End Zone Research Articles

Longitudinal Shear of a Composite Material in Which the Binder and Inclusions are Weakened by Cohesive Cracks

Background: An elastic medium is considered that is weakened by a doubly periodic system of round holes filled with washers made of a homogeneous elastic material and has cohesive cracks, the surface of which is uniformly covered with a cylindrical non-metallic film. The binder (medium) is weakened by two doubly periodic systems of rectilinear cohesive cracks, directed parallel to the abscissa and ordinate axes, and the length of the crack and their dimensions are not the same (different). General concepts are constructed that describe a class of problems with doubly periodic stress distribution outside circular holes and cohesive cracks under longitudinal shear. The analysis of the limit equilibrium of cracks within the framework of the end zone model is performed on the basis of a nonlocal failure criterion with a force condition for the advancement of the crack tip and a deformation condition for determining the advance of the edge of the end zone of the crack. In solving the problem, the main resolving equations are obtained in the form of infinite algebraic systems and three nonlinear singular integro-differential equations. The equations obtained in each approximation were solved by the Gaussian method with the choice of the main element for different order values depending on the radius of the holes. Calculations were carried out to determine the forces in the connections of the end zones and the ultimate loads causing crack growth. Objective: In the considered problem, the problem of longitudinal slip weakened by cracks parallel to the x axis in the filling medium with two pairs of two periodic cracks weakened by 2 periodic circular holes is considered. In the problem, the boundary problem along the contour of the circular holes is determined, and at the same time, the surface problem is established for the cracks parallel to the x and y axes. The solution of the problem is sought analytically, and taking into account the boundary condition, a system of linear algebraic equations for circular holes and 3 singular integral equations for cracks is obtained. Theoretical Framework: The problem is solved analytically, as the system of linear algebraic equations obtained for circular holes and the system of linear integral equations are jointly solved, and the stress intensity factor at the end of the cracks is determined. Method: The problem was solved using "Kolosova Muskhalashvili" functions and "Collondia's method of solving singular integral equations". Results and Discussion: The main essence of the considered issue is that the stress intensity factor at the end of the cracks is determined according to Fig. 1. Research Implications: For the first time, the stress intensity factor was calculated in composite materials with two pairs of biperiodic cracks of different lengths weakened by biperiodic round holes. Originality/Value: For the first time, the stress intensity coefficient was determined in composite materials with two periodic two pairs of cohesive cracks.

Análisis de los remates del Qatar Major Premier Padel 2023

The aim was to analyze the characteristics of the finalist shots, through the validated OASP (Observation instrument for the analysis of the smash in padel), instrument, according to their effectiveness in men´s professional padel. For this, 880 finalist smashes corresponding to 20 male matches of the Premier Padel Major tournament played in Qatar during the 2023 season were analyzed, carrying out a descriptive and inferential analysis. The results indicate that 73.18% of the final smashes are winners, while only 26.82% of the final smashes are errors. In addition, the winning finalist smashes are made from the zones close to the net (zones 3 (RTC=4.9) and 4 (RTC=5.3)) and to a lesser extent from the middle zones of the court (zones 2 (RTC=2.6). and 5 (RTC=2.6)) and are usually flat (RTC=8.4), parallel (RTC=5.4) and ending X3 (RTC=6.2) or X4 (RTC=5.0). While the finalist smashes that end in error are usually made from the end zones of the court (zones 1 (RTC=8.9) and 6 (RTC=6.7)) and are usually slice (RTC=11.9), crossed (RTC=5.4) and that end in their own court (they stay in the net; RTC=3.9) or opposite court (the ball hits the glass or the fence directly; RTC=3.5). Thus, padel players should know these results to perform effective shots in real competition situations to promote success in the match.

Anticipatory coarticulation of the Spanish alveolar fricative /s/ in adults with apraxia versus dysarthria

This acoustic study compares anticipatory coarticulation characteristics of the Spanish alveolar sibilant fricative /s/ when in utterance-initial position followed by a vowel in adults with dysarthria and apraxia of speech. Three groups of participants (28 individuals with no speech disorder, 20 with dysarthria, and 8 with apraxia of speech) produced 12 monosyllabic words that included the five vowel sounds of central-peninsular Spanish. The acoustic measurements compared within and between groups were frequency of the spectral intensity peak (FreqMid) in different zones of fricative execution, magnitude of the change in frequency of the spectral intensity peak (ΔFreq) in the end zone compared to the average of the initial and middle zones, first three spectral moments, and the difference in spectral center of gravity between the middle and end zones (DiffM-E CoG). Several of these measures were able to differentiate between dysarthric and healthy speech, especially when /s/ was followed by an unrounded vowel, and the same occurred for apraxia, but this time when the adjacent vowel was rounded. While both disorders showed similar spectral patterns, the two motor speech disorders differed in terms of the measures FreqMid and DiffM-E CoG. Possible explanations for these differences are here discussed within the framework of motor control models.

Risks in the current groundwater regulation approach in the Beetaloo region, Northern Territory, Australia

ABSTRACT Plans are underway to greatly increase rates of groundwater extraction from the Northern Territory’s Cambrian Limestone Aquifer (CLA), particularly above the Beetaloo sub-basin, to allow expansion of shale gas and agricultural industries. We analyse current groundwater regulations in the NT, and the state of knowledge regarding key aspects of the region’s hydrogeology and values sustained by groundwater. We find that the current rules governing the administration of groundwater licencing in areas without a Water Allocation Plan (WAP) – the Top End and Arid Zone rules – are poorly suited to protect ecological, Indigenous socio-cultural and other water use values. These rules (as currently applied) allow the depletion of substantial groundwater storage in areas that fall within the ‘arid zone’ (as defined in NT policy). Such depletion risks the reduction or loss of groundwater flows to ecosystems and stygofauna habitat and reduced throughflow of groundwater between different regions, within the highly connected CLA system. This may disrupt water flows that sustain local livelihoods and those that are integral to Indigenous peoples’ beliefs and cultural practices. The new WAP that applies over much of the Beetaloo sub-basin (Georgina-Wiso WAP) is also deficient in key areas. It has failed to comply with national water policy, in that no substantive steps have been taken to understand Indigenous cultural and ecological values sustained by groundwater prior to setting an Estimated Sustainable Yield. A more precautionary, inclusive approach to determining groundwater regulations would involve a) setting of conservative water extraction limits combined with trigger levels for ecosystem protection and b) co-management in partnership with Aboriginal peoples, with both consultation and decision-making processes that recognise their inherent rights and interests in water. This will be critical to avoiding long-term environmental and socio-cultural harm from over-extraction of groundwater.

Influence of Magnetic Screen Material on Leakage Magnetic Field and Losses in the End Zone of Turbine Generator Based on Double Iterative Method

The overheating problem of the end components affects the safe and stable operation of the turbine generator. The magnetic screen layer can improve effectively the distribution of leakage magnetic field in the end zone. Taking the nonlinearity of the core material, rotor rotation, and the complex structure into consideration, mathematical model of nonlinear transient electromagnetic field is established in the end zone of 1407MVA turbine generator. The influence of different materials of magnetic screen layer on the end leakage magnetic field is studied based on double iterative method. Current density distribution of screen plate and finger plate are determined. The losses of the end components are obtained under the different materials of magnetic screen layer, which are used as heat sources in the three-dimensional fluid-solid coupled heat transfer model. Complex fluid flow and temperature distribution of the end components are obtained in the end zone of the turbine generator. The calculation results are verified by experiments.

Effect of boundary element detailing on the seismic performance of reinforced concrete masonry shear walls

Laboratory tests demonstrated that reinforced masonry shear walls (RMSWs) can provide sufficient strength and ductility to be considered an efficient seismic force resisting system (SFRS) for mid-rise buildings. The ductility and overall seismic performance of shear walls were increased by providing confinement to the end zones of the walls to form boundary elements (BEs)., which enhanced the ultimate masonry compressive strain and curvature ductility of the walls. Regular stretcher blocks are commonly used in the construction of masonry boundary elements; however, they impose some constraints due to their geometrical characteristics. This study investigated the construction and testing of three half scale specimens of reinforced masonry shear walls with boundary elements (RMSWs+BEs) that were characterized by flexural dominance under reversed cyclic moment and lateral loading. In the lower story panel of a 12-story RMSW building, these walls constitute the plastic hinge zone, which is represented by a plastic hinge wall. In this study, C-shaped masonry units were used instead of stretcher units to construct BEs with different sizes and vertical reinforcement ratios. The findings of this work revealed that employing C-shaped masonry units to construct the BEs was effective in overcoming the construction limits imposed by stretcher units. Additionally, the results of this study demonstrated that when RMSWs+BEs are subjected to quasi-static reversed cyclic loading, they are capable of providing a high level of ductility with minimal loss of strength.

Analysis of leakage flux, losses, and temperature in large synchronous generator end zone under the multi‐layer screen thickness based on novel iterative method

AbstractThe multi‐layer screen is the key component in the large synchronous generator end zone. The leakage flux, losses, and temperature of end components are significantly affected by the thickness of multi‐layer screen in the synchronous generator. To investigate the influence of multi‐layer screen thickness on the end leakage flux, losses, and temperature in the synchronous generator end zone, 1407MVA nuclear power synchronous generator is studied. Three‐dimensional transient electromagnetic field model of synchronous generator end zone is established. Three‐dimensional transient electromagnetic field in the end zone of 1407MVA synchronous generator with the multi‐layer screen is calculated based on the novel iterative method. The flux density of end components is compared and studied in the end zone under the variation of multi‐layer screen thickness. Influence of the different thicknesses of multi‐layer screen on the losses of the shield plate, screen, finger plate, and stator end core is researched. The losses of end components obtained from 3D end electromagnetic field calculation are applied to the end zone as the heat source in the three‐dimensional fluid and thermal coupled field. The temperature distribution of the end components is determined. The accuracy of the calculated results is validated by the experimental values.

Strategic use of ultra-high-performance concrete and carbon fiber reinforced polymer reinforcement for end zone design of prestressed girders

The design of end zones to prevent severe cracking is a key requirement toward durable prestressed girders. Traditional approaches employ large amounts of steel reinforcement to attain this requirement, which may result in steel congestion. This paper investigates a hybrid girder concept that uses Ultra-High-Performance Concrete (UHPC) and Carbon Fiber Reinforced Polymer (CFRP) bars to enhance crack control and long-term durability in the end zones of prestressed girders. The objectives of this study are to quantify the UHPC zone lengths needed to restrain end zone cracks, eliminate or reduce the required amount of steel reinforcement, and investigate its replacement with CFRP bars. A finite element modeling (FEM) approach was developed for this purpose and its fidelity was validated with experimental data. The FEM results showed that UHPC zones with lengths below or equal to half of the girder depth can significantly reduce end zone cracking. CFRP bars can be added in the UHPC zones as a conservative measure to crack control, to ensure the long-term corrosion resistance of the girders.

Experimental study on the seismic performance of non-compact H-section steel frames

In order to assess the seismic performance of steel frame systems with non-compact members, cyclic tests were conducted on three full-scale frames incorporating beams and columns of varying plate width-thickness ratios. The seismic performance of these specimens, including failure modes, hysteresis curves, load-bearing capacities, ductility, and energy dissipation capabilities was thoroughly examined. The test results indicated that the dominating failure mode observed in all the specimens was the local buckling deformation occurring at the beam end and column bottom zones, and the occurrence of the first concentrated local failure would lead to the ultimate load-bearing state of the frames. Moreover, the occurrence sequence and development degree of the buckling deformations had a significant effect on the seismic performance of the frames. These findings suggest that reasonable combinations of beam and column sections should be carefully considered to retain rational balance between load-bearing capacity, ductility and energy dissipation capabilities for non-compact frames.

Analysis of transient electromagnetic force on end windings of 300 Mvar synchronous condenser during dynamic reactive power compensation process

The uneven distribution of renewable energy supply and demand promotes the development of high-voltage direct current transmission. As the critical reactive power compensation equipment for high voltage direct current transmission, the synchronous condenser must have a strong overload capability. One of the critical factors limiting the improvement of its overload capacity is the reliability of the end winding, which depends on the magnitude of the force on end windings during dynamic large reactive power output. Therefore, this paper proposes a coupling model of transient electromagnetic force for the high voltage direct current transmission system and the end zone of the synchronous condenser. The transient response of the synchronous condenser under different fault degrees is calculated, analyzed, and verified by experiments. Based on the current response of the synchronous condenser, the transient electromagnetic force on end windings is calculated. The distribution law of the force on end windings of the synchronous condenser under different degrees of dynamic reactive power compensation process is revealed. Further, the regions on end windings with larger force during strong overload are indicated. The optimizing fixation scheme for end windings is proposed according to the distribution features of the force, which can improve the operational reliability of end windings.

Analysis of the spatial distribution of the serve and the type of serve-return in elite table tennis. Sex differences.

Serve and return of the serve are among the most critical technical-tactical factors influencing performance in table tennis (TT). The present study aimed to analyse sex differences in the spatial distribution of serve and serve-return in elite TT players. A total of 48 elite TT players (men: n = 24; women: n = 24) participated in the investigation. A total of 24 matches were recorded and examined, analysing 1,177 plays and 5,319 strokes in the men's competition and 950 games and 5,097 strokes in the women's competition. Technical actions were analysed using an observation tool validated by two expert TT coach with a high level of agreement (K > 0.80). Men distributed their serves over zones 1 and 2 of the table, while women more frequently selected zone 5 (p < 0.05). In men, 30.1% of the serves were near the net, 63.6% in the middle zone of the table and 6.2% in the end zone of the table, while in women, these values were 10.9%, 67.2%, and 21.8%, respectively. As for the technique of the serve-return depending on the zone of the service, in men the action of the cut from zone 1 and 2 predominated, while in women this technique was more frequent from zone 5 (p < 0.05). On the other hand, the serve-return with the flip technique in zone 1, 3 and 4 was more frequent in men (p < 0.05). As for the return of the serve with the topspin technique, there were differences in zone 3, being more frequent in men (p < 0.05). Finally, the serve return with cut and defensive serve-return techniques in zones 3, 4, 5, and 6 were more frequent in women (p < 0.05). There are differences between sexes in service and return of serve actions during a match in elite players.

Влияние режима потребления реактивной мощности на техническое состояние турбогенератора Т3ФП-110-2МУ3

The necessity of turbogenerators operation in the reactive power consumption mode is determined by the shortage of compensating devices in the network. Recently, accidents associated with generators long-term operation at low levels of excitation have become more frequent, which is a prerequisite for the consumption of reactive power by the generator. The purpose of this research is to assess the effect of the reactive power consumption mode on the technical condition of the T3FP-110-2MU3 turbogenerator. The source of information about the technical condition of the turbogenerator is the data obtained from the operating and repair documentation, electrical and thermal tests protocols, technical reports with the results of comprehensive diagnostic examinations of the turbogenerator. The cores of T3F series generators have been examined. No gaps between the pressure fingers and the surface of the edge packages have ever been detected during examinations, which indicates the absence of significant curvature of the extreme core packages. During the study of temperature by T3FP-110-2MU3 thermal resistance converters, it is found out that with an increase of reactive power consumption, the temperature of the windings and the active steel of the stator core of the turbo generator decreases and it does not exceed the upper warning settings in the mode of reactive power output, the opposite dependence is visible. It is established that the influence of the reactive power consumption mode on the technical condition of the T3FP-110-2MU3 when operating in steady-state modes within the factory PQ-diagram is minimal. In the stator core of the turbogenerator under consideration, high resistance of the teeth of the extreme packages to operational loads has been achieved, due to significant improvements in the design and manufacturing technology of the end zones. From the point of view of practical significance, T3F series turbogenerators are allowed to be used for reactive power consumption. As a further direction of research, it is planned to consider the operation of turbogenerator in maneuverable modes with the transition from the issuance of reactive power to its consumption and vice versa.

Notational Analysis on Goal Scoring and Comparison in Two of the Most Important Soccer Leagues: Spanish La Liga and English Premier League

Goals scored are the most important performance indicator and may be a good tool to analyze game style predominance within different leagues. The aims of this study are to describe how goals are scored in the two major soccer leagues in the season of 2020/21, and to compare both leagues to watch possible differences in the offensive sequences that lead to goal-scoring. The aims of this study were: to evaluate goal scoring trends among two main soccer leagues and to compare the two leagues. A total of 1409 goals were observed using notational analysis. The total results show a dominance of positional play/fast attack (n = 38%), followed by set pieces as the second means to score (n = 32%) with corner kicks having a great impact (n = 36%) within set pieces goals. The most goals were scored by short possessions (n = 50%) with short passes number (n = 57%), with the recovery of the ball in the offensive third (n = 47%) and the huge dominance of finalization in central areas inside the box (n = 78%). Spanish La Liga scored more by positional play/fast attack, with most of the possessions starting in the medium third and using more the “central wing goal area” and “between wings left in the box” end zones when compared with English Premier League. The latter has more goals from counterattacks and corner kicks with very long possessions. Most of the possessions start in the offensive third and more goals are scored in “central wing between penalty and goal area” in comparison with Spanish La Liga. Coaches must be aware of the trends of the game and of the differences across leagues to prepare themselves when working in different countries to each specific characteristic.

Analytical study of splitting resistance of precast prestressed ultra-high performance concrete girder end zones

Ultra-high performance concrete (UHPC) has gained popularity gradually because of its superior mechanical properties, including high compressive and tensile strengths, and exceptional durability. Many researchers have explored the possibility of using long, precast prestressed UHPC girders in buildings and bridges. To do so, the girders generally require a large number of prestressing strands, which causes concern about potential cracking in the end zones at prestress release. Currently, there are no specifications or codes on end zone designs for precast prestressed UHPC girders in the United States. Thus, this paper presents an analytical study that explores highly prestressed UHPC girders’ end zone behavior. Finite element analyses were conducted to analyze the end zones of a series of UHPC girders, including one 889-mm-deep and two 813-mm-deep I-girders, and the analysis results were validated with test data. Additional finite element models were developed for other girders with heights of 1,829 mm and 2,743 mm using various reinforcement details. Bursting stress variations in the reinforcement and UHPC were reported based upon the analytical and test results. An equation for splitting resistance attributable to the reinforcement and UHPC was proposed for highly prestressed girders.

ASYMMETRIC DISTRIBUTION OF PIPE ADAPTER FOR CARS

It is shown that the responsible parts of each vehicle are tubular connecting lines, which are included into the braking, fuel and exhaust systems of cars. These pipelines have high requirements for reliability, vibration resistance, strength, corrosion resistance and durability. These parts are used as expanders and connecting elements when transitioning from a smaller pipeline diameter to a larger one. The paper presents studies of the operation of distributing the end of the pipe blank with a rigid punch. In the process of distribution, the acting tangential stresses lead to a decrease in the thickness of the edge section of the workpiece. This entails a decrease in the reliability of this area during operation and a decrease in its maintainability and corrosion resistance. Also, to ensure the tightness of pipe connections, threads are cut or these areas are welded together in the specified areas of the workpieces. Therefore, an important design feature of tubular diffusers is the same wall thickness throughout the cross-section of the semi-finished product. To solve the problem of increasing the thickness of the semi-finished product after distribution, an asymmetric tool is proposed. The task was solved in the finite-element formulation using a special complex of 3D modeling Simulia Abaqus – student edition. The pipe blank was represented as a deformable solid, while the punch was modeled as a completely rigid discrete solid. The construction method for both models is "revolution". According to finite element modeling, dispensing with a conical asymmetric tool has advantages from the point of view of increasing the thickness of the end zone of the pipe bell. The thickness of the part increases by 22.5% from a thickness of 1.77 mm for the classic version of distribution, to 1.82 mm – for distribution with an asymmetric tool. To reduce the thinning of the wall after distributing the pipe blank, it is recommended to use an asymmetric punch. To obtain a symmetrical pipe socket, it is necessary to make two dispensing transitions with a 180° rotation of the blank or punch

Getting to the End Zone: Scoring a Touchdown Through Collaborative Learning in Online Sports PR Instruction

Getting to the End Zone: Scoring a Touchdown Through Collaborative Learning in Online Sports PR Instruction

Elastic-plastic problem for a perforated plate under transversal shear

The problem of solving the problem of the transverse shear of a plate along the edges of the holes and weakened by a two-periodic system of rectilinear through cracks with plastic end zones, collinear to the abscissa and ordinate axes of unequal length, is considered. General representations of solutions are constructed that describe a class of problems with a doubly periodic distribution of moments outside circular holes and straight-line cracks with end zones of plastic deformations. Satisfying the boundary conditions, the solution of the problem of the plate shear theory is reduced to two infinite systems of algebraic equations and two singular integral equations. Then each singular integral equation is reduced to a finite system of linear algebraic equations.

An overpressure-time history model of methane-air explosion in tunnel-shape space

This study investigated methane-air explosion in tunnel-shape space and developed an overpressure-time history model based on numerical results. The findings revealed that for the progressively vented gas explosion with movable steel obstacles in a 20 m long tunnel, the inner peak overpressure increased as the activation pressure of the tunnel top cover got higher but remained below 6 bar. However, as the activation pressure increased to 8 bar or higher, the peak inner overpressure remained unchanged. As the segment cover panel became wider, the peak pressure was almost unchanged, but the pressure duration and impulse declined significantly. The peak pressure and impulse increased as the tunnel length vary from 10 to 30 m. With fixed tunnel length, higher blast pressure but lower impulse was observed as the inner obstacles were closer or the activation pressure of obstacles was higher. It is also found that a local enlarged space in the tunnel enhanced the peak pressure significantly. An overpressure time history model for the tunnel with fixed top cover and enlarged end zone was established. The model considered activation pressure of vent cover, area and length of vent opening, methane concentration, number and blockage ratio of fixed obstacles was developed to calculate the overpressure and corresponding time at characteristic points of the pressure-history curve. The cubic Hermite interpolation algorithm and a specially tuned formula consisting of the power and exponential function were used to interpolate pressure values between characteristic points. The proposed model can predict both the peak pressure and the overpressure time history with acceptable accuracy.

Transverse shear of an isotropic elastic medium in the case when the binder and inclusions are weakened by crack initiation

An elastic medium is considered, weakened by a doubly periodic system of round holes, filled with absolutely rigid inclusions, soldered along the bypass and has a crack initiation. The medium (binder) is weakened by two periodic systems of rectilinear crack initiation directed collinear to the abscissa and ordinate axes, and their sizes are not the same. General representations are constructed that describe a class of problems with a doubly periodic stress distribution outside circular holes and cracks under transverse shear. The analysis of the limiting equilibrium of cracks in the framework of the end zone model is carried out on the basis of a nonlocal fracture criterion with a force condition for the propagation of the crack tip and a deformation condition for determining the advancement of the edge of the end zone of the crack. Basic resolving equations are obtained in the form of infinite algebraic systems and three nonlinear singular integro-differential equations. The equations in each approximation were solved by the Gaussian method with the choice of the principal element for different values of the order of M, depending on the radius of the holes. Calculations were carried out to determine the forces in the connections of the end zones and the ultimate loads causing the growth of cracks.

INVESTIGATION OF THE STRESS-STRAIN STATE OF RODS WITH TRANSVERSE CRACKS UNG UNDER UNEVEN HEATING

The problem of fracture mechanics for a strip (rod) weakened by a straight-through crack with end zones when the strip is under the influence of an uneven temperature field is considered. The determination of the forces in the connections between the sides is reduced to the solution of a singular integro-differential equation.