Eric Coatanéa

Study of an exergy method for environmental evaluation assessment in the early design phase using comparative LCA and exergy approach

Environmental evaluation analysis made at an early design stage is an important practical problem because existing approaches such as the LCA method require detailed information about the studied product or service. Consequently, to be efficient such a method requires a product or service located in an advanced development phase. An exergy method offers an appropriate solution for an environmental evaluation analysis at an early design stage. The theoretical model has been validated in previous journal articles. The goal of the present article is to validate the concordance of the results provided by the exergy and LCA approach, as LCA is a widely used approach even though the scientific reliability of LCA techniques has been questioned. This paper addresses the last phase of the validation of the exergy approach by comparing results of a case study analysed through both commercial LCA software and an exergy approach.

Model-based approach for change propagation analysis in requirements

The need for support related to the complexity management of systems engineering problems, specifically for requirements management and changes is especially necessary during the early stages of the systems engineering process. Indeed, these stages have a tremendous impact on the overall outcome of a project. If not anticipated at early stages, changes in requirements are leading to changes in the design and in the later implementation stages, resulting in an unexpected increase in costs (monetary, time, etc.). The framework proposed in this article for requirements change prediction consists of a three steps process. First, requirements are modeled using SysML with predefined relationships. Second, all the relationships between requirements in the SysML model are transformed into an adjacency matrix also named DSM. A higher order Dependency Structure Matrix is applied; this matrix-based methodology allows support in the prediction of which requirements will be affected after a change in a specific requirement. Third, the change propagation path is visualized. Using this framework, it is possible to predict the possible propagation of changes in requirements. In addition, it is also possible to identify the requirements that can be reused. This can help to save the time and cost for developing a new system.

A methodology supporting syntactic, lexical and semantic clarification of requirements in systems engineering

Product development is a challenging activity. The process begins with a description and representation of a design problem in form of a requirements document. It involves two phases: elicitation by description in Natural Language (NL) and clarification of the description. NL implies interpretation of terms within a context to avoid later misunderstanding. The paper proposes a methodology to elicit and refine the initial needs. The elicitation is done by finding support information from several sources such as patent databases, encyclopaedias and commercial websites. The refinement supported by a computer-based approach is done on different levels (grammar, words and context selection) to reduce the ambiguity of the requirements descriptions. The initial description is refined by an automatic questioning process. This is followed by an assisted search and selection of answers from different web-based sources. Relevant answers are selected using a similarity metric. A case study is used to demonstrate the approach.

Impact analysis of graph-based requirements models using PageRank algorithm

Managing requirements changes of complex systems and the potential impact of such changes represents a big issue for companies. Currently, commercial modelers propose tools for analyzing the direct impact of requirements changes on system design or code but the analysis of requirement change on other requirements remains seldom studied. This paper proposes an approach for the impact analysis of changes in requirements combined with a ranking of importance of requirements in graph based requirements network. Warshall algorithm is used in this paper for performing the impact analysis. Along with this approach, PageRank algorithm is used for ranking requirements according to their importance. Requirements hierarchy and their textual description of importance are considered as input for calculating their impact as well as their importance within the network of requirements. This combination of Warshall and PageRank algorithms provide significant results for helping designers in decision-making process of modifying requirements for future design versions.

Creating a Domain Ontology to Support the Numerical Models Exchange Between Suppliers and Users in a Complex System Design

Complex product development processes are evolving towards simulation driven design which leads to many heterogeneous computational models and design teams that interact with each other. However, this interaction creates a bottleneck for communication and models reuse throughout the design process because, very often, the model provider (i.e. analysts) and model users (i.e. designers) do not have the same level of understanding. In addition, the tools such as PDM (Product Data Management) or SDM (Simulation Data Management) consider the numerical models as black-box documents and they cannot access or link parameters and variables of models. The poverty of semantics in terms of simulation logics and design leads to a lack of interoperability between the contributing disciplinary simulation components, herein called numerical models. To reinforce this semantics, it is necessary to create a semantically-rich model characterization support to reduce knowledge gap between model provider and user, and to achieve a higher level of reuse. This work aims to introduce the first necessary step, herein, creation of domain ontology for formally characterizing reusable numerical model. Based on this common vocabulary, in automotive context, a Model Identity Card (MIC) is developed as an intermediate support which characterizes a model into five attributes; Physical Object, Interface, Methods, Means Usage, Validation and Verification. The MIC is illustrated with a Vehicle Thermic Comfort model example and a computer interface is developed to collect a series of representative MICs in a database.Copyright

Environmental analysis of the Product Life Cycle by using an aggregated metric based on exergy

Environmental accountancy and environmental impacts analysis are characterised by fragmented approaches encompassing a number of different perspectives and analytical techniques. Although Life Cycle Assessment (LCA) method is the most commonly used tool by which environmentally conscious design is carried out, the scientific reliability of LCA techniques has been questioned. Indeed, LCA techniques include limitations such as a lack of adequate inventory data, disparate underlying assumptions and environmental assessment made in terms that are not directly comparable. Those restrictions limit the applicability of LCA methods during early development stages. This article addresses this shortcoming by outlining previous researches in life cycle analysis and thermodynamics. It is argued herein that the early development phases require a simplified approach based on exergy. It is argued that the concept of exergy is a broad-based measure assessing the environmental impact and resource consumption of the Product Life Cycle (PLC). In addition, the article addresses a more ambitious research problem by integrating environmental impact and resource consumption into a broader design framework, described briefly in this article. The aim of the design framework presented herein is to optimise the comparison and evaluation process, which ends the early design process. This is in our viewpoint the first step of our work toward unified design theory based on topological principles.

Graph Based Representation and Analyses for Conceptual Stages

What is the fundamental similarity between investing in stock of a company, because you like the products of this company, and selecting a design concept, because you have been impressed by the esthetic quality of the presentation made by the team developing the concept?Except that both decisions are based on a surface analysis of the situations, they both reflect a fundamental human’s cognitive feature. Human brain is profoundly trying to minimize the efforts required to solve a cognitive task and is using when possible an automatic mode relying on recognition, memory, and causality. This mode is even used in some occasion without the engineer being conscious of it. Such type of tendencies are naturally pushing engineers to rush into known solutions, to avoid analyzing the context of a design problem, to avoid modelling design problems and to take decision based on isolated evidences. Those behaviors are familiar to experience teachers and engineers. This tendency is magnified by the time pressure imposed to the engineering design process. Early phases in particular have to be kept short despite the large impact of decisions taken at this stage. Few support tools are capable of supporting a deep analysis of the early design conditions and problems regarding the fuzziness and complexity of the early stage. The present article is hypothesizing that the natural ability of humans to deal with cause-effects relations push toward the massive usage of causal graphs analysis during the design process and specifically during the early phases. A global framework based on graphs is presented in this paper to efficiently support the early stages. The approach used to generate graphs, to analyze them and to support creativity based on the analysis is forming the central contribution of this paper.Copyright

A Discrete Differential Evolution Algorithm for Product Development Scheduling

The scheduling of the design activities in product development process is a crucial step in early stages in order to achieve the project in time and cost-effective manner. In complex product development process, many dependency relationships or feedback loop could exist between design activities with multiple technical domains. Sequencing the design activities is a decision making process in order to reduce these feedback loops, and therefore, reduce amount of required information flows between activities. In recent years, methods for sequencing the design activities in design process have been proposed in order to reduce lead-time development and cost. The purpose of this research work is to present a methodology for design process sequencing in product development project by using Design Structure Matrix (DSM) for visualization a complex process and Discrete Differential Evolution (DDE) for sequencing the design tasks. The tests performed in this article have shown that this approach provides very competitive results in term of the quality of obtained solutions when compared to Genetic algorithms (GA). In additional it is a simple, effective and easy to use since the amount of control parameters to set is reduced.Copyright

Product Upgradability: Towards a Medical Analogy

This paper explored the analogy between the medical area and product design. Many similarities, shared between the genetic mutation permitting human to ensure its survival and the product undergoing the introduction of new technologies to meet the market fluctuation, are found to propose this analogy. From creating genetic reference space to transplant technology into product, fundamental process of survival and evolution will be described and allows the parallel with a product, to understand how the evolution of product respond to future needs. It also ensures the durability of resources in an ecological perspective. We discuss the complexity of establishing the right diagnosis for directing the design to choose the right technology and to enable its future integration into a living product. This uncertainty in the technological maturity but also the integrability of this technology in the current product at first, then in the future will allow its product development. Conclusions for the use of this analogy and the justification to describe “living product“ will be drawn.

Organizing the Product Development Processes: Four Perspectives

As stated by Zeng (Zeng, 2011), design comes from an environment, serves the environment, and changes the environment. Understanding the environment of a product is recognized by the research community to have a crucial impact on quality and success of products, services and complex systems. In this context, the aim of the Journal of Integrated Design and Process Science (JIDPS) is to publish research findings covering transdisciplinary notions of design and process. The focus of the journal is aligned with three fundamental objectives which are; a) the understanding of design and process crossing boundaries of natural, human, and built environments, b) the principles, methods, and tools, and c) the applications of design and process science to engineering and social problems. The present transaction is covering well those three lines of research by providing researches associated with: 1The optimization of the scheduling and organization of the system development process, 2The integration of product service system tools into the product development process, 3The analysis of the consistency in the architecture of large scale systems, 4The risk management in new product and service process, The present issue is trying to understand and act on the environment in large of systems or services by understanding the processes associated with the design of those systems and services. The issue is also including research work about the principles, the methods and the tools. The first paper, titled “A Combined Design Structure Matrix (DSM) and Discrete Differential Evolution (DDE) Approach for Scheduling and Organizing System Development Tasks Modelled using SysML” by Nonsiri et al, aims to develop a method supported by Artificial Intelligence approaches for automatically optimizing scheduling and organization of system development tasks. The purpose of this work is to support the scheduling and organization of tasks that can become very complex in system engineering process. Significant savings in term of development time can be made by providing a method that is optimizing the amount of feedbacks and iterations to the minimal level simply required for the successful development of the system. In this article, the authors are proposing to combine a computational approach (Discrete Differential Evolution) with Model Based Systems Engineering (MBSE) for minimizing iterations and reducing lead-time development. The present article is contributing to recent research works using Design Structure Matrixes (DSM) and computational methods for visualizing and analysing systems engineering processes. The practical use of the proposed framework is demonstrated on the case study of a mobile robot developed for the Eurobot competition. The article also