Lalit Patil

Ontology-based exchange of product data semantics

An increasing trend toward product development in a collaborative environment has resulted in the use of various software tools to enhance the product design. This requires a meaningful representation and exchange of product data semantics across different application domains. This paper proposes an ontology-based framework to enable such semantic interoperability. A standards-based approach is used to develop a Product Semantic Representation Language (PSRL). Formal description logic (DAML+OIL) is used to encode the PSRL. Mathematical logic and corresponding reasoning is used to determine semantic equivalences between an application ontology and the PSRL. The semantic equivalence matrix enables resolution of ambiguities created due to differences in syntaxes and meanings associated with terminologies in different application domains. Successful semantic interoperability will form the basis of seamless communication and thereby enable better integration of product development systems. Note to Practitioners-Semantic interoperability of product information refers to automating the exchange of meaning associated with the data, among information resources throughout the product development. This research is motivated by the problems in enabling such semantic interoperability. First, product information is formalized into an explicit, extensible, and comprehensive product semantics representation language (PSRL). The PSRL is open and based on standard W3C constructs. Next, in order to enable semantic translation, the paper describes a procedure to semi-automatically determine mappings between exactly equivalent concepts across representations of the interacting applications. The paper demonstrates that this approach to translation is feasible, but it has not yet been implemented commercially. Current limitations and the directions for further research are discussed. Future research addresses the determination of semantic similarities (not exact equivalences) between the interacting information resources.

Progress Towards an International Standard for Data Transfer in Rapid Prototyping and Layered Manufacturing

Abstract This paper discusses the informational requirements of rapid prototyping and layered manufacturing (RPLM). The study is motivated by the recent decision to embark on the development of a new Application Protocol for the international standard ISO 10303, specifically to handle layered manufacturing information. The most common industrial use of RPLM today is for rapid prototyping, but a wider view of it as a flexible fabrication technology is taken here, to allow for future developments. Its use in building functional metallic parts under computer control has already been demonstrated, and commercial RPLM machines for building production parts are already being marketed. The paper includes a survey of current and proposed data formats for communication between the various stages of the RPLM process. In comparing them, particular attention is given to the issue of extensibility to meet future needs. In this last respect, special emphasis is given to materials-related and other non-geometric information needed for fabricating multi-material objects and objects with graded material properties.

A proposed standards‐based approach for representing heterogeneous objects for layered manufacturing

Information models for the representation of product data are being developed as an international standard. However, the current application protocols focus on the representation of homogeneous objects only. This paper suggests an information model to represent heterogeneous objects using the information modeling methodology developed for ISO 10303. The data planning model is then extended to represent the two‐dimensional (2D) slice information using concepts from ISO 10303. The proposed formats are validated by physical realization of objects on two LM machines. This information model will help in providing a uniform base in the development of heterogeneous solid modeling systems. It will also equip the solid modeler with the ability to integrate with other applications and process planning in the domain of layered manufacturing.

Multi-Objective Optimization of Product Configuration

In the context of globalization and mass customization, selecting the appropriate product configuration requires a simultaneous consideration of multiple criteria or objectives, which are in conflict with each other. The large solution space implies that analyzing each feasible solution is a combinatorial problem. Furthermore, no single optimal solution exists; on the contrary, there is a set of valid optimal solutions, i.e., the solution set is Pareto-optimal. We present the configuration problem from the perspective of using two types of attributes: static, i.e., the attributes that have pre-defined and constant values throughout the configuration process, and dynamic, i.e., attributes whose values vary according to decisions that are being made during the configuration process. We pose the product configuration as a multiobjective optimization problem requiring that multiple objective functions cannot be combined into a single objective function. We demonstrate the applicability of using Multi-Objective Genetic Algorithms (MOGA) to solve the problem and converge to a Pareto-optimal solution set from the large number of feasible solutions.Copyright

An Approach to Determine Important Attributes for Engineering Change Evaluation

Enterprises plan detailed evaluation of only those engineering change (EC) effects that might have a significant impact. Using past EC knowledge can prove effective in determining whether a proposed EC effect has significant impact. In order to utilize past EC knowledge, it is essential to identify important attributes that should be compared to compute similarity between ECs. This paper presents a knowledge-based approach for determining important EC attributes that should be compared to retrieve similar past ECs so that the impact of proposed EC effect can be evaluated. The problem of determining important EC attributes is formulated as the multi-objective optimization problem. Measures are defined to quantify importance of an attribute set. The knowledge in change database and the domain rules among attribute values are combined for computing the measures. An ant colony optimization (ACO)-based search approach is used for efficiently locating the set of important attributes. An example EC knowledge-base is created and used for evaluating the measures and the overall approach. The evaluation results show that our measures perform better than state-of-the-art evaluation criteria. Our overall approach is evaluated based on manual observations. The results show that our approach correctly evaluates the value of proposed change impact with a success rate of 83.33%.

Ontology Formalization of Product Semantics for Product Lifecycle Management

Product Lifecycle Management (PLM) is a concept that takes into account that the development of a product is influenced by knowledge from various stakeholders throughout its lifecycle. Computing environments in the PLM framework are expected to have several independent information resources. This requires a meaningful formal representation of product data semantics throughout the product’s lifecycle. This paper presents an ontological approach to formalize product semantics into a Product Semantic Representation Language (PSRL). Building blocks to develop the explicit, extensible and comprehensive PSRL are described. The PSRL is open and based on standard W3L OWL constructs. The extensibility is demonstrated by considering an example product. The representation and the method of its development is expected to support several applications in the context of PLM. The use of OWL will enable the provision of the application software and information resources as Web services in the context of the Semantic Web.Copyright

Function Semantic Representation (FSR): A Rule-Based Ontology for Product Functions

Defining or understanding a product in terms of its functions facilitates a wide variety of tasks such as design synthesis, modeling, and analysis. However, the lack of a semantically correct formal representation of product functions creates a barrier to their effective capture, exchange, and reuse. This paper presents Function Semantics Representation, a rule-based ontological formalism that is consistent with the Semantic Web standards to capture different components of a product function. In particular, the Semantic Web Rule Language is used to overcome limitations in using the basic Web Ontology Language ontology to explicitly capture advanced semantics essential to completely represent product functions. This enables support for an effective reasoning mechanism to develop and validate the product function (or functional model). We present examples that demonstrate consistency checking and the ability to retrieve functionally similar products from a repository.

An approach to compute similarity between engineering changes

Detailed evaluation of a proposed Engineering Change (EC) or its effects is a time-consuming process requiring considerable user expertise. Therefore, enterprises plan detailed evaluation of only those EC effects that might have a significant impact. Since similar ECs are likely to have similar effects and impacts, past EC knowledge can be utilized for determining whether the proposed EC effect has significant impact. Utilizing past ECs to predict the impact of proposed EC effect requires an approach for computing similarity between ECs. This paper presents an approach to compute similarity between ECs that are defined by a set of disparate attributes. Since the available information is probabilistic, the fundamental measures of information are utilized for defining measures to compute similarity between two attribute values or ECs. The semantics associated with attribute values are identified and utilized to compute similarity between attribute values. The similarities between attribute values are aggregated to compute the similarity between ECs in the context of overall goal. A case-study is presented to demonstrate the applicability of the proposed approach.

Similarity Computation for Knowledge-Based Sustainability Evaluation of Engineering Changes

Systematic sustainability assessment of a proposed Engineering Change (EC) is, typically, a time-consuming process due to the complexity of typical products and the lifecycle-wide impact of a change. One approach to enable faster evaluation is the use of the knowledge from similar past ECs. In this paper, we present an approach based on research in psychology to calculate the similarity of Engineering Changes such that the retrieved ECs can be used to predict only the carbon footprint of the proposed EC. Product knowledge is structured, and there is no acceptable standard for representation. Therefore, we propose a measure that focuses on identifying and aligning corresponding components of the query and target representations. We apply the measure to a case of 14 Engineering Changes (91 matching problems) and compare the matches for relevance to evaluation of carbon footprint. The precision and recall are evaluated by comparing against carbon footprints obtained using commercial LCA tool.Copyright

An Information-Theoretic Approach to Determine Important Attributes for Engineering Change Evaluation

A proposed Engineering Change (EC) can affect several lifecycle-wide components. Enterprises plan detailed evaluation of only those changes or effects that may have a significant impact. Using past knowledge of engineering changes can prove effective in determining whether an effect is significant. However, comparing ECs for every single attribute is a combinatorial problem, because an EC is composed of a large number of disparate and interdependent attributes. In this paper, we propose an information-theoretic approach to determine important attributes that should be compared to retrieve past ECs similar to the proposed change. Our approach accounts for unknown interdependencies between attributes of disparate datatypes. We believe that the method discussed in this paper will improve overall efficacy of the Engineering Change Management (ECM) process by facilitating fast and reliable evaluation of a proposed EC.Copyright