Circular Rotation Research Articles

Large Circular Dichroism and Polarization Rotation in Plasmonic Ψ-Like Structured Gold Metasurface

Large Circular Dichroism and Polarization Rotation in Plasmonic Ψ-Like Structured Gold Metasurface

Optimizing Circular Rotations in Confined Systems via Enhanced Self-Driven Speed of Active Nematics

Abstract Active matter exhibits collective motions at various scales. Geometric confinement has been identified as an effective way to control and manipulate active fluids, with much attention given to external factors. However, the impact of the inherent properties of active particles on collective motion under confined conditions remains elusive. Here, we use a highly tunable active nematics model to study active systems under confinement, focusing on the effect of self-driven speed of active particles. We identify three distinct states characterized by unique particle and flow fields within confined active nematic systems, among which circular rotation emerges as a collective motion involving rotational movement in both particle and flow fields. The theoretical phase diagram shows that increasing the self-driven speed of active particles significantly enhances the region of circular rotation state and improves its stability. Our results provide insights into the formation of high quality vortices in confined active nematic systems.

Indefinitely flat rotation curves from Mpc sized charged cocoons

Abstract Weak lensing exhibits that rotation curves of isolated galaxies remain flat up to Mpc scale (Mistele et al, 2024). Recently we proposed that dark matter is a combination of electrostatic and vacuum energy in standard physics. In this theory, isolated galaxies may be embedded in ``charged cocoons'', spheres with $\pm 1/r^2$ charge density. The related circular rotation curves decay at the Mpc scale. The analytic solution is extended to the early Universe. A peak in the cosmic microwave background spectrum is expected at the arcsec scale. The induced nanometer size of the cocoons at the Big Bang makes the initial state inhomogeneous.

Sensing Aharonov-Bohm Phase Using a Multiply-Orbiting-Ion Interferometer.

Interferometers, which are built using spatially propagating light or matter waves, are commonly used to measure physical quantities. These measurements are made possible by exploiting the interference between waves traveling along different paths. This study introduces a novel approach to sensing of the Aharonov-Bohm phase, an ion matter-wave interferometer operating within a two-dimensional rotational trajectory in a trap potential. The ion orbitals in the nearly circular potential change rotation direction with time. This reversal of rotation direction results in a corresponding change in the interference phase. Our study is the first attempt to utilize propagating matter waves of an ion in constructing a two-dimensional interferometer for the measurement of physical quantities. Given that the scale factor of the interferometer to the cyclotron motion and the rotation of the system is common, the sensitivity to the Aharonov-Bohm phase in this study corresponds to a rotation sensitivity of approximately 300 rad/s. Besides advancing interferometry, our work also lays the foundation for future research into the use of ion matter waves in gyroscopic applications.

The time‐fractional ISPH method for fin circular rotation on MHD bioconvection flow of oxytactic microorganisms and NEPCM within a hexagonal‐shaped cavity

AbstractThis work investigates the bioconvection flow of oxytactic microorganisms and nanoparticle‐enhanced phase change material (NEPCM) within a hexagonal‐shaped cavity containing a rotated cross fin, utilizing the incompressible smoothed particle hydrodynamics (ISPH) method based on a time‐fractional derivative. The study considers the circular rotation of an inner cross fin and the presence of two rectangular heat sources on the plane walls inside the hexagonal cavity. The novelty of this work is its integration of a hexagonal‐shaped cavity with a rotated cross fin and the use of a time‐fractional derivative in the ISPH method to analyze bioconvection flow, offering new insights into the interaction between microorganism motion and heat transfer dynamics in complex geometries. The effects of Darcy, Hartmann, Lewis, Peclet, Rayleigh, and bioconvection Rayleigh numbers on isotherms, heat capacity ratio, microorganism density, velocity fields, and average Nusselt number are analyzed. The key findings demonstrate the significant impact of Rayleigh and bioconvection Rayleigh numbers in enhancing heat distribution and velocity fields, thereby significantly influencing microorganism motion. Due to Lorentz forces, the velocity field decreases by with an increase in the Hartmann number from 0 to 50. The resistance of the nanofluid's velocity becomes apparent as the Darcy number decreases. Increasing Lewis and Péclet numbers cause the microorganisms to shift towards the cavity's boundaries.

ALMA Reveals Spatially Resolved Properties of Molecular Gas in the Host Galaxy of FRB 20191001A at z = 0.2340

We report the detection of the CO(2–1) emission line with a spatial resolution of 0.″9 (3.5 kpc) from the host galaxy of the fast radio burst (FRB), FRB 20191001A at z = 0.2340, using the Atacama Large Millimeter/submillimeter Array. This is the first detection of spatially resolved CO emission from the host galaxy of an FRB at a cosmological distance. The inferred molecular gas mass of the host galaxy is (2.3 ± 0.4) × 1010 M ⊙, indicating that it is gas-rich, as evidenced by the measured molecular gas fraction μ gas = 0.50 ± 0.22. This molecular gas mass and the star formation rate of the host, SFR = (8.06 ± 2.42) M ⊙ yr−1, differ from those observed in the other FRB host galaxies with the average M gas = 9.6 × 108 M ⊙ and SFR = 0.90M ⊙ yr−1. This lends further credibility to the hypothesis that FRBs may originate from single or multiple progenitors across a diverse range of galaxy environments. Based on the observed velocity field modeling, we find that the molecular gas disk is dominated by an ordered circular rotation, despite the fact that the host galaxy has a gas-rich companion galaxy with a projected separation of ∼25 kpc. The formation of the FRB’s progenitor might not have been triggered by this interaction. We derive the 3σ upper limit of the molecular gas column density at the FRB detection site to be <2.1 × 1021 cm−2 with a 3σ upper limit.

XookSuut: A BAYESIAN TOOL FOR MODELING CIRCULAR AND NON–CIRCULAR FLOWS ON 2D VELOCITY MAPS

We present XookSuut, a Python implementation of the DiskFit algorithm, optimized to perform robust Bayesian inference on parameters describing models of circular and noncircular rotation in galaxies. XookSuut surges as a Bayesian alternative for kinematic modeling of 2D velocity maps; it implements effcient sampling methods, specifically Markov Chain Monte Carlo (MCMC) and Nested Sampling (NS), to obtain the posteriors and marginalized distributions of kinematic models including circular motions, axisymmetric radial flows, bisymmetric flows, and harmonic decomposition of the LoS velocity. In this way, kinematic models are obtained by pure sampling methods, rather than standard minimization techniques based on the Χ2. All together, XookSuut represents a sophisticated tool for deriving rotational curves and to explore the error distribution and covariance between parameters.

An EM-Tracked Approach for Calibrating the 3D Pose of Flexible Endoscopes.

Flexible endoscopes are ideal instruments for visualizing and diagnosing the inner surfaces of organs via a minimally invasive incision. Calibrating a flexible endoscope is a troublesome yet inevitable process in image-based tools tracking. Aiming to simplify the calibration process, we propose an electromagnetic (EM)-tracked calibration approach that does not require any predefined poses of the EM sensor. A three-stage calibration protocol was presented in an extensor. First, the orientation of the endoscope tube was derived by conducting a circular rotation of the endoscope around its axis utilizing a pair of tightly bearing stands. Second, the 3D position of the endoscope tip was acquired by having the tip come into contact with a flat plane. Third, the pose model of the bending section was derived and transformed into the local coordinate system of the EM sensor attached to the endoscope handle. To assess the accuracy of the proposed calibration approach, two experiments were designed and performed. Experimental results indicate accuracies of 0.09 ± 0.06 deg and 0.03 ± 0.19 deg in the estimation of the endoscope tube orientation and 0.52 ± 0.29, 0.33 ± 0.11, and 0.29 ± 0.17 mm in the x,y, and z estimations of the endoscope tip position, respectively. The proposed approach is accurate and easy to operate, does not require the employment of custom calibration markers, and can be used not only in surgical training systems but also in the endoscopic-based tools tracking.

THE OPERATION DESERT STORM AND THE PATRIOT MISSILE DEFENSE SYSTEM [1] -TRAJECTORY MOTIONS IN THE AIR

Contrary to the physics text book description of a high-speed trajectory motion of an object in the air, engineers have hard time on simulating the actual trajectory of a high-speed object in the air. There are various effects of air frictions such as vibrating motions, circular rotations and sideway swings, together with some additional non-linear effects on top of these.

THE OPERATION DESERT STORM AND THE PATRIOT MISSILE DEFENSE SYSTEM [1] -TRAJECTORY MOTIONS IN THE AIR

Contrary to the physics text book description of a high-speed trajectory motion of an object in the air, engineers have hard time on simulating the actual trajectory of a high-speed object in the air. There are various effects of air frictions such as vibrating motions, circular rotations and sideway swings, together with some additional non-linear effects on top of these.

IMAGE ENCRYPTION TECHNIQUE BASED ON A BINARY COMBINATION OF MULTIPLE CHAOTIC MAPS AND DNA SEQUENCE OPERATIONS

The huge advance of digital communication and networks has led to enormous storage and transmission of information over public networks. Nevertheless, the assurance of information security remains incomplete across these unsecured networks. Digital images are the primary means for sharing information over open networks. Consequently, the confidentiality of digital images during storage and transmission has become a crucial concern, particularly when sharing sensitive information. Image encryption has emerged as a solution to this problem. This paper presents an image encryption technique based on multiple one-dimensional chaotic maps and DNA coding. The method employs three one-dimensional chaotic maps, including the Logistic map, Tent map, and piecewise map, multiple times to produce 18 random sequences with different initial values and parameters. SHA-512 hash function is used to indicate the initial values of chaotic maps. For encrypting images, the binary elements from various sequences of chaotic maps are amalgamated to alter the pixel intensities of the image in the diffusion process. Dynamic DNA coding is performed through a random selection of DNA rules and operations (XOR, XNOR, and Addition) to each pixel in the image. The technique is enforced using circular rotations which are applied randomly to each key. The proposed technique is evaluated using many standard images. Different performance metrics have been measured. The empirical findings illustrate the security and resilience of the suggested method and its ability to resist statistical and differential attacks.

Digit-Serial DA-Based Fixed-Point RNNs: A Unified Approach for Enhancing Architectural Efficiency.

The next crucial step in artificial intelligence involves integrating neural network models into embedded and mobile systems. This requires designing compact and energy-efficient neural network models in silicon for optimized performance. This article introduces a unified approach for enhancing the architectural efficiency of long short-term memory (LSTM) recurrent neural networks (RNNs). Precisely, two new structures (I and II) based on the two's complement (TC) digit-serial distributed arithmetic (DSDA) technique are presented. The block-circulant matrix-vector multiplications (MVMs) and element-wise multiplications (EWMs) are formulated using TC DSDA. In addition, a fixed-point (FxP) training procedure for quantized LSTM RNNs is considered and validated for speech recognition tasks. Both structures leverage the circular rotation of weights and generate partial products with input digit slices. A new partial-product generator (PPG) and partial-product selector (PPS) designed to work with both unsigned and signed digits is introduced. In Structure I, a nonpipelined MVM is realized with a few PPGs and PPSs, followed by a shift-accumulate unit (SAU). Conversely, in Structure II, a suitably chosen depth-pipelined MVM is achieved with multiple PPGs and PPSs, followed by a shift-to-add tree (SAT). A critical path delay (CPD) analysis for both the proposed structures is also presented. Compared with previous works, post-synthesis results on 28 -nm fully depleted silicon-on-insulator (FDSOI) technology reveal that for a model size of 128 × 128 , Structures I and II provide 39.87% , 95.63% , and 30.95% , 91.18% more area and energy efficiencies, respectively.

Effect of kinematics of working tool during surface plastic deformation on performance characteristics of reinforced parts

The article presents the results of experimental studies to determine the influence of the kinematics of the working tool during surface plastic deformation (SPD) on the operational properties of machine parts: wear resistance, corrosion resistance and flexural rigidity. As a result of experimental studies of the quality of the surface layer of machine parts, it was established that when hardened by surface plastic deformation with a toroidal roller with reverse circular motion, in comparison with a similar roller, but rotating relative to the central axis and with a roller that performs circular rotation relative to the central axis passing through the plane, connecting single-radius elements, wear resistance increases by 69,6 % and 29,8 %, the corrosion rate decreases by 53,0 % and 23,8 % and flexural stiffness increases by 58,0 % and 36,8 %, respectively.

Circular rotation of different structures on natural convection of nanofluid-mobilized circular cylinder cavity saturated with a heterogeneous porous medium

The incompressible smoothed particle hydrodynamics (ISPH) method is utilized for studying the circular rotations of three different structures, circular cylinder, rectangle and triangle centered in a circular cylinder cavity occupied by Al2O3 nanofluid. The novelty of this work is appearing in simulating the circular rotations of different solid structures on natural convection of a nanofluid-occupied a circular cylinder. The circular cylinder cavity is suspended by heterogeneous/homogeneous porous media. The embedded structures are taken as a circular cylinder, rectangle and triangle with equal areas. The first thermal condition considers the whole structure is heated, the second thermal condition considers the half of the structure is heated and the other is cooled and the third thermal condition considers the quarter of the structure is heated and the others are cooled. The outer boundary of cylinder cavity is cooled. Due to the small angular velocity ω=3.15 (low rotational speeds), then the natural convection case will be considered only. The results are representing the temperature, velocity fields. The simulations revealed that the presence of the inner hot/cold structures affects on the velocity distributions and temperature field inside a circular cylinder cavity. The triangle shape has introduced the highest temperature distributions and maximum values of the velocity fields compare to other shapes inside a circular cylinder cavity. The homogeneous porous level reduces the maximum values of velocity field by 25% compared to the heterogeneous porous level.

Modeling of novel circular gait motion through daisy sequence fitting algorithm in a vertical climbing snake robot

AbstractSnake robots can be used in multiple tasks, like, climbing, surveillance, pipe inspection, welding, and so forth. Current gaits of snake robots do not support rotation on a single horizontal plane in a circular fashion of a pole or tree at a fixed height. This makes snake robot extremely difficult to take the end effector to the desired target position and orientation. In addition, torque requirement of individual actuators or links of snake robot proportionally increases based on the number of links to be lifted while performing any task. In this paper, we propose a new gait called circular gait using the Daisy Sequence Fitting algorithm to solve the problems of circular rotation on a horizontal plane at a certain height with low torque. A sliding mode (SM) controller is implemented to achieve the circular gait's required position dynamically. Simulation results show that using the proposed circular gait, the end effector can be moved to any point on the circumference of the fixed horizontal plane of the pole or tree with a lesser torque. For the 0.5 kg module, circular gait moved the end effector to the target point using only 4.5 N m torque. The SM controller outperforms the proportional, integral, and derivative controllers in terms of response characteristics.

Effect of wobble parameters on microwelding bead formation of AISI 316L stainless steel

This study examines the impact of wobble movement on a laser beam’s behavior while moving over an AISI 316L stainless steel sample of 1.2 mm thickness during welding. The laser beam oscillatory movement is superimposed on linear movement, using a 400 W fiber laser installed on an experimental bench equipped with a scanner and worktable. Mathematical modeling estimates instantaneous beam speed values, predicting thermal influence on weld bead aspects. Microwelding experiments use autogenous processing with lateral beam oscillation. Two forms of overlapping transverse wobble are tested: one with a circular path and the other describing the mathematical symbol “infinity.” Correlations are evidenced between the input parameters and results obtained in the microwelds, including penetration and width of the beads. Results show that the frequency of movement in a circle and in “infinity” for frequencies from 200 to 400 Hz has no significant influence on the result. Increasing the amplitude of the wobble movement from 0.5 to 2 mm significantly influences the width and depth of the strands generated. The wobble technique is effective in preventing discontinuities in the process, such as porosities. A bead obtained with 300 W, 50 mm/s, 0.5 mm overlapping wobble movement, and 300 Hz circular rotation frequency showed the highest relationship between width and depth.

Face-on map of the molecular disc and 3-kpc expanding ring of the galaxy based on a high-accuracy rotation curve

We analyze the longitude-velocity diagram (LVD) of 12CO-line emission from archival data and use the most accurate rotation curve (RC) of the Milky Way to transform radial velocity to face-on position in the galactic plane. We point out that the face-on transformation is highly sensitive to the adopted RC, especially in the inner Milky Way, in the sense that deviations of the RC from the true rotation velocity lead either to an artifact hole or overcrowded concentration along the tangent circle for over- or under-estimated RC, respectively. Even if the RC is sufficiently accurate, non-circular motion such as with the 3 kpc expanding ring introduces significant artifacts in the resulting face-on-map, as long as a circular rotation is assumed. On the other hand, if we properly take into account the non-circular motion, it can be used to solve the near-far degeneracy problem of determination of kinematic distance. We thus propose a new method to solve the degeneracy by incorporating the expanding motion of a ring or arms. We apply the method to the LVD of the 3-kpc expanding ring and present its face-on map projected onto the galactic plane for the first time.

Giant molecular cloud G18.1-0.3+51 associated with H ii regions and supernova remnant in the 3-kpc expanding ring

ABSTRACT Analysing the high-resolution CO line survey of the Galactic plane with the Nobeyama 45-m telescope (FUGIN), we show that the star-forming complex G18.15-0.30+51 (G18) at radial velocity of 51 km s−1 is a tight triple association of a giant molecular cloud (GMC), H ii regions, and a supernova remnant (SNR). The radial velocity of G18 allows three possible kinematic distances of d = 3.9 ± 0.2 kpc for near solution or 12 ± 0.2 kpc for far solution, if we assume circular Galactic rotation, or d = 6.1 ± 0.1 kpc, if it is moving with the 3-kpc expanding ring at an expanding velocity of 50 km s−1. The H i line absorption of radio continuum from the H ii region constrains the distance to 5.6 ≲ dSNR ≤ 7.6 kpc. The Σ−D (radio brightness–diameter) relation yields the distance to the SNR of $d_{\rm SNR}=10.1^{+11.5}_{-4.7}$ kpc, allowing for a minimum distance of 5.4 kpc. From these, we uniquely determined the distance of G18 to be 6.07 ± 0.13 kpc in the 3-kpc expanding ring with the SNR being physically associated. The molecular mass of the GMC is estimated to be Mmol ∼ 3 × 105 M⊙. The ratio of virial to luminous molecular masses is greater than unity in the central region and decreases outward to ≲0.2 at the cloud edge, indicating that the central region is dynamic, while the entire cloud is stable. We discuss the origin of the G18 triple system and propose a sustainable GMC model with continuous star formation.

An image encryption algorithm based on circular rotation and generalized Feistel structure

An image encryption algorithm based on circular rotation and generalized Feistel structure

Star map matching method for optical circular rotation imaging based on graph neural networks.

This paper focuses on a dynamic star image acquisition and matching method for space situational awareness, which can quickly search for widely distributed resident space objects. First, the optical circular rotation imaging method performed by a single space camera is proposed to obtain a series of star images. And then, the image matching method based on graph neural networks is proposed for generating a wide observation star image. Experiment results show that compared with baseline matching algorithms, the matching accuracy and matching precision of the proposed algorithm are improved significantly.