Development of a structured approach for decomposition of complex systems on a functional basis

YesThe purpose of this paper is to present the System State Flow Diagram (SSFD) as a structured and coherent methodology to decompose a complex system on a solution-independent functional basis. The paper starts by reviewing common function modelling frameworks in literature and discusses practical requirements of the SSFD in the context of the current literature and current approaches in industry. The proposed methodology is illustrated through the analysis of a case study: design analysis of a generic Bread Toasting System (BTS)

Analytical target cascading framework for engine calibration optimisation

YesThis paper presents the development and implementation of an Analytical Target Cascading (ATC) Multi-disciplinary Design Optimisation (MDO) framework for the steady state engine calibration optimisation problem. The case is made that the MDO / ATC offers a convenient framework for the engine calibration optimisation problem based on steady state engine test data collected at specified engine speed / load points, which is naturally structured on 2 hierarchical levels: the “Global” level, associated with performance over a drive cycle, and “Local” level, relating to engine operation at each speed / load point. The case study of a gasoline engine equipped with variable camshaft timing (VCT) was considered to study the application of the ATC framework to a calibration optimisation problem. The paper describes the analysis and mathematical formulation of the VCT calibration optimisation as an ATC framework, and its Matlab implementation with gradient based and evolutionary optimisation algorithms. The results and performance of the ATC are discussed comparatively with the conventional two-stage approach to steady state calibration optimisation. The main conclusion from this research is that ATC offers a powerful and efficient approach for engine calibration optimisation, delivering better solutions at both “Global” and “Local” levels. Further advantages of the ATC framework is that it is flexible and scalable to the complexity of the calibration problem, and enables calibrator preference to be incorporated a priori in the optimisation problem formulation, delivering important time saving for the overall calibration development process.The research work presented in this paper was funded by UK Technology Strategy Board (TSB) through the CREO (Carbon Reduction through Engine Optimisation) project

A systems approach to the development and use of FMEA in complex automotive applications

YesThe effective deployment of FMEAs within complex automotive applications faces a number of challenges, including the complexity of the system being analysed, the need to develop a series of coherently linked FMEAs at different levels within the systems hierarchy and across intrinsically interlinked engineering disciplines, and the need for coherent linkage between critical design characteristics cascaded through the systems levels with their counterparts in manufacturing. The approach presented in this paper to address these challenges is based on a structured Failure Mode Avoidance (FMA) framework which promotes the development of FMEAs within an integrated Systems Engineering approach. The effectiveness of the framework is illustrated through a case study, centred on the development of a diesel exhaust aftertreatment system. This case study demonstrates that the structured FMA framework for function analysis supports an effective decomposition of complex interdisciplinary systems facilitating the DFMEA deployment through a series of containable, structured DFMEAs developed at successive system levels, with clear vertical integration of functional requirements and critical parameters cascade. The paper also discusses the way in which the approach supports deployment across engineering disciplines and domains, ensuring the integrity of information flow between the design and manufacturing activities

Development of an Interface Analysis Template for System Design Analysis

yesInterface definition is an essential and integral part of systems engineering. In current practice, interface requirements or control documents are generally used to define systems or subsystems interfaces. One of the challenges with the use of such documents in product development process is the diversity in their types, methodology, contents coverage, and structure across various design levels and across multidisciplinary teams, which often impedes the design process. It is important that interface information is described with appropriate detail and minimal or no ambiguity at each design level. The purpose of this paper is to present an interface analysis template (IAT) as a structured tool and coherent methodology, built upon a critical review of existing literature concepts, with the aim of using and implementing the same template for capturing interface requirements at various levels of design starting from stakeholders' level down to component level analysis. The proposed IAT is illustrated through a desktop case study of an electric pencil sharpener, and two examples of application to automotive systems

Application of the interface analysis template for delivering system requirements

yesThis paper presents a structured approach for systems requirements analysis that integrates use case modelling with a coherent flows based approach for describing interface exchanges based on the Interface Analysis Template. The approach is discussed in the context of current frameworks for requirements elicitation from the engineering design and systems engineering domains, and it is illustrated with an automotive case study. This illustrates the strength of the framework to support structured multi-domain and multi-disciplinary analysis of requirements for complex systems

Functional Modelling of Systems with Multiple Operation Modes: Case Study on an Active Spoiler System

YesThis article presents the application of the Enhanced Sequence Diagram (ESD) for the analysis of the functionality of a system with shape-changing aspects in the context of its multiple operational modes, considering an active rear spoiler as a case study. The article provides new insights on the ESD support for model-based capture and articulation of functional requirements across multiple operation modes of the same system, with appropriate detail on attributes and metrics, and the alignment of these attributes and metrics in line with the concept of time through scope lines. The article also provides a comprehensive argument and discussion, exemplified based on the case study, for the support that the ESD provides for early systems functional and architecture analysis, within the context of a broader model-based Failure Mode Analysis methodology

A Framework for Complex Product Architecture Analysis using an Integrated Approach

YesContemporary design decomposition and synthesis analytical tasks at the conceptual design stage reply on functional and structural modelling approaches. There is a wide diversity of elements used by various modelling approaches for information and representation of product architecture, which incurs difficulties for multidisciplinary engineers working across different phases of design in capturing, visualising, sharing and tracing consistent yet common knowledge and elements across the function and structure domains. This prompts for fixation of detail and common modelling knowledge across both functional and structural analytical approaches which is also critical from automatized software perspective. A limitation of existing approaches is that they tend to focus more on ‘what’ and less on ‘how’ (and vice versa). This paper proposes an integrated conceptual product architecting approach that combines and expands the functional and structural modelling approaches, enabling capturing and tracing knowledge coherently through a common binding domain. This is underpinned by the view that most interaction requirements amongst the physical components during structural modelling can be derived from functional modelling. The proposed integrated approach is underpinned by the critical analysis and synthesis of existing approaches in literature dealing with functional and structural architecture analysis, integrated within a Multiple Domain Matrix (MDM) to fuse the knowledge of both solution independent (functional) and dependent (structural) analyses. The proposed framework is illustrated with a case study of solar robot toy, followed by discussion and suggestions for future work

Performance evaluation of metamodelling methods for engineering problems: towards a practitioner guide

YesMetamodelling or surrogate modelling techniques are frequently used across the engineering disciplines in conjunction with expensive simulation models or physical experiments. With the proliferation of metamodeling techniques developed to provide enhanced performance for specific problems, and the wide availability of a diverse choice of tools in engineering software packages, the engineering task of selecting a robust metamodeling technique for practical problems is still a challenge. This research introduces a framework for describing the typology of engineering problems, in terms of dimensionality and complexity, and the modelling conditions, reflecting the noisiness of the signals and the affordability of sample sizes, and on this basis presents a systematic evaluation of the performance of frequently used metamodeling techniques. A set of metamodeling techniques, selected based on their reported use for engineering problems (i.e. Polynomial, Radial Basis Function, and Kriging), were systematically evaluated in terms of accuracy and robustness against a carefully assembled set of 18 test functions covering different types of problems, sampling conditions and noise conditions. A set of four real-world engineering case studies covering both computer simulation and physical experiments were also analysed as validation tests for the proposed guidelines. The main conclusions drawn from the study are that Kriging model with Matérn 5/2 correlation function performs consistently well across different problem types with smooth (i.e. not noisy) data, while Kriging model with Matérn 3/2 correlation function provides robust performance under noisy conditions, except for the very high noise conditions, where the Kriging model with nugget appears to provide better models. These results provide engineering practitioners with a guide for the choice of a metamodeling technique for problem types and modelling conditions represented in the study, whereas the evaluation framework and benchmarking problems set will be useful for researchers conducting similar studies

Comprehensive review of VPPs planning, operation and scheduling considering the uncertainties related to renewable energy sources

YesThe penetration of renewable energies in the energy market has increased significantly over the last two decades due to environmental concerns and clean energy requirements. The principal advantage of renewable energy resources (RESs) over non-RESs is that it has no direct carbonisation impact on the environment and that it has none of the global warming effects which are caused by carbon emissions. Furthermore, the liberalisation of the energy market has led to the realisation of the virtual power plant (VPP) concept. A VPP is a unified platform for distributed energy resources that integrates the capacities of various renewable energies together for the purpose of improving power generation and management as well as catering for the buying and selling of energy in wholesale energy markets. This review study presents a comprehensive review of existing approaches to planning, operation and scheduling of the VPP system. The methodologies that were adopted, their advantages and disadvantages are assessed in detail in order to benefit new entrants in the power system and provide them with comprehensive knowledge, techniques and understanding of the VPP concept

Synthesis of functional models from use cases using the system state flow diagram: A nested systems approach

noThe research presented in this paper addresses the challenge of developing functional models for complex systems that have multiple modes of operation or use cases. An industrial case study of an electric vehicle is used to illustrate the proposed methodology, which is based on a systematic modelling of functions through nested systems using the system state flow diagram (SSFD) method. The paper discusses the use of SSFD parameter based state definition to identify physical and logical conditions for joining function models, and the use of heuristics to construct complex function models