Amplifying perceptual demands: How changes in the colour vests affect youth players performance during medium-sided games

This study explored how manipulating the colour of training vests affects footballers’ individual and collective performance during a Gk+6vs6+Gk medium-sided game. A total of 21 under-17 years old players were involved in three experimental conditions in a random order for a total of four days: i) CONTROL, two teams using two different colour vests; ii) SAME, both teams wearing blue vests; iii) MIXED, all 6 players per team wore different colour vests. Players’ positional data was used to compute time-motion and tactical-related variables, while video analysis was used to collect technical variables. Further, these variables were synchronized with spatiotemporal data allowing to capture ball-related actions in a horizontal 2D plan. All variables were analysed from the offensive and defensive perspective. From the offensive perspective, players performed more and further shots to goal during the CONTROL than in SAME and MIXED (small effects) conditions, with a decreased distance to the nearest defender (small effects). While defending, results revealed lower distance to the nearest teammate (small effects) in the CONTROL than in the SAME and MIXED conditions, and higher team longitudinal synchronization (small effects). In addition, the CONTROL showed in general lower values of team width while defending than in the other 2 conditions. Overall, coaches may use the CONTROL condition to emphasize offensive performance and defensive behaviour over the longitudinal direction with increased physical demands. In turn, coaches may use the manipulation of players vests to emphasize defensive performance, as players seem to behave more cohesively under such scenarios.

A study on the temperature profile of bifurcation tunnel fire under natural ventilation

This study simulated a series of bifurcation tunnel fire scenarios using the numerical code to investigate the temperature profile of bifurcation tunnel fire under natural ventilation. The bifurcation tunnel fire scenarios considered three bifurcation angles (30°, 45°, and 60°) and six heat release rates (HRRs) (5, 10, 15, 20, 25, and 30 MW). According to the simulation results, the temperature profile with various HRRs and bifurcation angles was described. Furthermore, the effects of bifurcation angles and HRRs on the maximum temperature under the bifurcation tunnel ceiling and the temperature decay along the longitudinal direction of the branch were investigated. According to the theoretical analysis, two prediction models were proposed. These models can predict a bifurcation tunnel fire’s maximum temperature and longitudinal temperature decay in the branch. The results of this study could be valuable for modelling a bifurcation tunnel fire and benefit the fire engineering design of bifurcation tunnels.

Numerical Performance of Energy Dissipation Slotted Plate for Bridge Unseating Prevention

Recently, the bridge unseating prevention devices are widely used in active seismic zones. These devices are stiffness dependant, velocity dependant and energy dissipation devices. The energy dissipation devices are designed to overcome the energy that transfers from bridge substructure to superstructure. However, the current devices are not controlled to function with different ground motion intensities and should be replaced after yielding. Therefore, this research introduced a slotted plate energy dissipation device with three parts, each part function in known deformation range. The slotted plate behavior has been evaluated numerically by finite element method. Displacement control and load control analysis has been done, and then the effect of steel grade is studied to predict the suitable steel properties for designing the plate. Moreover, the slotted plate behavior is applied in 3D bridge seismic analysis to assess the multi-level performance and the ability to overcome the seismic effect on the bridge in longitudinal direction. The results approved the capability of the plate to dissipate energy in multi-stage of deformation. The lower steel grade is suitable for low to moderate earthquake zone and the high grade can be used in severe ground motion areas. Furthermore, the bridge longitudinal behavior has enhanced with different steel grades of the slotted plate.

Establishment of the dependence of the strength indicator of the composite material of pressure hoses on the character of single damages

Experimental studies are presented and the dependence of the change in the strength of the material of a pressure head fire hose of type T with an inner diameter of 77 mm in the longitudinal direction is established, taking into account single damages. The work describes the plan of the experiment and carried out a number of field experiments to determine the effect of the length ld and the depth K damage on the strength F of the hose material, that is, obtaining the dependence F=f (ld, K). A mathematical method of experiment planning was used and a plan was drawn up for a complete multivariate experiment of type 2k with an acceptable model accuracy of 5 %. The limits of variation of the factors are set taking into account a priori information, experimental capabilities and on the basis of the results of preliminary search experiments. The dependence in the coded and natural values of the factors is obtained. The reliability of the relationship was checked using the Fisher test, the calculated value of which was 5.98, which confirms the adequacy of the described process with a probability of 95 %. Analyzing experimental studies of the dependence of the change in the strength of the hose material on the length and depth of damage, it can be said that the change in the strength of the hose almost linearly depends on the specified damage parameters. It is found that with increasing damage, the strength of the hose material significantly decreases. When varying the length factor and the greatest depth of damage, K=0.4 mm, the strength of the hose material decreases from 11.67 kN to 8.77 kN, and in percentage terms by 25 %. The results obtained can be used in practical units of emergency rescue teams, when diagnosing hidden damage in pressure head fire hoses in order to prevent their failure in case of fires

Effect of Anatomical Sites On the Mechanical Properties of Spinal Dura Subjected to Biaxial Stretching

The spinal cord is encased by spinal meninges called the pia, arachnoid, and dura maters. Among these membranes, the dura mater is the thick and outermost layer and is the toughest and strongest. Thus, mechanical failure of the dura mater can lead to spontaneous cerebrospinal fluid leaks or hypovolemia, resulting in a complication or exacerbation of unfavorable symptoms involved in a mild traumatic brain injury. To develop protective equipment that can help prevent such injuries, accurate characterization of the spinal dura mater is required, especially regarding the mechanical properties at different anatomical sites. In this study, we used an equiload biaxial tensile tester to investigate the mechanical properties of porcine meningeal dura mater along the whole length of the spine. The resultant strain of the dorsal side was greater than that of the ventral side (P < 0.01), while the circumferential direction was significantly stiffer than the longitudinal direction (P < 0.01) at lower strains regardless of the spinal level. We also found that the material stiffness progressively increased from the cervical level to the thoracolumbar level at lower strains, which implies that the dura mater inherently possesses structurally preferred features or functions because the neck requires sufficient flexibility for daily activities. Further, Young's modulus was significantly less on the dorsal side than on the ventral side at higher strains (P < 0.05), suggesting that the dorsal side is readily elongated by spinal flexion even within the range of physiological motion.

Interstellar Neutral He Parameters from Crossing Parameter Tubes with the Interstellar Mapping and Acceleration Probe Informed by 10 yr of Interstellar Boundary Explorer Observations

The Sun's motion through the interstellar medium leads to an interstellar neutral (ISN) wind through the heliosphere. Several ISN species, including He, moderately depleted by ionization are observed with pickup ions and directly imaged. Since 2009, analyzed Interstellar Boundary Explorer (IBEX) observations returned a precise 4D parameter tube associated with the bulk velocity vector and the temperature of ISN flow distribution. This 4D parameter tube is typically expressed in terms of the ISN speed, the inflow latitudinal direction, and the temperature as a function of the inflow longitudinal direction and the local flow Mach number. We have used IBEX observations and those from other spacecraft to reduce statistical parameter uncertainties: V ISN ∞ = 25.99 ± 0.18 km s−1, λ ISN ∞ = 75 .° 28 ± 0 .° 13 , β ISN ∞ = −5 .° 200 ± 0 .° 075 , and T ISN ∞ = 7496 ± 172 K. IBEX ISN viewing is restricted almost perpendicular to the Earth–Sun line, which limits observations in ecliptic longitude to ∼130° ± 30° and results in relatively small uncertainties across the IBEX parameter tube but large uncertainties along it. Operations over the last three years enabled the IBEX spin axis to drift to the maximum operational offset (7°) west of the Sun, helping to break the ISN parameter degeneracy by weakly crossing the IBEX parameter tubes: the range of possible inflow longitudes extends over the range λ ISN ∞ = 75 .° 28 − 2.21 + 2.27 and the corresponding range of other ISN parameters is V ISN ∞ = 25.99 − 1.76 + 1.86 km s−1, β ISN ∞ = −5 .° 200 − 0.085 + 0.093 , and T ISN ∞ = 7496 − 1528 + 1274 K. This enhances the full χ 2 analysis of ISN parameters through comparison with detailed models. The next-generation IBEX-Lo sensor on IMAP will be mounted on a pivot platform, enabling IMAP-Lo to follow the ISN flow over almost the entire spacecraft orbit around the Sun. A near-continuous set of 4D parameter tube orientations on IMAP will be observed for He and for O, Ne, and H that cross at varying angles to substantially reduce the ISN flow parameter uncertainties and mitigate systematic uncertainties (e.g., from ionization effects and the presence of secondary components) to derive the precise parameters of the primary and secondary local interstellar plasma flows.

Earthquake Resistance Optimization and Evaluation of Bridge Piers Structural Form and Dimensions Based on Demand to Capacity Ratio and Yielding Points of Force-Displacement

The evaluation of structural safety must be taken after each earthquake. The importance losses of life and materials carries the significance of the works in the field of earthquake engineering. The purpose of this study was to optimize and evaluate the earthquake resistance of bridge piers by adopting different cross-section forms and dimensions for bridge supports under earthquake action. Two methods of seismic design were used in the optimization and evaluation process. These methods were demand to capacity ratio (DCR) and yielding point. The results of demand to capacity ratio shown that the values of DCR for all piers forms models were increased when the dimension of pier cross section were increased and the values of DCR became less than 1.0, indicating that the increasing in dimensions leading to rise the capacity of bridge supports to carry the earthquake loads in transverse and longitudinal direction. Comparing with models, solid wall pier form had the lower value of DCR, indicating that solid wall piers were suitable in the design of bridge supports to resist the lateral loads of earthquake and it has enough stiffness and capacity under earthquake action. The results of performance points shown that the yielding points were increased when the dimensions of piers were increased for all piers form in transverse and longitudinal direction. The maximum values were appeared within support No. 1 and support No. 4. Solid wall form of pier had the higher values of yielding points, meaning that this type of piers form had higher seismic capacity and it will resist the earthquake action more than others piers form. This study recommended that to use third model for each pier form in the design of bridges structures to resist the earthquake load. Also this study was recommended to use solid wall piers as supports in construction of bridge structure within areas had earthquake action.

Pitting Corrosion in AA7075 Friction Stir Welds on Minor Additions of Silver

AA7075 is extensively used in aerospace, defense, automotive applications because of its high strength to weight ratio. Issues related to fusion welding and corrosion resistance are key problems associated with these alloys. Friction stir welding is an alternative welding technique that overcomes problems associated with fusion welding. In the present investigation, preliminary studies were done on pitting corrosion behavior of AA7075 friction stir welds by adding silver along the weld joint line. Silver paste was applied along the longitudinal direction of AA7075-T6 rolled plates of 6-mm thickness and cured at 130 °C for 30 seconds. Weld joints were prepared at two different tools rotational speeds, i.e., 750 rpm and 1000 rpm, while keeping other parameters fixed. Welded joints were cut as per the required sizes to study the hardness, microstructure, and pitting corrosion resistance in various regions. It was observed that the hardness was not much affected, but pitting corrosion resistance substantially improved by trace addition of silver. In the stir zone and the thermo-mechanically affected zone, onion ring type marks were observed. Grain refinement in the stirred zone (SZ) was higher at 750 rpm compared to 1000 rpm. The increased hardness in the welds was due to grain refinement. All the observed results were correlated with microstructural features as evidenced by optical microscopy.

The Interventricular Septum Is Biomechanically Distinct from the Ventricular Free Walls

The interventricular septum contributes to the pumping function of both ventricles. However, unlike the ventricular wall, its mechanical behavior remains largely unknown. To fill the knowledge gap, this study aims to characterize the biaxial and transmural variation of the mechanical properties of the septum and compare it to the free walls of the left and right ventricles (LV/RV). Fresh hearts were obtained from healthy, adult sheep. The septal wall was sliced along the mid-line into two septal sides and compared to the epicardial layers of the LV- and RV-free walls. Biaxial tensile mechanical tests and constitutive modeling were performed to obtain the passive mechanical properties of the LV- and RV-side of the septum and ventricular walls. We found that both sides of the septum were significantly softer than the respective ventricular walls, and that the septum presented significantly less collagen than the ventricular walls. At low strains, we observed the symmetric distribution of the fiber orientations and a similar anisotropic behavior between the LV-side and RV-side of the septum, with a stiffer material property in the longitudinal direction, rather than the circumferential direction. At high strains, both sides showed isotropic behavior. Both septal sides had similar intrinsic elasticity, as evidenced by experimental data and constitutive modeling. These new findings offer important knowledge of the biomechanics of the septum wall, which may deepen the understanding of heart physiology.

Characteristics of Overburden Failure and Fracture Evolution in Shallow Buried Working Face with Large Mining Height

In order to solve the issues of uncertain overburden failure height and water loss at the Daliuta coal mine, the collapse characteristics of overburden and the development height of water-conducting fractured zone were studied by using physical modeling, FLAC 3D numerical simulation, and field observation, which were used to verify each other. In order to quantitatively analyze the distribution characteristics of fracture rate of overlying rock mass in goaf, the overburden collapse image was binarized. The results showed that: (1) the failure characteristics of overburden in goaf obtained by the three research methods were roughly consistent, and the reliability of the results was high. The overburden failure height of No. 5−2 coal with large mining height was 137.32–153 m, which was 20.8–23.2 times the mining height. (2) The repeated mining of No. 5−2 coal intensified the further failure of the disturbed rock mass in the No. 2−2 coal goaf. (3) In the horizontal direction of the goaf, the fracture rate of rock mass was distributed in the shape of “saddle”. In the longitudinal direction of the goaf, the rock mass fracture rate decreased in a logarithmic function with the increase of the height from the mining coal seam. Overall, the conclusions are of engineering significance for accurately adopting water resources protection mining technology and reducing mine water inrush disasters.