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1 – 10 of 19
Article
Publication date: 6 March 2017

Mengmeng Zhang and Arthur Rizzi

A collaborative design environment is needed for multidisciplinary design optimization (MDO) process, based on all the modules those for different design/analysis disciplines, and…

387

Abstract

Purpose

A collaborative design environment is needed for multidisciplinary design optimization (MDO) process, based on all the modules those for different design/analysis disciplines, and a systematic coupling should be made to carry out aerodynamic shape optimization (ASO), which is an important part of MDO.

Design/methodology/approach

Computerized environment for aircraft synthesis and integrated optimization methods (CEASIOM)-ASO is developed based on loosely coupling all the existing modules of CEASIOM by MATLAB scripts. The optimization problem is broken down into small sub-problems, which is called “sequential design approach”, allowing the engineer in the loop.

Findings

CEASIOM-ASO shows excellent design abilities on the test case of designing a blended wing body flying in transonic speed, with around 45 per cent drag reduction and all the constraints fulfilled.

Practical implications

Authors built a complete and systematic technique for aerodynamic wing shape optimization based on the existing computational design framework CEASIOM, from geometry parametrization, meshing to optimization.

Originality/value

CEASIOM-ASO provides an optimization technique with loosely coupled modules in CEASIOM design framework, allowing engineer in the loop to follow the “sequential approach” of the design, which is less “myopic” than sticking to gradient-based optimization for the whole process. Meanwhile, it is easily to be parallelized.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

Open Access
Article
Publication date: 8 May 2018

Aidan Jungo, Mengmeng Zhang, Jan B. Vos and Arthur Rizzi

The purpose of this paper is to present the status of the on-going development of the new computerized environment for aircraft synthesis and integrated optimization methods…

2157

Abstract

Purpose

The purpose of this paper is to present the status of the on-going development of the new computerized environment for aircraft synthesis and integrated optimization methods (CEASIOM) and to compare results of different aerodynamic tools. The concurrent design of aircraft is an extremely interdisciplinary activity incorporating simultaneous consideration of complex, tightly coupled systems, functions and requirements. The design task is to achieve an optimal integration of all components into an efficient, robust and reliable aircraft with high performance that can be manufactured with low technical and financial risks, and has an affordable life-cycle cost.

Design/methodology/approach

CEASIOM (www.ceasiom.com) is a framework that integrates discipline-specific tools like computer-aided design, mesh generation, computational fluid dynamics (CFD), stability and control analysis and structural analysis, all for the purpose of aircraft conceptual design.

Findings

A new CEASIOM version is under development within EU Project AGILE (www.agile-project.eu), by adopting the CPACS XML data-format for representation of all design data pertaining to the aircraft under development.

Research limitations/implications

Results obtained from different methods have been compared and analyzed. Some differences have been observed; however, they are mainly due to the different physical modelizations that are used by each of these methods.

Originality/value

This paper summarizes the current status of the development of the new CEASIOM software, in particular for the following modules: CPACS file visualizer and editor CPACSupdater (Matlab) Automatic unstructured (Euler) & hybrid (RANS) mesh generation by sumo Multi-fidelity CFD solvers: Digital Datcom (Empirical), Tornado (VLM), Edge-Euler & SU2-Euler, Edge-RANS & SU2-RANS Data fusion tool: aerodynamic coefficients fusion from variable fidelity CFD tools above to compile complete aero-table for flight analysis and simulation.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 March 1986

Arthur Rizzi and Charles J. Purcell

A numerical method that solves the Euler equations for compressible flow is used to study vortex stretching. The particular case simulated is supersonic flow M∞=1.2 α=10 degrees…

Abstract

A numerical method that solves the Euler equations for compressible flow is used to study vortex stretching. The particular case simulated is supersonic flow M∞=1.2 α=10 degrees around the twisted and cambered cranked‐and‐cropped TKF delta wing of MBB. This geometry induces multiple leading‐edge vortices in a straining velocity field that brings about flow instabilities but the result is a state of statistical equilibrium. The discretization contains over 600,000 cells and offers sufficient degrees of freedom in the solution to resolve the small‐scale unstable modes that lead to disordered vortex flow.

Details

Engineering Computations, vol. 3 no. 3
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 1 January 1985

Arthur Rizzi and Charles J. Purcell

The large‐scale numerical simulation of fluid flow is described as a discipline within the field of software engineering. As an example of such work, a vortex flowfield is…

Abstract

The large‐scale numerical simulation of fluid flow is described as a discipline within the field of software engineering. As an example of such work, a vortex flowfield is analysed for its essential physical flow features, an appropriate mathematical description is presented (the Euler equations with an artificial viscosity model), a numerical algorithm to solve the mathematical equations is described, and the programming methodology which allows us to attain a very high degree of vectorization on the CYBER 205 is discussed. Four simulated flowfields with vorticity shed from wing edges are computed with up to as many as one million grid points and verify the realism of the simulation model. The computed solutions show all the qualitative features that are expected in these flows. The twisted cranked‐and‐cropped delta case is one where the leading‐edge vortex is highly stretched and unstable, displaying ultimately inviscid large‐scale turbulent‐like phenomena.

Details

Engineering Computations, vol. 2 no. 1
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 4 May 2012

Mengmeng Zhang and Arthur Rizzi

The goal for this paper is to bring the easy‐to‐use geometry drawing software RDS to a “solid” mesh, which could be analyzed and simulated in CEASIOM, to enhance both CEASIOM and…

Abstract

Purpose

The goal for this paper is to bring the easy‐to‐use geometry drawing software RDS to a “solid” mesh, which could be analyzed and simulated in CEASIOM, to enhance both CEASIOM and RDS's capabilities.

Design/methodology/approach

The RDSSUMO interface is developed based on the feature that both RDS and SUMO define their geometric model using cross‐sectional information, i.e. their “universe” shapes are close to each other.

Findings

The translation is automated and allows the engineer to easily modify and augment the geometry in the process. Two test cases are shown, with their high quality Euler mesh and CFD computations. The A321‐look‐alike test case tests the mesh quality for transonic aerodynamics, such as high‐speed trim and drag divergence; the twin‐prop asymmetric aircraft is a “diffi+cult” non‐conventional configuration analyzed for yaw stability in one‐engine out mode.

Practical implications

This paper shows that the CFD solutions based on solid grids could be obtained once the design is proposed and the RDS wire‐frame model is available. The aerodynamic properties can then be predicted in early design stage, which is very efficient for preliminary aircraft design.

Originality/value

This fast meshing tool could obtain “working” grids of a new design within hours.

Details

Aircraft Engineering and Aerospace Technology, vol. 84 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Content available
Article
Publication date: 4 May 2012

Askin T. Isikveren

385

Abstract

Details

Aircraft Engineering and Aerospace Technology, vol. 84 no. 3
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 May 1981

Monday, February 23, 1981. A British cargo flight crashed near Billerica, Massachusetts, after the aircraft took off with an accumulation of ice and snow on the airframe and then…

Abstract

Monday, February 23, 1981. A British cargo flight crashed near Billerica, Massachusetts, after the aircraft took off with an accumulation of ice and snow on the airframe and then encountered moderate to severe icing conditions in flight.

Details

Aircraft Engineering and Aerospace Technology, vol. 53 no. 5
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 February 1990

Marjorie T. Stanley

The concept of a company's cost of capital is used in capital budgeting as a potential basic discount rate to be applied to expected future cash flows from a proposed investment…

Abstract

The concept of a company's cost of capital is used in capital budgeting as a potential basic discount rate to be applied to expected future cash flows from a proposed investment project being subjected to evaluation for acceptance or rejection. Discounted‐cash‐flow capital budgeting techniques derive from valuation theory that determines present value of expected future cash flows by discounting them down to the present at a discount rate appropriate to the degree of risk involved. Conceptually, this is true with regard to both domestic investment and foreign direct investment. However, there is recognition in the literature that capital budgeting for foreign direct investment decisions may involve complexities not present in the domestic case. These include economic, financial, and political factors, and related risks, e.g., foreign exchange risk, blocked currencies, expropriation. On the other hand, foreign direct investment is thought to provide diversification benefits, so that risks that are not domestically diversifiable are internationally diversifiable, thereby eliminating some otherwise systematic risk. Complexities such as these place a considerable burden upon the concept of cost of capital as a discount rate appropriately reflective of the degree of risk involved in a foreign direct investment project. Furthermore, cost of capital may be affected by environmental factors associated with what country the parent corporation calls “home” (Stonehill and Dullum).

Details

Managerial Finance, vol. 16 no. 2
Type: Research Article
ISSN: 0307-4358

Article
Publication date: 28 May 2021

Robert Stewart

The purpose of this study is to demonstrate that the internal ratings-based (IRB) approach provides more effective risk discrimination than the standardized approach when…

Abstract

Purpose

The purpose of this study is to demonstrate that the internal ratings-based (IRB) approach provides more effective risk discrimination than the standardized approach when calculating regulatory capital for retail credit risk exposures.

Design/methodology/approach

The author uses four retail credit data sets to compare regulatory capital appropriation using the IRB approach and the standardized approach. The author follows the regulatory capital calculation method recommended under Basel III. For the IRB approach, the author uses a logistic regression to determine the probability of default.

Findings

The results suggest that the IRB approach provides more effective risk discrimination across individual exposures, which allows more regulatory capital to be held against riskier exposures and less regulatory capital to be held against less risky exposures. The author further argues that the Basel III output floor, as presently constructed, may disincentivize the use of the IRB approach and further diminish the value of secured lending under the IRB approach. To address this issue, the author offers two simple adjustments to the current design of the output floor.

Originality/value

While studies have argued the idea of risk-sensitive regulatory capital, the author has not observed any research that empirically compares the risk-sensitivity of regulatory capital across retail credit exposures, which makes up a significant portion of many banks’ credit exposures. This study also highlights what appears to be a major point of concern for the output floor, which is set to be phased in starting January 2022. This is of particular value because this point has not appeared to receive any attention in the literature thus far.

Article
Publication date: 18 January 2021

Ananya Sheth and Joseph Victor Sinfield

Problem specification is a key front-end step in the innovation process. This paper aims to introduce ‘purpose-context’ – a conceptual framework to systematically explore…

Abstract

Purpose

Problem specification is a key front-end step in the innovation process. This paper aims to introduce ‘purpose-context’ – a conceptual framework to systematically explore problem-specification across mapped contexts. The framework’s logic is operationalized by the inherent structure of language – its syntax/grammar, which enables the systematic exploration of problem-specification. The method showcases two approaches to structurally explore the vast textual databases available to us today for problem-specification in innovation science, thereby furthering the pursuit of innovation through its foundational elements.

Design/methodology/approach

The conceptualization of the purpose-context framework was guided by logic and the scholarship of integration applied to bodies of work including innovation, design and linguistics. Further, the key elements of the conceptual framework were unpacked and structured using the syntax of language. Two approaches to operationalize the method were developed to illustrate the systematicity of the process. The construct was then validated by using it to systematically specify problems in the technical context of Raman spectroscopy and in the socio-technical context of international development. Overall, this paper is a work of relational scholarship of integration that bridges academic-practitioner gaps.

Findings

The purpose-context framework is well-suited for application in the innovation process with applicability across several abstraction levels. One key contribution is the recognition that a broader problem-specification exercise covering one-one, one-many, many-one, many-many problem-context mappings expands the range of potential solutions (innovations) to address the problem-space. Additionally, the work finds that it is possible to provide structure to the cognitive elements of the innovation process by drawing inspiration from the structure inherent in other cognitive processes such as language (e.g., parts-of-speech, phrase composition). Drawing from language is particularly appropriate as language mediates communication in any collective pursuit of the innovation process and furthermore because a large amount of information exists in textual form. Finally, this paper finds that there is merit in approaching innovation science from its foundational elements – i.e. data, information and knowledge.

Research limitations/implications

While the purpose-context framework is broadly applicable, the methodical approach to provide structure to the front-end cognitive process is ‘one’ fruitful approach. We suspect other approaches exist.

Practical implications

The purpose-context framework is simple in its framing yet provides innovators, scholars and thought leaders, the ability to specify the problem space with greater coverage and precision. Further, in the solution-space, it provides them the ability to choose the breadth of solution scope (e.g. targeted solution addressing a single problem, targeted solution addressing a set of problems, the combination of solutions addressing a single problem and combination of solutions addressing a combination of problems). In addition, by pairing the creative front-end innovation process with machine power, this study provides a formal method to scale-up the coverage of creativity (and potentially that of solutions to those problems) and reduces the chances of missed/blind-spots in problem-specification. Finally, evaluating purpose-contexts leads to ‘capability-contexts’ – a capability-oriented viewpoint informing capability development decisions such as the focus of R&D programs and related resource allocation decisions.

Originality/value

The paper uses logic to connect multiple bodies of research with a goal to provide systematicity to problem-specification – problem-specification, which is an under-addressed part of the innovation process. The use of data to systematically explore problem-space lends it systematicity (repeatability and measurability) and is therefore, valuable to innovation science. The proof-of-concept demonstrates the conversion of concept into a method for practical application.

Details

International Journal of Innovation Science, vol. 13 no. 3
Type: Research Article
ISSN: 1757-2223

Keywords

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