Types Of Balls Research Articles

Investigations on Flexural Strength and Stiffness of Hollow Slabs

A new type of hollow slab making use of plastic air balls has been developed, which can effectively reduce the amount of concrete and self weight of concrete structures. In this study, flexural and free vibration tests were carried out to investigate flexural behaviour, including the flexural stiffness, cracking, strength, and ductility. Six test specimens were examined: two conventional RC slabs; two hollow slabs; and two partially precast concrete slabs. The test parameters also included two different types of plastic balls. The test results showed that the hollow slabs yield a satisfactory flexural behaviour (i.e., crack pattern, and flexural strength) which is similar to that of conventional concrete solid slabs up to the ultimate state. It was also found that the current design provisions for concrete solid slabs are applicable to hollow slabs, without significant modification, for the evaluation of flexural strength and initial stiffness essential to the serviceability check.

Development Of Exercise Programs For The Elderly Based On Training Methods For Athletes, And Their Posture-Improving Effects

With the purpose of reducing fall-related accidents in the elderly, we not only developed, based on the opinions of community residents, original exercise programs, but also revised existing programs designed for athletes, and examined their effects on the physical strength of the elderly and posture improvement in an upright position. Between November and March 2006, we held a fall prevention school 15 times in Sadowara Town, Miyazaki City, Miyazaki Prefecture. Participants were elderly people aged sixty-five years or older, including 14 members from Group A (Group Vigor) and five candidates for leaders (19 in total) (74.32 ± 6.15) as well as 16 members from Group B (Group Energy) (80.65 ± 6.38); they were divided into two groups according to the time taken to stand up from a sitting position: Groups A (Group Vigor: about three seconds) and B (Group Energy: about five seconds). 1. Full body stretch (ten types) 2. Originally-developed fall prevention exercise (Two kinds of Exercise for Healthy Elderly and for Frail Elderly) 3. Walking training (Light Walking) 1) Walking on heels, toes, with long strides, and while being conscious of the thighs and waist (two types of walking training for each of eleven exercise levels) 2) Training using equipment - Ladder Drills (nineteen types) and low hurdles (three types for each of three exercise levels) 4. Muscle training (using five types of ceramic band and three types of small ball) 5. Aerobic exercise (Step Up for Your Health) We filmed the participants to record their postures from the front and back (frontal plane), using a digital video camera, before and after exercise sessions. We used image analysis software, Dartfish (Dartfish Co., Ltd), to examine the positions of the following body parts and the angles between them: the head, trunk, lower limbs, shoulders, hips, and the area between the top of the head and heels. We assessed the physical fitness of the elderly before and after the training sessions. In Group A, improvements were observed for all eleven items, and significant differences were shown regarding seven items. In Group B, improvements were observed for seven items, and marked differences were shown regarding two items. The results demonstrated an overall increase in the physical function of the elderly in both groups. However, smaller improvements were made in Group B, compared to A, particularly in lower limb function. This is probably because most elderly in Group B participated in programs that did not require vigorous exercise, including a light exercise session. We revised existing programs, which were designed to train athletes, for the elderly, and implemented them along with our originally-developed exercise programs. Significant improvements were observed for five of the six assessment items in the examination on the frontal plane, and the level of exercise performance was increased in most elderly people. The exercise programs were designed to improve the sense of equilibrium in the elderly by training the muscles on the both sides of their bodies evenly, and they proved to be effective. These training programs offer considerable benefits to the elderly, including an increase in physical function, posture improvement, and pain relief.

An in-situ examination of the timing of information pick-up for interception by cricket batsmen of different skill levels

Objectives Cricket batting is performed under demanding constraints, which requires rapid and accurate decision making for successful achievement of the skill goal. To understand how batsmen negotiate these constraints, the capability of highly skilled and low skilled cricket batsmen to utilise visual information prior to and during sections of ball flight to strike balls delivered by fast bowlers was examined. Method Six highly skilled and six low skilled batsmen faced different types of balls delivered by three fast bowlers. Batsmen wore vision occlusion spectacles and were required to strike delivered balls, while their vision of the bowler's delivery action and ball flight was selectively occluded. Three vision conditions were randomly designed that included temporal occlusion at: (i) a point prior to ball release (providing only advance information), (ii) a point prior to ball bounce (providing advance and ball flight information) and (iii) no occlusion (where all advance, ball flight and bounce information were visible). Foot movements made forward or backward were assessed as a measure of ball length judgement, while the quality of bat–ball contact was assessed as a measure of interception. Results Results demonstrated the superior capability of highly skilled batsmen to utilise information prior to ball release to judge short ball length. Expert batsmen were better able to utilise ball flight information prior to and post-bounce to attain a superior number of bat–ball contacts. Conclusions Findings demonstrate that the mechanism of experts to deal with task constraints when attempting to intercept a delivered ball is their capability to pick-up visual information to judge ball landing position.

Noncommutative ball maps

In this paper, we analyze problems involving matrix variables for which we use a noncommutative algebra setting. To be more specific, we use a class of functions (called NC analytic functions) defined by power series in noncommuting variables and evaluate these functions on sets of matrices of all dimensions; we call such situations dimension-free. These types of functions have recently been used in the study of dimension-free linear system engineering problems. In this paper we characterize NC analytic maps that send dimension-free matrix balls to dimension-free matrix balls and carry the boundary to the boundary; such maps we call “NC ball maps”. We find that up to normalization, an NC ball map is the direct sum of the identity map with an NC analytic map of the ball into the ball. That is, “NC ball maps” are very simple, in contrast to the classical result of D'Angelo on such analytic maps in C . Another mathematically natural class of maps carries a variant of the noncommutative distinguished boundary to the boundary, but on these our results are limited. We shall be interested in several types of noncommutative balls, conventional ones, but also balls defined by constraints called Linear Matrix Inequalities (LMI). What we do here is a small piece of the bigger puzzle of understanding how LMIs behave with respect to noncommutative change of variables.

An urn approach to generalized extreme shock models

Abstract We introduce a new intuitive approach to generalized extreme shock models (GESM) using urn processes. This allows us to indirectly model the moving risky threshold of generalized extreme shock models introduced in [Gut, A., Husler, J., 2005. Realistic variation of shock models. Statistics & Probability Letters 74, 187–204]. The basic idea is to link the colors of the balls in the urn with the levels of risk a system can face, and model the evolution of the process using a triangular reinforcement matrix. Using the analytic approach proposed in [Flajolet, P., Gabarro, J., Pekari, H., 2005. Analytic urns. Annals of Probability 33, 1200–1233], we explicitly derive probabilities, moments and limit laws for different types of balls, that is for the distinct levels of risk. Our model can be also considered as a way to incorporate GESM in a Bayesian framework. In fact, urn processes are an important tool of Bayesian Nonparametrics, in the way they allow us to compute posterior distributions without an explicit knowledge of priors.

Development of a fast-solving numerical model for the structural analysis of cricket balls

In cricket, high speed impacts occur between the cricket ball, the bat, players and their protective equipment. Improved understanding of impact dynamics has the potential to significantly improve the development of cricket equipment and also contribute to improving the player safety and performance. In particular, the development of high performance cricket balls with enhanced structural properties (e.g. improved durability) would benefit greatly from such insight. This article presents the development of two fast‐solving numerical models as well as a universal FE model for the structural analysis of cricket balls. The models were developed using experimental data obtained from drop tests and high speed impact tests. These models predict impact characteristics with very little computing cost. A universal Finite Element (FE) ball model has also been developed using ABAQUS, which combines an FE model template and a material parameter selection tool based on an Artificial Neural Network (ANN) model. This approach allows for rapid model development while producing accurate results at different impact speeds. Comparison of results revealed good agreement between simulation and experimental results. The developed FE‐ANN model can be used to predict the impact behaviour of different types of cricket balls under various dynamic conditions. This flexibility represents an advantage that can be utilized by sports equipment developers to rapidly develop different cricket ball models needed for inclusion in larger simulations involving impact of a cricket ball with other objects. This represents an invaluable tool for facilitating design, analysis and structural optimisation of cricket‐related sport equipment.

A maxiset approach of a Gaussian noise model

We consider the problem of estimating an unknown function f in a Gaussian noise setting under the global $\mathbb{L}^{p}$ risk. The particularity of the model considered is that it utilizes a secondary function v which complicates the estimate significantly. While varying the assumptions on this function, we investigate the minimax rate of convergence over two types of Besov balls. One is defined as usual and the other belongs to the family of weighted spaces. Adopting the maxiset approach, we show that a natural hard thresholding procedure attained the minimax rate of convergence within a logarithmic factor over such weighted Besov balls.

How do World-Class Cricket Batsmen Anticipate a Bowler's Intention?

Four experiments are reported that examine the ability of cricket batsmen of different skill levels to pick up advance information to anticipate the type and length of balls bowled by swing and spin bowlers. The information available upon which to make the predictive judgements was manipulated through a combination of temporal occlusion of the display and selective occlusion or presentation of putative anticipatory cues. In addition to a capability to pick up advance information from the same cues used by intermediate and low-skilled players, highly skilled players demonstrated the additional, unique capability to pick up advance information from some specific early cues (especially bowling hand and arm cues) to which the less skilled players were not attuned. The acquisition of expert perceptual-motor skill appears to involve not only refinement of information extraction but also progression to the use of earlier, kinematically relevant sources of information.

An urn model of the development of L/M cone ratios in human and macaque retinas

A model of the development of L/M cone ratios in the Old World primate retina is presented. It is supposed that during gestation, the cone cycles randomly between states in which it transcribes either L or M opsin. The current state determines and increases the probability that it will transcribe the same opsin in future cycles. These assumptions are sufficient to formalize the process as a Markov chain that can be modeled as an urn containing two types of balls, L and M. Drawing one ball results in the increase of its species and the decrease of the other. Over the long run, the urn will become populated with a single type of ball. This state corresponds to the photoreceptor adopting a fixed identity for its lifetime. We investigate the effect of the number of states and the rule that regulates the advantage of transition toward one cone type or another on the relation between fetal and adult L/M cone ratios. In the range of 100 to 1000 states, small variations of the initial L/M ratio or the transition advantage can each generate large changes in the final L/M ratio, in qualitative accord with the variation seen in human adult retinas. The time course to attain stable L/M ratios also varies with these parameters. If it is believed that the cycling follows a circadian rhythm, then final L/M cone ratios would be expected to stabilize shortly after birth in the human being and the macaque.

Firmness evaluation of melon using its vibration characteristic and finite element analysis

Analysis of the vibration responses of a fruit has been suggested as a non-destructive measure of its elastic properties (firmness). In this study, 'Huang gua' melons were excited using three types of balls (wooden, steel and rubber) and the vibration was detected by an accelerometer. The modulus of elasticity of the inner, middle and outer portions of melon flesh were determined using flat plate compression of cylindrical samples. The Instron device was used to measure the static elastic modulus and the Finite Element (FE) technique was used to determine the optimum location of the excitation on fruits. Four types of mode shapes were found: torsional or flexural mode shape, first-type of longitudinal mode shape, second-type of longitudinal mode shape and breathing mode shape. The results from FM simulation were in good agreement with experimental results and there was good correlation between the fruit firmness and its resonant frequency.

Construction of the Finite-Element Models of Golf Balls and Simulations of Their Collisions

The purpose of this study is to construct a finite-element (FE) model of golf balls with hyperelasticity and viscoelasticity and to devise a method for construction of FE ball models by investigating the relationship between the material properties and the behaviour of the golf ball during and after impact. As for the material model of the FE ball model, the Mooney-Rivlin model and the three-element viscoelastic model were used. In the FE analysis (FEA), normal and oblique impacts with a rigid body were simulated with these models. The impact load, deformation of the ball, rebound velocity, angle, and spin rate were investigated, and their effects on the behaviour of the ball were analysed by varying the individual material constants which make up the ball models. Then, a method for the construction of an FE ball model was proposed, based on these relationships. Impact experiments were also conducted to obtain the dynamic properties of the golf ball. The solutions of the FEA of the ball model, as constructed by the proposed method, closely matched with the experimental results, and the method was verified by applying the process to other types of golf balls.

Clinicopathologic and immunohistochemical characteristics of fungal sinusitis.

Fungal sinusitis (FS) is a common disease in Taiwan. Histologically, there are 4 types of FS, i.e., acute invasive, chronic invasive, fungal ball and allergic FS. Among the various fungal pathogens, Aspergillus is the most important. This study analyzed results of antibody staining against Aspergillus species on tissue sections of FS to identify fungal elements and evaluated the role of Aspergillus in different types of FS. We retrospectively reviewed 140 cases with a pathologic diagnosis of FS in our hospital from 1995 to 2003. The clinical information, hematoxylin and eosin staining, and Gomori methenamine silver staining results for each patient were analyzed. Patients were reclassified into 4 categories of FS according to histologic presentation. The causative fungi were divided into Aspergillus and non-Aspergillus groups according to the results of immunoreactivity against anti-Aspergillus antibody. Fungal ball was diagnosed in 126 patients (90%), 66.6% of whom were females. Only 3 patients died of underlying disease not related to the fungal infection. Immunohistochemical staining demonstrated Aspergillus infection in 108 out of 119 patients (90.7%). Thirteen patients were categorized as having acute invasive FS due to the presence of vascular and stromal invasion. All but 1 patient had underlying diseases associated with immunocompromised status and 11 out of the 13 patients died of sepsis. Immunohistochemical study revealed 5 of these patients were infected with Aspergillus species, and the other 8 were infected with non-Aspergillus fungi. Allergic FS was diagnosed in 1 patient based on the presence of allergic mucin containing numerous eosinophils and few fungal hyphae. The fungal elements were negative for anti-Aspergillus antibody. None of the patients had chronic invasive FS. Fungal ball and acute invasive FS were the 2 most common types of FS in this study from Taiwan. However, both allergic FS and chronic invasive FS are rare. Immunohistochemical staining was useful in identifying specific species of fungus in tissue sections. Aspergillus accounted for 90.7% of fungal ball infections and 38.4% of acute invasive FS infections. It is important to differentiate among the categories of FS because the clinical course, etiology, treatment and prognosis are quite different.

Firmness evaluation of melon using its vibration characteristic and finite element analysis

The "Huang gua" melons were measured for their physical properties including firmness and static elastic modulus. The vibrational characteristics of fruits and vegetables are governed by their elastic modulus (firmness), mass, and geometry. Therefore, it is possible to evaluate firmness of fruits and vegetables based on their vibrational characteristics. Analysis of the vibration responses of a fruit is suggested for measuring elastic properties (Firmness) non-destructively. The impulse response method is often used to measure firmness of fruits. The fruit was excited using three types of balls (wooden, steel and rubber) and the vibration is detected by an accelerometer. The Instron device was used to measure the static elastic modulus of the inner, middle and outer portions of melon flesh. Finite element (FE) technique was used to determine the optimum excitation location of the chosen measurement sensor and to analyze the mode shape fruits. Four types of mode shapes (torsional or flexural mode shape, first-type, second-type spherical mode and breathing mode shape) were found. Finite element simulation results agreed well with experimental results. Correlation between the firmness and resonant frequency (r2=0.91) and between the resonant frequency and stiffness factor (r2=0.74) existed. The optimum location and suitable direction for excitation and response measurement on the fruit were suggested.

Analytic urns

This article describes a purely analytic approach to urn models of the generalized or extended Pólya–Eggenberger type, in the case of two types of balls and constant “balance,” that is, constant row sum. The treatment starts from a quasilinear first-order partial differential equation associated with a combinatorial renormalization of the model and bases itself on elementary conformal mapping arguments coupled with singularity analysis techniques. Probabilistic consequences in the case of “subtractive” urns are new representations for the probability distribution of the urn’s composition at any time n, structural information on the shape of moments of all orders, estimates of the speed of convergence to the Gaussian limit and an explicit determination of the associated large deviation function. In the general case, analytic solutions involve Abelian integrals over the Fermat curve xh+yh=1. Several urn models, including a classical one associated with balanced trees (2–3 trees and fringe-balanced search trees) and related to a previous study of Panholzer and Prodinger, as well as all urns of balance 1 or 2 and a sporadic urn of balance 3, are shown to admit of explicit representations in terms of Weierstraß elliptic functions: these elliptic models appear precisely to correspond to regular tessellations of the Euclidean plane.

Asymptotics in randomized urn models

This paper studies a very general urn model stimulated by designs in clinical trials, where the number of balls of different types added to the urn at trial n depends on a random outcome directed by the composition at trials 1,2,…,n−1. Patient treatments are allocated according to types of balls. We establish the strong consistency and asymptotic normality for both the urn composition and the patient allocation under general assumptions on random generating matrices which determine how balls are added to the urn. Also we obtain explicit forms of the asymptotic variance–covariance matrices of both the urn composition and the patient allocation. The conditions on the nonhomogeneity of generating matrices are mild and widely satisfied in applications. Several applications are also discussed.

Lubricant oils additivated with polymers in EHD contacts: Part 2. Tests using a four‐ball machine

AbstractA mineral oil of low viscosity was additivated with different concentrations of low‐density polyethylene. The wear behaviour of the additivated samples and the base oil was evaluated using a four‐ball wear tester at constant speed and variable load. Steel and ceramic (silicon nitride) were chosen for the balls. The scuffing resistance of the ceramic balls was higher than that of the steel balls. No scuffing appeared in the case of an upper steel ball in contact with lower ceramic balls. As far as the minimum wear‐scar diameter on the lower balls was concerned, an optimum concentration of polymer added to the base oil was found from the experimental data, for both types of ball. For the systems investigated, the optimum concentration was about 1.0% polyethylene.

Random-allocation and urn models

We review some urn and random-allocation models, mostly using probability generating function (PGF) methods. We begin by formulating a basic problem which can be thought of as either an urn or a random-allocation model; a PGF solution to it is outlined. When the compartments in the latter model are no longer homogeneous, the multivariate PGF can still be derived, though the algebra becomes cumbersome. Some results are given for the case where there are two types of compartment and for the case where there are two types of ball. Some comments are offered on the Frobenius–Harper property of PGFs.

Random-allocation and urn models

We review some urn and random-allocation models, mostly using probability generating function (PGF) methods. We begin by formulating a basic problem which can be thought of as either an urn or a random-allocation model; a PGF solution to it is outlined. When the compartments in the latter model are no longer homogeneous, the multivariate PGF can still be derived, though the algebra becomes cumbersome. Some results are given for the case where there are two types of compartment and for the case where there are two types of ball. Some comments are offered on the Frobenius–Harper property of PGFs.

326 ゴルフボール用樹脂およびゴムの衝撃圧縮特性(OS 材料・構造の動的特性(5))

In order to understand fully the restitution performance of two different types of golf balls, high strain-rate compressive characteristics of resin and rubbers used for 2-piece and 3-piece balls were evaluated using the conventional split Hopkinson bar. An aluminum split Hopkinson bar was used to measure the impact compressive stress-strain relations for the resin and rubbers with low acoustic impedance. Compressive stress-strain data at high strain rates are presented and compared with those at quasi-static strain rates obtained on an Instron testing machine. It is shown that the resin exhibits hisher strain rate sensitivity than does the rubbers.

General urn models with several types of balls and Gaussian limiting fields

AbstractWe study a system of m urns, where several types of balls are thrown, and an additive valuation is assigned to each urn depending on its state. Examples are the join models studied in a database context, and some models with two types of balls. The object of our investigation is the evolution of the valuation with time, when a ball is thrown at each time unit. By means of a generating function approach we show the weak convergence of the valuation process to a Gaussian field. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 2004