Search results for "C120"
showing 7 items of 297 documents
Prompt Determination of the Mechanical Properties of Industrial Polypropylene Sandwich Pipes
2021
A simple and prompt method to determine the mechanical properties of industrial multilayer extrusion polypropylene pipes for a gravity sewer network is suggested. The engineering formulas included for calculating the permissible thickness and relative position of a foam core in the pipes are based on a linear-elastic approximation and the rule of mixtures. The applicability of the approximation was justified experimentally during investigation of the effective tensile characteristics of single- and multilayer pipes and each layer specimen by using traditional tests and finite-element calculations. The results obtained were used to formulate engineering recommendations for calculations of th…
Contrasts in fitness, motor competence and physical activity among children involved in single or multiple sports
2021
Abstract Study aim: While there is wide debate around specialization in one sport, there is a lack of information about fitness levels and motor competence of children participating in single or multiple sports. Material and methods: The study involved 358 fifth-grade children who participated in a set of health-related fitness and motor competence tests over two consecutive years. A subsample of children (n = 109) wore an accelerometer for seven consecutive days. The independent samples t-test and ANCOVA were used to compare differences between single and multi-sport participants in study variables and changes between baseline and follow-up. Results: Multi-sport participants performed bett…
Tendon length estimates are influenced by tracking location
2022
Abstract Purpose Measurement of medial gastrocnemius (MG) tendon length using ultrasonography (US) requires the muscle–tendon junction (MTJ) to be located. Previously, the MG MTJ has been tracked from different proximo-distal locations near the MTJ, which could influence estimates of tendon length change due to the different characteristics of the aponeurosis and tendon. We used US to evaluate the effect of tracking point location on MG MTJ displacement during maximal and submaximal (10, 20 and 30% of the non-injured maximal) isometric plantar flexion contractions. Methods Displacement behaviour of MTJ was tracked from (1) the exact MTJ; and (2) from an insertion point of a muscle fascicle …
A New Reliable Performance Analysis Template for Quantifying Action Variables in Elite Men’s Wheelchair Basketball
2019
This study aimed to develop a valid and reliable performance analysis template for quantifying team action variables in elite men’s wheelchair basketball. First action variables and operational definitions were identified by the authors and verified by an expert panel of wheelchair basketball coaching staff in order to establish expert validity. A total of 109 action variable were then placed into 17 agreed Categorical Predictor Variable categories. The action variables were then used to develop a computerized performance analysis template for post-event analysis. Each possession (n = 200) from an international men’s wheelchair basketball game was analyzed by the first author on two occasio…
Aposematism in the burying beetle? Dual function of anal fluid in parental care and chemical defence
2017
Burying beetles (Nicrophorus vespilloides) bear distinctive and variable orange-black patterning on their elytra and produce an anal exudate from their abdomen when threatened. During breeding, the anal exudates contribute to the antimicrobial defence of the breeding resource. We investigated whether the anal exudates also provide a responsive chemical defence, which is advertised to potential avian predators by the beetle’s orange and black elytral markings. We found that that the orange-black elytral markings of the burying beetle are highly conspicuous for avian predators against range of backgrounds, by using computer simulations. Using bioassays with wood ants, we also showed that the …
Electrical conductivity of glass fiber-reinforced plastic with nanomodified matrix for damage diagnostic
2021
The electrical conductivity of glass fiber-reinforced plastic (GFRP) with epoxy matrix modified by multiwall carbon nanotubes (MWCNT) was studied. The electrical conductivity of nanomodified lamina and multi-layered GFRP was investigated on several levels using a structural approach. Components of the electrical conductivity tensor for unidirectional-reinforced monolayer were calculated similarly as in micromechanics using the conductivity of the nanomodified matrix. The electrical conductivity of multilayer composite was calculated using laminate theory and compared with values measured experimentally for various fiber orientation angles. Calculated and experimental data were in good agree…
Validation in Young Soccer Players of the Modified Version of the Harre Circuit Test: The Petrucci Ability Test
2021
The evaluation of soccer players’ physical fitness from youth onward is important for monitoring performance and planning training. While health-related factors present valid and reliable tests, the skill-related component should be studied in depth. An interesting test to evaluate the skill-related factors is the Harre circuit test (HTC); unfortunately, this test includes the somersault, an element not present in soccer. The aim of the present study is the validation of the Petrucci ability test (PAT), a variation of the HTC without the somersault for young soccer players. Children and adolescents (age range 10–13 years old) soccer players concluded the 20-m, the HTC and the PAT. To establ…