The first project undertaken was to develop a currently non-existent forensic technique -- data recovery from damaged SIM cards. SIM cards hold data valuable to a forensic investigator within non-volatile EEPROM/flash memory arrays. This data has been proven to be able to withstand temperatures up to 500°C, surviving such scenarios as house fires or criminal evidence disposal. A successful forensically-sound sample extraction, mounting and backside processing methodology was developed to expose the underside of a microcontroller circuit's floating gate transistor tunnel oxide, allowing probing via AFM-based electrical scanning probe techniques. Scanning Kelvin probe microscopy has thus far proved capable of detecting the presence of stored charge within the floating gates beneath the thin tunnel oxide layer, to the point of generating statistical distributions reflecting the threshold voltage states of the transistors. The second project covered the novel forensic application of AFM as a complimentary technique to SEM examination of quartz grain surface textures. The analysis and interpretation of soil/sediment samples can provide indications of their provenance, and enable exclusionary comparisons to be made between samples pertinent to a forensic investigation. Multiple grains from four distinct sample sets were examined with the AFM, and various statistical figures of merit were derived. Canonical discriminant analysis was used to assess the discriminatory abilities of these statistical variables to better characterise the use of AFM results for grain classification. The final functions correctly classified 65.3% of original grouped cases, with the first 3 discriminant functions used in the analysis (Wilks' Lambda=0.336, p=0.000<0.01). This degree of discrimination shows a great deal of promise for the AFM as a quantitative corroborative technique to traditional SEM grain surface examination.

This thesis presents techniques for designing fractional-N synthesisers which achieve both low phase noise and high loop bandwidth simultaneously. The objective is to provide a single-loop synthesiser solution that satisfies the requirements on both the phase noise level and frequency switching speed specified by wireless standards. The GSM 900 standard is used as the bench- mark in this work but these techniques can also be applied to synthesisers for other wireless applications. A linearised synthesiser phase noise model is proposed for evaluating the proposed techniques. The model is constructed by characterising the major sources of synthesiser phase noise and integrating them with the loop transfer function. The accuracy of the model is validated by experimental results. As quantisation noise is one major source contributing to synthesiser phase noise, a number of novel noise reduction techniques are proposed. These techniques are based on \Sigma\Delta modulation and implemented with the stored-sequence method. A streamlined procedure for designing the \Sigma\Delta sequences is proposed. A prototype hardware synthesiser is developed with the proposed techniques. The synthesiser is designed for the GSM 900 standard with an output frequency range between 890 MHz and 960 MHz. The loop bandwidth is 250 kHz. Results obtained from measurements show that the synthesiser has a phase noise performance that meets GSM 900 phase noise specifications. Results also confirm the effectiveness of the proposed quantisation noise reduction technique. A new mechanism responsible for intermodulation effects in fractional-N synthesisers is described. It is found that fractional-N synthesisers are vulnerable to VCO-to-PFD coupling, which generates a family of spurious components in the synthesiser spectrum. Analytical and numerical models are developed to predict the magnitude and distribution of these spurs. The predictions are confirmed by results from hardware synthesiser experiments.

This dissertation describes experimental studies on the surface treatment and functionalisation of carbon nanomolecules. For characerisation of the disaggregation state of single-walled carbon nanotube bundles, dielectrophoresis with Raman spectroscopy has been investigated. The presence of semiconducting nanotubes in the Raman spectrum following dielectrophoretic assembly indicates incomplete disaggregation. I show that this novel technique is a more effective measure than two existing conventional techniques: (a) optical absorption measurement and (b) the reduction of (10, 2) semiconducting nanotube peak in the Raman spectrum. Excimer lamp processing has been used for three applications: (i) preferential destruction of metallic nanotubes, (ii) nitrization of nanotubes and (iii) instantaneous removal of nanotube caps by ozonolysis. Preferential destruction was undertaken by ultraviolet irradiation in an argon atmosphere. The Raman spectrum after radiation reveals that more metallic nanotubes were destroyed than semiconducting nanotubes. The radial breathing mode peak intensity of (13, 4) metallic nanotubes dropped by about 67 %. Nitrization of carbon nanotubes was undertaken by dissociation of nitric oxide using excimer lamp irradiation. Spectroscopic studies by FTlR and XPS on the irradiated nanotubes suggest that nitric oxide was chemically functionalised on the surface of the nanotubes. The change of surface morphology of the nanotubes was shown by transmission electron microscopy. Removal of nanotube caps was done by excimer lamp induced ozonolysis. Contact angle measurement and electron microscopy on the nanotubes which had been irradiated for ten seconds showed that the end-caps had been removed. Electrophoresis has been utilised for fabrication of a glass-like carbon film. Raman spectroscopy and scanning electron microscopy has shown the presence of glass-like carbon. This fabrication can be done at room temperature, whereas most fabrication processes are undertaken by high temperature processes exceeding 1000 oC.

The Transmission Control Protocol (TCP) carries the majority of today’s Internet traffic due to the success of the responsive congestion control mechanisms. However, the number of streaming media applications has grown tremendously during the past several years. Such applications do not use the TCP protocol, this implies that they rarely provide end-to-end congestion control (i.e. they are unresponsive) in a TCP-friendly manner and that they do not share the available bandwidth fairly with applications built on TCP. Additionally, it has been observed that short-lived flows (SLF) are at a disadvantage when competing against long-lived flows (LLF). This dissertation presents the fair bandwidth allocation architectural framework to provide fair allocation of network resources for competing flows traversing the network. The major contribution of this work is the design and implementation of a router-based Active Queue Management (AQM) scheme, Fair Early Drop (FED) which provides fair distribution of network bandwidth amongst competing responsive and unresponsive flows and LLFs and SLFs. A traffic classification module is also developed to identify LLFs from SLFs to enable FED to preferentially treat SLFs over LLF. SLFs are allowed to pass through the network without dropping any packets from them.

Zinc oxide (ZnO) has become a popular semiconducting material to study because of its wide applications. ZnO Nanorods (NR) in particular are very exciting features because of their unique properties which include the crystal dimensionality, highly optical transparency, tuneable electrical conductivity, integrity into pre-existing technologies and many others. Meanwhile, controlled and reliable synthesis of ZnO NR is still challenging and many methods have been proposed for a cheap growth of ZnO NR in large scale. Recently, electrochemically deposited ZnO film is attracting much attention, as it provides large-scale synthesis while ensuring a good electrical contact. This thesis studied the growth of a single nanostructure zinc oxide (ZnO) using electrochemistry, with special focus on the nanorod and their physical properties. In this work, ZnO was electrochemically deposited on ITO using mainly three electrochemical techniques: potentiodynamic (PD), potentiostatic (PS) and galvanostatic (GS). The time transient current and voltages were recorded in situ and analysed in depth. During our PD studies, we have identified different deposition mechanisms depending on the growth parameters, which are progressive and coalescent nucleation (NC). The Sharifker equation was the model used to describe PS ZnO progressive and NC process while nothing has been suggested for GS. Furthermore, we noticed that the same Sharifker model could no longer hold where the recorded current density was considerably high during the PS ZnO deposition. Here, we propose a model for GS ZnO deposition based on the electrical damping. We also suggest its adaptability for PS ZnO deposition when the charge transfer rate is comparably high. The physical properties of the nanorods were characterized using scanning electron microscope (SEM) and x-ray diffraction (XRD). The morphology of features at different deposition setups were studied and a parameter for was established for obtaining ITO covered with ZnO NR only. AFM and MATLAB program were also used to find a pattern of how for the size and the density of rods are distributed during the ZnO deposition on ITO. We have also investigated the crystal properties of deposited ZnO NR and we discovered that different deposition technique, or current density during the deposition, lead to different levels of Zn(OH)2 incorporation in the NR crystal which was confirmed with FTIR. The electrical conductivity was deduced using scanning tunnelling microscope (STM) at different tip heights, and was found to be 20 Ωcm with a carrier concentration of 3x1015 cm-3. Similar results were also obtained with a conductive atomic force microscope (AFM). In addition, two conduction mechanisms were observed depending on the crystallinity of the sample. The results show that electrochemically grown ZnO nanorods have electrical properties suitable with possibility of tailoring for use in optoelectronic devices such as diodes, varistors, solar cells and transistors. Few optoelectronic devices were designed based on the ECD grown ZnO. ASi: H p-i-n solar cells were deposited after the electrochemical deposition of ZnO on ITO-coated substrates. The results show that the textured solar cell performance was 30% higher than the planar solar cell. We also attempted flexible transparent ZnO based liquid-solid state solar cell (photoelectrochemical cell). Although a photoresponse was observed under UV, it had a poor charge collection efficiency (< 0.5%) which was attributed to the transparency and the thickness of ZnO layer.

Radar has emerged as a useful tool for measuring avalanches to improve our knowledge of their behaviour. These measurements are used to refine and validate mathematical models of avalanches which are employed in the calculation of avalanche risk zones. However, current radar measurements do not provide a true representation of an entire avalanche flow due to their inadequate range resolution and lack of cross-range resolution. This thesis describes the development of an FMCW phased-array radar for use as a research tool to enable 2-D field measurements of avalanches in unparalleled detail. The design of the radar is presented in detail based on a review of the current avalanche remote sensors and applicable radar literature. The radar operates at 5.3GHz to illuminate dense centimetre-size blocks of snow. It is shown that the developed radar has a range resolution of 1.3m following processing, a 19x gain over other avalanche radar, and is sensitive to snow movements beyond 2.5km, sufficient to measure an entire avalanche flow. Additionally, methods of processing the radar data are developed. These include MTI processing using an IIR filter, avalanche front detection using OS-CFAR, and cohering of the array using low-quality phase synchronising sources within the field-of-view of the radar. The radar is now deployed in a bunker at well-equipped avalanche test site in Switzerland where it automatically records naturally occurring avalanches. This thesis describes two avalanches which were recorded by the radar during the 2010/11 winter. The collected data has been processed using the aforementioned processing techniques. The processing outputs are presented including single channel range-time images, velocity measurements of the avalanche fronts, and detailed 2-D images of the avalanches showing unprecedented detail. It is shown that there is the potential to extract velocity measurements of individual blocks of snow comprising the avalanche.

With the proliferation of latency aware services such as live video streaming, Internetbased financial trading and the popularity of distributed overlays such as BitTorrent there is a growing need for latency-aware distributed overlays. To make such overlays viable, efficient resource discovery services are needed. Anycast is a routing protocol that sends packets to nodes that are a member of a particular group, with the work presented the Anycast protocol in the distributed overlay domain. Structured and unstructured distributed networks have become a popular way to disseminate data without the need for a fixed infrastructure, however there is a need to provide quality of service (QoS). To meet the demands of applications, an overlay needs to maintain accurate Anycast group membership data, locality information and have minimal protocol overhead. Three protocols are proposed to meet these goals. The Distributed Overlay Anycast Table (DOAT) brings the notion of locality to a structured overlay, while introducing Bloom filters as an efficient data structure to present an overlay that can accurately return a node that is participating in a particular group. The Gossip Overlay Anycast Table (GOAT) is a scalable location-aware unstructured overlay that can provide the probabilistic Anycast routing. Through the use of an efficient discovery protocol and the use of Bloom filters, GOAT is able to provide the advantages of a structured overlay, while mitigating the performance issues typically found in unstructured overlays. The N-casting overlay is an unstructured overlay with the ability to send queries to multiple members of an group, uses a hierarchical decomposition of the Internet and an elegant data structure that offers predictable compression of overlay membership. N-casting shows that unstructured overlays can be scalable and sustain high performance in environments that exhibit realistic membership churn. DOAT, GOAT and N-casting present viable services that implemented at the application layer provide location aware node discovery in QoS-enabled applications.

This research project aims to investigate the phenomenon of extraordinary optical transmission (EOT) in arrays of asymmetric cruciform apertures. The specific area of EOT examined is the dependence of transmission on incident polarisation. The approach to investigating this phenomenon can be divided into three main sections: fabrication, characterisation and simulations. The method of fabrication involved two main processes: fabrication of Au thin films on CaF2 substrates using thermal evaporation, and the milling of cruciform apertures in the thin films using focused in beam (FIB). A 5 nm adhesion layer of Cr was first thermally evaporated onto the CaF2 substrate followed by an Au film, typically of 30 nm thickness. The unit cells have a lattice constant of 2 μm and typical feature sizes of the apertures are between 160 nm and 1675 nm. The transmission and reflection characteristics are examined using Fourier transform infrared spectroscopy (FTIR) for the Mid IR wavelength range. The dependence of the transmission and reflection on polarisation was investigated. It was found that the arrays display two distinct transmission maxima and a point at which transmission is invariant for all polarisations. The transmission peaks occurred in the wavelength range of 2μm to 6 μm. An ensemble of arrays was fabricated to examine the change in wavelength of the transmission peaks and the invariant point as one of the aperture dimensions was varied. It was found that the transmission wavelength and the wavelength of the invariant point could be tuned by altering the dimensions of the cruciform apertures. Simulations for transmission and reflection were carried out in addition to field profile simulations. Together, these confirmed the assumed processes by which the polarisation dependent transmission maxima were generated, i.e. by localised surface plasmons. One of the arrays more closely examined had transmission peaks at 3.9μm and 5.75μm and an invariant point at 4.46μm. For this array simulations were also used to determine the polarisation state of the transmitted wave. The simulations show that arrays of asymmetric apertures change the incident polarisation such that the transmitted wave becomes elliptically polarised with a major axis that is in general different from the polarisation angle of the incident wave. A maximum shift of around 33! was determined using simulations for a wavelength ! = 3.9μm and an incident polarisation of 60! relative to the x axis. Experimental data was obtained that corroborates these findings.

This thesis is concerned with methods to facilitate automatic target recognition using images generated from a group of associated radar systems. Target recognition algorithms require access to a database of previously recorded or synthesized radar images for the targets of interest, or a database of features based on those images. However, the resolution of a new image acquired under non-ideal conditions may not be as good as that of the images used to generate the database. Therefore it is proposed to use super-resolution techniques to match the resolution of new images with the resolution of database images. A comprehensive review of the literature is given for super-resolution when used either on its own, or in conjunction with target recognition. A new superresolution algorithm is developed that is based on numerical Markov chain Monte Carlo Bayesian statistics. This algorithm allows uncertainty in the superresolved image to be taken into account in the target recognition process. It is shown that the Bayesian approach improves the probability of correct target classification over standard super-resolution techniques. The new super-resolution algorithm is demonstrated using a simple synthetically generated data set and is compared to other similar algorithms. A variety of effects that degrade super-resolution performance, such as defocus, are analyzed and techniques to compensate for these are presented. Performance of the super-resolution algorithm is then tested as part of a Bayesian target recognition framework using measured radar data.

This thesis addresses the topic of integration of weapons systems into communication networks to provide an advanced battlefield capability, with particular application to air launched and long range crew served weapon systems which may also be vehicle mounted. It considers the use of 'Military off-the-shelf' seeker, navigation and communication systems coupled with a novel tandem warhead system. This combination of 'low risk' technologies and a novel warhead system is intended to demonstrate a greater flexibility in weapon systems which could be exploited to reduce development risk, integration risk, qualification costs and increase target defeat capability across the wider more current target set. The use of a suitable communication and navigation system enabling integration of such a weapon system into a networked force was also investigated. This thesis is based on one area of research; Multiple Effects Weapons. Research is being undertaken by several nations on Multiple Effects Weapons. The aim of this research is not to provide a one weapon fits all solution, a panacea, the aim is to widen the utility of one system which could be employed in many roles. As yet no warhead system has achieved the types of effects that are being sought, although research and product development – particularly in the United States of America - continues. Therefore the United Kingdom government has sought to understand what technologies would be required to achieve a truly flexible warhead system which would enable defeat of large Main Battle Tanks, heavily armoured Infantry Fighting Vehicles, Soft Skinned Vehicles, infantry and urban structures. To this end numerical modelling, design and a demonstration programme of a MEW warhead system was performed. MEW systems are not only reliant on 'Smart' warhead systems, the application of sensors, fuzing and communication systems are crucial to enable suitable employment of a 'one size fits most' approach. The other important sub-systems which provide the link to the battlefield network are also discussed in this thesis, the inclusion of these well developed low risk technologies make it is possible to bring such systems into service in the near term with increased system flexibility. The integration of such a system relies on the current United States Department of Defense procurement strategy which includes development of the Joint Tactical Radio System radio system which will allow Ad-Hoc networking between platforms, weapons systems and commanders. Airframe and propulsion technologies are not discussed; they are outside of the scope of this thesis. The use of proprietary data from suppliers other than QinetiQ has been avoided as suitable permissions are not in place, this has limited the systems engineering aspects of this thesis to high level block diagrams which provide guidance on integration issues.