"Physical factors affecting the strength of arm wrestling"

Arm-wrestling is known as an easy-to-use, friendly play or competition. Since arm-wrestling is won by involving the opponent's arm and falling down, it is said that the size of the body frame, the grip strength, which is the gross muscle strength of the entire arm, or the effective mechanical activity of the muscle groups is important. However, there has been no research on the factors that are effective in winning arm wrestling. Therefore, we examined the factors necessary to win arm wrestling by examining the arm wrestling rate and forearm length, weight, grip strength, and maximum internal rotation vector value of the shoulder joint by using 16 healthy 20-22 years old as subjects. The relationship was examined statistically by Spearman's correlation coefficient. Then, using a multiple regression analysis, the winning rate of arm wrestling was analyzed as a dependent variable, and items with significant correlation were analyzed as independent variables. As a result, it was found that the winning rate of arm wrestling has a high correlation between forearm length and the maximum internal rotation vector value of the shoulder joint, and the latter is particularly involved.

Fault Diagnosis of Rotation Vector Reducer for Industrial Robot Based on a Convolutional Neural Network

As a key component of a mechanical drive system, the failure of the reducer will usually cause huge economic losses and even lead to serious casualties in extreme cases. To solve this problem, a two-dimensional convolutional neural network (2D-CNN) is proposed for the fault diagnosis of the rotation vector (RV) reducer installed on the industrial robot (IR). The proposed method can automatically extract the features from the data and reduce the connections between neurons and the parameters that need to be trained with its local receptive field, weight sharing, and subsampling features. Due to the aforementioned characteristics, the efficiency of network training is significantly improved, and verified by the experimental simulations. Comparative experiments with other mainstream methods are carried out to further validate the fault classification accuracy of the proposed method. The results indicate that the proposed method out-performs all the selected methods.

STRESS-STRAIN BEHAVIOR OF ROCK MASS AROUND CYLINDRICAL EXCAVATIONS WITH THE PRESET CAUCHY STRESS STRESSES AND DISPLACEMENTS AT THE BOUNDARIES

The authors solve the problem on the stresses and strains of rock mass around a cylindrical excavation with the preset vectors of the Cauchy stresses and displacements at the boundary. It is assumed that the surrounding rock mass is elastic. Along the cylindrical excavation (free of stresses), displacements are measured as functions of two surface coordinates (polar angle and length along the symmetry axis of the excavation). These measurements are used to determine all components of tensors of stresses and strains at the boundary, and all coordinates of rotation vector. It is shown how this information can be used in the stress-strain analysis of rock mass farther from the excavation.

Method of remote control of the position of the movable part of the elastic connecting unit

A method for remote control of the position in space of the movable part of the elastic connecting unit is proposed. The control is carried out by continuous measurement of six lengths between the tops of two triangles, rigidly connected, respectively, with the fixed and the movable parts of the connecting unit. For measuring the lengths, it is proposed to use Вт 718 cable sensors. Keywords: elastic connecting joint, remote control of coordinates, displacement vector, rotation vector. [email protected]

Time integration of rigid bodies modelled with three rotation parameters

Three rotation parameters are commonly used in multibody dynamics or in spacecraft attitude determination to represent large spatial rotations. It is well known, however, that the direct time integration of kinematic equations with three rotation parameters is not possible in singular points. In standard formulations based on three rotation parameters, singular points are avoided, for example, by applying reparametrization strategies during the time integration of the kinematic equations. As an alternative, Euler parameters are commonly used to avoid singular points. State-of-the-art approaches use Lie group methods, specifically integrators, to model large rigid body rotations. However, the former methods are based on additional information, e.g. the rotation matrix, which must be computed in each time step. Thus, the latter method is difficult to incorporate into existing codes that are based on three rotation parameters. In this contribution, a novel approach for solving rotational kinematics in terms of three rotation parameters is presented. The proposed approach is illustrated by the example of the rotation vector and the Euler angles. In the proposed approach, Lie group time integration methods are used to compute consistent updates for the rotation vector or the Euler angles in each time step and therefore singular points can be surmounted and the accuracy is higher as compared to the direct time integration of rotation parameters. The proposed update formulas can be easily integrated into existing codes that use either the rotation vector or Euler angles. The advantages of the proposed approach are demonstrated with two numerical examples.

N-BISHOP DARBOUX VECTOR OF A TIMELIKE CURVE IN MINKOWSKI 3-SPACE

It is known that a Bishop frame of a curve is one of the effective alternative approach in the differential geometry. Recently, several important works have been done about the Bishop frames. The aim of our paper is to investigate the N-Bishop frame for timelike curves in Minkowski space. We define the N-Bishop frame for the timelike curve in Minkowski space. Then, we consider some properties of the frame. Moreover, we describe the N-Bishop Darboux frame for the first time. Additionally, we compute some geometrical characterizations for the N-Bishop Darboux axis and momentum rotation vector.

Explicit Time Integration of Multibody Systems Modelled With Three Rotation Parameters

Rigid bodies are an essential part of multibody systems. As there are six degrees of freedom in rigid bodies, it is natural but also precarious to use three parameters for the displacement and three parameters for the rotation parameters — since there is no singularity-free description of spatial rotations based on three rotation parameters. Standard formulations based on three rotation parameters avoid singularities, e.g. by applying reparameterization strategies during the time integration of the rotational kinematic equations. Alternatively, Euler parameters are commonly used to avoid singularities. State of the art approaches use Lie group methods, specifically integrators, to model rigid body motion without the need for the above mentioned solutions. However, the methods so far have been based on additional information, e.g., the rotation matrix, which has to been computed in each step. The latter procedure is thus difficult to be implemented in existing codes that are based on three rotation parameters. In this paper, we use the rotation vector to model large rotations. Whereby Lie group integration methods are used to compute consistent updates for the rotation vector in every time step. The resulting rotation vector update is finite, while the derivative of the rotation vector in the singularity becomes unbounded. The advantages of this method are shown in an example of a gyro. Additionally, the method is applied to a multibody system and the effects of crossing singularities are presented.