Strokes for Representing Univariate Vector Field Maps

Particle systems make an excellent tool for creating tracks (which we call strokes) in vector fields. The question addressed in this paper is how such tracks should be made to vary in size and colour in order to reveal properties such as local direction and strength of the field. We find that for strokes that vary from large to small, direction is indicated by the large end. We also find that for strokes that vary in colour, the colour of the background is the most important determinant of perceived direction

Pile-up solutions for some systems of conservation laws modelling dislocation interaction in crystals

Some continuum models for dislocation interactions in a simple crystal geometry are studied. The simplest models are mixed systems of conservation laws which are shown to exhibit singularities and instabilities. These are then regularized, leading to parabolic free-boundary problems. In both cases, solutions describing the formation of structures such as dislocation pile-ups are discussed

Constraint capture and maintenance in engineering design

The Designers' Workbench is a system, developed by the Advanced Knowledge Technologies (AKT) consortium to support designers in large organizations, such as Rolls-Royce, to ensure that the design is consistent with the specification for the particular design as well as with the company's design rule book(s). In the principal application discussed here, the evolving design is described against a jet engine ontology. Design rules are expressed as constraints over the domain ontology. Currently, to capture the constraint information, a domain expert (design engineer) has to work with a knowledge engineer to identify the constraints, and it is then the task of the knowledge engineer to encode these into the Workbench's knowledge base (KB). This is an error prone and time consuming task. It is highly desirable to relieve the knowledge engineer of this task, and so we have developed a system, ConEditor+ that enables domain experts themselves to capture and maintain these constraints. Further we hypothesize that in order to appropriately apply, maintain and reuse constraints, it is necessary to understand the underlying assumptions and context in which each constraint is applicable. We refer to them as “application conditions” and these form a part of the rationale associated with the constraint. We propose a methodology to capture the application conditions associated with a constraint and demonstrate that an explicit representation (machine interpretable format) of application conditions (rationales) together with the corresponding constraints and the domain ontology can be used by a machine to support maintenance of constraints. Support for the maintenance of constraints includes detecting inconsistencies, subsumption, redundancy, fusion between constraints and suggesting appropriate refinements. The proposed methodology provides immediate benefits to the designers and hence should encourage them to input the application conditions (rationales)

The role of ontologies in creating and maintaining corporate knowledge: a case study from the aero industry

The Designers’ Workbench is a system, developed to support designers in large organizations, such as Rolls-Royce, by making sure that the design is consistent with the specification for the particular design as well as with the company’s design rule book(s). The evolving design is described against a jet engine ontology. Currently, to capture the constraint information, a domain expert (design engineer) has to work with a knowledge engineer to identify the constraints, and it is then the task of the knowledge engineer to encode these into the Workbench’s knowledge base (KB). This is an error prone and time consuming task. It is highly desirable to relieve the knowledge engineer of this task, and so we have developed a tool, ConEditor+ that enables domain experts themselves to capture and maintain these constraints. The tool allows the user to combine selected entities from the domain ontology with keywords and operators of a constraint language to form a constraint expression. Further, we hypothesize that to apply constraints appropriately, it is necessary to understand the context in which each constraint is applicable. We refer to this as “application conditions”. We show that an explicit representation of application conditions, in a machine interpretable format, along with the constraints and the domain ontology can be used to support the verification and maintenance of constraints

Environmental and biodiversity impacts of organic farming in the hills and uplands of Wales

1. Organic farming is based on principles of co-existence with natural systems, the minimisation of pollution and damage to the environment, and the promotion of the health of soil, plant and animal to produce healthy food with high standards of animal welfare and respect for the wider social and ecological impacts of the agricultural system. 2. Organic Farming has become an important aspect of EU agri-environment policy. Since the implementation of EC Reg. 2078/92 the EU promotes organic farming explicitly on its positive effects on the environment. 3. The environmental and biodiversity benefits of organic systems in the lowlands for mixed farming is generally accepted (Shepherd, 2003) but similar benefits for upland systems have not been identified. This report has been produced by OCW with funding from CCW to address this gap. Where relevant, means to ensure the beneficial impacts through changes to agri-environment schemes, organic standards, and education and dissemination are identified. 4. Hill and uplands are characterised as areas over 200m above sea level where the physical landscape results in production constraints. 5. Biodiversity losses linked to changes in hill and upland agriculture include the erosion of genetic diversity in farmed livestock and crops as well as in wildlife and flora, a reduction in habitat, soil and wildlife diversity and the loss of local knowledge and farming culture. 6. The organic approach to sustainable agriculture in hill or upland systems is through the use of multi species swards and mixed stocking. 7. The report identifies potential points of difference between organic and conventional management practices with regard to hill and upland farming and highlights research requirements to confirm or explore those potentials. 8. Conventional farms can adopt any or all of the practices of the organic farming system, but the engagement with the entire system and annual inspections are specific to the organic farmer. 9. The impacts are not just determined by the system of organic regulations and but also by the management ability and technical skills of the farmer and workers. 10. The practices on organic livestock farms identified that may differ from conventional and have direct biodiversity or environmental impacts are: lower stocking rates (overall manure loading maximum of 170kg/N/ha/yr); an adjustment of the stocking balance (increasing ratio of cattle to sheep); keeping indigenous breeds and strains adapted to the environmental conditions on the farm; limitation on products to control external parasites; reduction and restriction on the use of prophylactic veterinary medicines; the use of foragebased diets; storage and use of slurries, manures and composts, and constraints on the import and export of nutrients. 11. Organic practices in management of grassland and crops identified that may differ from conventional and have direct biodiversity or environmental impacts are: cessation of N fertiliser use; restriction on P & K use; use of lime to maintain pH; use of clovers and herbs in grass leys; cessation of use of chemical pesticides and all herbicides; mechanical and manual weed control and sensitive and timely cultivations; the use of mixed farm systems and rotations on in-bye land; the use of cover crops and undersowing; the use of green manures. 12. Organic regulations do not require habitat creation, but standards state, “that concern for the environment should manifest”…“in high standards of conservation management throughout the organic holding”. Discussion 13. Apart from practices that impact directly on biodiversity or the environment, each management decision on the farm will have knock-on effects that have their own consequences, for example welfare standards for livestock require bedding materials and greater housing space. 14. Organic farms operating solely in the hills and uplands can only be part of a system. Use of in-bye land or having a relationship with lowland holdings to provide winter-feed and forage is necessary to comply with regulations. This will increase the amount of lowland managed organically, bringing widely recognised environmental benefits. 15. Organic agriculture is, by legal definition, a system of production and is based on principles and uses practices adopted to optimise the health of the system. Any farmer may adopt individual practices, and the Tir Gofal scheme provides an opportunity for farmers to provide positive conservation measures, whether conventional or organic. Farming under the EU Regulation defining Organic farming provides assurance to the end consumer that the system used to produce or process the food product was according to that system. This provides a reliable means for consumers to support a system of agriculture that fits more closely with their expectations than intensive systems. 16. Any advantages of lower stocking rates and mixed stocking will only be maintained while organic farms are viable. Organic labelling provides an opportunity for consumers to make a positive choice for high welfare, environmentally benign systems; however the difficulties of marketing, the lack of consumer awareness of food production issues and unwillingness to pay are barriers to access to premium markets for many producers. Conclusions: 17. The potential benefits of individual practices outlined in the document are often clear, but there are currently few data to confirm the extent of some of the practices that may have most beneficial impact. The need for data on actual practices of the organic farmers in the hills and uplands is therefore highlighted. 18. Few Standards changes are recommended, however the monitoring of derogations to standards and use of restricted veterinary inputs is recommended. 19. Research and development needs, technical, education and dissemination, and agri-environment policy issues which may establish, ensure, or enhance the environmental and biodiversity impacts of organic farming in the hills and uplands are outlined. 20. Infrastructure work to integrate hill and upland and lowland systems is necessary to facilitate organic farming in the uplands; this may assist the viability of lowland organic holdings: the environmental benefits of which are established

A Photonic Implementation for the Topological Cluster State Quantum Computer

A new implementation of the topological cluster state quantum computer is suggested, in which the basic elements are linear optics, measurements, and a two-dimensional array of quantum dots. This overcomes the need for non-linear devices to create a lattice of entangled photons. We give estimates of the minimum efficiencies needed for the detectors, fusion gates and quantum dots, from a numerical simulation

ConEditor+: Capture and Maintenance of Constraints in Engineering Design

The Designers' Workbench is a system, developed to support designers in large organizations, such as Rolls-Royce, by making sure that the design is consistent with the specification for the particular design as well as with the company’s design rule book(s). Currently, to capture the constraint information, a domain expert (design engineer) has to work with a knowledge engineer to identify the constraints, and it is then the task of the knowledge engineer to encode these into the Workbench's knowledge base (KB). This is an error prone and time consuming task. It is highly desirable to relieve the knowledge engineer of this task, and so we have developed a tool, ConEditor+ that enables domain experts themselves to capture and maintain these constraints. The tool allows the user to combine selected entities from the domain ontology with keywords and operators of a constraint language to form a constraint expression. Further, we hypothesize that to apply constraints appropriately, it is necessary to understand the context in which each constraint is applicable. We refer to this as "application conditions". We show that an explicit representation of application conditions, in a machine interpretable format, along with the constraints and the domain ontology can be used to support the verification and maintenance of constraints