A generic visual language for diagram editing has been created which may be instantiated for a particular modelling technique. The instantiated visual language is used within the generated design tool. It provides non-obtrusive guidance observing the semantics of the underlying modelling technique. The tool user is allowed to produce intermediate inconsistent states to facilitate diagram editing. A prototype, comprising a compiler for the specification language, a multi-purpose graph tool and a configurable design tool was implemented to prove the feasibility of the complete approach. The prototype compiler generates executable code. The target of the compiler is the persistent programming language Napier88. The architecture of the compiler has been designed as two separate components: a front-end (the parser), and a back-end (the code generator). This approach gives independence from the target language. The code generator comprises a number of translation rules to produce Napier88 from a VC-t specification. The prototype compiler only incorporates some of the translation rules to demonstrate that executable Napier88 can be generated automatically. The remainder of the translation rules have been applied manually to produce Napier88, to demonstrate that the rules are correct. The multi-purpose graph tool, designated as GraphTool, can be used with the class of applications using graphs as their main data structures. It provides support for visual and interactive representations of an application. The application acts as a client of the Graph-Tool. A protocol has been defined to connect the client application to the GraphTool. Any number of visual representations can be associated with the application. Maps are used for this purpose: to change the representation it is only necessary to change the map. The GraphTool includes a constraint manager used to associate constraints with the representations objects and check these at run-time. The configurable design tool has been developed as a client for the GraphTool. It includes generic components for diagram editing and a drawing canvas. The functionality of the canvas is fully provided by the GraphTool.

This study examines the growth, need for and demands on university-industry collaborative (UIC) partnerships as a vehicle for the nation‟s development through technological innovation. In Malaysia, gaps and weaknesses exist when compared to best practices, these limit the establishment and overall effectiveness of UICs. In the Malaysian context, UICs are by no means a new phenomenon, however the approaches adopted, the success stories and related issues have not received significant academic attention. Thus, this study aims to provide an insight into collaborative endeavours in Malaysia. This study adopted an exploratory interpretative case study approach via semi-structured interviews and self-administered questionnaire survey to collect data from university researchers, industry players and research agencies. This data, along with the findings from an extensive literature review were used to benchmark best practices and define the requirements that are placed on a PMM designed specifically for use in the Malaysian UIC project environment. Based on this analysis, a novel and appropriate PMM was developed and subsequently evaluated by an expert panel and iteratively refined. The primary outcome of this study is a PMM guidebook for use in the initiation, planning, execution, monitoring and closing of UIC research projects. The PMM developed aims to make project management best practices accessible and appropriate for the needs of UIC researchers and also encourages academic researchers to embrace project management knowledge which in turn helps them to understand industrial needs and wants. The PMM developed is customisable for project size and nature. It consists of a set of processes, templates, tools and techniques to assist in the planning and management of the project throughout the entire life cycle. The components of the PMM are (1) project management processes such as initiating, planning, executing and monitoring project progress with (2) a selection of tools and techniques to communicate delivery to the satisfaction of all stakeholders; (3) consolidated and integrated set of appropriate best practices and values of project management and (4) a list of references of terminology as a common denominator and language for us in the project environment. NB Please note that the online version does not include volume 2 of the printed thesis:Project management methodology [PMM] guidebook.

In recent years that has been a worldwide increase in the utilisation of Autonomous Underwater Vehicles (AUVs) for many diverse subsea applications. This has given rise to an increase in the research and development of these vehicles, with a particular focus on extending operational capability and longevity. Consequently, this activity has resulted in the design of many different types of AUVs that employ a variety of different propulsion and manoeuvring mechanisms. One particular area that has yielded promising results involves the vehicles designs that are biologically inspired or biomimetic. This class of AUV replicates the anatomical features of aquatic species in order to exploit some of the benefits associated with this type of swimming e.g. higher efficiency at low speeds, improved manoeuvrability. The study presented in this thesis considers the design and performance analysis of a unique biomimetic AUV design based on the physiology of an adult Atlantic salmon. This vehicle, called RoboSalmon, is equipped with a multiple jointed, fully actuated tail that is used to replicate the undulatory swimming gait of a real fish. The initial stage of this design process involves the development of a mathematical model to describe the fusion of the dynamics and electro-mechanics of this vehicle. This model provides the design specifications for a prototype vehicle, which has been used in water tank trials to collect data. Forward swimming and manoeuvring experiments, e.g. cruise in turning and turning circle swimming patterns, have been conducted for performance analysis and validation purposes. This part of the study has illustrated the relationship between the vehicle surge velocity, tail amplitude and tail beat frequency. It was found that the maximum surge velocity has been measured at 0.143 ms-1. Also, the vehicle has been shown to accomplish turning circle manoeuvres with turning radius just over the half of its body length. The final stage of this study involved the design of a heading control system, which changes the course of the vehicle by altering the tail centreline. This study allowed the course changing performance of the vehicle to be analysed. Furthermore, a line of sight guidance system has been used to navigate the vehicle through a multiple waypoint course in order to show autonomous operation within a simulated environment. Moreover, the vehicle has demonstrated satisfactory performance in course changing and tracking operations. It is concluded that the RoboSalmon biomimetic AUV exhibits higher propulsive efficiency and manoeuvrability than propeller based underwater vehicles at low speeds. Thus the results of this study show that mimicking biology can improve the propulsive and manoeuvring efficiencies of AUVs.

The immense power of the sea presents many life-threatening dangers to humans, and many fall foul of its unforgiving nature. Since manned rescue operations at sea (and indeed other search and rescue operations) are also inherently dangerous for rescue workers, it is common to introduce a level of autonomy to such systems. This thesis investigates via simulations the application of various search algorithms to an autonomous air-sea rescue system, which consists of an unmanned surface vessel as the main hub, and four unmanned helicopter drones. The helicopters are deployed from the deck of the surface vessel and are instructed to search certain areas for survivors of a stricken ship. The main aim of this thesis is to investigate whether common search algorithms can be applied to the autonomous air-sea rescue system to carry out an efficient search for survivors, thus improving the present-day air-sea rescue operations. Firstly, the mathematical model of the helicopter is presented. The helicopter model consists of a set of differential equations representing the translational and rotational dynamics of the whole body, the flapping dynamics of the main rotor blades, the rotor speed dynamics, and rotational transformations from the Earth-fixed frame to the body frame. Next, the navigation and control systems are presented. The navigation system consists of a line-of-sight autopilot which points each vehicle in the direction of its desired waypoint. Collision avoidance is also discussed using the concept of a collision cone. Using the mathematical models, controllers are developed for the helicopters: Proportional-Integral-Derivative (PID) and Sliding Mode controllers are designed and compared. The coordination of the helicopters is carried out using common search algorithms, and the theory, application, and analysis of these algorithms is presented. The search algorithms used are the Random Search, Hill Climbing, Simulated Annealing, Ant Colony Optimisation, Genetic Algorithms, and Particle Swarm Optimisation. Some variations of these methods are also tested, as are some hybrid algorithms. As well as this, three standard search patterns commonly used in maritime search and rescue are tested: Parallel Sweep, Sector Search, and Expanding Square. The effect of adding to the objective function a probability distribution of target locations is also tested. This probability distribution is designed to indicate the likely locations of targets and thus guide the search more effectively. It is found that the probability distribution is generally very beneficial to the search, and gives the search the direction it needs to detect more targets. Another interesting result is that the local algorithms perform significantly better when given good starting points. Overall, the best approach is to search randomly at the start and then hone in on target areas using local algorithms. The best results are obtained when combining a Random Search with a Guided Simulated Annealing algorithm.

An injury to the cervical region of the spinal cord can cause paralysis affecting all four limbs, termed tetraplegia. People with tetraplegia also have paralysis or impaired function of the major respiratory muscles, namely the diaphragm and intercostal and abdominal muscles. This often reduces respiratory function, with associated respiratory complications a leading cause of morbidity and mortality for this population. Abdominal Functional Electrical Stimulation (AFES), the application of electrical pulses to the abdominal muscles causing them to contract, has been shown to improve respiratory function in tetraplegia. Despite these positive results, further work is needed to establish AFES as a standard clinical treatment. The aim of this thesis is to support the clinical introduction of AFES. This was achieved by addressing two primary objectives. Firstly, the development of new technologies and protocols to optimise AFES for use in a clinical setting. Secondly, the clinical evaluation of these technologies and protocols with tetraplegic patients. For research purposes, AFES has typically been applied manually, requiring an operator to synchronise stimulation with respiratory activity. One important step necessary for the clinical introduction of AFES is the development of an automated AFES device that can apply stimulation in synchrony with the users respiratory activity, with different stimulation parameters applied for different breath types such as a quiet breath and a cough. In this thesis, the signal from a non-intrusive respiratory effort belt, worn around the chest, was used to develop a statistical classifcation algorithm capable of classifying respiratory activity in real-time, and applying AFES in synchrony with the user's respiratory activity. The effectiveness of AFES can also be enhanced by stimulating at the abdominal muscle motor points. In this thesis the positions of the abdominal motor points were located systematically for the frst time, in ten able bodied and five tetraplegic participants. To aid the clinical introduction of AFES it is necessary to establish the patient groups who would benefit most from this intervention, and to develop appropriate clinical protocols. This is addressed in two clinical studies, where the feasibility and effectiveness of AFES to improve the respiratory function of the acute ventilator dependant and sub-acute tetraplegic populations was demonstrated. In the first study, conducted with 10 acute ventilator dependant tetraplegics, AFES was applied on alternate weeks for a total duration of eight weeks. This resulted in acute improvements in breathing and led to a longitudinal increase in respiratory function over the study duration. It was found that participants weaned from mechanical ventilation on average 11 days faster than matched historic controls. Previous work, which investigated the effect of a three week AFES training programme on the respiratory function of people with sub-acute tetraplegia, suggested that an extended AFES training programme may be more effective. In the second clinical study in this thesis, a continuous eight week AFES training protocol (combined with a six week control period) was evaluated with three sub-acute tetraplegic participants. The application of AFES led to an acute increase in respiratory function, with a longitudinal improvement in respiratory function observed throughout the study. In a single participant case study, the feasibility of combining AFES with assisted coughing delivered by mechanical insufflation-exsufflation was demonstrated for the first time. This was shown to lead to an acute improvement in respiratory function at six of the eight assessment sessions, indicating that this technique could be used to aid secretion removal. This thesis highlights the feasibility and effectiveness of AFES to improve the respiratory function of the acute ventilator dependant and sub-acute tetraplegic populations. The clinical protocols that enable AFES to be used with these patient groups, and the technological developments detailed throughout this thesis, are an important step towards the introduction of AFES as a regular treatment modality.

Ranked the third biggest cyber security threats of 2013 by Forbes, Internal Identity Theft-Related Crimes (IIDTRC) leave countless victims in their wake, including online retail companies and consumers. With the rapid growth in the use of credit and debit cards in e-commerce, the online retail has been a key target for the IIDTRC perpetrators. IIDTRC involve the misuse of information systems (IS) by the dishonest employees to steal victims’ personal identifiable data. The crimes pose significant socio-economic impact and data security risks. In the context of online retail, relatively little research has been done to prevent IIDTRC. A few studies focus on situational-based IIDTRC prevention approach built on an independent use of software security. Others develop IIDTRC prevention frameworks in the context of generic e-businesses. The majority of the frameworks have little or no grounded empirical research. This research entitled the ‘The Prevention of Internal Identity Theft-Related Crimes: A Case Study Research of the UK Online Retail Companies’, attempts to bridge this research gap. It provides answers to two questions – what is the nature of IIDTRC in online retail companies and what framework can be used for IIDTRC prevention. This research set out three aims to answer the two questions. First, it provides understanding of causes, methods of carrying out and prevention of IIDTRC. Second, it extends a role-based framework (RBF) for the prevention of IIDTRC. Third, it evaluates the extent the RBF can be applied in the prevention of IIDTRC in online retail companies. A qualitative case study was used to achieve these aims. The empirical data were collected in the northwest of UK from 2011 to 2013. The field study was carried through archival analysis, semi-structured interview and participant observation. Organisational role theory (ORT) was used to guide the concept of a role-based framework (RBF) – a collaborative approach where the key components of management work in unison is required to prevent IIDTRC. The attributes of RBF were synthesised from the recommended IIDTRC prevention practices. The empirical evidence suggests that IIDTRC perpetrators in online retail companies are likely to be the top management and call centre employees. The findings suggest that online retail consumers’ credits/debits cards details are as much vulnerable to IIDTRC as the companies’ identities such as trade secrets and trademarks. Furthermore, the common methods used by the IIDTRC perpetrators include collaboration, collusion, infiltration and social engineering. Some of the IIDTRC prevention practices, of which the majority is software security, are implemented without considering the contribution of human-centred security based on management roles. In examining the contribution of the management roles in implementing Information Systems security practices, major challenges that are faced by online retail companies were identified. They include lack of resources, lack of management support and lack of IIDTRC prevention awareness training. This research concludes that an application of RBF can reduce the impact of the identified challenges. This was suggested by applying RBF in conducting IS security auditing in three online retail companies. The finding from the selected companies suggests that the RBF approach can maximise management performance in providing effective IIDTRC prevention practices. It provides better returns on cost, quality and time in the IS security auditing. It has an impact on management attitudes on preventing IIDTRC by clarifying and aligning their roles in implementing effective IS security auditing. There is heterogeneity of this effect across the companies suggesting that some are utilising the RBF approach while others are not. The finding confirms the plausibility of the RBF attributes. It suggests that the human-centred security play an integral role for effective internal data security in preventing IIDTRC. It suggests that it pays to use the collaborative management roles approach for implementing IIDTRC prevention practices. Furthermore, the use of the RBF approach can improve the effectiveness of the online retail companies in preventing IIDTRC. The findings suggest that benefits may accrue from the RBF approach when supplemented with a collaborative IS auditing. The benefits depend on the level of management IT skills, their perception of their roles, top management support and the organisational operations. This research contributes to the literature in identity theft prevention in online retail. To IS security practitioners, it identifies the data security challenges and IIDTRC prevention practices. To theory, it extends a role-based framework for IIDTRC prevention. To the emerging research in the digital economy, it puts forward as a robust starting point for further related works in cyber security, cybercrimes prevention and criminology.

The use of an electronic olfactory device, termed an electronic 'nose', was investigated for the detection of unique human odour characteristics. The detection of these unique odours was applied to the field of biometrics for access control, where a human's unique characteristics were used to authenticate a user of an access control system. An electronic odour sensing device was designed and constructed using an array of conducting polymer gas sensors in order to facilitate the regular screening of a group of human subjects over a period of six weeks. A static sampling method was used to measure odour levels from human hands, which were found to contain a reliable source of human odour. Human odour levels were low so dynamic sampling proved to be unsuitable for this application due to the dilution of the odour mixture. Feature analysis results revealed that the features of adsorption and desorption gradient contained discriminatory information in addition to the commonly used maximum divergence. Pattern recognition revealed that neural network architectures produced superior results when compared to statistical methods as a result of their ability to model the non-linearities in the data set. The highest recognition rate was 73% which was produced using a Multi-Layer Perceptron (MLP) neural network compared to 63% obtained using the best statistical method of Parzen windows. The majority of the recognition error was caused by a minority of the humans. Analysis of sensor data revealed that only 30% of the sensor array were contributing discriminatory information so it was deduced that performance would undoubtedly improve if a full array of effective sensors were available. Exploratory data analysis revealed that human odour changed from day to day and often an increasing divergence with time was observed. A time-adaptive method was devised which increased the recognition to 89%, but was still too low for use as a biometric recognition device. However, use as a verification device demonstrated acceptable levels of performance but resulted in high levels of user frustration caused by a high proportion of users being falsely rejected. This work demonstrated that an olfactory based biometric access control system could be a realistic proposition but requires further work, especially in the areas of sensor development and unique human odour research, before an operational system could be produced.

This research contributes to current academic thinking by highlighting new perspective to studying the IS Project Escalation phenomenon through the application of Agency Theory. This theory views the customer as the (principal) who needs an IS product, and the IS developer as the (agent) who creates this IS product. According to this viewpoint, examining current IS project escalation literature suggests the majority of previous studies implicitly adopted the assumption that the customer (principal) is entirely capable of identifying the requirements of the proposed IS product, and a project is prone to escalate because of the attitude of the IS developer (agent). This presents a gap in the literature in that the impact of the customer (principal) not been explicitly explored. As such, one critical aim of this research is to investigate IS project escalation by employing an extension of Agency Theory. This extended theory assumes that the customer (principal) suffers challenges of incompetence when it comes to the transfer of knowledge (i.e. requirements) to the IS developer (agent). This leads to a situation of information asymmetry on the principal’s side because of incomplete knowledge transfer. In turn, this situation develops and leads to IS project escalation. Another aim of this research is to investigate the process of requirement elicitation (RE) in IS development practice. This is to identify the role of the incorporated knowledge artefacts within this activity, in terms of how the project manager and developers effectively create and utilise these objects. Thus, this is in order to provide a possible solution with respect to the challenge of incomplete knowledge transfer. To achieve that, this research employed a qualitative methodology and collected data in two stages in Saudi Arabia by using semi-structured interviews. In this respect, in the first stage, a number interviews with 30 IS project manager form five different IS development organisations is conducted. In the second stage, a number of interviews with 10 customers form different organisations is conducted. The findings in general acknowledged and complemented a number of previous studies’ results through the employed perspective of the extended Agency Theory in this research. Considering the identified gap, the empirical evidence supported the assumption of this research, and provided a new explanation for IS project escalation which highlighted the role of the customer (principal) this time. In addition, an influence diagram (i.e. Project Escalation Framework), which clarifies the relationship between the reasons behind incomplete knowledge transfer and IS project escalation, is developed. Also, the empirical evidence identifies a number of incorporated and relevant knowledge artefacts throughout the process of requirement elicitation (RE), namely Initial Request, Features, Process Diagrams, Prototypes, and Requirements. In this respect, the discussion categorised the different roles these artefacts can act out, in terms of being boundary object, epistemic objects, and activity objects. Additionally, a process diagram (i.e. Knowledge Transfer Framework), which clarifies the knowledge process in five main steps during RE phase, is developed. Analysing a number of IS development cases in a various contexts demonstrated multiple practical applications of the Project Escalation Framework with respect to managing issues building up to and leading to several project outcomes (i.e. success, failure, and escalation). Additionally, this analysis presented the artefacts in the Knowledge Transfer Framework as critical linchpins of an otherwise fragmented process when it comes to eliciting customer requirements. These artefacts have much broader implications that go beyond acting as just a procedure to elicit customer requirements. The ‘inclusion’ or ‘omission’ of these artefacts contributes to project success or failure respectively. Consequently, this understanding will result in improvement of IS development investigations, rather than exclusively enhance RE processes between principals and agents. Furthermore, the findings provided a number of highlighted things to be aware of and useful hints which reflect professional experience from real life applications. Thus, considering learning from such rich experience in terms of employing the advantages and avoiding the drawbacks would positively reflect on IS development practice. This includes managing and dealing with challenges of IS development projects, particularly project escalation, in addition to improving RE process and enhancing the process of receiving customer requirements and ideas.

Among the several numerical methods which are available for solving complex problems in many areas of engineering and science such as structural analysis, fluid flow and bio-mechanics, the Finite Element Method (FEM) is the most prominent. In the context of these methods, high quality meshes can be crucial to obtaining accurate results. Finite Element meshes are composed of elements and the quality of an element can be described as a numerical measure which estimates the effect that the size/shape of an element will have on the accuracy of an analysis. In this thesis, the strong link between mesh geometry and the accuracy and efficiency of a simulation is explored and it is shown that poor quality elements cause both interpolation errors and poor conditioning of the global stiffness matrix. Numerical optimisation is the process of maximising or minimising an objective func- tion, subject to constraints on the solution. When this is applied to a finite element mesh it is referred to as mesh optimisation, where the quality of the mesh is the objec- tive function and the constraints include, for example, the domain geometry, maximum element size, etc. A mesh optimisation strategy is developed with a particular focus on optimising the quality of the worst elements in a mesh. Using both two and three dimensional examples, the most efficient and effective combination of element quality measure and objective function is found. Many of the problems under consideration are characterised by very complex geometries. The nodes lying on the surfaces of such meshes are typically treated as unmovable by most mesh optimisation software. Techniques exist for moving such nodes as part of the mesh optimisation process, however, the resulting mesh geometry and area/volume is often not conserved. This means that the optimised mesh is no longer an accurate discretisation of the original domain. Therefore, a method is developed and demonstrated which optimises the positions of surface nodes while respecting the geometry and area/volume of a domain. At the heart of many of the problems being considered is the Arbitrary Lagrangian Eulerian (ALE) formulation where the need to ensure mesh quality in an evolving mesh is very important. In such a formulation, a method of determining the updated nodal positions is required. Such a method is developed using mesh optimisation techniques as part of the FE solution process and this is demonstrated using a two-dimensional, axisymmetric simulation of a micro-fluid droplet subject to external excitation. While better quality meshes were observed using this method, the time step collapsed resulting in simulations requiring significantly more time to complete. The extension of this method to incorporate adaptive re-meshing is also discussed.

In this thesis the theory of both linear differential equations with periodic coefficients and linear differential equations with random coefficients is applied to investigate the stability and accuracy of parameter adaptation of sinusoidal perturbation and model reference adaptive control systems. Throughout dimensional analysis applied so that all the results are presented in a non-dimensional form. The first part of the thesis t s devoted to investigating the stability of such differential equations. In chapter 1 a system of linear homogeneous differential equations with periodic coefficients is considered and a numerical procedure, based on Floquet theory and well suited for use on a digital computer, is presented for obtaining necessary and sufficient conditions for asymptotic stability of the null solution. Also considered in this chapter is the so called infinite determinant method of obtaining the stability boundaries for a restricted class of linear differential equations with periodic coefficients. Chapter 2 is devoted to reviewing the current state of the stability theory of linear differential equations with random coefficients. In chapter 3 a theoretical analysis of the stability and accuracy of parameter adaptation of a single input, sinusoidal perturbation, extremum control system with output lag is considered. Using the principle of harmonic balance it is shown that various stable harmonic and sub-harmonic steady state solutions are possible in certain regions of the parameter space. By examining the domains of attraction, corresponding to the stable solutions, regions in three dimensional space are obtained within .which initial conditions will lead to a given steady state stable oscillation. It is also shown that the subharmonic steady state solutions do not correspond to the optimum solution, so that, for certain initial conditions and parameter values, it is possible for the system to reach a steady state solution which is not the optimum solution. All the theoretical results are verified by direct analogue computer simulation of the system. The remainder of the thesis is devoted to investigating the stability and accuracy of parameter adapt.at ion of model reference adaptive control systems. In order to develop a mathematical analysis, and to illustrate the difficulties involved, a stability analysis of a first order M.I.T. type system with controllable gain, when the input varies with time in both a periodic and random manner, is first carried out. Also considered are the effects of (a) random disturbances at the system output (b) and (b) periodic and random variations, with time, of the controlled process environmental parameters, on the stability of the system and the accuracy of its parameter adaptation. When the input varies sinusoidally with time stability boundaries are obtained using both a numerical implementation of Floquet theory and the infinite determinant method; the relative merits of the two methods is discussed. The theoretical results are compared with stability boundaries obtained by analogue computer simulation of the system. It is shown that the stability boundaries are complex in nature and that some knowledge of such boundaries is desirable before embarking on an analogue computer investigation of the system. When the input varies randomly with time the stability problem reduces to one of investigating the stability of a system of linear differential equations with random coefficients. Both the theory of Markov processes, involving use of the Fokker-Planck equation, and the second method of Liapunov are used to investigate the problem; limitations and difficulty of applications of the theory is discussed. The theoretical results obtained are compared with those obtained by digital simulation of the system. If the controlled process environmental parameter is allowed to become time varying then it is shown that this effects both the stability of the system and the accuracy of its parameter adaptation. Theoretical results are obtained for the cases of the parameter varying both sinusoidally and randomly with time; some of the results are compared with those obtained by digital simulation of the system. It is also shown that noise disturbance at the system output has no effect on the system stability but does effect the accuracy of the parameter adaptation. The doubts concerning the stability and the difficulty of analysis of the M.I.T. , type system have led.:researchers to think about redesigning the model reference system from the point of view of stability. In particular we have the Liapunov synthesis method where the resulting system is guaranteed stable for all possible inputs. However, in designing such systems the controlled process environmental parameters are assumed constant and, by considering the Liapunov redesign scheme of the first order M.I.T. system previously discussed, it will be shown that the effect of making such parameters time varying is to introduce a stability problem. In chapter 6 the methods developed for analysing the first order system are extended to examine the stability of a higher order M.I.T. type system. The system considered has a third order process and a second order model and a stability analysis is presented for both sinusoidal and random input. Steady state values of the adapting parameters are first obtained and the linearized variational equations , for small disturbances about such steady states, examined to answer the stability problem. Theoretical results are compared with those obtained by direct analogue computer simulation of the system. The effect, on the mathematical analysis , of replacing the system multipliers by diode switching units is also considered in this chapter. The chapter concludes by presenting a method of obtaining a Liapunov redesign scheme for the system under discussion.