Managing object schemas in a distributed database architecture for concurrent engineering

Abstract

In recent years, object database systems have emerged as a new technology, integrating object‐oriented paradigms with transaction and query capabilities of conventional database systems. The strength of distributed object database systems is further enhanced by new generations of powerful workstations. The synergy between object databases and the networked workstation environment, however, brings forth a new set of challenges. In this paper, we address the issues of managing object schemas in a cooperative network environment. After reviewing existing solutions, we present a more dynamic approach to the problem of distributed schema management. We also show how this approach can serve as a general framework for supporting various schema management policies.     

Product design in a concurrent engineering environment: an optimization approach

In this paper an optimization approach to the design of products in a concurrent engineering environment is explored. A five-step algorithm containing attribute-based utility values is utilized which allows for the incorporation of concurrent engineering design attributes in the objective function. Two integer programming models are presented. Model 1 considers module/part interactions; however, it does not consider the interactions among various part options making up a product. Model 2 considers both interactions and also results in groups of part options that can be designed and manufactured together. In each step of the optimization process, the design of a pad assembly of a braking system is considered and explained.     

Requirements management: an enabler for concurrent engineering in the automotive industry

Defining and agreeing the product requirements is especially important when the design and manufacture of a system is part of an Extended Enterprise. To realize an all-inclusive concurrent engineering process, tools for the upstream design activities are needed. In practice, it is often difficult for the companies to have a shared understanding of what needs to be developed, and so specifications contain ambiguities in describing the product requirements. This paper clarifies the problem domain in the context of a complex product, designed and manufactured in a pan-national Extended Enterprise and serving a highly competitive market. The authors show how the challenge can be addressed through the application of ontology. A model of a requirements-management tool is proposed that will allow the various systems and associated levels of a product to be described and then shared through the supply chain. A prototype system is presented and illustrated through a case study from the automotive industry.     

Managing information for concurrent engineering: Challenges and barriers

An ongoing research project with a large international manufacturing company has uncovered many critical issues for the development and introduction of systems that supportconcurrent engineering. Several of these issues can be solved through careful interface design, while others require significant technical and organizational changes. To reduce training costs and support a broad spectrum of users, computer system developers must create a single system image, giving the users the impression that they are accessing a single database through a consistent and easy to use interface. This interface, and the tools it contains, may be used to support concurrent engineering activities even when a company is geographically distributed over a large area. The complexity of the firm's products and processes and the need for rapid access to relevant performance information make it essential that developers identify suitable frameworks for organizing database queries.Design hierarchies, representations of the structure and function of the firm's products and processes, have proven to be powerful tools for effective query management, and for efficient navigation through the database. The database interface must also produce integrated displays of data drawn from a number of sources in response to prestructured queries. Beyond these interface design issues, there are a number of technical and organizational barriers to the implementation of large-scale engineering systems. In particular, the existence of many incompatible databases in different parts of an organization makes the introduction of a new, uniform system very difficult. Organizational issues also play a major role in achieving, or hindering, the implementation of new computer systems. This paper describes some of the technical innovations, and the motivations behind them, from one particular engineering design system. It also discusses the reactions of engineers and management, and explains why management may oppose innovation even when engineers enthusiastically support it.     

Knowledge elicitation for risk mapping in concurrent engineering projects

Concurrent Engineering aims to incorporate the overlapping of processes in order to reduce its time-to-market and thereby sustain the existence of organizations in increasingly competitive times. Although faster product design, development, and delivery are the intended outcomes of concurrent engineering, one of the undesirable by-products is an increase in risks as a consequence of uncertainties between interdependent processes. Hence, the risks need to be identified, assessed, and mitigated together with concurrent engineering considerations for the elimination of the ‘domino-effect’ within risk management. This paper concentrates primarily on knowledge elicitation techniques that were used to provide information to the Intelligent Risk Mapping and Assessment System (IRMAS?) to identify, prioritise, analyse, and assist project managers to manage perceived sources of CE risks. Techniques such as expert interviews, brainstorming, the Delphi technique, and the analogy process are discussed in relation to compiling the knowledge used for this expert system. A total of 589 risk items were identified for different project types, and information on 4372 items and 136 lessons learned were collected from experts at HdH. The core of the research is a reasoning methodology used for Knowledge Elicitation of a Risk Mapping and Assessment System which will not only support the decision-making process of the user but also aid the knowledge retrieval, storage, sharing, and updating process of manufacturing organizations. This research provides a systematic engineering approach to risk management of concurrent product and process development.     

Distributed coordination space: Toward a theory of distributed team process and performance

This paper discusses a theoretical framework designed to elucidate the many issues surrounding distributed team performance, emphasizing how work characteristics associated with such teams may alter both the processes and the products emerging from distributed interaction. It is suggested that distributed team performance can best be understood through conceptualization of a coordination space within which distributed interaction occurs over time and distance. The goal is to take a socio-technical approach to distributed team research so that one can explicate both the cognitive consequences of a lack of co-location as well as the social consequences affecting interaction and team development when work is technology-mediated. The overall objective is to present a framework of 'distributed coordination' such that the principles most appropriate for distributed team performance can be developed.     

Designing in young organisations: engineering change propagation in a university design project

Engineering change (EC) is an important phenomenon in the design of products and systems, accounting for nearly one-third of the work effort; however, the literature has been focused on mature firms, and few studies have documented the impact of EC beyond them. Hence, we use a case study approach to study EC and its propagation in the context of a university design project as an example of young organisations, and compare it with the existing work done on mature firms. It was found that 33% of the changes that occurred in the case study were planned, and change propagation accounted for 20% of all changes. The propagation of changes was usually one step (67%), and it was concentrated in one independent network (54%). The results were subsequently compared with EC studies done in mature firms, being revealed that EC behaves differently in the context of a university design project; hence, existing change management tools developed to suit mature firms may not be directly suitable for supporting university design projects. The findings from this work can be used as a platform to better understand how EC propagates when designing in young organisations and shape the development of appropriate change management tools.     

I2QFD: A blackboard-based multiagent system for supporting concurrent engineering projects

Although Concurrent Engineering has been accredited as a superior approach to product development, its intrinsic complexity in coordinating the multidisciplinary project team is further augmented when team members are remotely distributed. Assuming the teamwork is supported by an Intranet, this paper proposes the framework of a blackboard-based multiagent system, called I 2 QFD, to facilitate the communication and coordination of the design projects. Configured within a hierarchical structure, this system is defined with IDEF0 and high-level Petri nets to depict the operations of Intelligent Agencies and their affiliated agents. Based on temporal logic, the operation of the project team with I 2 QFD is simulated to manifest the dynamics of the design process as well as to generate the project's schedule that ensures the intended concurrency.     

Evaluation of the contract reliability for alternative infrastructure project delivery: a contract engineering method

Governments at all levels are increasingly motivating the private sector to participate in infrastructure development using alternative project delivery methods to relieve financial burden. When designing contracts, governments usually offer incentives while requiring cost or time guarantee to balance project attractiveness to the private sector and fair protection of public interest. However, a practical and critical problem is how to properly design these provisions. Although previous studies have investigated the value of these provisions, a knowledge gap still exists with respect to methods of fairly and effectively designing such provisions. This study fills this gap by developing a methodology that analyzes the appropriateness of guarantee or warranty provisions for contracts. In this study, a contract reliability index is constructed, and a process of evaluating contract reliability is proposed. The New Mexico Highway 44 project, in which three warranty provision arrangements are investigated, is used as a case study to illustrate the analysis process. Results show that although a ceiling clause can effectively motivate the private sector to participate in the project, it sacrifices a significant amount of public benefits. By contrast, although a warranty option can protect public benefits, it cannot effectively incentivize the private sector. A combination of the ceiling clause and the warranty option will therefore result in improved contract provision design. The proposed methodology in this study is especially useful for governments in properly determining contract clauses in infrastructure development.     

Applying a risk assessment approach for cost analysis and decision-making: a case study for a basic design engineering project

Abstract

Many uncertainties and cost variations occur in the work activities of a project, thereby causing many possibilities of under-estimating or over-estimating for a bid price. A comprehensive study for each process of risk management should be investigated to achieve project objectives. However, a limited number of studies have a comprehensive viewpoint to indicate the benefits of risk management and the effect on project performance for the engineering design stage of engineering–procurement–construction (EPC) projects, especially in the basic design stage. This research was conducted to identify and analyze the risks associated with a Basic Design Engineering (BDE) project for a high value-added petrochemical plant in Taiwan. First, a project risk management work flow was proposed as an effective tool to minimize the project risks and maximize the management capacity of practitioners. Second, the cost effect of project risks was described by conducting a case study for the design process of a high value-added petrochemical plant using a Monte Carlo simulation. A risk register was identified to support the data required for conducting simulation analysis. The results of this paper provide reference points for risk management planning of project execution and help project managers evaluate particular risks at the engineering design stage of EPC projects to avoid cost overruns.     

PERTS: an environment for specification and verification of reactive systems

In this paper, we describe the design and implementation of an environment for specification, analysis and verification of reactive systems. The environment allows the user to develop specification in the graphical formalism of Statecharts and analyze them using a simulation tool. A built-in translator tool translates the specification into an Esterel program for the purpose of carrying out verification. Through such an approach, we have been able to integrate the powerful graphical formalism of Statecharts, which is very appealing to engineers, and the power of the formal verification environment of Esterel. Since we translate Statecharts, which can be non-deterministic, to Esterel programs, which are fully deterministic, the system overcomes the non-determinism in the specifications by enforcing priority. The behavior of Esterel programs generated by the translator follow Harel and Naamad's ‘step’ semantics. In the paper, we describe the main components of the PERTS environment and the principles underlying the translation and illustrate the use of the system for specification and verification using an example.     

Assessing validity of tolerance specification for monitored parameters in metrological review of engineering systems

Translated from Izmeritel'naya Tekhnika, No. 7, pp. 14–16, July, 1992.     

Driving simulators for robust comparisons: A case study evaluating road safety engineering treatments

Road authorities considering the implementation of speed management interventions should have access to the results of scientifically robust evaluations on which to base their decisions. However, studies that evaluate a diverse range of interventions with comparable metrics are rare, with most focussing on one type, for example, types of signage, perceptual countermeasures or physical traffic calming. This paper describes a driving simulator study designed to overcome these constraints. Twenty diverse speed-reducing treatments were developed and tested in urban and rural road environments. Forty participants encountered all the treatments allowing a comparison to be made with their driving behaviour when the treatment was not present. A number of speed parameters were developed to encapsulate the range of effects of the treatments. The results suggest that whilst straight sections of road are difficult to treat, speed reductions can be obtained by increasing risk perception. In contrast, alerting treatments had more effect at junctions, particularly in an urban environment; drivers approaching curves demonstrated improved speed adaptation if the curve radius was highlighted (either implicitly or explicitly). The study highlights how driving simulators can be used to overcome methodological constraints encountered in real-world evaluations of this type.     

A Method for Driving an Oscillator at a Quasi-Uniform Velocity

We describe a simple way to drive an actuator, comprising a superconducting coil moving in a static magnetic field, at a quasi-uniform velocity. The main objective is to avoid oscillations in this system with low damping, as they undermine the uniformity of the velocity. The method consists in calculating the force that should be exerted on the coil from the equation of motion and programming a waveform generator to produce the corresponding current through the coil. The method was tested on a device towing a grid through a closely fitted channel filled with superfluid ⁴He at temperatures below 100 mK. The motion of the grid over the distance of 4.3 cm at 10?cm/s resulted in oscillations of less than 50 μm in amplitude (or less than 1 mm/s in terms of velocity). The method can be applied to any oscillator.     

Stress intensity factor solution for a semi-elliptical crack in an arbitrarily distributed stress field

An equation for the stress intensity factor (SIF) for semi-elliptical crack has been developed. It is based on the Newman-Raju's solution for the crack in a plate under bending or tension. The equation can be applied when a stress distribution is described by a power function. Using the approach outlined, the SIF for a surface crack in a T-butt welded connection has been estimated. The results obtained can be used in a fracture-mechanics-based fatigue analysis.     

Developing an Environmentally Friendly Engineering Ethic: A Course for Undergraduate Engineering Students

An undergraduate course designed to develop a new, environmentally-friendly, engineering ethic is described. The various components of the course are: individual and societal values clarification, the current state of the environment, critical and creative thinking skills development and conflict resolution. For each component, the rationale is given along with activities and evaluation of the unit.