Biospheres and solar system exploration

The implications of biosphere technology is briefly examined. The exploration status and prospects of each world in the solar system is briefly reviewed, including the asteroid belt, the moon, and comets. Five program elements are listed as particularly critical for future interplanetary operations during the coming extraterrestrial century. They include the following: (1) a highway to Space (earth orbits); (2) Orbital Spaceports to support spacecraft assembly, storage, repair, maintenance, refueling, launch, and recovery; (3) a Bridge Between Worlds to transport cargo and crews to the moon and beyond to Mars; (4) Prospecting and Resource Utilization Systems to map and characterize the resources of planets, moons, and asteroids; and (5) Closed Ecology Biospheres. The progress in these five field is reviewed

Structural techniques in descriptive complexity

In 2017, Abramsky, Dawar, and Wang published a paper which gave a comonadic characterisation of pebble games, tree-width, and k-variable logic, a key trio of related concepts in Finite Model Theory. In 2018, Abramsky and Shah expanded upon this to give an analogous comonadic characterisation of Ehrenfeucht Fraisse games, tree-depth, and bounded quantifier rank logic. A key feature of these papers is the connection between two previously distinct subfields of logic in computer science; Categorical Semantics, and Finite Model Theory. This thesis applies the ideas and techniques in these papers to give a categorical account of some cornerstone results of Finite Model Theory, including Rossman’s Equirank Homomorphism Preservation Theorem, Courcelle’s Theorem (on the model-checking properties of structures of bounded tree-width), and Gaifman’s Locality Theorem

Electronic countermeasures applied to passive radar

Passive Radar (PR) is a form of bistatic radar that utilises existing transmitter infrastructure such as FM radio, digital audio and video broadcasts (DAB and DVB-T/T2), cellular base station transmitters, and satellite-borne illuminators like DVB-S instead of a dedicated radar transmitter. Extensive research into PR has been performed over the last two decades across various industries with the technology maturing to a point where it is becoming commercially viable. Nevertheless, despite the abundance of PR literature, there is a scarcity of open literature pertaining to electronic countermeasures (ECM) applied to PR. This research makes the novel contribution of a comprehensive exploration and validation of various ECM techniques and their effectiveness when applied to PR. Extensive research has been conducted to assess the inherent properties of the lluminators of Opportunity to identify their possible weaknesses for the purpose of applying targeted ECM. Similarly, potential jamming signals have also been researched to evaluate their effectiveness as bespoke ECM signals. Whilst different types of PR exist, this thesis focuses specifically on ECM applied to FM radio and DVB-T2 based PR. The results show noise jamming to be effective against FM radio based PR where jamming can be achieved with relatively low jamming power. A waveform study is performed to determine the optimal jamming waveform for an FM radio based PR. The importance of an effective direct signal interference (DSI) canceller is also shown as a means of suppressing the jamming signal. A basic overview of counter-ECM (ECCM) is discussed to counter potential jamming of FM based PR. The two main processing techniques for DVB-T2 based PR, mismatched and inverse filtering, have been investigated and their performance in the presence of jamming evaluated. The deterministic components of the DVB-T2 waveform are shown to be an effective form of attack for both mismatched filtering and inverse filtering techniques. Basic ECCM is also presented to counter potential pilot attacks on DVB-T2 based PR. Using measured data from a PR demonstrator, the application and effectiveness of each jamming technique is clearly demonstrated, evaluated and quantified

Lecture capture using large interactive display systems

There are various software technologies that allow capture and redelivery of lectures. Most of these technologies however rely on the use of proprietary software, often requiring extra efforts from the lecturer in terms of the initial preparation of the lecture material, or in editing and annotating after the lecture to make the material suitable for the students. To review the material students then require access to the proprietary software. This paper describes a system for the lightweight capture of lecture presentations, based on the use of a low-cost large interactive display surface, together with standard Microsoft PowerPoint™ presentation software. The captured version of the presentation includes the original lecture slides, graphical annotations made by the lecturer during the lecture, and the audio recording of the lecture; all saved as a PowerPoint file. In addition, the system adds some annotations and index slides to allow quick and easy access to different segments of the presentation. Presentations can be replayed in part or in full as required, preserving all of the content of the live lecture

Practical considerations for deep learning

The work in this dissertation was done as a major shift in machine perception and deep learning research was happening. Neural networks have proved to be an important part of machine perception and other domains of artificial intelligence over the last several years. This is due to several advances that have made neural networks more practical for real world applications. The goal of this dissertation is to present several works that track some advances in deep learning including: the move from greedy unsupervised pre-training to end-to-end supervised learning, GPU accelerated training of large neural, and the more recent successes of auto-regressive models for generating high-dimensional data. This dissertation will present four of my works. The first, develops a novel convolutional auto-encoder, and shows it can learn useful features that improve supervised image classification results when data is scarce. The second, uses distributed systems with multiple GPUs to train neural networks. The third, develops a method for using neural networks for object detection in video. The fourth speeds up generation for auto-regressive models of time-series, i.e. Wavenet. Then I will conclude and describe some follow up research I would like to pursue including: work on speeding up generation for auto-regressive models of images, i.e. PixelCNN, and using dilated causal convolutional models for Reinforcement Learning

Design and implementation of a dual polarised L-band parabolic dish antenna for NeXtRAD

Research into multi-static, multi-band networked radar has led to the development of the NeXtRAD radar system. This dissertation will investigate the design and implementation of a dual polarised L-Band prime focus dish antenna with a centre frequency of 1.3 GHz and a HPBW of 10° in the azimuth plane. The antenna is required to handle a peak power of 1.5 kW over a 50 MHz bandwidth and be able to withstand environmental factors such as wind while mounted on a tripod. This dissertation forms part of the larger NeXtRAD project and as such, the antenna design requirements have been set based on the wider system specifications. Previous investigations into the feasibility of various antenna designs have concluded that a prime focus parabolic dish antenna would be the most appropriate to meet the design requirements. The dissertation details the design and manufacturing process followed. All antenna parameters have been simulated using a combination of FEKO v7 and CST 2014 to compare and verify the designs and simulations. Due to manufacturing limitations, the optimal antenna design could not be manufactured and, as a result, compromises had to be made in order for an antenna prototype to be manufactured and tested. These tests include, amongst others, characterisation of the return loss, cross polarisation, gain, beamwidth and beam pattern of the antenna in both planes of polarisation. These results have been recorded, analysed and compared to those found through simulations