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Technical Paper

Industry Experiences with Activity-Based LCA

2000-04-26
2000-01-1464
In this paper, we discuss our experiences with applying an approach called Activity-Based Life-Cycle Assessment (LCA) in industrial settings. In contrast to other Life-Cycle Assessment approaches, we have taken modern cost management practices such as Activity Based Costing as a basis for our approach to environmental impact assessment. The resulting method, Activity-Based LCA, is an extension of Activity-Based Costing as it handles costs, energy consumption and waste generation simultaneously under the presence of uncertainty in a single framework.
Technical Paper

Time Irreversibility and Comparison of Cyclic-Variability Models

1999-03-01
1999-01-0221
We describe a method for detecting and quantifying time irreversibility in experimental engine data. We apply this method to experimental heat-release measurements from four spark-ignited engines under leaning fueling conditions. We demonstrate that the observed behavior is inconsistent with a linear Gaussian random process and is more appropriately described as a noisy nonlinear dynamical process.
Technical Paper

Digital Human Modeling for Universal Design

2003-06-17
2003-01-2199
Several research institutions and universities have taken on the challenge of providing solutions for accessible and universally designed workplace accommodations with a focus on people with disabilities. Accessible Design is a subset of what is termed Universal Design. Where Universal Design covers the design of products, systems and environments for all people and encompasses all design principles, Accessible Design focuses on principles that extend the standard design process to those people with some type of performance limitation. In order for individuals with disabiltities to gain better access to the work environments and the products that facilitate independence, health, safety, and social participation a multi-disciplined approach to the research is needed to identify needs and challenges of the targeted population.
Technical Paper

Georgia Tech's FutureTruck Split-Parallel Hybrid SUV Design

2003-03-03
2003-01-1270
The Georgia Tech FutureTruck Team has designed a strong parallel split-hybrid powertrain for the model year 2002 Ford Explorer SUV. The modified powertrain uses a Lincoln LS 3.0L, V-6, DOHC, aluminum engine driving the rear axle. An AC-150 from AC Propulsion is coupled to the front wheels through a 3.75:1 Auburn Gear speed reducer. This split-hybrid structure fits well into the Explorer and is to manufacture. The interior cabin has been maintained in a stock configuration by carefully integrating the added instrumentation and electric drive controls into the dash and console. The toque-blending hybrid electric control is designed to be charge sustaining such that the refueling procedures match those of the stock vehicle. When fully operational, this powertrain is expected to yield a net 25% increase in fuel efficiency while lowering emissions without any sacrifice in customer acceptability.
Technical Paper

Buckling Analysis of Structures with Interval Uncertainty

2005-04-11
2005-01-0347
In order to ensure the safety of a structure, adequate strength for structural elements must be provided. In addition, the catastrophic deformations such as buckling must be prevented. In most buckling analyses, structural properties and applied loads are considered certain. Using the linear finite element method, the deterministic buckling analysis is done in two main steps. First, a static analysis is performed using an arbitrary ordinate of applied load. Using the obtained element axial forces, the geometric stiffness of the structure is assembled. Second, performing an eigenvalue problem between the structure's elastic and geometric stiffness matrices yields the structure's critical buckling loads. However, these deterministic approaches disregard uncertainty in the structure's material and geometric properties. In this work, an interval formulation is used to represent the uncertainty in the structure's parameters such as material characteristics.
Technical Paper

Experimental Investigation of Dither Control on Effective Braking Torque

2003-05-05
2003-01-1617
Automotive brake squeal is a problem that has plagued the automotive industry for years. Many noise cancellation techniques have been published. One such technique is the use of an external dither signal, that has been shown to suppress automotive disc brake squeal in experiments with a brake dynamometer, but the effect of this control on the system's braking torque has yet to be determined. By imposing a high frequency disturbance normally into the brake pad, squeal is suppressed. There are many studies that lead to the conclusion of a lower effective braking torque due to the high frequency dither control signal. Under the assumption of Hertzian contact stiffness it has been speculated that the loss in braking torque is due to a lowering of the average normal force. There has also been work done that proves that the application of a dither signal in the normal direction eliminates the ‘stick-slip’ oscillation that causes brake squeal by an effective decrease in the friction force.
Technical Paper

Development of a Simple Homogeneous Flow Model of a Two-Phase Ejector

1999-08-02
1999-01-2698
This paper first briefly reviews the concept of ejector-driven heating and refrigerating systems. The advantages of these systems over conventional systems are outlined. The issue of momentum mismatch between the primary and secondary flows in ejectors is identified as the primary cause of their inherently low second law efficiency. An idea is proposed to solve this problem by adding a non-volatile liquid to the primary flow to reduce the momentum mismatch. The preliminary feasibility of this technique is explored by developing a simple homogeneous two-phase flow model of an ejector. Preliminary results show that the proposed idea reduces irreversibilities and potentially increases the cooling effect.
Technical Paper

The Implementation of a Conceptual Aerospace Systems Design and Analysis Toolkit

1999-10-19
1999-01-5639
The Conceptual Aerospace Systems Design and Analysis Toolkit (CASDAT) provides a baseline assessment capability for the Air Force Research Laboratory. The historical development of CASDAT is of benefit to the design research community because considerable effort was expended in the classification of the analysis tools. Its implementation proves to also be of importance because of the definition of assessment use cases. As a result, CASDAT is compatible with accepted analysis tools and can be used with state-of-the-art assessment methods, including technology forecasting and probabilistic design.
Technical Paper

Development of Wing Structural Weight Equation for Active Aeroelastic Wing Technology

1999-10-19
1999-01-5640
A multidisciplinary design study considering the impact of Active Aeroelastic Wing (AAW) technology on the structural wing weight of a lightweight fighter concept is presented. The study incorporates multidisciplinary design optimization (MDO) and response surface methods to characterize wing weight as a function of wing geometry. The study involves the sizing of the wing box skins of several fighter configurations to minimum weight subject to static aeroelastic requirements. In addition, the MDO problem makes use of a new capability, trim optimization for redundant control surfaces, to accurately model AAW technology. The response surface methodology incorporates design of experiments, least squares regression, and makes use of the parametric definition of a structural finite element model and aerodynamic model to build response surface equations of wing weight as a function of wing geometric parameters for both AAW technology and conventional control technology.
Technical Paper

An Application of a Technology Impact Forecasting (TIF) Method to an Uninhabited Combat Aerial Vehicle

1999-10-19
1999-01-5633
In today’s atmosphere of lower U.S. defense spending and reduced research budgets, determining how to allocate resources for research and design has become a critical and challenging task. In the area of aircraft design there are many promising technologies to be explored, yet limited funds with which to explore them. In addition, issues concerning uncertainty in technology readiness as well as the quantification of the impact of a technology (or combinations of technologies), are of key importance during the design process. The methodology presented in this paper details a comprehensive and structured process in which to explore the effects of technology for a given baseline aircraft. This process, called Technology Impact Forecasting (TIF), involves the creation of a forecasting environment for use in conjunction with defined technology scenarios. The advantages and limitations of the method will be discussed, as well its place in an overall methodology used for technology infusion.
Technical Paper

Viable Designs Through a Joint Probabilistic Estimation Technique

1999-10-19
1999-01-5623
A key issue in complex systems design is measuring the ‘goodness’ of a design, i.e. finding a criterion through which a particular design is determined to be the ‘best’. Traditional choices in aerospace systems design, such as performance, cost, revenue, reliability, and safety, individually fail to fully capture the life cycle characteristics of the system. Furthermore, current multi-criteria optimization approaches, addressing this problem, rely on deterministic, thus, complete and known information about the system and the environment it is exposed to. In many cases, this information is not be available at the conceptual or preliminary design phases. Hence, critical decisions made in these phases have to draw from only incomplete or uncertain knowledge. One modeling option is to treat this incomplete information probabilistically, accounting for the fact that certain values may be prominent, while the actual value during operation is unknown.
Technical Paper

Enabling Advanced Design Methods in an Internet-Capable Framework

1999-10-19
1999-01-5578
The enabling of advanced design methods in an internet-capable framework will be discussed in this paper. The resulting framework represents the next generation of design and analysis capability in which engineering decision- making can be done by geographically distributed team members. A new internet technology called the lean-server approach is introduced as a mechanism for granting Web browser access to frameworks and domain analyses. This approach has the underpinnings required to support these next generation frameworks - collaboratories. A historical perspective of design frameworks is discussed to provide an understanding of the design functionality that is expected from framework implementations to insure design technology advancement. Two research areas were identified as being important to the development of collaboratories: design portals and collaborative methods.
Technical Paper

Method for the Exploration of Cause and Effect Links and Derivation of Causal Trees from Accident Reports

1999-04-13
1999-01-1433
The ultimate goal of knowledge-based aircraft design, pilot training and flight operations is to make flight safety an inherent, built-in feature of the flight vehicle, such as its aerodynamics, strength, economics and comfort are. Individual flight accidents and incidents may vary in terms of quantitative characteristics, circumstances, and other external details. However, their cause-and-effect patterns often reveal invariant structure or essential causal chains which may re-occur in the future for the same or other vehicle types. The identification of invariant logical patterns from flight accident reports, time-histories and other data sources is very important for enhancing flight safety at the level of the ‘pilot - vehicle -operational conditions’ system. The objective of this research project was to develop and assess a method for ‘mining’ knowledge of typical cause-and-effect patterns from flight accidents and incidents.
Technical Paper

Engineering a Space Based Construction Robot

2005-10-03
2005-01-3406
This paper describes a machine to quarry construction material, sinter walls, and assemble future space station modules. In prior work, we explored the solar energy requirements to build a 50m diameter, 50m high, cylindrical module out of pulverized rock from a Near-Earth Object, using tailored radio wave fields. In this paper, we describe the issues in the conceptual design of the robotic construction machines. The 4-legged Rock breaker is designed to fit the payload bay of a modern heavy-lift booster to reach Low Earth Orbit, and primary solar-sail propulsion for most of its journey. It uses beamed microwave energy for its cutting operations. Rotating, telescoping arms use integrated laser/plasma jet cutter arrays to dig trenches in spiral patterns which will form blocks of material. Cut blocks are sent into a toroidal cloud of material for use in the force field tailoring for automatic module formation.
Technical Paper

Conceptual Design of Current Technology and Advanced Concepts for an Efficient Multi-Mach Aircraft

2005-10-03
2005-01-3399
A design process is formulated and implemented for the taxonomy selection and system-level optimization of an Efficient Multi-Mach Aircraft Current Technology Concept and an Advanced Concept. Concept space exploration of taxonomy alternatives is performed with multi-objective genetic algorithms and a Powell’s method scheme for vehicle optimization in a multidisciplinary modeling and simulation environment. A dynamic sensitivity visualization analysis tool is generated for the Advanced Concept with response surface equations.
Technical Paper

Supersonic Business Jet Design and Requirements Exploration using Multiobjective Interactive Genetic Algorithms

2005-10-03
2005-01-3398
Although market research has indicated that there is significant demand for a supersonic business aircraft, development of a feasible concept has proven difficult. Two factors contributing to this difficulty are the uncertain nature of the vehicle’s requirements and the fact that conventional design methods are inadequate to solve such non-traditional problems. This paper describes the application of a multiobjective genetic algorithm to the design space exploration of such a supersonic business jet. Results obtained using this method are presented, and give insight into the important decisions that must be made at the early stages of a design project.
Technical Paper

Technology Assessment of a Supersonic Business Jet

2005-10-03
2005-01-3393
This paper presents a quantitative process to track the progress of technology developments within NASA’s Vehicle Systems Program (VSP) as implemented on a Supersonic Business Jet (SBJ). The process, called the Technology Metric Assessment and Tracking (TMAT) process, accounts for the temporal aspects of technology development programs such that technology portfolio assessments, in the form of technological progress towards VSP sector goals, may be tracked and assessed. Progress tracking of internal research and development programs is an essential element to successful strategic endeavors and justification of the pursuit of capital projects [1].
Technical Paper

Specification of a P3 Parallel Hybrid Electric Vehicle Architecture for the EcoCAR 3 Competition

2016-04-05
2016-01-1245
The Georgia Tech EcoCAR 3 team’s selection of a parallel hybrid electric vehicle (HEV) architecture for the EcoCAR 3 competition is presented in detail, with a focus on the team’s modeling and simulation efforts and how they informed the team’s architecture selection and subsequent component decisions. EcoCAR 3, sponsored by the United States Department of Energy and General Motors, is the latest in a series of Advanced Vehicle Technology Competitions (AVTCs) and features 16 universities from the United States and Canada competing to transform the 2016 Chevrolet Camaro into a hybrid electric American performance vehicle. Team vehicles will be scored on performance, emissions, fuel economy, consumer acceptability, and more over the course of the four-year competition. During the first year, the Georgia Tech team considered numerous component combinations and HEV architectures, including series RWD and AWD, parallel, and power-split.
Technical Paper

Yaw Effects on the Narrowband Spectra Above a Delta Wing in Turbulent Flow

2016-09-20
2016-01-2056
Combat aircraft maneuvering at high angles of attack or in landing approach are likely to encounter conditions where the flow over the swept wings is yawed. This paper examines the effect of yaw on the spectra of turbulence above and aft of the wing, in the region where fins and control surfaces are located. Prior work has shown the occurrence of narrowband velocity fluctuations in this region for most combat aircraft models, including those with twin fins. Fin vibration and damage has been traced to excitation by such narrowband fluctuations. The narrowband fluctuations themselves have been traced to the wing surface. The issue in this paper is the effect of yaw on these fluctuations, as well as on the aerodynamic loads on a wing, without including the perturbations due to the airframe.
Technical Paper

A Cycloidal Rotor and Airship System for On-Demand Hypercommuting

2016-09-20
2016-01-2026
An architecture is proposed for on-demand rapid commuting across congested-traffic areas. A lighter-than-air (LTA) vehicle provides the efficient loitering and part of the lift, while a set of cycloidal rotors provides the lift for payload as well as propulsion. This combination offers low noise and low downwash. A standardized automobile carriage is slung below the LTA, permitting driveway to driveway boarding and off-loading for a luxury automobile. The concept exploration is described, converging to the above system. The 6-DOF aerodynamic load map of the carriage is acquired using the Continuous-Rotation method in a wind tunnel. An initial design with rear ramp access is modified to have ramps at both ends. The initial design shows a divergence sped in access of 100 mph. An effort to improve the ride quality using yaw stabilizers, failed as the dynamic behavior becomes unstable. The requirements for control surfaces and instrumentation are discussed.
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