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The MX-2 neutral buoyancy space suit analogue has been designed and developed at the University of Maryland to facilitate analysis of space suit components and assessment of the benefits of advanced space suit technologies, The MX-2 replicates the salient features of microgravity pressure suits, including the induced joint torques, visual, auditory and thermal environments, and microgravity through the use of neutral buoyancy simulation. In this paper, design upgrades and recent operations of the suit are outlined, including many experiments and tests of advanced space suit technologies, This paper focuses on the work done using the MX-2 to implement and investigate various advanced controls and displays within the suit, to enhance crewmember situational awareness and effectiveness, and enable human-robotic interaction.

Design optimization is an important engineering design activity. Performing design optimization in the presence of uncertainty has been an active area of research. The approaches used require modeling the random variables using precise probability distributions or representing uncertain quantities as fuzzy sets. This work, however, considers problems in which the random variables are described with imprecise probability distributions, which are highly relevant when there is limited information about the distribution of a random variable. In particular, this paper formulates the imprecise probability design optimization problem and presents an approach for solving it. We present examples for illustrating the approach.

The thermal comfort inside automotive cabin has been extensively studied for decades. Traditional CFD models provide accurate simulation results of the air temperature distributions inside cabins but at a relatively high computation cost. In order to reduce the computational cost while still providing reasonable accuracy in simulating the air temperature profile inside a mid-sized sedan cabin, this paper introduces a new simulation tool that utilizes a proper orthogonal decomposition (POD) method. The POD method, an interpolation technique, requires only one set of multiple CFD simulations to produce a set of “snapshots”. Later, any simulations that require CFD runs to solve algorithm equation sets can be simplified by using interpolation between the snapshots provided that the geometry of the cabin keeps the same. As a result, the computation time can be reduced to only a few minutes.

A newly designed and built Mobile Tire Testing Machine (MTTM) is described that has features for large and continuously variable camber and steering angles with minimum tire scrub. This equipment was used to examine tire properties for six passenger car tires. Of special interest were the tire characteristics at combinations of high slip and camber angle. It was found that camber stiffness decreases with increasing slip angle when the slip and camber angles are both positive, and at limit conditions in slip angle, cambering a tire has little effect on the lateral side force produced. When the slip angle is negative, and the camber angle is positive, preliminary data shows that a greater lateral force is produced when compared to operating at limit conditions in slip angle alone.

The Pride of Maryland is a single seat solar powered trans-continental race car designed and built by engineering students at the University of Maryland. The car competed in G.M. Sunrayce USA, placing third, and has gone on to compete in the World Solar Challenge. This paper outlines the three general areas of design and development for the solar vehicle: aerodynamic, electrical, and mechanical. An exercise in high efficiency, the Pride of Maryland has been extremely successful as both a race car and as an educational tool for training student engineers in “real world” problems.

Smoke detection experiments were conducted in the Microgravity Science Glovebox (MSG) on the International Space Station (ISS) during Expedition 15 in an experiment entitled Smoke Aerosol Measurement Experiment (SAME). The preliminary results from these experiments are presented. In order to simulate detection of a prefire overheated-material event, samples of five different materials were heated to temperatures below the ignition point. The smoke generation conditions were controlled to provide repeatable sample surface temperatures and air flow conditions. The smoke properties were measured using particulate aerosol diagnostics that measure different moments of the size distribution. These statistics were combined to determine the count mean diameter which can be used to describe the overall smoke distribution.

Task-based intensity and fatigue metrics were developed and applied to neutral buoyancy simulations of extravehicular activities (EVA). Surface electromyographic (EMG) signals from hand flexor and extensor musculature were recorded during neutral buoyancy EVA simulations at Marshall Space Flgiht Center (MSFC) in August-September 1996. A task intensity index, based on the cumulative histogram of EMG amplitude, was developed and used to determine relative physical difficulty of handgripping, knob turning, bolt manipulation, and j-hook release tasks. A fatigue index, based on the task intensity metric and task duration, was used to provide a measure of task-related fatigue.

The Army continues to improve its Reliability-based Design Optimization (RBDO) process, expanding from component optimization to system optimization. We are using the massively parallel computing power of the Department of Defense (DoD) High Performance Computing (HPC) systems to simultaneously optimize multiple components which interact with each other in a mechanical system. Specifically, we have a subsystem of a military ground vehicle, consisting of more than four components and are simultaneously optimizing five components of that subsystem using RBDO methods. We do not simply optimize one component at a time, sequentially, and iterate until convergence. We actually simultaneously optimize all components together. This can be done efficiently using the parallel computing environment. We will discuss the results of this optimization, and the advantages and disadvantages of using HPC systems for this work.

The University of Maryland team converted a model year 2000 Chevrolet Suburban to an ethanol-fueled hybrid-electric vehicle (HEV) and tied for first place overall in the 2000 FutureTruck competition. Competition goals include a two-thirds reduction of greenhouse gas (GHG) emissions, a reduction of exhaust emissions to meet California ultra-low emissions vehicle (ULEV) Tier II standards, and an increase in fuel economy. These goals must be met without compromising the performance, amenities, safety, or ease of manufacture of the stock Suburban. The University of Maryland FutureTruck, Proteus, addresses the competition goals with a powertrain consisting of a General Motors 3.8-L V6 engine, a 75-kW (100 hp) SatCon electric motor, and a 336-V battery pack. Additionally, Proteus incorporates several emissions-reducing and energy-saving modifications; an advanced control strategy that is implemented through use of an on-board computer and an innovative hybrid-electric drive train.

AMBER (Active Magnetic Bearing Evaluation Routine) is a computer algorithm developed for the University of Maryland pancake magnetic bearing, which supports and controls a flywheel in a kinetic energy storage system. Because of the gap growth due to centrifugal forces at high speed, the bearing axial load capability degrades and the axial characteristics become critical in the bearing design. AMBER applies magnetic circuit theory, magnetic material saturation curves, coenergy theory, and finite permeance-based elements to solve the air gap flux density and coenergy over a series of incremental axial displacements. Differentiation of the coenergy of the magnetic field yields axial force and stiffness characteristics. An axial test machine is constructed to conduct experiments to verify the flux distribution and axial forces predicted by the model. User interaction with AMBER allows modification of the bearing geometry and composition to optimize future prototypes.

Thermal destruction of municipal solid waste (MSW) can provide an effective solution for the volume reduction of waste and energy recovery. Effective thermal destruction of waste depends on several factors including the operating temperature, excess air, heating rate, as well as physical and chemical properties, feed size and moisture content of the waste. Different processes associated with thermal destruction of waste have been identified. Prominent thermal destruction processes evaluated in this study include: pyrolysis, gasification and combustion. The kinetics and thermochemical analysis of these processes has been carried out. It is found that the maximum operating temperature and heating rate to which the waste is subjected determines the operational regime of a particular thermal destruction system. The thermal destruction systems evaluated are: rotary kiln, mass burn incinerators, fluidized beds, electrically heated reactors and plasma arc reactors.

Chemically enhanced autoignition in a spark-ignited engine with a special design of piston geometry has been observed experimentally, in which the engine would operate stably without a spark, once it is started by spark ignition. Under this operation mode, the engine provides lower pollutant emissions including NOx. In this process, the intermediate species left from the previous cycle play a key role in the low temperature autoignition. The objective of this study is to determine the effect of some important radical and intermediate species, such as HO2, OH, and H2O2, on autoignition by a numerical modeling approach using a detailed chemical kinetic mechanism. The fuel studied is hydrogen. The effect of added HO2, OH and H2O2 on the characteristics of the autoignition of H2-air mixture is investigated. Chemically enhanced autoignition of H2-air in an internal combustion engine is also simulated.

An automotive transmission maintains a proper equilibrium between the power and torque produced by an engine and those demanded by the drive wheels. Most automatic, transmissions employ some kind of epicyclic gear mechanisms to achieve the above purpose. The first step in the design process of such a mechanism involves finding a configuration that provides a set of desired speed ratios, and meets other dynamic, and kinematic requirements. In this work, the kinematic structural characteristics of epicyclic gear mechanisms have been identified, and a methodology is formulated to systematically enumerate all possible configurations of such mechanisms. This is achieved by defining a canonical graph to represent the mechanisms. Graphs of mechanisms with up to ten links have been generated using this methodology.

Effects of boundary conditions on the computational simulation of time dependent flows is studied. In particular, the effect of various boundary conditions for the flow over a half circular cylinder which is known to exhibit periodic shedding under certain conditions is investigated. A type of convection boundary condition called the radiation boundary condition is demonstrated to eliminate the secondary frequency which contaminates the solution due to the partial reflection of the fluid structures at the exit plane. However, the boundary condition implementation comes at the additional cost of storing results corresponding to three time levels.

The Ranger Telerobotic Shuttle Experiment (RTSX) is a Space Shuttle-based flight experiment to demonstrate key telerobotic technologies for servicing assets in Earth orbit. The flight system will be teleoperated from onboard the Space Shuttle and from a ground control station at the NASA Johnson Space Center. The robot, along with supporting equipment and task elements, will be located in the Shuttle payload bay. A number of relevant servicing operations will be performed-including extravehicular activity (EVA) worksite setup, orbital replaceable unit (ORU) exchange, and other dexterous tasks. The program is underway toward an anticipated launch date in CY2002. This paper gives an overview of the RTSX mission, and describes several follow-on mission scenarios involving cooperative Ranger and EVA activities.

There is little information in the technical literature about the dependence of drag coefficient, CD, on aspect ratio (height/width) for car and truck aerodynamics. Some of the information suggests that CD should increase with aspect ratio as the flow over the body becomes more two dimensional. Recent tests of candidate shapes for a commercial van with various roof heights suggested the opposite is true; the taller vans had lower drag coefficients. This report discusses the results of several experimental investigations to examine this relationship. Scale model and production drag measurements of commercial vans are presented along with drag measurements of simple shapes. The shapes consisted of eight radiused rectangular boxes of constant length and frontal area, but with different height/width ratios. The effects of underbody roughness and bumper presence were evaluated and are discussed.

The Maryland Advanced Research/Simulation (MARS) Suit is designed to be a low-cost test bed for extravehicular activity (EVA) research, providing an environment for the development and application of biomedical sensors and advanced EVA technologies. It is also designed to be used in gaining more experience with human-telerobotic interactions in an integrated EVA worksite. This paper details the first generation MARS Suit (MX-1) design, describes the low-cost development process, and presents results from ongoing suit testing, as well as plans for future work.

A mathematical model of combustion process in a diesel engine has been developed according to the theory of the chain reactions for the higher hydrocarbon compounds. The instantaneous rates of fuel vaporization and combustion are defined by the current values of temperature, pressure, concentration of fuel vapors, overall diffusion rate, fuel injection rate, and mean fuel droplet size in terms of the SMD. Numerical experiments have been carried out for investigating the interdependencies between various combustion-related parameters. Specifically, the effect of fuel droplet size (in terms of SMD) on the subsequent combustion parameters, such as, pressure, temperature, thermodynamic properties of air/gas mixture, heat transfer, fuel vaporization, combustion rate, current A/F ratio, gas mixture composition have been investigating. In addition, the integral indicator parameters of the engine, such as the mean indicated pressure, peak pressure, compression pressure have been analyzed.

This manuscript presents a systematic approach for the design and development of a 403 V, 7 kWh battery pack for a Formula SAE student racing electric car. The pack is made up of 6 individual segments which are connected in series. Each segment has a maximum energy of 1.17 kWh and is made up of 16 arrays connected in series. Each array holds 8 Lithium-ion batteries which are connected in parallel. The overall design of the battery pack is in full compliance with the Formula SAE rules. The manuscript presents the calculation procedure and battery sizing for the power demand of a typical Formula SAE student racing electric car using vehicle dynamics equations. The entire electric traction system is modelled in Matlab/Simulink. The paper also explains the development process of the 7 kWh battery pack and highlights important design considerations, such as busbar sizing.