A Method for Architecting Product Platforms

Consider a group of products sharing common parts and assemblies. The products in question we call a product family, and the common elements, the platform. In this paper, we present a method for designing product platforms and the derived family that takes into consideration both the technical performance requirements as well as the cost of the product family. The design of a platform-based product family is formulated as a general optimization problem in which the advantages of designing a common platform must be balanced against the constraints of the individual product variants and constraints of the family as a whole. This optimization approach forms the basis for a practical implementation as an interactive, team-based negotiation model for designing a family of interplanetary spacecraft based on a common platform. The approach is used to consider and specify different subsystems that could be made common to all the missions. It is also used to evaluate the impact of those platform design decisions on the performance of the product family, and thus be able to select from among feasible platform designs.     

Developing Strategic Alliances: A Framework for Collaborative Negotiation in Design

This work applies a theory-based framework of collaborative negotiation to some of the disputes that regularly arise during group design. Although the framework was developed to provide general support for group work, this paper focuses on its use as a design tool. The framework, embodied in our system NegotiationLens, has four facets. It: 1. Provides a negotiation method intended to produce gain for all parties. 2. Provides an efficient process for conflict resolution. 3. Develops working alliances. 4. Lets parties decide quickly when they should go their separate ways. The framework produces the above results by: • Helping parties develop well-reasoned and clearly articulated points of view (Adelson and Jordan, 1991; Conklin and Yakemovic, 1991; Conklin and Begeman, 1988; MacLean et al ., 1991). • Creating a context of committment and respect. • Moving negotiating parties away from an adversarial stance and into a collaboration. • Allowing joint construction of solutions that are more beneficial than the unilateral solutions each party initially brought to the table. We present our framework for collaborative negotiation, describe NegotiationLens, and present two cases in which it was used. We present a third case, a large design project with recurrent design conflicts, and argue how NegotiationLens could have been of benefit there.     

A Subjective Design Framework for Conceptual Design of Polymeric Processes with Multiple Parameters

Polymer processes are in general difficult to model, especially because of coupling between process conditions, polymeric behaviors and geometries. Arising from high thermal gradients, non-Newtonian viscous behaviors and non-linear pressure effects, polymer processing is not well described mathematically. A conceptual design methodology is proposed formally as a useful tool for treating polymeric processes with multiple performance parameters on a structured design platform. Without resorting to engineering models, this approach deals with the initial selection of process conditions within a three-stage framework: (1) qualitative design; (2) process modeling; and (3) quantitative design. Based on subjective reasoning, this procedure makes it possible to account for one’s prior experience, and incorporate it into the process development. The notion of conceptual robutstness is introduced to ensure deesign quality in the early-stage process development. A case study of compression molding is illustrated in a step-by-step manner.     

More than Just Robust Design: Why Product Development Organizations Still Contend with Variation and its Impact on Quality

Current market conditions require design and manufacturing companies to continually increase product functionality, reduce design cycles, decrease cost and improve quality. One way to improve quality is to minimize the impact part and process variation has on final product quality. Although companies know they must reduce variation, they are still struggling with executing coherent variation management strategies. To understand why companies still fail to systematically address variation, an ideal model of variation management is proposed, entitled Variation Risk Management (VRM). This model was used to assess the state of industry practice. These results are compared to the current literature available on the subject. It was found that many problems with industry implementation are due to a lack of quantitative models that enable a design team to make quick and accurate decisions. This paper concludes with a list of interesting challenges facing the VRM field.     

Framework for Modeling Dependencies in Collaborative Engineering Processes

This article describes an engineering process representation and modeling tool. The approach is especially suitable for describing large-scale, mature design processes involving numerous tasks, some of which may be performed by automated computer agents. The underlying representation is a graph of information-processing units with explicitly defined input and output feature elements. We show that this representation is more complete than those used in previous process modeling approaches and overcomes some of their limitations when dealing with design processes involving dependencies at multiple levels of detail. The representation is combined with rules for automatically operating upon the graph to preserve consistency when traversing to higher or lower levels of detail.     

CADOM: A Component Agent-based Design-Oriented Model for Collaborative Design

Information technology is the foundation for collaborative design. This paper reviews the state-of-the-art of the current research on product modeling, and a schema for a Design-Oriented Model (DOM) containing functional, structural and management data is proposed. The functional data explains the design purpose, function, object behavior and design rationale; the management data is for keeping the consistency of the model data, capturing the evolution process and controlling the operation action and authority; the structural data is the core of the model data. The integration of functional and management data directs the model towards design integration in place of application integration. The modeling system adopts the Component Agent (CA) mechanism that represents a complex product in an intelligent, autonomous hierarchy. A CA encapsulates the DOM data and consists of a definer, a communicator, an adaptor and a manager. These units are responsible for defining the model data, interacting with other agents, deriving special data and managing the constraints, version, authority and operation. Finally, several aspect supporting the collaborative design enabled by the CADOM (CA-based DOM) are discussed, as the multi-views model, the semantics communication between perspectives, the dynamic constraints management, the version and authority management, and the product and process integration. The discussion indicate that the model is an information infrastructure with more capabilities for collaborative design.     

A Multilevel Framework for Lean Product Development System Design

Abstract:

Organizations today face intense and growing pressure to reduce cost, decrease time to market, and maximize stakeholder value in product development (PD). Many organizations have adopted lean product development (LPD) methods in an attempt to improve their PD systems; however, despite two decades of research, there is still much less understanding of the characteristics of effective LPD systems than of effective lean manufacturing systems. LPD systems are complex systems involving multiple organizational levels; however, most LPD research to date has focused only on a single level. There is currently a lack of understanding of the interactions between levels and effective means for managing these interactions. In this article, we propose a multilevel framework designed to capture key LPD system principles at the functional, project, and portfolio levels; tools and practices for implementing principles at each level; and approaches for managing the interactions between levels. A longitudinal case study is used to expand and refine a conceptual framework developed through literature review. Future research should focus on further validating the framework and applying the framework to improve LPD system design.     

A Mathematical Framework for the Key Characteristic Process

To maximize product quality, a product design team selects concepts and dimensions to minimize a product’s sensitivity to variation. However, even for the most robust products, it is rarely possible to transition a product into production without encountering any variation-related problems. In a complex product, it is not economically or logistically feasible to control and/or monitor the thousands of tolerances specified in a product’s drawing set. To address this problem, many organizations are using Key Characteristic (KCs) methods to identify where excess variation will most significantly affect product quality, and what product features and tolerances require special attention from manufacturing. As simple as this principle seems, most companies struggle to effectively implement KC methods because no quantitative methods to prioritize KCs exist. This paper develops a mathematical definition of a KC based on a variation propagation model. In addition, it develops a quantitative effectiveness measure used to prioritize where verification, variation reduction, and on-going monitoring should be applied. The effectiveness measure incorporates the cost of control, the benefit of control, and the expected change in process capability. The methods are illustrated using an automotive door assembly.     

A Taxonomy for Design Requirements from Corporate Customers

We have developed a taxonomy that classifies those needs of a corporation that impact product design. We call these needs corporate requirements. In contrast to the consumer or end-user requirements, corporate requirements come from internal sources such as marketing, finance, manufacturing, and service. This taxonomy allows for an organized method of gathering, managing, and retrieving the requirements. The taxonomy also helps to facilitate a broader, clearer form of Quality Function Deployment. Generic in nature, this taxonomy provides a template with which to create taxonomies for a given product within a given company or industry. We include an industrial case study to demonstrate this concept.     

A Framework for Reliability Prediction During Product Development Process Incorporating Engineering Judgments

This paper presents a comprehensive framework for reliability prediction during the product development process. Early in the product development process, there is typically little or no quantitative evidence to predict the reliability of the new concept except indirect or qualitative information. The proposed framework addresses the issue of utilizing qualitative information in the reliability analysis. The framework is based on the Bayesian approach. The fuzzy logic theory is used to enhance the capability of the Bayesian approach to deal with qualitative information. This paper proposes to extract the information from various design tools and design review records and incorporate it into the Bayesian framework through a fuzzy inference system. The Weibull distribution is considered as failure/survival time distribution with the assumption of a known value of shape factor. Initial parameters of the Weibull distribution are estimated from warranty data of prior systems to estimate the initial Bayesian parameter ( λ_t). The applicability of the framework is illustrated via an example.     

A scheduling method for Berth and Quay cranes

This paper discusses a method for scheduling Berth and Quay cranes, which are critical resources in port container terminals. An integer programming model is formulated by considering various practical constraints. A two-phase solution procedure is suggested for solving the mathematical model. The first phase determines the Berthing position and time of each vessel as well as the number of cranes assigned to each vessel at each time segment. The subgradient optimization technique is applied to obtain a near-optimal solution of the first phase. In the second phase, a detailed schedule for each Quay crane is constructed based on the solution found from the first phase. The dynamic programming technique is applied to solve the problem of the second phase. A numerical experiment was conducted to test the performance of the suggested algorithms. RID="*" ID="*" This research has been supported in part by Brain Korea 21 Program (1999–2002). Correspondence to: Y.-M. Park     

Reduced outpatient waiting times with improved appointment scheduling: a simulation modelling approach

Abstract. An outpatient department represents a complex system through which many patients with varying needs pass each day. An effective appointment system is a critical component in controlling patient waiting times within clinic sessions. Current waiting times are often unacceptable and place great stress on clinic staff. This paper describes the development and use of a detailed simulation model of an Ear, Nose and Throat (ENT) outpatient department. The simulation allows various appointment schedules to be examined and their effects on the clinic evaluated. The model has been used to identify a number of critical factors that influence patient waiting times and the build up of queues in the clinic. Alternative appointment schedules have been shown to drastically reduce patient waiting times, without the need for extra resources, and enable the department to move towards meeting the UK Government's Patient's Charter. RID="*" ID="*" The authors would like to express their thanks for the valuable support provided by the anonymous participants (outpatient department staff). Thanks also to Helen Gilby, Dr Arjan Shahani and Professor Valter de Senna for their useful comments and help during the research. Correspondence to: P.R. Harper     

Portfolio management in the binomial model: conditions for outperforming benchmarks

The performance of a portfolio manager is in practice usually measured by the result of his trading strategy compared to a benchmark. Therefore the information whether there exists a strategy that allows to outperform the benchmark is of high value for an active investor. The article shows how this information can be generated in the binomial model. In this context the connection between trading strategies and the investor's expectations concerning future asset prices is analyzed. Based on these findings several conditions are derived that allow the portfolio manager to judge whether the benchmark can be outperformed by an active trading strategy. RID="*" ID="*" Thomas Balzer now works in the Risk Measurement & Management Department of Credit Suisse First Boston in London. The views expressed in this article are those of the author, and do not necessarily represent those of Credit Suisse Group or Credit Suisse First Boston. The author thanks Dr. Michael Olbrich for careful reading and several useful comments.     

A computational study of LP-based heuristic algorithms for two-dimensional guillotine cutting stock problems

In this paper we develop and compare several heuristic methods for solving the general two-dimensional cutting stock problem. We follow the Gilmore-Gomory column generation scheme in which at each iteration a new cutting pattern is obtained as the solution of a subproblem on one stock sheet. For solving this subproblem, in addition to classical dynamic programming, we have developed three heuristic procedures of increasing complexity, based on GRASP and Tabu Search techniques, producing solutions differing in quality and in time requirements. In order to obtain integer solutions from the fractional solutions of the Gilmore-Gomory process, we compare three rounding procedures, rounding up, truncated branch and bound and the solution of a residual problem. We have coded and tested all the combinations of algorithms and rounding procedures. The computational results obtained on a set of randomly generated test problems show their relative efficiency and allow the potential user to choose from among them, according to the available computing time. Rceived: January 9, 2001 / Accepted: December 10, 2001     

Coordination Approaches and Systems – Part I: A Strategic Perspective

This is the first part of a two-part paper presenting a fundamental review and summary of research of design coordination and cooperation technologies. The theme of this review is aimed at the research conducted within the decision management aspect of design coordination. The focus is therefore on the strategies involved in making decisions and how these strategies are used to satisfy design requirements. The paper reviews research within collaborative and coordinated design, project and workflow management, and, task and organization models. The research reviewed has attempted to identify fundamental coordination mechanisms from different domains, however it is concluded that domain independent mechanisms need to be augmented with domain specific mechanisms to facilitate coordination. Part II is a review of design coordination from an operational perspective.     

Lot-sizing for a single-stage single-product production system with rework of perishable production defectives

We consider a single-stage single-product production system. Produced units may be non-defective, reworkable defective, or non-reworkable defective. The system switches between production and rework. After producing a fixed number (N) of units, all reworkable defective units are reworked. Reworkable defectives are perishable or can become technologically obsolete. We assume that the rework time and the rework cost increase linearly with the time that a unit is held in stock. Therefore, N should not be too large. On the other hand, N should not be too small either, since there are set-up times and costs associated with switching between production and rework. For a given N, we derive an explicit expression for the average profit (sales revenue minus costs). Using this expression, the optimal value for N can be determined numerically. Moreover, it is easy to perform a sensitivity analysis, as we illustrate. RID="*" ID="*"The research of Dr. Ruud H. Teunter has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences. The research presented in this paper is part of the research on re-use in the context of the EU sponsored TMR project REVersed LOGistics (ERB 4061 PL 97-5650) in which take part the Otto-von-Guericke Universitaet Magdeburg (D), the Erasmus University Rotterdam (NL), the Eindhoven University of Technology (NL), INSEAD (F), the Aristoteles University of Thessaloniki (GR), and the University of Piraeus (GR). We thank the anonymous referees for their many helpful comments. Correspondence to: R. H. Teunter     

Decision support for AIDS control programmes in Eastern Africa

The Acquired Immune Deficiency Syndrome (AIDS) constitutes the worst hazard to health care systems in Eastern Africa. Misallocation of scarce resources of AIDS Control Programmes will unavoidably lead to additional infections and casualties. The following paper discusses a system dynamics model which allows to assess the impact of different interventions on a pattern population in Eastern Africa. It becomes obvious that short- and long-term consequences of these programmes differ significantly. The optimal allocation of resources, therefore, is highly complex and calls for decision support systems to sustain AIDS control programmes.     

Meta-heuristic based decision support for portfolio optimization with a case study on tracking error minimization in passive portfolio management

In this paper we describe the concept and design of a meta-heuristic based decision support system generator (DSS-generator) for portfolio optimization. We report extensively on experience with the application of a specific DSS that has been customized for controlling and optimizing passively managed stock funds. Here, the constraints from the law on investment trust companies as well as several fund specific guidelines prohibit that the benchmark can be identically reproduced. For measuring the performance of the portfolio a tracking error model with data stemming from a factor model is applied. Our results show that the system provides proposals for the fund manager in acceptable time which are feasible with respect to the guidelines and excellent in quality.     

On the steady state of the replicating portfolio: accounting for a growth rate

For the risk management and transfer pricing of non-maturity liabilities, banks in Europe often use a so-called replicating portfolio technique. A commonly used implementation is replication of a fixed investment rule every time period. This paper deals with the development of the portfolio in the long run, when using this methodology. Applying this replicating portfolio technique yields, after a while, a steady state. Besides the straightforward result when volume is constant, we solve the steady states for the case where the funds (volume) grow with a fixed rate (e.g. due to credited interest or growth in GDP). We therefore define a system growth process, alternative to the Markov process (when volume is constant). From a transfer pricing and risk-management point of view, the resulting portfolio should satisfy certain requirements concerning return and flexibility. Once the steady state can be calculated for given growth rates, the investment policy can be specified. The importance of taking account of a growth rate is illustrated. Growth in volume implies that a different rule will converge to the desired steady state. This is illustrated analytically and with numerical examples. The purpose of the paper is not to find the ideal hedge strategy for non-maturity liabilities, but to improve the existing risk management without any implementation costs for the banks. Given the currently used methodology, accounting for a growth rate can significantly improve the risk management of non-maturity liabilities. RID="*" ID="*" I thank Anja De Waegenaere, Peter Kort and an anonymous referee for useful comments on an earlier draft.     

A Dominance-based Design Metric in Multiattribute Robust Design

This paper outlines the development of an effective and consistent ‘designing-in-quality’ strategy that can be used to deal with concepts of uncertainty, quality and robustness in engineering design. Specifically, this paper presents a decision analysis-based robust design metric that seamlessly integrates objective evaluations on the goodness of a design alternative with the designer’s intent and preferences. This is achieved through the development of a set of performance-reflecting dominance indices for the attributes and their utilization in a preference-influenced multiattribute utility formulation. Such a knowledge feedback-based decision model development will be particularly useful when dealing with complex iteration-based engineering design process where little information on the expected outcomes may be known a priori, or where product performance is computationally expensive to evaluate. Application of this robust design metric in a multi-stage experimentation and modeling design process is presented. The characteristics of the proposed design metric and the effectiveness of the overall design procedure in dealing with constrained engineering design problems are examined with the aid of demonstrative case studies and the results are discussed.