Multimodal image registration with applications to image fusion

This paper presents an algorithm for accurately aligning two images of the same scene captured simultaneously by sensors operating in different wavebands (e.g. TV and IR). Such a setup is common in image fusion systems where the sensors are physically aligned as closely as possible and yet significant image mis-alignment remains due to differences in field of view, lens distortion and other camera characteristics. Our proposed registration method involves numerically minimising a global objective function defined in terms of local normalised correlation measures. The algorithm is demonstrated on real multimodal imagery and applications to imagefusion are considered. In particular we illustrate thatfused image quality is closely related to the degree ofregistration accuracy achieved. To maintain this accuracy in real systems it is often necessary to continuously update the transform over time. Thus we extend our registration approach to execute in real time on live imagery, providing optimal fused imagery in the presence ofrelative sensor motion andparallax effects

Forensic electrochemistry: developing electrochemical sensors for the detection of illicit compounds

The following thesis reports the development of novel electrochemical protocols to further expand the niche research area of Forensic Electrochemistry. 0 introduces the key fundamental concepts within electrochemistry detailing why it is a significant analytical tool. Also described within this chapter are prior examples of electrochemistry used within in a forensic environment to further justify the use of such techniques in this work setting a solid foundation for the development of electrochemical sensors for previously un-detected (electrochemically) materials. Chapter 2 focuses on the growing epidemic of “Legal Highs” formally known as “Novel (New) Psychoactive Substances” (NPSs) that, at the time of this research is a major concern for drug authorities. Highlighted within is the multitude of existing techniques to analyse NPSs yet unable to simultaneous detect in-the-field with great sensitivity. Chapter 3 provides a summation of the materials employed in this research in addition to the experimental procedures. Furthermore, a brief synopsis of the screen-printing methodology is provided in order to deliver further understanding of the novel electrochemical sensors that are used throughout the thesis. Chapter 4 explores the use of screen-printed electrodes) as a novel electrochemical sensor for illicit compounds; with a particular focus on the NPS mephedrone (4-MMC; MKat; the most commonly abused NPS). The common ‘date-rape’ drug Rohypnol® (flunitrazepam) is also detected using screen-printed electrodes for the first time. The concept of screen-printed electrodes as a novel detector for illicit materials is expanded within Chapter 5 exploring different carbon materials utility as a sensor as well as the avant-garde field of study “Regal Electrochemistry” which utilises British Currency (GBP) to successfully quantify 4-MMC. Finally, Chapter 6 provides a summary and conclusion of the presented work highlighting the societal impact of such research whilst also posturing future work to ensure the field of Forensic Electrochemistry continues to grow

Correlating the Energetics and Atomic Motions of the Metal-Insulator Transition of M1 Vanadium Dioxide

Materials that undergo reversible metal-insulator transitions are obvious candidates for new generations of devices. For such potential to be realised, the underlying microscopic mechanisms of such transitions must be fully determined. In this work we probe the correlation between the energy landscape and electronic structure of the metal-insulator transition of vanadium dioxide and the atomic motions occurring using first principles calculations and high resolution X-ray diffraction. Calculations find an energy barrier between the high and low temperature phases corresponding to contraction followed by expansion of the distances between vanadium atoms on neighbouring sub-lattices. X-ray diffraction reveals anisotropic strain broadening in the low temperature structure's crystal planes, however only for those with spacings affected by this compression/expansion. GW calculations reveal that traversing this barrier destabilises the bonding/anti-bonding splitting of the low temperature phase. This precise atomic description of the origin of the energy barrier separating the two structures will facilitate more precise control over the transition characteristics for new applications and devices.Comment: 11 Pages, 8 Figure

Astrophysical constraints on decaying dark gravitons

In the dark dimension scenario, which predicts an extra dimension of micron scale, dark gravitons (KK modes) are a natural dark matter candidate. In this paper, we study observable features of this model. In particular, their decay to standard matter fields can distort the CMB and impact other astrophysical signals. Using this we place bounds on the parameters of this model. In particular we find that the natural range of parameters in this scenario is consistent with these constraints and leads to the prediction that the mean mass of the dark matter today is close to a few hundred keV and the effective size of the extra dimension is around 1–30 μm

Room-temperature exciton-polaritons with two-dimensional WS2

Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensationand superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS$_2$ coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of $\hbar \Omega_{\rm{Rabi}} = 70$ meV, exceeding the exciton linewidth. Our data are well described by a transfer matrix model appropriate for the large linewidth regime. This work provides a platform towards observing strongly correlated polariton phenomena in compact photonic devices for ambient temperature applications.Comment: 12 pages, 6 figure