Browsing by Author "Riaz, Atif"
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Item Open Access Aircraft systems architecting: a functional-logical domain perspective(American Institute of Aeronautics and Astronautics, 2016-06-17) Guenov, Marin D.; Molina-Cristobal, Arturo; Voloshin, V.; Riaz, Atif; van Heerden, Albert S. J.; Sharma, Sanjiv; Cuiller, C.; Giese, TimPresented is a novel framework for early systems architecture design. The framework defines data structures and algorithms that enable the systems architect to operate interactively and simultaneously in both the functional and logical domains. A prototype software tool, called AirCADia Architect, was implemented, which allowed the framework to be evaluated by practicing aircraft systems architects. The evaluation confirmed that, on the whole, the approach enables the architects to effectively express their creative ideas when synthesizing new architectures while still retaining control over the process.Item Open Access Assessment of structurally-constrained spanloads for span-extended wing design(AIAA, 2024-01-04) Bragado-Aldana, Estela; Riaz, AtifHigh aspect ratio wings are receiving increased attention as a promising solution in pursuit of reducing aviation's environmental impact. To address the challenging trade-off between induced drag and weight, this paper presents an overview of the evaluation of the synthesis of wing aerodynamic and structural requirements for the design of high aspect ratio wings. This is done as a means to improve overall vehicle performance and enlighten the relevant complexities of the design process. A physics-based framework for the conceptual design stage has been composed to produce a set-based design space for the analysis of aircraft with high aspect ratio wings under prescribed aero-structural requirements, integrating state-of-the-art computational models and in-house developed methodologies to create a multi-disciplinary and multi-fidelity design environment. This enables to conduct comparative performance analyses of the proposed concepts relative to a conventional airliner. The impact of such a design approach is assessed at a mission performance level, yielding up to a 30% reduction in structural weight growth with span extension and increasing range-to-weight capabilities by 5%.Item Open Access Assumption management in model-based systems engineering: an aircraft design perspective.(2021-12) El Fassi, Soufiane; Riaz, Atif; Guenov, Marin D.Early design of complex systems is characterised by significant uncertainty due to lack of knowledge, which can impede the design process. In order to proceed with the latter, assumptions are typically introduced to fill knowledge gaps. However, the uncertainty inherent in the assumptions constitutes a risk to be mitigated. In fact, assumptions can negatively impact the system if they turn out to be invalid, such as causing system failure, violation of requirements, or budget and schedule overruns. Within this context, the aim of this research was to develop a computational approach to support assumption management in model-based systems engineering, with an explicit consideration of the uncertainty in assumptions. To achieve the research aim, the objectives were to: (1) devise methods to enable assumption management in a model-based design environment; and (2) devise methods to manage risk of change due to invalid assumptions, with an explicit consideration of both assumptions and margins. The scope was limited to the early stages of aircraft design. To evaluate this research, a demonstration was performed based on two use cases to assess whether the methods work as intended. The developed methods were demonstrated to industry experts in order to obtain feedback on expected usefulness in practice, thus assessing the impact of this research. The experts concluded that the proposed methods are innovative, useful and relevant to industry, where these methods can lead to: (i) fewer undesired iterations, due to earlier identification and management of risks associated with assumptions; and (ii) a better margin balance, due to timely and interactive margin revision. Future work includes further industrial evaluation, extending the research scope and studying the scalability and associated costs of the proposed methods.Item Open Access An assumption network-based approach to support margin allocation and management(Cambridge University Press, 2020-05-31) El Fassi, Soufiane; Guenov, Marin D.; Riaz, AtifPresented is an approach to support margin allocation and management via a graph-theoretical network of assumptions. In contrast to the document-centric approach, the network captures assumptions dependencies, and enables an algorithmic process supporting margin allocation and management. Ultimately, this methodology is intended to assist decision-makers in managing assumptions and examining their impact on an architecture. Explicitly linking margins to assumptions allows to support mitigating their risk of invalidity. The approach is demonstrated with a conceptual aircraft design exampleItem Open Access Building safety into the conceptual design of complex systems. An aircraft systems perspective.(2021-06) Jimeno Altelarrea, Sergio; Guenov, Marin D.; Riaz, AtifSafety is a critical consideration during the design of an aircraft, as it constrains how primary functions of the system can be achieved. It is essential to include safety considerations from early design stages to avoid low-performance solutions or high costs associated with the substantial redesign that is commonly required when the system is found not to be safe at late stages of the design. Additionally, safety is a crucial element in the certification process of aircraft, which requires compliance with safety requirements to be demonstrated. Existing methods for safety assessment are limited in their ability to inform architectural decisions from early design stages. Current techniques often require large amounts of manual work and are not well integrated with other system engineering tools, which translates into increased time to synthesise and analyse architectures, thus reducing the number of alternative architectures that can be studied. This lack of timely safety assessment also results in a situation where safety models evolve at a different pace and become outdated with respect to the architecture definition, which limits their ability to provide valuable feedback. Within this context, the aim is to improve the efficiency and effectiveness of design for safety as an integral part of the systems architecting process. Three objectives are proposed to achieve the stated aim: automate and integrate the hazard assessment process with the systems architecting process; facilitate the interactive introduction of safety principles; and enable a faster assessment of safety and performance of architectures. The scope is restricted to the earlier (conceptual) design stages, the use of model-based systems engineering for systems architecting (RFLP paradigm) and steady-state models for rapid analysis. Regarding the first objective, an enabler to support the generation of safety requirements through hazard assessment was created. The enabler integrates the RFLP architecting process with the System-Theoretic Process Analysis to ensure consistency of the safety assessment and derived safety requirements more efficiently. Concerning the second objective, interactive enablers were developed to support the designer when synthesizing architectures featuring a combination of safety principles such as physical redundancy, functional redundancy, and containment. To ensure consistency and reduce the required amount of work for adding safety, these methods leverage the ability to trace dependencies within the logical view and between the RFLP domains of the architecture. As required by the third objective, methods were developed to automate substantial parts of the creation process of analysis models. In particular, the methods enable rapid obtention of models for Fault Tree Analysis and subsystem sizing considering advanced contextual information such as mission, environment, and system configurations. To evaluate this research, the methods were implemented into AirCADia Architect, an object-oriented architecting tool. The methods were verified and evaluated through their applications to two aircraft-related use cases. The first use case involves the wheel brake systems and the second one involves several subsystems. The results of this study were presented to a group of design specialists from a major airframe manufacturer for evaluation. The experts concluded that the proposed framework allows architects to define and analyse safe architectures faster, thus enabling a more effective and efficient design space exploration during conceptual design.Item Open Access Computational framework for interactive architecting of complex systems(Wiley, 2020-02-17) Guenov, Marin D.; Riaz, Atif; Bile, Yogesh H.; Molina-Cristobal, Arturo; van Heerden, Albert S. J.Presented is a novel framework for interactive systems architecture definition at early design stages. It incorporates graph‐theoretic data structures, entity relationships, and algorithms that enable the systems architect to operate interactively and simultaneously in different domains. It explicitly captures the “zigzagging” of the functional reasoning process, including not only allocated, but also the derived functions. A prototype software tool, AirCADia Architect, was implemented, which allowed the framework to be demonstrated to and tried hands‐on by practicing aircraft systems architects. The tool enables architects to effectively express their ideas when interactively synthesizing new architectures, while still retaining control over the process. The proposed approach was especially acknowledged as the way forward for rationale capture.Item Open Access Conceptual design of a next generation supersonic airliner for low noise and emissions(AIAA, 2023-01-19) Villena Munoz, Cristina; Bonavolontà, Giordana; Lawson, Craig;; Riaz, AtifThe development of an innovative, medium-range supersonic airliner to meet low drag, low emissions and LTO noise requirements is presented in this paper, including a multi-disciplinary design framework targeting firstly to meet at least the current noise regulations for subsonic aircraft during take-off and landing and secondly to reduce the emission levels. The aircraft is designed to fly 4000 nm at Mach 2.2, carrying 100 passengers. The work contributes to the EU SENECA ((LTO) noiSe and EmissioNs of supErsoniC Aircraft) project, which aims to design different SST (SuperSonic Transport) aircraft platforms to investigate the emissions, the noise and the global environmental impact of supersonic aviation. Results from SENECA can support ICAO in the process of creating future certification requirements as well as form legislation guidelines specifically for the future supersonic commercial aircraft. The technical work includes the assessment of different aircraft-engine configurations, in terms of engine number and positions, on typical flight missions. This enables the evaluation of the baseline layouts that represent the best compromise among payload-range capability, aerodynamic performance, weight and noise. A multi-disciplinary airframe-engine integrated design is carried out in order to pursue a comparative analysis focusing on take-off noise for the different aircraft-engine combination platforms. Lastly, the investigation of the potential use of variable noise reduction systems (VNRS), such as a FADEC controlled thrust reduction during take-off, called Programmed Lapse Rate (PLR) is carried out to study their impact in the mitigation of the resultant noise in the airport environment.Item Open Access Conceptual design of supersonic aircraft to investigate environmental impact(AIAA, 2024-01-04) Villena Munoz, Cristina; Lawson, Craig;; Riaz, Atif; Jaron, RobertThe SENECA ((LTO) noiSe and EmissioNs of supErsoniC Aircraft) project, funded under the EU Horizon 2020 framework, is dedicated to the exploration of future designs for supersonic business jets and supersonic commercial airliners, placing significant emphasis on minimising landing and take-off noise and mitigating emissions. The research outcomes are intended to inform discussions at ICAO level, providing scientific support to enhance the European perspective on regulatory requirements for novel supersonic aircraft. The overall aim of the research is the development of four different supersonic transport aircraft platforms, comprising both airframes and engines design. These aircraft configurations range from supersonic business jets, designed for cruise Mach numbers of 1.4 and 1.6, to large airliners capable of accommodating 100 passengers, with cruise Mach numbers of 1.8 and 2.2. In pursuit of the next generation of environmentally sustainable supersonic civil aircraft, the research employs a multi-disciplinary design optimisation strategy. This strategy primarily focuses on meeting the current noise regulations for subsonic aircraft during landing and take-off and secondly on reducing emissions levels. This paper details the conceptual development of the platforms specifications for the four supersonic aircraft designed within SENECA project. These specifications include geometrical and configuration data, performance characteristics, as well as mission trajectories and profiles.Item Open Access Data Supporting "Managing Assumption-Driven Design Change via Margin Allocation and Trade-offs"(Cranfield University, 2023-10-24 15:45) Chen, Xin; El Fassi, Soufiane; Riaz, Atif; Guenov, Marin; Van heerden, Albert; Jimeno Altelarrea, SergioResults of design of experiment study produced in "Managing Assumption-Driven Design Change via Margin Allocation and Trade-offs". Presented as Figures 16, 17, and 18 in the paper.Item Open Access Data supporting "Set Based Design Techniques for Evolvability Exploration During Conceptual Aircraft Design”(Cranfield University, 2024-09-19) Jimeno Altelarrea, Sergio; Riaz, Atif; van Heerden, Albert S.J.; Chen, XinItem Open Access Efficient method for variance-based sensitivity analysis(Elsevier, 2018-07-05) Chen, Xin; Molina-Cristobal, Arturo; Guenov, Marin D.; Riaz, AtifPresented is an efficient method for variance-based sensitivity analysis. It provides a general approach to transforming a sensitivity problem into one uncertainty propagation process, so that various existing approximation techniques (for uncertainty propagation) can be applied to speed up the computation. In this paper, formulations are deduced to implement the proposed approach with one specific technique named Univariate Reduced Quadrature (URQ). This implementation was evaluated with a number of numerical test-cases. Comparison with the traditional (benchmark) Monte Carlo approach demonstrated the accuracy and efficiency of the proposed method, which performs particularly well on the linear models, and reasonably well on most non-linear models. The current limitations with regard to non-linearity are mainly due to the limitations of the URQ method used.Item Open Access Enabling interactive safety and performance trade-offs in early airframe systems design(AIAA, 2020-01-05) Jimeno, Sergio; Riaz, Atif; Guenov, Marin D.; Molina-Cristobal, ArturoPresented is a novel interactive framework for incorporating both safety and performance analyses in early systems architecture design, thus allowing the study of possible trade-offs. Traditionally, a systems architecture is first defined by the architects and then passed to experts, who manually create artefacts such as Fault Tree Analysis (FTA) for safety assessment, or computational workflows, for performance assessment. The downside of this manual approach is that if the architect modifies the systems architecture, most of the process needs to be repeated, which is tedious and time consuming. This limits the exploration of the design space, with the associated risk of missing better architectures. To overcome this limitation, the proposed framework automates parts of the safety and performance analysis in the context of the Requirement, Functional, Logical, and Physical (RFLP) systems engineering paradigm. Safety analysis is carried out by automatic creation of FTA models from the functional and logical flow views. Regarding performance analysis, computational workflows are first automatically created from the logical flow view, and then executed for a set of flight conditions over the range of the mission in order to determine the most demanding condition. Finally, performance characteristics of the subsystems, such as weights, power offtakes, ram drag etc. are evaluated at the most demanding flight condition, which enables the architect to compare architectures at aircraft level. The framework is illustrated with a representative example involving the design of an environmental control system of a civil aircraft, where the safety and performance trade-off is conducted for multiple ECS architectures.Item Open Access Evaluation of a collaborative and distributed aircraft design environment, enabled by microservices and cloud computing(AIAA, 2023-01-19) Chen, Xin; Isoldi, Adriano; Riaz, Atif; Mourouzidis, Christos; Keskin, Akin; Smith, Dale; Guenov, Marin D.; Pachidis, VassiliosPresented in this paper are the outcomes from the evaluation of a distributed aircraft design environment, based on microservices and cloud computing. The evaluation was performed on a representative airframe-engine optimization case study, including the engine, wing aero-structural geometry, and high-lift devices. The (computational) design process involved multiple distributed design teams and design tools. The latter were implemented with different programming languages and deployed on the Azure cloud service. As a benchmark, the same case study was performed using the traditional email/document-based approach to design collaboration. Compared with the traditional collaboration, the cloud-based approach substantially reduced the time for design iterations between the design teams. This was mainly due to the fast remote access of models/tools on the cloud and automation of data exchange. Also, the exercise indicated that the cloud-based approach is more flexible with regard to orchestrating the computational workflows and optimization studies, while protecting the Intellectual Property (IP) of the collaborating partners.Item Open Access Framework for multi-fidelity assessment of open rotor propeller aeroacoustics(AIAA, 2024-05-30) Huang, Guangyuan; Sharma, Ankit; Chen, Xin; Riaz, Atif; Jefferson-Loveday, RichardAerodynamically generated noise from open rotor aircraft has received immense research interests. Multi-fidelity numerical approaches are in demand for evaluating open rotor propeller noise without compromising computational accuracy and reducing cost. In this paper, propeller noise modelling methods at different fidelity levels are assessed by application to an aircraft propeller configuration at an advance ratio of 0.485 together with tip Reynolds and Mach numbers of 3.7×10^5 and 0.231, respectively. The flow solution of the propeller is obtained using coarse-grid Large Eddy Simulation and then inputted into three acoustic solvers. At higher-fidelity level, Ffowcs-Williams and Hawkings analogy method is employed. Hanson’s method and Gutin’s method are applied at the medium- and lower -fidelity levels, respectively. Results from the three models are compared correlatively, as well as against existing experimental measurement data. Through the assessment, insight is given into future development of a multi-fidelity model for low-emission open rotor aircraft design. The presented multi-fidelity framework is being developed as part of the Innovate UK, Aerospace Technology Institute (ATI) funded research project – ONEheart (Out of Cycle NExt generation highly efficient air transport).Item Open Access Incorporating safety in early (airframe) systems design and assessment(AIAA, 2019-01-14) Jimeno, Sergio; Molina-Cristobal, Arturo; Riaz, Atif; Guenov, Marin D.Presented is a novel framework for incorporating safety analysis in early systems architecture design.Traditionally, a systems architecture is first defined by the architects and then passed to safety experts, who manually create artefacts such as Function Hazard Analysis (FHA) or Fault Tree Analysis (FTA) for safety assessment. The problem with this manual approach is that if the architect modifies the systems architecture, then the whole safety assessment process needs to be repeated, which is tedious and time consuming. To overcome this limitation, the proposed framework automates the creation of safety models such as FHA and FTA by utilizing the Requirement, Functional, Logical, and Physical (RFLP) systems engineering paradigm. The framework supports three main activities. First, the safety targets are determined by performing a FHA of the architecture and the Requirements view is updated. Second, compliance with the safety requirements is analyzed using dynamic fault trees, automatically generated from the Logical view. Interactive visualization techniques are proposed to interpret the safety results, e.g. highlighting the greatest contributors to the probability of failure. Third, an algorithm is developed that enables the designer to interactively improve the architecture’s safety by introducing more reliable components or increasing redundancy. The concept is illustrated with a representative example, where the environmental control system of a civil aircraft is studied from a safety point of view.Item Open Access Interactive uncertainty allocation and trade-off at early-stage aircraft computational design(AIAA, 2018-01-13) Molina-Cristobal, Arturo; Guenov, Marin D.; Riaz, Atif; van Heerden, Albert S. J.A common probabilistic approach to uncertainty allocation is to assign acceptable variability in the sources of uncertainty, such that pre-specified probabilities of meeting performance constraints are satisfied. However, the computational cost of obtaining the associated trade-offs increases significantly when more sources of uncertainty and more outputs are considered. Consequently, visualizing and exploring the trade-off space becomes increasingly difficult, which, in turn, makes the decision-making process cumbersome for practicing designers. To tackle this problem, proposed is a parameterization of the input probability distribution functions, to account for several statistical moments. This, combined with efficient uncertainty propagation and inverse computation techniques, results in a computational system which performs order(s) of magnitude faster, compared with a combination of Monte Carlo Simulation and optimization techniques. Also, to aid decision-making regarding the potential combinations of uncertainty allocation, enablers for visualizing the trade space are proposed. The combined approach is demonstrated by means of a representative aircraft thermal system integration example.Item Open Access Interactive uncertainty allocation and tradeoff for early-stage design of complex systems(AIAA, 2019-11-20) Molina-Cristobal, Arturo; Chen, Xin; Guenov, Marin D.; Riaz, Atif; van Heerden, Albert S. J.A common probabilistic approach to perform uncertainty allocation is to assign acceptable variability in the sources of uncertainty, such that prespecified probabilities of meeting performance constraints are satisfied. However, the computational cost of obtaining the associated tradeoffs increases significantly when more sources of uncertainty and more outputs are considered. Consequently, visualizing and exploring the decision (trade) space becomes increasingly difficult, which, in turn, makes the decision-making process cumbersome for practicing designers. To address this problem, proposed is a parameterization of the input probability distribution functions, to account for several statistical moments. This, combined with efficient uncertainty propagation and inverse computation techniques, results in a computational system that performs order(s) of magnitude faster than a state-of-the-art optimization technique. The approach is demonstrated by means of an illustrative example and a representative aircraft thermal system integration example.Item Open Access Managing assumption-driven design change via margin allocation and trade-offs(Taylor and Francis, 2023-10-11) El Fassi, Soufiane; Chen, Xin; Riaz, Atif; Guenov, Marin D.; van Heerden, Albert S. J.; Jimeno Altelarrea, SergioAssumptions are commonly introduced to fill gaps in knowledge during the engineering design process. However, the uncertainty inherent in these assumptions constitutes a risk that ought to be mitigated. That is, assumptions can negatively impact the system if they turn out to be invalid. Adverse effects may include system failure, violation of requirements, or budget and schedule overruns. In this paper, the relationships between assumptions and margins are made explicit, with the purpose of aiding risk mitigation, as well as accommodating future opportunities such as product evolvability. To this end, a novel assumption management framework is proposed, which consists of a taxonomy of margins, an algorithm for change absorber localisation, and an interactive approach for margin trade-off. The proposed framework is demonstrated with a conceptual aircraft design use case, which shows that the most relevant margins can be identified, given a revision of a set of assumptions. It is also demonstrated that the application of the method allowed the margins to be adjusted according to the confidence in the assumptions, while maintaining satisfaction of all design constraints, without unacceptable compromise of system performance.Item Open Access Margin allocation and trade-off in complex systems design and optimization(AIAA, 2018-05-01) Guenov, Marin D.; Chen, Xin; Molina-Cristobal, Arturo; Riaz, Atif; van Heerden, Albert S. J.Presented is an approach for interactive margin management. Existing methods enable a fixed set of allowable margin combinations to be identified, but these have limitations with regard to supporting interactive exploration of the effects of: 1) margins on other margins, 2) margins on performance and 3) margins on the probabilities of constraint satisfaction. To this purpose, the concept of a margin space is introduced. It is bi-directionally linked to the design space, to enable the designer to understand how assigning margins on certain parameters limits the allowable margins that can be assigned to other parameters. Also, a novel framework has been developed. It incorporates the margin space concept as well as enablers, including interactive visualization techniques, which can aide the designer to explore the margin and design spaces dynamically, as well as the effects of margins on the probability of constraint satisfaction and on performance. The framework was implemented into a prototype software tool, AirCADia, which was used for a qualitative evaluation by practicing designers. The evaluation, conducted as part of the EU TOICA project, demonstrated the usefulness of the approach.Item Open Access On wings with non-elliptic lift distributions(ICAS, 2021-09-10) Bragado-Aldana, Estela; Lone, Mudassir; Riaz, AtifNon-elliptic lift distributions were originally conceived by Prandtl as a solution for wings having optimal aerodynamic and structural efficiency. Since 1933, many researchers have expanded on this theory to confirm that it explicitly facilitates the trade-off between induced drag and weight, and have unveiled other potential benefits such as proverse yaw. This theory is seen as a promising alternative to redefine the underlying principles of conceptual wing design in the search for a step increase in efficiency. Given the recent revival of this approach, in this paper the authors present a concise review of its theoretical basis, the developments carried out in this area and their relevance to the future of aviation.