Forced Resonance Orbit Analysis of Binary Asteroid System

The solar radiation pressure becomes one of the major perturbations to orbits in the study of binary asteroid system, since asteroids have relatively weak gravity fields. In this paper, based on the idea of treating the solar radiation pressure as periodic external excitation, one novel family of orbits due to primary resonance and another novel family of orbits due to both primary resonance and internal resonance have been found by the classical perturbation method. The two types of steady-state orbits due to external resonance with different area-to-mass ratios have been determined and discussed by the frequency-response equations. Five binary asteroid systems, 283 Emma-S/2003 (283) 1, 22 Kalliope-Linus, 31 Euphrosyne-S/2019 (31) 1, 2006 Polonskaya-S/2005 (2006) 1 and 4029 Bridges have been taken as examples to show the validity of the proposed mechanism in the explanation of orbits formation due to resonance.

Experimental Investigation of Aerostatic Journal Bearings made of Carbon Fiber-Reinforced Carbon Composites

This study describes experimental results using carbon fiber-reinforced carbon (C/C) material for porous journal bearings under static conditions. Exerted radial forces of up to 90 N, a supply pressure of up to 6 bar and a maximum rotational speed of 8000 rpm were tested. The occurrence of pneumatic hammering was not observed under these operating points. Triangulation sensors were mounted vertically and horizontally as well as in front of and behind the tested bearing. These sensors measure eccentricity and misalignment. The orbit analysis demonstrated an improvement in concentricity with an increment in the supply pressure. The layered structure of the C/C material used for the porous liner is presented. A rotational speed below 8000 rpm negligibly influenced the load-carrying capacity and the flow rate. The vertical misalignment of the shaft was determined in relation to the force-applied test bearing to the shaft. In addition, two vertically positioned sensors on the support-bearing housing were used to discern the misalignment in the absolute system. On the other hand, reducing the speed to 1000 rpm increased the concentricity error. The shaft showed no significant signs of use after the experiments. The measurements confirm the suitability of the material for porous bearings.

Analysing nystagmus waveforms: a computational framework

We present a new computational approach to analyse nystagmus waveforms. Our framework is designed to fully characterise the state of the nystagmus, aid clinical diagnosis and to quantify the dynamical changes in the oscillations over time. Both linear and nonlinear analyses of time series were used to determine the regularity and complexity of a specific homogenous phenotype of nystagmus. Two-dimensional binocular eye movement recordings were carried out on 5 adult subjects who exhibited a unilateral, uniplanar, vertical nystagmus secondary to a monocular late-onset severe visual loss in the oscillating eye (the Heimann-Bielschowsky Phenomenon). The non-affected eye held a central gaze in both horizontal and vertical planes (± 10 min. of arc). All affected eyes exhibited vertical oscillations, with mean amplitudes and frequencies ranging from 2.0°–4.0° to 0.25–1.5 Hz, respectively. Unstable periodic orbit analysis revealed only 1 subject exhibited a periodic oscillation. The remaining subjects were found to display quasiperiodic (n = 1) and nonperiodic (n = 3) oscillations. Phase space reconstruction allowed attractor identification and the computation of a time series complexity measure—the permutation entropy. The entropy measure was found to be able to distinguish between a periodic oscillation associated with a limit cycle attractor, a quasiperiodic oscillation associated with a torus attractor and nonperiodic oscillations associated with higher-dimensional attractors. Importantly, the permutation entropy was able to rank the oscillations, thereby providing an objective index of nystagmus complexity (range 0.15–0.21) that could not be obtained via unstable periodic orbit analysis or attractor identification alone. These results suggest that our framework provides a comprehensive methodology for characterising nystagmus, aiding differential diagnosis and also permitting investigation of the waveforms over time, thereby facilitating the quantification of future therapeutic managements. In addition, permutation entropy could provide an additional tool for future oculomotor modelling.

A DFT-BASED ANALYSIS OF ADSORPTION PERFORMANCE OF CU2+ AND ZN2+ ON DEFECTIVE GRAPHENE FOR THE APPLICATION OF POLLUTING METAL IONS TREATMENT

The density functional theory has been used to study the adsorption performance of polluting Cu[Formula: see text] and Zn[Formula: see text] ions on defective graphene. Compared to intrinsic graphene, the adsorption distance between defective graphene and Cu[Formula: see text]/Zn[Formula: see text] decreases greatly, and the adsorption energy and charge transfer amount increases significantly. The calculation of charge density demonstrates that clear hybridization happens between defective graphene and Cu[Formula: see text]/Zn[Formula: see text] ions, suggesting the formation of chemical adsorption. The frontier orbit analysis shows that defective graphene has greater electrical sensitivity after adsorbing Cu[Formula: see text]/Zn[Formula: see text] ions. Therefore, defective graphene could be a potential material for the treatment of contaminating heavy metal ions.

Using commensurabilities and orbit structure to understand barred galaxy evolution

ABSTRACT We interpret simulations of secularly evolving disc galaxies through orbit morphology. Using a new algorithm that measures the volume of orbits in real space using a tessellation, we rapidly isolate commensurate (resonant) orbits. We identify phase-space regions occupied by different orbital families. Compared to spectral methods, the tessellation algorithm can identify resonant orbits within a few dynamical periods, crucial for understanding an evolving galaxy model. The flexible methodology accepts arbitrary potentials, enabling detailed descriptions of the orbital families. We apply the machinery to four different potential models, including two barred models, and fully characterize the orbital membership. We identify key differences in the content of orbit families, emphasizing the presence of orbit families indicative of the bar evolutionary state and the shape of the dark matter halo. We use the characterization of orbits to investigate the shortcomings of analytic and self-consistent studies, comparing our findings to the evolutionary epochs in self-consistent barred galaxy simulations. Using insight from our orbit analysis, we present a new observational metric that uses spatial and kinematic information from integral field spectrometers that may reveal signatures of commensurabilities and allow for a differentiation between models.