Papers by Dimitri N. Mavris
A multidisciplinary design optimization method applied to stoppable rotor configurations
Recent emphasis in the design and acquisition of complex systems has focused on the requirements ... more 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.
The methodology presented in this paper is concerned with the ability to make informed decisions ... more 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's Short Haul Civil Tiltrotor.
Progress in establishing an analysis package and design/optimization framework for preliminary de... more Progress in establishing an analysis package and design/optimization framework for preliminary design of a civil tiltrotor aircraft is reported. Updates to the sizing/performance program VASCOMP and Equivalent LAminated Plate Solution ELAPS are described. Correlation of this updated ELAPS (now including shear panels) and a state-space unsteady aerodynamic analysis, PWAKE, with reference results from the Automated STRuctural Optimization System, ASTROS, is shown. A generic UNIXbased, flexible executive system for multidisciplinary design/ optimization tasks is presented. The framework features a central data base, provisions for parallel analysis execution on different host computers connected to the same file server, local sensitivity calculation using finite differencing, global sensitivity calculation using the Global Sensitivity Equation (GSE), and a utility allowing different levels of user control. A simple sample case demonstrates proper framework operation and practical advantages in accuracy in the GSE approach versus global finite differencing.
AIAA 4th Aviation Technology, Integration and Operations (ATIO) Forum, 2004
A methodology employing physics-based and economics-based tools in conjunction with probabilistic... more A methodology employing physics-based and economics-based tools in conjunction with probabilistic treatment is developed to study Personal Air Vehicle business model. In the context of the paper, a business model is a mathematical representation of a service provider business operation. Vehicle concepts and hypothesized metrics such as mobility freedom and 'value of time' are embedded in the methodology. Market behavior of the complex transportation environment is captured as part of the equation through Agent-based Modeling and Monte Carlo Simulation techniques. This simulation platform for the transportation environment facilitates the case study of the Atlanta Regional Transportation System. The establishment of this model lays the foundation for creating a robust and adaptive design methodology that allows experts in fields other than aerospace engineering to contribute their expertise towards the realization of this very diverse and dynamic future air transportation system.
Publicreporting burden for thiscollection of information is estimatedto average 1 hour per respon... more Publicreporting burden for thiscollection of information is estimatedto average 1 hour per response, including the time for reviewinginstructions, searchingexistingdata sources, gathering and maintaining the data needed, and completingand reviewing the collectionof information. Send comments regarding his burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports,
In this paper, a problem is studied that extends the motives and goals of multi-"discipline" anal... more In this paper, a problem is studied that extends the motives and goals of multi-"discipline" analysis and design to multi-"system" analysis and design. This transition is important since aerospace engineers and designers are increasingly being posed with "system-of-systems" type problems. Future aviation transportation concepts, future package delivery architectures, and future air-traffic management systems are three prime examples of such emerging system-of-systems. An extension to a novel methodology for conducting design trade-offs is presented, representing a critical part of the system engineering process. The new extension is probabilistic in nature and proceeds under the assumption that both requirement ambiguity and technology uncertainty play a key role in the early design exploration of system-of-systems problems. To simulate the interplay between requirements and technologies, a system-of-systems synthesis capability is needed, to serve in much the same capacity as sizing routines serve in aircraft design. System dynamics modeling, especially including causal loop analysis, is employed for this purpose by representing interaction mechanisms between heterogeneous systems. In this way, the sensitivities of overall system-ofsystems responses to both system and intersystem architecture variables can be computed. After an introduction to the problem and a brief survey of related fields, a detailed description of key elements of a new system-of-systems conceptual design method is presented. An example application problem is introduced as the method is presented to further illustrate the approach. This problem involves the design of a package delivery architecture utilizing autonomous, vertical take-off and landing air vehicles.
2018 AIAA Aerospace Sciences Meeting, 2018
Community noise exposure is the one of the key challenges to the potential growth of the aviation... more Community noise exposure is the one of the key challenges to the potential growth of the aviation industry. Various forecasts have shown that the industry is expected to grow in the future years, and with this comes a predicted increase in noise levels around airports without a significant influx of noise reduction technologies across the fleet. In order to plan for these future scenarios, airports, airlines, the FAA, and local governments must analyze various noise mitigation strategies, operational restrictions, and changes to airport states, whilst still increasing capacity. Thus, it has become important for these entities to be able to rapidly tradeoff different noise mitigation strategies to effectively manage community noise exposure in current and future airport scenarios. However, noise modeling can be a cumbersome task due to the potential for high computational times and its case dependency. Each entity, airport, and community have their own concerns, conditions, and population structure. Current noise modeling software can take multiple hours to set up an airport case study and run a single operational state. REACT, a tradeoff environment developed in this paper, aims to provide the key stakeholders with airport-specific information, an accessible visual user interface, and most importantly, rapid computations. REACT connects the various mitigation strategies and techniques most important to each of the key stakeholders, and allows these authorities to investigate solutions that are most important to them in current and future airport states.
Proceedings of the Asia Pacific Conference of the PHM Society, Jul 14, 2017
This paper introduces a design methodology for resilientbased control reconfiguration of Unmanned... more This paper introduces a design methodology for resilientbased control reconfiguration of Unmanned Autonomous Systems (UAS) when extreme disturbances, such as a largely growing fault or component failure mode occur. It is documented that more than 40% of Class air mishaps are attributed to Unmanned Aerial Vehicles (UAVs). There is an urgent need to improve the operational integrity, resilience and reliability of such critical assets. An optimal control approach with Differential Dynamic Programming (DDP) and Model Predictive Control (MPC) is introduced in this paper as a means for control authority redistribution and reconfiguration; therefore, the system continues performing its mission while compensating for the impact of the extreme disturbances. Prognostic knowledge is considered in a quadratic cost function of the optimal control problem as a soft constraint. A trade-off parameter is introduced between the prognostic constraint and the terminal cost. An autonomous ground operable under-actuated hovercraft is used to demonstrate the efficacy of the proposed reconfiguration strategy, and it is extendable to other cyber physical systems.
Operational and Economic Feasibility of Electric Thin Haul Transportation
17th AIAA Aviation Technology, Integration, and Operations Conference, Jun 5, 2017
UAV Swarms for Migration Flow Monitoring and Search and Rescue Mission Support
2018 AIAA Information Systems-AIAA Infotech @ Aerospace, Jan 7, 2018
AIAA Aviation 2019 Forum, Jun 15, 2019
Novel architectures and technologies carry with them an uncertainty related to their reliability ... more Novel architectures and technologies carry with them an uncertainty related to their reliability and associated safety risk. Existing safety assessment methods involve determining the severity of discrete functional failure and the corresponding probability. However, with the advent of novel aircraft architectural and operational concepts, traditional methods of establishing severity and probabilities failures are found lacking due to the scarcity of available data. The current work proposes a safety assessment method that uses architecture-specific performance models along with continuous functional hazard assessments to inform hazard severity. The probability of failures is determined using a Bayesian framework that does not falter when data is scarce. Taken together, it is expected that this new proposed methodology will enable a more accurate safety assessment of novel aircraft architectures and technologies. A safety assessment of an electric propulsion system powered by a fuel cell is conducted using the proposed methodology to serve as a proof of concept.
Operational and Economic Feasibility of Electric Thin Haul Transportation
17th AIAA Aviation Technology, Integration, and Operations Conference, Jun 5, 2017
AIAA Aviation 2019 Forum, Jun 15, 2019
Airworthiness certification is to ensure the safety of aircraft. With the surge in novel general ... more Airworthiness certification is to ensure the safety of aircraft. With the surge in novel general aviation aircraft configurations and technologies, the Federal Aviation Administration replaced prescriptive design requirements with performance-based airworthiness standards in Federal Aviation Regulations Part 23 that governs the airworthiness of normal category airplane. The amendment ported over the accepted means of compliance (MoC) from prescriptive advisory circulars to a number of consensus standards from aviation community. Because these MoCs are scattered in multiple documents and cross-reference one another, the certification practice with this new format may be cumbersome and time-consuming.This paper proposes a Model-Based System Engineering (MBSE) approach that is envisioned to parametrically transform the document-centric exercise to a model-based process. The approach helps collect the FAR-23 regulations and the associated MoC in an integrated system model along with the relevant mappings between them. This allows users to automatically generate a compliance checklist for any specific certification requirement. Other benefits of the MBSE approach include circular referencing check, automatically propagating any future changes to the FARs or MoC standards through the model, and potential incorporation with early aircraft design.
AIAA Aviation 2019 Forum, Jun 15, 2019
Novel architectures and technologies carry with them an uncertainty related to their reliability ... more Novel architectures and technologies carry with them an uncertainty related to their reliability and associated safety risk. Existing safety assessment methods involve determining the severity of discrete functional failure and the corresponding probability. However, with the advent of novel aircraft architectural and operational concepts, traditional methods of establishing severity and probabilities failures are found lacking due to the scarcity of available data. The current work proposes a safety assessment method that uses architecture-specific performance models along with continuous functional hazard assessments to inform hazard severity. The probability of failures is determined using a Bayesian framework that does not falter when data is scarce. Taken together, it is expected that this new proposed methodology will enable a more accurate safety assessment of novel aircraft architectures and technologies. A safety assessment of an electric propulsion system powered by a fuel cell is conducted using the proposed methodology to serve as a proof of concept.
The authors express their appreciation to the individuals who reviewed drafts of this report, off... more The authors express their appreciation to the individuals who reviewed drafts of this report, offering their thoughtful comments and expert counsel. Following careful examination, we addressed many of these suggestions in this final version. Other suggestions are being considered as part of ongoing development; we will address these suggestions in future documents. This inclusive process is inherent to PARTNER's mission and philosophy. It greatly contributes to the thoroughness of our research, enhancing accuracy, validity, and communication with a broad-based constituency.
AIAA Aviation 2019 Forum, Jun 15, 2019
16th AIAA Aviation Technology, Integration, and Operations Conference, Jun 10, 2016
The thin-haul commuter concept refers to an envisioned class of four to nine passenger aircraft o... more The thin-haul commuter concept refers to an envisioned class of four to nine passenger aircraft operating very short flights and providing scheduled and on-demand air services from smaller airports. Its objective is to enhance regional mobility reach by combining the flexibility of automobile travel with the shorter commute times associated with air travel. To achieve economic viability, the thin-haul commuter concept must provide appreciable economic advantages when compared to current commuter aircraft. This may be achieved by increasing the revenue potential through innovative pricing and scheduling, while drastically reducing operating costs, in particular, energy, maintenance, and labor costs. These ambitious objectives require the infusion of new cutting edge technologies. The use of distributed electric propulsion is investigated to reduce both energy and maintenance expenditures. New avionics systems are considered to enable simplified operations and thus to reduce both labor and training costs. The purpose of this on-going research is to assess the viability of the thin-haul aviation concept by investigating both the operational and economic impact of introducing a fleet of distributed electric propulsion aircraft into the operations of a commuter airline. This paper presents the development of an integrated economics and operations model that incorporates preliminary estimates of a distributed electric propulsion vehicle performance as well as some aspects of typical commuter operator schedules. The model helps compare advanced electric vehicles with more conventional commuters, and therefore enables a preliminary assessment of the expected cost savings.
16th AIAA Aviation Technology, Integration, and Operations Conference, Jun 10, 2016
The thin-haul commuter concept refers to an envisioned class of four to nine passenger aircraft o... more The thin-haul commuter concept refers to an envisioned class of four to nine passenger aircraft operating very short flights and providing scheduled and on-demand air services from smaller airports. Its objective is to enhance regional mobility reach by combining the flexibility of automobile travel with the shorter commute times associated with air travel. To achieve economic viability, the thin-haul commuter concept must provide appreciable economic advantages when compared to current commuter aircraft. This may be achieved by increasing the revenue potential through innovative pricing and scheduling, while drastically reducing operating costs, in particular, energy, maintenance, and labor costs. These ambitious objectives require the infusion of new cutting edge technologies. The use of distributed electric propulsion is investigated to reduce both energy and maintenance expenditures. New avionics systems are considered to enable simplified operations and thus to reduce both labor and training costs. The purpose of this on-going research is to assess the viability of the thin-haul aviation concept by investigating both the operational and economic impact of introducing a fleet of distributed electric propulsion aircraft into the operations of a commuter airline. This paper presents the development of an integrated economics and operations model that incorporates preliminary estimates of a distributed electric propulsion vehicle performance as well as some aspects of typical commuter operator schedules. The model helps compare advanced electric vehicles with more conventional commuters, and therefore enables a preliminary assessment of the expected cost savings.
AIAA Scitech 2021 Forum, Jan 4, 2021
Many research groups have been committed to developing numerical models for weather forecasts. Th... more Many research groups have been committed to developing numerical models for weather forecasts. The models are currently used to predict weather patterns and trends in the aviation industry. In particular, pilots receive wind information predicted by the models and use the forecast to not only calculate how much fuel is needed for a flight but also optimize flight routes by seeking favorable winds. One potential issue is that the models provide relatively coarse wind information in both space and time, which potentially leads to inaccurate calculation of fuel consumption. This research aims to yield a continuous wind prediction model by combining a supervised learning algorithm with the Inverse Distance Weighting technique. Specifically, this research compares three different supervised learning algorithms that include Gaussian Process, Multi-Layer Perceptron, and Support Vector Machine to identify the most appropriate algorithm. The selected algorithm is then compared to a linear interpolation method that is widely used in current flight planning systems for obtaining continuous wind information. A case study is performed with the real Delta Airlines flight 1944 to evaluate the proposed methodology. The results show that 1) the Support Vector Machine provides a better wind prediction compared to the other models, 2) the supervised learning-based regression method performs better than the linear interpolation method in wind predictions, and 3) there are 16 seconds of difference between the real flight (12,117 seconds) and the simulated flight (12,101 seconds) for the cruise portion, indicating that the proposed methodology generates valid results as long as input wind data is provided accurately.
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Papers by Dimitri N. Mavris