Mavris, Dimitri N.

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Now showing 1 - 10 of 72
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    Viable Designs Through a Joint Probabilistic Estimation Technique
    (Georgia Institute of Technology, 1999-10) Bandte, Oliver ; Mavris, Dimitri N. ; DeLaurentis, Daniel A.
    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. Hence, to account for a multi-criteria as well as a probabilistic approach to systems design, a joint-probabilistic formulation is needed to accurately estimate the probability of satisfying the criteria concurrently. When criteria represent objective/ aspiration functions with corresponding goals, this ?int probability?can also be called viability. The proposed approach to probabilistic, multi-criteria aircraft design, called the Joint Probabilistic Decision Making (JPDM) technique, will facilitate precisely this estimate.
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    An Improved Process for the Generation of Drag Polars for Use in Conceptual/Preliminary Design
    (Georgia Institute of Technology, 1999-10) Mavris, Dimitri N. ; Qiu, Songtao
    One of the most essential contributors in the aircraft sizing and synthesis process is the creation and utilization of accurate drag polars. An improved general procedure to generate drag polars for conceptual and preliminary design purposes in the form of Response Surface Equations is outlined and discussed in this paper. This approach facilitates and supports aerospace system design studies as well as Multi-disciplinary Analysis and Optimization. The analytically created Response Surface Equations replace the empirical aerodynamic relations or historical data found in sizing and synthesis codes, such as the Flight Optimization System (FLOPS). These equations are commonly incorporated into system level studies when a configuration falls beyond the conventional realm. The approach described here is a statistics-based methodology, which combines the use of Design of Experiments and Response Surface Method (RSM). Computational aerodynamic codes based on linearized potential flow and boundary layer theory are employed to generate the needed parametric relationships. The process is facilitated through the use of an automated computational architecture that is capable of handling massive exchanges of data and information. The aforementioned process is demonstrated through an implementation of the procedure for a High Speed Civil Transport concept. The accuracy of these Response Surface Equations is finally tested to demonstrate the fidelity and accuracy of their predictive capability.
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    The Implementation of a Conceptual Aerospace Systems Design and Analysis Toolkit
    (Georgia Institute of Technology, 1999-10) Hale, Mark A. ; Mavris, Dimitri N. ; Carter, Dennis L.
    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.
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    Elements of an Emerging Virtual Stochastic life Cycle Design Environment
    (Georgia Institute of Technology, 1999-10) Mavris, Dimitri N. ; DeLaurentis, Daniel A. ; Hale, Mark A. ; Tai, Jimmy C. M.
    The challenge of designing next-generation systems that meet goals for system effectiveness, environmental compatibility, and cost has grown to the point that traditional design methodologies are becoming ineffective. Increases in the analysis complexity required, the number of objectives and constraints to be evaluated, and the multitude of uncertainties in today? design problems are primary drivers of this situation. A new environment for design has been formulated to treat this situation. It is viewed as a testbed, in which new techniques in such areas as design-oriented/physics-based analysis, uncertainty modeling, technology forecasting, system synthesis, and decision-making can be posed as hypotheses. Several recent advances in elements of this multidisciplinary environment, termed the Virtual Stochastic Life Cycle Design Environment, are summarized in this paper.
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    Enabling Advanced Design Methods in an Internet-Capable Framework
    (Georgia Institute of Technology, 1999-10) Hale, Mark A. ; Mavris, Dimitri N.
    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. An internet-enabled design framework called IMAGE is highlighted and demonstrated using a probabilistic design example. The prototyped methods have found their way into a Conceptual Aerospace Systems Design and Analysis Toolkit used by the Air Force Research Laboratory.
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    An Application of a Technology Impact Forecasting (TIF) Method to an Uninhabited Combat Aerial Vehicle
    (Georgia Institute of Technology, 1999-10) Mavris, Dimitri N. ; Soban, Danielle Suzanne ; Largent, Matthew Clinton
    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. In addition, the example TIF application used in this paper, that of an Uninhabited Combat Aerial Vehicle, serves to illustrate the applicability of this methodology to a military system.
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    Forecasting Technology Uncertainty in Preliminary Aircraft Design
    (Georgia Institute of Technology, 1999-10) Kirby, Michelle Rene ; Mavris, Dimitri N.
    An evolved version of the Technology Identification, Evaluation, and Selection (TIES) method is presented that provides techniques for quantifying technological uncertainty associated with immature technologies. Uncertainty in this context implies forecasting. Forecasting the impact of immature technologies on a system is needed to provide increased knowledge to a decision-maker in the conceptual and preliminary phases of aircraft design. The increased knowledge allows for proper allocation of company resources and program management. The TIES method addresses the milestones encountered during a technology development program, the sources of uncertainty during that development, a potential method for bounding and forecasting the uncertainty, and a means to quantify the impact of any emerging technology. A proof of concept application was performed on a High Speed Civil Transport concept due to its technically challenging customer requirements.
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    Development of Wing Structural Weight Equation for Active Aeroelastic Wing Technology
    (Georgia Institute of Technology, 1999-10) Zink, Paul Scott ; Mavris, Dimitri N. ; Flick, Peter M. ; Love, Michael H.
    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. The goal for this design study is to demonstrate a process by which some of the benefits associated with AAW technology can be quantified over the wing geometry design space, so that future conceptual designers may make the best use of the technology.
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    A Lean-Server Approach to Enabling Collaboration Using Advanced Design Methods
    (Georgia Institute of Technology, 1999-09) Hale, Mark A. ; Craig, James I. ; Mavris, Dimitri N.
    The design framework research community utilizes the internet as a facilitator for collaborative activities. The internet provides a platform independent interface and geographic distribution. Information can be easily represented to the end-user using the HyperText Markup Language and can be coded in a reasonable timeframe. A shortcoming of exploiting this technology further is the reliance on existing Web servers to interface with analysis tools and design services. In this case, interactive components require auxiliary processes (called CGI scripts) to be started by the server that are used in an inefficient manner. This model does not provide the user-oriented capability required by standalone applications. Java offers improvements in client-side processing but a server bottleneck still exists. A novel approach using lean-servers is introduced as an alternative method for providing an efficient server-side computing model. In this case, internet requests are brokered directly by the design application by providing a gateway to the application? programming interface using a HyperText Transfer Protocol compliant layer. This allows requests to be managed directly by the application rather than requiring auxiliary services. Step-by-step directions for implementing this approach using a case study of an existing design framework are given in this paper. A prototype system, called the Systems Programming Architecture for Collaborative Engineering, is described as one scenario for implementing the lean-server technology. Usability of the approach is demonstrated through a Design of Experiments example that is representative of modern design methods. This example also demonstrates collaboration because it executes asynchronously with multi-user intervention at any time during the process. In hindsight, the lean-server approach is an enabling technology for collaborative design and focuses future research direction on the establishment of collaborative design practices.
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    A Method for Probabilistic Sensitivity Analysis of Commercial Aircraft Engines
    (Georgia Institute of Technology, 1999-09) Mavris, Dimitri N. ; Roth, Bryce Alexander ; Macsotai, Noel I.
    The objective of this paper is to illustrate how probabilistic methods can be utilized to rationally and analytically make design decisions in the presence of uncertainty, with emphasis on the use of probabilistic sensitivities in the aircraft gas turbine engine preliminary design process. A brief review of risk and uncertainty in the engine design process is given, and the role of probabilistic methods is discussed. Probabilistic sensitivity analysis, used in conjunction with response surface methods, is proposed as a computationally-efficient method to address defined sources of uncertainty and risk in engine design from a system level perspective. The method outlined is then applied to the analysis of engine component performance uncertainty impact on the performance of a notional four-engine wide-body commercial transport. More specifically, uncertainty in engine design parameters is shown to have a direct and quantifiable impact on aircraft system figures of merit such as design range and fuel burn. The methods developed are then used to create a set of contour plots showing the behavior of vehicle performance uncertainty over the design space of interest.