Tilt Of Rotation Axis Research Articles

Research of the elastic properties of a vehicle tire with an tilting wheel rotation axis

The purpose of the study is to develop computational and experimental methods for determining the normal, longitudinal and lateral stiffness of a vehicle tire with an inclined rotation wheel axis. Dimensionless correction factors were obtained to adjust the tire stiffness along the corresponding coordinate when the wheel rotation axis is tilted. It has been established that when the wheel rotation axis is tilted, the tire stiffness changes along different coordinates in different ways. It has been determined that the normal and longitudinal tire stiffness when the wheel rotation axis is tilted always decreases, regardless of the tilt direction. A change in the lateral tire stiffness when the wheel rotation axis is tilted can occur either in the direction of decrease or increase, depending on the combination of the tilt direction and the vector of the wheel lateral force. Keywords vehicle support wheel, rotation axis tilt, tire elastic properties, methods for determining

Solar Polar Magnetic Fields: Comparing Full-disk and High-resolution Spectromagnetograph Data

This is the first systematic comparison between photospheric polar magnetic field data from a full-disk synoptic observing program, the National Solar Observatory’s Synoptic Optical Long-term Investigations of the Sun Vector Spectromagnetograph (SOLIS/VSM), and a high-resolution vector spectromagnetograph, the Hinode Solar Optical Telescope Spectropolarimeter (SOT/SP). Polar magnetic fluxes derived from longitudinal magnetic field measurements from both telescopes and from SOT/SP full-Stokes vector data are all compared in the form of polar synoptic maps. Measurements taken over 35 day periods with advantageous rotation axis tilt angle are used; observations extend to the poles, and no synthetic pole-filling is needed. Polar fluxes are derived from longitudinal data assuming an approximately radial field, whereas those derived from vector data are based on measured vector magnitude and direction. However, the full-vector measurements may have a detection problem: polar fields are observed as mostly transverse from (near) Earth, and Zeeman sensitivity to transverse fields is significantly lower than for longitudinal fields. Accordingly, the SOT/SP vector-based polar fluxes are lower than the longitudinal-based fluxes from both telescopes, a result driven by pixels without sufficient Q and U signals for the full-Stokes inversions to detect significant radial field but with good Stokes V signal implying a significant field. Furthermore, the SOT/SP longitudinal-based fluxes are significantly higher than their VSM counterparts because of superior seeing-free spatial resolution and longer observation time. The SOT/SP longitudinal-based polar fluxes appear large enough to account for radial interplanetary field measurements whereas the SOT/SP vector-based and the VSM ones are generally too low.

Thermal Noise Decoupling of Micro-Newton Thrust Measured in a Torsion Balance

The space gravitational wave detection and drag free control requires the micro-thruster to have ultra-low thrust noise within 0.1 mHz–0.1 Hz, which brings a great challenge to calibration on the ground because it is impossible to shield any spurious couplings due to the asymmetry of torsion balance. Most thrusters dissipate heat during the test, making the rotation axis tilt and components undergo thermal drift, which is hysteretic and asymmetric for micro-Newton thrust measurement. With reference to LISA’s research and coming up with ideas inspired from proportional-integral-derivative (PID) control and multi-timescale (MTS), this paper proposes to expand the state space of temperature to be applied on the thrust prediction based on fine tree regression (FTR) and to subtract the thermal noise filtered by transfer function fitted with z-domain vector fitting (ZDVF). The results show that thrust variation of diurnal asymmetry in temperature is decoupled from 24 μN/Hz1/2 to 4.9 μN/Hz1/2 at 0.11 mHz. Additionally, 1 μN square wave modulation of electrostatic force is extracted from the ambiguous thermal drift background of positive temperature coefficient (PTC) heater. The PID-FTR validation is performed with experimental data in thermal noise decoupling, which can guide the design of thermal control and be extended to other physical quantities for noise decoupling.

New constraints on the chemical composition and outgassing of 67P/Churyumov-Gerasimenko

Strong heterogeneities in the composition of the volatile species have been detected in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) by the ROSINA instrument onboard the ESA’s Rosetta spacecraft. However, it is not clear if these heterogeneities are indicative of heterogeneities in the near-surface nucleus composition or if the coma composition is mainly insolation-driven. In order to clarify the link between the composition of the nucleus and the composition of the coma we have performed numerical simulations and compare our results with measurements acquired by ROSINA/DFMS for three major volatile species namely, H2O, CO2, and CO. We use a previously published thermo-physical numerical model designed to study cometary nucleus evolution, including volatile outgassing and internal stratigraphy, as the comet orbits the Sun. The model follows schemes used for much of the past three decades to model cometary outgassing. Our results match well the experimental volatiles density measurements of ROSINA/DFMS for most of the Rosetta mission. They suggest that the outgassing pattern is mainly insolation-driven and the variations are caused by the tilt of rotation axis and eccentricity of the nucleus. The nucleus shows to 1st order a homogeneous composition and therefore we can provide constraints on the bulk volatiles composition of 67P/C-G nucleus which is dominated by H2O (91.4% ​± ​4.5%), then CO2 (6.7% ​± ​3.5%) and CO in small amount (1.9% ​± ​1.2%). However, in details, a dichotomy in composition between the northern and southern hemispheres of the comet is revealed. A CO/CO2 bulk composition ratio of about 0.6 ​± ​0.1 is required to reproduce the measurements from the northern hemisphere and about 0.2 ​± ​0.1 for the southern hemisphere. To match the data, the thermal properties of the nucleus surface must be modified by adding a thin desiccated dust mantle (~5 ​mm) for northern latitudes while this appears not to be necessary for southern latitudes. This may be related to the observed dichotomy in putative airfall deposits. We suspect that, because of thermal inertia, seasonally non-illuminated areas continue to outgas and influence the ROSINA measurements. This effect cannot be reproduced with the model. Therefore during some periods of the mission, the fits are not ideal. Finally, the outgassing of the different ices leads to a layered internal structure defined by the sublimation front of each ice and formation of harder layers close to the surface due to sublimation/condensation processes. However, the thermo-physical model overestimates the absolute volatiles production (mainly in the southern hemisphere) leading to an overestimation of the erosion rates. Further investigations will be performed to improve the thermo-physical model and the sensitivity analysis.

The Tendencies of Change of the Incoming Solar Radiation to the Upper Atmosphere Boundary and Their Spatial Localization

Satellite-based measurements of the total flow of incoming solar radiation arriving at the Earth (total solar irradiance (TSI)) have been carried out since 1977. By now, a continuous series of variations of the TSI is obtained. The 11-year cycle and its amplitude in multiyear variations of solar radiation are revealed. However, two mechanisms having different physical nature are defined in regulation of the incoming solar radiation to the Earth (with the atmosphere not accounted for), and in its distribution over the Earth surface (solar climate of the Earth). One mechanism is related to the variation in solar activity. Another mechanism is defined by celestial-mechanical processes, which alter the orbit elements of the Earth (Earth–Sun distance, duration of the tropical year, etc.), the Earth rotation axis tilt, and the relevant variations in the Earth’s insolation. The performed calculations of the insolation related to the celestial-mechanical processes were used as a basis for differentiating the satellite observational data on the changes of the TSI with respect to the mechanisms of different physical nature. It was made possible to estimate the contributions of the variation in solar activity and of the celestial-mechanical processes to the total incoming solar radiation.

Rotational test of an integrated magnetic bearing using multiple HTS cubic bulk units

For magnetic bearings combining multiple cubic superconducting bulks, placement is a crucial factor. In this paper, the magnetic bearing surface constructed by arrangement optimization was composed of eight superconducting cubic bulk units. The combined arrangement of cubic superconducting bulks was determined by optimizing the spatial uniformity of the magnetic bearing's trapped magnetic flux distribution. We constructed a physical model in which a permanent magnet in the form of a floating rotor was sandwiched from above and below by an integrated magnetic bearing surface. Using rotation test equipment and an encoder, we investigated the influence of an optimal arrangement index on rotation loss that occurs due to magnetic flux distribution nonuniformity. In addition, the rotation axis tilt angle due to nonuniform magnetic flux distribution was measured using a laser displacement meter. The advantage of the method proposed in this research is that the magnetic distribution can be controlled optimally depending on the arrangement of the cubic bulk when it is incorporated in various bulk applications, not limited to SMB.

Demonstration of the Google Earth as a Tool in Learning the Earth Physics

Earth Physics is a course at the Physics Education Program Study, University of Riau, Indonesia. The problem facing by students were the student commonly not able to imagine the rotation effect and the tilt of rotation axis to some phenomenon. Furthermore the students were difficult to imagine the subduction zone of two tectonic plates. This study was demonstrate some assignments to the student regarding the use Google Earth in the learning the earth physically. In this study, a total of 38 students were chosen to use the Google Earth as an interactive learning media. To demonstrate the Google Earth in the learning process, several assignments have been given to the students. The first was to compare the distance measurement manually and through Google Earth. The second demonstration was to define some selected areas. The third was to demonstrate the tilt axis of rotation effect on the earth. The last was a mini project to demonstrate the use of Google Earth in imagine of the subduction of two tectonic plates. The result shows that mostly students (92%) were able to reconstruction the process involved in the assignment although a few of them cannot explain well. Whilst, 8% of the student were still difficult to reconstruction the process involved in the assignment, although they can submit all the assignments with fairly well. Finally, the Google Earth is generally success used in the demonstration of earth physics subject learning media.

The Determination of Rotation Axis in the Rotation Electron Diffraction Technique

Methods to determine the rotation axis using the rotation electron diffraction technique are described. A combination of rotation axis tilt, beam tilt, and simulated experimental diffraction patterns with nonintegers zone axis has been used. Accurate knowledge of the crystallographic direction of the incident beam for deducing the excitation error of reflections simultaneously near Bragg positions is essential in quantitative electron diffraction. Experimental patterns from CoP₃ are used as examples.

Modeling seasonal and diurnal effects on ionospheric conductances, region-2 currents, and plasma convection in the inner magnetosphere

[1] The present study focuses on a modeling of the seasonal and diurnal effects on the dynamics of the coupled magnetosphere-ionosphere system under different solar illumination conditions, to try to reproduce some of the observations concerning the region 2 (R2) field-aligned currents (FAC). This is performed by introducing in the Ionosphere Magnetosphere Model (IMM) the Earth's rotation axis tilt, the dipole axis tilt and an eccentric dipole. The simulated patterns of the R2 FAC agree rather well with the observations. In particular the dayside FAC density is two times greater in the summer hemisphere than in the winter one. The results show that seasonal tilt of the dipole axis affects the distributions of the Pedersen conductances and FAC by 28.5–52.8% and do not have much influence on the distribution of the magnetospheric plasma, which is modified by only 0.9–3.9%. The diurnal variations induced by the tilt of the dipole axis are of the same order of magnitude, 5.5–29% for the Pedersen conductances and FAC and 0.4–7.1% for the magnetospheric plasma. They modulate the interhemispheric asymmetry of the FAC by 26–59%. The eccentric dipole induces an increase (decrease) of the daily variations of the conductances and the FAC by a factor 1.2–2.3 in the Southern (Northern) Hemisphere, irrespective of the season, which contributes to increase the asymmetry between the two hemispheres. This results in an increase of the daily variations of the ion maximum pressure and of the electron maximum energy flux at the December solstice and at the March and September equinoxes, but a decrease at the June solstice. The maximal variation of the magnetospheric plasma distribution amounts to 6.7% at December solstice. These results underline the importance of considering the three different effects at the same time.

Otolith-semicircular canal interaction during postrotatory nystagmus in humans.

The otolith-semicircular canal interaction during postrotatory nystagmus was studied in ten normal human subjects by applying fast, short-lasting, passive head and body tilts (15, 30, 45, or 90 degrees in the roll or pitch plane) 2 s after sudden stop from a constant-velocity rotation (100 degrees/s) about the earth-vertical axis in yaw. Eye movements were measured with three-dimensional magnetic search coils. Following the head tilt, activity in the semicircular canal primary afferents continues to reflect the postrotatory angular velocity vector in head-centered coordinates, whereas otolith primary afferents signal a different orientation of the head relative to gravity. Despite the change in head orientation relative to gravity, postrotatory eye velocity decayed closely along the axis of semicircular canal stimulation (horizontal in head coordinates) for large head tilts (90 degrees) and also for small head tilts (15-45 degrees) for reorientations in the pitch plane. Only for small head tilts (15-45 degrees) in the roll plane was there a reorientation of the eye rotation axis toward the gravitational vector. This reorientation was approximately compensatory for 15 degrees head tilts. For 30 degrees and 45 degrees head tilts the eye rotation axis tilted toward the gravitational vector by about the same amount as for 15 degrees head tilts. These results suggest that, with the exception of small head tilts in the roll plane, there was no compelling data showing a relationship between the eye rotation axis and head tilt and that postrotatory nystagmus is largely organized in head-centered rather than gravity-centered coordinates in humans. This indicates a rudimentary, nonlinear, and direction-specific interaction of semicircular canal and otolith signals in the central vestibular system in humans.