An investigation into the use of knowledge representation in computer-integrated manufacturing

In a certain automobile factory, batch-painting of the body types in colours is controlled by an allocation system. This tries to balance production with orders, whilst making optimally-sized batches of colours. Sequences of cars entering painting cannot be optimised for easy selection of colour and batch size. `Over-production' is not allowed, in order to reduce buffer stocks of unsold vehicles. Paint quality is degraded by random effects. This thesis describes a toolkit which supports IKBS in an object-centred formalism. The intended domain of use for the toolkit is flexible manufacturing. A sizeable application program was developed, using the toolkit, to test the validity of the IKBS approach in solving the real manufacturing problem above, for which an existing conventional program was already being used. A detailed statistical analysis of the operating circumstances of the program was made to evaluate the likely need for the more flexible type of program for which the toolkit was intended. The IKBS program captures the many disparate and conflicting constraints in the scheduling knowledge and emulates the behaviour of the program installed in the factory. In the factory system, many possible, newly-discovered, heuristics would be awkward to represent and it would be impossible to make many new extensions. The representation scheme is capable of admitting changes to the knowledge, relying on the inherent encapsulating properties of object-centres programming to protect and isolate data. The object-centred scheme is supported by an enhancement of the `C' programming language and runs under BSD 4.2 UNIX. The structuring technique, using objects, provides a mechanism for separating control of expression of rule-based knowledge from the knowledge itself and allowing explicit `contexts', within which appropriate expression of knowledge can be done. Facilities are provided for acquisition of knowledge in a consistent manner.

Development of techniques to predict production line efficiency

This industrial based research project was undertaken for British Leyland and arose as a result of poor system efficiency on the Maxi and Marina vehicle body build lines. The major factors in the deterioration of system efficiency were identified as: a) The introduction of a 'Gateline' system of vehicle body build. b) The degeneration of a newly introduced measured daywork payment scheme. By relating the conclusions of past work on payment systems to the situation at Cowley, it was concluded that a combination of poor industrial relations and a lack of managerial control had caused the measured daywork scheme to degenerate into a straightforward payment for time at work. This ellminated the monetary incentive to achieve schedule with the consequence that both inefficiency and operating costs increased. To analyse further the cause of inefficiency, a study of Marina gateline stoppage logs was carried out. This revealed that poor system efficiency on the gateline was caused more by the nature of its design than poor reliability on individual items of' plant. The consideration given to system efficiency at the design stage was found to be negligible, the main obstacles being: a) A lack of understanding pertaining to the influence of certain design factors on the efficiency of a production line. b) The absence of data and techniques to predict system efficiency at the design stage. To remedy this situation, a computer simulation study of' the design factors was carried out from which relationships with system efficiency were established and empirical efficiency equations developed. Sets of tables were compiled from the equations and efficiency data relevant to vehicle body building established from the gateline stoppage logs. Computer simulation, the equations and the tables,when used in conjunction. with good efficiency data, are shown to be accurate methods of predicting production line system.efficiency.

Global and physical self-esteem and body dissatisfaction as mediators of the relationship between weight status and being a victim of bullying

Research has found evidence of a link between being overweight or obese and bullying/peer victimisation, and also between obesity and adjustment problems such as low self-esteem and body dissatisfaction. Studies have also found that adjustment problems can put children at an increased risk of being bullied over time. However, to date the factors that place overweight or obese children at risk of being bullied have been poorly elucidated. Self-report data were collected from a sample of 11-14 year olds (N=376) about their weight status, about their experiences of three different types of bullying (Verbal, Physical and Social), their global self-worth, self-esteem for physical appearance, and body dissatisfaction. Overweight or obese children reported experiencing significantly more verbal and physical (but not social) bullying than their non-overweight peers. Global self-worth, self-esteem for physical appearance and body dissatisfaction each fully mediated the paths between weight status and being a victim of bullying.

A road safety performance indicator for vehicle fleet compatibility

This paper discusses the development and the application of a safety performance indicator which measures the intrinsic safety of a country's vehicle fleet related to fleet composition. The indicator takes into account both the ‘relative severity’ of individual collisions between different vehicle types, and the share of those vehicle types within a country's fleet. The relative severity is a measure for the personal damage that can be expected from a collision between two vehicles of any type, relative to that of a collision between passenger cars. It is shown how this number can be calculated using vehicle mass only. A sensitivity analysis is performed to study the dependence of the indicator on parameter values and basic assumptions made. The indicator is easy to apply and satisfies the requirements for appropriate safety performance indicators. It was developed in such a way that it specifically scores the intrinsic safety of a fleet due to its composition, without being influenced by other factors, like helmet wearing. For the sake of simplicity, and since the required data is available throughout Europe, the indicator was applied to the relative share of three of the main vehicle types: passenger cars, heavy goods vehicles and motorcycles. Using the vehicle fleet data from 13 EU Member States and Norway, the indicator was used to rank the countries’ safety performance. The UK was found to perform best in terms of its fleet composition (value is 1.07), while Greece has the worst performance with the highest indicator value (1.41).

Impact of driver behaviour on availability of electric vehicle stored energy for STOR

As take up of low carbon vehicles increase, there is interest in using the energy stored in the vehicles to help maintain system frequency through ancillary services on the electricity grid system. Research into this area is generally classed as vehicle-to-grid research. In theory, the energy available from electric vehicles could be directly correlated to the vehicle's state of charge (SoC) and battery capacity during the time the car is parked and plugged in. However, not all the energy in the vehicle may be used, as some capacity is required by the driver for their next journey. As such, this paper uses data captured as part of a large scale electric vehicle trial to investigate the effect of three different types of driver routine on vehicle-to-grid availability. Each driver's behaviour is analysed to assess the energy that is available for STOR, with follow on journey requirements also considered.