A feature-based approach to injection mould cooling system design

Most existing work on the design of cooling systems of plastic injection moulds has been focused on the detailed analysis or the optimization of the cooling system. However, before a cooling system can be analysed or optimized, an initial design has to be developed. We explore a new design synthesis approach to solve this initial design problem. A plastic part with a complex shape is decomposed into simpler shape features. The cooling systems of the individual features are first obtained, they are then combined to form the cooling system of the entire part. Decomposing a complex shape into shape features is a feature recognition problem. A new algorithm for the recognition of features specific to cooling system design is developed. Design examples generated by the design synthesis process are analysed by C-Mold to verify the feasibility of the approach.     

A feature-based database evolution approach in the design process

Design data are assigned in geometric and non-geometric form in order to meet design requirements. These data and information must be encapsulated in a data structure that has significance for design applications in each design process phase. The main goal of this research is to find design data groups that represent each mechanical design phase, which will be called phase's design signature. In addition, current data should be an evolution of the geometric and non-geometric information of the previous design phase. In this paper, the purpose is to identify and model a set of design features that encapsulate the design data and their transformations which occurred during the mechanical design phases. This database must capture the designer's intents that can be modeled and implemented using feature-based model in the conventional CAD systems, object-oriented modeling, and Java classes.     

A feature-based fixture design methodology for the manufacturing of aircraft structural parts

In fixture design for the manufacturing of aircraft structural parts, there are various challenges and serious problems in industry, such as difficulty in design knowledge capture and reuse, and the arbitrary or non-standard nature of design, which influence the efficiency and quality of fixture design. This paper proposes a feature-based fixture design methodology in which previous fixture design cases and design rules are described in association with features and thus the design knowledge is integrated with geometric information of aircraft structural parts, which are the main concern of this project. In this methodology, machining features of the structural parts and their associated attributes are identified by feature recognition technique from the 3 dimensional (3D) part models defined based on model-based definition (MBD) technique. The feature-based part information models are then established and are used to retrieve previous fixture design cases and design rules stored in the knowledge base. Fixture designers will choose the appropriate retrieved design cases as the starting point for new fixture design or use previous designs to assess his/her current design. In this way the process of new fixture design can be improved. In the current stage of the research, a prototype feature-based fixture design system based on CATIA for the manufacturing of aircraft structural parts has been developed and used by a large airplane manufacturer.     

A hyper-heuristic approach to aircraft structural design optimization

The conceptual design of an aircraft is a challenging problem in which optimization can be of great importance to the quality of design generated. Mass optimization of the structural design of an aircraft aims to produce an airframe of minimal mass whilst maintaining satisfactory strength under various loading conditions due to flight and ground manoeuvres. Hyper-heuristic optimization is an evolving field of research wherein the optimization process is continuously adapted in order to provide greater improvements in the quality of the solution generated. The relative infancy of hyper-heuristic optimization has resulted in limited application within the field of aerospace design. This paper describes a framework for the mass optimization of the structural layout of an aircraft at the conceptual level of design employing a novel hyper-heuristic approach. This hyper-heuristic approach encourages solution space exploration, thus reducing the likelihood of premature convergence, and improves the feasibility of and convergence upon the best solution found. A case study is presented to illustrate the effects of hyper-heuristics on the problem for a large commercial aircraft. Resulting solutions were generated of considerably lighter mass than the baseline aircraft. A further improvement in solution quality was found with the use of the hyper-heuristics compared to that obtained without, albeit with a penalty on computation time.     

A feature-based approach to better automatic treebank conversion

In the field of constituency parsing, there exist multiple human-labeled treebanks which are built on non-overlapping text samples and follow different annotation standards. Due to the extreme cost of annotating parse trees by human, it is desirable to automatically convert one treebank (called source treebank) to the standard of another treebank (called target treebank) which we are interested in. Conversion results can be manually corrected to obtain higher-quality annotations or can be directly used as additional training data for building syntactic parsers. To perform automatic treebank conversion, we divide constituency parses into two separate levels: the part-of-speech (POS) and syntactic structure (bracketing structures and constituent labels), and conduct conversion on these two levels respectively with a feature-based approach. The basic idea of the approach is to encode original annotations in a source treebank as guide features during the conversion process. Experiments on two Chinese treebanks show that our approach can convert POS tags and syntactic structures with the accuracy of 96.6 and 84.8 %, respectively, which are the best reported results on this task.     

A feature-based approach towards an integrated product model including conceptual design information

Due to the highly complex and informal data that has to be managed in the conceptual design this early design phase still lacks of suitable computer support. Furthermore, existing approaches towards a computer aided conceptual design are insufficiently integrated with the downstream applications of the product development process. The paper therefore introduces an approach towards a feature-based integrated product model that incorporates a feature-based representation scheme for capturing product semantics handled in the conceptual design phase and links early design with part and assembly modelling.     

A parametric feature-based approach to reconstructing traditional filigree jewelry

This paper presents a novel approach to reconstructing traditional filigree jewelry. Our method aims at producing an editable CAD representation that can accurately capture the original design and be capable of re-parameterization and modification prior to manufacturing (for example to insert custom designs and abide to free-form artistic alterations). To achieve this, we have developed robust and accurate representations of patterns, used in the design of such jewelry, based on spirals, circular and elliptic arcs, curve segments and braids of various types; all optimized by fairness criteria for aesthetic purposes. We have also built a library of parametric, constraint-based, manufacturable solid patterns that occur frequently in filigree jewelry. For the purposes of this work, a suite of software tools called ReJCAD has been developed, that is able to process a highly accurate point cloud of jewelry pieces and to detect features which are fitted by the primitives of the pattern library through user interaction. The point cloud, in the current framework, guides the assembling of all patterns into one robust manufacturable solid piece. We demonstrate the unique capabilities of ReJCAD by reconstructing a filigree brooch part commonly used in late 19th century in northwestern Greece.     

A feature-based approach for individualized human head modeling

Published online: 18 September 2001     

A mixed design approach for probabilistic structural durability

In this paper, a mixed approach for probabilistic structural durability design of mechanical systems is proposed. In this approach, a deterministic design optimization that considers structural crack initiation and crack propagation lives at critical points of the structural component as design constraints is performed first. After an optimal design is obtained, a reliability analysis is performed to ascertain if the deterministic optimal design is reliable. If the probability of the failure of the deterministic optimal design is found to be acceptable, a reliability-based design approach that employs a set of interactive design steps, such as trade-off analysis and what-if study, is used to obtain a near-optimal design that is reliable with an affordable computational cost. A 3-D tracked vehicle roadarm is employed to demonstrate the feasibility of the proposed approach.     

On a game approach to optimal structural design

A game problem of structural design is formulated as a problem of playing against external circumstances. The compliance plays the role of the pay-off function. Two players — the designer and nature — try to respectively minimize or maximize it, possessing limited resources. Discrete and continual optimization problems are considered.It is proved that the essential game characteristic, the upper game value, is expressed in terms of the minimal eigenvalue of the inverse operator of the system (continual case), or the response matrix (discrete case). For a special case of convex game, this eigenvalue is equal to the value of the game, and the optimal strategies of the designer and nature are uniquely determined.     

Ontology-based semantic similarity: A new feature-based approach

Estimation of the semantic likeness between words is of great importance in many applications dealing with textual data such as natural language processing, knowledge acquisition and information retrieval. Semantic similarity measures exploit knowledge sources as the base to perform the estimations. In recent years, ontologies have grown in interest thanks to global initiatives such as the Semantic Web, offering an structured knowledge representation. Thanks to the possibilities that ontologies enable regarding semantic interpretation of terms many ontology-based similarity measures have been developed. According to the principle in which those measures base the similarity assessment and the way in which ontologies are exploited or complemented with other sources several families of measures can be identified. In this paper, we survey and classify most of the ontology-based approaches developed in order to evaluate their advantages and limitations and compare their expected performance both from theoretical and practical points of view. We also present a new ontology-based measure relying on the exploitation of taxonomical features. The evaluation and comparison of our approach’s results against those reported by related works under a common framework suggest that our measure provides a high accuracy without some of the limitations observed in other works.     

On editability of feature-based design

Techniques needed for editing generative designs are presented. When a feature is edited, all features attached later must be re-evaluated to satisfy the required constraints and shape references in the initial design. We describe name matching techniques that support the design reevaluation procedure. The algorithms account for failed or multiple matches. The matching uses a naming schema based on historical, topological, and geometric design information that has been described in a companion paper.     

A framework for feature-based representation of the design process

The design process is very complicated and differs with each engineer. The development of computer-based aids for design must take this into consideration and allow for the nuances of the individual. A generic representation of the information used in design is required for the development of any data base that supports the design aid. A properly designed data base or set of data bases can help aid. A properly designed data base or set of data bases can help integrate CAD, expert system, and ancillary programs, thereby forming an intelligent design system. A model has been developed that allows the information requirements of the design process to be analyzed. A data base for an intelligent design system can be developed based on these results.     

A formal approach to automating conceptual structural design,Part I: Methology

In the conceptual phase of structural design a designer develops and investigates many potential alternatives for safe and economic transfer of loads that are to be carried by the structure. A methodology for automating conceptual structural design is presented in this paper. Some of the salient aspects of the methodology are: (1) an explicit representation of the structural form, function, and behavior; (2) modeling the structural engineering domain as well as the strategy employed by expert designers; (3) usingcost/value ratio as an intrinsic measure of the merit of a design alternative; and (4) reduced reliance on heuristics with more emphasis on first principles and fundamental knowledge. The categories of knowledge that need to be represented in a computer system to support the reasoning for conceptual structural design are identified. The use of such knowledge is illustrated through examples based on several different types of structures. A constraint classification system (to organize the constraints that arise from structural and exogenous considerations) is also proposed.     

A novel feature-based approach to characterize algorithm performance for the traveling salesperson problem

Meta-heuristics are frequently used to tackle NP-hard combinatorial optimization problems. With this paper we contribute to the understanding of the success of 2-opt based local search algorithms for solving the traveling salesperson problem (TSP). Although 2-opt is widely used in practice, it is hard to understand its success from a theoretical perspective. We take a statistical approach and examine the features of TSP instances that make the problem either hard or easy to solve. As a measure of problem difficulty for 2-opt we use the approximation ratio that it achieves on a given instance. Our investigations point out important features that make TSP instances hard or easy to be approximated by 2-opt.     

A structural approach to reversible computation

Reversibility is a key issue in the interface between computation and physics, and of growing importance as miniaturization progresses towards its physical limits. Most foundational work on reversible computing to date has focussed on simulations of low-level machine models. By contrast, we develop a more structural approach. We show how high-level functional programs can be mapped compositionally (i.e. in a syntax-directed fashion) into a simple kind of automata which are immediately seen to be reversible. The size of the automaton is linear in the size of the functional term. In mathematical terms, we are building a concrete model of functional computation. This construction stems directly from ideas arising in Geometry of Interaction and Linear Logic—but can be understood without any knowledge of these topics. In fact, it serves as an excellent introduction to them. At the same time, an interesting logical delineation between reversible and irreversible forms of computation emerges from our analysis.     

A structural approach to robust control

We consider the problem of stabilizing linear stationary parametrically uncertain systems with a guaranteed stability margin. The methodology of our approach is based on the synthesis of superstable closed systems, done with the procedures derived from the block control principle and their modifications, the procedures consisting of sequential establishment of local connections in elementary blocks that provide for the superstability of each block and the closed system as a whole in the new coordinate basis. The fact that the notion of superstability is formulated in terms of the elements of the system matrix based on inequalities lets us provide for robust stability for all admissible values of indefinite parameters in such systems. The robust control algorithms that we have developed are applicable to a practically significant class of linear systems which, given that parameters change in known ranges, preserve structural controllability properties defined by the nominal system.     

A knowledge-based approach to design

A framework is presented for constructing knowledge-based aids for design problems. In particular, we describe the organization of an interactive knowledge-based consultant for VLSI design (called VEXED?an acronym for VLSI expert editor), and a prototype implementation of VEXED. The paper focuses on the principles underlying the design of VEXED, and on several lessons and research issues that have arisen from implementing and experimenting with this prototype.     

Particle swarm approach for structural design optimization

This paper presents in detail the background and implementation of a particle swarm optimization algorithm suitable for constraint structural optimization tasks. Improvements, effect of the different setting parameters, and functionality of the algorithm are shown in the scope of classical structural optimization problems. The effectiveness of the approach is illustrated by three benchmark structural optimization tasks. Results show the ability of the proposed methodology to find better optimal solutions for structural optimization tasks than other optimization algorithms.