Application of entity-based approach for unified representation of design alternatives for structural design

To support the design process fully from preliminary to detailed design stages in a natural way, a computer-integrated design system is needed. In early design stages more than one design alternatives are considered as possible solutions. The representation of design alternatives must be uniform and unbiased to be equally treated. In this study, an entity-based approach has been adopted to develop product and process models for representing design alternatives, which is more desirable for top–down design process because it allows high-level abstraction in representing design information and design activities. The entity-based approach has several benefits: (1) a unified representation of design alternatives; (2) a consistent development of product and process models based on the entity-based concepts; and (3) an easy integration of the product and process models. The work toward product and process models for structural design presented in this paper is a useful step toward integrated computer-aided design systems.     

Extended liaison as an interface between product and process model in assembly

This paper describes the use of liaison to better integrate product model and assembly process model so as to enable sharing of design and assembly process information in a common integrated form and reason about them. Liaison can be viewed as a set, usually a pair, of features in proximity with which process information can be associated. A liaison is defined as a set of geometric entities on the parts being assembled and relations between these geometric entities. Liaisons have been defined for riveting, welding, bolt fastening, screw fastening, adhesive bonding (gluing) and blind fastening processes. The liaison captures process specific information through attributes associated with it. The attributes are associated with process details at varying levels of abstraction. A data structure for liaison has been developed to cluster the attributes of the liaison based on the level of abstraction. As information about the liaisons is not explicitly available in either the part model or the assembly model, algorithms have been developed for extracting liaisons from the assembly model. The use of liaison is proposed to enable both the construction of process model as the product model is fleshed out, as well as maintaining integrity of both product and process models as the inevitable changes happen to both design and the manufacturing environment during the product lifecycle. Results from aerospace and automotive domains have been provided to illustrate and validate the use of liaisons.     

An approach to identify design and manufacturing features from a data exchanged part model

Due to the large variety of CAD systems in the market, data exchange between different CAD systems is indispensable. Currently, data exchange standards such as STEP and IGES, etc. provide a unique approach for interfacing among different CAD platforms. Once the feature-based CAD model created in one CAD system is input into another via data exchange standards, many of the original features and the feature-related information may not exist any longer. The identification of the design features and their further decomposition into machining features for the downstream activities from a data exchanged part model is a bottleneck in integrated product and process design and development. In this paper, the feature panorama is succinctly articulated from the viewpoint of product design and manufacturing. To facilitate feature identification and extraction, a multiple-level feature taxonomy and hierarchy is proposed based on the characteristics of part geometry and topology entities. The relationships between the features and their geometric entities are established. A litany of algorithms for the identification of design and machining features are proposed. Besides, how to recognize the intersecting features or compound features based on the featureless chunks of geometry entities is critical and the issue is addressed in the paper. A multi-level compound feature representation and recognition approach are presented. Finally, case studies are used to illustrate the validity of the approach and algorithms proposed for the identification of the features from CAD part models in neutral format.     

From Contracts to E-Contracts: Modeling and Enactment

Contracts are complex to understand, represent and process electronically. Usually, contracts involve various entities such as parties, activities and clauses. An e-contract is a contract modeled, specified, executed and enacted (controlled and monitored) by a software system (such as a workflow system). Workflows are used to automate business processes that govern adherence to the e-contracts. E-contracts can be mapped to inter-related workflows, which have to be specified carefully to satisfy the contract requirements. Most workflow models do not have the capabilities to handle complex inter/intra relationships among entities in e-contracts. An e-contract does not adhere to activity/task oriented workflow processes, thus generating a gap between a conceptual model of e-contract and workflow. In this paper, we describe conceptual modeling of e-contracts and present a business process model for e-contract enactment. The enactment of e-contracts necessitates dynamic generation and initiation of workflows during the e-contract execution, besides the static workflows. ER^EC business process model facilitates an integrated approach to e-contracts enactment. Our methodology is illustrated by means of a case study conducted using Financial Messaging Solution contract for banking transactions.     

家谱文本中实体关系提取方法研究

实现家谱资源的高效的组织和利用,需要从非结构化的家谱文本中提取实体及关系,进行结构化的表示。实体和关系的提取通常被作为序列标注任务来解决,输入的句子被映射到标签序列。针对家谱文本中实体和关系高度密集、关系重叠很常见的特点,该文构建了相应的概念模型来指导整个提取过程。在序列标注部分,该文在真实数据上检验了常用的深度学习模型的表现。实验结果显示,BERT-BiLSTM-CRF模型的精确率、召回率和F₁值均优于所对比的其他模型,该文所提出的方法能够有效地解决家谱文本中的实体关系提取问题。     

Knowledge graph construction for product designs from large CAD model repositories

Product Design based Knowledge graphs (KG) aid the representation of product assemblies through heterogeneous relationships that link entities obtained from multiple structured and unstructured sources. This study describes an approach to constructing a multi-relational and multi-hierarchical knowledge graph that extracts information contained within the 3D product model data to construct Assembly-Subassembly-Part and Shape Similarity relationships. This approach builds on a combination of utilizing 3D model meta-data and structuring the graph using the Assembly-Part hierarchy alongside 3D Shape-based Clustering. To demonstrate our approach, from a dataset consisting of 110,770 CAD models, 92,715 models were organized into 7,651 groups of varying sizes containing highly similar shapes, demonstrating the varied nature of design repositories, but inevitably also containing a significant number of repetitive and unique designs. Using the Product Design Knowledge Graph, we demonstrate the effectiveness of 3D shape retrieval using Approximate Nearest Neighbor search. Finally, we illustrate the use of the KG for Design Reuse of co-occurring components, Rule-Based Inference for Assembly Similarity and Collaborative Filtering for Multi-Modal Search of manufacturing process conditions. Future work aims to expand the KG to include downstream data within product manufacturing and towards improved reasoning methods to provide actionable suggestions for design bot assistants and manufacturing automation.     

A neutral object data model for integrated building design and construction environment

Construction and civil engineering projects include large numbers of design elements, materials, activities, in addition to a diversity of data types and complex relationships. The need to adopt appropriate representational schemes and database technologies that can handle complex data types and relationships continue to hinder the search for solutions to an integrated design-construction environment. This paper describes a scheme that classifies and codes design information to support an integrated building design data model. The model is conceptual and based on the object-oriented paradigm. It uses concepts such as objects, attributes and different relations between objects. The main feature of the model is a set of hierarchies of design objects which have classes for describing the various aspects of design elements of a building. These classes represent elements, materials, geometry and construction activities represented by work sections. The model provides classes of data items from which the designer can select to model the various pieces of design elements and their associated work sections. Attributes provide information included in design and construction documents like drawings, specifications and bills of quantities. The model deals with a diversity of data abstracts including multimedia features like sound and video that can be stored in different design documents.     

B-hist: Entity-centric search over personal web browsing history

Web Search is increasingly entity centric; as a large fraction of common queries target specific entities, search results get progressively augmented with semi-structured and multimedia information about those entities. However, search over personal web browsing history still revolves around keyword-search mostly. In this paper, we present a novel approach to answer queries over web browsing logs that takes into account entities appearing in the web pages, user activities, as well as temporal information. Our system, B-hist, aims at providing web users with an effective tool for searching and accessing information they previously looked up on the web by supporting multiple ways of filtering results using clustering and entity-centric search. In the following, we present our system and motivate our User Interface (UI) design choices by detailing the results of a survey on web browsing and history search. In addition, we present an empirical evaluation of our entity-based approach used to cluster web pages.     

A knowledge sorting process for a product design expert system

Knowledge sorting is one way to organize the knowledge acquired from the domain expert(s) and various sources. Well-organized knowledge representation will make rule extraction much easier. This paper describes a knowledge sorting process that was developed to facilitate the rule extraction for a product design expert system. The process capitalizes on the relationships between design attributes and factors, dependent and independent variables, and consists of three stages: identification of knowledge sources, generation of taxonomic trees, and organization of acquired knowledge. An example applies the sorting process to the development of an expert system for the design of wood head golf clubs.     

联合作战模拟系统中军事模型体系结构

进行联合作战模拟系统体系结构设计时,面临的主要问题之一是设计在结构水平上与被仿真对象(联合作战)基本相似的模型体系(模型结构和模型数据),即它必须包含映射“联合作战”中实体及实体活动的各种军事模型和映射实体间各种关系的军事模型间关系。针对此问题,该文以联合作战模拟为应用背景,设计了联合作战模拟系统中军事模型的体系结构,说明了它的相关概念;阐述了军事模型的开发过程,并确定了联合作战模拟系统中军事模型间信息控制关系。     

Web classification of conceptual entities using co-training

Social networking websites, which profile objects with predefined attributes and their relationships, often rely heavily on their users to contribute the required information. We, however, have observed that many web pages are actually created collectively according to the composition of some physical or abstract entity, e.g., company, people, and event. Furthermore, users often like to organize pages into conceptual categories for better search and retrieval, making it feasible to extract relevant attributes and relationships from the web. Given a set of entities each consisting of a set of web pages, we name the task of assigning pages to the corresponding conceptual categories conceptual web classification. To address this, we propose an entity-based co-training (EcT) algorithm which learns from the unlabeled examples to boost its performance. Different from existing co-training algorithms, EcT has taken into account the entity semantics hidden in web pages and requires no prior knowledge about the underlying class distribution which is crucial in standard co-training algorithms used in web classification. In our experiments, we evaluated EcT, standard co-training, and other three non co-training learning methods on Conf-425 dataset. Both EcT and co-training performed well when compared to the baseline methods that required large amount of training examples.     

Managing the exchange of engineering product data to support through life ship design

An approach for managing the exchange of engineering product data between geographically distributed designers and analysts using a heterogeneous tool set for the through-life design of a ship is described. The approach was developed within a pan-European maritime project called VRShips-ROPAX 2000 that demonstrated how information technology could be integrated into the design process. This paper describes the development of a common model containing neutral ship product data through a bottom-up consideration of the requirements of the tools to be integrated, as well as a top-down consideration of the data requirements for through life design. This common model was supported within an Integrated Design Environment (IDE) that co-ordinated design activity distributed across Europe. The IDE ensured that the users were provided with the right data in the right form at the right time to do the right task, i.e., that the design activity was timely and appropriate. The strengths and weaknesses of the approach are highlighted.     

A PDES/STEP-based model and system for concurrent integrated design and assembly planning

Product data exchange and interfacing between different CAD/CAM systems are of great importance to the development of concurrent integrated design environments and computer integrated manufacturing systems. This paper presents a STEP-based method and system for concurrent integrated design and assembly planning. An integrated object model for mechanical systems and assemblies is first defined by a hierarchy of structure, geometry and feature. The structure is represented as a component-connector or joint multi-level graph with both hierarchical functional and assembly relations. These hierarchical relation models are then used for uniformly describing their causal relations both for assembly level and feature based single part level. The generic product assembly model is organized according to STEP, using mostly the entities of integrated resources and partly self-defined entities, which are necessary for design and assembly planning. Based on the generic product assembly model, STEP-based strategies and agent concepts are used for agent-based concurrent integration of design and assembly planning. A prototype system, consisting of a CAD system, a product modeling system, an assembly planning system, and an assembly evaluation system is developed, in which product data can be exchanged between these subsystems. Details about the implementation of the system are addressed. The integrated design and assembly planning system can support the introduction of a new product. The results of assembly planning are feedback to the stage of assembly design to improve on the design. A case study is carried out for assembly-oriented design of a gearbox, to illustrate the proposed approach and to validate the developed system.     

Re-engineering of the design process for concurrent engineering

According to the requirements of concurrent engineering, three interdependency relationships (uncoupled relationship, coupled relationship and decoupled relationship) between design activities are presented in this paper. And the coupled relationship plays an important role in concurrent product design process. To represent the precedence relationships among design activities, a directed graph is used to describe the design process. And the interdependency relationship between activities is illustrated by a Design Structure Matrix which is the transpose of the accessibility matrix of the corresponding graph. Using the DSM, an algorithm of recognizing the coupled activities during the design process is presented. Moreover, an algorithm to figure out the order levels of activities during the design process is proposed. And both algorithms are illustrated with a die design example.     

Integration of product design,process planning,scheduling, and FMS control using XML data representation

An efficient model for communications between CAD, CAPP, and CAM applications in distributed manufacturing planning environment has been seen as key ingredient for CIM. Integration of design model with process and scheduling information in real-time is necessary in order to increase product quality, reduce the cost, and shorten the product manufacturing cycle. This paper describes an approach to integrate key product realization activities using neutral data representation. The representation is based on established standards for product data exchange and serves as a prototype implementation of these standards. The product and process models are based on object-oriented representation of geometry, features, and resulting manufacturing processes. Relationships between objects are explicitly represented in the model (for example, feature precedence relations, process sequences, etc.). The product model is developed using XML-based representation for product data required for process planning and the process model also uses XML representation of data required for scheduling and FMS control. The procedures for writing and parsing XML representations have been developed in object-oriented approach, in such a way that each object from object-oriented model is responsible for storing its own data into XML format. Similar approach is adopted for reading and parsing of the XML model. Parsing is performed by a stack of XML handlers, each corresponding to a particular object in XML hierarchical model. This approach allows for very flexible representation, in such a way that only a portion of the model (for example, only feature data, or only the part of process plan for a single machine) may be stored and successfully parsed into another application. This is very useful approach for direct distributed applications, in which data are passed in the form of XML streams to allow real-time on-line communication. The feasibility of the proposed model is verified in a couple of scenarios for distributed manufacturing planning that involves feature mapping from CAD file, process selection for several part designs integrated with scheduling and simulation of the FMS model using alternative routings.     

A scenario for the development and implementation of a building product model standard

Product models offer a promising method for structuring data describing a building in the databases which will be used in the computer integrated construction process of the next century.In order to define product model standards which completely describe modern buildings, many years of theoretical and experimental work are needed. In order to ensure industrial backing for the work needed to develop full standards, it seems prudent to organize such work on a step by step basis where partial standards can be agreed on and implemented rather quickly.In addition to the international work being carried out within the ISO/STEP working group, it is possible to obtain results on a national basis, provided there is a large enough consensus within the construction industry on what ought to be done.In Finland the basic principles of a building product model, the RATAS-model, have been defined. The model uses a data model consisting of such concepts as objects, attributes, relationships and it describes the building with a five-level abstraction hierarchy starting with the building object. At present a number of prototypes are being developed based on the RATAS-model. These prototypes are developed using different types of application software: relational databases, hypermedia, drafting systems etc., but they all utilize the same conceptual information structure.     

Simulation based Scheduling of multiple change propagations in multistage product development processes

Multiple engineering changes can simultaneously occur in different product development domains or stages, which can cause product delivery delays or development failure. To carefully manage multiple change propagations in multistage product development processes, a digraph-based model, combined with input and output logics, is adopted to represent entities obtained in different product development stages. Dependencies and mapping relationships are used to model inter- and intra- domain entity connections, along which engineering changes can propagate. Mathematical models are developed to compute change impacts and required efforts for resolving changes. Simulation algorithms are present to explore possible change evolution paths across different stages. Genetic algorithm (GA) is employed to find the optimal change propagation paths. A multistage development model representing functional design, structural design and manufacturing process of an air-conditioner is used to test the change scheduling method. Change durations and propagation traces for one, two and three emergent changes are compared to find the best strategy for coping with multiple change requests in multistage product development processes.     

Development of control mechanisms to support coherency of product model during cooperative design process

Product development became an increasingly collaborative and distributed activity. Collaborative design process gathers experts from different backgrounds and areas for a common objective about product development. An effective exchange support is expected to share and integrate design knowledge avoiding conflicts between designers. The management of heterogeneous product representation is a major step to integrate expert activities. To successfully manage this process, this paper proposes: (1) A research experimental platform for cooperative design in product development processes. (2) A new constraint based model to maintain complex relationships in multi-disciplinary cooperative design. (3) A model differentiation technique, which identifies differences and conflicts between models. (4) A Meta-rule concept, which controls the constraint network in design process, leading to a new notification mechanism to present conflict to all corresponding actors.