Motion In Region Research Articles

The Restricted Six-Body Problem with Stable Equilibrium Points and a Rhomboidal Configuration

We explore the central configuration of the rhomboidal restricted six-body problem in Newtonian gravity, which has four primaries m i (where i = 1 , … 4 ) at the vertices of the rhombus a , 0 , − a , 0 , 0 , b , and 0 , − b , respectively, and a fifth mass m 0 is at the point of intersection of the diagonals of the rhombus, which is placed at the center of the coordinate system (i.e., at the origin 0,0 ). The primaries at the rhombus’s opposite vertices are assumed to be equal, that is, m 1 = m 2 = m and m 3 = m 4 = m ˜ . After writing equations of motion, we express m 0 , m , and m ˜ in terms of mass parameters a and b . Finally, we find the bounds on a and b for positive masses. In the second part of this article, we investigate the motion and different features of a test particle (sixth body m 5 ) with infinitesimal mass that moves under the gravitational effect of the five primaries in the rhomboidal configuration. All four cases have 16, 12, 20, and 12 equilibrium points, with case-I, case-II, and case-III having stable equilibrium points. A significant shift in the position and the number of equilibrium points was found in four cases with the variations of mass parameters a and b . The regions for the possible motion of test particles have been discovered. It has also been observed that as the Jacobian constant C increases, the permissible region of motion expands. We also have numerically verified the linear stability analysis for different cases, which shows the presence of stable equilibrium points.

Numerical Analysis of Porpoising Stability Limit of a Blended-Wing–Body Aircraft During Ditching

The ditching processes of a blended-wing–body (BWB) aircraft under different initial speeds and pitch angles are simulated by numerically solving the unsteady Reynolds-averaged Navier–Stokes equations and the realizable turbulence model using the finite volume method. The volume-of-fluid model is adopted to capture the water–air interface. The six-degree-of-freedom model is employed to couple fluid dynamics and aircraft rigid-body kinematics. The global moving mesh is used to deal with the relative motion between the aircraft and the water. It is found that the plane composed of initial speed and pitch angle can be divided into two regions by a stability limit line, that is, the porpoising motion region (the aircraft takes coupled oscillatory motion between heaving and pitching) with large initial speeds and pitch angles and the stable motion region with low initial speeds and pitch angles. When the initial speed is large, the aircraft’s pitch-up moment peak and heaving amplitude are enhanced. Hence the aircraft carries out the porpoising motion. For the large initial pitch angle, the water entry depth of the aircraft increases and the waterline moves forward, which produces a more significant pitch-up moment peak and overload peak. As a result, the aircraft conducts the porpoising motion. The porpoising stability of the BWB configuration is obviously worse than the conventional and flying wing configurations. When the BWB aircraft ditches on water, the pilots should reduce the initial speed and pitch angle as much as possible to avoid the dangerous porpoising motion.

On the rhomboidal restricted five-body problem: Analysis of the basins of convergence

This manuscript aims to investigate numerically the effect of parameter λ on the basins of convergence (BoCs) associated with the equilibrium points (EPs) of the restricted rhomboidal five-body problem (RR5BP). Moreover, the parametric variation of EPs and zero velocity curves (ZVCs) are also illustrated. Firstly, we have scanned the entire interval for λ∈(13,3) to evaluate the critical value of λ where the number of EPs changes. It is observed that there exist either eleven, thirteen or fifteen EPs in total, however the stability analysis suggests that none of the EPs are linearly stable. The effect of the parameter λ and Jacobian constant C on the regions of possible motion are also illustrated. A systematic numerical investigation is performed to unveil the fact that how the parameter λ affects the geometry of the BoCs. Moreover, we have recorded the total number of iterations needed for each of the initial condition (IC) to converge a specific attractor and shown how the BoCs are related to these iterations and the associated probability distributions. Our numerical results strongly suggest that the parameter λ is indeed very influential factor in this dynamical system. The evolution of attracting regions in this dynamical system is very complicated yet an issue of paramount importance.

Floquet stability analysis of equilibrium points and numerical exploration of pulsating zero-velocity curves and Newton–Raphson basins of attraction

An important and pivot aspect of a dynamical system is the stability property and its range, which play a crucial role towards the stabilisation of a mission design. Present paper deals with Floquet stability analysis of equilibrium points and estimation of pulsating zero velocity curves and Newton–Raphson basins of attraction associated to these equilibrium points under the radiation pressure effect in the photo-gravitational planar elliptic restricted four body problem. Floquet stability test for the equilibrium points is performed with the help of the transition curves, which are generated under the influence of radiation pressure. It is noticed that stability range of the respective equilibrium points have deviated due to radiation pressure. To observe the possible regions of motion for restricted body, the pulsating zero velocity curves are numerically explored after establishing an invariant relation. It is found that not only the radiation parameter but also eccentricity and true anomaly reflect a considerable impact on the shape and size of forbidden regions. To see the tendency of randomly selected points in the phase space, Newton–Raphson basins of attraction associated to each attractor are estimated and effects of perturbing parameters are analysed. It is observed that effects of radiation and mass parameters are considerable however, that of eccentricity and true anomaly are negligible. Moreover, from probability distribution bar diagram, most probable number of iterations is 10 for the case when two primaries are of equal masses and third one is different, whereas it is 20 for the case when all primaries are of identical mass. These results will be helpful to study the generalised problem along with other kind of perturbations.

Anomalous surface elevation, velocity, and area changes of Split Lake Glacier, western Prince of Wales Icefield, Canadian High Arctic

Here we use a variety of remote sensing data sets to characterize the evolving extent, surface features, dynamics, and surface elevations of Split Lake Glacier, a small outlet of the Prince of Wales Icefield, Nunavut. The glacier started advancing between 1959 and 1975, with a continued increase in terminus area up to the present day, coincident with significant upper elevation thinning and lower elevation thickening that cannot be accounted for by surface mass balance. The highest velocities reach >600 m year−1, with the region of fastest ice motion focused around an icefall that occurs in a bedrock constriction. Distinctive ogives are present in a 1975 air photo of the glacier for the first time, which suggests that rapid motion started by 1970. These patterns are anomalous when compared with the geometry, velocity, and area changes of all other nearby areas of western Prince of Wales Icefield and suggest that Split Lake Glacier may be a slowly surging glacier. The surge duration of 50+ years is longer than any other previously described surge within the Canadian Arctic Archipelago. These results give further information concerning the wide variety of dynamic and geometrical changes of glaciers across this region.

Face Recognition for Criminal Detection

Abstract: In these days, assessment camera structure wins as a security system at high speed since this structure can screen from remote spots using Web camera joined to video screen by network. Besides, computerized supplies like Web camera, and hard circle drive are proficiently fabricated, and are sold for minimal price. Likewise, execution gain of these mechanized sorts of stuff improves at a fast rate. Current perception camera structure shows dynamic pictures from some oversight areas shot by various Web cameras all the while. Then, this system makes spectator's mind and body tired considering the way that he/she wants to watch enormous number of dynamic pictures been persistently strengthened. Moreover, this structure has a troublesome issue, which is an observer slips over mark of bad behavior. This study eliminates Motion Region from moving individual, and measures Motion Quantity for assessing his/her dynamic state. Also, this recommendation method finds the distinctive place of questionable activity, and checks the degree of risk of the questionable development.

Analysis of Equilibrium Points in Quantized Hill System

In this work, the quantized Hill problem is considered in order for us to study the existence and stability of equilibrium points. In particular, we have studied three different cases which give all whole possible locations in which two points are emerging from the first case and four points from the second case, while the third case does not provide a realistic locations. Hence, we have obtained four new equilibrium points related to the quantum perturbations. Furthermore, the allowed and forbidden regions of motion of the first case are investigated numerically. We demonstrate that the obtained result in the first case is a generalization to the classical one and it can be reduced to the classical result in the absence of quantum perturbation, while the four new points will disappear. The regions of allowed motions decrease as the value of the Jacobian constant increases, and these regions will form three separate areas. Thus, the infinitesimal body can never move from one allowed region to another, and it will be trapped inside one of the possible regions of motion with the relative large values of the Jacobian constant.

A domain-general frontoparietal network interacts with domain-preferential intermediate pathways to support working memory task.

Working memory (WM) is essential for cognition, but the underlying neural mechanisms remain elusive. From a hierarchical processing perspective, this paper proposed and tested a hypothesis that a domain-general network at the top of the WM hierarchy can interact with distinct domain-preferential intermediate circuits to support WM. Employing a novel N-back task, we first identified the posterior superior temporal gyrus (pSTG), middle temporal area (MT), and postcentral gyrus (PoCG) as intermediate regions for biological motion and shape motion processing, respectively. Using further psychophysiological interaction analyses, we delineated a frontal-parietal network (FPN) as the domain-general network. These results were further verified and extended by a delayed match to sample (DMS) task. Although the WM load-dependent and stimulus-free activations during the DMS delay phase confirm the role of FPN as a domain-general network to maintain information, the stimulus-dependent activations within this network during the DMS encoding phase suggest its involvement in the final stage of the hierarchical processing chains. In contrast, the load-dependent activations of intermediate regions in the N-back task highlight their further roles beyond perception in WM tasks. These results provide empirical evidence for a hierarchical processing model of WM and may have significant implications for WM training.

Behaviour Detection and Recognition of College Basketball Players Based on Multimodal Sequence Matching and Deep Neural Networks.

This study fuses multimodal sequence matching with a deep neural network algorithm for college basketball player behavior detection and recognition to conduct in-depth research and analysis, analyzing the basic components of basketball technical action videos by studying the practical application of technical actions in professional games and teaching videos from self-published authors of short video platforms. The characteristics of the dataset are also analyzed through literature research related to the basketball action dataset. On the established basketball technical action dataset, combined with the SSD target detection algorithm, the video images with cropping of human motion regions to reduce the size of image frames, generating a basketball technical action dataset based on cropped frames, reduces the amount of network training and improves the efficiency of subsequent action recognition training. In this study, by analyzing the characteristics of basic camera motion, a univariate global motion model is proposed to introduce a quadratic term to accurately express the shaking transformation, while the horizontal and vertical motion are independently represented to reduce the model complexity. Comparative experimental results show that the proposed model achieves a good balance between complexity and accuracy of global motion representation. It is suitable for global motion modeling in behavior recognition applications, laying the foundation for global and local motion estimation. On this basis, the visual feature change pattern of the key area of the scene (basketball area) is combined with the group behavior recognition based on motion patterns and the success-failure classification based on key visual information to achieve basketball semantic event recognition. The experimental results at NCAA show that the fusion of global and local motion patterns can effectively improve group behavior recognition performance. The semantic event recognition algorithm combining motion patterns and video key visual information achieves the best performance.

Spinal Kinematic Assessment of Chiropractic Side-Posture Adjustments: Development of a Motion Capture System

ObjectiveThe purpose of this study was to develop a protocol and a data analysis system for the assessment of postures and movements of doctors of chiropractic during side-posture adjustments (SPAs), otherwise known as side-posture chiropractic spinal manipulation. MethodsFor this study, an experienced chiropractor performed Gonstead-style lumbar SPAs on 10 participants. We used an inertial measurement unit system to record spinal angular motions and analyzed data with a custom application written in Microsoft Excel. ResultsData collection was successful for all trials. We identified postural angles at the time of set-up and thrust and maximum and minimum angles in a period centered on the thrust. All spinal regions of the chiropractor were flexed during the entire period; otherwise, movement patterns were characterized by biphasic wavelike motions, which begin before the time of the thrust and finish afterward. Within each region and plane of motion, patterns were qualitatively similar between participants, but time of thrust was not consistent within the patterns. There was a wide range of angular velocities, and the fastest was measured in the chiropractor's cervical and thoracic regions. ConclusionIn this study, we developed a protocol and a data analysis system for assessment of chiropractors’ postures and movements during SPAs. The protocol may be useful to future investigators who wish to use similar methods for educational purposes or to examine the role of optimal or suboptimal movement patterns in occupational injuries of doctors of chiropractic.

Coriolis coupling in a Hénon–Heiles system

We study the impact of a Coriolis term in the dynamics of a perturbed Hénon–Heiles Hamiltonian. The strength of the Coriolis coupling is measured by a frequency ω that regulates two different regimes. If (in scaled units) ω1, the minimum becomes a dynamically stable maximum, and there appears an open region of stable motion around that maximum. We restrict our study to ω∈[0,1) because we find richer dynamics in that interval. Poincaré surfaces of section are used to show how the strength of the Coriolis coupling controls the size of the trapping area. While, for ω=0, most of the orbits escape, for ω≈1 most of the orbits remain trapped. The transition from one situation to the other one reveals complex resonant structures giving rise to a chaotic sticky region of long living orbits. The study of the escape basins reveals that they evolve from a complex structure, with fractal boundaries, to basins with smooth boundaries. Explicit computation of the evolution of the basin entropy confirms this fact. The escape probability as a function of ω is also calculated. Both the evolution of the escape probability and the entropy are not monotonic and exhibit intricate and complex dynamics for intermediate values of ω.

Research on Postproduction of Film and Television Based on Computer Multimedia Technology

In the postproduction of film and television, the fast movement of objects or camera shake will lead to an excessive selection of key frames, resulting in information redundancy and affecting the stability of postproduction videos and video-editing effects. Aiming at this problem, this paper proposes a method of film and television postproduction based on digital media technology. Firstly, the film and video shots are segmented to find out the changing scenes; secondly, the bottom feature vector of each image is formed according to the color space entropy, motion vector, and motion region, and the video key frame is extracted based on digital media technology; finally, the pixel label information is established in the key frame, and the feature points located in the foreground are removed, while the time feature matching points and spatial feature matching points in the background are left, so as to achieve dynamic video mosaic. The experimental results show that the film and television postproduction method based on digital media technology has strong advantages compared with other methods, which can improve the stability score of video and reduce the average stitching error.

A Study on the Design and Implementation of an Improved AdaBoost Optimization Mathematical Algorithm Based on Recognition of Packaging Bottles

In this paper, a special design system is developed based on the design of the packaging bottle to achieve the effective acquisition of the image of the cross-section of the packaging bottle to be measured under the condition of limited space size, avoiding the distortion of the object to be measured. At the same time, the image of the area where the target packaging bottle is located is segmented, and the curve features are quickly determined and effectively matched with the template library to realize the recognition of the shape features of the bottle. In this paper, the design of the packaging bottle is first designed by mechanism design and 3D modeling, followed by rapid prototyping methods such as 3D printing, and the prototype is made for functional verification. Finally, the transmission speed and stability of the design system for packaging bottle recognition are improved through structural analysis and optimization methods. To realize the intelligent control of the packaging bottle transmission and identification system, the hardware control circuit is designed and the relevant intelligent control program is prepared based on the embedded system so that the packaging bottles in the transmission process can be quickly and accurately positioned and identified. An improved AdaBoost algorithm is proposed for packaging bottle detection. In the process of algorithm learning, the Haar features are too large and time-consuming, and the training sample is cropped to remove the sample edge pixels, which effectively reduces the number of features, thus reducing the computation. The proposed optical flow method is used to obtain the motion region in the video image as the region of interest, and the canny operator is used in the region of interest for edge detection, and the region of interest is filtered by the edge energy to exclude the noninterest region. Finally, the AdaBoost algorithm is used to detect the region of interest, which reduces the detection area and decreases the detection time. The improved AdaBoost algorithm has a high accuracy improvement over the traditional AdaBoost algorithm for the recognition of various packaging bottles with relatively suitable training set samples, and the system recognition time has reached the requirements of industrial recognition.

A Numerical Simulation of the Development Process of a Mesoscale Convection Complex Causing Severe Rainstorm in the Yangtze River Delta Region behind a Northward Moving Typhoon

In recent years, due to the influence of global warming, extreme weather events occur frequently, such as the continuous heavy precipitation, regional high temperature, super typhoon, etc. Tropical cyclones make frequent landfall, heavy rains and flood disasters caused by landfall typhoons have a huge impact, and typhoon rainstorms are often closely related to mesoscale and small-scale system activities. The application 2020 NCEP (National Centers for Environmental Prediction) final operational global analysis data and WRF (Weather Research and Forecasting model, version 3.9) mesoscale numerical prediction model successfully simulates the evolution characteristics of the mesoscale convective complex (MCC) that caused an extreme rainstorm in the Yangtze River delta region behind a northwards typhoon in this article. The results show that a meso-β-scale vortex existed in the mid- to upper troposphere in the region where the MCC occurred; accompanied by the occurrence of the meso-β-scale vortex, the convective cloud clusters developed violently, and its shape is a typical vortex structure. The simulation-sensitive experiment shows that the development of the meso-β-scale cyclonic vortex is the main reason for the enhancement of MCC. The occurrence and development of the MCC is manifested as a vertical positive vorticity column and a strong vertical ascending motion region in the dynamic field. In the development and maturity stage of the MCC, the vorticity and vertical rising velocity in the MCC area are significantly greater than those in the weakened typhoon circulation, which shows significant mesoscale convective system characteristics. The diagnostic analysis of the vorticity equation shows that the positive vorticity advection caused by the meso-β-scale cyclonic vortex in the mid- to upper troposphere plays important roles in the development of the MCC. Enhanced low-level convergence enhances vertical ascending motion. The convective latent heat release also plays an important role on the development of the MCC, changes the atmospheric instability by heating, enhances the upward movement, and delivers positive vorticity to the upper level, making the convection develop higher, forming a positive feedback mechanism between low-level convergence and high-level divergence. The simulation-sensitive experiment also shows that the meso-β-scale cyclonic vortex formation in this process is related to convective latent heat release.

Numerical investigation of transonic buffet on a prescribed-pitching OAT15A airfoil

The transonic buffet over a prescribed-pitching OAT15A airfoil was numerically investigated using a well-validated delayed detached eddy simulation approach. The present approach successfully reproduced self-sustained shock wave oscillations. The computational results show that the amplitude of the lift fluctuations in the pitching case is approximately six times that of the fixed case. Compared to the fixed case, the presence of a larger shock motion region, two shock wave interactions, and severe boundary separation give rise to higher pressure and velocity fluctuation levels on the whole upper surface in the pitching case. In particular, the highly disordered flow replaces the periodic vortex shedding in the wake, resulting in the disappearance of the secondary fluctuation in unsteady lift coefficients, which is observed at 2274 Hz in the fixed case. A proper orthogonal decomposition analysis shows that the buffet flow in the fixed case exhibits the feature of regular motion, which is closely related to the coherent flow structure of shock oscillations and Karman vortices. Strong interactions between the Karman vortex structure and the shock oscillations are also observed. Compared to those in the fixed case, the fluctuation amplitudes of the coefficients of the first mode pair and the second to fourth mode pairs in the pitching case are 2.5 times and 5 times larger, respectively, and the energy ratio of the nonlinear component in the total mode energy is significantly increased. Furthermore, the main frequencies of modes 1–10 in the pitching case are all located at the shock buffet frequency or its higher-order harmonics.

Fractal basins of convergence in the restricted rhomboidal six-body problem

In the present study, we numerically examined the basins of convergence (BoCs) by deploying the well known Newton–Raphson (NR) iterative scheme, associated to the libration points (LPs) (indeed, act as attractors), in the restricted rhomboidal six-body problem (RRSBP). The parametric evolution of the positions of LPs as a function of the value of parameter “b” is illustrated. Additionally, the linear stability of these LPs and the regions of possible motion are also studied. The BoCs, on the configuration (x,y) plane are unveiled by using the bivariate version of NR-iterative method. Further, a systematic analysis is performed in an order to unveil how the parameter “b” affects the topology as well as degree of fractality of the BoCs. We have also recorded the required number of iterations along with the associated probability distributions (PDs) to show how they are related to the regions of convergence. It is observed that the topology of the BoCs is directly linked with the shape of rhombus. Moreover, basin entropy and basin boundary entropy are also evaluated to unveil the degree of uncertainty of the BoC diagram.

Dynamic modeling and bifurcation analysis of blade-disk rotor system supported by rolling bearing

The dynamic modeling and bifurcation analysis are carried out for a blade-disk rotor system supported by rolling bearing in this paper. Considering the nonlinearity of rolling bearings and the flexible coupling between multi-stage blades and disk, the coupled dynamics model of the blade-disk rotor system is established by using the finite element method. Subsequently, with numerical simulations the steady-state responses of the nonlinear system are obtained. Using the bifurcation diagrams, the time histories, whirling orbits, Poincaré maps and power spectrums, the parametric studies are conducted in detail to investigate the system's bifurcation characteristics. The results indicate that considering the blade mass and stiffness will create a new resonance peak near the first-order resonance of the rotor system with linearized rolling bearing stiffness. For the rotor system with nonlinear rolling bearing forces, with the increase of the blade length, the system motion pattern becomes complex, slender blades will lead to chaotic motion at high speed, and blade stiffness and mass will obviously increase the rotational speed region of quasi-periodic motion. Moreover, the Young's modulus of the blade significantly affects the bifurcation characteristics of the system, i.e., small Young's modulus values make the motion form complex, which leads the range of quasi-periodic motion and chaotic motion increased obviously. The results of this research would be helpful to deepen comprehensive understanding of the nonlinear dynamic characteristics of blade-disk rotor system supported by rolling bearing.

Magnetization switching in the inertial regime

We have numerically solved the Landau-Lifshitz-Gilbert (LLG) equation in its standard and inertial forms to study the magnetization switching dynamics in a $3d$ thin film ferromagnet. The dynamics is triggered by ultrashort magnetic field pulses of varying width and amplitude in the picosecond and Tesla range. We have compared the solutions of the two equations in terms of switching characteristic, speed and energy analysis. Both equations return qualitatively similar switching dynamics, characterized by regions of slower precessional behavior and faster ballistic motion. In case of inertial dynamics, ballistic switching is found in a 25 % wider region in the parameter space given by the magnetic field amplitude and width. The energy analysis of the dynamics is qualitatively different for the standard and inertial LLG equations. In the latter case, an extra energy channel, interpreted as the kinetic energy of the system, is available. Such extra channel is responsible for a resonant energy absorption at THz frequencies, consistent with the occurence of spin nutation.

On the topology of basins of convergence linked to libration points in the modified R3BP with oblateness

We numerically investigate the effect of oblateness parameter on the topology of basins of convergence connected with the equilibrium points in the restricted three-body problem when the test particle is an oblate spheroid, and the influence of the gravitational potential from the belt is taken into consideration. Additionally, the primaries are also not spherical in shape, on the contrary, it is oblate or prolate spheroid. The parametric variation of the equilibrium points, their stability, and the regions of possible motion are illustrated as the function of the parameters involved. The domain of convergence, on the several two dimensional planes, are unveiled by applying the bi-variate version of the Newton–Raphson iterative method. In addition, we perform a systematic investigation in an order to show how the used parameters affect the topology as well as the degree of fractality of basins of convergence. Moreover, it is also unveiled that how the region of the convergence is related with the number of the required iterations to achieve the desired accuracy with the corresponding probability distribution.

Design of Athlete’s Running Information Capture System in Space-Time Domain Based on Virtual Reality

In order to improve the training effect of athletes, aiming at the problems of inaccurate information capture results, poor real-time performance of sports information capture, and inability to effectively suppress noise interference in traditional methods, an athlete space-time running information capture system based on virtual reality is designed. Establish the athlete’s human skeleton, obtain the athlete’s sports joint points, design the overall architecture of the athlete’s space-time running information capture system, and realize the whole link design of sports information capture through RF chip, infrared camera, sports data acquisition module, data transmission module, and human-computer interaction module. Based on virtual reality technology, a virtual reality environment is built to obtain the characteristic parameters of athletes’ sports posture in space-time domain, and the median filtering algorithm is used to filter the original signal to eliminate the impact of noise signal on athletes’ sports information capture. Finally, the activity of the motion region is detected, and the motion information is captured combined with the Gaussian mixture model. The experimental results show that the system designed in this paper has high accuracy and anti-interference and can realize the real-time capture of motion information.