Maximum Ball Research Articles

Novel concept of recycling sludge and dust to BOF converter through dispersed in-situ phase induced by composite ball explosive reaction

Recycling of iron and steelmaking dusts is a key issue in environmental protection efforts and to ensure efficient utilization. In this investigation, we developed a novel recovery process that uses a dispersed in-situ phase induced by an explosive reaction of composite balls of iron and steelmaking dusts. We designed and prepared composite balls for this function using a laboratory model batch-type balling disc (at 12 r/min) and optimized the feeding modes in 180-t and 260-t basic oxygen furnace (BOF) converters. The results indicate that feeding composite balls into BOF converters is an effective novel technology for recovering iron and steelmaking dusts. The period after hot metal charging and prior to the oxygen-blowing process is the most reasonable time to feed composite balls. Composite ball treatment is not appropriate for steel production with sulfur requirements lower than 80 ppm. The maximum composite ball feeding amount is 40 kg/t and the iron yield rate is better than 95%. Compared with the conventional recycling process of sludge and dust, this novel technology is more convenient and efficient, saving up to 309 RMB per ton of steel. Further investigation of this novel recycling technology is merited.

Golf Ball Mark Severity and Recovery as Affected by Mowing Height, Rolling Frequency, Foot Traffic, and Moisture

Core Ideas Digital image analysis methods to evaluate putting green ball mark severity and recovery. Firmer surfaces from dry conditions or lightweight rolling increased maximum ball mark injury area. Rate of recovery was similar for all treatments, but increased wear increased time to 50% recovery. Demonstrates positive attributes of dispersing foot and equipment traffic throughout the green. Putting greens experience stress from golf balls striking the surface, maintenance equipment, and foot traffic. Improved creeping bentgrass (Agrostis stolonifera L.) cultivars, sand‐based root zones, and skilled superintendents maintain plant health while providing firmer conditions. Many researchers have studied effects of compaction and wear on putting greens, but few have determined the effect of these stresses on ball marks. The objective of this research was to evaluate ball mark severity and recovery of creeping bentgrass under different mowing heights (2.5, 3.2, and 4.0 mm), rolling frequencies (0, 3, or 6 d wk−1), and foot traffic using digital image analysis. Digital images of golf balls placed in the depression were used to calculate ball mark depth, and a cover analysis was conducted to model ball mark injury area using a one phase decay model to determine theoretical maximum injury, slope, and days to 50% recovery. Soil moisture content was positively correlated with ball mark depth, but common stresses rarely altered ball mark depth. The mean theoretical maximum ball mark injury was 377 mm2 greater for daily rolled treatments in 2010 compared to non‐rolled treatments. The slope of recovery rarely changed among treatments suggesting that theoretical maximum ball mark injury area has a greater effect on recovery. Lastly, combining the lowest mowing height or daily rolling and foot traffic slowed the time ball marks took to reach 50% recovery. This research demonstrates the effects common management practices and soil moisture have on the severity and recovery of ball marks during environmental stress.

Pore network extraction from pore space images of various porous media systems

AbstractPore network extraction, which is defined as the transformation from irregular pore space to a simplified network in the form of pores connected by throats, is significant to microstructure analysis and network modeling. A physically realistic pore network is not only a representation of the pore space in the sense of topology and morphology, but also a good tool for predicting transport properties accurately. We present a method to extract pore network by employing the centrally located medial axis to guide the construction of maximal‐balls‐like skeleton where the pores and throats are defined and parameterized. To validate our method, various rock samples including sand pack, sandstones, and carbonates were used to extract pore networks. The pore structures were compared quantitatively with the structures extracted by medial axis method or maximal ball method. The predicted absolute permeability and formation factor were verified against the theoretical solutions obtained by lattice Boltzmann method and finite volume method, respectively. The two‐phase flow was simulated through the networks extracted from homogeneous sandstones, and the generated relative permeability curves were compared with the data obtained from experimental method and other numerical models. The results show that the accuracy of our network is higher than that of other networks for predicting transport properties, so the presented method is more reliable for extracting physically realistic pore network.

Rubber Bat Effect of Maximal Ball Velocity in Table Tennis

This study is focused on the analysis of the characteristics and the effects on the ball speed of smash stroke using different types of bat rubber. The types of bat rubber researched in this study are inverted, pimpled out and hard rubber. The study samples are table tennis athletes of Table Tennis Student Activity Unit at UPI Bandung. The data of the study is obtained by conducting video analysis using motion software analysis system (Frame-DIAS IV). From the result of this study, speed data of each type of bat rubber is obtained. One-way ANOVA statistical test shows that there is no significant difference on the ball speed between inverted and hard rubber types. Another result shows that there are significant differences of ball speed which are produced by using inverted and hard rubber types. Some of the factors that influence these differences are pips orientation and thickness of each rubber. This test result shows that the selection of bat rubber types is vital in improving the quality of athlete performance.

Accurate and efficient maximal ball algorithm for pore network extraction

The maximal ball (MB) algorithm is a well established method for the morphological analysis of porous media. It extracts a network of pores and throats from volumetric data. This paper describes structural modifications to the algorithm, while the basic concepts are preserved. Substantial improvements to accuracy and efficiency are achieved as follows: First, all calculations are performed on a subvoxel accurate distance field, and no approximations to discretize balls are made. Second, data structures are simplified to keep memory usage low and improve algorithmic speed. Third, small and reasonable adjustments increase speed significantly. In volumes with high porosity, memory usage is improved compared to classic MB algorithms. Furthermore, processing is accelerated more than three times. Finally, the modified MB algorithm is verified by extracting several network properties from reference as well as real data sets. Runtimes are measured and compared to literature.

Absolutely classical spin states

We introduce the concept of "absolutely classical" spin states, in analogy to absolutely separable states of bi-partite quantum systems. Absolutely classical states are states that remain classical under any unitary transformation applied to them. We investigate the maximum ball of absolutely classical states centered on the fully mixed state that can be inscribed into the set of classical states, and derive a lower bound for its radius as function of the total spin quantum number. The result is compared to the case of absolutely separable states.

Differences in Throwing Kinematics among Youth Baseball Pitchers and Football Quarterbacks

The purpose of this study was to examine throwing kinematics of youth baseball pitchers and football quarterbacks. Eighteen pitchers (13.6 ± 1.3 years; 169.3 ± 8.0 cm; 62.3 ± 10.2 kg) and fifteen quarterbacks (14.3 ± 1.6 years; 174.9 ± 7.9 cm; 69.1 ± 14.0 kg) participated. Pitchers threw three fastballs to a catcher (46 ft; 14.0 m), while quarterbacks threw three 15 yard (13.7 m) passes to a receiver. Baseball pitchers displayed significantly greater trunk flexion at maximum external rotation (MER), ball release (BR) and maximum internal rotation (MIR) (p<0.001, p=0.003, p=0.007); as well as greater trunk rotation opposite throwing arm side at BR (p=0.048). Football quarterbacks displayed greater trunk rotation to throwing arm side at MER (p=0.002); shoulder horizontal adduction at FC (p=0.004); shoulder external rotation at BR (p=0.036); and elbow flexion at FC and MER (p=0.018, p=0.044). Trunk kinematic differences may be the result of pitchers throwing from a mound versus flat ground, just as upper extremity kinematic differences could be the result of the weight and shape of the ball.

四ローラ式ボール発射機の発射機構の開発

Ball shooting machine (pitching machine) is used for practicing ball sports, and it is widely prevalent. However, there are few pitching machines that can throw a ball with a gyro spin, such as a football or rifle bullet, in which the axis of the ball spins in the same direction as the ball travels. In this study, a new ball shooting machine, which can throw in the ball in a wide range of speeds and all pitch types (no, top, down, side and gyro spin balls) was invented by introducing a launch mechanism using four rollers (two launch and two gyro rollers). The shooting machine is able to arbitrarily change the rotational speed of the four rollers and the crossing angle of both gyro rollers. Shooting tests were conducted using the prototype shooting machine to confirm the ability of its performance. From the experiment results, the prototype machine had a maximum ball speed of 42.5 m/s, a spin rate of exceeding 5000 rpm, and a ball of any pitch type could also be shot. In addition, the position accuracy (shot accuracy) at the targeted fall position in the opponent's court was high because the gyro spin and other pitch types (no, top and side spins) were less than 140 mm and 40 mm (the diameter of one table tennis ball), respectively. The prototype machine had the necessary launching performance for table tennis practice of a college student level.

Role of Vertical Jumps and Anthropometric Variables in Maximal Kicking Ball Velocities in Elite Soccer Players.

Kicking is one of the most important skills in soccer and the ability to achieve ma ximal kicking velocity with both legs leads to an advantage for the soccer player. This study examined the relationship be tween kicking ball velocity with both legs using anthropometric measurements and vertical jumps (a squat jump (SJ); a countermovement jump without (CMJ) and with the arm swing (CMJA) and a reactive jump (RJ)). Anthropome tric measurements did not correlate with kicking ball velocity. Vertical jumps correlated significantly with kicking ball velocity using the dominant leg only (r = .47, r = .58, r = .44, r = .51, for SJ, CMJ, CMJA and RJ, respectively) . Maximal kicking velocity with the dominant leg was significantly higher than with the non-dominant leg (t = 18.0 4, p < 0.001). Our results suggest that vertical jumps may be an optimal test to assess neuromuscular skills involved in kicking at maximal speed. Lack of the relationship between vertical jumps and kicking velocity with the non-dominant leg may reflect a difficulty to exhibit the neuromuscular skills during dominant leg kicking.

Effect of Instructions Prioritizing Speed or Accuracy on Kinematics and Kicking Performance in Football Players

ABSTRACTThe authors' purpose was to investigate if there is a speed accuracy trade-off in soccer kicking by using instructions prioritizing velocity, accuracy, or both upon soccer kicking performance and kicking direction in experienced soccer players. In addition, kinematics were measured to investigate the eventual differences in performance. Thirteen experienced male footballers performed penalty kicks with different instructions prioritizing velocity, accuracy or both. Three-dimensional kinematics, together with maximal ball velocity and hitting accuracy, were measured on all kicks. The main findings were that when the main aim was accuracy, accuracy increased, while the velocity reduced, which supports Fitts' law (Fitts, 1954). In addition, kicking accuracy was higher when kicking to the contralateral side. The slower ball velocity was caused by lower segmental and in run velocities. These lower segmental velocities were mainly caused by the lower maximal knee extension and pelvis rotation during the accuracy priority kicks.

Effects of axial preloading displacement and off-sized balls and raceway error on mechanical performance of angular contact ball bearings

Taking the off-sized balls and raceway error into account, the effects of axial preloading displacement on the mechanical performance of angular contact ball bearings are investigated in this paper. Through the geometric analysis of the angular contact ball bearing and the force balance, the contact load-deformation expressions of ball-to-raceway, the expression of load zone and their relation to axial preloading displacement are derived. By numerical calculation for a concrete example, we found the influences of preloading on the loading zone and maximum ball load and found the influences of off-sized balls and raceway error on the minimum preloading displacement, ball load distribution, inner ring centre trajectory and inner ring vibration frequency. Some curves about these influences are obtained and discussed.

Width of the Gakhov class over the Dirichlet space is equal to 2

Gakhov class G is formed by the holomorphic and locally univalent functions in the unit disk with no more than unique critical point of the conformal radius. Let D be the classical Dirichlet space, and let P: f ↦ F = f″/f′. We prove that the radius of the maximal ball in P(G)∩D with the center at F = 0 is equal to 2.

Single- and two-phase flow simulation based on equivalent pore network extracted from micro-CT images of sandstone core.

Due to the intricate structure of porous rocks, relationships between porosity or saturation and petrophysical transport properties classically used for reservoir evaluation and recovery strategies are either very complex or nonexistent. Thus, the pore network model extracted from the natural porous media is emphasized as a breakthrough to predict the fluid transport properties in the complex micro pore structure. This paper presents a modified method of extracting the equivalent pore network model from the three-dimensional micro computed tomography images based on the maximum ball algorithm. The partition of pore and throat are improved to avoid tremendous memory usage when extracting the equivalent pore network model. The porosity calculated by the extracted pore network model agrees well with the original sandstone sample. Instead of the Poiseuille’s law used in the original work, the Lattice-Boltzmann method is employed to simulate the single- and two- phase flow in the extracted pore network. Good agreements are acquired on relative permeability saturation curves of the simulation against the experiment results.

Physical performance of elite and subelite Spanish female futsal players.

The aim of this study was to determine the parameters distinguishing top female futsal players from lower level players. Twenty-seven female futsal players participated in the study, composed of professional first division (elite; n = 15) players and semi-professional second division players (sub-elite; n = 14). Active and passive straight leg raise tests, isokinetic strength of the knee extensor and flexor muscles at 60° · s-1 angular velocity, squat and counter movement jumps, 30 m sprint, 30 m agility, repeated sprint ability test and maximum ball speed during shooting were measured. The elite players were more agile and kicked harder than sub-elite players in maximum ball speed during the shooting test (P ≤ 0.05). However, no significant differences between teams were observed in active and passive hamstring flexibility, jumping ability, repeated sprint ability test, 30 m sprint time, H/Q ratio and absolute and relative torque from 60° · s-1 angular velocity. Based on these findings we conclude that agility and maximum ball speed during shooting may be important determinant factors of Spanish female futsal actions and could distinguish ability at high-level games.

A microfluidic framework for studying relative permeability in coal

A significant unconventional energy resource is methane gas stored in shallow coal beds, known as coal seam gas. The flow and transport of fluid in coal beds occur in a well-developed system of natural fractures, called cleats. In this study, we developed an efficient workflow for the fabrication of microfluidic chips based on X-ray micro-Computed Tomography (micro-CT) images of coal. A dry and wet micro-CT imaging technique is utilized to image coal cleats that would be otherwise non-resolvable. The obtained image of the cleat network is then etched into silicon wafers and used to fabricate poly dimethyl siloxane (PDMS) microfluidic devices. Fluid transport and displacement efficiency are visualized and quantified in real time by injecting water with a flow rate of 1μlmin−1 into the fabricated cleat structure initially saturated with air. A microfluidic approach is used to measure the relative permeability of a realistic coal cleat system by monitoring the liquid recovery at recorded saturations after the breakthrough. Relative permeability curves show the cross and end point values for the water and gas flow, and predict a maximum relative permeability of 0.15 for the water phase. Understanding the relationship between coal cleat structure and the resulting relative permeability is crucial for the optimization of methane gas extraction and to reduce the environmental concerns of excess surface water production. Also, pore network modelling based on the Maximal Ball (MB) concept is applied to predict relative permeability curves numerically. Our experimental results are in good agreement with pore network modelling outcomes and provide consistent and smooth macro-scale relationships along with direct observation of the pore-scale physics. Therefore not only can the microfluidic approach be used as a validation tool for multiphase flow numerical models but it can also provide direct visualization of transport properties unique to coals. Overall, our developed system provides a better understanding of fluid flow behaviour in coal and presents novel relative permeability data for coal seam gas reservoirs under identical conditions and cleat sizes.

Permeability estimation of porous media by using an improved capillary bundle model based on micro-CT derived pore geometries

The purpose of this work is to develop a permeability estimation method for porous media. This method is based on an improved capillary bundle model by introducing some pore geometries. We firstly carried out micro-CT scans to extract the 3D digital model of porous media. Then we applied a maximum ball extraction method to the digital model to obtain the topological and geometrical pore parameters such as the pore radius, the throat radius and length and the average coordination number. We also applied a random walker method to calculate the tortuosity factors of porous media. We improved the capillary bundle model by introducing the pore geometries and tortuosity factors. Finally, we calculated the absolute permeabilities of four kinds of porous media formed of glass beads and compared the results with experiments and several other models to verify the improved model. We found that the calculated permeabilities using this improved capillary bundle model show better agreement with the measured permeabilities than the other methods.

Comparison of range of motion tests with throwing kinematics in elite team handball players

ABSTRACTThe aim of this study was to compare the active and passive range of motion (ROM) of the glenohumeral external rotation with the maximal external rotation and throwing performance during different throws with different wind-up techniques in elite team handball players. Twenty-two elite team handball players participated in the study in which the maximal ball release velocity and maximal external rotation during standing, with run-up and jump throws with two types of wind-ups were measured together with the maximal active and passive glenohumeral ROM of the external rotation, lying supine on a bench. Higher maximal external rotation was found during the throws with the whip-like wind-up in comparison to circular-like wind-up throws together with a lower external rotation during the active ROM test. No correlations were found between the ROM of the external rotation with the maximal ball release velocity and the maximal external rotation measured during the throws. It was concluded that ROM of the external rotation measured on the bench does not give any information about the maximal throwing performance or the external rotation angle during throwing and therefore cannot be used to identify potential fast throwers or injuries in elite team handball players.

The effect of fatigue and duration knowledge of exercise on kicking performance in soccer players

PurposeThe purpose of this study was to investigate the influence of fatigue upon kicking maximal ball velocity and the target-hitting accuracy of soccer players; and also to examine the effect of the knowledge of the exercise duration upon these 2 parameters. MethodsTwenty-four semi-professional soccer players participated in this study and performed maximal instep kicks before and after the implementation of an exercise protocol, either with or without knowledge of the duration of this protocol. ResultsA mixed model of analysis of variance showed that kicking maximal ball velocity was significantly affected (F(5, 85) = 11.6, p < 0.001, η2 = 0.39) but only after just 1 circuit of the fatigue protocol and then remained similar. Accuracy did not change during the protocol (F(5, 75) = 0.23, p = 0.76, η2 = 0.03) and knowing the duration of exercitation did not affect accuracy and velocity development (F(1, 23) ≤ 1.04, p ≥ 0.32, η2 ≤ 0.06). ConclusionThese findings demonstrated the potential negative effects of fatigue on kicking ball velocity in soccer but not in the kicking accuracy and that the effect of fatigue may not be progressive over time. Knowing or not knowing the duration of exercitation did not affect the results.

Does one size suit all? Dung pad size and ball production by Scarabaeus sacer (Coleoptera: Scarabaeidae: Scarabaeinae)

Large, ball rolling dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) are competitively dominant and can strongly influence community succession in dung pads. Ball production by Scarabaeus sacer Linnaeus was recorded in the Kizilirmak Delta on the Black Sea coast of Turkey by using artificial dung pads from 125 g to 2,000 g. Utilisation of pads across the 16-fold range of pad sizes demonstrated behavioural variation that may reduce intraspecies competition. Ball production was highly concentrated, with 66 balls (61%) produced from 8 pads of the 3 largest pad sizes, which may be related to chemical attraction between males and females. Ball size increased with increasing pad size (P < 0.05) but the number of balls produced per 100 g of dung decreased with increasing pad size (P < 0.01). Pad size for maximum ball production and ball size were 1,371 g and 1,260 g, respectively. The highest and lowest percentage of dung used for ball production was 43% of 125 g pads and 13% of 2,000 g pads, respectively. Ball production and time of day were significantly related (P < 0.01); S. sacer was almost exclusively nocturnal, with 59% of all balls produced between 21.00 and 22.00. This optimum period for ball production early in the night may be a compromise between reduced risk of predation and the increased energy costs of ball production as the temperature falls.

The influence of different exercise intensities on kicking accuracy and velocity in soccer players

PurposeThe aim of this study was to investigate the influence of different exercise intensities induced by a soccer specific protocol on kicking performance in soccer players. MethodsTwelve semi-professional male soccer players participated in this study and performed maximal instep kicks before and after the implementation of an exercise protocol to determine the influence of different intensities upon kicking ball velocity and the target-hitting accuracy. ResultsAnalysis of variance designs with repeated measures showed that maximal ball velocity was affected only after the most intense circuit (F(6, 66) = 2.3; p = 0.041; η2 = 0.18), while accuracy was not affected in the protocol (F(6, 66) = 0.19; p = 0.98; η2 = 0.02). Low and moderate intensities did not affect accuracy or kicking ball velocity. ConclusionThese findings suggest that kicking ball velocity is influenced by high-exercise intensities. Low and moderate exercise intensities do not affect the performance of the kick, and intensity does not influence accuracy. Otherwise, it is possible that other mechanisms (not only physiological) may influence players during the exercise.