David G. Bramall

Key digital enterprise technology methods for large volume metrology and assembly integration

Digital enterprise technology (DET) is a theoretical framework for collaborative design and production development in the context of a products lifecycle. The DET framework can be used to configure digital product and process development technologies which assimilate design data, at various levels of completeness, with a high degree of real-time measurement feedback from the production environment in order to validate the products tolerance specification and the selected production and assembly processes. This paper describes research focused on the integration of two major facets of DET; process planning and large volume metrology (LMV). The challenges encountered include the representation of early designs of complex products, the definition of high risk areas in the process plan and the generation of accurate, dynamic measurement data from large-scale laser metrology in the production environment. The methods employed demonstrate how DET-based strategies for design, manufacture and integration can utilize recent technology advances in aggregate modelling and planning, tolerance analysis tools and 3D coordinate metrology. Early testing using aerospace products has been very promising and the research findings will benefit manufacturers of high-value, high-complexity products within distributed production networks.

Resource-Aware Aggregate Planning for the Distributed Manufacturing Enterprise

Abstract The realization of ‘intelligent and resource aware’ distributed enterprises requires substantial development of the underpinning modelling, information management and knowledge representation technologies. This paper deals with the ‘resource-aware, aggregate planning’ of manufacturing operations at early design stages. The term ‘resource aware’ indicates the creation of a dynamic inter-relationship between the planning entities and the enterprise resources , humans and machines. The technologies employed for implementing the pilot methods include; a web-centric co-development environment, unique methods for enriching planning entities with knowledge , and a flexible engine supporting planning scenarios by using evolutionary computing for optimisation and capability analysis techniques for feedback evaluation.

Organizational knowledge encapsulation and re-use in collaborative product development

This paper discusses the theoretical aspects and applications of a novel methodology for exploiting a knowledge management editor tool to structure organizational knowledge and integrate it with product development activities. An organizational knowledge framework for capturing and representing manufacturing know-how has been developed using an ontological approach. The captured knowledge is converted into the industry-standard eXtensible mark-up language (XML) and then shared within a web-centric product data management (PDM) system to support a collaborative and distributed product development environment. The key business benefit of adopting such an approach arises from the closer integration between the key technical and business activities taking place during early design. In particular the effectiveness of decision making is increased.

A theoretical framework for the integration of resource aware planning with logistics for the dynamic validation of aggregate plans within a production network

One of the most persistent and potentially far reaching, in terms of industrial benefits, problem in new product development, is the parallel and synchronous design and evaluation of the product, the production processes and the production network. The proposed theoretical framework for collaborative design and production network development is based on the concept of Digital Enterprise Technology (DET) and facilitates the integration of design and resource aware planning with aspects of network design and logistics. The controlling cycle of the framework is the DET-enabled, human centric evaluation of products, plans and network configurations that gives rise to an emergent synthesis environment. Early testing using aerospace products has been very encouraging.

A Novel Digital Enterprise Technology Framework for the Distributed Development and Validation of Complex Products

Abstract The development of complex products Involves considerable risk In terms of meeting target delivery dates, controlling life-cycle costs and establishing an efficient production network. This paper describes a new methodology for complex product design and development that utilises the recently proposed framework of ‘Digital Enterprise Technology’ (DET). The methodology Involves utilising the five technical strands of DET and In particular focuses in developing novel methods and tools for aggregate modelling, knowledge management and laser measurement planning to ‘bridge’ the gap that exists between conceptual product design and the organisation of the corresponding manufacturing and business operations. A pilot system has been created for simulating the distributed development and validation of complex aerospace products.

The SALT HRS spectrograph : final design, instrument capabilities, and operational modes

The high-resolution échelle spectrograph, SALT HRS, is at an advanced stage of construction and will shortly become available to the user community of the Southern African Large Telescope (SALT). This paper presents a commentary on the construction progress to date and gives the instruments final specification with refined estimates for its performance based on the initial testing of the optics and the science-grade detectors. It also contributes a discussion of how the fibre input optics have been tailored to specific scientific aspirations to give four distinct operational modes. Finally, the use of the instrument is discussed in the context of the most common science cases.

Performance of the Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS)

The Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS) is a fibre-fed R4 échelle spectrograph employing a white pupil design with red and blue channels for wavelength coverage from 370–890nm. The instrument has four modes, each with object and sky fibres: Low (R~15000), Medium (R~40000) and High Resolution (R~65000), as well as a High Stability mode for enhanced radial velocity precision at R~65000. The High Stability mode contains a fibre double-scrambler and offers optional simultaneous Th-Ar arc injection, or the inclusion of an iodine cell in the beam. The LR mode has unsliced 500μm fibres and makes provision for nod-and-shuffle for improved background subtraction. The MR mode also uses 500μm fibres, while the HR and HS fibres are 350μm. The latter three modes employ modified Bowen-Walraven image-slicers to subdivide each fibre into three slices. All but the High Stability bench is sealed within a vacuum tank, which itself is enclosed in an interlocking Styrostone enclosure, to insulate the spectrograph against temperature and atmospheric pressure variations. The Fibre Instrument Feed (FIF) couples the four pairs of fibres to the telescope focal plane and allows the selection of the appropriate fibre pair for a given mode, and adjustment of the fibre separation to optimally position the sky fibre. The HRS employs a photomultiplier tube for an exposure meter and has a dedicated auto-guider attached to the FIF. We report here on the commissioning results and overall instrument performance since achieving first light on 28 September 2013.

The SALT HRS spectrograph: instrument integration and laboratory test results

SALT HRS is a fibre-fed, high dispersion échelle spectrograph currently being constructed for the Southern African Large Telescope (SALT). In this paper we highlight the performance of key optical components, describe the integration tasks that have taken place and present some first light results from the laboratory. The instrument construction is well advanced and we report on the attainment of the required mechanical and thermal stability and provide a measurement of the input optics performance (including the fibre feed). The initial optical alignment of both the fibre input optics, including image slicers, and the spectrograph optics has taken place and is described.

DRAGON: a wide-field multipurpose real time adaptive optics test bench

DRAGON is be a new and in many ways unique visible light adaptive optics test bench. Initially, it will test new and existing concepts for CANARY, the laser guide star tomographic adaptive optics demonstrator on the WHT, then later it will be used to explore concepts for other existing and future telescopes. Natural and Laser Guide Stars (NGS and LGS) are emulated, where the LGSs exhibit the effects of passing up through turbulence and spot elongation. AO correction is performed by one high and one low order deformable mirror, allowing woofer-tweeter control, and multiple high and low order wave front sensors detect wave front error. The Durham Adaptive Optics Real-time Controller (DARC) is used to provide real-time control over various DRAGON configurations. DRAGON is currently under construction, with the turbulence simulator completed. Construction and alignment of the system is expected to be finished in the coming year, though first results from completed modules follow sooner.

Design and production of DESI slit assemblies

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 sq. deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fibre optic positioners. The fibres in turn feed ten broad-band spectrographs. We describe the design, production, quality assurance procedures and performance of the DESI slit assemblies.