Actual Ball Research Articles

Peanut & Fifi Have a Ball by Randall de Sève (review)

Reviewed by: Peanut & Fifi Have a Ball by Randall de Sève Deborah Stevenson, Editor de Sève, Randall Peanut & Fifi Have a Ball; illus. by Paul Schmid. Dial, 2013[ 32p] ISBN 978-0-8037-3578-1 $15.99 Reviewed from galleys Ad 4–7 yrs Despite the title, it’s initially only Peanut who has an actual ball, and the little girl is delighted with her new toy (“It was bright blue. And it was special”). Her sister, pigtailed Fifi, yearns for a piece of the action, but grabbing for the ball, begging, and suggesting shared games don’t melt Peanut’s resolve to hang on to her toy. Finally Fifi gets wise and presents an attraction all her own: a seal named Bob, and a planned trip around the world for Bob, Fifi, Peanut, and the ball. The back-and-forth rhythm between Peanut and Fifi (one resisting, the other pushing) is brisk, [End Page 460] and their exchanges are funny as Fifi grows ever more creative in her attempts to make Peanut share her treasure. The story spirals into confusion, however, with the arrival of Bob the seal, and a fakeout ending stops the momentum in its tracks. Additionally, Peanut’s sudden yearning to play with Fifi is a bit puzzling, since it’s never made clear why this pretend game is any more inviting than the others. Schmidt’s art makes the sisters into an adorable pair: strongly graphic digital images involving smooth, thick black outlines and a few slightly smoky planes of color contrast with the ivory backgrounds, and the girls’ poses differentiate them as clearly as their clothing and hair. Kids know both the desire to grab and the desire to withhold, so they’ll relate to both the sisters and have similar tales to tell of their own sharing dramas. Copyright © 2013 The Board of Trustees of the University of Illinois

インタラクティブなプロジェクションマッピングの実現

We propose an interactive projection mapping that provides ultra-realistic effects by mixing realistic and diverse visual effects with the users interactions. To achieve high quality and real-time generation of the visual effects, we create pre-rendered movies with layered architecture including the target itself, its background, and additional effects. Based on the user's interactions estimated with a depth camera, the movies are superimposed for various visual patterns in real time. These movies are projected on a real space by using common 3D projection mapping techniques, and it feels like the resultant projection is part of the real world. In this research, we implemented a wall breaking game by throwing a virtual and an actual ball at a real wall.

Ceramic Balls Machining by Centerless Grinding Using a Surface Grinder

This paper proposes a novel method for machining ceramic balls by centerless grinding technique performed on a surface grinder. In this method, a compact unit consisting mainly of an ultrasonic shoe, an ultrasonic regulator, a relay controller, a blade, a stopper and their respective holders is installed on the worktable of a surface grinder to conduct centerless grinding operations of ceramic balls. The ultrasonic shoe and regulator are produced by bonding a piezoelectric ceramic device (PZT) onto a metal elastic body, and when two phases of AC voltage are applied to the PZT an elliptic motion occurs on their end-faces which can be used to control the ball rotational motion in the radial and axial direction of the wheel, respectively. The function of the relay controller is to regulate the alternating current “on” and “off” time which is applied on the regulator for achieving the whole spherical surface grinding process. A grinding unit was actually constructed and it was experimentally confirmed that the ball rotational speed can be controlled well by the shoe or regulator. Grinding tests were subsequently carried out and the obtained results indicated that the constructed grinding unit performed well on actual ball centerless grinding operations.

Manipulating informational constraints shapes movement reorganization in interceptive actions

Movement organization of cricket batters' actions was analyzed under three distinct experimental task constraints: a representative condition of a practice context in which the batters batted against a "live" bowler, a ball projection machine, and a near life-size video simulation of a bowler. Results showed that each distinct set of task constraints led to significant variations in the patterns of movement control. Removal of advanced information sources from a bowler's actions when the batters faced the ball projection machine caused significant delays in movement initiation, resulting in reduced peak bat swing velocities and a reduction in the quality of bat-ball contact, when compared with batting against a "live" bowler. When responding to a two-dimensional video simulation, batters were able to use information from the bowlers' action, enabling fidelity of initial behavioral responses consistent with the task of batting against a "live" bowler. However, without interceptive task requirements or actual ball flight information, significant variations in downswing initiation timing and peak bat velocities were demonstrated. Findings stress the need for representative experimental and learning designs in fast ball sports for developing performers.

Evaluations of Whisker Growth and Fatigue Reliability of Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.05Ce Solder Ball Grid Array Packages

Sn-Ag-Cu solders doped with rare-earth elements were reported to exhibit beneficial mechanical properties; however, rapid whisker growth could be induced. In order to retain the advantageous effects of rare-earth doping without causing the formation of tin whiskers, a Sn-3Ag-0.5Cu-0.05Ce alloy was suggested. In the present study, metallographic observations indicate that whisker growth is indeed prevented in this alloy. However, tensile tests with the bulk materials show that the ultimate tensile strength and Young’s modulus of this Sn-3Ag-0.5Cu-0.05Ce alloy are only slightly higher than those of undoped Sn-3Ag-0.5Cu. Further reliability tests with actual ball grid array packages indicate that the Sn-3Ag-0.5Cu-0.05Ce solder joints have fatigue lives similar to those of undoped Sn-3Ag-0.5Cu specimens regardless of the various surface finishes, such as electroless nickel/immersion gold (ENIG), immersion tin (ImSn), and organic solderability preservatives (OSP). The results suggest that, although lowering the content of rare-earth elements in solders can inhibit the occurrence of rapid whisker growth, it cannot ensure the improvement of the tensile properties of bulk solders and the fatigue reliability of solder joints in actual packages.

BASE WAVELET SELECTION FOR BEARING VIBRATION SIGNAL ANALYSIS

A critical issue to ensuring the effectiveness of wavelet transform in machine condition monitoring and health diagnosis is the choice of the most suited base wavelet for signal decomposition and feature extraction. This paper addresses this issue by introducing a quantitative measure to select an appropriate base wavelet for analyzing vibration signals measured on rotary mechanical systems. Specifically, the measure based on energy-to-Shannon entropy ratio has been investigated. Both the simulated Gaussian-modulated sinusoidal signal and an actual ball bearing vibration signal have been used to evaluate the effectiveness of the developed measure on base wavelet selection. Experimental results demonstrate that the wavelet selected using the developed measure is better suited than other wavelets in diagnosing structural defects in the bearing. The method developed provides systematic guidance in wavelet selection.

Ball detection from broadcast soccer videos using static and dynamic features

In this paper, we propose an approach for detecting ball in broadcast soccer videos. We use hybrid techniques for identifying ball in medium and long shots. Candidate ball positions are first extracted using features based on shape and size. For medium shots, a ball is identified by filtering the candidates with the help of motion information. In long shots, after motion based filtering of the non-ball candidates, a directed weighted graph is constructed for the remaining ball candidates. Each node in the graph represents a candidate and each edge links candidates in a frame with the candidates in next two consecutive frames. Finally, dynamic programming is applied to find the longest path of the graph, which gives the actual ball trajectory. Experiments with several soccer sequences show that the proposed approach is very efficient.

Mirror Approach for the Patients with Unilateral Spatial Neglect and Mirror Agnosia

Mirror Agnosia is characterized by searching for the mirror image and showing difficulty of modifying behavior even after the object is presented in real space (Ramachandran, 1997). The possibility of therapeutic intervention of using a mirror for unilateral spatial neglect (USN) with mirror agnosia was suggested, but few researches on mirror agnosia and mirror approach for USN have been reported. The purpose of this study was to confirm the influence of the use of a mirror for USN with mirror agnosia. Two patients with left hemiparesis with USN were evaluated. We propped a mirror on the right side of the patient parallel to the sagittal plane and presented a ball apart from it. We asked the patient to grasp it with looking into the mirror. If they could not reach the actual ball, we shifted the ball closer to the mirror and tried again. When two patients grasped the ball, we asked them to reach it repeatedly. Albert test was executed before and after the session. Both patients could not reach the ball initially, but were able to grasp it when it was closer to the mirror. They showed an improvement in the Albert test after this approach. This method might be useful therapeutic intervention for USN with mirror agnosia.

Ball mill simulation in wet grinding using a tumbling mill and its correlation to grinding rate

A method for simulating the motion of balls in tumbling ball mill under wet condition is investigated. The simulation method is based on the three-dimensional discrete element method (DEM) and takes into account the effects of the presence of suspension, i.e., drag force and buoyancy. The impact energy on balls' collision, which enables us to provide useful information for predicting the grinding rate, was calculated from the simulation work. Actual ball motion in the suspension in the mill was observed through a transparent mill lid made of acrylic acid resin at different solid concentrations and the suspension was made of water with powder samples such as gibbsite, limestone and talc. Grinding tests of the gibbsite sample using two laboratory tumbling ball mills made of stainless steel and using alumina with balls made of steel, alumina and glass were conducted and the grinding rate was determined by measuring the 50% particle size of the product. The specific impact energy calculated from the simulation work correlates well with the grinding rate of the sample, irrespective of the grinding conditions, so that the energy is the key factor controlling the grinding phenomena in wet milling.

A Damage Mechanics-Based Fatigue Life Prediction Model for Solder Joints

A thermomechanical fatigue life prediction model based on the theory of damage mechanics is presented. The damage evolution, corresponding to the material degradation under cyclic thermomechanical loading, is quantified thermodynamic framework. The damage, as an internal state variable, is coupled with unified viscoplastic constitutive model to characterize the response of solder alloys. The damage-coupled viscoplastic model with kinematic and isotropic hardening is implemented in ABAQUS finite element package to simulate the cyclic softening behavior of solder joints. Several computational simulations of uniaxial monotonic tensile and cyclic shear tests are conducted to validate the model with experimental results. The behavior of an actual ball grid array (BGA) package under thermal fatigue loading is also simulated and compared with experimental results.

2453 ボールねじの玉の運動挙動計測に関する研究

In order to make clear the high speed operating limit or the seizure resistance limit of the ball screw, it is necessary to grasp the actual ball motion in the ball screw, and the development of measuring method of the ball motion has been expected. In the present paper, using a magnetized ball and hall elements arranged on the nut and the return tube, the authors tried to measure the ball motion in the ball screw (ZFT4020) rotating at the shaft speed in the range of 120∿950rpm. The results were compared with the analytical results calculated based on the kinematic geometry of ball screw mechanisms. When the magnetic circuit attached to the measuring system, it became possible to observe the changes in the hall voltage, and the measured values such as the rotational speed of ball revolution and ball rotation almost agreed with the analytical values.

Experimental Damage Mechanics of Microelectronics Solder Joints under Concurrent Vibration and Thermal Loading

Concurrent vibration and thermal loading is commonly encountered in the service life of electronic packaging, such as in automotive, airplane, military and mobile electronic devices. Solder joint reliability has been a critical issue of the overall design of microelectronic devices. However, the contribution of vibration to thermal fatigue life of solder joints has rarely been investigated. Presently, vibration is taken as a loading case that only causes elastic material response. Literature is scarce on vibration plasticity and vibration caused fatigue for micron scale structures. The standard practice in the industry is to use Miner’s rule to calculate combined environment fatigue life. This study shows that using Miner’s rule for fatigue life under combined loading is inaccurate for micron scale solder joints. There are a number of constitutive models to simulate thermomechanical behavior of solder joints, yet few of these, if any, models are verified by test data obtained from actual microelectronics solder joints. The authors see the need of such tests for the purpose of better understanding of material behavior of micron scale solder joints under thermal and vibration loading and providing a solid basis for more accurate material modeling and fatigue life prediction. This paper reports observations from a series of concurrent thermal cycling and vibration tests on 63Sn/37Pb solder joints of an actual ball grid array (BGA) package. Moiré interferometry (MI) is used to measure the inelastic deformation field of solder joints with submicron resolution. A large capacity Super AGREE thermal chamber and a high acceleration electrodynamic shaker are assembled together to perform the concurrent cycling. The cyclic plasticity of solder joints and microstructure evolution are discussed and related to fatigue life prediction. The results obtained in this study agree with findings reported in the literature from micron scale material testing where it has been shown that “smaller is stronger.”

Measurement of Three Dimensional Ball Motion in Angular Contact Ball Bearing. Measurement with Hall Elements Arranged on Fixed Oblique Coordinates.

In order to make clear the causes of heat generation, friction loss and tribo-failures such as smearing in high speed ball bearings, it is indispensable to grasp the contact conditions between ball and races or between ball and separator, and the development of measuring method of the actual ball motion has been desired. In the present paper, using hall elements arranged on the fixed oblique coordinates, the authors measured the behavior of the three dimensional ball motion in the angular contact ball bearing 7209 A under various running conditions. The results were compared with those of the conventional method with a moving orthogonal coordinate system and it was confirmed that the measured values such as the rotational speed of the ball and the separator almost agree by two different methods. It was recognized that the propositional method is practical use and useful.

Experimental and Numerical Verification of Fatigue Life Estimation for Solder Bumps

Fatigue life estimation of solder bumps is one of the most critical technologies for the development of ball grid array packages. In this study, mechanical fatigue tests were carried out using Sn63-Pb37 solder bump specimens. The cracks were initiated along the entire circumference in the vicinity of the interface. The fatigue life estimation of the solder bumps was performed based on the elastic-creep finite element method (FEM) analysis. It was clear that the strain concentration region coincides with the crack initiation site. The estimation result for the crack initiation was in good agreement with the experimental results. The results reconfirmed that it was desirable to employ the equivalent creep strain range occurring at a distance of 50 μm from the singularity point. The life ratio, which provides the quantitative correlation between the crack initiation and the ultimate fracture, was determined from the experimental results. The number of cycles to the fatal failure can be roughly estimated by multiplying the analytical estimation results for the crack initiation by this life ratio. This simple estimation of fatal failure may well be of practical use in actual ball grid array (BGA) design for thermal load conditions.

ANALYSIS AND EXPERIMENTS OF BALL DEFORMATION FOR ULTRA-FINE-PITCH WIRE BONDING

This paper discusses ultra-fine-pitch bonding on a 50-μm bond-pad-pitch platform using ϕ23-μm gold wire. A technique for the bonding process and the bonding tool design was developed using the finite element method. It was possible to simulate and analyze the variation in the plastic deformation of ball bond when it was subjected to different loading conditions and capillary configurations. The analysis indicated that the critical bonding tool dimensions and bonding process parameters such as free air ball consistency and bonding force played critical roles in reliable bond deformation. A wire diameter of 23 μm with a capillary hole size of 28–30 μm would be robust for a mass production environment. A diameter of 32–33 μm is recommended as the average size of the free air balls for 50-μm bond-pad-pitch bonding using the ϕ23-μm gold wire. Based on the results obtained from the analysis, special bonding tool configurations were designed and fabricated. Actual bonding was performed to further validate the simulation results with experimental bonding responses. Comparison of the simulation results with the experimental data indicated that the actual ball size (38.5 μm) was approximately 3% larger than that (37.4 μm) obtained from the simulation.

A Study of Hall Element Method for Ball Motion in a Ball Bearing.

Determining the actual ball motion in a ball bearing is important for tribological analysis, such as estimating oil film thickness, heat generation, etc. Generally, the method used for this purpose is to measure the magnetic field change induced by the rotation of a magnetized ball. In earlier studies, a search coil was used to detect the ball motion, by means of which three-dimensional ball motion was not available. Recently, Kawakita developed the Hall element method, in which Hall elements were arranged so as to detect three-dimensional ball motion. In his method, in spite of the fact that the radial direction components of the magnetic flux were measured through contact points, a fixed cartesian coordinate system was used regardless of the contact condition. In this study, the direction of the contact points was taken into consideration to calculate the Hall voltage and to estimate the angular velocity error due to a fixed cartesian coordinate system. The resultsshow that the direction of the contact points considerably affects the angular velocity calculation.

再現熱履歴試験法による金ワイヤーボールボンディングの熱影響部機械的特性の検討

A method of thermal history simulation has been developed to obtain a better understanding of mechanical properties of the grain growth region (heat-affected zone-HAZ) of gold bonding wires.The simulator is degigned to simulate the HAZ microstructures over a several inches length of the wire, which is necessary for mechanical testing. It has been found that grain size of the coarse grained HAZ cal be satisfactorily reproduced on the simulated thermal history condition. The breaking load obtained in this condition found to exhibit good agreement with the pull load of actual ball bonded wires.Using the simulator, changes in mechanical properties with varying simulated thermal cycles are briefly studied. With increase of grain size, strength of simulated HAZ decreased. On the other hand, elongation first increased with decreasing the strength but decreased sharply to a very low level. The intensive decrease of the elongation occurs because deformation does not occur uniformely but concentrated on heavily coarsened grains.

The actual motion and the contact angle of a ball in a deep groove ball-bearing II: Shaft speed Ni = 100 rev min −1; thrust load Fa = 600, 800 and 1000 N

In the previous paper, one of the authors reported the ball motion in a deep groove ball-bearing under thrust load conditions F a = 0, 200 and 400 N. On the basis of the experimental data the actual ball behaviour and the contact angle obtained by a graphic method were discussed. As the thrust load increased the ball behaviour became complicated. To follow the previous experiments, the ball motion under thrust load conditions F a = 600, 800 and 1000 N was investigated. In this paper the periodic variation in ball motion, the actual contact angle of the ball or the ball rotation axis and their fluctuation etc. are discussed.

Periodic ball behaviour in a deep groove ball-bearing under conditions of low radial load and low shaft speed

The actual ball behaviour during one cage revolution was investigated by using a new measuring method for three-dimensional ball motion. From the experimental results, periodic ball motion with slip was recognized and according to the differences in ball behaviour distinct peripheral regions of the bearing could be discerned.

The performance of a new measuring method for three-dimensional ball motion in a ball-bearing

Recently, a new method for measuring ball motions three dimensionally was developed by one of the present authors and its principle was reported in the previous paper. Before its practical applications were examined, the calibration tests were carried out and the outputs obtained by this new method were compared with the values expected theoretically. By compensating for some undesirable effects, it was confirmed that the outputs were sufficient to analyse actual ball motions within an experimental error of 5%. In order to demonstrate its usefulness, an example of experimental results obtained by this new technique is shown.