High Angular Velocity Research Articles

The simulation of particle movement and heat transfer in rotary kiln for plastic waste pyrolysis

The wide application of massive plastic products in our daily life leads to the rapid generation of plastic wastes. The end-of-life management of plastic wastes has become a serious public concern. Converting plastic waste to energy products is a promising solution to both energy shortage and environment pollution. Plastic waste could be converted to pyrolysis gas, pyrolytic oil and pyrolytic char after pyrolysis in rotary kiln. The loading of heat carrier in the rotary kiln has an important impact on the particle movement and heat transfer, hence affecting the distribution of gas, oil and char in the pyrolysis products. This article used quartz sand as the heat carrier to pyrolyze plastic waste, and the heat carrier loading increased from 5% to 15%. With the increase of heat carrier loading, the yield of oil and char increased, but the gas yield decreased. By the analysis of particle movement and heat transfer in EDEM, it was found that loading more heat carrier could increase both the translational velocity and angular velocity of particles. The translational velocity showed an almost linear correlation to the loading of heat carriers. A noticeable phenomenon is that the velocity profile of 5% heat carrier loading was instable with time. This is because low heat carrier loading such as 5% could not impose sufficient friction on the kiln wall, and the heat carrier bed slipped on the kiln wall from time to time. On the contrary, the slipping move did not occur in cases with heat carrier loading more than 10% because of sufficient friction on the kiln wall. At these higher heat carrier loadings, the only way to release of gravitational potential is the rolling of particles from the top position along the bed surface. This rolling mode of particle movement certainly caused high angular velocity of particles, and increased the frequency of particle contacts. With 5% heat carrier loading, the average angular velocity of particles was one magnitude lower due to the fact that particles were slipping as a whole rather than each particle rolling from the top to the bottom. Owing to the difference of particle movement at different heat carrier loadings, the heat transfer was also affected by the heat carrier loadings. The cases with more heat carrier could definitely enhance the physical contact between particles, which facilitated the heat transfer from heat carrier to plastic particles. The temperature profile from EDEM showed that the plastic waste particles were heated at a higher heating rate if more heat carrier was in the rotary kiln. Therefore, loading more heat carriers accelerated volatilization process, and reduced the retention time of volatiles. This led to the increment of oil production and decrement of gas production. In addition, the increased loading of heat carrier could maintain the temperature of particle bed at higher level to enhance the carbonation reaction of volatiles, which increased the yield of pyrolytic char. The DEM simulation provided the detailed information of particle’s movement and heat transfer, which could be used as an effective tool to interpret the experimental observation and optimize the process parameters.

Sequential action, power generation and balance characteristics of a martial arts kick combination

ABSTRACT This paper presents a kinematic analysis of a kick combination action: Commonly performed, functional motion sequences are identified and, focusing on balance and sequential action characteristics, a classification of different kicking patterns of Pointfighting Martial Arts athletes is suggested. Vicon® motion analysis system was used to record 28 participants’ double side kick execution. Fighters were divided into groups determined by their highest tournament achievements (national and international athletes). A comprehensive biomechanical model was developed expanding on an existing functional phase model solely derived from the kicking leg motion. Supporting leg and thorax motion phases were added. Appropriate variables were defined and obtained to characterise balance and sequential kick action. The statistical analysis established that (a) better techniques are characterised by less directly supported dynamic balance conditions and (b) there is a clear proximal-to-distal sequence (PDMS) for each kick movement, whereby better fighters create more hip-abduction angular change and higher angular velocities at PDMS1 and more angular velocity during the knee extension of the second PDMS. Results indicate that better fighters show a higher variety in dynamic balance conditions, as well as a stronger focus in the first leg abduction and their second leg extension.

Differences in muscle mechanics underlie divergent optimality criteria between feeding and locomotor systems.

Tetrapod musculoskeletal diversity is usually studied separately in feeding and locomotor systems. However, direct comparisons between these systems promise important insight into how natural selection deploys the same basic musculoskeletal toolkit-connective tissues, bones, nerves, and skeletal muscle-to meet the differing performance criteria of feeding and locomotion. Recent studies using this approach have proposed that the feeding system is optimized for precise application of high forces and the locomotor system is optimized for wide and rapid joint excursions for minimal energetic expenditure. If this hypothesis is correct, then it stands to reason that other anatomical and biomechanical variables within the feeding and locomotor systems should reflect these diverging functions. To test this hypothesis, we compared muscle moment arm lengths, mechanical advantages, and force vector orientations of two jaw elevator muscles (m. temporalis and m. superficial masseter), an elbow flexor (m. brachialis) and extensor (m. triceps- lateral head), and a knee flexor (m. biceps femoris-short head) and extensor (m. vastus lateralis) across 18 species of primates. Our results show that muscles of the feeding system are more orthogonally oriented relative to the resistance arm (mandible) and operate at relatively large moment arms and mechanical advantages. Moreover, these variables show relatively little change across the range of jaw excursion. In contrast, the representative muscles of the locomotor system have much smaller mechanical advantages and, depending on joint position, smaller muscle moment arm lengths and almost parallel orientations relative to the resistance arm. These patterns are consistent regardless of phylogeny, body mass, locomotor mode, and feeding specialization. We argue that these findings reflect fundamental functional dichotomies between tetrapod locomotor and feeding systems. By organizing muscles in a manner such that moment arms and mechanical advantage are relatively small, the locomotor system can produce broad joint excursions and high angular velocities with only small muscular contraction. As such, the anatomical organization of muscles within the limbs allows striding animals to move relatively rapidly and with minimal energetic expenditure. In contrast, the anatomical configuration of muscles in the feeding system, at least m. superficial masseter and m. temporalis, favors their force-producing capacity at the expense of excursion and velocity.

Bilateral torque asymmetry analysis of lower limbs of active and insufficiently active older adults

BACKGROUND:Physical activity is an important tool for positively impacting physical, cognitive, and social aspects and is linked to the capacity to develop muscle strength and power. However, no studies have observed the effects of physical activity on the bilateral torque asymmetry at different movement velocities in older adults.
 AIM:Investigate the effects of different angular velocities on bilateral torque asymmetry for hip, knee, and ankle joints in active and insufficiently active older adults.
 METHOD:Forty-four older adults were distributed into two groups: active and insufficiently active. An isokinetic dynamometer was used. The tests consisted of maximal concentric contractions of hip, knee, and ankle flexors and extensors at velocities of 60º/s and 120º/s. The variables were asymmetry of peak torque and of mean power.
 RESULTS:Results showed greater asymmetry in hip extension and ankle flexion for peak torque and mean power, as well as increased asymmetry in flexion movement at the higher angular velocity compared with the lower angular velocity for the mean power. Furthermore, there were no differences in asymmetry between groups.
 CONCLUSION:The conclusion of the present study was that older adults showed similar behavior for bilateral torque asymmetry, regardless of the level of physical activity.

Tooth length and occlusion in four species of piscivorous fishes: getting a grip on prey

Fitness is in part determined by the success of prey capture, often achieved in marine piscivores using teeth to capture and process prey. In ram feeding piscivores, a pattern of monognathic heterodonty has been observed where tooth size either increases posteriorly (Scomberomorus maculatus), or anteriorly (Carcharhinus limbatus), with exceptions such as Trichiurus lepturus and Sphyraena barracuda which have large anterior fangs. Tooth size and placement, as related to prey capture, was examined in Atlantic Spanish Mackerel (S. maculatus), Great Barracuda (S. barracuda), Atlantic Cutlassfish (T. lepturus), and the Blacktip shark (C. limbatus) by quantifying tooth occlusion along the jaw. Percent gape at occlusion in S. maculatus decreased anteriorly in a linear fashion, indicating occlusion from posterior to anterior. Therefore, prey initially contact the posterior teeth with high puncture pressure during high velocity strikes, capitalizing the region of greatest bite force. For S. barracuda and T. lepturus, posterior teeth and premaxillary fangs occlude at similar percent gapes (within 10%). The premaxillary fangs are likely used for initial capture due to the high angular velocity of the anterior section of the jaw and then for cutting, due to their laterally compressed shape. In C. limbatus all teeth occluded within a narrow range of 1.4–8.8% gape, indicating that all teeth meet at almost complete jaw closure. Simultaneous puncture of teeth prevents prey escape while maximizing the cutting area during head shaking. Thus, various tooth size and dentition patterns may yield similar success in prey capture, serving the same function.

A snapping shrimp has the fastest vision of any aquatic animal

Animals use their sensory systems to sample information from their environments. The physiological properties of sensory systems differ, leading animals to perceive their environments in different ways. For example, eyes have different temporal sampling rates, with faster-sampling eyes able to resolve faster-moving scenes. Eyes can also have different dynamic ranges. For every eye, there is a light level below which vision is unreliable because of an insufficient signal-to-noise ratio and a light level above which the photoreceptors are saturated. Here, we report that the eyes of the snapping shrimp Alpheus heterochaelis have a temporal sampling rate of at least 160 Hz, making them the fastest-sampling eyes ever described in an aquatic animal. Fast-sampling eyes help flying animals detect objects moving across their retinas at high angular velocities. A. heterochaelis are fast-moving animals that live in turbid, structurally complex oyster reefs and their fast-sampling eyes, like those of flying animals, may help them detect objects moving rapidly across their retinas. We also report that the eyes of A. heterochaelis have a broad dynamic range that spans conditions from late twilight (approx. 1 lux) to direct sunlight (approx. 100 000 lux), a finding consistent with the circatidal activity patterns of this shallow-dwelling species.

Nonlinear Spacecraft Attitude Control via Cascade-Forward Neural Networks

The problem of spacecraft attitude control has been addressed in the literature via several linear and nonlinear algorithms. In the current study, cascade-forward neural networks have been used to mimic the behaviour of the High Performance Nonlinear Discrete Controller (HPNDC). Controller stability is proven via Lyapunov second method. The developed control algorithm has the ability to work during all of the spacecraft operational modes and alleviates many problems associated with other nonlinear algorithms existing in the literature. Performance of the algorithm has been tested against various nonlinear attitude control algorithms including HPNDC, Sliding Mode (SM) Controller, Nonlinear Dynamic Inversion (NDI)controller, and Adaptive Neuro-Fuzzy Inference Systems (ANFIS) controller. The proposed neural networks control algorithm achieved a good performance compared to the aforementioned control algorithms. The behaviour of the HPNDC control algorithm has been used for training of the Neural Networks due to its numerous advantages when operating in linear and nonlinear operational modes. To prevent data overfitting, 10% of the training data set are used for testing. The training ratio is selected to be 90%. Gravity gradient torques acting on EGYPTSAT-1 spacecraft are considered the main acting disturbance. The developed control algorithm can nullify the initial high angular velocities and attitude angles of the spacecraft within two orbits.

Estimation of the Tangential Winds and Asymmetric Structures in Typhoon Inner Core Region Using Himawari‐8

AbstractObservations of the winds in tropical cyclones are still limited. We propose a new method for deriving the tangential winds in tropical cyclones, which employs a spectral analysis of high‐frequency cloud imaging by latest‐generation geostationary meteorological satellites such as Himawari‐8. The method was applied to the visible images of boundary layer clouds in the eye of Typhoon Lan (2017) over an 8.5‐hr period. The low‐level tangential winds over the central two thirds of the eye in radius were close to a rigid body rotation and increased with time. On its outside was a region with striating clouds rotating at much higher angular velocities, which may have been supergradient. Asymmetric motions were visualized as the deviation from the inner rotation, and the vorticity of some mesovortices were quantified. These asymmetric motions are suggested to transport angular momentum to accelerate the inner rotation.

The asymptotic solutions of the governing system of a charged symmetric body under the influence of external torques

This paper investigates the motion of a dynamically symmetric rigid body about one of its fixed points in which it is incurred to Newtonian force field, electromagnetic field and external torques. These torques acted in the direction of the principal axes of the body and are represented by perturbing and gyrostatic torques. The body rotates initially about the symmetry dynamic axis with high angular velocity. Therefore, a small parameter can be introduced. The averaging method is applied to convert the governing system of motion into another convenient averaging one in terms of a small parameter. The asymptotic analytical solutions of the latter system are obtained for some distinct applications depending upon the perturbing torques and the restoring one. The good effect of the body parameters on the motion is clarified in the graphical representations of the obtained solutions of the considered applications. The significance of this work is due to its great implementation of practical life like submarines, devices that maintain the stability and measure the orientations of airplanes and for several physics and engineering applications.

Vibration reduction of rotating frame structure based on quadratic performance index

An efficient method based on quadratic performance index and Lyapunov's second method is developed for the vibration reduction optimization of frame structure rotating at a constant angular velocity. Four optimization formulations and algorithms are studied for both low and high angular velocity. These formulations consider both linear vs nonlinear dynamic models as well as direct integration and Lypunov method to evaluate performance index. Three numerical examples are presented to compare the effectiveness of the four algorithms. Numerical results show that all the four optimization methods can reduce vibration at low rotating speed and find very similar optimal designs. However, at high rotating speed, dynamic model of rotating structure must consider nonlinear axial strain in order to obtain correct dynamic response. Since the Lyapunov's second method is not applicable for the nonlinear model and the NFTI (nonlinear dynamic model with nonlinear axial strain and time integration) method is very inefficient, the present study develops a perturbation method, linearizes the nonlinear dynamic model and establishes the LNFLA(linearized dynamic model with nonlinear axial strain, the Lyapunov's second method). Numerical examples show the optimization method LNFLA provides an efficient numerical method for vibration reduction of rotating frame structure with both low and high rotating speed.

Elastic Limit Angular Velocity and Acceleration Investigation in Non-Uniform Rotating Disk under Time-Dependent Mechanical Loading

An analytical effort is made to achieve cognition on the effect of time-dependent mechanical loading ‎on the stress fields of rotating disks with non-uniform thickness and density. At high variable angular ‎velocities and accelerations, evaluation of the effect of shear stress on the values of von Mises stress is ‎significant and it is excellent to consider shear stress in this equivalent stress calculation alongside the ‎radial and tangential stress. In the proposed analytical model, the Homotopy perturbation method (HPM) ‎solves the general structure of rotating disks equilibrium equations in both radial and tangential ‎directions. HPM is an efficient tool to solve linear and nonlinear equations, providing solutions in quick ‎converging series. The results obtained through this process are then confirmed using the finite ‎difference method and the exact solution in the literature. The effect of parameters in angular velocity ‎and acceleration functions with the parameter in the thickness function and the effect of boundary ‎conditions on the values of elastic limit angular velocity and acceleration are established by performing ‎numerical examples. Furthermore, the effect of shear stress on the maximum values of ‎von Mises stress is discussed. It is shown that shear stress has more influence on the distribution of ‎equivalent von Mises stress in the elastic region. It is shown the introduced analytical model is useful for ‎evaluating rotating disk with any arbitrary shape of thickness and density function, without using the ‎commercial finite element simulation software.

Time-Optimal Magnetic Attitude Detumbling

The problem of minimum-time spacecraft attitude detumbling using magnetic rods is revisited in this paper within the context of optimal control theory. Two formulations are presented; the first one assumes the availability of the angular velocity measurements for feedback. The second formulation assumes the availability of only the ambient magnetic field measurements in the feedback. In both formulations, the constraint in this optimal control problem is a limit on the maximum magnetic dipole moment of the magnetic rods. It is shown that the time optimality will be achieved if the triple orthogonality condition between the torque, the dipole moment, and the magnetic field vector is fulfilled. This triple orthogonality is considered as a condition of optimality, which is often neglected in the existing B-dot law and its variants in the literature. The Pontryagin minimum principle is used to derive analytically the control logic, for each formulation, in this nonautonomous system, under the assumption of high angular velocity. The second formulation is shown to yield a new variant of the B-dot law. The Monte Carlo simulation results presented in this paper confirm that the two controls found in both formulations outperform most existing algorithms. In addition, the results show lower power consumption by the magnetic rods when using the proposed variant of the B-dot law as compared to existing B-dot laws.

Impact of a rotating cone on forced convection of Ag–MgO/water hybrid nanofluid in a 3D multiple vented T-shaped cavity considering magnetic field effects

Forced convection of hybrid Ag–MgO/water nanofluid in a three-dimensional T-shaped vented cavity with multiple ports under the effects of a inner rotating cone and magnetic field is numerically studied with finite volume method. The simulation is performed for various values of parameters such as: Reynolds number (between 100 and 1000), Hartmann number (between 0 and 60), angular velocity of the rotating cone (between − 200 rad/s and 0), aspect ratio of the circular cylinders of the base of the cone (between 0.5 and 2) and nanoparticle solid volume fraction of the hybrid nanofluid ( $$\phi _1$$ between 0 and 0.01, $$\phi _2$$ between 0 and 0.01). It was observed that the average heat transfer rate rises with higher values of Reynolds number, Hartmann number above a specified value, angular rotational speed of the cone, aspect ratio of the cone for values above 1 and solid nanoparticle volume fractions of the hybrid particles. In total, 61% of average heat transfer enhancement for left horizontal upper surface is achieved with the imposed magnetic field. The enhancement in the average Nusselt numbers is 25.6% for the rotating cone at the highest angular velocity as compared to a motionless one. The average heat transfer increases almost linearly with hybrid solid nanoparticle volume fraction, while 8.96% and 15.52% enhancements are obtained for varying the solid volume fraction of the particles with the lower and higher thermal conductivity up to 0.01.

Performance Analysis of a Lower Limb Multi Joint Angle Sensor Using CYTOP Fiber: Influence of Light Source Wavelength and Angular Velocity Compensation.

This paper presents the analysis of an intensity variation polymer optical fiber (POF)-based angle sensor performance, i.e., sensitivity, hysteresis and determination coefficient (), using cyclic transparent optical polymer (CYTOP) fiber. The analysis consisted of two approaches: influence of different light source central wavelengths (430 nm, 530 nm, 660 nm, 870 nm and 950 nm) and influence of different angular velocities ( rad/s, rad/s, rad/s, rad/s and rad/s). The first approach aimed to select the source which resulted in the most suitable performance regarding highest sensitivity and linearity while maintaining lowest hysteresis, through the figure of merit. Thereafter, the analysis of different angular velocities was performed to evaluate the influence of velocity in the curvature sensor performance. Then, a discrete angular velocity compensation was proposed in order to reduce the root-mean-square error (RMSE) of responses for different angular velocities. Ten tests for each analysis were performed with angular range of to , based on knee and ankle angle range during the gait. The curvature sensor was applied in patterns simulating the knee and ankle during the gait. Results show repeatability and the best sensor performance for nm in the first analysis and show high errors for high angular velocities ( rad/s) in the second analysis, which presented up to angular error. The uncompensated RMSE was high for all velocities ( to ), whereas the compensated RMSE decreased up to ( to ). The compensated responses of application tests showed maximum error of and minimum of , presenting a decrease of mean angular error up to when compared with uncompensated responses.

Spinning elastic beads: a route for simultaneous measurements of the shear modulus and the interfacial energy of soft materials.

Large deformations of soft elastic beads spinning at high angular velocity in a denser background fluid are investigated theoretically, numerically, and experimentally using millimeter-size polyacrylamide hydrogel particles introduced in a spinning drop tensiometer. We determine the equilibrium shapes of the beads from the competition between the centrifugal force and the restoring elastic and surface forces. Considering the beads as neo-Hookean up to large deformations, we show that their elastic modulus and interfacial energy constant can be simultaneously deduced from their equilibrium shape. Also, our results provide further support to the scenario in which interfacial energy and interfacial tension coincide for amorphous polymer gels.

Anti-Disturbance Control Based on Cascade ESO and Sliding Mode Control for Gimbal System of Double Gimbal CMG

Disturbance torque and unmodeled dynamics are the main important factors which affect the angular velocity precision of a gimbal system in double gimbal control moment gyro (DGCMG). In this paper, a compound control method combining reduced-order cascade extended state observer (RCESO) and integral sliding mode control (SMC) is proposed, aiming at effectively eliminating the influence of exogenous disturbances and unmodeled dynamics, and achieving high precision angular velocity control of the gimbal system. Firstly, the disturbance torque is observed by the RCESO, and the parameter tuning method of RCESO is studied. Secondly, to enhance the robustness of the whole control system and take into account disturbance estimation errors, an integral sliding mode control is introduced. Simulation and experimental results show that the proposed control method not only improves the compensation performance of the gimbal system with external disturbances, but also enhances the robustness and improves the angular velocity precision of the gimbal system.

Real-time observation of the optical Sagnac effect in ultrafast bidirectional fibre lasers

Active ring laser gyroscopes (RLG) operating on the principle of the optical Sagnac effect are preferred instruments for a range of applications, such as inertial guidance systems, seismology, and geodesy, that require both high bias stability and high angular velocity resolutions. Operating at such accuracy levels demands special precautions like dithering or multi-mode operation to eliminate frequency lock-in or similar effects introduced due to synchronisation of counter-propagating channels. Recently proposed bidirectional ultrafast fibre lasers can circumvent the limitations of continuous wave RLGs. However, their performance is limited due to the nature of the highly-averaged interrogation of the Sagnac effect. In general, the performance of current optical gyroscopes relies on the available measurement methods used for extracting the signal. Here, by changing the paradigm of traditional measurement and applying spatio-temporal intensity processing, we demonstrate that the bidirectional ultrafast laser can be transformed to an ultrafast gyroscope with acquisition rates of the order of the laser repetition rate, making them at least two orders of magnitude faster than commercially deployed versions. We also show the proof-of-principle for dead-band-free round trip time-resolved spectral domain measurements using the Dispersive Fourier Transform, further enhancing the gyroscopic sensitivity. Our results reveal the high potential of application of novel methods of signal measurements in mid-sized ultrafast fibre laser gyroscopes to achieve performances that are currently available only with large-scale RLGs.

Compact Swimming Robot with Continuum Water Jet Nozzle for Rapid Turns

Abstract In this paper, a swimming robot capable of rapid turns not only horizontally but also vertically in an underwater environment is proposed. The robot utilizes a wire-driven continuum water jet nozzle, which can be oriented in an arbitrary direction and allows the robot to turn in a small radius. In this study, the deformation characteristics of the nozzle were first experimentally investigated, and the nozzle was then implemented in the robot. The performance of the robot was experimentally investigated in an underwater environment. The results indicated that it was capable of a high angular velocity, and could accomplish 180 degree turns within a tactical diameter that was smaller than its body length.

Rotation of floating particles in submesoscale cyclonic and anticyclonic eddies: a model study for the southeastern Baltic Sea

Abstract. We hypothesized that the overwhelming dominance of cyclonic spirals on satellite images of the sea surface could be caused by some differences between the rotary characteristics of submesoscale cyclonic and anticyclonic eddies. This hypothesis was tested by means of numerical experiments with synthetic floating Lagrangian particles embedded offline in a regional circulation model of the southeastern Baltic Sea with very high horizontal resolution (0.125 nautical mile grid). The numerical experiments showed that the cyclonic spirals can be formed from both a horizontally uniform initial distribution of floating particles and from the initially lined-up particles during an advection time of the order of 1 d. Statistical processing of the trajectories of the synthetic floating particles allowed us to conclude that the submesoscale cyclonic eddies differ from the anticyclonic eddies in three ways favoring the formation of spirals in the tracer field: they can be characterized by (a) a considerably higher angular velocity, (b) a more pronounced differential rotation and (c) a negative helicity.

The effects of annealing temperature and angular velocity variation on microstructure and optical properties of barium titanate (BaTiO3) using chemical solution deposition method

This study is aimed to find out the energy gap value of BaTiO3 thin film since this study has a purpose to reduce the energy gap so that it can be used for photovoltaic applications. The making of Barium Titanate (BaTiO3) thin film was carried out on the quartz substrate using the Chemical Solution Deposition (CSD) method with the technique of depositing spin coating. The making of BaTiO3 thin film was carried out using variation of angular velocity at 4000 rpm and 5000 rpm and variation of annealing temperature at 750°C, 800°C, 850°C. The samples in this study were annealed at 750°C, 800°C, 850°C with a holding time of 1 hour and an increase in temperature of 3°C/minute. The microstructure characterization of the samples was carried out using X-Ray Diffraction (XRD) equipment, and the thickness of the thin film characterization and grain size of samples using Scanning Electron Microscopy (SEM) equipment. The annealing temperature increase, the intensity becomes higher. As the annealing temperature increase, then the crystallinity, crystallite size and grain size of BaTiO3 thin film will get bigger. The annealing temperature increase is resulted the thickness and energy gap are smaller. The intensity value of the XRD remains decrease along with the angular velocity increase. The higher angular velocity causes the crystallinity and crystallite size of BaTiO3 thin film becomes higher. However, the angular velocity increase then the grain size will become smaller. The angular velocity higher, then the BaTiO3 thin film gets thinner. The angular velocity gets higher, then the smaller energy gap produced. The energy gap value was produced between 3.00 – 3.50 eV.