No / Coalescence enhancement of water droplets in oil emulsions is commonly contemplated for the separation of an aqueous phase dispersed in a dielectric oil phase with a considerably lower dielectric constant than that of the dispersed phase. The characteristics and geometry of the electrode system have a large impact on the performance of an electrostatic coalescer and are actually strictly linked to the type of the applied electric field and the emulsion used. Furthermore, addition of chemicals and heating has also been revealed to further enhance the electrocoalescence of water droplets. In this work, the coalescence of two water drops sinking in a dielectric oil phase at an applied high voltage, pulsed dc electric field, in particular with regards to the effects of pressure and temperature on coalescence performance is investigated. The developed model should help to recognise and prove approaches to electrocoalescence mechanisms, the dispersion flow direction with respect to the applied electric field, as well as the electric field configuration.

Process modelling is a design approach where a system or procedure is decomposed in a number of abstract, independent, but connected processes, and then recomposed into a well-defined workflow specification. Research in formal verification, for its part, and theorem proving in particular, is focused on the rigorous verification of system properties using logical proof. This thesis introduces a systematic methodology for process modelling and composition based on formal verification. Our aim is to augment the numerous benefits of a workflow based specification, such as modularity, separation of concerns, interoperability between heterogeneous (including human-based) components, and optimisation, with the high level of trust provided by formally verified properties, such as type correctness, systematic resource accounting (including exception handling), and deadlock-freedom. More specifically, we focus on bridging the gap between the deeply theoretical proofs-as-processes paradigm and the highly pragmatic tasks of process specification and composition. To accomplish this, we embed the proofs-as-processes paradigm within the modern proof assistant HOL Light. This allows the formal, mechanical translation of Classical Linear Logic (CLL) proofs to p-calculus processes. Our methodology then relies on the specification of abstract processes in CLL terms and their composition using CLL inference. A fully diagrammatic interface is used to guide our developed set of high level, semi-automated reasoning tools, and to perform intuitive composition actions including sequential, parallel, and conditional composition. The end result is a p-calculus specification of the constructed workflow, with guarantees of correctness for the aforementioned properties. We can then apply a visual, step-by-step simulation of this workflow or perform an automated workflow deployment as executable code in the programming language Scala. We apply our methodology to a use-case of a holiday booking web agent and to the modelling of real-world collaboration patterns in healthcare, thus demonstrating the capabilities of our framework and its potential use in a variety of scenarios.

The educational benefits of involving learners as active players in the learner modelling process have been an important motivation for research on this form of learner modelling, henceforth referred to as participative learner modelling. Such benefits, conceived as the promotion of learners' reflection on and awareness of their own knowledge, have in most cases been asserted on the grounds of system design and supported only by anecdotal evidence. This dissertation explores the issue of whether participative learner modelling actually promotes learners' reflection and awareness. It does so by firstly interpreting 'reflection' and 'awareness' in light of "classical" theories of human cognitive architecture, skill acquisition and meta-cognition, in order to infer changes in learner abilities (and therefore behaviour) amenable to empirical corroboration. The occurrence of such changes is then tested for an implementation of a paradigmatic form of participative learner modelling: allowing learners to inspect and modify their learner models. The domain of application centres on the sensorimotor skill of controlling a pole on a cart and represents a novel type of domain for participative learner modelling. Special attention is paid to evaluating the method developed for constructing learner models and the form of presenting them to learners: the former is based on a method known as behavioural cloning for acquiring expert knowledge by means of machine learning; the latter deals with the modularity of the learner models and the modality and interactivity of their presentation. The outcome of this research suggests that participative learner modelling may increase the abilities of learners to report accurately their problem-solving knowledge and to carry out novel tasks in the same domain—the sort of behavioural changes expected from increased learners' awareness and reflection. More importantly perhaps, the research suggests a viable methodology for examining the educational benefits of participative learner modelling. It also exemplifies the difficulties that such endeavours will face.

Co-rotating twin-screw extruders are unique and versatile machines that are used widely in the plastics and food processing industries. Due to the large number of operating variables and design parameters available for manipulation and the complex interactions between them, it cannot be claimed that these extruders are currently being optimally utilised. The most significant improvement to the field of twin-screw extrusion would be through the provision of a generally applicable dynamic process model that is both computationally inexpensive and accurate. This would enable product design, process optimisation and process controller design to be performed cheaply and more thoroughly on a computer than can currently be achieved through experimental trials. This thesis is divided into three parts: dynamic modelling, measurement and control. The first part outlines the development of a dynamic model of the extrusion process which satisfies the above mentioned criteria. The dynamic model predicts quasi-3D spatial profiles of the degree of fill, pressure, temperature, specific mechanical energy input and concentrations of inert and reacting species in the extruder. The individual material transport models which constitute the dynamic model are examined closely for their accuracy and computational efficiency by comparing candidate models amongst themselves and against full 3D finite volume flow models. Several new modelling approaches are proposed in the course of this investigation. The dynamic model achieves a high degree of simplicity and flexibility by assuming a slight compressibility in the process material, allowing the pressure to be calculated directly from the degree of over-fill in each model element using an equation of state. Comparison of the model predictions with dynamic temperature, pressure and residence time distribution data from an extrusion cooking process indicates a good predictive capability. The model can perform dynamic step-change calculations for typical screw configurations in approximately 30 seconds on a 600 MHz Pentium 3 personal computer. The second part of this thesis relates to the measurement of product quality attributes of extruded materials. A digital image processing technique for measuring the bubble size distribution in extruded foams from cross sectional images is presented. It is recognised that this is an important product quality attribute, though difficult to measure accurately with existing techniques. The present technique is demonstrated on several different products. A simulation study of the formation mechanism of polymer foams is also performed. The measurement of product quality attributes such as bulk density and hardness in a manner suitable for automatic control is also addressed. This is achieved through the development of an acoustic sensor for inferring product attributes using the sounds emanating from the product as it leaves the extruder. This method is found to have good prediction ability on unseen data. The third and final part of this thesis relates to the automatic control of product quality attributes using multivariable model predictive controllers based on both direct and indirect control strategies. In the given case study, indirect control strategies, which seek to regulate the product quality attributes through the control of secondary process indicators such as temperature and pressure, are found to cause greater deviations in product quality than taking no corrective control action at all. Conversely, direct control strategies are shown to give tight control over the product quality attributes, provided that appropriate product quality sensors or inferential estimation techniques are available.

Co-rotating twin-screw extruders are unique and versatile machines that are used widely in the plastics and food processing industries. Due to the large number of operating variables and design parameters available for manipulation and the complex interactions between them, it cannot be claimed that these extruders are currently being optimally utilised. The most significant improvement to the field of twin-screw extrusion would be through the provision of a generally applicable dynamic process model that is both computationally inexpensive and accurate. This would enable product design, process optimisation and process controller design to be performed cheaply and more thoroughly on a computer than can currently be achieved through experimental trials. This thesis is divided into three parts: dynamic modelling, measurement and control. The first part outlines the development of a dynamic model of the extrusion process which satisfies the above mentioned criteria. The dynamic model predicts quasi-3D spatial profiles of the degree of fill, pressure, temperature, specific mechanical energy input and concentrations of inert and reacting species in the extruder. The individual material transport models which constitute the dynamic model are examined closely for their accuracy and computational efficiency by comparing candidate models amongst themselves and against full 3D finite volume flow models. Several new modelling approaches are proposed in the course of this investigation. The dynamic model achieves a high degree of simplicity and flexibility by assuming a slight compressibility in the process material, allowing the pressure to be calculated directly from the degree of over-fill in each model element using an equation of state. Comparison of the model predictions with dynamic temperature, pressure and residence time distribution data from an extrusion cooking process indicates a good predictive capability. The model can perform dynamic step-change calculations for typical screw configurations in approximately 30 seconds on a 600 MHz Pentium 3 personal computer. The second part of this thesis relates to the measurement of product quality attributes of extruded materials. A digital image processing technique for measuring the bubble size distribution in extruded foams from cross sectional images is presented. It is recognised that this is an important product quality attribute, though difficult to measure accurately with existing techniques. The present technique is demonstrated on several different products. A simulation study of the formation mechanism of polymer foams is also performed. The measurement of product quality attributes such as bulk density and hardness in a manner suitable for automatic control is also addressed. This is achieved through the development of an acoustic sensor for inferring product attributes using the sounds emanating from the product as it leaves the extruder. This method is found to have good prediction ability on unseen data. The third and final part of this thesis relates to the automatic control of product quality attributes using multivariable model predictive controllers based on both direct and indirect control strategies. In the given case study, indirect control strategies, which seek to regulate the product quality attributes through the control of secondary process indicators such as temperature and pressure, are found to cause greater deviations in product quality than taking no corrective control action at all. Conversely, direct control strategies are shown to give tight control over the product quality attributes, provided that appropriate product quality sensors or inferential estimation techniques are available.

This thesis investigates the proposition that use must be made of quantitative information to control the reporting of hazard scenarios in automatically generated HAZOP reports. HAZOP is a successful and widely accepted technique for identification of process hazards. However, it requires an expensive commitment of time and personnel near the end of a project. Use of a HAZOP emulation tool before conventional HAZOP could speed up the examination of routine hazards, or identify deficiencies I in the design of a plant. Qualitative models of process equipment can efficiently model fault propagation in chemical plants. However, purely qualitative models lack the representational power to model many constraints in real plants, resulting in indiscriminate reporting of failure scenarios. In the AutoHAZID computer program, qualitative reasoning is used to emulate HAZOP. Signed-directed graph (SDG) models of equipment are used to build a graph model of the plant. This graph is searched to find links between faults and consequences, which are reported as hazardous scenarios associated with process variable deviations. However, factors not represented in the SDG, such as the fluids in the plant, often affect the feasibility of scenarios. Support for the qualitative model system, in the form of quantitative judgements to assess the feasibility of certain hazards, was investigated and is reported here. This thesis also describes the novel "Fluid Modelling System" (FMS) which now provides this quantitative support mechanism in AutoHAZID. The FMS allows the attachment of conditions to SDG arcs. Fault paths are validated by testing the conditions along their arcs. Infeasible scenarios are removed. In the FMS, numerical limits on process variable deviations have been used to assess the sufficiency of a given fault to cause any linked consequence. In a number of case studies, use of the FMS in AutoHAZID has improved the focus of the automatically generated HAZOP results. This thesis describes qualitative model-based methods for identifying process hazards by computer, in particular AutoHAZID. It identifies a range of problems where the purely qualitative approach is inadequate and demonstrates how such problems can be tackled by selective use of quantitative information about the plant or the fluids in it. The conclusion is that quantitative knowledge is' required to support the qualitative reasoning in hazard identification by computer.

The goal of this paper is to describe process management and a possibility of its implementation in the real medical organization. The first part is devoted to a description of the basic concepts, principles, definitions and procedures of process management, which form the paradigm. The second part deals with the application of process management in the real dental clinic and presents an analysis of the current state and its improvement recommendations, conceptual and process modeling, description of basic levels of medical information systems and recommends criteria for information system selection. Diagrams are created in programs PowerDesigner and Cacoo.com are also included in this paper.

Theses is devided into two parts, the first one is dealing with theory the other one with practical exercise. There is basic terminology set in the first part, focusing mainly on process management and methodologies leading the current evolution in that respect, Lean and Six Sigma. I also refer about tools for mapping the processes and devote a section to theory of queues which is a main subject for modelling in the practical part. I have not omitted to mention axioms for modeling itself. Practical part comes from job experience I had. Main goal is to set up a model simulation based on the main features of the process structure, involve main principles of mentioned methodologies and to discuss the results simulation brings.

This paper introduces the Mobile Process Landscaping (MPL) method for modelling, analysing and improving mobile business processes. Current approaches for process modelling and analysis do not explicitly allow the consideration of typical mobility issues, e.g. location-dependent activities, mobile networks as resources and specifics of mobile information systems. Thus, our method focuses on the modelling and analysis of these characteristics, and is furthermore based on the process landscaping approach, supporting the easy creation of hierarchical models of distributed processes. The method comes with a specialized modelling notation and guidelines for the creation of process landscapes, context models, and business object models. Furthermore, it provides a catalogue of formally defined evaluation objectives, targeting at typical mobility issues. Each evaluation objective can automatically be tested on the created process landscape. Furthermore, the method includes a best practices catalogue with patterns for process and application improvements for typical mobility situations. A validation of the method is presented showing results from the method’s use in a real-world project.

Process patterns allow the modular modelling and adaptable application of software processes. Present descriptions of process patterns show defects like non-uniform and unequivocal description forms and missing relationship definitions. These defects disadvantageously affect the effective usage of process patterns. In this work we present the language PROPEL (Process Pattern Description Language), which provides concepts for the semiformal description of process patterns and relationships between process patterns. With the help of PROPEL single process patterns can be modelled and, by definition of relationships, be composed to more complex processes. With the representation of different views of a process pattern catalog the process patterns and their relationships can be shown clearly. An example illustrates how a process pattern catalog and the contained process patterns are modelled. It is shown that in applying PROPEL the complexity of a process model can be reduced, the inconsistencies of processes can be eliminated and the flexibility of processes can be improved.