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Technical Paper

A Comparative Study of Non-Asbestos Organics vs. Low Steel Lomets for Humidity Sensitivity

Non-Asbestos Organic (NAO) disc pads and Low Steel Lomet disc pads were subjected to high and low humidity conditions to discover how humidity affects these two classes of formulations for physical properties, friction, wear and noise characteristics. The 2 classes of formulations show similarities and differences in response to increasing humidity. The humidity effect on deformation of the surface microstructure of the gray cast iron disc is also investigated. Humidity implications for pad quality control and brake testing are discussed.
Journal Article

A Comparison of Dual-Core Approaches for Safety-Critical Automotive Applications

Safety is a requirement concerning an increasing number of automotive applications. Recent safety standards set requirements for designing safety-critical systems. Among others, these specifications include a comprehensive detection and handling of hardware faults. Currently emerging dual-core microcontrollers provide a cost-effective opportunity to fulfill these requirements. In this paper we analyze a safety-critical application example and discuss two different approaches, an application-specific approach and a generic approach for implementing functional safety requirements on a dual-core microcontroller. An investigation of the associated concepts called function monitoring architectures and generic architectures reveals their differences and at the same time advantages and disadvantages. Besides effects on safety, effects on reliability, modifiability and costs are evaluated and presented graphically.
Journal Article

A Comparison of Methods for Representing and Aggregating Uncertainties Involving Sparsely Sampled Random Variables - More Results

This paper discusses the treatment of uncertainties corresponding to relatively few samples of random-variable quantities. The importance of this topic extends beyond experimental data uncertainty to situations involving uncertainty in model calibration, validation, and prediction. With very sparse samples it is not practical to have a goal of accurately estimating the underlying variability distribution (probability density function, PDF). Rather, a pragmatic goal is that the uncertainty representation should be conservative so as to bound a desired percentage of the actual PDF, say 95% included probability, with reasonable reliability. A second, opposing objective is that the representation not be overly conservative; that it minimally over-estimate the random-variable range corresponding to the desired percentage of the actual PDF. The presence of the two opposing objectives makes the sparse-data uncertainty representation problem an interesting and difficult one.
Technical Paper

A Comparison of Power/Weight/Space Requirements for Water-recycling Processors

Several quite different waste-water processing subsystems have been tested for space mission applications. Mission choice, and choice of priority for further development, involves processor requirements for (electrical) power, launch and resupply weights, and space occupied, and developmental factors of reliability and reparability. For each subsystem one can identify theoretical power, etc., requirements, and current realistic requirements, and potential realistic subsystem requirements. Compared are reverse osmosis, vapor-compression-distillation, and TIMES processes, in terms of power, weight, and space requirements. Discussions of electrodialysis and CELSS are included as components of water treatment systems.
Technical Paper

A Comparison of Time Domain and Frequency Domain Test Methods for Automotive Components

Frequency domain testing has had limited use in the past for durability evaluations of automotive components. Recent advances and new perspectives now make it a viable option. Using frequency domain testing for components, test times can be greatly reduced, resulting in considerable savings of time, money, and resources. Quality can be built into the component, thus making real-time subsystem and full vehicle testing and development more meaningful. Time domain testing historically started with block cycle histogram tests. Improved capabilities of computers, controllers, math procedures, and algorithms have led to real time simulation in the laboratory. Real time simulation is a time domain technique for duplicating real world environments using computer controlled multi-axial load inputs. It contains all phase information as in the recorded proving ground data. However, normal equipment limitations prevent the operation at higher frequencies.
Technical Paper

A Comparison of Unit Injector and Pump Line Nozzle Systems

The paper presents a comparative analysis of the parameters of the injection process in unit injector and pump line nozzle systems. The analysis is based on numerical programs which simulate the working processes of the both systems. The basic assumptions underlying the physical models used in these programs are discussed and the good agreement between numerical results and actual processes is shown. The analysis takes into account the most important parameters for the combustion performance efficiency of injection and durability of the system. The results confirm the essential advantages of unit injection systems for fuelling high-speed diesel engines with direct injection.
Technical Paper

A Comparison of the Tribology of Tetrahedral Amorphous Carbon and Hydrogenated Amorphous Carbon

The tribology of different DLC coatings is studied through different mechanical and tribological tests like micro-hardness, scratch tests, friction in different oils, dry friction and impact-wear tests. The different tests reveal that hydrogen-free DLC coatings exhibit high hardness and low friction coefficient against steel, in boundary lubrication regime. Unfortunately, the remarkable tribological properties of tetrahedral amorphous carbon (ta-C) coatings are balanced by a low fracture toughness and low endurance behaviour, which affect the durability of coated mechanical components.
Technical Paper

A Complex Weapon System Bayes' Strategy Using Component Test Data

The paper defines a “best” estimate of system effectiveness or reliability as one that minimizes the potential loss due to either overestimating or underestimating such a system figure of merit. A loss function is expressed in terms of the decision maker's order of preference for the consequences of either overestimation (underkill) or underestimation (overkill). However, in order for an estimate to be optimal, sufficient information at the system level should be provided. This lack or abundance of information is reflected in the variability of the measurement of system effectiveness or reliability. The variability and central tendency of this measurement are obtained from the variability and central tendency of the component data. This is achieved through the combined use of effectiveness or reliability models, Monte Carlo simulation and/or probability moments, and Bayesian statistics.
Technical Paper

A Comprehensive Study of Humidity Effects on Friction, Pad Wear, Disc Wear, DTV, Brake Noise and Physical Properties of Pads

Passenger car NAO(Non-Asbestos Organic) disc pads were subjected to low and high humidity conditions. Humidity is found to measurably affect pad dimensions, pad hardness, compressibility, friction, pad wear, disc wear, disc roughness, DTV(Disc Thickness Variation) and brake noise. Also the friction film is found to absorb a significant amount of moisture. It is essential to have a tight control of temperature and humidity for brake testing and quality control if meaningful data are to be generated with minimum variability. Seasonal changes must be considered for brake testing on the road.
Technical Paper

A Computer Controlled Power Tool for Servicing the Hubble Space Telescope

The Hubble Space Telescope (HST) was designed to be serviced from the shuttle by astronauts performing extravehicular activities (EVA). During the first HST Servicing Mission (STS-61) two types of power tools were flown, the Power Ratchet Tool (PRT) and the HST Power Tool. Each tool had both benefits and drawbacks. An objective for the second HST servicing mission was to combine the reliability, accuracy, and programmability of the PRT with the pistol grip ergonomics and compactness of the HST Power Tool into a new tool called the EVA Pistol Grip Tool (PGT). The PGT is a self-contained, microprocessor controlled, battery powered, 3/8-inch drive hand-held tool. The PGT may also be used as a non-powered ratchet wrench. Numerous torque, speed, and turn or angle limits can be programmed into the PGT for use during various servicing missions. Batteries Modules are replaceable during ground, Intravehicular Activities (IVA), and EVA operations.
Technical Paper

A Computer-Aided System for Interactive Geometric Modeling, Structural/ Dynamics Analysis and N/C Manufacturing/Inspection of Radial Flow Compressors

The technological advances which have been made in the computer hardware industry, from interactive computer graphics systems to numerically controlled manufacturing and inspection machines, has resulted in major changes in the impeller design process. The contents of this paper describes an “Interactive CAD/CAM Geometric Modeling System for Impellers” developed to integrate aerodynamic design, mechanical design, structural and dynamics analysis, manufacturing and quality assurance into an integrated CAD/CAM impeller system. The system allows for more design and analysis iterations to take place in a short time frame, resulting in optimized impeller designs. The system also reduces the lead time required for part fabrication and inspection from many months to a few weeks.
Technical Paper

A Concept of Aftermarket Support

In today's world economic environment, the probability for increased product opportunity for any given company is diminishing because we are faced with a maturing world marketplace. Much of the demand for product will come from users who replace existing products with improved and advanced state-of-the-art products that can perform utilitarian services at a more efficient and economic cost. Although advanced design concepts and improved application of engineering principles have resulted in more reliable and longer life product, there still remains a strong need to keep these products performing to meet the level of user expectation.
Technical Paper

A Configurable Solid State Power Management and Distribution System

Future vehicle power systems must achieve greater flexibility and reliability than those used in previous generations. New functions that enhance safety, such as arc detection and wiring integrity verification, are essential for new systems. Embedded autonomous control, and fault correction can be built into Fault Tolerant Processors that integrate into a vehicle Open System Architecture. This approach will provide status and fault detection information to maintenance interfaces and provide fault correction. Safety is enhanced by the prevention of dangerous restarts from crew and personnel. The embedded features allow for pre-flight mission configuration to setup systems before takeoff and on-board and off-board maintenance control. This enables operators to evaluate power system health and history to help reduce turn around time.
Technical Paper

A Cooling System for the EAPU Shuttle Upgrade

The Shuttle orbiter currently uses hydrazine-powered APU’s for powering its hydraulic system pumps. To enhance vehicle safety and reliability, NASA is pursuing an APU upgrade where the hydrazine-powered turbine is replaced by an electric motor pump and battery power supply. This EAPU (Electric APU) upgrade presents several thermal control challenges, most notably the new requirement for moderate temperature control of high-power electronics at 132 °F (55.6 °C). This paper describes how the existing Water Spray Boiler (WSB), which currently cools the hydraulic fluid and APU lubrication oil, is being modified to provide EAPU thermal management.
Technical Paper

A Corporate Product Quality Assurance Program

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.”
Technical Paper

A Critical Review of Physical Test Methods for Gasket Materials

A considerable number of test methods exist for the determination of the physical properties of nonmetallic gasket materials. Some are used primarily as quality controls while others also serve to describe specific functional properties. The relationships of various test procedures to the characteristics of these materials differ considerably in their degree of applicability. Current development work on new test methods is directed principally toward increased emphasis on functional properties. The goal is to provide more reliable means for selecting and qualifying gasket materials.
Technical Paper

A Custom Built Microcomputer System for Automotive Applications

A custom microprocessor system (CPU, I/O, ROM) has been developed especially for automotive applications. The design goal was to create a chip-set which can be manufactured for reasonable costs, meets the tough reliability and environmental conditions, and performs well enough for modern engine control requirements. The system was designed in close cooperation with a semiconductor house (AMI) so that all design trade-offs were transparent to the original system designers. The first part deals with the general design philosophy. The second gives some detailed information on the microprocessor system itself.
Technical Paper

A DFSS Approach to Optimize the Second Row Floor Duct Using Parametric Modelling

The main function of mobile air conditioning system in a vehicle is to provide the thermal comfort to the occupants sitting inside the vehicle at all environmental conditions. The function of ducts is to get the sufficient airflow from the HVAC system and distribute the airflow evenly throughout the cabin. In this paper, the focus is to optimize the rear passenger floor duct system to meet the target requirements through design for six sigma (DFSS) methodology. Computational fluid dynamics analysis (CFD) has been used extensively to optimize system performance and shorten the product development time. In this methodology, a parametric modeling of floor duct design using the factors such as crossectional area, duct length, insulation type, insulation thickness and thickness of duct were created using CATIA. L12 orthogonal design array matrix has been created and the 3D CFD analysis has been carried out individually to check the velocity and temperature.
Technical Paper

A Data Acquisition and Processing System for Engine Tests

This paper describes the data acquisition and processing system of the Machines and Machine Construction Laboratory of the University of Gent. A system incorporating a minicomputer has been found to give by far most possibilities. Its flexibility, modular design, simplicity in use and computing capacity are particularly appreciated. The installation is fixed in order to have a reliable system. Analog lines for the signals and digital lines for the operators console connect the test rigs to the data logger. The calculation of the static pressure level from dynamic measurements is described as a possible application of the system.