasingly become a problem regarding shaft misalignment. Engineers are restricted with regard to applying ISO standards when investigating bearing life cycles as they tend only to cover normal [radial thrust] load conditions. Depending on the application, the need has arisen for numerical models to determine reduction in normal life cycles due to abnormal running conditions. The Simulia Finite Element package Abaqus v6.7 provides trends in the deformations, contact pressures and their respective distribution. It was found the most efficient profile, with regards to a uniform contact pressure, under both radial and misaligned conditions is the toroidal profile.

Three recent developments suggest cost-beneficial approaches to communications for Advanced Traveler Information Systems (ATIS) : 1) the use of FM subcarrier for efficient paging-type (digital) one-way broadcast, along with the upcoming introduction of Radio Data System (RDS) vehicle receivers, 2) the rapidly growing use of RF “tags” for automatic tolling, which have recently been upgraded for discrete zone two-way communication, and 3) the “signal processing gain” and “demand access” capability of spread-spectrum-type coding, which together make event-driven communications more feasible and cost-beneficial. An architecture concept exploiting these thrusts is outlined in terms of a “baseline” and a higher level ATIS. The baseline emphasizes basic traffic exception and safety messages and supports higher level (optional) services such as navigators and invehicle route guidance computers.

The objective of this study is to compare the risk of injury to pedestrians involved in vehicle-pedestrian impacts as predicted by two different types of risk assessment tools: the pedestrian subsystem impactors recommended by the European Enhanced Vehicle-Safety Committee (EEVC) and post-mortem human surrogates (PMHS). Seven replicate full-scale vehicle-pedestrian impact tests were performed with PMHS and a mid-sized sedan travelling at 40 km/h. The PMHS were instrumented with six-degree-of-freedom sensor cubes and sensor data were transformed and translated to predict impact kinematics at the head center of gravity, proximal tibiae, and knee joints. Single EEVC WG 17/EuroNCAP adult headform, upper legform and lower legform impactor tests of the same vehicle were selected for comparison based on the proximity of their impact locations to that of the PMHS.

This paper examines the performance of different active control strategies for improving lateral stability of car-trailer systems using numerical simulations. For car-trailer systems, three typical unstable motion modes, including trailer swing, jack-knifing and roll-over, have been identified. These unstable motion modes represent potentially hazardous situations. The effects of passive mechanical vehicle parameters on the stability of car-trailer systems have been well addressed. For a given car-trailer system, some of these passive parameters, e.g., the center of gravity of the trailer, are greatly varied under different operating conditions. Thus, lateral stability cannot be guaranteed by selecting a specific passive parameter set. To address this problem, various active control techniques have been proposed to improve handling and stability of car-trailer systems. Feasible control methods involve active trailer steering control (ATSC) and active trailer braking (ATB).

A study has been conducted as an initial step in determining the differences observed between the motions of a living human impact sled test subject and a dummy test subject. The mechanism which is proposed for accomplishing this is the HSRI Two-Dimensional Mathematical Crash Victim Simulator. A series of measurements were taken on human test subjects, including classical and nonclassical anthropometric measurements, range of motion measurements for the joints, and maximum foot force measurements. A series of mathematical expressions has been used to predict body segment weight, centers of gravity, and moments of inertia using the results of the various body measurements. It was then possible to prepare a data set for use with the mathematical model.

This research compares vehicle dynamic simulations in PC-Crash 8.2 to data recorded during instrumented handling tests conducted by Mechanical Systems Analysis Incorporated (MSAI). The handling tests, which were used to examine rollover stability in a 1998 and a 1999 Ford Explorer, involve rapid steering inputs at speeds between 30 mph [48.3 kph] and 60 mph 96.6 [kph]. Vehicle weight, center of gravity (c.g) position, suspension stiffness parameters, tire parameters, steering angle, and vehicle speed data provided by MSAI were used as input for the PC-Crash model. Lateral acceleration, roll angle, roll rate, and yaw rate vehicle response from PC-Crash were compared to the MSAI sensor data. The authors modeled 26 handling tests. PC-Crash appeared to be a reasonable tool for modeling gross vehicle response. In addition, PC-Crash correctly predicted whether or not the test vehicle would experience rollover instability in a majority of the cases.

As aircraft programs currently ramp up, productivity of assembly processes needs to be improved while keeping quality, reliability and manufacturing cost requirements. Efficiency of the drilling process still remains an issue particularly in the case of CFRP/metal stacks: hot and long metallic chips are difficult to remove and often damage the surface of CFRP holes. Low frequency axial vibration drilling has been proposed to solve this issue. This innovative drilling process allows breaking up the metallic chips in such a way that jamming is avoided. This paper presents a case of CFRP/Ti6Al4V drilling on a CNC machine where productivity must be increased. A comparison is made between the current regular process and the MITIS drilling process. First the analysis and comparison method is presented. The current process is analyzed and its limits are highlighted. Then the vibration process is implemented and its performances are studied.

The moments of inertia, in yaw, pitch, and roll, as well as the center of gravity height are necessary to successfully model the 3D dynamic behavior of vehicles before, during and after collision. A number of vehicle parameter estimation techniques have been developed and are currently in use in North America and Europe. Many parameters have been measured by NHTSA and others. The estimation techniques are compared to the available measured values, and recommendations are made for best estimating the parameters when measured values are not available. The sensitivity of 3D vehicle collision dynamics and trajectory simulation to variance in the moment of inertia is demonstrated.

Three lift/propulsion concepts for a V/STOL supersonic combat aircraft have been compared. The intention was to show the effect of the propulsion system on aircraft weight and size, performance, and life cycle costs for: 1 Vectored thrust with Plenum Chamber Burning (bypass air augmentation) 2 Lift engines and a lift/cruise reheated turbofan 3 A reheated lift/cruise turbofan with a remote augmented lift system (RALS) For a postulated deck-launched intercept mission, the vectored thrust propulsion system with Plenum Chamber Burning gives the smallest and cheapest aircraft having the required performance. In addition, for a given take-off ground run the vectored thrust powered aircraft has the longest fighter escort mission radius.

To date, the most commonly used rollover test device has been the rollover dolly described in the SAE J2114 recommended practice, which is commonly referred to as the “208 rollover dolly.” However, for a number of reasons, the rollover dolly has never been accepted as a standard for rollover testing. One of the primary limitations of the rollover dolly has been the controllability of the first roof-to-ground impact. A new rollover test device, known as the Controlled Rollover Impact System (CRIS), was presented at the SAE Congress in March 2001. This device allows the roll, pitch, and yaw angles, roll rate, translational velocity, and drop height of the vehicle to be specified for the first roof-to-ground impact. One objective of the current study was to compare the vehicle dynamics produced by each test device using an Econoline-350 van as the test vehicle.

This paper describes a comprehensive model of piston skirt lubrication, developed for use in conjunction with piston secondary dynamic analysis, to accurately characterize the effects of the skirt-cylinder oil film on piston motions. The model represents both hydrodynamic and boundary lubrication modes and applies an asperity contact pressure when surfaces are in close proximity with each other. In addition to skirt dimensions and surface roughness properties, the circumferential extent of lubrication, an arbitrary skirt profile and bore distortion are specifiable inputs to the model. The model is also extended to represent the oil starvation at the cylinder end of the skirt by allowing the axial extent of lubrication on the skirt surface to vary circumferentially and with time to satisfy continuity of oil.

This paper deals with the performance prediction of one member of a family of thrust producing intermittent combustion engines, namely the pulsejet. The first part is concerned with formulating basic concepts of how pulsejets work. It describes the different methods of providing intake valving action and derives theory to demonstrate the operation of the aerodynamic tuned valve in particular. The second part is concerned with devising a computer program to simulate and predict the performance of valveless pulsejets. The program is based on the method of characteristics for calculating unsteady gas flow. Theories and techniques are given to handle the major problems associated with this application. These problems include the large range of discontinuous temperature and entropy, flow through an area discontinuity and the calculation of mean thrust.

A class of heavy truck vehicles, characterized primarily by high centers of gravity, was studied using analysis and computer simulation to identify and understand the relationship between directional and roll stability of such vehicles during steady turning maneuvers. Findings of the computer-based study suggest: (1) directional instability (yaw divergence) is possible for such vehicles during steady turning while operating at elevated speeds on horizontal road surfaces, (2) yaw divergence will lead to rollover in the absence of corrective steering action and/or reduced speed, and (3) the primary mechanism responsible for precipitating yaw divergent behavior in such vehicles is the nonlinear sensitivity of truck tire cornering stiffness to vertical load acting in combination with typical heavy truck fore/aft roll stiffness distributions. In addition, the influences of roadway superelevation and driver steering control as contributors to vehicle stabilization are examined and discussed.

This paper presents a method for optimization design of an engine mounting system subjected to some constraints. The engine center of gravity, the mount stiffness rates, the mount locations and/or their orientations with respect to the vehicle can be chosen as design variables, but some of them are given in advance or have limitations because of the packaging constraints on the mount locations, as well as the individual mount rate ratio limitations imposed by manufacturability. A computer program, called DynaMount, has been developed that identifies the optimum design variables for the engine mounting system, including decoupling mode, natural frequency placement, etc.. The degree of decoupling achieved is quantified by kinetic energy distributions calculated for each of the modes. Several application examples are presented to illustrate the validity of this method and the computer program.

Because of an increasing popularity of the SUV and Light Truck with an elevated center of gravity, the rollover propensity is higher than before. This paper proposes a method to detect and prevent an impending rollover of the vehicle using Electronic Stability Control(ESC). The Rollover Prevention(ROP) function determines a rollover critical situations based on the rollover propensity index and generates a proper activation through a brake and engine intervention. The rollover propensity index is calculated from the relative distance of the trajectory to the threshold on the phase plane of roll-angle and roll-rate. The threshold on the phase plane is deduced from the conservation of energy in the roll model. For the detection and activation of continuous rollover phenomena, we use the TTL concept that presents a gradually increasing rollover propensity. The proposed algorithm in this paper is shown to be effective in mitigating a rollover through the simulation and vehicle test.

This paper outlines what a large company is doing on a corporate staff basis to help combat Product Liability problems. Eaton Corporation is multi-national and serves a variety of markets. The extensive and complex line of products dictates the need for a well organized, corporate Product Assurance Program. The program is made up of five thrusts: 1) Corporate Policy, 2) Guidelines, 3) Divisional Committees, 4) Surveys and 5) Training. Utilizing a product development project, the implementation of several elements of Product Quality Assurance are explained. The program was designed for flexibility and emphasizes the chairman's motto to “DO IT RIGHT THE FIRST TIME, EVERY TIME.”

A decentralized, multivariable controls methodology is being developed for the functional integration of a fighter's aerodynamic controls with those of its propulsion system (inlet, engine, and thrust vectoring/reversing nozzle). Integrated controls account for, and take advantage of the significant cross-coupling between these system elements. A high-fidelity, six-degrees-of-freedom (6 DOF) aircraft simulation has been developed, incorporating advanced tactical fighter features such as variable cycle engines, variable geometry inlets, 2D-CD TV/TR nozzles, canards and a propulsive lift concept. A comprehensive evaluation test plan, including a piloted simulation, has been developed to validate this integrated-controls design methodology. Preliminary results show significant benefits of integrated control in terms of enhanced aircraft maneuverability, precise flight path control, reduced pilot workload, and fault tolerant system design.

The reproduction of the vehicle motion is a crucial element of accident reconstruction. Apart from the position of the center of gravity in an inertial coordinate system, the vehicle heading plays an important role. The heading is the sum of the yaw angle and the vehicle body side slip angle. In standard vehicles, the yaw angle can be determined using the yaw rate sensor and the wheel speeds. However, the yaw rate sensor is often subject to temperature drift. The wheel speed signals are forged at low speeds or due to slip. These errors result in significant deviations of reconstructed and real vehicle heading. Therefore, an intelligent combination of these signals is required. This paper describes a fuzzy system which is capable to increase the accuracy of yaw angle calculation by means of fuzzy logic. Before the data is applied to the fuzzy system, it is preprocessed to ensure the accuracy of the fuzzy system inputs.

This paper describes a numerical method for solving three-dimensional incompressible flow problems and its use in predicting the aerodynamic characteristics of V/STOL aircraft. Arbitrary configuration and inlet geometry, fan inflow distributions, thrust vectoring, jet entrainment, angles of yaw, and flight speeds from hover through transition can be treated. Potential-flow solutions are obtained with the method of influence coefficients, using source and doublet panels distributed on the boundary surfaces. The results include pressure distributions, lift, induced drag and side force, and moments. Theoretical solutions are presented for clean lifting wings and for a NASA fan-in-wing model. Comparisons with the experimental NASA data demonstrate the validity of the approach and uncover the importance of viscous effects, fan inflow distribution, and jet entrainment.