Mavris, Dimitri N.

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Now showing 1 - 7 of 7
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    System Reliability Assessment using Covariate Theory
    (Georgia Institute of Technology, 2004-01) Wallace, Jon Michael ; Mavris, Dimitri N. ; Schrage, Daniel P.
    A method is demonstrated that utilizes covariate theory to generate a multi-response component failure distribution as a function of pertinent operational parameters. Where traditional covariate theory uses actual measured life data, a modified approach is used herein to utilize life values generated by computer simulation models. The result is a simulation-based component life distribution function in terms of time and covariate parameters for each failure response. A multivariate joint probability covariate model is proposed by combining the covariate marginal failure distributions with the Nataf transformation approach. Evaluation of the joint probability model produced significant improvement in joint probability predictions as compared to the independent series event approach. The proposed methods are executed for a nominal aircraft engine system to demonstrate the assessment of multi-response system reliability driven by a dual mode turbine blade component failure scenario as a function of operational parameters.
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    An Integrated Decision-making Method to Identify Design Requirements Through Agent-based Simulation for Personal Air Vehicle System
    (Georgia Institute of Technology, 2002-10) Lewe, Jung-Ho ; Ahn, Byung-Ho ; DeLaurentis, Daniel A. ; Mavris, Dimitri N. ; Schrage, Daniel P.
    A product?s design requirements guide the next development efforts. Thus, correct decision-making is critical in generating design requirements as vehicle concepts are being formulated. A new method is proposed to account for system-of-systems aspects and to aid a decision-making process in synthesizing design requirements for a personal air vehicle system. The use of an agent-based modeling technique facilitates the abstraction of the key elements in the whole system. A traveling party is treated as an agent, and the infrastructure environment in the national transportation system is easily represented in the model. A number of simulations are performed to demonstrate the capability of this new approach. The method not only measures the effect of design requirements of a personal air vehicle system through sensitivity analyses, but also evaluates the effect of system technologies quantitatively, while maintaining the system-of-systems perspective. With this powerful method, designers can extract essential technical requirements that allow polishing of concept vehicles; policy makers can investigate the infrastructure and technology impact of new systems; and business planners can perform an analysis based on their own market assumptions.
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    System-of-Systems Modeling for Personal Air Vehicles
    (Georgia Institute of Technology, 2002-09) DeLaurentis, Daniel A. ; Lim, Choon Giap ; Kang, Taewoo ; Mavris, Dimitri N. ; Schrage, Daniel P.
    On-going research is described in this paper concerning the development of a methodology for adaptable system studies of future transportation solutions based upon personal air vehicles. Two challenges in this research are presented. The challenge of deriving requirements for revolutionary transportation concepts is a difficult one, due to the fact that future transportation system infrastructure and market economics are inter-related (and uncertain) parts of the equation. Thus, there is a need for a macroscopic transportation model, and such a task is well suited for the field of techniques known as system dynamics. The determination and visualization of the benefits of proposed personal air vehicle concepts for individuals presents a second challenge. In this paper, the primary benefit metrics that serve as system requirements for personal transportation applications are the Doorstep-to-Destination travel time-savings and net present value of utilizing the new transportation option as compared to a conventional transportation mode. The modeling and determination of these metrics, the synthesis of vehicle characteristics, as well as existing travel statistical data are integrated into the system model to enable visualization of the design space and to guide the design space evolution through sensitivity assessment. This individual traveler-based analysis is referred to as a microscopic model, and interesting results from its execution are reported. The results indicate the level and direction of technology progress required to create economically viable personal air transportation architectures.
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    Assessing the Impact of Mission Requirements, Vehicle Attributes, Technologies and Uncertainty in Rotorcraft System Design
    (Georgia Institute of Technology, 2002-06) Baker, Andrew Paul ; Mavris, Dimitri N. ; Schrage, Daniel P.
    This research provides a probabilistic design environment for the propagation of design uncertainty to the system level to assist in making more educated decisions in the early stages of design. This design uncertainty is associated with the key elements that are addressed in system design and which are captured in the appropriate design environment, namely mission requirements, vehicle attributes and technologies. The proposed environments are constructed using a metamodeling technique called Response Surface Methodology (RSM) and provide a model relating system-level responses to the mission requirements, vehicle attributes and technologies. The Mission Space Model is concerned with mission requirements exclusively and provides the ability to model an infinite set of missions. The Unified Tradeoff Environment (UTE) integrates the mission requirements, vehicle attributes and technologies in a single environment while allowing both deterministic and probabilistic analyses. The design environments and design methods proposed in this research are demonstrated for a rotorcraft of current interest, namely the Future Transport Rotorcraft, and probabilistic applications are presented. educated decisions in the early phases of complex system design.
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    Simultaneous Assessment of Requirements and Technologies in Rotorcraft Design
    (Georgia Institute of Technology, 2000-05) Mavris, Dimitri N. ; Baker, Andrew Paul ; Schrage, Daniel P.
    Recent emphasis in the design and acquisition of complex systems has focused on the requirements that drive the design process. Most fundamental to the rotorcraft designer is the effect that requirements have on the system design. Requirements drive initial design studies, procurement decisions, and ultimately operational effectiveness and cost. However, it is often the case that design processes (and designers) overlook the impact of changes and/or ambiguity in requirements and fail to understand the relationships between requirements, technologies, and the design space. Increasingly, the decisions made early in the design time line involve the choice of new technologies or combinations of new technologies that will ensure the system meets customer requirements. Providing the designer/decision maker with knowledge of these relationships enhances the ability to find a technically feasible, economically viable, robust solution for the customer. In this paper, the authors present a design environment for the simultaneous assessment of technologies, requirements and design space. The creation of this environment is described along with the tools for its implementation. Examples of the various design spaces are presented for a civil tiltrotor. The requirements space for the civil tiltrotor is further examined. Finally, the benefit of applying this environment to the Joint Transport Rotorcraft is discussed.
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    Capturing Corporate Philosophy: The Future of IT
    (Georgia Institute of Technology, 2000-02) Hale, Mark A. ; Daberkow, Debora Daniela ; DeLaurentis, Daniel A. ; Mavris, Dimitri N. ; Schrage, Daniel P. ; Craig, James I.
    Context is proposed as a mechanism for organizing Information Technology practices in the future through its role in interpretation. An enterprise organization model based on decision-flow is presented here that is applicable to a variety of domains. It contains elements that mark the information content with respect to a full consideration of its environment. These elements are, in order of increasing superiority, data, information, knowledge, judgement, and philosophy. There are four marked stages where contextual derivation occurs among these elements, including definition, refinement, improvement, and realization. Discovery occurs during the derivation of context and it is at this time that higher-level processes influence subordinate processes. For this reason, it is believed that corporate philosophy can be infused explicitly throughout enterprise practices. The resulting organizational model can be used by an enterprise to strategically allocate resources and maintain competitive advantage.
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    Technology Infusion and Resource Allocation for a Civil Tiltrotor
    (Georgia Institute of Technology, 2000-01) Mavris, Dimitri N. ; Baker, Andrew Paul ; Schrage, Daniel P.
    The methodology presented in this paper is concerned with the ability to make informed decisions early in the design time line in order to provide a feasible, viable and robust system to the customer. Increasingly, the issues of affordability, uncertainty in design and technology impact assessment are shaping the modern design environment. Current methodologies and techniques are not able to properly handle these issues. The research presented here builds on the authors?previous work which described an appropriate probabilistic design environment that allows for design in the presence of uncertainty as well as the infusion and assessment of new technologies. This environment is an essential part of a design methodology referred to as the Technology Identification, Evaluation and Selection (TIES) method. The objective of this research is to provide a comprehensive, structured, and robust methodology for decision making in the early phases of rotorcraft design. In this paper the authors will describe in detail the steps that encompass the TIES methodology. Illustrative examples of techniques, methods and tools used during the methodology will be presented as applied to NASA? Short Haul Civil Tiltrotor.