ABSTRACT
OBJECTIVES@#To investigate the relationship between the perpetrator's sex, victim's position and slashing location as well as anthropometric parameters on distance and space required for slashing, to provide the theoretical basis for the judgment of whether the crime scene was consistent with the criminal activity space.@*METHODS@#The kinematics data of 12 male and 12 female subjects slashing the neck of standing and supine mannequins as well as the chest of the standing mannequins with a kitchen knife were obtained by using a 3D motion capture system. The relationship between the perpetrator's sex-victim's position, the perpetrator's sex-slashing location, and anthropometric parameters and the distance and space required for the slashing were analyzed by two-factor repeated measures ANOVA and Pearson correlation analysis respectively.@*RESULTS@#Compared with slashing the neck of supine mannequins, the distance (L) and normalized L (l) of slashing the neck of standing mannequins were greater, while vertical distance (LVR) and normalized LVR (lVR) of the knife side were smaller. Compared with slashing the neck of standing mannequins, the L and l slashing the chest of standing mannequins were greater, while LVR and lVR were smaller. Horizontal distance (LHR) and normalized LHR (lHR) of the knife side in males were greater than that in females. Height and arm length were positively correlated with L, LHR, and LVR when striking the standing mannequins.@*CONCLUSIONS@#When slashing the neck of supine or standing victims, the slashing distance is shorter and the slashing height is greater. Furthermore, the distance and space required for slashing are correlate with anthropometric parameters.
Subject(s)
Humans , Male , Female , Motion Capture , Crime , Biomechanical PhenomenaABSTRACT
All professional or amateur athletes sustain different kinds of acute or overused injuries, which vary with sports events. Biomechanics plays the key role in determining risk factors and elucidating injury mechanisms for sports injuries. Three kinds of research methods, experimental test, modeling and computer simulation and statistical simulation, are generally used in biomechanical studies of sports injuries. This paper firstly reviews the epidemiology of sports injuries, and then comprehensively summarizes the related researches on injury biomechanics, in purpose of providing theoretical basis for studies on sports injury biomechanics, prevention of sports injuries, and clinical treatments and rehabilitation.
ABSTRACT
Objective To analyze the dynamics of vault springboard designated to using in formal competitions by the Federation International de Gymnastique (FIG), and find a new method measuring the reaction force of the springboard, so as to provide scientific supports for diagnosis of its take-off technique. Methods The stiffness values of GYMNOVA soft and hard springboards were derived by method of material mechanics, then the springboards were then tested with static, dynamic experiments and computer simulations. In the static experiment, two video cameras with the sample frequency of 600 Hz were placed at a 90° angle to capture the deformation of the springboards under the loads of 160, 180, 210 and 230 kg, respectively. In the dynamic experiment, a volunteer performed drop jump (DJ) from a 1.25 m high platform onto the hard and soft springboards, respectively, while a camera was employed to capture the deformation at the sample frequency of 300 Hz. All the three cameras were calibrated using a 2-dimensional framework, and the changes of the board height, velocity under different loads and acceleration of center of mass (COM) of the human body in DJ experiment were all obtained by digitizing the videos using SIMI MOTION software. Finally, modeling and computer simulation were performed to simulate the DJ in the dynamic experiment. Results The equation F=kx+c describing force-displacement of both the springboard was obtained. The depressing displacements of the board under different loads in the static experiment were close to those calculated by the equation. The vertical reaction force curve in DJ calculated by the equation was highly correlated to that obtained by acceleration of COM. The coefficient of multiple correlation was all greater than 0.86. Conclusions The study developed a new method for measuring the vertical reaction force of the springboard based on board depressing displacement and velocity with the help of high-speed camera. This method, which can be employed with convenience to rapidly monitor the board reaction force during take-off, provides scientific supports for enhancement of vaulting techniques and plays an active role in prevention of vaulting injuries.
ABSTRACT
The method of biomechanical modeling and computer simulation for human movement has been widely used in such research fields as elucidating physiological mechanisms of different kinds of movements, investigating the causes of sports injuries, helping to promote sports performances and to prevent injuries for athletes. Such method involves mathematical modeling on a series of physiological, anatomical and mechanical characteristics of human bones, joints, muscles and nerves. Muscle forces exerted during movements can be estimated using algorithms based on such models. Meanwhile, simulation experiments can be performed and make the results visualized by using computer software. This paper will review the biomechanical modeling and computer simulation of human movement and its application in details.