Leg Dominance and OSB12 Kick Start Performance in Young Competitive Swimmers

The purpose of this study was to examine differences in starting and kick-plate positions, pointing to an effect on kick-start performance with the dominant and non-dominant feet placed on the front edge of the OSB12 starting block. The sample included 20 female competitive swimmers whose average age was 16.1 ± 0.6 years. To assess swimmers’ lower body explosive strength and determine leg dominance, a triple hop distance test was administered. We determined the swimmers’ preferred starting position on a starting block in terms of the kick-plate setting and body position on the starting block. The results of our study demonstrate the importance of leg dominance and positioning on the OSB12 starting block. After the preferred starting position was determined, the optimal position for the kick start was selected. When the dominant leg was placed on the front edge of the starting block (p < 0.05; Cohen’s d—large effect), swimmers produced shorter block times and times to 2 and 5 m. For most of the tested swimmers, the optimal basic position on the starting block included neutral- and rear-weighted positions with the kick plate set to positions 3–4 and the right leg placed on the front edge of the OSB12 starting block.

How to Insert Acupuncture Needles into the Subacromial Space through LI15

LI15 is an important acupuncture point to treat shoulder pain. There are 4 needling methods for LI15 in the textbook; 1 method requires the insertion of the needle horizontally between the acromion and the great tuberosity of the humerus with the arm lowered for supraspinatus tendonitis. This method is also applicable for all conditions of rotator cuff disease, but it has not previously been described in detail. Providing X-ray scans and describing needle direction and depth of insertion will provide evidence for needling with the arm down as an effective stimulation of the subacromial space. Firstly, for this technique, with the arm raised, a concave point is located between the front edge of the acromion and the humerus, and the lower upper arm. Secondly, the acupuncture needle is inserted slightly posteriorly towards the supraspinous fossa, in the direction of the supraspinatus tendon and to a depth of 30-40 mm.

Experiment On Fluid Regime Under Different Rotate Velocity In Physical Simulation of Titanium Vertical Centrifugal Casting

In this paper, the physical simulation of filling process of vertical centrifugal casting (VCC) of complex titanium alloy casting was studied. Combined with the mature PTV particle tracking technology, the high-speed photography pictures of the filling process of VCC at different rotational speeds were obtained. The trajectory and velocity information of tracer particles in the rotating flow field were obtained by the corresponding analysis software. Then, through the analysis and modeling of quantitative experimental data, the flow behavior characteristics and movement law of titanium alloy melt in the mold cavity under different mold speeds were studied. The results show that: 1. When the mold is still, the front edge of the filling fluid forms a curved surface with the curvature center pointing to the outside of the mold; when the mold rotates, the front edge of the liquid flow forms a curved surface with the curvature center pointing to the inside of the mold; 2. With the increase of the mold rotation speed, the speed of the fluid filling the mold increases significantly; when the rotational speed is greater than 120 rpm, the fluid still has a certain driving force in the mold center far away from the gate It is good for filling the inner corner of mold with fluid; 3. When the rotational speed of centrifugal casting of titanium alloy reaches 45 rpm or above, typical turbulent vortices appear in the wake; with the increase of rotating speed to 180 rpm, the average curvature radius of turbulent vortices first increases and then decreases, and reaches the minimum value of 0.67 cm at 120 rpm.

Invasion fronts and adaptive dynamics in a model for the growth of cell populations with heterogeneous mobility

We consider a model for the dynamics of growing cell populations with heterogeneous mobility and proliferation rate. The cell phenotypic state is described by a continuous structuring variable and the evolution of the local cell population density function (i.e. the cell phenotypic distribution at each spatial position) is governed by a non-local advection–reaction–diffusion equation. We report on the results of numerical simulations showing that, in the case where the cell mobility is bounded, compactly supported travelling fronts emerge. More mobile phenotypic variants occupy the front edge, whereas more proliferative phenotypic variants are selected at the back of the front. In order to explain such numerical results, we carry out formal asymptotic analysis of the model equation using a Hamilton–Jacobi approach. In summary, we show that the locally dominant phenotypic trait (i.e. the maximum point of the local cell population density function along the phenotypic dimension) satisfies a generalised Burgers’ equation with source term, we construct travelling-front solutions of such transport equation and characterise the corresponding minimal speed. Moreover, we show that, when the cell mobility is unbounded, front edge acceleration and formation of stretching fronts may occur. We briefly discuss the implications of our results in the context of glioma growth.

Study on Stability of Exit Slope of Chenjiapo Tunnel Under Condition of Long-term Rainfall

The exit slope of Chenjiapo Tunnel is located directly above the exit of Chenjiapo Tunnel on Enshi to Laifeng expressway. During the excavation of the exit of the right line of the tunnel, the left side of the front edge of the slope slips. Under the joint action of excavation and rainfall, a large landslide of 6.27×10 4 m 3 and a huge unstable slope of 8.69×10 5 m 3 are formed. The landslide body and unstable slope body not only cause the tunnel to be shut down, but also directly threaten the operation safety of the later expressway. Therefore, in order to study the stability change process of the exit slope of Chenjiapo tunnel under the condition of long-term rainfall, the finite element calculation of the slope is carried out by GeoStudio software. The results show that under the condition of long-term continuous rainfall, the safety factor of the slope decreases with the increased rainfall time, but the reduction rate gradually slows down, and finally tends to be stable. The safety factor of the slope is reduced from 1.187 in the natural state to 1.015, which indicates that the slope is still in a stable state under the condition of long-term continuous rainfall, but the safety reserve is not high, and it is easy to lose stability and damage due to the influence of external adverse factors. As the rainfall continues, the seepage line inside the slope is rising, and the saturated area of the soil at the toe of the slope is increasing. Until the slope begins to drain outwards, the seepage field inside the slope is basically stable. The maximum horizontal displacement of the slope increases with the increased rainfall time, but the increase rate gradually slows down until it tends to be stable. The maximum horizontal displacement of the slope occurred in the middle surface of the slope at the beginning of the rainfall, and gradually transferred to the toe of the slope within 7 days of the rainfall and continued until the end of the rainfall. At the end of the rainfall, the maximum horizontal displacement of the toe of the slope is 0.128 m, and the toe of the slope will be damaged first. At the beginning of the rainfall, the plastic zone of the slope is only scattered at the slope surface and the slope toe. And then as the rainfall continues, the distribution range of the plastic zone in the slope surface, the slope toe and the slide zone gradually widen, and the slope stability gradually decreases. The maximum horizontal displacement and plastic zone of the slope are concentrated at the toe of the slope, the slope presents obvious traction failure characteristics. According to the results of field survey, there are small-scale gravel soil collapses and shear outlets at the front edge of the slope, and the survey results are consistent with the simulation results. It is suggested to set up perfect drainage engineering in the middle and back of the slope, and set anti slide piles and drainage holes at the toe of the slope to reinforce the slope.

Improving the Manufacturing Process of Aluminium Rims

The aim of the study was to indicate the reasons for non-compliance of aluminium rim castings and, using quality management instruments (Pareto-Lorenzo diagram and 5WHy method?), elimination or reduction of non-compliant products. The object of the research was an aluminium rim, while the diagnostic process of the object of the research was based on the quality control of the chemical composition of the casting, the control of mechanical properties and the control of the continuity of the material structure by radiographic and microscopic methods. On the basis of the research carried out, it was found that a sensitive casting area is the front edge of the rim rim - a significant number of porosity clusters were identified in this area. The reason for their occurrence was also specified - too rapid flooding of moulds, which resulted in gassing of the alloy. The identified cause had its origins in human resources mismanagement, namely the lack of training of the newly recruited employee. So far, the company has not carried out analyses of quality problems with the use of a sequential quality management methodology, so the implemented corrective actions have not always led to the full achievement of quality objectives. The presented sequential method, which is a combination of diagnostic and control tests and quality management instruments, is a universal way to monitor the level of quality of products and to quickly correct nonconformities.

Second and third harmonic generation from gold nanolayers: experiment versus theory

The use of semiconductors, metals, or ordinary dielectrics in the process of fabrication of nanodevices is at the front edge of nowadays technology, exploiting the properties of light propagation and localization at nanometric scale in new and surprising ways. Understanding accurately how light interacts with these materials at the nanoscale is crucial if one is to properly engineer nano-devices. When the nanoscale is reached, light-matter interactions display new phenomena where conventional approximations may not always be applicable and they should be either revised or voided. In this work, we measure the efficiency of second and third harmonic generation from gold nanolayers. The experimental results are compared with numerical simulations based on a detailed microscopic hydrodynamic model that considers different effects playing a role in the nonlinear response, not usually considered by more generic models. The agreement between experimental and theoretical results proves the importance of all these contributions.

Calculation of the interaction of a supersonic jet with a flat obstacle inclined off the jet axis

This paper presents results of a numerical solution of the model problem of the interaction of a plane supersonic jet with a semiinfinite flat plate inclinable off the jet axis. The paper is devoted to the study of the flow parameters in the jet flow field and the pressure distribution over the plate surface as a function of the plate inclination. The aim of the paper is to obtain the flow parameters in the jet flow field and the pressure distribution over the plate surface as a function of the plate inclination angle and front edge position. To obtain numerical results, marching algorithms in the inviscid gas and viscous layer approximation were used. At specified values of the supersonic underexpanded/overexpanded jet parameters, calculations were conducted in the plate inclination angle range of 0 to 20?. The position of the plate front edge was specified by two coordinates: a longitudinal and a transversal one, and in the parametric calculations the transversal coordinate was varied at a fixed longitudinal one. The cross-section at which the nonuniform jet field starts to interact with the plate was determined as a function of both the plate front edge position and the plate inclination. The numerical study showed the following: with increasing plate inclination angle, the oscillation frequencies of the flow parameters in the jet flow field and on the plate surface decrease, while their oscillation amplitudes increase, and the position of the maximum pressure point on the plate surface depends on the initial position of the plate front edge and may not coincide with the cross-section at which the jet–plate interaction starts. The results obtained may be used in qualitative estimation of the effect of different parameters in the jet flow field.