Angular Rotation Research Articles

Вековое геодезическое вращение небесных тел в системе спутников Юпитера

This article studies the relativistic effect of geodetic precession in the rotation around their axes of Jupiter and its 94 satellites for which ephemerides are known. As a result, the most significant secular terms of the geodetic rotation of these celestial bodies were determined for the first time: 1. for Jupiter relative to the barycenter of the Solar System and the plane of the mean orbit of Jupiter at the epoch J2000.0 in Euler angles, in the perturbing terms of physical libration and in the absolute value of the vector of angular rotation of the geodetic rotation of the body under study; 2. for 8 regular (4 inner (Metis J16, Adrastea J15, Amalthea J5 and Thebe J14)) and 4 Galilean (Io J1, Europa J2, Ganymede J3 and Callisto J4))) satellites of Jupiter relative to: a) the barycenter of the Solar system and the plane of the mean orbit of the satellite under study at epoch J2000.0 in Euler angles, in the perturbing terms of the physical libration and in the absolute value of the vector of angular rotation of the geodetic rotation of the body under study; b) the barycenter of the Solar system and the plane of the mean orbit of the barycenter of the Jovian system at epoch J2000.0 in Euler angles, in the perturbing terms of the physical libration and in the absolute value of the vector of angular rotation of the geodetic rotation of the body under study; c) the barycenter of the Jupiter satellite system and the plane of the mean orbit of the studied satellite of the J2000.0 epoch in the perturbing terms of the physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the studied body; 3. for 86 irregular satellites (J6–J13, J17–J72, J5501–J5507, J5509–J5523) of Jupiter relative to: a) the barycenter of the Solar system in the absolute value of the angular rotation vector of the geodetic rotation of the studied body; b) the barycenter of the Jupiter satellite system in the absolute value of the angular rotation vector of the geodetic rotation of the studied body. For the J2000.0 epoch, the mean orbits of the studied celestial bodies and the mean orbit of the barycenter of the Jovian system were calculated. For regular satellites, the values of the angles of inclination of their equator to their own orbits were determined. The obtained analytical values of the geodetic precession of the studied celestial bodies can be used for a numerical study of the rotation of these bodies in the relativistic approximation.

Improving Treatment Quality of Gynecologic Cancers with Online Adaptive Brachytherapy Using Deep Learning-Based CT Imaging

This study proposes a framework for online adaptive three-dimensional (3D) brachytherapy, a type of radiation therapy used to treat gynecological cancers such as cervical and endometrial cancers. Intracavitary brachytherapy is used to deliver a high dose of radiation directly to the tumor, while minimizing exposure to the surrounding normal tissue. Maintaining accurate reproducibility of radiation dose delivery during each treatment session is important. The proposed framework uses a C-arm-based integrated online imaging system for computed tomography (CT) and single-photon emission computed tomography (SPECT) to detect changes in the treatment conditions and improve treatment quality. The C-arm CT system acquires 3D images by obtaining two-dimensional image data at limited rotation angles, which are less than the complete 360° range of rotation. However, images obtained with limited angular rotation have poor image quality and many artifacts. To overcome this limitation, a deep learning technique was applied to eliminate these artifacts and improve image quality. This study evaluated the auto-segmentation performance of ground truth (GT) images, limited-angle C-arm cone-beam CT images, and C-arm CT images corrected using deep learning. We used the Dice similarity coefficient and Hausdorff distance to quantitatively evaluate the auto-segmentation performance of major organs in the pelvic region. Although slight differences were observed in certain areas, the auto-segmentation results demonstrated an overall high performance, similar to that of the GT image. The results showed that the proposed framework can establish an optimal treatment plan by quickly and accurately calculating the patient's internal radiation dose distribution. This study demonstrates the potential of deep learning-based high-quality CT imaging techniques and auto-contouring techniques for major organs within images to improve the treatment quality of intracavitary brachytherapy.

Positioning errors and accuracy of CNC machine tools

Abstract Computerized numerically controlled (CNC) machine tools are a solid foundation for modern industrial manufacturing. These machines provide linear and angular displacements in three or five axes. The accuracy of moving and positioning the tooltip relative to the work part’s surface determines the final product’s accuracy. Errors due to machine positioning can be linear or angular or both. This work studies the positioning errors of a vertical turning center CNC machine type. This machine has three axes, two linear X (horizontal) and Z (vertical), and one rotation axis ‘C’. The travel of the spindle carrying the cutting tool along the X-axis is 1400 mm, and the travel of the carriage holding the spindle along the Z-axis is 1300 mm divided into six latches. The machine rotary table which carries the work part can rotate 360°. A highly precise laser interferometer system determines the linear positioning errors in both the X and Z axes. The angular positioning errors for the ‘C’ rotation axis are determined accurately by an autocollimator system. The positioning error measurements are carried out based on ISO 230–2 as a measurement standard of positioning deviation, accuracy, and repeatability. The collected error measurements in linear displacements and angular rotation are analyzed, interpreted, and compared with manufacturer specifications and ISO 13041–4 allowable tolerances.

On the evolution of the shock waves systems created by the fan blades

Fan is one of the noise sources in a modern engine. The fan noise is especially noticeable during takeoff at high angular rotation speeds. In such operating modes, supersonic flow around the tips of the fan blades is realized, which leads to the formation of shock waves that propagate upstream until they exit of the engine channel. As a result, a specific noise is emitted into the front hemisphere, consisting of harmonics that are multiples of the fan rotation frequency. The paper analyzes the described effect based on a simple model of the propagation of a shock waves system. By using energy analysis, it is shown that the system of shock waves with equal amplitude decays faster than a system of shock waves with a spread in amplitude.

دراسة علمية حول العزم الزاوي وعلاقته بالخصائص الميكانيكية لشفرات التوربينات

The general trend now in all countries of the world and all sectors is to achieve sustainability. One of how this sustainability can be achieved is to develop and improve the properties of raw materials, and in the field of turbine-powered power plants, sustainability must be achieved in light of the global crisis facing the energy sector, in this study, which aims to study the effect of angular torque on Mechanical properties of turbine blades, so that we can develop and improve the properties of those blades Angular torque is very important in turbine blades because it drives the turbine to rotate. Angular torque results from a force acting on a rotating body. In the case of turbine blades, the force of the gas flow produces angular torque. Turbine blades typically consist of thin, curved metal sheets. When gas passes through the blades, it exerts a force on the blades. This force forces the blades to rotate around its axis the greater the angular torque it produces. The greater the angular torque, the faster the turbine rotates. This study provides a mathematical model to calculate the angular torque resulting from turbine blades. The model was used to study the effect of various factors on the angular torque, including the gas flow speed, the shape of the blades, and their mechanical properties. Then, a simulation was run using the ANSYS program to determine the relationship between the angular torque and the mechanical properties of the turbine blades. The results indicated a large deviation of the flexible blades and unstable rotation of the rotating blade systems, due to the coupling effect of rotation and vibration, where the mechanical properties of mass/inertia distributions, damping, and stiffness are related to changes in rotational speed and local deformation in rotor blade systems, thus, the harmonic balance must occur and the mechanical properties of the blades be improved. Keywords: Angular Torque, Mechanical Properties, Raw Materials, Turbine blades, mathematical model, flow speed, ANSYS, rotation and vibration, harmonic balance.

Loss-tolerant and supersensitive angular rotation estimation based on quantum-enhanced interferometers

Loss-tolerant and supersensitive angular rotation estimation based on quantum-enhanced interferometers

Investigating the mechanical properties related to the vertical bending of composite I‐beams with corrugated steel webs

AbstractThe maximum angular rotation attributable to the in‐plane shear deformation of flange slabs is used as generalised displacement in the conventional analysis method for I‐beams. However, the mechanical concepts are poorly understood due to the complex nature of this analysis method. Consequently, a novel strategy for analysing vertical bending in composite I‐beams is proposed in this study. This approach uses the additional deflection of composite I‐beams induced by the shear lag effect as the generalised displacement. Furthermore, this research comprehensively considers the accordion effect, shear lag and self‐equilibrium conditions for the shear lag warping stress and bending moment. Moreover, two longitudinal warping displacement difference functions are employed to accurately describe the variation of shear lag in composite I‐beams with varying flange slab widths. The differential equations of the I‐beams with corrugated steel webs in the elastic range are established based on the energy‐variation method. A complete mechanical system of a composite I‐beam is decomposed into two parts, namely, the shear lag mechanical system and the elementary beam mechanical system, which are independent of each other. The theory presented in this paper reflects the internal mechanical mechanism of composite I‐beams. The calculation accuracy is considerably improved in this study. Therefore, this method is more unambiguous and well‐defined. It enriches and advances the current analysis theory of composite structures, which can guide the design of composite I‐beams.

Structure-preserving finite element methods for computing dynamics of rotating Bose-Einstein condensate

This work is concerned with the construction and analysis of structure-preserving Galerkin methods for computing the dynamics of rotating Bose-Einstein condensate (BEC) based on the Gross-Pitaevskii equation with angular momentum rotation. Due to the presence of the rotation term, constructing finite element methods (FEMs) that preserve both mass and energy remains an unresolved issue, particularly in the context of nonconforming FEMs. Furthermore, in comparison to existing works, we provide a comprehensive convergence analysis, offering a thorough demonstration of the methods’ optimal and high-order convergence properties. Finally, extensive numerical results are presented to check the theoretical analysis of the structure-preserving numerical method for rotating BEC, and the quantized vortex lattice’s behavior is scrutinized through a series of numerical tests.

Analyzing the Combined Effects of Axial Loads and Bending Moments on Unequal-Angle Steel Members

Angle steel is commonly used in inclined bracing components such as transmission towers. Due to its inherent section characteristics, unequal angle steel undergoes angular rotation when subjected to eccentric axial pressure, resulting in a change in the direction of action along the X and Y axes. In comparison to equal angle steel, the analysis of unequal angle steel is more complex. In design, particular attention should be given to whether the angle steel section is compact or noncompact, with a significant emphasis on the impact of the width-to-thickness ratio on strength. In study analyzed nine different angle steel sections, revealing that two of them exhibit a phenomenon known as control point transfer. This is especially prone to occur with shorter lengths of angle steel components, leading to Leg Local Buckling. In contrast, longer components are more susceptible to Lateral-Torsional Buckling. Summarizing the research findings, it is recommended to exercise caution when using non-compact section angle steel in design, and a preference for compact sections is advised to ensure the safety of the structure. Furthermore, it is advised to pay attention to the parameter βw in the AISC unequal angle steel calculation formula and adhere to relevant specifications to enhance the accuracy and reliability of structural design.

ϵ Sagittarii: An Extreme Rapid Rotator with a Decretion Disk

We report high-precision, multiwavelength linear-polarization observations of the bright B9 (or A0) star ϵ Sagittarii. The polarization shows the distinctive wavelength dependence expected for a rapidly rotating star. Analysis of the polarization data reveals an angular rotation rate ω (=Ω/Ωcrit) of 0.995 or greater, the highest yet measured for a star in our Galaxy. An additional wavelength-independent polarization component is attributed to electron scattering in a low-density, edge-on gas disk that also produces the narrow absorption components seen in the spectrum. Several properties of the star (polarization due to a disk, occasional weak Hα emission, and multiple periodicities seen in space photometry) resemble those of Be stars, but the level of activity in all cases is much lower than that of typical Be stars. The stellar properties are inconsistent with single-rotating-star evolutionary tracks, indicating that it is most likely a product of binary interaction. The star is an excellent candidate for observation by interferometry, optical spectropolarimetry to detect the Öhman effect, and ultraviolet polarimetry, any of which would allow its extreme rotation to be tested and its stellar properties to be refined.

Transformation towards a Low-Emission and Energy-Efficient Economy Realized in Agriculture through the Increase in Controllability of the Movement of Units Mowing Crops While Simultaneously Discing Their Stubble

When harvesting cereals and fodder grasses, a two-phase method is often used. This process is carried out using trailed and suspended collecting units. The former are asymmetrical and often pose problems regarding the stability of their movement in the horizontal plane. In practice, suspended harvesting units with a front-mounted header are becoming more and more widely used. The disadvantage of their use is that the soil is exposed after passing through the space between the swaths of the mown crop. This is followed by an intense loss of moisture. In order to eliminate this shortcoming, a collecting unit was proposed, consisting of a tractor with a front attachment and a disc harrow mounted at the rear. An appropriate mathematical model was developed to justify the scheme and parameters of such a unit. In this case, this model is used to assess the controllability of the movement of the dynamic system under the influence of control action in the form of the angular rotation of the tractor’s steered wheels. As a result of mathematical modelling, it was found that satisfactory controllability of the movement of the harvesting units can be ensured by acting on the tractor’s driven wheels with a frequency of 0–1 s−1 and a working speed of close to 3 m·s−1. In this case, it is desirable to set the deflection resistance coefficient of the rear tyres of the tractor (and therefore, the air pressure in them) to a smaller value, and that of the front tyres to a larger value. This helps both to improve the movement controllability of the harvesting unit and to reduce its energy consumption by an average of 6.75%. The emissivity of selected harmful chemicals and particulates emitted by the harvesting unit, depending on the fuel burned, was also examined. The way in which the use of the harvesting unit affects the reduction of emissions of harmful compounds into the atmosphere was also revealed.

Nanoradian-scale precision in light rotation measurement via indefinite quantum dynamics.

The manipulation and metrology of light beams are pivotal for optical science and applications. In particular, achieving ultrahigh precision in the measurement of light beam rotations has been a long-standing challenge. Instead of using quantum probes like entangled photons, we address this challenge by incorporating a quantum strategy called "indefinite time direction" into the parameterizing process of quantum parameter estimation. Leveraging this quantum property of the parameterizing dynamics allows us to maximize the utilization of orbital angular momentum resources for measuring ultrasmall angular rotations of beam profile. Notably, a nanoradian-scale precision of light rotation measurement is lastly achieved in the experiment, which is the highest precision by far to our best knowledge. Furthermore, this scheme holds promise in various optical applications due to the diverse range of manipulable resources offered by photons.

Noise Level of a Ring Laser Gyroscope in the Femto-Rad/s Range.

Absolute angular rotation rate measurements with sensitivity better than prad/s would be beneficial for fundamental science investigations. In this regard, large frame Earth based ring laser gyroscopes are top instrumentation as far as bandwidth, long-term operation, and sensitivity are concerned. Here, we demonstrate that the GINGERINO active-ring laser upper limiting noise is close to 2×10^{-15} rad/s for ∼2×10^{5} s of integration time, as estimated by the Allan deviation evaluated in a differential measurement scheme. This result is more than a factor of 10 better than the theoretical prediction so far accounted for ideal ring lasers shot-noise with the two beams counterpropagating inside the cavity considered as two independent propagating modes. This feature is related to the peculiarity of real ring laser system dynamics that causes phase crosstalking among the two counterpropagating modes. In this context, the independent beam model is, then, not applicable, and the measured noise limit falls below the expected one.

Tunable acoustic vortex generation by a compact rotating disk

Acoustic vortices (AVs) carry orbital angular momentum (OAM), showing great promise in advancing communication, biomedicine, and metrology. An ideal OAM generation method that realizes the tunability of AV topological charge and working frequency in a compact way is strongly desired. Here, we utilize aerodynamic dipole sources from a rotating disk to generate AV. This method generates AVs with different topological charges through the interference of these dipole sources at the angular rotation frequency and its multiples. These AVs exhibit high purity, and their three-dimensional characteristics are explored. Furthermore, our experiment demonstrates that the generated AVs significantly enhance the sound field amplitude at their working frequency, which is the product of the topological charge and angular frequency. The results also verify that this amplitude enhancement effect is positively correlated with the AV’s stability and achieves the contactless detection of disk rotation information. The demonstrated method provides expanded versatility for OAM-based applications.

Enhancing predictive capabilities in fusion burning plasmas through surrogate-based optimization in core transport solvers

This work presents the PORTALS framework (Rodriguez-Fernandez et al 2022 Nucl. Fusion 62 076036), which leverages surrogate modeling and optimization techniques to enable the prediction of core plasma profiles and performance with nonlinear gyrokinetic simulations at significantly reduced cost, with no loss of accuracy. The efficiency of PORTALS is benchmarked against standard methods, and its full potential is demonstrated on a unique, simultaneous 5-channel (electron temperature, ion temperature, electron density, impurity density and angular rotation) prediction of steady-state profiles in a DIII-D ITER Similar Shape plasma with GPU-accelerated, nonlinear CGYRO (Candy et al 2016 J. Comput. Phys. 324 73–93). This paper also provides general guidelines for accurate performance predictions in burning plasmas and the impact of transport modeling in fusion pilot plants studies.

Kinematical and ellipsoidal properties of the inner-halo hot subdwarfs observed in Gaia DR3 and LAMOST DR7

Here, we report the kinematical parameters of inner-halo hot subdwarfs located within (d≤15kpc) at high Galactic latitudes (bo≥20). The study included three program stars for one of the extreme He-rich groups (eHe-1) with eccentricity (e= 0.65) and the z-component of the angular momentum (Jz = 4288.66 kpc km s−1), the inner halo program I with 121 points (Teff≥24,000) and their subsections, i.e. inner halo program II (sdB; 79 points) with (40,000≥Teff≥24,000) and inner halo program III (sdO; 42 points) with (80,000≥Teff≥40,000). First, we calculated the spatial velocities (U¯,V¯,W¯;kms−1) along the Galactic coordinates (i.e., 25.73 ± ± 5.07, 28.79 ± 5.37, −14.51 ± 3.81) and their dispersion velocities (σ1,σ2,σ3;kms−1) = (161.94 ± 12.73, 140.31 ± 11.85, 101.57 ± 10.08) and subsequently their subsections sdB and sdO. Second, we calculated the vertex longitudes (l2) and the Solar motion (S⊙=41.246.42kms−1) as well as their subsections. Finally, based on the kinematic relation of the ratio (σ2/σ1) and our previously computed numerical value of the angular rotation rate (|A−B|=26.07±5.10;kms−1kpc−1), we obtained the average Oort's constants as (A&B;kms−1kpc−1) = (9.38 ± 0.33, −16.69 ± 0.25).

Twist-Induced Hyperbolic Shear Metasurfaces

Following the discovery of moiré-driven superconductivity and density waves in twisted-graphene multilayers, twistronics has spurred a surge of interest in tailored broken symmetries through angular rotations enabling new properties, from electronics to photonics and phononics. Analogously, in monoclinic polar crystals a nontrivial angle between nondegenerate dipolar phonon resonances can naturally emerge due to asymmetries in their crystal lattice, and its variations are associated with intriguing polaritonic phenomena, including axial dispersion, i.e., the rotation of the optical axis with frequency, and microscopic shear effects that result in an asymmetric distribution of material loss. So far, these phenomena have been restricted to specific midinfrared frequencies difficult to access with conventional laser sources and fundamentally limited by the degree of asymmetry and by the strength of light-matter interactions available in natural crystals. Here, we leverage the twistronics concept to demonstrate maximal axial dispersion and loss redistribution of hyperbolic waves in elastic metasurfaces, achieved by tailoring the angle between coupled metasurface pairs featuring tailored anisotropy. We show extreme control over elastic wave dispersion and absorption via the twist angle and leverage the resulting phenomena to demonstrate enhanced propagation distance, in-plane reflection-free negative refraction and diffraction-free defect detection. Our work welds the concepts of twistronics, non-Hermiticity, and extreme anisotropy, demonstrating the powerful opportunities enabled by metasurfaces for tunable, highly directional surface-acoustic-wave propagation of great interest for a wide range of applications spanning from seismic mitigation to on-chip phononics and wireless communication systems, hence paving the way toward their translation into emerging photonic and polaritonic metasurface technologies. Published by the American Physical Society 2024

New method for incorporating foundation damping in time-domain analysis of integrated offshore wind turbine structures

Foundation damping has significant potential for reducing the loads of monopile-supported offshore wind turbines. However, the contribution of foundation damping is not well understood, primarily because of the absence of suitable methods for incorporating it into the time-domain analysis of wind turbine structures. This paper presents a novel approach for this purpose. In this approach, a dashpot is attached parallel to each of the p-y springs along a monopile, which models the stiffness and damping of soil-pile interactions. Employing this approach, the influence of foundation damping on the structural dynamic response is investigated using the time-domain analysis of a monopile-supported IEA 15 MW reference wind turbine. The results demonstrate that foundation damping has a limited impact on the overall dynamic response and fatigue loads of wind turbines during power production. However, the foundation fatigue loads after an emergency shutdown can be reduced by 29-46% owing to the inclusion of foundation damping. In addition, foundation damping is found to significantly influence the bending moment, horizontal displacement, and angular rotation of the monopile at the mudline under parked conditions, with load reductions of up to 20%.

MHD mixed convection of nanofluid flow Ag- Mgo/water in a channel contain a rotational cylinder

This investigation explores the mixed convection phenomenon of a hybrid nanofluid flowing within a Channel oriented horizontally featuring a triangular cavity attached to the lower channel wall. The cavity houses a rotating circular cylinder with a radius of R = 0.12. The fluid within the enclosure is a water-based nanofluid containing Ag-MgO nanoparticles. Two scenarios of combined natural and forced convection are examined: in Case 1, all channel walls, the left wall of the cavity, and the surface of the rotating cylinder are adiabatic, while the inclined wall of the cavity is isothermal. In Case 2, all channel walls, the ready wall of the cavity, and the surface of the rotating cylinder are adiabatic, except for the left wall of the cavity, which is isothermal. The dimensionless governing equations are solved under steady flow conditions for various physical parameters using a higher-order and stable Galerkin-based finite element method implemented through the software package FlexPDE. Key governing parameters such as Re number (falling within the amplitude of 10 to 100), Ri number (ranging from Ri = 0.1 to 30), and the location of cylinder rotation (Xo = 0.65 to 0.9) are simulated. The study presents results in terms of average Nusselt numbers and contour maps of streamlines and isotherms. It is observed that the average Nusselt number increases with higher Reynolds number, angular rotation speed, cylinder location, and Richardson number. Specifically, heating the inclined surface suggests that the optimal location for the rotating cylinder is Xo = 0.9, whereas if the left wall of the cavity is heated, the preferred location for the cylinder is Xo = 0.75. These findings are corroborated by comparing them with previous research, demonstrating significant agreement.

Painting robot with three axis motion

Paint was applied directly to the painted surface while painting with a brush. There are occasionally unsatisfactory outcomes, such as paint stacking or streaks remaining. Spray guns yield better paint results, therefore a robot was developed that can regulate the spray gun's movement in order to apply paint. A painting robot that resembles an arm is one that has three axes of movement. The robot can move left-right on the x axis, up-down on the y axis, and back-front on the z axis. Its end effector is a spray cannon. An ultrasonic sensor is used to measure the distance between components and the spray gun; when the sensor measures near distances, such as between 4 and 8 cm, the test sensor distance measurements have a larger average error. When the test reading distance is increased from 10 cm to 14 cm, the average error reduces. Superior painting outcomes can be achieved with a paint distance of 10 cm, an air pressure of 80 psi, and a spray gun arm movement speed of 25 rpm. With average x-axis movement of 74.6 cm, y-axis movement of 14.8 cm, and z-axis movement of 88.2 cm, the largest volume that can be painted is 97,517.5 cm3. The rotation of the arm is used to determine the angular rotation needed to paint components. Painting the left side of the component at an angle of 10°, the back side at an angle of 100°, the right side at an angle of 190°, and only painting the front side of the component at the required angle of 90° require the rotational movement of the arm to the left.