A Model for Quantifying System Evolvability Based on Excess and Capacity

Tackett, Morgan; Mattson, Christopher A.; Ferguson, Scott

doi:10.1115/1.4026648

Cited by 39 publications

(27 citation statements)

References 33 publications

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“…De Neufville et al (2006) advocates "design options" as a form of deliberate planning for anticipated changes, which is costed and deliberately decided upon. Looking at margins from the perspective of overdesign that exists, Tackett et al (2014) address margins in the context of shipbuilding in terms of excess, as "the quantity of surplus in a system once the necessities of the system are met" and capacity as "the ability of a system to meet future performance objectives using existing system excess". With regard to building services engineering, design margins are primarily applied to safeguard against uncertainty and risk (CIBSE, 1986), however this practise often leads to overengineered solutions.…”

Section: Design Marginsmentioning

confidence: 99%

Margins Leading to Over-Capacity

Jones¹,

Eckert²,

Gericke³

2018

Design Conference Proceedings

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This paper categorises and describes the design stages, stakeholders and decision processes of an overcapacity boiler upgrade that came about from the excessive use of design margins. Using a hospital case study, the reason behind the overcapacity and excessive margins is explored using semi-structured interviews, document analysis and process modelling. Design margins arise from a lack of systemic thinking during the design and installation phases. It is likely that margins are added as a matter of habit with no real thought to their applicability, calling into question the design process.

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Section: Design Marginsmentioning

confidence: 99%

Margins Leading to Over-Capacity

Jones¹,

Eckert²,

Gericke³

2018

Design Conference Proceedings

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“…Saleh and Hastings (2000) and Olewnik et al (2004) focus on determining when and how to embed flexibility. The authors of this paper Tackett et al 2014;Watson et al 2016) use the concept of designed-in excess to provide systems with increased flexibility. Tilstra et al have presented several papers on the value of system flexibility and associated design guidelines (Tilstra et al 2009(Tilstra et al , 2012(Tilstra et al , 2015.…”

Section: Review Of Related Workmentioning

confidence: 99%

“…(Saleh and Hastings 2000). As an illustration, consider the C-130 aircraft, which was originally designed in the early 1950s as a military cargo and troop carrier Tackett et al 2014;Bowman 1999). Since its first flight in 1954 it has undergone over 55 adaptations, including maritime patrol and rescue, electronic warning and control system, aerial refueling, and even a gun ship.…”

Section: Introductionmentioning

confidence: 99%

“…The authors of this paper have written three previous papers regarding evolvability and excess capability in complex engineered systems. Those papers address two aspects of evolvability: (i) that evolvability can be numerically evaluated by considering the usability of excess within a design Tackett et al 2014), and (ii) that excess can be optimized to increase the evolvability of a product (Watson et al 2016). While the current paper utilizes the concept that excess can be designed into a product to increase the flexibility of the design, it is unique because it presents a technique that identifies for the designer which assumptions must be refined in the context of optimizing the product for uncertain requirements.…”

Section: Introductionmentioning

confidence: 99%

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Designing in Excess Capability to Handle Uncertain Product Requirements in a Developing World Setting

Allen

Mattson

Thacker

2016

Volume 2A: 42nd Design Automation Conference

Self Cite

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Products designed for the developing world often go unused or under used by the intended individuals. Designers with experience in developed areas of the world naturally apply their values to the products they design. This results in a misjudgment of the actual requirements of individuals in developing areas. When the products do not have the ability to adapt to the actual user requirements, long-term adoption is not achieved. The ability of a product to adapt to new or changing requirements has been shown to extend the service life of large complex engineered systems (e.g., aircraft carriers, aircraft, communication systems, and space craft). These systems must remain in service for extended periods of time, even though the environments and requirements may change dramatically. The ability of these complex systems to adapt to meet these new requirements is a valuable attribute. Applying these proven techniques to products designed for the developing world can address the issue of misunderstood requirements. Adaptability is achieved, in this paper, by incorporating appropriate excess capabilities into the original design. These excess capabilities can be identified and analyzed using a numerical search methodology. This paper presents a methodology for increasing the adaptability, and therefore adoptability of products designed for the developing world by incorporating strategically determined excess capabilities.

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“…Alternatively to the collective term changeability, one can identify individual research tracks in the literature focusing on specific “ilities,” such as adaptability, flexibility, upgradeability, evolvability, and agility . An extensive contribution to flexibility in engineering design is given by de Neufville and Scholtes .…”

Section: Introductionmentioning

confidence: 99%

Quantification of changeability level for engineering systems

Rehn

Pettersen

Garcia

et al. 2018

Systems Engineering

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This paper outlines a generic method for quantifying changeability level, to support better decision making in the early stages of design of engineering systems. Changeability represents the ability of a system to change form, function, or operation, and is a collective term for characteristics such as flexibility, adaptability, and agility. Quantification of changeability level must not be confused with valuation of changeability. The level of changeability in a design is essentially under the control of the designer. Two aspects of changeability are discussed, the first being how to structure changeable design alternatives using the Design for Changeability (DFC) variable. The DFC variable represents combinations of path enablers built into a design. Path enablers are characteristics of systems enabling them to change more easily. The second aspect is to quantify the level of changeability for a given design alternative, based on change cost and time. For the latter, we propose two measures for quantification: (1) bottom-up, measuring the reduction of cost and time enabled for each relevant change, and (2) top-down, measuring the span of change opportunities at given cost and time thresholds. A case study of a ship is presented to demonstrate the proposed generic method. K E Y W O R D S changeability, flexibility, systems design, uncertainty 80

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A Model for Quantifying System Evolvability Based on Excess and Capacity

Cited by 39 publications

References 33 publications

Margins Leading to Over-Capacity

Margins Leading to Over-Capacity

Designing in Excess Capability to Handle Uncertain Product Requirements in a Developing World Setting

Quantification of changeability level for engineering systems

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