Motion In Space Research Articles

Recurrent 3D Hand Pose Estimation Using Cascaded Pose-Guided 3D Alignments.

3D hand pose estimation is a challenging problem in computer vision due to the high degrees-of-freedom of hand articulated motion space and large viewpoint variation. As a consequence, similar poses observed from multiple views can be dramatically different. In order to deal with this issue, view-independent features are required to achieve state-of-the-art performance. In this paper, we investigate the impact of view-independent features on 3D hand pose estimation from a single depth image, and propose a novel recurrent neural network for 3D hand pose estimation, in which a cascaded 3D pose-guided alignment strategy is designed for view-independent feature extraction and a recurrent hand pose module is designed for modeling the dependencies among sequential aligned features for 3D hand pose estimation. In particular, our cascaded pose-guided 3D alignments are performed in 3D space in a coarse-to-fine fashion. First, hand joints are predicted and globally transformed into a canonical reference frame; Second, the palm of the hand is detected and aligned; Third, local transformations are applied to the fingers to refine the final predictions. The proposed recurrent hand pose module for aligned 3D representation can extract recurrent pose-aware features and iteratively refines the estimated hand pose. Our recurrent module could be utilized for both single-view estimation and sequence-based estimation with 3D hand pose tracking. Experiments show that our method improves the state-of-the-art by a large margin on popular benchmarks with the simple yet efficient alignment and network architectures.

An Improved Spherical Vector and Truncated Mean Stabilization Based Bat Algorithm for UAV Path Planning

Unmanned aerial vehicles have a wide range of applications. An intelligent optimization algorithm based on the traditional bat algorithm (BA) is investigated in this paper for UAV flight path planning in a static complex environment. The primary goal of this work is to develop a safer flight path while considering the feasibility of the UAV and the requirements for safe operation. This research proposes an improved spherical coordinate and truncated average stable strategy-based bat optimization algorithm (TMS-SBA). The algorithm uses the UAV’s motion space to encode the operator, and by substituting a new bat for the worst of the old one after each iteration to increase population diversity, the algorithm can converge quickly in a complex environment while maintaining stable operation. In addition, the flight path is smoothly generated by using B-spline curves to make the planned path suitable for UAV. MATLAB simulation experiments show that, compared with other traditional swarm intelligent algorithms, TMS-SBA can successfully generate feasible and effective optimal solutions in complex environments and plan shorter, safer, and more accessible flight paths for UAV.

Star formation in IC1396: Kinematics and subcluster structure revealed by Gaia

Aims. We investigate the star formation history of the IC1396 region by studying its kinematics and completing the population census. Methods. We used multiwavelength data, combining optical spectroscopy to identify and classify new members and near-infrared photometry to trace shocks, jets, and outflows as well as the interactions between the cluster members and the cloud. We also used Gaia EDR3 data to identify new potential members in the multidimensional proper motion and parallax space. Results. The revised Gaia EDR3 distance is 925±73 pc, slightly closer than previously obtained with DR2. The Gaia data reveal four distinct subclusters in the region. These subclusters are consistent in distance but display differences in proper motion. This result, with their age differences, hints toward a complex and varied star formation history. The Gaia data also unveil intermediate-mass objects that tend to evade spectroscopic and disk surveys. Our analysis has allowed us to identify 334 new members. We estimate an average age of ∼4 Myr, confirming previous age estimates. With the new members added to our study, we estimate a disk fraction of 28%, lower than previous values, due to our method detecting mainly new, diskless, intermediate-mass stars. We find age differences between the subclusters, which offers evidence of a complex star formation history with different episodes of star formation.

A Novel Strategic Aircraft Track Planning Method Considering Conflict Probability

Generally, air track planning is conducted in real time and takes modified track distance minimization as objective. Next-generation air transport systems provide aircrafts with more flexibility in track planning and more responsibilities in self-separation, which present a great challenge for aircraft optimal track planning, especially in some high-density airspaces and some complex conflict scenarios. This paper proposes a novel aircraft track planning method by taking aircraft conflict probability into consideration. First, the concepts of aircraft potential motion space and the estimation method for aircraft conflict probability is introduced. Then, taking conflict probability minimization as the objective, the classical ant colony algorithm (ACA) algorithm is improved to solve the model. Finally, an experimental study is conducted to illustrate the proposed method. Results show that the proposed method is able to provide a scientific and effective track planning approach considering the potential conflict probability of aircrafts, which is able to provide fundamental to the safety of entire air transport system.

Kambin's triangle-related data based on magnetic resonance neurography and its role in percutaneous transforaminal endoscopic lumbar interbody fusion

BackgroundThe percutaneous transforaminal endoscopic lumbar interbody fusion (PETLIF) has many advantages as a new minimally invasive surgical technique, and its surgical approach passes through the Kambin's triangle. One of the greatest challenges in completing PETLIF is avoiding nerve root damage. In previous studies, the relevant anatomic data do not correspond well with current surgical techniques, and there is a paucity of studies based on magnetic resonance neurography (MRN), which is the clearest imaging method for nerve roots. The purpose of this study was to analyze the safety of the PETLIF at each lumbar segment based on measured results from the MRN imaging data and to propose a novel method of intraoperative positioning.MethodsThe coronal images with the clearest course of nerve roots were chosen for retrospective observation. During the PETLIF, the secure region of the operation was considered to be a trapezium. The following parameters were measured, respectively: trapezoid area, height, and median line length, as well as the relevant parameters of the positional relation between the point “O,” the most secure operating center point of the secure region, and each osseous anatomic landmark. And the data were compared with the size of the cage to obtain safety.ResultsAt L1-S1, with the downward motion of the target intervertebral space, the area increased from (67.94 ± 15.22) mm2 to (140.99 ± 26.06) mm2, and the height increased from (7.23 ± 1.17) mm to (12.59 ± 1.63) mm. At L1–L5, the length of the median line was increased from (9.42 ± 1.70) mm to (12.70 ± 1.88) mm. Even though it was reduced to (11.59 ± 1.99) mm at L5–S1, it was still longer than that at L3–L4. The safety obtained by the primary observational indicator was 34.52%, 33.33%, 53.57%, 96.43%, and 77.38%, respectively, at L1–S1. The safety obtained by the two secondary observational indicators was 77.38% and 95.24% at L3–L4 and 100% at L4–S1. There was no point “O” outside the anatomic mark line. The intraoperative positioning method of the point “O” was as follows: It was located medially and horizontally approximately 3/5 of the anatomic mark line at L1–L5; the horizontal distances were (0.48 ± 0.67) mm, (1.20 ± 0.89) mm, (2.72 ± 1.01) mm, and (3.69 ± 1.47) mm, respectively. In addition, it was necessary to locate (3.43 ± 1.41) mm inward at about 4/5 of the anatomic mark line at L5–S1.ConclusionsThe MRN allows clearer and more accurate visualization of the nerve roots, and the basic anatomic study of the Kambin's triangle based on this technology is of practical clinical significance. In the current study, it is believed that, during the PETLIF, cage implantation is the safest at L4–L5, followed by L5–S1; L1–L3 is more likely to cause nerve root injury, and L3–L4 is not less likely. To improve safety, a comprehensive individualized imaging assessment should be performed before surgery. This study also provides an easy method of intraoperative localization, which helps avoid nerve root injury.

The performance of nonlinear vibration control via NiTiNOL–Steel wire ropes

Conventional nonlinear vibration absorbers must provide additional mass and motion space to achieve the expected vibration control effect, which will significantly alter the original design of the target structure. In this study, the shape memory NiTiNOL–steel (NiTi–ST) wire rope and composite plate are coupled to investigate the vibration control effect of such a configuration. The vibration response of the model is studied using the Galerkin truncation method (GTM) and the harmonic balance method (HBM), and the stability of the frequency response curve is determined using the linearized stability theory. NiTi–ST wire rope is found to have a good damping effect for both low- and high-order resonances. Under a strong external excitation, the appearance of the closed detached response (CDR) may cause system amplitude mutation; however, it can also achieve effective inhibition. Finally, the effect of the structural parameters on the vibration control is discussed. The nonlinear damping term in NiTi–ST determines the soft and hard characteristics of the system, while the equivalent linear damping term is mainly responsible for vibration suppression. Therefore, as a novel shock absorber, NiTi–ST can be applied to engineering structures in order to prevent vibration damage.

On the perception of movement vigour.

It is common to get the impression that someone moves rather slowly or quickly in everyday life. In motor control, the natural pace of movement is captured by the concept of vigour, which is often quantified from the speed or duration of goal-directed actions. A common phenomenon, here referred to as the vigour law, is that preferred speed and duration idiosyncratically increase with the magnitude of the motion. According to the direct-matching hypothesis, this vigour law could thus underlie the judgement of someone else's movement vigour. We conducted a series of three experiments (N = 80) to test whether the vigour law also exists in perception and whether it is linked to that of action. In addition to measuring participants' vigour, we also asked them to judge the quickness of stimuli representing horizontal arm reaching movements varying through amplitudes, speeds, and durations. Results showed that speed and duration of movements perceived as neither fast nor slow (i.e., natural pace) increased with amplitude, thereby indicating that the vigour law holds when an observer judges the natural pace of others' movements. Results also revealed that this judgement was population-based (related to the average vigour of all participants) rather than individual-based (participant's own vigour).

Epidemic processes on self-propelled particles: Continuum and agent-based modeling

Most spreading processes require spatial proximity between agents. The stationary state of spreading dynamics in a population of mobile agents thus depends on the interplay between the time and length scales involved in the epidemic process and their motion in space. We analyze the steady properties resulting from such interplay in a simple model describing epidemic spreading (modeled as a susceptible-infected-susceptible process) on self-propelled particles (performing run-and-tumble motion). Focusing our attention on the diffusive long-time regime, we find that the agents' motion changes qualitatively the nature of the epidemic transition from an inactive phase to an active one, characterized by the emergence of a macroscopic fraction of infected agents. Indeed, the transition becomes of the mean-field type for agents diffusing in one, two, and three dimensions, while, in the absence of motion, the epidemic outbreak depends on the dimension of the underlying static network determined by the agents' fixed locations. The insights obtained from a continuum description of the system are validated by numerical simulations of an agent-based model. Our work aims at establishing a connection between the research fields of soft active matter physics and theoretical epidemiology, and may be of interest for both communities.

Review: The Masjid in Contemporary Islamic Africa

Review: <i>The Masjid in Contemporary Islamic Africa</i>

The Feasibility of Trajectory Controller by SS Equation of an Error Model in WMR

There has been an increasing amount of research on WMRs. The WMRs have lots of advantages: their mechanical system is usually simple; the whole movement mostly contains two dependent motors; and their motions in two-dimensional space are quite adaptable. At the same time, the WMRs have better power efficiency. WMRs have been studied from many points of view, such as modelling control, obstacle avoidance, localization, tip-over stability, and so on. This paper discusses the control algorithm. WMRs have nonholonomic constraints. That is, the mobile robot may not be able to reach a specific position and angle in a specific time; however, the robot can reach the target in a different motion or within a limited time. In this paper, an error model based on the WMR is introduced. The model explains the error between the actual position and the ideal or target position in the continuous motion of WMRs. The error model will be transformed into a state-space equation in order to demonstrate that the algorithm that controls the WMR`s movement is controllable. By splitting the inputs into and , the whole equation is transformed into a zero-input state-space system. Then, the errors can be minimized with the optimization of the feedback. The results show that by optimizing the time-varying feedback matrix, the error is asymptotically stable and close to zero. Therefore, by adding this control law to the controller, an approach to making mobile robots follow the planned trajectory is obtained.

Decentralized modular hybrid supervisory control for the formation of unmanned helicopters

Formation control of Unmanned Aerial Vehicles (UAVs) requires them to tightly cooperate to reach and keep the formation, while avoiding collision. This paper proposes a novel decentralized hybrid supervisory control approach for the formation control of multiple UAVs. This is achieved by developing a symbolic motion planning technique to polarly partition the motion space resulting in a finite state discrete event model for the motion dynamics of each UAV. Then, a modular discrete supervisor is designed for different components of the formation mission including reaching the formation, keeping the formation, and collision avoidance. Further, for the collision avoidance mechanism, a novel top-down decomposition-based approach is developed to design local supervisors decentralizedly. It is formally proved that with the proposed top-down decomposition-based approach, the (locally) supervised UAVs, as a whole, can cooperatively satisfy the desired (global) collision avoidance specification. The proposed decentralized supervisory control algorithm is also verified through a hardware-in-the-loop simulator for the formation control of unmanned helicopters.

Physiological Alterations in Relation to Space Flight: The Role of Nutrition.

Astronauts exhibit several pathophysiological changes due to a variety of stressors related to the space environment, including microgravity, space radiation, isolation, and confinement. Space motion sickness, bone and muscle mass loss, cardiovascular deconditioning and neuro-ocular syndrome are some of the spaceflight-induced effects on human health. Optimal nutrition is of the utmost importance, and-in combination with other measures, such as physical activity and pharmacological treatment-has a key role in mitigating many of the above conditions, including bone and muscle mass loss. Since the beginning of human space exploration, space food has not fully covered astronauts' needs. They often suffer from menu fatigue and present unintentional weight loss, which leads to further alterations. The purpose of this review was to explore the role of nutrition in relation to the pathophysiological effects of spaceflight on the human body.

Human Motion Capture Data Retrieval and Segmentation Technology for Professional Sports Training

Human motion capturing is frequently used in sports research. The focus of this research is to help the user choose an appropriate motion capture system for their experimental setup for sports activities that addresses the challenges of linear size and acceptable fits with non-linear futures. In this paper, the eigenvalue combination was used to represent different motion postures, so as to construct an index space related to the motion sequence; and according to this index space, fast and accurate motion retrieval was done; at the same time, a motion data segmentation method based on MVU nonlinear dimensionality reduction was proposed. MVU can overcome the shortcomings that the linear size is reduced and difficult to deal with nonlinear features, and can better fit human motion data, and achieve higher accuracy.

Analytical Investigation on Load Sharing Performance of Planetary Gear Transmission under Loop Maneuver

In order to explore the influence of airframe space motion on the load sharing performance (LSP) of planetary gear transmission (PGT) inside an aircraft, the combined influence of the rotation of the carrier (internal non-inertial system, INIS) and space motion of the fuselage (external non-inertial system, ENIS) is considered. Firstly, the motion equations of PGT members under the airframe loop maneuver are derived, and then the time-varying meshing stiffness, backlash, and tooth profile error are considered; a system-level dynamics model of PGT with casing is established and solved by numerical integration. The results show that the loop maneuver intensifies the fluctuation of the dynamic meshing force in the time domain and does not change its spectral distribution, but it will affect the peak value of the low frequency part. After considering the loop maneuver, there are differences in the load sharing coefficient (LSC) of each branch, and the fluctuation range of LSC increases. The interactive influence of working conditions, bearing stiffness, manufacturing eccentricity errors and loop motion parameters on the LSP is investigated and compared in depth. This research can be utilized to guide the design of aircraft’s drivetrain.

Vibration resistance FBG temperature sensor fabrication and its application in the motor for hydraulic pump

This paper fabricated a fiber Bragg grating (FBG) temperature sensor with rapid response and excellent anti-vibration performance. The lightweight and miniaturization of the sensor provided favorable conditions for its application in mechatronic components. Specifically, the Invar capillary with an ultra-low thermal expansion coefficient was selected to package the FBG, which avoided the separation possibility between capillary and FBG under sharp temperature differences. It implied a wide temperature measurement range of the sensor. Nanometer copper suspension filled the tiny gap between capillary and FBG. Its good thermal conductivity brought a fast response speed close to the bare FBG. In addition, the jitter of FBG in the capillary was significantly reduced thanks to the nanometer copper suspension occupying its motion space. This sensor realized the reliability, rapidity and stability together. The FBG temperature sensor was applied to the temperature monitoring of small-size motor for hydraulic pump and achieved ideal results.

Folklore and choreography in the dialogue of cultural and national interaction

Subject and purpose. In the modern world, the preservation, revival and development of folk culture is becoming relevant. Due to a number of reasons, the original folklore samples are lost, and may not be subject to restoration. Therefore, at present, the problems of fixing and preserving unique folklore data that were created at different times and contained in the creations of famous choreographers remain unresolved. Samples of preserved and studied folklore can serve as a means of developing creative activity, both in dance groups and students studying folk choreography. The purpose of the study is to identify the contact links of folklore and dance culture in the context of national interaction, to identify aspects of the development of folk dance as an ethno–cultural phenomenon, to identify the potential of its use in the poly-artistic education of peoples. Materials and methods. The methodological foundation of the study is based on a discussion analysis, which helps to understand that the originality of choreography manifests in the style, manner of performance, number of participants, pace of movements, composition, genre, and traditions. Russian dances are characteristic of certain choreographic customs, which allows us to consider them not only as folk art but also as a national one. This work employs interdisciplinary and integrated approaches involving cultural studies, folklore studies, art history, and other related sciences. The results of the study. For a long time, dance folklore is one of the important forms of preservation and transfer of the accumulated experience of spiritual culture from one generation to another. Folklore is always modern and distant, it includes a variety of genres, images, poetics, which is due to social and domestic functions, also ways of expression in art. Folklore is an important source for choreography, as it serves as a material that directors resort to – directors during dancing, and theaters are examined for scientific purposes. Choreography uses oral and written folklore, both in semantic and structural aspects. He, refracted through the dance language, acquires the instance of visualization. In some cases, visual folklore becomes a conceptual idea of creating choreographic numbers and whole dance ensembles. In the archaic geometry of the early forms of dance, a communicative function is laid related to the cosmic symbols of the interaction of nature and man. Folklore principles developed in folk choreography mainly rely on the realistic method of expression, which contributed to the complexity of national recognized world schools. In the classical dance, a separate direction of characteristic dance was distinguished, based on national folklore, the mandatory study of which is now included in the educational process of choreographic educational institutions. Thus, the study of folklore in folk dance helps to understand social relations in society between representatives of a certain ethnic group, reveal their spiritual and material culture and present the aesthetic level of the creators. Depending on the ethnic composition of the dance group itself, an acquaintance with a folklore of a certain ethnic group occurs. Modern professional choreographic art, reflecting folklore, complicates and modifies it, can be considered in the context of experimental art practices and potentially used in new stage solutions. Conclusions. The conducted study allows us to conclude that the ideological, developmental, informational, educational, and socioeducational functions are important elements in the system of the art of choreography. Consequently, folklore reflects folk history, and choreographic folklore helps to study folk dances characteristic of the ethnos to which it belongs. Folk dances contain information about the nation, and the dialogue of cultures, i.e., through its representatives, allows us to obtain information about cultural values, relationships, and norms of behavior of people of another ethnic group. Thus, folklore and folk choreography broaden our horizons and integrate the connection of generations, and the communicative properties inherent in them characterize a certain people.

Properties of globular clusters formed in dark matter mini-halos

We seek to differentiate dynamical and morphological attributes between globular clusters (GCs) that were formed inside their own dark matter (DM) mini-halo from those who were not. We employed high-resolution full N-body simulations on a Graphics Processing Unit (GPU) of the GCs with and without a DM mini-halo, orbiting a Fornax-like dwarf galaxy. For GCs with DM, we observed that this dark extra mass triggers a tidal radius growth that allows the mini-halo to act as a protective shield against tidal stripping, being itself stripped beforehand. We demonstrate that this shielding effect becomes negligible when the tidal radius is smaller than the half-mass radius of the mini-halo. Contrary to previous predictions, we found that the inflation of outer stellar velocity dispersion profiles is expected for GCs with and without a mini-halo, as a result of the host’s tidal field. Moreover, we observed that GCs with a DM mini-halo should have, in general, relatively more radial outer velocity anisotropy profiles throughout all of their orbits, smaller degrees of internal rotation, and as a consequence of the latter, smaller ellipticities for their stellar distribution. Due to dynamical friction, we observed a clear bimodal evolutionary distribution of GCs with and without DM in the integrals of motion space and show that for GCs originally embedded in DM, this method is not reliable for association with previous accretion events. Finally, we provide parametric mass profiles of disrupted DM mini-halos from GCs that are to be used in Jeans modelling and orbital integration studies.

Global-PBNet: A Novel Point Cloud Registration for Autonomous Driving

Registration performs an individual and deciding role in multiple intelligent transport systems. The advancement of deep-learning-based methods enhances the robustness and effectiveness of the preliminary registration stage, although the algorithm will effortlessly fall into local optima when improving the ultimate exactitude. Similarly, traditional method based on optimization has a more reliable performance in terms of precision. However, its performance still counts on the quality of initialization. In order to solve the above problems, we propose a PBNet that combines a point cloud network with a global optimization method. This framework uses the feature information of objects to perform high-precision rough registration and then searches the entire 3D motion space to implement branch-and-bound and iterative nearest point methods. The evaluation results show that PBNet significantly reduce the influence of initial values on registration and has good robustness against noise and outliers.

APPLICATION OF A DIFFERENTIATED APPROACH IN THE ELABORATION OF WELLNESS WALKING PROGRAMS FOR PEOPLE OF THE SECOND MATURE AGE

The relevance of the problems presented in the research article is the need to elaborate modern wellness walking programs for people of mature age using a differentiated approach, taking into account the availability and health potential of wellness walk against the background of general problems of hypokinesia and morbidity of the adult working-age population. It is also important that wellness walk is the most accessible type of recreational physical culture, which is able to provide a relatively high functional load. The purpose of the article is to elaborate the wellness walking programs for people of second mature age using a differentiated approach based on different differentiation criteria. The article uses such research methods as literature analysis and pedagogical observation. Application of a differentiated approach to physical education of adults should take into account individual, environmental and social factors. In the context of the purpose of this article, criteria are used that correlate with individual factors, such as a health status and the presence or absence of the most dangerous diseases, and certain individual somatic features of the organism, in particular indicators of body mass, which directly affects the degree of detection of physical abilities. Accordingly, the training programs to wellness walk have been elaborated for people of second mature age, using a differentiated approach based on the criteria of overall health, body mass, and the state of the cardiovascular system. The author presents three wellness walking programs – for healthy people, for people with excess body mass, and for people with a mild form of coronary heart disease. Kenneth Cooperʼs principle was using in the development of programs. These programs regulate the duration of the warm-up, the walking distance, the maximum time for completing the main task, the duration of active rest after its completion, the intensity of walking within the maximum heart rate, and the number of trainings per week at various stages of the programs. Performing wellness walking programs should be taken into account that the training effect depends not only on the distance and duration of walking, but also on its speed. Therefore, the method of individual adjustment of walking speed depending on the width of step and the pace of movement is offered. As the main principle of the proposed programs, a continuous and gradual increase of loads in a five-month cycle is provided. Separate recommendations refer to cases of deterioration of well-being during training and compliance with breathing rules while walking. The elaborated programs may require testing and adjustment.

Research progress of lower limb alignment correction and prosthesis position angle in unicompartmental knee arthroplasty

The angle between the lower extremity force line and the position of the unicondylar prosthesis is an important factor affecting the long-term survival and rate clinical outcome of the unicondylar replacement prostheses. Insufficient lower limb alignment will accelerate the wear of prosthesis and reduce the survival rate of prosthesis. Excessive lower limb alignment will accelerate the progress of contralateral interventricular arthritis. It is generally believed that the lower limb force line should be corrected in mild varus after unicompartmental knee arthroplasty. However, some scholars believe that the lower limb alignment has no effect on the functional score and prosthesis survival rate after unicompartmental knee arthroplasty. The poor position of femoral and tibial prosthesis will cause unexplained pain and even prosthesis wear, but the optimal position of femoral and tibial prosthesis is controversial. It is generally believed that the posterior tibial slope should be corrected in the range of 3° to 7° in unicompartmental knee arthroplasty, but some scholars believe that excessive change of posterior tibial slope will also affect the balance of knee joint space and knee joint range of motion. This study shows that the correction of lower limb alignment to mild varus is still the best lower limb alignment for unicompartmental knee arthroplasty. The best position of femoral and tibial prosthesis needs to be confirmed by further biomechanical research. The correction of tposterior tibial slope should be changed according to the specific original dissection angle of patients before operation.