arXiv subjects

Rudi Cloots

Publications and source records attributed to Rudi Cloots.

7 recordsLinked to original sources

arXiv2026

Towards Athlete Fatigue Assessment from Association Football Videos

Fatigue monitoring is central in association football due to its links with injury risk and tactical performance. However, objective fatigue-related indicators are commonly derived from subjective self-reported metrics, biomarkers derived from laboratory tests, or, more recently, intrusive sensors such as heart monitors or GPS tracking data. This paper studies whether monocular broadcast videos can provide spatio-temporal signals of sufficient quality to support fatigue-oriented analysis. Building on state-of-the-art Game State Reconstruction methods, we extract player trajectories in pitch coordinates and propose a novel kinematics processing algorithm to obtain temporally consistent speed and acceleration estimates from reconstructed tracks. We then construct acceleration--speed (A-S) profiles from these signals and analyze their behavior as fatigue-related performance indicators. We evaluate the full pipeline on the public SoccerNet-GSR benchmark, considering both 30-second clips and a complete 45-minute half to examine short-term reliability and longer-term temporal consistency. Our results indicate that monocular GSR can recover kinematic patterns that are compatible with A-S profiling while also revealing sensitivity to trajectory noise, calibration errors, and temporal discontinuities inherent to broadcast footage. These findings support monocular broadcast video as a low-cost basis for fatigue analysis and delineate the methodological challenges for future research.

cs.CV↗

arXiv2024

Plasmonic properties of electrochromic doped metal oxides investigated through Kubelka Munk formalism

Materials with broadband tunable optical properties are looked for in smart windows applications. Doped metal oxides presenting dual band visible (VIS) near infrared (NIR) electrochromic properties can be used for solving such a challenge, and their accurate optical characterization is therefore of prime importance. Kubelka Munk model is a state of the art way to optically quantify the absorption properties of materials and is occasionally applied to plasmonic materials, even if great care should be taken to meet the formalism hypotheses. In the present work, Kubelka Munk theory is discussed in the context of particles of indium tin oxide and molybdenum tungsten oxide formulations that are used as single NIR and both VIS and NIR active advanced electrochromic materials, respectively. An analytical model is derived for particles of much smaller dimensions than the incident wavelength and is experimentally verified. A dilution method is applied to verify the plasmonic characteristics of the particles. This study is key for efficient characterization of optical properties of metal oxides, and plasmonic materials in general, from diffuse reflectance measurements.

physics.optics↗

arXiv2014

Ranking structures and Rank-Rank Correlations of Countries. The FIFA and UEFA cases

Ranking of agents competing with each other in complex systems may lead to paradoxes according to the pre-chosen different measures. A discussion is presented on such rank-rank, similar or not, correlations based on the case of European countries ranked by UEFA and FIFA from different soccer competitions. The first question to be answered is whether an empirical and simple law is obtained for such (self-) organizations of complex sociological systems with such different measuring schemes. It is found that the power law form is not the best description contrary to many modern expectations. The stretched exponential is much more adequate. Moreover, it is found that the measuring rules lead to some inner structures, in both cases.

physics.soc-ph↗

arXiv2010

Structural and Magnetic Properties of Nanosized Barium Hexaferrite Powders Obtained by Microemulsion Technique

Thin hexagonal barium hexaferrite particles synthesized using the microemulsion technique were studied. A water-in-oil reverse microemulsion system with cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, n-butanol as a co-surfactant, n-hexanol as a continuous oil phase, and an aqueous phase were used. The microstructural and magnetic properties were investigated. The particles obtained were mono-domain with average particle size 280 nm. The magnetic properties of the powder were investigated at 4.2 K and at room temperature. The saturation magnetization was 48.86 emu/g and the coercivity, 2.4 x 105 A/m at room temperature. The anisotropy field Ha and magneto-crystalline anisotropy K1 were 1.4 x 106 A/m and 2.37 x 105 J/m3, respectively.

cond-mat.mtrl-sci↗

arXiv2007

Magnetic shielding properties of high-temperature superconducting tubes subjected to axial fields

We have experimentally studied the magnetic shielding properties of a cylindrical shell of BiPbSrCaCuO subjected to low frequency AC axial magnetic fields. The magnetic response has been investigated as a function of the dimensions of the tube, the magnitude of the applied field and the frequency. These results are explained quantitatively by employing the method of Brandt (1998 Phys. Rev. B 58 6506) with a Jc(B) law appropriate for a polycrystalline material. Specifically, we observe that the applied field can sweep into the central region either through the thickness of the shield or through the opening ends, the latter mechanism being suppressed for long tubes. For the first time, we systematically detail the spatial variation of the shielding factor (the ratio of the applied field over the internal magnetic field) along the axis of a high-temperature superconducting tube. The shielding factor is shown to be constant in a region around the centre of the tube, and to decrease as an exponential in the vicinity of the ends. This spatial dependence comes from the competition between two mechanisms of field penetration. The frequency dependence of the shielding factor is also discussed and shown to follow a power law arising from the finite creep exponent n.

cond-mat.supr-con↗

arXiv2006

Effect of Ga doping on magnetotransport properties in collosal magnetoresistive La0.7Ca0.3Mn1-xGaxO3 (0 < x < 0.1)

Samples of La0.7Ca0.3Mn1-xGaxO3 with x = 0, 0.025, 0.05 and 0.10 were prepared by standard solid-state reaction. They were first characterized chemically, including the microstructure. The magnetic properties and various transport properties, i.e. the electrical resistivity, magnetoresistivity (for a field below 8T), thermoelectric power and thermal conductivity measured each time on the same sample, are reported. The markedly different behavior of the x = 0.1 sample from those with a smaller Ga content, is discussed. The dilution of the Mn3+/Mn4+ interactions with Ga doping considerably reduces the ferromagnetic double exchange interaction within the manganese lattice leading to a decrease of the Curie temperature. The polaron binding energy varies from 224 to 243 meV with increased Ga doping.

cond-mat.str-el↗

arXiv2004

Multiscale Modeling of Peritectic Reaction Growth

Peritectic growth of bulk superconducting cuprate perovskite, like YBa2Cu3O7-x has been studied. The microstructure features are recalled. The simplest model giving the best description of the microstructure complexity at the mesoscopic scale is an Eden model adapted to chemical reactions. A repulsive dynamical interaction between the front and the solid 211 particles, rejected by the solidifying matrix, is also taken into account. A growth probability-with chemical reaction and pushing-transfer matrix method is developed. The simulations put into evidence the effect of the initial 211 size distribution on the microstructure.

cond-mat.mtrl-sci↗