Development of a Low-Cost 6 DOF Brick Tracking System for Use in Advanced Gas-Cooled Reactor Model Tests

This paper presents the design of a low-cost, compact instrumentation system to enable six degree of freedom motion tracking of acetal bricks within an experimental model of a cracked Advanced Gas-Cooled Reactor (AGR) core. The system comprises optical and inertial sensors and capitalises on the advantages offered by data fusion techniques. The optical system tracks LED indicators, allowing a brick to be accurately located even in cluttered images. The LED positions are identified using a geometrical correspondence algorithm, which was optimised to be computationally efficient for shallow movements, and complex camera distortions are corrected using a versatile Incident Ray-Tracking calibration. Then, a Perspective-Ray-based Scaled Orthographic projection with Iteration (PRSOI) algorithm is applied to each LED position to determine the six degree of freedom pose. Results from experiments show that the system achieves a low Root Mean Squared (RMS) error of 0.2296 mm in x, 0.3943 mm in y, and 0.0703 mm in z. Although providing an accurate measurement solution, the optical tracking system has a low sample rate and requires the line of sight to be maintained throughout each test. To increase the robustness, accuracy, and sampling frequency of the system, the optical system can be augmented with an Inertial Measurement Unit (IMU). This paper presents a method to integrate the optical system and IMU data by accurately timestamping data from each set of sensors and aligning the two coordinate axes. Once miniaturised, the developed system will be used to track smaller components within the AGR models that cannot be tracked with current instrumentation, expanding reactor core modelling capabilities

Reactivating Dynamic Architecture: A Strategy to Inject Relevant Bodily Imagery Back into Architecture

The building-body analogy, which used to be crucial in the designing of buildings, to the exception of a few, is fading. This broken link leaves us with a melancholic yearning; a sense of loss. Reactivating Dynamic Architecture readdresses the use of the body in architecture by the application of an intervening design process. The processes we undertake in order to design architecture are too often assumed, and go unchallenged. In this thesis the design process is seen as a protagonist for change. Representation, both architectural and artistic, is a central theme as the thesis guides images of the human body through abstraction. Both the dynamic body and fragmented body are investigated for their potential to create a relevant expression for the human condition. Dalibor Vesely’s theory of the positive fragment is identified as a way forward for bodily fragmentation, and Analytical Cubism, which resonated with this theory, is explored. The thesis initially moves through the investigation of historical interpretations of the body before drawing on contemporary theory. Past depictions of the fragmented and dynamic body are assessed in order to establish what they can offer us for future analysis. A representational mode is established, based on Cubism’s methods, from here the transition from drawings to architecture begins. Rowe and Slutzky’s text Transparency: Literal and Phenomenal is used to unravel the intricacies of Le Corbusier’s Villa at Garches, and their reading of this building is used to channel a successful conversion process. The resulting architecture was created as a trial of the strategy and is posed as an expression, or speculation, for what can be achieved through this method. Three different scale interventions are explored within the chosen site of Ava Train Station, Wellington. Carlo Scarpa’s techniques guide the last transition to architecture, as his processes are recognised for their ability to fold meaning into design. The described design process gathers complexity as it gains momentum; there is much to negotiate through the realms of bodily perception, modern art and architectural representation. However, the architectural expression carries that density of meaning in a simple expressio

Design and calibration of a hall effect system for measurement of six-degree-of-freedom motion within a stacked column

This paper presents the design, development and evaluation of a unique non-contact instrumentation system that can accurately measure the interface displacement between two rigid components in six degrees of freedom. The system was developed to allow measurement of the relative displacements between interfaces within a stacked column of brick-like components, with an accuracy of 0.05 mm and 0.1 degrees. The columns comprised up to 14 components, with each component being a scale model of a graphite brick within an Advanced Gas-cooled Reactor core. A set of 585 of these columns makes up the Multi Layer Array, which was designed to investigate the response of the reactor core to seismic inputs, with excitation levels up to 1 g from 0 to 100 Hz. The nature of the application required a compact and robust design capable of accurately recording fully coupled motion in all six degrees of freedom during dynamic testing. The novel design implemented 12 Hall effect sensors with a calibration procedure based on system identification techniques. The measurement uncertainty was ±0.050 mm for displacement and ±0.052 degrees for rotation, and the system can tolerate loss of data from two sensors with the uncertainly increasing to only 0.061 mm in translation and 0.088 degrees in rotation. The system has been deployed in a research programme that has enabled EDF to present seismic safety cases to the Office for Nuclear Regulation, resulting in life extension approvals for several reactors. The measurement system developed could be readily applied to other situations where the imposed level of stress at the interface causes negligible material strain, and accurate non-contact six-degree-of-freedom interface measurement is required

The development of a physical model of an advanced gas cooled reactor core: Outline of the feasibility study

The ageing issues of the Advanced Gas Cooled Reactor (AGR) cores need addressing to maintain their safe and reliable operation, hence the requirement for the computer models of the cores used for the seismic resilience assessments to be conservative and to represent larger percentages of damaged graphite components. The current models have undergone limited experimental validation for high levels of degradation, so there is a need to validate those numerical models and also to enhance the understanding of core dynamics by physical modelling and testing. This paper outlines the feasibility study of a quarter scale model rig of an AGR core developed by the University of Bristol. The damage scenarios to be considered in demonstrating the core seismic tolerability were defined. The principles of scale modelling were put under scrutiny in parallel with several practical aspects of material selection and component design and manufacturing. Several variants of physical models of different size and shape were proposed and their merits with respect to their feasibility and outcomes were discussed. Aspects of instrumentation design are presented together with relevant measurement results. The rig is a viable experimental tool whose outputs can be employed directly in computer model validation