arXiv subjects

David Ceddia

Publications and source records attributed to David Ceddia.

5 recordsLinked to original sources

arXiv2025

Mathematical Modelling and Optimisation of Athletic Performance: Tapering and Periodisation

We conduct a mathematical optimization of the training impulse profile to maximize performance for two seminal athletic performance models: the Banister et al. (1975) Fitness--Fatigue Impulse Response Model and the Busso (2003) Variable Dose--Response Model. We discuss discrepancies in both the quantitative and qualitative aspects of the optimized training impulse profiles compared to what is physically plausible and relative to common training practices recommended in the empirical sports science literature, such as periodization and tapering. We analytically prove that, under the Banister formulation, the optimal training strategy always consists of sustained maximal training, followed by the complete cessation of training prior to the prioritized performance date, and therefore does not yield periodization, or tapering beyond this trivial form. This highlights a gap between theoretical prediction and empirically supported practice, underscoring the need for models that incorporate additional physiological effects. We then propose a set of illustrative and interpretable nonlinear modifications in the magnitude and time response to training in the Fitness--Fatigue Impulse Response model such that the optimized training impulse profile demonstrates these qualities.

q-bio.QM↗

arXiv2023

Universal mask for hard X rays

The penetrating power of X rays underpins important applications such as medical radiography. However, this same attribute makes it challenging to achieve flexible on-demand patterning of X-ray beams. One possible path to this goal is ``ghost projection'', a method which may be viewed as a reversed form of classical ghost imaging. This technique employs multiple exposures, of a single illuminated non-configurable mask that is transversely displaced to a number of specified positions, to create any desired pattern. An experimental proof-of-concept is given for this idea, using hard X rays. The written pattern is arbitrary, up to a tunable constant offset, and its spatial resolution is limited by both (i) the finest features present in the illuminated mask and (ii) inaccuracies in mask positioning and mask exposure time. In principle, the method could be used to make a universal lithographic mask in the hard-X-ray regime. Ghost projection might also be used as a dynamically-configurable beam-shaping element, namely the hard-X-ray equivalent of a spatial light modulator. The underpinning principle can be applied to gamma rays, neutrons, electrons, muons, and atomic beams. Our flexible approach to beam shaping gives a potentially useful means to manipulate such fields.

eess.IV↗

arXiv2022

Ghost projection. II. Beam shaping using realistic spatially-random masks

Spatial light modulation is important for many scientific and industrial applications. The spatial light modulator and optical data projector both rely on precisely configurable optical elements to shape a light beam. Here we explore an image-projection approach which does not require a configurable beam-shaping element. We term this approach ghost projection on account of its conceptual relation to computational ghost imaging. Instead of a configurable beam shaping element, the method transversely displaces a single illuminated mask, such as a spatially-random screen, to create specified distributions of radiant exposure. The method has potential applicability to image projection employing a variety of radiation and matter wave fields, such as hard x rays, neutrons, muons, atomic beams and molecular beams. Building on our previous theoretical and computational studies, we here seek to understand the effects, sensitivity, and tolerance of some key experimental limitations of the method. Focusing on the case of hard x rays, we employ experimentally acquired masks to numerically study the deleterious effects of photon shot noise, inaccuracies in random-mask exposure time, and inaccuracies in mask positioning, as well as adapting to spatially non-uniform illumination. Understanding the influence of these factors will assist in optimizing experimental design and work towards achieving ghost projection in practice.

eess.IV↗

arXiv2021

Ghost Projection

Ghost imaging is a developing imaging technique that employs random masks to image a sample. Ghost projection utilizes ghost-imaging concepts to perform the complementary procedure of projection of a desired image. The key idea underpinning ghost projection is that any desired spatial distribution of radiant exposure may be produced, up to an additive constant, by spatially-uniformly illuminating a set of random masks in succession. We explore three means of achieving ghost projection: (i) weighting each random mask, namely selecting its exposure time, according to its correlation with a desired image, (ii) selecting a subset of random masks according to their correlation with a desired image, and (iii) numerically optimizing a projection for a given set of random masks and desired image. The first two protocols are analytically tractable and conceptually transparent. The third is more efficient but less amenable to closed-form analytical expressions. A comparison with existing image-projection techniques is drawn and possible applications are discussed. These potential applications include: (i) a data projector for matter and radiation fields for which no current data projectors exist, (ii) a universal-mask approach to lithography, (iii) tomographic volumetric additive manufacturing, and (iv) a ghost-projection photocopier.

eess.IV↗

arXiv2018

On Random-Matrix Bases, Ghost Imaging and X-ray Phase Contrast Computational Ghost Imaging

A theory of random-matrix bases is presented, including expressions for orthogonality, completeness and the random-matrix synthesis of arbitrary matrices. This is applied to ghost imaging as the realization of a random-basis reconstruction, including an expression for the resulting signal-to-noise ratio. Analysis of conventional direct imaging and ghost imaging leads to a criterion which, when satisfied, implies reduced dose for computational ghost imaging. We also propose an experiment for x-ray phase contrast computational ghost imaging, which enables differential phase contrast to be achieved in an x-ray ghost imaging context. We give a numerically robust solution to the associated inverse problem of decoding differential phase contrast x-ray ghost images, to yield a quantitative map of the projected thickness of the sample.

eess.IV↗