86 research outputs found

    Evaluating system change options and timing using the epoch syncopation framework

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    Complex engineering systems face many unknowns with respect to their operating contexts and time-varying stakeholder needs over their lifespan. A useful means for partitioning this problem is to consider a set of static snapshots of contexts with accompanying stakeholder needs over fixed periods of time, herein called “epochs.” Designs can be optimized towards delivering stakeholder utility in a specific epoch or across a variety of epochs. In order to consider the uncertain sequence of epochs experienced by a system, the Epoch Syncopation Framework (ESF) is introduced in this paper. This framework, using Monte Carlo analysis and Markov probability matrices, analyzes the execution of potential system “change mechanisms,” which alter a system over time to respond to epoch shifts. Through an analysis of design tradespaces, the ESF takes into account performance, schedule, cost, and uncertainty regarding experienced epoch shifts. The intended contributions of the ESF include a set of useful baseline designs, desirable change mechanisms, and strategies for executing change mechanisms across a system lifespan. The ESF is demonstrated through an application to an existing dataset containing designs for a “space tug” satellite including its set of potential epochs.Massachusetts Institute of Technology. Systems Engineering Advancement Research Initiativ

    A normative approach to designing for evolvability : methods and metrics for considering evolvability in systems engineering

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012."June 2012." Page 124 blank. Cataloged from PDF version of thesis.Includes bibliographical references (p. 121-123).As engineering endeavors become larger, more complex, and more expensive, the advantages of evolvable design and redesign grow. Cost and complexity are not the only factors driving the need for evolvability; changes in requirements and context can also lead to the need for redesign. This research looks to characterize evolvability, propose design principles for evolvability, determine the conditions that make designing for evolvability appropriate, and in the case of preplanned generations, determine an appropriate generation length. Evolvability is defined in this research as "the ability of an architecture to be inherited and changed across generations [over time]." This definition is used as a basis for determining a metric for measuring evolvability. The Filtered Outdegree for Evolvability metric was determined to be the most appropriate metric for measuring evolvability. The Epoch Syncopation Framework (ESF) was developed as a way of analyzing point designs, change mechanisms, execution timing, and change strategies. The ESF provides the capability to determine the conditions that make evolvability an appropriate design consideration, as well as use the temporal nature of system changes to decide on an appropriate generation length if preplanned generations are to be utilized. The Expedited Tradespace Approximation Method (ETAM) was developed in response to the heavy reliance of filtered outdegree metric and ESF on tradespace networks. ETAM leverages intelligent subsampling and interpolation methods to generate acceptable data for a large tradespace, using less computational resources than applying a performance model to every design point would normally take. All three methods were applied to case studies to demonstrate their effectiveness. A list of evolvability design principles is proposed informed by literature and findings from case study applications. The contributions of this research will enable future considerations of evolvability in systems engineering.by Daniel O'Brien Fulcoly.S.M

    Identification of Technology Integration Challenges at Two Global Automotive OEMs

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    Platform design has been firmly established in the automotive industry as a strategy to provide wider product variety while maintaining cost effective production. But this strategy can struggle to keep up with the pace and nature of emerging technologies. This paper reviews the existing approaches to modelling product platforms, and showcases the challenges at OEMs introducing new technological innovations in their platforms. A gap is identified in the methods to assess the ability of existing platforms to integrate new technologies whenever they become available

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    Enabling Design for Affordability: An Epoch-Era Analysis Approach

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    Identification and Valuation of Flexibility in Marine Systems Design

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    Marine systems, typically related to transport services and offshore petroleum projects, are often complex and involve a high degree of uncertainty related to their future operating context. Uncertain factors, such as oil prices and changing environmental regulations, are usually highly influential for the performance of these projects and introduce risks for investors in the capital-intensive maritime industry. This thesis investigates how flexibility can be considered at the design stage for handling uncertainty for marine systems, in contrast to traditional post-design operational methods. Flexibility opens up for both reducing the downside risk and taking advantage of upside possibilities, hence increasing the expected value of a design. Even though real options analysis represents an established approach for analysing flexibility, it may be inappropriate for more complex systems. To better structure options for marine systems design, a differentiation is made between more traditional, operational "on" options, and more complex, technical "in" options. Choosing the right method for analysis is ambiguous, therefore multiple approaches for identifying and valuing relevant flexibilities are discussed in this thesis. Identification methods include interviews and different systems engineering platforms for exploring how designs respond to changing contextual parameters. Valuation approaches include traditional analytical, lattice and Monte Carlo simulation methods for pricing real options, and more novel tradespace evaluation techniques. A generic framework for flexibility analysis is presented, serving as a stepwise approach to quantifying flexibility and as a means of communication between analysts and decision makers, both technical and non-technical. The flexibility analysis framework is illustrated through a case study of a large container ship design. By using screening methods to identify candidate flexibilities such as capacity expansion and fuel-switching, and Monte Carlo simulations for valuation, it was found that flexibility increases the profitability index by 27%, on a 200 million dollar investment. Furthermore, it was demonstrated that screening and simulation methods are appropriate for the use in design of large commercial deep-sea marine transportation systems. From an established real options valuation side, it is obvious that strategic flexibility has value, however, for non-standard applications typically involving complex "in" options, it is more ambiguous how to proceed. Even though system analysts recognise the value of flexibility, there is still a need for further research since flexibility rarely is seen in the maritime industry

    PSYCHOACOUSTIC OPTIMIZATION OF THE VQ-VAE AND TRANSFORMER ARCHITECTURES FOR HUMAN-LIKE AUDITORY PERCEPTION IN MUSIC INFORMATION RETRIEVAL AND GENERATION TASKS

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    Despite incredible advancements in the utilization of learning-based architectures (AI) in natural language and image domains, their applicability to the domain of music has remained limited. In fact, the performance of state-of-the-art Automated Music Transcription (AMT) systems has seen only marginal improvements from novel AI architectures. Moreover, the importance of psychoacoustic perception and its incorporation into MIR systems have mostly stayed addressed, leading to shortcomings in current approaches. This thesis provides an overview of music processing and novel neural architectures, investigates the reasons behind the subpar performance achieved by their utilization in music information retrieval (MIR) tasks, and proposes several ways of adjusting both the music (data-related) pre-processing pipelines, and psychoacoustically-adjusted transformer-based model to improve the performance on MIR and AMT tasks. In particular, a new music transformer architecture is proposed, and various algorithms of music pre-processing for psychoacoustic optimization are implemented along with several adaptive models aimed at addressing the missing factor of modeling human music perception. The preliminary performance results exhibit promising outcomes, warranting the continued investigation of transformer architectures for music information retrieval applications. Several intriguing insights unveiled during the research process are discussed and presented. The thesis concludes by delineating a set of promising future research directions, paving the way for further advancements in the field of music information retrieval and generation using proposed architectures

    Empirically characterizing evolvability and changeability in engineering systems

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012."June 2012." Cataloged from PDF version of thesis.Includes bibliographical references (p. 205-212).The beginning phases of system development and conceptual design require careful consideration, as these decisions will have significant influence on system lifetime performance and are often made with incomplete system knowledge. Decision makers may improve their capacity to discriminate between system concepts and design choices by measuring a system's "ilities" such as changeability, evolvability, and survivability. These ilities may enable systems to respond to perturbations in the design space, context space, and needs space in order to ensure system functionality and adequate performance over time. A system may be designed to change in response to perturbations, or remain statically robust/survivable to perturbations in order to avoid deficiencies or failures. This research attempts to analyze the mechanisms that allow system changes to occur. More specifically, this research will further the characterization of system changeability and evolvability and ultimately provide a structured and meaningful way of classifying system characteristics often described as "ilities". Value sustainment is proposed as an ultimate goal of systems, providing value in spite of perturbations in design, context, or needs. The premise of value sustainment is investigated through four distinct research thrusts: 1) a basis for defining system changes and ilities; 2) a system change examples database with categorical cluster analysis case research; 3) epoch-shift, impact, response, outcome case research; and 4) expert interviews case research. Focusing on change-related ilities, this research proposes constructs for identifying and enabling vague, yet desirable, system properties. Evolvability is characterized as a subset of changeability and defined as the ability of an architecture to be inherited and changed across generations [over time], with a set of ten proposed design principles including decentralization, redundancy, targeted modularity, scalability, integrability, reconfigurability, mimicry, leverage ancestry, disruptive architectural overhaul, and resourceful exaptation.by Jay Clark Beesemyer, Jr.S.M
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