Autonomous task decision-making and its implications for job design

This paper describes a model for task related decision-making. A distinction is made between three types of task decisions: boundary control decisions, which related the task system to its environment; intrasystem control decisions, which determine the means of performing the assigned tasks; and regulation decisions, which counteract disturbances that may affect task performance. Propositions for autonomous decision-making by the task performer under various conditions, derived from the model, were confirmed through extensive investigations of actual workstations.

Implications of research findings on job design are also discussed.     

An adaptive framework for aligning (re)planning decisions on supply chain strategy,design, tactics,and operations

Over the last decade, a wealth of valuable approaches to supply chain strategic, tactical, and operational planning has been extensively developed. However, conventionally the planning decisions at each of these levels have been considered in isolation from the other levels. Moreover, decisions on supply chain strategy, design, tactics, and operations are interlinked and dispersed over different supply chain structures (functional, organisational, informational, financial, etc.). This study develops a framework to increase the efficiency, consistency, implacability, and sustainability of decisions on how to design, plan, and run supply chains. In this paper it is proposed that comprehensive planning as an adaptive process encapsulates the planning decisions to be interrelated at all the decision-making levels. A conceptual model is described interlinking the supply chain strategy, design, planning, and operations on adaptation principles. Subsequently, a mathematical modelling complex and its realisation in a software environment is presented. This study contributes to developing methodical basics and practical tools to transit from simple open time slots incremental planning to dynamic, feedback-based adaptive supply chain planning. The elaborated framework serves to increase the efficiency, consistency, implacability, and sustainability of decisions on supply chain strategy, design, tactics, and operations. Decisions alignment can help to increase the wealth of organisations by producing demand-corresponding products in the most cost-effective manner through increasing agility, responsiveness, reaction speed to market changes, and continuous comprehensive improvements/adaptation of supply chains.     

Bridge strike reduction: optimising the design of markings

Cases of high-sided vehicles striking low bridges is a large problem in many countries, especially the UK. This paper describes an experiment to evaluate a new design of markings for low bridges. A full size bridge was constructed which was capable of having its overhead clearance adjusted. Subjects sat in a truck cab as it drove towards the bridge and were asked to judge whether the vehicle could pass safely under the bridge. The main objective of the research was to determine whether marking the bridge with a newly devised experimental marking would result in more cautious decisions from subjects regarding whether or not the experimental bridge structure could be passed under safely compared with the currently used UK bridge marking standard. The results show that the type of bridge marking influenced the level of caution associated with decisions regarding bridge navigation, with the new marking design producing the most cautious decisions for the two different bridge heights used, at all distances away from the bridge structure. Additionally, the distance before the bridge at which decisions were given had an effect on the level of caution associated with decisions regarding bridge navigation (the closer to the bridge, the more cautious the decisions became, irrespective of the marking design). The implications of these results for reducing the number of bridge strikes are discussed.     

The design of robust value-creating supply chain networks

This paper provides a methodology for supply chain network (SCN) design under uncertainty. The problem is initially casted as a two-level organizational decision process: the design decisions must be made here and now, but the reengineered SCN can be used for daily operations only after an implementation period. The network structure can also be adapted during the planning horizon considered. When making the design decisions, the operational response and structural adaptation decisions taking place during the planning horizon must be anticipated. The methodology recognizes three event types to characterize the future SCN environment: random, hazardous and deep uncertainty events. At the design time, plausible futures are anticipated through a scenario planning approach. Several Monte Carlo scenario samples are generated and corresponding sample average approximation programs are solved in order to produce a set of alternative designs. A multi-criteria design evaluation approach is then applied to select the most effective and robust design among candidate solutions. An illustrative case, based on the location–transportation problem, is finally introduced to illustrate the approach, and computational experiments are performed to demonstrate its feasibility.     

Once is not enough: repeated exposure to and aesthetic evaluation of an automobile design prototype

In industry, design selection and refinement decisions are frequently based on consumers' one-time aesthetic impressions of a proposed design. This paper reports on a study in which the same group of people were asked to evaluate a design prototype on two separate occasions at a 3-month interval. The results reveal that their perceptions of a design concept appear to change with repeated exposure. This finding suggests that design evaluation protocols which rely on a one-time evaluation may provide misleading information to designers and design decision-makers about consumer enthusiasm for a given design over its production lifetime.     

A functional failure reasoning methodology for evaluation of conceptual system architectures

In this paper, we introduce a new methodology for reasoning about the functional failures during early design of complex systems. The proposed approach is based on the notion that a failure happens when a functional element in the system does not perform its intended task. Accordingly, a functional criticality is defined depending on the role of functionality in accomplishing designed tasks. A simulation-based failure analysis tool is then used to analyze functional failures and reason about their impact on overall system functionality. The analysis results are then integrated into an early stage system architecture analysis framework that analyzes the impact of functional failures and their propagation to guide system-level architectural design decisions. With this method, a multitude of failure scenarios can be quickly analyzed to determine the effects of architectural design decisions on overall system functionality. Using this framework, design teams can systematically explore risks and vulnerabilities during the early (functional design) stage of system development prior to the selection of specific components. Application of the presented method to the design of a representative aerospace electrical power system (EPS) testbed demonstrates these capabilities.     

Axiomatic approach to structural design

As civil engineering enters the 21st century, the demands on the profession will move toward complex, interdisciplinary tasks such as infrastructure rehabilitation, environmental cleanup, and the delivery of high-technology facilities (e.g., hospitals, R&D laboratories, and advanced manufacturing plants). The current structural design paradigm is a top-down process that includes a nonhomogeneous approach to decision-making. There is an apparent lack of basic principles to formalize and evaluate conceptual design decisions while preliminary and detailed design decisions reflect increasing formalization and reliance on computational methods. This nonhomogeneous approach to decision-making limits how well the practicing engineer can meet the impending design challenges; particularly since conceptual design decisions determine a significant portion of a project's total cost. Axiomatic design is presented as a systematic framework for structural design because it aids the designer in satisfying multiple design objectives in a homogeneous manner throughout the design process. It is also an effective framework for formalizing and evaluating conceptual design decisions. The design of a structural frame for an innovative mechanical parking system is presented as an illustrative case study. This paper represents an initial effort to apply the principles of axiomatic design to the domain of civil engineering structures.     

Identified research directions for using manufacturing knowledge earlier in the product life cycle

Design for manufacturing (DFM), especially the use of manufacturing knowledge to support design decisions, has received attention in the academic domain. However, industry practice has not been studied enough to provide solutions that are mature for industry. The current state of the art for DFM is often rule-based functionality within computer-aided design (CAD) systems that enforce specific design requirements. That rule-based functionality may or may not dynamically affect geometry definition. And, if rule-based functionality exists in the CAD system, it is typically a customisation on a case-by-case basis. Manufacturing knowledge is a phrase with vast meanings, which may include knowledge on the effects of material properties decisions, machine and process capabilities or understanding the unintended consequences of design decisions on manufacturing. One of the DFM questions to answer is: How can manufacturing knowledge, depending on its definition, be used earlier in the product life cycle to enable a more collaborative development environment? This paper will discuss the results of a workshop on manufacturing knowledge that highlights several research questions needing more study. This paper proposes recommendations for investigating the relationship of manufacturing knowledge with shape, behaviour and context characteristics of a product to produce a better understanding of what knowledge is most important. In addition, the proposal includes recommendations for investigating the system-level barriers to reusing manufacturing knowledge and how model-based manufacturing may ease the burden of knowledge sharing. Lastly, the proposal addresses the direction of future research for holistic solutions of using manufacturing knowledge earlier in the product life cycle.     

Design for manufacturing: application of collaborative multidisciplinary decision-making methodology

Design for manufacturing is often difficult for mechanical parts, since significant manufacturing knowledge is required to adjust part designs for manufacturability. The traditional trial-and-error approach usually leads to expensive iterations and compromises the quality of the final design. The authors believe the appropriate way to handle product design for manufacturing problems is not to formulate a large design problem that exhaustively incorporates design and manufacturing issues, but to separate the design and manufacturing activities and provide support for collaboration between engineering teams. In this article, the Collaborative Multidisciplinary Decision-making Methodology is used to solve a product design and manufacturing problem. First, the compromise Decision Support Problem is used as a mathematical model of each engineering teams’ design decisions and as a medium for information exchange. Second, game-theoretic principles are employed to resolve couplings or interactions between the teams’ decisions. Third, design-capability indices are used to maintain design freedom at the early stages of product realization in order to accommodate unexpected downstream design changes. A plastic robot-arm design and manufacturing scenario is presented to demonstrate the application of this methodology and its effectiveness for solving a complex design for manufacturing problem in a streamlined manner, with minimal expensive iterations.     

Conceptual robustness in simultaneous engineering: An extension of Taguchi's parameter design

Simultaneous engineering processes involve multifunctional teams; team members simultaneously make decisions about many parts of the product-production system and aspects of the product life cycle. This paper argues that such simultaneous distributed decisions should be based on communications about sets of possibilities rather than single solutions. By extending Taguchi's parameter design concepts, we develop a robust and distributed decision-making procedure based on such communications. The procedure shows how a member of a design team can make appropriate decisions based on incomplete information from the other members of the team. More specifically, it (1) treats variations among the designs considered by other members of the design team asconceptual noise; (2) shows how to incorporate such noises into decisions that are robust against these variations; (3) describes a method for using the same data to provide preference information back to the other team members; and (4) provides a procedure for determining whether to release theconceptually robust design or to wait for further decisions by others. The method is demonstrated by part of a distributed design process for a rotary CNC milling machine. While Taguchi's approach is used as a starting point because it is widely known, these results can be generalized to use other robust decision techniques.     

Cooperation in aircraft design

We describe how aircraft are designed in a large organization. We discuss the different phases of design and interaction with the customer. We then describe the models used by each specialist department and the interactions among departments during the design process. We observe that the main design choices are refinement operations on the design. We then briefly describe how the negotiation process is controlled by an organizationally agreed sequence of commitment steps. We then describe negotiation at higher levels in the organization. What decisions are made, the compromises worked out, and the effect of these higher-level commitments on the design process.We conclude that: (1) aircraft design proceeds by thecooperation ofspecialists (specialist teams or departments); (2) each specialist has its ownmodel of the design, and may use several different models or partial models for different purposes; (3) specialists have limited ability to understand each other's models. They communicate using ashared vocabulary, but not necessarily shared technical knowledge; (4) design proceeds by successiverefinement of the models, which are coordinated and updated together; (5) the design decisions, which are acts of commitment and model refinement, arenegotiated by the specialists among themselves; (6) one way this negotiation process is organized and controlled is by the use ofcommitment steps; (7) negotiations occur at higher levels in the organization, resulting in commitments which greatly influence and constrain the design process and its organization, and which have the greatest effect on the cost of the product.     

Design of Common Components Considering Implications of Inventory Costs and Forecasting

This paper is related to component (or module) design decisions. It deals with instances in which non-substitutable components of a similar nature are used in different product lines. The question addressed is whether one should invest in efforts to redesign so that several similar (but not the same) components may be replaced by a common one. Reduction of the standard error of forecast and its implications to inventory systems are utilized toward decisions for commonality. Clustering algorithms are presented.     

Collaborative multidisciplinary decision making using game theory and design capability indices

The complexity of modern product realization processes requires collaborative work of engineering teams from different disciplines. We apply principles from game theory to model the relationships between engineering teams and facilitate collaborative decision making. In order to maintain design freedom in the early stages of product realization so that engineering teams in the later stages can adjust their decisions while still maintaining feasibility, we postulate the use of design capability indices to facilitate the teams making a ranged set of decisions, instead of specific ones. The effect of game theoretic principles and design capability indices on design freedom and therefore on the design solutions is also investigated. An electronic package design and analysis scenario is used to demonstrate the efficacy of the proposed method.     

Branch-and-price approach for prescribing profitable feature upgrades

High technology products such as notebook computers and digital cameras have short life cycles due to global competition and rapid technological advances. As newer products, replete with latest technologies, become available, the demand for older products erodes. To renew the competitiveness of a product, the manufacturer may upgrade its features over time. Since products comprise a set of features with several alternatives for each, design involves complicated decisions: which features to upgrade, what alternatives should be chosen, and when to upgrade. This paper proposes a model to prescribe profitable upgrades of individual features in a family of products. The model integrates decisions traditionally made by various organizations in the enterprise (marketing, product design engineering, process design engineering, production planning and supply chain management). The special structures embedded in the model are identified and decomposition principles are applied to solve large-scale instances of the size and scope encountered in industry. Tests establish computational benchmarks, showing that this decomposition approach outperforms a commercial solver, most dramatically on more challenging instances. The solution obtained by solving the model will aid managers in deciding the content and timing of upgrades to maximize life cycle profit.     

An argumentation-based method for managing complex issues in design of infrastructural systems

The many interacting and conflicting requirements of a wide range of stakeholders are the main sources of complexity in the infrastructure and utility systems. We propose a systemic methodology based on negotiation and argumentation to help in the resolution of complex issues and to facilitate options appraisal during design of such systems. A process-based approach is used to assemble and propagate the evidence on performance and reliability of the system and its components, providing a success measure for different scenarios or design alternatives. The reliability of information sources and experts opinions are dealt with through an extension of the mathematical theory of evidence. This framework helps not only in capturing the reasoning behind design decisions, but also enables the decision-makers to assess and compare the evidential support for each design option.     

Ergonomics in design education: a user-centred approach

Despite unprecedented technological capability much of our environment is poorly designed in ergonomic terms. Using a simple model of the design process this paper argues the impossibility of ensuring that all design decisions are taken by qualified ergonomists. It suggests that whereas it is not reasonable to expect clients, production engineers or designers to be especially interested in the scientific base of ergonomics it is both reasonable and realistic to attempt to give them a more homocentric perspective on design. An educational approach developed at the Open University is described which is aimed primarily at modifying attitudes to design and which introduces ergonomics by stealth. Although unorthodox, this approach is paradoxically ergonomically paradigmatic and its potential lessons for fulltime ergonomists are considered.     

Ever improve–a guide to managing production the TOC way by O. Cohen

Over the past decades, several companies have introduced product platforms in the design of their products in order to produce a large product variety in a cost-efficient way. However, for some companies, the introduction of platforms ended up being more costly than expected, leading them to reconsider their platform decisions. In this paper, we develop a model to support companies in determining (1) how many platforms to develop, (2) which platforms to develop and (3) which products to derive from which platforms. The model takes into account the impact of these product-platform decisions on a company’s relevant supply chain activities and costs. The model shows how the optimal product-platform decisions depend on the trade-off between the costs of platforms versus the costs of customising these platforms to final product variants. We propose a simulated annealing algorithm to solve large problem instances within reasonable time. The practical validity of our model is shown through its application in a global technology company specialised in the development and production of medical screens.     

A risk-based approach to manufacturing process control: use in autoclave moulded composite sandwich panels

The quality of a design solution is largely the consequence of making informed decisions based on the quality of available information. This information is not always accurate or reliable and therefore its use is not without risk, forcing designers to be conservative. The design of mechanical components is dependent amongst other things on the materials and manufacturing processes utilised. Composites are unique in that the component configuration, material and manufacturing process can be simultaneously manipulated, allowing highly optimised structures to be designed. Risk analysis is a pragmatic way of managing the variability of such information and therefore the risk associated with design for manufacture decision-making. This paper investigates the use of statistical process control techniques for improving the consistency of autoclave moulded composite components.     

Human factors methods for early evaluation of control room systems – guidelines for use in practice

Formative human factors (HF) evaluation is an important activity in control room design. Its purpose is to provide design feedback in the development process, preferably early so as to lower the risk of late and sub-optimal design changes. Early evaluation requires assessment of higher level design decisions due to the gradual specificity of design decisions made as the development process progresses. There is also a need to further develop HF methods that are applicable in practice. The purpose of this article is to seek understanding of, and base guidelines on, the practical use of HF methods for formative assessment of higher level design decisions in control rooms. Evaluations in three development projects at a Swedish nuclear power plant were studied, identifying 18 method guidelines. The guidelines related to: 1) the method’s ability to define, adapt, focus and balance; 2) execution of the evaluation workshops; 3) the communicative purpose of the evaluation activity. Comparing the identified guidelines with literature showed similarities, but also highlighted unique guidelines. The compiled results can be used to further develop methods for early formative evaluation of control rooms in practice.     

Knowledge base for the systematic design of wet cooling towers. Part I: Selection and tower characteristics

This paper describes part of the detailed methodology for the thermal design of wet, counterflow and crossflow types of mechanical and natural draught cooling towers. Starting with a brief introduction, an attempt is made here to present different steps of cooling tower design. The steps include: selection of a cooling tower; determination of tower characteristic ratio; computation of moist air properties; determination of the ratio of the water-to-air loading; integration procedure for the tower characteristic ratio. The design of a cooling tower needs the use of different logical decisions, empirical relations and assumptions. The choice of a proper tower and its proper design would increase its efficiency and help conserve energy.