UC Research Repository Collection:
http://hdl.handle.net/10092/840
2015-10-07T22:50:44ZThermal modelling and optimisation of building-integrated photo-voltaic thermal systems.
http://hdl.handle.net/10092/11079
Title: Thermal modelling and optimisation of building-integrated photo-voltaic thermal systems.
Authors: McDowell, Alastair Kieran Joel
Abstract: This Masters project has involved detailed thermal analysis of a unique
renewable energies building. A TRNSYS model of this building has been
developed and validated by real measurements and has shown to be capable of accurately predicting room temperatures and total heat gain from a solar-thermal roofing system. Supporting experiments were conducted experimentally and numerically. An experimental solar thermal testing unit constructed for the purpose of validating the solar-thermal roof concept. This experimental apparatus has been used to evaluate the effect of various operating procedures on the total heat gain from the system under a range of meteorological conditions. The validated thermal building model is used to conduct long-term simulations to provide a measure of year-round thermal performance of the building and estimated gains from renewable energy systems. Similar techniques are used to assist in the design and optimisation of a new transportable sustainable building concept in association with StoneWood Homes. It was found that a 4.5kW BIVP/T system could
supply the small building with 100% of the yearly electrical energy and space heating requirements.2015-01-01T00:00:00ZLog periodic dipole array analysis and design for free-space and above-ground applications
http://hdl.handle.net/10092/11077
Title: Log periodic dipole array analysis and design for free-space and above-ground applications
Authors: Foo, Norman Yeow Khean
Abstract: Preliminary to a solution of the problem of horizontally polarized log periodic aerial arrays above ground, various types of log periodic aerials are analysed. Numerical design data for the former problem are displayed in charts which should reduce trial-and-error beam scanning designs to a minimum. The single mast sloping dipole log periodic aerial is given particular attention. Computer programmes and approximate formulae are developed for both free-space and above-ground designs. The far field of these aerials is shown to be predictable from near field data. Experimental investigations, although limited in scope, confirm most of the developed theory at least qualitatively. Suggestions for further investigations are included.1966-01-01T00:00:00ZAccurate wide-area tracking for architectural, engineering and surveying applications.
http://hdl.handle.net/10092/11052
Title: Accurate wide-area tracking for architectural, engineering and surveying applications.
Authors: Head-Mears, James Bradley
Abstract: Augmented Reality (AR) is a powerful tool for the visualisation of, and interaction with, digital information, and has been successfully deployed in a number of consumer applications. Despite this, AR has had limited success in industrial applications as the combined precision, accuracy, scalability and robustness of the systems are not up to industry standards. With these characteristics in mind, we present a concept Industrial AR (IAR) framework for use in outdoor environments.
Within this concept IAR framework, we focus on the improving the precision and accuracy of consumer level devices by focusing on the issue of localisation, utilising LiDAR based point clouds generated as part of normal surveying and engineering workflow.
We evaluate key design points to optimise the localisation solution, including the impact of increased field of view on feature matching performance, the filtering of feature matches between real imagery and an observed point cloud, and how pose can be estimated from 2D to 3D point correspondences.
The overall accuracy of this localisation algorithm with respect to ground-truth observations is determined, with unfiltered results indicating an on par horizontal accuracy and significantly improved vertical accuracy with best-case consumer GNSS solutions. When additional filtering is applied, results of localisation show a higher accuracy than best-case consumer GNSS.2013-01-01T00:00:00ZOblique decision trees in transformed spaces.
http://hdl.handle.net/10092/11051
Title: Oblique decision trees in transformed spaces.
Authors: Wickramarachchi, Darshana Chitraka
Abstract: Decision trees (DTs) play a vital role in statistical modelling. Simplicity and interpretability of the solution structure have made the method popular in a wide range of disciplines. In data classification problems, DTs recursively partition the feature space into disjoint sub-regions until each sub-region becomes homogeneous with respect to a particular class. Axis parallel splits, the simplest form of splits, partition the feature space parallel to feature axes. However, for some problem domains DTs with axis parallel splits can produce complicated boundary structures. As an alternative, oblique splits are used to partition the feature space potentially simplifying the boundary structure. Various approaches have been explored to find optimal oblique splits. One approach is based on optimisation techniques. This is considered the benchmark approach, however, its major limitation is that the tree induction algorithm is computationally expensive. On the other hand, split finding approaches based on heuristic arguments have gained popularity and have made improvements on benchmark methods. This thesis proposes a methodology to induce oblique decision trees in transformed spaces based on a heuristic argument.
As the first goal of the thesis, a new oblique decision tree algorithm, called HHCART (\underline{H}ouse\underline{H}older \underline{C}lassification and \underline{R}egression \underline{T}ree) is proposed. The proposed algorithm utilises a series of Householder matrices to reflect the training data at each non-terminal node during the tree construction. Householder matrices are constructed using the eigenvectors from each classes' covariance matrix. Axis parallel splits in the reflected (or transformed) spaces provide an efficient way of finding oblique splits in the original space. Experimental results show that the accuracy and size of the HHCART trees are comparable with some benchmark methods in the literature. The appealing features of HHCART is that it can handle both qualitative and quantitative features in the same oblique split, conceptually simple and computationally efficient.
Data mining applications often come with massive example sets and inducing oblique DTs for such example sets often consumes considerable time. HHCART is a serial computing memory resident algorithm which may be ineffective when handling massive example sets. As the second goal of the thesis parallel computing and disk resident versions of the HHCART algorithm are presented so that HHCART can be used irrespective of the size of the problem.
HHCART is a flexible algorithm and the eigenvectors defining Householder matrices can be replaced by other vectors deemed effective in oblique split finding. The third endeavour of this thesis explores this aspect of HHCART. HHCART can be used with other vectors in order to improve classification results. For example, a normal vector of the angular bisector, introduced in the Geometric Decision Tree (GDT) algorithm, is used to construct the Householder reflection matrix. The proposed method produces better results than GDT for some problem domains. In the second case, \textit{Class Representative Vectors} are introduced and used to construct Householder reflection matrices. The results of this experiment show that these oblique trees produce classification results competitive with those achieved with some benchmark decision trees.
DTs are constructed using two approaches, namely: top-down and bottom-up. HHCART is a top-down tree, which is the most common approach. As the fourth idea of the thesis, the concept of HHCART is used to induce a new DT, HHBUT, using the bottom-up approach. The bottom-up approach performs cluster analysis prior to the tree building to identify the terminal nodes. The use of the Bayesian Information Criterion (BIC) to determine the number of clusters leads to accurate and compact trees when compared with Cross Validation (CV) based bottom-up trees. We suggest that HHBUT is a good alternative to the existing bottom-up tree especially when the number of examples is much higher than the number of features.2015-01-01T00:00:00Z