Abstract: Probabilistic optimization design offers tools for making reliable decisions with the consideration of uncertainty associated with design variables/parameters and simulation models. In a probabilistic design, such as reliability-based design and robust design, the design feasibility is formulated probabilistically such that the probability of the constraint satisfaction (reliability) exceeds the desired limit. The reliability assessment for probabilistic constraints often involves an iterative procedure; therefore, two loops are involved in a probabilistic optimization. Due to the double-loop procedure, the computational demand is extremely high. To improve the efficiency of a probabilistic design, a novel method – sequential optimization and reliability assessment (SORA) is developed in this paper. The SORA method employs a single-loop strategy where a serial of cycles of optimization and reliability assessment is employed. In each cycle optimization and reliability assessment are decoupled from each other; no reliability assessment is required within optimization and the reliability assessment is only conducted after the optimization. The key concept of the proposed method is to shift the boundaries of violated deterministic constraints (with low reliability) to the feasible direction based on the reliability information obtained in the previous cycle. Hence the design is quickly improved from cycle to cycle and the computational efficiency is improved significantly. Two engineering applications, the reliability-based design for vehicle crashworthiness of side impact and the integrated reliability and robust design of a speed reducer, are presented to demonstrate the effectiveness of the SORA method.Copyright © 2002 by ASME

Abstract: Developing a robust, product platform architec- ture brings an important competitive advantage to a company. The major benefits are reduced design effort and time-to-market for future generations of the product. This paper describes a step-by-step method that aids companies in developing such product platform architectures. Using the concept of specification ''flows'' within a product de- velopment project, the design for variety (DFV) method develops two indices to measure a product's architecture. The first index is the generational variety index (GVI), a measure for the amount of redesign effort required for future designs of the product. The second index is the coupling index (CI), a measure of the coupling among the product components. The design team uses these two indices to develop a decoupled architecture that requires less design effort for follow-on products. This paper describes the DFV method and uses a water cooler example to illustrate the method.

Abstract: This paper presents a state of the art review of existing research, projects, and applications in the domain of collaborative conceptual design, based on the Internet and Web technologies. The purpose of the review is to understand the needs for conceptual engineering design, to clarify the current conceptual design practice, to classify the available technologies, and to study the future trend in this area. The emphasis of this paper is to briefly outline the methodologies, architectures, and tools developed for the projects reviewed in this paper. It also uncovers approaches to conflict resolution and team/project management, as they are vital to a successful engineering design in a collaborative environment. More than 80 journal and conference papers and about 20 projects are reviewed based on the primary focus mentioned above. The selected research works are further categorised into several areas based on the application domain, design theory, and the technology used for implementation. The selected research projects and applications are basically for, but not limited to, the collaborative conceptual design.

Abstract: In 1998, after six years of joint work originally foreseen under the ITER engineering design activities (EDA) agreement, a design for ITER had been developed fulfilling all objectives and the cost target adopted by the ITER parties in 1992 at the start of the EDA. While accepting this design, the ITER parties recognized the possibility that they might be unable, for financial reasons, to proceed to the construction of the then foreseen device. The focus of effort in the ITER EDA since 1998 has been the development of a new design to meet revised technical objectives and a cost reduction target of about 50% of the previously accepted cost estimate. The rationale for the choice of parameters of the design has been based largely on system analysis drawing on the design solutions already developed and using the latest physics results and outputs from technology R&D projects. In so doing the joint central team and home teams converge towards a new design which will allow the exploration of a range of burning plasma conditions. The new ITER design, whilst having reduced technical objectives from its predecessor, will nonetheless meet the programmatic objective of providing an integrated demonstration of the scientific and technological feasibility of fusion energy. Background, design features, performance, safety features, and R&D and future perspectives of the ITER design are discussed.

Abstract: This paper describes a hierarchical computational procedure for optimizing material distribution as well as the local material properties of mechanical elements. The local properties are designed using a topology design approach, leading to single scale microstructures, which may be restricted in various ways, based on design and manufacturing criteria. Implementation issues are also discussed and computational results illustrate the nature of the procedure.

Abstract: Analytical target cascading (ATC) is a relatively new methodology for the design of engineering systems. ATC deals with the issue of propagating desirable top level product design specifications (or targets) to appropriate targets at lower levels in a consistent and ecient manner. Most existing problem formulations for multilevel design often exhibit convergence diculties. In this article, it is proved that under convexity assumptions the ATC process converges to the optimal solution of the original design target problem.

Abstract: This second article of our series looks at the process of designing a survey. The design process begins with reviewing the objectives, examining the target population identified by the objectives, and deciding how best to obtain the information needed to address those objectives. However, we also need to consider factors such as determining the appropriate sample size and ensuring the largest possible response rate.To illustrate our ideas, we use the three surveys described in Part 1 of this series to suggest good and bad practice in software engineering survey research.

Abstract: Robust design has been gaining wide attention, and its applications have been extended to making reliable decisions when designing complex engineering systems in a multidisciplinary design environment. Though the usefulness of robust design is widely acknowledged for multidisciplinary design systems, its implementation is rare. One of the reasons is the complexity and computational burden associated with the evaluation of performance variations caused by the randomness (uncertainty) of a system. A multidisciplinary robust design procedure that utilizes efficient methods for uncertainty analysis is developed here. Different from the existing uncertainty analysis techniques, our proposed techniques bring the features of a multidisciplinary design optimization I MDO) framework into consideration. The system uncertainty analysis method and the concurrent subsystem uncertainty analysis method are developed to estimate the mean and variance of system performance subject to uncertainties associated with both design parameters and design models. As shown both analytically and empirically, compared to the conventional Monte Carlo simulation approach, the proposed techniques used for uncertainty analysis will significantly reduce the number of design evaluations at the system level and, therefore, improve the efficiency of robust design in the domain of MDO. A mathematical example and an electronic packaging problem are used as examples to verify the effectiveness of these approaches.

Abstract: The technical complexities inherent in today's optical components, systems and networks make the use of dedicated software tools for researchers and designers not a luxury, but a bare necessity [1]. One important category of such software tools provides the capability to simulate the physical behavior of optical systems by modeling time-dependent signal propagation; the results allow the user to assess the performance of a design, for instance with respect to the bit error rate to expect under certain conditions. A broad range of applications can benefit from this capability, including naturally research and design, but also product evaluation and technical marketing. Due to the wide range of scales involved - from wavelength-sized resonators in lasers and filters, to interactions in global networks - such design tools must employ highly advanced simulation technology. This chapter outlines the status of design software which is commercially available today, covering simulator technology as well as modeling problems. While the availability of accurate and efficient software is a prerequisite for successful modeling of optical systems, its application in a real-world engineering environment still faces many problems. The most dominant problems include a lack of qualified designers, a lack of support for the design process within the tools, and finally a lack of precise input data as required for an accurate simulation. We discuss development trends that strive to improve the practical usability by introducing concepts which address the problems mentioned above.

Abstract: Many engineering design applications require geometric modeling and mechanical simulation of thin flexible structures, such as those found in the automotive and aerospace industries Traditionally, geometric modeling, mechanical simulation, and engineering design are treated as separate modules requiring different methods and representations Due to the incompatibility of the involved representations the transition from geometric modeling to mechanical simulation, as well as in the opposite direction, requires substantial effort However, for engineering design purposes efficient transition between geometric modeling and mechanical simulation is essential We propose the use of subdivision surfaces as a common foundation for modeling, simulation, and design in a unified framework Subdivision surfaces provide a flexible and efficient tool for arbitrary topology free-form surface modeling, avoiding many of the problems inherent in traditional spline patch based approaches The underlying basis functions are also ideally suited for a finite-element treatment of the so-called thin-shell equations, which describe the mechanical behavior of the modeled structures The resulting solvers are highly scalable, providing an efficient computational foundation for design exploration and optimization We demonstrate our claims with several design examples, showing the versatility and high accuracy of the proposed method

Abstract: This article will review recent developments in dividing-wall column technology and provide guidelines for the design of these columns. Finally, two applications will be discussed to illustrate the design process.

Abstract: The paper introduces a new version of the Bi-Level Integrated System Synthesis (BLISS) methods intended for optimization of engineering systems conducted by distributed specialty groups working concurrently and using a multiprocessor computing environment. The method decomposes the overall optimization task into subtasks associated with disciplines or subsystems where the local design variables are numerous and a single, system-level optimization whose design variables are relatively few. The subtasks are fully autonomous as to their inner operations and decision making. Their purpose is to eliminate the local design variables and generate a wide spectrum of feasible designs whose behavior is represented by Response Surfaces to be accessed by a system-level optimization. It is shown that, if the problem is convex, the solution of the decomposed problem is the same as that obtained without decomposition. A simplified example of an aircraft design shows the method working as intended. The paper includes a discussion of the method merits and demerits and recommendations for further research.

Abstract: An improvement methodology is proposed for the design process in construction projects. Based on concepts and principles of lean production, the methodology considers the design process as a set of three different models—conversion, flow, and value. Four stages are necessary to produce improvements and changes— ~1! diagnosis/evaluation; ~2! changes implementation; ~3! control; and ~4! standardization. The methodology suggests the application of seven tools in accordance to specific needs ~detected and desired! on five potential areas of improvement—client, administration, project, resources, and information. Results of an application included an increase of 31% in the share of value adding activities, 44% reduction of unit errors in the products, up to 58% decrease of waiting times in the process, and an expansion of the utilization in the cycle times. In this manner, not only did the efficiency and effectiveness of internal engineering products improve, but also the whole project, by improving one of the main suppliers of construction.

Abstract: A process, as a kind of system, derives its added value from the relationships among its elements (e.g., activities). For a group of activities to be truly integrated (versus merely aggregated), the flow of deliverables among them must be well defined, agreed to, and committed to. Engineering processes are especially complex because of the large number of interdependencies among the activities, as many types of information flow to many destinations. A process model of what actually flows must be extracted from the existing, implicit way work really gets done. Since this requires getting “close” to where work is actually done, it is beyond the ability of a single, centralized group to build the entire model. Instead, a number of process “puzzle pieces” must be integrated into a single process model that will have more holistic descriptive, analytical, and prescriptive value. (The systems engineering “V” model applies to processes as well as to products.) This paper applies a powerful technique for representing and analyzing complex processes, the design structure matrix (DSM). The paper shows how to use the DSM to display both internal and external inputs and outputs, thereby defining the “edges” of the process puzzle pieces so they can be assembled to form large, integrated processes where value can flow. Process definition and integration is akin to “mapping the genome” of how work is efficiently and effectively accomplished across disciplines and organizations. It is an important enabler of process understanding and improvement. © 2002 Wiley Periodicals, Inc. Syst Eng 5: 180–193, 2002

Abstract: The design of high technology structures aims to define the best compromise between cost and safety. The Reliability-Based Design Optimization (RBDO) allows us to design structures which satisfy economical and safety requirements. However, in practical applications, the coupling between the mechanical modelling, the reliability analyses and the optimization methods leads to very high computational time and weak convergence stability. Traditionally, the solution of the RBDO model is achieved by alternating reliability and optimization iterations. This approach leads to low numerical efficiency, which is disadvantageous for engineering applications on real structures. In order to avoid this difficulty, we propose herein a very efficient method based on the simultaneous solution of the reliability and optimization problems. The procedure leads to parallel convergence for both problems in a Hybrid Design Space (HDS). The efficiency of the proposed methodology is demonstrated on the design of a steel hook, where the RBDO is combined with Finite Element Analysis (FEA).

Abstract: 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.

Abstract: Cost and schedule increases are common in engineering design projects Some research has studied factors associated with better design performance, but the reasons for cost and schedule increases are not formally investigated This paper identifies the reasons bottom up from four case project documents and further quantifies their contributions to cost and schedule increases These reasons are complete and can be used to analyze the cause-effect relationship, trace responsibility, and improve performance for engineering design projects

Abstract: This paper presents a design methodology for synthesizing organizations to execute complex missions efficiently. It focuses on devising mission planning strategies to optimally achieve mission goals while optimally utilizing organization's resources. Effective planning is often the key to successful completion of the mission, and conversely, mission failure can often be traced back to poor planning. Details on subsequent phases of the design process to construct the mission-driven human organizations are discussed in a companion paper.

Abstract: The design process can be conceptualized in at least three different ways: 1) as a process of transforming inputs into outputs, 2) as a flow of information through time and space, and 3) as a process for generating value for customers. Case studies and research findings to date indicate that design management in construction is deficient from all three of these points of view. In this paper, a series of experiments aiming at creating clarity and introducing systematic management principles from all three perspectives is described. The results of these experiments suggest that the use of relatively simple, albeit theory-driven, tools can achieve major improvements in the process of construction design. It is argued that only when based on suitable conceptualizations, and informed by empirical data, can effective methods be devised to ameliorate construction design and engineering.