Deep Mapping of Small Solar System Bodies with Galactic Cosmic Ray Secondary Particle Showers

We will investigate the use of galactic cosmic ray (GCR) secondary particles to probe the deep interiors of small solar system bodies (SSBs), including comets, asteroids, and geologic structures on the surfaces of airless bodies. Applications include solar system science, planetary defense, and resource utilization. Our Phase I study demonstrated that muons, the long-range charged component of GCR showers, can penetrate SSBs up to a km in diameter, providing information on their interior structure. Muons produced in Earths atmosphere have been applied to image the interior of large objects for science and engineering. In Phase I, we found that the production of muons in the solid surfaces of airless bodies is much smaller than in Earths atmosphere. Nevertheless, the flux of transmitted muons is sufficient to detect inclusions within an asteroid or comet in a reasonable amount of time, ranging from hours to weeks, depending on the size of the SSB and the density contrast, position and size of the inclusion. For asteroids and comets, large density variations (e.g., porous soil or ice versus solid rock) are relatively easy to detect. The intrinsic spatial resolution of muon radiography (muography) is on the scale of a few meters. The spatial resolution that can be achieved in practice depends on signal intensity and integration time (counting statistics), the angular resolution of the muon tracker (hodoscope) and details of data reduction and analysis methodology. Our Phase II project will assess remaining unknowns for the application of muography to determining the interior structure of SSBs, assess risks for implementation, and provide a roadmap for development of SSB muography beyond the NIAC program. To achieve our objectives, we will focus on four interrelated tasks: Task1) Signal and background characterization: Characterize the production and transmission of muons and secondary particle backgrounds made by cosmic ray showers in SSBs; and near-surface features from radiographic and tomographic data; Task2) Imaging studies: Develop methods to determine the density structure of SSB interiors and near-surface features from radiographic and tomographic data; Task3) Instrument design: Using simulations and bench-top laboratory experiments, investigate specific concepts for the design of compact hodoscopes and components; Task4) Synthesis: Combine the results of the first three tasks to determine the range of applicability of the method, identify the steps needed for maturation of the concept, and explore concepts for a pilot muography mission

Towards a better understanding of sensory substitution: the theory and practice of developing visual-to-auditory sensory substitution devices

Visual impairment is a global and potentially devastating affliction. Sensory substitution devices have the potential to lessen the impact of blindness by presenting vision via another modality. The chief motivation behind each of the chapters that follow is the production of more useful sensory substitution devices. The first empirical chapter (chapter two) demonstrates the use of interactive genetic algorithms to determine an optimal set of parameters for a sensory substitution device based on an auditory encoding of vision (“the vOICe”). In doing so, it introduces the first version of a novel sensory substitution device which is configurable at run-time. It also presents data from three interactive genetic algorithm based experiments that use this new sensory substitution device. Chapter three radically expands on this theme by introducing a general purpose, modular framework for developing visual-to-auditory sensory substitution devices (“Polyglot”). This framework is the fuller realisation of the Polyglot device introduced in the first chapter and is based on the principle of End-User Development (EUD). In chapter four, a novel method of evaluating sensory substitution devices using eye-tracking is introduced. The data shows both that the copresentation of visual stimuli assists localisation and that gaze predicted an auditory target location more reliably than the behavioural responses. Chapter five explores the relationship between sensory substitution devices and other tools that are used to acquire real-time sensory information (“sensory tools”). This taxonomy unites a range of technology from telescopes and cochlear implants to attempts to create a magnetic sense that can guide further research. Finally, in chapter six, the possibility of representing colour through sound is explored. The existence of a crossmodal correspondence between (equi-luminant) hue and pitch is documented that may reflect a relationship between pitch and the geometry of visible colour space

Computer Generation of Integral Images using Interpolative Shading Techniques

Research to produce artificial 3D images that duplicates the human stereovision has been ongoing for hundreds of years. What has taken millions of years to evolve in humans is proving elusive even for present day technological advancements. The difficulties are compounded when real-time generation is contemplated. The problem is one of depth. When perceiving the world around us it has been shown that the sense of depth is the result of many different factors. These can be described as monocular and binocular. Monocular depth cues include overlapping or occlusion, shading and shadows, texture etc. Another monocular cue is accommodation (and binocular to some extent) where the focal length of the crystalline lens is adjusted to view an image. The important binocular cues are convergence and parallax. Convergence allows the observer to judge distance by the difference in angle between the viewing axes of left and right eyes when both are focussing on a point. Parallax relates to the fact that each eye sees a slightly shifted view of the image. If a system can be produced that requires the observer to use all of these cues, as when viewing the real world, then the transition to and from viewing a 3D display will be seamless. However, for many 3D imaging techniques, which current work is primarily directed towards, this is not the case and raises a serious issue of viewer comfort. Researchers worldwide, in university and industry, are pursuing their approaches in the development of 3D systems, and physiological disturbances that can cause nausea in some observers will not be acceptable. The ideal 3D system would require, as minimum, accurate depth reproduction, multiviewer capability, and all-round seamless viewing. The necessity not to wear stereoscopic or polarising glasses would be ideal and lack of viewer fatigue essential. Finally, for whatever the use of the system, be it CAD, medical, scientific visualisation, remote inspection etc on the one hand, or consumer markets such as 3D video games and 3DTV on the other, the system has to be relatively inexpensive. Integral photography is a ‘real camera’ system that attempts to comply with this ideal; it was invented in 1908 but due to technological reasons was not capable of being a useful autostereoscopic system. However, more recently, along with advances in technology, it is becoming a more attractive proposition for those interested in developing a suitable system for 3DTV. The fast computer generation of integral images is the subject of this thesis; the adjective ‘fast’ being used to distinguish it from the much slower technique of ray tracing integral images. These two techniques are the standard in monoscopic computer graphics whereby ray tracing generates photo-realistic images and the fast forward geometric approach that uses interpolative shading techniques is the method used for real-time generation. Before this present work began it was not known if it was possible to create volumetric integral images using a similar fast approach as that employed by standard computer graphics, but it soon became apparent that it would be successful and hence a valuable contribution in this area. Presented herein is a full description of the development of two derived methods for producing rendered integral image animations using interpolative shading. The main body of the work is the development of code to put these methods into practice along with many observations and discoveries that the author came across during this task.The Defence and Research Agency (DERA), a contract (LAIRD) under the European Link/EPSRC photonics initiative, and DTI/EPSRC sponsorship within the PROMETHEUS project

Virtual Reality Games for Motor Rehabilitation

This paper presents a fuzzy logic based method to track user satisfaction without the need for devices to monitor users physiological conditions. User satisfaction is the key to any product’s acceptance; computer applications and video games provide a unique opportunity to provide a tailored environment for each user to better suit their needs. We have implemented a non-adaptive fuzzy logic model of emotion, based on the emotional component of the Fuzzy Logic Adaptive Model of Emotion (FLAME) proposed by El-Nasr, to estimate player emotion in UnrealTournament 2004. In this paper we describe the implementation of this system and present the results of one of several play tests. Our research contradicts the current literature that suggests physiological measurements are needed. We show that it is possible to use a software only method to estimate user emotion

Reconstruction algorithms for multispectral diffraction imaging

Thesis (Ph.D.)--Boston UniversityIn conventional Computed Tomography (CT) systems, a single X-ray source spectrum is used to radiate an object and the total transmitted intensity is measured to construct the spatial linear attenuation coefficient (LAC) distribution. Such scalar information is adequate for visualization of interior physical structures, but additional dimensions would be useful to characterize the nature of the structures. By imaging using broadband radiation and collecting energy-sensitive measurement information, one can generate images of additional energy-dependent properties that can be used to characterize the nature of specific areas in the object of interest. In this thesis, we explore novel imaging modalities that use broadband sources and energy-sensitive detection to generate images of energy-dependent properties of a region, with the objective of providing high quality information for material component identification. We explore two classes of imaging problems: 1) excitation using broad spectrum sub-millimeter radiation in the Terahertz regime and measure- ment of the diffracted Terahertz (THz) field to construct the spatial distribution of complex refractive index at multiple frequencies; 2) excitation using broad spectrum X-ray sources and measurement of coherent scatter radiation to image the spatial distribution of coherent-scatter form factors. For these modalities, we extend approaches developed for multimodal imaging and propose new reconstruction algorithms that impose regularization structure such as common object boundaries across reconstructed regions at different frequencies. We also explore reconstruction techniques that incorporate prior knowledge in the form of spectral parametrization, sparse representations over redundant dictionaries and explore the advantage and disadvantages of these techniques in terms of image quality and potential for accurate material characterization. We use the proposed reconstruction techniques to explore alternative architectures with reduced scanning time and increased signal-to-noise ratio, including THz diffraction tomography, limited angle X-ray diffraction tomography and the use of coded aperture masks. Numerical experiments and Monte Carlo simulations were conducted to compare performances of the developed methods, and validate the studied architectures as viable options for imaging of energy-dependent properties

NASA Tech Briefs, February 1996

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