scholarly journals Biomechanical Characteristics of Vertical Jumping of Preschool Children in China Based on Motion Capture and Simulation Modeling

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8376
Author(s):  
Panchao Zhao ◽  
Zhongqiu Ji ◽  
Ruixiang Wen ◽  
Jiahui Li ◽  
Xiao Liang ◽  
...  
Keyword(s):  
Preschool Children ◽  
Motion Capture ◽  
Simulation Modeling ◽  
Muscle Force ◽  
Three Dimensional ◽  
Great Influence ◽  
Physical And Mental Health ◽  
Compression Phase ◽  
Compression Time ◽  
Vertical Jumping

Vertical jumping is one of the basic motor skills, and it is an essential part of many sports. The main purpose of this paper is to investigate characteristics of vertical jumping of children. This paper uses a motion capture system, three-dimensional platforms, and a simulation modeling system to analyze the kinematics and dynamics performance of children’s vertical jumping. The compression time increases from 3 to 4 years old, and flight height and time increases with age and stage gradually. In the compression phase and pushing phase, the hip and knee joint play a major role; in the landing phase, the knee and ankle joint play a major role. Muscle forces are mainly affected by age, and the three types of muscle force had two different trends. The muscle force of the shank and thigh increased with age, and the pelvic girdle muscles showed an “low–high–low” trend. The regression model suggests that the force of GMiP and the hip angular velocity have a great influence on jumping ability. Therefore, if we want to improve the jumping ability of preschool children, we should pay more attention to hip exercises. We should integrate the hip exercises into interesting games, which are more in line with their physical and mental health.

Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

2020 ◽  
pp. 095441002096645
Author(s):  
Jie Gao ◽  
Chunde Tao ◽  
Dongchen Huo ◽  
Guojie Wang
Keyword(s):  
Performance Improvement ◽  
High Efficiency ◽  
Three Dimensional ◽  
Great Influence ◽  
Aerodynamic Characteristics ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axial Turbine ◽  
Flow Interactions ◽  
And Performance

Marine, industrial, turboprop and turboshaft gas turbine engines use nonaxisymmetric exhaust volutes for flow diffusion and pressure recovery. These processes result in a three-dimensional complex turbulent flow in the exhaust volute. The flows in the axial turbine and nonaxisymmetric exhaust volute are closely coupled and inherently unsteady, and they have a great influence on the turbine and exhaust aerodynamic characteristics. Therefore, it is very necessary to carry out research on coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics, so as to provide reference for the high-efficiency turbine-volute designs. This paper summarizes and analyzes the recent advances in the field of coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery. This review covers the following topics that are important for turbine and volute coupled designs: (1) flow and loss characteristics of nonaxisymmetric exhaust volutes, (2) flow interactions between axial turbine and nonaxisymmetric exhaust volute, (3) improvement of turbine and volute performance within spatial limitations and (4) research methods of coupled turbine and exhaust volute aerodynamics. The emphasis is placed on the turbine-volute interactions and performance improvement. We also present our own insights regarding the current research trends and the prospects for future developments.

Experimental investigation on the three-dimensional flow field from a meltblowing slot die

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 724-732
Author(s):  
Changchun Ji ◽  
Yudong Wang
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Great Influence ◽  
Distribution Characteristics ◽  
Air Velocity ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Airflow Distribution ◽  
Slot Die ◽  
Center Area

AbstractTo investigate the distribution characteristics of the three-dimensional flow field under the slot die, an online measurement of the airflow velocity was performed using a hot wire anemometer. The experimental results show that the air-slot end faces have a great influence on the airflow distribution in its vicinity. Compared with the air velocity in the center area, the velocity below the slot end face is much lower. The distribution characteristics of the three-dimensional flow field under the slot die would cause the fibers at different positions to bear inconsistent air force. The air velocity of the spinning centerline is higher than that around it, which is more conducive to fiber diameter attenuation. The violent fluctuation of the instantaneous velocity of the airflow could easily cause the meltblowing fiber to whip in the area close to the die.

scholarly journals Engineering Comprehensive Model of Complex Wind Fields for Flight Simulation

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 145
Author(s):  
Jianwei Chen ◽  
Liangming Wang ◽  
Jian Fu ◽  
Zhiwei Yang
Keyword(s):  
Wind Field ◽  
Three Dimensional ◽  
Great Influence ◽  
Spatial Location ◽  
Flight Simulation ◽  
Comprehensive Model ◽  
Flight Trajectory ◽  
Wind Fields ◽  
Wind Field Simulation ◽  
Low Level Jet

A complex wind field refers to the typical atmospheric disturbance phenomena existing in nature that have a great influence on the flight of aircrafts. Aimed at the issues involving large volume of data, complex computations and a single model in the current wind field simulation approaches for flight environments, based on the essential principles of fluid mechanics, in this paper, wind field models for two kinds of wind shear such as micro-downburst and low-level jet plus three-dimensional atmospheric turbulence are established. The validity of the models is verified by comparing the simulation results from existing wind field models and the measured data. Based on the principle of vector superposition, three wind field models are combined in the ground coordinate system, and a comprehensive model of complex wind fields is established with spatial location as the input and wind velocity as the output. The model is applied to the simulated flight of a rocket projectile, and the change in the rocket projectile’s flight attitude and flight trajectory under different wind fields is analyzed. The results indicate that the comprehensive model established herein can reasonably and efficiently reflect the influence of various complex wind field environments on the flight process of aircrafts, and that the model is simple, extensible, and convenient to use.

scholarly journals A Novel Suture Training System for Open Surgery Replicating Procedures Performed by Experts Using Augmented Reality

2021 ◽  
Vol 45 (5) ◽  
Author(s):  
Yuri Nagayo ◽  
Toki Saito ◽  
Hiroshi Oyama
Keyword(s):  
Augmented Reality ◽  
Motion Capture ◽  
Open Surgery ◽  
Three Dimensional ◽  
Training System ◽  
Surgical Skills ◽  
Surgical Instruments ◽  
Interrupted Suture ◽  
Education Environment ◽  
Surgical Field

AbstractThe surgical education environment has been changing significantly due to restricted work hours, limited resources, and increasing public concern for safety and quality, leading to the evolution of simulation-based training in surgery. Of the various simulators, low-fidelity simulators are widely used to practice surgical skills such as sutures because they are portable, inexpensive, and easy to use without requiring complicated settings. However, since low-fidelity simulators do not offer any teaching information, trainees do self-practice with them, referring to textbooks or videos, which are insufficient to learn open surgical procedures. This study aimed to develop a new suture training system for open surgery that provides trainees with the three-dimensional information of exemplary procedures performed by experts and allows them to observe and imitate the procedures during self-practice. The proposed system consists of a motion capture system of surgical instruments and a three-dimensional replication system of captured procedures on the surgical field. Motion capture of surgical instruments was achieved inexpensively by using cylindrical augmented reality (AR) markers, and replication of captured procedures was realized by visualizing them three-dimensionally at the same position and orientation as captured, using an AR device. For subcuticular interrupted suture, it was confirmed that the proposed system enabled users to observe experts’ procedures from any angle and imitate them by manipulating the actual surgical instruments during self-practice. We expect that this training system will contribute to developing a novel surgical training method that enables trainees to learn surgical skills by themselves in the absence of experts.

scholarly journals Analysis of Turn-to-Turn Fault on Split-Winding Transformer Using Coupled Field-Circuit Approach

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1314
Author(s):  
Cunxiang Yang ◽  
Yiwei Ding ◽  
Hongbo Qiu ◽  
Bin Xiong
Keyword(s):  
Low Voltage ◽  
Short Circuit ◽  
Three Dimensional ◽  
Great Influence ◽  
Normal Operation ◽  
Transient Field ◽  
Axial Forces ◽  
Leakage Field ◽  
Characteristics Analysis ◽  
Split Winding

The turn-to-turn faults (TTF) are also inevitable in split-winding transformers. The distorted leakage field generated by the TTF current results in large axial forces and end thrusts in the fault windings as well as affecting other branch windings normal operation, so it is of significance to study TTF of split-winding transformers. In this paper, the characteristics analysis of the split-winding transformer under the TTFs of the low voltage winding at different positions are presented. A 3600 KVA four split-windings transformer is taken as an example. Then, a simplified three-dimensional simplified model is established, taking into account the forces of the per-turn coil. The nonlinear-transient field-circuit coupled finite element method is used for the model. The leakage field distribution under the TTFs of the low voltage winding at different positions is studied. The resultant force of the short-circuit winding and the force of the per-turn coil are obtained. Subsequently, the force and current relationship between the branch windings are analyzed. The results show that the TTF at the specific location has a great influence on the axial windings on the same core, and the distorted leakage magnetic field will cause excessive axial force and end thrust of the normal and short-circuit windings. These results can provide a basis for the short-circuit design of split-winding transformer.

scholarly journals The Effect of Lateral Column Lengthening on Subtalar Motion: Are We Trading Deformity for Stiffness?

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0004
Author(s):  
Brittany Hedrick ◽  
Anthony Riccio ◽  
Danielle M. Thomas ◽  
Claire Shivers ◽  
Matthew Siebert ◽  
...  
Keyword(s):  
Motion Capture ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Porous Titanium ◽  
Testing System ◽  
Materials Testing ◽  
Lateral Column ◽  
Fresh Frozen ◽  
Lateral Column Lengthening ◽  
Paired T Test

Category: Hindfoot; Other Introduction/Purpose: While lengthening of the lateral column through a calcaneal neck osteotomy is an integral component of flatfoot reconstruction in younger patients with flexible planovalgus deformities, concern exists as to the effect of this intra- articular osteotomy on subtalar motion. The purpose of this study is to quantify the alterations in subtalar motion following lateral column lengthening (LCL). Methods: The subtalar motion of 14 fresh frozen cadaveric feet was assessed using a three-dimensional motion capture system and materials testing system (MTS). Following potting of the tibia and calcaneus, optic markers were placed into the tibia, calcaneus and talus. The MTS was used to apply a rotational force across the subtalar joint to a torque of 5Nm. Abduction/adduction, supination/pronation, and plantarflexion/dorsiflexion about the talus was recorded. Specimens then underwent LCL via a calcaneal neck osteotomy which was maintained with a 12mm porous titanium wedge. Repeat subtalar motion analysis was performed and compared to pre-LCL motion using a paired t-test. Results:: No statistically significant differences in subtalar abduction/adduction (10.9O vs. 11.8O degrees, p=.48), supination/pronation (3.5O vs. 2.7O, p=.31), or plantarflexion/dorsiflexion (1.6O vs 1.0O, p=.10) were identified following LCL. Conclusion:: No significant changes in subtalar motion were observed following lateral column lengthening in this biomechanical cadaveric study. While these findings do not obviate concerns of clinical subtalar stiffness following planovalgus deformity correction, they suggest that diminished postoperative subtalar motion may be due to soft tissue scarring rather than alterations of joint anatomy.

A Low-Dimensional Dissimilarity Analysis of Unilateral and Bilateral Stroke-Impacted Hand Trajectories

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Jay Ryan U. Roldan ◽  
Dejan Milutinović ◽  
Zhi Li ◽  
Jacob Rosen
Keyword(s):  
Multidimensional Scaling ◽  
Healthy Subject ◽  
Motion Capture ◽  
Early Phase ◽  
Three Dimensional ◽  
High Rate ◽  
Motion Capture System ◽  
Trajectory Data ◽  
The Difference ◽  
Low Dimensional

In this paper, we propose a quantitative approach based on identifying hand trajectory dissimilarities through the use of a multidimensional scaling (MDS) analysis. A high-rate motion capture system is used to gather three-dimensional (3D) trajectory data of healthy and stroke-impacted hemiparetic subjects. The mutual dissimilarity between any two trajectories is measured by the area between them. This area is used as a dissimilarity variable to create an MDS map. The map reveals a structure for measuring the difference and variability of individual trajectories and their groups. The results suggest that the recovery of hemiparetic subjects can be quantified by comparing the difference and variability of their individual MDS map points to the points from the cluster of healthy subject trajectories. Within the MDS map, we can identify fully recovered patients, those who are only functionally recovered, and those who are either in an early phase of, or are nonresponsive to the therapy.

scholarly journals Examination of Kinect’s Torso PCA Model for Planar Activities Assessment after Stroke

2019 ◽  
Vol 8 (12S2) ◽  
pp. 476-482
Keyword(s):  
Motion Capture ◽  
Upper Limb ◽  
Daily Living ◽  
Hand Movement ◽  
Three Dimensional ◽  
Principal Component ◽  
Stroke Patients ◽  
Joint Coordination ◽  
Arm Transport ◽  
Statistical Results

Compensatory movement after stroke occurred when inter-joint coordination between arm and forearm for the purpose of arm transport becomes limited due to the weaknesses of the upper limb after stroke. This limitation causes an inefficiency of hand movement to perform the activity of daily living (ADL). Previous work has shown the possibility of using Kinect to assess torso compensation in typical assessment of upper limb movement in a stroke-simulated setting using a Torso Principal Component Analysis (PCA) Model. This research extends the study into evaluating Torso PCA Model in terms of orientation angles of the torso in three dimensional when performing planar activities namely circle tracing and point-topoint tracing. The orientation angles were compared to the outcome of the measurement from a standard motion capture system and Kinect’s intrinsic chest orientation angles. Based on the statistical results, Torso PCA model is concurrently valid with the clinically accepted measures of torso orientation and can be used further to analyze torso compensation in stroke patients.

scholarly journals SIMULATION MODELING OF INVOLUNTARY HUMAN MOVEMENTS

2019 ◽  
pp. 67-76
Author(s):  
Д.В. Горбунов ◽  
Т.В. Гавриленко
Keyword(s):  
Simulation Model ◽  
Simulation Modeling ◽  
High Efficiency ◽  
Three Dimensional ◽  
Neuromuscular System ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Human Movements ◽  
Human Limb ◽  
Model Algorithm

Разработана математическая и симуляционная модель для моделирования биомеханических движений конечности человека. Разработанный алгоритм модели базируется на биологическом представлении о включении и выключении в процессе удержания положения конечности отдельных мышц или их групп. Работа модели осуществляется за счет генерации случайных чисел (в математической форме симмуляционной модели отсутствуют статические величины). Сравнительный анализ экспериментальных и модельных данных показывает высокую эффективность работы симуляционной модели. Созданная симуляционная модель позволяет изучать принципы работы нервно-мышечной системы. Также модель является масштабируемой, что позволит в дальнейшем перейти к трехмерному моделированию для изучения механизмов самоорганизации биосистемы на уровне и нервно-мышечной системы, и центральной нервной системы. Mathematical and simulation model has been developed for modeling the biomechanical movements of a human limb. The developed model algorithm is based on the biological presentation and shutdown in the process of maintaining the positions of the final individual muscles or their groups. Work in models is due to statistical values. A comparative analysis of experimental and model data shows the high efficiency of the simulation model. The created simulation model allows to study the principles of the neuromuscular system. This model is scalable, which will allow us to switch to three-dimensional modeling to study the signs of self-organization of biosystems at the level of the neuromuscular system and central nervous system.

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