Joseph O. Ajaefobi

Modelling dynamic value streams in support of process design and evaluation

To remain competitive, most manufacturing enterprises (MEs) need cost-effective and responsive business processes with capability to realise multiple value streams specified by changes in customer needs. Models of MEs can play a critical role in enabling enhanced enterprise process and systems design and change based on analysis of their performance, and ongoing management and control of their operation. Typical models of MEs can provide reusable computational representations of organisational structures, processes, information, resources and related value flows in an enterprise. This paper presents a dynamic modelling approach to value stream mapping which enhances current best practice when reasoning about changing process and resource systems requirements. Here, coherent use of enterprise and simulation modelling techniques were deployed to develop value streams of a case study enterprise which is a make-to-order furniture manufacturing SME. The paper explains how models created during the modelling stages were validated and reused as a basis for informed SME decision making in relation to product realisation strategies and related organisation design and change decisions and actions.

On modelling reusable components of change-capable manufacturing systems

Abstract New modelling constructs are defined to enable human, machine, and IT resource systems to be described coherently and explicitly as ‘reusable’, ‘change-capable’ ‘components’ of manufacturing enterprises. These components are referred to as ‘dynamic producer units’ or DPUs. DPU characterization is designed to facilitate: graphical representation of resource systems; explicit specification of resource systems; and implementation description of resource systems that can be computer executed within simulation modelling environments. Also described is a methodological use of the DPU modelling constructs, which shows how they can complement the use of ISO enterprise modelling and proprietary (discrete event and continuous) simulation software. By so doing, the modelling of responsive production systems is enabled, where such systems comprise user defined configurations of process networks, resource systems, and time-dependent flows of units of work. This modelling method enables decomposition and semantically rich representation of complex systems composed from interoperating DPUs that can be computer exercised within specific organizational contexts. This paper introduces the DPU and illustrates its systematic application when designing responsive production systems.

Enriched multi-process modelling in support of the life cycle engineering of Business Processes

A new approach to enterprise modelling is described that facilitates the reuse of multi-perspective models of Business Process networks. The approach has been designed to advance current best practice when engineering change to interdependent Business Processes of types commonly deployed within Manufacturing Enterprises. The approach is unique in the way it maintains coherence between (1) conventional enterprise models, used primarily to represent graphically (at multiple levels of abstraction) relatively enduring properties of Business Process networks; and (2) dynamic models of selected segments of a parent Business Process network, which can be computer-executed via conventional simulation modelling and workflow modelling technology. Thereby, context-dependent dynamic models can be used to replicate and analyse historical patterns of enterprise behaviour, and predict and analyse possible future patterns of enterprise behaviour, should selected elements and parameters of the modelled Business Process network be changed. The paper also considers ‘needed decision support capabilities’ during Business Process Reengineering and Business Process improvement projects. In so doing, it collates those decision support requirements identified into a generalized description of the life phases of such projects. This generalized description was used to help structure the design of the new enterprise modelling approach. Furthermore, it is used to help illustrate an example application of the new modelling approach.

Process thinking in support of system specification and selection

Process thinking supported by enterprise modelling can naturally inform and help structure, the engineering of large scale systems, but this potential has only partially been realised. To facilitate an advance in the application of process thinking, common properties of processes used in Manufacturing Enterprises (MEs) are discussed. This process characterisation is analysed with a view to specifying generic requirements of human and technical systems, against which common properties exhibited by IT systems used in MEs can be contrasted and compared. The paper concludes by illustrating how the combined use of characteristic models of ME processes and proprietary IT systems could lead to improved IT system specification and selection.

Development of a Multi-Product Cost and Value Stream Modelling Methodology

In support of the life-cycle engineering of manufacturing enterprises (MEs), there is a need to provide reusable computational representations of organisational structures, processes, information, resources, and related cost and value flows. Current best process mapping techniques do not suitably capture key time-based attributes of ME systems, particularly with respect to the dynamics associated with multi-product work flows through shared resource systems. However, multiple work-flow dynamics will likely impact significantly on cost and value generation, and if this kind of dynamics cannot be effectively modelled, the use of process mapping will be limited as a basis for decision-making. Therefore, this paper presents an integrated multi-product dynamic cost and value stream modelling methodology with the embedded capability of capturing aspects of dynamics associated with multiple product realisations in MEs. The first part of the research presented in this paper shows the application of an enhanced and integrated use of process mapping and enterprise modelling techniques in a case study involving a POP manufacturing company in the UK. When compared with the use of current lean-based value-stream-mapping techniques, case study results obtained when using the first part of the modelling method have led to improved solutions to problems of: analysing and estimating cost and values; and improving the design and operation of multi-product realising systems.

Integrated approach to modelling human systems as reuseable components of manufacturing workplaces

A new approach to modelling human systems as reusable components of manufacturing workplaces is described. Graphical and computer executable models of people competences and behaviours are created which are qualitatively and quantitatively matched to equivalent models of process networks, decomposed into roles and dependencies between roles. To enable model creation and reuse, coherent sets of role, competence and dynamic producer unit (DPU) modelling concepts have been defined and instrumented using enterprise modelling (EM), simulation modelling (SM) and causal loop modelling (CLM) techniques. This paper reports on an application of the modelling approach to create related models of ‘process oriented roles’ and ‘candidate human systems’ so as to systemise matching of role requirements to resource systems attributes and to inform aspects of strategic and tactical decision making in an SME making composite bearings.

Modelling Human Systems in Support of Process Engineering

There is a general requirement to resource the business processes of manufacturing enterprises with suitably structured human and technical systems. Further custom and practice is based upon specifying, building, utilizing and developing multiple human and technical systems so that they must be capable of interoperating in a customized way in order to concurrently fulfill the goals of multiple business processes. Various Enterprise Modelling techniques have been developed in recent decades which offer support for enterprise design and thereby help specify system requirements and solutions. However those techniques are generally known to be deficient in the support they provide for human systems engineering. This paper proposes means of characterizing the competencies and capacities of human resources, with reference to strategic, tactical and operational aspects of business processes. Also it explains how these ‘models’ of human resource can be deployed within the wider context of Enterprise Modelling to match the abilities and behaviors of stereotypical human systems to specific business process requirements.

Predicting the performance of candidate human systems within specific work contexts

This paper describes concepts embedded into an ‘enhanced multi process modelling’ approach designed to capture and reuse coherent models of enterprise processes and human systems. Human systems are modelled in terms of the competencies and capacities they can bring as potential occupants of work roles. Multiple dependent enterprise processes (used by a specific ‘manufacturing enterprise’) are also modelled. The process modelling enables separable groupings of activities to be identified and designated as required work roles, to which competency and capacity requirements are associated. By coherently modelling role requirements and potential role occupants, and at needed abstraction levels, the enhanced multi-process modelling approach (i) supports human system selection (from among candidates), (ii) enables the development and testing of simulation models (that predict relative cost and lead-time performance of alternative role occupants) and (iii) enables the generation of workflow models (that support the runtime management and control of work through specified process and human resource system configurations). The current paper illustrates the use of the developed approach and observed benefits in respect to (i) and (ii). An example application of the approach is described that concerns the human resourcing of a machine design and build process currently used by a vendor of automotive production lines.

Human systems modelling in support of enterprise engineering

Organisations comprise human and technical systems that typically perform a variety of business, engineering and production roles. Of late, attention is being focused on modelling various aspects of people working within production systems. In the research reported graphical and computer executable models of people have been conceived and used in support of human systems engineering. The paper describes how the modelling approach can underpin the conceptual design and runtime simulation of alternative human system configurations. In this paper, the authors illustrate the application of the modelling approach and the advantages gained from the use of simulation technologies. [Received 10 September 2009; Revised 27 May 2010; Accepted 22 October 2010]

People at Work: Modelling Human Performance in Shop Floor for Process Improvement in Manufacturing Enterprises

Predicting actual human performance in manufacturing plants is difficult and not a straightforward task. This motivates further investigation of ways of modelling, measuring and predicting behaviours of people working in production systems. People can be modelled in terms of their competences in relation to the roles they play in realising enterprise activities. This research introduces a combined application of Enterprise Modelling (EM) and Simulation Modelling (SM) to investigate and understand how people systems can be matched to process-oriented roles in production situations. EM facilitates the development of static models of structural aspects of people system from both top-down and bottom-up points of view. It can also provide organisational models in terms of roles and role relationships. Developed versions of EMs can also explicitly define key attributes of current and possible future ‘work contexts in which productions systems’ are used. In this way any given EM can underpin the creation of multiple SMs that characterise important structural and dynamic aspects of production systems (in terms of human configuration, performance, flexibility, etc), and production throughput within specific contexts of use. The research methods are illustrated via the use of case studies in which roles that people play in the production systems of an international company were studied and modelled. The findings of related SM experiments have generated useful insights for industrialist and academics.