Study of core strength characteristics as an indicator of the volume distribution of the Temposcreen-Plus polymer-gel system

Filtration experiments are widely used in the oil and gas industry. They are used to determine the key physical and chemical characteristics of the porous medium, the parameters of fluid filtration. Also, filtration experiments are the main method for evaluating the residual resistance factor for compositions that are used in water shut-off technologies. However, filtration studies are not sufficient to study the distribution of the filtrate over the volume of the porous medium. This paper describes a method for using strength characteristics studies to evaluate the distribution of the polymer-gel system "Temposcreen-Plus" in the pore volume of the core after filtration. A method for representing core strength data in the form of a visualized image of the hardness distribution on a color scale is also proposed. Keywords: strength characteristics; hardness; core; "Temposcreen-Plus"; filtration experiments; visualization.

Effect of 12 Weeks Core Training on Core Muscle Performance in Rhythmic Gymnastics

Background: Rhythmic gymnastics performance is characterized by technical elements involving flexibility, aerobic capacity and strength. Increased core strength in rhythmic gymnastics could lead to improved sporting performance. Objective: The aim of this study was to analyze the effect of 12 weeks of core muscle training on core muscle performance in rhythmic gymnasts. Methods: A randomized controlled study involving 24 rhythmic gymnastics was conducted. Participants were randomly assigned to a control group (CG; n = 12; age 13.50 ± 3.17 years) or a training group (TG; n = 12; age 14.41 ± 2.35 years). Body composition, isometric strength of trunk, core endurance and core muscle electromyographic activity were measured (EMG) after 12 weeks of core training. Independent sample t-tests were carried out to compare baseline values between groups. A two-way repeated-measures analysis of variance (ANOVA) (time × group) was applied. Results: The TG improved body composition, trunk lean mass (mean differences MD = −0.31; p = 0.040), lean mass (MD = 0.43; p = 0.037) and bone mass (MD = −0.06; p < 0.001) after training. Core training increased isometric strength of trunk, flexion test (MD = −21.53; p = 0.019) and extension test (MD = 22.7; p = 0.049), as well as the prone bridge core endurance test (MD = −11.27; p = 0.040). The EMG values also increased in the TG in prone bridge for front trunk (MD = −58.58; p = 0.026). Conclusions: Core strength training leads to improvements in body composition, as well as improvements in trunk strength and increases in muscle electromyographic activity. These improvements could therefore improve performance during competitive rhythmic gymnastics exercises.

HOW DOES PARTICIPATION IN PHYSICAL ACTIVITY AFFECT PHYSICAL FITNESS ELEMENTS IN CHILDREN AGED 5-9?

This study was conducted to examine the effect of participation in physical activity on physical fitness parameters in children aged 5-9 years. A total of 83 children, 44 girls, and 39 boys, studying in a private primary school participated in the study voluntarily. The Eurofit Test Battery was used to evaluate the physical fitness levels of children. Within the scope of the Eurofit test battery; the body weight and height values of the children were measured. In the determination of motoric performances, flamingo balance, disc touch, sit-reach, standing long jump, sit-up, bent-arm hanging, and 5x10 meter sit-up tests were used. A personal information form prepared by the researchers was used to determine demographic characteristics. Whether the data is normally distributed or not was checked with kurtosis and skewness values. In the statistical analysis dimension; descriptive analysis (mean, standard deviation, median, min-max value, ratio, frequency), independent samples t test (Independent Samples t test) were used. In terms of children having an athlete license, a significant difference was found in their height, standing long jump test, sit-up test, bent-arm hanging test, 5x10 meter sit-up run test scores (p>0.05). A significant difference was found in the findings of height, body weight, standing long jump test, sit-up test, bent arm hanging test, 5x10 meter sit-up run test in terms of children's participation in traditional children's games (p>0.05). As a result, it has been determined that children's having an athlete's license increases their height, explosive strength, core strength endurance, upper extremity strength endurance, agility, and again, the students' participation in traditional children's games has positive effect on height, body weight, explosive strength, core strength endurance, upper extremity strength endurance and agility. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0891/a.php" alt="Hit counter" /></p>

NUMERICAL STUDY ON SHEAR BEHAVIOUR OF ENHANCED C-CHANNELS IN STEEL-UHPC-STEEL SANDWICH STRUCTURES

This paper firstly developed a three-dimensional (3D) finite element model (FEM) for enhanced C-channels (ECs) in steel-UHPC-steel sandwich structures (SUSSSs). The FEM was validated by 12 push-out tests on ECs with UHPC. With the validated FEM, this paper performed in-depth parametric studies on shear behaviours of ECs with ultra-high performance concrete (UHPC). These investigated parameters included bolt-hole gap (a), grade (M) and diameter (d) of bolt, core strength (fc), length of C-channel (Lc), and prestressing force ratio on bolt (ρ) in ECs. Under shear forces, the ECs in UHPC exhibited successive fractures of bolts and C-channels. Increasing the bolt-hole gap within 0-2 mm has no harm on the ultimate shear resistance, but greatly improves the slip capacity of ECs. Increasing grade and diameter of bolts improves the shear resistance and ductility of ECs through increasing the PB/PC (shear strength of bolt to that of C-channel) ratio. Increasing the core strength increased the shear resistance, but reduced the ductility of ECs due to the reduced PB/PC ratio. The ECs with Lc value of 50 mm offer the best ductility. Prestressing force acting on the bolts reduced the shear strength and ductility of ECs with UHPC. Analytical models were proposed to estimate the ultimate shear resistance and shear-slip behaviours of ECs with UHPC. The extensive validations of these models against 12 tests and 31 FEM analysis cases proved their reasonable evaluations on shear behaviours of ECs with UHPC.

The relationship between core stability and athletic performance in female university athletes

Background: Questions remain as to whether core stability represents a single or more components, how to assess core stability, and if a relationship exists with athletic performance in different sport codes. Objectives: To investigate the relationship between core stability and athletic performance in female university athletes. Methods: Eighty-three female athletes (hockey, netball, running, soccer and tennis) participated in this quantitative, cross-sectional study. The isometric back extension (IBE), lateral flexion (LF) and abdominal flexion (AF) tests were used to measure core strength and endurance. The core stability grading system using a pressure biofeedback unit was applied to measure core neuromuscular control (NMC). Athletic performance was assessed using the 40 m sprint, T-test, vertical jump (VJ) and the medicine ball chest throw (MBCT). Correlations between the core stability tests and the athletic performance tests were determined, overall and separately by sport. The effect of core stability on athletic performance was analysed using ANCOVA. Results: Most correlations were weak (r=0.10–0.39), although a very strong correlation was found between LF (strength) and VJ (r=0.90). When considered separately, moderate correlations (r=0.40–0.69) were found between core strength, endurance and motor control with certain athletic performance tests in all five sport codes. In runners, strong correlations (r=0.70–0.89) occurred between AF (endurance) and VJ, and in tennis players between IBE (strength) and the sprint. Conclusion: Correlations were found between core stability and athletic performance, although most correlations were negligible or weak. Athletic performance in different sport codes is associated with different components of core stability.