Multidisciplinary Design Optimization of Electric Aircraft Considering Systems Modeling and Packaging

Electric aircraft propulsion is an intriguing path towards sustainable aviation, but the technological challenges are significant. Bulky and heavy electrical components such as batteries create spatial integration and aircraft performance challenges, especially for longer-range aircraft. A common thread among all aircraft with electric propulsion is the close coupling of aircraft design disciplines, such as aerodynamics, structures, propulsion, controls, and thermal management. Multidisciplinary design optimization (MDO) is a promising technique for solving design problems with many closely-coupled physical disciplines. The first half of this dissertation focuses on MDO of electric aircraft considering systems modeling. First, design of electric aircraft is reviewed in detail from the perspective of the various disciplines. Next, methods and models for electric aircraft propulsion systems are introduced. A case study involving a general aviation airplane is explored in order to validate the performance of the methods and generate some insight into the tradespace for series hybrid aircraft. The systems modeling approach is then extended to include basic thermal management systems. The prior case study is revisisted while considering thermal constraints. Impact of thermal management on aircraft performance is assessed. The thermal management analysis methods are validated using flight test data from the Pipistrel Velis Electro, finding good agreement between experiment and simulation. Finally, an MDO model of a parallel hybrid electric transport aircraft with a liquid-cooled thermal management system is constructed. Sensitivities of aircraft performance with respect to important technologies parameters are computed. This first half introduces the first publicly-available simulation tool that can handle unsteady thermal states and that offers efficient and accurate gradients. The methods are very efficient, enabling users to perform dozens or hundreds of optimization runs in a short amount of time using modest computational resources. Other novel contributions include the first empirical validation of thermal management models for MDO against real flight test data, as well as the only comprehensive look so far at the unsteady thermal management of a transport-scale parallel hybrid aircraft. The second half of the dissertation introduces novel methods for performing high-fidelity shape optimization studies subject to packaging or spatial integration constraints. A new mathematical formulation for generalized packaging constraints is introduced. The constraint formulation is demonstrated on simple aerodynamic shape optimization test cases. Next, a wing design study involving optimal battery packaging is conducted in order to demonstrate the coupling of outer mold line design and propulsion system component design via spatial integration. Finally, a more complex aerostructural optimization involving the wing of a hydrogen aircraft is constructed and solved. These test cases demonstrate the interdisciplinary coupling introduced by packaging constraints, as well as the impact of spatial integration on aircraft performance. This latter half contributes a powerful new way for MDO engineers to pose realistic spatial constraints in their shape optimization problems, thus solving an important practical barrier to the industrial adoption of MDO for certain relevant problems. This work also represents the first time an MDO problem has been posed and solved for an aircraft using hydrogen fuel in the wing. Altogether, this dissertation significantly advances the state of the art in modeling, simulation, and optimization tools for aircraft with electric propulsion architectures and introduces new insights into the design spaces for several diverse aircraft configurations.PHDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169658/1/bbrelje_1.pd

Methodology for sizing and optimising a Blended Wing-Body with distributed electric ducted fans

The increase of air traffic in the last decades and its projections pose a key challenge towards the carbon neutral growth objective. To cope with this societal goal, there is a need for disruptive air transport aircraft concepts featuring new technologies with low environmental impact. Such future air vehicle relies on the various interactions between systems, disciplines and components. This Ph.D. research thus focuses on the development of a methodology dedicated to the exploration and performance evaluation of unconventional configurations using innovative propulsion concepts. The use case to be considered is the optimisation at conceptual level of a Blended Wing-Body with distributed electric propulsion, a promising concept which combines high aerodynamic performances and benefits from electric propulsion. The optimisation process based on FAST, the ISAE-SUPAERO / ONERA aircraft sizing tool, has been implemented within OpenMDAO, the NASA open-source multidisciplinary analysis and optimisation framework. With the idea of a progressive enhancement of the multidisciplinary design analysis and a better capture of the different effects, the two pioneering elements have been studied separately. First, the classical process has been revised to take into account the new hybrid powerplant. Second, a methodology has been revised to consider a radically new airframe design. Last, a design process featuring both innovative aspects has been developed to investigate a Blended Wing Body concept with distributed electric propulsion. Concerning the design process, results show that the use of gradients in the optimisation procedure speeds up the process against a gradient-free method up to 70%. This is an important gain in time that facilitates designer’s tasks. For the disruptive concept performances, results have been compared to the ones obtained for a conventional A320 type aircraft based on the same top level requirements and technological horizon. Overall, the hybrid electric propulsion concept is interesting as it allows zero emissions for Landing/Take-Off operations, improving the environmental footprint of the aircraft: fuel can be saved for missions below a certain range. This limitation is associated to the presence of batteries: indeed they introduce indeed a relevant penalty in weight that cannot be countered by benefits of electrification for longer range. Additional simulations indicate that a Blended Wing-Body concept based on a turbo-electric only architecture is constantly performing better than the baseline within the limits of the assumptions

A Methodology for Capturing the Aero-Propulsive Coupling Characteristics of Boundary Layer Ingesting Aircraft in Conceptual Design

Economic and environmental benefits of fuel efficient aircraft have driven research towards unconventional configurations and technologies. Boundary Layer Ingesting (BLI) concepts appear to be a promising solution, relying on a synergistic interaction between the airframe and propulsor for improved fuel efficiency. Maximizing benefits of BLI while minimizing the risks not only involves careful design of the propulsor, but also the airframe given that the embedded propulsor performance is dependent on the ingested boundary layer flow, which in turn is affected by the airframe. The highly coupled nature of the propulsion system with the airframe for BLI concepts requires a Multidisciplinary Design Analysis and Optimization (MDAO) approach. Majority of the modeling approaches in literature, however, have treated the BLI problem in a decoupled fashion, especially at the vehicle sizing stage. On the other hand, coupled aero-propulsive methodologies proposed are better suited for point design refinement at the preliminary design stage. Decoupled methods fail to capture aero-propulsive interactions. The impacts of BLI may be overestimated or underestimated, and thus, there is a risk that the sized vehicle will not be satisfactory or even feasible. Quantifying the consequences of ignoring BLI aero-propulsive coupling at the aircraft sizing stage is the primary motivation of this research effort. To address this aspect, a parametric and coupled aero-propulsive design and analysis methodology that is appropriate for conceptual design BLI vehicle sizing and corresponding trade studies is necessary. A MDAO methodology for BLI aircraft in conceptual design is proposed, allowing for design space exploration and simultaneous optimization of the airframe and propulsor cycle. BLI effects on vehicle performance are identified using the Power Balance formulation. Studies are devised to identify the critical airframe and propulsor design space influencing these BLI effects. Through physics based reasoning, these studies provide rule of thumb guidelines for concept designers to focus on certain design parameters over others. High fidelity aerodynamic analysis, through CFD, is used strategically for constructing parametric semi-empirical models of the BLI effects, which are then integrated with a cycle analysis code, an aircraft sizing and mission analysis tool, and other analysis modules in a MDAO environment. A fine balance is thus achieved between high fidelity requirements for modeling complex physics and the need for expedited MDAO in conceptual design. The proposed method is applied to the design and analysis of two tube and wing BLI configurations with different engine locations, similar to the D8 and NOVA-BLI concepts. These vehicles are also designed using a decoupled approach that is reflective of similar methods in literature. A design space exploration involving engine cycle and airframe design parameters is conducted, using the decoupled and coupled approaches, followed by optimization to find the best designs within the specified constraints. The studies show noteworthy differences in performance and design trends between the two BLI modeling approaches. Additionally, the wing influence on the ingested airflow is observed to affect the BLI aero-propulsive coupling strength. The top-mounted engine configuration like the D8 exhibits stronger coupling compared to the side-mounted engine variant like the NOVA-BLI. In general, the results support use of coupled and parametric methodologies for BLI concept design.Ph.D

A Comprehensive Survey on Deep Learning Techniques in Educational Data Mining

Educational Data Mining (EDM) has emerged as a vital field of research, which harnesses the power of computational techniques to analyze educational data. With the increasing complexity and diversity of educational data, Deep Learning techniques have shown significant advantages in addressing the challenges associated with analyzing and modeling this data. This survey aims to systematically review the state-of-the-art in EDM with Deep Learning. We begin by providing a brief introduction to EDM and Deep Learning, highlighting their relevance in the context of modern education. Next, we present a detailed review of Deep Learning techniques applied in four typical educational scenarios, including knowledge tracing, undesirable student detecting, performance prediction, and personalized recommendation. Furthermore, a comprehensive overview of public datasets and processing tools for EDM is provided. Finally, we point out emerging trends and future directions in this research area.Comment: 21 pages, 5 figure

Scaffolding Human Champions: AI as a More Competent Other

Artifcial intelligence (AI) has surpassed humans in a number of specialised intellectual activities—chess and Go being two of many examples. Amongst the many potential consequences of such a development, I focus on how we can utilise cutting edge AI to promote human learning. The purpose of this article is to explore how a specialised AI can be utilised in a manner that promotes human growth by acting as a tutor to our champions. A framework for using AI as a tutor of human champions based on Vygotsky’s theory of human learning is here presented. It is based on a philosophical analysis of AI capabilities, key aspects of Vygotsky’s theory of human learning, and existing research on intelligent tutoring systems. The main method employed is the theoretical development of a generalised framework for AI powered expert learning systems, using chess and Go as examples. In addition to this, data from public interviews with top professionals in the games of chess and Go are used to examine the feasibility and realism of using AI in such a manner. Basing the analysis on Vygotsky’s socio-cultural theory of development, I explain how AI operates in the zone of proximal development of our champions and how even non-educational AI systems can perform certain scafolding functions. I then argue that AI combined with basic modules from intelligent tutoring systems could perform even more scafolding functions, but that the most interesting constellation right now is scafolding by a group consisting of AI in combination with human peers and instructors.publishedVersio

Research & scholarly achievements, July 1, 1985 - June 30, 1986

Annual summary of scholarly activities at UCF for the period from July 1, 1985 to June 30, 1986. This report highlights the contributions to scholarship by the Faculty during this period, including books and monographs, articles, creative works, presentations, grants and contracts

Authenticity and cultural heritage in the age of 3D digital reproductions

This volume represents the first attempt to collate an organic collection of contributions on authenticity and the digital realm in heritage and archaeology. It analyses the concept of authenticity from different perspectives and with different multidisciplinary contributions, together with theoretical debate. The collection of papers explores the concept of authenticity in a comprehensive way, engaging with theories relating to the commodification of ancient material culture, heritage-making processes, scholarly views and community engagement. These papers also take into account current digital practices for the study of past material culture and how their use affects and redefines interpretation processes in archaeology. This will provide a key reference text for archaeologists, museum and heritage specialists, and other readers interested in authenticity, cultural heritage and 3D reproductions.This book was funded by the EU 7th Framework Programme (7FP), DIGIFACT 625637 Project (http://cordis.europa.eu/project/rcn/187953_ en.html) and ADS3DV 625636 Project (http://cordis.europa.eu/project/ rcn/187952_en.html). The book will be Open Access, thanks to FP7 post-grant Open Access (https://www.openaire.eu/postgrantoapilot)

10th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens

This Special Issue book contains selected papers from works presented at the 10th EASN (European Aeronautics Science Network) International Conference on Innovation in Aviation & Space, which was held from the 2nd until the 4th of September, 2020. About 350 remote participants contributed to a high-level scientific gathering providing some of the latest research results on the topic, as well as some of the latest relevant technological advancements. Eleven interesting articles, which cover a wide range of topics including characterization, analysis and design, as well as numerical simulation, are contained in this Special Issue